Distance measuring device and distance measuring program

Abstract

To provide a distance measurement device and a distance measurement program which can correct a distance difference generated between regions when measuring a distance to an object by driving a light emitting element independently in the plurality of regions.SOLUTION: An irradiation optical system 30 shapes light from a light source 20 such that an overlapping part T in which adjacent regions to which light is emitted from a plurality of light emitting sections 24 overlap each other is generated on a measurement object 80 and a 3D sensor 5, determines a deviation amount of the measurement distance in the overlapping part T, and corrects at least one of light emission of the light source 20 and light reception of the 3D sensor 5 so as to eliminate the difference.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a distance measurement device and a distance measurement program. [Background technology]

[0002] Patent Document 1 proposes a distance measurement device that includes a light receiving unit having a plurality of pixels, a reference time measurement unit connected to a reference signal line connected to a specific pixel among the plurality of pixels and measuring a reference time value from a first light emission timing under a first light emission control on the light emitting unit to a light reception timing at the specific pixel, a time measurement unit connected to a main signal line connected to the specific pixel and measuring a predetermined time value from the first light emission timing to the light reception timing, and a correction processing unit that calculates and stores a correction value for the main signal line based on the reference time value and the predetermined time value, and is configured to correct the delay of a signal output from the specific pixel via the main signal line in response to a second light emission control on the light emitting unit based on the stored correction value.

[0003] Specifically, even if light is emitted at the same timing and reflected by an object at the same distance, the distance calculated by each pixel of the sensor array will differ due to physical differences in the signal lines connected to each pixel. Therefore, in order to correct this difference between pixels, it has been proposed to correct the output signal from the sensor so that the output value of one pixel is used as a reference and the output values ​​of the other pixels are adjusted to the reference. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-148682 Summary of the Invention [Problem to be solved by the invention]

[0005] In a light-emitting unit equipped with multiple light-emitting elements, differences in the light-emitting timing of each light-emitting element occur due to external factors such as driving conditions and temperature conditions, individual differences, and changes over time. When such spatial differences in the light-emitting timing of the light-emitting unit occur, if the light-emitting elements are driven independently in multiple regions to measure the distance to an object, differences in distance depending on the differences in light-emitting timing between the regions will occur.

[0006] Therefore, the object is to provide a distance measurement device and a distance measurement program that can correct the distance difference that occurs between areas when measuring the distance to an object by driving light-emitting elements independently in multiple areas. [Means for solving the problem]

[0007] In order to achieve the above object, the distance measuring device of the first aspect includes: a light emitting unit having a plurality of light emitting elements and capable of being driven independently in a plurality of regions; a light receiving unit having a plurality of light receiving elements that receive reflected light of light emitted from the light emitting unit toward an object; a shaping unit that causes overlapping portions to occur in adjacent regions of the light receiving unit where the received reflected light overlaps; a measuring unit that measures the distance to the object from the difference between the waveform received by the light receiving unit and the waveform of the light emitting unit; and a correction unit that corrects the distance difference between the adjacent regions of the reflected light using the distance measurement value in the overlapping portion measured by the measuring unit.

[0008] The distance measurement device of the second aspect is the distance measurement device of the first aspect, wherein the shaping unit shapes the light emitted from the light emitting unit so that overlapping areas occur in the areas where the reflected light is received on the light receiving unit.

[0009] A distance measurement device according to a third aspect is a distance measurement device according to the second aspect, wherein the shaping unit includes a lens, and the overlapping portion is generated by shifting the position of the focal length of the lens from the position of the light emitting unit.

[0010] A distance measurement device according to a fourth aspect is a distance measurement device according to the third aspect, wherein the lens includes a plurality of lenses, and the overlapping portion is generated by shifting the position of the composite focal length of the plurality of lenses from the position of the light emitting portion.

[0011] A distance measurement device according to a fifth aspect is a distance measurement device according to the third or fourth aspect, in which the shaping unit generates the overlapping portion by shifting the position of the light emitting unit from the position of the focal length toward the lens.

[0012] A distance measurement device according to a sixth aspect is the distance measurement device according to the first aspect, wherein the shaping section generates the overlapping portion in a part of the region where the received reflected light is adjacent to each other.

[0013] A distance measuring device according to a seventh aspect is a distance measuring device according to the sixth aspect, wherein the shaping unit generates the overlapping portion by light emitted from the light-emitting element in a part of the adjacent areas where the reflected light is received and at a position away from the connection between the light-emitting unit and a wiring unit that sends signals to each area of ​​the light-emitting unit.

[0014] The distance measuring device of the eighth aspect is the distance measuring device of the first aspect, wherein the shaping unit generates the overlapping portion by causing adjacent areas to be received by the light receiving area of ​​the light receiving unit, which regards the adjacent areas as one piece of data, and the correction unit corrects the distance difference by matching the distance measurement value in one of the areas received by the light receiving area to the distance measurement value in the other area.

[0015] A distance measurement device according to a ninth aspect is the distance measurement device according to any one of the first to eighth aspects, further comprising a distance reference unit for measuring a distance reference within the device.

[0016] A distance measurement device according to a tenth aspect is the distance measurement device according to the ninth aspect, wherein the distance reference portion is provided in a partial area of ​​a cover glass.

[0017] A distance measurement device according to an eleventh aspect is a distance measurement device according to any one of the first to tenth aspects, wherein the correction unit corrects the distance difference by correcting at least one of the light emitted by the light emitting unit and the light received by the light receiving unit.

[0018] A distance measurement device according to a twelfth aspect further includes an abnormality identifying section that identifies an area where an abnormality is likely to occur, and the correction section makes correction based on the area where no abnormality is present.

[0019] A distance measurement device according to a thirteenth aspect is a distance measurement device according to any one of the first to twelfth aspects, in which when there are multiple light-emitting elements corresponding to an overlapping portion, the correction unit calculates and corrects an average value as the distance measurement value in the overlapping portion.

[0020] A distance measurement program according to a fourteenth aspect causes a computer to function as the measurement unit and the correction unit of the distance measurement device. [Effects of the Invention]

[0021] According to the first aspect, it is possible to provide a distance measurement device that can correct a difference in distance that occurs between a plurality of areas when measuring the distance to an object by driving light emitting elements independently in the areas.

[0022] According to the second aspect, it is possible to generate an overlapping portion on the light receiving portion without using a special light source.

[0023] According to the third aspect, it is possible to generate the overlapping portion more easily than when a special light source is used.

[0024] According to the fourth aspect, it is possible to generate an overlapping portion with higher accuracy than when an overlapping portion is generated using a single lens.

[0025] According to the fifth aspect, it is possible to make the device more compact than when the position of the light emitting unit is shifted from the position of the focal length of the lens to the opposite side of the lens.

[0026] According to the sixth aspect, it is possible to derive the difference in distance that occurs between a plurality of regions when the light emitting elements are driven independently in the regions to measure the distance to the object.

[0027] According to the seventh aspect, it is possible to correct the error at a position where it becomes larger than when an overlapping portion is generated by light emitted from a transmitting element located closer to the joint portion.

[0028] According to the eighth aspect, it is possible to derive the difference in distance that occurs between a plurality of regions when the light emitting elements are driven independently in the regions to measure the distance to the object.

[0029] According to the ninth aspect, more accurate correction is possible than when there is no distance reference.

[0030] According to the tenth aspect, it is possible to provide a distance reference unit in an existing configuration.

[0031] According to the eleventh aspect, it is possible to correct a difference in distance that occurs between a plurality of areas when light-emitting elements are driven independently in the areas to measure the distance to the object.

[0032] According to the twelfth aspect, it is possible to perform correction more accurately than when correction is performed based on an arbitrary region.

[0033] According to the thirteenth aspect, it is possible to make corrections taking into consideration errors of a plurality of light emitting elements corresponding to the overlapping portion.

[0034] According to the fourteenth aspect, it is possible to provide a distance measurement program capable of correcting a difference in distance that occurs between a plurality of areas when measuring the distance to an object by driving light emitting elements independently in the areas. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a schematic diagram illustrating the configuration of a measurement device according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing the main configuration of an electrical system of the measurement device. [Figure 3] FIG. [Figure 4] FIG. 10 is a diagram for explaining light-emitting sections. [Figure 5] FIG. 2 is a circuit diagram of the measurement device. [Figure 6] FIG. 2 is a plan view of a 3D sensor. [Figure 7] FIG. 2(a) is a diagram showing an optical device according to a first embodiment, and FIG. 2(b) is a diagram showing a light emitting unit, a focal length of a lens, and the position of the light emitting unit. [Figure 8] FIG. 10 is a diagram illustrating conditions under which an overlapping portion occurs. [Figure 9] 4 is a flowchart showing the flow of a calibration process executed by a control unit of the measurement device according to the first embodiment. [Figure 10] 10A and 10B are diagrams illustrating an example of criteria and measurement order for light emitting sections. [Figure 11] FIG. 10 is a diagram illustrating an optical device according to a second embodiment. [Figure 12] FIG. 10 is a diagram showing an example in an optical device according to the third embodiment in which an overlapping portion is generated so that some VCSELs in adjacent light-emitting sections overlap (light irradiated from the VCSEL closer to the gate electrode overlaps). [Figure 13] FIG. 10 is a diagram showing an example in an optical device according to the third embodiment in which an overlapping portion is generated so that some VCSELs in adjacent light-emitting sections overlap (light irradiated from VCSELs farther from the gate electrode overlaps). [Figure 14] 10A and 10B are diagrams illustrating an example in which light emitted from VCSELs in adjacent portions at a corner in each light-emitting section is overlapped in the optical device according to the third embodiment. [Figure 15] FIG. 10 is a diagram illustrating an optical device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, an example of an embodiment of the disclosed technology will be described in detail with reference to the drawings. First Embodiment Among measurement devices that measure the three-dimensional shape of a measurement target, there are devices that measure the three-dimensional shape based on the so-called ToF (Time of Flight) method, which relies on the time of flight of light. The ToF method measures the time from when light is emitted from a light source of the measurement device to when the irradiated light is reflected by the measurement target and received by a three-dimensional sensor (hereinafter referred to as a 3D sensor) of the measurement device, and determines the three-dimensional shape by measuring the distance to the measurement target. Note that an object whose three-dimensional shape is being measured is referred to as a measurement target. A measurement target corresponds to an example of a target. Measuring a three-dimensional shape is sometimes referred to as three-dimensional measurement, 3D measurement, or 3D sensing.

[0037] The ToF method includes a direct method and a phase difference method (indirect method). The direct method is a method in which pulsed light that is emitted for a very short time is irradiated onto the object to be measured, and the time it takes for the light to return is measured. The phase difference method is a method in which pulsed light is periodically flashed, and the time delay when multiple pulsed light beams travel back and forth between the object to be measured and the object is detected as a phase difference. In this embodiment, a case in which a three-dimensional shape is measured using the phase difference method will be described.

[0038] Such measurement devices are installed in portable information processing devices and the like, and are used for, for example, facial authentication of users attempting to access the devices. Conventionally, methods for authenticating users using passwords, fingerprints, irises, etc. have been used in portable information processing devices. In recent years, there has been a demand for authentication methods with higher security. Therefore, portable information processing devices have begun to be equipped with measurement devices that measure three-dimensional shapes. That is, a three-dimensional image of the face of the accessing user is acquired, and it is determined whether or not the access is permitted. Only when the user is authenticated as being authorized to access, is the device (portable information processing device) permitted to be used.

[0039] Such a measuring device is also applicable to cases where the three-dimensional shape of an object to be measured is continuously measured, such as in augmented reality (AR).

[0040] The configurations, functions, methods, etc. described in the present embodiment below can be applied not only to face recognition and augmented reality, but also to measuring the three-dimensional shapes of other measurement objects.

[0041] (Measuring device 1) FIG. 1 is a block diagram illustrating an example of the configuration of a measurement apparatus 1 that measures a three-dimensional shape.

[0042] The measurement device 1 includes an optical device 3 and a control unit 8. The control unit 8 controls the optical device 3. The control unit 8 includes a three-dimensional shape specifying unit 81 that specifies the three-dimensional shape of the object to be measured. The measurement device 1 is an example of a distance measurement device. The control unit 8 is an example of a measurement unit and a correction unit.

[0043] Fig. 2 is a block diagram showing the hardware configuration of the control unit 8. As shown in Fig. 2, the control unit 8 includes a controller 12. The controller 12 includes a central processing unit (CPU) 12A, a read-only memory (ROM) 12B, a random access memory (RAM) 12C, and an input / output interface (I / O) 12D. The CPU 12A, the ROM 12B, the RAM 12C, and the I / O 12D are connected to each other via a system bus 12E. The system bus 12E includes a control bus, an address bus, and a data bus.

[0044] Furthermore, a communication unit 14 and a storage unit 16 are connected to the I / O 12D.

[0045] The communication unit 14 is an interface for performing data communication with an external device.

[0046] The storage unit 16 is configured with a nonvolatile rewritable memory such as a flash ROM, and stores a calibration program 16A, a measurement program 16B, a partition correspondence table 16C, and other programs, which will be described later. The CPU 12A reads the calibration program 16A stored in the storage unit 16 into the RAM 12C and executes it, thereby calibrating the optical device 3. Furthermore, the CPU 12A reads the measurement program 16B stored in the storage unit 16 into the RAM 12C and executes it, thereby configuring a three-dimensional shape specification unit 81, which specifies the three-dimensional shape of the object to be measured. The calibration program 16A is an example of a distance measurement program.

[0047] The optical device 3 includes a light-emitting device 4 and a 3D sensor 5. The light-emitting device 4 includes a wiring substrate 10, a heat dissipation base 100, a light source 20, a drive unit 50, a holding unit 60, and capacitors 70A and 70B. The light-emitting device 4 may further include passive elements such as a resistive element 6 and a capacitor 7 to operate the drive unit 50. Here, the light-emitting device 4 includes two resistive elements 6 and two capacitors 7. Although two capacitors 70A and 70B are shown, one may be included. When the capacitors 70A and 70B are not distinguished, they are referred to as capacitors 70. Furthermore, the resistive element 6 and the capacitor 7 may each be one or more. Here, electrical components such as the 3D sensor 5, the resistive element 6, and the capacitor 7, other than the light source 20, the drive unit 50, and the capacitor 70, may be referred to as circuit components without distinction. The capacitor may also be referred to as a condenser. The light source 20 is an example of a light-emitting unit, and the 3D sensor 5 is an example of a light-receiving unit.

[0048] The heat dissipation base 100, the drive unit 50, the resistive element 6, and the capacitor 7 of the light emitting device 4 are provided on the surface of the wiring substrate 10. Although the 3D sensor 5 is not provided on the surface of the wiring substrate 10 in FIG. 1, it may be provided on the surface of the wiring substrate 10.

[0049] The light source 20, the capacitors 70A and 70B, and the holder 60 are provided on the surface of the heat dissipation base material 100. Here, the surface refers to the front side of the paper in FIG. 1. More specifically, in the wiring board 10, the side on which the heat dissipation base material 100 is provided is referred to as the surface, front side, or front side. In addition, in the heat dissipation base material 100, the side on which the light source 20 is provided is referred to as the surface, front side, or front side.

[0050] The light source 20 is configured as a light-emitting element array in which a plurality of light-emitting elements are arranged two-dimensionally (see FIG. 3 described later). One example of the light-emitting element is a vertical-cavity surface-emitting laser (VCSEL). In the following, the light-emitting element will be described as a vertical-cavity surface-emitting laser (VCSEL). Since the light source 20 is provided on the surface of the heat-dissipating base 100, the light source 20 emits light perpendicular to the surface of the heat-dissipating base 100, in a direction away from the heat-dissipating base 100. In other words, the light-emitting element array is a surface-emitting laser array. Note that the plurality of light-emitting elements in the light source 20 are arranged two-dimensionally, and the surface of the light source 20 that emits light may be referred to as an emission surface.

[0051] An irradiation optical system 30, which is an example of a shaping unit, is provided on the light emission side of the light source 20, and the light emitted from the light source 20 is irradiated onto the object to be measured via the irradiation optical system 30. The irradiation optical system 30 is composed of, for example, one or more lenses. Note that the irradiation optical system 30 may emit diffused light.

[0052] When performing three-dimensional measurement using the ToF method, the light source 20 is required to emit pulsed light (hereinafter referred to as emitted light pulses) at, for example, 100 MHz or higher and with a rise time of 1 ns or less, using the driving unit 50. In the case of facial recognition, for example, the distance over which the light is irradiated is approximately 10 cm to 1 m. The range over which the light is irradiated is approximately 1 m square. The distance over which the light is irradiated is referred to as the measurement distance, and the range over which the light is irradiated is referred to as the irradiation range or measurement range. A surface virtually located within the irradiation range or measurement range is referred to as the irradiation surface. In cases other than facial recognition, the measurement distance to the object to be measured and the irradiation range for the object to be measured may be other than those described above.

[0053] The 3D sensor 5 includes a plurality of light receiving elements, for example, 640 x 480 light receiving elements, and outputs a signal corresponding to the time from when light is emitted from the light source 20 to when the light is received by the 3D sensor 5. The 3D sensor 5 also includes a condensing optical system 31, through which light is incident.

[0054] For example, each light-receiving element of the 3D sensor 5 receives pulsed light (hereinafter referred to as a received light pulse) reflected from the object to be measured in response to an emitted light pulse from the light source 20, and accumulates a charge corresponding to the time it takes for the light to be received. The 3D sensor 5 is configured as a CMOS device, with each light-receiving element having two gates and a corresponding charge storage section. Alternately applying pulses to the two gates transfers generated photoelectrons to one of the two charge storage sections at high speed. Charges corresponding to the phase difference between the emitted light pulse and the received light pulse are accumulated in the two charge storage sections. The 3D sensor 5 then outputs a digital value corresponding to the phase difference between the emitted light pulse and the received light pulse as a signal for each light-receiving element via an AD converter. That is, the 3D sensor 5 outputs a signal corresponding to the time from when light is emitted from the light source 20 to when the light is received by the 3D sensor 5. In other words, the 3D sensor 5 acquires a signal corresponding to the three-dimensional shape of the object to be measured. The AD converter may be provided in the 3D sensor 5 or may be provided outside the 3D sensor 5.

[0055] As described above, the measurement device 1 diffuses the light emitted by the light source 20 and irradiates the object to be measured, and receives the light reflected from the object to be measured by the 3D sensor 5. In this way, the measurement device 1 measures the three-dimensional shape of the object to be measured.

[0056] First, the light source 20, the irradiation optical system 30, the drive unit 50, and the capacitors 70A and 70B that constitute the light emitting device 4 will be described.

[0057] (Configuration of light source 20) 3 is a plan view of light source 20. Light source 20 is configured by arranging multiple VCSELs in a two-dimensional array. In other words, light source 20 is configured as a light-emitting element array using VCSELs as light-emitting elements. The rightward direction on the paper surface is defined as the x-direction, and the upward direction on the paper surface is defined as the y-direction.

[0058] The direction perpendicular to the x and y directions is defined as the z direction. The front surface of light source 20 refers to the front side of the paper, i.e., the surface on the +z direction side, and the back surface of light source 20 refers to the back side of the paper, i.e., the surface on the -z direction side. The plan view of light source 20 is a view of light source 20 as seen from the front surface side.

[0059] To explain further, in the light source 20, the side on which an epitaxial layer that functions as a light emitting layer (an active region, which will be described later) is formed is referred to as the surface, front side, or front surface side of the light source 20.

[0060] A VCSEL is a light-emitting element that has an active region serving as a light-emitting region between a lower multilayer reflector and an upper multilayer reflector stacked on a semiconductor substrate 200, and emits laser light perpendicular to the surface. For this reason, VCSELs can be more easily formed into a two-dimensional array than edge-emitting lasers. The number of VCSELs included in the light source 20 is, for example, 100 to 1000. The multiple VCSELs are connected in parallel and driven in parallel. The number of VCSELs listed above is an example, and may be set according to the measurement distance and irradiation range.

[0061] The light source 20 is driven independently in multiple regions. For example, as shown in FIG. 4, it is divided into multiple light-emitting sections 24, and each light-emitting section is driven. In the example of FIG. 4, as shown by the dashed lines, there are 12 light-emitting sections 24 arranged in a 4×3 pattern. 11 ~24 34 However, the number of light-emitting sections is not limited to this. When no particular distinction is made between the light-emitting sections, they are simply referred to as light-emitting sections 24. In the example of Fig. 4, one light-emitting section 24 includes 16 VCSELs, but the number of VCSELs included in one light-emitting section 24 is not limited to this, and it is sufficient that one or more VCSELs are included.

[0062] An anode electrode 218 (see FIG. 5) common to the multiple VCSELs is provided on the front surface of the light source 20. A cathode electrode 214 (see FIG. 5) is provided on the back surface of the light source 20. In other words, the multiple VCSELs are connected in parallel. By driving the multiple VCSELs connected in parallel, light with a higher intensity is emitted compared to when the VCSELs are driven individually.

[0063] Here, the shape of light source 20 when viewed from the front side (referred to as a planar shape, the same applies below) is rectangular. The side surface on the -y direction side is referred to as side surface 21A, the side surface on the +y direction side is referred to as side surface 21B, the side surface on the -x direction side is referred to as side surface 22A, and the side surface on the +x direction side is referred to as side surface 22B. Side surface 21A and side surface 21B face each other. Side surface 22A and side surface 22B connect side surface 21A and side surface 21B, respectively, and face each other.

[0064] The center of the planar shape of the light source 20, that is, the center in the x and y directions, is defined as a center Ov.

[0065] (Driver 50 and capacitors 70A and 70B) If it is desired to drive the light source 20 at higher speed, low-side driving is preferable. Low-side driving refers to a configuration in which a driving element such as a MOS transistor is located downstream of the current path of a driving target such as a VCSEL. Conversely, a configuration in which a driving element is located upstream is called high-side driving.

[0066] FIG. 5 is a diagram showing an example of an equivalent circuit when the light source 20 is driven by low-side driving. FIG. 5 shows the VCSEL of the light source 20, the driving unit 50, the capacitors 70A and 70B, and the power supply 82. The power supply 82 is provided in the control unit 8 shown in FIG. 1. The power supply 82 generates a DC voltage with the positive side serving as a power supply potential and the negative side serving as a reference potential. The power supply potential is supplied to a power supply line 83, and the reference potential is supplied to a reference line 84. The reference potential may be a ground potential (sometimes referred to as GND, and represented as [G] in FIG. 5).

[0067] As described above, the light source 20 is configured by connecting a plurality of VCSELs in parallel. The anode electrode 218 of the VCSEL (see FIG. 3, denoted as [A] in FIG. 5) is connected to the power line 83.

[0068] As described above, the light source 20 is divided into a plurality of light-emitting sections 24, and the control unit 8 drives a VCSEL for each light-emitting section 24. Note that in Fig. 5, only one light-emitting section 24 is shown with three VCSELs, and the other VCSELs and light-emitting sections are not shown.

[0069] 5, a switch element SW is provided between each VCSEL and a power supply line 83, and each switch element SW is simultaneously turned on and off in response to a command from the control unit 8. As a result, the VCSELs included in one light-emitting section 24 are controlled to emit light or not emit light at the same timing.

[0070] The driving unit 50 includes an n-channel MOS transistor 51 and a signal generating circuit 52 that turns the MOS transistor 51 on and off. The drain (denoted as [D] in FIG. 5) of the MOS transistor 51 is connected to the cathode electrode 214 of the VCSEL (see FIG. 3; denoted as [K] in FIG. 5). The source (denoted as [S] in FIG. 5) of the MOS transistor 51 is connected to a reference line 84. The gate of the MOS transistor 51 is connected to the signal generating circuit 52. In other words, the VCSEL and the MOS transistor 51 of the driving unit 50 are connected in series between a power supply line 83 and a reference line 84. Under the control of the control unit 8, the signal generating circuit 52 generates an "H level" signal that turns the MOS transistor 51 on and an "L level" signal that turns the MOS transistor 51 off.

[0071] One terminal of each of the capacitors 70A and 70B is connected to a power supply line 83, and the other terminal is connected to a reference line 84. Here, when there are multiple capacitors 70, the multiple capacitors 70 are connected in parallel. That is, in FIG. 5, the capacitors 70 are two capacitors 70A and 70B. The capacitors 70 are, for example, electrolytic capacitors or ceramic capacitors.

[0072] Next, a method for driving the light source 20, which is low-side driving, will be described.

[0073] First, the control unit 8 turns on the switch element SW of the light-emitting section 24 in which the VCSEL is desired to emit light, and turns off the switch element SW of the light-emitting section 24 in which the VCSEL is not desired to emit light.

[0074] The following describes how the VCSEL included in the light-emitting section 24 is driven when the switch element SW is turned on.

[0075] First, assume that the signal generated by the signal generating circuit 52 in the driver 50 is at "L level." In this case, the MOS transistor 51 is in the off state. In other words, no current flows between the source ([S] in FIG. 5) and drain ([D] in FIG. 5) of the MOS transistor 51. Therefore, no current flows through the VCSEL connected in series with the MOS transistor 51. In other words, the VCSEL does not emit light.

[0076] At this time, capacitors 70A and 70B are connected to a power supply 82, and one terminal of capacitors 70A and 70B connected to a power supply line 83 is at the power supply potential, and the other terminal connected to a reference line 84 is at the reference potential. Therefore, a current flows (charge is supplied) from the power supply 82 to charge capacitors 70A and 70B.

[0077] Next, when the signal generated by the signal generating circuit 52 in the driver 50 goes to "H level," the MOS transistor 51 transitions from an OFF state to an ON state. This forms a closed loop with the capacitors 70A and 70B and the series-connected MOS transistor 51 and VCSEL, and the charge stored in the capacitors 70A and 70B is supplied to the series-connected MOS transistor 51 and VCSEL. This means that a drive current flows through the VCSEL, causing it to emit light. This closed loop is the drive circuit that drives the light source 20.

[0078] Then, when the signal generated by the signal generating circuit 52 in the driving unit 50 goes low again, the MOS transistor 51 transitions from the on state to the off state. As a result, the closed loop (driving circuit) between the capacitors 70A, 70B and the series-connected MOS transistor 51 and VCSEL becomes an open loop, and no driving current flows to the VCSEL. This causes the VCSEL to stop emitting light. Then, the capacitors 70A, 70B are charged by the supply of electric charge from the power supply 82.

[0079] As described above, each time the signal output by the signal generating circuit 52 transitions between "H level" and "L level," the MOS transistor 51 repeatedly turns on and off, causing the VCSEL to repeatedly emit and not emit light. The repeated on and off of the MOS transistor 51 is sometimes called switching.

[0080] On the other hand, the 3D sensor 5 includes a plurality of light receiving elements PD, as shown in FIG. 6. In this embodiment, the 3D sensor 5 is divided into a plurality of light receiving sections 26, and the irradiation optical system 30 shapes the light emitted from the light source 20 and irradiated from each light emitting section 24 so that an overlapping portion T (see FIG. 7(a)) where adjacent light receiving sections 26 overlap is generated. The light receiving section 26 includes one or more light receiving elements PD. In the example of FIG. 6, one light receiving section 26 includes 16 light receiving elements PD, but the number of light receiving elements PD is not limited to this. Note that, for convenience of explanation, in the example of FIG. 6, the 3D sensor 5 is divided into 4×3 light receiving sections 26, similar to the light emitting sections 24. 11 ~26 34 However, the light receiving sections may be divided into a number different from that of the light emitting sections 24. When the light receiving sections are not particularly distinguished, they will be simply referred to as light receiving sections 26.

[0081] In this embodiment, it is assumed that a light-receiving section 26 to which a light-receiving element PD that receives direct light belongs when all the VCSELs belonging to the light-emitting section 24 are made to emit light is specified in advance for each light-emitting section 24. The correspondence between the light-emitting section 24 and the light-receiving section 26 is stored in advance in the storage unit 16 as a section correspondence table 16C (see FIG. 2).

[0082] The section correspondence table 16C is calculated from the amount of light received by each light receiving section 26 when each light emitting section 24 is individually illuminated with light toward a predetermined object to be measured in a state where no obstacles or the like are present.

[0083] The light-emitting sections 24 and the light-receiving sections 26 may correspond to each other in one-to-one, many-to-one, one-to-many, or many-to-many relationships, but in this embodiment, for the sake of convenience, they are assumed to correspond to each other in one-to-one relationship.

[0084] In this embodiment, as shown in FIG. 7A, light emitted from the light source 20 is irradiated onto the object 80 via the irradiation optical system 30, reflected by the object 80, and incident on the 3D sensor 5 via the condensing optical system 31. The irradiation optical system 30 shapes the light from the light source 20 so that adjacent areas emitted from the multiple light-emitting sections 24 overlap on the object 80 and the 3D sensor 5. Therefore, the light source 20 is driven for each light-emitting section 24, and although adjacent light-emitting sections 24 do not overlap, the light from the light source 20 is shaped by the irradiation optical system 30 and irradiated onto the object 80 so that adjacent areas overlap in the areas irradiated from the light-emitting sections 24. Therefore, on the object 80, as shown in FIG. 7A, adjacent areas overlap in the areas corresponding to each light-emitting section 24, generating overlapping areas T. The light is then reflected by the object 80 and incident on the 3D sensor 5, and overlapping areas T are also generated between adjacent light-receiving sections 26 on the 3D sensor 5. 7(a), the overlapping portion T of the regions 5 to 7 on the 3D sensor 5 is indicated by hatching. Note that the correspondence between the overlapping portion T and the light receiving element PD is stored in advance in the storage unit 16, including the correspondence relationship between the overlapping portion T and the light receiving element PD in a partition correspondence table 16C.

[0085] In FIG. 7(b), the irradiation optical system 30 generates an overlapping portion T by, for example, shifting the focal length position of the lens from the position of the light emitting unit (light source 20). The lens may be a plurality of lenses, and in the case of a plurality of lenses, the overlapping portion T is generated by shifting the combined focal length of the plurality of lenses from the position of the light emitting unit. When shifting the position of the light emitting unit from the focal length position of the lens, it may be shifted farther from the lens, but shifting it closer to the lens is preferable because it makes the device more compact.

[0086] As shown in FIG. 8, the overlapping portion T occurs when the beam spacing Δ on the irradiated surface and the beam divergence σ on the irradiated surface are approximately equal (the integrated intensity of each beam within the region is uniform) or when the beam spacing Δ on the irradiated surface is greater than the beam divergence σ on the irradiated surface (the integrated intensity of each beam within the region has a distribution). On the other hand, when the beam spacing Δ on the irradiated surface is greater than the beam divergence σ on the irradiated surface (for example, in FIG. 7(b) , the distance between the light-emitting element and the lens is equal to the lens focal length (σ approaches 0)), the overlapping portion T does not occur. Therefore, the beam spacing Δ and the beam divergence σ can be set to satisfy the conditions for the overlapping portion T. For example, the beam divergence σ on the irradiated surface is adjusted by the far field pattern (FFP) of the light source 20 and the beam divergence, which is determined by the positional relationship between the lens focal length and the light-emitting element. On the other hand, the beam spacing Δ on the irradiated surface is adjusted by the optical system magnification, which is determined by the element spacing of the light source 20 and the positional relationship between the lens focal length and the light-emitting element. Here, the profile of the beam intensity I of each beam depending on the illuminance irradiation surface position (x) is calculated as I=e^(-(x-Δ)^2 / σ^2), where Δ is the beam spacing on the irradiation surface and σ is the beam spread on the irradiation surface.

[0087] In addition, the irradiation optical system 30 may be configured so that the light irradiated from the light source 20 onto the object to be measured 80 is uniform light for each light-emitting section, or may be configured to irradiate the light so that it is point-irradiated even on the object to be measured 80.

[0088] In the light source 20 equipped with multiple VCSELs as in this embodiment, deviations occur in the light emission timing of each VCSEL due to external factors such as driving conditions and temperature conditions, individual differences, and changes over time. Therefore, in this embodiment, the deviation amount of the measured distance in the overlapping portion T is determined, and at least one of the light emission of the light source 20 and the light reception of the 3D sensor 5 is corrected to eliminate the difference. For example, in the light-emitting section 24 21 The light receiving section 26 when 21 The measured distance calculated from the light receiving result of the overlapping part T in the 22 The light receiving section 26 when 21The amount of deviation is determined by comparing the measured distance obtained from the light reception results of the overlapping portion T with the measured distance obtained from the overlapping portion T, and a correction value is calculated from the amount of deviation. By determining the amount of deviation for each overlapping portion T in the same way, a correction value for correcting the deviation in the light emission timing of each VCSEL can be obtained.

[0089] Next, the operation of the measurement device 1 according to this embodiment will be described. Fig. 9 is a flowchart showing the flow of calibration processing executed by the control unit 8 of the measurement device 1 according to this embodiment. The measurement processing shown in Fig. 9 is executed by the CPU 12A reading the calibration program 16A stored in the storage unit 16.

[0090] In step 100, the CPU 12A illuminates the predetermined light-emitting section 24, and then proceeds to step 102. That is, the MOS transistor 51 of the driver 50 is turned on and the switch element SW is turned on so that the VCSEL in the predetermined light-emitting section 24 of the light source 20 emits light. This causes the VCSEL in the predetermined light-emitting section 24 to emit light. As an example of the predetermined light-emitting section 24, the light-emitting section 24 in the upper left of FIG. 4 is 11 emits light.

[0091] In step 102, the CPU 12A measures the distance of the overlapping portion T and proceeds to step 104. That is, by referring to the section correspondence table 16C, the CPU 12A acquires from the 3D sensor 5 the amount of light received by the light-receiving element PD belonging to the overlapping portion T of the light-receiving section 26 corresponding to the light-emitting section 24, and measures the distance to the object to be measured by the phase difference method described above. For example, 11 When the light is emitted, the light receiving section 26 11 and light receiving section 26 12 The distance is measured based on the amount of light received by the light receiving element PD in the overlapping portion T.

[0092] In step 104, the CPU 12A turns off the light-emitting section 24 that is currently emitting light, turns on the adjacent light-emitting section 24, and then proceeds to step 106. That is, the MOS transistor 51 of the drive unit 50 is turned on and the switch element SW is turned on so that the VCSEL in the light-emitting section 24 adjacent to the predetermined light-emitting section 24 of the light source 20 emits light. This causes the VCSEL in the light-emitting section 24 adjacent to the predetermined light-emitting section 24 to emit light.

[0093] In step 106, the CPU 12A measures the distance of the overlapping portion T and proceeds to step 108. That is, by referring to the section correspondence table 16C, the CPU 12A acquires from the 3D sensor 5 the amount of light received by the light-receiving element PD belonging to the overlapping portion T of the light-receiving section 26 corresponding to the light-emitting section 24, and measures the distance to the object to be measured using the phase difference method described above. Note that the overlapping portion T is the overlapping portion T corresponding to step 102.

[0094] In step 108, the CPU 12A calculates the difference in the measurement values ​​of the overlapping portion T as a correction value, and proceeds to step 110. This obtains a correction value that corrects the distance difference that occurs between adjacent light-emitting sections 24. The correction value may be a correction value that corrects the light emission of the light source 20, a correction value that corrects the light reception of the 3D sensor 5, or a correction value that corrects both.

[0095] In step 110, the CPU 12A determines whether distance measurement for all light emitting sections has been completed. If the determination is negative, the process proceeds to step 112, and if the determination is affirmative, the series of processes ends.

[0096] In step 112, the CPU 12A corrects the light-emitting section 24 that is emitting light, and returns to step 102 to repeat the above-described process. That is, the CPU 12A corrects the light-receiving result of the light-receiving element PD of the light-receiving section 26 that corresponds to the light-emitting section 24 that is emitting light, and / or the light emission amount of the VCSEL of that light-emitting section 24, using a correction value.

[0097] 9, for example, by performing the above process in order from a predetermined reference light-emitting section 24 in the direction of the arrow as shown in Fig. 10, correction values ​​that match the reference can be obtained. Furthermore, the reference and the measurement order are not limited to the order shown in Fig. 10, and another position may be used as the reference, or another measurement order may be applied.

[0098] Second Embodiment Next, a second embodiment will be described. The same parts as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted. Fig. 11 is a diagram showing an optical device according to the second embodiment.

[0099] In the first embodiment, the relative error between sections is eliminated, but the deviation from the true value cannot be corrected. Therefore, in the second embodiment, a distance reference unit 40 is provided in the device as shown in FIG.

[0100] Distance reference unit 40 is provided on a cover glass by increasing the reflectance of a part of the outermost periphery of the cover glass provided at a position where the distance is known. Alternatively, a member with high reflectance may be provided on the optical path of light source 20 separately from the cover glass.

[0101] Furthermore, if the distance reference unit 40 is provided on the optical path of one light-emitting section 24, that section becomes the reference, and by performing processing similar to that in the first embodiment, a correction value that corrects the deviation from the true value is calculated.

[0102] <Third embodiment> Next, a third embodiment will be described. Note that the same parts as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0103] In the above embodiment, an example was described in which the overlapping portion T overlaps all of the VCSELs of adjacent light-emitting sections 24, but the overlapping portion T does not need to overlap all of the VCSELs of adjacent light-emitting sections 24, and may only overlap partially.

[0104] In the third embodiment, an example will be described in which an overlapping portion T is generated so that some VCSELs of adjacent light-emitting sections 24 overlap. Fig. 12 is a diagram showing an example in which an overlapping portion T is generated so that some VCSELs of adjacent light-emitting sections 24 overlap. Note that the black circles in Fig. 12 indicate the beam profile of the VCSEL on the irradiation surface.

[0105] As shown in Figure 12, when light-emitting sections 24 are formed by arranging VCSELs in a row, it is possible to overlap the light emitted from some of the VCSELs, such as the VCSELs on one end, rather than overlapping all of the VCSELs in adjacent sections. The example in Figure 12 shows a beam profile on the irradiation surface, with the light emitted from one VCSEL on the gate electrode 90 side overlapping. The gate electrode 90 corresponds to the connection between the wiring that sends signals to each light-emitting section 24 and the light source 20.

[0106] When overlapping only one VCSEL as shown in Figure 12, it is preferable to overlap the light emitted from the VCSEL farthest from the gate electrode 90 as shown in Figure 13, rather than the VCSEL on the gate electrode 90 side. In other words, the amount of deviation in light emission timing is more likely to be greater at the VCSEL farther from the gate electrode 90 than at the VCSEL closer to the gate electrode 90, and when correcting the light emission timing, it is easier to adjust it based on the later VCSEL. Note that although Figures 12 and 13 show an example in which light emitted from one VCSEL is overlapped, light emitted from two or more VCSELs may also be overlapped.

[0107] Furthermore, in cases where VCSELs are two-dimensionally arranged in the light-emitting sections 24 as in the above embodiment, the light emitted from the VCSELs in adjacent portions at the corners of each light-emitting section 24 may be overlapped, as shown in Fig. 14. In the example of Fig. 14, the beam profile of regions 1, 3, 4, and 6 is adjusted so that the light emitted from one VCSEL at the corner overlaps, and the beam profile of regions 2 and 4 is adjusted so that the light emitted from two VCSELs at the corners overlaps.

[0108] Here, a method for generating the overlapping portion T by overlapping only the light beams emitted from some of the VCSELs, as in the third embodiment, will be described.

[0109] The first method involves varying the aperture through which the VCSEL emits light. Specifically, VCSELs are made of materials with a high Al content, such as AlAs. When oxidized, the Al becomes Al, resulting in a layer called a current-confining layer, which increases electrical resistance and creates a region where current flow is restricted. When the current-confining layer is oxidized, oxidation progresses from the periphery to the center of the circular cross section. By not oxidizing the center, the center of the VCSEL cross section becomes a current-passing region where current flow is easy, while the periphery becomes a current-blocking region where current flow is restricted. The VCSEL then emits light where the current path is restricted by the current-passing region in the light-emitting layer. The area on the surface of the VCSEL corresponding to this current-passing region becomes the light-emitting point and the light-emitting aperture. Therefore, by differentiating the oxidized diameter of this current-passing region from the oxidized diameter of other elements and widening the FFP of the light source, the beam profile σ on the illuminated surface can be changed.

[0110] In the second method, a microlens corresponding to each VCSEL is provided as the irradiation optical system 30, and the lens shape of the overlapping beam portion is made different from the other portions, thereby changing the beam profile σ on the irradiation surface.

[0111] <Fourth embodiment> Next, a fourth embodiment will be described. Note that the same parts as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0112] In each of the above embodiments, the irradiation optical system 30 shapes the light from the light source 20 so as to generate an overlapping area T on the object to be measured 80 and the 3D sensor 5 where adjacent areas emitted from multiple light-emitting sections 24 overlap, but in this embodiment, the method of generating the overlapping area T is different.

[0113] In this embodiment, the overlapping portion T is not an actual overlap of light, but rather light is emitted via the illumination optical system 30 by setting the positional relationship between the light source 20 and the 3D sensor 5 so that the light is exposed on an area of ​​the 3D sensor 5 that is regarded as one piece of data. For example, as shown in FIG. 15 , the light source 20 is configured as light-emitting sections 24 in which VCSELs are arranged in a row, and light emitted from the VCSELs of adjacent light-emitting sections 24 is irradiated onto a light-receiving section 26 that is regarded as one piece of data. This is equivalent to light emitted from the VCSELs of adjacent light-emitting sections 24 overlapping on the 3D sensor, so the light-receiving section 26 can be regarded as the overlapping portion T.

[0114] In this manner, in this embodiment, even if the light-receiving light-emitting sections 24 are overlapped instead of the actual overlapping of the light, a correction value can be obtained by performing the same processing as in the above embodiment.

[0115] In this case, if it is determined from the output results of areas 1, 2, and 3 in FIG. 15 that there is likely to be a light emission delay in area 2, correction can be made to match the results with those of area 1, which has the same sensor area.

[0116] In other words, if there is something wrong with area 2, and you try to make corrections so that area 3 minus area 2 is the same, the correction will include the light reception error of the sensor, so it is better to make corrections between area 1, which overlaps on the light receiving element PD.

[0117] If the sensor area can be changed, it is even better to try both area 1-area 2 and area 3-area 2 and then make corrections.

[0118] The control unit 8 identifies an area where an abnormality such as a delayed light emission in area 2 is likely to occur, for example, by checking whether the areas are continuous, determining whether only that area is always close based on changes over time, determining whether only that area is always close even when the camera position is moved, comparing with a two-dimensional camera image, etc. In this case, the control unit 8 functions as an abnormality identification unit.

[0119] Also, in each of the above embodiments, an area where an abnormality is likely to occur may be identified, and correction may be performed based on an area where no abnormality is present.

[0120] Furthermore, in each of the above embodiments, when the light-receiving section 26 corresponding to the overlapping portion T includes multiple light-receiving elements PD, the correction value may be obtained by calculating the average value of the light-receiving results of the multiple light-receiving elements PD as the distance measurement value in the overlapping portion T. Alternatively, the correction value may be obtained by calculating the sum of the light-receiving results of the multiple light-receiving elements PD.

[0121] Incidentally, in a light-emitting unit equipped with multiple light-emitting elements as in this embodiment, deviations occur in the light-emitting timing of each light-emitting element due to external factors such as driving conditions, temperature conditions, etc. The deviations in the light-emitting timing make it impossible for the light-receiving unit, which receives the reflected light of light irradiated onto the measurement object from each light-emitting element, to receive the reflected light uniformly.

[0122] Therefore, the object may be to provide a distance measuring device that can receive reflected light uniformly, compared to when light emitted from a light-emitting unit equipped with multiple light-emitting elements is directly irradiated onto an object and the reflected light is received.

[0123] In this case, the distance measuring device a light-emitting section including a plurality of light-emitting elements and capable of being driven independently in a plurality of regions; a light receiving unit including a plurality of light receiving elements that receive reflected light of light emitted from the light emitting unit toward an object; The light receiving unit may further include a shaping unit that generates overlapping portions where the reflected light is received in adjacent regions on the light receiving unit.

[0124] In the above embodiment, a CPU has been described as an example of a processor, but the term "processor" refers to a processor in a broad sense, and includes general-purpose processors (e.g., CPUs, etc.) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.).

[0125] Furthermore, the operations of the processors in the above embodiments may not only be performed by a single processor, but may also be performed by multiple processors located at physically separate locations working together. Furthermore, the order of the operations of the processors is not limited to the order described in the above embodiments, and may be changed as appropriate.

[0126] Furthermore, the processing performed by the control unit 8 of the measurement device 1 according to the above embodiment may be processing performed by software, processing performed by hardware, or processing performed by a combination of both. Furthermore, the processing performed by the control unit 8 of the measurement device 1 may be stored as a program on a storage medium and distributed.

[0127] Furthermore, the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0128] 1. Measuring equipment 3 Optical equipment 4. Light-emitting device 5 3D sensors 8 Control Unit 16B Partition Correspondence Table 16C Calibration Program 20 light source 24 Light-emitting section 26 Light receiving section 40 Distance reference part 90 gate electrode VCSEL Vertical Cavity Surface Emitting Laser PD photodetector T overlap part

Claims

1. a light-emitting section including a plurality of light-emitting elements and capable of being driven independently in a plurality of regions; a light receiving unit including a plurality of light receiving elements that receive reflected light of light emitted from the light emitting unit toward an object; a shaping unit that generates an overlapping portion where the reflected light is received in the adjacent regions on the light receiving unit; a measuring unit that measures the distance to the object based on the difference between the waveform of the light received by the light receiving unit and the waveform of the light emitting unit; a correction unit that corrects a distance difference between adjacent regions of the reflected light using a distance measurement value in the overlapping portion measured by the measurement unit; A distance measuring device comprising:

2. The distance measurement device according to claim 1 , wherein the shaping unit shapes the light emitted from the light emitting unit so that overlapping portions occur in the areas where adjacent reflected light is received on the light receiving unit.

3. The distance measuring device according to claim 2 , wherein the shaping unit includes a lens, and the overlapping portion is generated by shifting the focal position of the lens from the position of the light emitting unit.

4. 4. The distance measuring device according to claim 3, wherein the lens includes a plurality of lenses, and the overlapping portion is generated by shifting a position of a composite focal length of the plurality of lenses from a position of the light emitting portion.

5. 5. The distance measuring device according to claim 3, wherein the shaping unit generates the overlapping portion by shifting the position of the light emitting unit toward the lens from the position of the focal length.

6. The distance measuring device according to claim 1 , wherein the shaping section generates the overlapping portion in a part of the area where the received reflected light is adjacent to one another.

7. The distance measurement device described in claim 6, wherein the shaping unit generates the overlapping portion by light emitted from the light-emitting element in a part of the adjacent area where the reflected light is received and at a position away from the connection between the wiring unit that sends signals to each area of ​​the light-emitting unit and the light-emitting unit.

8. The distance measurement device of claim 1, wherein the shaping unit generates the overlapping portion by causing adjacent areas to be received by the light receiving area of ​​the light receiving unit, which regards the adjacent areas as one piece of data, and the correction unit corrects the distance difference by matching the distance measurement value in one of the areas received by the light receiving area to the distance measurement value in the other area.

9. 9. The distance measuring device according to claim 1, further comprising a distance reference section for measuring a distance reference within the device.

10. The distance measuring device according to claim 9 , wherein the distance reference portion is provided in a partial area of ​​a cover glass.

11. 11. The distance measuring device according to claim 1, wherein the correction unit corrects the distance difference by correcting at least one of the light emitted by the light emitting unit and the light received by the light receiving unit.

12. The distance measurement device according to any one of claims 1 to 8, further comprising an abnormality identification unit that identifies an area where an abnormality is likely to occur, and the correction unit performs correction based on the area where no abnormality is present.

13. 13. The distance measurement device according to claim 1, wherein when there are a plurality of light-emitting elements corresponding to the overlapping portion, the correction unit calculates and corrects an average value as the distance measurement value in the overlapping portion.

14. A distance measurement program for causing a computer to function as the measurement unit and the correction unit of the distance measurement device according to any one of claims 1 to 13.

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