Illuminative light communication system, lighting device and illuminative light source
Information received from a wired network terminal on the wall face, or the like, is delivered as a light signal from a light transmitting/receiving section of a light communication unit. A lighting fixture is provided with a light transmitting/receiving section where light is received from the light communication unit in order to acquire information, and a light emitting element emits illumination light modulated according to that information. A terminal can acquire the information by receiving the illumination light at a light transmitting/receiving section. Since communication is performed from the light communication unit to the terminal by irradiating light into the space, a convenient illumination light communication system requiring no communication cable or laying work of optical fibers can be constructed.
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This application is a continuation of U.S patent application Ser. No. 10/532,250 filed Oct. 23, 2003, as International Application No. PCT/JP03/013539, now pending, the contents of which, including specification, claims and drawings, are incorporated herein by reference in their entirety. This application claims priority from Japanese Patent Application Ser. No. 2003-084819 filed Mar. 26, 2003, the contents of which are incorporated herein by reference in their entireties.
BACKGROUND OF THE INVENTIONThe present invention aims to provide an illuminative light communication system that does not require electrical work for providing a cable or an optical fiber, and prevents problems such as restriction on bandwidths, radio wave radiation, and superimposition of noise from developing, which is different than power line communication, and a lighting device and an illuminative light source used for such illuminative light communication system.
According to such objective, an illuminative light communication system that carries out communication using illuminative light includes multiple lighting units that emit light for lighting and an optical communication unit that optically transmits data through the air to the lighting units. The lighting units receive light from the optical communication unit, thereby capturing data, and modulate emitted light in accordance with the data. According to such objective, an illuminative light communication system includes multiple lighting units that emit light for lighting; and an optical communication unit that optically transmits data through the air to one or more of the lighting units. The one or more of the lighting units receive light from the optical communication unit, thereby capturing data, and optically transmit the data through the air to another lighting unit. Each lighting unit modulates emitted light in accordance with the data received from the optical communication unit or another lighting unit and transmits the data via the modulated, emitted light.
With such structure, data to be transmitted to the lighting unit that allows communication through modulating illuminative light is transmitted through the air from the optical communication unit or another peripheral lighting unit. When using an optical fiber for optical communication, it is necessary to provide the optical fiber. On the other hand, it is unnecessary when carrying out optical communication via the air. As a result, the illuminative light communication system can be constructed very easily. In addition, different than power line communication, problems such as restriction on bandwidths and radio wave radiation do not develop.
Note that the plurality of lighting units allows optical bi-directional communication through the air with the optical communication unit or another lighting unit. In addition, since the plurality of lighting units includes a light receiving unit that receives light modulated in accordance with data emitted from a terminal device, which receives emitted light and thereby receives data, optical bidirectional communication between the terminal device and the plurality of lighting units is possible. Furthermore, the plurality of lighting units uses a semiconductor light emitting device such as an LED as an illuminative light source. The plurality of lighting units can be an indoor illumination lamp or a street lamp.
A lighting device used for such aforementioned illuminative light communication system includes one or multiple illuminative light emitting units that emits light for lighting, an optical transmitting/receiving unit for optically communicating through the air with a light emitting unit provided in a device, and a control unit that controls the illuminative light emitting unit in accordance with data received by the light transmitting/receiving unit, so as to modulate light emitted from the illuminative light emitting unit in accordance with the data, thereby transmitting the data.
With such structure, since there is no need to provide a cable or an optical fiber as described above, an illuminative light communication system can be constructed through simple electrical work such as replacement of an existing lighting device with a lighting device, according to the present invention.
Note that the optical transmitting/receiving unit is deployed in multiple positions in different communication directions, and data received by a certain light transmitting/receiving unit can be optically transmitted through the air from another light transmitting/receiving unit to the device. As a result, the lighting devices can be deployed freely, and data transmission is possible regardless of the positions of the lighting devices. In addition, the light transmitting/receiving unit allows bi-directional optical communication through the air with another device. Furthermore, since the plurality of lighting units includes a light receiving unit that receives light modulated in accordance with data emitted from a terminal device, which receives emitted light and thereby receives data, optical bidirectional communication among the terminal device and the plurality of lighting units is possible. The plurality of illuminative light emitting units uses a semiconductor light emitting device such as an LED as an illuminative light source. The plurality of lighting units can be an indoor illumination lamp or a street lamp.
Furthermore, an illuminative light source includes one or multiple illuminative light emitting devices that emits light for lighting, an optical transmitting/receiving unit for optically communicating through the air with a light emitting unit provided in another lighting unit, and a control unit that controls the illuminative light emitting device in accordance with data received by the optical transmitting/receiving unit, so as to modulate light emitted by the illuminative light emitting device in accordance with the data, thereby transmitting the data.
In this manner, by providing the optical transmitting/receiving unit and the control unit in the illuminative light source, construction of an illuminative light communication system using the existing lighting device, merely with simple electrical work such as replacement of a fluorescent lamp or an electric bulb with an illuminative light source according to the present invention becomes possible.
The optical transmitting/receiving unit is deployed in multiple positions in different communication directions. Data received by a certain light transmitting/receiving unit can be optically transmitted through the air from another light transmitting/receiving unit to another device. In addition, by structuring the optical transmitting/receiving unit so as to be able to change an optical transmission/reception direction, deployment of them on arbitrarily positioned lighting devices becomes possible. Furthermore, as with a lighting device using a fluorescent lamp, the optical transmitting/receiving unit is deployed in plural; one is used, in the case of the plurality of illuminative light emitting devices being arranged, to allow optical communication through the air with an adjacent illuminative light source, while the other is used to allow optical communication through the air with another illuminative light source provided in another lighting unit.
With such an illuminative light source, the optical transmitting/receiving unit can be structured allowing bidirectional optical communication through the air with another lighting unit. Furthermore, since the plurality of lighting units includes a light receiving unit that receives light modulated in accordance with data emitted from a terminal device, which receives emitted light and thereby receives data, optical bidirectional communication among the terminal device and the plurality of lighting units is possible. The illuminative light emitting device may be one or multiple semiconductor light emitting devices such as LEDs. Note that the illuminative light source may be an indoor illumination lamp or an outdoor street lamp.
Lighting elements are provided on a ceiling, or a pole is provided for illuminating light from above so as to prevent shadows across a certain area. There is an advantage for illuminative light communication in that high quality communication is possible because shadowing does not develop and high illuminative electric power is available.
Meanwhile, since lighting elements are provided in high places such as the ceiling as described above, there is a problem that it is difficult to carry out electrical work. For example, in the case of the aforementioned illuminative light communication, data to be transmitted must be sent to the lighting elements through illuminative light communication. A method of providing a cable or an optical fiber for a network may be considered as a method for transmitting data to lighting elements, for example. However, since new electrical work is necessary for providing a cable or an optical fiber, usage of illuminative light communication is not easy and is costly.
As with the present invention, a method of superimposing a signal on an electric wire for lighting and transmitting the resulting data to lighting elements, for example, has been considered as a method not requiring provision of additional cables or optical fibers. However, in the case of transmitting data by superimposing a signal on an electric wire, undesired radio emission may often develop or wireless communication may be interrupted when the frequency of the signal is high. In addition, there is another problem in that signals are easily influenced by motor noise and inverter noise.
As described above, there have been no preferred means for transmitting data to lighting elements for illuminative light communication, which has been an obstacle to illuminative light communication. The present invention provides a preferred means for transmitting data to each lighting element.
The optical communication device 501, which transmits to the lighting elements 502 data that is to be sent by them through illuminative light communication, is provided indoors. The optical communication device 501 is connected to the network, and transmits/receives data via the network. The network is a wired network, which is provided in offices, schools, plants, and homes, and is configured from an optical fiber, a coaxial cable, or a stranded wire, many of which are connected to an external telephone network or the Internet. A terminal of such network is often provided in a wall as shown in
The optical communication device 501 allows communication via the network as described above, and has the light transmitting/receiving unit 511 allowing optical communication among the lighting elements 502 through the air. According to the present invention, since optical communication is carried out through the air, an optical fiber is unnecessary. Needless to say, it is unnecessary to extend the communication cable 512 to the respective lighting elements 502. Since the lighting elements 502 are provided at a high position such as the ceiling, the optical communication device 501 may be provided at a lower position where the lighting elements 502 carrying out communication cannot be blinded.
The light transmitting/receiving unit 511 includes a light emitting device and a light reception device, emits modulated light through control of the light emitting device to modulate in accordance with data, and transmits data to the lighting elements 502. In this example, it is desirable that lights emitted from the light emitting device may be received by the multiple lighting elements 502. Therefore, light with poor directivity is preferable. Alternatively, it is possible to output to the respective lighting elements 502 emitted lights with high directivity, which allows identification of each lighting element 502.
The light reception device receives light emitted from the light transmitting/receiving units 522 of the lighting elements 502, thereby receiving data transmitted from the lighting elements 502. Note that since illuminative light emitted from the lighting elements 502 is received, it is necessary to separate and capture data from the light emitted from the light transmitting/receiving units 522 of the lighting element 502. When it is unnecessary to receive data from the lighting elements 502, the light reception device is unnecessary.
With such structure, the optical communication device 501 allows communication via the wired communication cable 512 and functions as a gateway, which carries out conversion for optical communication. In addition, through communication with multiple lighting elements 502, it also functions as a base station for wireless (optical) communication. Note that light used by the light transmitting/receiving unit 511 for communication is not limited to visible light, and infrared light is also available.
The lighting elements 502, according to the present invention, are provided on the ceiling, for example, and illuminates indoors by light emitted from the light emitting device. The lighting elements 502 are each provided with light transmitting/receiving units 522 including light emitting devices and light reception devices. According to this embodiment, optical communication with the optical communication device 501 through the air is carried out. The light emitting devices should be formed so as to allow pinpoint reception of light from the light transmitting/receiving unit 511 of the optical communication device 501 by providing a lens system, for example. Needless to say, direction should be appropriately changeable in consideration of light incident direction. The light emitting devices are provided for transmitting data to the optical communication device 501 from the lighting elements 502, and should allow pinpoint transmission of light to the light transmitting/receiving unit 511 of the optical communication device 501. For example, when using laser diodes (LDs), a rectilinear progression characteristic may improve, and identifiability of the optical communication device 501 may be improved by coherent light. These light transmitting/receiving units 522 allow bidirectional data communication among the lighting elements 502 and the optical communication device 501.
The lighting elements 502 are each provided with a controller not shown in the drawing. The light transmitting/receiving units 522 receive and demodulate light, and the resulting demodulated data is transmitted to corresponding controller. The controller controls the light emitting devices 521 to modulate in accordance with received data and emits illuminative light modulated in accordance with that data. This allows illuminative light data transmission from the lighting elements 502 to the terminal device 503.
In the example shown in
The light reception devices 523 are used for receiving light from the terminal device 503. They receive and demodulate modulated light emitted from the terminal device 503, and the controller can then capture data transmitted from the terminal device 503. The captured data may be optically transmitted from the light transmitting/receiving units 522 to the optical communication device 501, and then to the network. Those light reception devices 523 allow bidirectional communication among the lighting elements 502 and the terminal device 503. Note that those light reception devices 523 may receive infrared light, other than visible light. In addition, a structure such that an antenna is provided instead of the light reception devices 523 for radio wave data reception from the terminal device 503 is possible. In the case of a broadcast system, the light reception devices 523 are unnecessary.
The terminal device 503 is a data terminal comprising the light transmitting/receiving unit 531. The light transmitting/receiving unit 531 receives and demodulates illuminative light, thereby capturing data. In addition, the light transmitting/receiving unit 531 is controlled to emit light modulated in accordance with data, thereby transmitting data from the terminal device 503 to the lighting elements 502. The terminal device 503 may be provided in an arbitrary position as long as it is illuminated by the lighting elements 502. Accordingly, communication is possible even if the terminal device 503 is movable. In addition, since the lighting elements are typically provided so as to prevent shadows, and illuminative light has large electric power, high quality and high speed communication is possible. Furthermore, illuminative light may be used safely without adversely influencing the human body such as eyes as with infrared rays.
In the aforementioned first embodiment, the optical communication device 501 controls the light transmitting/receiving unit 511 to emit light, thereby optically transmitting data, which has been transmitted from the network, through the air. The respective light transmitting/receiving units 522 of the lighting elements 502 receive light emitted from the light transmitting/receiving unit 511 of the optical communication device 501, thereby receiving data. The respective lighting elements 502 then control the light emitting devices 521 to modulate in accordance with data captured through reception of light by the light transmitting/receiving units 522, and thereby outputting the modulated illuminative light. The terminal device 503 receives and demodulates the modulated illuminative light, and thus the terminal device 503 can receive data.
On the other hand, the light transmitting/receiving unit 531 of the terminal device 503 emits light modulated in accordance with data in the terminal device 503. The light reception devices 523 of the lighting devices 502 then receive that emitted light, thereby receiving that data. The light transmitting/receiving units 522 of the lighting devices 502 then emit light modulated in accordance with that received data, transmitting the data to the optical communication device 501. In the optical communication device 501, the light transmitting/receiving unit 511 receives modulated light from the lighting elements 502 and converts it to electrical signals, transmitting the resulting signals to the network. This allows data transmission from the terminal device 503 to the network.
In the second embodiment, as shown in
In the example shown in
The light transmitting/receiving units 522 are used for optical communication among the respective lighting elements 502 through the air. This allows communication from the optical communication device 501 to the respective lighting elements 502 without providing a communication cable or an optical fiber. In addition, with the first embodiment, it can be considered that light intensity for communication among the optical communication device 501 and the lighting elements 502 attenuates if the lighting elements 502 are provided at a distance from the optical communication device 501. On the other hand, with the second embodiment, since the respective lighting elements 502 are provided at almost regular intervals, communication quality does not decrease due to locations of the lighting elements 502. Furthermore, since data is transmitted through communication among the lighting elements 502, even the lighting elements 502 provided within an area visible from the optical communication device 501 may be used for illuminative light communication, which is possible by communicating indirectly with the optical communication device 501 through communication with another lighting element 502.
The light transmitting/receiving units 522 allow bi-directional communication among the lighting elements 502 and among the lighting elements 502 and the optical communication device 501. Note that in the case of unidirectional communication as with a broadcast system, the light transmitting/receiving units 522 may be constituted by either light emitting devices or light reception devices, and light emitting devices and light reception devices of the respective lighting elements 502 for data communication should be provided facing one another.
In the second embodiment, the rod illuminative light sources 542 with the same shape as strip lights as shown in
Needless to say, the shape of the illuminative light source is not limited to the same rod shape as strip lights and may have a circular shape as with circular fluorescent lamps. Alternatively, an electric bulb-shaped illuminative light source is available, as described later.
For example, the suspended lighting elements 502 are often provided over each customer's seat in a store. The structure shown in
In the example shown in
In addition, the inter-lighting element light transmitting/receiving units 553 are provided for communicating with illuminative light sources 551 other than the adjacent illuminative light sources 551 and the optical communication device 501. The inter-lighting element light transmitting/receiving units 553 should be formed such that the length and orientation thereof are adjustable to accommodate various lighting elements. Note that in
Such illuminative light sources 551 are fixed replacing the existing fluorescent lamps of the lighting elements. In this case, the illuminative light sources 551 should be attached directly to the sockets to which fluorescent lamps are inserted. As a result, electric power may be supplied to the illuminative light sources 551 from the sockets of the lighting elements. Illuminative light data transmission is possible by regulating the length and orientation of the inter-lighting element light transmitting/receiving units 553.
The example shown in
The example shown in
Note that
The light reception devices 523 receive light (visible light or infrared light) emitted from the light transmitting/receiving unit 511 of the optical communication device 501, thereby receiving data from the optical communication device 501. Light emitted from the light emitting devices 521 is modulated in accordance with the received data, and the resulting modulated illuminative light is emitted. The terminal device 503 then receives and demodulates the modulated illuminative light, allowing the terminal device 503 to receive data.
On the other hand, in the case of transmitting data from the terminal device 503, the light reception devices 523 in the illuminative light sources 551 receive and demodulate modulated light emitted from the terminal device 503, and then data from the terminal device 503 is transmitted to the illuminative light sources 551. Light emitted from the light emitting devices 521 is modulated in accordance with the received data, and the resulting modulated illuminative light is emitted. If the light transmitting/receiving unit 511 of the optical communication device 501 receives and demodulates the modulated illuminative light, data is transmitted from the terminal device 503 to the optical communication device 501.
In this manner, in the fourth embodiment, both the optical communication device 501 and the terminal device 503 emit light to the illuminative light sources 551, and receive illuminative light emitted from the illuminative light sources 551. This allows use of illuminative light having large electric power and reduction in influences of shadowing since the lighting elements are provided in the ceiling where shadows are difficult to generate, thereby providing favorable communication rather than the case of direct optical communication between the optical communication device 501 and the terminal device 503. Needless to say, it is unnecessary to extend a communication cable or an optical cable to the lighting elements 502.
Note that in the example shown in
According to the present invention, the light transmitting/receiving units 522 are provided in the street lights 561, and optical data communication among the street lights 561 is provided through the air as with the aforementioned second embodiment. This allows data transmission to the respective street lights 561 and illuminative light data transmission by the street lights 561. Such structure is economical since only electrical work for the respective street lights 561 is necessary without providing a communication cable or an optical fiber.
Note that the intervals between the street lights 561, for example, of approximately 30 m on an expressway are longer than in the aforementioned case of indoors. However, optical communication is sufficiently possible. In addition, due to the present topology or structure of the road, the orientation of the light transmitting/receiving units 522 must be regulated so as for those units to face adjacent street lights. This is not very difficult as long as they have typical intervals between adjacent street lights. Furthermore, a problem that the field of vision may be obstructed by mist is expected. However, this is not a significant problem since the intervals are approximately 30 m.
An example of optical communication among the street lights provided on the road is shown as an outdoor network herein, and an application according to the present invention is not limited to this. For example, it is applicable to taxiway lights for air crafts or illumination lamps in event halls.
Several embodiments and modified examples according to the present invention have been described above. In the aforementioned description, data is transmitted from the optical communication device 501 to the lighting elements 502, the illuminative light sources 551, or the street lights 561 (referred to as lighting elements and the like). It is unnecessary for the respective lighting elements and the like to transmit received data as is through illuminative light. For example, a structure such that an address or an ID is attached to a header of data to be transmitted and that the lighting elements and the like select data in accordance with that header and transmit the selected data via illuminative light is possible. In addition, the lighting elements and the like, which function as a relay or a router and are not used for illuminative light data communication, may be provided.
As described above, according to the present invention, when each of lighting elements and illuminative light sources are used for optical communication, data is transmitted thereto through the air. Therefore, electrical work for providing a communication cable or an optical fiber is unnecessary, allowing constituting an illuminative light communication system at low cost. In this case, the system may be structured using existing lighting elements, allowing further reduction in cost. In addition, different from power line communication, optical communication prevents problems such as constraints on bandwidth, radio wave radiation, and superimposition of noise from developing, allowing high-quality data communication.
Claims
1. An illuminative light communication system, comprising:
- a plurality of lighting units that emits light for lighting; and
- an optical communication unit that optically transmits data through the air to the lighting units; wherein the lighting units receive light from the optical communication unit, thereby capturing data, and modulate emitted light in accordance with the data.
2. An illuminative light communication system, comprising:
- a plurality of lighting units that emits light for lighting; and
- an optical communication unit that optically transmits data through the air to one or more of the lighting units; wherein the one or more of the lighting units receive light from the optical communication unit, thereby capturing data, and optically transmit the data through the air to another lighting unit; and each lighting unit modulates emitted light in accordance with the data received from the optical communication unit or another lighting unit and transmits the data via the modulated, emitted light.
3. The illuminative light communication system according to either claim 1 or claim 2, wherein the plurality of lighting units is an indoor illumination lamp.
4. The illuminative light communication system according to claim 2, wherein the plurality of lighting units is a street lamp.
5. The illuminative light communication system according to either claim 1 or claim 2, wherein the plurality of lighting units allows optical bidirectional communication through the air with the optical communication unit or another lighting unit.
6. The illuminative light communication system according to claim 5, wherein the plurality of lighting units comprises a light receiving unit that receives light modulated in accordance with data emitted from a terminal device, which receives emitted light and thereby receives data, and allows optical bidirectional communication between the terminal device and the plurality of lighting units.
7. The illuminative light communication system according to either claim 1 or claim 2, wherein the plurality of lighting units uses a semiconductor light emitting device as an illuminative light source.
8. A lighting device, comprising:
- one or a plurality of illuminative light emitting units that emits light for lighting;
- an optical transmitting and receiving unit for optically communicating through the air with a light emitting unit provided in a device; and
- a control unit that controls the illuminative light emitting unit in accordance with data received by the light transmitting and receiving unit, so as to modulate light emitted from the illuminative light emitting unit in accordance with the data, thereby transmitting the data.
9. The lighting device according to claim 8, wherein the optical transmitting and receiving unit is deployed in a plurality of positions in different communication directions; and the control unit controls so that data received by a certain light transmitting and receiving unit can be optically transmitted through the air from another light transmitting and receiving unit to the device.
10. The lighting device according to claim 8, wherein the illuminative light emitting unit lights indoors.
11. The lighting device according to claim 8, wherein the illuminative light emitting unit lights the road.
12. The lighting device according to claim 8, wherein the optical transmitting and receiving unit allows bidirectional optical communication through the air with the device.
13. The lighting device according to claim 12, further comprising a light receiving unit that receives light modulated in accordance with data emitted from a terminal device, which receives light emitted from the light emitting unit, thereby receiving data; wherein bidirectional communication with the terminal device is carried out via light.
14. The lighting device according to claim 8, wherein the illuminative light emitting unit comprises one or a plurality of semiconductor light emitting devices as an illuminative light source.
15. An illuminative light source, comprising:
- one or a plurality of illuminative light emitting devices that emits light for lighting;
- an optical transmitting and receiving unit for optically communicating through the air with a light emitting unit provided in another lighting unit; and
- a control unit that controls the illuminative light emitting device in accordance with data received by the optical transmitting and receiving unit, so as to modulate light emitted by the illuminative light emitting device in accordance with the data, thereby transmitting the data.
16. The illuminative light source according to claim 15, wherein the optical transmitting and receiving unit is deployed in a plurality of positions in different communication directions; and the control unit controls so that data received by a certain light transmitting and receiving unit can be optically transmitted through the air from another light transmitting and receiving unit to the another device.
17. The illuminative light source according to claim 15, wherein the optical transmitting and receiving unit is structured to be capable of changing an optical transmission and a reception direction.
18. The illuminative light source according to claim 15, wherein the optical transmitting and receiving unit is deployed in plural; one is used, in the case of the plurality of illuminative light emitting devices being arranged, to allow optical communication through the air with an adjacent illuminative light source, while the other is used to allow optical communication through the air with another illuminative light source provided in another lighting unit.
19. The illuminative light source according to claim 15, wherein the optical transmitting and receiving unit carries out bidirectional optical communication through the air with the another lighting unit.
20. The illuminative light source according to claim 19, further comprising a light receiving unit that receives light modulated in accordance with data emitted from a terminal device, which receives light emitted from the light emitting unit, thereby receiving data; wherein bidirectional optical communication is carried out through the air with the terminal device.
21. The illuminative light source according to claim 15, wherein the illuminative light emitting device is one or a plurality of semiconductor light emitting devices.
Type: Application
Filed: Aug 5, 2009
Publication Date: Dec 3, 2009
Applicant: Nakagawa Laboratories, Inc. (Tokyo)
Inventors: Masao Nakagawa (Kanagawa), Toshihiko Komine (Shizuoka), Shinichiro Haruyama (Kanagawa)
Application Number: 12/461,226
International Classification: H04B 10/10 (20060101);