Light-emitting device, light-emitting apparatus, and measuring apparatus

Abstract

The invention provides a light-emitting device, a light-emitting apparatus, and a measuring apparatus. A light-emitting device is provided with: a plurality of light-emitting blocks each including a light-emitting element and a setting element that sets the light-emitting element to a state in which the light-emitting element can be turned on; and a discharge path including a discharge element capable of controlling discharge when the light-emitting element is turned off, the discharge path discharging the stored charge when the light-emitting element is turned on, and the plurality of light-emitting blocks are electrically connected in parallel with the discharge path.

Description

Technical Field

[0001] The present invention relates to a light-emitting device, a light-emitting apparatus, and a measuring device. Background Art

[0002] In Patent Document 1, there is described a light-emitting apparatus including: a light-emitting unit including a light-emitting element; a driving unit including a first element connected to a cathode electrode provided on the cathode side of the light-emitting element, and supplying a current for generating light to drive the light-emitting element; and a capacitor unit provided in parallel with a current path for generating light between an anode electrode provided on the anode side of the light-emitting element and the cathode electrode.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-112924

[0004] In recent years, as a distance measurement sensor for object recognition and the like, a ToF (Time of Flight) sensor has become mainstream, and a light-emitting device integrating a light-emitting element such as a vertical cavity surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser) is used as a light source thereof.

[0005] The ToF sensor for application programs of mobile devices such as smartphones is required to achieve both high spatial resolution and power saving. The light-emitting element as a light source is required to have a rise time / fall time of less than 1 ns. If the light source has a block including a plurality of light-emitting elements and block illumination for lighting the selected block is provided, power saving can be achieved compared with the case of lighting all the light-emitting elements at the same time. In block illumination, the unselected blocks form a capacitor and accumulate charges. Due to the discharge of the charges, the fall time of the light-emitting element becomes longer. Summary of the Invention

[0006] An object of the present invention is to provide a light-emitting device and the like in which the fall time of a light-emitting element is shorter than in the case of not having a discharge path.

[0007] The invention according to Scheme 1 is a light-emitting device including: a plurality of light-emitting blocks each including a light-emitting element and a setting element for setting the light-emitting element in a state where it can be lit; and a discharge path including a discharge element capable of controlling discharge when the light-emitting element is extinguished and discharging the accumulated charges when lit, and the plurality of light-emitting blocks are electrically connected in parallel with the discharge path.

[0008] The invention according to Scheme 2 is the light-emitting device according to Scheme 1, wherein the discharge element is a thyristor.

[0009] The invention according to Embodiment 3 is the light-emitting device according to Embodiment 2, wherein the discharge path is constituted by a thyristor, i.e., the discharge element. In the light-emitting block, the light-emitting element is a surface-emitting laser, and the setting element is a thyristor. The discharge path is electrically connected in parallel with respect to the series connection of the light-emitting element and the setting element.

[0010] The invention according to Embodiment 4 is the light-emitting device according to Embodiment 3, wherein the thyristor serving as the setting element and the thyristor serving as the discharge element have laminated semiconductor layers with the same structure.

[0011] The invention according to Embodiment 5 is the light-emitting device according to Embodiment 2, wherein the discharge path is constituted by the series connection of the discharge element and a pseudo surface-emitting laser. In the light-emitting block, the light-emitting element is a surface-emitting laser, and the setting element is a thyristor. The discharge path is electrically connected in parallel with respect to the series connection of the light-emitting element and the setting element.

[0012] The invention according to Embodiment 6 is the light-emitting device according to Embodiment 5, wherein the thyristor serving as the setting element and the thyristor serving as the discharge element have laminated semiconductor layers with the same structure, and the surface-emitting laser serving as the light-emitting element and the pseudo surface-emitting laser have laminated semiconductor layers with the same structure.

[0013] The invention according to Embodiment 7 is a light-emitting device including: the light-emitting device according to any one of Embodiments 1 to 6; a driver connected to the light-emitting device and supplying a lighting current to the light-emitting element of the light-emitting device; a selection unit that selects the light-emitting block to be lit in the light-emitting device and supplies a selection signal to the setting element of the selected light-emitting block; a lighting control unit that supplies a lighting control signal for controlling the lighting period of the light-emitting element in the light-emitting device to the driver; and a discharge control unit that supplies a discharge control signal for controlling discharge to the light-emitting device.

[0014] The invention according to Embodiment 8 is the light-emitting device according to Embodiment 7, wherein the discharge control signal starts to become a signal voltage for turning on the discharge element when the lighting control signal becomes a signal voltage for turning off the driver.

[0015] The invention according to Embodiment 9 is the light-emitting device according to Embodiment 7 or 8, wherein the width of the signal for turning on the discharge element in the discharge control signal is smaller than the width of the signal for turning on the driver in the lighting control signal.

[0016] The invention according to Embodiment 10 is the light-emitting device according to any one of Embodiments 7 to 9, wherein the power supply voltage supplied to the light-emitting device is the same as the power supply voltage supplied to the discharge control unit.

[0017] The invention according to Embodiment 11 is the light-emitting device according to any one of Embodiments 7 to 10, which includes an adjustment unit that adjusts the timing of the signal for turning on the discharge element in the discharge control signal transmitted by the discharge control unit according to the timing of turning off the driver in the lighting control signal and the number of the lit light-emitting blocks.

[0018] The invention according to Embodiment 12 is a measuring device, which includes: the light-emitting device according to any one of Embodiments 7 to 11; and a light-receiving unit that receives the light emitted by the light-emitting device and reflected from the object to be measured, and the measuring device measures the three-dimensional shape of the object to be measured.

[0019] Advantages of the Invention

[0020] According to the first aspect of the present invention, compared with the case where there is no discharge path, the fall time of the light-emitting element can be shortened.

[0021] According to the second aspect of the present invention, compared with the case where it is not a thyristor, the switching is faster.

[0022] According to the third aspect of the present invention, compared with the case where the discharge path includes other elements in addition to the thyristor, the parasitic resistance can be reduced.

[0023] According to the fourth aspect of the present invention, compared with the case where the multilayer semiconductor layers do not have the same structure, the manufacturing of the light-emitting device becomes easier.

[0024] According to the fifth aspect of the present invention, compared with the case where the discharge element is not connected in series with the pseudo surface-emitting laser, the discharge path can be made to have the same structure as the light-emitting block.

[0025] According to the sixth aspect of the present invention, compared with the case where the multilayer semiconductor layers do not have the same structure, the manufacturing of the light-emitting device becomes easier.

[0026] According to the seventh aspect of the present invention, a light-emitting device capable of performing block irradiation can be realized.

[0027] According to the eighth aspect of the present invention, compared with the case where the discharge control signal becomes the signal voltage for turning on the discharge element when the lighting control signal is the signal voltage for turning on the driver, the power consumption can be reduced.

[0028] According to the ninth aspect of the present invention, compared with the case where the width of the signal for turning on the discharge element is greater than the width of the signal for turning on the driver, the power consumption can be reduced.

[0029] According to the tenth aspect of the present invention, compared with the case where the power supply voltages are different, the structure can be made simpler.

[0030] According to the 11th aspect of the present invention, the decay timing of the light emission of the light-emitting element can be controlled regardless of the number of light-emitting blocks that are lit, as compared with the case where no adjustment is made.

[0031] According to the 12th aspect of the present invention, a measurement device based on a three-dimensional shape can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0033] Figure 1 is a block diagram showing a schematic configuration of a measurement device for measuring the three-dimensional shape and the like of a measurement object by the ToF method to which the first embodiment is applied;

[0034] Figure 2 is a diagram illustrating an example of the planar shape of a light-emitting device to which the first embodiment is applied;

[0035] Figure 3 is a cross-sectional view illustrating an example of the cross-sectional structure of a light-emitting device to which the first embodiment is applied;

[0036] Figure 4 is an equivalent circuit of a light-emitting device to which the first embodiment is applied;

[0037] Figure 5 is an equivalent circuit of a light-emitting device that does not have a discharge thyristor and to which the first embodiment is not applied. (a) is an equivalent circuit showing 24 light-emitting blocks, and (b) is an equivalent circuit in which one light-emitting block is lit and the other light-emitting blocks are in an extinguished state;

[0038] Figure 6 is an equivalent circuit for explaining the influence of a parallel capacitor. (a) is a light-emitting device having one light-emitting block, and (b) is a light-emitting device having 24 light-emitting blocks;

[0039] Figure 7 is a result of simulating the current flowing in the VCSEL by the equivalent circuit for explaining the influence of the parallel capacitor;

[0040] Figure 8 is an equivalent circuit of a light-emitting device having a discharge thyristor and to which the first embodiment is applied;

[0041] Figure 9 is a timing chart showing the lighting control signal and the discharge control signal used in the simulation. (a) shows the lighting control signal, and (b) shows the discharge control signal;

[0042] Figure 10This is the result of simulating the current flowing through the VCSEL in a light-emitting device using a light-emitting device with a discharge thyristor to which the first embodiment is applied;

[0043] Figure 11 This is an equivalent circuit of a light-emitting device (comparative example) having a switch;

[0044] Figure 12 This is the result of simulating the current flowing through the VCSEL in a light-emitting device (embodiment) using a light-emitting device with a discharge thyristor and a light-emitting device (comparative example) having a switch;

[0045] Figure 13 This is a cross-sectional view illustrating the cross-sectional shape of a light-emitting device to which the second embodiment is applied;

[0046] Figure 14 This is an equivalent circuit of a light-emitting device using a light-emitting device to which the second embodiment is applied.

[0047] Symbol Explanation

[0048] 1, 1A, 1B, 1C, 2 - Light-emitting device, 7 - Three-dimensional sensor (3D sensor), 8 - Control unit, 9 - Three-dimensional shape measurement unit, 10, 10A, 10B, 20 - Light-emitting device, 11 (11-1, 11-2 to 11-24) - Light-emitting block, 12 - Selection signal pad, 13 - Anode pad, 14 - Discharge signal pad, 15 - Cathode pad, 17, 18, 19 - Discharge path, 41 - Cathode electrode, 42 - Anode electrode, 50 - Driver, 51, 71 - n-channel MOS transistor (nMOS transistor), 60 - Lighting control unit, 70 - Discharge control unit, 80 - Adjustment unit, 90 - Selection unit, C1 - Parallel capacitor, L1, L2, L3 - Parasitic inductance, P-VCSEL - Pseudo vertical cavity surface emitting laser, R1, R2, R3, R4, R5 - Resistor, S - Set thyristor, VCSEL - Vertical cavity surface emitting laser, VLD - Power supply, Power supply voltage, Z - Discharge thyristor. Detailed Embodiment

[0049] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, components having the same function are sometimes denoted by the same reference numerals. Also, reference numerals are attached to some structures, and the same structures are sometimes not denoted by reference numerals.

[0050] A ToF sensor for object recognition and the like is an example of a measuring device that measures the three-dimensional shape of a measurement object based on the distance to the measurement object measured by the ToF method. Hereinafter, the ToF sensor will be described as a measuring device. A measuring device that measures a three-dimensional shape or the like by the TOF method measures the distance to the measurement object based on the time from the timing when light is emitted from a light-emitting device provided in the measuring device until the emitted light is reflected by the measurement object and received by a three-dimensional sensor (hereinafter, sometimes referred to as a "3D sensor") provided in the measuring device, and measures the three-dimensional shape. In addition, the 3D sensor is an example of a light-receiving unit.

[0051] In the ToF method, there are an indirect ToF (iToF: indirect ToF) method that measures the time based on the difference in the phase of the emitted light and the phase of the received light, and a direct ToF (dToF: direct ToF) method that directly measures the time from the emission of light to the reception of light. In the ToF method, it is required that the rise / fall of the emitted light is steep, in other words, the rise time / fall time is short. In particular, compared with the indirect ToF method, the direct ToF method requires a shorter rise time / fall time. Here, the direct ToF method and the indirect ToF method are not distinguished and are described as the ToF method.

[0052] The three-dimensional shape of the measurement object is sometimes referred to as a "three-dimensional image" or a "3D shape". Also, measuring the three-dimensional shape is sometimes referred to as "three-dimensional measurement", "3D measurement", or "3D sensing".

[0053] Hereinafter, the structures, functions, methods, etc. described as embodiments of the present invention can be applied to face recognition, augmented reality (AR), or other three-dimensional measurements in information processing devices such as mobile devices.

[0054] In addition, the structures, functions, methods, etc. described as embodiments of the present invention can be used not only for three-dimensional measurement but also for measuring only the distance to the measurement object.

[0055] [First Embodiment]

[0056] (Measuring Device 100)

[0057] Figure 1FIG. 0 is a block diagram showing a schematic configuration of a measurement device 100 that measures the three-dimensional shape and the like of a measurement object by the ToF method according to the first embodiment. The measurement device 100 includes a light-emitting device 1 and a 3D sensor 7. The measurement device 100 may include a control unit 8 that controls the light-emitting device 1 and the 3D sensor 7. Further, the measurement device 100 may include a three-dimensional shape measurement unit 9 that measures the three-dimensional shape and the like of the measurement object based on the distance to the measurement object.

[0058] The light-emitting device 1 includes a light-emitting element 10, a driver 50, a lighting control unit 60, a discharge control unit 70, an adjustment unit 80, and a selection unit 90.

[0059] As described later, the light-emitting element 10 includes a plurality of light-emitting blocks 11. The light-emitting block 11 includes a light-emitting element. Hereinafter, the light-emitting element will be described as a vertical cavity surface emitting laser (VCSEL). The vertical cavity surface emitting laser will be expressed as VCSEL. Here, one light-emitting point (or light spot) will be expressed as VCSEL. The light-emitting block 11 is configured to include at least one VCSEL (refer to Figure 2 described later). In the case where the light-emitting block 11 includes a plurality of light-emitting points, the plurality of light-emitting points may be collectively referred to as a multi-light spot VCSEL. The vertical cavity surface emitting laser (VCSEL) is an example of a light-emitting element and an example of a surface emitting laser.

[0060] When the driver 50 changes from off to on, it supplies current to turn on the VCSEL of the light-emitting block 11. When the driver 50 changes from on to off, it blocks the current to turn off the VCSEL of the light-emitting block 11. The period during which the driver 50 is on is the lighting period.

[0061] The lighting control unit 60 supplies a signal for controlling the on / off of the driver 50 to the driver 50. Hereinafter, the signal for controlling the on / off of the driver 50 will be expressed as a lighting control signal.

[0062] The discharge control unit 70 supplies a signal for controlling the discharge of the accumulated charge when the light-emitting block 11 is lit to the light-emitting element 10. Hereinafter, the signal for controlling the discharge will be expressed as a discharge control signal.

[0063] The adjustment unit 80 adjusts the timing of supplying the signal for starting the discharge in the discharge control signal according to the timing of turning off the light-emitting block 11 in the lighting control signal and the number of the lit light-emitting blocks 11.

[0064] The selection unit 90 selects the light-emitting block 11 to be lit from the plurality of light-emitting blocks 11, and supplies a signal for setting the VCSEL of the selected light-emitting block 11 to a state where it can be lit to the selected light-emitting element 10. Hereinafter, the signal for setting the VCSEL of the selected light-emitting block 11 to a state where it can be lit will be expressed as a selection signal.

[0065] The control unit 8 controls the light-emitting device 1 and the 3D sensor 7. The control by the control unit 8 may include a function of measuring the distance to the measurement object according to the time measured by the 3D sensor 7. The three-dimensional shape measurement unit 9 acquires the distance from the control unit 8 to the measurement object and measures the three-dimensional shape of the measurement object.

[0066] The control unit 8 is configured as a computer including, for example, a CPU, a ROM, and a RAM. The ROM includes a non-volatile rewritable memory, such as a flash memory. Further, the program stored in the ROM is expanded into the RAM, and the CPU executes the program to control the light-emitting device 1 and the 3D sensor 7.

[0067] In Figure 1 , the control unit 8 is provided outside the light-emitting device 1. Any one or each of the lighting control unit 60, the discharge control unit 70, the adjustment unit 80, and the selection unit 90 may be configured in the same manner as the control unit 8. Further, the control unit 8 may include any one or all of the lighting control unit 60, the discharge control unit 70, the adjustment unit 80, and the selection unit 90.

[0068] The three-dimensional shape measurement unit 9 is configured in the same manner as the control unit 8 and measures the three-dimensional shape of the measurement object according to the distance to the measurement object. The control unit 8 may have the function of the three-dimensional shape measurement unit 9.

[0069] (Planar shape of the light-emitting device 10)

[0070] Figure 2 is a diagram showing an example of the planar shape of the light-emitting device 10 to which the first embodiment is applied. The horizontal direction of the paper surface is defined as the x direction, the upward direction of the paper surface is defined as the y direction, and the surface direction of the paper surface is defined as the z direction. The planar shape refers to the shape on the surface side of the substrate 30 described later (the shape on the x-y plane), and the cross-sectional shape described later refers to the shape of the cross-section perpendicular to the substrate 30.

[0071] As an example, the light-emitting device 10 is made of a GaAs-based compound semiconductor. As shown in the cross-sectional view described later (refer to Figure 3 ), the light-emitting device 10 is formed by laminating a plurality of semiconductor layers on the substrate 30. The plurality of laminated semiconductor layers are referred to as laminated semiconductor layers.

[0072] The light-emitting device 10 includes a plurality of light-emitting blocks 11 provided on the substrate 30, a discharge thyristor Z, a selection signal pad 12, an anode electrode 42, an anode pad 13, a discharge signal pad 14, and a cathode pad 15. The discharge thyristor Z is an example of a discharge element.

[0073] In Figure 2Among them, as an example, the light-emitting device 10 includes 24 light-emitting blocks 11. Six light-emitting blocks 11 are arranged in the x direction, and four light-emitting blocks 11 are arranged in the y direction. As an example, the planar shape (the shape on the x-y plane) of the light-emitting block 11 is a square. Between the light-emitting blocks 11 (the part indicated by the dotted line in Figure 2 ), the semiconductor layer is removed by mesa etching, so that they are electrically separated. The light-emitting block 11 located at the upper left end of the paper surface is labeled with a symbol, while the symbols for other light-emitting blocks 11 are omitted.

[0074] The light-emitting block 11 is formed by sequentially laminating a light-emitting element (here, a VCSEL) and a setting thyristor S on the substrate 30. The cathode of the VCSEL is located on the side of the substrate 30, and the anode of the setting thyristor S is located on the side away from the substrate 30. A cathode electrode 41 is provided on the back surface of the substrate 30 (in Figure 2 , it is expressed as 30(41).). In addition, the cathode electrode 41 is sometimes referred to as the back electrode. The setting thyristor S is an example of a setting element.

[0075] As an example, the light-emitting block 11 includes eight VCSELs. One setting thyristor S is provided on the eight VCSELs. In the light-emitting block 11, three positions where VCSELs can be arranged are equally spaced in the x direction, and three positions where VCSELs can be arranged are equally spaced in the y direction. However, at one place, no VCSEL is arranged, but the gate Gs of the setting thyristor S is provided. The gate Gs of the setting thyristor S is connected to the selection signal pad 12. The selection signal pad 12 is connected to Figure 1 the selection unit 90 shown.

[0076] The discharge thyristor Z has the same structure as the setting thyristor S, and the gate Gz is connected to the discharge signal pad 14. The discharge signal pad 14 is connected to Figure 1 the discharge control unit 70 shown. The cathode Kz of the discharge thyristor Z is connected to the cathode pad 15. The cathode pad 15 is connected to the cathode electrode 41 provided with the cathode Kz of the discharge thyristor Z on the back surface of the substrate 30.

[0077] The anode As of the setting thyristor S and the anode Az of the discharge thyristor Z are connected to the anode electrode 42. The anode electrode 42 is connected to the anode pads 13 continuously provided on the ±x direction sides of the substrate 30 where no light-emitting blocks 11 are provided. In Figure 2 , the anode electrode 42 and the anode pads 13 are indicated by a single dotted line. Incidentally, the anode As of the setting thyristor S and the anode Az of the discharge thyristor Z are covered by one anode electrode 42. A DC voltage is supplied from the power supply VLD to the anode pad 13. The DC voltage supplied by the power supply VLD is expressed as the power supply voltage VLD. The cathode electrode 41 is connected to Figure 1 the driver 50 shown.

[0078] The light-emitting device 10 includes 24 light-emitting blocks 11, but may also include a number of light-emitting blocks 11 other than 24. The light-emitting block 11 includes 8 VCSELs, but the light-emitting block 11 may also include a number of VCSELs other than 8. The light-emitting block 11 only needs to include at least 1 VCSEL. The arrangement of the light-emitting blocks 11 and the VCSELs may also be arrangements other than Figure 2 those shown. The light-emitting device 10 includes 1 discharge thyristor Z, but may also include a plurality of discharge thyristors Z.

[0079] (Cross-sectional structure of the light-emitting device 10)

[0080] Figure 3 is a cross-sectional view showing an example of the cross-sectional structure of the light-emitting device 10 to which the first embodiment is applied. The upward direction of the paper surface is the z direction. In Figure 3 three light-emitting blocks 11 are shown (in Figure 3 they are light-emitting blocks 11-1 to 11-3) and the discharge thyristor Z. The light-emitting block 11 includes 1 VCSEL. In the case where the light-emitting block 11 includes a plurality of VCSELs, a plurality of light-emitting ports 43 may be provided in the light-emitting block 11.

[0081] First, the light-emitting block 11 will be described. The light-emitting block 11 is formed by sequentially laminating a VCSEL and a setting thyristor S on a substrate 30.

[0082] The VCSEL is formed, for example, by laminating an n-type cathode layer (n-cathode layer) 31, a light-emitting layer 32, and a p-type anode layer (p-anode layer) 33 on the surface (+z direction side) of an n-type GaAs substrate 30. The n-cathode layer 31 is, for example, a distributed Bragg reflector (DBR: Distributed Bragg Reflector) formed by alternately overlapping AlGaAs layers with different Al compositions. The light-emitting layer 32 is, for example, an active region including a quantum well layer sandwiched between an upper spacer layer and a lower spacer layer. The p-anode layer 33 is, like the n-cathode layer 31, an upper distributed Bragg reflector formed by alternately overlapping AlGaAs layers with different Al compositions. In the VCSEL, the n-cathode layer 31 functions as a cathode, the light-emitting layer 32 functions as a light-emitting layer, and the p-anode layer 33 functions as an anode. The n-cathode layer 31, the light-emitting layer 32, and the p-anode layer 33 are laminated semiconductor layers constituting the VCSEL.

[0083] A tunnel junction layer 34 is laminated on the p-anode layer 33.

[0084] The set thyristor S is formed by laminating an n-type cathode layer (n-cathode layer) 35, a p-type gate layer (p-gate layer) 36, an n-type gate layer (n-gate layer) 37, and a p-type anode layer (p-anode layer) 38 on the tunnel junction layer 34. For example, the n-cathode layer 35 and the n-gate layer 37 are n-type AlGaAs layers, and the p-gate layer 36 and the p-anode layer 38 are p-type AlGaAs layers. In the set thyristor S, the n-cathode layer 35 functions as a cathode, the p-gate layer 36 functions as a p-gate, the n-gate layer 37 functions as an n-gate, and the p-anode layer 38 functions as an anode. Here, it is referred to as the set thyristor S, but it is a thyristor composed of four semiconductor layers. The n-cathode layer 35, the p-gate layer 36, the n-gate layer 37, and the p-anode layer 38 are the laminated semiconductor layers that make up the set thyristor S. In addition, the n-cathode layer 31, the light-emitting layer 32, the p-anode layer 33, the tunnel junction layer 34, the n-cathode layer 35, the p-gate layer 36, the n-gate layer 37, and the p-anode layer 38 are sometimes referred to as laminated semiconductor layers.

[0085] The p-anode layer 38, the n-gate layer 37, the p-gate layer 36, the n-cathode layer 35, and the tunnel junction layer 34 of the set thyristor S laminated on the upper side of the VCSEL are removed by etching to expose the p-anode layer 33, thereby forming a light exit 43 for emitting light from the VCSEL. The set thyristor S is composed of the n-cathode layer 35, the p-gate layer 36, the n-gate layer 37, and the p-anode layer 38 surrounding the light exit 43 of the VCSEL.

[0086] A p-type ohmic electrode (p-ohmic electrode) that makes an ohmic contact with the p-anode layer 38 is provided on the p-anode layer 38. This p-ohmic electrode is the anode terminal of the set thyristor S. Hereinafter, it is referred to as anode As. An n-type ohmic electrode (n-ohmic electrode) that makes an ohmic contact with the n-gate layer 37 is provided on the n-gate layer 37 exposed by etching away a part of the p-anode layer 38. This n-ohmic electrode is the gate terminal of the set thyristor S. Hereinafter, it is referred to as gate Gs.

[0087] The light-emitting blocks 11 are electrically separated by removing the light-emitting layer 32, the p-anode layer 33, the tunnel junction layer 34, the n-cathode layer 35, the p-gate layer 36, the n-gate layer 37, and the p-anode layer 38 by etching (mesa etching).

[0088] An insulating layer 39 is provided on the separated light-emitting blocks 11. Moreover, an anode electrode 42 is provided, and this anode electrode 42 is connected to the p-ohmic electrode (anode As of the set thyristor S) on the p-anode layer 38 through a through hole provided in the insulating layer 39. The anode electrode 42 is connected to the anode pad 13.

[0089] On the other hand, via a through hole provided in the insulating layer 39, an n ohmic electrode (setting the gate Gs of the thyristor S) on the n gate layer 37 is connected to the selection signal pad 12. In Figure 3 it is described that the gate Gs passes through the p anode layer 38 and is connected to the selection signal pad 12, but the p anode layer 38 in the portion where the gate Gs is provided has been removed.

[0090] A cathode electrode 41 that makes ohmic contact with the substrate 30 is provided on the back surface (-z direction side) of the substrate 30. The cathode electrode 41 is connected to the driver 50.

[0091] As described above, the VCSEL of the light emitting block 11 and the setting thyristor S are connected in series between the cathode electrode 41 and the anode electrode 42 on the VCSEL side. Moreover, a plurality of light emitting blocks 11 are connected in parallel between the cathode electrode 41 and the anode electrode 42.

[0092] A tunnel junction layer 34 is provided between the p anode layer 33 of the VCSEL and the n cathode layer 35 of the setting thyristor S. When a voltage is applied with the anode electrode 42 side being positive (+) and the cathode electrode 41 side being negative (-), a reverse bias is formed between the n cathode layer 35 of the setting thyristor S and the p anode layer 33 of the VCSEL, making it difficult for current to flow. Even when there is a reverse bias relationship between the n cathode layer 35 of the setting thyristor S and the p anode layer 33 of the VCSEL, the tunnel junction layer 34 easily allows current to flow. The tunnel junction layer 34 is a junction of a p ++ layer such as GaAs or AlGaAs with a high concentration of p-type impurities on the p anode layer 33 side of the VCSEL and an n ++ layer such as GaAs or AlGaAs with a high concentration of n-type impurities on the n cathode layer 35 side of the setting thyristor S. In the tunnel junction layer 34, due to the narrow width of the depletion region, even when in a reverse bias relationship, electrons tunnel from the conduction band on the n ++ layer side to the valence band on the p ++ layer side. Thus, current easily flows from the n cathode layer 35 of the setting thyristor S to the p anode layer 33 of the VCSEL. The VCSEL and the setting thyristor S are stacked and connected in series via the tunnel junction layer 34.

[0093] The p anode layer 33 includes a current constriction layer. The current constriction layer is composed of an AlAs layer or the like whose oxidation rate is faster than that of AlGaAs. The portion surrounding the light exit 43 is oxidized to form a current blocking portion β, and the portion of the light exit 43 is set as a non-oxidized current passing portion α. The current constriction layer concentrates the current on the central portion of the VCSEL of the resonant cavity structure.

[0094] Next, the discharge thyristor Z will be described. The discharge thyristor Z is formed by laminating an n cathode layer 35, a p gate layer 36, an n gate layer 37, and a p anode layer 38. In the discharge thyristor Z, the n cathode layer 35 functions as a cathode, the p gate layer 36 functions as a p gate, the n gate layer 37 functions as an n gate, and the p anode layer 38 functions as an anode. Here, it is referred to as the discharge thyristor Z, but it is a thyristor composed of four semiconductor layers. The n cathode layer 35, the p gate layer 36, the n gate layer 37, and the p anode layer 38 are the laminated semiconductor layers that make up the discharge thyristor Z. The laminated semiconductor layers that make up the discharge thyristor Z are the same as the laminated semiconductor layers that make up the set thyristor S. Thus, the manufacturing of the light-emitting device 10 becomes easy. In addition, below the discharge thyristor Z, there are an n cathode layer 31, a light-emitting layer 32, a p anode layer 33, and a tunnel junction layer 34 that form a VCSEL in the light-emitting block 11.

[0095] On the p anode layer 38, a p-type ohmic electrode (p ohmic electrode) that makes an ohmic contact with the p anode layer 38 is provided. This p ohmic electrode is the anode terminal of the discharge thyristor Z. Hereinafter, it is referred to as anode Az. On the n gate layer 37 exposed by etching away a part of the p anode layer 38, an n-type ohmic electrode (n ohmic electrode) that makes an ohmic contact with the n gate layer 37 is provided. This n ohmic electrode is the gate terminal of the discharge thyristor Z. Hereinafter, it is referred to as gate Gz. Moreover, an n ohmic electrode is provided on the n cathode layer 35 exposed by etching away a part of the p anode layer 38, the n gate layer 37, and the p gate layer 36. This n ohmic electrode is the cathode electrode of the discharge thyristor Z. Hereinafter, it is referred to as cathode Kz.

[0096] Similar to the case with the light-emitting block 11, the discharge thyristor Z and the light-emitting block 11 are electrically separated by etching away the light-emitting layer 32, the p anode layer 33, the tunnel junction layer 34, the n cathode layer 35, the p gate layer 36, the n gate layer 37, and the p anode layer 38.

[0097] Via a through hole provided in the insulating layer 39, the p ohmic electrode (anode Az of the discharge thyristor Z) on the p anode layer 38 is connected to the anode electrode 42.

[0098] The n ohmic electrode (cathode Kz of the discharge thyristor Z) provided on the n cathode layer 35 is connected to the cathode pad 15. The cathode pad 15 is connected to the cathode electrode 41. The discharge thyristor Z is connected in parallel with the light-emitting block 11 between the cathode electrode 41 and the anode electrode 42.

[0099] In Figure 3In this case, an n-ohmic electrode is provided on the n-cathode layer 35 to serve as the cathode Kz of the discharge thyristor Z. In the discharge thyristor Z, the p-anode layer 33 may also be exposed and a p-ohmic electrode may be provided on the p-anode layer 33 to serve as the cathode Kz of the discharge thyristor Z. Since the p-anode layer 33 is connected to the n-cathode layer 35 via the tunnel junction layer 34, the p-anode layer 33 and the n-cathode layer 35 have the same potential. By setting it in this way, the etching process for providing the cathode Kz of the discharge thyristor Z becomes the same as the process for providing the light exit port 43 of the light-emitting block 11, and the process of exposing the n-cathode layer 35 is not required.

[0100] (Equivalent circuit of the light-emitting device 10)

[0101] Figure 4 is the equivalent circuit of the light-emitting device 10 to which the first embodiment is applied. In Figure 4 In this case, the light-emitting device 10 shows 24 light-emitting blocks 11 (in Figure 4 are the light-emitting blocks 11-1 to 11-24) and the discharge thyristor Z. In Figure 4 In this case, in addition to the light-emitting device 10, the power supply VLD and the driver 50 are also shown together.

[0102] In Figure 4 In this case, the thyristor S and the discharge thyristor Z are set to be expressed as a combination of a pnp transistor and an npn transistor.

[0103] The light-emitting block 11 is configured by setting the thyristor S and the VCSEL to be connected in series. The cathode (emitter of the npn transistor) of the set thyristor S is connected to the anode of the VCSEL. The anode As (emitter of the pnp transistor) of the set thyristor S is connected to the anode electrode 42, and the cathode of the VCSEL is connected to the cathode electrode 41 via the resistor R1. The resistor R1 is an equivalent resistor that equivalently represents the internal resistances in the set thyristor S and the VCSEL.

[0104] A plurality of light-emitting blocks 11 are connected in parallel between the anode electrode 42 and the cathode electrode 41.

[0105] In the discharge thyristor Z, the anode Az (emitter of the pnp transistor) is connected to the anode electrode 42, and the cathode Kz is connected to the cathode pad 15 via the resistor R2. The cathode pad 15 is connected to the cathode electrode 41 outside the light-emitting device 10.

[0106] The anode pad 13 is connected to the power supply VLD via the parasitic inductance L1. The cathode electrode 41 is connected to the driver 50 via the parasitic inductance L2. The parasitic inductance L1 is the inductance parasitic on the wiring connecting the light-emitting device 10 and the power supply VLD when the light-emitting device 10 is installed in the light-emitting device 1. The parasitic inductance L2 is the inductance parasitic on the wiring connecting the light-emitting device 10 and the driver 50. In the wiring where they are connected, in addition to the inductance, resistance and capacitance are also generated, but the influence of the inductance is the greatest. In Figure 4 the inductances with great influence are expressed as parasitic inductances L1 and L2.

[0107] The driver 50 is, for example, an n-channel MOS transistor (nMOS transistor) 51, and performs constant current driving on the light-emitting block 11. In the nMOS transistor 51 of the driver 50, the source is grounded and the drain is connected to the cathode electrode 41. The light-emitting device 10 is driven in a so-called low-side manner.

[0108] Here, the lighting and extinguishing of the VCSEL in the light-emitting block 11 will be described. In addition, the lighting and extinguishing of the VCSEL in the light-emitting block 11 are expressed as the lighting and extinguishing of the light-emitting block 11. As an example, the voltages of the respective signals are shown in parentheses. And the forward voltage of the pn junction is set to 1.5V. In the pn junction, if a voltage of 1.5V or more is applied, it becomes a forward bias and current easily flows, and if a voltage less than 1.5V is applied, it becomes a reverse bias and current does not easily flow. In a thyristor, if a forward bias is formed between the anode (emitter of the pnp transistor) and the gate (base of the pnp transistor) while a voltage is applied between the anode (emitter of the pnp transistor) and the cathode (emitter of the npn transistor), the pnp transistor conducts. Subsequently, the npn transistor conducts. Thus, the thyristor becomes a conducting state. In addition, the transfer of the thyristor from the off state to the on state is expressed as turn on.

[0109] The state where none of the light-emitting blocks 11 are lit and the state before the light-emitting block 11 to be lit is selected is called the initial state. In the initial state, the power supply voltage VLD (9V) is applied from the power supply VLD to the anode pad 13 of the light-emitting device 10. Thus, the cathode electrode 41 becomes the power supply voltage VLD (9V). Selection signals (9V) that do not select any of the light-emitting blocks 11 are supplied from the selection unit 90 to all the selection signal pads 12. In addition, the selection signal (9V) is the same as the power supply voltage VLD (9V) applied to the anode As of the setting thyristor S. Incidentally, the emitter (anode As of the setting thyristor S) and the base (gate Gs of the setting thyristor S) of the pnp transistor of the setting thyristor S are at the same potential (power supply voltage VLD (9V)). In other words, a forward bias is not formed between the emitter (anode As of the setting thyristor S) - base (gate Gs of the setting thyristor S) of the pnp transistor of the setting thyristor S.

[0110] The lighting control signal (0V) that turns off the nMOS transistor 51 of the driver 50 is supplied from the lighting control unit 60 to the driver 50. Since the nMOS transistor 51 of the driver 50 is turned off, the cathode electrode 41 of the light-emitting device 10 becomes the power supply voltage VLD (9V). It is set that the cathode (emitter of the npn transistor) of the thyristor S and the anode of the VCSEL become the power supply voltage VLD (9V). It is set that the anode (emitter of the pnp transistor) and the cathode (emitter of the npn transistor) of the thyristor S are at the same potential (power supply voltage VLD (9V)).

[0111] The case of lighting one light-emitting block 11 (here, the light-emitting block 11-1) will be described. The selection unit 90 supplies a selection signal (7V) for selecting the light-emitting block 11-1 to the selection signal pad 12 of the light-emitting block 11-1. In this way, the voltage of the gate Gs of the set thyristor S of the light-emitting block 11-1 becomes 7V, and a forward bias is formed between the emitter (anode As of the set thyristor S) - base (gate Gs of the set thyristor S) of the pnp transistor. Thus, the set thyristor S is set to a state where it can be turned on (turn-on enabled state). In addition, since the anode (emitter of the pnp transistor) and the cathode (emitter of the npn transistor) of the set thyristor S are at the same potential (power supply voltage VLD (9V)), the set thyristor S does not turn on. This state is expressed as a turn-on enabled state. In addition, if the set thyristor S turns on, current flows through the VCSEL and emits light. If the set thyristor S becomes in a turn-on enabled state, the VCSEL becomes in a state where it can emit light. Therefore, the set thyristor S is described as an element that sets the VCSEL to a state where it can emit light. The selection signal (7V) is a value set to 9V of the power supply voltage VLD in consideration of the forward voltage (1.5V) of the pn junction.

[0112] Here, if a lighting signal (1.2V) that turns on the nMOS transistor 51 is supplied from the lighting control unit 60 to the driver 50, the nMOS transistor 51 changes from off to on. In this way, the voltage of the cathode electrode 41 (cathode voltage) is pulled to the ground voltage (0V) side. In this way, the set thyristor S in the turn-on enabled state in the light-emitting block 11-1 turns on. Then, current flows through the set thyristor S in the VCSEL, and the VCSEL emits light. That is, the light-emitting block 11-1 lights up. When the light-emitting block 11-1 lights up, the nMOS transistor 51 of the driver 50 operates as a constant current source. At this time, the voltage of the drain (cathode electrode 41) of the nMOS transistor 51 is set to about 1V. In addition, it is assumed that the lighting signal (1.2V) is a voltage that is higher than the threshold voltage of the nMOS transistor 51 of the driver 50 and turns on the nMOS transistor 51.

[0113] Next, the case of extinguishing the lit light-emitting block 11-1 will be described.

[0114] A lighting control signal (0V) for turning off the nMOS transistor 51 of the driver 50 is supplied from the lighting control unit 60. When the nMOS transistor 51 changes from conducting to non-conducting, the current flowing through the VCSEL via the set thyristor S is blocked, and the VCSEL stops emitting light. That is, the light-emitting block 11-1 is extinguished. Additionally, if a selection signal (7V) is supplied to the gate Gs of the set thyristor S of the light-emitting block 11-1, the set thyristor S maintains the turn-on state. When a lighting control signal (1.2V) for turning on the nMOS transistor 51 of the driver 50 is supplied from the lighting control unit 60, the set thyristor S of the light-emitting block 11-1 turns on, and thus the VCSEL emits light. That is, the light-emitting block 11-1 lights up again. However, if the selection signal (7V) is changed to a selection signal (9V) indicating non-selection during the lighting of the light-emitting block 11-1, even if a lighting control signal (1.2V) for turning on the nMOS transistor 51 of the driver 50 is supplied from the lighting control unit 60 after the light-emitting block 11-1 is extinguished, the set thyristor S of the light-emitting block 11-1 will not turn on, and the light-emitting block 11-1 will not light up again.

[0115] Even if the selection signal supplied to the gate Gs changes from a selection signal (7V) indicating selection to a selection signal (9V) indicating non-selection, the conducting set thyristor S will not change to the non-conducting state. The set thyristor S changes to the non-conducting state when the current stops flowing. Therefore, when the nMOS transistor 51 of the driver 50 changes from conducting to non-conducting and the current is flowing through the set thyristor S or after the current stops flowing, for example, the selection signal can be changed from a selection signal (7V) indicating selection to a selection signal (9V) indicating non-selection.

[0116] Next, the case of maintaining the state (extinguished state) of the extinguished light-emitting block 11-1 will be described. The selection unit 90 only needs to maintain the supply of a selection signal (9V) indicating non-selection to the light-emitting block 11-1. If a selection signal (9V) is supplied to the light-emitting block 11-1, as described above, the set thyristor S will not become in the turn-on state. Even if a lighting signal (1.2V) for turning on the nMOS transistor 51 of the driver 50 is supplied from the lighting control unit 60 and the nMOS transistor 51 of the driver 50 changes from non-conducting to conducting, the set thyristor S of the light-emitting block 11-1 will not turn on, and no current flows through the VCSEL. That is, the light-emitting block 11-1 maintains the extinguished state.

[0117] As described above, the light-emitting block 11 to be lit is selected by supplying a selection signal (7V) to the light-emitting block 11 among a plurality of light-emitting blocks 11. The number of light-emitting blocks 11 to be lit simultaneously can be 1, a plurality, or all.

[0118] Light-emitting device 10A without discharge thyristor Z

[0119] Here, before explaining the discharge thyristor Z in the light-emitting device 10 to which the first embodiment is applied, problems when performing block irradiation using the light-emitting device 10A without the discharge thyristor Z will be explained.

[0120] Figure 5 This is an equivalent circuit of the light-emitting device 1A using the light-emitting device 10A that does not apply the first embodiment and does not have the discharge thyristor Z. Figure 5 (a) shows the equivalent circuit of 24 light-emitting blocks 11, Figure 5 and (b) shows the equivalent circuit when one light-emitting block 11 is lit and the other light-emitting blocks 11 are set to the extinguished state.

[0121] Figure 5 (a) is a structure in which the discharge thyristor Z is removed in Figure 4 . In addition, instead of the selection signal pad 12, a selection unit 90 that supplies the selection signal is shown. The rest is the same as Figure 4 , so the same reference numerals are used and the description is omitted.

[0122] In Figure 5 (b), one light-emitting block 11 (light-emitting block 11-1 in Figure 5 (b)) is lit and the other light-emitting blocks 11 ( Figure 5 light-emitting blocks 11-2 to 11-24 in (a)) are set to the extinguished state.

[0123] As shown in Figure 5 (a), the light-emitting blocks 11 are connected in parallel between the anode electrode 42 and the cathode electrode 41. The light-emitting block 11 is a series connection of a set thyristor S and a VCSEL. If the light-emitting block 11-1 is lit, current flows from the anode electrode 42 to the cathode electrode 41 through the light-emitting block 11-1, and thus the VCSEL emits light. At this time, no current flows through the other light-emitting blocks 11-2 to 11-24. However, since the other light-emitting blocks 11-2 to 11-24 are located between the anode electrode 42 and the cathode electrode 41, they become capacitances, that is, parasitic capacitances. This capacitance is connected in parallel with the light-emitting block 11-1. Therefore, in Figure 5 (b), the other light-emitting blocks 11-2 to 11-24 are expressed as parallel capacitances C1. The resistor R3 is an equivalent resistor that equivalently represents the internal resistances in the other light-emitting blocks 11-2 to 11-24.

[0124] Figure 6 This is an equivalent circuit for explaining the influence of the parallel capacitance C1. Figure 6The (a) of [description] is a light-emitting device 1B that uses a light-emitting device 10B having one light-emitting block 11. Figure 6 The (b) of [description] is a light-emitting device 1A that uses a light-emitting device 10A having 24 light-emitting blocks 11. In Figure 6 In the light-emitting device 1B of the (a) of [description], one light-emitting block 11 provided is lit. In Figure 6 In the (a) of [description], it does not have Figure 5 the parallel capacitor C1 shown in the (b) of [description]. In Figure 6 In the light-emitting device 1A of the (b) of [description], one light-emitting block 11 is lit and the other 23 light-emitting blocks 11 are set to the extinguished state. Figure 6 The (b) of [description] is the same as Figure 5 the (b) of [description].

[0125] The current flowing in the VCSEL was obtained by simulation. The light-emitting state of the VCSEL can be known from the current flowing in the VCSEL. In the simulation, as Figure 6 shown in the (a) and (b) of [description], the power supply voltage VLD is set to 9V, the parasitic inductance L1 is set to 0.6 nH, the parasitic inductance L2 is set to 0.3 nH, and the resistance R1 is set to 6 Ω. Moreover, as Figure 6 shown in the (b) of [description], the parallel capacitor C1 is set to 75 pF and the resistance R3 is set to 0.26 Ω.

[0126] The lighting control signal supplied from the lighting control unit 60 to the driver 50 is the same as the lighting control signal shown in the (a) of the Figure 9 described later, with the amplitude set to 1.2V, the pulse width W1 set to 5 ns, and the rise time and fall time set to 0.5 ns.

[0127] Figure 7 This is the result of simulating the current I flowing in the VCSEL using an equivalent circuit that explains the influence of the parallel capacitor C1. The horizontal axis is the time t (ns), and the vertical axis is the current I (VCSEL) flowing through the VCSEL. In Figure 6 the light-emitting device 1B (described as "one light-emitting block" in Figure 7 [description]) that uses a light-emitting device 10B having one light-emitting block 11, the rise time and fall time of the current I (VCSEL) flowing in the VCSEL are short. The fall time is about 50 ns. On the other hand, in the light-emitting device 1A (described as "24 light-emitting blocks" in Figure 7 [description]) that uses a light-emitting device 10A having 24 light-emitting blocks 11, compared with the light-emitting device 1B ("one light-emitting block"), the rise of the current I (VCSEL) flowing in the VCSEL is delayed and the fall time is long. Due to the long fall time, the light emission of the VCSEL continues for a long time. In other words, the light emission of the VCSEL continues for a long time.

[0128] The reason why the rise of the light-emitting device 1A (“24 light-emitting blocks”) is slower than that of the light-emitting device 1B (“1 light-emitting block”) is that the current that starts to flow when the nMOS transistor 51 of the driver 50 is turned on first charges the parallel capacitor C1 and then flows through the VCSEL. The current I(VCSEL) flowing through the VCSEL rises rapidly because, during the charging of the parallel capacitor C1, the influence of the response of the parasitic inductances L1 and L2 of the current path, especially the voltage drop on the cathode electrode 41 side from 9V to 1V, is alleviated.

[0129] The reason why the fall time of the light-emitting device 1A (“24 light-emitting blocks”) is longer than that of the light-emitting device 1B (“1 light-emitting block”) is that the charge stored in the parallel capacitor C1 is discharged through the VCSEL with the time constant of the resistors R1 and R2 and the parallel capacitor C1. Incidentally, the charge stored in the parallel capacitor C1 is discharged in the path 16 indicated by the dotted line in Figure 6 (b). The path 16 includes the light-emitting block 11-1 including the lit VCSEL. Therefore, the light emission of the VCSEL continues for a long time. In the light-emitting device 1B (“1 light-emitting block”), the parasitic capacitance to be discharged is small, so the current flowing through the VCSEL rapidly decreases.

[0130] As described above, in block irradiation, all the unlit light-emitting blocks 11 become the parallel capacitor C1. The parallel capacitor C1 is several pF to 100 pF or more. Such a parallel capacitor C1 results in a fall time of several ns, which impairs the fall characteristics of the light-emitting device 1.

[0131] (Light-emitting device 1 using a light-emitting device 10 equipped with a discharge thyristor Z)

[0132] Figure 8 is an equivalent circuit of the light-emitting device 1 using the light-emitting device 10 equipped with the discharge thyristor Z applicable to the first embodiment. In Figure 8 , as the light-emitting device 1, the light-emitting device 10, the driver 50, the lighting control unit 60, and the discharge control unit 70 are shown.

[0133] The light-emitting device 10 includes 24 light-emitting blocks 11. Moreover, one light-emitting block 11 (the light-emitting block 11-1 in Figure 8 ) is selected for lighting, and the other light-emitting blocks 11 (light-emitting blocks 11-2 to 11-24) are set in the extinguished state. As described above, the light-emitting block 11-1 is represented by the series connection of the set thyristor S, the VCSEL, and the resistor R1. The extinguished light-emitting block 11 is represented by the series connection of the parallel capacitor C1 and the resistor R3. The discharge thyristor Z is connected in series with the resistor R2 that equivalently represents the internal resistance of the discharge thyristor Z.

[0134] It is set that the series connection of the thyristor S, the VCSEL, and the resistor R1, the series connection of the parallel capacitor C1 and the resistor R3, and the series connection of the discharge thyristor Z and the resistor R2 are connected in parallel between the cathode electrode 41 and the anode electrode 42. Additionally, since the resistors R1, R2, and R3 are parasitic resistors, it is set that the light-emitting block 11 in which the thyristor S is connected in parallel with the VCSEL and the discharge thyristor Z are connected in series.

[0135] The power supply VLD supplies the power supply voltage VLD to the anode electrode 42 via the parasitic inductance L1. The drain of the nMOS transistor 51 of the driver 50 is connected to the cathode electrode 41 via the parasitic inductance L2. The source of the nMOS transistor 51 of the driver 50 is grounded. The lighting control signal from the lighting control unit 60 is supplied to the gate of the nMOS transistor 51 of the driver 50. The on / off of the nMOS transistor 51 of the driver 50 is controlled according to the lighting control signal.

[0136] The discharge control unit 70 includes an nMOS transistor 71, a resistor R4, and an nMOS transistor control circuit 72. The nMOS transistor control circuit 72 supplies a signal (nMOS transistor control signal) for controlling the on / off of the nMOS transistor 71. One terminal of the resistor R4 is connected to the drain of the nMOS transistor 71. The other terminal of the resistor R4 that is not connected to the nMOS transistor 71 is connected to the power supply VLD. The source of the nMOS transistor 71 is grounded. The nMOS transistor control circuit 72 is connected to the gate of the nMOS transistor 71. The nMOS transistor control circuit 72 supplies an nMOS transistor control signal for turning on / off the nMOS transistor 71.

[0137] The gate Gz of the discharge thyristor Z is connected via the parasitic inductance L3 to the connection point between the drain of the nMOS transistor 71 of the discharge control unit 70 and the resistor R4. The parasitic inductance L3 is the inductance parasitic on the wiring connecting the discharge signal pad 14 connected to the gate Gz of the discharge thyristor Z and the discharge control unit 70. The voltage at the connection point between the drain of the nMOS transistor 71 of the discharge control unit 70 and the resistor R4 is the discharge control signal, which is supplied to the gate Gz of the discharge thyristor Z.

[0138] The discharge thyristor Z operates in the same manner as the aforementioned setting thyristor S. If a forward bias is established between the emitter (anode Az) and the base (gate Gz) of the pnp transistor of the discharge thyristor Z while a voltage is applied between the anode Az and the cathode Kz of the discharge thyristor Z, the discharge thyristor Z in the off state turns on and transitions to the on state. When the power supply voltage VLD is 9V, the emitter (anode Az) of the pnp transistor of the discharge thyristor Z becomes 9V. If the base (gate Gz) of the pnp transistor becomes 7.5V (9V - 1.5V) or less, a forward bias is established between the emitter (anode Az) and the base (gate Gz) of the pnp transistor, causing the discharge thyristor Z to turn on. Conversely, if the base (gate Gz) of the pnp transistor exceeds 7.5V, a forward bias will not be established between the emitter (anode Az) and the base (gate Gz) of the pnp transistor of the discharge thyristor Z, and thus it will not turn on.

[0139] If the nMOS transistor 71 of the discharge control unit 70 is turned off while a voltage is applied between the anode Az and the cathode Kz of the discharge thyristor Z, the connection point between the drain of the nMOS transistor 71 and the resistor R4 becomes the power supply voltage VLD (9V). In this case, the discharge control signal becomes 9V. If the discharge control signal is 9V, the gate Gz of the discharge thyristor Z becomes 9V, and the discharge thyristor Z does not turn on but remains in the off state. On the other hand, if the nMOS transistor 71 of the discharge control unit 70 is turned on, the connection point between the drain of the nMOS transistor 71 and the resistor R4 is pulled to the ground potential (0V) side. In this case, the discharge control signal changes towards 0V. If the discharge control signal drops to a voltage that causes the discharge thyristor Z to turn on, the discharge thyristor Z turns on. Additionally, even if the discharge control signal does not reach 0V, the discharge thyristor Z will still turn on. The switching of the thyristor from the off state to the on state is fast.

[0140] In the light-emitting device 1, when the light-emitting block 11 of the light-emitting element 10 (in Figure 8When the light-emitting block 11-1 is extinguished, the discharge thyristor Z is turned on. During the period when the light-emitting block 11-1 is lit, the cathode electrode 41 is 1V and the anode electrode 42 is the power supply voltage VLD (9V). If the light-emitting block 11-1 is extinguished and the discharge thyristor Z is turned on, the charge accumulated in the parallel capacitor C1 during the period when the light-emitting block 11-1 is lit is discharged through the discharge path 17 of the discharge thyristor Z. Then, the cathode electrode 41 rises toward the power supply voltage VLD (9V). When the cathode electrode 41 becomes the power supply voltage VLD (9V), the anode Az and the cathode Kz of the discharge thyristor Z become the same power supply voltage VLD (9V), and thus the discharge thyristor Z is turned off. In the light-emitting device 10, the discharge path 17 is constituted by the discharge thyristor Z. In addition, although the discharge also occurs through the lit light-emitting block 11-1, the path through the discharge thyristor Z is described as the discharge path 17 here.

[0141] The nMOS transistor 71 of the discharge control unit 70 is applied with the power supply voltage VLD (9V) via the resistor R4. Even when the nMOS transistor 71 is in the on state, since the flowing current is limited by the resistor R4, a large current flowing in the nMOS transistor 71 can be suppressed. Moreover, the nMOS transistor 71 only needs to supply the current for turning on the discharge thyristor Z, and the current capacitance can be small. By providing the resistor R4, the discharge control unit 70 (the drain of the nMOS transistor 71) can be connected to the power supply VLD without separately providing a power supply for the discharge control unit 70 (the drain of the nMOS transistor 71).

[0142] The following values were used in the simulation of the current I flowing through the VCSEL. The parasitic inductances L1, L2, the parallel capacitor C1, the resistors R1, R3 are the same as the above values, which are 0.6 nH, 0.3 nH, 75 pF, 6 Ω, 0.26 Ω respectively. Moreover, the parasitic inductance L3 is 0.8 nH and the resistor R2 is 6 Ω.

[0143] Figure 9 It is a timing chart showing the lighting control signal and the discharge control signal used in the simulation. Figure 9 (a) of represents the lighting control signal, Figure 9 (b) of represents the discharge control signal. The lighting control signal is a signal supplied from the lighting control unit 60 to the driver 50. The discharge control signal is a signal supplied from the discharge control unit 70 (the connection point of the drain of the nMOS transistor 71 and the resistor R4) to the gate Gz of the discharge thyristor Z. In addition, in Figure 9 (a) of, the nMOS transistor control signal supplied from the nMOS transistor control circuit 72 to the gate of the nMOS transistor 71 in the discharge control unit 70 is also shown. In Figure 9 , the horizontal axis is the time t (ns) and the vertical axis is the signal voltage (V).

[0144] As Figure 9 shown in (a) of FIG., the lighting control signal rises from 0V to 1.2V within 0.5ns at the timing of 5ns, and falls from 1.2V to 0V within 0.5ns at the timing of 9.5ns. The amplitude is 1.2V. The lighting control signal is a pulse signal with a period of 40ns. The pulse width W1 (sometimes referred to as width) at 1 / 2 of the amplitude is 5ns. The rise time and fall time are 0.5ns.

[0145] The nMOS transistor control signal rises from 0V to 1.2V within 0.3ns at the timing of 9.8ns, and falls from 1.2V to 0V within 0.3ns at the timing of 10.3ns. The amplitude is 1.2V. The nMOS transistor control signal is a pulse signal with a period of 40ns. The pulse width (sometimes referred to as width) at 1 / 2 of the amplitude is 0.8ns.

[0146] As Figure 9 shown in (b) of FIG., the discharge control signal controlled according to the nMOS transistor control signal falls from 9V to 0V within 0.3ns at the timing of 9.8ns, and rises from 0V to 9V within 0.3ns at the timing of 10.3ns. The amplitude is 9V. The discharge control signal is a pulse signal with a period of 40ns. The pulse width W2 (sometimes referred to as width) at 1 / 2 of the amplitude is 0.8ns.

[0147] The discharge control signal starts to fall 0.2ns before the timing (10ns) when the lighting control signal starts to fall. As described above, if the gate Gz becomes 7.5V or less, the discharge thyristor Z turns on. That is, when the lighting control signal is 1.2V, that is, during the period when the nMOS transistor 51 of the driver 50 is conducting, the discharge thyristor Z is turned on.

[0148] As Figure 9 shown in (a) and (b) of FIG., the timing when the discharge control signal starts to fall can be before the lighting control signal starts to fall or after the lighting control signal falls. The discharge control signal falling when the lighting control signal falls means that the timing when the discharge control signal starts to fall includes before the lighting control signal starts to fall and after the lighting control signal falls. In addition, if the discharge control signal starts to fall before the lighting control signal starts to fall, current flows from the power supply VLD through the discharge thyristor Z to the driver 50 (refer to Figure 8 ), so the power consumption increases. In order to reduce the power consumption, for example, it is better that the overlap between the lighting control signal and the discharge control signal on the time axis is small.

[0149] In the above, in the lighting control signal, the signal voltage that turns on the nMOS transistor 51 of the driver 50 is higher than the signal voltage that turns it off, and in the discharge control signal, the signal voltage that turns on the discharge thyristor Z is lower than the signal voltage that maintains it in the off state. Depending on the structures of the lighting control unit 60 and the discharge control unit 70, the high and low levels of the signal voltage are different. Therefore, it can be stated that the discharge control signal starts to become the signal voltage that turns on the discharge thyristor Z when the lighting control signal becomes the signal voltage that turns off the driver 50 (nMOS transistor 51). When the lighting control signal becomes the signal voltage that turns off the driver 50 (nMOS transistor 51), it can be just before the driver 50 (nMOS transistor 51) is about to turn off or just after it has turned off.

[0150] Once the thyristor is turned on, it will not transfer to the off state even if the gate voltage is changed. Therefore, the period (pulse width) during which the discharge control signal is lower than the power supply voltage VLD only needs to be a period that can turn on the discharge thyristor Z. After the discharge thyristor Z is turned on, the discharge control signal can be restored to 9V. The pulse width W2 (width) of the discharge control signal can be shorter than the pulse width W1 (width) of the lighting control signal. Also, the discharge control signal only needs to be able to turn on the discharge thyristor Z and does not have to change to 0V. During the period when the discharge control signal is lower than the power supply voltage VLD, the nMOS transistor control signal that turns on the nMOS transistor 71 becomes conductive. During the period when the discharge control signal is lower than the power supply voltage VLD, current flows through the nMOS transistor 71. Therefore, if the period when the discharge control signal is lower than the power supply voltage VLD is long, the power consumption in the light-emitting device 1 becomes large.

[0151] The timing of the discharge control signal and the lighting control signal is adjusted by the adjustment unit 80. When the number of light-emitting blocks 11 lit in parallel is small, the parallel capacitor C1 is large and the amount of charge stored in the parallel capacitor C1 is large. On the other hand, when the number of light-emitting blocks 11 lit in parallel is large, the parallel capacitor C1 is small and the amount of charge stored in the parallel capacitor C1 is small. Therefore, the adjustment unit 80 makes adjustments such as advancing the falling timing of the discharge control signal relative to the falling timing of the lighting control signal when the number of light-emitting blocks 11 lit in parallel is small, and delaying the falling timing of the discharge control signal relative to the falling timing of the lighting control signal when the number of light-emitting blocks 11 lit in parallel is large. The adjustment unit 80 adjusts the falling timing of the discharge control signal based on the falling timing of the lighting control signal and the number of lit light-emitting blocks.

[0152] Figure 10This is the result of simulating the current I flowing through the VCSEL in the light-emitting device 1 using the light-emitting device 10 equipped with the discharge thyristor Z applicable to the first embodiment. The light-emitting device 10 includes 24 light-emitting blocks 11. One light-emitting block 11 is lit and the other light-emitting blocks 11 are set to the extinguished state. In Figure 10 the horizontal axis is the time t (ns), and the vertical axis is the current I (VCSEL) flowing through the VCSEL. In Figure 10 the current I flowing through the VCSEL in the light-emitting device 1A using the light-emitting device 10A not equipped with the discharge thyristor Z is also shown (reference Figure 7 ). The light-emitting device 1 using the light-emitting device 10 equipped with the discharge thyristor Z is expressed as "the case of the light-emitting device 10 equipped with the discharge thyristor Z", and in Figure 10 it is expressed as "with a discharge thyristor". The light-emitting device 1A using the light-emitting device 10A not equipped with the discharge thyristor Z is expressed as "the case of the light-emitting device 10A not equipped with the discharge thyristor Z", and in Figure 10 it is expressed as "without a discharge thyristor". The lighting control signal and the discharge control signal in the case of the light-emitting device 10 equipped with the discharge thyristor Z are as shown in the timing charts of Figure 9 (a) and (b). The lighting control signal in the case of the light-emitting device 10A not equipped with the discharge thyristor Z is the lighting control signal in the timing chart shown in Figure 9 (a).

[0153] As shown in Figure 10 , regarding the rise of the current I of the VCSEL, there is little difference between the case of the light-emitting device 10 equipped with the discharge thyristor Z ("with a discharge thyristor") and the case of the light-emitting device 10A not equipped with the discharge thyristor Z ("without a discharge thyristor"). However, regarding the fall of the current I of the VCSEL, the delay in the case of the light-emitting device 10 equipped with the discharge thyristor Z ("with a discharge thyristor") is smaller than that in the case of the light-emitting device 10A not equipped with the discharge thyristor Z ("without a discharge thyristor"). That is, by equipping with the discharge thyristor Z, the fall time of the current I flowing through the VCSEL becomes shorter. The continuous light emission of the VCSEL is suppressed.

[0154] As described above, in the light-emitting device 1, when extinguishing the light-emitting block 11, the discharge thyristor Z is turned on. By lighting the light-emitting block 11, charges are accumulated in the parallel capacitor C1. If the discharge thyristor Z is turned on, the charges accumulated in the parallel capacitor C1 are discharged via the discharge path 17 formed by the discharge thyristor Z. As a result, the time constant of the discharge becomes smaller, and the fall time of the current I of the VCSEL becomes shorter. In order to reduce the time constant of the discharge, for example, it is better to reduce the internal resistance of the discharge thyristor Z, that is, the resistance R2.

[0155] (Light-emitting device 1C as a comparative example)

[0156] In the light-emitting device 1 of the first embodiment, a discharge thyristor Z is provided inside the light-emitting device 10. The discharge thyristor Z constitutes a discharge path 17 (embodiment) for discharging the charge accumulated in the parallel capacitor C1.

[0157] Here, as a comparative example, a light-emitting device 1C that uses a light-emitting device 10A not having a discharge thyristor Z and has a switch constituting a discharge path 18 provided outside the light-emitting device 10A will be described.

[0158] Figure 11 It is an equivalent circuit of the light-emitting device 1C (comparative example) having a switch 75. The light-emitting device 1C includes a light-emitting device 10A, a driver 50, a lighting control unit 60, and a switch 75. The switch 75 has the same function as the discharge control unit 70 of the light-emitting device 1 of the embodiment.

[0159] Assume that the light-emitting device 10A includes 24 light-emitting blocks 11 (refer to Figure 5 (a)). Moreover, one light-emitting block 11 (light-emitting block 11-1 in Figure 11 ) is lit and the other light-emitting blocks 11 (light-emitting blocks 11-2 to 11-24) are set to the extinguished state. In addition, for the same parts as Figure 8 , the same reference numerals are used and the description is omitted.

[0160] The switch 75 includes a p-channel MOS transistor (pMOS transistor) 76 and a pMOS transistor control circuit 77. The pMOS transistor control circuit 77 supplies a signal (pMOS transistor control signal) for turning on / off the pMOS transistor 76. The drain of the pMOS transistor 76 is connected to the drain of the nMOS transistor 51 of the driver 50. The source of the pMOS transistor 76 is connected to the power supply VLD. The gate of the pMOS transistor 76 is connected to the pMOS transistor control circuit 77. The pMOS transistor 76 of the switch 75 is turned off when the gate is at the power supply voltage VLD and is turned on when the gate becomes a voltage below the power supply voltage VLD minus the threshold voltage.

[0161] If the nMOS transistor 51 of the driver 50 is turned from off to on in the state where the switch 75 (pMOS transistor 76) is off, the light-emitting block 11-1 is lit. Along with the lighting of the light-emitting block 11-1, charge is accumulated in the parallel capacitor C1. If the nMOS transistor 51 of the driver 50 is turned from on to off, the light-emitting block 11-1 is extinguished. At this time, if the switch 75 (pMOS transistor 76) is turned on, the charge accumulated in the parallel capacitor C1 is discharged through the discharge path 18 passing through the switch 75 (pMOS transistor 76).

[0162] In the simulation shown below, the pMOS transistor control signal generated by the pMOS transistor control circuit 77 rises from 5.7 V to 9 V within 0.5 ns at the timing of 5 ns, and falls from 9 V to 5.7 V within 0.5 ns at the timing of 9.5 ns. The amplitude is 3.3 V. The pMOS transistor control signal is a pulse signal with a period of 40 ns. The pulse width at half of the amplitude (sometimes referred to as the width) is 5 ns. The rise time / fall time is 0.5 ns. When the pMOS transistor control signal is 9 V, the pMOS transistor 76 is turned off, and when the pMOS transistor control signal is 5.7 V, the pMOS transistor 76 is turned on.

[0163] The nMOS transistor 51 of the driver 50 operates according to Figure 9 the lighting control signal shown in (a) of. In this case, the nMOS transistor 51 of the driver 50 and the pMOS transistor 76 of the switch 75 operate complementarily. In other words, when the nMOS transistor 51 of the driver 50 is turned on, the pMOS transistor 76 is turned off, and when the nMOS transistor 51 of the driver 50 is turned off, the pMOS transistor 76 is turned on.

[0164] Figure 12 are the results of simulating the current I flowing through the VCSEL in the light-emitting device 1 (embodiment) using the light-emitting device 10 equipped with the discharge thyristor Z and the light-emitting device 1C (comparative example) equipped with the switch 75. The light-emitting device 1C (comparative example) uses the light-emitting device 10A that does not have the discharge thyristor Z. The horizontal axis is the time t (ns), and the vertical axis is the current I (VCSEL) flowing through the VCSEL. In addition, in Figure 12 the light-emitting device 1 using the light-emitting device 10 equipped with the discharge thyristor Z is expressed as "Embodiment (discharge thyristor)", and the light-emitting device 1C equipped with the switch 75 is expressed as "Comparative example (switch)".

[0165] In the light-emitting device 1 (embodiment) using the light-emitting device 10 equipped with the discharge thyristor Z and the light-emitting device 1C (comparative example) equipped with the switch 75, there is almost no difference in the rising characteristics of the current I flowing through the VCSEL. On the other hand, regarding the fall time of the current I flowing through the VCSEL, the light-emitting device 1 (embodiment) using the light-emitting device 10 equipped with the discharge thyristor Z is shorter than the light-emitting device 1C (comparative example) equipped with the switch 75. In the light-emitting device 1C (comparative example) equipped with the switch 75, the pMOS transistor 76 is provided outside the light-emitting device 10A. Moreover, the pMOS transistor 76 constituting the discharge path 18 is connected to the light-emitting device 10A via the parasitic inductance L2 (refer to Figure 11 ).

[0166] On the other hand, in the light-emitting device 1 (embodiment) using the light-emitting device 10 equipped with the discharge thyristor Z, the discharge thyristor Z constituting the discharge path 17 is formed inside the light-emitting device 10. Therefore, the inductance in the discharge path 17 is smaller than the inductance in the discharge path 18 of the comparative example. Due to the small inductance, the fall time of the current I flowing through the VCSEL becomes shorter.

[0167] In Figure 11 , the source of the pMOS transistor 76 of the switch 75 is the power supply voltage VLD (9V). When the nMOS transistor 51 of the driver 50 is turned on, the voltage at the drain of the nMOS transistor 51 is set to about 1V. In this way, a voltage of about 8V is applied between the source and drain of the turned-off pMOS transistor 76. The pMOS transistor 76 is required to be an element that operates at a high voltage.

[0168] As described above, by using a semiconductor device in which the light-emitting block 11 and the element constituting the discharge path 17 (here, the discharge thyristor Z) are integrated as in the light-emitting device 10 of the embodiment, the influence of parasitic inductance can be suppressed, and thus the light emission fall time of the light-emitting element (here, the VCSEL) becomes shorter.

[0169] [Second Embodiment]

[0170] In the light-emitting device 10 of the first embodiment, the discharge path 17 is the discharge thyristor Z, and the discharge path 17 constituted by the discharge thyristor Z is connected in parallel with the light-emitting block 11. Moreover, as Figure 3 shown, the n-cathode layer 35 of the discharge thyristor Z is exposed and an n-ohmic electrode (cathode Kz) is provided.

[0171] In the light-emitting device 20 of the second embodiment, it is not necessary to provide an n-ohmic electrode (cathode Kz) on the n-cathode layer 35 of the discharge thyristor Z.

[0172] Figure 13 is a cross-sectional view showing the cross-sectional shape of the light-emitting device 20 to which the second embodiment is applied. The upward direction on the paper surface is the z direction. For the same parts as Figure 3 , the same reference numerals are used and the description is omitted.

[0173] In the light-emitting device 20, the discharge path 19 (refer to Figure 14 described later) is composed of a discharge thyristor Z and a pseudo-VCSEL connected in series (in Figure 13 , Figure 14And below, it is expressed as P-VCSEL.) It is composed of. The P-VCSEL is composed of the same stacked semiconductor layers as the VCSEL in the light-emitting block 11. The light-emitting outlet 43 in the light-emitting block 11 is not provided in the P-VCSEL. The P-VCSEL is not used as a light-emitting element but as a diode. In other words, the P-VCSEL is the VCSEL in the light-emitting block 11, and current will flow when the series-connected discharge thyristor Z conducts. The series connection of the discharge thyristor Z and the P-VCSEL forms a discharge path 19 from the anode electrode 42 to the cathode electrode 41 (refer to Figure 14 ).

[0174] In the light-emitting device 20, there is no need to provide an n-ohmic electrode (cathode Kz) on the n-cathode layer 35 of the discharge thyristor Z in the light-emitting device 10 and connect it to the cathode pad 15. That is, there is no need for the process of exposing the n-cathode layer 35 of the discharge thyristor Z. The discharge thyristor Z has the same layer structure as the set thyristor S of the light-emitting block 11, and the P-VCSEL has the same layer structure as the set thyristor S of the light-emitting block 11. That is, in the light-emitting device 20, there is no need for a special process for forming the discharge path 19. And the light-emitting device 20 does not have the cathode pad 15 that the light-emitting device 10 has. If the P-VCSEL is composed of the same stacked semiconductor layers as the VCSEL in the light-emitting block 11, the manufacture of the light-emitting device 20 becomes easy.

[0175] The series connection of the discharge thyristor Z and the P-VCSEL forms a discharge path 19. Different from the case where the discharge path 17 is composed only of the discharge thyristor Z of the light-emitting device 10 in the first embodiment, the internal resistance of the P-VCSEL is added to the discharge path 19. However, by making the current path in the P-VCSEL thicker than that in the VCSEL in the light-emitting block 11, the internal resistance can be reduced.

[0176] If the discharge thyristor Z conducts, current flows in the P-VCSEL. At this time, when an abnormal situation such as the P-VCSEL emits light and its light transmits through the discharge thyristor Z and emits to the outside occurs, it is only necessary to set a light-shielding film on the light-emitting path using the anode electrode 42 or the like.

[0177] Figure 14 It is an equivalent circuit of the light-emitting device 2 using the light-emitting device 20 applicable to the second embodiment. For Figure 8Parts that are the same as those of the light-emitting device 1 of the light-emitting device 10 are denoted by the same reference numerals and their description is omitted. In the light-emitting device 20, the discharge path 19 is constituted by the series connection of the discharge thyristor Z and the P-VCSEL. Further, the resistor R5 is an equivalent resistor that equivalently represents the internal resistances of the discharge thyristor Z and the P-VCSEL. The series connection of the discharge thyristor Z and the P-VCSEL is connected in parallel with the light-emitting block 11 between the anode electrode 42 and the cathode electrode 41.

[0178] The light-emitting device 2 using the light-emitting device 20 operates in the same manner as the light-emitting device 1 using the light-emitting device 10 described in the first embodiment. The description of the light-emitting device 2 using the light-emitting device 20 is omitted.

[0179] In the light-emitting device 10 of the first embodiment and the light-emitting device 20 of the second embodiment, the case where the VCSEL and the setting thyristor S are sequentially stacked on the substrate 30 has been described, but the setting thyristor S and the VCSEL may be sequentially stacked on the substrate 30. At this time, as long as the discharge thyristor Z is configured in the same manner as the setting thyristor S, and the P-VCSEL in the second embodiment is configured in the same manner as the VCSEL. Further, the setting thyristor S and the VCSEL may be juxtaposed on the substrate 30 without being stacked.

[0180] In the light-emitting device 10 of the first embodiment and the light-emitting device 20 of the second embodiment, the case where the VCSEL is used as an example of the light-emitting element has been described, but a light-emitting diode LED (Light Emitting Diode) or a laser diode LD (Laser Diode) etc. may be used instead of the VCSEL. The case where the setting element is a thyristor described as the setting thyristor S and the discharge element is a thyristor described as the discharge thyristor Z has been described, but one or both of the setting element and the discharge element may be a transistor. As long as the setting element and the discharge element are integrally integrated on the semiconductor substrate together with the light-emitting element and are configured to be capable of block irradiation.

[0181] As described above, the embodiments of the present invention have been described, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clearly understood from the description of the technical solutions that embodiments obtained by making various changes or improvements to the above embodiments are also included in the technical scope of the present invention.

[0182] Moreover, various modifications can be made as long as they do not depart from the gist of the present invention.

[0183] (Supplementary Note) (((1)))

[0185] A light-emitting device includes:

[0186] A plurality of light-emitting blocks, including a light-emitting element and a setting element that sets the light-emitting element to a lit state; and

[0187] A discharge path, including a discharge element that can control discharge when the light-emitting element is off and discharges the accumulated charge when lit,

[0188] A plurality of the light-emitting blocks are electrically connected in parallel to the discharge path. ((((2)))

[0190] The light-emitting device according to (((1))), wherein

[0191] The discharge element is a thyristor. (((3)))

[0193] The light-emitting device according to (((2))), wherein

[0194] The discharge path is constituted by a thyristor, i.e., the discharge element,

[0195] In the light-emitting block, the light-emitting element is a surface-emitting laser, and the setting element is a thyristor,

[0196] The discharge path is electrically connected in parallel with respect to the series connection of the light-emitting element and the setting element. (((4)))

[0198] The light-emitting device according to (((3))), wherein

[0199] The thyristor as the setting element and the thyristor as the discharge element have the same structure of stacked semiconductor layers. (((5)))

[0201] The light-emitting device according to (((2))), wherein

[0202] The discharge path is constituted by the series connection of the discharge element and a pseudo surface-emitting laser,

[0203] In the light-emitting block, the light-emitting element is a surface-emitting laser, and the setting element is a thyristor,

[0204] The discharge path is electrically connected in parallel with respect to the series connection of the light-emitting element and the setting element. (((6)))

[0206] The light-emitting device according to (((5))), wherein

[0207] The thyristor serving as the setting element and the thyristor serving as the discharge element have stacked semiconductor layers with the same structure, and the surface-emitting laser serving as the light-emitting element and the pseudo surface-emitting laser have stacked semiconductor layers with the same structure. (((7)))

[0209] A light-emitting device includes:

[0210] A light-emitting device according to any one of ((1)) to ((6));

[0211] A driver, connected to the light-emitting device, and supplying a lighting current to the light-emitting element of the light-emitting device;

[0212] A selection unit that selects the light-emitting block to be lit in the light-emitting device and supplies a selection signal to the setting element of the selected light-emitting block;

[0213] A lighting control unit that supplies a lighting control signal for controlling the lighting period of the light-emitting element in the light-emitting device to the driver; and

[0214] A discharge control unit that supplies a discharge control signal for controlling discharge to the light-emitting device. (((8)))

[0216] The light-emitting device according to ((7)), wherein

[0217] The discharge control signal starts to become a signal voltage that turns on the discharge element when the lighting control signal becomes a signal voltage that turns off the driver. (((9)))

[0219] The light-emitting device according to ((7)) or ((8)), wherein

[0220] The width of the signal that turns on the discharge element in the discharge control signal is smaller than the width of the signal that turns on the driver in the lighting control signal. (((10)))

[0222] The light-emitting device according to any one of ((7)) to ((9)), wherein

[0223] The power supply voltage supplied to the light-emitting device is the same as the power supply voltage supplied to the discharge control unit. (((11)))

[0225] The light-emitting device according to any one of ((7)) to ((10)) includes an adjustment unit that adjusts the timing of the discharge control signal for turning on the discharge element sent by the discharge control unit according to the timing of turning off the driver in the lighting control signal and the number of the lit light-emitting blocks. (((12)))

[0227] A measuring device includes:

[0228] The light-emitting device according to any one of ((7)) to ((11)); and

[0229] A light-receiving unit that receives light emitted from the light-emitting device and reflected from a measurement object,

[0230] The measuring device measures the three-dimensional shape of the measurement object.

[0231] According to the light-emitting device according to ((1)), the fall time of the light-emitting element can be shortened compared with the case where there is no discharge path.

[0232] According to the light-emitting device according to ((2)), the switching is faster compared with the case where it is not a thyristor.

[0233] According to the light-emitting device according to ((3)), the parasitic resistance can be reduced compared with the case where the discharge path includes other elements in addition to the thyristor.

[0234] According to the light-emitting device according to ((4)), the manufacturing of the light-emitting device becomes easier compared with the case where it is not a multi-layer semiconductor layer having the same structure.

[0235] According to the light-emitting device according to ((5)), the discharge path can be made to have the same structure as the light-emitting block compared with the case where the discharge element is not connected in series with the pseudo surface-emitting laser.

[0236] According to the light-emitting device according to ((6)), the manufacturing of the light-emitting device becomes easier compared with the case where it is not a multi-layer semiconductor layer having the same structure.

[0237] According to the light-emitting device according to ((7)), a light-emitting device capable of performing block irradiation can be realized.

[0238] According to the light-emitting device according to ((8)), the power consumption can be reduced compared with the case where the discharge control signal becomes a signal voltage for turning on the discharge element when the lighting control signal is a signal voltage for turning on the driver.

[0239] According to the light-emitting device according to (((9))), power consumption can be reduced as compared with a case where the width of a signal for turning on a discharge element is greater than the width of a signal for turning on a driver.

[0240] According to the light-emitting device according to (((10))), the structure can be made simpler as compared with a case where the power supply voltage is different.

[0241] According to the light-emitting device according to (((11))), the light emission decay timing of a light-emitting element can be controlled without depending on the number of light-emitting blocks to be lit as compared with a case where no adjustment is made.

[0242] According to the measuring device according to (((12))), a measuring device based on a three-dimensional shape can be provided.

[0243] The above-described embodiments of the present invention are provided for purposes of illustration and description. In addition, the embodiments of the present invention do not comprehensively and exhaustively include the present invention and do not limit the present invention to the disclosed manner. Obviously, various modifications and variations are self-evident to those skilled in the art to which the present invention pertains. The present embodiment is selected and described in order to most easily explain the principle of the present invention and its applications. Thus, other technicians in the technical field can understand the present invention through various modified examples optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. A light-emitting device, comprising: a plurality of light-emitting blocks, including a light-emitting element and a setting element for setting the light-emitting element to a lit state; and a discharge path, including a discharge element capable of controlling discharge when the light-emitting element is extinguished, and discharging the accumulated charge during lighting, wherein the plurality of light-emitting blocks are electrically connected in parallel with the discharge path.

2. The light-emitting device according to claim 1, wherein the discharge element is a thyristor.

3. The light-emitting device according to claim 2, wherein the discharge path is constituted by the thyristor, i.e., the discharge element, in the light-emitting block, the light-emitting element is a surface-emitting laser, and the setting element is a thyristor, and the discharge path is electrically connected in parallel with the series connection of the light-emitting element and the setting element.

4. The light-emitting device according to claim 3, wherein the thyristor as the setting element and the thyristor as the discharge element have laminated semiconductor layers with the same structure.

5. The light-emitting device according to claim 2, wherein the discharge path is constituted by the series connection of the discharge element and a pseudo surface-emitting laser, in the light-emitting block, the light-emitting element is a surface-emitting laser, and the setting element is a thyristor, and the discharge path is electrically connected in parallel with the series connection of the light-emitting element and the setting element.

6. The light-emitting device according to claim 5, wherein the thyristor as the setting element and the thyristor as the discharge element have laminated semiconductor layers with the same structure, and the surface-emitting laser as the light-emitting element and the pseudo surface-emitting laser have laminated semiconductor layers with the same structure.

7. A light-emitting device, comprising: the light-emitting device according to any one of claims 1 to 6; a driver, connected to the light-emitting device and supplying a lighting current to the light-emitting element of the light-emitting device; a selection unit that selects the light-emitting block to be lit in the light-emitting device and supplies a selection signal to the setting element of the selected light-emitting block; a lighting control unit that supplies a lighting control signal for controlling the lighting period of the light-emitting element in the light-emitting device to the driver; and a discharge control unit that supplies a discharge control signal for controlling discharge to the light-emitting device.

8. The light-emitting device according to claim 7, wherein the discharge control signal starts to change to a signal voltage that turns on the discharge element when the lighting control signal changes to a signal voltage that turns off the driver.

9. The light-emitting device according to claim 7 or 8, wherein the width of the signal that turns on the discharge element in the discharge control signal is smaller than the width of the signal that turns on the driver in the lighting control signal.

10. The light-emitting device according to any one of claims 7 to 9, wherein the power supply voltage supplied to the light-emitting device is the same as the power supply voltage supplied to the discharge control unit.

11. The light-emitting device according to any one of claims 7 to 10, comprising an adjustment unit The adjustment unit adjusts the timing of the signal that turns on the discharge element in the discharge control signal transmitted by the discharge control unit according to the timing at which the driver is turned off in the lighting control signal and the number of the lit light-emitting blocks.

12. A measuring device, comprising: The light-emitting device according to any one of claims 7 to 11; and A light-receiving unit that receives the light emitted by the light-emitting device and reflected from the measurement object, The measuring device measures the three-dimensional shape of the measurement object.

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