JP6424581B2 - Optical flight type distance measuring device - Google Patents

Description

  The present invention emits modulated light modulated in a pattern having a repetitive cycle to space, receives modulated incident light including reflected light reflected by an object, and uses a charge according to the received incident light The present invention relates to an optical flight type ranging apparatus which calculates a distance from an own apparatus to an object and obtains a ranging value.

  A TOF (Time of Flight) type distance measuring device is provided as a distance measuring device which calculates the distance from the own device to an object without contact. The optical flight type distance measuring apparatus emits modulated light (ranging light) modulated in a pattern having a repetitive cycle to space, and receives incident light including reflected light which is reflected by the object. Then, the light flight type distance measuring apparatus calculates the distance from the own device to the object using the charge corresponding to the received incident light to obtain the distance measurement value (for example, see Patent Documents 1 to 4).

  In the optical flight type distance measuring apparatus, when the distance from the own apparatus to the object is short or the object is an object having a high reflectance, the reflected light of high intensity is received. On the other hand, when the distance from the own apparatus to the object is long or the object is an object with low reflectance, only reflected light of weak intensity is received. Therefore, a large dynamic range (for example, 80 dB or more) is required in the optical flight distance measuring apparatus. Particularly in the case of on-vehicle etc., if at least one of the own device and the object (person, vehicle, wall, etc.) is moving, if the distance from the own device to the object is short, Frequent calculations of the distance (increasing the frame rate) are required to avoid collisions. That is, it is necessary to make a large dynamic range and a high frame rate compatible.

  It is difficult to achieve a dynamic range of 80 dB or more with ordinary pixels, and it is necessary to perform multiple exposure (multiple exposures). However, when multiple exposures are performed in series, the exposure time becomes long, which causes a problem that the followability to a moving object is deteriorated. In this regard, a method of dividing a plurality of pixels in a plane into several pixel groups and changing the exposure time for each pixel group is disclosed (see, for example, Non-Patent Documents 1 and 2). As shown in FIGS. 21 and 22, the light receiving element 101 is configured to have a PD (Photodiode) 102, two modulation switches 103a and 103b, and one storage capacitor 104, and performs four-phase distance measurement. The case will be described as an example. In this case, as shown in FIG. 23, for example, the pixel group of pixel A repeats driving 1000 times to perform long-time exposure, and the pixel group of pixel B repeats driving 100 times to perform short-time exposure. The dynamic range can be extended by 20 dB.

Patent No. 5579893 gazette JP, 2010-96730, A Patent No. 5855903 gazette JP, 2010-25906, A

S.Nayar and T.Mitsunaga. "High Dynamic Range Imaging: Spatial Varying Pixel Exposures." In IEEE Conference on Computer Vision and Pattern Recognition (CVPR), volume 1, pages 472-479, Jun 2000 S. G. Narasimhan and S. K. Nayar "Enhancing Resolution Along Multiple Imaging Dimensions Using Assorted Pixels." "IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE, VOL. 27, NO. 4, APRIL 2005, pp. 518

  By dividing a plurality of pixels in a plane into a pixel group that performs long-time exposure and a pixel group that performs short-time exposure as described above, the frame rate can be increased compared to when multiple exposure is performed in series. However, as with long-time exposure, even if it is 4-phase distance measurement even in short-time exposure, the distance is calculated after each value of 0 degree, 90 degrees, 180 degrees, and 270 degrees is read out. Will be subject to the long exposure time. As described above, in the methods of Non-Patent Documents 1 and 2, there is a limit in increasing the frame rate of short-time exposure.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an optical flight distance measuring capable of appropriately enhancing a frame rate of short time exposure while appropriately expanding a dynamic range. It is in providing an apparatus.

According to the first aspect of the present invention, the light emitting element emits the modulated light modulated in the pattern having the repetition period to the space. The driving means drives the light emitting element. Each of the plurality of light receiving elements constitutes an in-plane pixel, and receives incident light including reflected light that the modulated light is reflected by the object. The control means controls charge accumulation in the plurality of light receiving elements and readout of the charge from the plurality of light receiving elements. The distance measurement value acquisition means calculates the distance from the own device to the object using the charge read out by the control means from the plurality of light receiving elements, and acquires the distance measurement value. In this case, the control means divides a plurality of pixels in the plane into several pixel groups, and the light receiving elements belonging to one pixel group perform long-time exposure once, thereby performing distance measurement by the distance measurement value acquiring means. Distance measurement is performed by the distance measurement value acquisition unit by performing multiple short exposures by the light receiving elements belonging to the other pixel groups performing charge accumulation and readout in multiple phases within a period in which the value is acquired once. The drive of the plurality of light receiving elements is controlled so that the value is acquired a plurality of times.

  That is, the dynamic range can be expanded by dividing a plurality of pixels in the plane into a pixel group that performs long-time exposure and a pixel group that performs short-time exposure. Also, within a period in which the light receiving elements of the pixel group performing the long time exposure acquire one distance measurement value by one long time exposure, the light receiving elements of the pixel group performing the short time exposure are subjected to multiple short exposures. The frame rate of the short time exposure can be increased by acquiring the distance measurement value multiple times. Thus, it is possible to appropriately increase the frame rate of the short exposure while appropriately expanding the dynamic range. In particular, it is suitable in the case of an on-vehicle in which at least one of the own apparatus and the target moves.

A functional block diagram showing the configuration of a single end output according to a first embodiment of the present invention The figure which shows the constitution of the light receiving element (1 capacity constitution) Diagram showing the sequence of single-ended output configuration A diagram showing a timing chart for performing multiple exposure in the configuration of single end output (part 1) The figure which shows the timing chart which performs multiple exposure in the structure of a single end output (the 2) The figure which shows the timing chart which performs multiple exposure in the structure of a single end output (the 3) Diagram showing arrangement of pixels (part 1) Diagram showing arrangement of pixels (part 2) The figure which shows the aspect which changes exposure time for every pixel The figure which shows the timing chart which performs multiple exposure in the structure of a single end output (the 4) Diagram showing the arrangement of pixels (Part 3) Diagram showing the arrangement of pixels (Part 4) A functional block diagram showing a configuration of differential output according to a second embodiment of the present invention Diagram showing the configuration of a light receiving element (2-capacitance configuration) Show a sequence of configuration of differential output (part 1) The figure which shows the timing chart which performs multiple exposure in the structure of a differential output (the 1) Show a sequence of configuration of differential output (part 2) The figure which shows the timing chart which performs multiple exposure in the structure of a differential output (the 2) Show the sequence of configuration of differential output (Part 3) The figure which shows the timing chart which performs multiple exposure in the structure of a differential output (the 3) The figure which shows the constitution of the light receiving element (1 capacity constitution) Diagram showing the sequence of single-ended output configuration Diagram showing a timing chart for performing conventional multiple exposure

First Embodiment
Hereinafter, a first embodiment in which the present invention is applied to, for example, an on-vehicle optical flight distance measuring apparatus that can be mounted on a vehicle will be described with reference to FIGS. 1 to 12. The first embodiment is a single-ended output configuration. The optical flight type distance measuring apparatus 1 comprises a signal source 2, a drive circuit 3 (drive means), a light emitting element 4, a control circuit 5 (control means), a light receiving element 6, and a distance measurement value acquisition circuit 7 (measurement means). Distance acquisition means). The distance measurement value acquisition circuit 7 includes a buffer 8, an AD conversion circuit 9, and a digital signal processing circuit 10.

  The signal source 2 outputs a drive signal to the drive circuit 3 and the control circuit 5 to establish synchronization between the light emitting element 4 and the light receiving element 6 and synchronizes with the modulated light emitted from the light emitting element 4. The exposure of the light receiving element 6 is controlled. The drive signal output from the signal source 2 may be a rectangular pulse (usually several to several tens of MHz) for driving the light emitting element 4 and the light receiving element 6 or may be only a synchronization pulse. The light emitting element 4 is, for example, a laser diode (LD) or a light emitting diode (LED) that emits infrared light as modulated light. The light receiving element 6 is an image sensor using, for example, a process of a complementary metal oxide semiconductor (CMOS) or a charge coupled device (CCD).

  As shown in FIG. 2, the light receiving element 6 has a PD (Photodiode) 11, two modulation switches 12a and 12b, and one storage capacitor 13. The two modulation switches 12a and 12b are, for example, MOS type devices such as MOS transistors and transfer gates, and devices having a CCD structure. The storage capacitor 13 is, for example, a capacitive element such as MOS, CCD, MIM (Metal Insulator Metal), wiring, parasitic capacitance of a PN junction, or the like. The light receiving element 6 drives the modulation switches 12a and 12b by the control signal (gate signal) TG1, stores the charge generated by the received incident light in the storage capacitor 13, and obtains the distance value for the signal indicating the charge amount of the charge. It outputs to the circuit 7. Since the control signal TG1 is a signal synchronized with the modulated light, the charge amount of the charge stored in the storage capacitor 13 changes according to the distance from the own device to the object.

  The buffer 8 is realized by, for example, a source follower circuit because of its simplicity. The AD conversion circuit 9 converts the signal input from the buffer 8 from an analog signal into a digital signal and outputs the digital signal to the digital signal processing circuit 10. The digital signal processing circuit 10 performs digital signal processing on the signal input from the AD conversion circuit 9, calculates the distance from the own device to the object from the charge amount of the charge stored in the storage capacitor 13, and obtains the distance measurement value. Yes (find distance).

  FIG. 3 shows a sequence (modulation period: Tm, exposure period: Tw) in the case of performing four-phase distance measurement (driving the light receiving element 6 with four phases) with the duty of the light emission waveform being 50%. The waveform (light emission waveform 110) of the modulated light emitted from the light emitting element 4 is modulated by a rectangular wave synchronized with the control signal TG1. Although FIG. 3 exemplifies a case where modulation is performed using a rectangular wave, modulation may be performed using a waveform such as a sine wave, a triangular wave, or a pseudo random sequence. The waveform (reflected waveform 120) of the reflected light in which the modulated light is reflected by the object has a time difference with respect to the light emission waveform 110, and thus becomes a waveform delayed by a phase difference φ with respect to the light emission waveform 110. On the other hand, the control signal TG1 is driven by rectangular waves that differ in phase by 90 degrees. The digital signal processing circuit 10 repeats the sequence driven by the control signals TG1-1 and TG1-2 (driving waveforms 111 and 112) in a cycle of several tens to several hundreds of thousands of times, and then generates information of the charges Q1 and Q2 generated. Acquire (charge voltage converted voltage value). Thereafter, the digital signal processing circuit 10 repeats the sequence driven by the control signals TG1-3 and TG1-4 (the drive waveforms 113 and 114) in a cycle of several tens to several hundreds of thousands times similarly, and generates the charge Q3. Get Q4, information. Then, the digital signal processing circuit 10 calculates the phase difference θ according to the following arithmetic expression (1) from the acquired Q1 to Q4 using the discrete Fourier transform (DFT).

θ = tan ⁻¹ [(Q ¹ -Q 3) / (Q 2 -Q 4)] (1)
Although the equation (1) is an equation for calculating the phase difference based on the four samplings, it is possible to calculate the phase difference θ according to the following equation (2) even for a general N phase.

θ = tan ⁻¹ [(ΣQk * sin (2π / N * k)) / (ΣQk * cos (2π / N * k))] (2)

  Now, in such a phase-type optical flying distance measuring apparatus 1, when assuming that it is used on a vehicle as described in [Background Art], expansion of the dynamic range is required, and a short time is required. It is required to improve the exposure frame rate. Hereinafter, a method of increasing the frame rate of short exposure while expanding the dynamic range according to the present invention will be described.

  FIG. 4 shows a timing chart of multiple exposure in the single-ended output configuration of the present invention. Compared to the conventional multiple exposure timing chart shown in FIG. 23 described above, in the multiple exposure of the present invention, the control circuit 5 converts a plurality of pixels in the plane into the pixel group of pixel A and the pixel group of pixel B. The division points are the same. However, in the multiple exposure of the present invention, the control circuit 5 performs charge accumulation and readout not in a single phase but in a plurality of phases in the pixel group of the pixel B during a long exposure period in the pixel group of the pixel A. To perform multiple short exposures. As a result, for the pixel group of the pixel B, the number of times of obtaining the distance measurement value increases compared to the conventional multiple exposure when compared in the same period, the distance measurement value can be updated more frequently, and the frame rate is increased. Can. In the example of FIG. 4, in the case where the pixel group of pixel A performs driving according to the timing chart of FIG. 23 by performing short exposure of four times within the period when the pixel group of pixel A performs long exposure once. Frame rate can be realized. The effective value (sufficient signal amplitude) that can be obtained by such a short time exposure is due to the reflected light reflected from an object with a short distance from the own apparatus or a high reflectance object. The frame rate can be increased for objects that are close in distance or have high reflectivity. That is, it is preferable in an environment where it is required to frequently calculate the distance (increase the frame rate) in order to avoid a collision with an object (person, vehicle, wall, etc.), especially in a vehicle.

  FIG. 5 shows a timing chart of another multiple exposure in a single-ended output configuration. In FIG. 4 mentioned above, although the ratio of the frame rate of long-time exposure to short-time exposure is “4”, the ratio of frame rate is not limited to “4”. That is, the frame rate can be further increased by increasing the cycle number (the number of repetitions) of the short exposure for the long exposure. In the example of FIG. 5, a frame rate of 12 times that of the case of driving by the timing chart of FIG. 23 can be realized, and a frame rate of three times that of the case of driving by the timing chart of FIG. be able to. Conversely, the frame rate can be lowered by reducing (thinning out) the number of cycles of short exposure for long exposure from the viewpoint of signal processing in the subsequent stage.

  FIG. 6 shows a timing chart of yet another multiple exposure in a single-ended output configuration. In FIG. 4 and FIG. 5 described above, although the distance measurement value is acquired once or more by short exposure within a period for each phase of long exposure, distance measurement by short exposure within a period across multiple phases of long exposure You may get the value once. In the example of FIG. 6, a frame rate twice that of the case of driving according to the timing chart of FIG. 23 can be realized.

  7 and 8 show an arrangement in which a plurality of pixels in a plane are divided into two pixel groups. In FIG. 7, the long exposure pixel group A and the short exposure pixel group B are divided into rows. In the configuration of FIG. 7, the wiring of control lines for driving the modulation switches 12a and 12b can be made common, and the frame rate of short-time exposure can be increased without making a major change to the existing configuration. On the other hand, in FIG. 8, the long exposure pixel group A and the short exposure pixel group B are divided into a checkered pattern. In the configuration of FIG. 8, it is necessary to increase the number of control lines, but the spatial resolution can be increased when an image is configured with only a pixel group to which short-time exposure is performed.

  FIG. 9 shows a mode in which a long exposure pixel group and a short exposure pixel group are switched with time. Reflected light that is reflected from an object that is far from the device itself or that has a low reflectance may possibly be received by only one pixel. Therefore, if the long exposure pixel group and the short exposure pixel group are fixed, there is a possibility that an object whose ranging value can not be obtained will appear indefinitely. In this regard, by switching the long exposure pixel group and the short exposure pixel group in time (for example, in units of frames), the occurrence of the above-described problem can be avoided in advance. The example of FIG. 9 is a mode in which switching is performed in the configuration in which the long exposure pixel group and the short exposure pixel group shown in FIG. 7 are divided into rows, but in the long exposure shown in FIG. It is possible to switch similarly in the configuration in which the pixel group and the pixel group for short exposure are divided into a checkered pattern.

  FIG. 10 shows still another multiple exposure timing chart of the single-ended output configuration. Although the pixels in the plane are divided into two pixel groups in FIGS. 4 to 6 described above, they may be divided into three pixel groups. In the example of FIG. 10, in the pixel group of the pixel B which performs medium-time exposure, a frame rate of 4 times that of the pixel group of the pixel A which performs long-time exposure can be realized. In the pixel group of 12, it is possible to realize a frame rate of 12 times that of the pixel group of the pixel A which performs long-time exposure.

  11 and 12 show an arrangement in which a plurality of pixels in a plane are divided into three pixel groups. In FIG. 11, the pixels C are arranged in all the rows, and the pixels A and B are divided so as to be arranged at one-row intervals. In the configuration of FIG. 11, the number of control lines required for one row is two in all rows, and it becomes easy to be common, and when the image is configured with only the pixel group of pixels C, the spatial resolution can be increased. . The pixels A may be arranged in all the rows and the pixels B and the pixels C may be arranged at intervals of one row, or the pixels B may be arranged in all the rows and the pixels A and C may be arranged. You may divide so that it may arrange | position by 1 line space | interval, respectively. On the other hand, in FIG. 12, the pixels A, B, and C are divided so as to be arranged in all the rows. In the configuration of FIG. 12, the number of control lines required for one row is three in all rows, which makes it difficult to share, but the image is configured with only any pixel group of pixel A, pixel B, and pixel C. You can even increase spatial resolution. Even when the plurality of pixels in the plane are divided into three pixel groups as described above, the respective pixel groups may be switched with time.

  As described above, according to the first embodiment, the following effects can be obtained. The dynamic range can be expanded by dividing the plurality of pixels in the plane into a pixel group that performs long-time exposure and a pixel group that performs short-time exposure in the light flight type distance measuring apparatus 1. Also, within a period in which the light receiving elements of the pixel group performing the long time exposure acquire one distance measurement value by one long time exposure, the light receiving elements of the pixel group performing the short time exposure are subjected to multiple short exposures. The frame rate of the short time exposure can be increased by acquiring the distance measurement value multiple times. Thus, it is possible to appropriately increase the frame rate of the short exposure while appropriately expanding the dynamic range. In particular, it is suitable in the case of an on-vehicle in which at least one of the own apparatus and the target moves.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIG. 13 to FIG. The description of the same parts as those of the first embodiment described above will be omitted, and only different parts will be described. The first embodiment is a single-ended output configuration, while the second embodiment is a differential output configuration. The optical flight distance measuring apparatus 21 includes a signal source 22, a drive circuit 23 (drive means), a light emitting element 24, a control circuit 25 (control means), a light receiving element 26, and a CM (common mode) component removal circuit 27 and a distance measurement value acquisition circuit 28 (distance measurement value acquisition means). The distance measurement value acquisition circuit 28 includes buffers 29 a and 29 b, a difference detection circuit 30, an AD conversion circuit 31, and a digital signal processing circuit 32.

  The signal source 22, the drive circuit 23, the light emitting element 24 and the control circuit 25 are respectively equivalent to the signal source 2, the drive circuit 3, the light emitting element 4 and the control circuit 5 described in the first embodiment. As shown in FIG. 14, the light receiving element 26 has a PD 41, two modulation switches 42a and 42b, and two storage capacitors 43a and 43b. The light receiving element 26 drives the modulation switches 42a and 42b by the control signals TG1 and TG2, distributes the charges generated by the received incident light to the storage capacitors 43a and 43b and stores the signals indicating the charge amount of the charge as the CM component The data is output to the removal circuit 27. Since the control signals TG1 and TG2 are signals synchronized with the modulated light, the charge amount of the charges distributed to and stored in the storage capacitors 43a and 43b changes according to the distance from the own device to the object. Although two storage capacitors 43a and 43b are illustrated in FIG. 14, three or more storage capacitors may be provided.

  The CM component removal circuit 27 prevents the saturation of the pixel due to the charge generated due to the background light, when the background light at a level that can not be ignored is present with respect to the modulated light being emitted. . Various techniques have been disclosed in the prior art as methods of removing the CM component. For example, U.S. Pat. No. 6,919,549 B2, U.S. Pat. No. 102005056774 A1, U.S. Pat. No. 1,622,200 A1 and the like. The difference detection circuit 30 detects the difference between the signals input from the CM component removal circuit 27 via the buffers 29a and 29b, and outputs a signal corresponding to the detected difference to the AD conversion circuit 31. The difference detection circuit 30 is realized by, for example, a differential amplifier.

  The AD conversion circuit 31 converts the signal input from the difference detection circuit 30 from an analog signal into a digital signal, and outputs the digital signal to the digital signal processing circuit 32. The digital signal processing circuit 32 performs digital signal processing on the signal input from the AD conversion circuit 31, and calculates the distance from the own device to the object from the charge amount of the charge distributed and stored in the storage capacitors 43a and 43b. Get the distance measurement value (distance measurement).

  FIG. 15 shows a sequence in the case of performing four-phase distance measurement (driving the light receiving element 26 with four phases) with the duty of the light emission waveform being 50%. The difference detection circuit 30 generates a digital value D1 by repeating the combination of the control signals TG1 and TG2, for example, by repeating the control signals TG1-1 (drive waveform 111) and TG2-1 (drive waveform 121) several tens to several hundreds of thousands of times. . Similarly, the difference detection circuit 30 repeats the control signals TG1-2 (drive waveform 112) and TG2-2 (drive waveform 122) several tens to several hundreds of thousands of times to generate the digital value D2. The difference detection circuit 30 outputs the digital values D1 and D2 as values from which the DC component is removed. Assign “1” when the control signal TG1 is “H” and TG2 is “L” for each digital value D1, D2, and the control signal TG1 is “L” and TG2 is “H” When assigning "-1", it describes. That is, the states of the control signals TG1 and TG2 are uniquely determined depending on whether the value of the waveform Dx is “1” or “−1”. Since Dx is a signal indicating the difference between the two storage capacitors 43a and 43b as described above, the AD conversion circuit 31 outputs the signal on which the operation corresponding to the numerator or denominator of the arithmetic expression (1) described above is performed. Output.

  FIG. 16 shows a timing chart of multiple exposure in the configuration of the operation output of the present invention. In the example of FIG. 16, the pixel group of pixel A performs long exposure by performing the pixel group B of pixel B performs short exposure six times within a period in which the pixel group of pixel A performs one long exposure period. A frame rate of six times that of a group can be realized.

  FIG. 17 shows another sequence of actuation outputs of the present invention, and FIG. 18 shows a timing chart of multiple exposures corresponding to the sequence. In FIG. 15 described above, only the digital values D1 and D2 are generated, but in addition to the digital values D1 and D2, the control signals TG1-3 (drive waveform 113) and TG2-3 (drive waveform 123) are several tens to several The digital value D3 is generated several hundreds of thousands of times repeatedly, and the digital values D4 are generated by repeating the control signals TG1-4 (drive waveform 114) and TG2-4 (drive waveform 124) several tens to several hundreds of thousands of times. In the example of FIG. 18, the pixel group of pixel A performs long exposure by performing the pixel group B of pixel B performs short exposure four times within a period in which the pixel group of pixel A performs one long exposure period. A frame rate of four times that of a group can be realized. In addition, circuit mismatch can be avoided in advance, and robustness can be enhanced.

  FIG. 19 shows still another sequence of the operation output of the present invention, and FIG. 20 shows a timing chart of multiple exposure corresponding to the sequence. The number of phases in the long time exposure and the number of phases in the short time exposure do not have to be the same but may be different. In the example of FIG. 19 and FIG. 20, long-time exposure is driven by six-phase distance measurement, and short-time exposure is driven by four-phase distance measurement. Also, in the examples of FIGS. 19 and 20, in addition to “1” and “−1” for long-time exposure, high-order exposure is performed by inserting “0” indicating a non-integral period which is a period in which the signal is not integrated. It is sensitive to harmonics. That is, when the duty of the light emission waveform is shorter than 50%, the energy of the component of the higher harmonics increases as the duty becomes shorter, and the sensitivity to a predetermined higher harmonic is used for long-time exposure. To effectively utilize the energy of the high-order harmonic components. The digital signal processing circuit 32 linearly combines the component of the fundamental wave and the component of the higher harmonics to calculate the distance, thereby adding the component of the higher harmonics to the distance from only the component of the fundamental wave. Distance error can be reduced more than when calculating. The applicant has filed Japanese Patent Application No. 2014-226069 for the invention for giving sensitivity to such high-order harmonics.

  As described above, according to the second embodiment, not only the single-ended output configuration but also the differential output configuration can provide the same effects as those of the first embodiment described above. The frame rate of the short exposure can be appropriately increased while appropriately expanding Note that the second embodiment is not limited to the configuration in which two pixel groups are divided, and may be configured in three pixel groups as in the first embodiment described above. You may switch by.

(Other embodiments)
The present invention is not limited only to the above-described embodiment, and can be modified or expanded as follows.
It may be applied to uses other than in-vehicle use.
In the present embodiment, the configuration in which the image is divided into two pixel groups and three pixel groups is illustrated, but the configuration may be such that the exposure period is divided into four or more pixel groups different from each other. Also, even when dividing into four or more pixel groups, each pixel group may be switched by time.
A combination of the respective phase numbers of the long exposure and the short exposure in the case of dividing into two pixel groups, and a phase number of each of the long exposure, the medium time and the short exposure in the case of dividing into three pixel groups Any combination may be used. Also, even in the case of dividing into four or more pixel groups, similarly, the combination of the respective phase numbers may be arbitrary.

  In the drawing, 1 and 21 are light flight type distance measuring devices, 3 and 23 are drive circuits (drive means), 4 and 24 are light emitting elements, 5 and 25 are control circuits (control means), 6 and 26 are light receiving elements, 7, 28 is a distance measurement value acquisition circuit (distance measurement value acquisition means).

Claims (13)

A light emitting element (4, 24) for emitting in space a modulated light modulated by a pattern having a repetition period;
Driving means (3, 23) for driving the light emitting element;
A plurality of light receiving elements (6, 26), each of which constitutes an in-plane pixel, and receives incident light including reflected light that the modulated light is reflected by the object;
Control means (5, 25) for controlling accumulation of charges in the plurality of light receiving elements and readout of charges from the plurality of light receiving elements;
Distance measurement value acquisition means (7, 28) for calculating the distance from the own device to the object using the charge read from the plurality of light receiving elements by the control means and acquiring the distance measurement value ,
The control means divides a plurality of pixels in a plane into several pixel groups, and the light receiving elements belonging to one pixel group perform one long-time exposure, and the distance measuring value acquiring means measures the distance measurement value. Within the period in which the light receiving element belonging to the other pixel group carries out a plurality of short-time exposures by storing and reading out electric charges in a plurality of phases within a period in which the distance measurement is performed by the distance measurement value acquisition means An optical flight distance measuring apparatus (1, 21) characterized by controlling driving of a plurality of light receiving elements so that a value is acquired plural times. In the optical flight type distance measuring apparatus according to claim 1,
The control means performs one long-time exposure in which the light receiving elements belonging to one pixel group repeat accumulation of n charges and n readout of charges based on n (n is a natural number of 2 or more) phases. The plurality of light-receiving elements belonging to another pixel group perform one short-time exposure repeatedly repeating accumulation of n charge and readout of n charge based on n phase within a period to be performed An optical flight distance measuring apparatus characterized in that the drive of the light receiving element of the above is controlled. In the optical flight distance measuring apparatus according to claim 2,
The light flight type distance measuring apparatus, wherein the control means controls driving of the plurality of light receiving elements using a driving waveform in which a rectangular waveform with a duty of 50% is shifted by 2π / n. In the optical flight type distance measuring apparatus according to claim 1,
The control means performs one long-time exposure in which the light receiving elements belonging to one pixel group repeat accumulation of n charges and n readout of charges based on n (n is a natural number of 2 or more) phases. Within the time period, m (where m is a natural number of 2 or more, n is a different value from n) light-receiving elements belonging to other pixel groups are accumulated m times based on the phase and m times charge readout A light flight type distance measuring apparatus characterized in that the drive of the plurality of light receiving elements is controlled such that one repetitive short exposure is performed a plurality of times. In the optical flight distance measuring apparatus according to claim 4,
The control means controls driving of the light receiving elements belonging to one pixel group using a driving waveform in which a rectangular waveform with a duty of 50% is shifted by 2π / n, and driving of light receiving elements belonging to the other pixel group An optical flight distance measuring apparatus characterized in that a rectangular waveform with a duty of 50% is controlled using a drive waveform shifted by 2π / m. The optical flight distance measuring apparatus according to any one of claims 1 to 5, wherein
The distance measurement value acquiring means (7) calculates the distance from the own device to the object using the values outputted at a single end from the plurality of light receiving elements (6) to acquire distance measurement values. An optical flight distance measuring apparatus (1) characterized by the above. The optical flight distance measuring apparatus according to any one of claims 1 to 5, wherein
The distance measurement value acquiring means (28) calculates the distance from the own device to the object using the values differentially output from the plurality of light receiving elements (26) to acquire the distance measurement value. An optical flight distance measuring apparatus (21) characterized by the above. In the optical flight distance measuring apparatus according to claim 7,
The control means controls driving of the light receiving elements belonging to the long exposure group such that the light receiving elements belonging to the long exposure group have sensitivity to a predetermined higher harmonic.
The said ranging value acquisition means is characterized by acquiring the ranging value by linearly combining the component of a fundamental wave and the component of a high-order harmonic about the light receiving element which belongs to the pixel group which performs long-time exposure. Optical flight type distance measuring device. The optical flight distance measuring apparatus according to any one of claims 1 to 8,
The control means divides one pixel group into another pixel group, and divides the light receiving elements belonging to one pixel group and the light receiving elements belonging to the other pixel group so as to be arranged in row units of one row interval. An optical flight type distance measuring device characterized by The optical flight distance measuring apparatus according to any one of claims 1 to 8,
The control means divides one pixel group into another pixel group, and divides the light receiving elements belonging to one pixel group and the light receiving elements belonging to the other pixel group into a checkered pattern. Flight type distance measuring device. The optical flight distance measuring apparatus according to any one of claims 1 to 8,
The control means sets the other pixel group to two including the first other pixel group and the second other pixel group, and the light receiving elements belonging to any one pixel group are arranged in a checkered pattern, and the rest A light-flying distance-measuring device, wherein light-receiving elements belonging to each of the two pixel groups are divided so that they are arranged in rows of one row apart in the rest of the checkered pattern. The optical flight distance measuring apparatus according to any one of claims 1 to 8,
The control means divides the other pixel group into two including the first other pixel group and the second other pixel group, and divides all the pixel groups so as to be arranged in all the rows. An optical flight type distance measuring device characterized by The optical flight distance measuring apparatus according to any one of claims 1 to 12.
The light flight type distance measuring apparatus, wherein the control means switches between a period in which a predetermined light receiving element belongs to one pixel group and a period in which another light receiving element belongs to another pixel group.

Images