Distance measuring device

Abstract

The present disclosure pertains to a distance measuring device capable of detecting light emission timing with a more appropriate configuration.　Provided is a distance measuring device (1) comprising: a light-emitting unit (12) having a plurality of light-emitting elements (31) that emit light pulse signals; a light detection unit (13) having a plurality of light-receiving elements (62) that receive reflected light pulse signals due to reflection of the light pulse signals by an object; a switching unit (16) that is provided between the light-emitting unit and the light detection unit and switches between transmission and blocking of the light pulse signals emitted from the light-emitting elements; and a processing unit (74) that, when the switching unit is in a transmission state, generates correction information for correcting a time difference in light emission timing between the plurality of light-emitting elements, on the basis of light reception information corresponding to the light pulse signals received by the plurality of light-receiving elements and magnetic flux information detected by analog circuits (35-1 to 35-n). For example, the present disclosure can be applied to a distance measuring device that performs distance measurement using a dToF method.

Description

distance measuring device

[0001] This disclosure relates to a distance measuring device, and more particularly to a distance measuring device that can detect the timing of light emission in a more appropriate configuration.

[0002] Time of Flight (ToF) sensors are known to measure the distance to an object by irradiating it with a pulsed light signal and receiving the reflected light signal from the object. When using a light-emitting module with multiple light-emitting elements as the light source, distance measurement can be performed by sequentially shifting the illumination of some of the multiple light-emitting elements.

[0003] To measure the distance to an object by emitting an optical pulse signal from a light-emitting element toward the object and receiving the reflected light pulse from the object with a photodetector, it is necessary to accurately detect the timing of the light emission of the light-emitting element. Patent Document 1 proposes a technique in which, in addition to a distance-measuring pixel, a reference pixel is provided, and the optical signals emitted by multiple light-emitting elements are directly received by multiple reference pixels via multiple optical waveguides, thereby detecting the time difference in the light emission timing of the multiple light-emitting elements.

[0004] International Publication No. 2023 / 190278

[0005] While techniques for detecting the light emission timing of multiple light-emitting elements have been proposed in the past, there has been a need for detecting the light emission timing with a more appropriate configuration.

[0006] This disclosure is made in light of these circumstances and aims to enable detection of light emission timing with a more appropriate configuration.

[0007] A distance measuring device according to one aspect of the present disclosure comprises a light-emitting unit having a plurality of light-emitting elements that emit light pulse signals, a photodetection unit having a plurality of photodetectors that receive reflected light pulse signals when the light-emitting pulse signals emitted by each of the plurality of light-emitting elements are reflected by an object, and a switching unit provided between the light-emitting unit and the photodetection unit that switches between transmitting and blocking the light-emitting pulse signals emitted from the light-emitting elements, wherein the light-emitting unit has a light-emitting array in which the plurality of light-emitting elements are arranged in a two-dimensional array, a soft magnetic bus made of a soft magnetic material arranged for the plurality of light-emitting elements, and an analog circuit that detects a current due to magnetic flux via the soft magnetic bus, and the photodetection unit has a processing unit that, when the switching unit is in a transmission state, generates correction information for correcting the time difference in the light emission timing of the plurality of light-emitting elements based on received light information corresponding to the light-emitting pulse signals received by the plurality of photodetectors and magnetic flux information detected by the analog circuit.

[0008] In a distance measuring device according to one aspect of this disclosure, there is a light-emitting unit having a plurality of light-emitting elements that emit light pulse signals, a light-detecting unit having a plurality of light-receiving elements that receive reflected light pulse signals when the light-emitting pulse signals emitted by each of the plurality of light-emitting elements are reflected by an object, and a switching unit provided between the light-emitting unit and the light-detecting unit that switches between transmitting and blocking the light-emitting pulse signals emitted from the light-emitting elements. The light-emitting unit is also provided with a light-emitting array in which the plurality of light-emitting elements are arranged in a two-dimensional array, a soft magnetic bus made of a soft magnetic material arranged around the plurality of light-emitting elements, and an analog circuit that detects current due to magnetic flux via the soft magnetic bus. When the switching unit is in a transmission state, correction information is generated to correct the time difference in the light emission timing of the plurality of light-emitting elements based on light-receiving information corresponding to the light-emitting pulse signals received by the plurality of light-receiving elements and magnetic flux information detected by the analog circuit.

[0009] Furthermore, the distance measuring device described in one aspect of this disclosure may be an independent device or an internal block constituting a single device.

[0010] This figure shows an example configuration of one embodiment of a distance measuring device to which the present disclosure is applied. This is a cross-sectional view showing the structure around the transmission / blocking switching section of Figure 1. This figure illustrates the principle of correction to which the present disclosure is applied. This is a circuit diagram showing an example configuration of a drive circuit. This figure illustrates the original simultaneous emission. This figure schematically shows the light produced by the original simultaneous emission. This figure illustrates pseudo-simultaneous emission. This figure schematically shows the light produced by pseudo-simultaneous emission. This figure illustrates the light emission unit of the light-emitting element. This figure illustrates a configuration that improves the reproducibility of through-current using a replica. This figure illustrates an example of the configuration of a soft magnetic bus. This figure illustrates an example of the configuration of a soft magnetic bus. This figure illustrates how the magnetic field generated when current flows is received by the soft magnetic bus. This figure schematically shows a noise rotating magnetic field caused by displacement current due to a voltage drop between the anode and cathode of a light-emitting element. This figure illustrates the principle of generating a noise rotating magnetic field caused by common impedance. This figure shows an overview of the wiring of the LDD in Figure 15. This figure shows an overview of the configuration shown in Figure 15. This figure shows a first example of the configuration of a soft magnetic bus including a disturbance cancellation mechanism. This figure shows a second example of the configuration of a soft magnetic bath. This figure illustrates a disturbance cancellation mechanism that can adopt any configuration. This figure shows a third example of the configuration of a soft magnetic bath including a disturbance cancellation mechanism. This figure schematically shows the separation of the common electrode. This figure schematically shows the separation of the common electrode. This figure shows a fourth example of the configuration of a soft magnetic bath including a disturbance cancellation mechanism. This figure shows a fifth example of the configuration of a soft magnetic bath. This figure shows a sixth example of the configuration of a soft magnetic bath. This figure shows a seventh example of the configuration of a soft magnetic bath. This figure shows a first example of the configuration of the disturbance cancellation mechanism. This figure shows a second example of the configuration of the disturbance cancellation mechanism. This figure shows a third example of the configuration of the disturbance cancellation mechanism. This figure shows a first example of a configuration using a Hall element as a magnetic flux detection element. This figure shows a second example of a configuration using a Hall element as a magnetic flux detection element. This figure shows an example of a configuration when a wound detection type is adopted. This is a circuit diagram showing a first example of the configuration of the AFE. This is a circuit diagram showing a second example of the configuration of the AFE. This is a circuit diagram showing a third example of the configuration of the AFE. This is a circuit diagram showing a first example of the configuration of the stage after the AFE. This is a circuit diagram showing a first example of the configuration of the peak hold circuit.This is a circuit diagram showing a second example of the configuration of the peak hold circuit. This is a circuit diagram showing a third example of the configuration of the peak hold circuit. This is a circuit diagram showing a second example of the configuration of the stage after the AFE. This is a circuit diagram showing a first example of the configuration of the AFE when a disturbance cancellation mechanism is provided before the AFE. This is a circuit diagram showing a second example of the configuration of the AFE when a disturbance cancellation mechanism is provided before the AFE. This is a circuit diagram showing a third example of the configuration of the AFE when a disturbance cancellation mechanism is provided before the AFE. This is a circuit diagram showing a fourth example of the configuration of the AFE when a disturbance cancellation mechanism is provided before the AFE. This is a diagram showing the overall flow of the first correction. This is a flowchart explaining the flow of the Rx relative correction process. This is a diagram explaining an example of light emission from a light-emitting element in Rx relative correction. This is a flowchart explaining the flow of the Tx absolute correction process. This is a diagram explaining an example of light emission from a light-emitting element in Tx absolute correction. This is a flowchart explaining the flow of the distance measurement process. This is a diagram explaining the details of the first correction. This is a diagram explaining the details of the first correction. This is a diagram explaining the details of the first correction. This is a diagram explaining the details of the first correction. This is a diagram explaining the overall flow of the second correction. This is a flowchart explaining the flow of the Tx absolute correction process. This is a diagram illustrating an example of light emission from a light-emitting element in absolute Tx correction. This is a flowchart illustrating the flow of the distance measurement process. This is a diagram illustrating the details of the second correction. This is a diagram illustrating the details of the second correction. This is a diagram illustrating the details of the second correction. This is a diagram illustrating the overall flow of the third correction. This is a flowchart illustrating the flow of the Rx relative correction process in RoI. This is a diagram illustrating the first example of RoI emission in relative Rx correction. This is a diagram illustrating the second example of RoI emission in relative Rx correction. This is a flowchart illustrating the flow of the Tx absolute correction process in RoI. This is a diagram illustrating an example of RoI emission in absolute Tx correction. This is a flowchart illustrating the flow of the distance measurement process in RoI. This is a diagram illustrating the overall flow of the fourth correction. This is a flowchart illustrating the flow of the Tx absolute correction process in RoI. This is a diagram illustrating an example of RoI emission in absolute Tx correction. This is a flowchart illustrating the flow of the distance measurement process in RoI.

[0011] <Device Configuration> Figure 1 shows an example of the configuration of one embodiment of a distance measuring device to which the present disclosure is applied.

[0012] The distance measuring device 1 in Figure 1 performs distance measurement using the dToF (direct Time of Flight) method. The distance measuring device 1 in Figure 1 comprises an overall control unit 11, a light-emitting unit 12, a light-detecting unit 13, lenses 14 and 15, and a transmission / blocking switching unit 16. The light-emitting unit 12 has a light-emitting section 12A, and the light-detecting unit 13 has a light-receiving section 13A. In this specification and drawings, the light-emitting unit 12A may be abbreviated as Tx, and the light-receiving unit 13A may be abbreviated as Rx.

[0013] The overall control unit 11 is composed of a processor, such as a CPU (Central Processing Unit). The overall control unit 11 controls the light-emitting unit 12 and the light-detecting unit 13. The overall control unit 11 may be integrated into either the light-emitting unit 12 or the light-detecting unit 13.

[0014] The light-emitting unit 12 includes a light-emitting array 21, a drive circuit 22, a clock generation unit 23, a light-emitting control unit 24, and a temperature measurement unit 25. The light-emitting array 21 is included in the light-emitting unit 12A. In the light-emitting array 21, a plurality of light-emitting elements 31 are arranged in a two-dimensional array. The plurality of light-emitting elements 31 repeatedly emit light-emitting pulse signals at predetermined time intervals. The light-emitting elements 31 are, for example, VCSELs (Vertical Cavity Surface Emitting Lasers). Hereinafter, the light-emitting array 21 will be described assuming that it is a VCSEL array.

[0015] Soft magnetic buses 32-1 to 32-n (n: natural number) are arranged around the bumps 41 of the multiple light-emitting elements 31 arranged in a two-dimensional array. The soft magnetic buses 32-1 to 32-n are made of a soft magnetic material such as thin-film ferrite. The bumps 41 are made of Cu or the like and electrically connect the multiple light-emitting elements 31 to the drive circuit 22. The soft magnetic bus 32-1 is arranged to surround the bumps 41, and a coil 33-1 is provided (wound around) in part of it. By surrounding the bumps 41 with the soft magnetic bus 32-1, it becomes the primary side of the transformer, and by forming the coil 33-1 with wiring, it becomes the secondary side of the transformer and is connected to the AFE (Analog Front End) 35-1.

[0016] The soft magnetic buses 32-2 to 32-n are configured similarly and connected to AFE 35-2 to 35-n. A disturbance cancellation mechanism 34 is provided before AFE 35-1 to 35-n. As will be described in detail later, the disturbance cancellation mechanism 34 may be configured in other ways, such as being provided after AFE 35-1 to 35-n. AFE 35-1 is an analog circuit that detects current due to magnetic flux via the soft magnetic bus 32-1. The same applies to AFE 35-2 to 35-n. The signals (information) output from AFE 35-1 to 35-n are input to the photodetector 13 via wiring.

[0017] The drive circuit 22 drives the multiple light-emitting elements 31 based on control signals from the light-emitting control unit 24. For example, the drive circuit 22 controls at least one of the light emission timing and light emission waveform of the light pulse signal based on the control signals. The clock generation unit 23 generates a clock signal synchronized with a reference clock signal. The reference clock signal is, for example, a signal input from outside the distance measuring device 1. Alternatively, the reference clock signal may be generated inside the distance measuring device 1.

[0018] The light emission control unit 24 generates a control signal synchronized with the clock signal to control at least one of the light emission timing and light emission waveform of each light-emitting element 31. The temperature measurement unit 25 measures the temperature of the light-emitting unit 12 (Tx chip temperature) and outputs the measured signal (temperature information) to the photodetection unit 13 via wiring. Note that the temperature measurement unit 25 does not need to be provided if the temperature information is not used in subsequent processing.

[0019] The light detection unit 13 includes a pixel array 51, a distance measurement processing unit 52, a control unit 53, a clock generation unit 54, a light emission timing control unit 55, a drive circuit 56, a distance measurement control unit 57, an output buffer 58, and a temperature measurement unit 59. The pixel array 51 is included in the light receiving unit 13A.

[0020] In the pixel array 51, a plurality of pixels 61 are arranged in a two-dimensional array. The plurality of pixels 61 receive the reflected light pulse signal from the object 2 via the lenses 14 and 15, and output a voltage signal corresponding to the reception. Each of the plurality of pixels 61 has a light receiving element 62. The light receiving element 62 is, for example, a SPAD (Single Photon Avalanche Diode).

[0021] The distance measurement processing unit 52 includes a TDC (Time to Digital Converter) 71, a histogram generation unit 72, a memory 73, and a signal processing unit 74. The TDC 71 generates a time-digital signal corresponding to the reception time of the reflected light pulse signal received by the light receiving element 62 with a predetermined time resolution. The histogram generation unit 72 generates a histogram corresponding to the time resolution of the TDC 71 based on the time-digital signal generated by the TDC 71.

[0022] The signal processing unit 74 calculates the center of gravity position of the reflected light pulse signal based on the histogram generated by the histogram generation unit 72, calculates the distance to the object 2, and outputs it via the output buffer 58. The memory 73 temporarily records data (information) from the histogram generation unit 72 or the signal processing unit 74. The signal processing unit 74 can perform processing using the data (information) recorded in the memory 73.

[0023] The control unit 53 controls the processing operations of each part of the light detection unit 13. The clock generation unit 54 generates the clock signals used by the TDC 71 and the histogram generation unit 72 based on the reference clock signal. The light emission timing control unit 55 controls the light emission control unit 24 of the light emission unit 12 and also controls the drive circuit 56. The drive circuit 56 drives the plurality of pixels 61 of the pixel array 51 based on the control signal from the light emission timing control unit 55.

[0024] The distance measurement control unit 57 controls the TDC 71, histogram generation unit 72, memory 73, and signal processing unit 74 of the distance measurement processing unit 52 based on the control signal from the control unit 53. The temperature measurement unit 59 measures the temperature of the photodetector 13 (Rx chip temperature) and outputs the measured signal (temperature information) to the signal processing unit 74. Note that the temperature measurement unit 59 does not need to be provided if the temperature information is not used in subsequent processing.

[0025] The transmit / block switch 16 switches between a transmit state, in which it transmits the light-emitting pulse signal emitted by the multiple light-emitting elements 31 arranged in the light-emitting array 21 of the light-emitting unit 12, and a block state, in which it blocks the said light-emitting pulse signal. The transmit / block switch 16 is, for example, an LCD (Liquid Crystal Display).

[0026] As will be described in detail later, when the transmission / blocking switching unit 16 is in the transmission state, the distance measuring processing unit 52 generates correction information to correct the time difference in the emission timing of the multiple light-emitting elements 31 based on the received light information (receiving timing information) corresponding to the emission pulse signals received by the multiple light-receiving elements 62 and the magnetic flux information (magnetic flux timing information) detected by the AFE 35. Also, when the transmission / blocking switching unit 16 is in the blocking state (i.e., when measuring the distance to object 2), the distance measuring processing unit 52 can calculate the distance to object 2 based on the emission timing of the multiple light-emitting elements 31 corrected based on the correction information and the magnetic flux information (magnetic flux timing information) detected by the AFE 35, and the received light information (receiving timing information) corresponding to the reflected light pulse signals received by the multiple light-receiving elements 62.

[0027] In addition, when generating correction information, temperature information (Tx chip temperature, Rx chip temperature) from the thermometer unit 25 and the thermometer unit 59 can be used. Due to the necessity of determining the timing of re-correction (re-generation of correction information) by grasping the physical properties of the light-emitting element 31, the change in the magnetic permeability of the soft magnetic material, and the change in the common impedance, at least one of the thermometer unit 25 and the thermometer unit 59 may be provided, but it is not essential. For example, the correction accuracy can be improved by increasing the data volume compared with the data at a specific temperature in the past, but if it is not necessary to grasp the deterioration amount by observing the change at the same temperature, there is no need to provide it.

[0028] <Peripheral Structure of Transmission / Blocking Switching Unit> FIG. 2 is a cross-sectional view showing the structure around the transmission / blocking switching unit 16 of FIG. 1. The transmission / blocking switching unit 16 is provided between the light-emitting unit 12 (light-emitting unit 12A) and the light-detecting unit 13 (light-receiving unit 13A). Light-shielding walls 101 and 102 are formed above and below the transmission / blocking switching unit 16. In the example of FIG. 2, the substrate on which the light-emitting unit 12 is arranged and the substrate on which the light-detecting unit 13 is arranged are provided separately.

[0029] As shown in FIG. 2, the light-emitting unit 12 has a stacked structure in which a VCSEL substrate 87 on which a VCSEL array 21 is arranged and an LDD (Laser Diode Driver) substrate 81 are joined. The VCSEL substrate 87 is a substrate made of a compound semiconductor such as GaAs. The surface of the VCSEL substrate 87 corresponding to the LDD substrate 81 is the front surface, and the laser light is emitted from the back surface (the upper surface of the VCSEL substrate 87 in FIG. 2). A plurality of mesa-structured light-emitting elements 31 are arranged on the VCSEL substrate 87 at predetermined intervals. Each light-emitting element 31 has a stacked film 86. The stacked film 86 includes a first multilayer film mirror, a first spacer layer, an active layer, a second spacer layer, a second multilayer film mirror, etc., resonates between the first multilayer film mirror and the second multilayer film mirror to improve the light intensity, and is emitted from the back surface side of the substrate (L in the figure). An undoped GaAs layer 88 is arranged on the end side of the VCSEL array 21.

[0030] The LDD substrate 81 has a plurality of pads 83 for supplying drive signals to a plurality of light-emitting elements 31. The pads 83 are formed of a conductive material such as Al. Bumps 41 made of Cu, for example, are arranged on top of the pads 83 of the LDD substrate 81 and are electrically connected to the bumps 41 on the light-emitting element 31 side via a solder layer 84 and a Ni layer 85. The LDD substrate 81 has a structure in which an insulating layer 82 made of SiN, etc. is laminated on a base layer made of Si, etc. A soft magnetic bus 32 is arranged on top of the LDD substrate 81 so as to surround the bumps 41. A coil 33 is provided in part of the soft magnetic bus 32 and the wiring forming the coil 33 is connected to the AFE 35. The AFE 35 of the light-emitting section 12 and the TDC 71 of the light-detecting section 13 are electrically connected via wiring 103.

[0031] As shown in Figure 2, the light detection unit 13 has a substrate 91 on which a plurality of pixels 61 are arranged. The substrate 91 is provided with circuits for generating voltages to be applied to the anode and cathode electrodes of the plurality of pixels 61, and circuits for reading the voltage signals of the cathode electrodes. The substrate 91 has a plurality of pads 93, which are electrically connected to the pads 95 of the plurality of pixels 61 via a solder layer 94, etc. The substrate 91 has a structure in which an insulating layer 92 made of SiN, etc. is laminated on a base material layer made of Si, etc. When the transmit / block switch 16 is in the transmit state, the light emission pulse signal emitted by the light-emitting element 31 is reflected by the lens 14, passes through the transmit / block switch 16, and is received by the light-receiving elements 62 of the plurality of pixels 61.

[0032] <Correction Principle of This Disclosure> Figure 3 is a diagram illustrating the principle of correction applied to this disclosure. Figure 3 shows the relationship between the light waveform, current waveform, and magnetic flux waveform when a light-emitting element 31 emits light individually (single-element emission) and when multiple light-emitting elements 31 emit light simultaneously (simultaneous emission). In each graph, the horizontal axis represents time, and the vertical axis represents the magnitude of light emission intensity (Power), current (I), and magnetic flux (B). In the graph for simultaneous emission, the graph for single-element emission is shown as a dashed line. Focusing on the light waveform, in simultaneous emission, compared to single-element emission, the light emission start time is delayed as shown by arrow A1, and the light emission intensity (Power) decreases as shown by arrow A2. In addition, the current waveform and magnetic flux waveform also show a decrease in current (I) and magnetic flux (B) during simultaneous emission (arrows A3, A4).

[0033] When there is a correlation between the light emission timing and the current waveform, the current waveform becomes a magnetic flux waveform and can be observed. If changes in magnetic flux density are not considered, the current waveform and the magnetic flux waveform will be similar in shape, as shown in Figure 3. Since only light and magnetic flux are actually observable, in this disclosure, instead of obtaining the light emission delay using light, the correlation between the light emission delay and the current waveform information of the light-emitting element is individually determined, and then the light emission delay during simultaneous emission is estimated from the current waveform information and corrected.

[0034] Figure 4 is a circuit diagram showing an example configuration of a drive circuit 22 that drives the light-emitting element 31. In Figure 4, the drive circuit 22 has a common drive circuit section 110 that is common to the drive circuit 22, and individual drive circuits 111-1 to 111-n that individually drive the light-emitting elements 31. The common drive circuit section 110 has a current source 121 and NMOS transistors 122 and 123. Individual drive circuit 111-1 has a PMOS transistor 130 and NMOS transistors 131 and 132, and drives the laser diode 133. Control signals from the light emission control unit 24 are input to the gates of the PMOS transistor 130 and NMOS transistor 132 via a delay or the like. Individual drive circuits 111-2 to 111-n are configured similarly to individual drive circuit 111-1.

[0035] In Figure 4, arrows A1 to A3 indicate the current when the current of the current source 121 is used as a current mirror during simultaneous illumination. For example, it is assumed that the current supply to the individual drive circuits 111-1 to 111-3 decreases as they move away from the common drive circuit section 110 (for example, towards the center in the case of shared access on both sides), causing a delay in the illumination of the laser diode 133. For the sake of explanation, the operation of the individual drive circuits 111-1 to 111-n will be described using the individual drive circuits 111-1 to 111-3 as representative examples.

[0036] Here, as shown in Figure 5, in the original simultaneous emission, each laser diode 133 emits light through the driving of the individual drive circuits 111-1 to 111-3. At this time, in the individual drive circuit 111-1, the PMOS transistor 130 is in the off state and the NMOS transistor 132 is in the on state, so the current from the laser diode 133 flows from the drain to the source of the NMOS transistor 132 (arrow A1). Similarly in the individual drive circuits 111-2 and 111-3, the PMOS transistor 130 is in the off state and the NMOS transistor 132 is in the on state, so the current from the laser diode 133 flows through the NMOS transistor 132 (arrows A2, A3).

[0037] At this time, as shown in Figure 6, when the transmission / blocking switching unit 16 is in the transmission state, the light L1 and L2 from the multiple light-emitting elements 31 (31-1, 31-2) corresponding to the laser diode 133 that is simultaneously emitted by the individual drive circuits 111-1 to 111-3 are reflected by the lens 14 and incident on the multiple pixels 61 of the pixel array 51. As a result, light that is a mixture of the light L1 and L2 from the multiple light-emitting elements 31 is incident, and it is not possible to distinguish which light-emitting element 31 emitted the light.

[0038] In this disclosure, among the laser diodes 133 that emit light simultaneously, one laser diode 133 emits light independently, while the remaining laser diodes 133 do not emit light, but a through-current flows, thereby simulating simultaneous emission. As shown in Figure 7, in the simulated simultaneous emission, among the individual drive circuits 111-1 to 111-3, the laser diode 133 emits light when driven by individual drive circuit 111-1, while the laser diodes 133 do not emit light when driven by individual drive circuits 111-2 and 111-3, but a through-current flows.

[0039] Specifically, in the individual drive circuit 111-1, the PMOS transistor 130 is in the off state and the NMOS transistor 132 is in the on state, causing current from the laser diode 133 to flow from the drain to the source of the NMOS transistor 132 (arrow A1). A switch 141 is provided in the wiring that electrically connects the gate of the PMOS transistor 130 and the gate of the NMOS transistor 132, and is in the off state. On the other hand, in the individual drive circuits 111-2 and 111-3, the PMOS transistor 130 is in the on state, the NMOS transistor 132 is in the on state, and the switch 141 is in the on state. As a result, the laser diode 133 does not emit light and no current flows to the laser diode 133, but a shoot-through current flows from the power supply VDD to ground (GND) (arrows A2, A3).

[0040] At this time, as shown in Figure 8, when the transmission / blocking switching unit 16 is in the transmission state, the light L1 from the light-emitting element 31-1, which corresponds to the laser diode 133 driven by the individual drive circuit 111-1, is reflected by the lens 14 and incident on the pixels 61 of the pixel array 51. In addition, the light-emitting element 31-2, which corresponds to the laser diode 133 driven by the individual drive circuits 111-2 and 111-3, does not emit light, but a through-current flows. That is, only one light-emitting element 31 emits light, and a through-current flows through the other light-emitting elements 31, so it is possible to detect the magnetic field corresponding to the current that has flowed, and since only one light-emitting element 31 emits light in a single pseudo-simultaneous emission while reproducing the common impedance, it is possible to obtain the correlation between the magnetic flux waveform and the optical timing.

[0041] The smallest unit of light emission may be a single light-emitting element or multiple light-emitting elements. For example, as shown in Figure 9, one laser diode 133 emits light when driven by individual drive circuit 111-1. Also, two laser diodes 133-1 and 133-2 emit light when driven by individual drive circuit 111-2. Three laser diodes 133-1 to 133-3 emit light when driven by individual drive circuit 111-3.

[0042] The accuracy of the reproducibility of the through-current may be improved by using a replica that mimics the laser diode 133. For example, as shown in Figure 10, the individual drive circuit 111-1 is configured to include a replica circuit 112-1 having a diode 151 and a PMOS transistor 152, where the diode 151 corresponds to the laser diode 133 but is a replica that does not emit light. The individual drive circuits 111-2 and 111-3 are configured similarly and include replica circuits 112-2 and 112-3. When a through-current flows during pseudo-simultaneous illumination, the PMOS transistor 152 and the NMOS transistor 132 are turned on, so the laser diode 133 does not emit light, but a through-current flows from the power supply VDD through the diode 151 to ground (GND).

[0043] The soft magnetic bus 32 can be constructed from a thin film of soft magnetic material. As the material for the thin film of soft magnetic material, for example, thin film ferrite or a material capable of transmitting magnetism can be used. When using thin film ferrite, it can be manufactured through low-temperature lamination and lithography processes. By thinning the soft magnetic material, high-frequency characteristics can be improved. Furthermore, thinning reduces the degrees of freedom, which is known to result in faster response times. Various configurations can be adopted for the soft magnetic bus 32.

[0044] For example, as shown in Figure 11, when the soft magnetic bus 32 surrounds the bump 41 of the light-emitting element 31, it may be configured to surround it with one layer in a cross-sectional view, or it may be configured to surround it with multiple layers. By stacking multiple layers of thin-film soft magnetic material, more magnetic flux can be captured, and magnetic saturation becomes less likely. Specifically, as shown in Figure 12, soft magnetic buses 32-1 to 32-4 may be provided to surround the bump 41 with four layers. A via 161 is provided on one side of the soft magnetic buses 32-1 to 32-4 and is connected to the AFE 35 via wiring 162. Details of the configuration examples of the soft magnetic bus 32 will be described later.

[0045] Here, according to Ampère's law, when an electric current flows, a magnetic flux is generated around it. In a capacitor, even if no actual current flows, a displacement current that can be considered as such can generate a rotating magnetic field inside the capacitor. However, since the soft magnetic bus 32 picks up magnetic fields without distinguishing between the rotating magnetic field caused by the current that is the intended target and magnetic fields caused by other disturbances, it is desirable to construct the thin-film soft magnetic material (e.g., thin-film ferrite) in a winding manner that can cancel out disturbances. Figure 13 shows that when a current A1 flows through the light-emitting element 31, a magnetic field B1 is generated around it and is received by the soft magnetic bus 32. In Figure 13, the magnetic field B1 generated by the flowing current A1 can be expressed by equation (1). Also, Ampère's law with the displacement current added is given by equation (2).

[0046]

[0047]

[0048] Figure 14 schematically shows the noise-generating rotating magnetic field caused by displacement current due to a voltage drop between the anode and cathode of the light-emitting element 31. While Figure 13 shows a magnetically rotating magnetic field caused by current, Figure 14 shows a rotating magnetic field (rotating magnetic field caused by displacement current) caused by a potential change between parallel plate-shaped electrodes. In Figure 14, the displacement current, i.e., the magnetic field B1, generated by the potential fluctuation between the electrodes of the common electrode of the VCSEL substrate 87 can be expressed by equation (3) from equations (1) and (2). Note that equation (3) corresponds to the displacement current portion extracted from equation (2).

[0049]

[0050] When the voltage drop of a light-emitting element 31 is caused by a current drawn by itself, it is like self-intoxication; there is always a correlation and it is harmless. However, when the voltage drop is caused by a current drawn by another light-emitting element 31, it is like external intoxication, and there is not necessarily a correlation. These relationships are expressed by the following equation (4). In equation (4), ΔV.self represents the voltage drop corresponding to current A1 (D1 in Figure 14), and ΔV.others represents the voltage drop corresponding to current A2 (D2 in Figure 14). Here, the voltage drop corresponding to current A1 generates a displacement current and creates a magnetic field B1. Similarly, the voltage drop corresponding to current A2 generates a magnetic field B2.

[0051]

[0052] In equation (4), the part of the external interference is an error; therefore, when constructing the soft magnetic bus 32, the winding method of the soft magnetic material should be such that it suppresses external interference. Note that external interference is an example of magnetic noise generated internally, and other noise sources exist, such as noise from the focusing mechanism of an adjacent camera.

[0053] The principle of generating a noise-generating rotating magnetic field due to common impedance will be explained with reference to Figures 15 to 17. In Figure 15, the LDD substrate 81 is configured as shown in Figure 16 when viewed from above in a plan view of the wiring, and parallel plates are formed by the wiring (common wiring, individual control wiring) of the light-emitting elements 31 by the VCSEL substrate 87 and the LDD substrate 81. Here, the parallel plates also appear as capacitance, and fluctuations in the voltage across them become a rotating magnetic field (displacement current). Also, as shown in Figure 17, the area A enclosed by the dashed line in the plan view of the VCSEL array 21 corresponds to the cross-sectional configuration shown in Figure 15. In Figure 17, among the circles numbered 0 to 15, circles with the same number represent light-emitting elements 31 that emit light simultaneously. In Figure 16, the LDD substrate 81 controls the light-emitting element 31 corresponding to number 0 to emit light through wiring 171 and 172.

[0054] In this case, as shown in Figure 15, the rotating magnetic field caused by voltage fluctuations is self-intoxicating and reproducible, so it does not pose a problem. On the other hand, the rotating magnetic field caused by voltage fluctuations due to common impedance is externally intoxicating, and the voltage drop due to the common impedance of the common electrode of the VCSEL substrate 87 is affected, so it is desirable to suppress it. Note that the light emission pattern shown in Figure 17 is just one example, and the simultaneously emitting locations do not necessarily have to be dispersed; for example, the simultaneously emitting locations may be in a line or clustered in one place. Note that there are multiple simultaneously emitting light-emitting elements 31, and when these are called banks, an operation is performed to switch them sequentially so that all banks emit light.

[0055] <Configuration of the soft magnetic bus> Figure 18 shows a first example of the configuration of the soft magnetic bus 32 including a disturbance cancellation mechanism. In Figure 18, the arrangement of the bumps 41 of the light-emitting elements 31 arranged in the VCSEL array 21 and the soft magnetic bus 32 provided with respect to the bumps 41 is shown in plan view. The soft magnetic bus 32 is arranged to surround a plurality of bumps 41, and a coil 33 is provided in part of it. The soft magnetic bus 32 surrounds the bumps 41 to form the primary side of the transformer, and the coil 33 is formed by wiring to form the secondary side of the transformer and is connected to the AFE 35.

[0056] In Figure 18, soft magnetic buses 32-1 to 32-4 are provided in the lateral direction in the figure for each of the bumps 41 arranged in a two-dimensional array. Coils 33-1 and 33-2 are provided on one side (the right side in the figure) of the soft magnetic buses 32-1 and 32-2 (the coils are wound around a part of the soft magnetic material) and are connected to the AFE 35-1 via wiring. Coils 33-3 and 33-4 are also provided on one side of the soft magnetic buses 32-3 and 32-4 and are connected to the AFE 35-2 via wiring. Note that Figure 18 shows only a partial configuration to explain the arrangement of the bumps 41 and soft magnetic buses 32, but in the VCSEL array 21, similar configurations are repeated.

[0057] As shown in Figure 18, the soft magnetic bus 32-1 is provided so as to surround the bumps 41 of the light-emitting elements 31 that do not emit light simultaneously in a plan view. In other words, within the range connected to the AFE 35-1, the light-emitting elements 31 can only emit light exclusively. The soft magnetic bus 32-1 is provided for multiple bumps 41, but the space between each bump 41 is narrowed (constricted), and it is provided so as to surround at least a part of each bump 41 with a polygonal shape. The soft magnetic buses 32-2 to 32-4 are configured in the same way as the soft magnetic bus 32-1.

[0058] Furthermore, in Figure 18, by reversing the phase of the connections between coils 33-1 and 33-2 connected to AFE 35-1, it is possible to cancel out the effects of uniform in-plane interference with the opposite phase. The same applies to the connections between AFE 35-2 and coils 33-3 and 33-4. Since AFE 35-1 and 35-2 are input as individual signals in both in-phase and out-of-phase, it is necessary to accommodate both rising and falling edges. In other words, in Figure 18, the function of the disturbance cancellation mechanism is realized by the connection between AFE 35 and coil 33.

[0059] Thus, the soft magnetic bus 32 can be positioned to surround the current-carrying portion (bump 41 made of Cu or the like) of the light-emitting element 31 in order to easily capture the rotating magnetic flux. Furthermore, in Figure 18, in order to better capture the rotating magnetic field, the soft magnetic bus 32 is positioned to surround the current-carrying portion of the light-emitting element 31, creating a configuration that cancels out the uniform rotating magnetic field. Specifically, coils 33-1 and 33-2 are connected in opposite directions to the pair of inputs of AFE 35-1, so that when a uniform rotating magnetic field is generated, each generates a voltage of the same strength but in opposite phase, resulting in them canceling each other out and no voltage being generated at AFE 35-1. The same applies to coils 33-3, 33-4 and AFE 35-2.

[0060] Figure 19 shows a second example of the configuration of the soft magnetic bus 32. As shown in Figure 19, the soft magnetic bus 32-1 is provided so as to surround the bumps 41 of the light-emitting element 31 that do not emit light simultaneously in a plan view. The soft magnetic bus 32-1 is provided for multiple bumps 41, and has a rectangular shape with rounded corners. In other words, the soft magnetic bus 32-1 in Figure 19 does not have a narrower width between each bump 41 compared to the soft magnetic bus 32-1 in Figure 18, but as long as it is arranged to capture the rotating magnetic flux, it does not necessarily have to be shaped to surround the part of the light-emitting element 31 through which the current flows.

[0061] A coil 33-1 is provided on one side of the soft magnetic bus 32-1 and connected to the AFE 35-1. The soft magnetic buses 32-2 to 32-n are configured in the same way as the soft magnetic bus 32-1. For example, a coil 33-n-1 is provided on one side of the soft magnetic bus 32-n-1 and connected to the AFE 35-n-1. A coil 33-n is provided on one side of the soft magnetic bus 32-n and connected to the AFE 35-n.

[0062] As shown in Figure 20, a disturbance cancellation mechanism 34 may be provided between the coil 33 and the AFE 35. In Figure 20, the same reference numerals are used for parts corresponding to those in Figure 19, and the disturbance cancellation mechanism 34 is provided between the coils 33-1 to 33-n and the AFEs 35-1 to 35-n. The configuration of the disturbance cancellation mechanism 34 is not limited to the wiring connection shown in Figure 18, but other configurations may be adopted. For example, the disturbance cancellation mechanism 34 is not limited to cancellation using two soft magnetic buses 32, but may use multiple soft magnetic buses 32, and any configuration that can cancel disturbances is arbitrary.

[0063] Figure 21 shows a third example of the configuration of the soft magnetic bus 32 including a disturbance cancellation mechanism. As shown in Figure 21, the soft magnetic bus 32-1 is provided so as to surround a common bump 41 in a plan view. For example, as shown in Figures 22 and 23, when the common electrodes 89-1 to 89-3 are separated, the soft magnetic bus 32 can be provided with respect to the bump 41 of the common electrode 90. In Figure 22, the common electrodes 89-1 to 89-3 are separated by substrate surface concentration by freely changing the substrate concentration of the doped GaAs. Also, in Figure 23, by separating the common electrodes 89-1 to 89-3 by bulk, plate-shaped common electrodes 89 and insulators 87A are formed alternately in a plan view. A coil 33-1 is provided on one side of the soft magnetic bus 32-1 and connected to the AFE 35-1.

[0064] In Figure 21, the soft magnetic buses 32-2 to 32-4 are configured in the same way as the soft magnetic bus 32-1. A coil 33-2 is provided on one side of the soft magnetic bus 32-2 and connected to the AFE 35-1. A coil 33-3 is provided on one side of the soft magnetic bus 32-3 and connected to the AFE 35-2. A coil 33-4 is provided on one side of the soft magnetic bus 32-4 and connected to the AFE 35-2. Thus, Figure 21 shows a configuration in which two soft magnetic buses 32 are connected by one AFE 35, including a disturbance cancellation mechanism, and shows a case where the bump 41 of the common electrode 90 is surrounded by the soft magnetic buses 32, in a configuration where only one light-emitting element 31 can emit light for each AFE 35. Furthermore, when employing a configuration that does not include a disturbance cancellation mechanism, if the common electrode can be separated into light-emitting units that do not emit light simultaneously, the portion corresponding to the common electrode (for example, the bump of the undoped GaAs layer 88 in Figure 2) can be surrounded by the soft magnetic bus 32.

[0065] Figure 24 shows a fourth example of the configuration of the soft magnetic bus 32 including a disturbance cancellation mechanism. As shown in Figure 24, the light-emitting elements that do not emit light simultaneously may be divided into two or more groups, and each bump of the light-emitting elements divided into two or more groups may be surrounded by a soft magnetic bus. For example, when the light-emitting elements 31 that do not emit light simultaneously are divided into two groups, the soft magnetic buses 32-1A and 32-2A are provided to surround the bump 41 of one group of light-emitting elements 31. The soft magnetic buses 32-1B and 32-2B are provided to surround the bump 41 of the light-emitting elements 31 of the other group.

[0066] Coils 33-1A and 33-2A are provided on one side (right side in the figure) of the soft magnetic buses 32-1A and 32-2A and connected to AFE 35-1A. Coils 33-1B and 33-2B are provided on one side (left side in the figure) of the soft magnetic bus 32-1B and coil 33-2B and connected to AFE 35-1B. Similarly, for the soft magnetic buses 32-3A and 32-4A, and the soft magnetic buses 32-3B and 32-4B, when the light-emitting elements 31 that do not emit light simultaneously are divided into two groups, the coils are provided so as to surround the bumps 41 of the light-emitting elements 31 included in one group and the other group. Figure 24 shows a configuration in which two soft magnetic buses 32 are connected by one AFE 35, including a disturbance cancellation mechanism.

[0067] Figure 25 shows a fifth example of the configuration of the soft magnetic bus 32. As shown in Figure 25, when surrounding the bumps of the light-emitting element with the soft magnetic bus, the direction of surrounding can be changed. For example, in the soft magnetic bus 32 provided for coil 33-1 connected to AFE 35-1, soft magnetic materials 32-1A, 32-1B, 32-2A, and 32-2B are wound clockwise and counterclockwise around bump 41. Vias 181A are provided for soft magnetic materials 32-1A and 32-2A, and vias 181B are provided for soft magnetic materials 32-1B and 32-2B. Similarly, in the soft magnetic bus 32 provided for coil 33-2 connected to AFE 35-2, soft magnetic materials 32-3A, 32-3B, 32-4A, and 32-4B are wound clockwise and counterclockwise around bump 41.

[0068] Figure 26 shows a sixth example of the configuration of the soft magnetic bus 32. As shown in Figure 26, when surrounding the bumps of the light-emitting elements with the soft magnetic bus, the configuration may involve multiple turns. For example, the soft magnetic buses 32-1 and 32-2 are provided so as to double-surround the bumps 41 of the light-emitting elements 31 that do not emit light simultaneously in a plan view. A coil 33 is provided on one side of the double-layered soft magnetic buses 32-1 and 32-2 and connected to the AFE 35. In Figure 26, a configuration is shown in which multiple bumps 41 are surrounded by two turns of the soft magnetic buses 32-1 and 32-2, but a configuration involving three or more turns may also be used.

[0069] Figure 27 shows a seventh example of the configuration of the soft magnetic bus 32. As shown in Figure 27, when surrounding the bumps of the light-emitting elements with the soft magnetic bus, a configuration with multiple layers is also possible. For example, the soft magnetic buses 32-1 to 32-4 are provided so as to surround the bumps 41 of the light-emitting elements 31 that do not emit light simultaneously in a cross-sectional view with four layers. A via 161 is provided on one side of the four-layered soft magnetic buses 32-1 to 32-4 and is connected to the AFE 35 through wiring 162. Although Figure 27 shows a configuration in which multiple bumps 41 are surrounded by four layers of soft magnetic buses 32-1 to 32-4, a configuration with two, three, or five or more layers is also possible.

[0070] As described above, the disturbance cancellation mechanism 34 can employ various configurations. As shown in Figure 28, the disturbance cancellation mechanism 34 can be provided between coils 33-1 and 33-2 and the AFE 35. In Figure 28, the disturbance cancellation mechanism 34 is provided for two coils 33 (soft magnetic bath 32), but it may also be provided for three or more coils 33 (soft magnetic bath 32).

[0071] Furthermore, as shown in Figure 29, the disturbance cancellation mechanism 34 is not limited to being placed before the AFE 35, but may also be placed after the AFE 35 (35-1, 35-2). As shown in Figure 30, if disturbance cancellation is possible after processing by the TDC 71, the disturbance cancellation mechanism 34 may be placed after the TDC 71. Thus, the disturbance cancellation mechanism 34 may be placed at the magnetic flux detection stage, after the AFE 35, or after the TDC 71 (for example, in the signal processing unit 74). Note that if the disturbance cancellation mechanism 34 is not needed, it may not be placed.

[0072] The element used for magnetic flux detection is not limited to a coil; for example, a Hall element may be used. As shown in Figure 31, the soft magnetic bus 32-1 is provided so as to surround the bumps 41 of the light-emitting element 31 that do not emit light simultaneously in a plan view, and a Hall element 191-1 is provided on one side. The Hall element 191-1 can detect a magnetic field by utilizing the Hall effect. The Hall element 191-1 is connected to the AFE 35-1 via wiring. Similarly, for the soft magnetic buses 32-2 to 32-4, a Hall element 191 is provided on one side. The disturbance cancellation mechanism 34 is connected to the AFE 35 (35-1 to 35-4) which are connected to the Hall elements 191 (191-1 to 191-4). Note that even when using the Hall element 191 as shown in Figure 31, a configuration without the disturbance cancellation mechanism 34 may be adopted.

[0073] When providing Hall elements, a feedback winding may be used considering the BH characteristics. In Figure 32, the same reference numerals are used for parts corresponding to those in Figure 31, and a feedback winding 192 is provided for each Hall element 191. As shown in Figure 32, a Hall element 191-1 and a feedback winding 192-1 are provided on one side of the soft magnetic bus 32-1. The feedback winding 192-1 is wound around a part of the soft magnetic bus 32-1 and connected to the AFE 35-1. Similarly, for the soft magnetic buses 32-2 to 32-4, a Hall element 191 and a feedback winding 192 are provided on one side. In this way, by providing a feedback winding 192 that cancels the magnetic flux in the magnetic core in order to cancel out the effect of the BH characteristics, it is possible to achieve a wide bandwidth. Note that even when using Hall elements 191 and feedback windings 192 as shown in Figure 32, a configuration without a disturbance cancellation mechanism 34 may be adopted.

[0074] When a coil is used as the element for detecting magnetic flux, a feedback winding may also be used. In Figure 33, the same reference numerals are used for parts corresponding to those in Figure 29, and a feedback winding 192 is provided for each coil 33. As shown in Figure 33, a coil 33-1 and a feedback winding 192-1 are provided on one side of the soft magnetic bus 32-1. The feedback winding 192-1 is wound around a part of the soft magnetic bus 32-1 and connected to the AFE 35-1. Similarly, a coil 33-2 and a feedback winding 192-2 are provided on one side of the soft magnetic bus 32-2. Note that even when using a coil 33 and a feedback winding 192 as shown in Figure 33, a configuration without a disturbance cancellation mechanism 34 may be adopted.

[0075] <Configuration of AFE> Figure 34 is a circuit diagram showing a first example of the configuration of the AFE 35. Figure 34 shows the circuit configuration of the main parts of the light-emitting unit 12 and the light-detecting unit 13. The light-emitting unit 12 has a common drive circuit unit 110, individual drive circuits 111, a soft magnetic bus 32, and the AFE 35. The common drive circuit unit 110 has a current source 121 and NMOS transistors 122 and 123. The individual drive circuits 111 have a PMOS transistor 130 and NMOS transistors 131 and 132, and drive the laser diodes 133. Multiple individual drive circuits 111 are provided according to the multiple light-emitting elements 31 (laser diodes 133) arranged in a two-dimensional array on the VCSEL array 21.

[0076] As shown in Figure 34, the light-emitting unit 12 uses a coil 33 as an element for detecting magnetic flux and has a transformer-type current detection means. The AFE 35 has an operational amplifier 231 and resistors 232 to 234, and converts the input current from the coil 33 into a voltage by the resistor 232 and amplifies it in a non-inverting manner by the operational amplifier 231. A comparator 241 is provided downstream of the AFE 35 and is connected to the TDC 71 of the photodetector 13 via buffers 242 and 243. With this configuration, magnetic flux waveform information (magnetic flux information) related to the waveform of the magnetic flux detected by the AFE 35 can be converted into magnetic flux timing information.

[0077] Figure 35 is a circuit diagram showing a second example of the configuration of the AFE 35. In Figure 35, the same reference numerals are used for parts corresponding to those in Figure 34. As shown in Figure 35, the light-emitting unit 12 has a transformer-type current detection means, and the AFE 35 has a TIA (Trans-impedance Amplifier) ​​consisting of an operational amplifier 251, a capacitor 252, and a resistor 253, which converts the input current into a voltage. A comparator 241 is provided downstream of the AFE 35 and is connected to the TDC 71 of the photodetector 13 via buffers 242 and 243.

[0078] Figure 36 is a circuit diagram showing a third example of the configuration of the AFE 35. In Figure 36, the same reference numerals are used for parts corresponding to those in Figure 34. As shown in Figure 36, the light-emitting unit 12 uses a Hall element 191 as an element used for magnetic flux detection and has a Hall element type current detection means. The Hall element 191 is connected to a power supply 261 to operate at a constant voltage. The AFE 35 has an operational amplifier 231 and resistors 233 and 234, and the input voltage is amplified non-inverting by the operational amplifier 231. A comparator 241 is provided downstream of the AFE 35 and is connected to the TDC 71 of the photodetector 13 via buffers 242 and 243.

[0079] Figure 37 is a circuit diagram showing a first example of the configuration after the AFE 35. In Figure 37, the same reference numerals are used for parts corresponding to those in Figure 34. For example, the configuration of the AFE 35 in Figure 37 can be the same as the configuration of the AFE 35 shown in Figure 34. As shown in Figure 37, a peak hold circuit 271 is connected between the AFE 35 and the comparator 241. By connecting the peak hold circuit 271 after the AFE 35, it is possible to grasp the approximate strength of the magnetic flux strength information related to the strength of the magnetic flux detected by the AFE 35.

[0080] The peak hold circuit 271 can use, for example, the circuit configurations shown in Figures 38 to 40. As shown in Figure 38, the peak hold circuit 271 has a source follower transistor 281, a current source 282, an operational amplifier 283, a capacitor 284, and a switch 285, so that it holds the maximum positive value of the output signal from AFE 35 in the capacitor 284 and outputs it. Also, as shown in Figure 39, the peak hold circuit 271 has one operational amplifier 291, a diode 292, a capacitor 293, and a switch 294, so that it holds the maximum positive value of the output signal from AFE 35 in the capacitor 293 and outputs it. Furthermore, as shown in Figure 40, the peak hold circuit 271 has two operational amplifiers 301 and 302, resistors 303 and 304, diodes 305 and 306, a capacitor 307, and a switch 308, so that it holds the maximum positive value of the output signal from AFE 35 in the capacitor 307 and outputs it.

[0081] Figure 41 is a circuit diagram showing a second example of the configuration of the AFE 35's downstream stage. In Figure 41, the same reference numerals are used for parts corresponding to those in Figure 34. For example, the configuration of the AFE 35 in Figure 41 can be the same as the configuration of the AFE 35 shown in Figure 34. As shown in Figure 41, comparators 241-1 to 241-3 are provided downstream of the AFE 35. Comparator 241-1 is connected to the TDC 71-1 of the photodetector 13 via buffers 242-1 and 243-1. Comparator 241-2 is connected to the TDC 71-2 of the photodetector 13 via buffers 242-2 and 243-2. ​​Comparator 241-3 is connected to the TDC 71-3 of the photodetector 13 via buffers 242-3 and 243-3.

[0082] Comparator 241-1 voltage threshold V TH1 , the voltage threshold V of comparator 241-2 TH2 , the voltage threshold V of comparator 241-3 TH3 V TH1 > V TH2 > V TH3 As a result, the voltage thresholds are different. By using comparators 241-1 to 241-3, each with different voltage thresholds, and the connected TDCs 71-1 to 71-3, the output signal from AFE 35 can be used to obtain both magnetic flux timing information and magnetic flux strength information. This allows us to determine not only the strength but also the slew rate of the current information (which is almost equal to the magnetic flux information).

[0083] In Figures 37 and 41, the configuration of the AFE 35 shown in Figure 34 is described, but the configuration of the AFE 35 shown in Figure 35 or Figure 36 may also be used. However, if the configuration of the AFE 35 shown in Figure 36 is used, the current detection means must be of the Hall element type. In Figure 41, a configuration with comparators 241-1 to 241-3 is shown as the downstream configuration of the AFE 35, but any number of comparators with different voltage thresholds may be provided, and the number of comparators 241 is not limited to three. Buffers 242, 243 and TDC 71 are provided according to the number of comparators 241.

[0084] Figures 42 to 45 show an example configuration of the AFE 35 when a disturbance cancellation mechanism is provided before the AFE 35. In Figure 42, the same reference numerals are used for parts corresponding to those in Figure 34. As shown in Figure 42, when a disturbance cancellation mechanism is present, the magnetic flux signal is input to the AFE 35 as positive and negative signals. The AFE 35 has a fully differential amplifier 236, which amplifies the positive and negative signals as differential inputs and outputs them as differential outputs. After the AFE 35, comparators 241-1 and 241-2 and an OR circuit 240 are provided. Comparator 241-1 is used when a magnetic flux is generated and the input voltage exceeds the voltage threshold V TH+ When it exceeds the voltage threshold V, it outputs an H-level signal. Comparator 241-2 generates magnetic flux and the input voltage exceeds the voltage threshold V. TH- When the value falls below a certain level, it outputs an H-level signal. The OR gate 240 outputs a signal corresponding to the H level when either of the signals input from comparators 241-1 and 241-2 is an H-level signal.

[0085] In Figures 43 to 45, the same reference numerals are used for parts corresponding to those in Figure 42. Figure 43 shows a configuration where the AFE 35 connected to the front of the fully differential amplifier 236, which converts the input current to a voltage, is different from the AFE 35 in Figure 42. Figure 44 shows a configuration where the fully differential amplifier 236 is a TIA. Figure 45 shows a configuration where a Hall element 191 is used as the element for detecting magnetic flux, and the AFE 35 has a fully differential amplifier 236 and operational amplifiers 237 and 238. In Figures 43 to 45, similar to Figure 42, the comparators 241-1 and 241-2 after the AFE 35 output signals corresponding to the generation of magnetic flux, and the OR circuit 240 outputs signals corresponding to the output signals of the comparators 241-1 and 241-2. As described above, the AFE 35 in Figures 42 to 45 is configured to include a fully differential amplifier 236, which makes it possible to handle positive and negative signals input when there is a disturbance cancellation mechanism in the preceding stage.

[0086] <Details of Correction> The correction described herein is performed when a range measuring error occurs in the range measuring device 1, that is, when there is a change in conditions that causes a delay. Such changes in conditions include, for example, when the temperature changes, when a certain amount of time has elapsed, or when the number of simultaneous light emission changes. Changes in temperature include changes in the physical properties of the light-emitting element, changes in the physical properties of the soft magnetic material, and changes in the resistance value of the common impedance. The elapsed time includes deterioration due to prolonged use. Changes in the number of simultaneous light emission include changes in the region when setting the RoI (Region of Interest).

[0087] The corrections that are performed again in response to changes in conditions include Rx relative correction and Tx absolute correction. Rx relative correction is a correction that corrects the time difference caused by the pixel 61 (photodetector 62) by recording the centroid time difference that occurs in the pixel 61 (photodetector 62) that should have received light at the same time when a single light source (light-emitting element 31) illuminates the entire photodetector 13A (Rx), and subtracting the relative difference. Tx absolute correction is a correction that calculates the zero point (time of zero distance) in distance measurement during actual use by obtaining the centroid time which is the sum of all the differences included in the path, by performing a series of steps from the light emission instruction to the light emission on the light-emitting element 12A (Tx) side and the light reception on the photodetector 13A (Rx) side for each individual light-emitting element 31.

[0088] The corrections described in this disclosure include cases where relative Rx correction and absolute Tx correction are performed (hereinafter referred to as the first correction), cases where absolute Tx correction is performed (hereinafter referred to as the second correction), cases where relative Rx correction and absolute Tx correction are performed when setting the RoI (hereinafter referred to as the third correction), and cases where absolute Tx correction is performed when setting the RoI (hereinafter referred to as the fourth correction). The principles of the first to fourth corrections are explained below.

[0089] <<Principle of the First Correction>> Figure 46 is a diagram showing the overall flow of the first correction. In Figure 46, the light-emitting unit 12, the light-detecting unit 13, and the transmission / blocking switching unit 16 provided in the distance measuring device 1 are schematically shown. In the distance measuring device 1, when it switches from the off state to the on state, Rx relative correction and Tx absolute correction are performed in that order. In Rx relative correction, the transmission / blocking switching unit 16 becomes the transmission state (LCD: ON), and the light-emitting element 31 emits light independently. At this time, other light-emitting elements do not emit light, and there is no need to generate a through-current. In Figure 46, the light that has passed through the transmission / blocking switching unit 16 due to the light-emitting element 31 is represented by the light L on the light-detecting unit 13.

[0090] In Tx absolute correction, the transmit / block switch 16 enters a transmit state, and the light-emitting element 31 emits light independently. At this time, other light-emitting elements (light-emitting elements that emit light simultaneously) do not emit light, but the LDD substrate 81 is controlled to allow a through-current to flow in order to reproduce the effect of common impedance. Rx relative correction and Tx absolute correction are performed again depending on the change in conditions. In distance measurement (distance measurement during actual use), the transmit / block switch 16 enters a light-blocking state (LCD: OFF), and multiple light-emitting elements 31 emit light simultaneously. In distance measurement, the distance to object 2 is measured based on the light emission timing of the multiple light-emitting elements 31 corrected based on the correction information and magnetic flux timing information acquired in Rx relative correction and Tx absolute correction, and the light-receiving timing of the multiple light-receiving elements 62.

[0091] Figure 47 is a flowchart illustrating the flow of the Rx relative correction process. In the Rx relative correction process shown in Figure 47, it is determined whether or not the light-emitting element 31 is to be skipped (S11). If it is determined that it is not to be skipped, the process from step S12 onwards is carried out. That is, the transmission / blocking switching unit 16 becomes the transmission state, and the light-emitting element 31 emits light on its own based on the control from the light emission timing control unit 55 (S12). The light pulse signal emitted by the light-emitting element 31 passes through the transmission / blocking switching unit 16 and is received by multiple pixels 61 of the pixel array 51 (S13). Next, the signal processing unit 74 performs timing and detects the time difference between, for example, the timing corresponding to the light emission command (Rx light emission command) from the light emission timing control unit 55 and the timing when the light-receiving element 62 receives the light pulse signal (S14).

[0092] Then, it is determined whether the processes in steps S12 to S14 have been repeated a first predetermined number of times (for example, 10,000 times) (S15). If it is determined that the processes have been repeated a first predetermined number of times, the signal processing unit 74 calculates the time difference in light reception timing between the multiple light-receiving elements 62 (hereinafter also called the Rx in-plane time difference) based on the result of repeating step S14 a first predetermined number of times (S16). Then, it is determined whether the relationship M = M_max is satisfied (S17). If it is determined that M = M_max is not satisfied, the process returns to step S11, and the above process is repeated. Here, M represents the set of light-emitting elements 31 that emit light simultaneously in the VCSEL array 21, and is called a bank.

[0093] For example, as shown in Figure 48, when the light-emitting elements 31 to be skipped in the VCSEL array 21 are represented by a dot pattern, the light-emitting elements 31 at the four corners and the center that are not to be skipped are illuminated individually in a predetermined number of units in sequence, and the Rx in-plane time difference is calculated. In the Rx relative correction process, all light-emitting elements 31 are illuminated one by one, and the Rx relative correction is performed based on this. However, if practical accuracy can be obtained through interpolation without individually illuminating all light-emitting elements 31, then some may be skipped. In other words, control is performed to illuminate all or some of the multiple light-emitting elements 31 one by one in sequence. In Figure 48, among the circles numbered 0 to 15, circles with the same number represent light-emitting elements 31 that are illuminated simultaneously, and the numbers 0 to 15 correspond to M. Specifically, in the example in Figure 48, there are Banks 0 to 15, and only specific light-emitting elements 31 within a specific bank are illuminated.

[0094] Each time the set of simultaneously emitting light-emitting elements 31 changes, the value of M is incremented. If it is determined that M = M_max, the signal processing unit 74 acquires (generates) Rx relative correction information based on the calculation result of step S16 (S18). When generating this Rx relative correction information, operations are performed to eliminate the dependency on the light-emitting location of the light-emitting elements 31. The Rx relative correction information includes information for correcting the relative delay time of the multiple photodetectors 62 (Rx in-plane time difference information). Note that temperature information may also be included in the Rx relative correction information. When the processing in step S18 is completed, the series of processes is finished.

[0095] Figure 49 is a flowchart illustrating the flow of the Tx absolute correction process. In the Tx absolute correction process shown in Figure 49, the transmit / block switch 16 enters the transmit state, and the light-emitting element 31 emits light independently based on control from the light emission timing control unit 55 (S21). At this time, based on control from the light emission control unit 24, the other light-emitting elements (light-emitting elements that emit light simultaneously) do not emit light, but are controlled to allow a through-current to flow. In other words, although we would like the other light-emitting elements to emit light as well, if the other light-emitting elements emit light, it would be impossible to detect the light emission delay of each light-emitting element, so one light-emitting element emits light, and the rest are treated as a through-current.

[0096] The light pulse signal emitted by the light-emitting element 31 passes through the transmission / blocking switching unit 16 and is received by multiple pixels 61 of the pixel array 51 (S22). The AFE 35 also detects the current due to the magnetic flux via the soft magnetic bus 32 (S22). Here, a through-current flows not only to the light-emitting element 31 that emits light independently, but also to other light-emitting elements (light-emitting elements that emit light simultaneously), so the current can be detected. Next, the signal processing unit 74 performs timing and detects, for example, the time difference between the timing corresponding to the Rx light emission command by the light emission timing control unit 55 and the timing when the light-receiving element 62 receives the light pulse signal, and the time difference between this and the timing when the AFE 35 detects the magnetic flux (and the resulting current) (S23).

[0097] Then, it is determined whether the processes in steps S21 to S23 have been repeated a second predetermined number of times (for example, 10,000 times) (S24). If it is determined that the processes have been repeated a second predetermined number of times, the signal processing unit 74 calculates the delay time of a light-emitting element 31 that has emitted light individually (hereinafter also called the Tx individual delay amount) based on the result of repeating step S23 a second predetermined number of times (S25). Subsequently, it is determined whether the through-current distribution has been completed (S26) and whether the simultaneous emission number distribution has been completed (S27). Here, in a bank where simultaneous emission will occur, a situation is created where there is only one light source, and whether this has been done once for all the light-emitting elements 31 that are to emit light in a single bank is called the through-current distribution. In addition, in the determination of simultaneous emission number distribution, it is determined whether all the information for Bank0 to Bank15 has been acquired, that is, whether the banks have been completed once. If it is determined that these distributions are incomplete (S26: No, S27: No), the process returns to step S21, and the above process is repeated. When this process is repeated, the bank number and the order of the through-currents within the bank are incremented.

[0098] For example, in Figure 50, among Bank0 to Bank15, banks with the same number represent simultaneously emitting light-emitting elements 31. In this example, there are eight light-emitting elements 31 in one bank, and processing is performed for all light-emitting points in this bank by having only one light-emitting element 31 emit light and the remaining seven emit through-current eight times. That is, among the simultaneously emitting light-emitting elements 31, one light-emitting element 31 emits light, and the remaining elements do not emit light, allowing through-current to flow, while the control is performed to sequentially switch the light-emitting elements 31 that emit light only one at a time. On the other hand, if it is determined that these switching processes are complete (S26: Yes, S27: Yes), the signal processing unit 74 acquires (generates) Tx absolute correction value information based on the calculation result of step S25 (S28).

[0099] This Tx absolute correction value information includes information for correcting the delay time of each of the multiple light-emitting elements 31 (information on the Tx individual delay amount). In addition to the Tx individual delay amount, the Tx absolute correction value information also includes the light emission position, simultaneous light emission position, and number of simultaneous light emission elements. The light emission position indicates the position when only one light-emitting element 31 is emitting light. The simultaneous light emission position indicates the position of the light-emitting elements 31 that are emitting light simultaneously (i.e., the position of the light-emitting elements 31 that are generating through current). The number of simultaneous light emission elements is the number of light-emitting elements 31 that are emitting light simultaneously, and since it can be determined from the light emission position and simultaneous light emission position, it does not necessarily need to be included. Note that magnetic flux strength information may also be included. When step S28 is completed, the series of processes is finished.

[0100] Thus, in Tx absolute correction, in order to reproduce the situation of current reduction in each light-emitting element 31 due to common impedance, only one light-emitting element 31 is actually made to emit light from the light-emitting unit 12A (Tx), so that the light receiving unit 13A (Rx) can acquire information on the light receiving timing without mixing the light from multiple light-emitting elements 31. At this time, the PMOS transistor 130 (Figure 7) of the individual drive circuit 111 is turned on to generate a through-current so that all but one of the simultaneously emitting light-emitting elements 31 do not emit light, and the light-emitting element 31 that emits light is sequentially switched to emit light only once among the simultaneously emitting light-emitting elements.

[0101] Figure 51 is a flowchart illustrating the distance measurement process. In the distance measurement process shown in Figure 51, the transmission / blocking switching unit 16 is in a light-blocking state, and multiple light-emitting elements 31 emit light simultaneously based on control from the light emission timing control unit 55 (S31). The reflected light pulse signals, which are the light pulse signals emitted by each of the multiple light-emitting elements 31 and reflected by the object 2, are received by multiple pixels 61 of the pixel array 51 (S32). Also, the AFE 35 detects the current due to the magnetic flux via the soft magnetic bus 32 (S32). Next, the signal processing unit 74 performs timing and detects, for example, the time difference between the timing corresponding to the Rx light emission command from the light emission timing control unit 55 and the timing when the light-receiving element 62 receives the reflected light pulse signal, and the time difference between the timing when the AFE 35 detects the magnetic flux (and the resulting current) (S33).

[0102] Then, it is determined whether the processes in steps S31 to S33 have been repeated a third predetermined number of times (for example, 100,000 times) (S34). If it is determined that the processes have been repeated a third predetermined number of times, it is determined whether the simultaneous emission number assignment has been completed (S35). If it is determined that the simultaneous emission number assignment has not been completed, the process returns to step S31 and the above process is repeated. On the other hand, if it is determined that the simultaneous emission number assignment has been completed, the processes from step S36 onwards are executed. For example, in the example in Figure 50, when the processes in steps S31 to S34 have been executed for all sets of simultaneous emission (light-emitting elements with the same simultaneous emission number), it is determined that the simultaneous emission number assignment has been completed (S35: Yes).

[0103] The signal processing unit 74 corrects the time difference in the emission timing of the multiple light-emitting elements 31 based on the Rx relative correction information, the Tx absolute correction value information, and the magnetic flux timing information (S36). For the correction, the absolute delay (Tx individual delay amount) of each light-emitting element 31, which is linked to the Rx in-plane time difference (relative value), emission position, and simultaneous emission position, is required as input, and this information is included in the Rx relative correction information and the Tx absolute correction value information. Here, correction can be performed using a table generated from this correction information. Alternatively, the table may be approximated using machine learning such as a Neural Network (NN), or the overall trend may be learned and the individual trends corrected. Note that a Deep Neural Network (DNN) may be used as the NN.

[0104] Then, the signal processing unit 74 measures the distance to object 2 based on the light emission timing of the multiple light-emitting elements 31 corrected based on the Rx relative correction information, Tx absolute correction value information, and magnetic flux timing information, and the light-receiving timing of the reflected light pulse signals at the multiple photodetectors 62, and outputs the distance measurement result (S37). When step S37 is completed, the series of processes is finished. Note that statistical data needs to be acquired in order to perform centroid calculation of the histogram, and one light-emitting element 31 needs to emit light a number of times specified as the first predetermined number, second predetermined number, and third predetermined number (for example, 10,000 to 100,000 times).

[0105] Here, the details of the first correction will be explained with reference to Figures 52 to 56. In the following explanation, the pixel 61 at coordinates (i, j) in the pixel array 51 may be referred to as pixel (i, j).

[0106] In the Rx relative correction process, the Rx in-plane time difference is calculated, and information regarding the relative delay of Rx is obtained. Since the delay time is a statistical value, the reception time is calculated from the centroid of the histogram for each pixel 61 in the pixel array 51. Figure 52A is a diagram that visually represents whether each pixel 61 in the pixel array 51 is relatively fast or slow using grayscale. In reality, it is a table that only contains information on the variability obtained by subtracting the average value of the pixel's reaction time from the pixels at each position in the pixel array 51. Figure 52B shows the reception time calculated from the centroid of the histogram. As shown in Figure 53, by subtracting the information regarding the relative delay of Rx obtained in the Rx relative correction process for each pixel 61 in the pixel array 51, it is possible to treat it as an ideal pixel without a systematic delay time (Rx shown at the end of arrow A1 in Figure 53). The Tx absolute correction process is performed based on the assumption of such an ideal pixel.

[0107] In the Tx absolute correction process, the light-emitting element 31 emits light independently, while the other light-emitting elements 31 do not emit light and a through-current flows. A table is obtained containing information such as the time from the Rx emission command to light reception (hereinafter also referred to as the light reception time), the time from the Rx emission command to the rise of the magnetic flux (hereinafter also referred to as the magnetic flux waveform rise time), and the average value of the magnetic flux waveform peak intensity. Figure 54 schematically shows the table obtained for each light-emitting element 31 that emitted light independently. In the multiple tables shown in the upper section, of the eight squares of interest, the upper left white square represents a light-emitting element 31 that emitted light independently, and the remaining black squares represent light-emitting elements 31 through-current flowing. The light reception time and magnetic flux waveform rise time are statistical information and therefore require histogram processing. The average value of the magnetic flux waveform peak intensity is statistical information, but since it is only within the scope of condition confirmation, an average value is sufficient.

[0108] And as long as the temperature is the same and the position and number of the light-emitting elements that become the through-current are the same, the rise time of the magnetic flux waveform can be regarded as constant from the rise time of the magnetic flux waveform, so individual variations can be subtracted. As a result, individual variations in the delay time from the Rx light emission command, the light emission of the light-emitting element 31, to the light reception of the light-receiving element 62 can be canceled (Tx shown at the tip of arrow A2 in FIG. 54).

[0109] Here, FIG. 55 shows the light reception time and magnetic flux waveform observed in the Tx absolute correction process. Since the transmission / shutter switching unit 16 is in the transmission state, the light reception time is the time via an LCD or the like. As shown in FIG. 55, when the Rx light emission command, the light reception time, and the magnetic flux waveform are represented on the same time axis, the time (t2: light reception time) from the Rx light emission command (T Fire ) to light reception is T Rx2i,j , and the time (t1: magnetic flux waveform rise time) from the Rx light emission command (T Fire ) to the rise of the magnetic flux is T B2i,j . Here, as shown at the tips of arrows A3 and A4 in FIG. 55, the centroid calculation of the histogram is performed, and the difference (T Rx2i,j - T B2i,j ) between the light reception time and the magnetic flux waveform rise time is obtained. These times are based on the Rx light emission command (T Fire ).

[0110] In the distance measurement process, distance measurement is performed in a state where individual variations in the delay time from the Rx light emission command, the light emission of the light-emitting element 31, to the light reception of the light-receiving element 62 are canceled by correction based on the correction information. Here, if the flow of the first correction described above is shown using mathematical formulas, it is as follows.

[0111] That is, in the Rx relative correction process, the individual centroid (T Rxi,j ) of the response time is obtained from the histogram of each pixel 61 of the pixel array 51 (FIG. 52). Also, the average value of the response time is calculated by Equation (5). However, in Equation (5), n represents the number of pixels for which the average value is to be obtained.

[0112]

[0113] Then, as shown in equation (6), the calculated average value is subtracted from the reaction time of each pixel 61 (individual pixel) in the pixel array 51, and information indicating how much faster or slower the pixel 61 at each position is compared to the average (the value calculated by equation (6)) is recorded in a table.

[0114]

[0115] At this time, temperature information is also recorded when the table is created. Since histogram information can be discarded at this point, memory usage is reduced. Finally, in the distance measurement process, the information recorded in the table (the value calculated by equation (6)) is added to correct the data to a state with no variation (Figure 53).

[0116] Furthermore, the Tx absolute correction process yields a table containing the reception time, magnetic flux waveform rise time, and average value of the magnetic flux waveform peak intensity (Figure 54). The reception time is the time from the Rx emission command to reception of light, and is calculated by equation (7). The magnetic flux waveform rise time is the time from the Rx emission command to the rise of the magnetic flux, and is calculated by equation (8). The average value of the magnetic flux waveform peak intensity is B peak.ave It is represented as follows.

[0117]

[0118]

[0119] Then, the centroid of the histogram is calculated, and the difference between the light reception time and the magnetic flux waveform rise time is calculated using equation (9) (Figure 55).

[0120]

[0121] At this time, the temperature is within a certain range (e.g., ±1°C), the rise time of the magnetic flux waveform is within a certain range, and the average value of the peak intensity of the magnetic flux waveform (B peak.ave As long as ) is within a certain range and within a certain time, after correction, the difference between the light reception time and the magnetic flux waveform rise time (T Rx2i,j - T B2i,j ) can be treated as a constant value. In distance measurement processing, the centroid time of the magnetic flux rise (T B3i,j ) to the said difference (T Rx2i,j - T B2i,jThe time obtained by adding the above can be treated as the zero second (=0 mm) of ToF (time at zero distance). The reason for keeping the magnetic flux waveform rise time and the average value of the magnetic flux waveform peak intensity within a certain range is that, for example, the wiring resistance may increase due to the temperature rise of the light-emitting part 12 (Tx chip), which may cause the supply voltage at the light-emitting point to decrease. The reason for keeping it within a certain time is, for example, to consider degradation, and because there is basically only one temperature measurement point in the chip, it may be difficult to accurately determine the temperature at a point far from the measurement point, so a correction is made after a certain amount of time has elapsed.

[0122] In the distance measurement process, distance measurement is performed with individual variations in the delay time from the Rx light emission command, the light emission of the light-emitting element 31, to the reception of light by the photodetector 62 canceled out by correction based on the correction information. The corrected period T of pixels (i, j) of the pixel array 51 ToFi,j This can be calculated using formula (10).

[0123]

[0124] Here, Figure 56 shows the light reception time and magnetic flux waveform observed during the distance measurement process. Since the transmission / blocking switching unit 16 is in a light-blocking state, the light reception time is considered to be the time that has passed through object 2. As shown in Figure 56, the corrected period T ToFi,j This is calculated by formula (10). In Figure 56, T Rx3i,j This is the light reception time (t4: time from Rx emission command to light reception), i.e., the centroid time of the light reception histogram. B3i,j This is the magnetic flux waveform rise time (t3: time from Rx light emission command to magnetic flux rise), that is, the histogram centroid time of the magnetic flux waveform rise time.

[0125] Also, T Rx2i,j This is the light reception time when the light-emitting element 31 emits light individually (other light-emitting elements 31 emit through current), i.e., the centroid time of the light reception histogram. B2i,j This is the rise time of the magnetic flux waveform when a single light-emitting element 31 is emitting light (other light-emitting elements 31 are emitting through current), i.e., the centroid time of the histogram. The relationship between these is as shown in equation (9). Also, T Rx1i,j ,T Rx1.aveThis is as shown in equation (6). In this way, in the distance measurement process, the distance to object 2 is calculated based on the correction information obtained in the Rx relative correction process and the Tx absolute correction process, the light emission timing of the multiple light-emitting elements 31 corrected based on the magnetic flux timing information corresponding to the magnetic flux information detected by the AFE 35, and the light reception timing corresponding to the reflected light pulse signal received by the multiple light-receiving elements 62. The correction information is generated based on the correlation between light reception timing information, which is information regarding the timing of the light pulse signal received by the multiple light-receiving elements 62, and magnetic flux timing information, which is information regarding the timing of the magnetic flux detected by the AFE 35. The correction information includes Rx relative correction information (for example, information on the Rx in-plane time difference) and Tx absolute correction value information (for example, information on the Tx individual delay amount).

[0126] Furthermore, the distance measurement processing unit 52 can reduce the amount of information stored in the memory 73 for each process by using the following information. Specifically, in the Rx relative correction process, only the value calculated by equation (6) is stored in the memory 73, and the histogram information shown in Figure 52B can be deleted. In the Tx absolute correction process, at least the values ​​calculated by equations (7) and (8) are stored in the memory 73, and the histogram information shown in Figure 55 can be deleted.

[0127] In the distance measurement process, the histogram information for light reception and the histogram information for magnetic flux, as shown in Figure 56, are stored in the memory 73. In other words, only two histograms are needed: one for light reception and one for magnetic flux. Generally, the number of pixels 61 in the pixel array 51 is greater than or equal to the number of light-emitting elements 31 (because multiple pixels 61 may correspond to one light-emitting element 31), so the number of light reception histograms will be equal to or greater than the number of magnetic flux histograms, and a proportional amount of memory will be required.

[0128] In the distance measuring device 1, calibration is performed each time there is a change in conditions, so even if temperature information is not acquired, data is acquired with information that includes it, making it not essential. However, it is necessary to retain temperature information when accumulating past data in a table or when using a Neural Network (NN) as an approximator for the table. In addition, temperature can cause changes in the physical properties of the light-emitting element, which may affect the light emission delay, and it is desirable to provide temperature measuring units 25 and 59 to detect that the permeability of soft magnetic materials and magnetic flux saturation density are temperature-dependent.

[0129] <<Principle of the Second Correction>> Figure 57 is a diagram illustrating the overall flow of the second correction. In Figure 57, as in Figure 46, the off state, Tx absolute correction, and distance measurement are illustrated. That is, since the second correction does not perform Rx relative correction compared to the first correction described above, when the system switches from the off state to the on state, Tx absolute correction and distance measurement are performed in that order. Here, since correction information for Rx relative correction can also be obtained by performing Tx absolute correction, the case in which Rx relative correction is not performed is shown.

[0130] Figure 58 is a flowchart illustrating the flow of the Tx absolute correction process. In steps S51 to S57, steps S51 to S55 are repeated until it is determined that the through-current distribution and simultaneous emission number distribution are complete (S56: Yes, S57: Yes), similar to steps S21 to S27 in Figure 49. Then, the signal processing unit 74 acquires (generates) correction information based on the calculation result of step S55 (S58). For example, as shown in Figure 59, when eight light-emitting elements 31 are emitted simultaneously, only one light-emitting element 31 actually emits light, and the remaining seven light-emitting elements 31 are treated as through-currents. Here, the Tx individual delay amount and Rx in-plane time difference are acquired as correction information. In addition to the Tx individual delay amount and Rx in-plane time difference, the correction information also includes the emission position, simultaneous emission position, and number of simultaneous emission elements. The correction information may also include temperature information and magnetic flux strength information. When step S58 is completed, the series of processes is finished.

[0131] Figure 60 is a flowchart illustrating the distance measurement process. In steps S61 to S65, steps S61 to S64 are repeated until it is determined that simultaneous light emission numbering is complete (S65: Yes), similar to steps S31 to S35 in Figure 51. The signal processing unit 74 then corrects the time difference in the light emission timing of the multiple light-emitting elements 31 based on the correction information and magnetic flux timing information (S66). This correction information includes the Tx individual delay amount and the Rx in-plane time difference. The signal processing unit 74 measures the distance to object 2 based on the light emission timing of the multiple light-emitting elements 31 corrected based on the correction information and magnetic flux timing information, and the reception timing of the reflected light pulse signals at the multiple photodetectors 62, and outputs the distance measurement result (S67). When step S67 is completed, the series of processes is finished.

[0132] Here, we will explain the details of the second correction with reference to Figures 61 to 64. Unlike the first correction described above, in the Tx absolute correction process, the Tx absolute correction is performed without performing the Rx relative correction. As shown in Figure 61, the Tx absolute correction process yields a table containing information such as the time from the Rx emission command to the reception of light (reception time), the time from the Rx emission command to the rise of the magnetic flux (magnetic flux waveform rise time), and the average value of the magnetic flux waveform peak intensity. Since the reception time and magnetic flux waveform rise time are statistical information, histogram processing is necessary. For the average value of the magnetic flux waveform peak intensity, an average value is acceptable.

[0133] Furthermore, as long as the temperature is the same and the position and number of light-emitting elements that become through-currents are the same, the magnetic flux waveform rise time and the light reception time can be considered constant, so individual variations can be subtracted. This makes it possible to cancel out individual variations in the delay time from the Rx light emission command to the emission of light from the light-emitting element 31 and the light reception of the light-receiving element 62 (Tx shown at the end of arrow A11 in Figure 61). Figure 62, similar to Figure 55, shows the light reception time and magnetic flux waveform observed in the Tx absolute correction process, and as shown at the end of arrows A12 and A13, the centroid calculation of the histogram is performed, and the difference between the light reception time and the magnetic flux waveform rise time (T Rx2i,j - T B2i,j ) can be calculated.

[0134] However, although the individual variations in the delay time from the Rx emission command to the emission of light from the light-emitting element 31 and the reception of light by the photodetector 62 have been corrected, the relative variations of the pixels 61 remain, making the correction incomplete (Tx shown at the end of arrow A11 in Figure 61). Here, the transmission / blocking switching unit 16 is in the transmission state, and light is incident on other pixels 61 (photodetector 62), so this information is stored as a histogram to obtain the relative variations of the pixels 61. Then, by correcting this relative variation, it is finally possible to correct the relative variations of the pixels 61 along with the individual variations in the delay time from the Rx emission command to the emission of light from the light-emitting element 31 and the reception of light by the photodetector 62 (Rx shown at the end of arrow A14 in Figure 63). In making these corrections, the latter value (a value corresponding to the relative variation of pixels 61) should be subtracted from the former value (a value corresponding to the state in which the individual variations in delay time have been corrected, but the relative variations of pixels 61 remain). In the second correction, when any of the light-emitting elements 31 emit light, the result is stored in a histogram. It is not necessary to create a histogram for every single emission, but it is necessary to keep it in memory 73 because subtraction is performed at the end.

[0135] In the distance measurement process, the distance is measured while canceling out individual variations in the delay time from the Rx light emission command, the light emission of the light-emitting element 31, to the reception of light by the light-receiving element 62 through correction based on the correction information. The flow of the second correction described above can be shown using mathematical formulas as follows.

[0136] In other words, the Tx absolute correction process yields a table containing the reception time, magnetic flux waveform rise time, and average value of the magnetic flux waveform peak intensity (Figure 61). However, the average value of the magnetic flux waveform peak intensity is not always necessary. The reception time is the time from the Rx emission command to reception of light, and is calculated by equation (7) above. The magnetic flux waveform rise time is the time from the Rx emission command to the rise of the magnetic flux, and is calculated by equation (8) above. The average value of the magnetic flux waveform peak intensity is B peak.ave It is represented as follows.

[0137] Then, the centroid of the histogram is calculated, and the difference between the light reception time and the magnetic flux waveform rise time is calculated using the above equation (9) (Figure 62). At this time, as long as the temperature is within a certain range, the magnetic flux waveform rise time is within a certain range, the average value of the magnetic flux waveform peak intensity is within a certain range, and it is within a certain time, the difference between the light reception time and the magnetic flux waveform rise time (T) after correction is calculated. Rx2i,j - T B2i,j ) can be treated as a constant value. In distance measurement processing, the centroid time of the magnetic flux rise (T B3i,j ) to the said difference (T Rx2i,j - T B2i,j The time added to this can be treated as zero seconds in ToF (Figure 64).

[0138] Furthermore, in the Tx absolute correction process, the individual centroids of the reaction time (T) are calculated from the histogram of each pixel 61 in the pixel array 51. Rxi,j ) is obtained (Figure 63). In addition, the average reaction time is calculated by the above formula (5). As shown in the above formula (6), the calculated average is subtracted from the reaction time of each pixel 61 (individual pixel) of the pixel array 51, and information indicating how much faster or slower each pixel 61 is than the average is recorded in the table. At this time, temperature information at the time of table creation may also be recorded. Finally, by adding the information recorded in the table (values ​​calculated by formula (6)), it is possible to correct to a state without variation (Figure 63).

[0139] In the distance measurement process, distance measurement is performed with individual variations in the delay time from the Rx light emission command, the light emission of the light-emitting element 31, to the reception of light by the photodetector 62 canceled out by correction based on the correction information. The corrected period T of pixels (i, j) of the pixel array 51 ToFi,j This can be calculated using the above formula (10) (Figure 64).

[0140] In the distance measurement processing unit 52, the amount of information to be stored in the memory 73 for each process can be reduced by using the following information. That is, in the Tx absolute correction process, the value calculated by the above equations (7) and (8), and B peak.aveOnly the value of can be stored in memory 73, and the histogram information shown in Figure 62 can be erased. As with the first correction described above, if the relative variation of the pixels 61 is obtained in advance, the amount of memory can be reduced by storing only the centroid time after histogram processing. However, in the second correction, it is necessary to store the histogram of the Rx relative correction in parallel with the histogram of the Tx absolute correction (two histograms for light reception are required), so it is necessary to secure memory for that purpose.

[0141] In the distance measurement process, the histogram information for light reception and the histogram information for magnetic flux, as shown in Figure 64, are stored in memory 73. In other words, two histograms are sufficient: one for light reception and one for magnetic flux.

[0142] <<Principle of the Third Correction>> Figure 65 is a diagram showing the overall flow of the third correction. In Figure 65, as in Figure 46, the off state, Rx relative correction, Tx absolute correction, and distance measurement are illustrated. That is, in the third correction, as with the first correction described above, when the state changes from the off state to the on state, Rx relative correction, Tx absolute correction, and distance measurement are performed in that order. However, in the Rx relative correction, Tx absolute correction, and distance measurement processes, RoI emission occurs when the light-emitting element 31 within the pre-set RoI region emits light.

[0143] Figure 66 is a flowchart illustrating the flow of the Rx relative correction process during RoI. In steps S81 to S87, steps S81 to S86 are repeated until it is determined that M = M_max (S87: Yes), similar to steps S11 to S17 in Figure 47. At this time, the light-emitting elements 31 outside the RoI region can be skipped, and for example, as shown in Figure 67, the light-emitting elements 31 within the RoI region 401 can be made to emit light to calculate the Rx in-plane time difference. Alternatively, as shown in Figure 68, only the light-emitting elements 31 in a specific region 411 within the RoI region 401 can be made to emit light to calculate the Rx in-plane time difference. Then, the signal processing unit 74 acquires (generates) Rx relative correction information based on the calculation result of step S86 (S88). When step S88 is completed, the series of processes is finished.

[0144] Figure 69 is a flowchart illustrating the flow of the absolute Tx correction process during RoI. In the absolute Tx correction process in Figure 69, it is determined whether or not the light-emitting element 31 is subject to skipping (S91). If the light-emitting element 31 is within the RoI region, the processes from step S92 onward are executed. In steps S92 to S98, steps S92 to S96 are repeated until it is determined that the through-current distribution and simultaneous emission number distribution have been completed (S97: Yes, S98: Yes), similar to steps S21 to S27 in Figure 49.

[0145] For example, as shown in Figure 70, the Tx individual delay amount can be calculated by illuminating one light-emitting element 31 within the RoI region 401 and allowing a through-current to flow through the other light-emitting elements 31. Note that when RoI illumination occurs, there are light-emitting elements 31 that do not emit light from the beginning, so in that case, depending on the RoI setting, the number of simultaneously illuminating light-emitting elements 31 may not be constant between patterns. Also, if there are light-emitting elements 31 that do not emit light, the number of simultaneously illuminating elements may differ from when RoI is not set, so the effect of common impedance can be reproduced by controlling the other light-emitting elements 31 to not emit light (generating a through-current) except for one light-emitting element 31 with the number of simultaneously illuminating elements when RoI is set. When RoI illumination occurs, there are light-emitting elements 31 that do not emit light from the beginning, but if the interpolation accuracy is practically acceptable, it is not necessary to illuminate all light-emitting elements 31. Then, the signal processing unit 74 acquires (generates) Tx absolute correction information based on the calculation result of step S96 (S99). When step S99 is completed, the series of processes is finished.

[0146] Figure 71 is a flowchart illustrating the distance measurement process during RoI. In the distance measurement process shown in Figure 71, it is determined whether or not the light-emitting element 31 is a target for skipping (S101). If the light-emitting element 31 is within the RoI region, the process from step S102 onwards is executed. In steps S102 to S106, steps S102 to S105 are repeated until it is determined that simultaneous light emission numbering is complete (S106: Yes), similar to steps S31 to S35 in Figure 51. The signal processing unit 74 then corrects the time difference in the light emission timing of the multiple light-emitting elements 31 based on the Rx relative correction information, Tx absolute correction value information, and magnetic flux timing information (S107). The signal processing unit 74 also measures the distance to object 2 based on the light emission timing of the multiple light-emitting elements 31 corrected based on the Rx relative correction information, Tx absolute correction value information, and magnetic flux timing information, and the reception timing of the reflected light pulse signals at the multiple photodetectors 62, and outputs the distance measurement result (S108). When step S108 is completed, the series of processes is finished.

[0147] The third correction differs from the first correction in that it limits the measurement to the RoI area rather than measuring all distance points. However, the details of the first correction, explained with reference to Figures 52 to 56, are basically the same as those of the third correction, so their explanation will be omitted.

[0148] <<Principle of the Fourth Correction>> Figure 72 is a diagram showing the overall flow of the fourth correction. In Figure 72, as in Figure 57, the off state, Tx absolute correction, and distance measurement are illustrated. That is, in the fourth correction, as with the second correction described above, when the state changes from off to on, Tx absolute correction and distance measurement are performed in that order. However, RoI emission occurs during the Tx absolute correction and distance measurement processes.

[0149] Figure 73 is a flowchart illustrating the flow of the absolute Tx correction process during RoI. In the absolute Tx correction process in Figure 73, it is determined whether or not the light-emitting element 31 is a target for skipping (S121). If it is a light-emitting element 31 within the RoI region, the process from step S122 onwards is executed. In steps S122 to S128, steps S122 to S126 are repeated until it is determined that the through-current distribution and simultaneous emission number distribution are complete (S127: Yes, S128: Yes), similar to steps S51 to S57 in Figure 58. For example, as shown in Figure 74, the Tx individual delay amount can be calculated by emitting light from one light-emitting element 31 within the RoI region 401, allowing through-current to flow through the other light-emitting elements 31. Then, the signal processing unit 74 acquires (generates) correction information based on the calculation result of step S126 (S129). The correction information includes the Tx individual delay amount, Rx in-plane time difference, etc. When step S129 is completed, the series of processes is finished.

[0150] Figure 75 is a flowchart illustrating the distance measurement process during RoI. In the distance measurement process shown in Figure 75, it is determined whether or not the light-emitting element 31 is a target for skipping (S141). If the light-emitting element 31 is within the RoI region, the process from step S142 onwards is executed. In steps S142 to S146, steps S142 to S145 are repeated until it is determined that simultaneous light emission numbering is complete (S146: Yes), similar to steps S61 to S65 in Figure 60. The signal processing unit 74 then corrects the time difference in the light emission timing of the multiple light-emitting elements 31 based on correction information and magnetic flux timing information (S147). This correction information includes the Tx individual delay amount and the Rx in-plane time difference. The signal processing unit 74 also measures the distance to object 2 based on the light emission timing of the multiple light-emitting elements 31 corrected based on the correction information and magnetic flux timing information, and the reception timing of the reflected light pulse signals at the multiple photodetectors 62, and outputs the distance measurement result (S148). When step S148 is completed, the series of processes is finished.

[0151] Note that the fourth correction differs from the second correction in that it limits the measurement to the RoI area rather than measuring all distance points. However, the details of the second correction, explained with reference to Figures 61 to 64, are basically the same as the details of the fourth correction, so the explanation will be omitted.

[0152] As described above, the distance measuring device 1 includes a light-emitting unit 12 having a plurality of light-emitting elements 31 that emit light pulse signals, a light-detecting unit 13 having a plurality of light-receiving elements 62 that receive reflected light pulse signals when the light-emitting pulse signals emitted from each of the plurality of light-emitting elements 31 are reflected by an object 2, and a transmission / blocking switching unit 16 provided between the light-emitting unit 12 and the light-detecting unit 13, which switches between transmitting and blocking the light-emitting pulse signals emitted from the light-emitting elements 31. The light-emitting unit 12 has a light-emitting array 21 in which a plurality of light-emitting elements 31 are arranged in a two-dimensional array, a soft magnetic bus 32 made of a soft magnetic material arranged on the plurality of light-emitting elements 31, and an AFE 35 that detects current due to magnetic flux via the soft magnetic bus 32. The light-detecting unit 13 has a distance measuring processing unit 52 that generates correction information to correct the time difference in the light emission timing of the plurality of light-emitting elements 31 based on light-receiving information corresponding to the light-emitting pulse signals received by the plurality of light-receiving elements 62 and magnetic flux information detected by the AFE 35 when the transmission / blocking switching unit 16 is in the transmission state. When the transmission / blocking switching unit 16 is in the blocked state, the distance measurement processing unit 52 calculates the distance to object 2 based on the light emission timing of the multiple light-emitting elements 31 corrected based on the correction information and magnetic flux information, and the light reception timing corresponding to the reflected light pulse signal received by the multiple light-receiving elements 62.

[0153] In the distance measuring device 1 configured as described above, it is assumed that black resin will be used to seal the Tx module (the part on the substrate of the light-emitting unit 12 in Figure 2 where the bumps 41 are formed). However, since the soft magnetic bus 32 is arranged to surround the bumps 41 of the light-emitting element 31, and the AFE 35 detects the current due to the magnetic flux via the soft magnetic bus 32, this does not pose a particular problem. In other words, the distance measuring device 1 estimates (detects) the light emission timing without directly detecting the light emission timing by converting the light emission current of the light-emitting element 31 into a magnetic flux for detection and obtaining the correlation between it and the light emission. Therefore, there is no problem even if black resin that does not transmit light is used for sealing. Furthermore, in a configuration using an optical waveguide, alignment accuracy between the light-emitting unit 12 and the photodetector 13 is required to be in units of 100 nm, requiring assembly precision. In contrast, in the distance measuring device 1, as shown in Figure 2, the AFE 35 of the light-emitting unit 12 and the TDC 71 of the photodetector 13 are connected by wiring 103, so there is no need to consider alignment accuracy. Therefore, the timing of light emission from multiple light-emitting elements 31 can be detected with a more appropriate configuration. The distance measuring device 1 may also be considered as a distance measuring system, and the light-emitting unit 12 may be configured as a light-emitting device and the light-detecting unit 13 as a light-detecting device.

[0154] The series of processes described above can be executed by hardware or by software. When the series of processes are executed by software, the programs constituting that software are installed on a computer. The programs executed by the computer (processor) can be provided, for example, by recording them on a removable recording medium such as a packaged media. Furthermore, the programs can be provided via wired or wireless transmission media such as a local area network or the internet.

[0155] In a computer, a program can be installed in a storage device by inserting a removable storage medium into a drive. Alternatively, a program can be received by a communication device via a wired or wireless transmission medium and installed in a storage device. Furthermore, programs can be pre-installed in ROM or other storage devices. In this specification, the processing performed by a computer according to a program does not necessarily have to follow the order described in the flowchart. The processing performed by a computer according to a program includes processing that is executed in parallel or individually (e.g., parallel processing or object-based processing). Also, a program may be processed by a single computer (processor) or processed in a distributed manner by multiple computers.

[0156] The embodiments described herein are not limited to those described above, and various modifications are possible without departing from the spirit of this disclosure. Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0157] Furthermore, this disclosure can take the following form.

[0158] (1) A distance measuring device comprising: a light-emitting unit having a plurality of light-emitting elements that emit light pulse signals; a light-detecting unit having a plurality of light-receiving elements that receive reflected light pulse signals when the light-emitting pulse signals emitted by each of the plurality of light-emitting elements are reflected by an object; and a switching unit provided between the light-emitting unit and the light-detecting unit, which switches between transmitting and blocking the light-emitting pulse signals emitted from the light-emitting elements, wherein the light-emitting unit has a light-emitting array in which the plurality of light-emitting elements are arranged in a two-dimensional array; a soft magnetic bus made of a soft magnetic material arranged around the plurality of light-emitting elements; and an analog circuit that detects a current due to magnetic flux via the soft magnetic bus, and the light-detecting unit has a processing unit that, when the switching unit is in a transmission state, generates correction information for correcting the time difference in the light emission timing of the plurality of light-emitting elements based on received light information corresponding to the light-emitting pulse signals received by the plurality of light-receiving elements and magnetic flux information detected by the analog circuit. (2) The distance measuring device according to (1), wherein the soft magnetic bus is arranged to surround light-emitting elements that do not emit light at the same time. (3) The distance measuring device according to (1) or (2), wherein the soft magnetic bath is arranged to surround the current-carrying portions of the plurality of light-emitting elements. (4) The distance measuring device according to any one of (1) to (3), wherein the soft magnetic bath is arranged to surround the plurality of light-emitting elements in multiple circles in a plan view, or to surround the plurality of light-emitting elements in multiple layers in a cross-sectional view. (5) The distance measuring device according to any one of (1) to (4), wherein the light-emitting unit or the light-detecting unit further has a disturbance cancellation mechanism for canceling disturbances. (6) The distance measuring device according to any one of (1) to (5), wherein at least one of the light-emitting unit and the light-detecting unit further has a temperature measuring unit, and the processing unit generates the correction information based on the temperature information measured by the temperature measuring unit.(7) The distance measuring device according to any one of (1) to (6), wherein the light detection unit further comprises a pixel array in which the plurality of light-receiving elements are arranged in a two-dimensional array, a drive circuit for driving the plurality of light-receiving elements, and a light emission timing control unit for controlling the drive circuit and a light emission control unit for controlling the light emission of the plurality of light-emitting elements, and the processing unit comprises a TDC for generating a time digital signal corresponding to the reception time of the reflected light pulse signal received by the plurality of light-receiving elements, a histogram generation unit for generating a histogram based on the time digital signal, and a signal processing unit for calculating the distance to the object based on the histogram. (8) The distance measuring device according to any one of (1) to (7), wherein the processing unit generates the correction information based on the correlation between reception timing information relating to the timing of the received light pulse signal and magnetic flux timing information relating to the timing of the magnetic flux. (9) The distance measuring device according to (8), wherein when the switching unit is in a shut-off state, the signal processing unit calculates the distance to the object based on the light emission timing of the plurality of light-emitting elements corrected based on the correction information and magnetic flux timing information corresponding to the magnetic flux information detected by the analog circuit, and the light reception timing corresponding to the reflected light pulse signal received by the plurality of light-receiving elements. (10) The distance measuring device according to (9), wherein the magnetic flux information includes magnetic flux waveform information relating to the waveform of the magnetic flux, and the subsequent stage of the analog circuit is connected to the TDC via a comparator and a buffer to convert the magnetic flux waveform information into magnetic flux timing information. (11) The distance measuring device according to (10), wherein the processing unit acquires magnetic flux intensity information relating to the intensity of the magnetic flux, and generates the correction information based on the magnetic flux intensity information. (12) The distance measuring device according to any one of (1) to (11), wherein a coil or a Hall element is used as the element used to detect the magnetic flux. (13) The distance measuring device according to any one of (1) to (12), wherein the switching unit is an LCD. (14) The distance measuring device according to any one of (1) to (13), wherein the processing unit regenerates the correction information when a predetermined condition change occurs.(15) The distance measuring device according to any one of (1) to (14), further comprising a control unit that controls whether to emit light from all of the plurality of light-emitting elements in the light-emitting array, or to emit light from the light-emitting element corresponding to the ROI region. (16) The distance measuring device according to any one of (1) to (14), wherein the correction information includes first correction information for correcting the relative delay time of the plurality of photodetectors and second correction information for correcting the delay time of each of the plurality of light-emitting elements. (17) The distance measuring device according to (16), wherein the processing unit performs, in that order, a first correction for correcting the relative delay time of the plurality of photodetectors and a second correction for correcting the delay time of each of the plurality of light-emitting elements based on the correction information. (18) The distance measuring device according to (16), wherein the processing unit performs a second correction for correcting the delay time of each of the plurality of light-emitting elements based on the correction information. (19) The distance measuring device according to (16) or (17), wherein the light-emitting unit has a light-emitting control unit that controls all or some of the plurality of light-emitting elements to emit light one by one in sequence when generating the first correction information. (20) The distance measuring device according to any one of (16) to (18), wherein the light-emitting unit has a light-emitting control unit that controls one of the simultaneously emitting light-emitting elements to emit light, while the remaining light-emitting elements do not emit light and a through-current flows, and sequentially switches the light-emitting element that emits light only one at a time.

[0159] 1 Distance measuring device, 2 Object, 11 Overall control unit, 12 Light-emitting unit, 12A Light-emitting unit, 13 Light detection unit, 13A Light-receiving unit, 14, 15 Lenses, 16 Transmission / blocking switching unit, 21 Light-emitting array (VCSEL array), 22 Drive circuit, 23 Clock generation unit, 24 Light emission control unit, 25 Temperature measurement unit, 31 Light-emitting element, 32, 32-1 to 32-n Soft magnetic bus, 33, 33-1 to 33-n Coil, 34 Disturbance cancellation mechanism, 35, 35-1 to 35-n AFE, 41 Bump, 51 Pixel array, 52 Distance measuring processing unit, 53 Control unit, 54 Clock generation unit, 55 Light emission timing control unit, 56 Drive circuit, 57 Distance measuring control unit, 58 Output buffer, 59 Temperature measurement unit, 61 Pixel, 62 Photodetector, 71 TDC, 72 Histogram generation unit, 73 Memory, 74 Signal processing unit, 110 Common drive circuit unit, 111, 111-1 to 111-3 Individual drive circuits, 191 Hall element, 192 Feedback winding

Claims

1. A distance measuring device comprising: a light-emitting unit having a plurality of light-emitting elements that emit light pulse signals; a light-detecting unit having a plurality of light-receiving elements that receive reflected light pulse signals when the light-emitting pulse signals emitted by each of the plurality of light-emitting elements are reflected by an object; and a switching unit provided between the light-emitting unit and the light-detecting unit, which switches between transmitting and blocking the light-emitting pulse signals emitted from the light-emitting elements, wherein the light-emitting unit has a light-emitting array in which the plurality of light-emitting elements are arranged in a two-dimensional array; a soft magnetic bus made of a soft magnetic material arranged around the plurality of light-emitting elements; and an analog circuit that detects a current due to magnetic flux via the soft magnetic bus, and the light-detecting unit has a processing unit that, when the switching unit is in a transmission state, generates correction information for correcting the time difference in the light emission timing of the plurality of light-emitting elements based on received light information corresponding to the light-emitting pulse signals received by the plurality of light-receiving elements and magnetic flux information detected by the analog circuit.

2. The distance measuring device according to claim 1, wherein the soft magnetic bath is arranged to surround light-emitting elements that do not emit light simultaneously.

3. The distance measuring device according to claim 1, wherein the soft magnetic bus is arranged to surround the current-carrying portions of the plurality of light-emitting elements.

4. The distance measuring device according to claim 1, wherein the soft magnetic bus is arranged to surround the plurality of light-emitting elements by multiple perimeters in a plan view, or to surround the plurality of light-emitting elements by multiple layers in a cross-sectional view.

5. The distance measuring device according to claim 1, wherein the light-emitting unit or the light-detecting unit further comprises a disturbance cancellation mechanism for canceling disturbances.

6. The distance measuring device according to claim 1, wherein at least one of the light-emitting unit and the light-detecting unit further comprises a temperature measuring unit, and the processing unit generates the correction information based on the temperature information measured by the temperature measuring unit.

7. The distance measuring device according to claim 1, wherein the light detection unit further comprises a pixel array in which the plurality of light-receiving elements are arranged in a two-dimensional array, a drive circuit for driving the plurality of light-receiving elements, and a light emission timing control unit for controlling the drive circuit and a light emission control unit for controlling the emission of light from the plurality of light-emitting elements, and the processing unit comprises a TDC for generating a time digital signal corresponding to the reception time of the reflected light pulse signal received by the plurality of light-receiving elements, a histogram generation unit for generating a histogram based on the time digital signal, and a signal processing unit for calculating the distance to the object based on the histogram.

8. The distance measuring device according to claim 7, wherein the processing unit generates the correction information based on the correlation between light reception timing information relating to the timing of the received light pulse signal and magnetic flux timing information relating to the timing of the magnetic flux.

9. The distance measuring device according to claim 8, wherein the signal processing unit calculates the distance to the object when the switching unit is in a shut-off state, based on the light emission timing of the plurality of light-emitting elements corrected based on the correction information and magnetic flux timing information corresponding to the magnetic flux information detected by the analog circuit, and the light reception timing corresponding to the reflected light pulse signal received by the plurality of light-receiving elements.

10. The distance measuring device according to claim 9, wherein the magnetic flux information includes magnetic flux waveform information relating to the waveform of the magnetic flux, and the subsequent stage of the analog circuit is connected to the TDC via a comparator and a buffer to convert the magnetic flux waveform information into magnetic flux timing information.

11. The distance measuring device according to claim 10, wherein the processing unit acquires magnetic flux intensity information relating to the intensity of the magnetic flux and generates the correction information based on the magnetic flux intensity information.

12. The distance measuring device according to claim 1, wherein a coil or a Hall element is used as the element for detecting the magnetic flux.

13. The distance measuring device according to claim 1, wherein the switching unit is an LCD.

14. The distance measuring device according to claim 1, wherein the processing unit regenerates the correction information when a predetermined condition change occurs.

15. The distance measuring device according to claim 1, further comprising a control unit that controls whether to emit light from all of the plurality of light-emitting elements in the light-emitting array, or to emit light from the light-emitting elements corresponding to the ROI region.

16. The distance measuring device according to claim 1, wherein the correction information includes a first correction information for correcting the relative delay time of the plurality of photoreceiving elements and a second correction information for correcting the delay time of each of the plurality of light-emitting elements.

17. The distance measuring device according to claim 16, wherein the processing unit performs, in order, a first correction for correcting the relative delay time of the plurality of light-receiving elements and a second correction for correcting the delay time of each of the plurality of light-emitting elements, based on the correction information.

18. The distance measuring device according to claim 16, wherein the processing unit performs a second correction based on the correction information to correct the delay time of each of the plurality of light-emitting elements.

19. The distance measuring device according to claim 16, wherein the light-emitting unit has a light-emitting control unit that controls all or some of the plurality of light-emitting elements to emit light one by one in sequence when generating the first correction information.

20. The distance measuring device according to claim 16, wherein the light-emitting unit has a light-emitting control unit that, when generating the second correction information, causes one of the simultaneously emitting light-emitting elements to emit light, while the remaining light-emitting elements do not emit light and a through-current flows, and also controls the sequential switching of the single light-emitting element that emits light.

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