Light source device and measuring device

Abstract

To provide a light source device or the like in which an ON state is not maintained when maintenance of the ON state is not required.SOLUTION: A light source device includes: a light emitting part including a plurality of light emitting elements each having a thyristor; and a control part for performing the control so that the erasing pulse for disabling re-emission of the light emitting element is supplied after supplying a light emitting current to the light emitting part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light source device and a measurement device. [Background technology]

[0002] Patent Document 1 describes a light-emitting component comprising a substrate, a plurality of light-emitting elements provided on the substrate and emitting light in a direction intersecting the surface of the substrate, and a plurality of thyristors stacked on the plurality of light-emitting elements and driving the light-emitting elements to emit light or increase the amount of light emitted when turned on, the thyristors having an opening in the path of light from the light-emitting elements toward the thyristors.

[0003] Patent document 2 describes a light emitting device including a light source having a plurality of light emitting elements, a plurality of driving elements provided corresponding to the plurality of light emitting elements and driving the light emitting elements to light up when turned on, and a control unit that switches between a sequential lighting operation for lighting up the plurality of light emitting elements in sequence and a simultaneous lighting operation for lighting up the plurality of light emitting elements simultaneously in parallel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-57652 A [Patent Document 2] JP 2021-158160 A Summary of the Invention [Problem to be solved by the invention]

[0005] There are light emitting devices that have a light emitting element having a capacitance such as a thyristor, and the light emitting element emits light by turning on the thyristor. Since the thyristors in these light emitting devices have a capacitance, it has been found that once they are turned on, the on state may be maintained even if no signal is input to turn them on. The present invention provides a light source device that does not maintain the on state when it is not necessary to maintain the on state. [Means for solving the problem]

[0006] The invention described in claim 1 is Emit light when charge accumulates A light emitting unit including a light emitting element having a thyristor; While the thyristor is in a state where electric charges are accumulated, a light emission signal is used to control the emission and quenching of the light emitting element. After supplying light-emitting current and emitting light, The charge of the thyristor is erased by an erase signal different from the light emission signal. and a control unit that controls the light emitting element to supply an erasing pulse that disables the light emitting element from re-emitting light. The invention described in claim 2 is the light emitting unit includes a plurality of light emitting elements each having the thyristor; The control unit controls a part of the plurality of light-emitting elements of the light-emitting unit to emit light, and after supplying a light-emitting current to cause the part of the plurality of light-emitting elements to emit light, before causing another light-emitting element to emit light, Disable some of the light-emitting elements of the light-emitting unit from re-emitting light. 2. The light source device according to claim 1, wherein the erase pulse is supplied. The invention described in claim 3 is Emit light when charge accumulates A light emitting unit including a plurality of light emitting elements each having a thyristor, and a part of the plurality of light emitting units of light-emitting elements Thyristor Charge accumulated A setting unit for setting The part of light-emitting elements Thyristor When the charge accumulates After setting, A light emission signal controls the emission and quenching of the part of the light emitting elements. Before supplying light emitting current, By using an erase signal different from the light emission signal, charges of the thyristors of the light emitting elements other than the part of the light emitting elements in the light emitting section are erased to remove the part of the light emitting elements. and a control unit that supplies an erasing pulse that disables the light emission of the light emitting element. The invention described in claim 4 is the light emitting unit includes a plurality of light emitting elements each having the thyristor; The control unit is A light-emitting element that causes some of the light-emitting elements in the light-emitting section to emit light , For the part of light emitting elements After turning the light-emitting current on and off multiple times, Disable re-emission of some of the light-emitting elements 2. The light source device according to claim 1, wherein the erase pulse is supplied. In the invention described in claim 5, the control unit controls the light-emitting current and the erase pulse for causing the light-emitting element to emit light. and 4. The light source device according to claim 1, wherein the first and second input terminals are connected to a ground terminal of the power source. The invention described in claim 6 is the light source device described in claim 5, in which the thyristor and the light-emitting element are stacked, and the thyristor is stacked on a side farther from the ground side than the light-emitting element. Claim 7The invention described in claim 1 or 3 is a light source device according to claim 1 or 3, wherein the pulse width of the erasing pulse is narrower than the pulse width when emitting light. Claim 8 The invention described in claim 1 or 3 is the light source device described in claim 1 or 3, wherein the current value of the erase pulse is lower than the current value when emitting light. The invention described in claim 9 is a light source device as described in claim 1 or 3, characterized in that the control unit includes a first driver that turns on / off the light-emitting current to the ground side of a power supply that supplies the light-emitting current to the light-emitting element, and a second driver that supplies the erasing pulse, and the second driver has an on-resistance that is smaller than the off-resistance of the first driver and is set to a value that disables re-emission by turning on when the first driver is off. Claim 10 The invention described in claims 1 to 9 and a light receiving section that receives light emitted from the light emitting section of the light source device and reflected by an object to be measured. Effect of the Invention

[0007] Claim 1 to According to the described invention, when it is not necessary to maintain the ON state, the ON state can be prevented from being maintained. According to the invention as recited in claim 2, it is possible to prevent a light emitting element that has previously emitted light from erroneously emitting light. According to the invention as recited in claim 3, it is possible to prevent the light emitting element of the thyristor that has been once turned on by the setting section from erroneously lighting up. According to the fourth aspect of the present invention, the repetition period of light emission can be made shorter than in the case where an erasing pulse is provided for each light emission. Claim 5 、6 According to the invention described in the above, the rise time of the light-emitting current can be made shorter compared to the case where the light-emitting current is not supplied from the ground side. Claim 7、8 According to the invention described in the above, the amount of light emitted by the light emitting element due to the erase pulse is suppressed. According to the ninth aspect of the present invention, the erasing pulse can be easily set. Claim 10According to the invention described in the above, a measuring device capable of measuring a three-dimensional shape is provided. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams illustrating a light source device to which a first embodiment is applied. [Diagram 2] 1A and 1B are diagrams illustrating the operation of a light-emitting device including a shift thyristor, a coupling transistor, a light-emission control thyristor, and a VCSEL, where (a) is an equivalent circuit, and (b) is a cross-sectional view of a portion of the shift thyristor and the coupling transistor. [Diagram 3] 1A and 1B are diagrams illustrating a layout and a cross section of a light emitting device, where (a) is the layout, and (b) is a cross section taken along line IIIB-IIIB in (a). [Figure 4] 4 is a timing chart showing the operation of the light source device to which the first embodiment is applied. [Diagram 5] 5 is a timing chart showing how a light source device different from that in FIG. 4 is operated. [Figure 6] 13 is a diagram showing the voltage in the emission control thyristor and the emission current of the VCSEL in a series connection of the emission control thyristor and the VCSEL, where (a) is a set timing chart, and (b) is the voltage in the emission control thyristor and the emission current of the VCSEL. [Figure 7] 1 shows an equivalent circuit of a light-emission control thyristor and a VCSEL, where (a) is a diagram showing the equivalent circuit, and (b) is a diagram showing the parasitic capacitance of a semiconductor layer and a pn junction. [Figure 8] 13 is a diagram showing the cathode voltage of the light-emission control thyristor and the light-emission current of the VCSEL when the off-resistance of the driver is changed. FIG. [Figure 9] 11 is another diagram showing the cathode voltage of the light-emission control thyristor and the light-emission current of the VCSEL when the off-resistance of the driver is changed, where (a) shows the entire light-emission current, and (b) is an enlarged view of the light-emission current in (a). [Figure 10] 11A and 11B are diagrams illustrating a light source device to which a second embodiment is applied. [Figure 11] 13A and 13B are diagrams illustrating a light source device to which a third embodiment is applied. [Figure 12] 11 is a timing chart illustrating the timing of providing an erase pulse. [Figure 13] FIG. 2 is a block diagram illustrating a configuration of a measurement device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, a light source device will be described which does not maintain the on state when it is not necessary to maintain the on state of a setting unit or a thyristor in a light emitting element having a thyristor. Until now, it was thought that the light-emitting element would not turn on unless the setting unit or the thyristor in a light-emitting element having a thyristor was maintained in the on state. However, there was a risk that unnecessary power would be consumed if the setting unit or the thyristor in a light-emitting element having a thyristor was maintained in the on state. In addition, it was thought that the on state of the light-emitting element could be cleared by turning off ("L") the light-emitting signal that causes the light-emitting element to emit light. However, if the light-emitting signal is turned on ("H") when the light-emitting element is in an on state or can transition to an on state, there was a risk of malfunction, such as a light-emitting element that should not be emitted emitting light.

[0010] [First embodiment] Fig. 1 is a diagram for explaining a light source device 1 to which the first embodiment is applied. In Fig. 1, the right direction on the paper surface is the +x direction. Thyristors and transistors are indicated by symbols, and resistors are indicated by rectangles. The same applies to other cases. The light source device 1 shown in FIG.

[0011] (Light emitting device 10) The light emitting device 10 includes a GND terminal, a VGK terminal, a φ1 terminal, a φ2 terminal, a VLD terminal, and a Vdrv terminal on one side (the −x direction side). Note that GND is a ground potential that is a reference voltage (hereinafter, referred to as ground potential GND, and the same applies below), VGK is a power supply potential (power supply potential VGK), VLD is a light emitting voltage VLD that supplies a light emitting current, and Vdrv is a driver voltage Vdrv that is output by a driver that turns on / off the light emitting current.

[0012] The light emitting device 10 includes a light emitting section 11 and a shift section 12. The light emitting section 11 includes a plurality of vertical cavity surface emitting lasers VCSELs (Vertical Cavity Surface Emitting Lasers) and emission control thyristors S. Hereinafter, the vertical cavity surface emitting lasers VCSELs are referred to as VCSELs. In FIG. 1, six VCSELs (VCSEL(1) to VCSEL(6)) and six emission control thyristors S (emission control thyristors S(1) to S(6)) are shown. The anodes of the VCSELs and the cathodes of the emission control thyristors S are connected. That is, the VCSELs and the emission control thyristors S of the same number are connected in series. The six VCSELs and the six emission control thyristors S are arranged from one side (-x direction side) to the other side (+x direction side). The series-connected VCSELs and the emission control thyristors S are an example of a light emitting element having a thyristor. The light emitting element may be an element in which the pn junction of a thyristor emits light, and this element is also a light emitting element having a thyristor.

[0013] The shift section 12 includes a plurality of shift thyristors T, coupling transistors Q, power supply line resistances Rg, current limiting resistances RL, and coupling resistances Rc. Six shift thyristors T (shift thyristors T(1) to T(6)) and six coupling transistors Q (coupling transistors Q(1) to Q(6)) are shown. Note that six power supply line resistances Rg, six current limiting resistances RL, and six coupling resistances Rc are included, but are not numbered. One shift thyristor T, coupling transistor Q, power supply line resistance Rg, current limiting resistance RL, and coupling resistance Rc constitute a shift unit 12a. Six shift units 12a are arranged from one side (-x direction side) to the other side (+x direction side). The shift section 12 includes a power supply line resistance Rg and a start resistance at an end on one side (-x direction side). Furthermore, the light emitting device 10 includes current limiting resistances R1 and R2.

[0014] In the shift unit 12a, the light-emission control thyristor S and the coupling transistor Q are connected. The coupling transistor Q in the shift unit 12a is connected to the light-emission control thyristor S of the light-emitting section 11. In other words, the light-emission control thyristors S(1) to S(6) are connected to the coupling transistors Q(1) to Q(6), and the coupling transistors Q(1) to Q(6) are connected to the same numbers as the light-emission control thyristors S(1) to S(6). Here, six light-emission control thyristors S, coupling transistors Q, light-emission control thyristors S, and VCSELs are shown, but other numbers may be used.

[0015] In the light emitting device 10, the VGK terminal is connected to a power supply line 71, the GND terminal is connected to a ground line 73, the φ1 terminal is connected to a shift signal line 72-1, the φ2 terminal is connected to a shift signal line 72-2, the VLD terminal is connected to a voltage supply line 74, and the Vdrv terminal is connected to a driver voltage line 75. When there is no need to distinguish between the shift signal lines 72-1 and 72-2, they are referred to as shift signal lines 72.

[0016] The control unit 50 includes buffers Buf1 and Buf2, power supplies VS1 and VS2, a driver Drv, and a light-emitting current limiting resistor RI. The buffer Buf1 supplies a shift signal p1 to the φ1 terminal of the light-emitting device 10. The buffer Buf2 supplies a shift signal p2 to the φ2 terminal of the light-emitting device 10. The power supply VS1 generates a power supply potential VGK and supplies it to the VGK terminal of the light-emitting device 10. The power supply VS1 also serves as a power supply for the buffers Buf1 and Buf2. That is, when the shift signals p1 and p2 are at the H level, the buffers Buf1 and Buf2 output a voltage that is approximately equal to the power supply VS1, and when the shift signals p1 and p2 are at the L level, they output a voltage that is approximately equal to the ground potential GND. The power supplies for the buffers Buf1 and Buf2 may be independent of the power supply potential VGK.

[0017] The power supply VS2 generates a light-emitting voltage VLD and supplies it to the VLD terminal of the light-emitting device 10. The driver Drv is, for example, an NMOS transistor as a driver element, and is turned on / off by a light-emitting signal pI applied to the gate. The source of the NMOS transistor is grounded, and the drain is connected to the Vdrv terminal via a light-emitting current limiting resistor RI. When the driver Drv is turned on, it supplies a ground potential GND to the Vdrv terminal of the light-emitting device 10. As described later, the driver Drv has a preset on-resistance Ron and off-resistance Roff. The on-resistance Ron is the resistance when the driver Drv is on, and the off-resistance Roff is the resistance when the driver Drv is off. The off-resistance Roff may be configured by the structure of an NMOS transistor, or may be configured by controlling the gate voltage of the NMOS transistor. The off-resistance Roff may be configured by providing a resistor in parallel with the NMOS transistor between the source and drain of the NMOS transistor, which has a sufficiently large resistance when off. Instead of the NMOS transistor, other elements such as an insulated gate bipolar transistor (IGBT) may be used. The NMOS transistor and the IGBT are examples of the driver element.

[0018] The connection relationship in the light emitting device 10 will be explained using an enlarged view. The light-emission control thyristor S may be referred to as the light-emission control thyristor, the shift thyristor T as the shift thyristor, and the coupling transistor Q as the coupling transistor. The light-emission control thyristor S and the shift thyristor T may be referred to as the thyristor without distinction.

[0019] (Operation of shift thyristor, coupling transistor, VCSEL and light emission control thyristor) Here, the basic operation of the light emitting device 10 will be described. The shift thyristor and the light-emission control thyristor are thyristors with an npnp structure. The thyristors are equipped with an n-type cathode K (hereinafter, written as cathode K, and the same applies below), a p-type gate Gp (p-gate Gp), an n-type gate Gn (n-gate Gn), and a p-type anode A (anode A). Note that the light-emission control thyristor S does not use the p-gate Gp for control, so it is not shown.

[0020] The coupling transistor is a multi-collector npn bipolar transistor. The coupling transistor has an n-type emitter E (emitter E), a p-type base B (base B), and n-type collectors Cf, Cs (collector Cf, Cs).

[0021] The above symbols are used without distinction between thyristors and coupling transistors. The same applies to the bipolar transistors that make up the thyristors described below. However, as described below, the thyristor is composed of a combination of single-collector npn bipolar transistors and pnp bipolar transistors. Therefore, they are written as emitter E, base B, and collector C. In the following, even if symbols are not attached to the figures, the symbols are used as anode A, cathode K, n-gate Gn, p-gate Gp, emitter E, base B, and collector C.

[0022] The shift thyristor T, the coupling transistor Q, the light-emission control thyristor S, and the VCSEL are composed of a III-V compound semiconductor such as GaAs. Here, the forward voltage (diffusion potential) Vd of the junction of this compound semiconductor is 1.5V, and the saturation voltage Vc of the bipolar transistor composed of the compound semiconductor is 0.3V. The ground potential GND is 0V, the power supply potential VGK, and the light-emission voltage VLD are 5V. The shift signals p1, p2, and the light-emission signal pI are signals whose L level is 0V ("L" (0V)) and whose H level is 5V ("H" (5V)). The driver Drv is turned off when the light-emission signal pI becomes "L" (0V), and turned on when the light-emission signal pI becomes "H" (5V).

[0023] 2 is a diagram explaining the operation of the light emitting device 10 using the shift thyristor T(1), the coupling transistor Q(1), the light emitting control thyristor S(1), and the VCSEL(1). Fig. 2(a) is an equivalent circuit, and Fig. 2(b) is a cross-sectional view of the shift thyristor T(1) and the coupling transistor Q(1). Fig. 2(a) also shows the shift thyristor T(2).

[0024] As shown in FIG. 2(a), the shift thyristor T(1) is composed of a combination of an npn bipolar transistor Tr1 (hereinafter, referred to as npn transistor Tr1) and a pnp bipolar transistor Tr2 (hereinafter, referred to as pnp transistor Tr2). The base B of the npn transistor Tr1 is connected to the collector C of the pnp transistor Tr2, and the collector C of the npn transistor Tr1 is connected to the base B of the pnp transistor Tr2. The emitter E of the npn transistor Tr1 is the cathode K of the shift thyristor T(1), the collector C of the npn transistor Tr1 (the base B of the pnp transistor Tr2) is the n gate Gn of the shift thyristor T(1), the collector C of the pnp transistor Tr2 (the base B of the npn transistor Tr1) is the p gate Gp of the shift thyristor T(1), and the emitter E of the pnp transistor Tr2 is the anode A of the shift thyristor T(1). The emitter E of the npn transistor Tr1, which is the cathode K of the shift thyristor T(1), is connected to a ground line 73 connected to a GND terminal to which a ground potential GND is supplied. The emitter E of the pnp transistor Tr2, which is the anode A of the shift thyristor T(1), is connected to a shift signal line 72-1 connected to the φ1 terminal. The n gate Gn is connected to a connection point between the start resistor Rs and the power supply line resistor Rg connected in series. The other side (the side that is not the connection point) of the start resistor Rs is connected to a shift signal line 72-2 connected to the φ2 terminal. The other side (the side that is not the connection point) of the power supply line resistor Rg is connected to a power supply line 71 connected to a VGK terminal to which a power supply potential VGK is supplied. A shift signal p1 is supplied to the φ1 terminal. A shift signal p2 is supplied to the φ2 terminal.

[0025] The coupling transistor Q(1), which is an npn transistor, has a base B connected to the p gate Gp (the base B of the npn transistor Tr1 and the collector C of the pnp transistor Tr2) of the shift thyristor T(1), and an emitter E connected to a ground line 73. The collector Cf is connected to a power supply line 71 to which a power supply potential VGK is supplied via a coupling resistor Rc and a power supply line resistance Rg connected in series. The connection point between the coupling resistor Rc and the power supply line resistance Rg is connected to the n gate Gn of the shift thyristor T(2).

[0026] The npn transistor Tr1 in the shift thyristor T(1) and the coupling transistor Q(1) form a current mirror circuit. That is, a current proportional to the current flowing through the npn transistor Tr1 flows through the coupling transistor Q(1).

[0027] The collector Cs of the coupling transistor Q(1) is connected to the n-gate Gn of the light-emitting control thyristor S(1), and is also connected, via a current-limiting resistor RL, to a voltage supply line 74 that is connected to a VLD terminal to which a light-emitting voltage VLD is supplied.

[0028] As described above, the VCSEL(1) and the light-emission control thyristor S(1) are connected in series. In other words, the anode A of the VCSEL(1) and the cathode K of the light-emission control thyristor S(1) are connected. The anode A of the light-emission control thyristor S(1) is connected to a voltage supply line 74. The cathode K of the VCSEL(1) is connected to a driver voltage line 75 that is connected to a Vdrv terminal to which a driver voltage Vdrv is supplied.

[0029] The anode A of the shift thyristor T(2) is connected to the shift signal line 72-2 connected to the φ2 terminal. As shown in FIG. 1, the anode A of the odd-numbered shift thyristors T is connected to the shift signal line 72-1, and the anode A of the even-numbered shift thyristors T is connected to the shift signal line 72-2. Except for the connection relationship between the shift thyristors T and the shift signal lines 72-1 and 72-2, the connection relationships of the shift thyristors T numbered 2 or more, the coupling transistors, the light-emission control thyristors S, and the VCSELs are the same as those of the shift thyristor T(1), the coupling transistor (1), the light-emission control thyristor S(1), and the VCSEL(1). Hereinafter, they may be referred to as a shift signal p1(φ1) and a shift signal p2(φ2).

[0030] First, the operation of the shift thyristor T(1) will be described. First, the power supply line 71 is set to a power supply potential VGK (5V), the ground line 73 is set to a ground potential GND (0V), and the shift signals p1 (φ1) and p2 (φ2) are set to "L" (0V). At this time, the npn transistor Tr1 and the pnp transistor Tr2 constituting the shift thyristor T(1) are in an off state. The n gate Gn of the shift thyristor T(1) is connected to the connection point between the start resistor Rs and the power supply line resistance Rg connected in series. The other side (the side other than the connection point) of the start resistor Rs is connected to the shift signal line 72-2 of "L" (0V), and the other side (the side other than the connection point) of the power supply line resistance Rg is connected to the 5V power supply line 71. Therefore, the n gate Gn becomes a voltage obtained by dividing the voltage difference (5V) between the start resistor Rs and the power supply line resistance Rg. If the resistance ratio between the start resistor Rs and the power supply line resistor Rg is 1:5, for example, the n gate Gn becomes 0.83V. Note that the light emission signal pI is "L" (0V) and the driver Drv is off. Therefore, the driver voltage Vdrv is not supplied to the driver voltage line 75. This state is referred to as the initial state.

[0031] Here, when the shift signal p1 (φ1) transitions from "L" (0V) to "H" (5V), the voltage difference between the emitter E ("H" (5V)) and base B (p-gate Gp) (0.83V) of the pnp transistor Tr2 of the shift thyristor T(1) of 4.17V becomes equal to or greater than the forward voltage Vd (1.5V), the emitter E-base B becomes forward biased, and the pnp transistor Tr2 transitions from the OFF state to the ON state. Then, the collector C (base B of the npn transistor Tr1) of the pnp transistor Tr2 becomes 4.7V, which is the emitter E ("H" (5V)) minus the saturation voltage Vc (0.3V). The voltage difference (4.7V) between the emitter E (0V) and base B (4.7V) of the npn transistor Tr1 becomes equal to or greater than the forward voltage Vd (1.5V), and the emitter E and base B become forward biased, so the npn transistor Tr1 transitions from the off state to the on state. The npn transistor Tr1 and the pnp transistor Tr2 in the shift thyristor T(1) transition to the on state, so the shift thyristor T(1) transitions from the off state to the on state. The transition of the shift thyristor T from the off state to the on state is referred to as turning on. The transition of the shift thyristor T from the on state to the off state is referred to as turning off.

[0032] In the initial state, when the shift signal p1 (φ1) transitions from "L" (0V) to "H" (5V), the shift thyristor T(1) turns on and transitions from the off state to the on state. Therefore, the state in which the anode A can turn on when it becomes "H" (5V) is expressed as the state in which it can transition to the on state. The same applies to other cases.

[0033] When the shift thyristor T(1) turns on, the n gate Gn of the shift thyristor T(1) becomes 0.3V, which is the saturation voltage Vc. Also, the anode A becomes a voltage determined by the sum of the forward voltage Vd and the saturation voltage Vc (Vd+Vc) and the voltage drop due to the internal resistance of the shift thyristor T. Here, it is assumed that the anode A becomes 1.9V. In other words, when the shift thyristor T(1) turns on, the shift signal line 72-1 transitions from 5V to 1.9V. Then, the p gate Gp of the shift thyristor T(1) becomes 1.6V.

[0034] As described above, the shift thyristor T(1) turns on when the voltage of the n gate Gn becomes lower than the voltage of the anode A by the forward voltage Vd (1.5 V) or more. The shift thyristor T(1) turns off when the voltage of the shift signal line 72-1 (the voltage between the anode A and the cathode K) becomes less than the above 1.9 V. For example, when the anode A becomes "L" (0 V), the voltage difference between the anode A and the cathode K becomes 0 V, so the shift thyristor T(1) turns off. On the other hand, if the voltage of the shift signal line 72-1 (the voltage difference between the anode A and the cathode K) is 1.9 V or more, the shift thyristor T(1) is maintained in the on state. Therefore, 1.9 V is represented as the holding voltage. Even if the holding voltage is applied, if there is no current flowing to maintain the shift thyristor T(1) in the on state, the shift thyristor T(1) is not maintained in the on state. The current that maintains the on-state is referred to as the holding current.

[0035] Next, the operation of the coupling transistor Q(1) will be described. If the shift thyristor T(1) is in the off state, the npn transistor Tr1 is in the off state. Therefore, the coupling transistor Q(1) is also in the off state. At this time, in the coupling transistor Q(1), the emitter E is set to the ground potential GND (0V). The collector Cf is at the power supply potential VGK (5V) via the power supply line resistance Rg and the coupling resistance Rc, which are connected in series. In addition, the collector Cs is at the light-emitting voltage VLD (5V) via the current limiting resistance RL.

[0036] When the shift thyristor T(1) turns on, that is, when the npn transistor Tr1 is turned on, the p-gate Gp of the shift thyristor T(1) becomes 1.6V as described above. Then, since the base B of the coupling transistor Q(1) is connected to the p-gate Gp of the shift thyristor T(1), the forward voltage Vd (1.5V) or more is applied between the emitter E and base B, that is, the coupling transistor Q(1) transitions from the off state to the on state. Then, the collector Cf becomes the saturation voltage Vc (0.3V) (the collector Cs will be described later). The connection point between the power supply line resistance Rg and the coupling resistance Rc (the n-gate Gn of the shift thyristor T(2)) becomes a voltage obtained by dividing the voltage difference (4.7V) between the voltage of the power supply line 71 (5V) and the voltage of the collector Cf (0.3V) by the power supply line resistance Rg and the coupling resistance Rc. If the resistance ratio of the power supply line resistance Rg and the coupling resistance Rc is 5:1 as an example, the connection point between the power supply line resistance Rg and the coupling resistance Rc (the n gate Gn of the shift thyristor T(2)) becomes 1.08V.

[0037] The anode A of the shift thyristor T(2) is connected to the shift signal line 72-2 to which the shift signal p2 (φ2) is supplied. Since the shift signal p2 (φ2) is "L" (0V), the shift thyristor T(2) does not turn on. However, when the shift signal p2 (φ2) transitions from "L" (0V) to "H" (5V), the anode A of the shift thyristor T(2) becomes "H" (5V), and the voltage difference (3.92V) with the n gate Gn (1.08V) becomes equal to or greater than the forward voltage Vd (1.5V), that is, the n gate Gn-anode A becomes forward biased, and the shift thyristor T(2) turns on. In this way, there are a plurality of elements, and the operation in which the elements to be turned on among the plurality of elements transition one after another is the shift operation. Also, in the embodiment in this specification, the element that is turned on or off by this shift operation is the shift element.

[0038] Finally, the operation of the light-emission control thyristor S(1) and the VCSEL(1) will be described. The collector Cs of the coupling transistor Q(1) is connected to the n-gate Gn of the light-emitting control thyristor S(1). Therefore, when the coupling transistor Q(1) is turned on, the pn junction between the anode An and gate Gn of the light-emitting control thyristor S becomes forward, and the collector Cs draws in a current from the light-emitting voltage VLD through the pn junction between the anode An and gate Gn of the light-emitting control thyristor S, resulting in a voltage of approximately 3.5V obtained by subtracting the forward voltage Vd (1.5V) from the light-emitting voltage VLD (5V). Here, when the driver Drv is turned on and the driver voltage Vdrv becomes the GND voltage (0V), the cathode K of the VCSEL(1) becomes 0V. Therefore, the voltage difference (5V) between the light-emitting voltage VLD (5V) and the driver voltage Vdrv (0V) is applied between the anode A of the light-emitting control thyristor S(1) and the cathode K of the VCSEL(1). This turns on the light-emission control thyristor S(1), causing current to flow through the series-connected light-emission control thyristor S(1) and VCSEL(1), causing VCSEL(1) to emit light. Note that when the coupling transistor Q(1) is turned on and the n-gate Gn of the light-emission control thyristor S(1) is at 3.5 V, the VCSEL(1) emits light when the driver Drv is turned on. Therefore, this state, in which the coupling transistor Q(1) is turned on and a forward bias (3.5 V) is applied between the anode An and gate Gn of the light-emission control thyristor S(1), is referred to as the state in which the VCSEL(1) is capable of emitting light. The light-emission control thyristor S controls the light emission of the VCSEL by the potential of the n-gate Gn, and is therefore referred to as the light-emission control thyristor.

[0039] That is, the initial state is a state in which the power supply line 71 is set to the power supply potential VGK (5V), the ground line 73 is set to the ground potential GND (0V), the shift signals p1 (φ1) and p2 (φ2) are "L" (0V), the driver Drv is off, and the driver voltage Vdrv is not supplied to the driver voltage line 75. In the initial state, the shift thyristor T(1) is in a state in which it can transition to the ON state. Here, when the shift signal p1 (φ1) (shift signal line 72-1) transitions from "L" (0V) to "H" (5V), the shift thyristor T(1) turns on and transitions from the OFF state to the ON state. When the shift thyristor T(1) turns on, the coupling transistor Q(1) transitions from the OFF state to the ON state. Then, the anode A and the n-gate Gn of the light-emission control thyristor S(1) are forward biased, and the VCSEL(1) is in a state in which it can emit light. Furthermore, when the coupling transistor Q(1) is turned on, the shift thyristor T(2) is able to transition to the on state. When the shift signal p2 (φ2) (shift signal line 72-2) transitions from "L" (0V) to "H" (5V), the shift thyristor T(2) turns on. When the shift signal p1 (φ1) (shift signal line 72-1) transitions from "H" (5V) to "L" (0V), the cathode K and anode A of the shift thyristor T(1) become "L" (0V), and the shift thyristor T(1) is turned off. The other shift thyristors T, coupling transistors Q, light-emission control thyristors S and VCSELs operate in the same manner.

[0040] As shown in FIG. 2(b), the light emitting device 10 is configured by stacking a plurality of semiconductor layers (see FIG. 3 described later). FIG. 2(b) shows a portion where an n-type semiconductor layer 85, a p-type semiconductor layer 86, an n-type semiconductor layer 87, and a p-type semiconductor layer 88 constituting the shift thyristor T(1) and the coupling transistor Q(1) are stacked. The shift thyristor T(1) is configured with the n-type semiconductor layer 85 as the cathode K, the p-type semiconductor layer 86 as the p-gate Gp, the n-type semiconductor layer 87 as the n-gate Gn, and the p-type semiconductor layer 88 as the anode A. On the other hand, the coupling transistor Q(1) is configured with the n-type semiconductor layer 85 as the emitter E, the p-type semiconductor layer 86 as the base B, and the n-type semiconductor layer 87 as the collectors Cf and Cs. Here, the cathode K of the shift thyristor T(1) and the emitter E of the coupling transistor Q(1) are electrically connected via the n-type semiconductor layer 85. Similarly, the p-gate Gp of the shift thyristor T(1) and the base B of the coupling transistor Q(1) are electrically connected via a p-type semiconductor layer 86. And, the n-gate Gn of the shift thyristor T(1) and the collectors Cf, Cs of the coupling transistor Q(1) are both composed of an n-type semiconductor layer 87, but are separated. The same is true for the other shift thyristors T and coupling transistors Q.

[0041] Fig. 3 is a diagram illustrating the layout and cross section of the light emitting device 10. Fig. 3(a) is the layout, and Fig. 3(b) is a cross section taken along line IIIB-IIIB in Fig. 3(a). Fig. 3(a) mainly illustrates the shift thyristors T(1)-(4), the coupling transistors Q(1)-(4), the light emission control thyristors S(1)-S(4), and the VCSEL(1)-(4). Fig. 3(b) illustrates a cross section of the light emission control thyristor S(1), the VCSEL(1), the shift thyristor T(1), the coupling transistor Q(1), the coupling resistor Rc connected to the coupling transistor Q(1), and the power line resistor Rg.

[0042] As shown in FIG. 3(b), the light emitting device 10 is configured by stacking an n-type semiconductor layer 81, an active layer 82, a p-type semiconductor layer 83, a tunnel junction layer 84, an n-type semiconductor layer 85, a p-type semiconductor layer 86, an n-type semiconductor layer 87, and a p-type semiconductor layer 88 on an n-type semiconductor substrate 80. The elements such as the shift thyristor T, the coupling transistor Q, the light emission control thyristor S, and the VCSEL are configured from a plurality of islands separated by removing a part of the semiconductor layer by etching. The island may be referred to as a mesa, and the etching for forming the island (mesa) may be referred to as mesa etching. In the following, the islands (islands 300, 301 to 307) will be described, focusing on the island 301 where the light emission control thyristor S(1) and the VCSEL(1) are provided, and the island 302 where the shift thyristor T(1) and the coupling transistor Q(1) are provided.

[0043] The island 300 is a portion in which the shift section 12 (see FIG. 1) such as the shift thyristor T(1) and the coupling transistor Q(1) is provided, and an n-type semiconductor layer 81, an active layer 82, a p-type semiconductor layer 83, a tunnel junction layer 84, and an n-type semiconductor layer 85 are left on an n-type semiconductor substrate 80 without being removed.

[0044] A VCSEL(1) and a light-emission control thyristor S(1) are stacked on an island 301. A shift thyristor T(1) and a coupling transistor Q(1) shown in FIG. 2(b) are provided on an island 302. A current-limiting resistor RL is provided on an island 303, and a power supply line resistor Rg and a coupling resistor Rc are provided on an island 304. A power supply line resistor Rg and a start resistor Rs are provided on an island 305. A current-limiting resistor R1 is provided on an island 306, and a current-limiting resistor R2 is provided on an island 307.

[0045] The layout and cross section will be described below with reference to FIGS. Around the island 301, the n-type semiconductor layer 81, the active layer 82, the semiconductor layer 83, the tunnel junction layer 84, and the semiconductor layers 85 to 88 are removed by etching. A p-ohmic electrode 321 that easily makes ohmic contact with the p-type semiconductor layer is provided on the p-type semiconductor layer 88. An n-ohmic electrode 331 that easily makes ohmic contact with the n-type semiconductor layer is provided on the n-type semiconductor layer 87 that is exposed by removing the p-type semiconductor layer 88. In the VCSEL (1), the n-type semiconductor layer 81 is the cathode K (see FIG. 2(a)), the active layer 82 is the active layer, and the p-type semiconductor layer 83 is the anode A. In the light-emitting control thyristor S (1), the n-type semiconductor layer 85 is the cathode K, the p-type semiconductor layer 86 is the p-gate Gp (p-gate layer), the n-type semiconductor layer 87 is the n-gate Gn (n-gate layer), and the n-type semiconductor layer 88 is the anode A. The n-ohmic electrode 331 is the n-gate Gn of the light-emission control thyristor S(1).

[0046] As shown in FIG. 3(b), a VCSEL(1) is provided on an n-type semiconductor substrate 80, and an emission control thyristor S(1) is provided on the VCSEL(1) via a tunnel junction layer 84. The tunnel junction layer 84 prevents a p-type semiconductor layer 83 of the VCSEL(1) and an n-type semiconductor layer 85 of the emission control thyristor S(1) from being reverse biased, making it difficult for a current to flow. The tunnel junction layer 84 is an n-type semiconductor layer doped with a high concentration of n-type impurities. ++ layer and p-type highly doped p ++ Even in the case of reverse bias, a current flows due to the tunnel effect.

[0047] The island 301 is cylindrical except for the portion where the n-ohmic electrode 331 is provided. The p-ohmic electrode 321 is provided in an annular shape on the p-type semiconductor layer 88 of the cylindrical island 301. A part of the semiconductor layer constituting the p-type semiconductor layer 83 exposed by etching is oxidized from the cylindrical outer periphery, forming a current blocking portion β through which current does not easily flow in an annular shape. On the other hand, the central portion that is not oxidized becomes a current passing portion α through which current easily flows. Light is emitted from the central portion of the annular p-ohmic electrode 321. The current blocking portion β is formed by providing an AlAs layer or an AlGaAs layer with a high Al concentration in the p-type semiconductor layer 83, and oxidizing the exposed outer periphery to oxidize Al. The peripheral portion of the VCSEL (1) has many defects due to etching, and non-radiative recombination is likely to occur. Therefore, by providing the current blocking portion β, the power consumed by non-radiative recombination is suppressed. By providing the current blocking portion β, it is possible to reduce power consumption and improve light extraction efficiency. The light extraction efficiency is the amount of light that can be extracted per unit of electric power.

[0048] 3(a) and 3(b), the VCSEL(1) emits light through the light-emission control thyristor S(1). Note that the light-emission control thyristor S(1) (tunnel junction 84, semiconductor layers 85-88) in the portion of the island 301 from which the light is emitted may be removed. In this case, the light-emission control thyristor S(1) becomes cylindrical. This prevents the light emitted by the VCSEL(1) from being absorbed by the light-emission control thyristor S(1) and causing a decrease in the amount of light.

[0049] Around the island 302, the p-type semiconductor layer 86, the n-type semiconductor layer 87, and the p-type semiconductor layer 88 are removed by etching (see FIG. 2(b)). A p-ohmic electrode 322 is provided on the p-type semiconductor layer 88. The p-ohmic electrode 322 is an electrode (anode A electrode) connected to the anode A of the shift thyristor T(1), and is connected to a shift signal line 72-1 to which a shift signal p1 (φ1) is supplied. N-ohmic electrodes 332, 333, and 334 are provided on the n-type semiconductor layer 87 exposed by removing the p-type semiconductor layer 88. The n-ohmic electrodes 332 and 334 are electrodes (collector Cf and Cs electrodes) connected to the collectors Cs and Cf of the coupling transistor Q(1). The n-type semiconductor layer 87 between the p-ohmic electrode 322 and the n-ohmic electrodes 332 and 334 is removed (see FIG. 2(b)). The n-ohmic electrode 333 is an electrode (n-gate Gn electrode) connected to the n-gate Gn of the shift thyristor T(1).

[0050] Around the island 303, the p-type semiconductor layer 86, the n-type semiconductor layer 87, and the p-type semiconductor layer 88 are removed by etching. Furthermore, in the island 303, two n-ohmic electrodes 335, 336 are provided on the exposed n-type semiconductor layer 87. The n-type semiconductor layer 87 between the two n-ohmic electrodes 335, 336 is a current limiting resistor RL.

[0051] Island 304 is configured similarly to island 303. Three n-ohmic electrodes 337, 338, and 339 are provided on n-type semiconductor layer 87 exposed by removing p-type semiconductor layer 88. The n-type semiconductor layer 87 between n-ohmic electrodes 337 and 338 is a coupling resistance Rc, and the n-type semiconductor layer 87 between n-ohmic electrodes 338 and 339 is a power line resistance Rg.

[0052] The island 305 is configured similarly to the island 304, and is provided with a start resistor Rs and a power line resistor Rg. The islands 306 and 307 are configured similarly to the island 303, and are provided with current limiting resistors R1 and R2.

[0053] An n-ohmic electrode 338 is provided on the exposed n-type semiconductor layer 85 of the island 300. On the back surface of the n-type semiconductor substrate 80, a back surface electrode 79 is provided.

[0054] Next, the connections will be described. In Fig. 3(a), the wiring used for the connections (power supply line 71, shift signal lines 72-1 and 72-2, and voltage supply line 74) are shown as straight lines. A p-ohmic electrode 321 which is an anode A electrode of the light-emission control thyristor S(1) of the island 301 is connected to a voltage supply line 74 to which a light-emission voltage VLD is supplied. An n-ohmic electrode 331 which is an n-gate Gn electrode of the light-emission control thyristor S(1) of the island 301 is connected to an n-ohmic electrode 332 which is a collector Cs electrode of the coupling transistor Q(1) of the island 302. The n-ohmic electrode 332 is connected to an n-ohmic electrode 336 of a current limiting resistor RL provided in the island 303. An n-ohmic electrode 335 of the island 303 is connected to the voltage supply line 74.

[0055] A p-ohmic electrode 322 which is an anode A electrode of the shift thyristor T(1) of the island 302 is connected to a shift signal line 72-1. The shift signal line 72-1 is connected to a φ1 terminal to which a shift signal p1 is supplied via a current limiting resistor R1 provided in the island 306. An n-ohmic electrode 333 which is an n-gate Gn electrode of the shift thyristor T(1) of the island 302 is connected to an n-ohmic electrode (without symbol) which is a connection point between the power supply line resistor Rg and the start resistor Rs provided in the island 305. An n-ohmic electrode 334 which is a collector Cf electrode of the coupling transistor Q(1) of the island 302 is connected to one n-ohmic electrode 337 of the coupling resistor Rc of the island 304.

[0056] The other n-ohmic electrode 338 of the coupling resistance Rc of the island 304 is connected to an n-ohmic electrode (no symbol) which is the n-gate Gn electrode of the shift thyristor T(2). The other n-ohmic electrode 339 of the power supply line resistance Rg of the island 304 is connected to the power supply line 71 to which the power supply potential VGK is supplied.

[0057] One n-ohmic electrode (no symbol) of the start resistance Rs of the island 305 is connected to the shift signal line 72-2. The other n-ohmic electrode (no symbol) of the power supply line resistance Rg of the island 305 is connected to the power supply line 71. The shift signal line 72-2 is connected to a φ2 terminal to which a shift signal p2 (φ2) is supplied via a current limiting resistance R2 provided in the island 307.

[0058] The shift signal line 72-1 is connected to the p-ohmic electrode which is the anode A electrode of the odd-numbered shift thyristors T, and the shift signal line 72-2 is connected to the p-ohmic electrode which is the anode A electrode of the even-numbered shift thyristors T.

[0059] The other shift thyristors T, coupling transistors Q, light-emission control thyristors S, and VCSELs are configured similarly to the shift thyristor T(1), coupling transistor Q(1), light-emission control thyristor S(1), and VCSEL(1).

[0060] The n-ohmic electrode 338 of the exposed n-type semiconductor layer 85 of the island 300 serves as a GND terminal to which the ground potential GND is supplied, and the rear surface electrode 79 on the rear surface of the n-type semiconductor substrate 80 serves as a Vdrv terminal to which the driver voltage Vdrv is supplied.

[0061] The shift thyristor T and the coupling transistor Q are provided on a laminated semiconductor layer (structure) equivalent to the layer in which the light-emitting control thyristor S and the VCSEL are configured. However, an n-ohmic electrode 338 is provided on the n-type semiconductor layer 85 and set to the ground potential GND. On the other hand, a driver voltage Vdrv (≧0V) is supplied to the back electrode 79 on the back surface of the n-type semiconductor substrate 80. That is, the n-type semiconductor layer 81 always has a lower potential than the anode A with respect to the p-type semiconductor layer 83, and the pn junction formed by the n-type semiconductor layer 81, the active layer 82, and the p-type semiconductor layer 83 does not have a forward direction. That is, the semiconductor layer 85 included in the island 300 is insulated from the back electrode 79.

[0062] As described above, the light emitting device 10 is provided on a semiconductor substrate 80 made of a single semiconductor.

[0063] Fig. 4 is a timing chart for operating the light source device 1 to which the first embodiment is applied. The horizontal axis represents time, which progresses in alphabetical order from time a to time r. Fig. 4 shows changes over time in the shift signals p1, p2 and the light-emission signal pI, and indicates the numbers of the shift thyristor T, light-emission control thyristor S and VCSEL that are turned on. The light-emission control thyristor S and VCSEL are indicated as S / VCSEL.

[0064] Here, in the light emitting device 10 shown in Fig. 1, it is assumed that VCSEL(1) and VCSEL(6) are caused to emit light. After VCSEL(1) is caused to emit light from the initial state, the light emitting device 10 is returned to the initial state, and then VCSEL(6) is caused to emit light. In other words, VCSEL(1) and VCSEL(6) are caused to emit light. In this manner, the VCSELs can be arbitrarily selected to emit light. In other words, the VCSELs can be caused to emit light randomly.

[0065] As described in FIG. 2, the VCSEL (1) is made to emit light by turning on the shift thyristor T (1). The VCSEL (6) is made to emit light by turning on the shift thyristor T (6). The VCSEL (1) and VCSEL (6) are made to emit light intermittently multiple times (five times in FIG. 4). By making them emit light in this manner, the light-emission control thyristor S is more likely to maintain a state in which it can emit light, and once the shift thyristor T has made it possible to emit light, it is easier to make them emit light again regardless of whether the shift thyristor T is on.

[0066] The timing chart of FIG. 4 will be described with reference to FIG. Before time a, the state is the initial state. The initial state is a state in which the power supply line 71 is set to the power supply potential VGK (5V), the ground line 73 is set to the ground potential GND (0V), the shift signals p1 (φ1) and p2 (φ2) are "L" (0V), the driver Drv is off, and the driver voltage Vdrv is not supplied to the driver voltage line 75. At this time, the shift thyristor T(1) is in a state in which it can transition to the on state.

[0067] At time a, when the shift signal p1 transitions from "L" (0 V) to "H" (5 V), the shift thyristor T(1) turns on and transitions from the OFF state to the ON state. Then, a forward bias is applied between the anode An and gate Gn of the light-emission control thyristor S(1), and the VCSEL(1) enters a state in which it can emit light. At time b, the light-emitting signal pI transitions from "L" (0 V) to "H" (5 V). The driver Drv changes from off to on, and the driver voltage Vdrv becomes the ground potential GND (0 V). This turns on the light-emitting control thyristor S(1), and a light-emitting voltage VLD (5 V) is applied between the anode A of the light-emitting control thyristor S(1) and the cathode K of the VCSEL(1). This causes a current to flow through the light-emitting control thyristor S(1) and VCSEL(1), which are connected in series, and the VCSEL(1) emits light.

[0068] At time c, when the shift signal p1 transitions from "H" (5V) to "L" (0V), the shift thyristor T(1) turns off and transitions from the on state to the off state. Furthermore, at time c, when the light emission signal pI transitions from “H” (5 V) to “L” (0 V), no current flows between the anode A of the light emission control thyristor S(1) and the cathode K of the VCSEL(1), and the VCSEL(1) stops emitting light (becomes quenched). After that, between time c and time d, the light emission signal pI is changed four times from "L" (0V) to "H" (5V) and then from "H" (5V) to "L" (0V), causing the VCSEL (1) to emit light four times. The VCSEL emits light intermittently, so this is referred to as an emission pulse. The period from time b to time c is the pulse width, and the period between the emission pulses (the period from time s to time t in Figure 6(a) described below) is the pulse interval.

[0069] Between time c and time d, the shift signal p1 (φ1) is “L” (0 V), the shift thyristor T(1) is in the off state, and no current flows. The same is true for the other shift thyristors T. Therefore, power consumption in the shift unit 12 (see FIG. 1) is suppressed.

[0070] At time d, the initial state is reached. At this time, the shift thyristor T(1) is in a state in which it can transition to the ON state.

[0071] At time e, when the shift signal p1 transitions from "L" (0V) to "H" (5V), the shift thyristor T(1) turns on and transitions from the OFF state to the ON state, similar to the time a. At time f, when the shift signal p2 transitions from "L" (0V) to "H" (5V), the shift thyristor T(2) is turned on.

[0072] At time g, when the shift signal p1 transitions from "H" (5V) to "L" (0V), the shift thyristor T(1) is turned off. In this order, at time h, the shift thyristor T(3) is turned on, and at time i, the shift thyristor T(2) is turned off. Furthermore, at time j, the shift thyristor T(4) is turned on, and at time k, the shift thyristor T(3) is turned off. At time l, the shift thyristor T(5) is turned on, and at time m, the shift thyristor T(4) is turned off. At time n, the shift thyristor T(6) is turned on, and at time o, the shift thyristor T(5) is turned off. At this time, a forward bias is applied between the anode An and gate Gn of the light-emission control thyristor S(6), and the VCSEL(6) is able to emit light.

[0073] At time p, the light emission signal pI transitions from "L" (0 V) to "H" (5 V). The driver Drv turns from off to on, and the driver voltage Vdrv becomes the ground potential GND (0 V). Then, just like at time b, the VCSEL (6) emits light.

[0074] At time q, when the shift signal p2 transitions from "H" (5V) to "L" (0V), the shift thyristor T(6) is turned off. Furthermore, at time q, when the light emission signal pI transitions from "H" (5 V) to "L" (0 V), the VCSEL (6) stops emitting light (becomes quenched). After that, between time q and time r, the light emission signal pI is changed four times, from “L” (0 V) to “H” (5 V) and from “H” (5 V) to “L” (0 V), causing the VCSEL (6) to emit light four times.

[0075] Between time q and time r, the shift signal p2 (φ1) is “L” (0 V), the shift thyristor T (6) is in the off state, and no current flows. The same is true for the other shift thyristors T. Therefore, power consumption in the shift unit 12 (see FIG. 1) is suppressed.

[0076] As described above, the shift section 12 turns on the shift thyristor T located upstream of the two adjacent shift thyristors T, then turns on the shift thyristor T located downstream of the shift, and then turns off the shift thyristor T located upstream of the shift. In this way, in the shift section 12, the on state is shifted by the shift operation of the shift thyristors T by shift signals (shift signal p1 and shift signal p2) with a phase difference of 180 degrees, during which two adjacent shift thyristors T are simultaneously turned on (for example, from time f to time g).

[0077] Fig. 5 is a timing chart for operating a light source device 1 different from that in Fig. 4. This timing chart is referred to as a conventional example. The light emitting device 10 is the same, and the horizontal axis in Fig. 5 is the same as that in Fig. 4.

[0078] In the conventional example shown in FIG. 5, the shift thyristor T(1) is maintained in the ON state during the period from time c to time d when the VCSEL(1) intermittently repeats the emission of light. Similarly, the shift thyristor T(6) is maintained in the ON state during the period from time q to time r when the VCSEL(6) intermittently repeats the emission of light. During these periods, a current that maintains the ON state continues to flow through the shift thyristor T(1) or the shift thyristor T(6). Therefore, the conventional example consumes more power than the operation of the light source device 1 shown in the timing chart to which the first embodiment is applied in FIG. 4. In addition, in the conventional example shown in FIG. 5, since the shift thyristor T(1) is maintained in the ON state, even if an erase pulse described later is input, a forward bias is applied between the anode An and gate Gn of the light-emission control thyristor S, and the VCSEL maintains a state in which it can emit light.

[0079] Next, the intermittent emission of light from the VCSEL during the period in which the shift thyristor T is in the OFF state (for example, the period from time c to time d in FIG. 4) will be described.

[0080] FIG. 6 is a diagram showing the voltage at the light-emission control thyristor S(1) and the light-emission current of the VCSEL(1) in a series connection of the light-emission control thyristor S(1) and the VCSEL(1). FIG. 6(a) is a set timing chart, and FIG. 6(b) is the voltage at the light-emission control thyristor S(1) and the light-emission current of the VCSEL(1). FIG. 6(a) is a part of the timing chart shown in FIG. 4 starting from time a. Note that between time c and time d (see FIG. 4), times s to y are added in alphabetical order. In FIG. 6(b), the horizontal axis is time (ns), and the left vertical axis is the voltages (V) of the p-gate Gp, n-gate Gn, and cathode K of the light-emission control thyristor S(1). The right vertical axis is the light-emission current (mA) of the VCSEL(1).

[0081] The timing chart set in FIG. 6(a) will be explained. At time a, the shift signal p1 is shifted from "L" (0V) to "H" (5V) to turn on the shift thyristor T(1). At time b, the light-emitting signal pI is shifted from "L" (0V) to "H" (5V) to make the VCSEL(1) emit light. This time is set to 100 ns on the time axis of FIG. 6(b). Then, at time c, 10 ns after time b, the shift signal p1 is shifted from "H" (5V) to "L" (0V) to turn off the shift thyristor T(1). At time s, 10 ns after time c, the light-emitting signal pI is shifted from "H" (5V) to "L" (0V) to turn off the VCSEL(1). At time t, 100 ns after time s, the light-emitting signal pI is shifted again from "L" (0V) to "H" (5V) to make the VCSEL(1) emit light again. After this, the light emission signal pI is repeated from time b to time t. That is, VCSEL(1) emits light for 20 ns from time b of 100 ns, goes out, pauses for 100 ns, and then emits light again for 20 ns. Then, the light emission is repeated at the same time interval. In this manner, during this period, even if the shift signal p1 is shifted from "H" (5 V) to "L" (0 V) to turn off the shift thyristor T(1), VCSEL(1) will emit light due to the light emission signal pI. Here, if VCSEL(6) is to be made to emit light after VCSEL(1), if the time interval is too short, VCSEL(1) will also be erroneously turned on. Specifically, if an interval is set as short as the interval from time s to time t, and VCSEL(6) is set as the next VCSEL to emit light by the shift thyristor T(6), not only VCSEL(6) but also VCSEL(1) will emit light.

[0082] Figure 6(b) shows the results of a simulation in which the light emission current limiting resistor RI in Figure 1 is 100Ω, the power supply potential VGK supplied by the power supply VS1 and the light emission voltage VLD supplied by the power supply VS2 are both 5V, the on-resistance Ron of the driver Drv is 1Ω, and the off-resistance Roff is 1MΩ. The p-gate Gp is ​​not extracted, but Figure 6(b) shows the voltage of the p-gate Gp.

[0083] FIG. 7 shows an equivalent circuit of the light-emission control thyristor S(1) and the VCSEL(1). FIG. 7(a) shows the equivalent circuit, and FIG. 7(b) shows the parasitic capacitance of the semiconductor layers and the pn junction. FIG. 7(b) shows an n-type semiconductor layer 81 constituting the cathode K and a p-type semiconductor layer 83 constituting the anode A in the VCSEL(1), and an n-type semiconductor layer 85 constituting the cathode K, a p-type semiconductor layer 86 constituting the p-gate Gp, an n-type semiconductor layer 87 constituting the n-gate Gn, and a p-type semiconductor layer 88 constituting the anode A in the light-emission control thyristor S (see FIG. 3(b)). The active layer 82 and the tunnel junction layer 84 are omitted.

[0084] In the VCSEL(1), a parasitic capacitance Cv exists at the pn junction between the cathode K (n-type semiconductor layer 81) and the anode A (p-type semiconductor layer 83). In the light-emission control thyristor S(1), a parasitic capacitance Cgk exists at the pn junction between the cathode K (n-type semiconductor layer 85) and the p-gate Gp (p-type semiconductor layer 86), a parasitic capacitance Cgg exists at the pn junction between the p-gate Gp (p-type semiconductor layer 86) and the n-gate Gn (n-type semiconductor layer 87), and a parasitic capacitance Cag exists at the pn junction between the n-gate Gn (n-type semiconductor layer 87) and the anode A (p-type semiconductor layer 88). Note that a tunnel junction layer 84 exists between the anode A (p-type semiconductor layer 83) of the VCSEL(1) and the cathode K (n-type semiconductor layer 85) of the light-emission control thyristor S(1), and these have the same potential. Therefore, no parasitic capacitance occurs between the anode A (p-type semiconductor layer 83) of the VCSEL and the cathode K (n-type semiconductor layer 85) of the light-emission control thyristor S(1).

[0085] The timing chart of FIG. 6(a) will be described with reference to FIGS. 7(a) and 7(b). At time a, when the shift thyristor T(1) is turned on, the collector Cs of the coupling transistor Q(1) starts to draw current from the n-gate Gn of the light-emission control thyristor S. Here, since the light-emission voltage VLD (voltage supply line 74) is 5V, the voltage of the anode A of the light-emission control thyristor S(1) is 5V. Therefore, a forward bias is applied between the anode A and the n-gate Gn of the light-emission control thyristor S(1), and the voltage of the n-gate Gn becomes 3.5V, which is the voltage of the anode A minus the forward voltage Vd (1.5V). The voltage of the p-gate Gp becomes 4.7V, which is the voltage of the anode A minus the saturation voltage Vc (0.3V). In addition, the voltage of the cathode K becomes 1.7V, which is lower than the voltage of the p-gate Gp by 2×Vd, taking into account the forward voltage Vd (1.5V) of the VCSEL(1). This is the state just before time b in FIG. 6(a), and just before 100 ns on the time axis in FIG. 6(b).

[0086] At time b, when the light emission signal pI changes from "L" (0V) to "H" (5V) and the driver Drv is turned on, the driver voltage line 75 to which the cathode K of the VCSEL is connected becomes the ground potential GND via the driver Drv and the light emission current limiting resistor RI. This turns on the light emission control thyristor S(1) and the VCSEL(1) emits light. In the simulation results shown in Figure 6(b), the light emission current flows, causing the voltages of the n gate Gn, p gate Gp, and cathode K to be approximately 3.2V, 4.7V, and 1.7V, respectively.

[0087] Even if the shift signal p1 transitions from "H" (5V) to "L" (0V) at time c, the voltage of the n gate Gn does not change because the VCSEL(1) is emitting light.

[0088] At time s, when the light emission signal pI changes from "H" (5V) to "L" (0V) and the driver Drv turns off, the driver Drv switches from an on-resistance Ron of 1Ω to an off-resistance Roff of 1MΩ. If the off-resistance Roff is sufficiently large, the current between the anode A of the light emission control thyristor S(1) and the cathode K of the VCSEL(1) becomes equal to or less than the holding current, the light emission control thyristor S turns off, and the VCSEL(1) goes out of light. Since the n gate Gn is connected to the voltage supply line 74 of the light emission voltage VLD (5V) via the current limiting resistor RL, the voltage of the n gate Gn rises toward the light emission voltage VLD (5V). That is, the parasitic capacitance Cag (capacity is Cag) discharges via the current limiting resistor RL (resistance value is RL) with a time constant of RL×Cag. On the other hand, the charges stored in the parasitic capacitances Cgg, Cgk, and Cv cannot move, so the voltages of the p gate Gp and cathode K rise by the amount that the voltage of the n gate Gn rises. In Figure 6(b), the voltages of the n gate Gn, p gate Gp, and cathode K are about 5V, 6V, and 3V.

[0089] At time t, when the light-emitting signal pI changes from "L" (0 V) to "H" (5 V) and the driver Drv turns on again, the driver voltage line 75 to which the cathode K of VCSEL(1) is connected suddenly changes toward the ground potential GND (0 V). As a result, a displacement current flows through the parasitic capacitances Cag, Cgg, and Cgk, and with this as the threshold current, the light-emitting control thyristor S(1) turns on, causing the VCSEL(1) to emit light. At time u, when the light-emission signal pI changes from "H" (5 V) to "L" (0 V) and the driver Drv turns off, the light-emission control thyristor S turns off in the same manner as at time s, and the VCSEL (1) ceases to emit light. By repeating the process from time s to time t, the VCSEL (1) emits light intermittently multiple times.

[0090] Fig. 8 is a diagram showing the voltage of the cathode K of the light-emission control thyristor S(1) and the light-emission current of the VCSEL(1) when the off-resistance Roff of the driver Drv is changed. Fig. 8 shows the results of a simulation in which the off-resistance Roff is set to 50 kΩ, 100 kΩ, 200 kΩ, 500 kΩ, and 1 MΩ. The timing chart set is that shown in Fig. 6(a).

[0091] The smaller the off-resistance Roff is, the greater the drop in voltage at the cathode K of the light-emission control thyristor S(1) after the VCSEL(1) is turned off. When the off-resistance Roff is set to 100 kΩ, 200 kΩ, 500 kΩ, and 1 MΩ, the light-emission control thyristor S(1) in FIG. 6(a) emits light again at time t after the light-emission control thyristor S(1) is turned off, that is, after the shift unit 12 is turned off. In other words, even after the shift unit 12 is turned off, the VCSEL(1) can be made to emit light intermittently multiple times (re-emission is possible).

[0092] On the other hand, when the off-resistance Roff is set to 50 kΩ, no light is emitted at time t after the light-emission control thyristor S(1) in Fig. 6(a) is turned off, that is, after the shift unit 12 is turned off. This is because even if the driver Drv is turned on, the light-emission control thyristor S(1) does not turn on because the voltage change in the driver voltage line 75 to which the cathode K of the VCSEL(1) is connected is small and the displacement current is small.

[0093] In the simulation, the voltage of the cathode K at which the light-emission control thyristor S(1) does not turn on was less than 0.9 V. When the light-emission control thyristor S does not turn on, the VCSEL(1) does not emit light again (it becomes unable to emit light again). The voltage of the cathode K is determined by the parasitic capacitance of each pn junction (parasitic capacitances Cgg, Cgk, and Cv in FIG. 7(b)), the threshold current of the light-emission control thyristor S, and the speed dV / dt of voltage change of the driver voltage line 75. The light-emission control thyristor S is an example of a capacitance unit, and the light-emission control thyristor S and the VCSEL connected in series are an example of a light-emitting element having a capacitance unit.

[0094] In order to make the VCSEL emit light intermittently after the shift unit 12 is turned off, it is preferable that the off-resistance Roff of the driver Drv is large. As described above, once a VCSEL is turned on, it becomes unable to emit light again when the voltage of the cathode K of the light-emission control thyristor S becomes less than 0.9 V. As shown in FIG. 8, the voltage of the cathode K of the light-emission control thyristor S decreases less as the off-resistance Roff increases. However, if the off-resistance Roff is too large, the period during which the VCSEL once turned on can emit light again becomes longer. In other words, in order to make another VCSEL emit light after the VCSEL once turned on becomes unable to emit light again, if the period during which the VCSEL once turned on can emit light again is long, the period (pause period) until the other VCSEL is made to emit light is set long.

[0095] 9 is another diagram showing the voltage of the cathode K of the light-emission control thyristor S(1) and the light-emission current of the VCSEL(1) when the off-resistance Roff of the driver Drv is changed. FIG. 9(a) shows the entire light-emission current, and (b) is an enlarged view of the light-emission current in FIG. 9(a). FIGS. 9(a) and (b) show the results of a simulation in which the off-resistance Roff is set to 50 kΩ and 30 kΩ. The set timing chart is that of FIG. 6(a), and the off-resistance Roff of 50 kΩ is the same as the off-resistance Roff of 50 kΩ in FIG. 8.

[0096] If the off-resistance Roff is made small, after the driver Drv is turned off, the voltage of the cathode K of the light-emission control thyristor S quickly approaches 0 V. However, if the off-resistance Roff is made too small, a current equal to or greater than the holding current continues to flow through the light-emission control thyristor S even after the driver Drv is turned off, and the light-emission control thyristor S(1) does not turn off.

[0097] As shown in FIG. 9(a), when the off resistance Roff is 50 kΩ, the second light emission does not occur at time t. However, when the off resistance Roff is 30 kΩ, light emission occurs again at time t. Then, light emission occurs again at the following times v and x. As shown in FIG. 9(b), when the light emission current is enlarged, when the off resistance Roff is 50 kΩ, the light emission current decreases during the period when the driver Drv is off, and becomes almost 0 A after time u. On the other hand, when the off resistance Roff is 30 kΩ, the light emission current flows at 0.07 mA during the period when the driver Drv is off. In other words, a current equal to or greater than the holding current continues to flow through the light-emission control thyristor S(1), and the light-emission control thyristor S(1) maintains the on state.

[0098] From the above, the off-resistance Roff of the driver Drv must be set so that the VCSEL is maintained in a state in which it can re-emit light during the period in which the VCSEL can re-emit light, and the period (pause period) until re-emission is no longer possible is not too long. Furthermore, the off-resistance Roff of the driver Drv must be set so that a current equal to or greater than the holding current does not flow through the light-emission control thyristor S during the period in which the driver Drv is off. In other words, the off-resistance Roff of the driver Drv is set according to a predetermined period until re-emission is no longer possible (pause period).

[0099] [Second embodiment] In the first embodiment, the driver Drv has one off resistance Roff. In the second embodiment, the value of the off-resistance Roff of the driver Drv is switchable.

[0100] FIG. 10 is a diagram for explaining a light source device 2 to which the second embodiment is applied. The control unit 50 of the light source device 2 includes two drivers Drv1 and Drv2 instead of the driver Drv in the first embodiment. The driver Drv1 has an on-resistance Ron1 and an off-resistance Roff1. The driver Drv2 has an on-resistance Ron2 and an off-resistance Roff2. The on-resistance Ron1 and the on-resistance Ron2 may be the same or different. On the other hand, the off-resistance Roff1 and the off-resistance Roff2 are different (for example, Roff1>Roff2). The drivers Drv1 and Drv2 are connected to a light emission current limiting resistor RI via a switch SW. The driver Drv1 and the driver Drv2 are switched by switching the switch. The switch may be an NMOS transistor or the like having a resistance value larger than both the off-resistance Roff1 and the off-resistance Roff2.

[0101] In the driver Drv2 with a small off-resistance Roff2, the voltage of the cathode K of the light-emission control thyristor S decreases faster than in the driver Drv1 with a large off-resistance Roff1. This shortens the period during which the VCSEL emits light intermittently. This shortens the period (pause period) until light cannot be emitted again. Therefore, the period during which light is emitted intermittently may be set by switching between the driver Drv1 and the driver Drv2. The pause period may also be set by switching between the driver Drv1 and the driver Drv2.

[0102] As a method for changing the off-resistance Roff, multiple resistors with different resistance values ​​may be connected in parallel between the source and drain of an NMOS transistor with a sufficiently large off-resistance via switches. By switching the switches, the off-resistance Roff of the driver Drv is changed.

[0103] [Third embodiment] In the light source device 1 to which the first embodiment is applied and the light source device 2 to which the second embodiment is applied, the period (pause period) until re-emission becomes impossible is determined by the off resistance Roff of the driver Drv. In the light source device 3 to which the third embodiment is applied, an erase pulse is provided to erase the VCSEL to a state where re-emission is not possible in order to set the pause period to be short. By providing an erase pulse, it is possible to suppress erroneous emission of the VCSEL in cases where the VCSEL continues to be in a state where it can emit light due to the light-emission control thyristor having been caused to emit light intermittently multiple times, or where the VCSEL has been in a state where it can emit light due to a malfunction of the light-emission control thyristor. Furthermore, if an erase pulse is not provided, in order to suppress re-emission of the VCSEL that previously emitted light, it is necessary to wait for a period (pause period) until the light-emission control thyristor S connected to this VCSEL runs out of charge. This delays the timing at which another VCSEL is caused to emit light, making it difficult to drive at high speed when switching between VCSELs to be emitted one after another. Therefore, by providing an erase pulse, the pause period is shortened, making it easier to drive at high speed.

[0104] FIG. 11 is a diagram for explaining a light source device 3 to which the third embodiment is applied. The control unit 50 of the light source device 3 further includes a driver Drv3 and an erase current limiting resistor RJ in addition to the control unit 50 of the light source device 1 shown in FIG. 1. The driver Drv3 is turned on / off by an erase signal pJ applied to the gate, for example, using an NMOS transistor as a driver element. The source of the NMOS transistor of the driver Drv3 is grounded, and the drain is connected to the Vdrv terminal via the erase current limiting resistor RJ. The erase signal pJ is a signal having a ground potential GND ("L" (0V)) and a power supply potential VGK ("H" (5V)). Here, the driver Drv3 is turned off when the erase signal pJ is "L" (0V), and turned on when the erase signal pJ is "H" (5V). In other words, the period during which the erase signal pJ is "H" (5V) is the pulse width of the erase pulse. The driver Drv is an example of a first driver, and the driver Drv3 is an example of a second driver.

[0105] The driver Drv3 has an on-resistance Ron close to 0Ω and an off-resistance Roff close to infinity. The erase current limiting resistor RJ is set to a value that, when the driver Drv3 is turned on, reduces the voltage of the cathode K of the light-emission control thyristor S during a preset erase period (pulse width of the erase pulse) and renders the VCSEL unable to emit light again. For example, the off resistance Roff shown in FIG. 8(b) is 50 kΩ. As described above, the erase current limiting resistor RJ is set to a value that prevents a current greater than the holding current from flowing through the light-emission control thyristor S.

[0106] Fig. 12 is a timing chart explaining the timing of providing an erase pulse. As an example of erasing the effect of turning on the light-emission control thyristor S(1) / VCSEL(1), the vicinity of time n to time r in the timing chart shown in Fig. 4 is cut out and an erase pulse is added. For this reason, times aa and ab are added between times o and p.

[0107] The erase pulse should be placed after the end of the series of VCSEL light emission (time d in FIG. 4) and before the next VCSEL to be emitted (time p in FIG. 4). In FIG. 12, it is assumed that VCSEL (6) is to be emitted. At time n, the shift signal p2 changes from "L" (0V) to "H" (5V), turning on the shift thyristor T(6) and changing from the off state to the on state. At time o, the shift signal p1 changes from "H" (5V) to "L" (0V), turning off the shift thyristor T(5) and changing from the on state to the off state. At time aa, the erase signal pJ is shifted from "L" (0V) to "H" (5V) to turn on the driver Drv3. Then, in the period until time ab, the VCSEL is put into a state in which it is unable to emit light again. Time aa is the timing when only the shift thyristor T(6) that sets the VCSEL(6) to emit light is in the on state.

[0108] At time ab, the erase signal pJ transitions from "H" (5V) to "L" (0V) to turn off the driver Drv3. Then, at time b after time ab, the light emission signal pI transitions from "L" (0V) to "H" (5V) to cause the VCSEL (6) to emit light. The period during which the erase signal pJ is "H" (5V) from time aa to time ab is the pulse width of the erase pulse. Here, the VCSEL (6) is described as emitting light, but other VCSELs may be used.

[0109] More preferably, the erase pulse is provided after the time when only the shift thyristor T that sets the VCSEL to be emitted is turned on (time o in FIG. 12) and before the VCSEL to be emitted is emitted (time p in FIG. 12). This is because, when the on state is shifted in the shift section 12, the erase pulse resets (initializes) the effect of lowering the voltage of the n-gate Gn of the light-emission control thyristor S other than the set VCSEL and the fluctuation in the voltage of the n-gate Gn of the light-emission control thyristor S due to noise during shifting. Therefore, the erase pulse may be used not only to disable the re-emission of a previously emitted VCSEL, but also before the first emission of a VCSEL in order to disable emission of any VCSEL in the light-emitting device 10.

[0110] When the driver Drv is composed of an NMOS transistor, multiple resistors with different resistance values ​​may be connected in parallel between the source and drain of an NMOS transistor with a sufficiently large off-resistance, and one of the resistors may be used as the erase current limiting resistor RJ. The multiple resistors may be connected via a switch, and the erase pulse may be generated by switching the switch.

[0111] By making the pulse width of the erase pulse narrower than the pulse width of the light-emitting pulse and / or making the current value of the erase pulse smaller than the current value of the light-emitting pulse, light emission from the VCSEL due to the erase pulse is suppressed.

[0112] It is advisable to supply a pulse with a slow voltage change rate dV / dt to the driver voltage line 75 as the erase pulse. Even when the light-emitting control thyristor S is turned on and off, charge remains. The light-emitting voltage VLD is applied to the n-gate Gn by the current limiting resistor RL. Therefore, charge in the n-gate layer 87, which is the n-gate Gn, is likely to escape. On the other hand, charge is likely to remain in the p-gate layer 86, which is the p-gate Gn (see FIG. 3) (see FIG. 7(b)). The threshold voltage of the light-emitting control thyristor S changes depending on the amount of remaining charge. In this way, a pulse with a slow voltage change rate dV / dt may be supplied to the driver voltage line 75 to increase the threshold voltage of the light-emitting control thyristor S, making it difficult to turn on the light-emitting control thyristor S.

[0113] In the first to third embodiments, the VCSEL emits light during each period in which the light-emission signal pI is "H" (5V). However, this period may be set so that the light-emission control thyristor S is turned on but the amount of light emitted by the VCSEL is small. This period in which the amount of light emitted by the VCSEL is small is provided not for the purpose of making the VCSEL emit light, but to extend the period in which the VCSEL can emit light again. In other words, when the light-emission control thyristor S is turned on, the voltage of the cathode K increases and the period in which light can be emitted again is reset. Instead of the light-emission pulse, a period extension pulse is set to a period (pulse width) shorter than the period (pulse width) in which the VCSEL emits light, or the current value flowing through the VCSEL is reduced compared to when the VCSEL emits light, thereby turning on the light-emission control thyristor S but setting a period in which the amount of light emitted by the VCSEL is small. When this period ends, the period in which the VCSEL can emit light again begins again. Thus, the period in which the VCSEL can emit light again can be extended to any period.

[0114] In the first to third embodiments, the light emitting device 10 having a plurality of light emitting elements is shown, but these embodiments may be applied to a light emitting device composed of one light emitting element. When a current unintentionally flows through the light emitting element due to noise or the like, the light emitting element is prevented from erroneously emitting light. For example, if the light emission control thyristor S has enabled the VCSEL to emit light, the VCSEL may emit light, but if the light emission control thyristor S has disabled the VCSEL from emitting light, the VCSEL is prevented from erroneously emitting light.

[0115] In the first to third embodiments, light source devices 1, 2, and 3 that emit light multiple times are shown, but these embodiments may be applied to a light source device that emits light only once. As shown in FIG. 6, even after the first emission, the light emitting element (here, VCSEL) continues to be capable of emitting light. Also, depending on the configuration of the light emitting device, even one emission may have an effect for a long period of time of ms or more. Therefore, by changing the state to one that cannot emit light, the interval between the emission of multiple light emitting elements at different times is shortened, and the occurrence of erroneous emission by the light emitting elements is suppressed.

[0116] Although the light emitting device 10 described above has a common cathode, it may have a common anode. In this case, an n-ohmic electrode is provided on the n-gate layer (n-type semiconductor layer 87), but a p-ohmic electrode may be provided on the p-gate layer (p-type semiconductor layer 86). Furthermore, in the shift section 12 of the light emitting device 10, the shift thyristors T are connected by the coupling transistors Q, but may be connected by diodes or resistors. Furthermore, an example has been described in which the shift section 12 is the setting section, but instead of a shift section that performs a shift operation, the setting section may be configured to send a signal directly from the driver to the thyristor of the light-emitting element.

[0117] (Measuring device 100) The light source devices 1, 2, and 3 shown in the first to third embodiments can be applied to a measurement device that measures a three-dimensional shape (hereinafter, referred to as a 3D shape) of a measurement object. The measurement device is a device that measures a 3D shape based on a so-called ToF (Time of Flight) method using the time of flight of light. The measurement device includes a light source device and a three-dimensional sensor (hereinafter, referred to as a 3D sensor). In the ToF method, the time from the timing when light is emitted from the light source device to the timing when the light is reflected by the measurement object and received by the 3D sensor is measured. Then, the distance to the measurement object is calculated from the time acquired from the three-dimensional sensor, and the 3D shape of the measurement object is specified. In addition, measuring a three-dimensional shape may be referred to as three-dimensional measurement, 3D measurement, or 3D sensing. The three-dimensional sensor is an example of a light receiving unit.

[0118] Such a measuring device is applied to recognize a measurement target from a specified 3D shape. For example, it is mounted on a portable information processing device and used to recognize the face of a user who is trying to access the device. In other words, the 3D shape of the face of the user who has accessed the device is acquired, and it is determined whether the user is permitted to access the device. Only when the user is recognized as being permitted to access the device, is the device (portable information processing device) permitted to be used. This measuring device is also applicable to cases where the 3D shape of an object is continuously measured, such as in augmented reality (AR).

[0119] Such a measuring device can be applied to information processing devices other than portable information processing devices, such as personal computers (PCs).

[0120] FIG. 13 is a block diagram for explaining the configuration of the measurement device 100. The measurement device 100 includes light source devices 1, 2, and 3, each including a light emitting device 10 and a control unit 50, and a 3D sensor 5. The light source devices 1, 2, and 3 emit light toward the object to be measured. The 3D sensor 5 acquires light (reflected light) reflected by the object to be measured. The 3D sensor 5 outputs information (distance information) about the distance to the object to be measured based on the time from emission to reception of the reflected light, measured by the ToF method. The measurement device 100 may include a measurement control unit 200. The measurement control unit 200 is configured as a computer including a CPU, a ROM, a RAM, and the like, and identifies the three-dimensional shape of the object to be measured based on the distance information acquired from the 3D sensor 5.

[0121] The present invention may be understood as follows. In the light-emitting device, the shift section is configured with transfer elements to which the ON state is transferred in the order of the arrangement. In this way, the shift section is easier to configure than when the ON state is not transferred. In the light emitting device, when the thyristor in the shift section is turned on, the light emitting element is brought into a state in which it can emit light by the thyristor function. In this way, the control of the shift section and the control of the light emitting section are separated. The light emitting device is characterized in that the light emitting element is composed of a surface light emitting element and a thyristor connected in series, which makes it easy to improve the light emitting characteristics. [Explanation of symbols]

[0122] 1, 2, 3...light source device, 5...3D sensor, 10...light emitting device, 11...light emitting section, 12...shift section, 12a...shift unit, 50...control section, 71...power supply line, 72, 72-1, 72-2...shift signal line, 73...ground line, 74...voltage supply line, 75...driver voltage line, 79...rear electrode, 100...measurement device, 200...measurement control section, Buf1, Buf2...buffer, Drv, Drv1, Drv2, Drv3...driver, GND...ground potential, p1, p2...shift signal, pI...light emission signal, pJ...erase signal, S...light emission control thyristor, T...shift thyristor, VCSEL...vertical cavity surface emitting laser, Vc...saturation voltage, Vd...forward voltage (diffusion potential), Vdrv...driver voltage, VGK...power supply potential, VLD...light emission voltage, VS1, VS2...power supply

Claims

1. A light-emitting unit including a light-emitting element having a thyristor that enables light to be emitted when an electric charge is accumulated; a control unit that controls the light-emitting unit to emit light by supplying a light-emitting current to the light-emitting unit in response to a light-emitting signal that controls light emission and extinction of the light-emitting element while keeping the thyristor in a state where electric charge is accumulated therein, and then controls the light-emitting unit to supply an erasing pulse that erases the electric charge of the thyristor in response to an erasing signal different from the light-emitting signal, thereby disabling the light-emitting element from emitting light again; A light source device comprising:

2. The light-emitting unit includes a plurality of light-emitting elements each having the thyristor, The control unit controls a part of the plurality of light-emitting elements of the light-emitting unit to emit light, and supplies a light-emitting current to cause the part of the plurality of light-emitting elements to emit light, and then supplies the erase pulse to disable the part of the plurality of light-emitting elements of the light-emitting unit from emitting light again before causing another light-emitting element to emit light. The light source device according to claim 1 .

3. A light-emitting unit including a plurality of light-emitting elements each having a thyristor that enables light to be emitted when an electric charge is accumulated; a setting unit that sets thyristors of some of the light-emitting elements of the light-emitting unit to a state in which electric charges are accumulated; a control unit that, after the setting unit sets the thyristors of the part of the light-emitting elements to a state in which charges are accumulated, and before supplying a light-emitting current in accordance with a light-emitting signal that controls the light-emitting and non-light-emitting of the part of the light-emitting elements, supplies an erasure pulse that erases charges of the thyristors of the light-emitting elements in the light-emitting unit other than the part of the light-emitting elements by an erasure signal different from the light-emitting signal, thereby disabling the light-emitting elements other than the part of the light-emitting elements from emitting light; A light source device comprising:

4. The light emitting unit includes a plurality of light emitting elements each having the thyristor, The light source device according to claim 1, characterized in that the control unit causes a portion of the plurality of light-emitting elements of the light-emitting unit to emit light, and after turning on / off the light-emitting current for the portion of the light-emitting elements to emit light a plurality of times, it supplies the erasure pulse that disables the portion of the light-emitting elements from emitting light again.

5. 4. The light source device according to claim 1, wherein the control unit supplies the light-emitting current for causing the light-emitting element to emit light and the erase pulse from a ground side of a power supply.

6. The thyristor and the light-emitting element are stacked, The light source device according to claim 5 , wherein the thyristor is stacked on a side farther from the ground side than the light emitting element.

7. 4. The light source device according to claim 1, wherein the erase pulse has a pulse width narrower than a pulse width for emitting light.

8. 4. The light source device according to claim 1, wherein a current value of the erase pulse is lower than a current value when light is emitted.

9. The control unit is a first driver that turns on / off a light-emitting current on a ground side of a power source that supplies a light-emitting current to the light-emitting element, and a second driver that supplies the erase pulse; The light source device according to claim 1 or 3, characterized in that the second driver has an on-resistance smaller than the off-resistance of the first driver, and is set to a value that disables re-emission when the first driver is off and turns on.

10. A light source device according to any one of claims 1 to 9; a light receiving unit that receives light emitted from the light emitting unit of the light source device and reflected by an object to be measured; A measuring device comprising:

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