Position Sensor
A hinge position sensor comprises first and second members connected together to provide a hinge, and an optical fibre or wave-guide connected between the first and second members to provide a communication link between the first and second members. A laser or LED is coupled to the optical fibre or wave-guide to transmit optical signals between the first and second members and the optical signal is received by a photo-detector. The optical fibre or wave-guide is physically distorted by actuation of the hinge such that light escapes from the optical fibre or wave-guide. The optical power level received by the photo-detector is used to determine the position of the hinge.
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This application is a divisional application of co-pending U.S. Non-Provisional Application No. 11/423,927, filed Jun. 13, 2006, entitled “Position Sensor”, the disclosure of which is expressly incorporated herein by reference in its entirety.
FIELD OF THE INVENTIONThe present invention relates to an optical position sensor, particularly, but not exclusively, to a fibre optic position sensor for sensing the position of a hinged lid of a portable electronic device such as a mobile telephone or a lap-top computer.
BACKGROUND TO THE INVENTIONIt is common for a portable electronic device such as a lap-top computer or a mobile telephone to comprise a base, which includes the device's keypad, and a lid, which includes the device's screen or user display. In this type of device, the base and the lid are connected together by a hinge section such that the user display can be hinged to lie flat against the keypad when the device is not in use. By detecting when the hinge is closed, the device is able to detect when it may safely switch to a power-saving mode. This function allows the device to conserve battery power when the device is not in use.
It is known to detect the open/closed state of this type of hinge using a mechanical sensor, such as a boss-type media detection switch or a rotary-type position detection switch. However, the use of a mechanical sensor often imposes design constraints on the electronic device and may also require that bosses be fitted to the device's exterior. A mechanical sensor often also requires extra space on the motherboard of the device for the inclusion of a detector switch.
Alternatively, the position of the hinge may be detected using a solid-state relay. For example, it is known to magnetically detect the position of a lid with a system employing a Hall Integrated Circuit. However, this type of detector requires both space on the motherboard of the device and a level of standby power. In addition, magnetic switches of this type are liable to interfere with other types of sensor which may be integrated into the device, such as those employed by global positioning systems.
The use of optical proximity sensors is also known. However the surfaces of a proximity sensor's emitter and receiver must be kept clean in order for the sensor to function reliably.
SUMMARY OF THE INVENTIONAccording to the present invention, there is provided a hinge-position detection apparatus comprising a first member and a second member rotationally connected to one another so as to provide a hinge, a first optical fibre, a light emitter to transmit light through the optical fibre and a light detector to detect a power level of light emitted from the optical fibre, wherein the optical fibre is physically distorted by actuation of the hinge and the detected power level is used to determine the position of the hinge.
Preferably, a physical distortion in the optical fibre causes light to escape from the optical fibre and affects the optical power level detected by the light detector.
Preferably, the optical fibre is connected between the first member and the second member so as to traverse the hinge.
Preferably, the determined position of the hinge is used to control the operation of an electronic device.
More preferably, if the hinge is determined to be in a closed position, the apparatus is configured to switch one or more components of an electronic device to a power saving mode.
Preferably, the hinge is determined to be in a closed position if the detected optical power level reaches a predetermined threshold level.
Preferably, the light emitter is included in the first member, the light detector is included in the second member and the optical fibre is coupled between the light emitter and the light detector.
Preferably, the light detector is positioned to directly detect the emission of light from the optical fibre, the emission of light being caused by a physical distortion in the fibre.
More preferably, the apparatus includes a further optical fibre operable to direct the emission of light from the optical fibre to the detector.
Preferably, the light emitter comprises an LED or a laser, and the light detector comprises a photo-sensitive device, such as a photo-diode, photo-transistor or photo-resistor.
In order that the invention may be more fully understood, embodiments thereof will now be described by way of illustrative example with reference to the accompanying drawings in which:
Referring to
The telephone handset 11 is configured to operate in a cellular radio network, such as a GSM network, although it could be configured for use with other networks such as a 3G network or I-mode.
The telephone handset 11 is provided with a user display 15, for example in the form of a liquid crystal display (LCD) panel. The handset 11 is additionally provided with a loudspeaker 16, which is located in the lid 13 and is on the same surface as the user display 15. The base 12 of the handset 11 houses the remainder of the telephone's principal components, including a keypad 17.
The keypad 17 is located on the surface of the base 12 such that, when the hinge joint 14 is in the closed position, the keypad 17 directly faces the user display 15. Thus, the user display 15 and keypad 17 are not visible to the user when the hinge 14 is closed. An antenna 18 is located inside the base 12 such that it does not form part of the handset's exterior.
Referring to
The rf subsystem 26 contains the circuits of the telephone's transmitter and receiver. The rf subsystem 26 is coupled to the antenna 18 for the reception and transmission of radio signals in a cellular mobile network.
The antenna 18 is connected through the rf subsystem 26 to the codec 27, which is configured to process signals under the control of the micro-controller 28.
The micro-controller 28 operates according to a program stored in the memory 29 and controls the operation of the handset 11. It is coupled to the rf subsystem 26 for supplying tuning instructions to a frequency synthesizer.
The user display 15 is connected to the micro-controller 28 for receiving control data and the keypad 17 is connected to the micro-controller 28 for supplying user input data. In
The amplifier 24 amplifies demodulated audio from the codec 27 and applies it to the loudspeaker 16. Acoustic signals, detected by the microphone 21, are pre-amplified by the amplifier 25 and sent to the codec 27 for coding.
Information concerning the identity of the user is held on the smart card 22 in the form of a GSM SIM card which contains the usual GSM international mobile subscriber identity (IMSI) and an encryption key Ki that is used for encoding the radio transmission in a manner that is well known. The SIM card is removably received in the SIM card reader 23.
Referring to
Referring to
The optical fibre 31 comprises a central core 31a surrounded by a cladding layer 31b. The refractive index of the core 31a is of a different refractive index to that of the cladding 31b, meaning that light is confined to the core 31a by total internal reflection and is guided along the optical fibre 31. The optical fibre 31 may be either a graded optical fibre or a step-index optical fibre. The light transmitted through the optical fibre 31 may carry, for example, signals for controlling the operation of the user display 15 or loudspeaker 16. Alternatively, light transmitted through the optical fibre 31 may comprise control data for illumination at the lid side of the handset 11. In an alternative embodiment, the laser 41 could be replaced by a light-emitted diode (LED).
Further referring to
The optical fibre 31 is fabricated from suitable plastics and is flexible in such a way that it is able to bend with the hinge joint 14 of the telephone handset 11. The use of plastics allows the optical fibre 31 to be adapted such that it may be bent to a very small radius. This is convenient as the optical fibre 31 should be able to comfortably bend to a radius enabling it to traverse the hinge joint 14 when the handset 11 in the closed position. The use of plastics also provides advantages in terms of transmission speed and is inexpensive in comparison to alternative materials. However, it will be appreciated that materials other than plastics can be used.
Referring to
The optical power detected at the photodiode 42 can be used to calculate the position of the hinge joint 14. Information concerning the position of the hinge joint 14 may then be processed to determine whether the handset 11 is open or closed and, accordingly, may be used to control the operational mode of the handset 11.
As shown in
In an alternative embodiment, the laser 41 is comprised as part of the lid 13 and is coupled to the lid-end of the optical fibre 31. In this embodiment, the photo-diode 42 is comprised as part of the base and is coupled to the base-end of the optical fibre 31. Light transmitted through the optical fibre 31 may carry control signals for controlling the operation of the handset 11. The user display 15 may be a touch-sensitive display and may be operated by a user to select menu options from the display for operating the handset 11. Accordingly, the control signals transmitted through the optical fibre 31 may comprise, for example, information concerning a menu option selected by a user touching the display 15. This information may then be relayed to the micro-controller 28 and used for controlling the operation of the handset 11.
The photo-diode 42 is configured to detect the optical power received from the laser 41. Information concerning the optical power level detected at the base-end of the optical fibre 31 by the photo-diode 42 is supplied to the micro-controller 28 for controlling the operational mode of the handset 11. If the detected optical power level falls below the predetermined threshold value previously described, the handset 11 is determined to be closed and the micro-controller 28 switches the operational mode of the handset 11 to a power-saving mode. Alternatively, optical power level information supplied by the photo-diode 42 may be processed to control the operation of one or more components of the handset 11 directly.
Therefore, the optical power level detected by the photo-diode 42 is compared against a predetermined threshold value in order to determine whether the handset 11 is in the open or closed position. If the handset 11 is determined by the hinge-position detection apparatus to be in a closed position, the components of the handset 11 are configured to operate in a power saving mode. The handset 11 is thus able to increase the efficiency of its use of power and, accordingly, is able extend the standby time provided by a single charge of its battery (not shown).
Referring to
The second photodiode 61 is coupled to the micro-controller 28 such that information concerning the power of the optical light escaping from the fibre 31 may be relayed back to the controller 28 and processed to determine whether the handset 11 is in the open or closed position. Alternatively, the photodiode 61 may be configured to communicate the detected power level back to the controller 28 by wireless means, for example via a Bluetooth connection. In contrast with the previously described embodiments of the invention, the optical power level detected by the photo-diode 61 is inversely proportional to the radius of the hinge joint 14; as the radius of the bend in the optical fibre 31 decreases, the optical power level detected by the photo-diode 61 increases. By sensing the emitted light directly, the apparatus is able minimise the effect of errors due to losses caused by temperature fluctuations and aging of the optical fibre 31. In addition to determining whether the hinge joint 14 is open or closed, the relationship between the power level detected by the photo-diode 61 and the radius in the bend of the optical fibre 31 may be used to provide detailed information regarding the position of the hinge joint 14. For example, the optical power level detected by the photo-diode 61 may be used for calculating the angle of the hinge joint 14.
Alternatively, instead of the second photo-diode 61, the handset may comprise a different type of photo-sensitive device such as a photo-transistor or photo-resistor.
The controller 28 processes the optical power level information supplied by the photo-diode 61 to control the operational mode of the handset 11. If the optical power level detected by the photo-diode 61 increases above a predetermined threshold value, the handset 11 is determined to be closed and the micro-controller 28 switches the operational mode of the handset 11 to a power saving mode. Alternatively, the optical power level detected by the photo-diode 61 may be used to control the operational mode of one or more individual components of the handset 11 directly.
Referring to
The light inlet to the optical fibre 71 is positioned adjacent to the point of maximum emission of the first optical fibre 31 during bending thereof. The optical power level detected by the photo-diode 61 is used, either by the controller 28 or directly, to control the operational mode of the handset 11. If the optical power level detected by the photo-diode 61 increases above a predetermined threshold, the handset 11 is determined to be closed and the handset 11 is switched to a power saving mode.
The inclusion of the second optical fibre 71 provides more flexibility in the design of the handset 11 as the position of the second photo-diode 61 is not dictated by the position of maximum light emission from the first optical fibre 31. Accordingly, the photo-diode 61 may be positioned at a convenient position in the base 12 of the handset 11. Alternatively, the photo-diode 61 may be positioned in the lid 13 of the handset 11.
The optical fibre 31 may be surrounded by a protective jacket (not shown). In the described embodiments where light escaping from the bend in the fibre 31 is detected directly, if an LED is used instead of the laser 41, the jacket is removed at the point of maximum emission in order to allow the photo-diode 61 to detect the power level of the light escaping from the fibre 31. However, if the laser 41 is used as described, the protective jacket may be adapted such that the laser light is partially transmitted through the jacket. In this case, there is no need to remove the jacket in order for the photo-diode 61 to detect the light.
The control of the operational mode of the handset 11 has been described as being dependent on a detected power level of light at a photo-diode. However, the control of the handset could equally be dependent on a calculated signal-loss.
The implementation of the described hinge position detection apparatus involves minimal adaptation of the hardware of the handset 11. The components used for detection of the hinge's position are largely already present in many otherwise conventional mobile telephone handsets. Furthermore, apart from the optical fibre 31, no moving parts are used and, thus, the hinge-position detection apparatus can be considered to be extremely reliable. The hinge-position detection apparatus is not sensitive to electric or magnetic fields and will also not interfere with surrounding equipment, for example a GPS system, making use of such fields.
The above-described embodiments and alternatives may be used either singly or in combination to achieve the effects provided by the hinge-position detection apparatus. Although the hinge-position detection apparatus has been described with reference to a mobile telephone handset 11, the system is equally applicable to other types of electronic device which include a hinge section. These types of device include, for example, hand-held and lap-top computers, hand-held video games and personal digital assistants.
Claims
1. An apparatus comprising:
- a first member and a second member connected together to provide a pivoting joint;
- an optical wave-guide;
- a processor;
- a light emitter to transmit an optical signal through the optical wave-guide; and
- a light detector to detect the optical signal from the optical wave-guide;
- wherein the processor is configured to process the detected signal to determine the signal-loss through the optical wave-guide and to use the determined signal-loss to determine the position of the joint.
2. An apparatus according to claim 1, wherein the processor is configured to use the determined position of the joint to control the implementation of a power saving mode in the apparatus.
3. An apparatus according to claim 2, wherein if the determined signal-loss increases above a predetermined threshold, the joint is determined to be closed.
4. An apparatus according to claim 2, wherein if the determined signal-loss falls below a predetermined threshold, the joint is determined to be open.
5. An apparatus according to claim 1, wherein the optical wave-guide comprises an optical fiber.
6. An apparatus according to claim 1 comprising a mobile telephone.
7. An apparatus comprising:
- a lid and a base;
- a light emitter to transmit optical signals;
- a light detector for detecting the power level of optical signals; and
- an optical wave-guide;
- wherein the optical wave-guide is coupled to the light emitter and is connected between the lid and the base to provide a transmission medium for the optical signals, wherein the apparatus is configured to use the optical power level detected by the light detector to determine the position of the lid relative to the base, and wherein the apparatus is configured to use the position of the lid to employ a power-saving mode in the apparatus.
8. The apparatus according to claim 7, wherein the optical wave-guide comprises an optical fiber.
9. The apparatus according to claim 7, wherein if a determined signal-loss detected by the light detector increases above a predetermined threshold, the lid is determined to be closed.
10. The apparatus according to claim 7, wherein if a determined signal-loss detected by the light detector falls below a predetermined threshold, the lid is determined to be open.
11. A method comprising:
- transmitting an optical signal through an optical wave-guide;
- detecting an optical power level of an optical signal from the optical wave guide;
- determining the position of a lid of an apparatus relative to a base of the apparatus using the detected optical power level;
- employing a power saving mode in the apparatus based on the determined position of the lid of the apparatus.
12. The method of claim 11, wherein transmitting comprises transmitting the optical signal through an optical fiber.
13. An apparatus comprising:
- means for transmitting an optical signal through an optical wave-guide;
- means for detecting an optical power level of an optical signal from the optical wave-guide;
- means for determining the position of a lid of an apparatus relative to a base of the apparatus using the detected optical power level;
- means for employing a power saving mode in the apparatus based on the determined position of the lid of the apparatus.
14. The apparatus of claim 13, wherein the optical wave-guide comprises an optical fiber.
15. One or more computer readable media storing machine-readable instructions which, when executed by a computer apparatus, control the computer apparatus to perform a method comprising:
- determining the position of a lid of an apparatus relative to a base of the apparatus using a detected optical power level of an optical signal from an optical wave-guide;
- employing a power saving mode in the apparatus based on the determined position of the lid of the apparatus.
16. The computer readable media of claim 15, wherein the optical wave guide comprises an optical fiber.
17. The computer readable media of claim 15, wherein the detected optical power level comprises a signal loss detected by a light detector that detects the optical signal from the optical wave-guide.
18. The computer readable media of claim 17, wherein if the detected signal loss increases above a predetermined threshold, the lid is determined to be closed.
19. The computer readable media of claim 17, wherein if the detected signal loss decreased below a predetermined threshold, the lid is determined to be closed.
Type: Application
Filed: Jul 18, 2008
Publication Date: Jan 29, 2009
Applicant: NOKIA CORPORATION (Espoo)
Inventors: Ivan Kassamakov (Helsinki), Pasi Petteri Vihinen (Helsinki), Marcus Stefan Schorpp (Lempaala)
Application Number: 12/175,727
International Classification: G01J 1/04 (20060101);