Light-emitting device and distance measurement device

Abstract

To minimize the influence of abnormality without causing a through current to flow through a drive circuit.SOLUTION: A light emitting device includes: 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 electric charges to be supplied to the plurality of light-emitting elements. The selection circuits include a first switch that switches whether to charge electric charges to a corresponding capacitor among the plurality of capacitors, and a second switch that switches whether to discharge electric charges of the corresponding capacitor. The 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.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] LiDAR (Light Detection and Ranging) is one method of obtaining distance information. LiDAR shines light on the object for which distance information is to be obtained, and estimates the distance based on information obtained from the light reflected by the object. One of the LiDAR distance measurement methods is the time of flight (ToF). 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 a distance measurement system that uses 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. In Solid State LiDAR, for example, an array-shaped light emitting unit is used to select the location to emit light and project light onto the intended irradiation area. By sequentially switching the light emitting locations in the light emitting unit, it is possible to realize a light emitting system that scans light in 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 corresponding to the light emitting Ch of the light receiving element.

[0004] This type of light-emitting system is equipped with a light source in which laser diodes are arranged in an array, and a driving circuit, and is capable of driving the laser diodes of a selected light-emitting channel to emit light. By having no physically moving parts, the risk of failure can be reduced in situations where high reliability is required (see Patent Document 1). Patent Document 1 proposes a method of arranging multiple anodes and cathodes in a matrix and driving them individually. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2022-526998 Summary of the Invention [Problem to be solved by the invention]

[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 the drive circuit that controls the charging and discharging of the capacitor that holds the 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. In addition, 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, even if an abnormality occurs in which the anode and cathode of a light-emitting element are short-circuited, no through current flows through the drive circuit and that can minimize the effects of the abnormality. [Means for solving the problem]

[0008] In order to solve the above problems, according to the present disclosure, there is provided a light emitting device including: a plurality of light emitting elements arranged in a two-dimensional array, each having a first terminal and a second terminal; a plurality of first terminal wirings including 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, 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 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 configured to select the light emitting element to be a light emitting target; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and configured to drive the plurality of light-emitting elements; a plurality of capacitors electrically connected to the one of the first and second terminal wirings and configured to store electric charges to be supplied to the plurality of light-emitting elements; Each of the plurality of selection circuits a first switch that switches whether or not a corresponding capacitor among the plurality of capacitors is charged; a second switch for switching whether or not the charge in the corresponding capacitor is discharged; The selection circuit connected to the light emitting element not to emit light selects whether to keep the charge held in the corresponding capacitor or to discharge the charge by switching and controlling the second switch. A light emitting device is provided.

[0009] The selection circuit connected to a light-emitting element that is not to be emitted 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 be emitted are short-circuited.

[0010] The selection circuit connected to a 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] a plurality of third switches disposed between the plurality of capacitors and the plurality of light-emitting elements, the third switches switching whether or not to discharge the charges of the plurality of capacitors; A discharge current from the capacitor connected to the light-emitting element not to emit light may flow to the reference voltage node through the corresponding third switch without flowing to the light-emitting element not to emit light.

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

[0013] A wiring length between each of the plurality of capacitors and the corresponding third switch may be shorter than a wiring length 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 of driving the light-emitting element that is to be emitted, and a discharge current may be caused to flow 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, so that the discharge current of the capacitor connected to the non-light-emitting element is not passed to the non-light-emitting element but is passed to a reference voltage node.

[0016] The light emitting device may further include a charge adjustment unit that adjusts the amount of charge 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 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] an abnormality detection unit that detects an abnormality in at least one of the light-emitting elements; the plurality of selection circuits select, as a light emitting element to be emitted, a light emitting element connected to the drive circuit different from a light emitting element in which an abnormality has been detected by the abnormality detection unit; 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 will not be simultaneously entered by a human pupil as the light-emitting elements.

[0021] a non-light-emitting portion capable of passing a part of a discharge current of the capacitor connected to the light-emitting element to be emitted; 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 to the light-emitting element to be illuminated and the non-light-emitting portion.

[0022] the non-light emitting portion has a plurality of non-light emitting regions provided corresponding to the plurality of light emitting elements, 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 areas, the number of which is the same as the number of the light-emitting elements to be illuminated, and the light-emitting element to be illuminated.

[0023] the non-light emitting portion has non-light emitting regions whose number is less than the number of the light emitting elements, 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 areas, the number of which is less 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 has a plurality of mesas each of which emits laser light; Some of the mesas may have a non-light-emitting structure.

[0027] According to the present disclosure, a light emitting unit that emits light toward a subject; a light receiving unit that receives light that is emitted and reflected by the subject; 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; Equipped with The light emitting unit is A plurality of light emitting elements arranged in a two-dimensional array, each having a first terminal and a second terminal; a plurality of first terminal wirings including 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, 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 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 configured to select the light emitting element to be a light emitting target; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and configured to drive the plurality of light-emitting elements; a plurality of capacitors electrically connected to the one of the first and second terminal wirings and configured to store electric charges to be supplied to the plurality of light-emitting elements; Each of the plurality of selection circuits a first switch that switches whether or not a corresponding capacitor among the plurality of capacitors is charged; a second switch for switching whether or not the charge in the corresponding capacitor is discharged; The selection circuit connected to the non-target light-emitting element controls switching of the second switch when an abnormality is detected in the non-target light-emitting element. A ranging device is provided. [Brief description of the drawings]

[0028] [Figure 1] FIG. 2 is a circuit diagram of the light emitting device according to the first embodiment. [Diagram 2] FIG. 2 is a circuit diagram showing the connection relationship between a selection circuit, a light-emitting element, and a driver circuit. [Diagram 3] FIG. 3 is a timing diagram corresponding to the circuit diagram of FIG. 2. [Figure 4] 13 is a diagram showing a state in which an abnormality occurs in which the anode and cathode of a light-emitting element of a specific channel are short-circuited. [Diagram 5] FIG. 6 is a circuit diagram showing a main part of the light emitting device according to the first embodiment; FIG. [Figure 6] FIG. 4 is a circuit diagram for explaining a problem with the light emitting device according to the first embodiment. [Figure 7] FIG. 7 is a timing diagram corresponding to the circuit diagram of FIG. [Figure 8] FIG. 6 is a circuit diagram of a main part of a light emitting device according to a second embodiment. [Figure 9] FIG. 9 is a timing diagram corresponding to the circuit diagram of FIG. [Figure 10] FIG. 13 is a diagram showing a path through which a discharge current of a capacitor flows when a third switch is off. [Figure 11] FIG. 11 is a circuit diagram of a light emitting device according to a third embodiment. [Figure 12] FIG. 12 is a timing diagram corresponding to the circuit diagram of FIG. [Figure 13] 12 is a timing diagram corresponding to the circuit diagram of FIG. 11 when no control of the current output from the selection circuit is performed. [Figure 14] A diagram in which the signal waveforms in Figures 12 and 13 are superimposed. [Figure 15] FIG. 11 is a circuit diagram of a light emitting device according to a fourth embodiment. [Figure 16A] 10 is a diagram showing a schematic view of a light emitting position and a light receiving position of a light receiving device (not shown) when all light emitting elements perform a normal light emitting operation; [Figure 16B] 11 is a diagram showing a schematic view of a light-emitting position and a light-receiving position (not shown) when a short circuit occurs in some light-emitting elements; [Figure 17] FIG. 13 is a circuit diagram of a light emitting device according to a fifth embodiment. [Figure 18] FIG. 13 is a circuit diagram of a light emitting device according to a sixth embodiment. [Figure 19] FIG. 23 is a circuit diagram of a light emitting device according to a modified example of the sixth embodiment. [Figure 20] FIG. 1 is a cross-sectional view showing an example of a cross-sectional structure of a light emitting device having a VCSEL structure. [Figure 21] FIG. 13 is a perspective view showing a schematic difference in structure between a light-emitting element and a dummy light-emitting element. [Figure 22] 22 is a cross-sectional view of the dummy light-emitting element in FIG. 21. [Diagram 23] 22 is a perspective view showing a light emitting element having a structure different from that in FIG. 21 and a dummy light emitting element. [Figure 24A] 24 is a cross-sectional view of a mesa portion of the dummy light-emitting element in FIG. 23. [Figure 24B] FIG. 24B is a cross-sectional view of a mesa portion of a dummy light-emitting element according to a modified example of FIG. 24A. [Diagram 25] FIG. 1 is a 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. [Figure 26] FIG. 2 is a block diagram showing an example of the configuration of a distance measuring device as an implementation example of the light emitting device according to the embodiment. [Figure 27A] An explanatory diagram of the STL method. [Figure 27B] An explanatory diagram of the distance measurement principle of the STL method. [Figure 28] FIG. 1 is a block diagram showing an example of a schematic configuration of a vehicle control system. [Figure 29] FIG. 4 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment 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 have 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 the 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 9×9 light emitting elements 23 and 9×9 transistors 24. Thus, the light emitting device 1 shown in FIG. 1 includes a 9ch×9ch light emitting element array. The number of channels of the light emitting element array is arbitrary.

[0031] As shown in Fig. 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 wiring includes N first wirings (N is an integer of 2 or more) 31a, 32a, 33a extending in a first direction X, and N second wirings 31b, 32b, 33b extending in a second direction Y intersecting the first direction X and electrically connected to the N first wirings 31a, 32a, 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 wiring 31a and the second wiring 31b connected to each other are referred to as the first anode wiring 31, the second wiring 32a and the second wiring 32b connected to each other are referred to as the second anode wiring 32, and the third wiring 33a and the third wiring 33b connected to each other are referred to as the third anode wiring 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, each set consisting of the first to third anode wirings 31 to 33. Fig. 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 a first direction X (horizontal direction) and arranged along a 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 include a plurality (e.g., five) of first wirings 32a each extending in a first direction X (horizontal direction) and arranged along a second direction Y (vertical direction), and a plurality (e.g., five) of 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 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] Fig. 1 shows an example in which the light emitting device 1 according to the first embodiment includes five first horizontal wirings 31a, five first vertical wirings 31b, five second horizontal wirings 32a, five second vertical wirings 32b, five third horizontal wirings 33a, and five third vertical wirings 33b. Fig. 1 shows an example in which M sets of N first wirings and N second wirings are provided. The number of light emitting elements 23 shown in Fig. 1, represented by N and M, is N(M-2) x N(M-2).

[0038] The first to third anode wirings 31 to 33 may include Ma sets of the first to Nth horizontal wirings and Mb sets of the first to Nth vertical wirings (Ma and Mb are integers of 2 or more satisfying 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 the first switch of the present disclosure. The transistors 37b, 38b, and 39b are examples of the second switch 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 indicated by a thick solid line, the second anode wiring 32 is indicated by a thick dashed line, and the third anode wiring 33 is indicated 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 shape. These first horizontal wirings 31a and first vertical wirings 31b are electrically connected to each other at the points where the first horizontal wirings 31a and the 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 wires 31a to 33a extend in a first direction X (horizontal direction) and are adjacent to each other in a second direction Y (vertical direction). Although the first to third horizontal wires 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 wires 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 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 (9 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 to sandwich 9×9 light emitting elements 23. Each of the second to fourth sets of first to third vertical wirings 31b to 33b is arranged along one row (9 light emitting elements 23).

[0046] The anode of each light emitting element 23 is electrically connected to any 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 the 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 the first to third vertical wirings 31b to 33b. The anode of each light emitting element 23 may be electrically connected to any one of the first to third horizontal wirings 31a to 33a instead of being electrically connected to any 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 the 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 wire 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 a 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 element 23 to generate (output) light from the light-emitting element 23. For example, when light is to be generated from a certain light-emitting element 23, a predetermined signal is applied to the gate wiring 42 of the drive circuit E for this light-emitting element 23. This causes conduction between the source and drain of each transistor 24 in this drive circuit E, making it possible to pass a current through this light-emitting element 23. When a current flows through this light-emitting element 23, light is generated from this 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 drain of the transistor 37a and the drain of the transistor 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 accumulate charge in each of the first capacitors 34. The transistor 37b is used to discharge charge from each of the first capacitors 34. When a predetermined signal is applied to the gate of the transistor 37a, charge is accumulated in each of the first capacitors 34. When a predetermined signal is applied to the gate of the transistor 37b, charge is discharged from each of the first capacitors 34. Therefore, according to this embodiment, by selectively accumulating 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 through each of the light-emitting elements 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 charges in the second capacitors 35 by the second selection circuit 38, it is possible to pass a current through each light-emitting element 23 electrically connected to the second anode wiring 32. Furthermore, according to this embodiment, by storing charges in the third capacitors 36 by the third selection circuit 39, it is possible to pass a current through each light-emitting element 23 electrically connected to the third anode wiring 33.

[0055] [1st to 3rd 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 accumulates electric charge to be supplied to the light-emitting element 23 electrically connected to the first anode wiring 31. Each second capacitor 35 accumulates electric charge to be supplied to the light-emitting element 23 electrically connected to the second anode wiring 32. Each third capacitor 36 accumulates electric charge to be supplied to the light-emitting element 23 electrically connected to the third anode wiring 33. According to this embodiment, electric charge is supplied from the first to third capacitors 34 to 36 to each light-emitting element 23, so that a current can flow to each light-emitting element 23. Each of the first to third capacitors 34 to 36 has one electrode electrically connected to any 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 approximately square in a 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 of 2 or more). FIG. 1 shows an example where K is 4.

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

[0058] In each group, the first to third capacitors 34 to 36 are arranged in order in a clockwise direction. For example, the first capacitor 34, the second capacitor 35, and the third capacitor 36 of the first group are arranged on the left side, the center, and the right side, respectively, near the top side of the square. The first capacitor 34, the second capacitor 35, and the third capacitor 36 of the second group are arranged on the upper side, the center, and the lower side, respectively, near the right side of the square. As a result, the four groups of the 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 the fifth column among the 9×9 light emitting elements 23. In FIG. 1, the four groups of the 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 top left is close to the first capacitor 34 on the top side, but far from the first capacitor 34 on the bottom side. On the other hand, the light emitting element 23 at the bottom right is close to the third capacitor 36 on the right side, but far from the third capacitor 36 on the left side. Therefore, the average distance between the light emitting element 23 at the top left and the four first capacitors 34 is close to the average distance between the light emitting element 23 at the bottom right and the four third capacitors 36. This is similar 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 the present embodiment may include the first to third capacitors 34-36 only near one, two, or three of the four sides of the square. However, in this case, the first to third capacitors 34-36 are also desirably arranged symmetrically or nearly symmetrically with respect to the center of the square. Therefore, the light emitting device 1 of the present embodiment desirably includes the first to third capacitors 34-36 on two or more of the four sides of the square. For example, by arranging two sets of the first to third capacitors 34-36 near the top and bottom sides of the square, it is possible to realize 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 element 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, a plurality of capacitors 34 may be connected to the selection circuit 37, and a plurality of capacitors 35 may be connected to the selection circuit 38. However, for the sake of simplicity, FIG. 2 shows an example in which one capacitor 34, 35 is connected to each of the selection circuits 37, 38. The selection circuit 37 controls charging and discharging of the capacitor 34. The charge stored in the capacitor 34 is used to cause all the 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 the 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 the light-emitting elements 23 in the row connected to the capacitor 35 to emit light.

[0064] A driving circuit E is connected to the cathode of each light-emitting element 23. A plurality of driving circuits E are arranged along the first direction X (horizontal direction), and each driving circuit E drives the cathode of the corresponding light-emitting element 23. More specifically, when the transistor 24 of each driving circuit E is turned on, the cathode voltage of the light-emitting element 23 connected to the drain of the 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] The light emitting device 1 of the first embodiment has a plurality of light emitting elements 23 arranged two-dimensionally, as shown in FIG. 1, and the light emitting element 23 of a specific channel is selected and made to emit light by selection circuits 37 to 39 and a plurality of driving circuits E.

[0066] During the period from time t1 to time 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 becomes low level, the transistor (first switch) 37a turns on, and the capacitor 34 connected to the selection circuit 37 is charged. As a result, the anode voltage of each light-emitting element 23 in the row connected to the capacitor 34 rises linearly. During the period from time t3 to time 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 becomes high level, the transistor 24a turns on, the charge of the capacitor 34 is discharged, and an instantaneous current flows 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. Due to the discharge of the capacitor 34, the anode voltage of the light-emitting element 23 of the specific channel drops sharply.

[0067] On the other hand, between times t1 and t4, the gate voltage of the transistor 38a in the selection circuit 38 is maintained at a high level, so that the capacitor 35 connected to the selection circuit 38 is not charged. In addition, 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 is maintained at a low level, so that 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 to on, and a transistor (second switch) 37b is set to off. On the other hand, in the selection circuit 38 to which the anode of the light-emitting element 23 to be not emitted is connected, a transistor (first switch) 38a is set to off, and a transistor (second switch) 38b is set to on. As a result, a discharge current from the capacitor 35 to which the anode of the light-emitting element 23 to be not emitted flows through the transistor (second switch) 38b to the ground node, and the capacitor 35 is discharged.

[0069] Fig. 4 is a diagram showing a state in which an abnormality occurs in which the anode and cathode of the 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 object to emit light, and the light-emitting element 23z, which is not the object to emit light and has its cathode connected to that of the light-emitting element 23a, is abnormal in that its 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 light-emitting elements 23 emit light by applying a voltage higher than the cathode to the anode, but if a voltage higher than the anode is applied to the cathode for some reason, an abnormality may occur in which the anode and the cathode are short-circuited. 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, and the transistor (first switch) 38a of the selection circuit 38 to which the anode of the light-emitting element 23 not to be emitted is connected is set to off and the transistor (second switch) 38b is set to on. Therefore, a part 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, and then flows from the cathode to the anode of the light-emitting element 23z that has caused the short-circuit abnormality, and 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 selection circuit 37 through transistor (first switch) 37a will flow through transistor (second switch) 38b of selection circuit 38 to the ground node, causing a large amount of through current to flow from the power supply voltage node of selection circuit 37 to the ground node of selection circuit 38, which may destroy the circuit elements that make up selection circuits 37 and 38.

[0071] Fig. 5 is a circuit diagram showing a main part 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 in 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 object, 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 that shown in FIG. 4 in that, as shown in FIG. 5, a transistor (second switch) 38b of a selection circuit 38 connected to the anode of the light-emitting element 23z that has a short circuit is turned off. A part of the current flowing from the power supply voltage node of the selection circuit 37 to a transistor (first switch) 37a flows to a capacitor 34 to charge the capacitor 34, and the other current flows from the anode to the cathode of the light-emitting element 23a and then flows from the cathode to the anode of the light-emitting element 23z that has a short circuit. Since the transistor (second switch) 38b of the selection circuit 38 is off, this current does not flow to the selection circuit 38, but instead flows to the capacitor 35 to charge the capacitor 35. As a result, even if a light-emitting element 23z that has a short circuit is present, a through current does not flow to the selection circuits 37 and 38, and destruction of the circuit elements can be prevented.

[0073] It is possible to detect the abnormality of the non-light emitting element 23z, in which the anode and cathode are short-circuited, by detecting the current flowing through the output wiring of the selection circuits 37-39. Although omitted 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 of the selection circuits 37-39 to detect the abnormality of the light emitting element 23, and when the abnormality detection circuit detects an abnormality, the selection circuit (e.g., 38) to which the anode of the abnormal light emitting element 23z is connected switches off the 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, and prevents 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 to emit light can control switching of the transistor (second switch) 38b when an abnormality is detected in the light-emitting element 23z that is not to emit light, 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 to emit light, 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 caused a short circuit 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 caused a short circuit in the row connected to the capacitor 34 is made to emit light, the light emitting element 23c that is not to emit light in the row connected to the capacitor 35 also emits light.

[0077] 7, during the period from time t1 to time t2, the transistor (first switch) 37a of the selection circuit 37 is turned on. As a result, the capacitor 34 is charged from time t1 to time t2, and the anode voltage of the light-emitting element 23b to be emitted gradually increases. When the transistor 24b of the drive circuit E connected to the cathode of the light-emitting element 23b is turned on at time t2, the discharge current of the capacitor 34 flows through the transistor 24b between the anode and cathode of the light-emitting element 23b, and the light-emitting element 23c emits 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 also 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 be flowed to the bypass path 30B.

[0080] The third switch 30 is configured using, for example, an NMOS transistor. The 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-emission target light-emitting element 23c can be passed through the bypass path 30B via the third switch 30 without passing it to the non-emission target light-emitting element 23c. As a result, as shown in FIG. 6, when the light-emitting element 23a to be emitted is made to emit light, if the capacitor 35 connected to the non-emission target light-emitting element 23z is charged due to a short circuit abnormality of the non-emission target light-emitting element 23z, the discharge current of the capacitor 35 can be passed through the bypass path 30B without passing it to the non-emission target light-emitting element 23c. Therefore, as shown in FIG. 8, only the light-emitting element 23b to be emitted can be made to emit light.

[0082] Since 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 becomes. In Fig. 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 a current flows more easily through a wiring having a 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 FIG. 9, the operation during the period from time t1 to t2 is the same as that in FIG. 7. When the transistor 24b of the drive circuit E connected to the cathode of the light-emitting element 23b to be emitted is turned on at time t3, the discharge current of the capacitor 34 connected to the anode of the light-emitting element 23b to be emitted flows through the anode-cathode of the light-emitting element 23b to the transistor 24b, and the light-emitting element 23b emits light. Also, at time t3, the third switch 30 connected to the anode of the light-emitting element 23c not to be emitted is turned on. As a result, the discharge current of the capacitor 35 connected to the anode of the light-emitting element 23c not to be emitted does not flow to the anode of the light-emitting element 23c not to be emitted, but flows to the reference voltage (for example, ground) node through the third switch 30 on the bypass path 30B. Therefore, the light-emitting element 23c not to be emitted 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 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 through the non-target light-emitting element 23 but is passed to the reference voltage node.

[0087] Fig. 10 is a diagram showing a 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 that 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 23b 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 35, it is possible to stop the light emission of the non-target light-emitting element 23c as shown in Fig. 9.

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

[0089] (Third embodiment) In the third embodiment, when an abnormality occurs in which the anode and cathode are shorted in some of the light-emitting elements 23z, not only the light-emitting element 23b that is the target of light emission but also the light-emitting element 23c that is not the target of light emission may emit light as shown in Fig. 6, 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 element 23b that is the target of light emission is controlled.

[0090] FIG. 11 is a circuit diagram of the light emitting device 1 according to the 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 from 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, when the detected voltage is lower than a predetermined voltage, the transistor 37a is turned on to start storing the charge. On the other hand, when the detected voltage is higher than the predetermined voltage, the transistor 37a is turned off to end storing the charge. According to this modification, it is possible to change the light emission luminance of the light emitting device 1 by changing the value of this predetermined voltage. The value of this predetermined voltage is adjusted, for example, by the voltage detection units 71 to 73 shown in FIG. 1. In this way, the voltage detection units 71 to 73 function as a charge adjustment unit that adjusts the amount of charge to be charged in at least one of the capacitors 34 to 36, which is connected to the light emitting element to be emitted, when an abnormality is detected in at least one light emitting element 23. For example, when an abnormality is detected in at least one light-emitting element 23, the voltage detection units 71 to 73 reduce 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 emitted, compared to 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 38a 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 39a 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 to detect abnormalities in the multiple 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, so that the short-circuit abnormality can be detected by detecting the voltages of the first to third anode wirings 31 to 33.

[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) when it is determined that an abnormality occurs based on the detected voltage. The error signal output from the first to third voltage detection circuits 71 to 73 is sent to, for example, a control unit of the distance measuring device not shown in FIG. 11. Based on the error signal output from the first to third voltage detection circuits 71 to 73, the control unit instructs, for example, the abnormal light-emitting element 23 to stop emitting light, or instructs the light-receiving element 18 corresponding to the abnormal light-emitting element 23 to stop receiving light. As a result, when some light-emitting elements are abnormal, it is possible to stop emitting light from only the abnormal light-emitting element and stop receiving light from only the corresponding light-receiving element 18, and the distance measuring process can be continued using normal light-emitting elements and normal light-receiving elements 18, thereby 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 in at least one of the capacitors 34 to 36 connected to the light-emitting element 23 to be emitted, when an abnormality is detected in at least one light-emitting element 23. When an abnormality is detected in at least one light-emitting element 23, the charge adjustment unit makes 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 emitted smaller than the amount of charge charged before the abnormality was detected.

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

[0097] In the following, it is assumed that when a charging current from capacitor 34 is passed through light-emitting element 23a, which is the target for 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 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] Fig. 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 emitted 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 through the transistor (first switch) 37a to the capacitor 34 can be suppressed, and the amount of charge stored in the capacitor 34 can also be suppressed.

[0099] During the period from time t2 to t3, the transistor (first switch) 38a of the selection circuit 38 connected to the anode of the light emitting element 23c that is not to emit light is also turned on. Since the period from time t2 to t3 is short, the amount of charge stored in the capacitor 35 is also suppressed.

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

[0101] Since the amount of charge stored in the capacitors 34 and 35 is smaller than normal, the emission intensity of the light-emitting elements 23b and 23c becomes weaker than normal, and the 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 in the case where the first to third voltage detection circuits 71 to 73 do not control the current output from the selection circuits 37 to 39. When the current output from the selection circuits 37 to 39 is not controlled even though some of the light-emitting elements 23 have a short circuit abnormality, not only the light-emitting element 23b to be emitted, but also the light-emitting element 23c connected to the capacitor 35 that is charged due to the short circuit abnormality among the light-emitting elements 23 that are not to be emitted, emits light. In the case of FIG. 13, the period from time t2 to t3 is longer than the period from time t2 to t3 in FIG. 12. Therefore, in the case of FIG. 13, the amount of charge charged in the capacitors 34 and 35 becomes larger than in FIG. 12, and the light-emitting luminance of the light-emitting elements 23b and 23c becomes higher than in FIG. 12. As a result, there is a risk that light will be emitted at a light-emitting luminance that exceeds the safety standard 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, 35. For example, by shortening the charging period, it is possible to keep the emission brightness of light-emitting elements 23b, 23c low.

[0104] In this way, 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 luminance of the light-emitting elements 23 can be kept low. This makes it possible to prevent a problem in which the light emission luminance of the light-emitting elements 23 emits light at such a high light emission luminance that it exceeds the safety standard for laser light due to the influence of an abnormality in some of the light-emitting elements 23.

[0105] (Fourth embodiment) The light emitting device 1 of the fourth embodiment is configured to prevent multiple light emitting elements 23 located within the range of the human pupil 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 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, the light emitting elements 23b and 23c at other locations whose cathodes are not connected to the light emitting element 23z that has the short circuit are caused to emit light.

[0107] Fig. 15 shows an example in which the capacitor 35 connected to the anode of the light-emitting element 23z that has a short circuit abnormality is charged. In the example of Fig. 15, two light-emitting elements 23b and 23c that are located at light-emitting positions that do not simultaneously enter the human eye are selected as light-emitting elements. In this case, after the transistor (first switch) 37a of the selection circuit 37 connected to the anodes of the light-emitting elements 23b and 23c that are the light-emitting elements to be emitted is turned on to charge the capacitor 34, when the 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 light-emitting elements to be emitted are both turned on, a current from the capacitor 35 connected to the anodes of the non-light-emitting elements 23d and 23e whose cathodes are connected to the transistors 24b and 24c flows to the non-light-emitting elements 23d and 23e, causing them to emit light.

[0108] In this way, in the example of Fig. 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 received by the human eye, and the light-emitting elements 23c and 23e are also located within the range that would be received by the human eye. 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 of the human eye. Since each of the light-emitting groups has a light-emitting intensity that does not exceed the safety standard for laser light, safety is improved.

[0109] Fig. 16A is a diagram 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 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 normally perform light-emitting operations, as shown in Fig. 16A, only the light-emitting elements 23 at 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 at the intended light-emitting positions. On the other hand, when some of the light-emitting elements 23 have a short circuit abnormality, the light-emitting elements 23 at two locations that do not enter the human pupil are made to emit light to reduce the light emission intensity. Also, since the capacitor 35 connected to the anode of the light-emitting elements 23 that are not intended to emit light is charged, a total of four light-emitting elements 23 emit light, as shown in Fig. 16B.

[0111] When some of the light-emitting elements 23z have a short circuit, the light-receiving device receives reflected light from the subject with 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 from the timing of light reception by the two light-receiving groups. In other words, the light-receiving device can effectively use the light-receiving results by the two light-receiving groups to measure the distance to the subject.

[0112] In this way, in the fourth embodiment, when some of the light-emitting elements 23 suffer a short circuit abnormality, 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 since the discharge current of the same capacitor is passed through the multiple light-emitting elements 23 to emit light, the emission luminance can be weakened and the light can be made to emit light at a luminance that does not exceed the safety standard 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 flows not only to the light emitting element 23 that is the light emitting target 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 the light-emitting element 23a, the cathode of which is connected to the light-emitting element 23z, is to be made to 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 to charge 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 other than the drive circuit E to which the cathode of the light emitting element 23z that has caused the short circuit is connected. This allows the discharge current of the capacitor 34 to be dispersed, and the emission intensity of the light emitting element 23a to be weakened. In addition, the discharge current of the capacitor 35 is also passed to the light emitting element 23b and the other dummy light emitting element 23D. This allows the discharge current of the capacitor 35 to be dispersed, and the emission intensity of the light emitting element 23b to be weakened.

[0119] In this manner, 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. Therefore, when some of the light-emitting elements 23 suffer a short circuit abnormality, the discharge current of the capacitor 34 (35) can be made to flow not only to the light-emitting element 23 to be illuminated, but also to the dummy light-emitting element 23D, thereby weakening the light emission intensity of the light-emitting element 23 to be illuminated.

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

[0121] FIG. 18 is a circuit diagram of the light emitting device 1 according to the 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 the selection circuits, and a drive circuit E for driving 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 one 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 having a non-light emitting structure, as in the fifth embodiment.

[0122] FIG. 18 shows an example in which one of the light-emitting elements 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 section 50, which are connected to a drive circuit E other than the drive circuit E to which the cathode of the light-emitting element 23z that has a short circuit is connected. This allows the discharge current of the capacitor 34 to be dispersed, and the light emission intensity of the light-emitting element 23b to be emitted can be weakened. 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 allows the discharge current of the capacitor 35 to be dispersed, and the light emission intensity of the light-emitting element 23b can be weakened.

[0123] The non-light emitting regions 50a of the dummy light emitting elements 23D and the like do not necessarily have a similar structure to the light emitting elements 23. They may have any structure that allows a portion of the current that should be passed to 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 made of a resistive element 50b. A part 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 manner, in the sixth embodiment, since the non-light-emitting section 50 including the dummy light-emitting element 23D or the resistive element 50b shared by all the selection circuits 37 to 39 is provided, the configuration of the non-light-emitting section 50 can be simplified more than in the fifth embodiment.

[0126] In the above-mentioned first to sixth embodiments, when the light-emitting element 23z not to be emitted has a short circuit abnormality, 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 forcibly turned off. However, when all the 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 light-emitting element 23z not to be emitted may be forcibly turned off. This allows the capacitor 35 to which the anode of the light-emitting element 23z not to be emitted to be connected to continue to hold charge. The charge held in the capacitor 35 can be used, for example, to make a light-emitting element 23 other than the light-emitting element 23 to be originally emitted emit light. The charge held in the capacitor 35 may be discharged by turning on the transistor (second switch) 38b in the corresponding selection circuit immediately before the light-emitting element 23 to which the capacitor 35 is connected becomes the light-emitting element.

[0127] Seventh embodiment The light emitting device 1 according to the 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 device 1 according to the first to sixth embodiments is, for example, a surface emitting laser element. More specifically, the light emitting device 1 according to the first to sixth embodiments has, 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 a substrate 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 the laser light is emitted from the back surface S3 side of the substrate 21. The laminated film 22 includes a first multilayer reflector, a first spacer layer, an active layer, a second spacer layer, and a second multilayer reflector, and the laser light generated in the active layer is resonated between the first multilayer reflector and the second multilayer reflector to improve the light intensity and is emitted from the back surface S3 side of the substrate. Thus, the LD chip 46 in FIG. 20 is a back-illuminated type. In this specification, the light emitting element 23 having the layer structure as shown in FIG. 20 is called 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. When 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, when viewed from the substrate 21 side, a cathode electrode 48 is disposed on the upper surface and side surface of the laminated film 22 disposed on the end side of the LD chip 46. When viewed from the substrate 21 side, the cathode electrode 48 is also disposed on the lowermost layer side 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 disposed in reverse. In FIG. 20, the common electrode is the cathode electrode 48, but the common electrode may be the anode electrode 47 and the 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 to each other 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 drive. Alternatively, the LDD substrate 45 may supply a voltage corresponding to a drive signal generated by an external drive circuit to the pad 21. In this case, the LDD substrate 45 performs passive drive.

[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 front surface S2 of the substrate 21 as a 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 front surface S2 to the back surface S3 of the substrate 21. In this manner, the LD chip 11 of this embodiment is a back-emission type 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 showing a schematic difference in structure between the light-emitting element 23 and the dummy light-emitting element 23D. Fig. 21 shows the structure of a mesa portion 20 of a VCSEL structure. The left side of Fig. 21 shows the mesa portion 20 functioning as the light-emitting element 23, and the right side shows the mesa portion 20 functioning as the dummy light-emitting element 23D. The upper surface of the mesa portion 20 in Fig. 21 is the light emission surface. A ring-shaped electrode 62 is disposed on the light emission surface side of the mesa portion 20 of the light-emitting element 23, and a light emission portion 60 is provided inside the electrode 62.

[0138] In contrast, in the mesa portion 20 of the dummy light-emitting element 23D, an electrode is provided over the entire light-emitting surface. The electrode is made of a material that does not transmit light, such as tungsten. As a result, the dummy light-emitting element 23D does not emit light, and a non-light-emitting region 50a is realized.

[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 laminated 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 laminated 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] Fig. 23 is a perspective view that typically shows a light emitting element 23 and a dummy light emitting element 23D having a structure different from that shown in Fig. 21. Fig. 23 shows the surface of the mesa portion 20 opposite to the light emission surface on the upper side. An n-DBR layer 25 is disposed on the surface of the mesa portion 20 opposite to the light emission surface. By removing at least a portion of the n-DBR layer 25, the amount of light reflected from the n-DBR layer 25 to the p-DBR layer 61 side 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 emission 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 manner, the resistance value of the non-light emitting portion 50 can be varied by adjusting the size of the mesa portion 20 of the dummy light emitting element 23D.

[0144] In this way, in the seventh embodiment, when the light emitting device 1 according to the first to sixth embodiments has 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 at any location by utilizing the manufacturing process of the VCSEL.

[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) 40 that measures the distance to an object in a non-contact manner. The distance measuring device 40 requires a light receiving device 41 that receives the reflected light signal from the light emitting device 1 that is reflected by the object. The light emitting device 1 and the light receiving device 41 may be disposed separately or on a common support member 42.

[0146] 25 is a cross-sectional view of a ToF sensor 43 in which a light emitting device 1 and a light receiving device 41 are arranged on the same support member 42. As shown in FIG. 25, the light emitting device 1 and the light receiving device 41 are mounted on a common mounting substrate 13.

[0147] 25 includes an LD (Laser Diode) chip 11 including the above-mentioned light emitting unit 2, an LDD (Laser Diode Driver) substrate 12 including the above-mentioned driving unit 3, a mounting substrate 13, a heat dissipation substrate 14, a correction lens holding portion 15, one or more correction 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 section and a signal processing section may be further 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 part 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. The light emitted from the light-emitting part 2 in the LD chip 11 is corrected by these correction lenses 16, and then irradiated onto the above-mentioned subject S. FIG. 25 shows two correction lenses 16 held by the correction lens holding part 15 as an example.

[0151] The wiring 17 is provided on the front, back, inside, etc. 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 surface of the mounting substrate 13, or a via wiring penetrating the mounting substrate 13. The wiring 17 of this embodiment further passes 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 mounting the light emitting device 1 according to this embodiment.

[0153] As shown in the figure, the distance measuring device 40 includes a light emitting unit 51, a driving unit 52, a power supply circuit 53, a light emitting side optical system 54, a light receiving side optical system 55, a light receiving unit 56, a signal processing unit 57, a control unit 58, and a temperature detection unit 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-mentioned light emitting device 1. As described later, the light emitting unit 51 in this example has light emitting elements 23 using VCSELs (Vertical Cavity Surface Emitting LASERs) as the respective light sources, and the light emitting elements 23 are arranged in a predetermined manner, such as in 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, described later) for the driving unit 52 based on an input voltage (an input voltage Vin, 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 as a distance measurement target via a light-emitting side optical system 54. Then, the light thus irradiated is reflected from the subject S and enters a light-receiving surface of a 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, which receives reflected light from the subject S incident via the light receiving side optical system 55 as described above, converts the light into an electrical signal, and outputs it. The light receiving unit 56 and the light receiving side optical system 55 correspond to the light receiving device 41 shown in FIG.

[0158] The light receiving unit 56 performs, for example, CDS (Correlated Double Sampling) processing, AGC (Automatic Gain Control) processing, etc., on the electrical signal obtained by photoelectrically converting the received light, and further performs A / D (Analog / Digital) conversion processing. Then, the signal is output as digital data to the signal processing unit 57 at the downstream side.

[0159] Further, 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), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., or an information processing device such as a DSP, and controls the drive unit 52 for controlling the light emission operation by the light emitter 51, and controls the light receiving operation by the light receiver 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 enable identification of the three-dimensional shape of the subject S.

[0163] A specific distance measurement method used by distance measuring device 40 will be described later.

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

[0165] In this example, information on 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] (Distance measurement method) The distance measuring method used by the distance measuring 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, a pattern light Lp having a dot pattern as 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 prevented from overlapping between blocks B).

[0169] FIG. 27B is a diagram illustrating the distance measurement principle of the STL method.

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

[0171] In addition, in the drawing, “BLn” 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 section 56.

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

[0173] The STL method uses the fact that the irradiated pattern is distorted by the object shape of the subject S to determine the shape and depth of the subject S. Specifically, this method determines the shape and depth of the subject S from the way the pattern is distorted.

[0174] When the STL method is adopted, for example, an IR (Infrared) light receiving unit using a global shutter method is used as the light receiving unit 56. In the case of the STL method, 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 way the pattern is distorted.

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

[0176] When a 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 when light is emitted from the light emitting unit 51 and when it is 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 a 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] (Example of application to moving objects) 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 moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, etc.

[0179] FIG. 28 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a moving 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, as functional configurations of the integrated control unit 12050, a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

[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 mounted on 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 head lamps, back lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals of various switches transmitted from a portable device that replaces a key may be input to the body system control unit 12020. The body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, and the like of the vehicle.

[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 an image outside the vehicle, and receives the captured image. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for a person, a car, an obstacle, a sign, or characters on a road surface, based on the received image.

[0184] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according 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.

[0186] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the outside-of-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output a control command 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 the driver's operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired 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-vehicle 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-vehicle information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

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

[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 an imaging unit 12031.

[0192] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The images of the front acquired by the imaging units 12101 and 12105 are mainly used to detect a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

[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, an overhead image of the vehicle 12100 viewed from above is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

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

[0195] For example, the microcomputer 12051 can extract, as a preceding vehicle, a three-dimensional object that is the closest three-dimensional object on the travel path of the vehicle 12100 and travels at a predetermined speed (for example, 0 km / h or more) in approximately the same direction as the vehicle 12100, by calculating the distance to each three-dimensional object in the imaging ranges 12111 to 12114 and the change over time of this distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104. Furthermore, the microcomputer 12051 can set a vehicle distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of automatic driving that travels autonomously without relying on the driver's operation.

[0196] For example, the microcomputer 12051 classifies and extracts three-dimensional object data on 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. Then, the microcomputer 12051 determines a collision risk indicating 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 imaging 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 or not a pedestrian is present in the captured images of the imaging units 12101 to 12104. The recognition of such a pedestrian is performed, for example, by a procedure of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras, and a procedure of performing pattern matching processing on a series of feature points that indicate the contour of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

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

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

[0200] (1) a plurality of light-emitting elements arranged in a two-dimensional array, each of the light-emitting elements having a first terminal and a second terminal; a plurality of first terminal wirings including 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, 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 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 configured to select the light emitting element to be a light emitting target; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and configured to drive the plurality of light-emitting elements; a plurality of capacitors electrically connected to the one of the first and second terminal wirings and configured to store electric charges to be supplied to the plurality of light-emitting elements; Each of the plurality of selection circuits a first switch that switches whether or not a corresponding capacitor among the plurality of capacitors is charged; a second switch for switching whether or not the charge in the corresponding capacitor is discharged; The selection circuit connected to the light emitting element not to emit light selects whether to keep the charge held in the corresponding capacitor or to discharge the charge by switching and controlling the second switch. Light emitting device. (2) the selection circuit connected to the light-emitting element not to be emitted 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 not to be emitted are short-circuited; The light-emitting device according to (1). (3) the selection circuit connected to the light emitting element not to emit light turns off the second switch and keeps the corresponding capacitor holding the charge when the light emitting element not to emit light operates normally; The light-emitting device according to (1). (4) a plurality of third switches are disposed between the plurality of capacitors and the plurality of light-emitting elements, and the third switches switch whether or not the electric charges of the plurality of capacitors are discharged; A discharge current from the capacitor connected to the light emitting element that is not a light emitting element flows to a reference voltage node through the corresponding third switch without flowing to the light emitting element that is not a light emitting element. The light-emitting device according to (1). (5) 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. (4) A light-emitting device according to the present invention. (6) A wiring length between each of the plurality of capacitors and the corresponding third switch is shorter than a wiring length between each of the plurality of capacitors and the corresponding light-emitting element. A light-emitting device according to (4) or (5). (7) the third switch connected to the light emitting element that is not a light emitting element is turned on in synchronization with a timing at which the light emitting element that is a light emitting element is driven, and a discharge current is caused to flow from the capacitor connected to the light emitting element that is not a light emitting element to a reference voltage node; A light emitting device according to any one of (4) to (6). (8) When an abnormality occurs in which the anode and the cathode of the non-light emitting element are short-circuited, the third switch connected to the non-light emitting element is turned on, and a discharge current of the capacitor connected to the non-light emitting element is caused to flow to a reference voltage node instead of to the non-light emitting element. A light emitting device according to any one of (4) to (7). (9) A charge adjusting unit adjusts an amount of charge to be charged in at least one of the capacitors connected to the light emitting element to be illuminated when an abnormality in at least one of the light emitting elements is detected. A light emitting device according to any one of (1) to (8). (10) 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 the abnormality is detected and the amount of charge charged in the capacitor connected to the light-emitting element to be emitted, compared to the amount of charge charged before the abnormality is detected. The light emitting device according to (9). (11) When an abnormality is detected in at least one of the light-emitting elements, the selection circuits select a light-emitting element connected to the drive circuit other than the abnormal light-emitting element as a new light-emitting target. A light emitting device according to any one of (1) to (7). (12) An abnormality detection unit that detects an abnormality in at least one of the light-emitting elements, the plurality of selection circuits select, as a light emitting element to be emitted, a light emitting element connected to the drive circuit different from a light emitting element in which an abnormality has been detected by the abnormality detection unit; The abnormality detection unit outputs an abnormality detection signal to the outside. The light emitting device according to (11). (13) When an abnormality in at least one of the light-emitting elements is detected, the selection circuits select, from among the light-emitting elements, two or more light-emitting elements that are arranged in a position that is not simultaneously incident on a human eye, as light-emitting elements. The light-emitting device according to (11) or (12). (14) A non-light-emitting portion capable of passing a part of a discharge current of the capacitor connected to the light-emitting element to be emitted, When an abnormality in at least one of the light-emitting elements is detected, a discharge current of the capacitor connected to the light-emitting element to be emitted flows in a distributed manner to the light-emitting element to be emitted and the non-light-emitting portion. A light emitting device according to any one of (1) to (7). (15) The non-light emitting portion has a plurality of non-light emitting regions provided corresponding to the plurality of light emitting elements, When an abnormality of at least one of the light-emitting elements is detected, a discharge current of the capacitor connected to the light-emitting element to be emitted flows in a distributed manner to 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 element to be emitted. The light-emitting device according to (14). (16) The non-light emitting portion has non-light emitting regions whose number is less than the number of the light emitting elements, When an abnormality in at least one of the light-emitting elements is detected, a discharge current of the capacitor connected to the light-emitting element to be emitted flows in a distributed manner to the non-light-emitting areas, the number of which is less than the total number of the light-emitting elements to be emitted, and the light-emitting elements to be emitted. The light-emitting device according to (14). (17) 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. A light-emitting device according to (15) or (16). (18) The plurality of light-emitting elements are VCSELs (Vertical Cavity Surface Emitting Lasers) or other types of surface-emitting laser elements. A light emitting device according to any one of (1) to (17). (19) The VCSEL has a plurality of mesas each emitting a laser beam, Some of the mesa portions have a non-light-emitting structure. The light-emitting device according to (18). (20) A light emitting unit that emits light toward a subject; a light receiving unit that receives light that is emitted and reflected by the subject; 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; Equipped with The light emitting unit is A plurality of light emitting elements arranged in a two-dimensional array, each having a first terminal and a second terminal; a plurality of first terminal wirings including 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, 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 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 configured to select the light emitting element to be a light emitting target; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and configured to drive the plurality of light-emitting elements; a plurality of capacitors electrically connected to the one of the first and second terminal wirings and configured to store electric charges to be supplied to the plurality of light-emitting elements; Each of the plurality of selection circuits a first switch that switches whether or not a corresponding capacitor among the plurality of capacitors is charged; a second switch for switching whether or not the charge in the corresponding capacitor is discharged; The selection circuit connected to the non-target light-emitting element controls switching of the second switch when an abnormality is detected in the non-target light-emitting element. Ranging device.

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

[0202] REFERENCE SIGNS LIST 1 light emitting device, 2 light emitting section, 3 driving section, 5 light emitting optical system, 11 chip, 12 substrate, 13 mounting substrate, 14 heat dissipation substrate, 15 correction lens holding section, 16 correction lens, 17 wiring, 20 mesa section, 21 substrate, 22 laminated film, 23 light emitting element, 23a light emitting element, 23b light emitting element, 23c light emitting element, 23d light emitting element, 23D dummy light emitting element, 23e light emitting element, 23z light emitting element, 24 transistor, 24a first transistor, 24b second transistor, 24c transistor, 26 cladding layer, 27 active layer, 28 cladding layer, 29 narrowing layer, 29a oxidation region, 29b non-oxidization region, 30 third switch, 30B bypass path, 31 first anode wiring, 31a first horizontal wiring, 31b second 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 capacitor, 35 capacitor, 36 third capacitor, 37 selection circuit, 37a transistor (first switch), 37b transistor (second switch), 38 selection circuit, 38a transistor (first switch), 38b transistor (second switch), 39 selection circuit, 39a transistor, 39b transistor, 40 distance measuring device, 41 light receiving device, 42 gate wiring, 43 sensor, 45 substrate, 46 (Laser Diode) chip, 46 chip, 47 anode electrode, 48 cathode electrode, 49 pad, 50 non-light emitting portion, 50a non-light emitting area, 50b resistor element, 51 light emitting portion, 52 drive portion, 53 power supply circuit, 54 Light emitting optical system, 55 light receiving optical system, 56 light receiving section, 57 signal processing section, 58 control section, 58a distance measuring section, 58a distance measuring section of this example, 59 temperature detection section, 60 light emitting section on the inside, 62 electrode, 63 bonding layer, 71 first voltage detection circuit, 72 second voltage detection circuit, 73 third voltage detection circuit

Claims

1. A plurality of light emitting elements arranged in a two-dimensional array, each having a first and a second terminal; a plurality of first terminal wirings including 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, and 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 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 configured to select the light emitting element to be a light emitting target; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and configured to drive the plurality of light-emitting elements; a plurality of capacitors electrically connected to the one of the first and second terminal wirings and configured to store electric charges to be supplied to the plurality of light-emitting elements; Each of the plurality of selection circuits a first switch that switches whether or not a corresponding capacitor among the plurality of capacitors is charged; a second switch for switching whether or not the charge of the corresponding capacitor is discharged; The selection circuit connected to the light emitting element not to emit light selects whether to keep the charge held in the corresponding capacitor or to discharge the charge by controlling the switching of the second switch. Light emitting device.

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

3. the selection circuit connected to the light emitting element not to emit light turns off the second switch and keeps the corresponding capacitor holding the charge when the light emitting element not to emit light operates normally; The light emitting device according to claim 1 .

4. a plurality of third switches disposed between the plurality of capacitors and the plurality of light-emitting elements, the third switches switching between whether or not to discharge the charges of the plurality of capacitors; A discharge current from the capacitor connected to the light emitting element that is not a light emitting element flows to a reference voltage node through the corresponding third switch without flowing to the light emitting element that is not a light emitting element. The light emitting device according to claim 1 .

5. 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; The light emitting device according to claim 4.

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

7. 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; The light emitting device according to claim 4.

8. When an abnormality occurs in which the anode and the cathode of the light-emitting element that is not a light-emitting target are short-circuited, the third switch connected to the light-emitting element that is not a light-emitting target is turned on, and a discharge current of the capacitor connected to the light-emitting element that is not a light-emitting target is caused to flow to a reference voltage node without flowing to the light-emitting element that is not a light-emitting target. The light emitting device according to claim 4.

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

10. 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 the abnormality is detected and the amount of charge charged in the capacitor connected to the light-emitting element to be emitted, compared to the amount of charge charged before the abnormality is detected.

10. The light emitting device according to claim 9.

11. 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, a light-emitting element connected to the drive circuit other than the abnormal light-emitting element. The light emitting device according to claim 1 .

12. an abnormality detection unit that detects an abnormality in at least one of the light-emitting elements; the plurality of selection circuits select, as a light emitting element to be emitted, a light emitting element connected to the drive circuit different from a light emitting element in which an abnormality has been detected by the abnormality detection unit; The abnormality detection unit outputs an abnormality detection signal to the outside.

12. The light emitting device according to claim 11.

13. When an abnormality in at least one of the light-emitting elements is detected, the selection circuits select, from among the light-emitting elements, two or more light-emitting elements that are arranged in a position that is not simultaneously incident on a human eye, as light-emitting targets.

12. The light emitting device according to claim 11.

14. a non-light-emitting portion capable of passing a part of a discharge current of the capacitor connected to the light-emitting element to be emitted; When an abnormality in at least one of the light-emitting elements is detected, a discharge current of the capacitor connected to the light-emitting element to be emitted flows in a distributed manner to the light-emitting element to be emitted and the non-light-emitting portion. The light emitting device according to claim 1 .

15. the non-light emitting portion has a plurality of non-light emitting regions provided corresponding to the plurality of light emitting elements, When an abnormality of at least one of the light-emitting elements is detected, a discharge current of the capacitor connected to the light-emitting element to be emitted flows in a distributed manner to the non-light-emitting regions having the same number as the light-emitting elements to be emitted and the light-emitting elements to be emitted.

15. The light emitting device according to claim 14.

16. the non-light emitting portion has non-light emitting regions whose number is less than the number of the light emitting elements, When an abnormality in at least one of the light-emitting elements is detected, a discharge current of the capacitor connected to the light-emitting element to be emitted flows in a distributed manner to the non-light-emitting areas, the number of which is less than the total number of the light-emitting elements to be emitted, and the light-emitting elements to be emitted.

15. The light emitting device according to claim 14.

17. 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.

16. The light emitting device according to claim 15.

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

19. The VCSEL has a plurality of mesas each of which emits laser light; Some of the mesa portions have a non-light-emitting structure.

20. The light emitting device of claim 18.

20. A light emitting unit that emits light toward a subject; a light receiving unit that receives light that is emitted and reflected by the subject; 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; Equipped with 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; a plurality of first terminal wirings including 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, and 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 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 configured to select the light emitting element to be a light emitting target; a plurality of drive circuits electrically connected to the other of the first and second terminal wirings and configured to drive the plurality of light-emitting elements; a plurality of capacitors electrically connected to the one of the first and second terminal wirings and configured to store electric charges to be supplied to the plurality of light-emitting elements; Each of the plurality of selection circuits a first switch that switches whether or not a corresponding capacitor among the plurality of capacitors is charged; a second switch for switching whether or not the charge of the corresponding capacitor is discharged; the selection circuit connected to the non-target light-emitting element controls switching of the second switch when an abnormality is detected in the non-target light-emitting element; Ranging device.

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