Distance measuring device

Abstract

To provide a distance measuring device with which it is possible to perform distance measurement about a plurality of light receiving elements with high accuracy.SOLUTION: The distance measuring device is characterized by comprising: an emission unit 11 for emitting emission light; a movable mirror provided on the optical path of the emission light; a plurality of light receiving elements 21A arrayed so that return light of the emission light having been reflected by an outside object is sequentially irradiated in accordance with the movement of the movable mirror; a distance measurement unit for calculating the distance to the outside object on the basis of the light reception result of the light receiving elements; and a control unit which, when at least one of the plurality of light receiving elements has received return light, causes the output signals of other light receiving elements which are irradiated with return light after the at least one light receiving element in sequence to be received by the distance measurement unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a distance measuring device, and more particularly to a distance measuring device that measures the distance to an object by comparing the phases of a transmitted signal and a received signal.

Background Art

[0002] There is known a distance measuring device that measures the distance to an object by irradiating the object with laser light and receiving and analyzing the laser light reflected by the object (for example, Patent Document 1). As distance measuring methods of such a distance measuring device, there are a TOF (Time of Flight) method and a phase difference method. In the TOF method, the time until the transmitted signal is reflected by the object and returns is measured, and the distance is measured based on the measured time.

[0003] On the other hand, in the phase difference method, for example, laser light whose light intensity is modulated by a sine wave is irradiated onto an object, the reflected light, which is the laser light reflected by the object, is received, and its light intensity is converted into an electrical signal. Then, the phase difference between the sine wave component included in the electrical signal and the sine wave component included in the light intensity of the laser light at the time of emission is extracted, the extracted phase difference is converted into a delay time, and the distance to the object is calculated based on the delay time and the light speed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When performing distance measurement as described above for a plurality of positions on the irradiation surface of the laser beam (hereinafter referred to as a plurality of pixel regions), the distance measurement device requires a corresponding plurality of light receiving units. For example, when irradiating a laser beam toward an object, the laser beam emitted from the light source is scanned in a two-dimensional direction for light projection. The plurality of light receiving units each receive the reflected light and calculate the distance for each pixel region based on the received light signal.

[0006] In distance measurement by the phase difference method, it is necessary to continuously receive the light incident from the outside by the light receiving element for a predetermined period (for example, the light receiving period corresponding to the scanning of one frame of a two-dimensional screen). However, when calculating the distance for each pixel region using a plurality of light receiving units, the time when the reflected light actually enters the light receiving unit corresponding to each pixel region within the predetermined period is extremely short, and in most of the other periods, only the background light is received. The background light becomes a noise component for the reception of the reflected light and deteriorates the signal-to-noise ratio of the signal. And when using the received light signal based on the background light for the phase demodulation operation after receiving the light, there is a problem that the noise component due to the background light is mixed into the demodulated phase as a disturbance, deteriorating the accuracy of the distance measurement result.

[0007] As described above, when performing distance measurement for a plurality of pixel regions, deterioration of the measurement accuracy due to the reception of the background light is cited as an example of the problem.

[0008] The present invention has been made in view of the above points, and one of its purposes is to provide a distance measurement device capable of performing high-precision distance measurement for a plurality of pixel regions.

Means for Solving the Problem

[0009] The invention according to claim 1 comprises an emitting unit that emits emitted light, a movable mirror provided on the optical path of the emitted light, a plurality of light receiving elements arranged such that return light obtained by reflecting the emitted light by an external object is sequentially irradiated in accordance with the movement of the movable mirror, a distance measuring unit that calculates the distance to the external object based on the light receiving results of the light receiving elements, and a control unit that, when at least one of the plurality of light receiving elements receives the return light, places the output signals of other light receiving elements, for which the order of irradiation with the return light is later than that of the at least one light receiving element, in a state where they can be received by the distance measuring unit.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 3B

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Figure 7A

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Figure 8A

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Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description and the accompanying drawings, substantially the same or equivalent parts are denoted by the same reference numerals.

[0012] FIG. 1 is a block diagram showing a schematic configuration of a distance measuring device 100 according to Embodiment 1. The distance measuring device 100 is composed of an optical distance measuring device such as LiDAR (Light Detection and Ranging) that optically measures the distance to an object, and is a detection device that detects the position of the object.

[0013] The distance measuring device 100 emits laser light with its light intensity modulated based on a signal of a predetermined frequency toward a distance measuring area, receives the laser light reflected by an object in the distance measuring area, and measures the distance to the object based on the phase difference (phase angle) of the signal component of the predetermined frequency included in the light intensity of the laser light at the time of emission and at the time of reception.

[0014] When emitting laser light, the distance measuring device 100 of the present embodiment changes the irradiation direction of the laser light so as to two-dimensionally scan the distance measuring area. Then, the distance measuring device 100 sequentially receives the laser light reflected at a plurality of positions on the irradiation surface in response to the change in the irradiation direction, and measures the distance for each of the plurality of positions.

[0015] The distance measuring device 100 of this embodiment is configured as, for example, a distance measuring device of a separated optical system method (i.e., a non-coaxial optical system method). The distance measuring device 100 includes a light emitting unit 11, a light receiving unit 12, a scanning mirror 14, a telescopic lens 15, a condenser lens 16, a distance measuring unit 17, and a control unit 18.

[0016] The light emitting unit 11 includes a laser light source composed of a laser diode or the like, and emits pulsed laser light (i.e., pulsed light). The light emitting unit 11 emits laser light in accordance with the control by the control unit 18. In this embodiment, the light emitting unit 11 emits laser light over a predetermined distance measuring time.

[0017] The light receiving unit 12 is configured by arranging a plurality of light receiving elements composed of photodiodes or the like. The light receiving unit 12 receives light that has entered the distance measuring device 100 from the outside and has been condensed by the condenser lens 16, and converts it into an electrical signal. The plurality of light receiving elements constituting the light receiving unit 12 are arranged so as to be able to receive reflected light from a plurality of positions on the irradiation surface of the laser light. For example, in this embodiment, the plurality of light receiving elements constituting the light receiving unit 12 are arranged in a matrix, for example, to form a two-dimensional light receiving plane.

[0018] The scanning mirror 14 is composed of, for example, a MEMS (Micro Electro Mechanical Systems) mirror that swings to two-dimensionally scan laser light. The light reflecting surface of the scanning mirror 14 is provided on the optical path of the emitted light emitted from the light emitting unit 11. As the scanning mirror 14 swings, the emitted light is projected toward the distance measuring area while changing the emission direction (optical axis direction).

[0019] The telescopic lens 15 is a magnifying lens provided to expand the scanning angle of the emitted light. The telescopic lens 15 is provided on the optical path of the emitted light reflected by the scanning mirror 14 (for example, between the scanning mirror 14 and an emission port (not shown) of the distance measuring device 100).

[0020] The light-collecting lens 16 is configured as a convex lens, for example, and collects the incident light. The light-collecting lens 16 is provided at the position where the laser light (i.e., the return light) reflected by the object in the measurement region is incident. The return light collected by the light-collecting lens 16 is received by the light-receiving unit 12.

[0021] The distance measurement unit 17 calculates the distance to the object based on the light reception result of the return light by the light-receiving unit 12. Specifically, the distance measurement unit 17 detects the phase difference between the emitted light and the return light received by each of the plurality of light-receiving elements for each light-receiving element, and calculates the distance to an external object based on the detected phase difference.

[0022] The control unit 18 controls each part of the distance measurement device 100. For example, the control unit 18 controls the emission of the laser light by the emission unit 11 and the drive control of the scanning mirror 14. Further, the control unit 18 controls the distance measurement unit 17 to execute the calculation of the distance based on the phase difference method.

[0023] FIG. 2 is a block diagram showing the functional blocks of the distance measurement device 100. The distance measurement device 100 includes a reference signal generation unit 10, an emission unit 11, and a light reception processing unit 20 (light reception processing units 20A and 20B).

[0024] The reference signal generation unit 10 generates a reference signal FS used for modulating the light intensity of the laser light at the time of emission and detecting the phase difference after light reception. The reference signal FS is, for example, a sine wave signal with a predetermined frequency. Let the predetermined frequency be f 0 , then, for example, signals represented by sin(2π·f 0 ·t) and cos(2π·f 0 ·t) become the reference signal FS.

[0025] The emission unit 11 includes a laser light source 11A that emits laser light and a laser emission drive unit 11B that drives the laser light source 11A. The emission unit 11 emits the laser light with the modulated light intensity as the emitted light OL based on the reference signal FS.

[0026] The emitted light OL is reflected by the object and enters the distance measuring device 100 as the reflected light RL. Note that the reflected light RL has an irradiation surface shape corresponding to the shape of the irradiation surface of the emitted light OL. For example, when the emitted light OL is a laser beam having a spot-shaped irradiation surface, the reflected light RL also becomes light having a spot-shaped irradiation surface corresponding thereto (hereinafter referred to as spot light).

[0027] The light receiving processing units 20 (20A and 20B) are provided corresponding to one of the plurality of light receiving elements arranged in a matrix in the light receiving unit 12, respectively. In the present embodiment, the light receiving processing units 20A and 20B are light receiving processing units corresponding to two light receiving elements whose light receiving order predicted from the scanning trajectory of the emitted light is temporally before and after and whose light receiving scheduled time is close among the plurality of light receiving elements that sequentially receive the reflected light RL.

[0028] FIG. 3A is a diagram schematically showing the positional relationship between the pixel A which is the light receiving element corresponding to the light receiving processing unit 20A and the pixel B which is the light receiving element corresponding to the light receiving processing unit 20B. Since the irradiation direction of the emitted light OL changes so as to two-dimensionally scan the distance measuring region, the light receiving elements that receive the reflected light RL also transition in the two-dimensional light receiving plane accordingly.

[0029] The combination of the pixel A and the pixel B is selected according to the trajectory of the operation of the scanning mirror 14. For example, when the scanning by the scanning mirror 14 is a raster scan, since the emission direction of the emitted light OL changes in a linear trajectory, the incident direction of the reflected light RL changes in a corresponding linear trajectory, and the reflected light RL is sequentially received by the plurality of light receiving elements constituting the light receiving unit 12. Assuming that the light receiving direction of the reflected light RL is in the X direction in the figure, for example, the light receiving elements arranged along the X direction and sandwiching one light receiving element therebetween become the pixel A and the pixel B.

[0030] For example, when the emitted light OL is spot light, the reflected light RL also enters the two-dimensional light receiving plane of the light receiving unit 12 as spot light and is sequentially received along the X direction in the figure (that is, the direction of the arrow).

[0031] Referring back to FIG. 2, the light receiving processing unit 20A and the light receiving processing unit 20B each include a light receiving unit 12 (12A and 12B), a gate switch 22, a phase difference detection unit 23, and a control signal generation unit 24.

[0032] The light receiving unit 12 (12A and 12B) receives the reflected light RL, which is the laser light reflected by an object within a predetermined region, and includes a light receiving element 21A that converts the light intensity of the received reflected light RL into an electrical signal, and a light receiving signal detection unit 21B that detects a light receiving signal RS from the electrical signal converted by the light receiving element 21A. The light receiving element 21A is composed of a photodetector such as a photodiode, for example, and converts the light intensity of the received reflected light RL into an electrical signal. For example, the light receiving element 21A is composed of an APD (Avalanche Photodiode).

[0033] The gate switch 22 is a connection switching unit that switches between a state in which it is electrically connected (i.e., a state in which the phase difference detection unit can receive the light receiving signal) and a state in which it is not electrically connected (i.e., a state in which the phase difference detection unit cannot receive the light receiving signal) between the light receiving signal detection unit 21B and the phase difference detection unit 23. When the light receiving signal detection unit 21B and the phase difference detection unit 23 are in an electrically connected state, the light receiving signal RS is supplied from the light receiving signal detection unit 21B to the phase difference detection unit 23. When the light receiving signal detection unit 21B and the phase difference detection unit 23 are in a state where they are not electrically connected, the supply of the light receiving signal RS from the light receiving signal detection unit 21B to the phase difference detection unit 23 is stopped.

[0034] The gate switch 22 performs the above switching in response to the supply of a gate control signal GCS from the control signal generation unit 24 of the light receiving unit whose light receiving order of the reflected light RL is in front. For example, in this embodiment, the gate switch 22 of the light receiving processing unit 20A switches between electrical connection and non-connection between the light receiving signal detection unit 21B and the phase difference detection unit 23 in response to the gate control signal GCS supplied from the control signal generation unit 24 of the light receiving processing unit 20B.

[0035] The phase difference detection unit 23 detects the phase difference PD between the emitted light OL and the reflected light RL based on the received light signal RS detected by the received light signal detection unit 21B and the reference signal FS supplied from the reference signal generation unit 10. The phase difference detection unit 23 supplies the detected phase difference PD to a distance calculation unit (not shown). The distance calculation unit calculates the distance to the object for each light receiving element (i.e., each pixel region) based on the supplied phase difference PD. Note that the phase difference detection unit 23 for each light receiving element constitutes the distance measurement unit 17 shown in FIG. 1 (not shown in FIG. 2) together with a distance calculation unit not shown.

[0036] The control signal generation unit 24 generates a gate control signal GCS in response to the supply of the received light signal RS from the received light signal detection unit 21B, and supplies it to the gate switch 22 of the light receiving processing unit whose light reception order of the reflected light RL is later (i.e., the light receiving processing unit whose reception of the reflected light RL is scheduled to be later in time). The control signal generation unit 24 is connected so as to be able to supply a signal via an electrical connection line or the like to the gate switch 22 of the light receiving processing unit which is the supply destination of the gate control signal GCS. For example, the control signal generation unit 24 of the light receiving processing unit 20B is pre-connected via a connection line to the gate switch 22 of the light receiving processing unit 20A.

[0037] The control signal generation unit 24 generates a gate control signal GCS having a binary signal level that becomes the "H" level for a predetermined period and becomes the "L" level in other periods. For example, the control signal generation unit 24 of the light receiving processing unit 20B generates a gate control signal GCS that becomes the "H" level only during the period when the signal level of the received light signal RS supplied from the received light signal detection unit 21B exceeds a predetermined threshold value, and becomes the "L" level in other periods, and supplies it to the gate switch 22 of the light receiving processing unit 20A.

[0038] FIG. 4 is a block diagram of a distance measuring device 100 including functional blocks constituting a control signal generation unit 24. Here, among the light receiving processing units 20A and 20B having a common configuration, only the light receiving processing unit 20B is shown in terms of the configuration of its functional blocks, and the illustration of the light receiving processing unit 20A is omitted. Also, here, when the reference signal generation unit 10 supplies the reference signals FS as the frequency signal FS1 = cos(2π·f 0 ·t) and the frequency signal FS2 = sin(2π·f 0 ·t), it will be described.

[0039] The control signal generation unit 24 includes integration units 25A and 25B, LPFs (Low Pass Filters) 26A and 26B, comparators 27A and 27B, and a pulse width adjustment unit 28.

[0040] The integration unit 25A performs an operation of multiplying the received light signal RS by the frequency signal FS1. Similarly, the integration unit 25B performs an operation of multiplying the received light signal RS by the frequency signal FS2.

[0041] The LPF 26A blocks high-frequency components from the operation result of multiplying the received light signal RS by the frequency signal FS1 and extracts the DC component. Thereby, the cosine component CS of the received light signal RS is detected.

[0042] The LPF 26B blocks high-frequency components from the operation result of multiplying the received light signal RS by the frequency signal FS2 and extracts the DC component. Thereby, the sine component SS of the received light signal RS is detected.

[0043] FIG. 5 is a diagram schematically showing the processes performed by the respective functional blocks of the control signal generation unit 24. By passing through the operations by the integration units 25A and 25B and the LPFs 26A and 26B, the envelope waveform of the received light signal RS at pixel B is detected.

[0044] Referring back to FIG. 4, comparator 27A compares the cosine component CS of the received signal RS with a predetermined threshold value and outputs the comparison result as a binary signal. Similarly, comparator 27B compares the sine component SS of the received signal RS with a predetermined threshold value and outputs the comparison result as a binary signal. As a result, as shown in FIG. 5, a binary signal is output as the comparator output such that the logical value is "1" (i.e., "H" level) during the period when the signal level of the envelope waveform of the received optical signal RS is equal to or higher than the threshold value TH, and the logical value is "0" (i.e., "L" level) during the period when it is less than the threshold value TH. The period during which this comparator output is at the "H" level corresponds to the period during which the reflected light RL is received at pixel B.

[0045] Pulse width adjustment unit 28 adjusts the pulse width for generating the gate control signal GCS based on the comparator outputs output from comparators 27A and 27B. For example, pulse width adjustment unit 28 adjusts the pulse width using the scanning speed of the emitted light OL calculated based on the operating speed of scanning mirror 14. As a result, as shown in FIG. 5, a gate control signal GCS having a pulse width corresponding to the signal waveform predicted as the received signal RS at pixel A is generated.

[0046] Referring back to FIG. 2, the gate control signal GCS emitted from the control signal generation unit 24 of the light reception processing unit 20B is supplied to the gate switch 23 of the light reception processing unit 20A. The gate switch 23 of the light reception processing unit 20A switches the electrical connection and disconnection between the received optical signal 21B and the phase difference detection unit 22 according to the signal level of the gate control signal GCS. For example, the gate switch 23 connects between the received optical signal detection unit 21B and the phase difference detection unit 22 during the period when the gate control signal GCS is at the "H" level, and disconnects between the received optical signal detection unit 21B and the phase difference detection unit 22 during the period when the gate control signal GCS is at the "L" level.

[0047] As a result, in the light receiving processing unit 20A, the light receiving signal RS is supplied from the light receiving signal detection unit 21B to the phase difference detection unit 22 during the period when the reception of the reflected light RL at pixel A is assumed, and the supply of the light receiving signal RS is stopped during other periods. Therefore, the phase difference detection unit 22 does not detect the phase difference during the period when only the background light is assumed to be incident, and detects the phase difference during the period when the reception of the reflected light RL is assumed.

[0048] FIG. 3B is a diagram schematically showing that the detection of the light receiving signal RS in the light receiving processing unit 20B corresponding to pixel B is used for controlling the supply of the light receiving signal RS to the phase difference detection unit 22 in the light receiving processing unit 20A corresponding to pixel A. Thus, based on the detection of the light receiving signal RS in the light receiving processing unit 20B, information on the light reception timing of the reflected light RL in pixel B is acquired, and based on the information on the light reception timing, the supply of the light receiving signal RS to the phase difference detection unit 22 of the light receiving processing unit 20A is controlled.

[0049] Next, the operation of the distance measuring device 100 of the present embodiment will be described with reference to the flowchart of FIG. 6.

[0050] First, the control unit 18 controls the emitting unit 11 to emit the emitted light OL. The emitted light OL is reflected by the scanning mirror 14, passes through the telephoto lens 15, and is projected outside the distance measuring device 100. At this time, by controlling and swinging the scanning mirror 14 by the control unit 18, the emitted light OL is projected while changing the emission direction so as to scan (STEP101).

[0051] The emitted light OL reflected by an object located outside the distance measuring device 100 enters the distance measuring device 100 as the reflected light RL, is condensed by the condenser lens 16, and enters the light receiving unit 12. At this time, as the emission direction of the emitted light OL changes due to the swing of the scanning mirror 14, the incident direction of the reflected light RL changes, so that the reflected light RL is sequentially received by a plurality of light receiving elements constituting the light receiving unit 12.

[0052] The light reception signal detection unit 21B of the light reception processing unit 20B corresponding to one pixel (for example, pixel B) detects a light reception signal RS from the reflected light RL received by the light receiving element 21A (STEP102).

[0053] The control signal generation unit 24 of the light reception processing unit 20B corresponding to the one pixel generates a gate control signal GCS based on the detection of the light reception signal RS by the light reception signal detection unit 21B, and supplies it to the gate switch 22 of the light reception processing unit 20A corresponding to another pixel (for example, pixel A). The gate switch 22 electrically connects between the light reception signal detection unit 21B and the phase difference detection unit 23 based on the supplied gate control signal GCS (STEP103).

[0054] The light reception signal detection unit 21B corresponding to the other pixel supplies the light reception signal RS to the phase difference detection unit 23 (STEP104). The phase difference detection unit 23 performs phase difference detection for pixel A based on the supplied light reception signal RS. The control unit 18 determines whether or not a predetermined ranging time has elapsed (STEP105). If it is determined that the predetermined ranging time has not elapsed (STEP105: No), while changing the target pixel according to the scanning trajectory (STEP106), the processes of STEP102 to STEP104 are repeatedly executed.

[0055] On the other hand, if it is determined that the predetermined ranging time has elapsed (STEP105: No), for all pixels, the state where the electrical connection between the corresponding light reception signal detection unit 21B and the phase difference detection unit 23 is non-connected (that is, the state where the phase difference detection unit 23 can receive the light reception signal RS) is set (STEP107), and the process is terminated.

[0056] While the above processes are being executed, each phase difference detection unit 23 that receives the supply of the light reception signal RS performs phase difference detection, and the ranging unit 17 calculates the distance to the object based on the detected phase difference.

[0057] In addition, when the light-receiving element corresponding to one pixel is the light-receiving element that first receives the reflected light RL in the light-receiving unit 12, although the first phase difference detection for the one pixel cannot be performed, for the light-receiving element that receives the reflected light RL at a subsequent timing, the phase difference can be detected.

[0058] As described above, in the distance measuring device 100 of the present embodiment, the light reception signal RS is supplied to the phase difference detection unit 22 only during the period when the reflected light RL is assumed to enter each light-receiving element. For this reason, the phase difference detection unit 22 corresponding to each light-receiving element does not perform phase difference detection at the timing when only the background light enters, and can perform phase difference detection at the timing when the reflected light RL is received. Therefore, according to the distance measuring device 100 of the present embodiment, it is possible to detect the phase difference while suppressing the influence of noise caused by the background light or the like.

[0059] Note that the present invention is not limited to the above-described embodiment. For example, in the above embodiment, the case where the emitted laser light is spot light has been described as an example. However, a laser light having an irradiation surface in a line shape (that is, a line beam) may be used as the emitted light. For example, the laser light source 11A can be configured by a multi-emitter in which a plurality of emitters are arranged in a line, so that the emitted light OL can be a line beam. When the emitted light OL is a line beam, the shape of the irradiation surface of the reflected light RL is also in a line shape.

[0060] At this time, it is preferable that the plurality of light-receiving elements constituting the light-receiving unit 12 are arranged in a higher dimension than the arrangement of the emitters. For example, when using a line beam emitted from a plurality of emitters arranged in a line as the emitted light, the plurality of light-receiving elements may be arranged in a matrix of a plurality of rows and a plurality of columns. Further, for example, when using a laser light having an irradiation surface in a spot shape emitted from one emitter (single emitter) as the emitted light, it may be arranged in a matrix of a plurality of rows and a plurality of columns, or the row or column direction may be arranged in a single straight line shape (that is, the shape of a line sensor).

[0061] Figures 7A and 7B show the arrangements of pixel B and pixel A when the emitted light OL is a line beam. As shown in Figure 7A, even when the emitted light OL is a line beam and the irradiation surface of the reflected light RL is in a line shape, the light-receiving elements (i.e., pixels) arranged at corresponding positions along the light-receiving direction (the X direction in the figure) become pixel B and pixel A. Also, as shown in Figure 7B, light-receiving elements having an oblique positional relationship with respect to the X direction may be used as pixel B and pixel A, instead of being strictly at positions along the light-receiving direction (the X direction in the figure).

[0062] In the above embodiment, the case where the scanning of the emitted light OL by the scanning mirror 14 is a raster scan and the light reception of the reflected light RL by the light-receiving unit 12 is performed along a linear trajectory has been described as an example. However, the present invention can also be applied when the scanning mirror 14 projects the emitted light OL by a Lissajous scan. In that case, since the light reception of the reflected light RL is performed along a trajectory corresponding to the Lissajous scan trajectory, it is possible to specify in advance the light-receiving elements that have the relationship of the light-receiving element A and the light-receiving element B in the above embodiment according to the trajectory.

[0063] In the above embodiment, the case where the control signal generation unit 24 corresponding to the light-receiving element B and the gate switch 22 corresponding to the light-receiving element A are connected (i.e., hard-wired) so that signals can be supplied by a connection line or the like in advance according to the trajectory of the scanning mirror 14 has been described as an example. However, differently from this, the configuration may be such that the control unit 18 shown in Figure 1 controls (i.e., soft-controls) the supply destination of the gate control signal GCS generated by the control signal generation unit 24 of each light-receiving processing unit. For example, a storage unit (not shown) provided in the distance measuring device 100 stores a table in which the light-receiving processing unit that is the supply source of the gate control signal GCS and the light-receiving processing unit that is the supply destination are associated with each other for each trajectory of the scanning mirror 14, and the control unit 18 can control the supply of the gate control signal GCS by appropriately reading and referring to this table.

[0064] In the above-described embodiment, an example in which the gate switch 22 and the phase difference detection unit 23 are provided for each light receiving element (i.e., each light receiving processing unit) has been described. However, these may be provided in common for a plurality of light receiving elements.

[0065] In the above-described embodiment, an example in which the control of the supply of the light reception signal RS to the phase difference detection unit 22 in the light reception processing unit 20A corresponding to one light receiving element (pixel A) is performed based on the timing of the reception of the reflected light RL of another light receiving element (pixel B) has been described. However, the present invention is not limited to this, and the control of the supply of the light reception signal RS to the phase difference detection unit 22 in the light reception unit corresponding to one light receiving element may be configured to be performed based on the reception of the reflected light RL by two or more other light receiving elements.

[0066] FIGS. 8A and 8B are diagrams schematically showing a state in which the control of the supply of the light reception signal RS to the phase difference detection unit is performed based on the reception of the reflected light RL by two light receiving elements. As shown in FIG. 8A, based on the reception results of the reflected light RL in the pixels B and C, which are two light receiving elements continuously arranged along the light reception direction (the X direction in the figure), the supply of the light reception signal RS to the phase difference detection unit 22 in the light reception processing unit 20A corresponding to the pixel A may be controlled. Further, according to the change in the position at which the reflected light RL is received in the two-dimensional light reception plane (i.e., the light reception direction), for example, as shown in FIG. 8B, based on the reception results of the reflected light RL in the light receiving elements (for example, the pixels B and C shown in the figure) continuously arranged in the diagonal direction, the supply of the light reception signal RS to the phase difference detection unit 22 in the light reception processing unit 20A corresponding to the pixel A may be controlled.

[0067] In the above-described embodiment, an example in which the control of the supply of the light reception signal RS to the phase difference detection unit 22 in the light reception processing unit (20A) corresponding to a certain light receiving element (pixel A) is performed based on the timing of the reception of the reflected light RL by another light receiving element (pixel B) has been described. However, the mode of controlling the supply of the light reception signal RS to the phase difference detection unit 22 is not limited to this.

[0068] FIG. 9 is a block diagram showing a configuration in which the gate switch 23 receives a gate control signal GCS from outside the light receiving processing unit 20 and switches between connection and disconnection of the connection between the light reception signal detection unit 21B and the phase difference detection unit 22. For example, the distance measuring device 100 may be configured to generate a gate control signal GCS based on distance information or the like to an object preliminarily acquired by operations of the scanning mirror 14, image processing using a camera, or the like, and supply the generated gate control signal to the gate switch 23.

[0069] FIG. 10 is a block diagram showing a configuration in the case where the gate switch 23 is controlled based on the reception result of the reflected light RL in the light receiving element itself instead of the reception result of the reflected light RL in other light receiving elements. The emission signal detection unit 24 supplies the gate control signal GCS not to the gate switches of other light receiving units but to the gate switch 23 in the same light receiving processing unit 20. The gate switch 23 switches between electrical connection and disconnection between the light reception signal detection unit 21B and the phase difference detection unit 22 based on the supplied gate control signal GCS. According to such a configuration, since the control of the gate switch 23 is performed after the light reception signal detection unit 21B detects the light reception signal RS, although there is a slight time lag until the supply of the light reception signal RS to the phase difference detection unit 22 starts, it is possible to sufficiently perform phase difference detection within a range necessary for distance measurement while suppressing the influence of noise caused by background light or the like.

[0070] Also, the series of processes described in the above embodiment can be performed by computer processing according to a program stored in a recording medium such as a ROM.

Explanation of Reference Numerals

[0071] 100 Distance measuring device 10 Reference signal generation unit 11 Emission unit 11A Laser light source 11B Laser emission driving unit 12 Light receiving unit 14 Scanning mirror 15 Telescope lens 16 Condensing lens 17 Distance measurement unit 20 Light reception processing unit 21A Light receiving element 21B Light reception signal detection unit 22 Phase difference detection unit 23 Gate switch 24 Emission signal detection unit 25A Integration unit 25B Integration unit 26A LPF 26B LPF 27A Comparator 27B Comparator 28 Pulse width adjustment unit

Claims

[Claim 1] An emission section that emits emission light; a movable mirror provided on an optical path of the emitted light; a plurality of light receiving elements arranged so that return light, which is the emitted light reflected by an external object, is sequentially irradiated in accordance with the movement of the movable mirror; a distance measuring unit that calculates a distance to the external object based on a light receiving result of the light receiving element; a control unit that, when at least one of the plurality of light receiving elements receives the return light, causes the distance measuring unit to be able to receive output signals of other light receiving elements that are irradiated with the return light after the at least one light receiving element; A distance measuring device comprising:

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