Illumination light communication device

Technical Field

0001The present invention relates to a technology that contributes to illuminative light communication.

Background Art

0002In recent years, a radio wave communication system has become available along with portable terminals. Recently, shorter wavelength infrared rays have been widely used due to available frequency depletion. Other than available frequency depletion; radio waves may influence medical devices or various precision equipment. Moreover, there is fear that infrared rays may adversely influence the human body (e.g., eyes). As a result, optical communication is in the spotlight as a safe communication method.

0003Meanwhile, white LEDs are developed owing to the success of development of blue LEDs. The features of white LEDs are: extremely lower power consumption than that of conventional incandescent lamps or fluorescent lamps, small size, and long life. Accordingly, use of white LEDs as a illuminative light source is considered. Another feature of white LEDs is a fast response speed relative to supplied power. Paying attention to these features, a study of electrically controlling blinking or light intensity and thereby transferring a signal has been conducted.

0004A study of integration of such signal transfer using white LED lights with the aforementioned power line communication system has been conducted. For example, a proposal regarding that study has been disclosed in INTEGRATED SYSTEM OF WHITE LED VISIBLE-LIGHT COMMUNICATION AND POWER-LINE COMMUNICATION written by inventors: <nplcit id="ncit0001" npl-type="s"><text>T. Komine, Y. Tanaka, and M. Nakagawa, Institute of Electronics, Information, and Communication Engineers Technical Research Report, The Institute of Electronics, Information, and Communication Engineers, March 12, 2002, Vol. 101, No. 726, pp. 99 - 104</text></nplcit>. Since such system utilizes lights, there are no effects on the human body, allowing safe communication. In addition, other applications are expected.

Disclosure of the Invention

0005The present invention has been developed considering the above-described problems and aims to provide various structures and applications for illuminative light communication.

0006A first aspect of the present invention aims to provide a broadcast system that broadcasts a great number of pieces of data through power line communication and illuminative light signal communication using LEDs, and to provide an electric bulb for lighting that is used for such broadcast system.

0007According to such objective, the broadcast system includes an LED light source for lighting, a power line that supplies electric power to the LED light source, a data modulator that modulates and multiplexes multiple pieces of data, superimposes the resulting signal on an electric power waveform, and then transmits the resulting superimposed signal waveform to the power line, and a filter unit that selectively separates one or more of multiple pieces of modulated data on the power line so as to control light intensity or blinking of the LED light source. Data is transmitted through changes in light intensity or blinking of the LED light source.

0008According to a first aspect of the present invention, multiple pieces of data are superimposed on a power line and then transmitted as described above. For example, control of light intensity or blinking of an LED source in accordance with data selected by a selector, which is provided for selecting data as a filter unit, allows selective optical data broadcast from the LED source. A structure such that data is selected using a physical switch or selected in conformity with instruction data on a power line, or selected by a receiver is possible.

0009More specifically, a structure such that a data modulator frequency division multiplexes multiple pieces of data, and transmits the resulting data via the power line and that the filter unit selects one of multiple band pass filters with different frequency bandwidths, which constitute a filter unit, and separates data is possible. Alternatively, a structure such that the data modulator time division multiplexes multiple pieces of data, adds tag data to the resulting divided data, and transmits the resulting data and that the filter unit identifies data based on the tag data and selectively separates data is possible.

0010An electric bulb, which is used for such broadcast system, receives supplied electric power, and emits light for lighting. This electric bulb includes an LED light source for lighting, and a filter unit that selectively separates one or more of multiple pieces of modulated data, which is superimposed on supplied electric power, and controls light intensity or blinking of the LED light source. Available electric power is AC power. In the case of using AC power, an AC-DC converter is provided converting AC power to DC power. Data component separated by the filter unit is then superimposed on the DC power, which is provided by the AC-DC converter, and the LED light source is driven by the resulting superimposed DC power. Data on the power line can be optically transmitted merely by replacing an available electric bulb with such electric bulb. Accordingly, data can be broadcast using existing lighting devices as is without any electrical work, such as replacement of a lighting device.

Brief Description of the Drawings

0011<ul id="ul0001" list-style="none" compact="compact"><li>FIG. 1 is a block diagram of a broadcast system, according to a first embodiment of a first aspect of the present invention;</li><li>FIG. 2(A) is a diagram describing an exemplary signal waveform of an electric wire; FIG. 2(B) is a partially magnified diagram thereof,</li><li>FIG. 3 is a block diagram of a broadcast system, according to a second embodiment of the first aspect of the present invention;</li><li>FIG. 4(A) is an explanatory diagram of an electric bulb of an embodiment applicable to the broadcast system, according to the first aspect of the present invention; FIG. 4(B) is a diagram describing how to detach the electric bulb;</li><li>FIG. 5 is a diagram describing a first application of the first aspect of the present invention;</li><li>FIG. 6 is a diagram describing a second application of the first aspect of the present invention;</li></ul>

Best Mode for Carrying Out the Invention

0012To begin with, the present invention is described forthwith. It relates to a broadcast system that optically broadcasts data, and an electric bulb preferable for the same. ,

0013A power-line communication system has been studied as one of communication systems. The power line communication system transmits data using a power line, which is provided in a house or a building as a signal transmission medium. The power line is a very popular infrastructure, which basically allows communication among devices connected via the power line. Meanwhile, communication among devices, such as portable terminals, not connected via the power line is impossible. The first aspect of the present invention provides a broadcast system, which broadcasts data to many devices not connected via the power line.

0014FIG. 1 is a block diagram of the broadcast system, according to the first embodiment of the first aspect of the present invention. In the drawing, 101 denotes a data source, 102 denotes a power line modulator, 103 denotes a power line, 104 and 105 denote outlets, 106 denotes an LED lighting element, 107 denotes a light reception terminal, 111 denotes an AC-DC converter, 112 denotes a band pass filter, 113 denotes a selector, 114 denotes a superimposing unit, and 115 denotes an LED group. The data source 101 may be constituted by apparatus, such as a TV, a CATV, a radio, and a tuner or a receiver for the CATV, as well as a computer, which are capable of outputting various data. Accordingly, what is broadcast may be various data, such as picture data, music data, sound data, image data, and character data. Moreover, what is broadcast may be a single piece of data or multiple pieces of data; it is assumed here that multiple pieces of data are output.

0015The power line modulator 102 modulates and multiplexes multiple pieces of data output from the data source 101, superimposes the resulting data on an electric power waveform, and then transmits the resulting superimposed data waveform to the power line 103. Note that ordinary power-line communication systems often include a demodulating means, which allows bi-directional communication; however, such a demodulating means is unnecessary for a broadcast system because the broadcast system allows only unidirectional communication. In addition, according to an exemplary data multiplexing method, frequency division is carried out for multiplexing.

0016Typically, the power line 103 is an electric wire, which is provided indoors or outdoors. An existing electric wire may be used as the power line 103. In addition, the outlets 104 and 105 are fixed to a wall surface in order to receive power from the power line 103. Existing outlets may be used as the outlets 104 and 105. In the exemplary structure shown in FIG. 1, the power-line modulator 102 is inserted into the outlet 104, and the LED lighting element 106 is inserted into the outlet 105. Needless to say, the power line 103 and the outlets 104 and 105 may be newly provided. Note that with this exemplary structure, it is assumed that AC electric power used as general commercial electric power is supplied.

0017The LED lighting element 106, which is connected to the power line 103, illuminates in the vicinity thereof. In the case of indoors, for example, it is fixed to the ceiling. Other various lighting elements, such as a spotlight, are available for various applications. In this exemplary structure, the LED lighting element 106 includes the AC-DC converter 111, the band pass filter 112, the selector 113, the superimposing unit 114, and the LED group 115.

0018The AC-DC converter 111 converts AC electric power supplied from the power line 103 to DC electric power, which is supplied to the LED group 115 to emit light. A conventional AC-DC converter may be used as the AC-DC converter 111. In addition, the AC-DC converter 111 also makes an adjustment to the operating voltage for the LED group 115. Furthermore, it supplies electric power needed for operation of the band pass filter 112. Note that since a modulated data waveform is superimposed on the power line 103 as described above, it is desirable that a smoothing circuit, for example, should be used for preventing development of the data waveform on a DC waveform.

0019The band pass filter 112 is provided for extracting a data signal superimposed on the power line 103. As described above, with this exemplary structure, since individual pieces of data are multiplexed through frequency division, the band pass filter 112, which allows only a specific frequency to pass through, can selectively isolate single data from multiple pieces of data. In the example shown in FIG. 1, multiple band pass filters, each allowing a different frequency to pass through, are arranged in parallel. Alternatively, a band pass filter, which is capable of changing frequency bandwidths passed therethrough, may be arranged. Note that a separated data waveform may be biased, trimmed, or amplified.

0020The selector 113 selects one or more out of multiple filters in the band pass filter 112, thereby allowing selection of data to be optically distributed. This selection may be manually made; alternatively, it may be made using another method or by selectively demodulating a transmitted control signal of a specific frequency and then making a selection of a filter based on that control signal. Alternatively, a structure capable of changing frequencies that pass through the band pass filter 112 may be used, and the selector 113 may set a frequency corresponding to data to be distributed to the band pass filter 112. In FIG. 1, the selector 113 is provided before the band pass filter 112; alternatively, it may be provided thereafter. In addition, in the case of that structure capable of changing a frequency band that the band pass filter 112 passes, the selector 113 may set a frequency bandwidth for the band pass filter 112 in conformity with a control signal of a specific frequency. Furthermore, when the LED lighting element 106 broadcasts only data of a fixed frequency, the selector 113 is unnecessary, and only the band pass filter 112 that passes signals of a fixed frequency bandwidth should be provided.

0021The superimposing unit 114 superimposes a data signal extracted by the band pass filter 112 on a converted DC electric power waveform, which is provided by the AC-DC converter 111. This allows change in voltage applied to the LED group 115 in conformity with the resulting data signal, and control of light intensity or blinking of the LED group 115. For example, in the case of making the LED group 115 blink, a structure such that electric power from the AC-DC converter 111 is controlled to turn on and off in conformity with a signal from the band pass filter 112 is possible.

0022The LED group 115 is basically an LED light source for lighting, which may be constituted by a great number of white LEDs, for example. Needless to say, a structure with a set of red LEDs, a set of blue LEDs, and a set of green LEDs is possible. Electric power from the superimposing unit 114 is supplied to the LED group 115, which then emits light. Since LEDs have excellent response characteristics, they can output optical data through changing light intensity and/ or blinking in conformity with a data signal. In this case, since high-speed change in light intensity and/ or high-speed blinking is unperceivable to the human eye, LEDs may be used for lighting as they are.

0023The light reception terminal 107 has a light reception means, receives light illuminated from the LED lighting element 106, extracts a data signal therefrom and demodulates it into data. An arbitrary device including a light reception means may be used as the light reception terminal 107, and it may be a variety of apparatus, such as a personal computer, a portable terminal, a cellular phone, an audio device having a light reception means, or a display apparatus such as a television.

0024An exemplary operation of the broadcast system, according to the first embodiment of the first aspect of the present invention, is briefly described forthwith. Various contents to be broadcasted are prepared as the data source 101. For example, in addition to data from a computer, various kinds of data from a TV, a CATV, and a radio are prepared for respective applications.

0025The power-line modulator 102 modulates and multiplexes multiple pieces of data output from the data source 101, superimposes the resulting data on an electric power waveform, and then transmits the resulting superimposed data waveform to the power line 103. FIG. 2 is a graph describing an exemplary signal waveform of an electric wire. In this example, a commercial AC electric power supply (50 Hz/ 60 Hz) is used, and a data signal waveform is superimposed on an electric power waveform. A data signal waveform, which is smaller than an electric power waveform, is superimposed so as to avoid adversely influencing other devices. A magnified view of FIG. 2(B) shows an example of data modulated using a method such as binary phase shift keying (BPSK) and then superimposed on the electric power waveform. Note that an existing electric wire may be used as the power line 103. In addition, receiving electric power from an outlet, separating and using data allows provision of data as with the case of using conventional power-line communication.

0026Electric power and data are transmitted to the LED lighting element 106 from the outlet 105 via the power line 103. The LED lighting element 106 receives from the outlet 105 electric power on which a signal waveform is superimposed. The AC-DC converter 111 rectifies and supplies DC electric power, which is then used to drive the LED group 115, and transmits it to the superimposing unit 114. On the other hand, a filter in the band pass filter 112 selected by the selector 113 passes and outputs only a predetermined frequency component. At this time, that component may be biased, trimmed, or amplified as necessary.

0027The superimposing unit 114 then combines DC electric power waveform, which is provided through conversion by the AC-DC converter 111, and a data signal extracted by the band pass filter 112, and then applies the resulting composite data signal waveform to the LED group 115. Voltage applied to the LED group 115 varies depending on the composite data signal waveform. As a result, light intensity of the LED group 115 changes depending on the data signal waveform, which allows transmission of data.

0028Light emitted from the LED group 115 is received by a light reception device on the light reception terminal 107 side. The light reception terminal 107 can receive data by detecting and demodulating changes in received light intensity. In this manner, of pieces of data provided from the data source 101, one selected by the LED lighting element 106 is transferred along with illuminative light; the light reception terminal 107 then receives that transferred data. In this case, the light reception unit in the light reception terminal 107 may not exactly face the LED lighting element 106 (LED group 115); however, it is possible to capture a data signal as long as a certain degree of illuminative light can be received since communication quality is excellent. This is because the LED illuminative light is used for lighting and apparent transmitted electric power is extremely large. When a signal with a similar signal intensity is transmitted using conventionally available infrared rays, influences on the human body (e.g., eyes) are unavoidable. In this regard, it is advantageous to optically transmit data.

0029Note that: only a single LED lighting element 106 is shown in the drawing; however, if multiple LED lighting elements 106 are arranged at a short distance, this arrangement is resistant to shadowing and can accommodate movement as long as the same data is selected and broadcast. On the other hand, even if an LED lighting element 106 for selecting and broadcasting data exists at a short distance, since light from another LED lighting element attenuates as long as reception is made near an LED lighting element 106, its influence becomes weak. In addition, if a problem of interference with other LED lighting elements develops, data from the data source 101 should be modulated using an interference resistant modulation method, such as on-off keying, return-to-zero (OOK-RZ) or orthogonal frequency division multiplexing (OFDM).

0030In addition, in the exemplary structure shown in FIG. 1, the AC-DC converter 111 and the band pass filter 112 are provided in the LED lighting element 106. However, this structure is not limited to this; alternatively, those circuits may be fixed in a light on/off wall switch, and DC electric power with a superimposed data waveform may be supplied between the switch and the LED lighting element 106. In this case, a switch to be used as the selector 113 may be fixed to a wall along with a light on/off switch. Needless to say, arrangement of respective units is not limited to those examples, and may arbitrarily be made.

0031FIG. 3 is a block diagram of a broadcast system, according to a second embodiment of the first aspect of the present invention. In the drawing, the same reference numerals are given to the same parts as those in FIG. 1, and repetitive descriptions thereof are thus omitted. 116 denotes a band pass filter, 117 denotes a determination unit, and 118 denotes a selector. In this exemplary structure, an identification code (such as IP, PN code) is assigned to each LED lighting element 106 or each piece of data, and only a specific piece of data is selected based on its own identification code and then broadcast.

0032A power line modulator 102 divides multiple pieces of data from a data source 101 into packets, adds a header to the top of each packet, carries out time division multiplexing, and superimposes the resulting packets of data on the electric power waveform. The header includes an identification code.

0033The LED lighting element 106 includes the band pass filter 116, the determination unit 117, and the selector 118 as well as an LED group 115 and an AC-DC converter 111. The band pass filter 116 removes AC components from electric power and separates data signal components. In this exemplary structure, all signals of multiple pieces of data pass through the band pass filter 116.

0034The determination unit 117 extracts a header from data signals separated by the band pass filter 116, compares it with a predetermined identification code, and determines whether or not the transmitted data should be optically transmitted. If YES, the selector 118 then selects a data signal and outputs it to a superimposing unit 114. The superimposing unit 114 superimposes a signal passed through the selector 118 on a DC electric power waveform, which is provided through conversion by the AC-DC converter 111, and supplies the resulting superimposed signal to the LED group 115. Subsequently, as with the above-mentioned first embodiment, light intensity or blinking of the LED group 115 is controlled based on a data signal, which allows optical data transmission. In addition, lighting comes from lights emitted by the LED group 115.

0035According to the second embodiment, by assigning an identification code to, for example, each LED lighting element 106, data broadcast by each LED lighting element 106 can be controlled on a transmitter side from which data is transmitted to the power line 103. Moreover, a structure that allows assignment of separate identification codes allows selection of data to be broadcast from each LED lighting element 106. In this case, multiple identification codes may be assigned, and multiple pieces of data may be selected to be optically transmitted.

0036The second embodiment may be structured in different ways as with the above-mentioned first embodiment. In addition, there are the same advantages as those of the above-mentioned first embodiment.

0037In addition to those embodiments, without selecting data to be broadcast using illuminative light, all data transmitted via the power line 103 may be optically broadcast, and broadcast data may be received and selected on a terminal side.

0038FIG. 4 is an explanatory diagram of an electric bulb applicable to the broadcast system, according to an embodiment of the first aspect of the present invention. In the drawing, 121 denotes an electric bulb, 122 denotes a base, and 123 denotes a socket. The example shown in FIG. 4 may be applied as a part of an LED lighting element 106 in the broadcast system, according to each embodiment described above. Typically, a lighting element including an attachable incandescent bulb has been available. As shown in FIG. 4(B), the socket 123 is arranged on the ceiling or the like, and electrical connection can be made by inserting the base 122 of the electric bulb 121 into the socket 123. In this example, existing facility in the interconnect portion extending until the power line 103 or the socket 123 is used as is, and as shown in FIG. 4(A), the internal structure of the LED lighting element 106, according to the first or the second embodiment described above, is accommodated in the electric bulb 121. For example, that structure may be accommodated in the base 122 of the electric bulb 121. In addition, differing from conventional point light sources with a filament such as an incandescent bulb, since a great number of LEDs are deployed in the same plane, a circuit can be deployed therebehind.

0039Use of such electric bulb 121 and only replacement of a typical incandescent bulb with the electric bulb 121, according to the first aspect of the present invention, allows use of the electric bulb 121 as an optical data transmission source.

0040Needless to say, variously shaped conventional electric bulbs may be used other than the shape as shown in FIG. 4. The shape of the electric bulb 121, according to the first aspect of the present invention, is not limited to that in FIG. 4, and it may be an arbitrary shape. For example, the electric bulb 121 may be structured with a form of linearly arranged LEDs such as a fluorescent lamp.

0041Next, several applications of the broadcast system, according to the first aspect of the present invention, are described forthwith. FIG. 5 is a diagram describing a first application, according to the first aspect of the present invention. In the drawing, 131 denotes LED lighting elements, 132 denotes artworks, and 133 denotes a light reception terminal. The example in FIG. 5 shows a case of the broadcast system according to the first aspect of the present invention used in an art gallery or a museum. In an art gallery or a museum, lighting such as spotlighting is used for each artwork or showpiece (hereafter, referred to as artworks 132) and description thereof. The LED lighting elements 131, according to the first aspect of the present invention, are used as lighting elements for illuminating the artworks 132. On the other hand, descriptive data for the artworks 132 is superimposed on a power line 103 via which electric power is supplied to the LED lighting elements 131, and the resulting superimposed data is transmitted. In this case, descriptive data for a great number of artworks 132 is superimposed on the power line 103. Each LED lighting element 131, which is provided for each artwork 132, selectively extracts descriptive data for each artwork, and controls light intensity or blinking of illuminative light as described above, optically transmitting the descriptive data.

0042When an appreciator takes out the light reception terminal 133 in front of an artwork 132, light is illuminated to the light reception terminal 133 and changes in the light intensity or blinking are captured and then demodulated, which allow the appreciator to read the descriptive data for the corresponding artwork 132. In addition, when the appreciator moves in front of the next artwork, descriptive data for the next artwork is then transmitted via light for illuminating that artwork. As a result, the appreciator can read the descriptive data for that artwork displayed in the light reception terminal 133.

0043In this manner, descriptive data for each artwork 132 is superimposed on an electric power waveform and then transmitted to the power line 103, and on the other hand, each of the LED lighting elements 131 for illuminating respective artworks selects descriptive data for the corresponding artwork 132 and optically transmits the resulting selected data, which allows provision of lighting to each artwork 132 and also allows an appreciator to read descriptive data for each artwork 132.

0044There may be more than once piece of descriptive data for each artwork. For example, in the case of providing descriptive data for each artwork in multiple languages, the LED lighting elements 131 select multiple pieces of descriptive data for artworks 132 to be illuminated, and optically transmit the selected data. The light reception terminal 133 then separates and demodulates optically transmitted, multiple pieces of descriptive data, selects descriptive data in a language of choice specified by the appreciator, and presents it to the appreciator. Alternatively, a structure such that the same LED lighting element 131 optically transmits multiple pieces of descriptive data for a single artwork 132, such as descriptive data for adults and that for children, is possible. Note that descriptive data is not limited to text data, and may be sound data, image data, or animation data. Alternatively, a combination thereof is also possible.

0045FIG. 6 is a diagram describing a second application, according to the first aspect of the present invention. In the drawing, 141 denotes LED lighting elements, 142 and 143 denote seats, and 144 denotes light reception terminals. The second application shows a case of the broadcast system, according to the first aspect of the present invention, used in an airplane, a train, or a bus. In the example of FIG. 6, the LED lighting elements 141 are provided to the respective seats, illuminating them. The LED lighting elements 141 also optically transmit data, which is transmitted via the power line 103. Furthermore, the light reception terminal 144 is provided in the backside of the front seat 142 so that a passenger seated in the seat 143 can see the screen of the light reception terminal 144. The light reception terminal 144 receives light illuminated from an LED lighting element 141, and captures data from the light. A passenger may select and view desired data through manipulation of the light reception terminal 144.

0046In an airplane or a spaceship, in particular, a radio wave must not be used because there may be adverse influences on instruments therein. Meanwhile, light has no effect on instruments as well as the human body. Accordingly, wireless data distribution may be carried out as shown in FIG. 6. Note that data may be selected by the light reception terminal 144 in addition to the LED lighting element 141.

0047Note that in an airplane, a train, or a bus, direct current is often used as electric power for lighting. Accordingly, the AC-DC converter 111 in FIGS. 1 and 3 is unnecessary. For example, in the case of optically transmitting all data transmitted via the power line 103, the band pass filter 112 and the superimposing unit 114 are unnecessary. Data may be optically transmitted by driving the LED group with data waveform superimposed electric power, which is supplied from the power line 103.

0048Two applications of the broadcast system, according to the first aspect of the present invention, have been shown above. However, the present invention is not limited to those applications, and can be applied to various applications for optically distributing data. For example, it can be used as a distribution system, which distributes to a personal computer on a desk in an ordinary office, and may be used for transmitting data to each process in a factory. In addition, broadcasting a television program or a radio program in a home is also possible, and that program can be viewed in any room using a portable display. In this case, a selector or a tuner may be provided in the LED lighting element, and a broadcasting station may be selected by controlling the selector using a television controller. Moreover, in a sport stadium or an event hall, for example, information of sports or events or information of other halls is superimposed on illuminative light and broadcast, and a portable terminal owned by a spectator receives it and provides that information for the spectator.

0049As described above, according to the present invention, a great number of pieces of data may be optically distributed using lighting elements as they are. In this case, different from the conventional way, it is unnecessary additionally deploy a transmitter and communication cables. Accordingly, a broadcast system can be constructed at low cost. In addition, there are no adverse effects on the human body, such as eyes, as with infrared rays, and there are no limitations on applications such as a limitation on available radio waves used for airplanes. Therefore, a safe broadcast system can be provided.