Light emitting element driving device, optical distance measuring device

Abstract

To effectively utilize power generated in a resistor when a backflow occurs in a light-emitting element drive circuit.SOLUTION: A light-emitting element driving circuit is a circuit for driving a first light-emitting element and a second light-emitting element, and includes a first circuit connected in parallel to the first light-emitting element and having a first diode and a first resistor element connected in series, and a transformer having a primary coil connected in parallel to the first resistor element and a secondary coil connected in parallel to the second light-emitting element.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a light-emitting element driving device and a light distance measuring device.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2021-19194 describes a light-emitting element driving device including a capacitor charged by a power source to supply current to a light-emitting element, a first wiring for flowing current from the capacitor to the light-emitting element, a second wiring through which the current output from the light-emitting element flows, a charging state for charging the capacitor from the power source, a first switch for switching the state of the capacitor to either a discharging state for supplying current from the capacitor to the light-emitting element, a diode reversely connected to the first wiring and the second wiring in parallel with the light-emitting element, and a resistor connected in series with the diode.

[0003] In the above light-emitting element driving device, secondary emission of the light-emitting element is suppressed by the parasitic inductance of the wiring. However, the power generated in the resistor when the reverse flow of current occurs due to the parasitic inductance has been consumed without being effectively utilized.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the objects of the specific aspect according to the present disclosure is to provide a technique capable of effectively utilizing the power generated in a resistor when a reverse flow occurs in a light-emitting element driving circuit.

Means for Solving the Problems

[0006] [1] A light-emitting element driving circuit according to one aspect of the present disclosure is A circuit for driving a first light-emitting element and a second light-emitting element, a first circuit having a first diode and a first resistance element connected in series and connected in parallel to the first light-emitting element, a transformer having a primary-side coil connected in parallel to the first resistance element and a secondary-side coil connected in parallel to the second light-emitting element, and including the above, a light-emitting element driving circuit. [2] An optical distance measuring device according to one aspect of the present disclosure is, the light-emitting element driving circuit of [1] above, a first light-emitting element and a second light-emitting element driven by the light-emitting element driving circuit, and including the above, an optical distance measuring device.

[0007] In the present disclosure, the state where "member A is connected to member B" means that in addition to the case where member A and member B are physically directly connected, member A and member B do not substantially affect their electrical connection state, or do not impair the functions and effects achieved by their connection, and also includes the case where they are indirectly connected via other members.

[0008] According to the above configuration, it is possible to effectively utilize the power generated by the resistor when a reverse current occurs in the light-emitting element driving circuit.

Brief Description of Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0010] FIG. 1 is a circuit diagram showing the configuration of a light-emitting element drive circuit according to an embodiment. The illustrated light-emitting element drive circuit is for driving two light-emitting elements 1 and 2, and includes a capacitor, resistor elements 11, 13, 14, 15, diodes 12, 16, a transformer 17, a field effect transistor 18, and a switching control unit 20. The light-emitting elements 1 and 2 are semiconductor light-emitting elements such as an LED (Light Emitting Diode) or an LD (Laser Diode), for example.

[0011] Note that the light-emitting element 1 corresponds to the "first light-emitting element", the light-emitting element 2 corresponds to the "second light-emitting element", the diode 12 corresponds to the "first backflow prevention diode", the diode 16 corresponds to the "second backflow prevention diode", the resistor element 13 corresponds to the "first resistor element", the resistor element 15 corresponds to the "second resistor element", the resistor element 14 corresponds to the "third resistor element", and the field effect transistor 18 corresponds to the "switching element", respectively.

[0012] One end of the resistor element 11 is connected to the capacitor and the power supply VDD, and the other end is connected to the anode of the light-emitting element 1, functioning as a limiting resistor. The resistor element 11 is connected between the capacitor, the power supply VDD, and the light-emitting element 1. The cathode of the light-emitting element 1 is connected to one input / output terminal (source / drain) of the field effect transistor 18.

[0013] The diode 12 is a reverse current prevention diode for protecting the light-emitting element 1. Its anode is connected to the cathode of the light-emitting element 1, and its cathode is connected to the resistance element 13.

[0014] One end of the resistance element 13 is connected to the cathode of the diode 12, and the other end is connected to the anode of the light-emitting element 1 and the other end of the resistance element 11. The diode 12 and the resistance element 13 are connected in series, and the whole of them (the first circuit composed of the diode 12 and the resistance element 13) is connected in parallel to the light-emitting element 1.

[0015] One end of the resistance element 14 is connected to the cathode of the diode 12, and the other end is connected to one end of the primary coil of the transformer 17. The resistance element 14 is connected in series with the primary coil of the transformer 17, and the whole of them (the third circuit composed of the resistance element 14 and the primary coil) is connected in parallel to the resistance element 13.

[0016] One end of the resistance element 15 is connected to one end of the secondary coil of the transformer 17, and the other end is connected to the anode of the light-emitting element 2. The light-emitting element 2 has its anode connected to the other end of the resistance element 15 and its cathode connected to the reference potential terminal (GND2). The resistance element 15 is connected in series with the light-emitting element 2, and the whole of them (the second circuit composed of the resistance element 15 and the light-emitting element 2) is connected in parallel to the secondary coil of the transformer 17.

[0017] The diode 16 is a reverse current prevention diode for protecting the light-emitting element 2. Its anode is connected to the cathode of the light-emitting element 2, and its cathode is connected to the anode of the light-emitting element 2. The diode 16 is connected in parallel to the light-emitting element 2.

[0018] The primary coil of transformer 17 has one end connected to resistor 14 and the other end connected to the anode of light-emitting element 1 and one end of resistor 13. Also, the other end of the primary coil of transformer 17 is connected to one end of resistor 14. The primary coil of transformer 17 and resistor 14 are connected in series, and their entirety is connected in parallel to resistor 14. Further, one end of the secondary coil of transformer 17 is connected to one end of resistor 15, and the other end is connected to the reference potential terminal (GND2).

[0019] One input / output terminal (source / drain) of field-effect transistor 18 is connected to the cathode of light-emitting element 1. The other input / output terminal is connected to the reference potential terminal (GND1). Also, the control terminal (gate) of field-effect transistor 18 is connected to switching control unit 20. For field-effect transistor 18, for example, a gallium nitride FET (GaNFET) can be preferably used.

[0020] Switching control unit 20 is connected to the control terminal of field-effect transistor 18 and applies a control voltage to the control terminal. When this control voltage is applied to the control terminal, the conduction state and non-conduction state of field-effect transistor 18 are switched. When field-effect transistor 18 is in the conduction state, current flows through light-emitting element 1, and light-emitting element 1 can be turned on. When field-effect transistor 18 is in the non-conduction state, no current flows through light-emitting element 1, and the light-emitting element can be turned off.

[0021] Figure 2 is a diagram for explaining the operation of the light-emitting element drive circuit. Here, for easy understanding, lines representing the flow of current are shown in the circuit shown in Figure 1. When a predetermined control voltage (pulse voltage) is applied from switching control unit 20 to the control terminal of field-effect transistor 18 and field-effect transistor 18 becomes conductive, current flows from the capacitor charged by power supply VDD through resistor 11 to light-emitting element 1 (see path a in the figure).

[0022] Next, when a predetermined control voltage is applied from the switching control unit 20 to the control terminal of the field-effect transistor 18 and the field-effect transistor 18 enters a non-conducting state, no current flows through the light-emitting element 1.

[0023] At this time, a reverse current due to a surge voltage generated by a parasitic inductance (not shown) occurs, and a reverse current flows through the diode 12 (see path b in the figure). This reverse current branches into a current path including the resistor element 13 and a current path including the resistor element 14 after passing through the diode 12 (see paths b1 and b2 in the figure).

[0024] Due to the current flowing through path b1, a potential V1 is generated in the resistor element 13. Due to the influence of this potential V1, a potential V2 is generated in the secondary-side coil of the transformer 17. Due to this potential V2, current flows through the resistor element 13 and the light-emitting element 2 (see path c in the figure). Thereby, the light-emitting element 2 can be turned on. Therefore, the power (potential V1) generated by the resistor element 13 can be effectively utilized to turn on the light-emitting element 2.

[0025] Note that since the control voltage applied from the switching control unit 20 to the control terminal of the field-effect transistor 18 is a pulse voltage, that is, a voltage in which the on-voltage and the off-voltage are repeated at a predetermined cycle, the light-emitting element 1 is pulse-driven, and the light-emitting element 2 is also pulse-driven.

[0026] FIG. 3(A) is a waveform diagram showing an example of the current flowing through the light-emitting element 1. Current flows through the light-emitting element 1 in a manner generally responsive to the pulse voltage output from the switching control unit 20, and the light-emitting element 1 is turned on. FIG. 3(B) is a waveform diagram showing an example of the potential V1 of the resistor element 13. It can be seen that the potential V1 is generated in the resistor element 13 due to the reverse current.

[0027] FIG. 4(A) is a waveform diagram showing an example of the voltage V2 generated on the secondary side of the transformer. It can be seen that the polarity of the electromotive force V1 generated by the resistance element 13 is converted by the transformer 17. FIG. 4(B) is a waveform diagram showing an example of the current flowing through the light-emitting element 2. A current flows through the light-emitting element 2 in a form generally responding to the potential V2, and the light-emitting element 2 lights up.

[0028] FIG. 5 is a waveform diagram showing an example of the current flowing through the light-emitting elements 1 and 2. The current starts to flow through the light-emitting element 2 slightly after the timing when the current starts to flow through the light-emitting element 1. From this, it can be seen that after the light-emitting element 1 lights up, the light-emitting element 2 lights up with a slight delay.

[0029] The delay time from the time when the light-emitting element 1 lights up to the time when the light-emitting element 2 lights up is substantially constant as long as there is no change in the circuit elements. Therefore, as an example of a method of utilizing the light from the light-emitting element 2, for example, it can be applied to a light distance measuring device, and the light from the light-emitting element 2 can be used to detect the emission timing of the emission light from the light-emitting element 1 as the distance measuring light. Hereinafter, an example of a method of utilizing the light from the light-emitting element 2 will be described in detail.

[0030] FIG. 6 is a schematic diagram showing the configuration of a light distance measuring device according to an embodiment. The light distance measuring device shown in FIG. 6 emits light to the outside and detects the distance to an object or generates a distance image by receiving the reflected light generated by the light, and includes the light-emitting element driving circuit according to the above-described embodiment. The light distance measuring device includes a light source unit 30, an information processing unit 31, and a light receiving unit 50. The light source unit 30 includes the light-emitting elements 1 and 2, a light receiving element 21, a reflector 22, circuit boards 25 and 26, an information processing unit 31, and connectors 32 and 33. The light-emitting elements 1 and 2 correspond to the light-emitting elements 1 and 2 that were the driving targets in the light-emitting element driving circuit of the above-described embodiment. The light receiving unit 50 includes a light receiving element 51, an optical filter 52, and a lens 53.

[0031] The light-emitting element 1 generates and emits light that is released to the outside for optical distance measurement. The emitted light generated by the light-emitting element 1 is reflected by a reflector 22 disposed in the light-emitting direction of the light-emitting element 1 and released to the outside of the light source unit 30. The light-emitting element 1 can be composed of a semiconductor light-emitting element such as an LED or an LD (Laser Diode). Also, according to the application of the optical distance measurement device, the light-emitting element 1 can be selected to emit light in a wavelength band suitable for the application.

[0032] The reflector 22 has a reflecting surface, is disposed at a position where the light emitted from the light-emitting element 1 can be incident, and emits the reflected light into the target space. The reflector 22 can be a fixed reflector or a scanning-type reflector that emits in various directions within a predetermined range. For example, as the reflector 22, a two-dimensional deflector (MEMS mirror) configured to be rotatable in each of two orthogonal directions can also be used. When using an MEMS mirror, an MEMS driver is connected, and a drive signal for controlling the operation of the MEMS mirror is generated and supplied to the MEMS mirror in response to deflection control from a control unit 35 described later.

[0033] The light-emitting element 2 generates and emits light when the light-emitting element 1 is lit. The emitted light generated by the light-emitting element 2 is received by a light-receiving element 21 disposed in the light-emitting direction of the light-emitting element 2. The light-receiving element 21 outputs an electrical signal (light-receiving signal) corresponding to the intensity of the received light.

[0034] The circuit board 25 is a board provided with the light-emitting element drive circuit of the above-described embodiment. In this embodiment, the light-emitting elements 1 and 2 are also mounted on this circuit board 25 together with each circuit element constituting the light-emitting element drive circuit. A connector 32 for electrically connecting the light-emitting element drive circuit and the information processing unit 31 is mounted on this circuit board 25. A control signal (light-emitting instruction signal) is supplied from the information processing unit 31 to the field-effect transistor 18 of the light-emitting element drive circuit via this connector 32.

[0035] The circuit board 26 is a board that includes a drive circuit for the light-receiving element 21 and the like. In this embodiment, the light-receiving element 21 is also mounted on this circuit board 26. Further, in this embodiment, the circuit board 26 is disposed above the circuit board 25 in the drawing. The circuit board 26 is mounted with a connector 33 for electrically connecting the light-receiving element 21 and its drive circuits to the information processing unit 31. An electrical signal (or a signal obtained by amplifying this, etc.) output from the light-receiving element 21 is output to the information processing unit 31 via this connector 33.

[0036] The light-receiving element 21 is disposed on one surface (the lower surface in the drawing) of the circuit board 26. The light-receiving element 21 is disposed so as to face the light-emitting element 2, receives the emitted light of the light-emitting element 2, and outputs an electrical signal corresponding to the light intensity. Thereby, the light-receiving element 21 has a function of grasping the light-emitting states and emission timing of the light-emitting element 2 and the light-emitting element 1. Further, the light-emitting element 2 and the light-receiving element 21 are disposed at a location where it is difficult for the light-receiving element 21 to receive direct light from the light-emitting element 1 and internal reflected light of the light emitted from the light-emitting element 1 within the light-emitting unit. As the light-receiving element 21, a photodiode (PD) can be used. As the PD, a PN-type PD, a PIN-type PD, or an APD (Avalanche Photodiode) can be used.

[0037] The light-receiving element 51, the optical filter 52, and the lens 53 are disposed such that reflected light generated by the object enters the light-receiving unit 50 and is received by the light-receiving element 51. The light-receiving element 51 receives the light emitted from the light-emitting element 2 and reflected from the object, and outputs an electrical signal corresponding to the light intensity. As the light-receiving element 51, a PD, a photomultiplier tube, a photoconductive element, or the like can be used. The lens 53 condenses the reflected light from the object. The optical filter 52 transmits the wavelength of the light from the light-emitting element 1 and blocks light in a wavelength range different from the wavelength of the light from the light-emitting element 1.

[0038] The information processing unit 31 controls the lighting and extinguishing of the light-emitting element 1, calculates the distance to the object based on the electrical signal (light reception signal) indicating the detection result by the light-receiving element 21 and the electrical signal output from the light-receiving element 51 in the light-receiving unit 50, and provides information (or a distance image) of the distance to an external device (not shown). The information processing unit 31 of the present embodiment performs optical distance measurement by the dTOF (direct Time Of Flight) method.

[0039] Specifically, the relative distance to the object is calculated based on the time difference Δt (t1 - t2) between the emission time t1 of the emitted light from the light-emitting element 1 and the reception time t2 of the reflected light from the object by this emitted light. The distance D is obtained by calculating {C × Δt} / 2 (C: the speed of light).

[0040] Here, the emission time t1 of the emitted light from the light-emitting element 1 is specified based on the electrical signal output from the light-receiving element 21. Also, the reception time t2 of the reflected light from the object is specified based on the electrical signal output from the light-receiving element 51. When the light-emitting element drive circuit of the present embodiment is used as described above, a certain delay time occurs from the time when the light-emitting element 1 lights up to the time when the light-emitting element 2 lights up. Therefore, when obtaining the distance D, the emission time t1 is obtained by performing correction to subtract this delay time, and the above time difference Δt is obtained using the emission time t1 obtained by this correction.

[0041] Thus, by using the light-emitting elements 1 and 2 driven by the light-emitting element driving circuit of the present embodiment, unlike the prior art, it is not necessary to dispose on the optical axis of the emitted light of the light-emitting element 1 a splitter for branching a part of the emitted light of the light-emitting element 1 in order to obtain the emission timing t1 of the emitted light of the light-emitting element 1, a reflector for making the light obtained by the branching incident on a light-receiving element, or the like. Therefore, there is an advantage that it is easy to reduce the size of the light source unit 30. Further, when attempting to use the internal reflected light generated in the light source unit 30 by the emitted light of the light-emitting element 1 as the emitted light of the light-emitting element 1, it is impossible to determine from where the reflected light is, and the detection accuracy of the emission timing t1 may decrease. However, by using the light-emitting element driving circuit of the present embodiment, the detection accuracy of the emission timing t1 can be improved.

[0042] FIG. 7 is a diagram showing a configuration example of the information processing unit 31 and the like in the case of monitoring the lighting state of the light-emitting element 1 using the electrical signal of the light-receiving element 21. Note that only the configuration necessary for monitoring is shown. The information processing unit 31 shown in FIG. 7 includes a control unit 35, a signal generation unit 36, and a determination unit 40. Further, the light source unit 30 includes a driving unit 37, a light-receiving unit 38, and a current-voltage conversion unit 39. The light-receiving unit 50 includes a light-receiving unit 54 and a current-voltage conversion unit 55.

[0043] The control unit 35 controls the overall operation of the information processing unit 31 and is configured by using, for example, a microcomputer including a processor or the like.

[0044] The signal generation unit 36 is connected to the control unit 35 and generates a signal for operating the driving unit 37 under the control of the control unit 35.

[0045] The drive unit 37 is connected to the signal generation unit 36, and lights up the light-emitting element 1 and the light-emitting element 2 based on the signal input from the signal generation unit 36. This drive unit 37 has a configuration corresponding to the light-emitting element drive circuit of the above-described embodiment. Further, when a scanning reflector such as a MEMS mirror is used as the reflector 22, in the control unit 35, based on the acquired (angle change information of the reflector) information, the signal generation unit 36 and the drive unit 37 control the lighting and extinguishing of the light-emitting element 1.

[0046] The light receiving unit 38 receives the electrical signal output from the light receiving element 21 and performs amplification processing and the like.

[0047] The current-voltage conversion unit 39 is connected to the light receiving unit 38, converts the current signal, which is the electrical signal output from the light receiving unit 38, into a voltage signal within a predetermined voltage range, and outputs it to the determination unit 40.

[0048] The determination unit 40 is connected to each of the control unit 35, the signal generation unit 36, and the current-voltage conversion unit 39, and based on the signal output from the signal generation unit 36 (the signal for controlling the light emission timing of the light-emitting element 1) and the electrical signal output from the light receiving element 21, and based on the signal output from the current-voltage conversion unit 39, determines the operating state of the light-emitting element 1 or / and the light-emitting element 2. The determination result is output to the control unit 35.

[0049] The light receiving unit 54 receives the electrical signal output from the light receiving element 51 and performs amplification processing and the like.

[0050] The current-voltage conversion unit 55 is connected to the light receiving unit 54, converts the current signal, which is the electrical signal output from the light receiving unit 54, into a voltage signal within a predetermined voltage range, and outputs it to the control unit 35.

[0051] FIG. 8 is a diagram for explaining the determination content by the determination unit 40. A signal output from the signal output unit 36 is input to the input unit (1) of the determination unit 40, and a signal output from the current-voltage conversion unit 39 is input to the input unit (2). Here, when the magnitude of the voltage value of each signal is relatively low, it is expressed as "0", and when it is relatively high, it is expressed as "1". Each signal takes either the state of "0" or "1".

[0052] When the magnitude of the voltage value of the signal input to either the input unit (1) or (2) is "0", the operation of the light-emitting element 1 is determined to be "normal". Since the light-emitting element 1 is turned off, and accordingly the light-emitting element 2 is also turned off, no light is detected by the light-receiving element 21, and the state matches the determination result.

[0053] When the magnitude of the voltage value of the signal input to the input unit (1) is "0" and the magnitude of the voltage value of the signal input to the input unit (2) is "1", the operation of the light-emitting element 1 is determined to be "abnormal". Although the light-emitting element 1 should originally be turned off and the light-emitting element 2 should also be turned off accordingly, light is detected by the light-receiving element 21, so it is considered that the light-emitting element 1 or the light-emitting element 2 is lit abnormally.

[0054] Also, when the magnitude of the voltage value of the signal input to the input unit (1) is "1" and the magnitude of the voltage value of the signal input to the input unit (2) is "0", the operation of the light-emitting element 1 is determined to be "abnormal". Although the light-emitting element 1 should originally be lit and the light-emitting element 2 should also be lit accordingly, no light is detected by the light-receiving element 21, so it is considered that the light-emitting element 1 or the light-emitting element 2 is turned off abnormally.

[0055] When the magnitude of the voltage value of the signal input to either the input unit (1) or (2) is "1", the operation of the light-emitting element 1 is determined to be "normal". Since the light-emitting element 1 is lit, and accordingly the light-emitting element 2 is also lit, light is detected by the light-receiving element 21, and the state matches the determination result.

[0056] In the control unit 35 that has received these determination results, when the determination result is "abnormal", measures such as stopping the lighting of the light-emitting element 1 are taken.

[0057] According to the above-described embodiments, the electric power generated in the resistor during reverse current generation in the light-emitting element drive circuit can be effectively utilized. As an example, when the light-emitting element drive circuit of the above-described embodiment is applied to a light distance measuring device, the emission timing of the emitted light can be accurately obtained. And since the emission timing can be accurately obtained, the accuracy of the detection distance can be improved. Also, an abnormal operation of the light-emitting element in the light distance measuring device can be monitored. Even when a scanning reflector such as a MEMS mirror is used as the reflector 22, the accuracy of obtaining the emission timing of the emitted light is improved, so the accuracy of the emission direction information of the emitted light is improved, and thus the accuracy of the distance information by the light distance measuring device can be improved.

[0058] Note that the present disclosure is not limited to the content of the above-described embodiments, and various modifications can be made and implemented within the scope of the gist of the present disclosure. For example, in the light-emitting element drive circuit of the above-described embodiment, a field-effect transistor is cited as an example of the switching element, but the switching element is not limited to this.

[0059] Also, in the above-described embodiment, one light-emitting element 1 is shown as the light-emitting element that lights up by receiving the voltage from the power supply VDD, but a plurality of light-emitting elements may be used. Similarly, one light-emitting element 2 is shown as the light-emitting element that lights up by receiving the voltage obtained using the transformer 17, but a plurality of light-emitting elements may be used. In any case, the plurality of light-emitting elements may be connected in series or in parallel with each other. Also, in the above-described embodiment, it is shown that the signal from the light-receiving unit is output to the control unit 35, but the signal from the light-receiving unit can also be output to the determination unit 40 and used for various determinations.

[0060] The present disclosure has the following features. (Appendix 1) A circuit for driving a first light-emitting element and a second light-emitting element, having a first reverse-current prevention diode and a first resistance element connected in series, and a first circuit connected in parallel to the first light-emitting element, a transformer having a primary-side coil connected in parallel to the first resistance element and a secondary-side coil connected in parallel to the second light-emitting element, A light-emitting element driving circuit including the above. (Appendix 2) Further including a second resistance element connected in series to the second light-emitting element to form a second circuit, wherein the second circuit is connected in parallel to the secondary-side coil of the transformer, The light-emitting element driving circuit according to Appendix 1. (Appendix 3) Further including a third resistance element connected in series to the primary-side coil of the transformer to form a third circuit, wherein the third circuit is connected in parallel to the first resistance element, The light-emitting element driving circuit according to Appendix 1 or 2. (Appendix 4) Further including a second reverse-current prevention diode connected in parallel to the second light-emitting element, The light-emitting element driving circuit according to any one of Appendices 1 to 3. (Appendix 5) Further including a switching element connected in series to the first light-emitting element and the first circuit, The light-emitting element driving circuit according to any one of Appendices 1 to 4. (Appendix 6) The light-emitting element driving circuit according to any one of Appendices 1 to 5, a first light-emitting element and a second light-emitting element driven by the light-emitting element driving circuit, An optical distance measuring device including the above. (Appendix 7) The first light-emitting element generates emitted light for distance measurement, The second light-emitting element generates emitted light for detecting the emission timing of the emitted light of the first light-emitting element, The optical distance measuring device according to Appendix 6. (Appendix 8) a first light-receiving element that receives the emitted light of the second light-emitting element; a second light-receiving element that receives the reflected light generated by the emitted light of the first light-emitting element; an information processing unit that outputs a control signal for controlling the lighting of the first light-emitting element, determines the emission timing of the emitted light of the first light-emitting element based on a light-receiving signal indicating a detection result by the first light-receiving element, and determines the mutual distance from the object based on the emission timing and the light-receiving signal by the second light-receiving element; The optical distance measuring device according to Supplementary Note 7, further comprising the above. (Supplementary Note 9) The information processing unit includes a determination unit that determines the presence or absence of an operation abnormality of the first light-emitting element based on each state of the control signal and the light-receiving signal. The optical distance measuring device according to Supplementary Note 8.

Explanation of Signs

[0061] 1, 2: Light-emitting elements, 11, 13, 14, 15: Resistance elements, 12, 16: Diodes, 17: Transformers, 18: Field-effect transistors, 20: Switching control unit, 21, 51: Light-receiving elements, 22: Reflector, 25, 26: Circuit boards, 30: Light source unit, 31: Information processing unit, 32, 33: Connectors

Claims

1. A circuit for driving a first light-emitting element and a second light-emitting element, comprising a first reverse-current prevention diode and a first resistance element connected in series, and a first circuit connected in parallel to the first light-emitting element, a transformer having a primary-side coil connected in parallel to the first resistance element and a secondary-side coil connected in parallel to the second light-emitting element, The light-emitting element driving circuit comprising the above.

2. further comprising a second resistance element connected in series with the second light-emitting element to form a second circuit, The second circuit being connected in parallel to the secondary-side coil of the transformer, The light-emitting element driving circuit according to claim 1.

3. further comprising a third resistance element connected in series with the primary-side coil of the transformer to form a third circuit, The third circuit being connected in parallel to the first resistance element, The light-emitting element driving circuit according to claim 1.

4. further comprising a second reverse-current prevention diode connected in parallel to the second light-emitting element, The light-emitting element driving circuit according to claim 1.

5. further comprising a switching element connected in series with the first light-emitting element and the first circuit, The light-emitting element driving circuit according to claim 1.

6. The light-emitting element driving circuit according to claim 1, a first light-emitting element and a second light-emitting element driven by the light-emitting element driving circuit, The optical distance measuring device comprising the above.

7. The first light-emitting element generates emitted light for distance measurement, The second light-emitting element generates emitted light for detecting the emission timing of the emitted light of the first light-emitting element, The optical distance measuring device according to claim 6.

8. a first light-receiving element that receives the emitted light of the second light-emitting element, a second light-receiving element that receives the reflected light generated by the emitted light of the first light-emitting element, an information processing unit that outputs a control signal for controlling the lighting of the first light-emitting element, obtains the emission timing of the emitted light of the first light-emitting element based on a light-receiving signal indicating the detection result by the first light-receiving element, and obtains the mutual distance from the object based on the emission timing and the light-receiving signal by the second light-receiving element, The optical distance measuring device according to claim 7, further comprising the above.

9. The information processing unit has a determination unit that determines the presence or absence of an operation abnormality of the first light-emitting element based on each state of the control signal and the light-receiving signal by the first light-receiving element, The optical distance measuring device according to claim 8.

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