Methods and Devices for Transmitting/Obtaining Identification Information and Positioning by Visible Light Signal
The present invention discloses methods and devices for transmitting/obtaining identification information and positioning by visible light signal. The method for transmitting identification information of a light source by visible light signal, the method comprising: modulating, on the basis of the identification information to be transmitted, a driving signal of the light source to obtain a modulated driving signal for driving the light source to emit visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points; and emitting the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points on the basis of the modulated driving signal, so as to transmit identification information corresponding to the varied numbers of bright or dark stripes shown in one or more images obtained from the visible light signal at one or more time points, which numbers are corresponding to the varied frequencies.
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The present invention generally relates to the field of visible light communication, and particularly relates to methods and devices for transmitting/obtaining identification information and positioning by visible light signal.
BACKGROUNDCurrently, global positioning system (GPS) is the most widely used positioning system. However, GPS is difficult to achieve a good positioning accuracy in an indoor environment and practically cannot be used for indoor positioning applications, since the signal of GPS is blocked by the roof and walls of buildings and thus is very weak or disappeared in the indoor environment.
Visible light communication is also developed to transmit identification information for positioning by using the variation of visible light (color, intensity, or position). Such communication technology for transmitting identification information is based on high-frequency blinking visible lights. In details, the identification information to be transmitted is firstly compiled into a digital signal; this digital signal is then applied to modulate the duration time or frequencies of the driving current or driving voltage of the light source, so that the light source blinks in high frequencies.
This high-frequency blinking signal can be detected by a photosensitive device, for example, an image sensor. The image sensor may be based on the “rolling shutter” mechanism, which means that different parts of the sensor, each row or each column, are exposed at different time. Based on this feature, when taking pictures of a light source with rapidly changing brightness, the image sensor with a rolling shutter can deliver an image which contains bright or dark stripes. By measuring the width of the stripes, the frequencies of the driving current or driving voltage of the light source may be calculated and the transmitted identification information may thus be restored.
However, this method has following drawbacks: the width of the stripes can be affected by local over-exposure of the image sensor, for instance, the bright stripes may become broader and the dark stripes may become narrower or even disappear within the over-exposed area, causing failure of the image analysis and decoding and different background lighting conditions may induce uncertainties for measuring the width of stripes.
Additionally, the photosensitive devices used in such visible light communication technology require to be specially designed to detect the visible light signal, and thus, only can be applied in limited scenarios. Additionally, although the commercially available mobile devices (such as, smartphones, tablets, PDAs) have photosensitive components, for example, the image sensor, they are not suitable for sensing such high-frequency blinking signal.
SUMMARYObjects of the present invention are to provide technical solutions for transmitting identification information, obtaining identification information, or positioning by visible light signals, which obviate at least one of the above-mentioned disadvantages.
According to a first aspect of the present invention, there is provided a method transmitting identification information of a light source by visible light signal, the method comprising: modulating, on the basis of the identification information to be transmitted, a driving signal of the light source to obtain a modulated driving signal for driving the light source to emit visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points; and emitting the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points on the basis of the modulated driving signal, so as to transmit identification information corresponding to the varied numbers of bright or dark stripes shown in one or more images obtained from the visible light signal at one or more time points, which numbers are corresponding to the varied frequencies.
According to some embodiments of the present invention, modulating on the basis of the identification information to be transmitted a driving signal of the light source to obtain a modulated driving signal comprises: modulating on the basis of the identification information to be transmitted a driving voltage or a driving current of the light source to obtain a first modulated driving voltage or a first modulated driving current.
According to some embodiments of the present invention, the first modulated driving current is greater than an un-modulated driving current, so that luminous flux of the light source driven by the first modulated driving current is equal to luminous flux of the light source driven by the un-modulated driving current.
According to some embodiments of the present invention, the method further comprising: emitting the visible light signal on the basis of a second modulated driving current which is greater than an un-modulated driving current together with a high frequency carrier wave signal, so that luminous flux of the light source driven by the second modulated driving current is constant among periods comprising peak levels and bottom levels.
According to some embodiments of the present invention, the first modulated driving voltage or the first modulated driving current is used for driving the light source to emit a visible light signal with a frequency from 100 Hz to 1.37 MHz, and duration of each bottom level of the visible light signal is fixed, or duration of each peak level of the light pulse signal is fixed.
According to some embodiments of the present invention, the method further comprising: detecting the presence of a human being within a illumination scope of the light source; and emitting a visible light signal on the basis of un-modulated driving signal in the absence of a human being.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits, which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
According to a second aspect of the present invention, there is provided a method for obtaining identification information of a light source from visible light signals, the method comprising: obtaining one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source; measuring the varied numbers of bright or dark stripes in the one or more images, the varied numbers of bright or dark stripes being corresponding to the varied frequencies; and obtaining identification information corresponding to the varied numbers of the bright or dark stripes.
According to a third aspect of the present invention, there is provided a method for positioning by visible light signals, the method comprising: obtaining at a position one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source; measuring varied numbers of bright or dark stripes in the one or more images, the varied numbers of bright or dark stripes being corresponding to the varied frequencies; obtaining identification information of the light source corresponding to the varied number of the bright or dark stripes; and determining the position by checking the identification information in a predetermined map database.
According to some embodiments of the present invention, the method further comprising: before determining the position by checking the identification information in a predetermined map database, determining an area of the position by means of one or more wireless positioning schemes; and determining the position by checking the identification information in a predetermined map database comprises: determining the position by checking the identification information with data of the area in the predetermined map database.
According to some embodiments of the present invention, the wireless positioning scheme comprises positioning by means of GPS, GPRS, GSM, CDMA, WIFI, Zigbee, Bluetooth, and RFID.
According to some embodiments of the present invention, identification information of a light source is unique for an area at which the light source is located.
According to some embodiments of the present invention, obtaining at a position one or more images at one or more time points from a visible light signal comprises: obtaining at the position the one or more images at one or more time points by an image capturing device comprising an image sensor whose exposure mode is rolling shutter mode, and a sampling rate of the rolling shutter is higher than the frame rate of the image sensor.
According to some embodiments of the present invention, obtaining at a position one or more images at one or more time points from a visible light signal comprises capturing at the position on an image sensor with a rolling shutter the one or more images in which different portions of the image sensor are exposed at different time points.
According to some embodiments of the present invention, the visible light signal is emitted by the light source on the basis of a modulated driving signal, which drives the light source to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points.
According to some embodiments of the present invention, the light source is one or more light sources, and obtaining one or more images at one or more time points from visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source comprises: obtaining one or more images at one or more time points from visible light signal having their level changed between peak levels and bottom levels with varied frequencies at different time points emitted by the one or more light sources, wherein one or more exposed regions in each image correspond to the one or more light sources, measuring the varied numbers of bright or dark stripes in the one or more images comprises: measuring the varied numbers of the bright or dark stripes of the one or more exposed regions in each image, and obtaining identification information corresponding to the varied numbers of the bright or dark stripes comprises: obtaining identification information corresponding to the varied numbers of the bright or dark stripes of the one or more exposed regions in each image.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
According to a fourth aspect of the present invention, there is provided light source for transmitting identification information by visible light signal, comprising: a modulator configured to modulate, on the basis of the identification information to be transmitted, a driving signal of the light source to obtain a modulated driving signal for driving the light source to emit visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points; and an emitter configured to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points on the basis of the modulated driving signal, so as to transmit identification information corresponding to the varied numbers of bright or dark stripes shown in one or more images obtained from the visible light signal at one or more time points, which numbers are corresponding to the varied frequencies.
According to some embodiments of the present invention, the modulator is configured to modulate on the basis of the identification information to be transmitted a driving voltage or a driving current of the light source to obtain a first modulated driving voltage or a first modulated driving current.
According to some embodiments of the present invention, the first modulated driving current is greater than an un-modulated driving current, so that luminous flux of the light source driven by the first modulated driving current is equal to luminous flux of the light source driven by the un-modulated driving current.
According to some embodiments of the present invention, the emitter is configured to emit the visible light signal on the basis of a second modulated driving current which is greater than an un-modulated driving current together with a high frequency carrier wave signal, so that luminous flux of the light source driven by the second modulated driving current is constant among periods comprising peak levels and bottom levels.
According to some embodiments of the present invention, the first modulated driving voltage or the first modulated driving current is used for driving the light source to emit a visible light signal with a frequency from 100 Hz to 1.37 MHz, and duration of each bottom level of the visible light signal is fixed, or duration of each peak level of the light pulse signal is fixed.
According to some embodiments of the present invention, the light source further comprising: a detector configured to detect the presence of a human being within an illumination scope of the light source; and the emitter is configured to emit a visible light signal on the basis of un-modulated driving signal in the absence of a human being.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits, which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
According to a fifth aspect of the present invention, there is provided a device for obtaining identification information of a light source from visible light signal, comprising: an image sensor configured to obtain one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source; a memory configured to store the one or more images obtained by the image sensor at one or more time points; and a processor configured to measure varied numbers of bright or dark stripes in the one or more images stored in the memory and obtain identification information corresponding to the varied numbers of the bright or dark stripes, the varied numbers of bright or dark stripes being corresponding to the varied frequencies.
According to a sixth aspect of the present invention, there is provided a device for positioning by visible light signal, comprising: an image sensor configured to obtain at a position one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source; a memory configured to store the one or more images obtained by the image sensor at one or more time points; and a processor configured to measure varied numbers of bright or dark stripes in the one or more images stored in the memory, obtain identification information of the light source corresponding to the varied number of the bright and dark stripes, and determine the position by checking the identification information in a predetermined map database, the varied numbers of bright or dark stripes being corresponding to the varied frequencies.
According to some embodiments of the present invention, the processor is configured to before determining the position by checking the identification information in a predetermined map database, determine an area of the position by means of one or more wireless positioning schemes; and the processor is configured to determine the position by checking the identification information with data of the area in the predetermined map database.
According to some embodiments of the present invention, the wireless positioning scheme comprises positioning by means of GPS, GPRS, GSM, CDMA, WIFI, Zigbee, Bluetooth, and RFID.
According to some embodiments of the present invention, identification information of a light source is unique for an area at which the light source is located.
According to some embodiments of the present invention, exposure mode of the image sensor is rolling shutter mode, and a sampling rate of the rolling shutter is higher than the frame rate of the image sensor.
According to some embodiments of the present invention, the image sensor is an image sensor with a rolling shutter and is configured to obtain the one or more images in which different portions of the image sensor are exposed at different time points.
According to some embodiments of the present invention, the visible light signal is emitted by the light source on the basis of a modulated driving signal, which drives the light source to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points.
According to some embodiments of the present invention, the light source is one or more light sources, and the image sensor is configured to obtain one or more images at one or more time points from visible light signal having their level changed between peak levels and bottom levels with varied frequencies at different time points emitted by the one or more light sources, wherein one or more exposed regions in each image correspond to the one or more light sources, the memory is configured to store the one or more images obtained by the image sensor at one or more time points; and the processor is configured to measure the varied numbers of the bright or dark stripes of the one or more exposed regions in each image, obtain identification information corresponding to the varied numbers of the bright or dark stripes of the one or more exposed regions in each image.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
In conclusion, the embodiments of the present invention provide an efficient and effective approach for positioning, transmitting and obtaining information, which can achieve indoor positioning, transmit and obtain information much faster and more accurate, and the information transmitted and obtained may contain more data bits. The present invention has advantages of high confidentiality, no occupancy of wireless channel resources, low cost, and easy integration with various light sources. Further, the present invention effectively avoids the undesirable blinking of the light source detectable by human eyes.
The accompanying drawings are included to provide a further understanding of embodiments and constitute a part of this description. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. The elements of the drawings are not necessarily to scale relative to each other. Similar reference numerals designate corresponding similar parts. It should be expressly understood that the drawings are included for illustrative purposes and do not in any manner limit the scope of the present invention.
In the following description, for purposes of explanation rather than limitation, specific details, such as the particular architecture, structure, techniques, etc., are set forth for illustration. However, it will be apparent to those of ordinary skill in the art that other embodiments that depart from these specific details would still be understood to be within the scope of the present invention. Moreover, for the purpose of clarity, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the present invention. It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise.
According to a first aspect of the present invention, there is provided a method for transmitting identification information of a light source by visible light signal.
As shown in
According to some embodiments of the present invention, the light source may be any type of light source emitting visible light signal, for example, LED, fluorescent, or incandescent lamp.
According to some embodiments of the present invention, the identification information transmitted by visible light signal may be any type of identification information, for example, the identifier (ID) of the light source, and other identification information.
According to some embodiments of the present invention, the driving signal of the light source may be in the forms of square wave, sine wave, triangle wave, wave on a higher-frequency carrier, the aforesaid waves containing DC component, or in other forms of wave.
According to some embodiments of the present invention, the driving signal of the light source may be modulated by the Pulse Width Modulation (PWM). Generally, the pulse duration is fixed, and the duty of the signal can be modulated, wherein the duty in a pulse cycle (such as square wave) is the ratio of the positive pulse duration (i.e., duration of the positive part) to the total duration.
According to some embodiments of the present invention, the step 110 may comprise: modulating on the basis of the identification information to be transmitted a driving voltage or a driving current of the light source to obtain a first modulated driving voltage or a first modulated driving current. And the first modulated driving voltage or the first modulated driving current may be used to drive the light source to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points.
According to some embodiments of the present invention, the driving signal, optionally the driving current, of the light source may be modulated on the basis of the identification information to be transmitted to obtain a first modulated driving current, as shown in
As shown in
Optionally, the dark stripe corresponds to the bottom level of the visible light signal, and the bright stripe corresponds to the peak level of the visible light signal. The varied number of the bright stripes and dark stripes corresponds to different identification information transmitted.
In
In
In
After emitting the visible light signal on the basis of the first modulated driving current, as shown in
Alternatively, the driving current or the driving voltage of the light source may have other wave forms. Alternatively, the driving current or the driving voltage of the light source may be modulated to emit visible light signal with four or more kinds of varied frequencies at different time points.
According to an embodiment of the present invention, the first modulated driving current is greater than the un-modulated driving current, so that luminous flux of the light source driven by the first modulated driving current is equal to luminous flux of the light source driven by the un-modulated driving current.
The luminous flux is the measure of the power of light emitted by the light source during unit time, and is proportional to the area below the wave of the driving signal, the variation of which is sensitive to human eye. The driving signal may be modulated with the first modulated driving currents greater than un-modulated driving currents, so that luminous flux of the light source is constant throughout the transmission of identification information to avoid blinking.
Alternatively, as for a first modulated driving current for driving the light source to emit the visible light signal with varied frequencies at different time points, for example, with varied frequencies f3a, f3c and f3e at different time points within time intervals ΔT1, ΔT2 and ΔT3 as shown in
According to some embodiments of the present invention, optionally, the method 100 may comprise a step of emitting the visible light signal on the basis of a second modulated driving current which is greater than an un-modulated driving current together with a high frequency carrier wave signal, so that luminous flux of the light source driven by the second modulated driving current is constant among periods comprising peak levels and bottom levels.
In order to avoid the blinking of the light source when transmitting different codes, the driving current which is greater than un-modulated driving current is further modulated with a high frequency carrier wave signal. By modulating with a high frequency carrier wave signal, within different time intervals, the durations of peak levels and bottom levels of the driving current for transmitting different codes are same, giving the same luminous flux among periods comprising the peak levels and bottom levels, and thus avoiding the blinking of the light source. For example, as shown in
For the purpose of illustration, the visible light signals shown in
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits, which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
With the first modulated driving current as shown in
According to an embodiment of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more starts bit and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits
According to some embodiments of the present invention, the first modulated driving voltage or the first modulated driving current is used for driving the light source to emit a visible light signal with a frequency from 100 Hz to 1.37 MHz, and duration of each bottom level of the visible light signal is fixed, or duration of each peak level of the light pulse signal is fixed.
Optionally, the image may be obtained by an image capturing device comprising an image sensor whose exposure mode is the rolling shutter mode. The exposure time of the image sensor is defined as the exposure time of pixels in each row (or column) of the rolling shutter based image sensor.
When a frame rate of the image sensor is 30 Hz and a resolution is 640*480 (V-line*H-line), time required for capturing one image is 1 s/frame rate=1 s/30 Hz=0.033 s=33 ms, and time required for capturing each row is 1 s/(frame rate*H-line)=33 ms/480=69 us≈70 us. In order to obtain a clear image containing bright or dark stripes with each stripe being corresponding to each row, the exposure time of each is less than 70 us, the duration of alternating the peak and bottom levels of the visible light signal emitted by the light source should be equal to or larger than 70 us and thus the frequency of the visible light signal is less than or equal to 1 s/(duration required for bright stripes+duration required for dark stripes)=1 s/(1 s/(Frame rate*H-line)+1 s/(Frame rate*H-line))=1 s/(70 us+70 us)=7.14 kHz.
When a frame rate of the image sensor is 30 Hz, a resolution is 3 billion Hz with V-line:H-line=1:1, the frequency of the visible light signal is less than or equal to 1 s/(duration required for bright stripes+duration required for dark stripes)=1 s/(1 s/(Frame rate*H-line)+1 s/(Frame rate*H-line))=0.5*30 Hz*(3000000000)0.5=1.37 MHz. Since the light blinking frequency detectable by human eyes is less than 100 Hz, the frequency of visible light signal is from 100 Hz to 1.37 MHz.
Referring to
According to some embodiments of the present invention, optionally, the method 100 may further comprise steps of detecting the presence of a human being within an illumination scope of the light source, and emitting a visible light signal on the basis of un-modulated driving signal in the absence of a human being.
It should be noted by those skilled in the art that the frequencies, waveforms, or widths of the peak levels and bottom levels of the modulated driving current are not limited to the above exemplary values, but may be set to have any values as required. Similarly, the frequencies, waveforms, or widths of the peak levels and bottom levels of the high frequency signal wave signal are not limited to the above exemplary values, but may be set to have any values as required.
According to a second aspect of the present invention, there is provided a method for obtaining identification information of a light source from visible light signal.
As shown in
According to a third aspect of the present invention, there is provided a method 300 for positioning by visible light signals.
Embodiments of the third aspect of the present invention also apply to the second aspect of the present invention, thus only the embodiments of the third aspect will be described in details hereinafter, and same embodiments of the second aspect will not be described repeatedly for the sake of conciseness.
As shown in
According to some embodiments of the present invention, the visible light signal may be emitted by the light source on the basis of a modulated driving signal, which drives the light source to emit visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points, as described hereinbefore in details with respect to the method 100.
According to some embodiments of the present invention, the modulated driving signal may be modulated by the PWM scheme. Optionally, the modulated driving signals may be modulated driving voltages or modulated driving currents.
Optionally, the modulated driving current may be greater than un-modulated driving current, so that luminous flux of the light source driven by the modulated driving current is equal to luminous flux of light source driven by the un-modulated driving current, as described hereinbefore in details with respect to the method 100 making reference to
Optionally, the modulated driving current may be greater than un-modulated driving currents together with a high frequency carrier wave signal, so that the luminous flux of the light source driven by the driving current is constant among periods comprising peak levels and bottom levels, as described hereinbefore in details with respect to the method 100 making reference to
The above embodiments have been described in details previously with respect to the method 100, and will not be iterated herein for the sake of conciseness.
According to some embodiments of the present invention, the image obtained from the visible light signal may be an image containing bright or dark stripes as shown in
According to some embodiments of the present invention, the step 210 may comprise obtaining at the position one or more images at one or more time points by an image capturing device comprising an image sensor whose exposure mode is rolling shutter mode, and a sampling rate of the rolling shutter is higher than the frame rate of the image sensor. The image capturing device is used for capturing the one or more images obtained from the visible light signal emitted by the light source. The image capturing device may be a smartphone, laptop computer, or other electronic device equipped with camera(s). Alternatively, the image capturing device may be an embedded system integrated in other devices or objects, for example, piece jewelry, key, card, pen, etc. The image sensor may be a photosensitive component.
For an image sensor whose exposure mode is rolling shutter mode, different parts of the image sensor, each row or each column, may be exposed at different time. The image sensor may obtain one or more images containing bright or dark stripes, such as those shown in
According to some embodiments of the present invention, the step 210 may comprise capturing at the position on an image sensor with a rolling shutter the one or more images in which different portions of the image sensor are exposed at different time points. Optionally, the image sensor may be a complementary metal-oxide-semiconductor (CMOS) image sensor or a Charge-Coupled Device (CCD) image sensor.
As shown in
According to some embodiments of the present invention, varied numbers of bright or dark stripes in the one or more images obtained from the visible light signal may be measured by, for example, an image processor or a general purpose processor. After the image is projected onto the image sensor surface, the optical signal detected by the image sensor is converted into electrical signal by the image sensor. The analog electrical signals are converted into digital signals by an analog-to-digital-converter (ADC) of the image sensor or the processor. The processor is applied to further process the digital signal and generate a digital image, which may be displayed on a monitor. Optionally, a digital signal processing (DSP) module of the processor may be applied to process the digital signal and generate a digital image.
As shown in
According to some embodiments of the present invention, the identification information of the light source corresponding to the pattern of the color stripes may be any type of identification information, for example, the identifier (ID) of the light source, and other identification information.
According to some embodiments of the present invention, the varied numbers of bright or dark stripes in the one or more images are derived from the varied frequencies of the visible light signal at different time points. According to some embodiments of the present invention, the identification information of the light source corresponding to the varied numbers of bright or dark stripes may be decoded. By this way, the initial identification information carried on the visible light signal can be recovered.
As shown in
It should be noted that although varied frequencies of the visible light signals at different time points are used during coding, the transmitted identification information of the light source may be decoded by comparing the relative frequencies corresponding to the numbers of the bright or dark stripes, instead of the absolute frequencies of the visible light signals.
According to some embodiments of the present invention, the light source may be one or more light sources. One or more images from visible light signal emitted by the light source may be obtained at one or more time points. Each image obtained may have one or more exposed regions, and each exposed region may contain bright or dark stripes corresponding to one light source.
The step 310 may comprise: obtaining one or more images at one or more time points from visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by the one or more light sources, wherein one or more exposed regions in each image correspond to the one or more light sources. The image having one or more exposed regions obtained from one or more light source, for example the image shown in
When the incident light is not in perpendicular with the plane of the image sensor, the shape of the light spot projected on the image sensor may have distortion, for example, from a circular to an ellipse. In this case, acceleration meter, gravity sensor, tilt sensor, gyro, or magnetic sensor may be applied to measure the angle of inclination, which may be used to obtain the identification information of one or more light sources corresponding to the varied numbers of bright or dark stripes of the one or more exposed regions in the image.
As shown in
According to some embodiments of the present invention, optionally, before step 330, method 300 may further comprise determining an area of the position by means of one or more wireless positioning schemes. After the area of the position is determined, the position can be then determined by checking the identification information with data of the area in the predetermined map database.
According to some embodiments of the present invention, identification information of a light source is unique for an area at which the light source is located.
According to some embodiments of the present invention, the wireless positioning scheme comprises positioning by means of GPS, GPRS, GSM, CDMA, WIFI, Zigbee, Bluetooth, and RFID.
By determining an area of the position by means of one or more wireless positioning schemes, the area where the light source is located can be determined, providing the rough position of the light source. Then, the position of the light source within the area can be determined by checking the identification information with data of the area in the predetermined map database, providing the accurate position of the light source. By this way, each area may have independent map database. The identification information of the light source in one area may be different from that in a different area.
Alternatively, the identification information of the light source in one area may be same as that in a different area, and under such circumstances, the area where the light source is located should be determined firstly and then the position of the light source within the area can be determined on the basis of the identification information which unique in the area. Such embodiment allows easier coding and shorter length of the identification information, and faster transmission of the identification information.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
With the modulated driving current as shown in
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
Referring to
Referring to
According to a fourth aspect of the present invention, there is provided a light source 400 for transmitting identification information by visible light signal. As shown in
As shown in
The modulator 410 may be configured to modulate, on the basis of the identification information to be transmitted, a driving signal of the light source to obtain a modulated driving signal for driving the light source to emit visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points.
The emitter 420 may be configured to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points on the basis of the modulated driving signal, so as to transmit identification information corresponding to the varied numbers of bright or dark stripes shown in one or more images obtained from the visible light signal at one or more time points, which numbers are corresponding to the varied frequencies.
According to some embodiments of the present invention, the modulator 410 may be configured to modulate on the basis of the identification information to be transmitted a driving voltage or a driving current of the light source to obtain a first modulated driving voltage or a first modulated driving current.
According to some embodiments of the present invention, the first modulated driving current is greater than the un-modulated driving current, so that the luminous flux of the light source driven by the first modulated driving current is equal to the luminous flux of the light source driven by the un-modulated driving current.
According to some embodiments of the present invention, the emitter 420 can be configured to emit the visible light signal on the basis of a second modulated driving current which is greater than the un-modulated driving current together with a high frequency carrier wave signal, so that luminous flux of the light source driven by the second modulated driving current is constant among periods comprising peak levels and bottom levels.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes may further comprise one or more starts bit and/or one or more error correction bits, the start bits are used to identify a start position of a set of data bits, and the one or more error correction bits are used to check error in the data bits.
According to some embodiments of the present invention, the first modulated driving voltage or the first modulated driving current is used for driving the light source to emit a visible light signal with a frequency from 100 Hz to 1.37 MHz, and duration of each bottom level of the visible light signal is fixed, or duration of each peak level of the light pulse signal is fixed.
According to some embodiments of the present invention, the light source 400 may further comprise a detector configured to detect the presence of a human being within an illumination scope of the light source, and the emitter is configured to emit a visible light signal on the basis of un-modulated driving signal in the absence of a human being.
The above detailed descriptions for the method 100 also apply to the embodiments of the light source 400 according to the present invention, and are thus not iterated for the sake of conciseness. In particular, the step 110 in the method 100 can be performed by the modulator 410, and the step 120 in the method 100 can be performed by the emitter 420.
According to a fifth aspect of the present invention, there is provided a device 500 for obtaining identification information from visible light signal. For example, the device may be a mobile device with a camera, such as a smartphone, tablet, laptop computer, or other electronic device. However, the device 500 is not limited to these examples, but can be any electronic device with photosensitive component.
As shown in
The image sensor 510 can be configured to obtain one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source. The memory 520 can be configured to store the one or more images obtained by the image sensor at one or more time points. The processor 530 can be configured to measure varied numbers of bright or dark stripes in the one or more images stored in the memory 520 and obtain identification information corresponding to the varied numbers of the bright or dark stripes, and the varied numbers of bright or dark stripes are corresponding to the varied frequencies.
According to a sixth aspect of the present invention, there is provided a device for positioning by visible light signal. For example, the device may be a mobile device with a camera, such as a smartphone, tablet, laptop computer, or other electronic device. However, the device is not limited to these examples, but can be any electronic device with photosensitive component.
Embodiments of the sixth aspect of the present invention also apply to the fifth aspect of the present invention, thus only the embodiments of the sixth aspect will be described in details hereinafter, and same embodiments of the fifth aspect will not be described repeatedly for the sake of conciseness.
Embodiments of device according to the sixth aspect of the present invention will be described with reference to
As shown in
The image sensor 510 can be configured to obtain at a position one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source. The memory 520 can be configured to store the one or more images obtained by the image sensor at one or more time points. The processor 530 can be configured to measure varied numbers of bright or dark stripes in the one or more images stored in the memory 520, obtain identification information corresponding to the varied numbers of the bright or dark stripes, and determine the position by checking the identification information in a predetermined map database, the varied numbers of bright or dark stripes being corresponding to the varied frequencies.
According to some embodiments of the present invention, the processor 530 is configured to before determining the position by checking the identification information in a predetermined map database, determine an area of the position by means of one or more wireless positioning schemes; and the processor 530 is configured to determine the position by checking the identification information with data of the area in the predetermined map database. According to some embodiments of the present invention, the wireless positioning scheme comprises positioning by means of GPS, GPRS, GSM, CDMA, WIFI, Zigbee, Bluetooth, and RFID.
According to some embodiments of the present invention, identification information of a light source 400 is unique for an area at which the light source 400 is located.
By determining an area of the position by means of one or more wireless positioning schemes, the area where the light source is located can be determined, providing the rough position of the light source. Then, the position of the light source within the area can be determined by checking the identification information with data of the area in the predetermined map database, providing the accurate position of the light source. By this way, each area may have independent map database. The identification information of the light source in one area may be different from that in a different area.
Alternatively, the identification information of the light source in one area may be same as that in a different area, and under such circumstances, the area where the light source is located should be determined firstly and then the position of the light source within the area can be determined on the basis of the identification information which unique in the area. Such embodiment allows easier coding and shorter length of the identification information, and faster transmission of the identification information.
According to some embodiments of the present invention, exposure mode of the image sensor is rolling shutter mode, and a sampling rate of the rolling shutter is higher than the frame rate of the image sensor.
According to some embodiments of the present invention, the image sensor 510 is an image sensor with a rolling shutter and is configured to obtain the one or more images in which different portions of the image sensor are exposed at different time points. Optionally, the image sensor 510 may be a complementary metal-oxide-semiconductor (CMOS) image sensor or a Charge-Coupled Device (CCD) image sensor.
According to some embodiments of the present invention, the visible light signal is emitted by the light source 400 on the basis of a modulated driving signal, which drives the light source 400 to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points.
According to some embodiments of the present invention, the light source 400 may be one or more sets of light sources, and the image sensor 510 can be configured to obtain one or more images at one or more time points from visible light signal having their level changed between peak levels and bottom levels with varied frequencies at different time points emitted by the one or more light sources, wherein one or more exposed regions in each image correspond to the one or more light sources; the memory 520 can be configured to store the one or more images obtained by the image sensor at one or more time points; and the processor 530 can be configured to measure the varied numbers of the bright or dark stripes of the one or more exposed regions in each image, and obtain identification information corresponding to the varied numbers of the bright or dark stripes of the one or more exposed regions in each image.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
According to some embodiments of the present invention, the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
The above detailed descriptions for the method 300 also apply to the embodiments of the device 500 according to the sixth aspect of the present invention, and are thus not iterated for the sake of conciseness. In particular, the step 310 in the method 300 as described above can be performed by the image sensor 510 and memory 520, and the steps 330, 340 and 350 in the method 300 can be performed by the processor 530.
According to some embodiments of the present invention, the device for positioning by visible light signal may be a mobile device.
According to some embodiments of the present invention, a mobile device may be integrated with a positioning software.
According to some embodiments of the present invention, a predetermined map database contains the identification information of the light sources.
There are two conventional ways to modify the identification information stored in the light source: Disassembling the memory chip from the light source, and modifying the identification information by a compiler, which can rewrite the memory chip; and reserving an interface for modifying identification information on the light source, connecting the interface with a compiler which can rewrite the memory chip through a cable to modify the memory chip. Both ways are complex and consequently lead to a high maintenance cost.
According to some embodiments of the present invention, the identification information of the light source may be modified by a mobile modification device via wireless communication.
According to some embodiments of the present invention, a mobile modification device can update the information stored in the light source as shown in
According to some embodiments of the present invention, the identification information of the light source may be updated through the mobile modification device as shown in
According to some embodiments of the present invention,
According to some embodiments of the present invention,
According to some embodiments of the present invention,
According to some embodiments of the present invention,
According to some embodiments of the present invention,
According to some embodiments of the present invention,
According to some embodiments of the present invention,
Magnetometer and gyroscope could be used to measure the direction of motion. The positioning can be realized only by visible light signal, or by combining with other positioning methods, such as, GPS, GPRS, GSM, CDMA, Wi-Fi, Zigbee, Bluetooth, RFID, accelerometer, angular transducer, gyroscope, ultrasonic, etc. Between two light sources, more methods as mentioned above may be applied, to improve the consistency and continuity of the positioning. For example, accelerometer is applied to measure the frequency of human steps; then the walking speed can be estimated by a normal length of ty of the positiangular transducer is applied to measure the walking direction. In this way, when moving between two light sources, the position of the mobile device still can be roughly positioned.
According to some embodiments of the present invention,
According to some embodiments of the present invention,
According to some embodiments of the present invention,
According to some embodiments of the present invention, a map database may be used for positioning. The mobile device receives the light signal sent by the light source; the position of the mobile device is determined by comparing the identification codes with the database; the current position of the mobile device is shown on the display of the mobile device. This positioning system can be applied for the navigation in a shopping mall or super market, and can be used for business statistics, market expansion, online support, SNS (Social Networking Services), Management profiles, or other position-related applications.
According to some embodiments of the present invention, the light source 400 may further comprises an AC/DC converter, a micro-controller and a memory, as shown in
According to some embodiments of the present invention, the exposure time of the image sensor 510 may be adjusted before capturing an image.
According to some embodiments of the present invention, in order to capture images with bright or dark stripes clearly, the sampling duration rate of the image sensor may be smaller or equal to the duration of the peak level or bottom level of the visible light signal emitted by the light source, as shown in
According to some embodiments of the present invention, after the image is captured, the exposed region in the image is detected as shown in
According to some embodiments of the present invention, when the light source is one or more light source, each image captured may contain one or more exposed regions corresponding to one or more light sources. The one or more exposed regions in the image may be detected as shown in
According to some embodiments of the present invention, the exposure time of the image sensor 510 may be adjusted before capturing an image.
According to some embodiments of the present invention, the captured image containing bright and dark stripes may be decoded, optionally by decoding software, in the following manner: capturing one or more images from the visible light signal emitted by a light source; determining one or more exposed regions in each image; measuring the number of the bright or dark strips where different number represents different code; and recovering the transmitted identification information.
Alternatively, the exposed region within the image is searched from the center of the image outwards along a spiral route, optionally, by pre-installed software, as shown in
Alternatively, the number of the bright or dark strips within the optimized exposed region may be measured by measuring the gray scale value within the optimized exposed region according to embodiments of the present invention, as shown in
Alternatively, the number of the bright or dark strips may be measured according to embodiments of the present invention, as shown in
Alternatively, the number of the bright or dark strips may be measured according to another embodiment of the present invention, as shown in
According to some embodiments of the present invention, the device 400 may contain multiple image sensors as shown in
According to some embodiments of the present invention, a software program may be used to trigger the image sensor in the device for obtaining identification information from visible light signal to start receiving the visible light signal. Optionally, the real-time image and the identification information obtained therefrom may be displayed in the program during the process of capturing image, as shown in
According to some embodiments of the present invention, a light source for transmitting identification information by visible light signal comprising a modulator and an emitter according to the present invention may be included in a transmitter as shown in
According to some embodiments of the present invention, when the image sensor is activated to receive the visible light signal, the transmitter is informed to send the visible light signal. This can be realized by a hardware-based switch installed on the transmitter, as shown in
According to some embodiments of the present invention, a photosensitive device may be integrated in the transmitter to detect the state of the image sensor, such as whether the image sensor is ready to capture images. Before the transmitter sends the visible light signal, the photosensitive device may first check the state of the image sensor. Optionally, when the image sensor is ready to capture images, the light emitting component of the image sensor changes the brightness at a certain frequency, and such changes of the brightness can be detected by the photosensitive device integrated in the transmitter; and then the transmitter starts to send the visible light signal, as shown in
According to some embodiments of the present invention, the transmitter may transmit multiple types of identification information, comprising but not limited to, identifier (ID) of the transmitter, voice, text, audio, pictures, video, etc., which may be stored in the memory, as shown in
According to some embodiments of the present invention, the transmitter may comprise a light source according to the present invention, a microprocessor (for example a MCU), and a battery, as shown in
According to some embodiments of the present invention, the transmitter may further comprise a sensor as shown in
According to some embodiments of the present invention, the transmitter may further comprise a memory as shown in
According to some embodiments of the present invention, the transmitter may further comprise a display as shown in
According to some embodiments of the present invention, the device for obtaining identification information may comprise an image sensor, a microprocessor (for example a MCU) and a power supply, as shown in
According to some embodiments of the present invention, the device for obtaining identification information from visible light signal having its level changed between a peak level and a bottom level with varied frequencies according to embodiments of the present invention may further comprise a communication module, as shown in
According to some embodiments of the present invention, the transmitter could be a lamp. The transmitter may be an embedded system integrated in other devices, such as an integrated part of a ring, as shown in
According to some embodiments of the present invention, the basic working principle of the system for transmitting and obtaining identification information by visible light signal comprising a light source for transmitting identification information by visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points and a device for obtaining identification information from visible light signal from light source according to embodiments of the present invention is as follows: the image sensor in the device captures the visible light signal emitted by the light source and obtain one or more images therefrom, and the processor in the device measures the varied numbers of bright or dark stripes in each image and recovers the identification information corresponding to the varied numbers of bright or dark stripes.
According to some embodiments of the present invention, the transmitter may be integrated in a wearable electronic device, providing advantages of small in volume, easy to carry, and low in power consumption. The wearable electronic device may be a jewelry, such as a ring, an earrings, a necklace, a watches, etc., or maybe a key, a card, a pen, etc. When the transmitter is integrated in the wearable electronic device, such wearable electronic device can emit visible light signals for transmitting identification information.
According to some embodiments of the present invention, the transmitter may be integrated in a wearable electronic device, such as a ring powered by a battery, as shown in
According to some embodiments of the present invention, the transmitter may comprise one or more light sources that can emit visible light signals having their level changed between peak levels and bottom levels with varied frequencies at different time points, as shown in
According to some embodiments of the present invention, the transmitter may further comprise a driver, as shown in
According to some embodiments of the present invention, the transmitter may further comprise a battery charging circuit, as shown in
According to some embodiments of the present invention, the transmitter may further comprise a memory as shown in
According to some embodiments of the present invention, the transmitter may further comprise a sensor as shown in
According to some embodiments of the present invention, the transmitter may further comprise a network adaptor as shown in
According to some embodiments of the present invention, before the transmitter sends the visible light signal, the transmitter may first check the state of the image sensor in the device for obtaining identification information from visible light signal. Optionally, when the image sensor is ready to capture images, the screen of the light emitting component changes the brightness at a certain frequency, and such changes of the brightness can be detected by the photosensitive device (e.g., a sensor) integrated in the transmitter; and then the transmitter starts to send the visible light signal, as shown in
According to some embodiments of the present invention, the transmitter is integrated in a wearable electronic device. When the wearable electronic device starts to send the visible light signals, its transmitter should be turned on. This can be realized by a hardware-based switch installed on the transmitter, or other sensor-based switch connected to the transmitter. When the wearable electronic device receives the switch-on signal, it starts to send light signal. The above described process is illustrated in
According to some embodiments of the present invention, after a transmitter starts to send the visible light signal, the working flow of the image sensor in the device for obtaining identification information from visible light signal is as follows, as shown in
According to some embodiments of the present invention, it provides a positioning system based on the visible light signal as shown in
In conclusion, the embodiments of the present invention provide an efficient and effective approach for transmitting/obtaining identification information and positioning by visible light signal, which can achieve indoor positioning, transmit/obtain identification information much faster and more accurate, and the identification information transmitted/obtained may contain more data bits. Further, the embodiments of the present invention effectively avoid the undesirable blinking of the light source detectable by human eyes.
It should be noted that the aforesaid embodiments are exemplary rather than limiting the present invention, substitute an alternative embodiments may be designed by those skilled in the art without departing from the scope of the claims enclosed. The word “include” does not exclude elements or steps which are present but not listed in the claims. The word “a” or “an” preceding the elements does not exclude the presence of a plurality of such elements. In the apparatus claims that list several components, several ones among these components can be specifically embodied in the same hardware item. The use of such words as first, second, third does not represent any order, which can be simply explained as names.
Claims
1. A method for transmitting identification information of a light source by visible light signal, the method comprising:
- modulating, on the basis of the identification information to be transmitted, a driving signal of the light source to obtain a modulated driving signal for driving the light source to emit visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points; and
- emitting the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points on the basis of the modulated driving signal, so as to transmit identification information corresponding to the varied numbers of bright or dark stripes shown in one or more images obtained from the visible light signal at one or more time points, which numbers are corresponding to the varied frequencies.
2. The method according to claim 1, wherein modulating on the basis of the identification information to be transmitted a driving signal of the light source to obtain a modulated driving signal comprises: modulating on the basis of the identification information to be transmitted a driving voltage or a driving current of the light source to obtain a first modulated driving voltage or a first modulated driving current.
3. The method according to claim 2, wherein the first modulated driving current is greater than an un-modulated driving current, so that luminous flux of the light source driven by the first modulated driving current is equal to luminous flux of the light source driven by the un-modulated driving current.
4. The method according to claim 2, further comprising: emitting the visible light signal on the basis of a second modulated driving current which is greater than an un-modulated driving current together with a high frequency carrier wave signal, so that luminous flux of the light source driven by the second modulated driving current is constant among periods comprising peak levels and bottom levels.
5. The method according to claim 2, wherein the first modulated driving voltage or the first modulated driving current is used for driving the light source to emit a visible light signal with a frequency from 100 Hz to 1.37 MHz, and duration of each bottom level of the visible light signal is fixed, or duration of each peak level of the light pulse signal is fixed.
6. The method according to claim 1, further comprising:
- detecting the presence of a human being within a illumination scope of the light source; and
- emitting a visible light signal on the basis of un-modulated driving signal in the absence of a human being.
7. The method according to claim 1, wherein the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits, which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
8. The method according to claim 7, wherein the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
9. A method for positioning by visible light signals, the method comprising:
- obtaining at a position one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source;
- measuring varied numbers of bright or dark stripes in the one or more images, the varied numbers of bright or dark stripes being corresponding to the varied frequencies;
- obtaining identification information of the light source corresponding to the varied number of the bright or dark stripes; and
- determining the position by checking the identification information in a predetermined map database.
10. The method according to claim 9, further comprising:
- before determining the position by checking the identification information in a predetermined map database, determining an area of the position by means of one or more wireless positioning schemes; and
- determining the position by checking the identification information in a predetermined map database comprises: determining the position by checking the identification information with data of the area in the predetermined map database.
11. The method according to claim 9, wherein obtaining at a position one or more images at one or more time points from a visible light signal comprises capturing at the position on an image sensor with a rolling shutter the one or more images in which different portions of the image sensor are exposed at different time points.
12. The method according to claim 9, wherein the visible light signal is emitted by the light source on the basis of a modulated driving signal, which drives the light source to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points.
13. The method according to claim 9, wherein the light source is one or more light sources, and
- obtaining one or more images at one or more time points from visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source comprises: obtaining one or more images at one or more time points from visible light signal having their level changed between peak levels and bottom levels with varied frequencies at different time points emitted by the one or more light sources, wherein one or more exposed regions in each image correspond to the one or more light sources,
- measuring the varied numbers of bright or dark stripes in the one or more images comprises: measuring the varied numbers of the bright or dark stripes of the one or more exposed regions in each image, and
- obtaining identification information corresponding to the varied numbers of the bright or dark stripes comprises: obtaining identification information corresponding to the varied numbers of the bright or dark stripes of the one or more exposed regions in each image.
14. The method according to claim 9, wherein the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
15. The method according to claim 9, wherein the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
16. A light source for transmitting identification information by visible light signal, comprising:
- a modulator configured to modulate, on the basis of the identification information to be transmitted, a driving signal of the light source to obtain a modulated driving signal for driving the light source to emit visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points; and
- an emitter configured to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points on the basis of the modulated driving signal, so as to transmit identification information corresponding to the varied numbers of bright or dark stripes shown in one or more images obtained from the visible light signal at one or more time points, which numbers are corresponding to the varied frequencies.
17. The light source according to claim 16, wherein the modulator is configured to modulate on the basis of the identification information to be transmitted a driving voltage or a driving current of the light source to obtain a first modulated driving voltage or a first modulated driving current.
18. The light source according to claim 17, wherein the first modulated driving current is greater than an un-modulated driving current, so that luminous flux of the light source driven by the first modulated driving current is equal to luminous flux of the light source driven by the un-modulated driving current.
19. The light source according to claim 17, wherein the emitter is configured to emit the visible light signal on the basis of a second modulated driving current which is greater than an un-modulated driving current together with a high frequency carrier wave signal, so that luminous flux of the light source driven by the second modulated driving current is constant among periods comprising peak levels and bottom levels.
20. The light source according to claim 17, wherein the first modulated driving voltage or the first modulated driving current is used for driving the light source to emit a visible light signal with a frequency from 100 Hz to 1.37 MHz, and duration of each bottom level of the visible light signal is fixed, or duration of each peak level of the light pulse signal is fixed.
21. The light source according to claim 16, further comprising:
- a detector configured to detect the presence of a human being within a illumination scope of the light source; and
- wherein the emitter is configured to emit a visible light signal on the basis of un-modulated driving signal in the absence of a human being.
22. The light source according to claim 16, wherein the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits, which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
23. The light source according to claim 22, wherein the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
24. A device for positioning by visible light signal, comprising:
- an image sensor configured to obtain at a position one or more images at one or more time points from a visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points emitted by a light source;
- a memory configured to store the one or more images obtained by the image sensor at one or more time points; and
- a processor configured to measure varied numbers of bright or dark stripes in the one or more images stored in the memory, obtain identification information of the light source corresponding to the varied number of the bright and dark stripes, and determine the position by checking the identification information in a predetermined map database, the varied numbers of bright or dark stripes being corresponding to the varied frequencies.
25. The device according to claim 24, wherein the processor is configured to before determining the position by checking the identification information in a predetermined map database, determine an area of the position by means of one or more wireless positioning schemes; and the processor is configured to determine the position by checking the identification information with data of the area in the predetermined map database.
26. The device according to claim 24, wherein the image sensor is an image sensor with a rolling shutter and is configured to obtain the one or more images in which different portions of the image sensor are exposed at different time points.
27. The device according to claim 24, wherein the visible light signal is emitted by the light source on the basis of a modulated driving signal, which drives the light source to emit the visible light signal having its level changed between a peak level and a bottom level with varied frequencies at different time points.
28. The device according to claim 24, wherein the light source is one or more light sources, and
- the image sensor is configured to obtain one or more images at one or more time points from visible light signal having their level changed between peak levels and bottom levels with varied frequencies at different time points emitted by the one or more light sources, wherein one or more exposed regions in each image correspond to the one or more light sources,
- the memory is configured to store the one or more images obtained by the image sensor at one or more time points; and
- the processor is configured to measure the varied numbers of the bright or dark stripes of the one or more exposed regions in each image, obtain identification information corresponding to the varied numbers of the bright or dark stripes of the one or more exposed regions in each image.
29. The device according to claim 24, wherein the identification information corresponding to the varied numbers of bright or dark stripes comprises data bits which comprise data corresponding to the varied frequencies, and each data bit corresponds to a number among the varied numbers of bright or dark stripes.
30. The device according to claim 24, wherein the identification information corresponding to the varied numbers of bright or dark stripes further comprises one or more start bits and/or one or more error correction bits, the one or more start bits being used to identify a start position of a set of data bits, and the one or more error correction bits being used to check error in the data bits.
Type: Application
Filed: Apr 7, 2014
Publication Date: Dec 18, 2014
Applicant: Zhuhai Hengqin Great Aim Visible Light Communication Technology Co. Ltd. (Zhuhai City)
Inventors: Cheng Guo (Beijing), Hong Hu (Beijing)
Application Number: 14/246,460
International Classification: G01C 15/00 (20060101); H05B 37/02 (20060101);
