JP2011199448A - Photoelectric switch with communication function, and photoelectric switch system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and low-cost photoelectric switch with a communication function that displays switch information, without having to increase the number of components of the photoelectric switch and allows the threshold to be changed and set, and to provide a photoelectric sensor system.SOLUTION: The photoelectric switch with a communication function has a configuration, such that the switch includes a lighting and displaying means 11 for lighting and displaying an internal state of the photoelectric switch 1. The switch is configured to use the lighting and displaying means for its original function of lighting and displaying, and simultaneously, as a transmission means for optical communication that transmits switch information including the light-receiving amount and the threshold. Accordingly, the switch information is displayed on an external display apparatus 5 or the threshold is changed and set. Thereby, it becomes possible to display the switch information, without increasing the number of components of the photoelectric switch, and consequently, it is possible to attain the small and low-cost photoelectric switch.

Description

  The present invention relates to a photoelectric switch with a communication function and a photoelectric switch system for communicating the amount of light received by a photoelectric switch and a threshold value.

  Conventionally, the amount of light projected from the projector is blocked by the object and changed, or the amount of light reflected from the object is received by the receiver, and based on whether the amount of received light exceeds the threshold, A photoelectric switch for detecting the presence or absence is known.

  FIG. 13 shows an example of a conventional photoelectric switch. (A) is a transmissive photoelectric switch that receives light projected from the light projecting section T of the light projector 101 by the light receiving section R of the light receiver 102 and determines the presence or absence of the object based on the change in the amount of light blocked by the object. To detect. This photoelectric switch has a power supply line 107 in the projector 101 and a power supply / output line 108 in the light receiver 102. (B) is a reflective photoelectric switch that receives light emitted from the light projecting unit T of the light projecting and receiving device 103 by the light receiving unit R and detects the presence or absence of the object based on the amount of light reflected from the object. This photoelectric switch has a power source / output line 108 in the light emitter / receiver 103. Both the photoelectric switches in FIGS. 13A and 13B determine the stability indicator lamp 12 that is lit when the received light signal is stable, the output indicator lamp 13 that is lit when the object presence / absence judgment output is turned on, and the presence or absence of the object. Threshold adjustment means (volume) 105 for adjusting the threshold value of the received light amount serving as a reference to be output, and an output changeover switch 106 for switching whether the judgment output is turned on when light is incident or whether the judgment output is turned on when light is blocked by an object have. Examples of this include a photoelectric switch having a stable indicator lamp (for example, Patent Documents 1 and 2).

  By the way, when adjusting the optical axis when installing a photoelectric switch, or during maintenance inspection, it is necessary to adjust the optical axis based on numerical management without relying on the operator's senses. In order to judge whether the axis is in an optimal state, it is necessary to display and check the threshold value.

  For this reason, it is known that a photoelectric switch is provided with an LCD (display unit) to display the amount of received light and the threshold value numerically (for example, Patent Document 3). Also, instead of installing this display unit, a bidirectional communication means is provided in the photoelectric switch to transmit information on the amount of received light with an external device (for example, Patent Document 4), and light projection and reception of a reflective photoelectric switch. A method of sharing a circuit with optical communication is also known (for example, Patent Document 5).

JP-A-7-106938 JP 2005-303264 A JP-A-9-252242 JP 2002-334391 A Japanese Patent No. 3055714

  However, as in Patent Document 3, incorporating the display unit in the photoelectric switch main body increases the number of components, making it difficult to reduce the size of the product and increasing the manufacturing cost. The confirmation of the amount of received light and the threshold value is limited at the time of installation and maintenance inspection, so this display unit is unnecessary during normal operation. Also in Patent Document 4, it is necessary to add a bidirectional communication means in the photoelectric switch, and the number of components increases. Patent Document 5 discloses that in a transmissive photoelectric switch, a light projector and a light receiver are separated, and the light receiver is only a light receiving element and does not have a light projecting element. Can not.

  The present invention solves the above-described problems, and enables communication to display switch information and change and set a threshold value at a small size and low cost without increasing the number of components of the photoelectric switch. An object is to provide a photoelectric switch with function and a photoelectric sensor system.

In order to achieve the above object, a photoelectric switch with a communication function according to one configuration of the present invention includes a light projector, a light receiver that receives light projected from the light projector, and a lighting display that displays the internal state of the photoelectric switch. A photoelectric switch comprising means and a switch main body control unit that controls each unit and detects the presence or absence of an object based on a light amount change blocked by an object received by the light receiver or a light amount reflected from the object, The switch body control unit includes first communication signal generation means for generating a light signal of switch information including at least a received light amount by pulse-modulating a lighting signal from the lighting display means, and the light signal of the switch information Then, the switch information is transmitted from the lighting display means used for the transmission means for optical communication so that the switch information is displayed on the external display device.
Here, the lighting display means in the internal state is a stable indicator lamp that is lit when the same received light amount is continuously detected a predetermined number of times and the received light signal is stable, and the same received light amount exceeding the threshold value. Refers to an output indicator lamp that is lit when a predetermined number of consecutive detections are made and an object presence / absence determination output is turned on, and an indicator lamp that displays other internal conditions.

  According to this configuration, the lighting display means for lighting the internal state of the photoelectric switch is used for the original lighting display, and at the same time, used as the transmission means for optical communication for transmitting the switch information including the received light amount, By displaying the switch information on the external display device, the switch information can be displayed at a small size and at a low cost without increasing the number of components of the photoelectric switch.

  Preferably, the light signal of the switch information includes a threshold value of the amount of received light for determining the presence or absence of an object. Therefore, not only the amount of received light but also a threshold value necessary for optical axis adjustment of the photoelectric switch can be displayed.

  Preferably, when the lighting display means is lit to display the internal state of the photoelectric switch, the switch body control unit designates the communication signal state by the width of the off pulse and displays the internal state of the photoelectric switch. Therefore, when the light is turned off, the communication signal state is designated by the width of the on-pulse. Therefore, the switch information can be transmitted more easily by using the lighting signal from the lighting display means.

  A photoelectric switch system with a communication function according to another configuration of the present invention includes the photoelectric switch with a communication function, a light receiving element that receives an optical signal of the switch information transmitted from a lighting display means of the light receiver, and the switch information. And an external display device having a device control unit for controlling each unit.

  According to this configuration, the lighting display means is used for the original lighting display, and at the same time, it is also used as a transmission means for optical communication for transmitting switch information including the amount of received light, and the switch information transmitted to the external display device is used. By receiving and displaying, it is possible to display switch information with a small size, low cost, and simple configuration without increasing the number of components of the photoelectric switch.

  Preferably, the external display device further includes a light projecting element, and the device control unit changes the threshold value of the received light amount and sets a transmission signal from the light projecting element. Second communication signal generating means for generating an optical signal of switch information including the changed threshold value by pulse modulation, and the threshold value changed and set by the threshold value setting means, The light projecting element is transmitted to the light receiver of the photoelectric switch. Therefore, the threshold value changed and set by the external display device can be easily transmitted to the light receiver of the photoelectric switch.

  Preferably, the device control unit performs control to shift a timing at which the threshold signal changed and set from the light projecting element of the external display device is transmitted to the light receiver with respect to the light project timing of the light projector. Therefore, the light receiver can easily discriminate between the light projection signal and the changed threshold signal.

  By using the lighting display means for lighting and displaying the internal state of the photoelectric switch as the transmission means for transmitting the switch information, the switch information is transmitted to and displayed on an external display device without increasing the number of components of the photoelectric switch. The switch information can be displayed with small size and low cost.

It is a block diagram which shows the photoelectric sensor system which has a communication function which concerns on one Embodiment of this invention. It is a circuit diagram which shows the projector of a photoelectric sensor. It is a circuit diagram which shows the light receiver of a photoelectric sensor. It is a time chart which shows the basic object detection and stable operation | movement of a photoelectric sensor. It is a figure which shows the modulation | alteration waveform of the lighting signal of a stable indicator lamp. It is a circuit diagram which shows an external display apparatus. It is a front view which shows the external appearance shape of the external display apparatus of FIG. FIG. 7 is a circuit diagram for displaying a received light amount and a threshold value in the external display device of FIG. 6. FIG. 7 is a circuit diagram for transmitting a changed threshold signal in the external display device of FIG. 6. It is a figure which shows the modulation waveform of the signal transmitted from an external display apparatus. It is a time chart which shows operation | movement of a photoelectric sensor. It is a lineblock diagram showing a photoelectric sensor system which has a plurality of photoelectric sensors. (A), (B) is a block diagram which shows the conventional photoelectric sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a photoelectric sensor system with a communication function according to an embodiment of the present invention. This photoelectric sensor system includes a photoelectric sensor 1 for detecting the presence / absence of an object and an external display device 5, and the received light amount obtained by the photoelectric sensor 1 in the external display device 5 and the received light amount serving as a reference for determining the presence / absence of an object. The threshold value is displayed, and the threshold value is changed and set.

  The photoelectric sensor 1 includes a projector 2, a light receiver 3 that receives the light projected from the projector 2, and the presence or absence of an object based on a change in the amount of light blocked by the object received by the light receiver 3 by controlling each unit. And a switch body control unit 7 (FIG. 3) for detecting the above. In this example, the transmission type is used, but the present invention may be applied to a reflection type that detects the presence or absence of an object based on the amount of light reflected from the object. The projector 2 includes a light projecting unit T that projects light and a power line 9 that supplies power.

  The light receiver 3 includes a stable indicator lamp 12 and an output indicator lamp 13 as a lighting display means 11 for displaying the internal state of the photoelectric sensor 1 in addition to the light receiver R and the power source / output line 14. The stability indicator lamp 12 is lit when the same amount of received light is continuously detected a predetermined number of times and the received light signal is stable. The output indicator lamp 13 is lit when the same received light amount is continuously detected a predetermined number of times and the object presence / absence determination output is turned on based on comparison with a threshold value.

  Unlike the conventional photoelectric switch, this photoelectric switch 1 does not require an output changeover switch and threshold value setting means (volume). Since the volume is usually adjusted or selected by rotating it, it is necessary to provide waterproofing. However, since the volume is not provided, it is not necessary to ensure waterproof performance, and a low-cost and highly reliable photoelectric switch can be realized.

  As shown in FIG. 2, the projector 2 projects pulsed light from the light projecting element 4 toward the light receiver 3. The light projecting pulse generating circuit 6 and the light projecting element 4 generate a light projecting pulse. Has a light projecting element driving circuit 8 for driving.

  FIG. 3 shows a circuit diagram of the light receiver 3. The switch main body control unit 7 is a component obtained by removing the light receiving element 21, the differential amplifier circuit 22, the stability indicator lamp 12, and the output indicator lamp 13 from the configuration of FIG. In the circuit diagram of FIG. 3, as a basic configuration of object detection and stable display in the photoelectric sensor 1, a light receiving element 21 that receives light projected from the projector 2, and a differential amplification circuit 22 that differentiates and amplifies the received light signal. , A voltage comparator 23 that compares the received light amount with a threshold value, a threshold value unit 24 that stores the threshold value, a D / A converter 25, a continuous number counter 26 that counts the continuous number of times of the same received light amount state, the presence or absence of an object The first continuous confirmation unit (confirms that the same result is 10 times continuous) 27, the determination result output circuit 28, and the second continuous confirmation unit (confirms that the same result is 3 times) In addition to 29 (confirm continuity), the above-mentioned stability indicator lamp 12 driven by the stability indicator lamp drive circuit 46 and the output indicator lamp 13 driven by the output indicator lamp drive circuit 30 are provided.

  FIG. 4 shows internal operation timing and operation waveforms for basic object detection and stable display in the photoelectric sensor. (A) to (f) show the states when the presence of an object is detected, and (g) to (l) show the states when no object is detected. First, (a) is a light projection waveform generated by the light projector 2 and converted into a light pulse projected from the light projecting element 4. (B) is a light reception waveform received by the light receiving element 21 of the light receiver 3 and converted into an electric signal. As shown in (c), only the pulse component is amplified by the differential amplifier circuit 22 in order to remove unnecessary external light. As shown in (d), the amplified signal is counted by the continuous number counter 26. As shown in (e), when the determination output is turned on continuously for a plurality of times (for example, 10 times) at a voltage higher than the set threshold value, the output indicator lamp 13 is turned on. As shown in (f), the stability indicator lamp 12 is turned on when the received light signal is stable continuously for a plurality of times (for example, three times) in the same high state. On the other hand, when the absence of an object is detected, (g) to (j) operate in the same manner as described above, and in the case of a voltage lower than the reversely set threshold as shown in (k), the determination is made. The output is turned off and the output indicator lamp 13 is turned off. Then, as shown in (l), the stability indicator lamp 12 is turned on when the received light signal is stable continuously for a plurality of times (for example, three times) in the same low state.

  In the circuit diagram of FIG. 3, as a threshold setting configuration, the light receiver 3 includes a changed threshold value transmitted from an external display device 5 described later in addition to the light receiving element 21 and the differential amplifier circuit 22. A pulse width measuring section 34 for measuring the pulse width of the signal, a first pulse width confirming section (for confirming the pulse width at level 0) 35 for confirming the pulse width at level 0, and a first pulse width confirming section for confirming the pulse width at level 1. 2 pulse width confirmation unit (confirm level 1 pulse width) 36, shift register 37 for storing binarized data of level (0, 1), header identification unit 38 for identifying the header of the data, A checksum calculator 39 that calculates whether the checksum value obtained by adding the header and the threshold value matches the received checksum value. If both checksum values match, the threshold value is valid. Store And a threshold at storage unit 40. The changed threshold value is sent to the threshold value unit 24.

  On the other hand, in the circuit diagram of FIG. 3, as a configuration of the received light amount display and pulse modulation, the light receiver 3 stores the A / D converter 41 and the detected received light amount in addition to the light receiving element 21 and the differential amplifier circuit 22. The received light amount part 42 is provided. Further, a shift register 43 for storing threshold value data of the threshold value unit 24 and received light amount data of the received light amount unit 42, a transmission pulse generating circuit 44 for generating a transmission pulse, and a lighting signal for the stable indicator lamp 12 are provided. A stable indicator lamp pulse modulation circuit (first communication signal generating means) 45 that generates an optical signal of switch information by pulse modulation, and a stable indicator lamp drive circuit 46 that drives the stable indicator lamp 12 are provided.

  FIG. 5 shows a modulation waveform of the lighting signal of the stable indicator lamp 12, and a communication optical signal including a received light amount and a threshold value is generated by pulse-modulating the lighting signal from the lighting signal of the stable indicator lamp 12. The (A) is a waveform in which a level 0 signal is modulated by an on-pulse when the stability indicator lamp 12 is extinguished, and (b) is a waveform in which a level 1 signal is modulated in (a). (C) is a waveform in which a level 0 signal is modulated by an off pulse when the stability indicator lamp 12 is lit, and (d) is a waveform in which a level 1 signal is modulated in (c). As described above, when the stability indicator lamp 12 is lit to display the internal state of the photoelectric switch 1, the communication signal state is designated by the width of the off pulse, and when it is unlit, the communication signal is represented by the width of the on pulse. Specify the state. (E) shows an example of transmission of an optical signal including the amount of received light and a threshold value. This communication signal constitutes serial data. The header is followed by a binarized received light amount and threshold value switch information, and a checksum is added.

  The stability indicator lamp 12 is originally turned on when the same amount of received light is continuously detected a predetermined number of times and the received light signal is stable, and is turned off when the light reception signal is stable, so that the detection state of the photoelectric switch 1 is stable. It is made to recognize whether it is doing. If the indicator lamp 12 is used as it is as a transmission means for optical communication, it will be turned on even when it is desired to turn it off, so that it will not be used as the stable indicator lamp 12. Thus, when the stability indicator lamp 12 is turned off, the lighting time ratio of the optical communication data can be made extremely short to make it appear almost the same as the off state. For example, modulation by communication is suppressed to about 1/100 of the whole. In addition, by synchronizing the pulse modulation timing with the light reception signal, it is possible to prevent a change in current consumption generated by this modulation from changing the amount of light received.

  FIG. 6 shows the configuration of the external display device 5, and FIG. 7 is a front view showing the external shape of the external display device 5. The external display device 5 shown in FIG. 1 is a wireless and portable remote controller that is operated close to the light receiver 3, and receives the light projected from the stable indicator lamp 12 as shown in FIG. A light receiving element 51, a light projecting element 68 that projects light onto the light receiving element 21 of the light receiver 3, a light receiving amount transmitted from the stability indicator lamp 12, a display unit 70 that displays a threshold value, and a threshold value for changing and setting the threshold value. A threshold addition button 71, a threshold subtraction button 72, an output mode switching button 73, and a data transmission button 74 for transmitting data to the optical receiver 3 are provided. The output mode switching button 73 is the same as the output switching switch 106 in FIG. 13 and switches whether the judgment output is turned on when light is incident (L) or turned on when the light is blocked (D).

  A device control unit 50 that controls each part of the external display device 5 in FIG. 6 includes a light receiving element 51, a differential amplification circuit 22, a light projecting element 68, and a display unit 70 that differentiate and amplify the received light signal from the configuration of FIG. It is a component excluded. Among the configurations of the external display device 5 of FIG. 6, FIG. 8 shows a configuration for displaying the received light amount and the threshold value. In FIG. 8, in addition to the light receiving element 51 and the differential amplifier circuit 52, the external display device 5 measures the received light amount included in the optical signal transmitted from the stable indicator lamp 12 and the pulse width of the threshold value. 53, a third pulse width confirmation unit (confirming the pulse width of level 0) 54 for confirming the pulse width of level 0, and a fourth pulse width confirmation unit (confirming the pulse width of level 1) for confirming the pulse width of level 1 (Check pulse width) 55, shift register 56 for storing binarized data of level (0, 1), header identification unit 57 for identifying the head header of data, header, received light amount and threshold value are added The checksum calculator 58 calculates whether the checksum value matches the received checksum value. If both checksum values match, the received light amount is stored as a valid received light amount and threshold value. - threshold storage unit 59, and the received light amount, and a light receiving quantity and the threshold value display unit 60 for displaying the threshold value.

  FIG. 9 shows a configuration in which the threshold value is changed and transmitted to the light receiver 3 in the configuration of the external display device 5 of FIG. In addition to the light receiving element 51 and the differential amplifier circuit 52, the external display device 5 includes a light receiving timing detection unit 61 that detects the light receiving timing of the optical signal transmitted from the stable indicator lamp 12 that is equivalent to the light projecting timing of the projector 2. A light projection timing generation unit (light projection timing) that generates a timing for shifting the timing at which the threshold signal changed and set from the light projecting element 68 of the external display device 5 is transmitted to the light receiver 3 with respect to the light project timing of the light projector 2 Generating means) 62, a threshold setting section (threshold setting means) 63 for changing and setting the threshold value, a threshold value section 64 for storing the threshold value, and storing binarized threshold value data Shift register 65, and a transmission pulse generation circuit (second communication signal generation) for generating a switch information optical signal including a threshold value changed by pulse modulation of a transmission signal from a light projecting element Stage) 66, and a light emitting element 68 to transmit the light projecting device drive circuit 67 drives the light projecting element 68, and changes the set threshold signal.

  FIG. 10 shows the modulation waveform of the transmission pulse for changing the threshold value and causing the optical receiver 3 to write the threshold value, and shows the timing and operation waveform of the threshold value writing. (A) is the light reception waveform of the transmission signal from the stability indicator lamp 12, (b) is the waveform after differential amplification, and (c) is the transmission signal from the stability indicator lamp 12 detected by the light reception timing detector 61. Light reception timing, (d) is a light projection timing generated by the light projection timing generation unit 62 and shifted from the light reception timing of (c), (e) is a transmission pulse generated by the transmission pulse generation circuit 66, (f) Indicates an example of transmission of an optical signal including a threshold value. This communication signal constitutes serial data, and includes a header followed by binarized threshold switch information and a checksum added.

  In the circuit diagram of the light receiver 3 in FIG. 3, the light receiver 3 is configured to discriminate between the light projection waveform of the light projector 2 and the light projection waveform from the external display device 5. The light receiver 3 includes a light receiving element 21 and a differential amplifier circuit 22. In addition to the above, a light projecting period synchronizing circuit 31 for synchronizing with a light projecting signal from the light projecting device 2, a discriminating circuit 33 for discriminating a light projecting signal from the light projecting device 2 and a threshold signal from the external display device 5, and a discriminating circuit 33 And a discrimination circuit switching signal generation circuit 32 for generating a signal for switching between.

  FIG. 11 is a timing chart for receiving an optical signal including a threshold value from the external display device 5 in the photoelectric switch 1. (A) is a projection waveform of the projector 2 of the photoelectric switch 1, (b) is a projection waveform from the projection element 68 of the external display device 5 whose timing is shifted from that of the projector 2 of (a), (C) is a light reception waveform of the light receiver 3 of the photoelectric switch 1, (d) a waveform after differential amplification, (e) is a light projection period synchronization signal, (f) is a discrimination circuit switching signal, and (g) is a photoelectric switch 1 (H) is a received light waveform received by the light receiver 3 of the photoelectric switch 1 and (i) is a waveform obtained by demodulating (h). Indicates. In this way, the light receiver 3 discriminates the waveform of the optical signal with the changed threshold value transmitted from the external display device 5 from the light projection waveform of the light projector 2, and allows the light receiver 3 to accurately receive the light waveform. it can.

  Thus, in the present invention, the lighting display means 11 for lighting and displaying the internal state of the photoelectric switch 1 is used for the original lighting display, and at the same time, for optical communication for transmitting switch information including the amount of received light and the threshold value. Displaying switch information on the external display device 5 as a transmission means, or by changing and setting a threshold value, the switch information is displayed in a small size and at a low cost without increasing the components of the photoelectric switch. It becomes possible.

  FIG. 12 shows a wireless and portable remote controller in which a plurality of photoelectric switches 1 with communication functions are connected and arranged, and the external display device 5 is single, and is operated close to each light receiver 3. It is. Therefore, even if a plurality of photoelectric switches are connected and arranged, the amount of light received and the threshold value of each light receiver 3 can be displayed with a simple configuration by a single external display device, and the threshold value can be changed and set. Can do.

  In this embodiment, the stability indicator lamp 12 is also used as a transmission means for communication for transmitting switch information. However, the output indicator lamp 13 and other lighting means for transmitting information on the internal state may be used. Good.

  In this embodiment, an optical signal including the amount of received light and the threshold value is transmitted from the stable indicator lamp 12, but an optical signal including only the amount of received light may be transmitted.

1: Photoelectric switch with communication function 2: Projector 3: Receiver 5: External display device 7: Switch main body control unit 11: Illumination display means 12: Stable indicator lamp 13: Output indicator lamp 45: First communication signal generator means 50: Device control unit 51: light receiving element 62: light projection timing generating circuit 63: threshold value setting means 66: second communication signal generating means 68: light projecting element 70: display part

Claims (6)

A light emitter, a light receiver that receives the light emitted from the light projector, a lighting display means that lights and displays the internal state of the photoelectric switch, and a change in the amount of light blocked by an object received by the light receiver by controlling each part Or a photoelectric switch comprising a switch body control unit that detects the presence or absence of an object based on the amount of light reflected from the object,
The switch main body control unit includes first communication signal generation means for generating a light signal of switch information including at least a received light amount by pulse-modulating a lighting signal from the lighting display means,
A photoelectric switch with a communication function, wherein an optical signal of the switch information is transmitted from the lighting display means used as a transmission means for optical communication so that the switch information is displayed on an external display device. In claim 1,
A photoelectric switch with a communication function, wherein the optical signal of the switch information includes a threshold value of received light amount for determining the presence or absence of an object. In claim 1,
When the lighting main display unit is lit to display the internal state of the photoelectric switch, the switch body control unit designates the communication signal state by the width of the off pulse and displays the internal state of the photoelectric switch. A photoelectric switch with a communication function that specifies the communication signal state with the width of the on-pulse when it is off. A photoelectric switch with a communication function according to any one of claims 1 to 3,
A light receiving element that receives an optical signal of the switch information transmitted from the lighting display means of the light receiver, a display that displays the switch information, and an external display device that has a device control unit that controls each part;
Photoelectric switch system with communication function. In claim 4,
The external display device further includes a light projecting element,
The device control unit includes threshold setting means for changing and setting the threshold of the amount of received light, and switch information including the changed and set threshold by pulse-modulating a transmission signal from the light projecting element. Second communication signal generating means for generating an optical signal,
A photoelectric switch system with a communication function, wherein the threshold value changed and set by the threshold value setting means is transmitted to a light receiver of the photoelectric switch by the light projecting element. In claim 5,
The device control unit is a photoelectric switch with a communication function for performing control to shift a timing for transmitting a threshold signal changed and set from a light projecting element of the external display device to a light receiver with respect to a light projecting timing of the light projector system.

Images