JP2018101925A - Light-receiving element multiplexer and scanning laser radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-receiving element multiplexer for switching and outputting signals outputted from a plurality of light receiving elements, which can appropriately detect a failure mode.SOLUTION: A light receiving element multiplexer 100 includes: a plurality of light receiving elements PD, a first light source LED1 that irradiates light so that the light receiving intensities of the light receiving elements are different from each other; a control unit CTL for controlling lighting of the first light source; a multiplexer MUX connected to each of the plurality of light receiving elements, for switching input signals from the light receiving elements and outputting the input signals; and a failure detection unit FD for detecting a failure of the multiplexer on the basis of a first output value of the multiplexer when the control unit turns on the first light source while the multiplexer is in the first connection state and a second output value of the multiplexer when the control unit turns on the first light source while the multiplexer is in a second connection state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light receiving element multiplexer and a scanning laser radar apparatus including the same, and more particularly to a light receiving element multiplexer that detects its own failure and a scanning laser radar apparatus including the same.

  2. Description of the Related Art Conventionally, a technique for detecting a failure of a multiplexer that switches and outputs a plurality of analog input signals is known. For example, Patent Document 1 discloses a multiplexer circuit that can accurately detect an abnormal operation of a multiplexer. The multiplexer circuit sequentially receives analog input signals input from a plurality of channels, multiplexes the input signals and outputs the multiplexer, and a plurality of digital inputs corresponding to the analog input signals output from the multiplexer. When the AD converter for converting to an output signal and the output values of a plurality of digital output signals are monitored, and the state where all the output values are within a predetermined range continues for a predetermined determination time, A processing device that determines that the operation of the multiplexer is in an abnormal state and a pulse signal generator that outputs a pulse signal having a cycle shorter than the determination time to the multiplexer as one of the analog input signals.

JP 2010-263420 A

  The present invention provides a light receiving element multiplexer that appropriately detects a failure mode in a light receiving element multiplexer that switches and outputs signals output from a plurality of light receiving elements.

In order to solve the above problems, a plurality of light receiving elements, a first light source that emits light so that the light receiving intensity of each light receiving element is different, a control unit that controls lighting of the first light source, and a plurality of light receiving elements A multiplexer connected to each of the light receiving elements to switch and output the input signal; a first output value of the multiplexer when the control unit turns on the first light source when the multiplexer is in the first connection state; A light receiving element multiplexer is provided that includes a failure detection unit that detects a failure of the multiplexer based on a second output value of the multiplexer when the control unit turns on the first light source in the second connection state.
According to this, in the light receiving element multiplexer that switches and outputs the signals output from the plurality of light receiving elements, it is possible to provide a light receiving element multiplexer that appropriately detects the failure mode using the function of the multiplexer.

Furthermore, the light source is further provided with a second light source that emits light so that the received light intensity is different in each light receiving element, the control unit controls the lighting of the second light source, and the failure detection unit outputs the first output value and the second output. The value, the third output value of the multiplexer when the control unit lights the second light source when the multiplexer is in the first connection state, and the control unit lights the second light source when the multiplexer is in the second connection state A failure of the multiplexer may be detected based on the fourth output value of the multiplexer.
According to this, the failure mode can be detected more accurately by having two light sources.

Further, the plurality of light receiving elements may be arranged in a line, and the first light source may be provided closest to one of the light receiving elements located at the end of the plurality of light receiving elements.
According to this, the failure mode can be detected with a simple structure by arranging the light sources so that the light receiving intensities of the light receiving elements are different.

Furthermore, the plurality of light receiving elements are arranged in a line, the first light source is provided closest to one of the light receiving elements located at the end of the plurality of light receiving elements, and the second light source includes the plurality of light receiving elements. The light receiving element may be provided closest to the other light receiving element located at the end.
According to this, the failure mode can be detected more accurately with a simple structure by arranging the two light sources so that the received light intensity in the light receiving element is different.

  ADVANTAGE OF THE INVENTION According to this invention, in the light receiving element multiplexer which switches and outputs the signal which the several light receiving element output, the light receiving element multiplexer which detects a failure mode appropriately using the function of the said multiplexer can be provided.

1 is a block diagram of a light receiving element multiplexer according to a first embodiment of the present invention. FIG. FIG. 2A is a circuit diagram of a light receiving element in the light receiving element multiplexer according to the first embodiment of the present invention, and FIG. In the light receiving element multiplexer according to the first embodiment of the present invention, (A) a multiplexer operating normally with the first light source on / second light source off, and (B) the first light source off / second light source. (C) A graph showing the distribution of received light intensity output from the multiplexer during normal operation. In the multiplexer for a light receiving element according to the first embodiment of the present invention, (A) a multiplexer during abnormal operation (at the time of sticking failure) with the first light source on and the second light source off, and (B) the first light source The graph which shows the distribution of the light reception intensity | strength output from a multiplexer at the time of abnormal operation (at the time of a sticking failure), and (C) abnormal operation (at the time of a sticking failure) in the state where the off / second light source is on. In the multiplexer for the light receiving element according to the first embodiment of the present invention, (A) a multiplexer during abnormal operation (when the first light source is on / second light is off) (at the time of disconnection between the light receiving element PD1 and the multiplexer), B) Multiplexer during abnormal operation (disconnection between light receiving element PD1 and multiplexer) with first light source off / second light source on, (C) Abnormal operation (disconnected between light receiving element PD1 and multiplexer) The graph which shows distribution of the received light intensity output from a multiplexer. In the multiplexer for the light receiving element according to the first embodiment of the present invention, (A) a multiplexer in an abnormal operation (short failure between the light receiving element and the multiplexer) when the first light source is on and the second light source is off, B) Multiplexer during abnormal operation (short failure between light receiving element and multiplexer) with first light source off / second light source on, (C) Abnormal operation (short failure between light receiving element and multiplexer) The graph which shows distribution of the received light intensity output from a multiplexer. (A) Top view, (B) Front view, (C) Perspective view, (D) Cover etc. of the scanning laser radar device to which the light receiving element multiplexer according to the first embodiment of the present invention is applied. FIG.

<First Example>
With reference to FIG. 1, a light receiving element multiplexer 100 in the present embodiment will be described. The light receiving element multiplexer 100 has channels CNL1 to CNL4 to which analog signals output from the plurality of light receiving elements PD1 to PD4, respectively, are input. The channels CNL1 to CNL4 are switched and sequentially received, and analog input signals are multiplexed. It is a device that outputs in the form. The light receiving element multiplexer 100 will be described as an example having four light receiving elements PD1 to PD4 and corresponding channels CNL1 to CNL4. Of course, it is not limited to this. The light receiving element multiplexer 100 is electrically connected to the AD converter ADC via a variable gain amplifier VGA that amplifies the output signal, and outputs the multiplexed signal to the AD converter ADC.

  The light receiving element multiplexer 100 includes a plurality of light receiving elements PD1 to PD4, a first light source LED1 and a second light source LED2 that irradiate light such that the light receiving intensities of the light receiving elements PD1 to PD4 are different, a first light source LED1 and a first light source LED1. A control unit CTL that controls the lighting of the two light sources LED2, a multiplexer MUX that is connected to each of the plurality of light receiving elements PD1 to PD4 and that switches and outputs an input signal from each of the light receiving elements PD1 to PD4, and a light receiving element multiplexer 100 And a failure detection unit FD that detects the failure.

  Each of the light receiving elements PD1 to PD4 includes, as shown in FIG. 2A, an element PD such as a photodiode that converts light energy into electric energy, and a transimpedance amplifier that converts a current output from the element PD into a voltage signal. It consists of TIA. As shown in FIG. 2B, the light receiving elements PD1 to PD4 constitute a light receiving element array arranged in a line in the vertical direction in the figure on the substrate PLT. Of course, the present invention is not limited to this. For example, the light receiving element array may be arranged in a two-dimensional direction such as a rectangular shape or an annular shape. However, the light receiving element array is preferable because the light receiving elements are arranged one-dimensionally and have a simple structure.

  The light receiving elements PD1 to PD4 and the input terminals of the multiplexer MUX are electrically connected one-to-one with the channels CNL1 to CNL4. The multiplexer MUX switches the channels to be output between the channels CNL1 to CNL4 so that one input terminal and the output terminal are connected at one time point between the four input terminals and one output terminal.

  1st light source LED1 and 2nd light source LED2 are light emitting diodes, It is preferable to select the light emitting diode which light-emits the light of the wavelength suitable for the peak value of the sensitivity wavelength of light receiving element PD1-PD4. 1st light source LED1 irradiates light so that the light reception intensity | strength in each light receiving element PD1-PD4 may differ. In this embodiment, the light receiving elements PD1 to PD4 are arranged in a line, and will be described with reference to FIG.

  The first light source LED1 is provided closest to one of the light receiving elements PD1 located at the end of the plurality of light receiving elements PD1 to PD4. That is, the first light source LED1 irradiates the light receiving element PD1 with a distance L1 to the light receiving element PD1. Similarly, the first light source LED1 irradiates light to the light receiving element PD2 with a distance L2 to the light receiving element PD2, and irradiates light to the light receiving element PD3 with a distance L3 to the light receiving element PD3. The light receiving element PD4 is irradiated with light with a distance L4 to the element PD4. Therefore, the first light source LED1 and the light receiving elements PD1 to PD4 are arranged so that the relationship of L1 <L2 <L3 <L4 is established. If the distance from the light source is short, the received light intensity is large (the amount of received light is large), and if it is far away, the received light intensity is small (the received light amount is small). Therefore, by arranging the light receiving elements PD1 to PD4 so that the respective distances from the first light source LED1 are different, the first light source LED1 emits light so that the light receiving intensities in the respective light receiving elements PD1 to PD4 are different. become.

  The arrangement of the light receiving elements PD1 to PD4 so that the respective distances from the first light source LED1 are different is an example, and the present invention is not limited to this. For example, even when the light source is arranged in the center of the light receiving element array, the light receiving intensity of each light receiving element may be different by attaching a filter that varies the amount of light irradiated to each light receiving element at the light source irradiation port. May be irradiated with light. In the present embodiment, the light irradiation port of the first light source LED1 is arranged to face the light receiving surfaces of the light receiving elements PD1 to PD4. However, the present invention is not limited to this, and the irradiation port is in the same direction as the light receiving surface. The light receiving element may receive the reflected light from the reflecting plate. According to this, since the distance between the light source and the light receiving element is doubled, the difference in received light intensity is large with respect to the physical distance to be arranged, and it is easy to make a difference.

  Similar to the first light source LED1, the second light source LED2 emits light so that the light receiving intensities of the light receiving elements PD1 to PD4 are different. That is, the second light source LED2 is provided closest to the other light receiving element PD4 located at the end of the plurality of light receiving elements PD1 to PD4. In addition, as above-mentioned in 1st light source LED1, it is an example that 2nd light source LED2 is arrange | positioned in this way.

  When detecting the failure mode of the light receiving element multiplexer 100, the control unit CTL controls the lighting of the first light source LED1 and the second light source LED2, as will be described later. Note that the control unit CTL controls the first light source LED1 and the second light source LED2 to be off while the light receiving elements PD1 to PD4 are being used as original functions.

  The failure detection unit FD is for the light receiving element based on the lighting state of the first light source LED1 and the second light source LED2 obtained from the control unit CTL, the switching state of the channels CNL1 to CNL4 of the multiplexer MUX, and the output value of the multiplexer MUX. A failure mode of the multiplexer 100 is detected. A failure mode detection method of the failure detection unit FD will be described with reference to FIGS.

  FIG. 3 shows output values of received light intensity of the light receiving elements PD1 to PD4 when the light receiving element multiplexer 100 operates normally. This figure (A) shows the state which control part CTL is controlling 1st light source LED1 to ON and 2nd light source LED2. In this state, the multiplexer MUX switches the channels CNL1 to CNL4. Then, the received light intensity at each of the light receiving elements PD1 to PD4, which is the output value of the multiplexer MUX, is represented by a black circle mark in FIG. The black circle mark has the highest light reception intensity in the light receiving element PD1, and the light reception intensity is lowest in the light receiving element PD4. That is, since the first light source LED1 and the light receiving elements PD1 to PD4 are arranged so that the relationship L1 <L2 <L3 <L4 is established, the first light source LED1 is closest to the light receiving element PD1. The light receiving intensity at the light receiving element PD1 is the highest, the light receiving intensity at the light receiving element PD2 is next highest, the light receiving intensity at the light receiving element PD3 is next highest, and the light receiving intensity at the light receiving element PD4 is the lowest. The received light intensity in the light receiving elements PD1 to PD4 appearing in the output value changes in proportion to the distance (L1, L2, L3, L4) from the first light source LED1 to the light receiving elements PD1 to PD4.

  This figure (B) shows the state which control part CTL is controlling 1st light source LED1 to OFF and 2nd light source LED2. In this state, the multiplexer MUX switches the channels CNL1 to CNL4. Then, the light receiving intensity in each of the light receiving elements PD1 to PD4, which is the output value of the multiplexer MUX, is represented by a white circle mark in FIG. The white circle mark has the smallest light receiving intensity in the light receiving element PD1 and the largest light receiving intensity in the light receiving element PD4. Since the light receiving intensity in the light receiving elements PD1 to PD4 appearing in the output value changes in proportion to the distance from the second light source LED2 to the light receiving elements PD1 to PD4, the tendency is completely opposite to that of the first light source LED1.

  Thus, the light receiving intensity of the light receiving elements PD1 to PD4 when the light receiving element multiplexer 100 is in normal operation is proportional to the distance between the first light source LED1 and the second light source LED2 and the light receiving elements PD1 to PD4. Therefore, in the failure detection unit FD, the received light intensity when the first light source LED1 is turned on is proportional to the distance between the first light source LED1 and each of the light receiving elements PD1 to PD4, and the received light intensity when the second light source LED2 is turned on. Is proportional to the distance between the second light source LED2 and each of the light receiving elements PD1 to PD4, it can be determined that the light receiving element multiplexer 100 is operating normally.

  FIG. 4 shows output values and the like when the selector switch of the multiplexer MUX is fixed to the channel CNL1 of the light receiving element PD1 in the light receiving element multiplexer 100. This figure (A) shows the state which control part CTL is controlling 1st light source LED1 to ON and 2nd light source LED2. In this state, the multiplexer MUX tries to switch the channels CNL1 to CNL4. However, since the selector switch of the multiplexer MUX is fixed to the channel CNL1, it cannot be switched to the channels CNL2 to CNL4. Then, since the light reception intensity that is the output value of the multiplexer MUX is output only as the light reception intensity of the light receiving element PD1, as represented by the black circle in FIG. is there. That is, since the received light intensity appearing in the output value does not change in proportion to the distance from the first light source LED1 to the light receiving elements PD1 to PD4, it can be determined that an abnormality has occurred.

  This figure (B) shows the state which control part CTL is controlling 1st light source LED1 to OFF and 2nd light source LED2. In this state, the multiplexer MUX tries to switch the channels CNL1 to CNL4. However, since the selector switch of the multiplexer MUX is fixed to the channel CNL1, it cannot be switched to the channels CNL2 to CNL4. Then, since the light reception intensity that is the output value of the multiplexer MUX is output only as the light reception intensity of the light receiving element PD1, as indicated by the white circles in FIG. is there. That is, since the received light intensity appearing in the output value does not change in proportion to the distance from the second light source LED2 to the light receiving elements PD1 to PD4, it can be determined that an abnormality has occurred.

  As described above, in the light receiving element multiplexer 100, the received light intensity appearing in the output value does not change in proportion to the distance between the first light source LED1 and the second light source LED2 and the light receiving elements PD1 to PD4, and thus an abnormality has occurred. It can be judged. Furthermore, since only a constant output value is output even when the channels CNL1 to CNL4 are switched, it can be determined that the changeover switch of the multiplexer MUX is stuck. Since the value with the highest light reception intensity when the first light source LED1 is turned on and the value with the smallest light reception intensity when the second light source LED2 is turned on are output, the channel CNL1 that transmits the light reception intensity of the light receiving element PD1 is output. It can be determined that the changeover switch is fixed.

  FIG. 5 shows output values when the channel CNL1 connecting the light receiving element PD1 and the input terminal of the multiplexer MUX in the light receiving element multiplexer 100 is disconnected. This figure (A) shows the state which control part CTL is controlling 1st light source LED1 to ON and 2nd light source LED2. In this state, the multiplexer MUX switches the channels CNL1 to CNL4. Then, the light reception intensity at each of the light receiving elements PD1 to PD4, which is the output value of the multiplexer MUX, is the same as that during normal operation as indicated by the black circles in FIG. However, the received light intensity at the light receiving element PD1 is zero. That is, since the received light intensity appearing in the output value does not change in proportion to the distance between the first light source LED1 and the light receiving elements PD1 to PD4, it can be determined that an abnormality has occurred.

  This figure (B) shows the state which control part CTL is controlling 1st light source LED1 to OFF and 2nd light source LED2. In this state, the multiplexer MUX switches the channels CNL1 to CNL4. Then, the received light intensity, which is the output value of the multiplexer MUX, is changed in the same manner as during normal operation, as shown by the white circles in FIG. However, the received light intensity in the light receiving element PD1 is zero. That is, since the received light intensity appearing in the output value does not change in proportion to the distance between the second light source LED2 and the light receiving elements PD1 to PD4, it can be determined that an abnormality has occurred.

  In this way, in the light receiving element multiplexer 100, the light reception intensity appearing in the output value does not change in proportion to the distance between the first light source LED1 and the second light source LED2 and the light receiving elements PD1 to PD4, and thus an abnormality has occurred. It can be judged. Further, when either the first light source LED1 or the second light source LED2 is turned on, only the output value of the light receiving element PD1 is zero, and therefore the channel CNL1 connecting the light receiving element PD1 and the input terminal of the multiplexer MUX is disconnected. Judgment can be made.

  FIG. 6 shows output values when the channel CNL1 connecting the light receiving element PD1 and the input terminal of the multiplexer MUX, and the channel CNL2 connecting the light receiving element PD2 and the input terminal of the multiplexer MUX are short-circuited in the light receiving element multiplexer 100. . This figure (A) shows the state which control part CTL is controlling 1st light source LED1 to ON and 2nd light source LED2. In this state, the multiplexer MUX switches the channels CNL1 to CNL4. Then, the light reception intensity at each of the light receiving elements PD1 to PD4, which is the output value of the multiplexer MUX, is the same as that during normal operation, as indicated by the black circles in FIG. However, the light receiving intensity of the light receiving element PD1 is the same as that of the light receiving element PD2. The received light intensity is approximately half of the sum of the received light intensity of the light receiving elements PD1 and PD2 during normal operation. That is, since the received light intensity appearing in the output value does not change in proportion to the distance between the first light source LED1 and the light receiving elements PD1 to PD4, it can be determined that an abnormality has occurred.

  This figure (B) shows the state which control part CTL is controlling 1st light source LED1 to OFF and 2nd light source LED2. In this state, the multiplexer MUX switches the channels CNL1 to CNL4. Then, the received light intensity, which is the output value of the multiplexer MUX, is changed in the same manner as during normal operation, as indicated by the white circles in FIG. However, the light receiving intensities of the light receiving element PD1 and the light receiving element PD2 are the same. The received light intensity is approximately half of the sum of the received light intensity of the light receiving elements PD1 and PD2 during normal operation. That is, since the received light intensity appearing in the output value does not change in proportion to the distance between the first light source LED1 and the light receiving elements PD1 to PD4, it can be determined that an abnormality has occurred.

  As described above, in the light receiving element multiplexer 100, the received light intensity appearing in the output value does not change in proportion to the distance between the first light source LED1 and the second light source LED2 and the light receiving elements PD1 to PD4, and thus an abnormality has occurred. It can be judged. Further, when either the first light source LED1 or the second light source LED2 is turned on, the received light intensity in the light receiving element PD1 and the light receiving element PD2 is the same as the output value, and the received light intensity is the light receiving element PD1 during normal operation. Therefore, it can be determined that the channel CNL1 and the channel CNL2 are short-circuited.

  In this way, a multiplexer having a plurality of light receiving elements includes a light source that irradiates each light receiving element with different received light intensity, and when the light source is turned on, the multiplexer channel is switched to evaluate the output value. The failure mode can be detected appropriately. That is, the failure detection unit FD switches the first output value of the multiplexer MUX and the changeover switch when the control unit CTL lights the first light source LED1 when the multiplexer MUX is in the first connection state, and the multiplexer MUX A failure of the multiplexer MUX is detected based on the second output value of the multiplexer MUX when the control unit CTL lights up the first light source LED1 when in the second connection state different from the one connection state. According to this, in the light receiving element multiplexer 100 that switches and outputs the signals output from the plurality of light receiving elements, the function of the multiplexer that switches the channel while receiving the light from the light source for failure detection is used. It is possible to provide the light receiving element multiplexer 100 that appropriately detects the mode.

  In this embodiment, there are two light sources. However, even if there is only one light source as described above, a failure mode can be realized by using a multiplexer function of switching channels while receiving light from the light source. Can be detected appropriately. However, it is preferable to use two light sources because the failure mode can be detected more accurately.

  When there are two light sources, the failure detection unit FD switches the first output value of the multiplexer MUX and the changeover switch when the control unit CTL lights the first light source LED1 when the multiplexer MUX is in the first connection state. When the control unit CTL turns on the first light source LED1 when the multiplexer MUX is in a second connection state different from the first connection state, and when the multiplexer MUX is in the first connection state When the control unit CTL turns on the second light source LED2, the third output value of the multiplexer MUX and the changeover switch are switched, and when the multiplexer MUX is in the second connection state different from the first connection state, the control unit CTL Based on the fourth output value of the multiplexer MUX when the two light source LEDs 2 are lit, To detect the failure of lexers MUX.

<Application example>
The light receiving element multiplexer 100 described above is applied to, for example, a scanning laser radar device RDR shown in FIG. The scanning laser radar device RDR is installed in a moving body such as a vehicle and detects the distance to the object. The scanning laser radar device RDR measures the distance and direction to the measurement object based on the time difference from when the laser light is emitted until the reflected light is received, and the projection direction of the emitted laser light. The scanning laser radar device RDR has a laser diode array in which a laser diode that emits light and a photodiode that receives light are arranged one-dimensionally, and a direction in which light is projected and received in a direction perpendicular to the arrangement direction. By changing in the one-dimensional direction, the surface (two-dimensional) is scanned by one scan (scan).

  As shown in FIGS. 4A to 4C, the scanning laser radar device RDR is a substantially rectangular parallelepiped having an arcuate laser radar cover 90 and components such as a laser diode and a photodiode in a front view. A laser radar housing 91 is provided. The laser radar cover 90 is made of a material that transmits laser light and its reflected light (electromagnetic wave), and projects the laser light emitted from the laser diode onto the object and receives the reflected light from the object. Make it possible.

  This figure (D) is the figure which removed only the laser radar cover 90 and the laser radar housing | casing 91, and represented only the main components contained inside. The scanning laser radar device RDR projects laser light emitted from a laser diode 20 that emits laser light, a photodiode array 30 that receives reflected light, and the laser light emitted from the laser diode 20 while being rotated by a motor 11 and reflected light. And a rotating mirror 10 that guides the light to the photodiode array 30.

  The reflected light that is reflected by the laser light emitted from the laser diode 20 and returned to the object passes through the light receiving lens 31 that forms an image on the photodiode array 30 and the light receiving mirror 32 that guides the light to the photodiode array 30. To reach. The photodiode array 30 includes the light receiving elements PD1 to PD4 described above. The photodiode array 30 is mounted on the substrate PLT, and the first light source LED1 and the second light source LED2 described above are arranged in the vicinity of both ends of the photodiode array 30 on the substrate PLT.

  During the operation of the scanning laser radar apparatus RDR, the reflected light of the laser light received by the light receiving elements PD1 to PD4 is converted into an electric signal, multiplexed by a multiplexer MUX (not shown), and an AD converter ADC (not shown). Output). When a failure of the scanning laser radar device RDR is detected, the first light source LED1 or the second light source LED2 is turned on, and the irradiation light is converted into an electric signal to be an output value of the multiplexer MUX. The output value is used for failure mode detection by the method described above.

  In addition, this invention is not limited to the illustrated Example, The implementation by the structure of the range which does not deviate from the content described in each item of a claim is possible. That is, although the present invention has been particularly illustrated and described with respect to particular embodiments, it should be understood that the present invention has been described in terms of quantity, quantity, and amount without departing from the scope and spirit of the present invention. In other detailed configurations, various modifications can be made by those skilled in the art.

100 light receiving element multiplexer PD1 to PD4 light receiving element LED1 first light source LED2 second light source CTL control unit MUX multiplexer CNL1 to CNL4 channel FD failure detection unit ADC AD converter PLT substrate RDR scanning laser radar device 10 rotating mirror 11 motor 20 laser diode 30 Photodiode array 31 Light receiving lens 32 Light receiving mirror 90 Laser radar cover 91 Laser radar housing

Claims (5)

A plurality of light receiving elements;
A first light source that irradiates light so that the received light intensity of each of the light receiving elements is different;
A control unit for controlling lighting of the first light source;
A multiplexer connected to each of the plurality of light receiving elements and switching and outputting an input signal from each of the light receiving elements;
The first output value of the multiplexer when the control unit turns on the first light source when the multiplexer is in the first connection state, and the control unit is configured to transmit the first light source when the multiplexer is in the second connection state. A failure detection unit for detecting a failure of the multiplexer based on the second output value of the multiplexer when
A light receiving element multiplexer. A second light source that emits light so that the received light intensity of each light receiving element is different;
The control unit controls lighting of the second light source,
The failure detection unit includes the first output value, the second output value, and a third output value of the multiplexer when the control unit turns on the second light source when the multiplexer is in the first connection state. And a failure of the multiplexer is detected based on a fourth output value of the multiplexer when the control unit turns on the second light source when the multiplexer is in the second connection state. 2. A multiplexer for a light receiving element according to 1. The plurality of light receiving elements are arranged in a line,
2. The light receiving element multiplexer according to claim 1, wherein the first light source is provided closest to one of the light receiving elements located at the end of the plurality of light receiving elements. The plurality of light receiving elements are arranged in a line,
The first light source is provided closest to one of the light receiving elements located at the end of the plurality of light receiving elements, and the second light source is the other located at the end of the plurality of light receiving elements. The light receiving element multiplexer according to claim 2, wherein the light receiving element multiplexer is provided closest to the light receiving element.   A scanning laser radar apparatus comprising the light-receiving element multiplexer according to claim 1.