Ranging system and light emitting element driver

Abstract

A distance measuring system for improving distance measurement accuracy is provided. A distance measuring system (70) includes a drive unit (24) that outputs a drive signal that causes a light emitting element to emit light to irradiate a target, a sensor section (302) that detects reflected light from the target, a measurement unit (23) that measures a delay time that is a time period included in a time period from a time at which a trigger signal for causing the light emitting element to emit light is output to a time at which the light emitting element actually emits light, and a distance measuring observation section (52) that is a processing section for performing a calculation of a distance to the target based on an output time of the trigger signal, a time at which the reflected light is received by the sensor section, and the delay time period.

Description

TECHNICAL FIELD

[0001] The present application relates to a distance measuring system and a driver of a light emitting element. BACKGROUND

[0002] A known distance measuring system measures a distance to an object by irradiating the object with light and detecting reflected light. For example, in Patent Literature 1, an object is irradiated with light from a light emitting unit, reflected light from the object is received by a light receiving sensor, and a distance to the object is measured based on time of flight (TOF).

[0003] LIST OF CITATIONS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: JP 2016-211881 A SUMMARY

[0006] TECHNICAL PROBLEM

[0007] However, the technology described in Patent Literature 1 has room for improvement in improving the accuracy of distance measurement.

[0008] Therefore, the present disclosure proposes a distance measuring system and a driver of a light emitting element that can improve the accuracy of distance measurement.

[0009] SOLUTION TO PROBLEM

[0010] The distance measuring system according to the present disclosure includes a driving unit that causes a light emitting element to emit light and outputs a driving signal for irradiating a target with light, a sensor unit that detects reflected light from the target, a measurement unit that measures a delay time included in a time from a timing at which a trigger signal for causing the light emitting element to emit light is output to a timing at which the light emitting element actually emits light, and a processing unit that performs processing of calculating a distance to the target based on an output timing of the trigger signal, a light reception timing of the reflected light obtained by the sensor unit, and the delay time.

[0011] The driver of a light emitting element according to the present disclosure includes a driving unit that causes a light emitting element to emit light and outputs a driving signal for irradiating a target with light, and a measurement unit that measures a delay time included in a time from a timing at which a trigger signal for causing the light emitting element to emit light is input to a timing at which the light emitting element actually emits light, wherein the driver outputs data corresponding to the delay time measured by the measurement unit. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a block diagram showing a configuration of an example of a distance measuring system applicable to each embodiment of the present disclosure.

[0013] Figure 2FIG. 1 is a diagram showing an example of a histogram showing times based on when a ranging sensor unit applied to a ranging system receives light.

[0014] Figure 3 FIG. 2 is a diagram showing an example of another ranging system of the present disclosure.

[0015] Figure 4 FIG. 3 is a diagram showing a configuration of main parts of the ranging system of the comparative example.

[0016] Figure 5 FIG. 4 is a diagram showing an operation example of the ranging system of the comparative example.

[0017] Figure 6 FIG. 5 is a diagram showing a ranging system according to a first embodiment of the present disclosure.

[0018] Figure 7 FIG. 6 is a timing chart showing an operation example of the ranging system according to the first embodiment.

[0019] Figure 8 FIG. 7 is a flowchart showing a first operation example of the ranging system according to the first embodiment.

[0020] Figure 9 FIG. 8 is a flowchart showing a second operation example of the ranging system according to the first embodiment.

[0021] Figure 10 FIG. 9 is a diagram showing a ranging system according to a first modification of the first embodiment.

[0022] Figure 11 FIG. 10 is a diagram showing a ranging system according to a second modification of the first embodiment.

[0023] Figure 12 FIG. 11 is a diagram showing a ranging system according to a third modification of the first embodiment.

[0024] Figure 13 FIG. 12 is a diagram showing a ranging system according to a fourth modification of the first embodiment.

[0025] Figure 14 FIG. 13 is a diagram showing a ranging system according to a fifth modification of the first embodiment.

[0026] Figure 15 FIG. 14 is a timing chart showing an operation example of the ranging system according to the fifth modification of the first embodiment.

[0027] Figure 16 FIG. 15 is a diagram showing a ranging system according to a sixth modification of the first embodiment.

[0028] Figure 17 FIG. 16 is a diagram showing a ranging system according to a seventh modification of the first embodiment.

[0029] Figure 18 FIG. 8 is a diagram showing a ranging system according to an eighth modification of the first embodiment.

[0030] Figure 19A FIG. 9 is a diagram showing a ranging system according to a ninth modification of the first embodiment.

[0031] Figure 19B FIG. 10 is a diagram showing a ranging system according to a tenth modification of the first embodiment.

[0032] Figure 19C FIG. 11 is a diagram showing a ranging system according to an eleventh modification of the first embodiment.

[0033] Figure 20 FIG. 12 is a diagram showing a ranging system according to a twelfth modification of the first embodiment.

[0034] Figure 21 FIG. 13 is a diagram showing a ranging system according to a thirteenth modification of the first embodiment.

[0035] Figure 22 FIG. 14 is a diagram showing a ranging system according to a second embodiment of the present disclosure.

[0036] Figure 23 FIG. 15 is a flowchart showing an operation example of the ranging system according to the second embodiment of the present disclosure.

[0037] Figure 24 FIG. 16 is a diagram for explaining an exemplary calculation of a delay time of the ranging system according to the second embodiment.

[0038] Figure 25 FIG. 17 is a diagram showing an example of rising timing of main signals of the ranging system according to the second embodiment.

[0039] Figure 26 FIG. 18 is a diagram showing a ranging system according to a first modification of the second embodiment.

[0040] Figure 27 FIG. 19 is a diagram showing a ranging system according to a second modification of the second embodiment.

[0041] Figure 28 FIG. 20 is a diagram showing a ranging system according to a third modification of the second embodiment.

[0042] Figure 29 FIG. 21 is a diagram showing a ranging system according to a fourth modification of the second embodiment.

[0043] Figure 30A FIG. 22 is a diagram showing a ranging system according to a fifth modification of the second embodiment.

[0044] Figure 30BFIG. 6 is a diagram showing a ranging system according to a first embodiment.

[0045] Figure 31 FIG. 7 is a diagram showing an example of a virtual load.

[0046] Figure 32A FIG. 8 is a diagram showing a ranging system according to a second embodiment.

[0047] Figure 32B FIG. 9 is a diagram showing a ranging system according to a sixth variation of the second embodiment.

[0048] Figure 33 FIG. 10 is a diagram showing a ranging system according to a seventh variation of the second embodiment.

[0049] Figure 34 FIG. 11 is a diagram showing a ranging system according to an eighth variation of the second embodiment.

[0050] Figure 35 FIG. 12 is a diagram showing a ranging system according to a ninth variation of the second embodiment.

[0051] Figure 36 FIG. 13 is a diagram showing a ranging system according to a tenth variation of the second embodiment.

[0052] Figure 37 FIG. 14 is a diagram showing an example in which a plurality of laser diodes are arranged in two dimensions.

[0053] Figure 38 FIG. 15 is a diagram showing a ranging system according to a ninth variation of the second embodiment.

[0054] Figure 39 FIG. 16 is a diagram for explaining the operation of a light emission waveform generation circuit.

[0055] Figure 40A FIG. 17 is a diagram showing a ranging system according to a third embodiment.

[0056] Figure 40B FIG. 18 is a diagram showing a ranging system according to a third embodiment.

[0057] Figure 40C FIG. 19 is a diagram showing a ranging system according to a third embodiment.

[0058] Figure 41 FIG. 20 is a diagram showing a ranging system according to a fourth embodiment. DETAILED DESCRIPTION

[0059] Hereinafter, embodiments of the present disclosure will be described in detail based on the drawings. Note that in each of the following embodiments, the same portions are denoted by the same symbols, and redundant description will be omitted.

[0060] Furthermore, the present disclosure will be described in the following item order.

[0061] 0. Embodiment-shared configuration

[0062] 0.1 Comparative example

[0063] 0.2 Configuration

[0064] 0.3 Operation

[0065] 1. First embodiment

[0066] 1.1 Configuration

[0067] 1.2 Operation

[0068] 1.2.1 First operation example

[0069] 1.2.2 Second operation example

[0070] 1.3 Effects

[0071] 1.4 First modification of the first embodiment

[0072] 1.4.1 Configuration

[0073] 1.4.2 Operation

[0074] 1.4.3 Effects

[0075] 1.5 Second modification of the first embodiment

[0076] 1.5.1 Configuration

[0077] 1.5.2 Operation

[0078] 1.5.3 Effects

[0079] 1.6 Third modification of the first embodiment

[0080] 1.6.1 Configuration

[0081] 1.6.2 Operation

[0082] 1.6.3 Effects

[0083] 1.7 Fourth modification of the first embodiment

[0084] 1.7.1 Configuration

[0085] 1.7.2 Operation

[0086] 1.7.3 Effects

[0087] 1.8 Fifth modification of the first embodiment

[0088] 1.8.1 Configuration

[0089] 1.8.2 Operation

[0090] 1.8.2.1 Operation Example

[0091] 1.8.3 Effect

[0092] 1.9 Sixth Modification of the First Embodiment

[0093] 1.9.1 Configuration

[0094] 1.9.2 Operation

[0095] 1.9.3 Effect

[0096] 1.10 Seventh Modification of the First Embodiment

[0097] 1.10.1 Configuration

[0098] 1.10.2 Operation

[0099] 1.10.3 Effect

[0100] 1.11 Eighth Modification of the First Embodiment

[0101] 1.11.1 Configuration

[0102] 1.11.2 Operation

[0103] 1.11.3 Effect

[0104] 1.12 Ninth Modification of the First Embodiment

[0105] 1.12.1 Configuration

[0106] 1.12.2 Operation

[0107] 1.12.3 Effect

[0108] 1.13 Tenth Modification of the First Embodiment

[0109] 1.13.1 Configuration

[0110] 1.13.2 Operation

[0111] 1.13.3 Effect

[0112] 1.14 Eleventh Modification of the First Embodiment

[0113] 1.14.1 Configuration

[0114] 1.14.2 Operation

[0115] 1.14.3 Effect

[0116] 2. Second Embodiment

[0117] 2.1 Configuration

[0118] 2.2 Operation

[0119] 2.3 Effects

[0120] 2.4 First Modification of the Second Embodiment

[0121] 2.4.1 Configuration

[0122] 2.4.2 Operation

[0123] 2.4.3 Effects

[0124] 2.5 Second Modification of the Second Embodiment

[0125] 2.5.1 Configuration

[0126] 2.5.2 Operation

[0127] 2.5.3 Effects

[0128] 2.6 Third Modification of the Second Embodiment

[0129] 2.6.1 Configuration

[0130] 2.6.2 Operation

[0131] 2.6.3 Effects

[0132] 2.7 Fourth Modification of the Second Embodiment

[0133] 2.7.1 Configuration

[0134] 2.7.2 Operation

[0135] 2.7.3 Effects

[0136] 2.8 Fifth Modification of the Second Embodiment

[0137] 2.8.1 Configuration

[0138] 2.8.2 Operation

[0139] 2.8.3 Effects

[0140] 2.9 Sixth Modification of the Second Embodiment

[0141] 2.9.1 Configuration

[0142] 2.9.2 Operation

[0143] 2.9.3 Effects

[0144] 2.10 Seventh Modification of the Second Embodiment

[0145] 2.10.1 Configuration

[0146] 2.10.2 Operation

[0147] 2.10.3 Effect

[0148] 2.11 Eighth Modification of Second Embodiment

[0149] 2.11.1 Configuration

[0150] 2.11.2 Operation

[0151] 2.11.3 Effect

[0152] 2.12 Ninth Modification of Second Embodiment

[0153] 2.12.1 Configuration

[0154] 2.12.2 Operation

[0155] 2.12.3 Effect

[0156] 2.13 Tenth Modification of Second Embodiment

[0157] 2.13.1 Configuration

[0158] 2.13.2 Operation

[0159] 2.13.3 Effect

[0160] 2.14 Eleventh Modification of Second Embodiment

[0161] 2.14.1 Configuration

[0162] 2.14.2 Operation

[0163] 2.14.3 Effect

[0164] 3. Third Embodiment

[0165] 4. Fourth Embodiment

[0166] 5. Summary

[0167] (0. Configuration Shared by Embodiments)

[0168] The present disclosure relates to control of a light emitting element (such as a laser diode) that emits light in response to current. Figure 1 is a block diagram showing a configuration of an example of a distance measuring system 70 applicable to each embodiment of the present disclosure. Note that in the following description, it is assumed that the light emitting element is a laser diode (LD). Laser diodes are applied to various fields such as distance measurement, optical transmission, and electrophotographic printers, with features such as excellent light straightness and light condensing properties, high response speed, and low power consumption. Note that the light emitting element applicable to the present disclosure is not limited to laser diodes. For example, a light emitting diode (LED) can also be applied as the light emitting element.

[0169] In Figure 1 the ranging system 70 as an electronic device includes a driver 10, a laser diode 12, a controller 11, a signal processing unit 51, and a ranging sensor unit 302.

[0170] The driver 10 drives the laser diode 12 according to a signal from the signal processing unit 51 to cause the laser diode 12 to emit light. For example, the controller 11 includes a central processing unit (CPU) and a memory, and supplies a control signal 40 generated by the CPU according to a program prestored in the memory to the driver 10 to control the driver 10.

[0171] The driver 10 generates a drive signal for driving the laser diode 12 to emit light in a pulse shape according to a signal supplied from the signal processing unit 51. The drive signal is input to the laser diode 12. The laser diode 12 emits light by the drive signal. That is, the laser diode 12 is caused to emit light based on the drive signal generated by the controller 11. The driver 10 transmits a signal indicating the timing of causing the laser diode 12 to emit light to the signal processing unit 51.

[0172] The controller 11 can determine whether an error has occurred based on a detection signal 42 supplied from the driver 10. For example, in a case where a measured delay time exceeds a determination reference value, it can be determined that an error has occurred. When it is determined that an error has occurred, the controller 11 can output an error signal. For example, the controller 11 can output the error signal to the outside of the ranging system 70.

[0173] The ranging sensor unit 302 functions as a sensor unit that detects reflected light from a target. The ranging sensor unit 302 includes a light-receiving element that outputs a light-receiving signal by photoelectric conversion based on received laser light. For example, a single-photon avalanche diode can be applied as the light-receiving element. The single-photon avalanche diode, also referred to as a SPAD, is characterized in that an electron generated in response to the incidence of one photon causes avalanche multiplication, thereby allowing a large current to flow. With this characteristic of the SPAD, the incidence of one photon can be detected with high sensitivity. The light-receiving element applicable to the ranging sensor unit 302 is not limited to the SPAD, and an avalanche photodiode (APD) or a general photodiode can also be applied.

[0174] The signal processing unit 51 calculates a distance D to a target 61 as a measurement target based on a time to when the laser diode 12 emits laser light t0 and a time t1 when the ranging sensor unit 302 receives light.

[0175] In the above configuration, for example, the laser 60 emitted from the laser diode 12 at the timing of time t0 is reflected by the target 61 and received as the reflected light 62 by the ranging sensor unit 302 at the timing of time t1. The signal processing unit 51 obtains the distance D to the target 61 based on the difference between the time t1 when the ranging sensor unit 302 receives the reflected light 62 and the time t0 when the laser diode 12 has emitted the laser. The distance D is calculated by the following equation (1), where the constant c is the speed of light (2.9979×10 [m / sec]).

[0176] D = (c / 2) × (t1 – t0) (1)

[0177] The signal processing unit 51 repeatedly executes the above processing multiple times. The ranging sensor unit 302 may include a plurality of light receiving elements, and may calculate the distance D based on each light receiving timing when each light receiving element receives the reflected light 62. The signal processing unit 51 classifies the time t from the light emission timing t0 to the light receiving timing t m (referred to as the light receiving time t m ) of the ranging sensor unit 302 receiving light based on bins, and generates a histogram.

[0178] Note that the light received by the ranging sensor unit 302 at the light receiving time t m is not limited to the reflected light (which 62 is the light emitted by the laser diode 12 and reflected by the target). For example, the ambient light around the ranging sensor unit 302 is also received by the ranging sensor unit 302.

[0179] Figure 2 is a diagram showing an example of a histogram applicable to the ranging system 70 based on the time when the ranging sensor unit 302 receives light. In Figure 2 , the horizontal axis represents bins, and the vertical axis represents the frequency of each bin. The bins are obtained by classifying the light receiving time t m [[ID=2�]]at each predetermined unit time d. Specifically, bin#0 is 0 ≤ t m < d, bin#1 is d ≤ t m < 2×d, bin#2 is 2×d ≤ t m < 3×d,..., and bin#(N - 2) is (N - 2)×d ≤ t m < (N - 1)×d. When the exposure time of the ranging sensor unit 302 is the time t ep , t ep = N×d. Note that N is a natural number.

[0180] The signal processing unit 51 obtains the light receiving time t based on bins mThe number of times is counted, the frequency 310 of each bin is obtained, and a histogram is generated. Here, the distance measuring sensor unit 302 also receives light other than reflected light that is light emitted from the laser diode 12 and reflected. Examples of such light other than target reflected light include ambient light. The portion indicated by the area 311 in the histogram includes an ambient light component attributable to ambient light. Ambient light is light that is randomly incident on the distance measuring sensor unit 302 and is noise with respect to target reflected light.

[0181] On the other hand, target reflected light is light received in accordance with a certain distance and appears in the histogram as an active light component 312. The bin corresponding to the frequency of the peak in the active light component 312 corresponds to the distance D to the target 61. The signal processing unit 51 can calculate the distance D to the target 61 in accordance with the above equation (1) by taking the representative time (for example, the time at the center of the bin) of the bin as the above time t1. In this way, by using a plurality of light reception results, for random noise, appropriate distance measurement can be performed.

[0182] Here, Figure 3 is a diagram showing an example of another distance measuring system 70' of the present disclosure. In Figure 3 In the distance measuring system 70' shown, the distance measuring sensor unit 302 is provided inside the signal processing unit 51 of the distance measuring system 70. That is, the signal processing unit 51 and the distance measuring sensor unit 302 are integrated. Hereinafter, a case where the signal processing unit 51 and the distance measuring sensor unit 302 are integrated will be described. Figure 1

[0183] (0.1 Comparative Example)

[0184] To facilitate understanding of the embodiments of the present disclosure, a comparative example will first be described.

[0185] [0.2 Configuration]

[0186] Figure 4 is a diagram showing the configuration of the main part of the distance measuring system of the comparative example. In Figure 4 The distance measuring system 70a of the comparative example includes the signal processing unit 51, the driver 10, and the laser diode 12. The signal processing unit 51 and the driver 10 are coupled by the coupling units 100a and 100b. The driver 10 and the laser diode 12 are coupled by the coupling unit 100c.

[0187] ​The signal processing unit 51 includes a phase-locked loop (PLL) unit 21, a light emission waveform generation circuit (Tgen) 22 as a light emission waveform generation unit, a time-to-digital converter (TDC) 23, a buffer B1, and the ranging sensor unit 302. The PLL unit 21 outputs a clock signal that serves as a reference for the operation of the ranging system 70a. For example, the PLL unit 21 includes a voltage-controlled oscillator that outputs a clock signal and controls the oscillation frequency of the clock signal based on a phase difference between the output clock signal and a reference signal that serves as a reference. The light emission waveform generation circuit 22 receives a trigger signal TRG' as an input. The light emission waveform generation circuit 22 generates a light emission pattern signal for causing the laser diode 12 to emit light. The light emission waveform generation circuit 22 outputs a count start signal Cntstart at the same time as the light emission pattern signal.

[0188] The TDC 23 outputs a digital signal corresponding to a time period from the timing at which the trigger signal TRG is input to the timing at which the ranging sensor unit 302 detects reflected light. The TDC 23 includes a counter for counting time, and counts time from the timing at which the count start signal Cntstart is input to the timing at which the ranging sensor unit 302 receives reflected light.

[0189] The buffer B1 includes, for example, two complementary metal-oxide semiconductor (CMOS) inverters connected in cascade. Alternatively, a differential buffer that conforms to a low-voltage differential signal (LVDS) standard can be used. The same applies to the buffers described below.

[0190] The driver 10 includes a buffer B2 and a drive unit (DRV) 24. The buffer B2 includes, for example, two CMOS inverters connected in cascade. The drive unit 24 outputs a drive signal for causing the laser diode 12 to emit light. More specifically, the drive unit 24 generates a drive current for causing the laser diode 12 to emit light, and supplies the drive current that has been generated as an output signal OUT to the laser diode 12.

[0191] The anode terminal of the laser diode 12 is connected to a power supply voltage V DD . The cathode terminal of the laser diode 12 is connected to the coupling unit 100c. Note that the anode terminal of the laser diode 12 can be connected to the coupling unit 100c, and the cathode terminal of the laser diode 12 can be connected to ground. In this case, the drive current flows from the drive unit 24 to the laser diode 12 via the coupling unit 100c.

[0192] [0.3Operation]

[0193] Figure 5 is a diagram illustrating Figure 4 an operation example of the ranging system 70a of the comparative example shown in FIG. 8. Figure 5is a diagram showing the timing of the rising of the trigger signal TRG and the rising of the output signal OUT. As shown in Figure 5 The timing of the rising of the trigger signal TRG does not coincide with the timing of the rising of the output signal OUT as shown in

[0194] The delay time Tpd1 is not constant due to fluctuations in the power supply and temperature environment and variations among the respective drivers 10. For example, as indicated by a broken line H1 in Figure 5 In the case where the timing of the rising of the output signal OUT is delayed from the timing Td1 and the output signal OUT rises at a timing Td2, the delay time of the output signal OUT with respect to the trigger signal TRG is a time Tpd2 as indicated by a broken line H2 in

[0195] In the distance measuring system 70a, adjustment is required to match the desired light emission timing with the actual light emission timing, and there is a possibility that the distance measuring accuracy decreases due to fluctuations in the propagation delay due to variations in the power supply and temperature environment. Furthermore, the propagation delay within the signal processing unit 51 and the propagation delay in the substrate can also fluctuate, which leads to a possibility that the distance measuring accuracy decreases. Therefore, in consideration of fluctuations in the propagation delay time due to variations in the power supply and temperature environment and among the respective drivers 10, it is necessary to improve the distance measuring accuracy.

[0196] (1. First Embodiment)

[0197] Next, a first embodiment of the present disclosure will be described. Figure 6 is a diagram showing a distance measuring system 70b according to the first embodiment of the present disclosure.

[0198] [1.1 Configuration]

[0199] In Figure 6 , the distance measuring system 70b includes a signal processing unit 51, a driver 10, and a laser diode 12. The driver 10 and the signal processing unit 51 can be manufactured integrally, or can be electrically connected to each other after being manufactured separately. The above is similarly applicable to the following embodiments. In this example, the signal processing unit 51 and the driver 10 are coupled by coupling units 100a and 100b and coupling units 100d and 100e.

[0200] The signal processing unit 51 includes the distance-measuring observation unit 52, the processing unit 53, and the distance-measuring sensor unit 302. The processing unit 53 includes the light-emission waveform generation circuit 22. The light-emission waveform generation circuit 22 as the light-emission waveform generation unit outputs the trigger signal TRG. The distance-measuring observation unit 52 calculates the distance D to the target 61 based on the output timing of the trigger signal TRG and the light-reception timing of the reflected light obtained by the distance-measuring sensor unit 302. The processing unit 53 controls each unit of the signal processing unit 51. Since the distance-measuring sensor unit 302 has been described, detailed description thereof will be omitted here. Figure 1 The distance-measuring sensor unit 302 is described, and therefore detailed description thereof will be omitted here.

[0201] The driver 10 includes the buffer B2, the TDC 23a, the drive unit 24, the logic unit 25, and the coupling unit 100f. The TDC 23a starts counting time by the trigger signal TRG and ends counting time when the drive unit 24 outputs the output signal OUT. The TDC 23a outputs digital data corresponding to the delay time as a measurement result of the counted time.

[0202] The logic unit 25 includes the storage unit 25M. The storage unit 25M stores digital data corresponding to the delay time as a measurement result of the TDC 23a. For example, the storage unit 25M includes a register. The storage unit 25M can be a memory. The clock signal Refclk as a reference of the operation of the TDC 23a is input to the coupling unit 100f.

[0203] In this embodiment, the processing unit 53 of the signal processing unit 51 is connected with the logic unit 25 of the driver 10 via the coupling units 100d and 100e. The processing unit 53 and the logic unit 25 can transmit and receive the input / output signal I / O. Therefore, the processing unit 53 of the signal processing unit 51 can access the storage unit 25M of the logic unit 25. Therefore, the processing unit 53 can acquire digital data corresponding to the delay time stored in the storage unit 25M of the logic unit 25.

[0204] [1.2 Operation]

[0205] The light emission waveform generation circuit 22 in the processing unit 53 of the signal processing unit 51 outputs a trigger signal TRG. The trigger signal TRG is input to the driver 10 via the coupling units 100a and 100b. When the trigger signal TRG is input, the TDC 23a in the driver 10 starts counting time. When the output unit 24 outputs the output signal OUT, the TDC 23a ends counting time. The TDC 23a outputs digital data corresponding to the delay time obtained by counting time. The TDC 23a transmits the digital data corresponding to the delay time to the logic unit 25. The logic unit 25 stores the digital data corresponding to the delay time acquired from the TDC 23a in the storage unit 25M.

[0206] The processing unit 53 of the signal processing unit 51 accesses the logic unit 25 of the driver 10 via the coupling units 100d and 100e. The processing unit 53 acquires the digital data of the delay time stored in the storage unit 25M of the logic unit 25. The processing unit 53 transmits the digital data of the delay time acquired from the storage unit 25M to the distance observation unit 52. The distance observation unit 52 calculates the distance D to the target 61 (hereinafter, can be referred to as distance measurement) using the digital data corresponding to the delay time. That is, the distance observation unit 52 performs distance measurement using the delay time. The distance observation unit 52 subtracts the digital data corresponding to the delay time acquired from the storage unit 25M from the time period from the timing at which the trigger signal TRG has been output to the timing at which the light is received by the distance sensor unit 302. As a result, it is possible to know the timing closer to the actual light emission timing without knowing the output timing of the trigger signal TRG, and thus it is possible to remove the delay time due to the internal circuit of the driver 10. As a result, it is possible to obtain the effect of improving the measurement accuracy of the distance D.

[0207] Figure 7 is a timing chart illustrating an operation example of the distance measurement system 70b according to Figure 6 is a timing chart illustrating an operation example of the distance measurement system 70b according to Figure 7 is a graph illustrating the contents stored in the storage unit 25M in the logic unit 25, the trigger signal TRG, the clock signal Refclk, and the output signal OUT.

[0208] In Figure 7In this example, the TDC 23a starts counting time at the timing at which the trigger signal TRG becomes high, that is, at the rising time Ttl. The TDC 23a counts time by counting the number of the clock signal Refclk. Then, the TDC 23a ends counting time at the timing at which the output signal OUT becomes high, that is, at the rising time Tdl. The TDC 23a transmits digital data of the time count value "Tpd1" to the logic unit 25. The logic unit 25 stores the digital data of the time count value in the storage unit 25M. Note that if the repetition period of the clock signal Refclk is made shorter, counting time can be performed more accurately. The TDC 23a can count the number of a signal other than the clock signal Refclk to count time.

[0209] The TDC 23a starts counting time at the timing at which the trigger signal TRG becomes high at a subsequent time, that is, at the rising time Tt2. The TDC 23a counts time by counting the number of the clock signal Refclk. Then, the TDC 23a ends counting time at the timing at which the output signal OUT becomes high, that is, at the rising time Td2. The TDC 23a transmits digital data of the time count value "Tpd2" to the logic unit 25. The logic unit 25 stores the digital data of the time count value "Tpd2" in the storage unit 25M.

[0210] Thereafter, digital data of the time count value of the TDC 23a is similarly stored in the storage unit 25M. The digital data of the time count value stored in the storage unit 25M is a delay time from the input trigger signal TRG to actual emission of the laser diode 12. That is, it is possible to measure the delay time as a reference Figure 5 The times Tpd1 and Tpd2 of the delay time described above are described, and digital data is stored in the storage unit 25M.

[0211] [1.2.1 First operation example]

[0212] An operation example of the entire distance measuring system 70b shown in Figure 6 will be described. Figure 8 is a flowchart showing a first operation example of the distance measuring system 70b according to Figure 6 the first embodiment shown in FIG. 6.

[0213] In Figure 8 In this example, the trigger signal TRG for causing the laser diode 12 to emit light is transmitted from the signal processing unit 51 to the driver 10 (step Sll).

[0214] The driver 10 receives the trigger signal TRG and starts counting time by the TDC 23a (step S12). The driver 10 outputs a drive signal for causing the laser diode 12 to emit light, stops the counting time of the TDC 23a at that timing, and obtains a delay time (step S13). The driver 10 stores digital data corresponding to the delay time in the storage unit 25M of the logic unit 25 (step S14).

[0215] The processing unit 53 of the signal processing unit 51 acquires the digital data corresponding to the delay time from the storage unit 25M in the logic unit 25 (step S15).

[0216] Next, it is determined whether or not the processing ends (step S16). If the processing does not end, the flow returns to step S11 and the above-described processing is performed (NO in step S16 → S11). If the processing ends, the processing ends (YES in step S16 → S17).

[0217] Note that the above-described processing is described with reference to Figure 8 The above-described processing can be performed each time the laser diode 12 is caused to emit light, or can not be performed each time but performed once each time the laser diode 12 is caused to emit light a predetermined number of times. The above-described processing can be performed at each predetermined time interval. The above-described processing can be performed only at the time of activation of the system and not performed thereafter.

[0218] [1.2.2 Second Operation Example]

[0219] Figure 9 is a flowchart showing a second operation example of the distance measuring system 70b according to Figure 6 the first embodiment shown in FIG. 8. In the second operation example, in a case where the measured delay time exceeds a determination reference value, the delay time abnormality is notified to the outside.

[0220] In Figure 9 , steps S11 to S14 are similar to the operation described with reference to Figure 8 It is determined whether or not the data of the delay time stored in the storage unit in step S14 exceeds a determination reference value (step S14a). If the data of the delay time does not exceed the determination reference value, the processing proceeds to step S15. In this case, the processing unit 53 of the signal processing unit 51 acquires the digital data corresponding to the delay time from the storage unit 25M in the logic unit 25 (step S15).

[0221] Next, it is determined whether or not the processing ends (step S16). If the processing does not end, the flow returns to step S11 and the above-described processing is performed (NO in step S16 → S11). If the processing ends, the processing ends (YES in step S16 → S17).

[0222] In step S14a, if the data of the delay time exceeds the determined reference value, the processing proceeds to step S18. In this case, the signal processing unit 51 stops the operation of the driving unit 24, notifies the outside of error information, and stores the error information in a predetermined register (step S18). The signal processing unit 51 confirms the error information stored in the register (step S19). Then, the processing proceeds to step S16.

[0223] Note that, with reference to Figure 9 The above-described processing described above can be executed every time the laser diode 12 is caused to emit light, or can not be executed every time but once every time the laser diode 12 is caused to emit light a predetermined number of times. The above-described processing can be executed every predetermined time interval. The above-described processing can be executed only at the time of activation of the system, and not thereafter.

[0224] [1.3 Effects]

[0225] By using the digital data of the delay time for calculating the distance D to the target 61, the distance-measuring observation unit 52 can not know the output timing of the trigger signal TRG, but a timing closer to the actual light emission timing. As a result, the distance-measuring observation unit 52 can eliminate the delay time attributed to the internal circuit of the driver 10. More specifically, the distance D to the target 61 can be calculated by measuring the delay time included in the time period from the output timing of the trigger signal TRG to the timing at which the light emission element actually emits light, based on the output timing of the trigger signal TRG, the light reception timing of the reflected light obtained by the distance sensor unit 302, and the delay time. As a result, an effect of improving the measurement accuracy of the distance D can be obtained. Furthermore, the delay time can be measured using the light emission pattern signal generated by the light emission waveform generation circuit 22a.

[0226] (1.4 First Modification of the First Embodiment)

[0227] Figure 10 is a view showing a distance-measuring system 70b' according to the first modification of the first embodiment described with reference to Figure 6 In the distance-measuring system 70b of the first modification, the storage unit 25M is included in the logic unit 25 of the driver 10. Meanwhile, the distance-measuring system 70b' of the second modification includes the storage unit 25M in the signal processing unit 51.

[0228] [1.4.1 Configuration]

[0229] The signal processing unit 51 of the distance-measuring system 70b' includes the storage unit 25M. The driver 10 does not include the storage unit 25M in the logic unit 25. The other configurations are similar to those of the distance-measuring system 70b described with reference to Figure 6 , and thus the description thereof will be omitted.

[0230] The storage unit 25M only needs to be provided in at least one of the signal processing unit 51 or the logic unit 25. The storage unit 25M can be provided in both the signal processing unit 51 and the logic unit 25, and the storage units 25M can exchange data.

[0231] [1.4.2 Operation]

[0232] The TDC 23a of the driver 10 transmits digital data of the time count value to the logic unit 25. The logic unit 25 transmits the digital data of the time count value to the signal processing unit 51. The signal processing unit 51 stores the digital data of the time count value in the storage unit 25M. Other operations are similar to the operations described with reference to Figure 7 、 8 and 9.

[0233] [1.4.3 Effects]

[0234] Since the storage unit 25M is provided in the signal processing unit 51, the area of the chip of the driver 10 can be reduced.

[0235] (1.5 Second Modification of the First Embodiment)

[0236] Figure 11 is a diagram illustrating a distance measuring system 70c according to the second modification of the first embodiment described with reference to Figure 6 .

[0237] [1.5.1 Configuration]

[0238] In Figure 11 , the distance measuring system 70c has the light emission waveform generation circuit 22a provided in the driver 10. That is, the distance measuring system 70b described with reference to Figure 6 has the light emission waveform generation circuit 22 provided in the processing unit 53 of the signal processing unit 51, while Figure 11 the distance measuring system 70c illustrated has the light emission waveform generation circuit 22a provided in the driver 10. When the trigger signal TRG' is input, the light emission waveform generation circuit 22a operates the drive unit 24. Other configurations are similar to the configuration of the distance measuring system 70b described with reference to Figure 6 , and thus the description thereof will be omitted.

[0239] [1.5.2 Operation]

[0240] The processing unit 53 of the signal processing unit 51 outputs the trigger signal TRG'. The trigger signal TRG' is input to the driver 10. When the trigger signal TRG' is input via the buffer B2, the light emission waveform generation circuit 22a operates the drive unit 24.

[0241] The TDC 23a counts time from when the trigger signal TRG' becomes high (i.e., the rising time) to when the output signal OUT output from the drive unit 24 becomes high (i.e., the rising time). The TDC 23a transmits digital data of the time count value to the logic unit 25. The logic unit 25 stores the digital data of the time count value in the storage unit 25M. Subsequent operations are similar to those described with reference to Figure 7 , 8 and 9.

[0242] [1.5.3 Effects]

[0243] By using the digital data corresponding to the delay time for calculating the distance D to the target 61, the distance-measuring observation unit 52 can not know the output timing of the trigger signal TRG, but a timing closer to the actual light emission timing. As a result, the distance-measuring observation unit 52 can eliminate the delay time due to the internal circuit of the driver 10. As a result, an effect of improving the measurement accuracy of the distance D can be obtained.

[0244] (1.6 Third Modification of the First Embodiment)

[0245] Figure 12 is a diagram showing a distance-measuring system 70c' according to a third modification of the first embodiment described with reference to Figure 6 . The distance-measuring system 70c of the second modification described with reference to Figure 11 has the storage unit 25M in the logic unit 25 of the driver 10. Meanwhile, the distance-measuring system 70c' of the third modification has the storage unit 25M in the signal processing unit 51.

[0246] [1.6.1 Configuration]

[0247] The signal processing unit 51 of the distance-measuring system 70c' includes the storage unit 25M. The driver 10 does not include the storage unit 25M in the logic unit 25. The other configuration is similar to that of the distance-measuring system 70c described with reference to Figure 6 , and thus the description thereof will be omitted.

[0248] [1.6.2 Operation]

[0249] The TDC 23a of the driver 10 transmits digital data of the time count value to the logic unit 25. The logic unit 25 transmits the digital data of the time count value to the signal processing unit 51. The signal processing unit 51 stores the digital data of the time count value in the storage unit 25M. The other operations are similar to those described with reference to Figure 7 , 8 and 9.

[0250] [1.6.3 Effects]

[0251] Since the storage unit 25M is provided in the signal processing unit 51, the area of the chip of the driver 10 can be reduced.

[0252] (1.7 Fourth Modification of the First Embodiment)

[0253] Figure 13 is a diagram illustrating a ranging system 70c' according to the fourth modification of the first embodiment described with reference to Figure 6 FIG. 8 is a diagram illustrating a ranging system 70c' according to the fourth modification of the first embodiment described with reference to

[0254] [1.7.1 Configuration]

[0255] Figure 13 The ranging system 70c' illustrated in FIG. 8 has a configuration in which the PLL unit 21a is added to the driver 10 of the ranging system 70c described with reference to Figure 11 FIG. 7. The PLL unit 21a receives the clock signal Refclk as input and outputs a clock signal Refclk' having a phase matching the phase of the clock signal Refclk.

[0256] The other configurations in the driver 10 are similar to those described with reference to Figure 11 FIG. 7. Note that, in Figure 13 FIG. 7, the configuration of the signal processing unit 51 is similar to that described with reference to Figure 11 FIG. 6. Thus, the explanation and description of the internal configuration of the signal processing unit 51 are omitted.

[0257] [1.7.2 Operation]

[0258] The PLL unit 21a receives the clock signal Refclk as input and outputs a clock signal Refclk' having a phase matching the phase of the clock signal Refclk. The clock signal Refclk' is input to the TDC 1. The TDC 1 counts time based on the clock signal Refclk'. The subsequent operation is similar to that described with reference to Figure 7 , 8 and 9.

[0259] [1.7.3 Effect]

[0260] By using the digital data of the delay time for calculating the distance D to the target 61, the ranging observation unit 52 can not know the output timing of the trigger signal TRG but know a timing closer to the actual emission timing. As a result, the ranging observation unit 52 can eliminate the delay time attributed to the internal circuit of the driver 10. As a result, the effect of improving the measurement precision of the distance D can be obtained.

[0261] (1.8 Fifth Modification of the First Embodiment)

[0262] Figure 14 is a diagram illustrating a ranging system 70c' according to the fourth modification of the first embodiment described with reference toFigure 6 FIG. of the ranging system 70d of the fifth modification of the first embodiment described.

[0263] [1.8.1 Configuration]

[0264] In Figure 11 , the ranging system 70d according to the fifth modification of the first embodiment includes a replica drive unit 24R that imitates the drive unit 24, separately from the original drive unit 24. The replica drive unit 24R has a structure similar to that of the drive unit 24. In this example, a path from the waveform generation circuit 22a to the drive unit 24 is branched, and the replica drive unit 24R is arranged in the middle of the branched path.

[0265] The replica drive unit 24R outputs a replica output signal OUTrep that simulates the output signal OUT output by the drive unit 24, based on a signal output by the waveform generation circuit 22a. The replica drive unit 24R either constantly outputs the replica output signal OUTrep (in the case of the first operation example described later), or operates similarly to the drive unit 24 and outputs the replica output signal OUTrep that is identical to the output signal OUT (in the case of the second operation example described later).

[0266] The other configurations in the driver 10 are similar to those described with reference to Figure 11 . Note that, in Figure 14 , the configuration of the signal processing unit 51 is similar to that described with reference to Figure 11 . Therefore, the explanation and description of the internal configuration of the signal processing unit 51 are omitted.

[0267] [1.8.2 Operation]

[0268] In Figure 11 , when the signal processing unit 51 outputs the trigger signal TRG', the trigger signal TRG' is input to the driver 10. The waveform generation circuit 22a in the driver 10 outputs a signal for causing the drive unit 24 and the replica drive unit 24R to output the output signal OUT and the replica output signal OUTrep, respectively. The drive unit 24 outputs the output signal OUT, and the replica drive unit 24R outputs the replica output signal OUTrep. The TDC 23a counts time from the time when the trigger signal TRG' rises, and ends counting time by the replica output signal OUTrep output from the replica drive unit 24R. The TDC 23a transmits digital data of the time count value to the logic unit 25. The logic unit 25 stores the digital data of the time count value in the storage unit 25M. The subsequent operation is similar to that described with reference to Figure 7 , 8 , and 9.

[0269] [1.8.2.1 Operation Example]

[0270] Figure 15 It shows the basis Figure 14 The timing diagram shows an operational example of the ranging system 70d in the fifth variation of the first embodiment. TDC 23a is the counting time from the time Tt when the trigger signal TRG' rises to the time Td2 when the replica output signal OUTrep rises. In this way, the delay time Tpd2 can be obtained.

[0271] [1.8.3 Effects]

[0272] There are situations where it is undesirable to provide a path branch to TDC 23a at the output side of the original driver unit 24 and the laser diode 12. For example, a path branching to TDC 23a might affect the current value of the output signal OUT of the laser diode 12. In this example, since the replica driver unit 24R is used to measure the delay time, it is possible to achieve an effect where this effect does not exist.

[0273] (1.9 Sixth variation of the first embodiment)

[0274] Figure 16 It shows according to the reference Figure 6 A figure of the ranging system 70e of the sixth variation of the first embodiment described.

[0275] [1.9.1 Configuration]

[0276] Figure 16 The ranging system 70e shown has a buffer BV added to the reference. Figure 14 The configuration of the ranging system 70d is described. A buffer BV is disposed on the input side of the replica drive unit 24R. The delay amount in the buffer BV is adjustable. The delay amount of the buffer BV is adjusted so that the delay time of the signal passing through the replica drive unit 24R and the buffer BV matches the delay time of the drive unit 24. The buffer BV serves as a delay adjustment unit for adjusting the delay time of the signal passing through the replica drive unit 24R.

[0277] Other configurations in driver 10 are similar to the reference. Figure 11 The configurations described. Note that in Figure 16 In this configuration, the signal processing unit 51 is similar to that in the reference design. Figure 11 The configuration described is omitted. Therefore, the description and explanation of the internal configuration of the signal processing unit 51 are omitted.

[0278] [1.9.2 Operation]

[0279] exist Figure 16When the signal processing unit 51 outputs the trigger signal TRG', the trigger signal TRG' is input to the driver 10. The waveform generation circuit 22a in the driver 10 outputs a signal for causing the drive unit 24 and the replica drive unit 24R to output the output signal OUT and the replica output signal OUTrep, respectively. The drive unit 24 outputs the output signal OUT, and the replica drive unit 24R outputs the replica output signal OUTrep.

[0280] Here, by adjusting the delay amount of the buffer BV, it is possible to match the timing at which the drive unit 24 outputs the output signal OUT that causes the laser diode 12 to emit light with the timing at which the replica output signal OUTrep is input to the TDC 23a from the buffer BV and the replica drive unit 24R.

[0281] The TDC 23a counts time from the time at which the trigger signal TRG' rises and ends counting time from the output timing at which the replica drive unit 24R outputs the replica output signal OUTrep. The TDC 23a transmits digital data of the time count value to the logic unit 25. The logic unit 25 stores the digital data of the time count value in the storage unit 25M. Subsequent operations are similar to the operations described with reference to Figure 7 、 8 and 9.

[0282] [1.9.3 Effects]

[0283] There are cases where it is undesirable to provide a path branched to the TDC 23a on the output side of the original drive unit 24 and the laser diode 12. For example, the path branched to the TDC 23a can affect the current value of the output signal OUT of the laser diode 12. In this example, since the replica drive unit 24R is used to measure the delay time, it is possible to obtain the effect that the influence does not exist.

[0284] Further, by adjusting the delay amount of the buffer BV, it is possible to match the timing at which the laser diode 12 emits light with the timing at which the replica output signal OUTrep is input to the TDC 23a. As a result, it is possible to more accurately measure the delay time, and it is possible to improve the distance measurement accuracy.

[0285] (1.10 Seventh Modification of the First Embodiment)

[0286] Figure 17 is a diagram that shows a distance measurement system 70f according to the seventh modification of the first embodiment described with reference to Figure 6

[0287] [1.10.1 Configuration]

[0288] Figure 17 The distance measurement system 70f shown in FIG. 9 has a configuration in which the temperature sensor 26 and the input buffer B​IN Added to the reference Figure 16 The configuration of the distance measuring system 70e described. The output signal of the input buffer B IN is input to the buffer B2, and is also input to the TDC 23a. The temperature sensor 26 detects the temperature of the driver 10. The delay amount of the buffer BV is adjusted based on the temperature of the driver 10 detected by the temperature sensor 26.

[0289] The other configurations in the driver 10 are similar to those described with reference Figure 11 to FIG. 6. Note that, in Figure 17 , the configuration of the signal processing unit 51 is similar to that described with reference Figure 11 to FIG. 6. Therefore, the explanation and description of the internal configuration of the signal processing unit 51 are omitted.

[0290] [1.10.2 Operation]

[0291] In Figure 17 , the temperature sensor 26 outputs a detection signal 260 corresponding to the temperature of the driver 10. The detection signal 260 is input to the buffer BV. The delay amount of the buffer BV is adjusted based on the detection signal 260. Even if the temperature of the driver 10 changes, the delay amount of the buffer BV is adjusted so that the delay time of the signal through the replica driver unit 24R and the buffer BV matches the delay time of the driver unit 24. The other operations are similar to those described with reference Figure 16 to FIG. 6.

[0292] [1.10.3 Effects]

[0293] There are cases where it is not desirable to provide a path branched to the TDC 23a on the output side of the original driver unit 24 and the laser diode 12. For example, the path branched to the TDC 23a can affect the current value of the output signal OUT of the laser diode 12. In this example, since the replica driver unit 24R is used to measure the delay time, it is possible to obtain the effect that this influence does not exist.

[0294] Further, by adjusting the delay amount of the buffer BV based on the temperature of the driver 10, it is possible to match the timing at which the laser diode 12 emits light and the timing at which the replica output signal OUTrep is input to the TDC 23a. As a result, it is possible to more accurately measure the delay time, and it is possible to improve the distance measuring accuracy.

[0295] (1.11 Eighth Modification of the First Embodiment)

[0296] Figure 18 is a diagram showing a distance measuring system 70g according to the eighth modification of the first embodiment described with reference Figure 6 to FIG. 6.

[0297] [1.11.1 Configuration]

[0298] Figure 18 The distance measuring system 70g illustrated has a configuration in which the signal on the input side of the drive unit 24 is input to the TDC 23a instead of the output signal of the drive unit 24. For example, in a case where the output signal OUT of the drive unit 24 cannot be used due to the installation environment of the driver 10, the signal on the input side of the drive unit 24 can be used to count time. That is, the output timing of the signal on the input side of the drive unit 24 ends the count time. In the present example, a buffer B3 is arranged between the light emission waveform generation circuit 22a and the drive unit 24, and the output signal 220 of the buffer B3 is input to the TDC 23a.

[0299] The other configurations in the driver 10 are similar to those described with reference to Figure 11 . Note that, in Figure 18 , the configuration of the signal processing unit 51 is similar to that described with reference to Figure 11 . Therefore, the explanation and description of the internal configuration of the signal processing unit 51 are omitted.

[0300] [1.11.2 Operation]

[0301] In Figure 18 , the processing unit 53 of the signal processing unit 51 outputs the trigger signal TRG'. The trigger signal TRG' is input to the driver 10. When the trigger signal TRG' is input via the buffer B2, the light emission waveform generation circuit 22a operates the drive unit 24.

[0302] The TDC 23a counts time from the timing at which the trigger signal TRG' becomes high (i.e., the rise time) to the timing at which the output signal 220 of the buffer B3 becomes high (i.e., the rise time). The TDC 23a transmits digital data of the time count value to the logic unit 25. The logic unit 25 stores the digital data of the time count value in the storage unit 25M. The subsequent operation is similar to the operation described with reference to Figure 7 , 8 , and 9.

[0303] [1.11.3 Effects]

[0304] In a case where the output signal of the drive unit 24 cannot be used due to the installation environment of the driver 10, by counting time using the signal on the input side of the drive unit 24, it is possible to improve the distance measuring accuracy.

[0305] (1.12 Ninth Modification of the First Embodiment)

[0306] Figure 19A , 19B , and 19C are diagrams illustratingFigure 6 A diagram of the ranging system 70h, 70h' and 70h” of the ninth variation of the first embodiment described.

[0307] [1.12.1 Configuration]

[0308] exist Figure 19A , 19B In 19C, the ranging systems 70h, 70h', and 70h" each include multiple laser diodes 121 to 12... N Multiple drive units 241 to 24 N (N is an integer greater than or equal to 2). In Figure 19A , 19B In 19C, the ranging systems 70h, 70h', and 70h" respectively include multiple laser diodes 121 to 12... N Coupling units 100c1 to 100c N Output signals OUT1 to OUT N From coupling unit 100c1 to 100c respectively N Output and input to the corresponding laser diodes 121 to 12 N .

[0309] Including multiple drive units 241 to 24 N In this case, it is conceivable to measure all drive units 241 to 24 N The delay time. However, in that case, the wiring becomes complex, which is impractical. Therefore, it is conceivable to use multiple drive units 241 to 24 N A portion is set as the measurement target. The measurement results of the drive unit that serves as the measurement target can be used for ranging of all other drive units.

[0310] With reference Figure 18 The described ranging system is similar to the 70g system. Figure 19A The ranging system 70h shown uses the output signal 220 of buffer B3 to measure the delay time. The output signal 220 of buffer B3 is input to drive units 241 to 2420. N The signal is the same as the signal. Other configurations are similar to the reference. Figure 18 The configuration of the ranging system described is 70g, therefore its description is omitted.

[0311] Figure 19B The distance measuring system 70h' shown uses multiple drive units 241 to 24 N The output signal of a drive unit 241 is used to measure the delay time. Other configurations are similar to the reference. Figure 11 The range finding system 70c configuration is described, therefore its description is omitted.

[0312] With referenceFigure 14 The described ranging system 70d is similar to Figure 19C The ranging system 70h" shown in FIG. 12B measures a delay time using the output signal OUTrep of the replica drive unit 24R. Other configurations are similar to those of the ranging system 70d described with reference to Figure 14 The described ranging system 70d is configured, and thus the description thereof is omitted.

[0313] [1.12.2 Operation]

[0314] Figure 19A The ranging system 70h shown in FIG. 11B measures a delay time using the output signal 220 of the buffer B3. The output signal 220 of the buffer B3 is the same signal as the signal input to the drive units 241 to 24 N Thus, Figure 19A The ranging system 70h shown in FIG. 11B measures a delay time using the output signal 220 of the buffer B3. The output signal 220 of the buffer B3 is the same signal as the signal input to the drive units 241 to 24 N Thus, Figure 18 The described ranging system 70g is configured, and thus the description thereof is omitted.

[0315] Figure 19B The ranging system 70h' shown in FIG. 12A measures a delay time using the drive signal of one of the drive units 241 to 24 N That is, a time is counted from the rising timing of the trigger signal TRG', the output timing of the drive signal of one of the drive units 241 to 24 N is ended, and a time count value is set as a delay time. For the other drive units 242 to 24 N Thus, Figure 11 The described ranging system 70c is configured, and thus the description thereof is omitted.

[0316] Figure 19C The ranging system 70h" shown in FIG. 12B measures a delay time using the output signal OUTrep of the replica drive unit 24R. Other configurations are similar to those of the ranging system 70d described with reference to Figure 14 The described ranging system 70d is configured, and thus the description thereof is omitted.

[0317] [1.12.3 Effects]

[0318] In the case where a plurality of drive units 241 to 24 N By using the output signal before branching or by using some of the drive units as a measurement target, it is possible to prevent the wiring from becoming complicated, measure a delay time, and improve ranging accuracy.

[0319] (1.13 Tenth variation of the first embodiment)

[0320] Figure 20 It shows according to the reference Figure 6 A figure of the ranging system 70i of the tenth variation of the first embodiment described.

[0321] [1.13.1 Configuration]

[0322] Figure 20 The ranging system 70i shown includes multiple TDCs 23a. In this example, the ranging system 70i includes two TDCs 23a1 and TDC 23a2. TDC 23a1 receives the output signal OUT1 of the drive unit 241 as input. TDC 23a2 receives the output signal OUT1 of the drive unit 241 as input. N OUT output signal N Other configurations are similar to the reference. Figure 11 The range finding system 70c configuration is described, therefore its description is omitted.

[0323] [1.13.2 Operation]

[0324] exist Figure 20 In the ranging system 70i shown, TDC 23a1 and TDC 23a2 each measure the delay time. The digital data of the delay times measured by the two TDCs 23a1 and TDC 23a2 are stored in storage unit 25M within logic unit 25. Other operations are similar to those in the reference system. Figure 11 The operation of the ranging system 70c is described, therefore its description is omitted. Note that the ranging system 70i may include three or more TDCs.

[0325] [1.13.3 Effects]

[0326] exist Figure 20 In the ranging system 70i shown, the signal processing unit 51 can acquire digital data of the delay time stored in the storage unit 25M in the logic unit 25. In this example, the signal processing unit 51 can acquire digital data of the delay time measured by each of the two TDCs 23a1 and 23a2. Therefore, the signal processing unit 51 can perform ranging using the two acquired digital data. For example, the average of the two digital data can be calculated to perform ranging using this average, thereby allowing for further improvement in ranging accuracy.

[0327] (1.14 Eleventh Modification of the First Embodiment)

[0328] Figure 21 It shows according to the reference Figure 6A figure of the ranging system 70j of the eleventh variation of the first embodiment described.

[0329] [1.14.1 Configuration]

[0330] Figure 21 The ranging system 70j shown includes multiple drive units 241 to 242. N and selector 27. Selector 27 selects multiple drive units 241 to 2420. N Each drive signal. Selector 27 can sequentially select multiple drive units 241 to 242. N The drive signal. Selector 27 can select multiple drive units 241 to 242 by a selection signal (not shown). N The driving signal.

[0331] Other configurations in driver 10 are similar to the reference. Figure 11 The configurations described. Note that in Figure 20 In this configuration, the signal processing unit 51 is similar to that in the reference design. Figure 11 The configuration described is omitted. Therefore, the description and explanation of the internal configuration of the signal processing unit 51 are omitted.

[0332] [1.14.2 Operation]

[0333] exist Figure 21 In the ranging system 70j shown, selector 27 selects multiple drive units 241 to 242. N One of the drive signals. Selector 27 can sequentially select multiple drive units 241 to 242. N One of the drive signals. The drive signal selected by selector 27 is input to TDC 23a. TDC 23a uses the drive signal selected by selector 27 to measure the delay time. That is, the time is counted from the rising timing of the trigger signal TRG', when selector 27 selects from multiple drive units 241 to 24... N The output timing of the selected drive signal in the drive signal is stopped after the count time, and the time count value is set to the delay time. Other operations are similar to the reference. Figure 11 The operation of the ranging system 70c is described, therefore its description is omitted.

[0334] [1.14.3 Effect]

[0335] because Figure 21 The distance measuring system 70j shown includes a selector 27, and thus corresponds to a plurality of drive units 241 to 242. N Compared to the TDC 23a configuration, all output signals have the advantage of simpler wiring and no increase in installation area.

[0336] (2. Second Embodiment)

[0337] Next, a second embodiment of the present disclosure will be described. In the first embodiment, the driver 10 measures the delay time. Meanwhile, in the second embodiment, the signal processing unit 51 measures the delay time.

[0338] [2.1 Configuration]

[0339] Figure 22 is a diagram illustrating a ranging system 70k according to the second embodiment of the present disclosure. In Figure 22 , the ranging system 70k includes the signal processing unit 51, the driver 10, and the laser diode 12. The signal processing unit 51 and the driver 10 are coupled through the coupling units 100a and 100b and the coupling units 100g and 100h. The driver 10 and the laser diode 12 are coupled through the coupling unit 100c.

[0340] The signal processing unit 51 includes the PLL unit 21, a light emission waveform generation circuit (Tgen) 22 as a light emission waveform generation unit, the TDC 23 and the TDC 23a, the buffers B1, B5, and B6, and the ranging sensor unit 302. The light emission waveform generation circuit 22 outputs a trigger signal TRG. The trigger signal TRG is a light emission pattern signal for causing the laser diode 12 to emit light. The light emission waveform generation circuit 22 outputs the trigger signal TRG and outputs a count start signal Cntstart. The buffer B5 receives the trigger signal TRG output from the buffer B1 as an input and outputs the trigger signal TRG to the TDC 23a. The buffer B6 receives a signal input from the coupling unit 100g and outputs the signal to the TDC 23a. The buffers B5 and B6 include, for example, two CMOS inverters connected in cascade.

[0341] Like the TDC 23, the TDC 23a includes a counter for counting time. When a signal output from the buffer B5 is input, the TDC 23a starts counting time. When a signal output from the buffer B6 is input, the TDC 23a ends counting time. Although the timing at which the laser diode 12 actually emits light is unknown, in this example, the time until the timing immediately before light emission (close to the light emission timing) is measured as the delay time. That is, the TDC 23a functions as a measurement unit for measuring the delay time, which is the time included in the time from the timing at which the trigger signal TRG for causing the laser diode 12 to emit light is output to the timing at which the laser diode 12 actually emits light. The other configuration of the signal processing unit 51 is similar to that of the ranging system 70a described with reference to Figure 4 The description thereof is omitted.

[0342] The driver 10 includes the buffers B2 and B4 and the drive unit 24. The signal on the input side of the drive unit 24 is branched. The branched signal is derived from the light emission timing and is input to the buffer B4. The buffer B4 returns the branched signal to the signal processing unit 51. The buffer B4 receives the signal output from the buffer B2 and outputs the signal to the signal processing unit 51 via the coupling units 100g and 100h. The other configurations of the driver 10 are similar to those described with reference to Figure 4 The configuration of the ranging system 70a described is omitted.

[0343] [2.2 Operation]

[0344] The TDC 23a serving as the measurement unit bifurcates the transmission path of the trigger signal TRG in the signal processing unit 51 and counts time from the rising timing of the returned signal. Then, the TDC 23a bifurcates the transmission path of the trigger signal TRG on the input side of the drive unit 24, counts time from the rising timing of the signal obtained by the returned trigger signal TRG, and sets the time count value as the delay time. That is, the trigger signal TRG for causing the laser diode 12 to emit light is output, and ranging is performed using the delay time generated by the delay element in the path extending to the point at which the trigger signal TRG actually drives the laser diode 12. That is, the time difference between the signals returned by different systems is measured as the delay time, and ranging is performed using the delay time.

[0345] An example of the operation of the entire ranging system 70k shown in Figure 22 will be described. Figure 23 is a flowchart showing an example of the operation of the ranging system 70k according to the second embodiment of the present disclosure shown in Figure 22

[0346] In Figure 22 , the signal processing unit 51 transmits the trigger signal TRG for causing the laser diode 12 to emit light to the driver 10 (step S21). The driver 10 receives the trigger signal TRG, outputs the drive signal for causing the laser diode 12 to emit light, and returns the signal derived from the light emission timing to the signal processing unit 51 (step S22).

[0347] The signal processing unit 51 measures the time difference between the signal derived from the light emission timing and the trigger signal TRG, that is, the delay time (step S23). The signal processing unit 51 adjusts the count start timing for ranging using the time difference, that is, the delay time, obtained by the measurement, and performs ranging (step S24).

[0348] ​Specifically, in TDC 23a, the counting start timing delay for ranging is corresponding to a delay time. That is, TDC 23a starts counting after a time corresponding to the delay time elapses from the output timing of the trigger signal TRG, and ends counting after the light receiving timing of the reflected light obtained by the ranging sensor unit 302. The signal processing unit 51 calculates the distance to the target 61 based on the time counting result of TDC 23a. As a result, ranging can be performed by adjusting the starting timing of the counting time.

[0349] Next, determine whether to end the process (step S25). If the process is not finished, the process returns to step S21 and the above process is executed (No in step S25 → S21). If the process is finished, the process ends (Yes in step S25 → S26).

[0350] Reference Figure 23 The described process can be performed each time the laser diode 12 emits light, or it can be performed once after a predetermined number of times the laser diode 12 emits light, instead of each time. The process can also be performed at each predetermined time interval. Alternatively, the process can be performed only when the system is activated and not thereafter.

[0351] Note that, similar to the first embodiment, a storage unit 25M can be provided, and digital data corresponding to the delay time measured in step S23 can be stored in the storage unit 25M. In this case, the digital data of the delay time stored in the storage unit 25M is used in step S24 to adjust the counting start timing for ranging.

[0352] Here, the description will be based on Figure 22 An exemplary calculation of the delay time of the ranging system 70k in the second embodiment shown. Figure 24 This is a diagram illustrating an exemplary calculation of the delay time of a 70k ranging system. Figure 24 In this diagram, let t_io1 be the delay time of buffer B1, t_ldd be the delay time of buffer B2, t_io1' be the delay time of buffer B4, t_io2 be the delay time of buffer B5, and t_io3 be the delay time of buffer B6. The delay time of buffer B5 is equal to the delay time of buffer B6. Since buffers B5 and B6 are formed on the same semiconductor chip, their delay times can be matched.

[0353] A delay time caused by a path from the trigger signal TRG to the TDC 23a via the buffers B1 and B6 in the signal processing unit 51 is indicated by T1. That is, a difference between a time at which the trigger signal TRG is output and a time at which the signal TRG_SPD corresponding to the trigger signal TRG is input to the TDC 23a is the delay time T1. The delay time T1 can be represented by the following equation (2).

[0354] T1 = t_io1 + t_ldd + t_io1' + t_io2 (2)

[0355] Further, a delay time caused by a path from the trigger signal TRG to the driver 10 from the signal processing unit 51 and back to the signal processing unit 51 via the driver 10 is indicated by T2. A difference between a time at which the trigger signal TRG is output and a time at which the signal TRG_DRV derived from the trigger signal TRG is input to the TDC 23a is the delay time T2. The delay time T2 can be represented by the following equation (3).

[0356] T2 = t_io1 + t_io2 (3)

[0357] Based on the equations (2), (3), a difference between the delay time T1 and the delay time T2 is represented by the following equation (4).

[0358] T1 - T2 = t_ldd + t_io1' (4)

[0359] The equation (4) is equivalent to the delay time Tdly measured by the TDC 23a. The delay time Tdly is input to the light emission waveform generation circuit 22 as the light emission waveform generation unit. The light emission waveform generation circuit 22 delays a rising timing of the count start signal Cntstart by a time corresponding to the delay time tdly. The delay time Tdly is a difference between the delay time in the signal processing unit 51 and the delay time in the driver 10, and by using the delay time Tdly, it is possible to improve the precision of the distance measurement.

[0360] Further, the rising timings of the main signals of the distance measurement system 70k shown in Figure 22 will be described. Figure 25 is a diagram showing an example of the rising timings of the trigger signal TRG, the signal TRG_SPD corresponding to the trigger signal TRG, the signal TRG_DRV derived from the trigger signal TRG, and the count start signal Cntstart in Figure 24

[0361] As Figure 25 ​As shown, the rising of the signal TRG_SPD has a delay from the rising time Tt1 of the trigger signal TRG, and the rising of the signal TRG_DRV has a further delay. The time difference between the rising timing of the signal TRG_SPD and the rising timing of the signal TRG_DRV is the delay time Tdly.

[0362] The light emission waveform generation circuit 22 can use the delay time Tdly to adjust the next or subsequent rising timing of the count start signal Cntstart. That is, as indicated by an arrow Y in FIG. 12, the count start signal Cntstart rises at a rising timing Tc that is delayed from the rising time Tt2 of the trigger signal TRG by the delay time Tdly. In this way, the count start time of the TDC 23a can be matched or closer to the actual light emission timing. Figure 25

[0363] [2.3 Effects]

[0364] By using the delay time Tdly that is the difference between the delay time in the signal processing unit 51 and the delay time in the driver 10, the count start time of the TDC 23a can be matched or closer to the actual light emission timing. As a result, the precision of the distance measurement can be further improved.

[0365] (2.4 First Modification of the Second Embodiment)

[0366] Figure 26 is a diagram illustrating a distance measurement system 70m according to the first modification of the second embodiment described with reference to Figure 22 FIG. 13.

[0367] [2.4.1 Configuration]

[0368] In the distance measurement system 70k of the second embodiment described with reference to Figure 22 to 25 FIG. 12, the path at the output side of the buffer B2 in the driver 10, that is, the input side of the drive unit 24 is branched to return the signal to the signal processing unit 51. Meanwhile, as shown in Figure 26 FIG. 13, the distance measurement system 70m according to the first modification of the second embodiment branches the path at the output side of the drive unit 24 in the driver 10 and returns the signal to the signal processing unit 51. The other configuration is the same as that of the distance measurement system 70k of the second embodiment, and thus the description thereof will be omitted.

[0369] [2.4.2 Operation]

[0370] According to Figure 26 ​The ranging system 70m of the first modification of the second embodiment shown in FIG. 12 branches the path at the output side of the drive unit 24 in the driver 10 and returns the signal to the signal processing unit 51 via the buffer B4. The other operations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0371] [2.4.3 Effects]

[0372] In the ranging system 70m of the first modification of the second embodiment, the subsequent stage of the drive unit 24, i.e., the point close to the laser diode 12, is set as the measurement target. Thus, the accuracy of the ranging can be further improved.

[0373] (2.5 Second Modification of the Second Embodiment)

[0374] Figure 27 is a diagram showing the ranging system 70p according to the second modification of the second embodiment described with reference to Figure 22 FIG. 13 is a diagram showing the ranging system 70p of the second modification of the second embodiment described with reference to

[0375] [2.5.1 Configuration]

[0376] In the ranging system 70m of the first modification of the second embodiment described with reference to Figure 26 In the ranging system 70m of the first modification of the second embodiment described with reference to Figure 27 The ranging system 70p of the second modification of the second embodiment shown in FIG. 12 includes the attenuator (ATT) 28 in the driver 10. The attenuator 28 is provided in the path after the branching from the path at the output side of the drive unit 24. The attenuator 28 attenuates the signal level. The other configuration is the same as that of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0377] [2.5.2 Operation]

[0378] The attenuator 28 attenuates the signal level to the signal level that the buffer B4 can process. The signal attenuated by the attenuator 28 is output to the signal processing unit 51 via the buffer B4. The other operations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0379] [2.5.3 Effects]

[0380] The attenuator 28 can attenuate to the signal level that the buffer B4 can process.

[0381] (2.6 Third Modification of the Second Embodiment)

[0382] Figure 28 is a diagram showing the ranging system 70q according to the third modification of the second embodiment described with reference to Figure 22 FIG. 14 is a diagram showing the ranging system 70q of the third modification of the second embodiment described with reference to

[0383] [2.6.1 Configuration]

[0384] In the ranging system 70k of the second embodiment described with reference to Figure 22 to Figure 25 the path on the output side of the buffer B1 in the signal processing unit 51 is branched. Meanwhile, as Figure 28 indicated in the ranging system 70q according to the third modification example of the second embodiment, the path on the input side of the buffer B1 in the signal processing unit 51 is branched. That is, the trigger signal TRG is directly input to the TDC 23a. The other configurations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0385] [2.6.2 Operation]

[0386] The trigger signal TRG output from the light emission waveform generation circuit 22 is input to the TDC 23a without passing through the buffer B1. Therefore, the delay time due to the buffer B1 can be removed. The other operations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0387] [2.6.3 Effects]

[0388] Since the trigger signal TRG is directly input to the TDC 23a, the delay time due to the buffer B1 can be removed to measure the delay time.

[0389] (2.7 Fourth Modification Example of Second Embodiment)

[0390] Figure 29 is a diagram showing a ranging system 70r according to a fourth modification example of the second embodiment described with reference to Figure 22 . As Figure 29 indicated in the ranging system 70r according to the fourth modification example of the second embodiment, like in the ranging system 70q described with reference to Figure 28 , the path on the input side of the buffer B1 in the signal processing unit 51 is branched. The ranging system 70r of the present example does not include the TDC 23a.

[0391] [2.7.1 Configuration]

[0392] As Figure 29 indicated in the ranging system 70r according to the fourth modification example of the second embodiment, the trigger signal TRG and the output signal of the buffer B5 are input to the TDC 23. The other configurations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0393] [2.7.2 Operation]

[0394] The TDC 23 starts counting time at the rising timing of the trigger signal TRG. The TDC 23 ends counting time at the rising timing of the output signal of the buffer B5. This counted time can be used to measure the delay time. Further, the TDC 23 starts counting time at the rising timing of the trigger signal TRG and ends counting time at the timing at which the ranging sensor unit 302 receives light. The time obtained from this counted time is subtracted by the delay time. As a result, the output timing of the trigger signal TRG can be unknown, but a timing closer to the actual light emission timing is known, and thus the delay time due to the internal circuit of the driver 10 can be removed. The other operations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0395] [2.7.3 Effects]

[0396] In the ranging system 70r according to the fourth modification example of the second embodiment, a point of the driver unit 24 close to the laser diode 12, that is, a subsequent stage is set as a measurement target. Thus, the accuracy of ranging can be further improved.

[0397] (2.8 Fifth Modification Example of Second Embodiment)

[0398] Figure 30A and 30B is a diagram showing a ranging system 70s according to a fifth modification example of the second embodiment described with reference to Figure 22 The ranging system 70q of the present example has a configuration in which a virtual load 29 is added inside the driver 10 of the ranging system 70k described with reference to Figure 22

[0399] [2.8.1 Configuration]

[0400] As shown in Figure 30A , the ranging system 70q of the present example includes the virtual load 29 provided in the driver 10. The virtual load 29 is connected to the output side of the buffer B2 via a transistor Tr1. The gate of the transistor Tr1 is connected to the output of the buffer B2.

[0401] The driver unit 24 includes a transistor Tr2. The gate of the transistor Tr2 is connected to the output of the buffer B2.

[0402] Figure 31 is a diagram showing an example of the virtual load 29. As shown in Figure 31 , the virtual load 29 of the example includes a resistor R1 and a capacitor C1. The resistor R1 and the capacitor C1 are connected in parallel. The virtual load 29 has a time constant corresponding to the time required for current to flow through the laser diode 12 to actually emit light. The other configurations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted. ​

[0403] Note that, as shown in Figure 30B , the cathode of the laser diode 12 can be connected to the ground, and the anode can be connected to the transistor Tr2' in the driver 10. The dummy load 29 is connected to the power supply via the transistor Tr'.

[0404] [2.8.2 Operation]

[0405] The transistor Tr2 in the drive unit 24 is turned on by the output signal of the buffer B2, and a current flows through the laser diode 12. As a result, the laser diode 12 emits light. Further, the transistor Trl is turned on, and a signal that has passed through the dummy load 29 is input to the buffer B4. As a result, a signal is output to the buffer B4 after a time corresponding to the time required for a current to flow through the laser diode 12 and the laser diode 12 to actually emit light. The other operations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0406] [2.8.3 Effect]

[0407] By arranging the dummy load 29, a signal can be returned to the signal processing unit 51 taking into account the delay time until a current flows through the laser diode 12 and the laser diode 12 emits light. As a result, the accuracy of ranging can be further improved.

[0408] (2.9 Sixth Modification of the Second Embodiment)

[0409] Figure 32A and 32B is a diagram showing a ranging system 70t according to a sixth modification of the second embodiment described with reference to Figure 22 . The ranging system 70s described with reference to Figure 30A , 30B and 31 includes one laser diode 12. Meanwhile, Figure 32A the ranging system 70t of the present example shown in

[0410] [2.9.1 Configuration]

[0411] As shown in Figure 32A , the ranging system 70t of the present example includes two laser diodes 121 and 122. The ranging system 70t of the present example includes drive units 241 and 242 corresponding to the laser diodes 121 and 122, respectively. The drive units 241 and 242 include transistors Tr21 and Tr22, respectively. The ranging system 70t can include N x M (N and M are natural numbers) laser diodes arranged in a matrix shape. The "N" and "M" above can be the same value or different values. The other configurations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0412] Note that, as Figure 32B As shown, the cathodes of laser diodes 121 and 122 can be connected to ground, and the anodes can be connected to transistors Tr21' and Tr22' in driver 10. The dummy load 29 is connected to the power supply via transistor Tr'.

[0413] [2.9.2 Operation]

[0414] Transistor Tr21 in drive unit 241 and transistor Tr22 in drive unit 242 are turned on by the output signal of buffer B2, and current flows in laser diodes 121 and 122. As a result, laser diodes 121 and 122 emit light. Furthermore, transistor Tr1 is turned on and, after a time corresponding to the time required for current to flow through laser diode 12 and for it to actually emit light, outputs a signal to buffer B4. Other operations are the same as those of the ranging system 70k in the second embodiment, and therefore their description will be omitted.

[0415] [Effect 2.9.3]

[0416] According to the ranging system 70t in this example, even when multiple laser diodes are included, the delay time can be measured, and the accuracy of ranging can be improved.

[0417] Note that one output side of the multiple drive units 241 and 242 can be branched off without setting up the virtual load 29, and the output signal can be returned to the signal processing unit 51 side. Alternatively, instead of arranging the virtual load 29, a copy drive unit of the analog drive unit 24 can be arranged, and the output signal of the copy drive unit can be returned to the signal processing unit 51 side.

[0418] (2.10 Seventh variation of the second embodiment)

[0419] Figure 33 It shows according to the reference Figure 22 A diagram of the ranging system 70u of the seventh modification of the second embodiment described herein. (See diagram for reference.) Figure 33 As shown, the ranging system 70u does not include the virtual load 29 set in the ranging system 70t.

[0420] [2.10.1 Configuration]

[0421] like Figure 33 As shown, the ranging system 70u returns the output of buffer B2 (i.e., the shared signal for the multiple drive units 241 and 242) to the signal processing unit 51. Other configurations are the same as those of the ranging system 70k in the second embodiment, and therefore their description will be omitted.

[0422] [2.10.2 Operation]

[0423] The transistor Tr21 in the drive unit 241 and the transistor Tr22 in the drive unit 242 are turned on by the output signal of the buffer B2, and a current flows in the laser diodes 121 and 122. As a result, the laser diodes 121 and 122 emit light. The other operations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0424] [2.10.3 Effects]

[0425] According to the ranging system 70u of the present example, even in the case where a plurality of laser diodes are included, the delay time can be measured, and the precision of the ranging can be improved.

[0426] (2.11 Eighth Modification of the Second Embodiment)

[0427] Figure 34 is a view that shows a reference Figure 22 to the ranging system 70v of the eighth modification of the second embodiment described above. Figure 34 The ranging system 70v illustrated includes the TDC 23a and the TDC 23b as a plurality of measurement units that respectively correspond to the plurality of drive units 241 and 242.

[0428] [2.11.1 Configuration]

[0429] As Figure 34 illustrated, the ranging system 70v includes the TDC 23a corresponding to the drive unit 241 and the TDC 23b corresponding to the drive unit 242. The driver 10 includes the buffer B41 corresponding to the drive unit 241. The driver 10 includes the buffer B42 corresponding to the drive unit 242. The signal processing unit 51 includes the buffer B51 corresponding to the TDC 23a. The signal processing unit 51 includes the buffer B52 corresponding to the TDC 23b. The signal processing unit 51 and the driver 10 are coupled through the coupling units 100a and 100b, the coupling units 100g1 and 100h1, and the coupling units 100g2 and 100h2. The other configurations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0430] [2.11.2 Operation]

[0431] In Figure 34In the range-finding system 70v shown, the drive signal of the drive unit 241 is output to the laser diode 121 via the coupling unit 100c1, branched at the output side of the drive unit 241, and input to the TDC 23a of the signal processing unit 51 via the buffer B41 and the buffer B51. Further, the drive signal of the drive unit 242 is output to the laser diode 122 via the coupling unit 100c2, branched at the output side of the drive unit 242, and input to the TDC 23b of the signal processing unit 51 via the buffer B42 and the buffer B52.

[0432] The TDCs 23a and 23b count time from the rise of the trigger signal TRG. The TDC 23a ends counting time at the rise timing of the drive signal of the drive unit 241 input via the buffer B41 and the buffer B51. The TDC 23b ends counting time at the rise timing of the drive signal of the drive unit 242 input via the buffer B42 and the buffer B52. The TDC 23a measures the delay time Tdly1. The TDC 23b measures the delay time Tdly2. The other operations are the same as the operation of the range-finding system 70k of the second embodiment, and thus the description thereof will be omitted.

[0433] [2.11.3 Effects]

[0434] According to the range-finding system 70v of the present example, the delay time can be individually measured for each of the plurality of drive units, and the precision of the range finding can be improved.

[0435] (2.12 Ninth Modification of the Second Embodiment)

[0436] Figure 35 is a view showing a range-finding system 70w according to the ninth modification of the second embodiment described with reference to Figure 22 FIG. 10 is a view showing the range-finding system 70w of the ninth modification of the second embodiment described with reference to Figure 35 The range-finding system 70w shown is different from the range-finding system 70v described with reference to Figure 34

[0437] [2.12.1 Configuration]

[0438] The driver 10 includes a multiplexer (MUX) 30, and the signal processing unit 51 includes a multiplexer (MUX) 31. The multiplexer 30 selects and inputs the output signal of the drive unit 241 and the output signal of the drive unit 242. The multiplexer 31 selects the TDC 23a or the TDC 23b. The multiplexer 31 inputs the output signal of the buffer B5 to one of the selected TDC 23a or TDC 23b. The multiplexer 30 and the multiplexer 31 can be switched at the same time.

[0439] ​[2.12.2 Operation]

[0440] exist Figure 35 In the ranging system 70w shown, multiplexer 30 selects and outputs the output signals of drive unit 241 and drive unit 242. The output signal of multiplexer 30 is input to multiplexer 31 via buffers B4 and B5. Multiplexer 31 inputs the output signal of multiplexer 30 to one of the selected TDC 23a or TDC 23b.

[0441] TDC 23a and TDC 23b begin counting time from the rising of the trigger signal TRG. The counting time ends with the output signal of multiplexer 31. Other operations are the same as those of the ranging system 70k in the second embodiment, and therefore their description will be omitted.

[0442] [Effect 2.12.3]

[0443] According to the ranging system 70w in this example, by using a multiplexer, the increase in the number of wires between the signal processing unit 51 and the driver 10 can be suppressed even when the delay time is measured individually for multiple drive units.

[0444] (2.13 Tenth variation of the second embodiment)

[0445] Figure 36 It shows according to the reference Figure 22 A figure of the ranging system 70x of the tenth variation of the second embodiment described.

[0446] [2.13.1 Configuration]

[0447] In the ranging system 70x, the time estimated using the delay time measured for some of the multiple laser diodes is regarded as the delay time for the other laser diodes.

[0448] The ranging system 70x includes multiple laser diodes and multiplexers 30 and 31 to perform as referenced. Figure 35 The switching in the 70W ranging system described. There are cases where the delay times of the measurements from multiple laser diodes are not identical. Here, among the multiple laser diodes, the laser diode with the shortest delay time and the fastest emission is referred to as laser diode 12. F Furthermore, the laser diode with the longest delay time and the slowest emission is called a laser diode.12 L .

[0449] Obtain a laser diode 12 F The measured delay time and the laser diode 12 LThe average of the measured delay times, and the average of the delay times that have been obtained, can be used for ranging using all of the laser diodes.

[0450] Further, a value obtained by performing linear interpolation on the delay times measured for the laser diodes can be used for ranging. For example, a value obtained by performing linear interpolation on the delay times of the laser diodes at several positions of the laser diodes arranged in two dimensions is used for ranging.

[0451] Figure 37 is a diagram illustrating an example in which a plurality of laser diodes are arranged in two dimensions. The laser diodes arranged in two dimensions (hereinafter, LD array) are, for example, vertical cavity surface emitting lasers (VCSEL). In Figure 37 In the present example, the laser diodes are arranged at respective positions of eleven rows by eight columns. Here, in Figure 37 In, the laser diode at the upper left position is denoted by LD(1, 1), the laser diode at the upper right position is denoted by LD(1, 8), the laser diode at the lower left position is denoted by LD(11, 1), and the laser diode at the lower right position is denoted by LD(11, 8).

[0452] [2.13.2 Operation]

[0453] If the delay time of LD(1, 1) is the shortest, and the delay time of LD(11, 8) is the longest, LD(1, 1) and LD(11, 1) are set as the measurement targets. By performing linear interpolation between the delay time of LD(1, 1) and the delay time of LD(11, 1), the delay times of the other laser diodes can be estimated. If the lengths of the wirings from the light emission waveform generation circuit 22 are known, the estimation can be made by performing weighting according to the lengths.

[0454] [2.13.3 Effects]

[0455] The ranging system 70x according to the tenth modification of the second embodiment can improve the accuracy of ranging by performing linear interpolation or the like, without setting all of the laser diodes included in the LD array as measurement targets.

[0456] (2.14 Eleventh Modification of Second Embodiment)

[0457] Figure 38 is a diagram illustrating a ranging system 70y according to the eleventh modification of the second embodiment described with reference to Figure 22 FIG. 2. Figure 38 The ranging system 70y illustrated has a configuration in which a buffer B7, a PLL unit 21a, and a light emission waveform generation circuit 22a are added to the ranging system 70k described with reference to Figure 22 FIG. 2.

[0458] [2.14.1 Configuration]

[0459] The buffer B7 includes two CMOS inverters connected in cascade like the other buffers. The PLL unit 21a receives the clock signal Refclk as an input. The light emission waveform generation circuit 22a operates the drive unit 24. The other configurations are similar to those of the ranging system 70k described with reference to Figure 22 The configuration of the ranging system 70k described with reference to the second embodiment, and thus the description thereof will be omitted.

[0460] [2.14.2 Operation]

[0461] The PLL unit 21a receives the clock signal Refclk as an input, and outputs the clock signal Refclk' having a phase matching that of the clock signal Refclk. The light emission waveform generation circuit 22a operates the drive unit 24 when the trigger signal TRG is input from the signal processing unit 51. The drive unit 24 outputs the output signal OUT. Further, the path of the output signal OUT output from the drive unit 24 branches, and the output signal OUT is transmitted to the signal processing unit 51 via the buffer b4.

[0462] Figure 39 is a diagram for illustrating the operation of the light emission waveform generation circuit 22a. Figure 39 is a diagram showing the trigger signal TRG and the output signal OUT. The light emission waveform generation circuit 22a of the present example outputs the output signal OUT changing similarly to the clock signal Refclk' after a lapse of a predetermined time period Tc from the rise of the trigger signal TRG. The light emission waveform generation circuit 22a outputs the output signal OUT only when the trigger signal TRG is at the high level. Note that the light emission waveform generation circuit 22a can output the output signal OUT of various waveform patterns, and is not limited to the changing output signal OUT as shown in Figure 39 The other operations are the same as those of the ranging system 70k of the second embodiment, and thus the description thereof will be omitted.

[0463] [2.14.3 Effects]

[0464] The signal considering the delay time of the light emission waveform generation circuit 22A can be returned to the signal processing unit 51. As a result, the accuracy of the ranging can be further improved.

[0465] (3.1 Third Embodiment)

[0466] Figure 40A to 40C is a diagram showing the ranging system according to the third embodiment. The third embodiment relates to the implementation of the laser diodes and the drivers of the ranging systems according to the above-described first and second embodiments. In the third embodiment, the other components included in the laser diodes arranged on another substrate (hereinafter, LD array) and the drivers are formed.

[0467] Figure 40A is a diagram schematically showing a state in which the LD array 1200b is arranged on a laser diode driver (LDD) chip 1000 on which each element included in the driver is arranged, which is applicable to the third embodiment. Figure 40A is a diagram showing the LDD chip 1000 and the LD array 1200b when viewed from the side (top side) thereof on which the light emitting units of the respective laser diodes 12 included in the LD array 1200b are arranged. Note that, in Figure 40A and Figure 40B , the LD array 1200b is shown in a state in which the side (back side) coupled to the LDD chip 1000 is viewed from the top side on which the light emitting units of the laser diodes 12 are arranged.

[0468] The LDD chip 1000 is a semiconductor chip, and is coupled to an external circuit by wire bonding on a plurality of pads 1001 arranged in a peripheral portion. For example, a power supply voltage V DD .

[0469] Figure 40B is a diagram schematically showing a configuration of the LD array 1200b applicable to the third embodiment. As Figure 40B indicated, on the back surface of the LD array 1200b, the respective cathode terminals 1201 of the plurality of laser diodes 12 included in the LD array 1200b and the anode terminal 1202 common to the plurality of laser diodes 12 are aligned and arranged.

[0470] In the example of Figure 40B , the horizontal direction in the drawing represents the row, and the vertical direction represents the column, and the cathode terminals 1201 are arranged in the center of the grid array of the LD array 1200b in C rows x L columns. That is, in this example, (C x L) laser diodes 12 are arranged in the LD array 1200b. Meanwhile, the anode terminal 1202 is arranged in a grid arrangement on the left end side C rows x Al columns of the LD array 1200b and on the right end side C rows x A2 columns.

[0471] Figure 40C is a side view of a structure including the LDD chip 1000 and the LD array 1200b, which is applicable to the third embodiment, viewed from the lower end side of Figure 40A . As described above, the LDD chip 1000 and the LD array 1200b have a structure in which the LD array 1200b is stacked onto the LDD chip 1000. Each cathode terminal 1201 and each anode terminal 1202 are connected to the LDD chip 1000, for example, by micro bump.

[0472] (4.1 Fourth Embodiment)

[0473] Figure 41 is a diagram showing a ranging system according to a fourth embodiment. Figure 41 is a diagram showing an embodiment related to the layout of each unit in an LDD chip.

[0474] For example, the LD array 1200b is arranged in the area of the dotted line H2. In that case, preferably, each drive unit 24 of the driver 10 is arranged directly below the LD array 1200b. With this configuration, it is possible to make the positions of the laser diodes included in the LD array 1200b and the positions of the drive units corresponding thereto close to each other. As a result, it is possible to obtain an effect of facilitating wiring between the laser diodes and the drive units.

[0475] Preferably, the TDC 23 provided in the driver 10 in the first embodiment is arranged in the vicinity of the LD array 1200b. Preferably, for example, the TDC 23 is arranged in the area indicated by the dotted line H3. As a result, it is possible to obtain an effect of facilitating wiring for extracting the output signal OUT from the output of the drive unit 24 and inputting the output signal OUT to the TDC 23.

[0476] Note that, preferably, the temperature sensor 26 provided in the ranging system 70f shown in Fig. 17 is arranged in the vicinity of the LD array. For example, the temperature sensor 26 is preferably arranged in the area indicated by the dotted line H3. Since the laser diode generates a large amount of heat, it is possible to efficiently detect the amount of heat generation by arranging the temperature sensor in the vicinity of the laser diode. Figure 17

[0477] (5. SUMMARY)

[0478] The ranging system includes the drive unit 24, the ranging sensor unit 302 as a sensor unit, the TDC 23a as a measurement unit, and the ranging observation unit 52 as a processing unit. The drive unit 24 outputs a drive signal for causing the laser diode 12 as a light emitting element to emit light to irradiate the target 61 with light. The ranging sensor unit 302 detects reflected light from the target 61. The TDC 23a measures a delay time that is a time included in a time from a timing at which a trigger signal for causing the light emitting element to emit light is output to a timing at which the light emitting element actually emits light. The ranging observation unit 52 calculates a distance to the target 61 based on an output timing of the trigger signal, a light reception timing of the reflected light obtained by the ranging sensor unit 302, and the delay time.

[0479] As a result, it is possible to perform ranging using the delay time that has been measured, and it is possible to further improve the accuracy of the ranging.

[0480] ​The TDC 23a as the measurement unit starts counting time from the rising timing of the trigger signal, ends counting time at the output timing of the signal on the input side of the drive unit 24, and sets the time count value as the delay time.

[0481] As a result, it is possible to measure the delay time that is included in the time until the timing at which the laser diode 12 as the light emitting element actually emits light.

[0482] The distance measuring system can include a light emission waveform generation circuit 22a that is a light emission waveform generation unit. The light emission waveform generation circuit 22a generates a light emission pattern signal for causing the light emitting element to emit light.

[0483] As a result, it is possible to measure the delay time using the light emission pattern signal generated by the light emission waveform generation circuit 22a.

[0484] The distance measuring system can include a replica drive unit 24R that is a copy of the drive unit 24. The TDC 23a as the measurement unit ends counting time at the output timing of the signal of the replica drive unit 24R.

[0485] As a result, it is possible to improve the precision of distance measurement using the replica drive unit 24R.

[0486] The distance measuring system can include a buffer BV that is a delay amount adjustment unit. The delay time of the signal of the replica drive unit 24R can be adjusted by the buffer BV, that is, the delay amount adjustment unit.

[0487] As a result, it is possible to improve the precision of distance measurement even in the case of using the replica drive unit 24R.

[0488] The distance measuring system can include a temperature sensor 26 that detects temperature. The delay amount of the buffer BV as the delay amount adjustment unit is adjusted in accordance with the temperature detected by the temperature sensor 26.

[0489] As a result, it is possible to improve the precision of distance measurement even in the case of temperature variation.

[0490] The TDC 23a as the measurement unit can start counting time from the rising timing of the trigger signal, end counting time at the output timing of the signal on the input side of the drive unit 24, and set the time count value as the delay time.

[0491] As a result, it is possible to measure the delay time even in the case where the output signal of the drive unit 24 cannot be used.

[0492] The ranging system may include multiple driving units corresponding to multiple light-emitting elements. The TDC 23a (which is the measuring unit) starts counting time from the rising timing of the trigger signal and ends counting time at the output timing of one of the driving signals of the multiple driving units, and sets the time count value as the delay time.

[0493] As a result, the delay time can be measured using a single drive signal from multiple drive units corresponding to multiple light-emitting elements, and the delay time already measured when performing ranging using another light-emitting element can be used.

[0494] The ranging system may include a selector 27, which selects one of the drive signals output from a plurality of drive units. The TDC 23a, acting as a measuring unit, ends the counting time at the output timing of the drive signal selected by the selector 27 and sets the time count value to the delay time.

[0495] As a result, when measuring the delay time of each drive signal using multiple drive units, wiring complexity can be prevented.

[0496] The ranging system may include multiple TDCs 23a and TDCs 23b corresponding to multiple drive units 24.

[0497] As a result, for example, ranging can be performed using the average of the delay times measured by the two TDCs 23a and 23b, and ranging accuracy can be further improved.

[0498] The ranging system may include a storage unit 25M that stores data corresponding to the delay time. The ranging observation unit 52 (which is a processing unit) uses the data stored in the storage unit 25M to perform the processing of calculating the distance to the target.

[0499] As a result, distance measurement can be performed using the data stored in the 25M storage unit.

[0500] The ranging system may include a signal processing unit 51 and a driver 10. The signal processing unit 51 includes a ranging observation unit 52 as a processing unit, the driver 10 includes a driving unit 24, and the storage unit 25M may be disposed in at least one of the driver 10 or the signal processing unit 51.

[0501] As a result, distance measurement can be performed using the data stored in the 25M storage unit.

[0502] The ranging observation unit 52 (which is a processing unit) can start counting time after the output of the trigger signal TRG at a time corresponding to the delay time, end counting time at the light receiving time of the reflected light, and calculate the distance to the target 61 based on the time counting result.

[0503] As a result, distance measurement can be performed by adjusting the start timing of the counting time.

[0504] The ranging system may include a signal processing unit 51 and a driver 10. The signal processing unit 51 includes a ranging observation unit 52 as a processing unit, and the driver 10 includes a driving unit 24. A TDC 23a, serving as a measurement unit, may be disposed within the signal processing unit 51. The TDC 23a branches the transmission path of the trigger signal in the signal processing unit 51, starts counting time from the rise time of the signal obtained by returning the trigger signal, branches the transmission path of the trigger signal on the input side of the driving unit 24, ends counting time at the rise time of the signal obtained by returning the trigger signal, and sets the time count value as the delay time.

[0505] As a result, the delay time can be measured in the signal processing unit 51.

[0506] The ranging system may include a signal processing unit 51 and a driver 10. The signal processing unit 51 includes a ranging observation unit 52 as a processing unit, and the driver 10 includes a driving unit 24. A TDC 23a, serving as a measurement unit, may be disposed within the signal processing unit 51. The TDC 23a branches the transmission path of the trigger signal within the signal processing unit 51, starts counting time from the rise time of the signal obtained by returning the trigger signal, branches the transmission path of the trigger signal at the output side of the driving unit, ends counting time at the rise time of the signal obtained by returning the trigger signal, and sets the time count value as the delay time.

[0507] As a result, the delay time can be measured in the signal processing unit 51.

[0508] The ranging system may include an attenuator 28, which branches off at the output of the drive unit 24 and attenuates the signal level of the signal obtained by the return trigger signal. It may also include a buffer B4, which receives the signal attenuated by the attenuator 28 as input and outputs the signal to the signal processing unit 51.

[0509] As a result, attenuator 28 can attenuate the signal level to a level that buffer B4 can handle.

[0510] The ranging system may include a dummy load 29, which receives a signal from a branch of the transmission path of the trigger signal from the input side of the drive unit 24 as input. The dummy load 29 has a time constant corresponding to the time required for current to flow through the light-emitting element to actually emit light, and the signal that has passed through the dummy load 29 can be output from the driver 10 to the signal processing unit 51 as a signal obtained by returning the trigger signal.

[0511] By arranging the virtual load 29, the delay time until the current flows through the laser diode 12 and the laser diode 12 emits light can be taken into account before the signal is returned to the signal processing unit 51. As a result, the accuracy of ranging can be further improved.

[0512] It may include multiple driving units corresponding to multiple light-emitting elements and multiple TDCs 23a and TDCs 23b arranged corresponding to the multiple driving units. Each of the multiple TDCs 23a and TDCs 23b branches the transmission path of the trigger signal on one of the output sides of the multiple driving units, ends the counting time at the rising time of the signal obtained by returning the trigger signal, and sets the time count value as the delay time.

[0513] As a result, even when multiple driving units corresponding to multiple light-emitting elements are included, the accuracy of ranging can be improved.

[0514] The ranging system may include a first multiplexer 30 and a second multiplexer 31. The first multiplexer 30 selects and outputs signals from multiple drive units. The second multiplexer 31 inputs the output of the first multiplexer 30 to one of a plurality of TDCs 23a and TDC 23b.

[0515] As a result, even when multiple driving units corresponding to multiple light-emitting elements are included, the accuracy of ranging can be improved.

[0516] When the ranging system includes multiple light-emitting elements, the delay time of the light-emitting element arranged in the middle can be obtained by interpolating the two delay times.

[0517] As a result, even without measuring the delay time for all multiple light-emitting elements, the accuracy of ranging can be further improved by using the delay time obtained through interpolation.

[0518] The driver for the light-emitting element includes a driving unit 24 and a TDC 23a, which serves as a measurement unit. The driving unit 24 outputs a driving signal to cause the light-emitting element to emit light and illuminate a target. The TDC 23a measures a delay time, which is the time from the timing of the input trigger signal to cause the light-emitting element to emit light to the timing of the actual emission of light by the light-emitting element. For example, data corresponding to the delay time measured by the TDC 23a is output and stored in the storage unit 25M.

[0519] As a result, ranging can be performed using data corresponding to the delay time, and the accuracy of ranging can be further improved.

[0520] Note that the effects described in this article are merely illustrative and not limiting, and other effects can be achieved. Furthermore, the configurations described in this article can be combined appropriately.

[0521] Note that the present technology can also have the following configuration. (1)

[0523] A distance measuring system includes:

[0524] a drive unit that causes a light emitting element to emit light and outputs a drive signal for irradiating a target with light;

[0525] a sensor unit that detects reflected light from the target;

[0526] a measurement unit that measures a delay time included in a time from a timing at which a trigger signal for causing the light emitting element to emit light is output to a timing at which the light emitting element actually emits light; and

[0527] a processing unit that performs processing of calculating a distance to the target based on an output timing of the trigger signal, a light reception timing of the reflected light obtained by the sensor unit, and the delay time. (2)

[0529] The distance measuring system according to (1),

[0530] wherein the measurement unit starts counting time from a rising timing of the trigger signal, ends counting time at an output timing of the drive signal to the light emitting element, and sets the time count value as the delay time. (3)

[0532] The distance measuring system according to (1) or (2), further comprising a light emission waveform generation unit that generates a light emission pattern signal for causing the light emitting element to emit light. (4)

[0534] The distance measuring system according to (2), further comprising:

[0535] a copy drive unit that simulates the drive unit,

[0536] wherein the measurement unit ends counting time at an output timing of a signal of the copy drive unit. (5)

[0538] The distance measuring system according to (4), further comprising a delay amount adjustment unit that adjusts a delay time of the signal by the copy drive unit. (6)

[0540] The distance measuring system according to (5), further comprising a temperature sensor that detects temperature, wherein a delay amount of the delay amount adjustment unit is adjusted based on the temperature detected by the temperature sensor. (7)

[0542] The distance measuring system according to (2),

[0543] wherein the measurement unit starts counting time from the rising timing of the trigger signal, ends counting time at the output timing of the signal on the input side of the drive unit, and sets the time count value as the delay time. (8)

[0545] The distance measuring system according to (2), further comprising a plurality of the drive units corresponding to a plurality of the light emitting elements,

[0546] wherein the measurement unit starts counting time from the rising timing of the trigger signal, ends counting time at the output timing of one of the drive signals of the plurality of the drive units, and sets the time count value as the delay time. (9)

[0548] The distance measuring system according to (2), further comprising a selector that selects one of the drive signals output from a plurality of the drive units,

[0549] wherein the measurement unit ends counting time at the output timing of the drive signal selected by the selector, and sets the time count value as the delay time. (10)

[0551] The distance measuring system according to (2), further comprising a plurality of the measurement units corresponding to a plurality of the drive units. (11)

[0553] The distance measuring system according to any one of (1) to (10), further comprising:

[0554] a storage unit that stores data corresponding to the delay time,

[0555] wherein the processing unit performs the processing of calculating the distance to the target using the data stored in the storage unit. (12)

[0557] The distance measuring system according to (11), further comprising: a signal processing unit including the processing unit; and a driver including the drive unit,

[0558] wherein the storage unit is provided in at least one of the driver and the signal processing unit. (13)

[0560] The distance measuring system according to any one of (1) to (12),

[0561] wherein the processing unit starts counting time after a time corresponding to the delay time from the output timing of the trigger signal, ends counting time at the light reception timing of the reflected light, and calculates the distance to the target based on the time count result. (14)

[0563] The distance measuring system according to (2), further comprising: a signal processing unit including the processing unit; and a driver including the driving unit,

[0564] wherein the measurement unit is provided in the signal processing unit, and

[0565] the measurement unit branches a transmission path of the trigger signal in the signal processing unit, starts counting time from a rising timing of a signal obtained by returning the trigger signal, branches the transmission path of the trigger signal at an input side of the driving unit, ends counting time at a rising timing of a signal obtained by returning the trigger signal, and sets the time count value as the delay time. (15)

[0567] The distance measuring system according to (2), further comprising: a signal processing unit including the processing unit; and a driver including the driving unit,

[0568] wherein the measurement unit is provided in the signal processing unit, and

[0569] the measurement unit branches a transmission path of the trigger signal in the signal processing unit, starts counting time from a rising timing of a signal obtained by returning the trigger signal, branches the transmission path of the trigger signal at an output side of the driving unit, ends counting time at a rising timing of a signal obtained by returning the trigger signal, and sets the time count value as the delay time. (16)

[0571] The distance measuring system according to (15), further comprising:

[0572] an attenuator that branches at the output side of the driving unit and attenuates a signal level of a signal obtained by returning the trigger signal; and

[0573] a buffer that receives, as input, a signal attenuated by the attenuator, and outputs the signal to the signal processing unit. (17)

[0575] The distance measuring system according to (14), further comprising:

[0576] a virtual load that receives a signal branched from the transmission path of the trigger signal from the input side of the drive unit as input,

[0577] wherein the virtual load has a time constant corresponding to a time required for a current to flow through the light emitting element to actually emit light, and

[0578] a signal having passed through the virtual load is output from the driver to the signal processing unit as a signal obtained by returning the trigger signal. (18)

[0580] The distance measuring system according to (2), further comprising a plurality of the drive units corresponding to the plurality of the light emitting elements; and a plurality of the measurement units provided corresponding to the plurality of the drive units,

[0581] wherein each of the plurality of the measurement units forks the transmission path of the trigger signal at a respective output side of the plurality of the drive units, ends counting time at a rising timing of a signal obtained by returning the trigger signal, and sets the time count value as the delay time. (19)

[0583] The distance measuring system according to (18), further comprising: a first multiplexer that selects and outputs one of output signals of the plurality of the drive units; and a second multiplexer that inputs the output of the first multiplexer to a selected one of the plurality of the measurement units. (20)

[0585] The distance measuring system according to (18) or (19),

[0586] wherein the plurality of the light emitting elements includes a first light emitting element and a second light emitting element, and

[0587] the delay time of the light emitting element provided between the first light emitting element and the second light emitting element is obtained by interpolation between the delay time of the first light emitting element and the delay time of the second light emitting element. (21)

[0589] A driver of a light emitting element, comprising:

[0590] a drive unit that causes the light emitting element to emit light and outputs a drive signal for irradiating a target with light; and

[0591] a measurement unit that measures a delay time included in a time from a timing at which a trigger signal for causing the light emitting element to emit light is input to a timing at which the light emitting element actually emits light,

[0592] wherein the driver outputs data corresponding to the delay time measured by the measurement unit. (22)

[0594] The driver of the light emitting element according to (21), further comprising a storage unit that stores data corresponding to the delay time measured by the measurement unit, wherein the driver outputs the data stored in the storage unit.

[0595] List of Reference Signs

[0596] 10 driver

[0597] 11 controller

[0598] 12 laser diode

[0599] 21, 21a PLL unit

[0600] 22, 22a light emitting waveform generating circuit

[0601] 23, 23a, 23a1, 23b1 TDC

[0602] 24 driving unit

[0603] 24R replica driving unit

[0604] 25 logic unit

[0605] 25M storage unit

[0606] 26 temperature sensor

[0607] 27 selector

[0608] 28 attenuator

[0609] 29 dummy load

[0610] 30, 31 multiplexer

[0611] 51 signal processing unit

[0612] 52 distance measuring observation unit

[0613] 53 processing unit

[0614] 61 target

[0615] 70, 70a to 70k, 70m, 70p to 70y distance measuring system

[0616] 12, 121 to 12 N laser diode

[0617] 24, 241 to 24N Driver unit

[0618] 302 Distance measuring sensor unit.

Claims

1. A distance measuring system comprising: a drive unit that causes a light emitting element to emit light and outputs a drive signal for irradiating light to a target; a sensor unit that detects reflected light from the target; a measurement unit that measures a delay time that is a time included from a timing at which a trigger signal for causing the light emitting element to emit light is output to a timing at which the light emitting element actually emits light; and a processing unit that performs processing of calculating a distance to the target based on an output timing of the trigger signal, a light reception timing of the reflected light obtained by the sensor unit, and the delay time, wherein the measurement unit starts counting a time from a rising timing of the trigger signal, ends counting the time at an output timing of the drive signal to the light emitting element, and sets the time count value as the delay time, the distance measuring system further comprising: a copy drive unit that simulates the drive unit, wherein the measurement unit ends counting the time at an output timing of a signal of the copy drive unit, the distance measuring system further comprising a delay amount adjustment unit that adjusts a delay time of a signal by the copy drive unit.

2. The distance measuring system according to claim 1, further comprising a light emission waveform generation unit that generates a light emission pattern signal for causing the light emitting element to emit light. The delay amount of the delay amount adjustment unit is adjusted based on a temperature detected by the temperature sensor.

3. The ranging system of claim 1, further comprising a temperature sensor to detect temperature, wherein, 4. The distance measuring system according to claim 1, wherein the measurement unit starts counting a time from a rising timing of the trigger signal, ends counting the time at an output timing of a signal on an input side of the drive unit, and sets the time count value as the delay time. wherein 5. The distance measuring system according to claim 1, further comprising a plurality of the drive units corresponding to a plurality of the light emitting elements, wherein the measurement unit starts counting a time from a rising timing of the trigger signal, ends counting the time at an output timing of one of the drive signals of the plurality of the drive units, and sets the time count value as the delay time. wherein 6. The distance measuring system according to claim 1, further comprising a selector that selects one of the drive signals output from the plurality of the drive units, wherein the measurement unit ends counting the time at an output timing of the drive signal selected by the selector, and sets the time count value as the delay time. wherein 7. The distance measuring system according to claim 1, further comprising a plurality of the measurement units corresponding to the plurality of the drive units.

8. The distance measuring system according to claim 1, comprising: a storage unit that stores data corresponding to the delay time, wherein the processing unit performs the processing of calculating the distance to the target using the data stored in the storage unit. a signal processing unit that includes the processing unit; and a driver that includes the drive unit, 9. The ranging system of claim 8, further comprising: wherein the storage unit is provided in at least one of the driver and the signal processing unit.

10. The distance measuring system according to claim 1, ​ wherein, The processing unit starts counting time after a time corresponding to the delay time from the output timing of the trigger signal, ends counting time at the light reception timing of the reflected light, and calculates the distance to the target based on the time count result.

11. The ranging system of claim 1, further comprising: a signal processing unit including the processing unit; and a driver including the drive unit, wherein the measurement unit is provided in the signal processing unit, and the measurement unit branches the transmission path of the trigger signal in the signal processing unit, starts counting time from the rising timing of the signal obtained by returning the trigger signal, branches the transmission path of the trigger signal at the input side of the drive unit, ends counting time at the rising timing of the signal obtained by returning the trigger signal, and sets the time count value as the delay time.

12. The ranging system of claim 1, comprising: a signal processing unit including the processing unit; and a driver including the drive unit, wherein the measurement unit is provided in the signal processing unit, and the measurement unit branches the transmission path of the trigger signal in the signal processing unit, starts counting time from the rising timing of the signal obtained by returning the trigger signal, branches the transmission path of the trigger signal at the output side of the drive unit, ends counting time at the rising timing of the signal obtained by returning the trigger signal, and sets the time count value as the delay time.

13. The distance measuring system according to claim 12, further comprising: an attenuator that branches and attenuates the signal level of the signal obtained by returning the trigger signal at the output side of the drive unit; and a buffer that receives the signal attenuated by the attenuator as input and outputs the signal to the signal processing unit.

14. The distance measuring system according to claim 11, further comprising: a virtual load that receives a signal branched from the transmission path of the trigger signal at the input side of the drive unit as input, wherein the virtual load has a time constant corresponding to the time required for a current to flow through the light emitting element to actually emit light, and a signal that has passed through the virtual load is output from the driver to the signal processing unit as the signal obtained by returning the trigger signal.

15. The ranging system of claim 1, further comprising: a plurality of the drive units corresponding to a plurality of the light emitting elements; and a plurality of the measurement units provided corresponding to the plurality of the drive units, wherein each of the plurality of the measurement units branches the transmission path of the trigger signal at the respective output side of the plurality of the drive units, ends counting time at the rising timing of the signal obtained by returning the trigger signal, and sets the time count value as the delay time.

16. The ranging system of claim 15, further comprising: a first multiplexer that selects and outputs one of the output signals of the plurality of the drive units; and a second multiplexer that inputs the output of the first multiplexer to a selected one of the plurality of the measurement units.

17. The distance measuring system according to claim 15, in, the plurality of the light emitting elements includes a first light emitting element and a second light emitting element, and the first light emitting element and the second light emitting element are driven by the plurality of the drive units. The delay time of the light emitting element provided between the first light emitting element and the second light emitting element is obtained by interpolation between the delay time of the first light emitting element and the delay time of the second light emitting element.

18. A driver of a light emitting element, comprising: a driving unit that causes the light emitting element to emit light and outputs a driving signal for irradiating light to a target; and a measuring unit that measures a delay time as a time included in a time from a timing of inputting a trigger signal for causing the light emitting element to emit light to a timing of the light emitting element actually emitting light, wherein the driver outputs data corresponding to the delay time measured by the measuring unit, wherein the measuring unit starts counting a time from a rising timing of the trigger signal, ends counting the time at an output timing of the driving signal to the light emitting element, and sets the time count value as the delay time, the driver further comprising: a copy driving unit that simulates the driving unit, wherein the measuring unit ends counting the time at an output timing of a signal of the copy driving unit, the driver further comprising a delay amount adjustment unit that adjusts a delay time of a signal by the copy driving unit.

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