JP2009021971A - Optical communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission system in which light emission of a fluorescent lamp is utilized as a transmission medium of a transmission signal to achieve, high-speed communication. <P>SOLUTION: An optical communication system comprises a fluorescent lamp 14; a transmission means 1 configured to include a transmission signal in light output from the fluorescent lamp; and a receiving means 2 for receiving the light output from the fluorescent lamp obtained from the transmission means to receive the transmission signal, wherein the receiving means 2 comprises a light receiving means 21 with light reception sensitivity property as to selectively receive a main spectral line of a discharge medium sealed in the fluorescent lamp from light included in the light output from the fluorescent lamp. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in an optical communication system that uses a light output of a fluorescent lamp as a transmission medium for a transmission signal.

  An optical communication system that performs communication using the light output of a fluorescent lamp that is used to illuminate a premises such as a building is known (see, for example, Patent Document 1).

  Fluorescent lamps that are frequently used for illumination are coated with a phosphor on the inner surface of a glass tube and filled with an inert gas such as mercury and argon as a discharge medium, and are emitted by low-pressure mercury vapor discharge. This is a lamp that utilizes visible light generated from a phosphor when ultraviolet rays (mainly 253.7 nm and 185 nm) excite the phosphor (see Non-Patent Document 1).

JP-A-60-032443 Lighting Terminology Dictionary (Illuminating Society of Japan, edited 25 November 1990) pp. 33-34

  As can be understood from the above, the light emission of the fluorescent lamp is mainly due to the phosphor.

  However, since phosphors generally have afterglow characteristics of several tens to several hundreds of ms, the response to communication signals is slow. For this reason, if the frequency of the transmission signal is increased in order to perform high-speed communication, there is a problem that it is difficult to extract the transmission signal from the output of the light receiving means. For example, since it takes at least several tens of ms to transmit 1-bit data, when communication is performed using visible light from the fluorescent material of the fluorescent lamp, only a communication speed of about 100 bps can be obtained.

  An object of the present invention is to provide an optical communication system that uses light emission of a fluorescent lamp as a transmission medium for a transmission signal and enables high-speed communication.

  An optical communication system according to the present invention includes a fluorescent lamp and a transmission means configured to include a transmission signal in the light output of the fluorescent lamp; receives the light output of the fluorescent lamp obtained from the transmission means and receives the transmission signal Receiving means having a light receiving sensitivity characteristic capable of selectively receiving main spectral lines of a discharge medium sealed in the fluorescent lamp from light included in the light output of the fluorescent lamp. A light-receiving means having;

  The present invention allows the following aspects.

  [Transmitting means] The transmitting means is configured to include a transmission signal in the light output of the fluorescent lamp. In order to realize this, for example, a lighting device for lighting a fluorescent lamp, a modulation means for including a transmission signal in the light output, a transmission data receiving means, and the like can be provided.

    (Fluorescent lamp) A fluorescent lamp is mainly composed of an airtight container, a phosphor layer, a discharge generating means, and a discharge medium, and radiates by low-pressure vapor or gas discharge of the discharge medium enclosed in the airtight container. Irradiation of the ultraviolet rays to the phosphor layer excites the phosphor to generate visible light.

  The airtight container is formed of a glass bulb or the like, and is allowed to have various known forms such as a straight tube shape, an annular shape, a U shape, a W shape, and a spiral shape. Further, the outer diameter and length of the hermetic container can be variously set according to the type and rating of the fluorescent lamp.

  The phosphor layer can be formed using a known phosphor for a fluorescent lamp. The phosphor used is not particularly limited in the present invention. For example, generally used three-wavelength phosphors or halophosphate phosphors can be used. The phosphor layer can be formed by a conventional method.

  The discharge generating means is a means for generating low-pressure vapor or gas discharge of a discharge medium, which will be described later, enclosed in an airtight container, and can be constituted by, for example, an electrode or a high-frequency magnetic field generating means. In the case of electrodes, internal electrodes and external electrodes are known, but either of them may be used.

  The discharge medium only needs to emit ultraviolet rays by low-pressure steam or gas discharge, and a rare gas such as mercury and argon is used as a fluorescent lamp for general illumination. Mercury is enclosed as pure mercury or amalgam.

  As the rare gas, one or more of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) are used depending on the type, rating, manufacturer, and the like of the fluorescent lamp. The discharge medium may contain only rare gas such as xenon, rare gas halide, etc. without containing mercury if desired.

  Further, the discharge medium emits not only ultraviolet rays but also visible light spectrum lines by low-pressure discharge. This spectral line is allowed to have a wavelength overlapping the wavelength region of visible light generated from the phosphor layer. However, even if the main spectrum line has a wavelength that overlaps the wavelength region of visible light generated from the phosphor layer, the radiant energy intensity is the radiant energy intensity of light emitted from the phosphor at the same wavelength. Must be bigger. The greater the difference between the two radiant energy intensities, the easier it is to identify the communication signal, which is more convenient, and is preferably at least 1.5 times, more preferably at least twice the radiant energy intensity of the phosphor emission.

  For example, in the case of mercury, low-pressure mercury vapor discharge causes visible spectral lines at wavelengths of 405, 408, 435, 436, 546, 577, 579 and 691 nm in addition to ultraviolet rays such as 253.7 nm, 185 nm, 313 nm and 365 nm and 1014 nm. It is known to generate spectral lines in the infrared region. Therefore, in the case of a fluorescent lamp for general illumination, the main spectral line may be detected among the above spectral lines of mercury. In this case, the main spectral line is preferably one that can be easily distinguished from phosphor emission in the visible light region. More preferably, the spectral line is commonly emitted regardless of the type, rating, manufacturer, etc. of the fluorescent lamp.

  Next, the types of commercially available fluorescent lamps will be described. Types: (1) Lamp type and shape, (2) Lamp size classification, Thin glass tube and high output type, (3) Light source color, color rendering and application, (4) Structure for starting assistance It is divided into (5) rated lamp power of power saving design, (6) product type, application function, and (7) having a film that absorbs near ultraviolet rays (313 nm and 365 nm). Is encoded. And the design of the fluorescent lamp differs depending on the type. In addition, the design differs depending on the manufacturer of the fluorescent lamp. Accordingly, fluorescent lamps have different designs depending on the type and manufacturer, and thus the spectral distribution characteristics of the fluorescent lamp's emission are various.

In the present invention, the light receiving means described later is preferably configured to selectively receive 405 nm or 436 nm, which is the main spectrum generated by the mercury discharge medium, from the radiation of the fluorescent lamp. For this reason, it is understood that the use of a fluorescent lamp that includes a transmission signal in the light output and whose emission characteristics satisfy the following conditions makes it easier to extract the transmission signal from the light reception signal on the light receiving means side. It was. That is, the fluorescent lamp has a ratio P _S / P _V (%) where P _V is a radiation power over a wavelength range of 380 to 780 nm and P _S is a radiation power in a wavelength range of 380 to 460 nm. Satisfies the following formula.
3 ≦ P _S / P _V ≦ 20

  In the above aspect of the present invention, the region having a wavelength of 380 to 780 nm is generally defined as visible light. On the other hand, the region with a wavelength of 380 to 460 nm is a short wavelength region in visible light, and the light color is perceived by humans as blue (including purple). Of the emission of the fluorescent lamp, the region of wavelength 380 to 460 nm is the main spectrum when the discharge medium is mercury, and light of wavelengths 405 nm and 436 nm suitable for selective light reception by the light receiving means. It is included in the range. The wavelength range is also a wavelength range in which short-wavelength radiation is included in the radiation from the phosphor of the fluorescent lamp.

Therefore, it is easier to distinguish between the spectrum and the radiation from the phosphor when there is no radiation from the phosphor in the vicinity of the wavelength of the main spectrum of the discharge medium or when the radiation intensity level is relatively low. That is, in the wavelength range received by the light receiving means, the identification becomes easier as the ratio of the radiation power of the wavelength 405 nm or the wavelength 436 nm, which is the main spectrum of the discharge medium, increases. In that sense, when the ratio P _S / P _V is within the range satisfying the above formula, it becomes easy to selectively receive light having a wavelength of 405 nm or 436 nm. On the other hand, if the ratio P _S / P _V exceeds 20%, radiation in the short wavelength region generated from the phosphor increases, and light having a wavelength of 405 nm and a wavelength of 436 nm is buried in the light emission of the phosphor. , It becomes difficult to receive light having a wavelength of 405 nm or 436 nm. Further, when the ratio P _S / P _V is less than 3%, the radiation power of the wavelength 405 nm or the wavelength 436 nm, which is the main spectrum of the discharge medium, is reduced, which may interfere with reception of communication signals. In addition, it is 5 to 15% of range suitably.

In the case of a fluorescent lamp using a three-wavelength light emitting phosphor, it is mainly a blue light emitting phosphor, for example, a BAM (BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ) phosphor, that generates radiation in the wavelength region of 380 to 460 nm. This difference is used for fluorescent lamps of each emission color. Therefore, if the amount of blue-emitting phosphor used is reduced, the ratio P _S / P _V can easily satisfy the above formula. That is, when the amount of blue light emitting phosphor used is 30% by mass or less, preferably 10% by mass or less of the entire phosphor used, the ratio P _S / P _V easily satisfies the above formula. Further, when the color temperature of the fluorescent lamp is 4500K or lower, preferably 3500K or lower, the ratio P _S / P _V easily satisfies the above formula. In addition, even if the usage-amount of blue light emission fluorescent substance is reduced to the above-mentioned level, white light can be generated and there is no problem in achieving the general illumination purpose.

In a commercially available three-wavelength light emitting fluorescent lamp, the light color is generally configured as follows.
Light color color temperature ratio P _S / P _V Formula satisfaction degree ・ Daylight color (ED color): 6700-8000K About 25% ×
・ Lunch white (EN color): 5000-6000K About 20% △
・ White (EW color): 3500-4200K About 15% ○
-Light bulb color (EL color): 2500-3000K About 9% ○

The main reason why the color temperature of the fluorescent lamp is different is that the amount of blue-emitting phosphor used is different. In addition, in the remaining four light-color fluorescent lamps excluding daylight color (ED color), the ratio P _S / P _V satisfies a relatively large number of the above formulas. That is, the ratio P _S / P _V is about 15% for white (EW color), and the ratio P _S / P _V is about 9% for the light bulb color (EL color). Satisfies the above formula. Further, the neutral white color (EN color) has a ratio P _S / P _V of about 20%, which may not satisfy the above formula. On the other hand, the daylight color (ED color) does not satisfy the above formula because the ratio P _S / P _V is about 25%.

    (Regarding Lighting Device) The lighting device is means for lighting a fluorescent lamp, and is preferably configured mainly by an inverter circuit and a load circuit, and the fluorescent lamp is turned on at high frequency.

  The inverter circuit is a DC-AC conversion circuit, and various known circuit systems can be selected and used as desired. For example, a half-bridge inverter, a full-bridge inverter, a parallel inverter, and the like. In addition, when using a low frequency alternating current power supply as a power supply of a lighting device, in order to obtain direct current power supply, a rectified direct current power supply circuit can be provided.

  The load circuit refers to circuit means interposed between the inverter circuit and the fluorescent lamp. In addition, the load circuit has a current-limiting means having a ballast function if desired, a filament preheating function for heating the filament electrode of the fluorescent lamp as required prior to starting, and a start for increasing the voltage applied to the fluorescent lamp at the start to promote the start A circuit function and a waveform shaping circuit function that makes a voltage waveform applied to the fluorescent lamp a sine wave can be provided.

    (Regarding Modulation Unit) The modulation unit is a unit for including a transmission signal in the optical output. When the transmission data receiving unit described later receives the transmission data, the transmission unit converts the transmission data into a transmission signal based on a predetermined modulation method. Thus, the transmission signal is included in the light output generated from the fluorescent lamp. As the modulation method, various known methods in optical communication can be adopted as appropriate. For example, FSK (frequency shift keying) modulation described in JP-A-60-032443, PPM (pulse position modulation) and inverted PPM (inverted pulse position modulation) described in JP-A-2004-072365 are used. Can do.

  In order to modulate the light output of the fluorescent lamp, the drive signal generation circuit of the inverter circuit of the lighting device is controlled to generate a modulated drive signal, and the inverter circuit switching circuit is driven by this drive signal, It is preferable to modulate the output of the inverter circuit according to the transmission data. As the output control, one or more of the oscillation frequency, amplitude, phase, pulse width, and the like can be changed in accordance with the modulation method. However, it is also possible to interpose a modulation circuit separately from the lighting device between the lighting device and the fluorescent lamp without controlling the lighting device as desired.

    (Regarding Transmission Data Accepting Unit) The transmission data receiving unit is a receiving unit for receiving transmission data in the transmitting unit, and includes an interface circuit and the like. Moreover, a buffer etc. can also be provided if desired. The transmission data may be in either digital or analog format. Also, a combination of digital and analog may be used as desired. Further, the transmission data is allowed to be selected from various data such as video, audio and computer data.

  [Receiving means] The receiving means includes light receiving means, receives light output of the fluorescent lamp, extracts a transmission signal contained therein, and communicates with the transmitting means. . The receiving means may comprise a demodulating means for extracting a transmission signal contained in the light output of the fluorescent lamp. If desired, a vibration component extracting means for selectively extracting a transmission signal can be interposed between the light receiving means and the demodulating means. Further, in order to increase the output level of the light receiving means to a desired level, an amplifier can be interposed between the light receiving means and the modulating means.

    (Regarding light receiving means) In the present invention, the light receiving means is means for receiving the light output of the fluorescent lamp. In order to make it easy to extract the transmission signal included in the light output of the fluorescent lamp, it has a light receiving sensitivity characteristic capable of selectively receiving main spectral lines of the discharge medium enclosed in the fluorescent lamp. Yes.

  As the main spectral lines of the discharge medium in the fluorescent lamp, for example, in the case of a fluorescent lamp mainly using a low-pressure mercury vapor discharge for general illumination, as described above, the wavelengths 313, 365, 405, 408, 435, 436, 546, and 577 are used. One can choose from spectral lines at 579, 691 and 1014 nm. Note that the above numerical values are rounded values, and can actually include spectral lines having numerical wavelengths below the decimal point. Among these spectral lines, spectral lines having wavelengths of 405, 435, 436, 546, 576, 579, and 691 nm have relatively different types such as presence / absence of an ultraviolet cut film, glass type, light color, and fluorescence of different manufacturers. Since it is included in common for the light emission of the lamp, it is easy to standardize and share the light receiving means. In particular, spectral lines having wavelengths of 405, 435 and 436 nm are common in almost all types of fluorescent lamps and are very convenient because they can be easily distinguished from phosphor emission.

  Note that light emission with wavelengths of 435 nm and 436 nm is generally detected as one spectral line. Therefore, in the case of detecting a spectral line with a wavelength of 436 nm, it can be said that the concept includes a spectral line with a wavelength of 435 nm.

  As described above, the specific means for providing the light receiving means with the light receiving sensitivity characteristic for selectively receiving the main spectral lines of the discharge medium of the fluorescent lamp is not particularly limited in the present invention. For example, a light receiving means is configured by combining a light receiving element having a relatively wide light receiving sensitivity characteristic over almost all or a part of a wavelength range of light emitted from a fluorescent substance of a fluorescent lamp and an optical filter having a desired narrow selective transmission characteristic. can do. The desired selective transmission characteristic is a characteristic that selectively transmits main spectral lines of the discharge medium of the fluorescent lamp. Such an optical filter can be easily obtained by, for example, a narrow-band optical filter formed using a multilayer thin film. Further, any desired narrow band light receiving element can be used as a light receiving means without using a narrow band optical filter.

  By using an optical filter having a half width of about 50 nm, light having a wavelength of 435 nm and 436 nm is detected as one spectral line, and light including a transmission signal from an LED light source including a blue light emitting element that emits blue light. The output can also be received. That is, according to said aspect, the light-receiving means which can be used in common with a fluorescent lamp and LED can be obtained.

  The light receiving means is preferably configured using a photoelectric conversion element. For example, a photodiode, a phototransistor, or the like can be used. As the photodiode, for example, a PIN photodiode, a photoPN diode, a Si photodiode, or the like can be used.

    (Regarding Demodulating Unit) The demodulating unit is a unit that demodulates the transmission signal in the light receiving output of the light receiving unit and extracts transmission data from the demodulated signal. Therefore, a decoding scheme that is paired with the applied modulation scheme may be used.

    (Vibration Component Extracting Unit) The vibration component extracting unit is a unit for selectively extracting a transmission signal from the output of the light receiving unit, and can be arranged as desired. The vibration component extraction means is interposed, for example, between the light receiving means and the demodulation means. However, if desired, the output of the light receiving means can be disposed in a subsequent stage after being amplified by an amplifier.

  Further, the vibration component extraction means can be constituted by a band pass waveform filter. In this case, the band to be filtered is the frequency band of the transmission signal.

  [Other Configurations] In the present invention, the following configurations can be added as desired.

  1. (About Lighting Equipment) The lighting equipment includes a fluorescent lamp and its lighting device that are constituent elements of the present invention, and is used for a required lighting purpose, and all or part of the transmission means of the optical communication system. Arrange there. The luminaire is mainly an indoor luminaire if the area for optical communication is indoor, and is mainly an outdoor luminaire if the area for optical communication is outdoor.

  A plurality of luminaires may be arranged apart from each other, and a transmission signal may be transmitted from each luminaire and included in the optical output so that optical communication is possible even if the receiving means moves.

  In the present invention, when the light output including the transmission signal of the fluorescent lamp is detected by the light receiving means, the light emission of the phosphor that cannot ignore the afterglow characteristics according to the prior art is avoided, and instead the main discharge medium of the fluorescent lamp is used. Since the detection is performed with the spectral line as the center, the response to the transmission signal becomes faster. For this reason, the response to the communication signal is slow in order to detect the emission of the phosphor having afterglow characteristics that cannot be ignored in the prior art and extract the communication signal. For example, the communication speed is about 10 bps. According to the invention, since the lifetime of the excited state of the isolated atom is generally on the order of 0.01 μs, the response to the communication signal becomes fast, so that the communication speed can be dramatically improved to about 10 kbps. Some phosphors have afterglow characteristics of 1 μs or less, and a quick response can be obtained accordingly. However, the types of such phosphors are limited and the range of selection becomes extremely narrow. Therefore, it is not practical.

  Also, in the case of fluorescent lamps for general lighting, by detecting the main spectral lines of mercury in the discharge medium, the spectral lines are common regardless of the type or manufacturer of the fluorescent lamp. The light receiving means can be standardized and shared with the fluorescent lamps of the product types and manufacturers.

  Further, since spectral lines having wavelengths of 405, 435 and 436 nm are included in common regardless of the light source color of the fluorescent lamp for general illumination, the light receiving means is standardized and shared for various fluorescent lamps. be able to.

  Furthermore, the light receiving means selectively receives a 436 nm spectral line as a main spectrum of the discharge medium and receives a light output including a transmission signal from an LED light source including a blue light emitting element that emits blue light. By configuring so as to be possible, a light receiving means common to the fluorescent lamp and the LED can be obtained.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a block circuit diagram showing a first mode for carrying out the optical communication system of the present invention. The optical communication system includes a transmission unit 1 and a reception unit 2.

  The transmission unit 1 includes a transmission data receiving unit 11, a modulation unit 12, a lighting device 13, and a fluorescent lamp 14, and constitutes a lighting fixture. In addition, the transmission means 1 is arrange | positioned in the lighting fixture main body, and it is not substantially different from the lighting fixture which is not provided with the transmission means in appearance.

  The transmission data receiving means 11 is configured mainly by an interface, for example, and receives transmission data generated from the external transmission data generating unit 3.

  The modulation unit 12 modulates the transmission data received by the transmission data receiving unit 11 using a predetermined modulation method.

  The lighting device 13 includes a DC power supply unit 13a and an inverter circuit / load circuit unit 13b. The DC power supply unit 13a rectifies and smoothes the AC voltage of the low-frequency AC power supply 4 and outputs a DC voltage. Inverter circuit / load circuit unit 13b includes an inverter circuit and a load circuit unit. The inverter circuit includes a switching circuit and a drive signal generation circuit 13b1.

  The drive signal generation circuit 13b1 generates a drive signal and drives the switching circuit of the inverter circuit at a predetermined oscillation frequency. The drive signal generation circuit 13b1 generates a drive signal modulated by the modulation means 12 with the transmission signal. As a result, the inverter circuit generates a high-frequency voltage including the modulated transmission signal.

  The fluorescent lamp 14 includes a glass bulb, a phosphor layer formed on the inner surface thereof, a pair of filament electrodes sealed inside both ends of the glass bulb, and a discharge medium sealed inside the glass bulb. The discharge medium is composed of an appropriate amount of mercury and a rare gas such as argon of several hundred Pa, and is for general illumination.

  Further, since the pair of filament electrodes of the fluorescent lamp 14 is connected to a predetermined position of the load circuit of the inverter circuit / load circuit unit 13b, a high frequency voltage including a transmission signal generated from the inverter circuit is applied to the load circuit. Via, it is applied between a pair of filament electrodes. As a result, the preheat filament electrode is preheated, and then a start voltage is applied to start and light up. And lighting produces the optical output of visible light including a transmission signal. However, since the transmission signal has a high frequency that is not perceived by human eyes, illumination that does not appear to be the same as in normal lighting without communication by lighting of the fluorescent lamp 14 is performed.

  The receiving unit 2 includes a light receiving unit 21, an amplifier 22, and a demodulating unit 23.

  The light receiving means 21 is arranged in a positional relationship so as to receive the light output of the fluorescent lamp 14, mercury enclosed in the glass bulb evaporates from the light output of the fluorescent lamp 14, and low-pressure mercury vapor discharge. Has a spectral light receiving sensitivity characteristic capable of selectively receiving a main spectral line radiated when, for example, visible light of 436 nm. Therefore, the transmission signal included in the optical output can be received, that is, received with high sensitivity.

  The amplifier 22 amplifies the transmission signal obtained from the light receiving means 21 to a required level.

  The demodulator 23 demodulates the amplified transmission signal to restore the transmission data. The obtained transmission data is taken out from the receiving means 2 and input to, for example, an external device 5 for communication.

  Next, experimental results for examining the relationship between the main spectral lines of the fluorescent lamp and the response speed will be described with reference to FIGS.

  2 and 3 show two different types of FL20SS EX-D / 18-Z type fluorescent lamp (hereinafter referred to as “fluorescent lamp A” for convenience) and FL20SS · W type fluorescent lamp (hereinafter referred to as “fluorescent lamp B for convenience”). Is a graph showing the spectral distribution characteristics. In each figure, the horizontal axis represents wavelength (nm) and the vertical axis represents radiation intensity (%). The horizontal axis is a relative value when the maximum peak of spectral radiation intensity is 100%.

  The fluorescent lamp A is a three-wavelength emission type daylight fluorescent lamp manufactured by Company A, and includes a phosphor layer mainly composed of a three-wavelength emission type rare earth phosphor. The fluorescent lamp B is a normal white fluorescent lamp manufactured by B company, and includes a phosphor layer mainly composed of a calcium halophosphate phosphor. 2 and 3, the numerical value added to the graph indicates the wavelength of light received by the light receiving means.

  FIG. 4 is a waveform diagram showing lamp voltage and lamp current when the fluorescent lamps A and B are pulse-lit at a lighting frequency of 14 kHz, respectively. FIG. 4A shows the lamp voltage, which is an AC pulse waveform with a pause period by PWM control. FIG. 4B shows the lamp current, which is an AC pulse waveform that substantially matches the lamp voltage waveform.

  5 and 6 are output waveform diagrams of the light receiving means at each light receiving wavelength of the fluorescent lamp A. FIG. In addition, the numerical value described in the upper part of each waveform diagram has shown the light reception wavelength. At wavelengths of 404.4 nm, 435.8 nm, 449.0 nm, 487.4 nm, 546.9 nm, 578.2 nm, and 654.0 nm, the response is relatively fast, and 28 kHz pulsed light can be extracted. However, 404.4 nm, 435.8 nm, and 449.0 nm have particularly high detection levels of pulsed light, and the response is particularly good. On the other hand, at wavelengths of 542.6 nm, 587.2 nm, 611.7 nm, 631.0 nm and 709.0 nm, the response is slow and it is almost impossible to extract pulsed light.

  FIG. 7 is an output waveform diagram of the light receiving means at each light receiving wavelength of the fluorescent lamp B. FIG. As in FIGS. 5 and 6, the numerical values described at the top of each waveform diagram indicate the received light wavelength. At wavelengths of 404.4 nm, 435.9 nm, 481.1 nm, 546.4 nm, 577.7 nm, and 653.4 nm, the response is relatively fast, and it is possible to extract 28 kHz pulsed light. However, 404.4 nm, 435.9 nm, and 546.4 nm have particularly large detection levels of pulsed light, and the response is particularly good. On the other hand, at a wavelength of 582.2 nm, the response is slow and it is almost impossible to extract pulsed light.

  Next, when FIG. 5 and FIG. 6 are compared with FIG. 7, the wavelengths of 405 nm (404.4 nm), 436 nm (435.8 nm and 435.9 nm) and 547 nm (546.9 nm and 546.4 nm) are fluorescent. Common to lamps A and B. All of these wavelengths are mercury spectral lines.

  FIG. 8 is a waveform diagram showing the lamp current and the waveform of the light pulse corresponding to the lamp current when the fluorescent lamp A receives light having a wavelength of 435.8 nm. Waveform a is the lamp current and waveform b is the light pulse.

  As can be seen from the figure, at the wavelength of 436 nm, it is understood that a quick response is obtained by selectively receiving the main spectral lines of the discharge medium.

  FIG. 9 is a waveform diagram showing the lamp current and the waveform of the light pulse corresponding to the lamp current in a timed manner when the fluorescent lamp B receives light having a wavelength of 435.9 nm. Waveform a is the lamp current and waveform b is the light pulse.

  As can be understood from the figure, it can be seen that this is the same as FIG.

  FIG. 10 is a graph showing the spectral distribution characteristics of the FL20SS / ENW / 18H fluorescent lamp. Also in this fluorescent lamp, a quick response can be obtained by selectively receiving mercury spectral lines having wavelengths of 404 nm and 436 nm.

  FIG. 11 is a block circuit diagram showing a second mode for carrying out the optical communication system of the present invention. In the figure, the same parts as those in FIG.

  In the second embodiment, a vibration waveform extracting unit 24 is interposed between the amplifier 22 and the demodulating unit 23. The vibration waveform extracting means 24 is composed of a band pass filter and receives light in a wavelength selective manner.

  According to this embodiment, since the optical pulse frequency band is allowed to pass and the frequency band lower than the pass band is blocked, the SN ratio of the transmission signal can be sufficiently increased.

  Next, a third mode for carrying out the optical communication system of the present invention will be described. In the present embodiment, PWM control is performed on a high-frequency output having an oscillation frequency of the inverter circuit of 112 kHz, for example, at a frequency of, for example, 28 kHz, which is a fraction of the oscillation frequency.

The block circuit diagram which shows the 1st form for implementing the optical communication system of this invention Graph showing spectral distribution characteristics of FL20SS EX-D / 18-Z type fluorescent lamp Graph showing spectral distribution characteristics of FL20SS / W type fluorescent lamp Waveform diagram showing lamp voltage and lamp current when a fluorescent lamp is lit with a pulse having a lighting frequency of 14 kHz. Output waveform diagram of light receiving means at each light receiving wavelength of fluorescent lamp A Output waveform diagram of light receiving means at each light receiving wavelength of fluorescent lamp A Output waveform diagram of light receiving means at each light receiving wavelength of fluorescent lamp B Waveform diagram showing the lamp current and the waveform of the light pulse corresponding to the lamp current when receiving light with a wavelength of 435.8 nm Waveform diagram showing the lamp current and the waveform of the light pulse corresponding to this in the received light of wavelength 435.9nm. Graph showing spectral distribution characteristics in FL20SS / ENW / 18H fluorescent lamp The block circuit diagram which shows the 2nd form for implementing the optical communication system of this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transmission means, 2 ... Reception means, 3 ... Transmission data generation part, 4 ... Low frequency alternating current power supply, 5 ... Apparatus, 11 ... Transmission data reception means, 12 ... Modulation means 12, 13 ... Lighting apparatus, 13a ... DC power supply , 13b... Inverter circuit / load circuit unit 13b, 13b1... Drive signal generation circuit, 14... Fluorescent lamp, 21.

Claims (5)

A transmission means comprising a fluorescent lamp and configured to include a transmission signal in the light output of the fluorescent lamp;
Receiving means for receiving the transmission signal by receiving the light output of the fluorescent lamp obtained from the transmitting means;
Comprising
The receiving means includes a light receiving means having a light receiving sensitivity characteristic capable of selectively receiving main spectral lines of a discharge medium enclosed in the fluorescent lamp from light included in the light output of the fluorescent lamp;
An optical communication system.   The light receiving means selectively receives a 436 nm spectral line as a main spectrum of the discharge medium and can receive an optical output including a transmission signal from an LED light source including a blue light emitting element that emits blue light. 3. The optical communication system according to claim 2, wherein the optical communication system is configured as described above.   2. The optical communication system according to claim 1, wherein the light receiving means is configured to selectively receive at least one of spectral lines having wavelengths of 405 nm and 436 nm as a main spectrum of the discharge medium.   3. The optical communication system according to claim 1, wherein the receiving means includes vibration component extracting means for selectively extracting and receiving the vibration component of the transmission signal from the output of the light receiving means. The fluorescent lamp is characterized in that the ratio P _S / P _V (%) of the radiation power P _S in the wavelength range of 380 to 460 nm to the radiation power P _{V in} the wavelength range of 380 to 780 nm satisfies the following equation. 5. The optical communication system according to any one of 1 to 4.
3 ≦ P _S / P _V ≦ 20

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