Projector and measuring device

Abstract

The present invention reduces a space for disposing a capacitor. This projector comprises: a first light-emitting element and a second light-emitting element which are adjacent to each other in a first direction; a capacitor which is electrically connected to both the first light-emitting element and the second light-emitting element; a first switch element which is connected in series to the first light-emitting element, and which supplies, to the first light-emitting element, charged electric charges accumulated in the capacitor when set to a closed state from an open state, to thereby cause the first light-emitting element to emit light; a second switch element which is connected in series to the second light-emitting element and which supplies, to the second light-emitting element, the charged electric charges accumulated in the capacitor when set to a closed state from an open state, to thereby cause the second light-emitting element to emit light; and a control circuit which sets the first switch element and the second switch element to a closed state from an open state at different timings.

Description

Floodlights, measuring devices

[0001] The technology disclosed in this specification relates to a projector and a measurement device.

[0002] With the advancement of autonomous driving (AD) systems and advanced driver assistance systems (ADAS), research and development of light detection and ranging (LiDAR) is underway as one of the measurement devices used to grasp the surrounding environment and estimate the vehicle's position while driving. LiDAR includes a light projector that projects laser light onto a measurement target and a light receiver that receives the light reflected from the measurement target. LiDAR measures the distance to the measurement target based on the difference between the timing at which the light projector emits the laser light and the timing at which the light receiver receives the reflected light. The light projector includes a plurality of light-emitting elements, a plurality of switch elements, a plurality of capacitors provided corresponding to each of the plurality of light-emitting elements, and a voltage output circuit that outputs an output voltage to be supplied to each capacitor (see, for example, Patent Documents 1 and 2). The capacitor is charged by the output voltage output from the voltage output circuit, and when the switch element changes from an open state to a closed state, the charge stored in the capacitor is discharged to the light-emitting element, causing the light-emitting element to emit light.

[0003] JP 2021-19194 A JP 2022-109724 A

[0004] In conventional floodlights, one capacitor is provided for each light-emitting element, which makes it difficult to secure space for arranging the capacitors.

[0005] This specification discloses a technique that can solve the above-mentioned problems.

[0006] The technology disclosed in this specification can be realized, for example, in the following forms.

[0007] (1) A floodlight disclosed in this specification includes a first light-emitting element and a second light-emitting element adjacent to each other in a first direction; a capacitor electrically connected to both the first light-emitting element and the second light-emitting element; a first switch element connected in series to the first light-emitting element, the first switch element switching from an open state to a closed state to supply a charge stored in the capacitor to the first light-emitting element, causing the first light-emitting element to emit light; a second switch element connected in series to the second light-emitting element, the second switch element switching from an open state to a closed state to supply a charge stored in the capacitor to the second light-emitting element, causing the second light-emitting element to emit light; and a control circuit that switches the first switch element and the second switch element from an open state to a closed state at mutually different times.

[0008] According to this configuration, the first light-emitting element and the second light-emitting element can emit light using a common capacitor. Furthermore, according to this configuration, the number of capacitors is smaller than in a configuration in which the first light-emitting element and the second light-emitting element are connected to different capacitors, and therefore the space required for arranging the capacitors can be reduced.

[0009] (2) In the above-described floodlight, a length of a first wiring pattern between the output terminal of the capacitor and the input terminal of the first light-emitting element may be substantially the same as a length of a second wiring pattern between the output terminal of the capacitor and the input terminal of the second light-emitting element. With this configuration, variations in light emission intensity due to parasitic inductance included in the wiring patterns can be suppressed compared to when the first wiring pattern and the second wiring pattern have different lengths.

[0010] (3) The above-described floodlight may include a plurality of the first light-emitting elements, a plurality of the second light-emitting elements, and a plurality of the capacitors, the plurality of first light-emitting elements and the plurality of second light-emitting elements being arranged in the first direction such that the first light-emitting elements and the second light-emitting elements alternate one by one, the plurality of capacitors being arranged in the first direction and parallel to the arrangement of the plurality of first light-emitting elements and the plurality of second light-emitting elements, and each of the capacitors may be electrically connected to both the first light-emitting element and the second light-emitting element of the closest pair among a plurality of pairs of the first light-emitting element and the second light-emitting element adjacent to each other. With this configuration, the plurality of light-emitting elements and the plurality of capacitors are arranged in parallel, and the first light-emitting element and the second light-emitting element can be caused to emit light using a common capacitor.

[0011] (4) In the above-described floodlight, a center position of each capacitor may be located between a first input terminal of the first light-emitting element and a second input terminal of the second light-emitting element corresponding to the capacitor in the first direction. With this configuration, a plurality of light-emitting elements can be arranged at a relatively narrow pitch with respect to a plurality of capacitors arranged at a predetermined center distance, and a common capacitor can be used to cause the first light-emitting element and the second light-emitting element to emit light.

[0012] (5) The floodlight may further include a substrate formed of a dielectric material, a ground layer formed on one surface of the substrate, a one-side wiring pattern formed on the other surface of the substrate and electrically connecting one terminal of the capacitor to the ground layer, and a other-side wiring pattern formed on the other surface of the substrate and electrically connecting the other terminal of the capacitor to each of the light-emitting elements, wherein the thickness of at least a portion of the substrate on which each of the wiring patterns is formed is 100 μm or less. According to this configuration, by making the thickness of the dielectric substrate 100 μm or less, it is possible to reduce the parasitic inductance contained in each of the wiring patterns.

[0013] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a projector, a measuring device, a power supply circuit, a light emission driving device, etc.

[0014] FIG. 1 is a block diagram showing a schematic configuration of a measurement device according to a first embodiment; FIG. 2 is a circuit diagram showing a schematic configuration of a light source unit; FIG. 3 is an explanatory diagram showing the layout of a light source unit according to the first embodiment; FIG. 4 is an explanatory diagram showing the layout of a light source unit according to a comparative example; and FIG. 5 is an explanatory diagram showing the layout of a light source unit according to a second embodiment.

[0015] A. First Embodiment: A-1. Configuration of Measuring Device 10: The first embodiment will be described with reference to FIGS. 1 to 4. The measuring device 10 of this embodiment is a LiDAR. The measuring device 10 is mounted, for example, on a vehicle equipped with an AD (automated driving system) or an ADAS (advanced driver assistance system). The measuring device 10 assists in detecting objects such as people and other vehicles while the vehicle is traveling, and provides various information to other devices and users that is useful for ensuring the safety of the vehicle driver and those around the vehicle and for reducing damage to surrounding objects while the vehicle is being driven.

[0016] As shown in FIG. 1, the measuring device 10 includes a light projector 100, a light receiver 400, an information processing device 500, and a communication interface 600.

[0017] 1 and 2, the projector 100 includes a light source unit 110 (light emission drive device), a control circuit board 210, and a light projection optical system 180. The control circuit board 210 is an example of a control circuit.

[0018] (Light Source Unit): As shown in Fig. 3, the light source unit 110 includes a plurality of light emitting elements 102, a plurality of capacitors 106, and a plurality of switch elements 104. For ease of explanation, Fig. 2 shows only one light emitting element 102, one capacitor 106, and one switch element 104.

[0019] The light emitting element 102 is, for example, an infrared laser light emitting element that emits infrared light. The laser light emitting element is, for example, a laser diode, a light emitting diode, or a surface light emitting element (for example, a VCSEL (Vertical Cavity Surface Emitting Laser)). The light source unit 110 may include a light emitting source having one or more light emitting element arrays (for example, light emitting elements 102 arranged in a line (one-dimensional) or a surface (two-dimensional)).

[0020] The switch element 104 is connected in series to the light-emitting element 102. The switch element 104 is, for example, a GaN FET (high electron mobility transistor). Note that the switch element 104 may be, for example, a field-effect transistor other than a GaN FET, a bipolar transistor, or an insulated gate bipolar transistor. Furthermore, although the switch element 104 is disposed on the low potential side of the light-emitting element 102 (the cathode of the light-emitting element 102), it may also be disposed on the high potential side of the light-emitting element 102 (the anode of the light-emitting element 102).

[0021] The power supply circuit 101 includes a capacitor 106 and a voltage output circuit 108 .

[0022] 2, the capacitor 106 is connected in parallel to the light-emitting element 102 and the switch element 104. Specifically, the low-potential terminal of the capacitor 106 is electrically connected to ground, and the high-potential terminal of the capacitor 106 is electrically connected to the anode of the light-emitting element 102. The capacitor 106 is, for example, a ceramic capacitor. However, the capacitor 106 may be another type of capacitor, such as an electrolytic capacitor or a film capacitor.

[0023] The voltage output circuit 108 outputs an output voltage Vd to be supplied to the capacitor 106. The voltage output circuit 108 generates the output voltage Vd based on an externally supplied supply voltage and applies it to the capacitor 106. The voltage output circuit 108 includes, for example, a DC-DC converter and a constant voltage DC power supply circuit.

[0024] (Control Circuit Board): The control circuit board 210 is a circuit board on which electronic components and the like are mounted for controlling the light emission of the light source unit 110. The control circuit board 210 controls the power supply circuit 101 and also controls the switching of each of the multiple switch elements 104. In other words, the control circuit board 210 switches each switch element 104 between an open state and a closed state.

[0025] (Light Projection Optical System): The light projection optical system 180 is disposed on the optical path of the output laser light Lout output from the light source unit 110. The light projection optical system 180 adjusts the light distribution of the output laser light Lout. The light projection optical system 180 may be, for example, a lens such as a collimator lens.

[0026] A-1-2. Photoreceiver, etc.: As shown in FIG.

[0027] The light receiving optical system 410 is an optical system for causing the light receiving unit 420 to receive reflected laser light Lre, which is light that is output laser light Lout reflected by the measurement target W and returned. The light receiving optical system 410 may be, for example, any of various lenses such as a condenser lens, any of various filters such as a wavelength filter, or a reflective mirror.

[0028] The light receiving unit 420 includes a light receiving element, such as a photodiode, that receives the reflected laser light Lre incident from the light receiving optical system 410, converts the reflected laser light Lre into a light receiving signal corresponding to the intensity and timing of receiving the reflected laser light Lre, and outputs the signal.

[0029] The TOF measurement device 430 includes, for example, a time measurement integrated circuit (IC) equipped with a time-to-digital converter (TDC) circuit. The TOF measurement device 430 is communicatively connected to the light-projection control device 211 and the light-receiving unit 420. The TOF measurement device 430 receives a timing signal indicating the emission timing output from the light-projection control device 211 and a light-receiving signal output from the light-receiving unit 420, and, based on these, calculates the difference between the timing at which the output laser light Lout is emitted and the timing at which the reflected laser light Lre is received, i.e., the time of flight (TOF) of the laser light. The TOF measurement device 430 outputs a signal corresponding to the calculated TOF and the light-receiving signal received from the light-receiving unit 420.

[0030] The information processing device 500 has a processor. The processor may be, for example, a central processing unit (CPU), a micro processing unit (MPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), or the like. The information processing device 500 is communicably connected to the TOF measurement device 430. The information processing device 500 receives a signal corresponding to the TOF output by the TOF measurement device 430 and a light receiving signal, and generates various information such as the distance to the measurement target W based on these signals. The information includes, for example, a histogram used in time-correlated single photon counting, the distance to each point on the measurement target W, point cloud information, and the like. The information generated by the information processing device 500 is transmitted via a communication interface 600 to an external device 700 that uses the information.

[0031] The external device 700 may be, for example, a device that creates an environmental map using a point cloud, or may be a device that performs self-location estimation (SLAM: Simultaneous Localization and Mapping) using a scan matching algorithm such as NDT (Normal Distributions Transform) or ICP (Iterative Closest Point).

[0032] A-2. Arrangement of the Light Source Unit: Next, we will explain the arrangement of the light emitting elements 102, capacitors 106, and switch elements 104 in the light source unit 110. As shown in Fig. 3, the light source unit 110 has a light emitting element array 103 in which a plurality of light emitting elements 102 (10 in the example of Fig. 3) are arranged in a row.

[0033] The plurality of light-emitting elements 102 includes a first group of light-emitting elements 102 (102A, 102C, 102E, 102G, and 102I) and a second group of light-emitting elements 102 (102B, 102D, 102F, 102H, and 102J). The number of light-emitting elements 102 in the first group and the number of light-emitting elements 102 in the second group are the same (five in the example of FIG. 3). The first light-emitting elements 102 in the first group and the light-emitting elements 102 in the second group are arranged alternately one by one along a predetermined direction (hereinafter referred to as the "arrangement direction"). The arrangement direction is an example of a first direction. The plurality of light-emitting elements 102 are arranged at intervals substantially equal to the minimum allowable width in the arrangement direction, thereby being mounted at a high density in the light-emitting element array 103. The minimum allowable width is the smallest allowable value for the spacing between components in the light-emitting element array 103.

[0034] The plurality of capacitors 106 are aligned along the alignment direction and are arranged parallel to the arrangement of the plurality of light-emitting elements 102 (102A to 102J). The number of capacitors 106 is the same as the number of light-emitting elements 102 in the first group (the number of light-emitting elements 102 in the second group) (five in the example of FIG. 3). Each capacitor 106 is electrically connected to both the light-emitting elements 102 in the first group and the light-emitting elements 102 in the second group that are adjacent to each other in the alignment direction. The light-emitting elements 102 in the first group that are electrically connected to each capacitor 106 are the light-emitting elements 102 that are located closest to the capacitor 106 among the plurality of light-emitting elements 102 (102A, 102C, 102E, 102G, 102I) that belong to the first group. The light-emitting elements 102 in the second group that are electrically connected to each capacitor 106 are the light-emitting elements 102 that are located closest to the capacitor 106 among the plurality of light-emitting elements 102 (102B, 102D, 102F, 102H, 102J) that belong to the second group.

[0035] For example, the capacitor 106A is electrically connected to both the light-emitting element 102A of the first group and the light-emitting element 102B of the second group. Specifically, the output terminal (high-potential terminal) of the capacitor 106A is electrically connected to the first input terminal PA of the first light-emitting element 102A via the first wiring pattern LA. Furthermore, the output terminal of the capacitor 106A is electrically connected to the second input terminal PB of the second light-emitting element 102B via the second wiring pattern LB.

[0036] In the arrangement direction, the center position M of each capacitor 106 is located between the first input terminal of the light-emitting element 102 of the first group and the second input terminal of the light-emitting element 102 of the second group corresponding to each capacitor 106. For example, in Fig. 3, the center position M of the capacitor 106E is located between the first input terminal PI of the light-emitting element 102I of the first group and the second input terminal PJ of the light-emitting element 102J of the second group.

[0037] The length of the first wiring pattern between the output terminal of each capacitor 106 and the first input terminal of the light-emitting element 102 of the first group is substantially the same as the length of the second wiring pattern between the output terminal of each capacitor and the second input terminal of the light-emitting element 102 of the second group. For example, in FIG. 3 , the length of the first wiring pattern LA between the output terminal of the capacitor 106A and the first input terminal PA of the light-emitting element 102A of the first group is substantially the same as the length of the second wiring pattern LB between the output terminal of the capacitor 106A and the second input terminal PB of the light-emitting element 102B of the second group. Furthermore, the length of the first wiring pattern LI between the output terminal of the capacitor 106E and the first input terminal PI of the light-emitting element 102I of the first group is substantially the same as the length of the second wiring pattern LJ between the output terminal of the capacitor 106E and the second input terminal PJ of the light-emitting element 102J of the second group. In this embodiment, all of the first wiring patterns and all of the second wiring patterns are the same length.

[0038] The output terminals of the light-emitting elements 102 (102A, 102C, 102E, 102G, and 102I) in the first group are commonly connected to the first switch element 104A via a first common line R1. Therefore, when the first switch element 104A is turned on, all of the light-emitting elements 102 in the first group are conductive and emit light. The output terminals of the light-emitting elements 102 (102B, 102D, 102F, 102H, and 102J) in the second group are commonly connected to the second switch element 104B via a second common line R2. Therefore, when the second switch element 104B is turned on, all of the light-emitting elements 102 in the second group are conductive and emit light.

[0039] 4 shows the arrangement of the light source unit 110a and the light source unit 110b of the comparative example. The light emitting element array 103a of the light source unit 110a is equipped with the light emitting elements 102 of the first group (102A, 102C, 102E, 102G, 102I), but not with the light emitting elements 102 of the second group. Therefore, the spacing between the light emitting elements 102 of the first group is wider than in the light emitting element array 103 of FIG. 3. The plurality of capacitors 106 (106A to 106E) are arranged in a line along the light emitting elements 102 of the first group.

[0040] The light-emitting element array 103b of the light source unit 110b has a higher density of light-emitting elements by mounting the second group of light-emitting elements 102 on the light-emitting element array 103a. Each of the second group of light-emitting elements 102 is electrically connected to a second group of capacitors (106F-106J). In this highly dense light-emitting element array 103b, the spacing between the output terminals of the light-emitting elements is narrow. Therefore, the capacitors for the first group (106A-106E) and the capacitors for the second group (106F-106J) cannot be arranged in a line. Specifically, the capacitors for the first group (106A-106E) are arranged close to the first group of light-emitting elements (102A, 102C, 102E, 102G, 102I), thereby shortening the first wiring pattern. On the other hand, the capacitors for the second group (106F to 106J) cannot be placed between the capacitors for the first group, and must be placed away from the light-emitting elements of the second group (102B, 102D, 102F, 102H, 102J), resulting in the second wiring pattern being longer than the first wiring pattern.

[0041] As shown in FIG. 2, the wiring pattern between the capacitor 106 and the light-emitting elements 102 includes a parasitic inductance Lp. The parasitic inductance Lp inhibits abrupt changes in the current Id flowing through the wiring pattern. The longer the wiring pattern, the greater the effect of Lp. In the light-emitting element array 103b, the length of the second wiring patterns LFb-LJb is longer than the length of the first wiring patterns LA-LI (see FIG. 4). Therefore, when the switch element 104 is turned on, the peak value of the pulse waveform of the current flowing through the second group of light-emitting elements 102 is smaller than the peak value of the pulse waveform of the current flowing through the first group of light-emitting elements 102. As a result, the emission intensity of the second group of light-emitting elements 102 is smaller than the emission intensity of the first group of light-emitting elements 102, resulting in variation in the emission intensities of the multiple light-emitting elements 102. Variation in the emission intensities of the multiple light-emitting elements 102 results in variation in the maximum measurement distance (maximum measurable distance) of the measurement device 10.

[0042] In the light-emitting element array 103 of this embodiment, the light-emitting elements 102 of the first group and the light-emitting elements 102 of the second group are electrically connected to a single common capacitor 106, and the single capacitor is used to time-share the light emission of the light-emitting elements 102 of the first group and the light-emitting elements 102 of the second group. In this way, because the number of capacitors 106 is small compared to the number of light-emitting elements 102, the lengths of all wiring patterns between the capacitors 106 and the light-emitting elements 102 can be made uniform. As a result, the light-emitting intensity of the light-emitting elements 102 of the second group and the light-emitting elements 102 of the first group are at the same level, and variations in the light-emitting intensity of the plurality of light-emitting elements 102 can be suppressed.

[0043] A-3. Advantages of this embodiment: As described above, in this embodiment, at least two adjacent light-emitting elements 102 are electrically connected to a common capacitor 106, and the stored charge in the capacitor 106 is supplied to each of the light-emitting elements 102 at different times to cause them to emit light. As a result, according to this embodiment, the common capacitor 106 can be used to cause the light-emitting elements 102 of the first group and the light-emitting elements 102 of the second group to emit light. Furthermore, according to this embodiment, the number of capacitors 106 is smaller than in a configuration in which the light-emitting elements 102 of the first group and the light-emitting elements 102 of the second group are connected to different capacitors 106 (see, for example, FIG. 4), and therefore the space required for arranging the capacitors 106 can be reduced.

[0044] In this embodiment, the first wiring pattern and the second wiring pattern have approximately the same length. Therefore, this embodiment can suppress variations in light emission intensity caused by the parasitic inductance Lp included in the wiring patterns compared to when the first wiring pattern and the second wiring pattern have different lengths (see, for example, FIG. 4 ). Furthermore, this embodiment allows the plurality of light-emitting elements 102 to be arranged at a relatively narrow pitch relative to the plurality of capacitors 106 arranged at a predetermined center-to-center distance, and allows the first group of light-emitting elements 102 and the second group of light-emitting elements 102 to emit light using the common capacitor 106.

[0045] B. Second Embodiment: Fig. 5 is an explanatory diagram showing the arrangement of the light source unit 110c in a second embodiment. The second embodiment differs from the first embodiment in the configuration of the light source unit. Among the configurations of the second embodiment, the same configurations as those of the first embodiment described above are assigned the same reference numerals, and the description thereof will be omitted.

[0046] As shown in FIG. 5, in the light source unit 110c of the second embodiment, a plurality of capacitors 106 and a plurality of wiring patterns LA to LJ are arranged on the surface of a substrate 120 made of a dielectric material. Each of the wiring patterns LA to LJ is connected to a capacitor. The lengths of the plurality of wiring patterns LA to LJ on the surface of the substrate 120 are approximately the same. A ground layer (ground plane) 122 is formed on the back surface of the substrate 120. Each of the wiring patterns LA to LJ is electrically connected to the ground layer 122. Note that each of the wiring patterns LA to LJ is an example of a one-side wiring pattern and an other-side wiring pattern.

[0047] Each of the wiring patterns LA to LJ is configured as a microstrip line. The substrate 120 is preferably a build-up substrate. The thickness of the substrate 120 is 100 μm or less. In this embodiment, the thickness of any position on the substrate 120 is 100 μm or less. The thickness of the substrate 120 may be 90 μm or less, 80 μm or less, or 70 μm or less. The thickness of the portion of the substrate 120 where each of the wiring patterns LA to LJ is arranged is 100 μm or less, and the thickness of the portion where each of the wiring patterns LA to LJ is not arranged may exceed 100 μm. Each of the wiring patterns LA to LJ may be configured as a strip line.

[0048] In conventional configurations, the thickness of the substrate used in the light source unit is 170 μm or more. In contrast, in this embodiment, the thickness of the substrate 120 used in the light source unit 110c is 100 μm or less. Therefore, according to this embodiment, the parasitic inductance included in each of the wiring patterns LA to LJ can be reduced compared to conventional configurations. In particular, in this embodiment, the lengths of the multiple wiring patterns LA to LJ on the surface of the substrate 120 are approximately the same. Therefore, variations in the parasitic inductance included among the multiple wiring patterns LA to LJ can also be suppressed.

[0049] C. Modifications: The technology disclosed in this specification is not limited to the above-described embodiment, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0050] In each of the above embodiments, the light emitting element 102 is an infrared laser light emitting element that emits infrared light, but is not limited to this and may be a light emitting element that emits visible light, ultraviolet light, or the like.

[0051] In the above embodiment, two light emitting elements are electrically connected to one capacitor, but this is not limiting, and three or more light emitting elements may be electrically connected to one capacitor.

[0052] In the above embodiment, the lengths of the first wiring pattern and the second wiring pattern may be different from each other. The center position M of each capacitor 106 does not have to be located between the first input terminal of the light-emitting element 102 of the first group corresponding to each capacitor 106 and the second input terminal of the light-emitting element 102 of the second group.

[0053] The floodlight disclosed in this specification may have the following configuration: "a floodlight comprising: a light-emitting element; a capacitor electrically connected to the light-emitting element; a switch element connected in series to the light-emitting element, the switch element switching from an open state to a closed state to supply a charge stored in the capacitor to the light-emitting element, causing it to emit light; a substrate made of a dielectric; a ground layer formed on one surface of the substrate; a one-side wiring pattern formed on the other surface of the substrate, the one-side wiring pattern electrically connecting one terminal of the capacitor to the ground layer; and a other-side wiring pattern formed on the other surface of the substrate, the one-side wiring pattern electrically connecting the other terminal of the capacitor to each of the light-emitting elements, wherein at least a portion of the substrate on which each of the wiring patterns is formed has a thickness of 100 μm or less." This configuration can reduce the parasitic inductance contained in each of the wiring patterns.

[0054] This international application claims priority based on Japanese Patent Application No. 2024-106516, which was filed on July 2, 2024, and Japanese Patent Application No. 2025-035144, which was filed on March 6, 2025. The entire contents of Japanese Patent Application Nos. 2024-106516 and 2025-035144 are incorporated by reference into this international application.

[0055] The above descriptions of specific embodiments of the present invention have been presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the precise forms described. Numerous modifications and variations will be apparent to those skilled in the art in light of the above description.

[0056] 10: Measuring device 100: Light projector 101: Power supply circuit 102: Light-emitting element 103, 103a, 103b: Light-emitting element array 104: Switch element 104A: First switch element 104B: Second switch element 106: Capacitor 108: Voltage output circuit 110, 110a, 110b, 110c: Light source unit 120: Substrate 122: Ground layer 180: Light-projecting optical system 210: Control circuit board 211: Light-projection control device 400: Light receiver 410: Light-receiving optical system 420: Light-receiving unit 430: TOF measuring device 500: Information processing device 600: Communication interface 700: External device

Claims

1. A floodlight comprising: a first light-emitting element and a second light-emitting element adjacent to each other in a first direction; a capacitor electrically connected to both the first light-emitting element and the second light-emitting element; a first switch element connected in series to the first light-emitting element, the first switch element switching from an open state to a closed state to supply the charge stored in the capacitor to the first light-emitting element, causing it to emit light; a second switch element connected in series to the second light-emitting element, the second switch element switching from an open state to a closed state to supply the charge stored in the capacitor to the second light-emitting element, causing it to emit light; and a control circuit that switches the first switch element and the second switch element from an open state to a closed state at mutually different times.

2. A floodlight according to claim 1, wherein the length of the first wiring pattern between the output terminal of the capacitor and the input terminal of the first light-emitting element is approximately the same as the length of the second wiring pattern between the output terminal of the capacitor and the input terminal of the second light-emitting element.

3. A floodlight as claimed in claim 1 or claim 2, comprising a plurality of the first light-emitting elements, a plurality of the second light-emitting elements, and a plurality of the capacitors, wherein the plurality of first light-emitting elements and the plurality of second light-emitting elements are arranged in the first direction so that the first light-emitting elements and the second light-emitting elements are arranged alternately one by one, the plurality of capacitors are arranged in the first direction and are arranged parallel to the arrangement of the plurality of first light-emitting elements and the plurality of second light-emitting elements, and each of the capacitors is electrically connected to both the first light-emitting element and the second light-emitting element of the closest pair out of a plurality of pairs of the first light-emitting element and the second light-emitting element that are adjacent to each other.

4. A light projector according to claim 3, wherein, in the first direction, the center position of each of the capacitors is located between the first input terminal of the first light-emitting element corresponding to each of the capacitors and the second input terminal of the second light-emitting element.

5. A floodlight as claimed in claim 1 or claim 2, further comprising: a substrate formed of a dielectric; a ground layer formed on one surface of the substrate; a one-side wiring pattern formed on the other surface of the substrate, electrically connecting one terminal of the capacitor to the ground layer; and a other-side wiring pattern formed on the other surface of the substrate, electrically connecting the other terminal of the capacitor to each of the light-emitting elements, wherein the thickness of at least the portion of the substrate on which each of the wiring patterns is formed is 100 μm or less.

6. A measuring device comprising the light projector according to claim 1 or 2.

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