Light-emitting device and distance measurement device

Abstract

[Problem]: To minimize the influence of abnormality without causing a through current to flow through a drive circuit. [Solution] This light-emitting device comprises: a plurality of light-emitting elements each having first and second terminals; a plurality of first terminal wires electrically connected to the first terminals of the light-emitting elements; a plurality of second terminal wires each electrically connected to N of the light-emitting elements; a plurality of selection circuits electrically connected to the first or second terminal wires to select the light-emitting elements that are to emit light; a plurality of drive circuits for driving the plurality of light-emitting elements; and a plurality of capacitors for storing charges to be supplied to the plurality of light-emitting elements. The selection circuits include a first switch that switches whether or not to charge a corresponding capacitor among the plurality of capacitors, and a second switch that switches whether or not to discharge the electric charge of the corresponding capacitor. A selection circuit connected to a light-emitting element that is not to emit light switch-controls the second switch when an abnormality is detected in the light-emitting element that is not to emit light.

Description

Light emitting device and distance measuring device

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

[0002] LiDAR (Light Detection and Ranging) is one method of obtaining distance information. LiDAR shines light onto the object for which distance information is to be obtained, and estimates the distance based on the information obtained from the light reflected by the object. One of the LiDAR distance measurement methods is the time of flight (ToF) method. With ToF, distance information is obtained by calculating the time it takes for the emitted light to be reflected by the object and return.

[0003] In ranging systems that use ToF, a structure in which the light-emitting unit and light-receiving unit do not have any physically moving parts is called solid-state LiDAR. Solid-state LiDAR, for example, uses an array of light-emitting units to select the location from which light is emitted and project light onto the intended irradiation area. By sequentially switching the light-emitting locations within the light-emitting unit, it is possible to create a light-emitting system that scans light across a two-dimensional area without a physical scanning mechanism. The light of the light-emitting channel selected by the light-emitting system is reflected by the target and received at the location of the light-receiving element that corresponds to the light-emitting channel.

[0004] This type of light-emitting system includes a light source in which laser diodes are arranged in an array and a drive circuit, and is capable of driving the laser diodes of a selected light-emitting channel. The absence of any physically moving parts reduces the risk of breakdowns in situations where high reliability is required (see Patent Document 1). Patent Document 1 proposes a method in which multiple anodes and cathodes are arranged in a matrix and driven individually.

[0005] Special Publication No. 2022-526998

[0006] In an existing light-emitting system in which multiple anodes and cathodes are arranged in a matrix and driven individually, as in Patent Document 1, if an abnormality occurs in which the anode and cathode of any light-emitting element are short-circuited, a through current flows through a drive circuit that controls the charging and discharging of a capacitor that holds charge corresponding to the current flowing through each light-emitting element, making it impossible to charge the capacitor normally and preventing the desired light-emitting element from emitting light normally.Furthermore, the through current flowing through the drive circuit may destroy the circuit elements that make up the drive circuit.

[0007] Therefore, the present disclosure provides a light-emitting device and a distance measuring device that can prevent a through current from flowing through the drive circuit even if an abnormality occurs in which the anode and cathode of a light-emitting element are short-circuited, and that can minimize the impact of the abnormality.

[0008] In order to solve the above problems, according to the present disclosure, there is provided a light emitting device comprising: a plurality of light emitting elements arranged in a two-dimensional array, each having a first and a second terminal; N first wirings (N is an integer of 2 or more) extending in a first direction, and N second wirings extending in a second direction intersecting the first direction and electrically connected to the N first wirings, respectively; a plurality of first terminal wirings electrically connected to the first terminals of the light emitting elements; a plurality of second terminal wirings electrically connected to the second terminals of the light emitting elements, each electrically connected to N of the light emitting elements; a plurality of selection circuits electrically connected to one of the first and second terminal wirings and selecting the light emitting elements to be light emitting; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and driving the plurality of light emitting elements; and a plurality of capacitors electrically connected to the one of the first and second terminal wirings and storing electric charge to be supplied to the plurality of light emitting elements, wherein each of the plurality of selection circuits comprises: a first switch which switches whether or not to charge a corresponding one of the plurality of capacitors; a second switch that switches whether or not to discharge the charge in the corresponding capacitor, and the selection circuit connected to a light-emitting element that is not to emit light selects whether to continue to hold the charge in the corresponding capacitor or to discharge the charge by switching and controlling the second switch.

[0009] The selection circuit connected to a light-emitting element that is not to emit light may turn off the second switch to stop discharging from the corresponding capacitor when an abnormality occurs in which the anode and cathode of the light-emitting element that is not to emit light are short-circuited.

[0010] The selection circuit connected to the light-emitting element not to emit light may turn off the second switch and continue to hold charge in the corresponding capacitor when the light-emitting element not to emit light operates normally.

[0011] The present invention may further comprise a plurality of third switches arranged between the plurality of capacitors and the plurality of light-emitting elements, for switching whether or not to discharge the charge of the plurality of capacitors, and the discharge current from the capacitors connected to the light-emitting elements that are not to emit light may flow to a reference voltage node through the corresponding third switch without flowing to the light-emitting elements that are not to emit light.

[0012] The impedance of the wiring between each of the plurality of capacitors and the corresponding third switch may be smaller than the impedance of the wiring between each of the plurality of capacitors and the corresponding light-emitting element.

[0013] The length of the wiring between each of the plurality of capacitors and the corresponding third switch may be shorter than the length of the wiring between each of the plurality of capacitors and the corresponding light-emitting element.

[0014] The third switch connected to the light-emitting element that is not to be emitted may be turned on in accordance with the timing at which the light-emitting element that is to be emitted is driven, and a discharge current may be passed from the capacitor connected to the light-emitting element that is not to be emitted to a reference voltage node.

[0015] In the event of an abnormality in which the anode and cathode of the non-light-emitting element are short-circuited, the third switch connected to the non-light-emitting element may be turned on, and the discharge current of the capacitor connected to the non-light-emitting element may be passed to a reference voltage node rather than to the non-light-emitting element.

[0016] The light emitting element may further include a charge adjustment unit that adjusts the amount of charge to be charged to at least one of the plurality of capacitors connected to the light emitting element to be illuminated when an abnormality is detected in at least one of the light emitting elements.

[0017] When an abnormality is detected in at least one of the light-emitting elements, the charge adjustment unit may reduce the amount of charge charged to the capacitor connected to the light-emitting element in which the abnormality was detected and the capacitor connected to the light-emitting element to be emitted, compared to the amount of charge charged before the abnormality was detected.

[0018] When an abnormality is detected in at least one of the light-emitting elements, the plurality of selection circuits may select, as a new light-emitting element, a light-emitting element connected to the drive circuit different from the abnormal light-emitting element.

[0019] The light emitting device may further include an abnormality detection unit that detects an abnormality in at least one of the light emitting elements, wherein the plurality of selection circuits select as the light emitting element a light emitting element connected to the drive circuit different from the light emitting element whose abnormality has been detected by the abnormality detection unit, and the abnormality detection unit may output an abnormality detection signal to the outside.

[0020] When an abnormality is detected in at least one of the light-emitting elements, the multiple selection circuits may select two or more light-emitting elements from the multiple light-emitting elements that are located in locations that do not simultaneously enter the human eye as light-emitting targets.

[0021] The light emitting element may be provided with a non-light emitting portion capable of flowing a portion of the discharge current of the capacitor connected to the light emitting element to be illuminated, and when an abnormality is detected in at least one of the light emitting elements, the discharge current of the capacitor connected to the light emitting element to be illuminated may be distributed and flow between the light emitting element to be illuminated and the non-light emitting portion.

[0022] The non-light-emitting section may have a plurality of non-light-emitting regions corresponding to the plurality of light-emitting elements, and when an abnormality is detected in at least one of the light-emitting elements, the discharge current of the capacitor connected to the light-emitting element to be illuminated may be distributed and flow among the non-light-emitting regions, the number of which is the same as the number of light-emitting elements to be illuminated, and the light-emitting elements to be illuminated.

[0023] The non-light-emitting portion may have a number of non-light-emitting regions that is smaller than the number of the plurality of light-emitting elements, and when an abnormality is detected in at least one of the light-emitting elements, the discharge current of the capacitor connected to the light-emitting element to be illuminated may be distributed and flow among the non-light-emitting regions, the number of which is smaller than the total number of the light-emitting elements to be illuminated, and the light-emitting elements to be illuminated.

[0024] The non-light-emitting region may be a non-light-emitting body having the same element structure as the light-emitting element, or may be a resistive element.

[0025] The plurality of light emitting elements may be vertical cavity surface emitting lasers (VCSELs) or other types of surface emitting laser elements.

[0026] The VCSEL may have a plurality of mesa portions each emitting laser light, and some of the plurality of mesa portions may have a non-light-emitting structure.

[0027] According to the present disclosure, a distance measuring device comprises: a light emitting unit that emits light toward a subject; a light receiving unit that receives light that is reflected by the subject from the emitted light; and a distance measuring unit that measures a distance to the subject based on the light emitted by the light emitting unit and the light received by the light receiving unit, wherein the light emitting unit includes: a plurality of light emitting elements arranged in a two-dimensional array, each having a first and a second terminal; N first wirings (N is an integer of 2 or more) extending in a first direction, and N second wirings that extend in a second direction intersecting the first direction and are electrically connected to the N first wirings, respectively; a plurality of first terminal wirings that are electrically connected to the first terminals of the light emitting elements; a plurality of second terminal wirings that are electrically connected to the second terminals of the light emitting elements, each second terminal wiring being electrically connected to N of the light emitting elements; a plurality of selection circuits that are electrically connected to one of the first and second terminal wirings and that select the light emitting elements to be light emitting; and a plurality of drive circuits that are electrically connected to the other of the first and second terminal wirings and that drive the plurality of light emitting elements. a plurality of capacitors electrically connected to one of the first and second terminal wirings and storing electric charge to be supplied to the plurality of light-emitting elements, wherein each of the plurality of selection circuits has a first switch that switches whether or not to charge a corresponding one of the plurality of capacitors, and a second switch that switches whether or not to discharge the electric charge of the corresponding capacitor, and the selection circuit connected to a light-emitting element that is not to emit light controls switching of the second switch when an abnormality is detected in the light-emitting element that is not to emit light.

[0028] Circuit diagram of the light-emitting device according to the first embodiment. Circuit diagram showing the connection relationship of the selection circuit, light-emitting element, and drive circuit. Timing diagram corresponding to the circuit diagram of FIG. 2. Diagram showing a state where an abnormality occurs in which the anode and cathode of the light-emitting element of a specific channel are short-circuited. Circuit diagram showing the main part of the light-emitting device according to the first embodiment, and FIG. 6 is a timing diagram corresponding to the circuit diagram of FIG. 5. Circuit diagram for explaining the problem of the light-emitting device according to the first embodiment. Timing diagram corresponding to the circuit diagram of FIG. 6. Circuit diagram of the main part of the light-emitting device according to the second embodiment. Timing diagram corresponding to the circuit diagram of FIG. 8. Diagram showing the path through which the discharge current of the capacitor flows when the third switch is off. Circuit diagram of the light-emitting device according to the third embodiment. Timing diagram corresponding to the circuit diagram of FIG. 11. Timing diagram corresponding to the circuit diagram of FIG. 11 when current control is not performed from the selection circuit. Diagram showing the signal waveforms of FIGS. 12 and 13 superimposed. Circuit diagram of the light-emitting device according to the fourth embodiment. Diagram schematically showing the light-emitting position when all the light-emitting elements perform a normal light-emitting operation and the light-receiving position of a light-receiving device not shown. Diagram schematically showing the light-emitting position and the light-receiving position not shown when some of the light-emitting elements cause a short-circuit abnormality. Circuit diagram of the light-emitting device according to the fifth embodiment. Circuit diagram of the light-emitting device according to the sixth embodiment. Circuit diagram of the light-emitting device according to a modified example of the sixth embodiment. Cross-sectional view showing an example of the cross-sectional structure of a light-emitting device with a VCSEL structure. Perspective view schematically showing the difference in structure between a light-emitting element and a dummy light-emitting element. Cross-sectional view of the dummy light-emitting element of FIG. 21. Perspective view schematically showing a light-emitting element and a dummy light-emitting element having a structure different from that of FIG. 21. Cross-sectional view of the mesa portion of the dummy light-emitting element of FIG. 23. Cross-sectional view of the mesa portion of the dummy light-emitting element according to a modified example of FIG. 24A. Cross-sectional view of a ToF sensor in which a light-emitting device and a light-receiving device are arranged on the same support member. Block diagram showing a configuration example of a distance measuring device as an implementation example of the light-emitting device according to the present embodiment. Explanation diagram of the STL method. Explanation diagram of the distance measuring principle of the STL method. Block diagram showing an example of the schematic configuration of a vehicle control system. Explanation diagram showing an example of the installation position of an out-of-vehicle information detection unit and an imaging unit.

[0029] Hereinafter, embodiments of a light emitting device and a distance measuring device will be described with reference to the drawings. The following description will focus on the main components of the light emitting device and the distance measuring device, but the light emitting device and the distance measuring device may include components and functions that are not shown or described. The following description does not exclude components and functions that are not shown or described.

[0030] (First Embodiment) Fig. 1 is a circuit diagram of a light emitting device 1 according to a first embodiment. As shown in Fig. 1, the light emitting device 1 according to the first embodiment includes a plurality of light emitting elements 23 arranged in a two-dimensional array, and a plurality of transistors 24 electrically connected to these light emitting elements 23. These transistors 24 are, for example, N-type MOS transistors. Fig. 1 shows an example in which the light emitting device 1 according to the first embodiment includes 9 x 9 light emitting elements 23 and 9 x 9 transistors 24. Therefore, the light emitting device 1 shown in Fig. 1 includes a 9ch x 9ch light emitting element array. The number of channels in the light emitting element array is arbitrary.

[0031] 1 , the light-emitting device 1 according to the first embodiment further includes a first anode wiring 31, a second anode wiring 32, a third anode wiring 33, a plurality of first capacitors 34, a plurality of second capacitors 35, a plurality of third capacitors 36, a first selection circuit 37, a second selection circuit 38, a third selection circuit 39, a plurality of cathode wirings 41, and a plurality of gate wirings 42. The first to third anode wirings 31 to 33 are an example of the first terminal wiring of the present disclosure, and the cathode wiring 41 is an example of the second terminal wiring of the present disclosure. The first to third capacitors 34 to 36 are an example of the first to Nth capacitors of the present disclosure, and the first to third selection circuits 37 to 39 are an example of the first to Nth selection circuits of the present disclosure (N is an integer of 2 or more). FIG. 1 shows an example where N is 3.

[0032] The first terminal wirings include N first wirings 31a, 32a, and 33a (N is an integer of 2 or greater) extending in a first direction X, and N second wirings 31b, 32b, and 33b extending in a second direction Y intersecting the first direction X and electrically connected to the N first wirings 31a, 32a, and 33a, respectively. FIG. 1 shows an example where N=3. The first terminal wirings are electrically connected to first terminals of a plurality of light-emitting elements 23. In this specification, the first wirings 31a and the second wirings 31b connected to each other are referred to as first anode wirings 31, the second wirings 32a and 32b connected to each other are referred to as second anode wirings 32, and the third wirings 33a and 33b connected to each other are referred to as third anode wirings 33. In this specification, the first direction X may be referred to as the horizontal direction, and the second direction Y may be referred to as the vertical direction.

[0033] The light emitting device 1 according to the first embodiment includes M (M is an integer of 1 or more) sets of the first to third anode wirings 31 to 33. Figure 1 shows an example where M=5.

[0034] The five sets of first anode wirings 31 include a plurality of (e.g., five) first wirings 31a each extending in the first direction X (horizontal direction) and arranged along the second direction Y (vertical direction), and a plurality of (e.g., five) second wirings 31b each extending in the second direction Y (vertical direction) and arranged along the first direction X (horizontal direction). In this specification, the first wirings 31a may be referred to as first horizontal wirings 31a, and the second wirings 31b may be referred to as first vertical wirings 31b.

[0035] The five sets of second anode wirings 32 each include a plurality of (e.g., five) first wirings 32a each extending in the first direction X (horizontal direction) and arranged along the second direction Y (vertical direction), and a plurality of (e.g., five) second wirings 32b each extending in the second direction Y (vertical direction) and arranged along the first direction X (horizontal direction). In this specification, the first wirings 32a may be referred to as second horizontal wirings 32a, and the first wirings 32b may be referred to as second vertical wirings 32b.

[0036] The five sets of third anode wirings 33 each include a plurality of (e.g., five) first wirings 33a each extending in the first direction X (horizontal direction) and arranged along the second direction Y (vertical direction), and a plurality of (e.g., five) second wirings 33b each extending in the second direction Y (vertical direction) and arranged along the first direction X (horizontal direction). In this specification, the first wirings 33a may be referred to as third horizontal wirings 33a, and the first wirings 33b may be referred to as third vertical wirings 33b.

[0037] 1 shows an example in which the light-emitting device 1 according to the first embodiment includes five first horizontal wires 31a, five first vertical wires 31b, five second horizontal wires 32a, five second vertical wires 32b, five third horizontal wires 33a, and five third vertical wires 33b. Fig. 1 also shows an example in which M sets of N first wires and N second wires are provided. The number of light-emitting elements 23 shown in Fig. 1 is N(M-2) x N(M-2), where N and M are symbols.

[0038] The first to third anode wirings 31 to 33 may include Ma sets of first to Nth horizontal wirings and Mb sets of first to Nth vertical wirings (Ma and Mb are integers of 2 or greater that satisfy Ma≠Mb). In this case, the number of light-emitting elements 23 in the light-emitting device 1 is N(Ma-2)×N(Mb-2).

[0039] The first selection circuit 37 includes transistors 37a and 37b connected in series. Similarly, the second selection circuit 38 includes transistors 38a and 38b connected in series. Similarly, the third selection circuit 39 includes transistors 39a and 39b connected in series. The transistors 37a, 38a, and 39a are, for example, P-type MOS transistors. The transistors 37b, 38b, and 39b are, for example, N-type MOS transistors. The transistors 37a, 38a, and 39a are examples of first switches of the present disclosure. The transistors 37b, 38b, and 39b are examples of second switches of the present disclosure.

[0040] [First to third anode wirings 31 to 33] In FIG. 1, in order to distinguish the first to third anode wirings 31 to 33 from one another, the first anode wiring 31 is shown by a thick solid line, the second anode wiring 32 is shown by a thick dashed line, and the third anode wiring 33 is shown by a thin solid line.

[0041] The first anode wiring 31 has a structure in which a plurality of first horizontal wirings 31a and a plurality of first vertical wirings 31b are arranged in a mesh pattern. These first horizontal wirings 31a and first vertical wirings 31b are electrically connected to each other at the locations where the first horizontal wirings 31a and first vertical wirings 31b intersect. Similarly, the second anode wiring 32 includes a plurality of second horizontal wirings 32a and a plurality of second vertical wirings 32b that are electrically connected to each other, and the third anode wiring 33 includes a plurality of third horizontal wirings 33a and a plurality of third vertical wirings 33b that are electrically connected to each other. Meanwhile, the first to third anode wirings 31 to 33 are electrically insulated from each other.

[0042] The first to third horizontal wirings 31a to 33a extend in the first direction X (horizontal direction) and are adjacent to each other in the second direction Y (vertical direction). Although the first to third horizontal wirings 31a to 33a extend linearly in the first direction X in FIG. 1, they may extend in a curved manner in the first direction X. That is, the first to third horizontal wirings 31a to 33a may include bent portions.

[0043] On the other hand, the first to third vertical wirings 31b to 33b extend in the second direction Y and are adjacent to each other in the first direction X. Although the first to third vertical wirings 31b to 33b extend linearly in the second direction Y in FIG. 1, they may also extend in a curved manner in the second direction Y. That is, the first to third vertical wirings 31b to 33b may also include bent portions.

[0044] FIG. 1 shows five sets of first to third horizontal wirings (first wirings) 31a to 33a. In FIG. 1, the first, second, third, fourth, and fifth sets of first to third horizontal wirings 31a to 33a are arranged in order from top to bottom. In each set, the first horizontal wiring 31a, the second horizontal wiring 32a, and the third horizontal wiring 33a are arranged in order from top to bottom. The first set of first to third horizontal wirings 31a to 33a and the fifth set of first to third horizontal wirings 31a to 33a are arranged so as to sandwich 9 × 9 light-emitting elements 23 therebetween. Each of the second to fourth sets of first to third horizontal wirings 31a to 33a is arranged along one row (nine light-emitting elements) 23.

[0045] FIG. 1 further shows five sets of first to third vertical wirings (second wirings) 31b to 33b. In FIG. 1, the first, second, third, fourth, and fifth sets of first to third vertical wirings 31b to 33b are arranged in order from left to right. In each set, the first vertical wiring 31b, the second vertical wiring 32b, and the third vertical wiring 33b are arranged in order from left to right. The first set of first to third vertical wirings 31b to 33b and the fifth set of first to third vertical wirings 31b to 33b are arranged so as to sandwich 9 × 9 light-emitting elements 23 therebetween. Each of the second to fourth sets of first to third vertical wirings 31b to 33b is arranged along one column (nine light-emitting elements) 23.

[0046] The anode of each light-emitting element 23 is electrically connected to one of the first to third vertical wirings 31b to 33b. For example, the light-emitting element 23 in the leftmost column is electrically connected to the first vertical wiring 31b in the second set of first to third vertical wirings 31b to 33b. The light-emitting element 23 in the rightmost column is electrically connected to the third vertical wiring 33b in the fourth set of first to third vertical wirings 31b to 33b. The anode of each light-emitting element 23 may be electrically connected to one of the first to third horizontal wirings 31a to 33a instead of being electrically connected to one of the first to third vertical wirings 31b to 33b. The anode is an example of a first terminal in the present disclosure.

[0047] [Cathode wiring 41] Each cathode wiring 41 extends in the first direction X and is electrically connected to the cathodes of three light-emitting elements 23. Specifically, each cathode wiring 41 is electrically connected to one light-emitting element 23 electrically connected to the first vertical wiring 31b, one light-emitting element 23 electrically connected to the second vertical wiring 32b, and one light-emitting element 23 electrically connected to the third vertical wiring 33b. These three light-emitting elements 23 are adjacent to each other in the first direction X. FIG. 1 shows 27 cathode wirings 41 for 81 light-emitting elements 23. The cathode is an example of a second terminal of the present disclosure.

[0048] Each light-emitting element 23 is provided between a corresponding anode wiring, i.e., any one of the first to third anode wirings 31 to 33, and a corresponding cathode wiring, i.e., any one of the plurality of cathode wirings 41. Each light-emitting element 23 emits light when a current flows between the corresponding anode wiring and the corresponding cathode wiring.

[0049] [Gate Wiring 42] Each gate wiring 42 extends in the first direction X and is electrically connected to the gates of three transistors 24. The sources of these three transistors 24 are electrically connected to the ground wiring (GND), and the drains of these three transistors 24 are electrically connected to the same single cathode wiring 41. These three transistors 24 form one drive circuit E. FIG. 1 shows 27 gate wirings 42 for 81 transistors 24.

[0050] Each drive circuit E is electrically connected to the cathodes of three light-emitting elements 23 via one cathode wiring 41. Each drive circuit E (output stage) E is used to drive the light-emitting elements 23 to generate (output) light from the light-emitting elements 23. For example, to generate light from a certain light-emitting element 23, a predetermined signal is applied to the gate wiring 42 of the drive circuit E for that light-emitting element 23. This brings the source and drain of each transistor 24 in that drive circuit E into conduction, allowing current to flow through that light-emitting element 23. When current flows through that light-emitting element 23, light is generated from that light-emitting element 23. The light-emitting device 1 shown in FIG. 1 includes 27 drive circuits E for 81 light-emitting elements 23.

[0051] [First to Third Selection Circuits 37 to 39] The first to third selection circuits 37 to 39 are electrically connected to the first to third horizontal wirings 31a to 33a of the first to third anode wirings 31 to 33, respectively. The first selection circuit 37 is used to select the light-emitting element 23 electrically connected to the first anode wiring 31 as the light-emitting element 23 that generates light. The second selection circuit 38 is used to select the light-emitting element 23 electrically connected to the second anode wiring 32 as the light-emitting element 23 that generates light. The third selection circuit 39 is used to select the light-emitting element 23 electrically connected to the third anode wiring 33 as the light-emitting element 23 that generates light. The first to third selection circuits 37 to 39 may be electrically connected to the first to third vertical wirings 31b to 33b of the first to third anode wirings 31 to 33, respectively, instead of the first to third horizontal wirings 31a to 33a of the first to third anode wirings 31 to 33.

[0052] The first selection circuit 37 includes a transistor 37a having a source electrically connected to the power supply wiring (VDD) and a transistor 37b having a source electrically connected to the ground wiring. The drains of the transistors 37a and 37b are electrically connected to the first anode wiring 31. The first selection circuit 37 is electrically connected to each of the first capacitors 34 via the first anode wiring 31.

[0053] The transistor 37a is used to store charge in each first capacitor 34. The transistor 37b is used to discharge charge from each first capacitor 34. When a predetermined signal is applied to the gate of the transistor 37a, charge is stored in each first capacitor 34. When a predetermined signal is applied to the gate of the transistor 37b, charge is discharged from each first capacitor 34. Therefore, according to this embodiment, by selectively storing charge in the first capacitor 34 of the first to third capacitors 34 to 36 using the first selection circuit 37, it is possible to pass a current to each light-emitting element 23 electrically connected to the first anode wiring 31.

[0054] 1 , the second and third selection circuits 38, 39 have the same structure as the first selection circuit 37. Therefore, according to this embodiment, by storing charge in each second capacitor 35 by the second selection circuit 38, it is possible to pass a current to each light-emitting element 23 electrically connected to the second anode wiring 32. Furthermore, according to this embodiment, by storing charge in each third capacitor 36 by the third selection circuit 39, it is possible to pass a current to each light-emitting element 23 electrically connected to the third anode wiring 33.

[0055] [First to Third Capacitors 34 to 36] The first to third capacitors 34 to 36 are electrically connected to the first to third anode wirings 31 to 33, respectively. Each first capacitor 34 stores charge to be supplied to the light-emitting element 23 electrically connected to the first anode wiring 31. Each second capacitor 35 stores charge to be supplied to the light-emitting element 23 electrically connected to the second anode wiring 32. Each third capacitor 36 stores charge to be supplied to the light-emitting element 23 electrically connected to the third anode wiring 33. According to this embodiment, by supplying charge to each light-emitting element 23 from the first to third capacitors 34 to 36, a current can be passed through each light-emitting element 23. Each of the first to third capacitors 34 to 36 has one electrode electrically connected to one of the first to third anode wirings 31 to 33 and the other electrode electrically connected to a ground wiring.

[0056] The light-emitting device 1 shown in FIG. 1 includes a light-emitting element array including 9×9 light-emitting elements 23 arranged in a two-dimensional array. As shown in FIG. 1, the shape of this light-emitting element array is roughly square in plan view. The light-emitting device 1 shown in FIG. 1 includes four sets of first to third capacitors 34-36 near the four sides of the square. Specifically, the light-emitting device 1 shown in FIG. 1 includes a first set of first to third capacitors 34-36 near the top side of the square, a second set of first to third capacitors 34-36 near the right side of the square, a third set of first to third capacitors 34-36 near the bottom side of the square, and a fourth set of first to third capacitors 34-36 near the left side of the square. These first to third capacitors 34-36 are examples of K sets of first to Nth capacitors of the present disclosure (K is an integer greater than or equal to 2). FIG. 1 shows an example where K is 4.

[0057] The first to third capacitors 34 to 36 of the first and third sets are electrically connected to the first to third horizontal wirings 31 a to 33 a of the first to third anode wirings 31 to 33, respectively. On the other hand, the first to third capacitors 34 to 36 of the second and fourth sets are electrically connected to the first to third vertical wirings 31 b to 33 b of the first to third anode wirings 31 to 33, respectively. As a result, the first to third capacitors 34 to 36 shown in FIG. 1 are electrically connected to the first to third anode wirings 31 to 33, respectively.

[0058] In each set, the first to third capacitors 34 to 36 are arranged in clockwise order. For example, the first capacitor 34, the second capacitor 35, and the third capacitor 36 of the first set are respectively arranged on the left, center, and right sides near the top edge of the square. The first capacitor 34, the second capacitor 35, and the third capacitor 36 of the second set are respectively arranged on the upper, center, and lower sides near the right edge of the square. As a result, the four sets of first to third capacitors 34 to 36 shown in FIG. 1 are arranged symmetrically with respect to the center of the square. The center of the square is approximately located at the position of the light-emitting element 23 in the fifth row and fifth column of the 9×9 light-emitting elements 23. In FIG. 1, the four sets of first to third capacitors 34 to 36 are arranged in four-fold rotational symmetry (90-degree rotational symmetry).

[0059] According to this embodiment, it is possible to set the average distance between each light-emitting element 23 and the corresponding four capacitors to a value close to the average distance between another light-emitting element 23 and the corresponding four capacitors.

[0060] For example, the light-emitting element 23 at the upper left is close to the first capacitor 34 above but far from the first capacitor 34 below. On the other hand, the light-emitting element 23 at the lower right is close to the third capacitor 36 on the right but far from the third capacitor 36 on the left. Therefore, the average distance between the light-emitting element 23 at the upper left and the four first capacitors 34 is close to the average distance between the light-emitting element 23 at the lower right and the four third capacitors 36. This is also true for the other 79 light-emitting elements 23. This makes it possible to reduce the difference in impedance between the wiring of different light-emitting elements 23 with respect to the anode wiring between each light-emitting element 23 and the corresponding four capacitors.

[0061] The light emitting device 1 of this embodiment may include the first to third capacitors 34 to 36 only near one, two, or three of the four sides of the square. However, in this case, it is desirable that the first to third capacitors 34 to 36 are also arranged symmetrically or nearly symmetrically with respect to the center of the square. Therefore, it is desirable that the light emitting device 1 of this embodiment include the first to third capacitors 34 to 36 on two or more of the four sides of the square. For example, by arranging two sets of the first to third capacitors 34 to 36 near the top and bottom sides of the square, it is possible to achieve an arrangement with two-fold rotational symmetry (180-degree rotational symmetry).

[0062] Fig. 2 is a circuit diagram showing the connection relationship between the selection circuits 37, 38, the light-emitting elements 23, and the drive circuit E, and Fig. 3 is a timing chart corresponding to the circuit diagram of Fig. 2. Fig. 2 shows two selection circuits 37, 38 arranged in the second direction Y (vertical direction) and a plurality of light-emitting elements 23 connected to each of two drive circuits E arranged in the first direction X (horizontal direction). Each of the two drive circuits E has a transistor 24. Hereinafter, the two transistors 24 in Fig. 2 will be referred to as a first transistor 24a and a second transistor 24b.

[0063] As shown in FIG. 2 , a capacitor 34 is connected to the selection circuit 37, and a capacitor 35 is connected to the selection circuit 38. As shown in FIG. 1 , multiple capacitors 34 may be connected to the selection circuit 37, and multiple capacitors 35 may be connected to the selection circuit 38. However, for simplicity, FIG. 2 shows an example in which only one capacitor 34, 35 is connected to each of the selection circuits 37, 38. The selection circuit 37 controls the charging and discharging of the capacitor 34. The charge stored in the capacitor 34 is used to cause all light-emitting elements 23 in the row connected to the capacitor 34 to emit light. More specifically, the discharge current of the capacitor 34 is supplied to the anodes of all light-emitting elements 23 in the row connected to the capacitor 34. Similarly, the charge stored in the capacitor 35 is used to cause all light-emitting elements 23 in the row connected to the capacitor 35 to emit light.

[0064] A drive circuit E is connected to the cathode of each light-emitting element 23. A plurality of drive circuits E are arranged along the first direction X (horizontal direction), and each drive circuit E drives the cathode of a corresponding light-emitting element 23. More specifically, when the transistor 24 of each drive circuit E is turned on, the cathode voltage of the light-emitting element 23 connected to the drain of this transistor 24 drops to a reference voltage (e.g., ground), and a discharge current of the capacitor 34 (35) flows between the anode and cathode of the light-emitting element 23 and between the drain and source of the transistor 24, causing the light-emitting element 23 to emit light.

[0065] As shown in Figure 1, the light-emitting device 1 of the first embodiment has a plurality of light-emitting elements 23 arranged two-dimensionally, and selection circuits 37 to 39 and a plurality of drive circuits E are used to select the light-emitting elements 23 of a specific channel and cause them to emit light.

[0066] Between times t1 and t2 in FIG. 3, when the gate voltage of the transistor (first switch) 37a in the selection circuit 37 connected to the anode of the light-emitting element 23 of a specific channel goes low, the transistor (first switch) 37a turns on, charging the capacitor 34 connected to the selection circuit 37. This causes the anode voltage of each light-emitting element 23 in the row connected to the capacitor 34 to rise linearly. Between times t3 and t4, when the gate voltage of the transistor 24a in the drive circuit E connected to the cathode of the light-emitting element 23 of a specific channel temporarily goes high, the transistor 24a turns on, discharging the charge in the capacitor 34 and causing an instantaneous current to flow between the anode and cathode of the light-emitting element 23 of the specific channel and between the drain and source of the transistor 24a. This instantaneous current causes the light-emitting element 23 of the specific channel to emit light in a pulsed manner. The discharge of the capacitor 34 causes the anode voltage of the light-emitting element 23 of the specific channel to drop sharply.

[0067] On the other hand, between times t1 and t4, the gate voltage of the transistor 38a in the selection circuit 38 remains high, so the capacitor 35 connected to the selection circuit 38 is not charged. Also, the gate voltage of the transistor 24 in the drive circuit E connected to the cathode of the light-emitting element 23 connected to the capacitor 35 remains low, so the transistor 24 remains off. Therefore, the light-emitting element 23 connected to the capacitor 35 remains unlit.

[0068] In the selection circuit 37 to which the anode of the light-emitting element 23 to be emitted is connected, a transistor (first switch) 37a is set on and a transistor (second switch) 37b is set off. On the other hand, in the selection circuit 38 to which the anode of the light-emitting element 23 not to be emitted is connected, a transistor (first switch) 38a is set off and a transistor (second switch) 38b is set on. As a result, a discharge current from the capacitor 35 to which the anode of the light-emitting element 23 not to be emitted flows through the transistor (second switch) 38b to the ground node, and the capacitor 35 is discharged.

[0069] 4 is a diagram showing a state in which an abnormality has occurred in which the anode and cathode of a light-emitting element 23 of a specific channel are short-circuited. More specifically, FIG. 4 shows an example in which the light-emitting element 23a connected to the selection circuit 37 is the light-emitting element, and the non-light-emitting element 23z, whose cathode is connected to this light-emitting element 23a, is the non-light-emitting element, and the anode and cathode are short-circuited. The light-emitting element 23a emits light due to the discharge current of the capacitor 34 connected to the selection circuit 37. The anode of the light-emitting element 23z is connected to the selection circuit 38 and the capacitor 35.

[0070] The plurality of light-emitting elements 23 emit light when a higher voltage is applied to their anodes than to their cathodes. However, if a voltage higher than that of the anodes is applied to the cathodes for some reason, an abnormality in which the anodes and cathodes are short-circuited may occur. In this case, the transistor (first switch) 37a of the selection circuit 37, to which the anode of the light-emitting element 23a to be emitted is connected, is set to on and the transistor (second switch) 37b is set to off, while the transistor (first switch) 38a of the selection circuit 38, to which the anodes of the light-emitting elements 23 not to be emitted are connected, is set to off and the transistor (second switch) 38b is set to on. Therefore, a portion of the current flowing from the power supply voltage node of the selection circuit 37 to the transistor (first switch) 37a flows to the capacitor 34 to charge the capacitor 34, and the remaining current flows from the anode to the cathode of the light-emitting element 23a to be emitted, then flows from the cathode to the anode of the light-emitting element 23z that has experienced the short-circuit abnormality, and then flows to the transistor (second switch) 38b of the selection circuit 38. As a result, the current passing from the power supply voltage node of the selection circuit 37 through the transistor (first switch) 37a flows through the transistor (second switch) 38b of the selection circuit 38 to the ground node, causing a large amount of through current to flow from the power supply voltage node of the selection circuit 37 to the ground node of the selection circuit 38, which may destroy the circuit elements that make up the selection circuits 37 and 38.

[0071] Fig. 5 is a circuit diagram showing the main parts of the light-emitting device 1 according to the first embodiment, and Fig. 6 is a timing chart corresponding to the circuit diagram of Fig. 5. As with Fig. 4, the light-emitting device 1 according to the first embodiment shows an example in which the light-emitting element 23a connected to the selection circuit 37 is the light-emitting element, and the non-light-emitting element 23z, the cathode of which is connected to the light-emitting element 23a, has an abnormality in which the anode and cathode are short-circuited. The light-emitting device 1 according to the first embodiment is characterized in that the selection circuit 38 connected to the anode of the non-light-emitting element 23z switches and controls the transistor (second switch) 38b when an abnormality is detected in the non-light-emitting element 23z.

[0072] More specifically, the first embodiment differs from the first embodiment in that, as shown in FIG. 5 , the transistor (second switch) 38b of the selection circuit 38 connected to the anode of the short-circuited light-emitting element 23z is turned off. A portion of the current flowing from the power supply voltage node of the selection circuit 37 to the transistor (first switch) 37a flows to the capacitor 34 to charge the capacitor 34, while the remaining current flows from the anode to the cathode of the light-emitting element 23a and then from the cathode to the anode of the short-circuited light-emitting element 23z. Because the transistor (second switch) 38b of the selection circuit 38 is off, this current does not flow through the selection circuit 38 but instead flows to the capacitor 35 to charge the capacitor 35. This prevents a through current from flowing through the selection circuits 37 and 38, even if a short-circuited light-emitting element 23z is present, thereby preventing damage to the circuit elements.

[0073] The occurrence of an abnormality in which the anode and cathode of a non-target light-emitting element 23z are short-circuited can be detected by detecting the current flowing through the output wiring of the selection circuits 37 to 39. Although not shown in FIG. 4 , for example, an abnormality detection circuit is provided that detects the current flowing through the output wiring (anode wiring 31, 32) of each selection circuit 37 to 39 to detect an abnormality in the light-emitting element 23. When an abnormality is detected by the abnormality detection circuit, the selection circuit (e.g., 38) to which the anode of the abnormal light-emitting element 23z is connected switches off a transistor (second switch) 38b. This charges the capacitor 35 with the current flowing between the cathode and anode of the abnormal light-emitting element 23z, preventing a through current from flowing through the selection circuits 37 and 38.

[0074] In this way, in the first embodiment, the selection circuit 38 connected to the anode of the light-emitting element 23z that is not a target for light emission can control switching of the transistor (second switch) 38b when an abnormality is detected in the light-emitting element 23z that is not a target for light emission, so that the current flowing between the cathode and anode of the abnormal light-emitting element 23z can be used to charge the capacitor 35, and no through current flows through the selection circuits 37 and 38. Charging the capacitor 35 allows it to be used to emit light from the light-emitting element 23 that is not a target for light emission, as will be described later.

[0075] Second Embodiment FIG. 6 is a circuit diagram for explaining the problem with the light emitting device 1 according to the first embodiment, and FIG. 7 is a timing chart corresponding to the circuit diagram of FIG.

[0076] In the light-emitting device 1 according to the first embodiment, as shown in Fig. 5, the capacitor 35 connected to the anode of the light-emitting element 23z that has short-circuited is charged by the discharge current of the capacitor 34 connected to the anode of the light-emitting element 23a that is to emit light. Therefore, as shown in Fig. 6, when a specific light-emitting element 23b other than the light-emitting element 23z that has shorted and that is in a row connected to the capacitor 34 is made to emit light, the light-emitting element 23c that is not to emit light and that is in a row connected to the capacitor 35 also emits light.

[0077] 7, during the period from time t1 to time t2, transistor (first switch) 37a of selection circuit 37 is turned on. As a result, capacitor 34 is charged from time t1 to time t2, and the anode voltage of light-emitting element 23b, which is the target of light emission, gradually increases. When transistor 24b of drive circuit E, which is connected to the cathode of light-emitting element 23b, is turned on at time t2, the discharge current of capacitor 34 flows through transistor 24b via the anode-cathode of light-emitting element 23b, causing light-emitting element 23c to emit light.

[0078] The transistor 24b is also connected to the cathode of the light-emitting element 23c that is not to emit light, and the discharge current of the capacitor 35 flows between the anode and cathode of the light-emitting element 23c to the transistor 24b, causing the light-emitting element 23c to emit light.

[0079] Fig. 8 is a circuit diagram of a main part of the light emitting device 1 according to the second embodiment, and Fig. 9 is a timing chart corresponding to the circuit diagram of Fig. 8. The light emitting device 1 according to the second embodiment includes a bypass path 30B that diverts the discharge current of the capacitor 35 without flowing it to the light emitting element 23c, and a third switch 30 that switches whether or not the discharge current of the capacitor 35 is to flow to the bypass path 30B.

[0080] The third switch 30 is configured using, for example, an NMOS transistor. A third switch 30 is provided for each of the capacitors 34 and 35. The drain of the transistor configuring the third switch 30 is connected to one end of the capacitors 34 and 35, and the source is connected to a reference voltage (for example, ground) node.

[0081] The third switch 30 is disposed near the capacitors 34 and 35. By providing the bypass path 30B and the third switch 30, the discharge current of the capacitor 35 connected to the anode of the non-target light-emitting element 23c can be passed through the bypass path 30B via the third switch 30 without flowing to the non-target light-emitting element 23c. As a result, as shown in FIG. 6, when the target light-emitting element 23a is to be made to emit light, if the capacitor 35 connected to the non-target light-emitting element 23z is charged due to a short circuit abnormality in the non-target light-emitting element 23z, the discharge current of the capacitor 35 can be passed through the bypass path 30B without flowing to the non-target light-emitting element 23c. Therefore, as shown in FIG. 8, only the target light-emitting element 23b can be made to emit light.

[0082] Because the third switch 30 is disposed near the capacitors 34 and 35, for example, the wiring length from one end of the capacitor 34 (35) to the third switch 30 is shorter than the wiring length from one end of the capacitor 34 (35) to the anode of the light-emitting element 23. Parasitic impedance including parasitic capacitance and parasitic inductance is added to the wiring, and the longer the wiring length, the larger the parasitic impedance. In Figure 8, the parasitic impedance from one end of the capacitor 34 (35) to the third switch 30 is Z1, and the parasitic impedance from one end of the capacitor 34 (35) to the anode of the light-emitting element 23 is Z2.

[0083] Since current flows more easily through wiring with smaller impedance, when the third switch 30 is turned on, the discharge current of the capacitor 34 (35) does not flow through the light emitting element 23 but flows through the bypass path 30B.

[0084] In Figure 9, the operation from time t1 to t2 is the same as in Figure 7. At time t3, when transistor 24b of drive circuit E connected to the cathode of light-emitting element 23b to be illuminated is turned on, the discharge current of capacitor 34 connected to the anode of light-emitting element 23b to be illuminated flows through the anode-cathode of light-emitting element 23b to transistor 24b, causing light-emitting element 23b to emit light. Also, at time t3, third switch 30 connected to the anode of light-emitting element 23c not to be illuminated is turned on. As a result, the discharge current of capacitor 35 connected to the anode of light-emitting element 23c not to be illuminated flows through third switch 30 on bypass path 30B to the reference voltage (e.g., ground) node without flowing to the anode of light-emitting element 23c not to be illuminated. Therefore, light-emitting element 23c not to be illuminated does not emit light.

[0085] In this way, the third switch 30 connected to the light-emitting element 23 that is not to be illuminated is turned on in accordance with the timing at which the light-emitting element that is to be illuminated is driven, and a discharge current flows from the capacitor 35 connected to the light-emitting element 23 that is not to be illuminated to the reference voltage (ground) node.

[0086] More specifically, when an abnormality occurs in which the anode and cathode of the non-target light-emitting element 23 are short-circuited, the third switch 30 connected to the non-target light-emitting element 23 is turned on, and the discharge current of the capacitor 35 connected to the non-target light-emitting element 23 is not passed to the non-target light-emitting element 23 but is passed to the reference voltage node.

[0087] FIG. 10 is a diagram showing the path through which the discharge current of the capacitor flows when the third switch 30 is off. When the third switch 30 is off, the parasitic impedance of the bypass path 30B becomes infinitely large, so the discharge current of the capacitor 35 connected to the anode of the non-target light-emitting element 23c flows through the anode-cathode of the non-target light-emitting element 23c to the transistor 24b of the drive circuit E. As a result, as shown in FIG. 10, both the target light-emitting element 23b and the non-target light-emitting element 23c emit light. By turning on the third switch 30 connected to the selection circuit 38, the light emission of the non-target light-emitting element 23c can be stopped, as shown in FIG. 9.

[0088] As described above, in the second embodiment, a bypass path 30B is provided near the capacitors 34, 35 that supply discharge current to the light-emitting element 23, and the third switch 30 is connected to the bypass path 30B. When the light-emitting element 23b to be emitted is to be made to emit light, the third switch 30 on the bypass path 30B that is connected to the anode of the light-emitting element 23c that is not to be emitted is turned on. This prevents the discharge current from the capacitor 35 from flowing to the light-emitting element 23c that is not to be emitted, and allows only the light-emitting element 23b to be emitted to be made to emit light.

[0089] 6, if an abnormality occurs in some of the light-emitting elements 23z, in which the anode and cathode are short-circuited, not only the light-emitting elements 23b that are the target light-emitting elements but also the light-emitting elements 23c that are not the target light-emitting elements may emit light, and the light emission intensity of the light-emitting device 1 may exceed the safety standard for laser light. Therefore, in the third embodiment, when an abnormality is detected in the light-emitting element 23z, the light emission intensity of the light-emitting elements 23b that are the target light-emitting elements is controlled.

[0090] 11 is a circuit diagram of a light-emitting device 1 according to a third embodiment. As shown in FIG. 11, the light-emitting device 1 according to the third embodiment includes first to third voltage detection circuits 71 to 73 in addition to the configuration of the light-emitting device 1 shown in FIG. 1. The first voltage detection circuit 71 is electrically connected to the first horizontal wiring 31a of the first anode wiring 31 and the gate of the transistor 37a. The second voltage detection circuit 72 is electrically connected to the second horizontal wiring 32a of the second anode wiring 32 and the gate of the transistor 38a. The third voltage detection circuit 73 is electrically connected to the third horizontal wiring 33a of the third anode wiring 33 and the gate of the transistor 39a.

[0091] The first voltage detection circuit 71 detects the voltage of the first anode wiring 31 via the first horizontal wiring 31a of the first anode wiring 31. This voltage indicates the amount of charge stored in the four first capacitors 34. Therefore, the first voltage detection circuit 71 controls the gate voltage of the transistor 37a in the selection circuit 37 based on the voltage detected from the first anode wiring 31. For example, if the detected voltage is lower than a predetermined voltage, the first voltage detection circuit 71 turns on the transistor 37a to start charge storage. On the other hand, if the detected voltage is higher than the predetermined voltage, the first voltage detection circuit 71 turns off the transistor 37a to end charge storage. According to this modification, the light emission luminance of the light-emitting device 1 can be changed by changing the value of this predetermined voltage. The value of this predetermined voltage is adjusted, for example, by the first to third voltage detection circuits 71 to 73 shown in FIG. 1. In this way, the first to third voltage detection circuits 71 to 73 function as a charge adjustment unit that adjusts the amount of charge stored in at least one of the capacitors 34 to 36 connected to the light-emitting element to be illuminated when an abnormality is detected in at least one light-emitting element 23. For example, when an abnormality in at least one light-emitting element 23 is detected, the first to third voltage detection circuits 71 to 73 make the amount of charge charged in the capacitor connected to the light-emitting element in which the abnormality was detected and the capacitor connected to the light-emitting element 23 to be illuminated smaller than the amount of charge charged before the abnormality was detected.

[0092] Similarly, the second voltage detection circuit 72 detects the voltage of the second anode wiring 32 and controls the gate voltage of the transistor 38 a based on the detected voltage. The third voltage detection circuit 73 detects the voltage of the third anode wiring 33 and controls the gate voltage of the transistor 39 a based on the detected voltage.

[0093] The first to third voltage detection circuits 71 to 73 detect the voltages of the first to third anode wirings 31 to 33, thereby detecting abnormalities in the plurality of light-emitting elements 23 connected to the first to third anode wirings 31 to 33. For example, in a light-emitting element 23z in which an abnormality has occurred in which the anode and cathode are short-circuited, the anode voltage does not reach the originally intended voltage level, and therefore, by detecting the voltages of the first to third anode wirings 31 to 33, it is possible to detect the short-circuit abnormality.

[0094] Each of the first to third voltage detection circuits 71 to 73 functions as an abnormality detection unit that detects an abnormality in at least one light-emitting element 23. Each of the first to third voltage detection circuits 71 to 73 may output an error signal (abnormality detection signal) if it determines an abnormality based on the detected voltage. The error signals output from the first to third voltage detection circuits 71 to 73 are sent to, for example, a control unit of the distance measuring device (not shown in FIG. 11 ). Based on the error signals output from the first to third voltage detection circuits 71 to 73, the control unit may, for example, instruct the abnormal light-emitting element 23 to stop emitting light or instruct the light-receiving element 18 corresponding to the abnormal light-emitting element 23 to stop receiving light. This makes it possible, when some light-emitting elements are abnormal, to stop emitting light from only the abnormal light-emitting element and stop receiving light from only the corresponding light-receiving element 18. This allows distance measurement processing to continue using normal light-emitting elements and normal light-receiving elements 18, improving the yield of the distance measuring device.

[0095] In this way, the first to third voltage detection circuits 71 to 73 function as a charge adjustment unit that adjusts the amount of charge to be charged to at least one of the capacitors 34 to 36 connected to the light-emitting element 23 to be illuminated when an abnormality is detected in at least one light-emitting element 23. When an abnormality in at least one light-emitting element 23 is detected, the charge adjustment unit reduces the amount of charge charged to the capacitor connected to the light-emitting element in which the abnormality was detected and the capacitor connected to the light-emitting element 23 to be illuminated to be smaller than the amount of charge charged before the abnormality was detected.

[0096] The selection circuits 37 to 39 control the currents flowing through the first to third anode wirings 31 to 33 based on the voltages of the first to third anode wirings 31 to 33 detected by the first to third voltage detection circuits 71 to 73 .

[0097] In the following description, it is assumed that when a charging current from capacitor 34 flows through light-emitting element 23a, which is the target for light emission and has its anode connected to selection circuit 37, the current passes between the cathode and anode of light-emitting element 23z that has experienced a short circuit and charges capacitor 35. Thereafter, when a specific light-emitting element 23b, whose anode is connected to selection circuit 37, is the target for light emission, a discharging current from capacitor 35 flows to the anode of light-emitting element 23c, whose cathode is connected to light-emitting element 23b and whose anode is connected to selection circuit 38.

[0098] 12 is a timing diagram corresponding to the circuit diagram of FIG. 11. At time t1, for example, the first voltage detection circuit 71 detects an abnormality and sets the error signal to a high level. During the period from time t2 to t3, the transistor (first switch) 37a of the selection circuit 37 connected to the anode of the light-emitting element 23b to be illuminated is turned on. By making the period from time t2 to t3 shorter than the normal state in which no abnormality is detected, the current flowing from the power supply voltage VDD node of the selection circuit 37 to the capacitor 34 via the transistor (first switch) 37a can be suppressed, and the amount of charge stored in the capacitor 34 can also be suppressed.

[0099] Furthermore, between times t2 and t3, the transistor (first switch) 38a of the selection circuit 38 connected to the anode of the light-emitting element 23c that is not the target for light emission is also turned on. Because the period between times t2 and t3 is short, the amount of charge stored in the capacitor 35 is also suppressed.

[0100] Thereafter, when transistor 24b of drive circuit E connected to the cathode of light-emitting element 23b to be illuminated during the period from time t4 to t5 is turned on, a current corresponding to the amount of charge stored in capacitor 34 flows to light-emitting element 23b, causing light-emitting element 23b to emit light at a brightness corresponding to the amount of current. Similarly, a discharge current from capacitor 35 flows to light-emitting element 23c, causing light-emitting element 23c to emit light at a brightness corresponding to the amount of current.

[0101] Since the amount of charge stored in the capacitors 34 and 35 is smaller than normal, the light emission intensity of the light emitting elements 23b and 23c is weaker than normal, and the light emission brightness of the light emitting elements 23b and 23c can be suppressed.

[0102] FIG. 13 is a timing diagram corresponding to the circuit diagram of FIG. 11 when the first to third voltage detection circuits 71 to 73 do not control the currents output from the selection circuits 37 to 39. If the selection circuits 37 to 39 do not control the currents output from the selection circuits 37 to 39 despite a short circuit occurring in some of the light-emitting elements 23, not only the light-emitting element 23b that is the target light-emitting element, but also the light-emitting element 23c, which is connected to the capacitor 35 and has been charged due to the short circuit, will emit light. In FIG. 13, the period from time t2 to t3 is longer than the period from time t2 to t3 in FIG. 12. Therefore, in FIG. 13, the amount of charge stored in the capacitors 34 and 35 is greater than in FIG. 12, and the light-emitting elements 23b and 23c emit light at a brightness higher than in FIG. 12. This may result in light emission at a brightness that exceeds the safety standards for laser light.

[0103] Fig. 14 is a diagram in which the signal waveforms of Fig. 12 and Fig. 13 are superimposed. As shown in the figure, by providing first to third voltage detection circuits 71 to 73, it is possible to adjust the charging period of capacitors 34 and 35. For example, by shortening the charging period, it is possible to keep the light emission brightness of light-emitting elements 23b and 23c low.

[0104] As described above, in the third embodiment, the first to third voltage detection circuits 71 to 73 that detect the voltages of the first to third anode wirings 31 to 33 are provided, so that it is possible to easily detect that an abnormality has occurred in some of the light-emitting elements 23. When the first to third voltage detection circuits 71 to 73 detect that an abnormality has occurred in some of the light-emitting elements 23, they control the currents output from the selection circuits 37 to 39 to limit the charging currents to the capacitors 34 to 36, so that the light emission brightness of the light-emitting elements 23 can be kept low. This makes it possible to prevent a problem in which the light-emitting elements 23 emit light at such a high brightness that it exceeds the safety standards for laser light due to an abnormality in some of the light-emitting elements 23.

[0105] (Fourth embodiment) The light-emitting device 1 according to the fourth embodiment prevents multiple light-emitting elements 23 located within the range of the human eye from emitting light simultaneously when some of the light-emitting elements 23 malfunction.

[0106] Fig. 15 is a circuit diagram of the light-emitting device 1 according to the fourth embodiment. Fig. 15 shows an example in which one of the plurality of light-emitting elements 23 connected to the row connected to the selection circuit 37 has a short circuit. If a current is passed through another light-emitting element 23a whose cathode is connected to the light-emitting element 23z that has the short circuit, the desired light emission may not be achieved. Therefore, light-emitting elements 23b and 23c in other locations whose cathodes are not connected to the light-emitting element 23z that has the short circuit are caused to emit light.

[0107] 15 shows an example in which a charge is stored in the capacitor 35 connected to the anode of the light-emitting element 23z that has experienced a short circuit. In the example of FIG. 15, two light-emitting elements 23b and 23c located in light-emitting locations that do not simultaneously strike the human eye are selected as light-emitting elements. In this case, a transistor (first switch) 37a of a selection circuit 37 connected to the anodes of the light-emitting elements 23b and 23c that are the target elements for light emission is turned on to charge the capacitor 34. Then, when both transistors 24b and 24c of the two drive circuits E connected to the cathodes of the light-emitting elements 23b and 23c that are the target elements for light emission are turned on, a current flows from the capacitor 35 connected to the anodes of the non-light-emitting elements 23d and 23e, the cathodes of which are connected to the transistors 24b and 24c, to the non-light-emitting elements 23d and 23e, causing them to emit light.

[0108] 15, a total of four light-emitting elements 23b, 23c, 23d, and 23e emit light. The light-emitting elements 23b and 23d are located within the range that would be seen by the human pupil, and the light-emitting elements 23c and 23e are also located within the range that would be seen by the human pupil. On the other hand, the light-emitting group of the light-emitting elements 23b and 23d and the light-emitting group of the light-emitting elements 23c and 23e are both located outside the range that would be seen by the human pupil. Since all of the light-emitting groups have light emission intensities that do not exceed the safety standards for laser light, safety is improved.

[0109] Fig. 16A is a diagram schematically showing the light-emitting positions and the light-receiving positions of a light-receiving device (not shown) when all light-emitting elements 23 are performing normal light-emitting operations. Fig. 16B is a diagram schematically showing the light-emitting positions and the light-receiving positions (not shown) when some of the light-emitting elements 23 have a short circuit abnormality. The light-emitting device 1 and the light-receiving device are built into, for example, a distance measuring device, and the light-receiving device receives light emitted by the light-emitting device 1 and reflected by a subject. It is assumed that there is a one-to-one correspondence between the light-emitting position of the light-emitting device 1 and the light-receiving position of the light-receiving element.

[0110] When all the light-emitting elements 23 are operating normally, only the light-emitting elements 23 in the intended light-emitting positions can be made to emit light, and the light-receiving elements receive reflected light at light-receiving positions corresponding to the light-emitting positions of the light-emitting elements 23 in the intended light-emitting positions, as shown in Figure 16A. On the other hand, when some of the light-emitting elements 23 are short-circuited, the light-emitting elements 23 in two locations that do not enter the human eye are made to emit light, thereby weakening the light emission intensity. Furthermore, because the capacitors 35 connected to the anodes of the light-emitting elements 23 that are not intended to emit light are charged, a total of four light-emitting elements 23 emit light, as shown in Figure 16B.

[0111] When some of the light-emitting elements 23z have a short circuit, the light-receiving device receives reflected light from the subject using two light-receiving groups corresponding to the two light-emitting groups, as shown in FIG. 16B . The distance measuring device measures the distance to the subject based on the timing of light reception by the two light-receiving groups. In other words, the light-receiving device can measure the distance to the subject by effectively utilizing the light-receiving results of the two light-receiving groups.

[0112] In this way, in the fourth embodiment, if some of the light-emitting elements 23 suffer a short circuit, there is a risk that the light-emitting elements 23 that are not the target light-emitting elements may also emit light in addition to the target light-emitting elements 23, so the light-emitting elements 23 at other light-emitting locations that do not enter the human eye are also made to emit light. As a result, a total of four light-emitting elements 23 emit light, but because the discharge current of the same capacitor is passed through the multiple light-emitting elements 23 to emit light, the light emission brightness can be weakened and can be made to emit light at a brightness that does not exceed the safety standards for laser light.

[0113] (Fifth embodiment) The light-emitting device 1 according to the fifth embodiment is characterized in that, when some of the light-emitting elements 23 suffer a short circuit abnormality, the discharge current of the capacitor is passed not only to the light-emitting element 23 that is the target of light emission but also to the non-light-emitting portion 50.

[0114] 17 is a circuit diagram of a light emitting device 1 according to the fifth embodiment. The light emitting device 1 according to the fifth embodiment includes a non-light emitting section 50 in addition to a plurality of light emitting elements 23. The non-light emitting section 50 according to the fifth embodiment includes a plurality of non-light emitting regions 50a and a drive circuit E that drives a plurality of dummy light emitting elements 23D.

[0115] The non-light-emitting region 50a is, for example, a non-light-emitting dummy light-emitting element 23D. The dummy light-emitting element 23D is provided for each selection circuit. Therefore, the discharge current of the capacitor connected to each selection circuit flows through the multiple light-emitting elements 23 in the same row and also flows through the dummy light-emitting element 23D in the same row.

[0116] The dummy light-emitting element 23D has an element structure similar to that of the light-emitting element 23, but is structured not to emit light. The specific element structure of the dummy light-emitting element 23D will be described later, but for example, a shielding member that shields the light-emitting surface of the light-emitting element 23 is provided.

[0117] 17 shows an example in which one of the light-emitting elements 23 connected to the selection circuit 37 has a short circuit. In this case, when an attempt is made to make the light-emitting element 23a, whose cathode is connected to that of the light-emitting element 23z, emit light, part of the discharge current of the capacitor 34 passes from the anode to the cathode of the light-emitting element 23a, and then passes from the cathode to the anode of the light-emitting element 23z, thereby charging the capacitor 35.

[0118] In this embodiment, the discharge current of the capacitor 34 is passed to the light-emitting element 23b and the dummy light-emitting element 23D of the non-light-emitting unit 50, which are connected to a drive circuit E different from the drive circuit E to which the cathode of the light-emitting element 23z that has experienced a short circuit is connected. This distributes the discharge current of the capacitor 34, thereby weakening the luminous intensity of the light-emitting element 23a. Furthermore, the discharge current of the capacitor 35 is also passed to the light-emitting element 23b and the dummy light-emitting element 23D, which is different from the light-emitting element 23b. This distributes the discharge current of the capacitor 35, thereby weakening the luminous intensity of the light-emitting element 23b.

[0119] In this way, in the fifth embodiment, a non-light-emitting region 50a such as a dummy light-emitting element 23D is provided for each of the selection circuits 37 to 39, so that when some of the light-emitting elements 23 suffer a short circuit abnormality, the discharge current of the capacitor 34 (35) can be passed not only to the light-emitting element 23 to be emitted, but also to the dummy light-emitting element 23D, thereby weakening the light-emitting intensity of the light-emitting element 23 to be emitted.

[0120] Sixth Embodiment A light emitting device 1 according to a sixth embodiment is provided with a non-light emitting portion 50 having a different configuration from that of the fifth embodiment.

[0121] FIG. 18 is a circuit diagram of a light-emitting device 1 according to a sixth embodiment. The light-emitting device 1 according to the sixth embodiment includes a non-light-emitting section 50 having a different configuration from that of the fifth embodiment. The non-light-emitting section 50 according to the sixth embodiment includes a non-light-emitting region 50a shared by all selection circuits and a drive circuit E that drives the non-light-emitting region 50a. Only one non-light-emitting region 50a may be provided, or multiple non-light-emitting regions 50a may be provided. When multiple non-light-emitting regions 50a are provided, the multiple non-light-emitting regions 50a are driven by a single drive circuit E, and each non-light-emitting region 50a can be used by any of the selection circuits. The non-light-emitting region 50a is, for example, a dummy light-emitting element with a non-light-emitting structure, as in the fifth embodiment.

[0122] FIG. 18 shows an example in which one light-emitting element 23 connected to the selection circuit 37 has a short circuit. In this embodiment, the discharge current of the capacitor 34 is passed to the light-emitting element 23b and the dummy light-emitting element 23D of the non-light-emitting unit 50, which are connected to a drive circuit E different from the drive circuit E to which the cathode of the light-emitting element 23z that has a short circuit is connected. This distributes the discharge current of the capacitor 34, thereby weakening the luminous intensity of the light-emitting element 23b that is the target for luminescence. In addition, the discharge current of the capacitor 35 is also passed to the light-emitting element 23c and the dummy light-emitting element 23D. This distributes the discharge current of the capacitor 35, thereby weakening the luminous intensity of the light-emitting element 23b.

[0123] The non-light emitting regions 50a of the dummy light emitting elements 23D and the like do not necessarily have a structure similar to that of the light emitting elements 23. They may have a structure that allows a portion of the current that should be passed through the light emitting elements 23 to emit light to flow therethrough.

[0124] 19 is a circuit diagram of a light-emitting device 1 according to a modified example of the sixth embodiment. The light-emitting device 1 according to the modified example includes a non-light-emitting region 50a formed of a resistive element 50b. A portion of the discharge current of the capacitor 34 (35) flows through the resistive element 50b. The resistive element 50b can be shared by all the selection circuits. By replacing the dummy light-emitting element 23D with the resistive element 50b, the configuration of the non-light-emitting portion 50 can be further simplified.

[0125] In this way, in the sixth embodiment, a non-light-emitting section 50 including a dummy light-emitting element 23D or a resistive element 50b that is shared by all selection circuits 37 to 39 is provided, so that the configuration of the non-light-emitting section 50 can be simplified more than in the fifth embodiment.

[0126] In the first to sixth embodiments described above, when a non-target light-emitting element 23z experiences a short circuit, the transistor (second switch) 38b in the selection circuit (e.g., 38) to which the anode of the abnormal light-emitting element 23z is connected may be turned off. However, when all light-emitting elements 23 are operating normally, the transistor (second switch) 38b in the selection circuit (e.g., 38) to which the anode of the non-target light-emitting element 23z is connected may be forcibly turned off. This allows a charge to be continuously held in the capacitor 35 to which the anode of the non-target light-emitting element 23z is connected. The charge held in this capacitor 35 can be used, for example, to emit light from a light-emitting element 23 other than the original target light-emitting element 23. The charge held in this capacitor 35 can be discharged by turning on the transistor (second switch) 38b in the corresponding selection circuit just before the light-emitting element 23 to which this capacitor 35 is connected becomes a target light-emitting element.

[0127] Seventh Embodiment A light emitting device 1 according to a seventh embodiment relates to a specific structure of the dummy light emitting element 23D in the light emitting device 1 according to the fifth and sixth embodiments.

[0128] The light emitting devices 1 according to the first to sixth embodiments are, for example, surface emitting laser elements. More specifically, the light emitting devices 1 according to the first to sixth embodiments have, for example, a VCSEL (Vertical Cavity Surface Emitting Laser) structure.

[0129] Fig. 20 is a cross-sectional view showing an example of the cross-sectional structure of a light emitting device 1 with a VCSEL structure. The light emitting device 1 in Fig. 20 is configured, for example, by stacking an LD (Laser Diode) chip 46 on an LDD substrate 45. The LD chip 46 includes a substrate 21, a laminated film 22, a plurality of light emitting elements 23 formed using the laminated film 22, a plurality of anode electrodes 47, and a cathode electrode 48.

[0130] The substrate 21 of the LD chip 46 is made of a compound semiconductor such as GaAs (gallium arsenide). The surface of the substrate 21 facing the LDD substrate 45 is the front surface S2, and laser light is emitted from the back surface S3 of the substrate 21. The stacked film 22 includes a first multilayer reflector, a first spacer layer, an active layer, a second spacer layer, and a second multilayer reflector. The laser light generated in the active layer is resonated between the first multilayer reflector and the second multilayer reflector to increase the light intensity and is emitted from the back surface S3 of the substrate. Thus, the LD chip 46 of FIG. 20 is a back-illuminated type. In this specification, a light-emitting element 23 having a layer structure such as that shown in FIG. 20 is referred to as a VCSEL structure.

[0131] The plurality of light-emitting elements 23 have a mesa structure formed by processing the laminated film 22 into a mesa shape. As viewed from the substrate 21 side, an anode electrode (second pad) 47 is disposed on the upper surface of each light-emitting element 23. Similarly, as viewed from the substrate 21 side, a cathode electrode 48 is disposed on the upper and side surfaces of the laminated film 22 disposed on the end side of the LD chip 46. As viewed from the substrate 21 side, a cathode electrode 48 is also disposed on the lowermost layer of the laminated film 22 of the plurality of light-emitting elements 23. In FIG. 20 , the anode electrode 47 and the cathode electrode 48 may be reversed. While the common electrode in FIG. 20 is the cathode electrode 48, the common electrode may be the anode electrode 47, and a cathode electrode 48 may be provided on each mesa portion 20.

[0132] The LDD substrate 45 has a plurality of pads 49 for supplying drive signals to the plurality of light emitting elements 23 of the LD chip 46. The pads 49 are arranged along a surface S1 of the LDD substrate 45 that faces the LD chip 46. A bonding layer 63 is arranged on these pads 49, and the pads 49 of the LDD substrate 45 and the pads of the corresponding anode electrodes 47 of the LD chip 46 are bonded via the bonding layer 63.

[0133] The LDD substrate 45 may have a drive circuit that generates a drive signal. In this case, the LDD substrate 45 performs active driving. Alternatively, the LDD substrate 45 may supply a voltage corresponding to a drive signal generated by an external drive circuit to the pad 49. In this case, the LDD substrate 45 performs passive driving.

[0134] The substrate 21 is, for example, a compound semiconductor substrate such as a GaAs (gallium arsenide) substrate. Fig. 20 shows a front surface S2 of the substrate 21 facing the -Z direction and a back surface S3 of the substrate 21 facing the +Z direction. The front surface S1 and back surface S2 shown in Fig. 20 are perpendicular to the Z direction. In Fig. 20, the front surface S2 is the lower surface of the substrate 21, and the back surface S3 is the upper surface of the substrate 21.

[0135] The light emitting element 23 is provided on the surface S2 of the substrate 21 as part of the laminated film 22. The light emitting element 23 of this embodiment has a VCSEL structure and emits light in the +Z direction. As shown in FIG. 20 , the light emitted from the light emitting element 23 passes through the substrate 21 from the surface S2 to the back surface S3 of the substrate 21. In this way, the LD chip 11 of this embodiment is a back-emitting VCSEL chip.

[0136] Each light-emitting element 23 is provided between an anode electrode (anode wirings 31 to 33) 47 and a cathode electrode 48. When a current flows between the anode electrode 47 and the cathode electrode 48, each light-emitting element 23 emits light.

[0137] Fig. 21 is a perspective view schematically showing the difference in structure between the light-emitting element 23 and the dummy light-emitting element 23D. Fig. 21 shows the structure of the mesa portion 20 of the VCSEL structure. The left side of Fig. 21 shows the mesa portion 20 that functions as the light-emitting element 23, and the right side shows the mesa portion 20 that functions as the dummy light-emitting element 23D. The upper surface of the mesa portion 20 in Fig. 21 is the light-emitting surface. A ring-shaped electrode 62 is arranged on the light-emitting surface side of the mesa portion 20 of the light-emitting element 23, and a light-emitting portion 60 is provided inside the electrode 62.

[0138] In contrast, the mesa portion 20 of the dummy light-emitting element 23D has an electrode provided over the entire light-emitting surface. The electrode is made of a material that does not transmit light, such as tungsten. This prevents light from being emitted from the dummy light-emitting element 23D, thereby realizing a non-light-emitting region 50a.

[0139] Fig. 22 is a cross-sectional view of the dummy light-emitting element 23D of Fig. 21. The mesa portion 20 of the dummy light-emitting element 23D has a layered structure in which an n-DBR layer 25, an n-clad layer 26, an active layer 27, a p-clad layer 28, a narrowing layer 29, a p-DBR layer 61, and a p-electrode 62 are layered on a substrate 21. The narrowing layer 29 is provided with an oxidized region 29a and a non-oxidized region 29b. The p-electrode 62 covers the entire upper surface of the p-DBR layer 61 and prevents light from emitting upward from the upper surface of the p-DBR layer 61.

[0140] 23 is a perspective view schematically showing a light emitting element 23 and a dummy light emitting element 23D having a structure different from that shown in FIG. 21. In FIG. 23, the surface opposite the light emitting surface of the mesa portion 20 is shown on the upper side. An n-DBR layer 25 is disposed on the surface opposite the light emitting surface of the mesa portion 20. By removing at least a portion of the n-DBR layer 25, the amount of light reflected from the n-DBR layer 25 toward the p-DBR layer 61 can be reduced, and optical resonance operation in the mesa portion 20 is no longer performed, so that light is no longer emitted from the light emitting surface.

[0141] Fig. 24A is a cross-sectional view of the mesa portion 20 of the dummy light emitting element 23D of Fig. 23. In the dummy light emitting element 23D of Fig. 24A, the n-DBR layer 25 is partially removed.

[0142] Fig. 24B is a cross-sectional view of the mesa portion 20 of a dummy light-emitting element 23D according to a modified example of Fig. 24A. The dummy light-emitting element 23D in Fig. 24B has a smaller mesa portion 20 than that in Fig. 24A. By reducing the size of the mesa portion 20, the resistance value of the dummy light-emitting element 23D can be increased.

[0143] In this way, by adjusting the size of the mesa portion 20 of the dummy light emitting element 23D, the resistance value of the non-light emitting portion 50 can be varied.

[0144] As described above, in the seventh embodiment, when the light emitting device 1 according to the first to sixth embodiments is made into a VCSEL structure, the dummy light emitting element 23D or the resistive element can be formed by processing the light emitting surface side or the opposite surface side of the mesa portion 20. Therefore, the non-light emitting portion 50 can be formed in any location by utilizing the VCSEL manufacturing process.

[0145] The light emitting device 1 according to this embodiment can be used, for example, in a distance measuring device (also called a distance measuring module) that measures the distance to an object in a non-contact manner. In a distance measuring device, an emission signal from the light emitting device 1 is reflected by the object, and a light receiving device is required to receive the reflected light signal. The light emitting device 1 and the light receiving device may be disposed separately or on a common support member.

[0146] Fig. 25 is a cross-sectional view of a portion of a ToF sensor in which a light emitting device 1 and a light receiving device are arranged on the same mounting substrate. As shown in Fig. 25, the light emitting device 1a and the light receiving device are mounted on a common mounting substrate 13. In Fig. 25, the light receiving device is not shown.

[0147] 25 includes an LD (Laser Diode) chip 11 including the above-described light-emitting unit 2, an LDD (Laser Diode Driver) substrate 12 including the above-described drive unit 3, a mounting substrate 13, a heat dissipation substrate 14, a correcting lens holder 15, one or more correcting lenses 16, and wiring 17. The LD chip 11 is also called a VCSEL substrate. The LD chip 11 is an example of a first substrate of the present disclosure, and the LDD substrate 12 is an example of a second substrate of the present disclosure.

[0148] 25 shows X-axis, Y-axis, and Z-axis that are perpendicular to each other. The +Z direction corresponds to the upward direction, and the −Z direction corresponds to the downward direction. Note that the −Z direction may or may not strictly coincide with the direction of gravity.

[0149] The LD chip 11 is disposed on a mounting substrate 13 via a heat dissipation substrate 14, and the LDD substrate 12 is also disposed on the mounting substrate 13. The mounting substrate 13 is, for example, a printed circuit board. A light receiving unit and a signal processing unit may also be disposed on the mounting substrate 13. The heat dissipation substrate 14 is, for example, a ceramic substrate such as an aluminum oxide substrate or an aluminum nitride substrate.

[0150] The correction lens holding portion 15 is disposed on the heat dissipation substrate 14 so as to surround the LD chip 11, and holds one or more correction lenses 16 above the LD chip 11. These correction lenses 16 are included in the above-mentioned light-emitting side optical system 5. Light emitted from the light-emitting portion 2 in the LD chip 11 is corrected by these correction lenses 16 and then irradiated onto the above-mentioned subject S. Figure 25 shows, as an example, two correction lenses 16 held by the correction lens holding portion 15.

[0151] The wiring 17 is provided on the front, back, or inside of the mounting substrate 13, and electrically connects the LD chip 11 and the LDD substrate 12. The wiring 17 is, for example, a printed wiring provided on the front or back of the mounting substrate 13, or a via wiring that penetrates the mounting substrate 13. In this embodiment, the wiring 17 also passes through the inside or near the heat dissipation substrate 14.

[0152] (Configuration of Distance Measuring Device 40) FIG. 26 is a block diagram showing an example of the configuration of a distance measuring device 40 as an example of implementation of the light emitting device 1 according to this embodiment.

[0153] As shown in the figure, the distance measuring device 40 includes an emitter 51, a driver 52, a power supply circuit 53, an emitter optical system 54, a receiver optical system 55, a receiver 56, a signal processor 57, a controller 58, and a temperature detector 59.

[0154] The light-emitting unit 51 emits light from a plurality of light sources. The light-emitting unit 51 and the light-emitting side optical system 54 correspond to the above-described light-emitting device 1. As will be described later, the light-emitting unit 51 in this example has light-emitting elements 23, each of which is a vertical cavity surface-emitting laser (VCSEL), as its light source, and these light-emitting elements 23 are arranged in a predetermined pattern, such as a matrix.

[0155] The driving unit 52 is configured to have a power supply circuit 53 for driving the light emitting unit 51. The power supply circuit 53 generates a power supply voltage (a driving voltage Vd, which will be described later) for the driving unit 52 based on an input voltage (an input voltage Vin, which will be described later) from, for example, a battery (not shown) or the like provided in the distance measuring device 40. The driving unit 52 drives the light emitting unit 51 based on the power supply voltage.

[0156] Light emitted from the light-emitting unit 51 is irradiated onto a subject (object) S, which is the object of distance measurement, via a light-emitting side optical system 54. The light thus irradiated is reflected from the subject S and enters the light-receiving surface of the light-receiving unit 56 via a light-receiving side optical system 55.

[0157] The light receiving unit 56 is a light receiving element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, and receives reflected light from the subject S that enters through the light receiving side optical system 55 as described above, converts it into an electrical signal, and outputs it.

[0158] The light receiving unit 56 performs processes such as CDS (Correlated Double Sampling) and AGC (Automatic Gain Control) on the electrical signal obtained by photoelectrically converting the received light, and then performs A / D (Analog / Digital) conversion on the electrical signal, and outputs the resulting digital data to the signal processing unit 57 at the subsequent stage.

[0159] Furthermore, the light receiving unit 56 in this example outputs a frame synchronization signal Fs to the driving unit 52. This enables the driving unit 52 to cause the light emitting element 23 in the light emitting unit 51 to emit light at a timing according to the frame period of the light receiving unit 56.

[0160] The signal processing unit 57 is configured as a signal processor, for example, a DSP (Digital Signal Processor), etc. The signal processing unit 57 performs various signal processes on the digital signal input from the light receiving unit 56.

[0161] The control unit 58 is configured with, for example, a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., or an information processing device such as a DSP, and controls the drive unit 52 for controlling the light-emitting operation by the light-emitting unit 51, and controls the light-receiving operation by the light-receiving unit 56.

[0162] The control unit 58 has a function as a distance measuring unit 58a. The distance measuring unit 58a measures the distance to the subject S based on a signal input via the signal processing unit 57 (i.e., a signal obtained by receiving reflected light from the subject S). The distance measuring unit 58a in this example measures the distance to each part of the subject S in order to be able to identify the three-dimensional shape of the subject S.

[0163] The specific distance measurement method used by the distance measuring device 40 will be explained later.

[0164] The temperature detection unit 59 detects the temperature of the light emitting unit 51. The temperature detection unit 59 may be configured to detect the temperature using, for example, a diode.

[0165] In this example, information about the temperature detected by the temperature detection unit 59 is supplied to the drive unit 52, which enables the drive unit 52 to drive the light emitting unit 51 based on the temperature information.

[0166] (Range Measurement Method) The distance measurement method used in the distance measurement device 40 may be, for example, a STL (Structured Light) method or a ToF (Time of Flight) method.

[0167] The STL method is a method for measuring distance based on an image of a subject S illuminated with light having a predetermined light / dark pattern, such as a dot pattern or a grid pattern.

[0168] Fig. 27A is an explanatory diagram of the STL method. In the STL method, pattern light Lp having a dot pattern such as that shown in Fig. 27A is irradiated onto a subject S. The pattern light Lp is divided into a plurality of blocks BL, and a different dot pattern is assigned to each block BL (dot patterns are arranged not to overlap between blocks BL).

[0169] FIG. 27B is an explanatory diagram of the distance measurement principle of the STL system.

[0170] In this example, a wall W and a box BX placed in front of it are treated as the subject S, and pattern light Lp is irradiated onto the subject S. "G" in the drawing schematically represents the angle of view of the light receiving unit 56.

[0171] In addition, "BLn" in the figure denotes the light of a certain block BL in the pattern light Lp, and "dn" denotes the dot pattern of the block BLn projected on the light-receiving image by the light-receiving unit 56.

[0172] Here, if there is no box BX in front of the wall W, the dot pattern of the block BLn is projected at the position "dn'" in the figure in the received light image. In other words, the position at which the pattern of the block BLn is projected in the received light image differs depending on whether the box BX is present or not, and specifically, the pattern is distorted.

[0173] The STL method is a method for determining the shape and depth of the subject S by utilizing the fact that the irradiated pattern is distorted by the object shape of the subject S. Specifically, it is a method for determining the shape and depth of the subject S from the way the pattern is distorted.

[0174] When the STL system is adopted, for example, a global shutter type IR (Infrared) light receiving unit is used as the light receiving unit 56. In the case of the STL system, the distance measuring unit 58a controls the driving unit 52 so that the light emitting unit 51 emits pattern light, detects distortion of the pattern in the image signal obtained via the signal processing unit 57, and calculates the distance based on the distortion of the pattern.

[0175] Next, the ToF method is a method for measuring the distance to an object by detecting the time of flight (time difference) of light emitted from the light-emitting unit 51, reflected by the object, and reaching the light-receiving unit 56.

[0176] When the so-called direct ToF (dTOF) method is adopted as the ToF method, a SPAD (Single Photon Avalanche Diode) is used as the light receiving unit 56, and the light emitting unit 51 is pulse-driven. In this case, the distance measuring unit 58a calculates the time difference between the light emitted from the light emitting unit 51 and the light received by the light receiving unit 56, based on a signal input via the signal processing unit 57, and calculates the distance to each part of the subject S based on the time difference and the speed of light.

[0177] When the so-called indirect ToF (iTOF) method (phase difference method) is adopted as the ToF method, a light receiving unit capable of receiving, for example, IR light is used as the light receiving unit 56 .

[0178] (Application Example to a Mobile Body) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0179] FIG. 28 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0180] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 28, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0181] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0182] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0183] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0184] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0185] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0186] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0187] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0188] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0189] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 28, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0190] FIG. 29 is a diagram showing an example of the installation position of the imaging unit 12031.

[0191] In FIG. 29, a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

[0192] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0193] 29 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0194] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0195] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0196] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0197] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0198] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to, for example, the image capturing unit 12031 among the components described above. Specifically, the light emitting device 1 according to the present disclosure can be provided together with the image capturing unit 12031. By applying the technology according to the present disclosure to the image capturing unit 12031, it is possible to improve the resolution of distance images while suppressing the generation of electromagnetic noise, thereby enhancing the functionality and safety of the vehicle 12100.

[0199] The present technology can be configured as follows:

[0200] (1) A light emitting device comprising: a plurality of light emitting elements arranged in a two-dimensional array, each having a first and a second terminal; N first wirings (N is an integer of 2 or more) extending in a first direction; and N second wirings extending in a second direction intersecting the first direction and electrically connected to the N first wirings, respectively; a plurality of first terminal wirings electrically connected to the first terminals of the light emitting elements; a plurality of second terminal wirings electrically connected to the second terminals of the light emitting elements, each electrically connected to N of the light emitting elements; a plurality of selection circuits electrically connected to one of the first and second terminal wirings and selecting the light emitting elements to be light emitting; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and driving the plurality of light emitting elements; and a plurality of capacitors electrically connected to the one of the first and second terminal wirings and storing electric charge to be supplied to the plurality of light emitting elements, wherein each of the plurality of selection circuits has: a first switch for switching whether to charge a corresponding one of the plurality of capacitors; and a second switch for switching whether to discharge the electric charge of the corresponding capacitor. (2) The light-emitting device according to (1), wherein the selection circuit connected to a light-emitting element that is not to emit light selects whether to continue to hold charge in the corresponding capacitor or to discharge the charge by switching and controlling the second switch. (3) The light-emitting device according to (1), wherein the selection circuit connected to a light-emitting element that is not to emit light turns off the second switch to stop discharge from the corresponding capacitor when an abnormality occurs in which the anode and cathode of the light-emitting element that is not to emit light are short-circuited. (4) The light-emitting device according to (1), wherein the selection circuit connected to a light-emitting element that is not to emit light turns off the second switch to continue to hold charge in the corresponding capacitor when the light-emitting element that is not to emit light operates normally. (5) The light-emitting device according to (1), wherein the selection circuit connected to a light-emitting element that is not to emit light turns off the second switch to continue to hold charge in the corresponding capacitor.(5) The light-emitting device according to (4), wherein an impedance of a wiring between each of the plurality of capacitors and the corresponding third switch is smaller than an impedance of a wiring between each of the plurality of capacitors and the corresponding light-emitting element. (6) The light-emitting device according to (4) or (5), wherein a wiring length of a wiring between each of the plurality of capacitors and the corresponding third switch is shorter than a wiring length of a wiring between each of the plurality of capacitors and the corresponding light-emitting element. (7) The light-emitting device according to any one of (4) to (6), wherein the third switch connected to the light-emitting element that is not to be subjected to light emission is turned on in synchronization with a timing at which the light-emitting element that is to be subjected to light emission is driven, and a discharge current flows from the capacitor connected to the light-emitting element that is not to be subjected to light emission to a reference voltage node. (8) The light-emitting device according to any one of (4) to (7), wherein, when an abnormality occurs in which the anode and cathode of the light-emitting element that is not to be subjected to light emission is short-circuited, the third switch connected to the light-emitting element that is not to be subjected to light emission is turned on, and a discharge current of the capacitor connected to the light-emitting element that is not to be subjected to light emission flows to a reference voltage node instead of to the light-emitting element that is not to be subjected to light. (9) The light-emitting device according to any one of (1) to (8), further comprising a charge adjustment unit that adjusts the amount of charge to be charged in at least one of the capacitors connected to the light-emitting element to be light-emitting when an abnormality is detected in at least one of the light-emitting elements. (10) The light-emitting device according to (9), wherein, when an abnormality in at least one of the light-emitting elements is detected, the charge adjustment unit reduces the amount of charge charged in the capacitor connected to the light-emitting element in which the abnormality was detected and the capacitor connected to the light-emitting element to be light-emitting, compared to the amount of charge charged before the abnormality was detected. (11) The light-emitting device according to any one of (1) to (7), wherein, when an abnormality in at least one of the light-emitting elements is detected, the plurality of selection circuits select, as a new light-emitting element, a light-emitting element connected to the drive circuit different from the abnormal light-emitting element.(12) The light-emitting device according to (11), further comprising: an abnormality detection unit that detects an abnormality in at least one of the light-emitting elements; wherein the plurality of selection circuits select, as a light-emitting target, a light-emitting element connected to the drive circuit different from a light-emitting element whose abnormality has been detected by the abnormality detection unit; and the abnormality detection unit outputs an abnormality detection signal to the outside. (13) The light-emitting device according to (11) or (12), further comprising: when an abnormality in at least one of the light-emitting elements is detected, the plurality of selection circuits select, as a light-emitting target, two or more light-emitting elements from the plurality of light-emitting elements that are arranged in locations that do not simultaneously enter a human pupil. (14) The light-emitting device according to any one of (1) to (7), further comprising: a non-light-emitting unit that is capable of flowing a portion of a discharge current of the capacitor connected to the light-emitting element that is a light-emitting target; and when an abnormality in at least one of the light-emitting elements is detected, the discharge current of the capacitor connected to the light-emitting element that is a light-emitting target flows in a distributed manner to the light-emitting element that is a light-emitting target and the non-light-emitting unit. (15) The light-emitting device according to (14), wherein the non-light-emitting section has a plurality of non-light-emitting regions provided corresponding to the plurality of light-emitting elements, and when an abnormality is detected in at least one of the light-emitting elements, a discharge current of the capacitor connected to the light-emitting elements to be emitted flows in a distributed manner among the non-light-emitting regions, the number of which is the same as the number of the light-emitting elements to be emitted, and the light-emitting elements to be emitted. (16) The light-emitting device according to (14), wherein the non-light-emitting section has a number of non-light-emitting regions fewer than the plurality of light-emitting elements, and when an abnormality is detected in at least one of the light-emitting elements, a discharge current of the capacitor connected to the light-emitting elements to be emitted flows in a distributed manner among the non-light-emitting regions, the number of which is fewer than the total number of the light-emitting elements to be emitted, and the light-emitting elements to be emitted. (17) The light-emitting device according to (15) or (16), wherein the non-light-emitting regions are non-light-emitting bodies having the same element structure as the light-emitting elements, or are resistive elements. (18) The light emitting device according to any one of (1) to (17), wherein the plurality of light emitting elements are vertical cavity surface emitting lasers (VCSELs) or other types of surface emitting laser elements.(19) The light emitting device according to (18), wherein the VCSEL has a plurality of mesa portions each emitting laser light, and some of the plurality of mesa portions have a non-light emitting structure. (20) A light emitting device comprising: a light emitting unit that emits light toward a subject; a light receiving unit that receives light that is reflected by the subject; and a distance measuring unit that measures a distance to the subject based on the light emitted by the light emitting unit and the light received by the light receiving unit, wherein the light emitting unit includes: a plurality of light emitting elements arranged in a two-dimensional array, each having a first and a second terminal; N first wirings (N is an integer of 2 or more) extending in a first direction; and N second wirings that extend in a second direction intersecting the first direction and are electrically connected to the N first wirings, respectively, a plurality of first terminal wirings that are electrically connected to the first terminals of the light emitting elements; a plurality of second terminal wirings that are electrically connected to the second terminals of the light emitting elements, each second terminal wiring being electrically connected to N of the light emitting elements; a plurality of selection circuits that are electrically connected to one of the first and second terminal wirings and that select the light emitting elements to be emitted; and a plurality of drive circuits that are electrically connected to the other of the first and second terminal wirings and that drive the plurality of light emitting elements. a plurality of capacitors electrically connected to one of the first and second terminal wirings and storing electric charge to be supplied to the plurality of light-emitting elements, wherein each of the plurality of selection circuits has a first switch that switches whether or not to charge a corresponding one of the plurality of capacitors, and a second switch that switches whether or not to discharge the electric charge of the corresponding capacitor, and the selection circuit connected to a light-emitting element that is not to emit light controls switching of the second switch when an abnormality is detected in the light-emitting element that is not to emit light.

[0201] The aspects of the present disclosure are not limited to the individual embodiments described above, but include various modifications that may be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-described contents. In other words, various additions, modifications, and partial deletions are possible within the scope of the conceptual idea and spirit of the present disclosure, which is derived from the contents defined in the claims and their equivalents.

[0202] REFERENCE SIGNS LIST 1, 1a light emitting device, 2 light emitting section, 3 driving section, 5 light emitting side optical system, 11 LD chip, 12 LDD substrate, 13 mounting substrate, 14 heat dissipation substrate, 15 correction lens holding section, 16 correction lens, 17 wiring, 18 light receiving element, 20 mesa section, 21 substrate, 22 laminated film, 23 light emitting element, 23a, 23b, 23c, 23d, 23e, 23z light emitting element, 23D dummy light emitting element, 24 transistor, 25 n-DBR layer, 26 cladding layer, 27 active layer, 28 cladding layer, 29 narrowing layer, 29a oxidized region, 29b non-oxidized region, 30 third switch, 30B bypass path, 31 first anode wiring, 31a first horizontal wiring, 31b first vertical wiring, 32 second anode wiring, 32a Second horizontal wiring, 32b Second vertical wiring, 33 Third anode wiring, 33a Third horizontal wiring, 33b Third vertical wiring, 34 First capacitor, 35 Second capacitor, 36 Third capacitor, 37 First selection circuit, 37a Transistor (first switch), 37b Transistor (second switch), 38 Second selection circuit, 38a Transistor (first switch), 38b Transistor (second switch), 39 Third selection circuit, 39a Transistor, 39b Transistor, 40 Range finder, 41 Cathode wiring, 42 Gate wiring, 43 Sensor, 45 LDD substrate, 46 LD chip, 47 Anode electrode (second pad), 48 Cathode electrode, 49 Pad, 50 Non-light emitting portion, 50a Non-light emitting region, 50b Resistive element, 51 Light emitting portion, 52 Drive portion, 53 Power supply circuit, 54 Light emitting side optical system, 55 Light receiving side optical system, 56 Light receiving unit, 57 signal processing unit, 58 control unit, 58a distance measuring unit, 58a distance measuring unit of this example, 59 temperature detection unit, 60 light emitting unit on the inside, 61 p-DBR layer, 62 p-electrode, 63 junction layer, 71 first voltage detection circuit, 72 second voltage detection circuit, 73 third voltage detection circuit

Claims

a plurality of first terminal wirings (N is an integer of 2 or more) extending in a first direction and N second wirings (N is an integer of 2 or more) extending in a second direction intersecting the first direction and electrically connected to the N first wirings, the plurality of first terminal wirings being electrically connected to the first terminals of the light-emitting elements; a plurality of second terminal wirings electrically connected to the second terminals of the light-emitting elements, each of the plurality of second terminal wirings being electrically connected to N of the light-emitting elements; a plurality of selection circuits electrically connected to one of the first and second terminal wirings and selecting the light-emitting elements to be light-emitting; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and driving the plurality of light-emitting elements; and a plurality of capacitors electrically connected to the one of the first and second terminal wirings and storing electric charge to be supplied to the plurality of light-emitting elements, each of the plurality of selection circuits having a first switch for switching whether or not to charge a corresponding one of the plurality of capacitors, and a second switch for switching whether or not to discharge the electric charge of the corresponding capacitor, The selection circuit connected to a light emitting element that is not to emit light selects whether the corresponding capacitor continues to hold charge or is discharged by switching and controlling the second switch.

2. The light-emitting device according to claim 1, wherein the selection circuit connected to a light-emitting element that is not to emit light turns off the second switch to stop discharging from the corresponding capacitor when an abnormality occurs in which the anode and cathode of the light-emitting element that is not to emit light are short-circuited.

3. The light-emitting device according to claim 1, wherein the selection circuit connected to a light-emitting element not to be emitted turns off the second switch and continues to hold charge in the corresponding capacitor when the light-emitting element not to be emitted operates normally.

4. The light emitting device according to claim 1, further comprising a plurality of third switches arranged between the plurality of capacitors and the plurality of light emitting elements, for switching whether or not to discharge the electric charge of the plurality of capacitors, and a discharge current from the capacitor connected to the light emitting element that is not to be emitted does not flow to the light emitting element that is not to be emitted, but flows through the corresponding third switch to a reference voltage node.

5. The light emitting device according to claim 4, wherein an impedance of a wiring between each of the plurality of capacitors and the corresponding third switch is smaller than an impedance of a wiring between each of the plurality of capacitors and the corresponding light emitting element.

6. The light emitting device according to claim 4, wherein the length of the wiring between each of the plurality of capacitors and the corresponding third switch is shorter than the length of the wiring between each of the plurality of capacitors and the corresponding light emitting element.

7. The light emitting device according to claim 4, wherein the third switch connected to the light emitting element that is not to be emitted is turned on in accordance with a timing for driving the light emitting element that is to be emitted, and a discharge current is caused to flow from the capacitor connected to the light emitting element that is not to be emitted to a reference voltage node.

8. The light-emitting device according to claim 4, wherein, when an abnormality occurs in which the anode and cathode of the non-target light-emitting element are short-circuited, the third switch connected to the non-target light-emitting element is turned on, so that the discharge current of the capacitor connected to the non-target light-emitting element is not passed to the non-target light-emitting element but to a reference voltage node.

9. The light-emitting device according to claim 1, further comprising a charge adjustment unit that adjusts the amount of charge charged to at least one of the plurality of capacitors that is connected to the light-emitting element to be illuminated when an abnormality is detected in at least one of the light-emitting elements.

10. The light-emitting device described in claim 9, wherein, when an abnormality is detected in at least one of the light-emitting elements, the charge adjustment unit reduces the amount of charge charged in the capacitor connected to the light-emitting element in which an abnormality has been detected and the capacitor connected to the light-emitting element to be emitted, compared to the amount of charge charged before the abnormality is detected.

11. The light-emitting device according to claim 1, wherein, when an abnormality is detected in at least one of the light-emitting elements, the plurality of selection circuits select, as a new light-emitting element to be emitted, a light-emitting element connected to the drive circuit other than the abnormal light-emitting element.

12. A light-emitting device as described in claim 11, further comprising an abnormality detection unit that detects an abnormality in at least one of the light-emitting elements, wherein the plurality of selection circuits select as the light-emitting element a light-emitting element connected to the drive circuit other than the light-emitting element in which an abnormality has been detected by the abnormality detection unit, and the abnormality detection unit outputs an abnormality detection signal to the outside.

13. The light-emitting device according to claim 11, wherein, when an abnormality is detected in at least one of the light-emitting elements, the plurality of selection circuits select, from among the plurality of light-emitting elements, two or more light-emitting elements that are positioned so as not to be simultaneously entered by a human pupil, as light-emitting elements.

14. The light-emitting device according to claim 1, further comprising a non-light-emitting section capable of flowing a portion of the discharge current of the capacitor connected to the light-emitting element to be illuminated, and when an abnormality is detected in at least one of the light-emitting elements, the discharge current of the capacitor connected to the light-emitting element to be illuminated flows in a distributed manner between the light-emitting element to be illuminated and the non-light-emitting section.

15. The light-emitting device according to claim 14, wherein the non-light-emitting section has a plurality of non-light-emitting regions corresponding to the plurality of light-emitting elements, and when an abnormality is detected in at least one of the light-emitting elements, the discharge current of the capacitor connected to the light-emitting element to be illuminated flows in a distributed manner among the non-light-emitting regions in the same number as the number of the light-emitting elements to be illuminated, and among the light-emitting elements to be illuminated.

16. The light-emitting device according to claim 14, wherein the non-light-emitting portion has non-light-emitting areas whose number is less than the number of the plurality of light-emitting elements, and when an abnormality is detected in at least one of the light-emitting elements, the discharge current of the capacitor connected to the light-emitting element to be illuminated flows in a distributed manner among the non-light-emitting areas whose number is less than the total number of the light-emitting elements to be illuminated and among the light-emitting elements to be illuminated.

17. The light emitting device according to claim 15, wherein the non-light emitting region is a non-light emitting body having the same element structure as the light emitting element, or is a resistive element.

18. The light emitting device according to claim 1, wherein the plurality of light emitting elements are VCSELs (Vertical Cavity Surface Emitting Lasers) or other types of surface emitting laser elements.

19. The light emitting device according to claim 18, wherein the VCSEL has a plurality of mesa portions each emitting laser light, and some of the plurality of mesa portions have a non-light emitting structure.

20. A device comprising: a light-emitting unit that emits light toward a subject; a light-receiving unit that receives light reflected by the subject from the emitted light; and a distance measuring unit that measures the distance to the subject based on the light emitted by the light-emitting unit and the light received by the light-receiving unit, wherein the light-emitting unit includes: a plurality of light-emitting elements arranged in a two-dimensional array, each having a first and a second terminal; N first wirings (N is an integer of 2 or more) extending in a first direction; and N second wirings that extend in a second direction intersecting the first direction and are electrically connected to the N first wirings, respectively; a plurality of first terminal wirings that are electrically connected to the first terminals of the light-emitting elements; a plurality of second terminal wirings that are electrically connected to the second terminals of the light-emitting elements and each are electrically connected to N of the light-emitting elements; a plurality of selection circuits that are electrically connected to one of the first and second terminal wirings and select the light-emitting elements to be emitted; and a plurality of drive circuits that are electrically connected to the other of the first and second terminal wirings and drive the plurality of light-emitting elements. a plurality of capacitors electrically connected to one of the first and second terminal wirings and storing electric charge to be supplied to the plurality of light-emitting elements, each of the plurality of selection circuits having a first switch for switching whether or not to charge a corresponding capacitor among the plurality of capacitors, and a second switch for switching whether or not to discharge the electric charge of the corresponding capacitor, and the selection circuit connected to a light-emitting element that is not to be subjected to light emission controls switching of the second switch when an abnormality is detected in the light-emitting element that is not to be subjected to light emission.

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