Light-emitting device and apparatus, and measuring device

Abstract

To provide a light-emitting device or the like in which the fall time of a light-emitting element is shorter than when there is no discharge path.SOLUTION: A light-emitting device includes a plurality of light-emitting blocks each including a light-emitting element and a setting element for setting the light-emitting element to a state in which the light-emitting element can be lit, and a discharge path including a discharge element capable of controlling discharge when the light-emitting element is turned off and for discharging the charge accumulated when the light-emitting element is turned on, and the plurality of light-emitting blocks and the discharge path are electrically connected in parallel.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Patent document 1 describes a light-emitting device that includes a light-emitting section including a light-emitting element, a driving section that includes a first element connected to a cathode electrode provided on the cathode side of the light-emitting element and supplies a current that causes light to be emitted, and a capacitance section that is provided between an anode electrode and a cathode electrode provided on the anode side of the light-emitting element and is arranged in parallel with the current path that causes light to be emitted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-112924 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, ToF (Time of Flight) sensors have become mainstream as distance measuring sensors used for object recognition, etc., and their light sources use light-emitting devices that integrate light-emitting elements such as vertical cavity surface-emitting lasers (VCSELs). ToF sensors used in applications for mobile devices such as smartphones are required to achieve both high spatial resolution and low power consumption. The light-emitting elements that serve as light sources are required to have rise and fall times of less than 1 ns. If the light source has multiple blocks of light-emitting elements and uses block illumination to light up selected blocks, power consumption can be reduced compared to lighting up all light-emitting elements simultaneously. With block illumination, the unselected blocks form a capacitor and accumulate charge. The discharge of charge lengthens the fall time of the light-emitting elements. An object of the present invention is to provide a light-emitting device or the like in which the fall time of the light-emitting element is shorter than when there is no discharge path. [Means for solving the problem]

[0005] The invention described in claim 1 is a light-emitting device comprising 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 it can be lit, and a discharge path including a discharge element that can control discharge when the light-emitting element is turned off and that discharges the charge accumulated when the light-emitting element is turned on, wherein the plurality of light-emitting blocks and the discharge path are electrically connected in parallel. A second aspect of the present invention is the light-emitting device according to the first aspect, wherein the discharge element is a thyristor. The invention described in claim 3 is a light-emitting device described in claim 2, wherein the discharge path is composed of the discharge element which is a thyristor, and in the light-emitting block, the light-emitting element is a surface-emitting laser, the setting element is a thyristor, and the discharge path is electrically connected in parallel to the series connection of the light-emitting element and the setting element. A fourth aspect of the present invention is the light-emitting device according to the third aspect, wherein the thyristor serving as the setting element and the thyristor serving as the discharge element have laminated semiconductor layers of the same configuration. The invention described in claim 5 is a light-emitting device described in claim 2, wherein the discharge path is composed of a series connection of the discharge element and a pseudo-surface-emitting laser, and in the light-emitting block, the light-emitting element is a surface-emitting laser, the setting element is a thyristor, and the discharge path is electrically connected in parallel to the series connection of the light-emitting element and the setting element. The invention described in claim 6 is a light-emitting device described in claim 5, in which the thyristor serving as the setting element and the thyristor serving as the discharge element have laminated semiconductor layers of the same configuration, and the surface-emitting laser serving as the light-emitting element and the quasi-surface-emitting laser have laminated semiconductor layers of the same configuration. The invention described in claim 7 is a light-emitting device comprising: a light-emitting device described in claim 1; a driver connected to the light-emitting device and supplying a lighting current to a light-emitting element of the light-emitting device; a selection unit in the light-emitting device that selects the light-emitting block to be lit 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 to the driver that controls the lighting period of the light-emitting element in the light-emitting device; and a discharge control unit that supplies a discharge control signal to the light-emitting device that controls discharge. The invention described in claim 8 is a light-emitting device described in claim 7, in which the discharge control signal begins 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. The invention of claim 9 is the light emitting device of claim 7, 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. A tenth aspect of the present invention is the light emitting device according to any one of the seventh to ninth aspects, wherein a power supply voltage supplied to the light emitting device and a power supply voltage supplied to the discharge control unit are the same. The invention described in claim 11 is a light-emitting device described in claim 7, which is provided with an adjustment unit that adjusts the timing at which the discharge control unit sends a signal to turn on the discharge element in the discharge control signal, depending on the timing at which the driver is turned off in the lighting control signal and the number of the light-emitting blocks that are lit. The invention described in claim 12 is a measurement device that measures the three-dimensional shape of a measurement object, comprising the light-emitting device described in claim 7 and a light-receiving unit that receives light emitted by the light-emitting device and reflected from the measurement object. [Effects of the Invention]

[0006] According to the first aspect of the present invention, the fall time of the light emitting element can be made shorter than when there is no discharge path. According to the invention as set forth in claim 2, switching is faster than in the case where a thyristor is not used. According to the third aspect of the present invention, the parasitic resistance can be reduced compared to when the discharge path includes other elements in addition to the thyristor. According to the invention as set forth in claim 4, the light emitting device can be manufactured more easily than when the light emitting device does not have multiple semiconductor layers of the same configuration. According to the invention as set forth in claim 5, the discharge path can be configured in the same way as the light-emitting block, compared to when the discharge element and the pseudo surface-emitting laser are not connected in series. According to the sixth aspect of the present invention, the light emitting device can be manufactured more easily than when the light emitting device does not have multiple semiconductor layers of the same configuration. According to the seventh aspect of the present invention, a light emitting device capable of block irradiation can be realized. According to the eighth aspect of the invention, power consumption can be reduced compared to when the discharge control signal changes from a signal voltage that turns on the driver to a signal voltage that turns on the discharge element when the lighting control signal is a signal voltage that turns on the driver. According to the ninth aspect of the present invention, power consumption can be reduced compared to when the width of the signal that turns on the discharge element is greater than the width of the signal that turns on the driver. According to the invention as set forth in claim 10, the configuration can be simplified compared to when the power supply voltages are different. According to the invention of claim 11, the timing of the fall of light emission of the light emitting elements can be controlled regardless of the number of light emitting blocks that are lit, compared to when no adjustment is made. According to the invention as set forth in claim 12, a measurement device based on a three-dimensional shape can be provided. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram showing a schematic configuration of a measurement apparatus that measures the three-dimensional shape of a measurement object by a ToF method to which a first embodiment is applied. [Figure 2] 2A to 2C are diagrams illustrating an example of a planar shape of a light-emitting device to which the first embodiment is applied. [Figure 3] 1 is a cross-sectional view illustrating an example of a cross-sectional structure of a light-emitting device to which the first embodiment is applied. [Figure 4] 2 is an equivalent circuit of a light-emitting device to which the first embodiment is applied. [Figure 5] 10 is an equivalent circuit illustrating a light emitting device using a light emitting device without a discharge thyristor, to which the first embodiment is not applied. (a) is an equivalent circuit showing 24 light emitting blocks, and (b) is an equivalent circuit when one light emitting block is lit and the other light emitting blocks are turned off. [Figure 6] These are equivalent circuits illustrating the effect of parallel capacitance. (a) is a light-emitting device using a light-emitting device with one light-emitting block, and (b) is a light-emitting device using a light-emitting device with 24 light-emitting blocks. [Figure 7] This is the result of simulating the current flowing through the VCSEL using an equivalent circuit that accounts for the effect of parallel capacitance. [Figure 8] 1 is an equivalent circuit of a light emitting apparatus using a light emitting device including a discharge thyristor to which the first embodiment is applied. [Figure 9] 10 is a timing chart illustrating the lighting control signal and the discharge control signal used in the simulation, where (a) shows the lighting control signal and (b) shows the discharge control signal. [Figure 10] 10 shows the results of simulating the current flowing through a VCSEL in a light emitting apparatus using a light emitting device including a discharge thyristor, to which the first embodiment is applied. [Figure 11] 1 is an equivalent circuit illustrating a light emitting device (comparative example) equipped with a switch. [Figure 12] 1 shows the results of simulating the current flowing through the VCSEL in a light emitting device (Example) using a light emitting device with a discharge thyristor, and in a light emitting device (Comparative Example) with a switch. [Figure 13] FIG. 10 is a cross-sectional view illustrating the cross-sectional shape of a light-emitting device to which the second embodiment is applied. [Figure 14] 10 is an equivalent circuit of a light emitting apparatus using a light emitting device to which the second embodiment is applied. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals may be used for components having similar functions. Also, some components may be given reference numerals, while similar components may not be given reference numerals.

[0009] A ToF sensor used for object recognition, etc., is an example of a measurement device that measures the three-dimensional shape of an object based on the distance to the object measured using the ToF method. Hereinafter, the ToF sensor will be described as a measurement device. A measurement device that measures three-dimensional shapes, etc. using the ToF method measures the distance to the object based on the time from when light is emitted from a light-emitting device included in the measurement device to when the emitted light is reflected by the object and received by a three-dimensional sensor (hereinafter, sometimes referred to as a "3D sensor") included in the measurement device, thereby measuring the three-dimensional shape. The 3D sensor is an example of a light-receiving unit.

[0010] There are two types of ToF methods: indirect ToF (iToF), which measures time from the difference between the phase of emitted light and the phase of received light, and direct ToF (dToF), which directly measures the time from light emission to reception. The ToF method requires that the emitted light rises and falls sharply, in other words, that the rise time and fall time be short. In particular, the direct ToF method requires shorter rise time and fall time than the indirect ToF method. Here, the direct ToF method and the indirect ToF method will not be distinguished and will be described as the ToF method.

[0011] The three-dimensional shape of an object to be measured is sometimes referred to as a "three-dimensional image" or "3D shape." Measuring three-dimensional shapes is sometimes referred to as "three-dimensional measurement," "3D measurement," or "3D sensing."

[0012] The configurations, functions, methods, etc. described below as embodiments of the present invention can be applied to face authentication in information processing devices such as mobile devices, augmented reality (AR), and other three-dimensional measurements. Furthermore, the configurations, functions, methods, etc. described as embodiments of the present invention can be used not only for three-dimensional measurement but also for simply measuring the distance to a measurement object.

[0013] [First embodiment] (Measuring device 100) 1 is a block diagram showing a schematic configuration of a measurement device 100 that measures the three-dimensional shape of a measurement object using a ToF method to which the first embodiment is applied. The measurement device 100 includes a light emitting device 1 and a 3D sensor 7. The measurement device 100 may also include a control unit 8 that controls the light emitting device 1 and the 3D sensor 7. Furthermore, the measurement device 100 may also include a three-dimensional shape measurement unit 9 that measures the three-dimensional shape of the measurement object based on the distance to the measurement object.

[0014] The light emitting device 1 includes a light emitting device 10, a driver 50, a lighting control unit 60, a discharge control unit 70, an adjustment unit 80, and a selection unit 90.

[0015] As will be described later, light-emitting device 10 includes a plurality of light-emitting blocks 11. Each light-emitting block 11 includes a light-emitting element. In the following description, the light-emitting element is described as a vertical-cavity surface-emitting laser (VCSEL). A vertical-cavity surface-emitting laser is referred to as a VCSEL. Here, one light-emitting point (or spot) is referred to as a VCSEL. Light-emitting block 11 includes at least one VCSEL (see FIG. 2, which will be described later). When 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-spot VCSEL. A vertical-cavity surface-emitting laser (VCSEL) is an example of a light-emitting element and an example of a surface-emitting laser.

[0016] When the driver 50 transitions from off to on, it supplies current to light up the VCSELs in the light-emitting blocks 11. When the driver 50 transitions from on to off, it cuts off the current to turn off the VCSELs in the light-emitting blocks 11. The period during which the driver 50 is on is the light-on period.

[0017] The lighting control unit 60 supplies a signal that controls the on / off of the driver 50 to the driver 50. Hereinafter, the signal that controls the on / off of the driver 50 will be referred to as a lighting control signal.

[0018] The discharge control unit 70 supplies a signal that controls the discharge of the accumulated charge when the light-emitting block 11 is turned on to the light-emitting device 10. Hereinafter, the signal that controls the discharge will be referred to as a discharge control signal.

[0019] The adjustment unit 80 adjusts the timing of supplying a signal to start discharge in the discharge control signal according to the timing of turning off the light-emitting blocks 11 in the lighting control signal and the number of light-emitting blocks 11 that are lit.

[0020] The selection unit 90 selects a light-emitting block 11 to be lit from the plurality of light-emitting blocks 11, and supplies a signal that sets the VCSEL of the light-emitting block 11 to a state where it can be lit to the selected light-emitting device 10. Hereinafter, the signal that sets the VCSEL of the selected light-emitting block 11 to be lit to a state where it can be lit will be referred to as a selection signal.

[0021] The control unit 8 controls the light emitting device 1 and the 3D sensor 7. The control of the control unit 8 may include a function of measuring the distance to the measurement object based on the time measured by the 3D sensor 7. The three-dimensional shape measurement unit 9 acquires the distance to the measurement object from the control unit 8 and measures the three-dimensional shape of the measurement object.

[0022] The control unit 8 is configured as a computer including, for example, a CPU, a ROM, a RAM, etc. The ROM includes a non-volatile rewritable memory, for example, a flash memory. A program stored in the ROM is loaded into the RAM, and the CPU executes the program to control the light emitting device 1 and the 3D sensor 7.

[0023] 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 similarly to the control unit 8. Furthermore, the control unit 8 may include any or all of the lighting control unit 60, the discharge control unit 70, the adjustment unit 80, and the selection unit 90.

[0024] The three-dimensional shape measurement unit 9 has the same configuration as the control unit 8, and measures the three-dimensional shape of the measurement object from the distance to the measurement object. The control unit 8 may also have the function of the three-dimensional shape measurement unit 9.

[0025] (Planar shape of light-emitting device 10) 2 is a diagram illustrating 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 is the x-direction, the upward direction of the paper is the y-direction, and the surface direction of the paper is the z-direction. The planar shape is the shape of the surface side of the substrate 30 (shape in the xy plane), which will be described later, and the cross-sectional shape is the shape of a cross section perpendicular to the substrate 30, which will be described later.

[0026] The light emitting device 10 is made of, for example, a GaAs-based compound semiconductor. As shown in a cross-sectional view (see FIG. 3) described later, the light emitting device 10 is configured by stacking multiple semiconductor layers on a substrate 30. The multiple stacked semiconductor layers are referred to as a stacked semiconductor layer.

[0027] The light-emitting device 10 includes a plurality of light-emitting blocks 11 provided on a 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.

[0028] In FIG. 2, the light emitting device 10 includes, as an example, 24 light emitting blocks 11. Six light emitting blocks 11 are arranged in the x direction and four in the y direction. The planar shape (shape on the xy plane) of the light emitting blocks 11 is, as an example, a square. The semiconductor layer between the light emitting blocks 11 (portions indicated by dashed lines in FIG. 2) is removed by mesa etching, and the light emitting blocks 11 are electrically isolated from each other. The light emitting block 11 located at the top left end of the page is assigned a reference number, and reference numbers are omitted for the other light emitting blocks 11.

[0029] The light-emitting block 11 is configured by stacking a light-emitting element (here, a VCSEL) and a setting thyristor S in this order on a substrate 30. The cathode of the VCSEL is located on the substrate 30 side, and the anode of the setting thyristor S is located on the side farther from the substrate 30. A cathode electrode 41 (denoted as 30 (41) in FIG. 2) is provided on the back surface of the substrate 30. The cathode electrode 41 is sometimes called a back surface electrode. The setting thyristor S is an example of a setting element.

[0030] As an example, the light-emitting block 11 includes eight VCSELs. One setting thyristor S is provided on each of the eight VCSELs. The light-emitting block 11 has three positions in the x direction and three in the y direction where VCSELs can be placed, spaced at equal intervals. However, in one location, no VCSEL is placed, and instead a gate Gs of the setting thyristor S is provided. The gate Gs of the setting thyristor S is connected to a selection signal pad 12. The selection signal pad 12 is connected to the selection unit 90 shown in FIG. 1.

[0031] The discharge thyristor Z has a configuration similar to that of the setting thyristor S, and its gate Gz is connected to a discharge signal pad 14. The discharge signal pad 14 is connected to the discharge control unit 70 shown in FIG. 1. The cathode Kz of the discharge thyristor Z is connected to a cathode pad 15. The cathode pad 15 connects the cathode Kz of the discharge thyristor Z to a cathode electrode 41 provided on the back surface of the substrate 30.

[0032] The anode As of the setting thyristor S and the anode Az of the discharge thyristor Z are connected to an anode electrode 42. The anode electrode 42 is connected to an anode pad 13 provided continuously on the ±x direction side of the substrate 30 where no light-emitting block 11 is provided. In FIG. 2, the anode electrode 42 and the anode pad 13 are indicated by a dashed dotted line. In addition, the anode As of the setting thyristor S and the anode Az of the discharge thyristor Z are covered by a single anode electrode 42. A DC voltage is supplied to the anode pad 13 from a power supply VLD. The DC voltage supplied by the power supply VLD is referred to as a power supply voltage VLD. The cathode electrode 41 is connected to the driver 50 shown in FIG. 1.

[0033] Although the light-emitting device 10 is described as including 24 light-emitting blocks 11, it may be provided with a number of light-emitting blocks 11 other than 24. Although the light-emitting block 11 is described as including eight VCSELs, it may be provided with a number of VCSELs other than eight. It is sufficient that the light-emitting block 11 includes at least one VCSEL. The arrangement of the light-emitting blocks 11, or the VCSELs, may be an arrangement other than that shown in FIG. 2. Although the light-emitting device 10 is described as including one discharge thyristor Z, it may be provided with multiple discharge thyristors Z.

[0034] (Cross-sectional structure of light-emitting device 10) FIG. 3 is a cross-sectional view illustrating an example of the cross-sectional structure of a light-emitting device 10 to which the first embodiment is applied. The upward direction on the paper surface is the z direction. FIG. 3 shows three light-emitting blocks 11 (light-emitting blocks 11-1 to 11-3 in FIG. 3) and a discharge thyristor Z. Each light-emitting block 11 includes one VCSEL. If each light-emitting block 11 includes multiple VCSELs, multiple light emission openings 43 may be provided in the light-emitting block 11.

[0035] First, a description will be given of the light-emitting block 11. The light-emitting block 11 is configured by stacking a VCSEL and a setting thyristor S on a substrate 30 in this order.

[0036] The VCSEL is configured by stacking 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, for example. The n-cathode layer 31 is, for example, a distributed Bragg reflector (DBR) made of alternating 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, like the n-cathode layer 31, is, for example, an upper distributed Bragg reflector made of alternating 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 stacked semiconductor layers that constitute the VCSEL.

[0037] A tunnel junction layer 34 is laminated on the p-anode layer 33 . The setting thyristor S is configured by stacking 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 a 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 setting 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, the setting thyristor S is a thyristor configured with 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 stacked semiconductor layers that constitute the setting thyristor S. 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 a stacked semiconductor layer.

[0038] The p-anode layer 38, n-gate layer 37, p-gate layer 36, n-cathode layer 35, and tunnel junction layer 34 of the setting thyristor S stacked above the VCSEL are removed by etching to expose the p-anode layer 33, thereby forming a light emitting aperture 43 for emitting light from the VCSEL. The setting thyristor S is composed of the n-cathode layer 35, p-gate layer 36, n-gate layer 37, and p-anode layer 38, which surround the light emitting aperture 43 of the VCSEL.

[0039] A p-type ohmic electrode (p ohmic electrode) in 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 setting thyristor S. Hereinafter, this will be referred to as an anode As. A portion of the p anode layer 38 is removed by etching to expose the n gate layer 37, and an n-type ohmic electrode (n ohmic electrode) in ohmic contact with the n gate layer 37 is provided on this n ohmic electrode. This n ohmic electrode is the gate terminal of the setting thyristor S. Hereinafter, this will be referred to as a gate Gs.

[0040] The light-emitting layers 32, p-anode layers 33, tunnel junction layers 34, n-cathode layers 35, p-gate layers 36, n-gate layers 37, and p-anode layers 38 are removed by etching (mesa etching) between the light-emitting blocks 11, thereby electrically isolating the blocks.

[0041] An insulating layer 39 is provided on the separated light-emitting blocks 11. An anode electrode 42 is provided, which is connected to the p-ohmic electrode (anode As of the setting thyristor S) on the p-anode layer 38 via a through-hole provided in the insulating layer 39. The anode electrode 42 is connected to the anode pad 13.

[0042] On the other hand, the n-ohmic electrode (gate Gs of the setting thyristor S) on the n-gate layer 37 is connected to the select signal pad 12 via a through-hole provided in the insulating layer 39. In FIG. 3, the gate Gs is shown as being connected to the select signal pad 12 through the p-anode layer 38, but the p-anode layer 38 in the portion where the gate Gs is provided is removed.

[0043] A cathode electrode 41 is provided on the rear surface (−z direction side) of the substrate 30, and is in ohmic contact with the substrate 30. The cathode electrode 41 is connected to a driver 50.

[0044] As described above, the VCSEL and setting thyristor S of the light-emitting block 11 are connected in series between the cathode electrode 41 and anode electrode 42 on the VCSEL side. A plurality of light-emitting blocks 11 are connected in parallel between the cathode electrode 41 and anode electrode 42.

[0045] 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 positive (+) and the cathode electrode 41 negative (-), a reverse bias is created 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. The tunnel junction layer 34 makes it easy for current to flow even when a reverse bias relationship is created 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 is made of p-type conductors such as GaAs or AlGaAs doped with a high concentration of p-type impurities on the side of the p anode layer 33 of the VCSEL. ++ layer and an n-type impurity-doped GaAs, AlGaAs, or the like on the side of the n-cathode layer 35 of the setting thyristor S. ++ In the tunnel junction layer 34, the width of the depletion region is narrow, so even in a reverse bias state, ++ From the conduction band on the layer side to p ++ Electrons tunnel into the valence band on the layer side, which makes it easier for current to flow from the n-cathode layer 35 of the setting thyristor S to the p-anode layer 33 of the VCSEL. The VCSEL and setting thyristor S are stacked via a tunnel junction layer 34, and are connected in series.

[0046] The p anode layer 33 includes a current confinement layer. The current confinement layer is made of an AlAs layer or the like, which has a faster oxidation rate than AlGaAs. The portion surrounding the light emission aperture 43 is oxidized to form a current blocking portion β, and the portion surrounding the light emission aperture 43 is made into a non-oxidized current passing portion α. The current confinement layer concentrates current in the center of the VCSEL resonator structure.

[0047] Next, the discharge thyristor Z will be described. The discharge thyristor Z is configured by stacking 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 the cathode, the p-gate layer 36 functions as the p-gate, the n-gate layer 37 functions as the n-gate, and the p-anode layer 38 functions as the anode. Here, the discharge thyristor Z is referred to as a discharge thyristor S, but it is a thyristor configured with 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 stacked semiconductor layers that constitute the discharge thyristor Z. The stacked semiconductor layers that constitute the discharge thyristor Z are the same as the stacked semiconductor layers that constitute the setting thyristor S. This facilitates the manufacture of the light-emitting device 10. 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 constitute the VCSEL in the light-emitting block 11.

[0048] On the p anode layer 38, a p-type ohmic electrode (p ohmic electrode) in ohmic contact with the p anode layer 38 is provided. This p ohmic electrode is the anode terminal of the discharge thyristor Z. Hereinafter, this will be referred to as anode Az. On the n gate layer 37 exposed by removing a portion of the p anode layer 38 by etching, an n-type ohmic electrode (n ohmic electrode) in ohmic contact with the n gate layer 37 is provided. This n ohmic electrode is the gate terminal of the discharge thyristor Z. Hereinafter, this will be referred to as gate Gz. Furthermore, an n ohmic electrode is provided on the n cathode layer 35 exposed by removing a portion of the p anode layer 38, the n gate layer 37, and the p gate layer 36 by etching. This n ohmic electrode is the cathode electrode of the discharge thyristor Z. Hereinafter, this will be referred to as cathode Kz.

[0049] The discharge thyristor Z and the light-emitting block 11 are electrically isolated from each other 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, just like between the light-emitting blocks 11.

[0050] The p-ohmic electrode (anode Az of the discharge thyristor Z) on the p-anode layer 38 is connected to the anode electrode 42 via a through-hole provided in the insulating layer 39.

[0051] 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 to the light-emitting block 11 between the cathode electrode 41 and the anode electrode 42.

[0052] 3, an n-ohmic electrode is provided on the n-cathode layer 35 to form the cathode Kz of the discharge thyristor Z. In the discharge thyristor Z, the p-anode layer 33 may be exposed and a p-ohmic electrode may be provided on the p-anode layer 33 to form 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. In this way, the etching step for providing the cathode Kz of the discharge thyristor Z becomes the same as the step for providing the light emission aperture 43 of the light-emitting block 11, and the step of exposing the n-cathode layer 35 becomes unnecessary.

[0053] (Equivalent circuit of light-emitting device 10) Fig. 4 is an equivalent circuit of the light-emitting device 10 to which the first embodiment is applied. In Fig. 4, the light-emitting device 10 includes 24 light-emitting blocks 11 (light-emitting blocks 11-1 to 11-24 in Fig. 4) and a discharge thyristor Z. In Fig. 4, in addition to the light-emitting device 10, a power supply VLD and a driver 50 are also shown.

[0054] In FIG. 4, the setting thyristor S and the discharge thyristor Z are represented by a combination of a pnp transistor and an npn transistor. The light-emitting block 11 is configured by connecting a setting thyristor S and a VCSEL in series. The cathode of the setting thyristor S (the emitter of the npn transistor) is connected to the anode of the VCSEL. The anode As (the emitter of the pnp transistor) of the setting thyristor S is connected to the anode electrode 42, and the cathode of the VCSEL is connected to the cathode electrode 41 via a resistor R1. The resistor R1 is an equivalent resistor that represents the internal resistance of the setting thyristor S and the VCSEL.

[0055] A plurality of light-emitting blocks 11 are connected in parallel between an anode electrode 42 and a cathode electrode 41 .

[0056] The discharge thyristor Z has an anode Az (emitter of the pnp transistor) connected to the anode electrode 42, and a cathode Kz connected to the cathode pad 15 via a resistor R2. The cathode pad 15 is connected to the cathode electrode 41 outside the light-emitting device 10.

[0057] The anode pad 13 is connected to the power supply VLD via a parasitic inductance L1. The cathode electrode 41 is connected to the driver 50 via a parasitic inductance L2. The parasitic inductance L1 is an inductance that parasitic on the wiring that connects the light-emitting device 10 to the power supply VLD when the light-emitting device 10 is mounted on the light-emitting apparatus 1. The parasitic inductance L2 is an inductance that parasitic on the wiring that connects the light-emitting device 10 to the driver 50. In addition to inductance, resistance and capacitance occur in the wiring that connects these, but the influence of inductance is greatest. In Figure 4, the inductances that have the greatest influence are denoted as parasitic inductances L1 and L2.

[0058] The driver 50 is, for example, an n-channel MOS transistor (nMOS transistor) 51, and drives the light-emitting block 11 with a constant current. The nMOS transistor 51 of the driver 50 has a source grounded and a drain connected to the cathode electrode 41. The light-emitting device 10 is so-called low-side driven.

[0059] Here, the turning on and off of the VCSEL in the light-emitting block 11 will be described. The turning on and off of the VCSEL in the light-emitting block 11 will be referred to as the turning on and off of the light-emitting block 11. The voltage of each signal is shown in parentheses as an example. The forward voltage of the pn junction is assumed to be 1.5 V. When a voltage of 1.5 V or more is applied to the pn junction, it becomes forward biased, allowing current to flow easily, and when a voltage of less than 1.5 V is applied, it becomes reverse biased, preventing current from flowing easily. When a voltage is applied between the anode (emitter of a pnp transistor) and the cathode (emitter of an npn transistor), a thyristor turns on when a forward bias occurs between the anode (emitter of the pnp transistor) and the gate (base of the pnp transistor). This turns on the npn transistor. This turns the thyristor on. The transition of a thyristor from an off state to an on state is referred to as turning on.

[0060] A state in which none of the light-emitting blocks 11 are lit and before a light-emitting block 11 to be lit is selected is called an initial state. In the initial state, a power supply voltage VLD (9V) is applied from the power supply VLD to the anode pad 13 of the light-emitting device 10. As a result, the cathode electrode 41 is at the power supply voltage VLD (9V). A selection signal (9V) that does not select any of the light-emitting blocks 11 is supplied from the selection unit 90 to all selection signal pads 12. The selection signal (9V) is the same as the power supply voltage VLD (9V) applied to the anode As of the setting thyristor S. In addition, the emitter (anode As of the setting thyristor S) and 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, the emitter (anode As of setting thyristor S) and base (gate Gs of setting thyristor S) of the pnp transistor of setting thyristor S are not forward biased.

[0061] The lighting control signal (0V) that turns off the nMOS transistor 51 of the driver 50 is supplied to the driver 50 from the lighting control unit 60. Because the nMOS transistor 51 of the driver 50 is off, the cathode electrode 41 of the light-emitting device 10 is at the power supply voltage VLD (9V). The cathode (emitter of the npn transistor) of the setting thyristor S and the anode of the VCSEL are at the power supply voltage VLD (9V). The anode (emitter of the pnp transistor) and cathode (emitter of the npn transistor) of the setting thyristor S are at the same potential (power supply voltage VLD (9V)).

[0062] A case will be described in which one light-emitting block 11, in this case, light-emitting block 11-1, is turned on. The selection unit 90 supplies a selection signal (7V) that selects the light-emitting block 11-1 to the selection signal pad 12 of the light-emitting block 11-1. Then, the voltage of the gate Gs of the setting thyristor S of the light-emitting block 11-1 becomes 7V, and a forward bias is applied between the emitter (anode As of the setting thyristor S) and base (gate Gs of the setting thyristor S) of the pnp transistor. This sets the setting thyristor S to a state in which it can be turned on (a turn-on possible state). Note that the anode (emitter of the pnp transistor) and cathode (emitter of the npn transistor) of the setting thyristor S are at the same potential (power supply voltage VLD (9V)), so the setting thyristor S does not turn on. This state is referred to as a turn-on possible state. Note that when the setting thyristor S turns on, a current flows through the VCSEL, causing it to emit light. When the setting thyristor S is in a state where it can be turned on, the VCSEL is in a state where it can emit light. Therefore, we will refer to the setting thyristor S as the element that sets the VCSEL to a state where it can emit light. The selection signal (7V) is a value set in consideration of the forward voltage (1.5V) of the pn junction relative to the power supply voltage VLD of 9V.

[0063] Here, when a lighting signal (1.2 V) that turns on the nMOS transistor 51 is supplied from the lighting control unit 60 to the driver 50, the nMOS transistor 51 transitions from off to on. Then, the voltage of the cathode electrode 41 (cathode voltage) is pulled toward the ground voltage (0 V). Then, the setting thyristor S that can be turned on in the light-emitting block 11-1 is turned on. Then, current flows to the VCSEL via the setting thyristor S, causing the VCSEL to emit 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 1 V. The lighting signal (1.2 V) is higher than the threshold voltage of the nMOS transistor 51 of the driver 50 and is a voltage that turns on the nMOS transistor 51.

[0064] Next, a case where the lit light-emitting block 11-1 is turned off will be described. The lighting control unit 60 supplies a lighting control signal (0V) that turns off the nMOS transistor 51 of the driver 50. When the nMOS transistor 51 transitions from on to off, the current that had been flowing to the VCSEL via the setting thyristor S is cut off, and the VCSEL stops emitting light. That is, the light-emitting block 11-1 turns off. Note that as long as the selection signal (7V) is supplied to the gate Gs of the setting thyristor S of the light-emitting block 11-1, the setting thyristor S remains in a state that allows it to be turned on. When the lighting control unit 60 supplies a lighting control signal (1.2V) that turns on the nMOS transistor 51 of the driver 50, the setting thyristor S of the light-emitting block 11-1 turns on, and 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) that does not select the light-emitting block 11-1 while the light-emitting block 11-1 is lit, then after the light-emitting block 11-1 is turned off, even if the lighting control signal (1.2V) that turns on the nMOS transistor 51 of the driver 50 is supplied from the lighting control unit 60, the setting thyristor S of the light-emitting block 11-1 will not be turned on, and the light-emitting block 11-1 will not be lit again.

[0065] The setting thyristor S in the ON state does not transition to the OFF state even when the selection signal supplied to the gate Gs transitions from a selected selection signal (7V) to a non-selected selection signal (9V). The setting thyristor S transitions to the OFF state when no current is flowing. For this reason, it is advisable to change the selected selection signal (7V) to a non-selected selection signal (9V) when the nMOS transistor 51 of the driver 50 transitions from ON to OFF and current is flowing through the setting thyristor S, or after the current stops flowing.

[0066] Next, a case where the light-emitting block 11-1 is maintained in an off state (off state) will be described. The selection unit 90 simply maintains the supply of a selection signal (9V) that does not select the light-emitting block 11-1. When the selection signal (9V) is supplied to the light-emitting block 11-1, as described above, the setting thyristor S does not enter a state in which it can be turned on. Even if the lighting control unit 60 supplies a lighting signal (1.2V) that turns on the nMOS transistor 51 of the driver 50 and the nMOS transistor 51 of the driver 50 transitions from off to on, the setting thyristor S of the light-emitting block 11-1 does not turn on and no current flows through the VCSEL. In other words, the light-emitting block 11-1 maintains the off state.

[0067] As described above, among the plurality of light emission blocks 11, the light emission blocks 11 to be lit are selected by supplying a selection signal (7V) to the light emission blocks 11. The number of light emission blocks 11 to be lit simultaneously may be one, more than one, or all of them.

[0068] (Light-emitting device 10A without discharge thyristor Z) Before describing the discharge thyristor Z in the light-emitting device 10 to which the first embodiment is applied, a problem that occurs when block irradiation is performed using a light-emitting device 10A that does not include the discharge thyristor Z will be described.

[0069] 5A and 5B are equivalent circuits illustrating a light emitting apparatus 1A to which the first embodiment is not applied, using a light emitting device 10A that does not include a discharge thyristor Z. Fig. 5A is an equivalent circuit showing 24 light emitting blocks 11, and Fig. 5B is an equivalent circuit in the case where one light emitting block 11 is lit and the other light emitting blocks 11 are turned off.

[0070] 5(a) shows the configuration of FIG. 4 except for the discharge thyristor Z. Note that a selection unit 90 that supplies a selection signal is shown instead of the selection signal pad 12. Since the rest is the same as in FIG. 4, the same reference numerals are used and the description will be omitted.

[0071] In FIG. 5(b), one light-emitting block 11 (light-emitting block 11-1 in FIG. 5(b)) is turned on, and the other light-emitting blocks 11 (light-emitting blocks 11-2 to 11-24 in FIG. 5(a)) are turned off.

[0072] As shown in FIG. 5(a), each light-emitting block 11 is connected in parallel between the anode electrode 42 and the cathode electrode 41. The light-emitting block 11 is a series connection of a setting thyristor S and a VCSEL. When the light-emitting block 11-1 is turned on, current flows from the anode electrode 42 to the cathode electrode 41 via the light-emitting block 11-1, causing the VCSEL to emit light. At this time, no current flows through the other light-emitting blocks 11-2 to 11-24. However, because the other light-emitting blocks 11-2 to 11-24 are located between the anode electrode 42 and the cathode electrode 41, they become capacitance, that is, parasitic capacitance. This capacitance is connected in parallel with the light-emitting block 11-1. Therefore, in FIG. 5(b), the other light-emitting blocks 11-2 to 11-24 are represented as parallel capacitance C1. Resistor R3 is an equivalent resistance that equivalently represents the internal resistance of the other light-emitting blocks 11-2 to 11-24.

[0073] FIG. 6 is an equivalent circuit illustrating the influence of the parallel capacitance C1. FIG. 6(a) shows a light emitting device 1B using a light emitting device 10B having one light emitting block 11, and FIG. 6(b) shows a light emitting device 1A using a light emitting device 10A having 24 light emitting blocks 11. In the light emitting device 1B of FIG. 6(a), one light emitting block 11 is lit. In FIG. 6(a), the parallel capacitance C1 shown in FIG. 5(b) is not provided. In the light emitting device 1A of FIG. 6(b), one light emitting block 11 is lit, and the other 23 light emitting blocks 11 are turned off. FIG. 6(b) is the same as FIG. 5(b).

[0074] The current flowing through the VCSEL was determined by simulation. The light emission state of the VCSEL can be determined by the current flowing through the VCSEL. In the simulation, as shown in Figures 6(a) and 6(b), the power supply voltage VLD was set to 9 V, the parasitic inductance L1 was set to 0.6 nH, the parasitic inductance L2 was set to 0.3 nH, and the resistance R1 was set to 6 Ω. Furthermore, as shown in Figure 6(b), the parallel capacitance C1 was set to 75 pF and the resistance R3 was set to 0.26 Ω.

[0075] 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 Figure 9(a) described below, with an amplitude of 1.2 V, a pulse width W1 of 5 ns, and a rise time and a fall time of 0.5 ns.

[0076] FIG. 7 shows the results of a simulation of the current I flowing through the VCSEL using an equivalent circuit that explains the effect of the parallel capacitance C1. The horizontal axis represents time t (ns), and the vertical axis represents the current I(VCSEL) flowing through the VCSEL. In the light emitting device 1B (represented as "1 light emitting block" in FIG. 7) using the light emitting device 10B with one light emitting block 11 shown in FIG. 6(a), the rise and fall times of the current I(VCSEL) flowing through the VCSEL are short. The fall time is approximately 50 ns. On the other hand, in the light emitting device 1A (represented as "24 light emitting blocks" in FIG. 7) using the light emitting device 10A with 24 light emitting blocks 11, the rise of the current I(VCSEL) flowing through the VCSEL is delayed and the fall time is long compared to the light emitting device 1B ("1 light emitting block"). Because the fall time is long, the VCSEL continues to emit light for a long time. In other words, the VCSEL emission lingers for a long time.

[0077] The reason why the light emitting device 1A ("24 light-emitting blocks") rises later than 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 turns on first charges the parallel capacitance C1 and then flows to the VCSEL. The reason why the current I(VCSEL) flowing to the VCSEL rises so quickly is because the response of the parasitic inductances L1 and L2 in the current path, in particular the effect of the voltage on the cathode electrode 41 side dropping from 9 V to 1 V (voltage drop), is mitigated while the parallel capacitance C1 is being charged.

[0078] The reason why the fall time of light emitting device 1A ("24 light-emitting blocks") is longer than that of light emitting device 1B ("1 light-emitting block") is because the charge accumulated in parallel capacitance C1 is discharged via the VCSEL with a time constant determined by resistors R1 and R2 and the parallel capacitance C1. In addition, the charge accumulated in parallel capacitance C1 is discharged via path 16 shown by the dashed line in Figure 6(b). Path 16 includes light-emitting block 11-1, which includes the lit VCSEL. This causes the light emission of the VCSEL to have a long tail. In light emitting device 1B ("1 light-emitting block"), the parasitic capacitance that needs to be discharged is small, so the current flowing through the VCSEL decreases rapidly.

[0079] As described above, in block illumination, all light-emitting blocks 11 that are not lit become parallel capacitance C1. The parallel capacitance C1 ranges from several pF to 100 pF or more. Such parallel capacitance C1 results in a fall time of several ns, impairing the fall characteristics of the light-emitting device 1.

[0080] (Light-emitting device 1 using light-emitting device 10 equipped with discharge thyristor Z) 8 is an equivalent circuit diagram of a light emitting device 1 to which the first embodiment is applied, the light emitting device 10 including a discharge thyristor Z. In FIG. 8, the light emitting device 1 includes the light emitting device 10, a driver 50, a lighting control unit 60, and a discharge control unit 70.

[0081] The light-emitting device 10 is assumed to include 24 light-emitting blocks 11. One light-emitting block 11 (light-emitting block 11-1 in FIG. 8) is selected and turned on, and the other light-emitting blocks 11 (light-emitting blocks 11-2 to 11-24) are turned off. As described above, the light-emitting block 11-1 is represented by a series connection of a setting thyristor S, a VCSEL, and a resistor R1. An off light-emitting block 11 is represented by a series connection of a parallel capacitance C1 and a resistor R3. The discharge thyristor Z and a resistor R2 equivalently representing the internal resistance of the discharge thyristor Z are connected in series.

[0082] The series connection of the setting thyristor S, VCSEL, and resistor R1, the series connection of the parallel capacitance C1 and resistor R3, and the series connection of the discharge thyristor Z and resistor R2 are connected in parallel between the cathode electrode 41 and the anode electrode 42. Note that the resistors R1, R2, and R3 are parasitic resistors, and therefore the light-emitting block 11 in which the setting thyristor S and VCSEL are connected in series and the discharge thyristor Z are connected in parallel.

[0083] The power supply VLD supplies the power supply voltage VLD to the anode electrode 42 via a parasitic inductance L1. The drain of the nMOS transistor 51 of the driver 50 is connected to the cathode electrode 41 via a parasitic inductance L2. The source of the nMOS transistor 51 of the driver 50 is grounded. A lighting control signal is supplied to the gate of the nMOS transistor 51 of the driver 50 from the lighting control unit 60. The nMOS transistor 51 of the driver 50 is controlled to be turned on or off by the lighting control signal.

[0084] 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) that controls the on / off of the nMOS transistor 71. The drain of the nMOS transistor 71 is connected to one terminal of the resistor R4. 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 gate of the nMOS transistor 71 is connected to the nMOS transistor control circuit 72. The nMOS transistor control circuit 72 supplies the nMOS transistor control signal that turns the nMOS transistor 71 on / off.

[0085] The gate Gz of the discharge thyristor Z is connected to the connection point between the drain of the nMOS transistor 71 of the discharge control unit 70 and the resistor R4 via a parasitic inductance L3. The parasitic inductance L3 is an inductance parasitic on the wiring connecting the discharge control unit 70 to the discharge signal pad 14 to which the gate Gz of the discharge thyristor Z is connected. 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 a discharge control signal, and is supplied to the gate Gz of the discharge thyristor Z.

[0086] The discharge thyristor Z operates in the same manner as the setting thyristor S described above. When a voltage is applied between the anode Az and cathode Kz of the discharge thyristor Z, and a forward bias is applied between the emitter (anode Az) and base (gate Gz) of the pnp transistor of the discharge thyristor Z, the discharge thyristor Z, which is 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. When the base (gate Gz) of the pnp transistor becomes 7.5V (9V - 1.5V) or lower, a forward bias is applied between the emitter (anode Az) and base (gate Gz) of the pnp transistor, and the discharge thyristor Z turns on. Conversely, if the base (gate Gz) of the pnp transistor exceeds 7.5V, the discharge thyristor Z does not become forward biased between the emitter (anode Az) and base (gate Gz) of the pnp transistor, and does not turn on.

[0087] When a voltage is applied between the anode Az and cathode Kz of the discharge thyristor Z, if the nMOS transistor 71 of the discharge control unit 70 is off, 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. When 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, when 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 toward the ground potential (0V). In this case, the discharge control signal changes toward 0V. When the discharge control signal drops to a voltage that turns on the discharge thyristor Z, the discharge thyristor Z turns on. Note that the discharge thyristor Z turns on even if the discharge control signal does not become 0V. Thyristors switch quickly from the off state to the on state.

[0088] In the light emitting device 1, when the light emitting block 11 (light emitting block 11-1 in FIG. 8) of the light emitting device 10 is turned off, the discharge thyristor Z is turned on. During the period when the light emitting block 11-1 was lit, the cathode electrode 41 is 1 V and the anode electrode 42 is at the power supply voltage VLD (9 V). When the light emitting block 11-1 is turned off and the discharge thyristor Z is turned on, the charge accumulated in the parallel capacitance C1 during the period when the light emitting block 11-1 was lit is discharged through the discharge path 17 via the discharge thyristor Z. Then, the cathode electrode 41 rises toward the power supply voltage VLD (9 V). When the cathode electrode 41 reaches the power supply voltage VLD (9 V), the anode Az and cathode Kz of the discharge thyristor Z become the same power supply voltage VLD (9 V), and the discharge thyristor Z is turned off. In the light emitting device 10, the discharge path 17 is composed of the discharge thyristor Z. Although discharge also occurs via the lit light-emitting block 11-1, the path via the discharge thyristor Z is referred to as a discharge path 17 here.

[0089] The nMOS transistor 71 of the discharge control unit 70 is applied with the power supply voltage VLD (9V) via a resistor R4. Even when the nMOS transistor 71 is turned on, the current flowing is limited by the resistor R4, preventing a large current from flowing through the nMOS transistor 71. Furthermore, the nMOS transistor 71 only needs to supply a current that turns on the discharge thyristor Z, and therefore need only have a small current capacity. 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, eliminating the need to provide a separate power supply for the discharge control unit 70 (the drain of the nMOS transistor 71).

[0090] The following values were used to simulate the current I through the VCSEL: the parasitic inductances L1 and L2, the parallel capacitance C1, and the resistances R1 and R3 are 0.6 nH, 0.3 nH, 75 pF, 6 Ω, and 0.26 Ω, respectively, as previously described. The parasitic inductance L3 is 0.8 nH, and the resistance R2 is 6 Ω.

[0091] FIG. 9 is a timing chart illustrating the lighting control signal and discharge control signal used in the simulation. FIG. 9(a) shows the lighting control signal, and FIG. 9(b) shows 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 between the drain of the nMOS transistor 71 and the resistor R4) to the gate Gz of the discharge thyristor Z. Note that FIG. 9(a) also shows the nMOS transistor control signal supplied to the gate of the nMOS transistor 71 by the nMOS transistor control circuit 72 in the discharge control unit 70. In FIG. 9, the horizontal axis represents time t (ns), and the vertical axis represents signal voltage (V).

[0092] As shown in FIG. 9(a), the lighting control signal rises from 0V to 1.2V in 0.5ns at a timing of 5ns, and falls from 1.2V to 0V in 0.5ns at a 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 an amplitude of 1 / 2 is 5ns. The rise time and fall time are 0.5ns.

[0093] The nMOS transistor control signal rises from 0V to 1.2V in 0.3ns at a timing of 9.8ns, and falls from 1.2V to 0V in 0.3ns at a 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 amplitude is 0.8ns.

[0094] As shown in Figure 9(b), the discharge control signal controlled by the nMOS transistor control signal falls from 9V to 0V in 0.3ns at a timing of 9.8ns, and rises from 0V to 9V in 0.3ns at a 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 an amplitude of 1 / 2 is 0.8ns.

[0095] The discharge control signal begins to fall 0.2 ns before the timing (10 ns) at which the lighting control signal begins to fall. As mentioned above, the discharge thyristor Z turns on when the gate Gz falls below 7.5 V. That is, the discharge thyristor Z is turned on while the lighting control signal is 1.2 V, that is, while the nMOS transistor 51 of the driver 50 is on.

[0096] The timing at which the discharge control signal starts to fall may be before the lighting control signal starts to fall, or after the lighting control signal has fallen, as shown in Figures 9(a) and 9(b). The discharge control signal falling when the lighting control signal falls includes the timing at which the discharge control signal starts to fall before the lighting control signal starts to fall and after the lighting control signal has fallen. If the discharge control signal starts to fall before the lighting control signal starts to fall, current flows from the power supply VLD to the driver 50 via the discharge thyristor Z (see Figure 8), resulting in increased power consumption. To reduce power consumption, it is better to minimize the overlap on the time axis between the lighting control signal and the discharge control signal.

[0097] In the above, the lighting control signal is set so that the signal voltage for turning on the nMOS transistor 51 of the driver 50 is higher than the signal voltage for turning it off, and the discharge control signal is set so that the signal voltage for turning on the discharge thyristor Z is lower than the signal voltage for keeping it off. The level of the signal voltage varies depending on the configurations of the lighting control unit 60 and the discharge control unit 70. From this, it can be expressed that the discharge control signal begins to change to the signal voltage for turning on the discharge thyristor Z when the lighting control signal changes to the signal voltage for turning off the driver 50 (nMOS transistor 51). The moment when the lighting control signal changes to the signal voltage for turning off the driver 50 (nMOS transistor 51) may be immediately before or immediately after the driver 50 (nMOS transistor 51) turns off.

[0098] Once the thyristor is turned on, it will not turn off even if the gate voltage is changed. For this reason, the period (pulse width) during which the discharge control signal is lower than the power supply voltage VLD may be a period that allows the discharge thyristor Z to be turned on. Once the discharge thyristor Z is turned on, the discharge control signal may be returned to 9V. The pulse width W2 (width) of the discharge control signal may be shorter than the pulse width W1 (width) of the lighting control signal. Furthermore, the discharge control signal does not have to change to 0V as long as it is able to turn on the discharge thyristor Z. During the period during which the discharge control signal is lower than the power supply voltage VLD, the nMOS transistor control signal that turns on the nMOS transistor 71 is on. During the period during which the discharge control signal is lower than the power supply voltage VLD, current flows through the nMOS transistor 71. For this reason, if the period during which the discharge control signal is lower than the power supply voltage VLD is long, the power consumption of the light emitting device 1 increases.

[0099] 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 capacitance C1 is large and the amount of charge accumulated in the parallel capacitance C1 is large. On the other hand, when the number of light-emitting blocks 11 lit in parallel is large, the parallel capacitance C1 is small and the amount of charge accumulated in the parallel capacitance C1 is small. Therefore, the adjustment unit 80 adjusts the falling timing of the discharge control signal to be earlier than the falling timing of the lighting control signal when the number of light-emitting blocks 11 lit in parallel is small, and to be later than 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 according to the falling timing of the lighting control signal and the number of light-emitting blocks that are lit.

[0100] FIG. 10 shows the results of a simulation of the current I flowing through the VCSEL in a light emitting device 1 using a light emitting device 10 including a discharge thyristor Z to which the first embodiment is applied. The light emitting device 10 includes 24 light emitting blocks 11, with one light emitting block 11 turned on and the other light emitting blocks 11 turned off. In FIG. 10, the horizontal axis represents time t (ns) and the vertical axis represents the current I (VCSEL) flowing through the VCSEL. FIG. 10 also shows the current I (see FIG. 7) flowing through the VCSEL in a light emitting device 1A using a light emitting device 10A without a discharge thyristor Z. The light emitting device 1 using the light emitting device 10 including the discharge thyristor Z is referred to as "light emitting device 10 including discharge thyristor Z" and is referred to as "with discharge thyristor" in FIG. 10. The light emitting device 1A using the light emitting device 10A without a discharge thyristor Z is referred to as "light emitting device 10A without discharge thyristor Z" and is referred to as "without discharge thyristor" in FIG. 10. The lighting control signal and the discharge control signal in the case of the light-emitting device 10 including the discharge thyristor Z are as shown in the timing charts of Figures 9(a) and 9(b). The lighting control signal in the case of the light-emitting device 10A not including the discharge thyristor Z is the lighting control signal in the timing chart of Figure 9(a).

[0101] As shown in FIG. 10, there is little difference in the rise of the current I of the VCSEL between the light-emitting device 10 equipped with the discharge thyristor Z (“with discharge thyristor”) and the light-emitting device 10A not equipped with the discharge thyristor Z (“without discharge thyristor”). However, the fall of the current I of the VCSEL has a smaller delay in the light-emitting device 10 equipped with the discharge thyristor Z (“with discharge thyristor”) than in the light-emitting device 10A not equipped with the discharge thyristor Z (“without discharge thyristor”). In other words, the provision of the discharge thyristor Z shortens the fall time of the current I flowing through the VCSEL. This suppresses trailing light emission from the VCSEL.

[0102] As described above, in the light emitting device 1, when the light emitting block 11 is turned off, the discharge thyristor Z is turned on. When the light emitting block 11 is turned on, charge is accumulated in the parallel capacitance C1. When the discharge thyristor Z is turned on, the charge accumulated in the parallel capacitance C1 is discharged via the discharge path 17 formed by the discharge thyristor Z. This reduces the discharge time constant and shortens the fall time of the VCSEL current I. In order to reduce the discharge time constant, it is advisable to reduce the resistance R2, which is the internal resistance of the discharge thyristor Z.

[0103] (Light emitting device 1C as a comparative example) In the light emitting device 1 to which the first embodiment is applied, a discharge thyristor Z is provided inside the light emitting device 10. The discharge thyristor Z forms a discharge path 17 that discharges the charge accumulated in the parallel capacitance C1 (example). Here, as a comparative example, a light emitting device 1C will be described in which a light emitting device 10A without a discharge thyristor Z is used and a switch forming a discharge path 18 is provided outside the light emitting device 10A.

[0104] 11 is an equivalent circuit diagram illustrating a light emitting device 1C (comparative example) that includes 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.

[0105] The light emitting device 10A is assumed to include 24 light emitting blocks 11 (see FIG. 5(a)). One light emitting block 11 (light emitting block 11-1 in FIG. 11) is turned on, and the other light emitting blocks 11 (light emitting blocks 11-2 to 11-24) are turned off. Other parts that are the same as those in FIG. 8 are given the same reference numerals, and description thereof will be omitted.

[0106] 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) that turns the pMOS transistor 76 on and off. 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 off when its gate is at the power supply voltage VLD, and is on when its gate becomes equal to or lower than the voltage obtained by subtracting the threshold voltage from the power supply voltage VLD.

[0107] When the nMOS transistor 51 of the driver 50 is turned on from off while the switch 75 (pMOS transistor 76) is off, the light-emitting block 11-1 lights up. As the light-emitting block 11-1 lights up, charge is accumulated in the parallel capacitance C1. When the nMOS transistor 51 of the driver 50 is turned off from on, the light-emitting block 11-1 goes out. At this time, when the switch 75 (pMOS transistor 76) is turned on, the charge accumulated in the parallel capacitance C1 is discharged via the discharge path 18 that passes through the switch 75 (pMOS transistor 76).

[0108] In the following simulation, the pMOS transistor control signal generated by the pMOS transistor control circuit 77 rises from 5.7V to 9V in 0.5ns at a timing of 5ns, and falls from 9V to 5.7V in 0.5ns at a timing of 9.5ns. The amplitude is 3.3V. The pMOS transistor control signal is a pulse signal with a period of 40ns. The pulse width (sometimes referred to as width) at 1 / 2 amplitude is 5ns. The rise time / fall time is 0.5ns. When the pMOS transistor control signal is 9V, the pMOS transistor 76 is off, and when the pMOS transistor control signal is 5.7V, the pMOS transistor 76 is on.

[0109] The nMOS transistor 51 of the driver 50 is operated by the lighting control signal shown in Fig. 9(a). 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 on, the pMOS transistor 76 is off, and when the nMOS transistor 51 of the driver 50 is off, the pMOS transistor 76 is on.

[0110] FIG. 12 shows the results of simulating the current I flowing through the VCSEL in a light emitting device 1 (Example) using a light emitting device 10 equipped with a discharge thyristor Z, and a light emitting device 1C (Comparative Example) equipped with a switch 75. The light emitting device 1C (Comparative Example) uses a light emitting device 10A that does not have a discharge thyristor Z. The horizontal axis represents time t (ns), and the vertical axis represents the current I (VCSEL) flowing through the VCSEL. In FIG. 12, the light emitting device 1 using a light emitting device 10 equipped with a discharge thyristor Z is referred to as the "Example (Discharge Thyristor)," and the light emitting device 1C equipped with a switch 75 is referred to as the "Comparative Example (Switch)."

[0111] There is almost no difference in the rise characteristics of the current I flowing through the VCSEL between the light emitting device 1 (Example) using the light emitting device 10 with the discharge thyristor Z and the light emitting device 1C (Comparative Example) using the switch 75. On the other hand, the fall time of the current I flowing through the VCSEL is shorter in the light emitting device 1 (Example) using the light emitting device 10 with the discharge thyristor Z than in the light emitting device 1C (Comparative Example) using the switch 75. In the light emitting device 1C (Comparative Example) using the switch 75, the pMOS transistor 76 is provided outside the light emitting device 10A. The pMOS transistor 76 that forms the discharge path 18 is connected to the light emitting device 10A via a parasitic inductance L2 (see FIG. 11).

[0112] On the other hand, in the light emitting apparatus 1 (Example) using the light emitting device 10 having the discharge thyristor Z, the discharge thyristor Z that constitutes the discharge path 17 is configured inside the light emitting device 10. Therefore, the inductance of the discharge path 17 is smaller than that of the discharge path 18 of the comparative example. The smaller inductance shortens the fall time of the current I flowing through the VCSEL.

[0113] 11, the source of the pMOS transistor 76 of the switch 75 is at the power supply voltage VLD (9 V). When the nMOS transistor 51 of the driver 50 is on, the drain voltage of the nMOS transistor 51 is set to about 1 V. Then, a voltage of about 8 V is applied between the source and drain of the off pMOS transistor 76. The pMOS transistor 76 is required to be an element that operates at a high voltage.

[0114] As described above, by integrating the light-emitting block 11 and the element (here, the discharge thyristor Z) that constitutes the discharge path 17 into a semiconductor device, as in the light-emitting device 10 of the embodiment, the influence of parasitic inductance is suppressed, and the fall time of the light emission of the light-emitting element (here, the VCSEL) is shortened.

[0115] [Second embodiment] In the light-emitting device 10 according to the first embodiment, the discharge path 17 is a discharge thyristor Z, and the discharge path 17 formed by the discharge thyristor Z is connected in parallel to the light-emitting block 11. Then, as shown in FIG. 3, the n-cathode layer 35 of the discharge thyristor Z is exposed, and an n-ohmic electrode (cathode Kz) is provided. In the light emitting device 20 of the second embodiment, it is not necessary to provide the n-ohmic electrode (cathode Kz) on the n-cathode layer 35 of the discharge thyristor Z.

[0116] 13 is a cross-sectional view illustrating the cross-sectional shape of a light-emitting device 20 to which the second embodiment is applied. The upward direction on the paper surface is the z direction. The same parts as in FIG. 3 are given the same reference numerals and their description will be omitted.

[0117] In the light-emitting device 20, the discharge path 19 (see FIG. 14 described later) is composed of a series-connected discharge thyristor Z and pseudo-VCSEL (referred to as P-VCSEL in FIGS. 13 and 14 and hereinafter). The P-VCSEL is composed of the same laminated semiconductor layers as the VCSEL in the light-emitting block 11. The P-VCSEL does not have the light-emitting aperture 43 of the light-emitting block 11. The P-VCSEL is used as a diode rather than as a light-emitting element. In other words, the P-VCSEL is the VCSEL in the light-emitting block 11, and current flows when the series-connected discharge thyristor Z is turned on. The series connection of the discharge thyristor Z and the P-VCSEL forms the discharge path 19 from the anode electrode 42 to the cathode electrode 41 (see FIG. 14 described later).

[0118] In the light-emitting device 20, it is not necessary to provide an n-ohmic electrode (cathode Az) 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, the process of exposing the n-cathode layer 35 of the discharge thyristor Z is not necessary. The discharge thyristor Z has the same layer structure as the setting thyristor S of the light-emitting block 11, and the P-VCSEL has the same layer structure as the setting thyristor S of the light-emitting block 11. That is, the light-emitting device 20 does not require a special process for configuring the discharge path 19. Furthermore, the light-emitting device 20 does not have the cathode pad 15 that the light-emitting device 10 has. If the P-VCSEL is configured using the same laminated semiconductor layers as the VCSEL in the light-emitting block 11, the light-emitting device 20 can be manufactured more easily.

[0119] The series connection of the discharge thyristor Z and the P-VCSEL forms a discharge path 19. Unlike 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 wider than the VCSEL in the light-emitting block 11, the internal resistance can be reduced.

[0120] When the discharge thyristor Z is turned on, a current flows through the P-VCSEL. At this time, if the P-VCSEL emits light and the light passes through the discharge thyristor Z and is emitted to the outside, a light-shielding film can be provided on the path of the emitted light, such as by using the anode electrode 42.

[0121] FIG. 14 is an equivalent circuit of a light emitting apparatus 2 using a light emitting device 20 to which the second embodiment is applied. Components similar to those of the light emitting apparatus 1 using the light emitting device 10 in FIG. 8 are designated by the same reference numerals, and a description thereof will be omitted. In the light emitting device 20, the discharge path 19 is formed by a series connection of a discharge thyristor Z and a P-VCSEL. Note that resistor R5 is an equivalent resistance that equivalently represents the internal resistance 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.

[0122] 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. A description of the light emitting device 2 using the light emitting device 20 will be omitted.

[0123] In the light-emitting device 10 to which the first embodiment is applied and the light-emitting device 20 to which the second embodiment is applied, the cases where the VCSEL and the setting thyristor S are stacked in this order on the substrate 30 have been described, but the setting thyristor S and the VCSEL may also be stacked in this order on the substrate 30. In this case, the discharge thyristor Z may be configured similarly to the setting thyristor S, and the P-VCSEL in the second embodiment may be configured similarly to the VCSEL. Furthermore, the setting thyristor S and the VCSEL may be arranged side by side on the substrate 30 without being stacked.

[0124] In the light-emitting device 10 to which the first embodiment is applied and the light-emitting device 20 to which the second embodiment is applied, a VCSEL has been described as an example of a light-emitting element, but a light-emitting diode (LED) (Light Emitting Diode) or a laser diode (LD) (Laser Diode) may be used instead of a VCSEL. While the setting element is a thyristor designated as setting thyristor S as an example and the discharge element is a thyristor designated as discharge thyristor Z as an example, either or both of the setting element and the discharge element may be transistors. It is sufficient that the setting element and the discharge element are integrally integrated on a semiconductor substrate together with the light-emitting element, and configured to enable block illumination.

[0125] Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope of the above-described embodiments. It is clear from the claims that various modifications and improvements to the above-described embodiments are also included in the technical scope of the present invention. Furthermore, various modifications may be made as long as they do not deviate from the spirit of the present invention.

[0126] (Addendum) (((1))) a plurality of light-emitting blocks each including a light-emitting element and a setting element that sets the light-emitting element to a light-enabled state; a discharge path including a discharge element capable of controlling discharge when the light-emitting element is turned off and discharging the charge accumulated when the light-emitting element is turned on; A light-emitting device in which a plurality of the light-emitting blocks and the discharge path are electrically connected in parallel. (((2))) The light-emitting device according to (((1))), wherein the discharge element is a thyristor. (((3))) the discharge path is formed by the discharge element being a thyristor, In the light-emitting block, the light-emitting element is a surface-emitting laser, and the setting element is a thyristor, The light-emitting device according to (((2))), wherein the discharge path is electrically connected in parallel to the series connection of the light-emitting element and the setting element. (((4))) The light-emitting device according to (((3))), wherein the thyristor serving as the setting element and the thyristor serving as the discharge element have laminated semiconductor layers of the same configuration. (((5))) the discharge path is formed by a 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 light-emitting device according to (((2))), wherein the discharge path is electrically connected in parallel to the series connection of the light-emitting element and the setting element. (((6))) The light-emitting device according to (((5))), wherein the thyristor as the setting element and the thyristor as the discharge element have laminated semiconductor layers of the same configuration, and the surface-emitting laser as the light-emitting element and the quasi-surface-emitting laser have laminated semiconductor layers of the same configuration. (((7))) a light-emitting device according to any one of (((1))) to (((6))); a driver connected to the light-emitting device and supplying a current for lighting a 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 to the driver to control a lighting period of a light-emitting element in the light-emitting device; a discharge control unit that supplies a discharge control signal to the light-emitting device to control discharge; A light emitting device comprising: (((8))) The light emitting device according to ((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 ((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 ((7)) to ((9))), wherein a power supply voltage supplied to the light emitting device and a power supply voltage supplied to the discharge control unit are the same. (((11))) The light emitting device according to any one of ((7))) to (((10))) further comprises an adjustment unit that adjusts the timing at which the discharge control unit sends a signal to turn on the discharge element in the discharge control signal according to the timing at which the driver is turned off in the lighting control signal and the number of the light emitting blocks that are lit. (((12))) a light-emitting device according to any one of (((7))) to (((11))); a light receiving unit that receives light emitted by the light emitting device and reflected from the measurement object, A measuring device that measures the three-dimensional shape of an object.

[0127] According to the light emitting device of (((1))), the fall time of the light emitting element can be made shorter than when there is no discharge path. The light emitting device according to (((2))) exhibits faster switching speed than non-thyristor devices. According to the light-emitting device of (((3))), the parasitic resistance can be reduced compared to when the discharge path includes other elements in addition to the thyristor. According to the light emitting device according to (((4))), the manufacturing of the light emitting device is easier than when the light emitting device does not have multiple semiconductor layers of the same configuration. According to the light emitting device of (((5))), the discharge path can be configured in the same way as the light emitting block, compared to when the discharge element and the pseudo surface emitting laser are not connected in series. According to the light emitting device of (((6))), the manufacturing of the light emitting device is easier than when the light emitting device does not have multiple semiconductor layers of the same configuration. According to the light emitting device according to (((7))), a light emitting device capable of block irradiation can be realized. According to the light emitting device of (((8))), power consumption can be reduced compared to when the lighting control signal is a signal voltage that turns on the driver and the discharge control signal changes to a signal voltage that turns on the discharge element. According to the light emitting device of (((9))), power consumption can be reduced compared to when the width of the signal that turns on the discharge element is greater than the width of the signal that turns on the driver. The light emitting device according to (((10))) can be configured more simply than when the power supply voltages are different. According to the light emitting device of (((11))), the timing of the fall of light emission of the light emitting elements can be controlled regardless of the number of light emitting blocks that are turned on, compared to when no adjustment is made. According to the measuring device according to (((12))), a measuring device based on a three-dimensional shape can be provided. [Explanation of symbols]

[0128] 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...shunt capacitance, L1, L2, L3...parasitic inductance, P-VCSEL...quasi-vertical-cavity surface-emitting laser, R1, R2, R3, R4, R5...resistor, S...setting thyristor, VCSEL...vertical-cavity surface-emitting laser, VLD...power supply, power supply voltage, Z...discharge thyristor

Claims

1. a plurality of light-emitting blocks each including a light-emitting element and a setting element that sets the light-emitting element to a light-enabled state; a discharge path including a discharge element capable of controlling discharge when the light-emitting element is turned off and discharging the charge accumulated when the light-emitting element is turned on; A light-emitting device in which a plurality of the light-emitting blocks and the discharge path are electrically connected in parallel.

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

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

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

5. the discharge path is formed by a 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 light-emitting device according to claim 2 , wherein the discharge path is electrically connected in parallel to 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 of the same configuration, and the surface-emitting laser as the light-emitting element and the pseudo-surface-emitting laser have laminated semiconductor layers of the same configuration.

7. A light emitting device according to claim 1; a driver connected to the light-emitting device and supplying a current for lighting a 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 to the driver to control a lighting period of a light-emitting element in the light-emitting device; a discharge control unit that supplies a discharge control signal to the light-emitting device to control discharge; A light emitting device comprising:

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. 8. The light emitting device according to claim 7, 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. 10. The light emitting device according to claim 7, wherein a power supply voltage supplied to the light emitting device and a power supply voltage supplied to the discharge control unit are the same.

11. The light emitting device according to claim 7, further comprising an adjustment unit that adjusts the timing at which the discharge control unit sends a signal to turn on the discharge element in the discharge control signal in accordance with the timing at which the driver is turned off in the lighting control signal and the number of the light emitting blocks that are lit.

12. The light emitting device according to claim 7; a light receiving unit that receives light emitted by the light emitting device and reflected from the measurement object, A measuring device that measures the three-dimensional shape of an object.

Images