JP2020201099A - Distance measuring device, distance measuring system, and distance measuring method - Google Patents

Abstract

To scan a target space by measurement light.SOLUTION: A distance measuring device 1 comprises a light emission control unit 11, a light reception control unit 12, a vibration control unit 13, and a distance acquisition unit 14. The light emission control unit 11 controls timing at which measurement light W1 is outputted by a light emission unit 2 that outputs the measurement light W1 toward a target space S1. The light reception control unit 12 controls the operation of a light reception unit 3. The light reception unit 3 has a plurality of pixel cells 30 for receiving the measurement light W1 reflected by an object 200 existing in the target space S1. The vibration control unit 13 controls the operation of a vibration addition unit 5. The vibration addition unit 5 vibrates an optical element 4. The optical element 4 is arranged on the optical path of the measurement light W1 from the light emission unit 2 to the object 200. The distance acquisition unit 14 finds the distance to the object 200 on the basis of a time from when the light emission unit 2 outputs the measurement light W1 to when the light reception unit 3 receives the measurement light W1.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a distance measuring device, a distance measuring system, and a distance measuring method, and more specifically, to a distance measuring device, a distance measuring system, and a distance measuring method for obtaining a distance to an object.

Patent Document 1 discloses an object detection device.

The object detection device includes an irradiation means, a light receiving means, and a detection means. The irradiation means scans the slit light along a direction intersecting the longitudinal direction of the slit light within the object detection range. In the light receiving means, the light receiving surface on which the slit light reflected by the object existing in the object detection range is irradiated is along the direction intersecting the moving direction of the slit light irradiation position accompanying the scanning of the slit light by the irradiation means. A plurality of light receiving elements are arranged. The detecting means detects the position of the object along the longitudinal direction of the slit light based on which light receiving element of the light receiving means receives the slit light reflected by the object.

The irradiation means includes a light source unit including a laser light source made of a laser diode and a beam shaper that shapes the laser light emitted from the laser light source into slit-shaped parallel light. The light source unit intermittently emits a slit-shaped laser beam. The irradiation means includes a galvano mirror. The galvano mirror includes a motor and a flat mirror whose back surface is attached to the side surface of the rotation shaft of the motor. The galvano mirror drive circuit drives the motor so that the rotation axis of the motor reciprocates within a certain angle range, so that the plane mirror attached to the rotation axis of the motor reciprocates within a certain angle range. Move it. As a result, the slit-shaped laser light reflected by the galvano mirror (plane mirror) is approximately horizontally oriented toward the front side of the object detection device via the projection lens arranged on the laser light emitting side of the galvano mirror. Scan along.

JP-A-2009-156810

In the field of a distance measuring device such as the object detecting device described in Patent Document 1, a new method of scanning a target space to be measured for distance measurement with measurement light is desired.

It is an object of the present disclosure to provide a distance measuring device, a distance measuring system, and a distance measuring method capable of providing a new method of scanning a target space with measurement light.

The distance measuring device according to one aspect of the present disclosure includes a light emitting control unit, a light receiving control unit, a vibration control unit, and a distance acquisition unit. The light emission control unit controls the timing at which the measurement light is output from the light emitting unit that outputs the measurement light toward the target space. The light receiving control unit controls the operation of the light receiving unit having a plurality of pixel cells for receiving the measurement light reflected by the object existing in the target space. The vibration control unit controls the operation of the vibration applying unit that vibrates the optical element arranged on the optical path of the measurement light from the light emitting unit to the object. The distance acquisition unit obtains the distance to the object based on the time from when the light emitting unit outputs the measurement light to when the light receiving unit receives the measurement light.

The distance measuring system according to one aspect of the present disclosure includes the distance measuring device, the light emitting unit, the light receiving unit, the optical element, and the vibration applying unit.

The distance measuring method according to one aspect of the present disclosure includes a light emission control step, a light reception control step, a vibration control step, and a distance acquisition step. The light emission control step includes controlling the timing of outputting the measurement light from the light emitting unit that outputs the measurement light. The light receiving control step includes controlling the operation of a light receiving unit having a plurality of pixel cells for receiving the measurement light reflected by the object. The vibration control step includes controlling the operation of a vibration applying unit that vibrates an optical element arranged on an optical path of the measurement light from the light emitting unit to the object. The distance acquisition step includes obtaining the distance to the object based on the time from when the light emitting unit outputs the measurement light to when the light receiving unit receives the measurement light.

The present disclosure can provide a novel method of scanning a target space with measurement light.

FIG. 1 is an explanatory diagram showing a usage state of the distance measurement system of one embodiment. FIG. 2 is a block diagram of the same distance measuring system. FIG. 3 is an explanatory diagram showing an outline of a vibration applying portion included in the same distance measuring system. FIG. 4 is an explanatory diagram of the measurement light output from the same distance measurement system. FIG. 5 is an explanatory diagram showing pixel cells included in the same distance measurement system. FIG. 6 is an operation explanatory diagram in the same distance measuring system. FIG. 7 is a time chart diagram for explaining the operation of the same distance measuring system. FIG. 8 is an explanatory view showing a light receiving portion of a distance measuring system of a modified example.

Hereinafter, the distance measurement system 100 according to the embodiment of the present disclosure will be described with reference to the drawings. However, the following embodiments are only part of the various embodiments of the present disclosure. The following embodiments can be variously modified according to the design and the like as long as the object of the present disclosure can be achieved.

(1) Outline of the Embodiment (1.1) The distance measuring system 100 of the present embodiment has a distance measuring device 1, a light emitting unit 2, a light receiving unit 3, and an optical element 4 as shown in FIGS. 1 and 2. And a vibration imparting unit 5. The distance measuring system 100 measures the distance to the object 200 by using the TOF method (TOF: Time Of Flight). The distance measurement system 100 can be used, for example, in an object recognition system mounted on an automobile to detect an obstacle, a surveillance camera for detecting an object (person), a security camera, or the like.

The light emitting unit 2 outputs the measurement light W1 toward the target space S1. The light receiving unit 3 has a plurality of pixel cells 30. The pixel cell 30 receives the measurement light W1 reflected by the object 200 existing in the target space S1. The optical element 4 is arranged on the optical path LP1 of the measurement light W1 from the light emitting unit 2 to the object 200. The vibration applying unit 5 vibrates the optical element 4.

As shown in FIG. 2, the distance measuring device 1 includes a measurement control unit 10 and a distance acquisition unit 14. The measurement control unit 10 includes a light emission control unit 11, a light reception control unit 12, and a vibration control unit 13.

The light emitting control unit 11 is connected to the light emitting unit 2. The light emission control unit 11 controls the light emission of the light emission unit 2. The light emission control unit 11 controls the timing at which the measurement light W1 is output from the light emission control unit 2. The light receiving control unit 12 is connected to the light receiving unit 3. The light receiving control unit 12 controls the light receiving of the light receiving unit 3. The vibration control unit 13 is connected to the vibration applying unit 5. The vibration control unit 13 controls the vibration of the vibration applying unit 5. The distance acquisition unit 14 obtains the distance to the object 200 based on the time from when the light emitting unit 2 outputs the measurement light W1 until the light receiving unit 3 receives the measurement light W1.

According to the distance measuring device 1 and the distance measuring system 100 of the present embodiment, the optical element 4 arranged on the optical path LP1 of the measurement light W1 is vibrated by the vibration imparting unit 5, so that the measurement light W1 is transferred to the optical path. It vibrates in the surface P100 intersecting with LP1. Therefore, the emission direction of the measurement light W1 from the distance measurement system 100 changes. That is, according to the distance measuring device 1 and the distance measuring system 100 of the present embodiment, the target space S1 can be scanned by the measuring light W1 by vibrating the optical element 4. In FIG. 1, the direction of the measurement light W1 output from the light emitting unit 2 is indicated by the solid arrow A1, and the vibration direction of the measurement light W1 is indicated by the solid arrows A2 and A3.

(1.2) Details The distance measuring device 1 of the present embodiment and the distance measuring system 100 including the distance measuring device 1 will be described in more detail with reference to FIGS. 1 to 7.

(1.2.1) Configuration As shown in FIG. 2, the distance measuring system 100 includes a distance measuring device 1, a light emitting unit 2, a light receiving unit 3, an optical element 4, and a vibration applying unit 5. ing.

The light emitting unit 2 includes a light source 21, and is configured to output pulse-shaped measurement light W1 (pulse light) from the light source 21 toward the target space S1. It is preferable that the measurement light W1 is monochromatic light, has a relatively short pulse width, and has a relatively high peak intensity. Further, in consideration of the use of the distance measurement system 100 in urban areas, the wavelength of the measurement light W1 is in the near-infrared wavelength region where human visual sensitivity is low and it is not easily affected by ambient light such as sunlight. It is preferable to have. In the present embodiment, the light source 21 is composed of, for example, a laser diode, and outputs a pulse laser. The intensity of the pulsed laser output by the light source 21 meets the class 1 or class 2 standard of the laser product safety standard (JIS C 6802) in Japan. In FIG. 2, the measurement light W1 is conceptually described by a virtual line.

The light emitting unit 2 is controlled by the measurement control unit 10 (light emission control unit 11) of the distance measuring device 1.

The light receiving unit 3 includes an image sensor 31 having a plurality of pixel cells 30 (a plurality of light receiving elements). The light receiving unit 3 is configured to receive the measurement light W1 which is the reflected light output from the light emitting unit 2 and reflected by the object 200 existing in the target space S1.

The plurality of pixel cells 30 are arranged in a two-dimensional array. The plurality of pixel cells 30 are arranged in a matrix here. However, the present invention is not limited to this, and the plurality of pixel cells 30 may be arranged in another array such as a honeycomb array.

The pixel cell 30 can receive light only during exposure. The pixel cell 30 includes a photodiode here. The pixel cell 30 converts the received measurement light W1 into an electric signal (hereinafter, also referred to as “pixel signal”).

The light receiving unit 3 further includes a pixel output unit 32 that outputs a pixel signal to the distance measuring device 1. In the present embodiment, since the light receiving unit 3 has a plurality of pixel cells 30, the pixel output unit 32 can output a plurality of pixel signals corresponding to the plurality of pixel cells 30. The signal level of the pixel signal is a value corresponding to the amount of light received by the measurement light W1 received by the pixel cell 30. Hereinafter, the signal level of the pixel signal is also referred to as a “pixel value”.

The pixel cell 30 may include an avalanche photodiode (APD). When the pixel cell 30 includes an avalanche photodiode, the signal level of the pixel signal may correspond to the number of pulses (photons) of the light received by the pixel cell 30.

The light receiving unit 3 is light receiving controlled by the measurement control unit 10 (light receiving control unit 12) of the distance measuring device 1.

The light receiving unit 3 may further include an optical system such as a lens. Further, the light receiving unit 3 may further include a filter that blocks or transmits light of a specific frequency. In this case, the distance measurement system 100 can acquire information on the frequency of light.

The optical element 4 is a diffraction grating 41 here. Here, the optical element 4 is a transmission type optical element that transmits the measurement light W1. That is, the optical element 4 is a transmission type diffraction grating 41.

As shown in FIG. 1, the diffraction grating 41 is arranged on the optical path LP1 of the measurement light W1 output from the light emitting unit 2. The diffraction grating 41 is arranged on the optical path LP1 of the measurement light W1 from the light emitting unit 2 to the object 200 (that is, on the optical path LP1 of the measurement light W1 before being output from the light emitting unit 2 and hitting the object 200). There is.

The diffraction grating 41 is a two-dimensional diffraction grating here. The diffraction grating 41 is formed by forming recesses at equidistant matrix-shaped lattice points on one surface of a transparent rectangular plate-shaped substrate such as a glass substrate. The diffraction grating 41 disperses (diffracts) the measurement light W1 incident on the incident surface from an exit surface opposite to the incident surface in a plurality of specific angular directions and emits the light W1. The direction of the measurement light W1 (diffraction light) emitted from the diffraction grating 41 is determined by the lattice spacing of the diffraction grating 41, the angle of incidence of the incident light on the diffraction grating 41, the wavelength of the measurement light W1 and the like.

The vibration imparting unit 5 vibrates the diffraction grating 41 (optical element 4). The vibration imparting unit 5 vibrates the diffraction grating 41 in a plane intersecting with the optical path LP1. Here, the vibration imparting unit 5 vibrates the diffraction grating 41 in the plane intersecting the optical path LP1 along two directions (vertical direction and horizontal direction in FIG. 4) intersecting each other.

As shown in FIG. 3, the vibration applying portion 5 includes at least one (four in this case) elastic portion 51 and at least one (two in this case) actuator 52.

The elastic portion 51 includes, for example, a coiled spring. One end of the spring is fixed to the side surface of the substrate of the diffraction grating 41 (optical element 4), and the other end is fixed to the wall surface of the housing accommodating the diffraction grating 41. The four springs are fixed to each of the four sides of the diffraction grating 41. The diffraction grating 41 is held by four springs so that it can vibrate in a plane along the expansion / contraction direction of the spring (in a plane parallel to the paper surface of FIG. 3).

The actuator 52 applies a force in the direction along the vibration direction of the elastic portion 51 to the diffraction grating 41. The two actuators 52 apply a force to two adjacent side surfaces of the four side surfaces of the diffraction grating 41, respectively. As a result, the diffraction grating 41 vibrates.

The actuator 52 is, for example, a piezo type actuator that converts an applied voltage into a force. However, the present invention is not limited to this, and the actuator 52 may be an electrostatic actuator, an electromagnetic induction type actuator such as a voice coil, or the like.

The vibration applying unit 5 (actuator 52) is vibration-controlled by the measurement control unit 10 (vibration control unit 13) of the distance measuring device 1.

As shown in FIG. 2, the distance measuring device 1 includes a measurement control unit 10 and a distance acquisition unit 14. The distance measuring device 1 is composed of, for example, a microcomputer having a processor and a memory. That is, the distance measuring device 1 is realized by a computer system having a processor and a memory. Then, the distance measuring device 1 functions as a measurement control unit 10 and a distance acquisition unit 14 when the processor executes an appropriate program. The program may be pre-recorded in a memory, may be recorded through a telecommunication line such as the Internet, or may be recorded and provided on a non-temporary recording medium such as a memory card.

The measurement control unit 10 includes a light emission control unit 11, a light reception control unit 12, and a vibration control unit 13.

The light emission control unit 11 controls the timing at which the measurement light W1 is output from the light source 21 (light emission timing), the pulse width of the measurement light W1 output from the light source 21 (light emission time), and the like in the light emission control of the light emission unit 2.

The light receiving control unit 12 controls the timing (exposure timing), the exposure width (exposure time), and the like of exposing the plurality of pixel cells 30 in the light receiving control of the light receiving unit 3.

The vibration control unit 13 controls the timing, frequency (cycle), and the like of vibrating the actuator 52 in the vibration control of the vibration applying unit 5.

The vibration control unit 13 vibrates the diffraction grating 41 in the plane by the vibration imparting unit 5, so that the measurement light W1 (diffraction light) emitted from the diffraction grating 41 is vibrated in the surface P100 intersecting the optical path LP1. .. In other words, the vibration control unit 13 vibrates the optical element 4 (diffraction grating 41) by the vibration imparting unit 5 so that the measurement light W1 vibrates two-dimensionally in the surface P100 intersecting the optical path LP1.

In the present embodiment, the vibration control unit 13 uses the vibration grating 5 to draw a substantially ∞ character in the surface P100 where the locus of the measurement light W1 emitted from the diffraction grating 41 intersects the optical path LP1. Vibrate 41. For example, when focusing on the 0th-order light of the measurement light W1 dispersed (diffracted) by the diffraction grating 41, the vibration control unit 13 has a trajectory of the 0th-order light of substantially ∞ in the surface P100 intersecting the optical path LP1. The diffraction grating 41 is vibrated by the vibration imparting unit 5 so as to draw a character (see FIG. 4). For example, the vibration control unit 13 may control the vibration applying unit 5 so that the diffraction grating 41 vibrates once in the horizontal direction and vibrates twice in the vertical direction. In FIG. 4, the locus of the measurement light W1 is indicated by a solid arrow.

The frequency (vibration frequency) at which the vibration imparting unit 5 vibrates the diffraction grating 41 is, for example, about several hundred Hz to several kHz. The vibration frequency here means the frequency of the two-dimensional vibration of the diffraction grating 41 (here, it is equal to the frequency of the vibration in the horizontal direction of the diffraction grating 41 and half of the frequency of the vibration in the vertical direction). .. Here, while the diffraction grating 41 vibrates once and two-dimensionally, the measurement light W1 moves in the order of points P1 → P2 → P3 → P4 → P5 → P6 → P7 → P8 → P1 (see FIG. 4). ).

In the distance measurement system 100 of the present embodiment, the measurement light W1 is pulse light. Further, the distance measuring device 1 has a light emitting unit so that the light emitting period of the measurement light W1 (pulse light) is shorter than the vibration period (the reciprocal of the above vibration frequency) in which the vibration applying unit 5 vibrates the optical element 4. 2 and the vibration applying unit 5 are controlled. Therefore, the measurement light W1 emits light discretely at a plurality of points in the character ∞. For example, when the light emitting control unit 11 controls the light emitting unit 2 so that the measurement light W1 emits light eight times (outputs pulsed light) during one cycle of the two-dimensional vibration of the diffraction grating 41, the measurement light W1 is irradiated for the light emission time in order at the positions corresponding to the points P1 to P8 in FIG.

By vibrating the diffraction grating 41 in this way, the measurement light W1 emitted from the diffraction grating 41 can be vibrated in the surface P100 intersecting the optical path LP1. That is, by vibrating the diffraction grating 41, it is possible to change the emission direction of the measurement light W1 from the distance measurement system 100. By changing the emission direction of the measurement light W1, it is possible to measure the distance from the distance measurement system 100 to the object 200 in different directions (directions corresponding to points P1 to P8) in the target space S1. Become.

When the emission direction of the measurement light W1 changes, the pixel cell 30 capable of receiving the reflected light among the plurality of pixel cells 30 of the light receiving unit 3 also changes. That is, the measurement light W1 having different emission directions is received by different pixel cells 30 among the plurality of pixel cells 30. For example, the measurement light W1 passing through the point P1 on the surface P100 intersecting the optical path LP1 can be received by the two pixel cells 301 shown in FIG. Similarly, the measurement light W1 passing through the point P2 is by the pixel cell 302, the measurement light W1 passing through the point P3 is by the pixel cell 303, the measurement light W1 passing through the point P4 is by the pixel cell 304, and the measurement light W1 passing through the point P5 is. The pixel cell 301 can receive the measurement light W1 passing through the point P6 by the pixel cell 306, the measurement light W1 passing through the point P7 by the pixel cell 307, and the measurement light W1 passing through the point P8 by the pixel cell 308. In FIG. 5, pixel cells 301 to 304 and 306 to 308 are shown by dot hatching, respectively.

The distance acquisition unit 14 acquires information regarding the timing at which the light emitting unit 2 outputs the measurement light W1 from the light emission control unit 11. The distance acquisition unit 14 acquires information regarding a pixel signal received from the pixel cell 30 of the light receiving unit 3 from the light receiving control unit 12. The distance acquisition unit 14 acquires information on the frequency and vibration timing of the vibration applying unit 5 from the vibration control unit 13. The distance acquisition unit 14 is the distance from the distance measurement system 100 to the object 200 based on the information received from the light emission control unit 11, the information received from the light reception control unit 12, and the information received from the vibration control unit 13. Ask for.

The distance acquisition unit 14 obtains the distance to the object 200 based on the time from when the light emitting unit 2 outputs the measurement light W1 until the light receiving unit 3 receives the measurement light W1. A specific method for obtaining the distance by the distance measuring system 100 including the distance acquisition unit 14 will be described in the column of “(1.2.2) Operation”.

(1.2.2) Operation Next, a specific example of the operation of the distance measuring system 100 to obtain the distance to the object 200 existing in the target space S1 will be described with reference to FIGS. 6 and 7.

As shown in FIG. 6, the distance measurement system 100 includes k (k is an integer of 2 or more) sub-periods corresponding to one distance measurement (hereinafter, referred to as “frame F1”). Divide into. Here, the distance measuring device 1 divides the frame F1 so as to include k sub-periods (first sub-period Tt1 to k-th sub-period Ttk) having equal time lengths with each other. Each sub-period is followed by a waiting time.

In the distance measurement system 100 of the present embodiment, the length (temporal length) of the frame F1 is set to be equal to the vibration period of the diffraction grating 41. That is, the measurement light W1 draws a locus for one cycle (two-dimensionally) during one frame F1. For example, when the vibration frequency of the diffraction grating 41 is 1 kHz, the length of the frame F1 is 1 ms.

Therefore, dividing the frame F1 so as to include k sub-periods corresponds to dividing the locus of the measurement light W1 (see FIG. 4) into k portions. Here, the distance measuring device 1 divides the frame F1 so as to include eight sub-periods of the first sub-period Tt1 to the eighth sub-period Tt8. The first sub-period Tt1 here corresponds to a period in which the measurement light W1 emitted from the diffraction grating 41 passes through the point P1 (or its vicinity) in the surface P100. Similarly, the second sub-period Tt2 to the eighth sub-period Tt8 correspond to the periods during which the measurement light W1 emitted from the diffraction grating 41 passes through the points P2 to P8 (or its vicinity) in the surface P100, respectively.

As shown in FIG. 7, the distance measuring device 1 further divides each sub-period so that n (n is an integer of 2 or more) measurement periods are included. That is, the distance measuring device 1 divides one sub-period so as to include n measurement periods of the first measurement period Tm1 to the nth measurement period Tmn. For example, the length of each measurement period is set equally.

Further, as shown in FIG. 7, the distance measuring device 1 further divides each measurement period into n division periods. Here, the distance measuring device 1 divides each measurement period into n division periods of the first division period Ts1 to the nth division period Tsn.

Then, the measurement control unit 10 of the distance measuring device 1 outputs the measurement light W1 (pulse light) from the light emitting unit 2 in the first division period (first division period Ts1) of each measurement period in one sub period. ..

Further, the measurement control unit 10 of the distance measuring device 1 exposes the pixel cell 30 of the light receiving unit 3 in any of the first division period Ts1 to the nth division period Tsn in each measurement period. The measurement control unit 10 sequentially shifts the timing of exposing the pixel cell 30 from the first division period Ts1 to the nth division period Tsn one by one in the first measurement period Tm1 to the nth measurement period Tmn.

In short, the light emitting control unit 11 causes the light emitting unit 2 to output the measurement light W1 a plurality of times. The light receiving control unit 12 exposes the light receiving unit 3 to the measurement light W1 output a plurality of times at different timings from the start time of the output of the measurement light W1 from the light emitting unit 2.

More specifically, the measurement control unit 10 exposes the pixel cell 30 in the first division period Ts1 in the first measurement period Tm1 and exposes the pixel cell 30 in the second division period Ts2 in the second measurement period Tm2. In the n measurement period Tmn, the exposure timing of the pixel cell 30 is controlled so that the pixel cell 30 is exposed in the nth division period Tsn (see FIG. 7). Therefore, when viewed in one sub-period, in the pixel cell 30, all of the first division period Ts1 to the nth division period Tsn are exposed in any of the measurement periods.

The pixel cell 30 of the light receiving unit 3 can detect the reflected light reflected by the object 200 only during the exposure period. The time from when the light emitting unit 2 emits light until the reflected light reaches the light receiving unit 3 varies depending on the distance from the distance measuring system 100 to the object 200. Assuming that the distance from the distance measurement system 100 to the object 200 is d and the speed of light is c, the reflected light reaches the light receiving unit 3 after a time t = 2d / c after the light emitting unit 2 emits light. Therefore, in the distance measuring device 1, in which division period the pixel cell 30 of the light receiving unit 3 received the reflected light, in other words, in which measurement period the pixel cell 30 of the light receiving unit 3 received the reflected light. , It is possible to calculate the distance to the object 200 in the emission direction of the measurement light W1 in this sub-period.

For example, in the example of FIG. 7, the reflected light from the object 200 reaches the time spanning the second division period Ts2 and the third division period Ts3 in each measurement period. In this case, in the first measurement period Tm1 in which the pixel cell 30 is exposed in the first division period Ts1, the light receiving unit 3 does not detect the presence of the reflected light. On the other hand, in the second measurement period Tm2 in which the pixel cell 30 is exposed in the second division period Ts2 and the third measurement period Tm3 in which the pixel cell 30 is exposed in the third division period Ts3, the reflected light reaches the light receiving unit 3. Since the pixel cell 30 is exposed at the timing of the exposure, the light receiving unit 3 detects the reflected light. As a result, the distance measuring device 1 (distance acquisition unit 14) emits light with a distance (c × Ts / 2) corresponding to the period from the start of light emission by the light emitting unit 2 to the start of the second division period Ts2. It is said that the object 200 exists in the distance range between the distance (3 × c × Ts / 2) corresponding to the period from the start of light emission by the unit 2 to the end of the third division period Ts3. Can be determined. Here, "c" above indicates the speed of light, and "Ts" indicates the length of the division period.

As is clear from the above description, the measurable distance of the distance measuring system 100 (the upper limit of the distance that the distance measuring system 100 can measure the distance) is represented by n × Ts × c / 2. For example, when the length Ts of the division period is 10 ns and the number n of the measurement periods is 10, the measurable distance is 15 m. Further, the resolution of the distance by the distance measuring device 1 is represented by Ts × c / 2. For example, when the length Ts of the division period is 10 ns, the resolution of the distance is 1.5 m. The length Tt of the sub-period is represented by n × Ts × n, ignoring the read period (described later). For example, when the length Ts of the division period is 10 ns and the number of measurement periods (= number of division periods) n is 10, the length Tt of the sub period is 10 μs if the read period is ignored.

In each sub-period, after each of the plurality of measurement periods, there is a read period. During the reading period, the image sensor 31 acquires pixel signals from a plurality of pixel cells 30 (hereinafter, also referred to as “reading pixel values”), and the pixel output unit 32 outputs the acquired pixel signals to the distance measuring device 1. It is a period to do.

Here, the pixel output unit 32 transfers only the pixel signal (pixel value) of the pixel cell 30 corresponding to the current sub-period to the distance measuring device 1 (light receiving control unit 12) among the plurality of pixel cells 30. Output. That is, in the first sub-period Tt1 in which the measurement light W1 is applied to the point P1 (see FIG. 4), the pixel output unit 32 transmits only the pixel signal of the pixel cell 301 (see FIG. 5) corresponding to the point P1 at a distance. Output to measuring device 1. Further, in the second sub-period Tt2 in which the measurement light W1 is applied to the point P2 (see FIG. 4), the pixel output unit 32 transmits only the pixel signal of the pixel cell 302 (see FIG. 5) corresponding to the point P2 at a distance. Output to measuring device 1. That is, the light receiving control unit 12 changes the pixel cell 30 that outputs the pixel signal among the plurality of pixel cells 30 according to the vibration position of the optical element 4 that vibrates according to the vibration cycle. For example, in the first sub-period Tt1, the vibration position of the optical element 4 is a position corresponding to the point P1. By limiting the pixel cell 30 that outputs the pixel signal in this way, the amount of data of the signal transmitted from the light receiving unit 3 to the distance measuring device 1 can be reduced.

The distance acquisition unit 14 is based on the pixel signal output from the pixel cell 30 of the light receiving unit 3 in each sub period, and the object 200 existing in the target space S1 in the emission direction of the measurement light W1 corresponding to this sub period. Find the distance to.

In this way, the distance acquisition unit 14 obtains the distance to the object 200 existing in the emission direction of the measurement light W1 passing through the point P1 in the first sub-period Tt1, and the point in the second sub-period Tt2. The distance to the object 200 existing in the emission direction of the measurement light W1 passing through P2 is obtained. That is, the distance measurement system 100 can obtain the distance to the object 200 existing in the target space S1 in a plurality of emission directions.

When the distance to the object 200 is obtained for all of the plurality of (k) sub-periods, the distance acquisition unit 14 generates a distance image based on the obtained k distances. The distance image is, for example, an image in which the pixel value of each pixel corresponds to the distance to the object 200 existing in the target space S1. In the present embodiment, the distance acquisition unit 14 can generate a distance image including at least the number of pixels (8) in the sub-period.

In the above description, the 0th-order light of the measurement light W1 by the diffraction grating 41 has been focused on, but the m-th order light (m is an integer of 1 or more) of the measurement light W1 is also emitted from the diffraction grating 41. To. Therefore, it is possible to measure the distance in the same manner as in the case of the 0th order light by using the mth order light of the measurement light W1. That is, by diffracting the measurement light W1 with the diffraction grating 41, a plurality of lights corresponding to a plurality of interference fringes can be generated, and the distances to a plurality of positions in the space can be measured by the plurality of lights. Is possible. In short, according to the distance measurement system 100, it is possible to measure the distance to the object 200 existing in the target space S1 within the range in which the diffracted light of the measurement light W1 exists.

The distance measurement system 100 may generate a composite distance image obtained by synthesizing a distance image obtained by using 0th order light and a distance image obtained by using mth order light. At least a part of the pixel cell 30 for receiving the reflected light of the 0th order light and the pixel cell 30 for receiving the reflected light of the mth order light may overlap, or the pixel cells 30 are separate. It may be.

(2) Modified Example The above-described embodiment is only one of the various embodiments of the present disclosure. The above-described embodiment can be changed in various ways depending on the design and the like as long as the object of the present disclosure can be achieved. A modified example of the above embodiment is listed. The modifications described below can be applied in combination as appropriate. In the following, the above embodiment may be referred to as a "basic example". Further, the same function as the distance measuring device 1 of the distance measuring system 100 may be realized by a distance measuring method, a (computer) program, a non-temporary recording medium on which the program is recorded, or the like.

The distance measuring method according to one aspect includes a light emission control step, a light reception control step, a vibration control step, and a distance acquisition step. The light emission control step includes controlling the timing of outputting the measurement light W1 from the light emitting unit 2 that outputs the measurement light W1. The light receiving control step includes controlling the operation of the light receiving unit 3 having a plurality of pixel cells 30 for receiving the measurement light W1 reflected by the object 200. The vibration control step includes controlling the operation of the vibration applying unit 5 that vibrates the optical element 4 arranged on the optical path LP1 of the measurement light W1 from the light emitting unit 2 to the object 200. The distance acquisition step includes obtaining the distance to the object 200 from the time from when the light emitting unit 2 outputs the measurement light W1 until the light receiving unit 3 receives the measurement light W1.

The distance measurement system 100 in the present disclosure includes, for example, a computer system in the measurement control unit 10 and the distance acquisition unit 14 of the distance measurement device 1. The main configuration of a computer system is a processor and memory as hardware. When the processor executes the program recorded in the memory of the computer system, the functions as the measurement control unit 10 and the distance acquisition unit 14 in the present disclosure are realized. The program may be pre-recorded in the memory of the computer system, may be provided through a telecommunications line, and may be recorded on a non-temporary recording medium such as a memory card, optical disk, hard disk drive, etc. that can be read by the computer system. May be provided. A processor in a computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The integrated circuit such as IC or LSI referred to here has a different name depending on the degree of integration, and includes an integrated circuit called a system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Further, an FPGA (Field-Programmable Gate Array) programmed after the LSI is manufactured, or a logical device capable of reconfiguring the junction relationship inside the LSI or reconfiguring the circuit partition inside the LSI should also be adopted as a processor. Can be done. A plurality of electronic circuits may be integrated on one chip, or may be distributed on a plurality of chips. The plurality of chips may be integrated in one device, or may be distributed in a plurality of devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

Further, it is not an essential configuration for the distance measurement system 100 that a plurality of functions in the distance measurement system 100 are integrated in one housing. The components of the distance measurement system 100 may be distributed in a plurality of housings. Further, at least a part of the functions of the distance measuring system 100 such as the distance acquisition unit 14 may be realized by, for example, a server device and a cloud (cloud computing). On the contrary, as in the above-described embodiment, all the functions of the distance measuring system 100 may be integrated in one housing.

In one modification, as shown in FIG. 8, the light emitting unit 2 may have a plurality of light sources 21. The plurality of light sources 21 may be arranged in an array, and in particular, may be arranged in a matrix similar to the lattice points of the diffraction grating 41. The arrangement of the plurality of light sources 21 may be similar to the arrangement of the lattice points of the diffraction grating 41. The distance d1 between adjacent light sources 21 may be equal to the grid spacing of the diffraction grating 41. In this case, it is possible to reduce the intensity unevenness of the measurement light W1 (intensity unevenness that can occur between a plurality of diffracted lights such as 0th-order light and primary light in the surface P100).

In the basic example, the light receiving control unit 12 outputs a pixel signal from only the corresponding pixel cell 30 of the plurality of pixel cells 30 according to the vibration position of the optical element 4, but the present invention is not limited to this. In one modification, the light receiving control unit 12 may receive pixel signals from all of the plurality of pixel cells 30 regardless of the vibration position of the optical element 4 that vibrates according to the vibration cycle. In this case, for example, even when the reflected light is received by a pixel cell 30 different from the assumed pixel cell 30 due to a misalignment of the optical element 4, the data can be used. Become.

In one modification, the image sensor 31 may read the pixel values from all of the plurality of pixel cells 30 in the read period after the measurement period, or may read the pixel values only from the pixel cells 30 corresponding to the current sub period. You may read it.

In the distance measurement system 100 of the basic example, when focusing on one sub-period, the operation of outputting (light emitting) the measurement light W1 and receiving the reflected light while the optical element 4 vibrates once is called light emission and exposure. It was performed n times while changing the time difference of, but it is not limited to this. In one modification, the operation of outputting the measurement light W1 and receiving the reflected light is performed only once in one vibration cycle of the optical element 4 for each sub-period, and this is performed to reduce the time difference between light emission and exposure. It may be performed for n vibration cycles while changing. That is, in the first vibration cycle, the light receiving unit 3 is exposed at a timing corresponding to the first division period Ts1, and in the second vibration cycle, the light receiving unit 3 is exposed at a timing corresponding to the second division period Ts2. And so on. Even in this way, it is possible to measure the distance to the object 200 existing in the object space S1.

In one modification, the optical element 4 may be a diffuser that diffuses the measurement light W1. Even in this case, the emission direction of the measurement light W1 from the distance measurement system is changed by vibrating the diffuser plate. Therefore, the target space S1 can be scanned by the measurement light W1.

In one modification, the optical element 4 may be a reflective optical element that reflects the measurement light W1. Even in this case, the emission direction of the measurement light W1 from the distance measurement system is changed by vibrating the reflection type optical element. Therefore, the target space S1 can be scanned by the measurement light W1. For example, the optical element 4 may be a reflection type diffraction grating 41 or a reflection type diffusion plate.

In one modification, the optical element 4 and the vibration imparting portion 5 may be MEMS (Micro Electro Mechanical Systems) integrated on a silicon substrate, a glass substrate, or the like by a microfabrication technique.

The vibration of the optical element 4 is not limited to that of the basic example. For example, the vibration control unit 13 may vibrate the optical element 4 a plurality of times in the horizontal direction while the optical element 4 vibrates 1/2 times in the vertical direction. It is preferable that the measurement light W1 is scanned so that the locus of the measurement light W1 fills a predetermined region (without gaps) in the surface P100.

(3) Summary The following aspects are disclosed from the embodiments and modifications described above.

The distance measuring device (1) according to the first aspect includes a light emitting control unit (11), a light receiving control unit (12), a vibration control unit (13), and a distance acquisition unit (14). The light emission control unit (11) controls the timing at which the measurement light (W1) is output from the light emitting unit (2) that outputs the measurement light (W1) toward the target space (S1). The light receiving control unit (12) controls the operation of the light receiving unit (3). The light receiving unit (3) has a plurality of pixel cells (30) for receiving the measurement light (W1) reflected by the object (200) existing in the target space (S1). The vibration control unit (13) controls the operation of the vibration applying unit (5). The vibration applying portion (5) vibrates the optical element (4). The optical element (4) is arranged on the optical path (LP1) of the measurement light (W1) from the light emitting unit (2) to the object (200). The distance acquisition unit (14) is based on the time from when the light emitting unit (2) outputs the measurement light (W1) to when the light receiving unit (3) receives the measurement light (W1). Find the distance to.

According to this aspect, the vibration applying portion (5) vibrates the optical element (4), so that the output direction of the measurement light (W1) from the light emitting portion (2) vibrates. Therefore, the target space (S1) can be scanned by the measurement light (W1).

In the distance measuring device (1) of the second aspect, in the first aspect, the light emitting unit (2) is configured to output pulsed light. The distance measuring device (1) has a light emitting unit (2) and a vibration applying unit (5) so that the light emitting cycle of the pulsed light is shorter than the vibration cycle in which the vibration applying unit (5) vibrates the optical element (4). ) Is controlled.

According to this aspect, the pulsed light is output at least once while the vibration applying unit (5) vibrates the optical element (4) for one cycle. That is, the distance can be measured at least once while the vibration applying unit (5) vibrates the optical element (4) for one cycle. Therefore, it is possible to measure the distance at at least one vibration position in one cycle of the vibration of the optical element (4). The emission cycle of the pulsed light may be half or less of the vibration cycle. In this case, since the pulsed light is output twice or more while the vibration applying unit (5) vibrates the optical element (4) for one cycle, the vibration applying unit (5) vibrates the optical element (4) for one cycle. During the period, the distance can be measured a plurality of times.

In the distance measuring device (1) of the third aspect, in the second aspect, the light receiving control unit (12) is configured to receive pixel signals from a plurality of pixel cells (30). The light receiving control unit (12) changes the pixel cell (30) that outputs a pixel signal among the plurality of pixel cells (30) according to the vibration position of the optical element (4) that vibrates according to the vibration cycle. ..

According to this aspect, the distance measuring device (1) does not receive pixel signals from all of the plurality of pixel cells (30), but pixels only from the pixel cells (30) according to the vibration position of the optical element (4). Receive a signal. Therefore, the amount of data of the signal transmitted from the light receiving unit (3) to the distance measuring device (1) can be reduced.

In the distance measuring device (1) of the fourth aspect, in the second aspect, the light receiving control unit (12) is configured to receive pixel signals from a plurality of pixel cells (30). The light receiving control unit (12) receives pixel signals from all of the plurality of pixel cells (30) regardless of the vibration position of the optical element (4) that vibrates according to the vibration cycle.

According to this aspect, even when the reflected light is received by a pixel cell (30) different from the assumed pixel cell (30) due to, for example, a misalignment of the optical element (4). The data can be used.

In the distance measuring device (1) of the fifth aspect, in any one of the first to fourth aspects, the optical element (4) is a diffraction grating (41).

According to this aspect, the traveling direction of the measurement light (W1) can be changed by vibrating the diffraction grating (41) by the vibration applying portion (5). Further, by diffracting the measurement light (W1) with the diffraction grating (41), a plurality of lights corresponding to a plurality of interference fringes can be generated, and the distances to a plurality of positions in the space by the plurality of lights. Can be measured.

In the distance measuring device (1) of the sixth aspect, in the fifth aspect, the diffraction grating (41) is a two-dimensional diffraction grating. The light emitting unit (2) has a plurality of light sources (21) arranged in an array at intervals corresponding to the lattice intervals of the diffraction grating (41).

According to this aspect, it is possible to suppress variations in the intensities of a plurality of lights generated by the diffraction grating (41).

In the distance measuring device (1) of the seventh aspect, in any one of the first to fourth aspects, the optical element (4) is a diffuser that diffuses the measurement light (W1).

According to this aspect, the traveling direction of the measurement light (W1) can be changed by vibrating the diffuser plate by the vibration applying portion (5).

In the distance measuring device (1) of the eighth aspect, in any one of the first to seventh aspects, the optical element (4) is a transmission type optical element that transmits the measurement light (W1).

According to this aspect, the traveling direction of the measurement light (W1) can be changed by vibrating the optical element (4) by the vibration applying portion (5).

In the distance measuring device (1) of the ninth aspect, in any one of the first to seventh aspects, the optical element (4) is a reflection type optical element that reflects the measurement light (W1).

According to this aspect, the traveling direction of the measurement light (W1) can be changed by vibrating the optical element (4) by the vibration applying portion (5).

In the distance measuring device (1) of the tenth aspect, in any one of the first to ninth aspects, the vibration control unit (13) emits the measurement light (W1) in the plane intersecting the optical path (LP1). The optical element (4) is vibrated by the vibration applying portion (5) so as to vibrate in a two-dimensional manner.

According to this aspect, the measurement light (W1) can be vibrated in a two-dimensional manner.

In the distance measuring device (1) of the eleventh aspect, in any one of the first to tenth aspects, the light emitting control unit (11) causes the light emitting unit (2) to output the measurement light (W1) a plurality of times. .. In the measurement light (W1) that is output a plurality of times, the light receiving control unit (12) causes the light receiving unit (3) to have the elapsed time from the start of the output of the measurement light (W1) from the light emitting unit (2). Expose at different timings.

According to this aspect, a plurality of measurement processes of outputting the measurement light (W1) from the light emitting unit (2) and receiving the measurement light (W1) at the light receiving unit (3) are performed while changing the time from the output to the light reception. Do it times. Therefore, it is possible to measure the distance to the object (200) by determining in which measurement process the measurement light (W1) is received.

The distance measuring system (100) according to the twelfth aspect includes a distance measuring device (1), a light emitting unit (2), a light receiving unit (3), and an optical element (1) according to any one of the first to eleventh aspects. 4) and a vibration imparting unit (5) are provided.

According to this aspect, the vibration applying portion (5) vibrates the optical element (4), so that the output direction of the measurement light (W1) from the light emitting portion (2) vibrates. Therefore, the target space S1 can be scanned by the measurement light W1.

The distance measuring method of the thirteenth aspect includes a light emission control step, a light reception control step, a vibration control step, and a distance acquisition step. The light emission control step includes controlling the timing of outputting the measurement light (W1) from the light emitting unit (2) that outputs the measurement light (W1). The light receiving control step includes controlling the operation of the light receiving unit (3) having a plurality of pixel cells (30) for receiving the measurement light (W1) reflected by the object (200). In the vibration control step, the operation of the vibration applying unit (5) that vibrates the optical element (4) arranged on the optical path (LP1) of the measurement light (W1) from the light emitting unit (2) to the object (200). Including controlling. In the distance acquisition step, the distance from the object (200) is obtained from the time from when the light emitting unit (2) outputs the measurement light (W1) to when the light receiving unit (3) receives the measurement light (W1). Including that.

According to this aspect, the vibration applying portion (5) vibrates the optical element (4), so that the output direction of the measurement light (W1) from the light emitting portion (2) vibrates. Therefore, the target space S1 can be scanned by the measurement light W1.

1 Distance measuring device 11 Light emitting control unit 12 Light receiving control unit 13 Vibration control unit 14 Distance acquisition unit 2 Light emitting unit 21 Light source 3 Light receiving unit 30 Pixel cell 4 Optical element 41 Diffraction grating 5 Vibration imparting unit 100 Distance measurement system 200 Object LP1 Optical path S1 Target space W1 Measurement light

Claims (13)

A light emitting control unit that controls the timing of outputting the measurement light from the light emitting unit that outputs the measurement light toward the target space,
A light receiving control unit that controls the operation of a light receiving unit having a plurality of pixel cells for receiving the measurement light reflected by the object existing in the target space.
A vibration control unit that controls the operation of a vibration applying unit that vibrates an optical element arranged on the optical path of the measurement light from the light emitting unit to the object.
A distance acquisition unit that obtains the distance to the object based on the time from when the light emitting unit outputs the measurement light to when the light receiving unit receives the measurement light.
To prepare
Distance measuring device. The light emitting unit is configured to output pulsed light.
The distance measuring device controls the light emitting unit and the vibration applying unit so that the light emitting cycle of the pulsed light is shorter than the vibration cycle in which the vibration applying unit vibrates the optical element.
The distance measuring device according to claim 1. The light receiving control unit is configured to receive pixel signals from the plurality of pixel cells.
The light receiving control unit changes the pixel cell that outputs the pixel signal among the plurality of pixel cells according to the vibration position of the optical element that vibrates according to the vibration cycle.
The distance measuring device according to claim 2. The light receiving control unit is configured to receive pixel signals from the plurality of pixel cells.
The light receiving control unit receives pixel signals from all of the plurality of pixel cells regardless of the vibration position of the optical element that vibrates according to the vibration cycle.
The distance measuring device according to claim 2. The optical element is a diffraction grating.
The distance measuring device according to any one of claims 1 to 4. The diffraction grating is a two-dimensional diffraction grating, and is
The light emitting unit has a plurality of light sources arranged in an array at intervals corresponding to the lattice intervals of the diffraction grating.
The distance measuring device according to claim 5. The optical element is a diffuser that diffuses the measurement light.
The distance measuring device according to any one of claims 1 to 4. The optical element is a transmissive optical element that transmits the measurement light.
The distance measuring device according to any one of claims 1 to 7. The optical element is a reflective optical element that reflects the measurement light.
The distance measuring device according to any one of claims 1 to 7. The vibration control unit vibrates the optical element by the vibration imparting unit so that the measurement light vibrates in a two-dimensional manner in a plane intersecting the optical path.
The distance measuring device according to any one of claims 1 to 9. The light emission control unit outputs the measurement light from the light emitting unit a plurality of times.
The light receiving control unit exposes the light receiving unit to the measurement light that is output a plurality of times at different timings from the start time of the output of the measurement light from the light emitting unit.
The distance measuring device according to any one of claims 1 to 10. The distance measuring device according to any one of claims 1 to 11,
With the light emitting part
With the light receiving part
With the optical element
With the vibration applying part
To prepare
Distance measurement system. A light emission control step that controls the timing of outputting the measurement light from the light emitting unit that outputs the measurement light,
A light receiving control step that controls the operation of a light receiving unit having a plurality of pixel cells for receiving the measurement light reflected by the object, and a light receiving control step.
A vibration control step that controls the operation of the vibration applying unit that vibrates the optical element arranged on the optical path of the measurement light from the light emitting unit to the object.
A distance acquisition step of obtaining the distance to the object based on the time from when the light emitting unit outputs the measurement light to when the light receiving unit receives the measurement light.
including,
Distance measurement method.

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