JP2010278573A - Lighting control device, anti-voyeurism system, projector - Google Patents

Abstract

Provided are a lighting control device, a voyeurism prevention system, and a projector that can prevent voyeurism using a general video camera having no special function.
A lighting circuit 12 blinks a light emitting unit 11 that irradiates light to a subject to be photographed by a video camera at a lighting frequency. The control unit 14 controls the lighting frequency at which the light emitting unit 11 blinks so that when the shooting target is shot with a video camera, flickering occurs in the video and normal shooting cannot be performed. Here, the control unit 14 sets the lighting frequency within a range equal to or higher than the critical fusion frequency so as not to feel flickering for those who are directly looking at the subject to be photographed, and changes the lighting frequency over time. .
[Selection] Figure 1

Description

  The present invention relates to a lighting control device, a voyeurism prevention system, and a projector that prevent a video camera from illegally taking a movie or a movie to be played in a theater or the like.

  Conventionally, the act of illegally photographing (voyeurizing) a movie currently being shown in a theater with a video camera (camcorder) and creating a so-called pirated version has been a problem.

  In order to cope with this type of problem, an RF tag (active radio tag) is built in the video camera, and the RF tag readers installed at the entrance and the exit of the theater are used to read the information of the RF tag. There has been proposed a technique for finding a photographing action within the network (for example, see Patent Document 1). In addition, a technique has been proposed in which control information is transmitted to a camera in an area where photographing is prohibited, and the camera that has received the control information is prohibited from photographing (for example, see Patent Document 2).

Japanese Patent Laying-Open No. 2005-051487 (pages 4-5) JP 2008-078845 (pages 5-6)

  However, in the inventions described in Patent Documents 1 and 2 described above, a dedicated video camera having a special function (Patent Document 1 is a video camera with a built-in RF tag, and Patent Document 2 receives control information to restrict shooting). Only the camera that is used to prevent voyeurism, and voyeurism using a general video camera that does not support these functions cannot be prevented.

  The present invention has been made in view of the above reasons, and provides a lighting control device, a voyeurism prevention system, and a projector that can prevent voyeurism using a general video camera having no special function. Objective.

  According to a first aspect of the present invention, there is provided a lighting circuit for lighting a light emitting unit that irradiates light to a subject to be photographed by a first video camera while blinking or changing brightness at a lighting frequency within a predetermined range, and the lighting frequency. A control unit that controls the lighting frequency, and the control unit has a lighting frequency that is equal to or lower than an upper limit frequency that is determined so as to generate flicker whose brightness varies between frames in an image shot by the first video camera. It is characterized by changing with the passage of time in the range above the fusion frequency.

  According to this configuration, the lighting circuit blinks the light emitting section or changes the brightness at a lighting frequency that is lower than the upper limit frequency determined to cause flicker in the video of the first video camera and higher than the critical fusion frequency. The image of the first video camera that captured the shooting target while preventing the flickering of the eyes of the person directly looking at the shooting target irradiated with the light from the light emitting unit. Flicker can be generated. As a result, even if an attempt is made to voyeur the subject to be photographed using a video camera, flicker is generated in the photographed video regardless of whether or not the video camera is a general video camera having no special function. There is an advantage that it is possible to prevent voyeurism of the subject to be photographed. Furthermore, since the control unit changes the lighting frequency as time elapses, even if flicker is suppressed by changing settings such as the shutter speed of the video camera in accordance with the lighting frequency, the lighting frequency is subsequently changed. Is changed, flicker occurs again and voyeurism is prevented. The critical fusion frequency means a limit frequency at which a flicker is not visually perceived and a continuous stimulus is felt when the light stimulus for the human eye is periodically changed.

  According to a second aspect of the present invention, there is provided the lighting control device according to the first aspect, a second video camera that captures an area irradiated with light of the light emitting unit, and the control unit before changing the lighting frequency. Based on the change notification unit that outputs change information including the lighting frequency and change timing after the change, and the change information output from the change notification unit, flicker is not generated in the video shot by the second video camera. And a setting changing unit for changing the setting of the second video camera.

  According to this configuration, by using the setting change unit, the setting of the video camera can be changed based on the change information output from the change notification unit so that no flicker occurs in the video shot by the video camera. Therefore, it is possible to shoot without causing flicker by using the setting change unit for the second video camera that is normally permitted to shoot. In other words, for a video camera that is normally permitted to shoot, settings such as the shutter speed can be changed based on the change information including the changed lighting frequency and change timing before the control unit changes the lighting frequency. Therefore, flicker can be prevented by synchronizing the timing at which the brightness of the light emitting unit changes and the shooting timing.

  According to a third aspect of the present invention, in the second aspect of the invention, the change notification unit is provided in the lighting control device, the setting change unit is provided in the second video camera, and the lighting control device changes to the setting change unit. The transmission of the change information is performed by communication between the lighting control device and the second video camera.

  According to this configuration, by performing communication between the lighting control device and the second video camera that is normally permitted to shoot, it is possible to shoot with the video camera. There is no need to prepare a special device for permitting photographing, and there is an advantage that the system configuration can be simplified.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the lighting control device includes a transmission unit that performs visible light communication by superimposing the change information on light output from a communication light source. The video camera includes a receiving unit that receives output light from a communication light source and acquires change information from the received output light from the communication light source.

  According to this configuration, since the change information is transmitted from the lighting control device to the second video camera by visible light communication, the lighting control device and the second video camera are not directly connected by a cable or the like. In addition, it is possible to shoot with the video camera.

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, the light emitting unit is also used as the communication light source.

  According to this configuration, since the light emitting unit for preventing flickering and preventing voyeurism is also used for visible light communication, an increase in the number of components for performing visible light communication can be suppressed.

  According to a sixth aspect of the present invention, the lighting control device according to the first aspect is provided, and an image is projected onto a screen using the light emitting unit as a light source.

  According to this configuration, it is possible to prevent the video from being stolen by using a projector that projects the video such as a movie on the screen.

  In the present invention, the lighting circuit causes the light emitting unit to light up while blinking or changing brightness at a lighting frequency within a predetermined range, and the control unit determines the lighting frequency so as to cause flicker in the video of the first video camera. Since it changes with time in a range below the upper limit frequency and above the critical fusion frequency, there is an advantage that voyeurism using a general video camera having no special function can be prevented.

(A) is a schematic block diagram of the lighting control apparatus of Embodiment 1 of this invention, (b) is explanatory drawing which shows the operation example. It is a schematic circuit diagram which shows a structure same as the above. It is explanatory drawing which shows the other operation example same as the above. It is a schematic circuit diagram which shows the other structure same as the above. It is a schematic block diagram of a voyeurism prevention system same as the above. It is explanatory drawing which shows the operation example same as the above. It is explanatory drawing which shows the operation example same as the above. It is explanatory drawing which shows the code | symbol used in the same as the above. It is explanatory drawing which shows the other operation example same as the above. It is a schematic circuit diagram of the lighting control apparatus of Embodiment 2 of this invention. It is explanatory drawing which shows the frequency characteristic of lamp electric power same as the above. It is a timing chart which shows the operation example same as the above.

(Embodiment 1)
The lighting control device of the present embodiment is for preventing an act of illegally photographing (voyeurizing) a theater or the like to be performed in a theater with a video camera (camcorder), and is a stage to be filmed by the video camera. It is equipped with a voyeurism prevention function in a lighting device that illuminates the top (may be a spotlight). Note that the voyeurism prevention function does not need to always function during the performance, so it is not necessary to install the voyeurism prevention function on all lighting fixtures that illuminate the stage.

  As shown in FIG. 1A, the lighting control device 10 includes a lighting circuit 12 that lights a light emitting unit 11 that is a light source for illumination, a driving circuit 13 that drives the lighting circuit 12 by a driving signal, and a driving circuit. 13 and a control unit 14 for controlling 13.

  As the light emitting unit 11, a light emitting unit that can blink at least at a lighting frequency equal to or higher than a critical fusion frequency is used. Here, an LED (light emitting diode) is used. The critical fusion frequency here means a frequency at which a person starts to visually recognize as if the light is continuously lit without flickering when the frequency of blinking light is gradually increased. The lighting circuit 12 blinks the light emitting unit 11 at a lighting frequency within a predetermined range by supplying power to the light emitting unit 11. The control unit 14 is mainly composed of a microcomputer and has a timer function. The drive circuit 13 has a function of driving the switching element 15 (see FIG. 2) in the lighting circuit 12 in accordance with the output signal of the control unit 14.

  Hereinafter, a specific configuration of the lighting control device 10 will be described with reference to FIG.

  The light emitting unit 11 includes an LED block having a plurality of LED arrays formed by connecting a plurality of LEDs 16 in series. The lighting circuit 12 includes a DC power supply circuit 17 that converts AC power (commercial power) AC into DC power. Power is supplied to the light emitting unit. Here, each LED array is connected in series with a current reducing resistor R1, and the light emitting unit 11 is applied by applying a DC voltage from a DC power supply circuit 17 to a parallel circuit composed of a plurality of LED arrays and the resistor R1. Lights up. A light emitting unit 11 and a resistor R1 are connected between output terminals of the DC power supply circuit 17 via a switching element 15 made of a MOSFET, and the light emitting unit 11 blinks in accordance with the on / off of the switching element 15. . Here, the switching element 15 of the lighting circuit 12 is ON / OFF controlled by the driving circuit 13 at the above-described lighting frequency, whereby the light emitting unit 11 is repeatedly turned on / off at the lighting frequency.

  Here, in the control unit 14, when the area irradiated with light from the light emitting unit 11 (here, on the stage) is imaged with a video camera (first video camera), flicker occurs and normal imaging cannot be performed. The lighting frequency is controlled as follows. That is, as is generally known, when a video camera captures an image, for example, if the illuminance of the object to be imaged varies periodically by using a non-inverter fluorescent lamp for illumination, the image is captured by the video camera. In such a video, flicker whose brightness varies between frames occurs. The occurrence of the flicker is caused by the fact that the amount of light received by the video camera during one shutter opening period differs from frame to frame.

  In the present embodiment, this flicker is intentionally generated to prevent unauthorized photographing (voyeurism) by the video camera. However, the flicker matches the reciprocal of the lighting frequency (or an even multiple thereof) and the shutter speed of the video camera (in recent years, video cameras with a shutter speed of about 1/24 to 1/8000 seconds are generally provided). If the lighting frequency is much higher than the reciprocal of the shutter speed, the upper limit frequency of the lighting frequency is determined from the latter condition. Specifically, the upper limit frequency is set so that the lighting frequency is less than the reciprocal of the shutter speed.

  Here, the lighting frequency is the above-mentioned critical fusion frequency (although there are individual differences depending on age and the like, generally about 30 so as not to feel flickering for those who are directly viewing the area irradiated with light from the light emitting unit 11. It should be set within the range of about 40 Hz or more. As a result, although the light output from the light emitting unit 11 actually fluctuates, the average light output in the time unit of the reciprocal of the critical fusion frequency is substantially constant, so that it is continuously lit to the human eye. Will look like.

  Eventually, the lighting frequency is in the range below the upper limit frequency and above the critical fusion frequency (for example, about 60 to 200 Hz) so as not to cause flickering in the video of the video camera while causing flickering to the person who is directly watching. ).

  However, in the video camera, a technique for reducing flicker according to the illumination state of the subject has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2008-31854 and Japanese Patent No. 3474999), and the light emitting unit 11 is simply blinked. Alone, there is a possibility that flicker can be reduced by using a video camera adopting this kind of technology. For example, flicker does not occur in a video camera in which the shutter speed is adjusted to match the lighting frequency so that the lighting frequency of the illumination light (or an even multiple thereof) matches the inverse of the shutter speed. There is a risk of unauthorized shooting using a video camera. Therefore, in the present embodiment, the control unit 14 adopts a configuration in which the lighting frequency is not fixed and is changed as needed over time.

  Here, as shown in FIG. 1B, by switching the lighting frequency between at least three of f1, f2, and f3, the light emitting unit 11 blinks at the lighting frequency f1 during the period from time t0 to t1, and the time t1 It flickers at the lighting frequency f2 (> f1) during the period of t2 and flickers at the lighting frequency f3 (<f1) during the period of time t3 to t4. In the present embodiment, the lighting frequency is periodically switched in a predetermined order according to a pre-installed program. However, the present invention is not limited to this example, and at least one of the lighting frequency change timing and the changed frequency is used. Alternatively, it may be determined randomly using a random number generation function.

  In this way, by changing the lighting frequency of the light emitting unit 11 with the passage of time, even if the shutter speed or the like is adjusted in accordance with one lighting frequency in the video camera, the lighting frequency is immediately changed and the flicker is changed. Will occur. In other words, even if an attempt is made to adjust the shutter speed or the like following the change in the lighting frequency, flicker occurs between the change of the lighting frequency and the actual change of the shutter speed or the like. You can't take a picture without it. This makes it possible to reliably prevent unauthorized shooting (voyeurism).

  In the above-described example, the light emitting unit 11 employs a method of repeating the lighting state and the extinguishing state at the lighting frequency. However, the present invention is not limited to this example, and the two-stage lighting states with different brightness as shown in FIG. (Bright state / dark state) may be set, and the light state and the dark state may be repeated at the lighting frequency. In this case, for example, as shown in FIG. 4, the light emitting unit 11 is divided into two LED blocks (light emitting units 11, 11 ′), and the switching elements 15, 15 ′ and the drive circuit 13, for each of the light emitting units 11, 11 ′. 13 ′ is provided, and a state in which only one of the light emitting units 11 and 11 ′ is lit (dark state) and a state in which both the light emitting units 11 and 11 ′ are lit (bright state) are alternately repeated. Good.

  By the way, there is a case where a certain regular video camera (second video camera) is permitted to shoot a play or the like when shooting a play or the like to be performed on the stage and creating a regular DVD. is there. In such a case, since it is necessary to avoid the occurrence of flicker in the video shot by a legitimate video camera with permission for shooting, a voyeurism prevention system described below is proposed.

  As shown in FIG. 5, this voyeurism prevention system includes a lighting control device 10 and a regular video camera 20 that is permitted to take a picture, and the lighting control device 10 changes the lighting frequency of the light emitting unit 11. Before, it has the structure which notifies change information, such as the frequency after a change, and a change timing, to the said video camera 20 from the lighting control apparatus 10. FIG. Here, the change information is a visible light communication technique using visible light output from the light emitting unit 11 as a medium (see, for example, Japanese Unexamined Patent Application Publication Nos. 2007-267036, 2009-010487, and 2007-274052). ) To the video camera 20. That is, the lighting control device 10 is provided with a function as a transmission unit that transmits the change information by modulating the amplitude and frequency of the illumination light output from the light emitting unit 11, and the video camera 20 receives the output light of the light emitting unit 11. Then, a receiving unit 30 that acquires the change information by demodulating is provided. In addition, the control part 14 of the lighting control apparatus 10 functions as a transmission part here.

  The receiving unit 30 includes a photoelectric conversion unit 31 that converts light received from the light emitting unit 11 into an electrical signal, an amplification unit 32 that amplifies the electrical signal output from the photoelectric conversion unit 31, and a signal in a predetermined frequency band. A band-pass filter 33 to be passed, a comparator 34 that binarizes the output of the band-pass filter, and a reception controller 35 that reversely converts the encoding method from the output of the comparator 34 and decodes the change information. is doing.

  The photoelectric conversion unit 31 is composed of a PIN photodiode. However, the present invention is not limited to this example, and the image pickup element (CCD or CMOS sensor) of the image pickup unit 21 of the video camera 20 is also used as the photoelectric conversion unit 31 (for example, Japanese Patent Application Laid-Open No. 2007-2007). -274052)). The photoelectric conversion unit 31 has an optical filter (not shown) that transmits only a specific wavelength in order to remove noise components and improve the light receiving accuracy of the output light of the light emitting unit 11. The amplification unit 32 is assumed to be a general-purpose unit composed of an operational amplifier IC, a transistor, and the like.

  Here, in this embodiment, since the change information is transmitted by superimposing the carrier wave on the output of the light emitting unit 11, the light emitting unit 11 is blinked at a driving frequency sufficiently higher than the lighting frequency while the light emitting unit 11 is turned on. (See FIG. 6). The band-pass filter 33 is a general-purpose band-pass filter that performs filtering using a frequency that is twice the driving frequency as a center frequency, and the amplification unit 32 that is generated when the photoelectric conversion unit 31 receives the output light from the light-emitting unit 11. Configured to pass the output of. The comparison unit 34 includes a comparator, and converts the signal that has passed through the band-pass filter 33 into a binary digital signal of “H” and “L” by comparing it with a predetermined threshold value. That is, the output of the comparator 34 becomes “H” when the light emitting unit 11 is turned on and becomes “L” when the light emitting unit 11 is turned off.

  The reception control unit 35 includes a general-purpose arithmetic device, and sets the shutter speed, the gain, and the like for the imaging unit 21 of the video camera 20 based on the demodulated change information. Note that flickering can be prevented even if the frame rate of the video camera 20 is synchronized with the lighting frequency. Therefore, the frame rate of the video camera 20 may be set based on the change information.

  Next, a mode of transmitting data (change information) by modulating the amplitude and frequency of the output light of the light emitting unit 11 will be described.

  FIG. 7 illustrates the light output of the light emitting unit 11 when a 4-value PPM (pulse position modulation) method is adopted as an example of a modulation method for visible light communication. Here, in the quaternary PPM system, as shown in FIGS. 8A to 8D, one symbol time is equally divided into four slots to generate pulses (that is, the light emitting unit 11 is lit). The sign of 2 bits per symbol time (four values of “00”, “01”, “10”, “11”) can be represented by the position of. That is, the first slot is “H” and the other “L” patterns correspond to “00”, the second slot is “H” and the other “L” patterns correspond to “01”. The third slot corresponds to “H” and the other “L” pattern corresponds to “10”, the fourth slot corresponds to “H” and the other “L” pattern corresponds to “11”. To do.

  In the example of FIG. 7, the light emitting unit 11 is turned off when “H” in FIG. 8, and the light emitting unit 11 is turned on when “L”. In this method, since the light emitting unit 11 is lit for 3 slots per symbol time in any code, the integrated value of the light output from the light emitting unit 11 for each symbol time is constant. FIG. 8E shows a start code indicating the start of communication.

  As described above, when the quaternary PPM method is employed, the brightness of the light emitting unit 11 changes with one symbol time as one cycle, and the reciprocal of one symbol time is the lighting frequency. Therefore, the control unit 14 does not fix the one symbol time constant, but changes the lighting frequency by changing it with time (in the example of FIG. 7, it is changed before and after time t1). To do.

  Further, the modulation method of visible light communication is not limited to the above-described four-value PPM method, and for example, the Manchester code method shown in FIG. 9 can be adopted. In the Manchester encoding method, a clock signal having a duty ratio of 50% is basically used, a clock signal changing from “H” to “L” is set to “1”, and a clock signal changing from “L” to “H” is set to “0”. To do. In this case, the integrated value of the light output from the light emitting unit 11 for each clock is constant. In this method, since the frequency of the clock signal becomes the lighting frequency, the control unit 14 changes the lighting frequency as needed over time (in the example of FIG. 9, the time is changed before and after the times t1 and t2, respectively). ).

  Here, when a plurality of lighting fixtures in the theater are used as the lighting control device 10 for preventing voyeurism, it is not necessary for all of the plurality of lighting fixtures to have a visible light communication function, and an upper network (such as a local area LAN). One or more luminaires connected to the TV may be configured to transmit the change information to the video camera 20 with the visible light communication function.

  Further, the light source (light emitting unit 11) that generates flicker in the video image of the video camera and the light source (communication light source) for transmitting change information to the video camera 20 through visible light communication may be separate lighting fixtures. Good. In this case, the change information is transmitted from the lighting control device 10 to the luminaire including the communication light source, and the change information is transferred from the luminaire to the video camera 20 by visible light communication. Furthermore, the receiving unit 30 may be configured as a separate device from the video camera 20, and the change information received by the receiving unit 30 may be further transferred to the video camera 20.

  Furthermore, it can also be used as the lighting control device 10 by interlocking a plurality of lighting fixtures. In this case, it is possible to link these plural lighting fixtures by connecting them to the upper network and matching the lighting frequency and the switching timing thereof. You may make it synchronize by performing visible light communication between lighting fixtures.

(Embodiment 2)
The lighting control device 40 of the present embodiment is different from the lighting control device 10 of the first embodiment in that the light emitting unit is a discharge lamp (fluorescent lamp).

  As shown in FIG. 10, the lighting control device 40 includes a DC power supply circuit 47 that converts an AC power supply AC into a DC power supply by smoothing the AC power supply AC with a capacitor C1 after full wave rectification using diode bridges D1 to D4. The lighting circuit 42 includes a series circuit of switching elements Q1 and Q2 connected between output terminals of the DC power supply circuit 47 (between both ends of the capacitor C1), and a drive circuit 43 that alternately turns on the pair of switching elements Q1 and Q2. And constitutes a half-bridge type inverter circuit. A discharge lamp La as a light emitting unit is connected between both ends of the switching element Q2 via a series circuit of a capacitor C2 and an inductor L1, and a preheating capacitor C3 is connected in parallel to the discharge lamp La. Capacitor C2 is a direct current cut capacitor that removes a direct current component from the lamp current, and a capacitor having a capacity significantly larger than capacitor C3 (for example, 10 times or more that of capacitor C3) is selected.

  The operating frequency of the lighting circuit 42 (that is, the frequency at which the drive circuit 43 turns on and off the switching elements Q1 and Q2) is controlled by the inverter control unit 45. In the inverter control unit 45, the discharge lamp La is preheated, started, and lit by changing the operating frequency. For example, when the power is turned on, a high voltage is generated between both ends of the discharge lamp La by the LC series resonance circuit (inductor L1, capacitor C3) after a predetermined preheating time elapses, whereby discharge starts and the discharge lamp La is turned on.

  FIG. 11 shows the relationship between the operating frequency of the lighting circuit 42 and the lamp power (power supplied to the discharge lamp La). If the operating frequency is set at a frequency lower than the resonance frequency fc of the LC series resonance circuit, an excessive current flows through the circuit when the discharge lamp La is started and stress is applied to the circuit components. Here, a region higher than the resonance frequency fc (here) Then, the operating frequency is changed at 40 kHz to 100 kHz. Thus, in the lighting circuit 42, dimming control of the discharge lamp La can be performed according to the operating frequency.

  Therefore, in this embodiment, the control unit 44 switches the operating frequency between two values of fd1 (> fc) and fd2 (> fd1) as shown in FIG. Set (bright / dark) and repeat the bright and dark states at the lighting frequency. That is, the discharge lamp La that drives the lighting circuit 42 at the operating frequency fd1 is in a relatively bright light state, and when the lighting circuit 42 is driven at the operating frequency fd2, the discharge lamp La is in a relatively dark dark state. In FIG. 12, until the time t1, the bright state and the dark state are alternately repeated at the lighting frequency f1, and after the time t1, the light state and the dark state are alternately repeated at the lighting frequency f2 (<f1). In addition, the average light output in FIG. 12 represents the average light output (that is, the brightness visually recognized by a person) in the time unit of the reciprocal of the critical fusion frequency.

Other configurations and functions are the same as those in the first embodiment. However, in each of the above embodiments, the lighting apparatus is exemplified as the lighting control device. However, the lighting apparatus is not limited to this example, and a projector (projector) for projecting a movie on the screen is used. It is also conceivable to add the function of the lighting control device of the present invention to a device). In this case, the light source of the projector is a light emitting unit. The light emitting unit may be a light source (for example, an organic EL) other than an LED or a discharge lamp.

DESCRIPTION OF SYMBOLS 10 Lighting control apparatus 11 Light emission part 12 Lighting circuit 14 Control part f1, f2, f3 Lighting frequency

Claims (6)

  A lighting circuit that illuminates a light emitting unit that irradiates light on a subject to be photographed by the first video camera while blinking or changing brightness at a predetermined lighting frequency; and a control unit that controls the lighting frequency. The control unit includes the lighting frequency within a range that is lower than an upper limit frequency and higher than a critical fusion frequency that is determined so as to generate flicker whose brightness changes between frames in an image shot by the first video camera. A lighting control device that changes with time.   The lighting control device according to claim 1, a second video camera that captures a region irradiated with light from the light emitting unit, and the lighting frequency and change after the change before the control unit changes the lighting frequency A change notification unit that outputs change information including timing, and a setting of the second video camera based on the change information output from the change notification unit so that flicker does not occur in video captured by the second video camera. A voyeurism prevention system comprising: a setting changing unit for changing the setting.   The change notification unit is provided in the lighting control device, the setting change unit is provided in the second video camera, and transmission of the change information from the lighting control device to the setting change unit is performed between the lighting control device and the second control unit. The voyeurism prevention system according to claim 2, wherein the voyeurism prevention system is performed by communication with a video camera.   The lighting control device includes a transmission unit that performs visible light communication by superimposing the change information on light output from a communication light source, and the second video camera receives output light of the communication light source. The voyeurism prevention system according to claim 3, further comprising a receiving unit that acquires change information from the received output light of the communication light source.   The voyeurism prevention system according to claim 4, wherein the light emitting unit is also used as the communication light source. A projector comprising the lighting control device according to claim 1, wherein an image is projected onto a screen using the light emitting unit as a light source.

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