Light-emitting device, optical device, and measuring device

Abstract

The present invention provides a light-emitting device, an optical device, and a measuring device. The light-emitting device includes: a first substrate; a laser unit provided on the first substrate; a capacitor element provided on the first substrate to supply a driving current to the laser unit; a wiring substrate including a second substrate having a lower thermal conductivity than the first substrate and mounting the first substrate; and a driving unit mounted on the wiring substrate to drive the laser unit.

Description

Technical Field

[0001] The present disclosure relates to a light-emitting device, an optical device, and a measuring device. Background Art

[0002] Japanese Patent Laid-Open No. 2008-252129 discloses a light-emitting device including: a ceramic substrate having translucency; a light-emitting element mounted on a surface of the ceramic substrate; a wiring pattern for supplying power to the light-emitting element; and a metalization layer containing a reflective metal, the metalization layer being formed inside the ceramic substrate so as to reflect light emitted from the light-emitting element. Summary of the Invention

[0003] In the case of measuring the three-dimensional shape of a measurement object based on a so-called Time of Flight (ToF) method using the flight time of light, it is required to reduce the inductance of a circuit that supplies a drive current to a laser unit and shorten the rise time of light emission from the laser unit. Further, it is required to improve the heat dissipation of the laser unit that generates a large amount of heat.

[0004] The present disclosure provides a light-emitting device or the like having the following structure, that is, it is easier to balance the reduction of the inductance of a drive circuit and the heat dissipation of a laser unit as compared with the case where a capacitor element that supplies a drive current to the laser unit is provided outside a first substrate.

[0005] According to a first aspect of the present disclosure, there is provided a light-emitting device including: a first base material; a laser unit provided on the first base material; a capacitor element provided on the first base material for supplying a drive current to the laser unit; a wiring substrate including a second base material having a lower thermal conductivity than the first base material and mounting the first base material; and a drive unit mounted on the wiring substrate for driving the laser unit.

[0006] According to a second aspect of the present disclosure, the planar shape of the first base material has a short side direction and a long side direction, and the drive unit is mounted in such a manner that at least a part thereof overlaps with an extension line in the short side direction and within a width range in the long side direction.

[0007] According to a third aspect of the present disclosure, the drive unit is mounted in such a manner that it is entirely included in an extension line in the short side direction and within a width range in the long side direction.

[0008] According to a fourth aspect of the present disclosure, the laser unit and the capacitor element are arranged in the long side direction.

[0009] According to a fifth aspect of the present disclosure, the laser unit is provided in the first base material so as to be offset toward the non-drive unit side.

[0010] According to the sixth aspect of the present disclosure, the capacitive element is provided in the first base material, deviated from the driving unit side.

[0011] According to the seventh aspect of the present disclosure, the laser unit includes a surface-emitting laser element array.

[0012] According to the eighth aspect of the present disclosure, the first base material includes ceramics.

[0013] According to the ninth aspect of the present disclosure, the first base material is a semiconductor substrate, and the driving unit for driving the laser unit is formed in the semiconductor substrate.

[0014] According to the tenth aspect of the present disclosure, the light-emitting device has an optical member that changes at least one of the direction and the divergence angle of the light emitted from the laser unit.

[0015] According to the eleventh aspect of the present disclosure, there is provided an optical device including: the light-emitting device; and a light-receiving unit that receives light emitted from the laser unit included in the light-emitting device and reflected by an object to be measured, and the light-receiving unit outputs a signal corresponding to the time from when the light is emitted from the laser unit until it is received by the light-receiving unit.

[0016] According to the twelfth aspect of the present disclosure, there is provided a measuring device including: the optical device; and a three-dimensional shape determination unit that determines the three-dimensional shape of the object to be measured based on the light emitted from the laser unit included in the optical device, reflected by the object to be measured, and received by the light-receiving unit included in the optical device, and the measuring device measures the three-dimensional shape of the object to be measured.

[0017] According to the thirteenth aspect of the present disclosure, there is provided a light-emitting device including: an insulating base material having a thermal conductivity of 10 W / m·K or more; a laser unit provided on the base material; a capacitive element provided on the base material for supplying a driving current to the laser unit; and a wiring connecting the laser unit and the driving unit, the driving unit driving the laser unit and provided outside the base material.

[0018] (Effect)

[0019] According to the first aspect or the thirteenth aspect, the following structure can be realized, that is, compared with the case where the capacitive element for supplying the driving current to the laser unit is provided outside the first substrate, it is easier to balance the reduction of the inductance of the driving circuit and the heat dissipation of the laser unit.

[0020] According to the second aspect, compared with the case where the first base material does not have a long side direction and a short side direction, it is easier to bring the laser unit and the driving unit closer.

[0021] According to the third solution, compared with the structure in which the driving unit is not mounted on the extension line in the short side direction and the width range in the long side direction, it is easier to bring the laser unit closer to the driving unit.

[0022] According to the fourth solution, the surface of the first substrate having the long side direction and the short side direction can be effectively utilized.

[0023] According to the fifth solution, compared with the structure in which the laser unit does not deviate toward the driving unit side, the circuit inductance is reduced.

[0024] According to the sixth solution, compared with the structure in which the capacitor element does not deviate toward the driving unit side, the circuit inductance is reduced.

[0025] According to the seventh solution, compared with the case of using an end-face-emitting laser, it is easier to arrange the laser elements in a two-dimensional shape.

[0026] According to the eighth solution, compared with the case of using a substrate having a lower thermal conductivity than the substrate containing a ceramic material, it is easier for the heat of the light-emitting element to be dissipated from the back side of the substrate to the outside.

[0027] According to the ninth solution, compared with the structure in which the driving unit is provided independently of the first substrate, the space for arranging the light-emitting device is reduced.

[0028] According to the tenth solution, compared with the case of not having an optical member, it is possible to change the direction and divergence angle of the light emitted from the light source and irradiate.

[0029] According to the eleventh solution, an optical device capable of acquiring a signal corresponding to a three-dimensional shape can be provided.

[0030] According to the twelfth solution, a measuring device capable of measuring a three-dimensional shape can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a block diagram illustrating an example of the structure of a measuring device for measuring a three-dimensional shape.

[0032] Figure 2 is a plan view of a light source.

[0033] Figure 3 is a diagram illustrating a cross-sectional structure of one vertical cavity surface emitting laser (VCSEL) in the light source.

[0034] Figure 4 of (a) and Figure 4 of (b) is a diagram illustrating an example of a light diffusion member. Figure 4 of (a) is a plan view, Figure 4The (b) of Figure 4 is a sectional view taken along line IVB-IVB of (a) of

[0035] Figure 5 is a diagram showing an example of an equivalent circuit when driving a light source by low-side driving.

[0036] Figure 6 The (a) of Figure 6 and the (b) of Figure 6 The (a) of Figure 6 is a plan view, Figure 6 and the (b) of

[0037] Figure 7 The (a) to Figure 7 the (c) of Figure 7 is a diagram showing the wiring provided on the wiring substrate and the wiring provided on the heat dissipation substrate. Figure 7 The (a) of Figure 7 is the wiring provided on the wiring substrate,

[0038] Figure 8 is a diagram further illustrating the light-emitting device to which this embodiment is applied.

[0039] Figure 9 The (a) of Figure 9 and the (b) of Figure 9 is a plan view, Figure 9 and the (b) of Figure 9 is a sectional view taken along line IXB-IXB of (a) of

[0040] Figure 10 The (a) to Figure 10 the (c) of Figure 10 is a diagram showing the wiring provided on the wiring substrate and the wiring provided on the heat dissipation substrate in the light-emitting device to which this embodiment is not applied. Figure 10 The (a) of Figure 10 is the wiring provided on the wiring substrate,

[0041] Figure 11 is a diagram further illustrating the light-emitting device to which this embodiment is not applied. Detailed Embodiments

[0042] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0043] In a measuring device for measuring the three-dimensional shape of a measurement object, there is a device that measures the three-dimensional shape based on the so-called Time of Flight (ToF) method using light. In the ToF method, the time from the timing when light is emitted from the light source of the measuring device until the irradiated light is reflected by the measurement object and received by the three-dimensional sensor (hereinafter referred to as the 3D sensor) of the measuring device is measured to determine the three-dimensional shape of the measurement object. In addition, the object for measuring the three-dimensional shape is called the measurement object. Moreover, measuring the three-dimensional shape is sometimes called three-dimensional measurement, 3D measurement, or 3D sensing.

[0044] Such a measuring device is mounted in a mobile information processing device or the like and is used for face authentication of a user to be accessed. Conventionally, in a mobile information processing device or the like, methods for authenticating a user by password, fingerprint, iris, etc. have been used. In recent years, a more secure authentication method has been sought. Therefore, a measuring device for measuring the three-dimensional shape is mounted in the mobile information processing device. That is, a three-dimensional image of the face of the user to be accessed is obtained, and it is identified whether access is permitted. Only in the case of a user who is authenticated as being permitted to access, the use of the own device (mobile information processing device) is permitted.

[0045] Moreover, such a measuring device is also applicable to cases where the three-dimensional shape of the measurement object is continuously measured, such as in Augmented Reality (AR).

[0046] In a measuring device for measuring the three-dimensional shape by the ToF method, a short rise time of the light emission of the light source is required. The shorter the rise time of the light emission of the light source, the higher the measurement accuracy. Therefore, the smaller the inductance (circuit inductance) of the drive circuit that supplies the current for the light source to drive the light source, the shorter the rise time of the light emission of the light source. If the circuit inductance is large, it will cause a delay in the high-frequency component and make the rise time longer. That is, it is required to reduce the circuit inductance and shorten the rise time of the light emission of the light source. To reduce the circuit inductance, it is effective to shorten the length of the drive circuit that supplies the current for the light source to drive the light source.

[0047] Moreover, the heat generation of the light source is large. In the face authentication, it is sufficient to irradiate the face with light for a short time, but in the case of continuously irradiating the measurement object with light in extended reality or the like, the heat generation of the light source becomes larger, and heat dissipation becomes important.

[0048] The structures, functions, methods, etc. described in the present embodiment described below can be applied to the measurement of the three-dimensional shape of a measurement object other than face authentication or augmented reality.

[0049] (Measuring Device 1)

[0050] Figure 1It is a block diagram showing an example of the structure of a measuring device 1 for measuring a three-dimensional shape.

[0051] The measuring device 1 includes an optical device 3 and a control unit 8. The control unit 8 controls the optical device 3. Further, the control unit 8 includes a three-dimensional shape determination unit 81 that determines the three-dimensional shape of the object to be measured. The control unit 8 is configured as a computer including a Central Processing Unit (CPU), a Read Only Memory (ROM), a Random Access Memory (RAM), etc. In addition, the ROM includes a non-volatile rewritable memory, such as a flash memory. And by expanding the program or constants stored in the ROM in the RAM and executing the program by the CPU, the three-dimensional shape determination unit 81 is constituted to determine the three-dimensional shape of the object to be measured.

[0052] The following will be described in sequence.

[0053] The optical device 3 includes a light-emitting device 4 and a 3D sensor 5.

[0054] The light-emitting device 4 includes a wiring board 10, a heat dissipation base material 100, a light source 20, a light diffusion member 30, a drive unit 50, a holding unit 60, and capacitors 70A and 70B. Further, the light-emitting device 4 may also include passive components such as a resistance element 6 and a capacitor 7 to operate the drive unit 50. Here, it is assumed that there are two resistance elements 6 and capacitors 7 respectively. Moreover, two capacitors 70A and 70B are described, but it may also be one. In addition, when not distinguishing between the capacitors 70A and 70B, it is denoted as capacitor 70. Further, the resistance element 6 and the capacitor 7 may be one each or multiple. Here, sometimes the electronic components such as the 3D sensor 5, the resistance element 6, and the capacitor 7 other than the light source 20, the drive unit 50, and the capacitor 70 are not distinguished separately and are called circuit components. In addition, a capacitor is sometimes called a capacitance. The 3D sensor 5 is an example of a light-receiving part. The capacitor 70 (capacitors 70A and 70B) is an example of a capacitance element.

[0055] The heat dissipation base material 100, the drive unit 50, the resistance element 6, and the capacitor 7 of the light-emitting device 4 are provided on the surface of the wiring board 10. In addition, Figure 1 in, the 3D sensor 5 is not provided on the surface of the wiring board 10, but it may also be provided on the surface of the wiring board 10.

[0056] The light source 20, the capacitors 70A and 70B, and the holding part 60 may also be provided on the surface of the heat dissipation substrate 100. Further, the light diffusion member 30 is provided on the holding part 60. Here, it is assumed that the outer shape of the heat dissipation substrate 100 is the same as that of the light diffusion member 30. Regarding these structures, details will be described using (a) to Figure 6 of the following Figure 8 . Here, the surface means Figure 1 the front side of the paper surface of. More specifically, in the wiring substrate 10, the portion where the heat dissipation substrate 100 is provided is referred to as the surface, the front side, or the front surface side. Further, in the heat dissipation substrate 100, the portion where the light source 20 is provided is referred to as the surface, the front side, or the front surface side.

[0057] The light source 20 is configured as a light-emitting element array in which a plurality of light-emitting elements are two-dimensionally arranged (refer to Figure 2 described later). As an example, the light-emitting element is a Vertical Cavity Surface Emitting Laser (VCSEL). Hereinafter, it is assumed that the light-emitting element is a vertical cavity surface emitting laser VCSEL for description. Further, the vertical cavity surface emitting laser VCSEL is referred to as VCSEL. Since the light source 20 is provided on the surface of the heat dissipation substrate 100, the light source 20 emits light perpendicularly to the surface of the heat dissipation substrate 100 in a direction away from the heat dissipation substrate 100. That is, the light-emitting element array is a surface-emitting laser element array. In addition, the surface of the light source 20 where a plurality of light-emitting elements are two-dimensionally arranged and light is emitted is sometimes referred to as the emission surface. The light source 20 is an example of the laser unit.

[0058] The light diffusion member 30 receives the light emitted from the light source 20. Further, the light diffusion member 30 diffuses the incident light and emits it. The light diffusion member 30 is provided so as to cover the light source 20 and the capacitors 70A and 70B. That is, the light diffusion member 30 is provided at a predetermined distance from the light source 20 and the capacitors 70A and 70B provided on the heat dissipation substrate 100 through the holding part 60 provided on the surface of the heat dissipation substrate 100. Therefore, the light emitted from the light source 20 is diffused by the light diffusion member 30 and irradiated onto the object to be measured. That is, compared with the case where the light diffusion member 30 is not included, the light emitted from the light source 20 is diffused by the light diffusion member 30 and irradiated over a wider range.

[0059] In the case of three-dimensional measurement by the ToF method, the light source 20 is required to emit a pulse light (hereinafter referred to as the emitted light pulse) of, for example, 100 MHz or more and a rise time of less than 1 ns through the driving unit 50. In addition, in the case of facial recognition as an example, the distance of the irradiated light is about 10 cm to about 1 m. And the range of the irradiated light is about 1 m square. In addition, the distance of the irradiated light is called the measurement distance, and the range of the irradiated light is called the irradiation range or the measurement range. And, the surface hypothetically set in the irradiation range or the measurement range is called the irradiation surface. In addition, in cases other than facial recognition, the measurement distance to the object to be measured and the irradiation range of the object to be measured may also be other than those described above.

[0060] The 3D sensor 5 includes a plurality of light receiving cells, and is a component as described below, that is, outputting a signal, which is equivalent to the time from the time when the light source 20 emits light to the time when it is received by the 3D sensor 5. For example, each light receiving cell of the 3D sensor 5 receives a pulsed reflected light (hereinafter referred to as a light receiving pulse) from the object to be measured relative to the outgoing light pulse from the light source 20, and stores a charge corresponding to the time until the light is received in each light receiving cell. The 3D sensor 5 is configured as an element of a complementary metal oxide semiconductor (CMOS) structure in which each light receiving cell includes two gates and a charge storage unit corresponding to them. And, by alternately applying pulses to the two gates, the generated photoelectrons are transmitted to either of the two charge storage units at a high speed. In the two charge storage units, charges corresponding to the phase difference between the outgoing light pulse and the light receiving pulse are stored. Furthermore, the 3D sensor 5 outputs a digital value corresponding to the phase difference between the outgoing light pulse and the received light pulse as a signal corresponding to each light receiving cell via an analog digital (AD) converter. That is, the 3D sensor 5 outputs a signal corresponding to the time from the time when the light is emitted from the light source 20 to the time when the light is received by the 3D sensor 5. That is, a signal corresponding to the three-dimensional shape of the object to be measured is obtained from the 3D sensor 5. In addition, the AD converter may be included in the 3D sensor 5 or may be provided outside the 3D sensor 5.

[0061] When the 3D sensor 5 is, for example, an element of the aforementioned CMOS structure, the three-dimensional shape determination unit 81 of the control unit 8 obtains the digital value obtained for each light-receiving cell, and calculates the distance to the object to be measured for each light-receiving cell. And, the three-dimensional shape of the object to be measured is determined based on the calculated distance, and the determination result is output. A signal corresponding to the three-dimensional shape can be obtained.

[0062] As described above, it is assumed that the control unit 8 is configured as a computer, and the three-dimensional shape determination unit 81 is implemented by a program. However, they may also include integrated circuits such as application specific integrated circuit (ASIC) or field programmable gate array (FPGA). Further, they may also include software such as a program and an integrated circuit such as ASIC.

[0063] As described above, the measuring device 1 diffuses the light emitted from the light source 20 and irradiates the object to be measured, and receives the reflected light from the object to be measured by the 3D sensor 5. In this way, the measuring device 1 measures the three-dimensional shape of the object to be measured. Thus, regardless of face authentication, in the measurement of the three-dimensional shape such as extended reality, it is required that the light source 20 has a large output. Therefore, it is required that heat is efficiently dissipated from the light source 20.

[0064] Figure 1 In the figure, the optical device 3 and the control unit 8 are separately shown, but they may also be integrally formed.

[0065] First, the light source 20, the light diffusion member 30, the drive unit 50, the capacitor 70A, and the capacitor 70B that constitute the light emitting device 4 will be described.

[0066] (Structure of the light source 20)

[0067] Figure 2 is a plan view of the light source 20. The light source 20 is formed by arranging a plurality of VCSELs in a two-dimensional array. That is, the light source 20 is configured as a light emitting element array using VCSEL as a light emitting element. The right direction of the paper surface is set as the x direction, and the upper direction of the paper surface is set as the y direction. The direction orthogonal to the x direction and the y direction in the counterclockwise direction is set as the z direction. In addition, the surface of the light source 20 refers to the front side of the paper surface, that is, the +z direction side surface, and the back surface of the light source 20 refers to the back side of the paper surface, that is, the -z direction side surface. The plan view of the light source 20 is a view of the light source 20 observed from the surface side. For further explanation, in the light source 20, the place where the epitaxial layer that functions as a light emitting layer (active region 206 described later) is formed is called the surface, front side, or front side of the light source 20.

[0068] The VCSEL is a light emitting laser element as described below, that is, it is stacked on a semiconductor substrate 200 (refer to the following Figure 3) An active region that serves as a light-emitting region is provided between the lower multilayer film mirror and the upper multilayer film mirror on []. The laser light is emitted in a direction perpendicular to the surface. Thus, compared with the case of using an end-face-emitting laser element, the VCSEL can be more easily arrayed two-dimensionally. As an example, the number of VCSELs included in the light source 20 is 100 to 1000. In addition, the multiple VCSELs are connected in parallel to each other and are driven in parallel. The number of the VCSELs is an example and can be set according to the measurement distance or the irradiation range.

[0069] On the surface of the light source 20, an anode electrode 218 shared by multiple VCSELs is provided (refer to Figure 3 ) described later. On the back surface of the light source 20, a cathode electrode 214 is provided (refer to Figure 3 ) described later. That is, the multiple VCSELs are connected in parallel. By driving the multiple VCSELs in parallel, compared with the case of independently driving the VCSELs, light with a stronger intensity can be emitted.

[0070] Here, assume that the shape of the light source 20 when viewed from the surface side (referred to as the planar shape, the same applies hereinafter) is rectangular. And the side on the -y direction side is referred to as the side surface 21A, the side on the +y direction side is referred to as the side surface 21B, the side on the -x direction side is referred to as the side surface 22A, and the side on the +x direction side is referred to as the side surface 22B. The side surface 21A faces the side surface 21B. The side surface 22A and the side surface 22B are respectively connected to the side surface 21A and the side surface 21B and face each other.

[0071] And the center of the planar shape of the light source 20, that is, the center in the x direction and the y direction, is set as the center Ov.

[0072] (Structure of VCSEL)

[0073] Figure 3 It is a diagram showing the cross-sectional structure of one VCSEL in the light source 20. The VCSEL is a VCSEL with a λ resonance structure. The upper direction of the paper surface is set as the z direction, the +z direction is referred to as the upper side, and the -z direction is referred to as the lower side.

[0074] A VCSEL is formed by sequentially stacking an n-type lower distributed Bragg reflector (DBR) 202, an active region 206, and a p-type upper distributed Bragg reflector 208 on an n-type semiconductor substrate 200 such as GaAs. The n-type lower distributed Bragg reflector 202 is formed by alternately overlapping AlGaAs layers with different Al compositions. The active region 206 includes a quantum well layer sandwiched between an upper spacer layer and a lower spacer layer. The p-type upper distributed Bragg reflector 208 is formed by alternately overlapping AlGaAs layers with different Al compositions. Hereinafter, the distributed Bragg reflector is referred to as DBR.

[0075] The n-type lower DBR 202 is configured as a stacked body in which Al 0.9 Ga 0.1 As layers and GaAs layers are paired. The thickness of each layer of the lower DBR 202 is λ / 4n r (where λ is the oscillation wavelength and n r is the refractive index of the medium), and they are alternately stacked for 40 periods. As a carrier, silicon, which is an n-type impurity, is doped. The carrier concentration is, for example, 3×10 18 cm -3 .

[0076] The active region 206 is formed by stacking a lower spacer layer, a quantum well active layer, and an upper spacer layer. For example, the lower spacer layer is an undoped Al 0.6 Ga 0.4 As layer, the quantum well active layer is an undoped InGaAs quantum well layer and an undoped GaAs barrier layer, and the upper spacer layer is an undoped Al 0.6 Ga 0.4 As layer.

[0077] The p-type upper DBR 208 is configured as a stacked body in which p-type Al 0.9 Ga 0.1 As layers and GaAs layers are paired. The thickness of each layer of the upper layer DBR 208 is λ / 4n r , and they are alternately stacked for 29 periods. As a carrier, carbon, which is a p-type impurity, is doped. The carrier concentration is, for example, 3×10 18 cm -3 . Preferably, a contact layer containing p-type GaAs is formed on the uppermost layer of the upper DBR 208, and a current confinement layer 210 of p-type AlAs is formed in or on the lowermost layer of the upper DBR 208.

[0078] By etching the semiconductor layer stacked from the upper DBR 208 to the lower DBR 202, a cylindrical mesa M is formed on the semiconductor substrate 200. As a result, the current confinement layer 210 is exposed on the side surface of the mesa M. Through an oxidation process, in the current confinement layer 210, an oxidized region 210A formed by oxidizing from the side surface of the mesa M and a conductive region 210B surrounded by the oxidized region 210A are formed. In addition, in the oxidation process, the oxidation rate of the AlAs layer is faster than that of the AlGaAs layer, and the oxidized region 210A is oxidized at a substantially constant rate from the side surface of the mesa M toward the inside. Therefore, the cross-sectional shape of the conductive region 210B becomes a circular shape that reflects the outer shape of the mesa M, and its center is substantially aligned with the axis of the mesa M indicated by the dash-dot line. In the present embodiment, the mesa M has a columnar structure.

[0079] On the uppermost layer of the mesa M, a metal ring-shaped p-side electrode 212 formed by laminating Ti / Au or the like is formed. The p-side electrode 212 makes an ohmic contact with the contact layer provided on the upper DBR 208. The inside of the ring-shaped p-side electrode 212 becomes a light exit port 212A through which laser light exits to the outside. That is, the VCSEL emits light in a direction perpendicular to the surface of the semiconductor substrate 200 (+z direction side surface). And the axis of the mesa M becomes the optical axis. Further, on the back surface of the semiconductor substrate 200, a cathode electrode 214 serving as an n-side electrode is formed. In addition, the surface (+z direction side surface) of the upper DBR 208 inside the p-side electrode 212 is the light exit surface. That is, the optical axis direction of the VCSEL becomes the light exit direction.

[0080] And an insulating layer 216 is provided so as to cover the surface of the mesa M except for the portion where the anode electrode 218 is connected to the p-side electrode 212 and the light exit port 212A. And the anode electrode 218 is provided in ohmic contact with the p-side electrode 212 except for the light exit port 212A. In addition, the anode electrode 218 is provided in common for a plurality of VCSELs. That is, the p-side electrodes 212 of the plurality of VCSELs constituting the light source 20 are connected in parallel through the anode electrode 218.

[0081] Figure 3 In [A] indicating the anode is marked at the portion of the anode electrode 218, and [K] indicating the cathode is marked at the portion of the cathode electrode 214.

[0082] The VCSEL can oscillate in a single transverse mode or a multi-transverse mode. For example, the light output of one VCSEL is 4 mW to 8 mW. Therefore, when the light source 20 includes 500 VCSELs, the light output of the light source 20 is 2 W to 4 W. Heat generation of such a high-output light source 20. Therefore, it is required to dissipate heat from the light source 20 efficiently.

[0083] (Structure of the light diffusing member 30)

[0084] Figure 4 in (a) and Figure 4 in (b) of FIG. are diagrams illustrating an example of the light diffusing member 30. Figure 4 In (a) of FIG., the right direction of the paper surface is defined as the x direction, and the upper direction of the paper surface is defined as the y direction. The direction orthogonal to the x direction and the y direction in the counterclockwise direction is defined as the z direction. Further, in the light diffusing member 30, the +z direction side is referred to as the front surface or the front surface side, and the -z direction side is referred to as the back surface or the back surface side. Thus, Figure 4 in (b) of FIG., the right direction of the paper surface is the x direction, the back direction of the paper surface is the y direction, and the upper direction of the paper surface is the z direction. Figure 4 in (a) of FIG., is a cross-sectional view taken along line IVB-IVB. Figure 4 In (a) of FIG., the right direction of the paper surface is defined as the x direction, the upper direction of the paper surface is defined as the y direction. The direction orthogonal to the x direction and the y direction in the counterclockwise direction is defined as the z direction. Further, in the light diffusing member 30, the +z direction side is referred to as the front surface or the front surface side, and the -z direction side is referred to as the back surface or the back surface side. Thus, Figure 4 in (b) of FIG., the right direction of the paper surface is the x direction, the back direction of the paper surface is the y direction, and the upper direction of the paper surface is the z direction.

[0085] As Figure 4 shown in (b) of FIG., the light diffusing member 30 includes, for example, a resin layer 32 formed with irregularities for diffusing light on the back surface (-z direction) side of the glass substrates 31 that are parallel and flat on both sides. The light diffusing member 30 expands the divergence angle of the light incident from the VCSEL of the light source 20 and emits it. That is, the irregularities formed in the resin layer 32 of the light diffusing member 30 refract or scatter the light, so that the incident light is emitted as light with a wider divergence angle. That is, as Figure 4 shown in (a) of FIG. and Figure 4 in (b) of FIG., the light diffusing member 30 causes the light with a divergence angle θ emitted from the VCSEL and incident from the back surface (-z direction side) to become light with a divergence angle larger than the divergence angle θ and be emitted from the front surface (+z direction side) Therefore, when the light diffusing member 30 is used, the area of the irradiated surface irradiated with the light emitted from the light source 20 is enlarged compared with the case where the light diffusing member 30 is not used. The divergence angle θ, the divergence angle is the full width at half maximum (FWHM).

[0086] Here, it is assumed that the light diffusing member 30 has the same planar shape as the heat dissipation substrate 100 described later. Further, the thickness t (thickness in the z direction) of the light diffusing member 30 d is 0.1 mm to 1 mm. Further, the planar shape of the light diffusing member 30 may also be other shapes such as a polygon or a circle.

[0087] (Drive unit 50 and capacitors 70A, 70B)

[0088] When it is desired to drive the light source 20 at a higher speed, low-side driving can be performed. Low-side driving refers to the following structure, that is, a driving element such as an MOS transistor is located on the downstream side of the current path with respect to a driving object such as a VCSEL. On the contrary, a structure in which the driving element is located on the upstream side is called high-side driving.

[0089] Figure 5 FIG. is an example of an equivalent circuit when driving the light source 20 by low-side driving. Figure 5 shows the VCSEL of the light source 20, the driving unit 50, the capacitors 70A, 70B, and the power supply 82. In addition, the power supply 82 is provided in Figure 1 the control unit 8 shown. The power supply 82 generates a DC voltage with the + side set to the power supply potential and the - side set to the reference potential. The power supply potential is supplied to the power supply line 83, and the reference potential is supplied to the reference line 84. In addition, the reference potential can be a ground potential (sometimes referred to as GND, Figure 5 marked as [G] in).

[0090] As described above, the light source 20 is composed of a plurality of VCSELs connected in parallel. The anode electrode 218 of the VCSEL (refer to Figure 3 ), Figure 5 marked as [A] in) is connected to the power supply line 83.

[0091] The driving unit 50 includes an n-channel MOS transistor 51 and a signal generation circuit 52 that turns the MOS transistor 51 on and off. The drain of the MOS transistor 51 ( Figure 5 marked as [D] in) is connected to the cathode electrode 214 of the VCSEL (refer to Figure 3 ), Figure 5 marked as [K] in). The source of the MOS transistor 51 ( Figure 5 marked as [S] in) is connected to the reference line 84. And, the gate of the MOS transistor 51 is connected to the signal generation circuit 52. That is, the VCSEL and the MOS transistor 51 of the driving unit 50 are connected in series between the power supply line 83 and the reference line 84. The signal generation circuit 52 generates a signal of "H level" that sets the MOS transistor 51 to the on state and a signal of "L level" that sets the MOS transistor 51 to the off state under the control of the control unit 8.

[0092] One terminal of each of the capacitors 70A and 70B is connected to the power supply line 83, and the other terminal is connected to the reference line 84. Here, when there are a plurality of capacitors 70, the plurality of capacitors 70 are connected in parallel. That is, Figure 5 in, it is assumed that the capacitor 70 is two capacitors 70A and 70B. In addition, the capacitor 70 is, for example, an electrolytic capacitor or a ceramic capacitor.

[0093] Next, a driving method for the light source 20 for low-side driving will be described.

[0094] First, assume that the signal generated by the signal generation circuit 52 in the driving unit 50 is at "L level". At this time, the MOS transistor 51 is in an off state. That is, no current flows between the source ([S]) and the drain ([D]) of the MOS transistor 51. Therefore, no current flows through the VCSEL connected in series with the MOS transistor 51. That is, the VCSEL does not emit light. Figure 5 of [S]) - drain ( Figure 5 of [D]) and no current flows. Thus, no current flows through the VCSEL connected in series with the MOS transistor 51. That is, the VCSEL does not emit light.

[0095] At this time, the capacitors 70A and 70B are connected to the power supply 82. One terminal of the capacitors 70A and 70B connected to the power supply line 83 becomes the power supply potential, and the other terminal connected to the reference line 84 becomes the reference potential. Therefore, the capacitors 70A and 70B are charged by flowing current (being supplied with charge) from the power supply 82.

[0096] Next, when the signal generated by the signal generation circuit 52 in the driving unit 50 changes to "H level", the MOS transistor 51 changes from the off state to the on state. Then, a closed loop is formed by the capacitors 70A and 70B, the MOS transistor 51 connected in series, and the VCSEL. The charge stored in the capacitors 70A and 70B is supplied to the MOS transistor 51 and the VCSEL connected in series. That is, a driving current flows through the VCSEL and the VCSEL emits light. The closed loop is the driving circuit for driving the light source 20.

[0097] Moreover, when the signal generated by the signal generation circuit 52 in the driving unit 50 changes to "L level" again, the MOS transistor 51 changes from the on state to the off state. As a result, the closed loop (driving circuit) of the capacitors 70A and 70B, the MOS transistor 51 connected in series, and the VCSEL becomes an open loop, and no driving current flows through the VCSEL. Thus, the VCSEL stops emitting light. Then, the capacitors 70A and 70B are supplied with charge from the power supply 82 and are charged.

[0098] As described above, whenever the signal output by the signal generation circuit 52 changes between "H level" and "L level", the MOS transistor 51 repeatedly turns on and off, and the VCSEL repeatedly emits light and does not emit light. The repeated on and off of the MOS transistor 51 is sometimes referred to as switching.

[0099] As described above, when the MOS transistor 51 is changed from the off state to the on state, the charges stored in the capacitors 70A and 70B are discharged all at once and supplied as a drive current to the VCSEL. As a result, the VCSEL emits light, for example, with a short rise time of 1 ns or less. In addition, after the light emission of the VCSEL stops, the supply (charging) of the charges to the capacitors 70A and 70B from the power supply 82 takes a longer time than the rise time. Alternatively, the capacitors 70A and 70B may not be provided, and the drive current may be directly supplied from the power supply 82 to the VCSEL. However, the path for supplying the current becomes longer, resulting in a longer rise time for the light emission of the VCSEL.

[0100] As described above, by supplying the drive current to the VCSEL all at once through the low-side drive with the capacitors 70A and 70B, the rise time of the light emission of the VCSEL is shortened. To shorten the rise time of the light emission of the VCSEL, it is preferable that the circuit inductance of the drive circuit that supplies the drive current for light emission to the light source 20, including the capacitors 70A and 70B, the MOS transistor 51 connected in series, and the VCSEL, is small. And to reduce the circuit inductance, the shorter the path through which the drive current flows in the drive circuit, the better. Therefore, it is preferable to shorten the distance between the light source 20 and the drive unit 50, and the distance between the light source 20 and the capacitors 70A and 70B, and shorten the length of the wiring connecting the respective components.

[0101] (Light-emitting device 4)

[0102] Next, the light-emitting device 4 will be described in detail.

[0103] Figure 6 of (a) and Figure 6 of (b) are diagrams for explaining the light-emitting device 4 to which the present embodiment is applied. Figure 6 of (a) is a plan view, Figure 6 of (b) is Figure 6 a cross-sectional view taken along the line VIB-VIB of (a). In addition, Figure 6 of (a) is a view observed through the light diffusion member 30. Here, Figure 6 in of (a), the right direction of the paper surface is set as the x direction, and the upper direction of the paper surface is set as the y direction. The direction orthogonal to the x direction and the y direction in the counterclockwise direction (the front side of the paper surface) is set as the z direction. And for each component (wiring substrate 10, heat dissipation substrate 100, light diffusion member 30, etc.) described below, the front side of the paper surface (+z direction) is referred to as the front surface or the front surface side, and the back side of the paper surface (-z direction) is referred to as the back surface or the back surface side. And hereinafter, observing each component through the front surface side is referred to as a top view. In addition, Figure 6In (b), the right direction on the paper surface is the x-direction, the inner direction of the paper surface is the y-direction, and the upward direction of the paper surface is the z-direction.

[0104] As Figure 6 shown in (a) and Figure 6 shown in (b), a heat dissipation substrate 100, a driving unit 50, a resistance element 6, and a capacitor 7 are provided on the surface of the wiring substrate 10. Further, a light source 20, a capacitor 70A, a capacitor 70B, and a holding unit 60 are provided on the surface of the heat dissipation substrate 100. Further, a light diffusion member 30 is provided on the holding unit 60.

[0105] The wiring substrate 10 is formed, for example, by providing a wiring layer on an insulating substrate such as glass epoxy resin, and the wiring layer forms a wiring including a metal such as copper (Cu) foil. Here, the wiring substrate 10 is described as a double-sided printed circuit board having wiring layers on both the front and back sides of the substrate. As an example of such a substrate using glass epoxy resin as the substrate, there is a substrate called FR-4. The thickness of the substrate is about 100 μm. Further, the thermal conductivity of the substrate is about 0.4 W / m·K. In addition, the thermal conductivity of copper (Cu) is about 360 W / m·K. Unless otherwise specified, the thermal conductivity shown here is the value at 25°C. The substrate of the wiring substrate 10 is an example of the second substrate.

[0106] The heat dissipation substrate 100 is a member having a higher thermal conductivity than the wiring substrate 10 and includes an insulating substrate. For example, the heat dissipation substrate 100 preferably has a substrate with a thermal conductivity of 10 W / m·K or more, and more preferably 50 W / m·K or more. Further, it is more preferably a substrate with a thermal conductivity of 100 W / m·K or more. As a substrate with a thermal conductivity of 10 W / m·K or more, alumina (Al2O3) with a thermal conductivity of 20 W / m·K to 30 W / m·K can be cited. Further, as a substrate with a thermal conductivity of 50 W / m·K or more, silicon nitride (Si3N4) with a thermal conductivity of about 85 W / m·K can be cited. Further, as a substrate with a thermal conductivity of 100 W / m·K or more, aluminum nitride (AlN) with a thermal conductivity of 150 W / m·K to 250 W / m·K can be cited. Sometimes they are called ceramic materials. Further, the heat dissipation substrate 100 may entirely include a ceramic material. If the heat dissipation substrate 100 includes a ceramic material, the heat dissipation effect becomes higher compared to the case of including a resin material. In addition, the heat dissipation substrate 100 may also be another highly thermally conductive insulating material such as silicon (Si) without impurities. The heat dissipation substrate 100 is an example of the first substrate.

[0107] Here, it is assumed that the outer shapes of the heat dissipation base material 100, the light diffusion member 30, and the holding portion 60 are the same. Therefore, the outer edges of the heat dissipation base material 100, the light diffusion member 30, and the holding portion 60 coincide. Additionally, the outer edge of the heat dissipation base material 100 may also be larger than the outer edge of the light diffusion member 30 or the outer edge of the holding portion 60. Conversely, the outer edge of the heat dissipation base material 100 may also be smaller than the outer edge of the light diffusion member 30 or the outer edge of the holding portion 60. At this time, the holding portion 60 only needs to be provided on the surface of the wiring board 10.

[0108] The heat dissipation base material 100 has the following planar shape, that is, it has a planar shape in the long side direction and the short side direction. Additionally, Figure 6 In (a) of, as an example, the planar shape of the heat dissipation base material 100 is shown as a rectangle, but it may also be a polygon or an ellipse having a long side direction and a short side direction. Additionally, a shape having a long side direction and a short side direction in the planar shape is sometimes referred to as an elongated shape. Figure 6 In (a) of, the long side direction of the heat dissipation base material 100 is the y direction, and the short side direction is the x direction. And, let the width in the long side direction of the heat dissipation base material 100 be Whl, and the width in the short side direction be Wh2 (Wh1 > Wh2). The width Wh1 in the long side direction and the width Wh2 in the short side direction of the heat dissipation base material 100 are, for example, 1 mm to 30 mm. Moreover, the thickness of the heat dissipation base material 100 is 100 μm to 500 μm. And, the center of the heat dissipation base material 100 (the center of the width Wh1 in the long side direction and the center of the width Wh2 in the short side direction) is set as the center Oh. Additionally, the width Wh1 in the long side direction and the width Wh2 in the short side direction of the heat dissipation base material 100 may also be the same.

[0109] And, one side (-y direction) in the long side direction of the heat dissipation base material 100 is referred to as the side surface 101A, the other side (+y direction) in the long side direction is referred to as the side surface 101B, one side (-x direction) in the short side direction is referred to as the side surface 102A, and the other side (+x direction) in the short side direction is referred to as the side surface 102B. The side surface 101A and the side surface 101B face each other. The side surface 102A and the side surface 102B are respectively connected to the side surface 101A and the side surface 101B and face each other.

[0110] As Figure 6As shown in (a) of FIG. 0, in the light-emitting device 4, the driving unit 50 is arranged on the extension line of the short side direction (x direction) of the heat dissipation substrate 100. In addition, the extension line of the short side direction means the part on the short side direction side of the heat dissipation substrate 100 and away from the heat dissipation substrate 100. And the driving unit 50 is provided within the width range in the long side direction of the heat dissipation substrate 100. That is, the driving unit 50 is provided within the range between the lead wire (101A') that leads out the end on one (-y direction) side in the long side direction of the heat dissipation substrate 100 to the driving unit 50 side and the lead wire (101B') that leads out the end on the other (+y direction) side in the long side direction of the heat dissipation substrate 100 to the driving unit 50 side. Thereby, the distance between the light source 20 and the driving unit 50 becomes shorter, bringing the light source 20 closer to the driving unit 50. In addition, the driving unit 50 may be provided in such a manner that a part thereof overlaps the range between the lead wire (101A') and the lead wire (101B') led out from the heat dissipation substrate 100 to the driving unit 50 side.

[0111] Furthermore, the center Ov of the light source 20 is set to deviate toward the driving unit 50 side from the center Oh of the heat dissipation substrate 100. In addition, setting to deviate means that the center Ov of the light source 20 is set at a position closer to the driving unit 50 than the center Oh of the heat dissipation substrate 100. In addition, the center Oh of the heat dissipation substrate 100, the center Ov of the light source 20, and the center (not shown) of the driving unit 50 may not necessarily be arranged in a straight line. That is, as long as in the short side direction (x direction) of the heat dissipation substrate 100, the center Ov of the light source 20 is set at a position closer to the driving unit 50 than the center Oh of the heat dissipation substrate 100. Thereby, the distance between the light source 20 and the driving unit 50 becomes shorter. In addition, from the viewpoint of heat dissipation, the light source 20 can be arranged at the center Oh of the heat dissipation substrate 100, but since the heat conductivity of the heat dissipation substrate 100 is large, even if the light source 20 is arranged deviating from the center Oh of the heat dissipation substrate 100, the influence on heat dissipation is small. Here, in order to shorten the rise time of the light emission of the light source 20, the light source 20 is arranged to deviate from the center Oh of the heat dissipation substrate 100 toward the driving unit 50 side to shorten the driving circuit.

[0112] And on the surface of the heat dissipation substrate 100, the anode wiring 112F is provided on the side away from the driving unit 50. That is, the anode wiring 112F is arranged to deviate from the center Oh of the heat dissipation substrate 100 toward the side away from the driving unit 50.

[0113] The capacitors 70A and 70B are arranged with the light source 20 interposed therebetween in the long side direction (±y direction) of the heat dissipation base material 100. That is, by arranging the capacitors 70A and 70B in the long side direction of the heat dissipation base material 100, the area of the rectangular heat dissipation base material 100 is effectively utilized. Also, the centers Oca and Ocb of the capacitors 70A and 70B, respectively, are set to deviate toward the drive unit 50 side from the center Oh of the heat dissipation base material 100, similar to the light source 20. In addition, the light source 20 and the centers Oca and Ocb of the capacitors 70A and 70B, respectively, do not necessarily have to be arranged in a straight line. As long as the centers Oca and Ocb of the capacitors 70A and 70B are set to deviate toward the drive unit 50 side. Thereby, the distances between the light source 20 and the capacitors 70A and 70B become shorter, bringing the light source 20 closer to the capacitors 70A and 70B.

[0114] As Figure 6 shown in (a) of Figure 6 , the holding part 60 includes a wall shown by a dotted line that is provided so as to surround the light source 20 and the capacitors 70A and 70B. And, as

[0115] shown in (b) of

[0116] , the holding part 60 holds the light diffusion member 30 by the wall. That is, the light diffusion member 30 is provided at a predetermined distance from the light source 20 and the capacitors 70A and 70B provided on the heat dissipation base material 100 by the holding part 60. And the light diffusion member 30 is provided so as to cover the light source 20 and the capacitors 70A and 70B. Here, the light diffusion member 30 covering the light source 20 means that the light diffusion member 30 is provided on the light emission path of the light emitted from the light source 20 and the light emitted from the light source 20 passes through the light diffusion member 30. That is, it means a state where the light source 20 and the light diffusion member 30 overlap when looking down at the light diffusion member 30 through the surface side of the light diffusion member 30.

[0117] The wiring substrate 10 and the heat dissipation substrate 100 are provided with a plurality of wirings on the front and back sides thereof. Figure 7 (a) to Figure 7 (c) Figure 8 The wiring refers to a conductor pattern for connecting an electric circuit, and the shape is not limited.

[0118] As described above, the light source 20 is provided on the surface of the heat dissipation substrate 100. Furthermore, the heat dissipation substrate 100 is provided on the surface of the wiring substrate 10. Thus, the heat generated from the light source 20 is efficiently dissipated. As described above, since the thermal conductivity of the substrate constituting the wiring substrate 10 is small, the light source 20 is provided on the surface of the heat dissipation substrate 100 having a larger thermal conductivity than the wiring substrate 10.

[0119] Figure 7 (a) to Figure 7 (c) is a diagram for explaining wiring provided on the wiring board 10 and wiring provided on the heat dissipation substrate 100 . Figure 7 (a) is a wiring provided on the wiring substrate 10, Figure 7 (b) is a wiring provided on the surface side of the heat dissipation substrate 100, Figure 7 (c) is a wiring provided on the back side of the heat dissipation substrate 100. Figure 7 (a) Figure 7 (b) and Figure 7 The xyz direction shown in (c) is Figure 6 (a) and Figure 6 The xyz direction shown in (b) is the same. Therefore, Figure 7 The wiring provided on the back side of the heat dissipation substrate 100 shown in (c) shows the state observed from the front side of the heat dissipation substrate 100, and shows that the Figure 7 (b) shows the state of the wiring provided on the surface of the heat dissipation substrate 100 and the heat dissipation substrate 100. In addition, the portion of the light source 20 connected to the cathode electrode 214 is marked as [K], the portion connected to the anode electrode 218 is marked as [A], and the portion supplied with the reference potential is marked as [G].

[0120] First of all, Figure 7 The wiring provided on the wiring substrate 10 shown in (a) will be described. Figure 7 In (a) of FIG. 1 , the outer shape of the heat dissipation substrate 100 is indicated by a dashed line.

[0121] Figure 7 In (a), the solid lines represent the wiring provided on the surface side of the wiring substrate 10, and the dotted lines represent the wiring provided on the back side of the wiring substrate 10. That is, on the surface side of the wiring substrate 10, the cathode wiring 11, the anode wiring 12, and the reference potential wiring 13F are provided which are insulated from each other.

[0122] The planar shape of the cathode wiring 11 is rectangular, the end on the +x direction side is connected to the driving unit 50, and the end on the -x direction side is connected to the cathode electrode 214 of the light source 20 via the heat dissipation substrate 100 (refer to Figure 6 of (a) and Figure 6 of (b)).

[0123] The planar shape of the anode wiring 12 is rectangular, the end on the +x direction side is connected to the anode electrode 218 of the light source 20 via the heat dissipation substrate 100, and the end on the -x direction side is connected to the + side of the power supply 82. Further, the anode wiring 12, the reference potential wiring 13, and the cathode wiring 11 are arranged in the x direction. Further, the reference potential wiring 13 is provided so as to extend in the ±y direction from the cathode wiring 11 and the anode wiring 12, and the extended portions are expanded in the ±x direction.

[0124] On the back side of the wiring substrate 10, a reference potential wiring 13B is provided. Further, the reference potential wiring 13F provided on the front side of the wiring substrate 10 and the reference potential wiring 13B provided on the back side are electrically connected by a conductive through-conductor 13V (refer to Figure 6 of (b)). Further, a reference potential is supplied to the reference potential wiring 13B provided on the back side. That is, the reference potential wiring 13F provided on the front side is supplied with the reference potential from the reference potential wiring 13B provided on the back side. Here, the reference potential wiring 13B is provided over the entire back surface of the wiring substrate 10. Further, the area of the reference potential wiring 13B is set to be larger than the areas of the other cathode wiring 11 and anode wiring 12. Generally, in order to stabilize the potential of the wiring provided on the front side, the reference wiring provided on the back surface of the wiring substrate 10 is often provided over a large area on the back surface. Further, Figure 7 the marking of the through-conductor 13V is omitted in (a) of

[0125] Next, Figure 7 of (b) and Figure 7 the wiring provided on the heat dissipation substrate 100 shown in (c) of

[0126] As Figure 7 shown in (b) of Figure 6(b)). The anode wiring 112F is provided so as to surround three sides of the cathode wiring 111F (one short side direction (-x direction) side and long side directions (±y directions) of the heat dissipation substrate 100). The anode wiring 112F is connected to the anode electrode 218 of the light source 20 on the side surfaces 21A and 21B (±y direction sides) of the light source 20 through the bonding wires 23A and 23B (see Figure 6 (a)) of this specification. And, two reference potential wirings 113F are provided on the ±y direction sides of the anode wiring 112F.

[0127] As Figure 7 (c) of this specification shows, on the back side of the heat dissipation substrate 100, a cathode wiring 111B, an anode wiring 112B, and a reference potential wiring 113B insulated from each other are provided. In addition, Figure 7 in (c) of this specification, the cathode wiring 111F shown in (a) of this specification is indicated by a dashed line. Figure 7 (a) of this specification.

[0128] The cathode wiring 111B is provided at a position facing the cathode wiring 111F provided on the surface side of the heat dissipation substrate 100 with the heat dissipation substrate 100 interposed therebetween. However, the area of the cathode wiring 111B is set to be smaller than the area of the cathode wiring 111F. And, the cathode wiring 111F and the cathode wiring 111B are connected through the through-conductor 111V. The anode wiring 112B is provided at a position facing a part of the end portion on the x direction side of the anode wiring 112F provided on the surface side of the heat dissipation substrate 100 with the heat dissipation substrate 100 interposed therebetween. That is, the area of the anode wiring 112B is smaller than the area of the anode wiring 112F. And, the anode wiring 112F and the anode wiring 112B are electrically connected through the through-conductor 112V.

[0129] The reference potential wiring 113B is provided between the cathode wiring 111B and the anode wiring 112B and is provided so as to extend in the long side direction (±y direction) of the heat dissipation substrate 100 from the cathode wiring 111B and the anode wiring 112B. And, the end portion side in the long side direction (±y direction) of the reference potential wiring 113B is provided at a position facing the two reference potential wirings 113F provided on the surface side of the heat dissipation substrate 100 with the heat dissipation substrate 100 interposed therebetween. And, the reference potential wiring 113F and the reference potential wiring 113B are electrically connected through the through-conductor 113V at the end portion side in the long side direction (±y direction).

[0130] As described above, the shapes of the cathode wiring 111F and the cathode wiring 111B, the anode wiring 112F and the anode wiring 112B, and the reference potential wiring 113F and the reference potential wiring 113B provided on the surface side and the back side of the heat dissipation substrate 100 and electrically connected to each other are different. And, as Figure 7As shown in (c), in a top view, the edge portions of the reference potential wiring 113B and the cathode wiring 111F shown by the dashed line coincide with each other on the ±y-direction side and the -x-direction side. Here, the coincidence of the cathode wiring 111F and the reference potential wiring 113B is the coincidence width W1o. The edge portions of the reference potential wiring 113B and the light source 20 shown by the dashed line also coincide with each other on the long side direction (±y direction) side of the heat dissipation substrate 100 and one of the short side directions (-x direction). Here, the coincidence of the cathode wiring 111F and the light source 20 is the coincidence width W2o. The coincidence width W1o and the coincidence width W2o are the same on the long side direction (±y direction) side of the heat dissipation substrate 100 and one of the short side directions (-x direction). In addition, the coincidence is sometimes referred to as overlap.

[0131] Moreover, the area of the reference potential wiring 113B provided on the back side of the heat dissipation substrate 100 is set to be larger than the area of either the cathode wiring 111F or the anode wiring 112F provided on the front side of the heat dissipation substrate 100. And the area of the reference potential wiring 113B is set to include the sizes of the capacitors 70A and 70B. That is, in a top view, the capacitors 70A and 70B are included in the reference potential wiring 113F. In addition, the area of the reference potential wiring 113B provided on the back side of the heat dissipation substrate 100 may also be set to be larger than the area of either the cathode wiring 111F or the anode wiring 112F provided on the front side of the heat dissipation substrate 100.

[0132] Figure 8 FIG. is a diagram for further explaining the light-emitting device 4 to which the present embodiment is applied. Figure 8 is Figure 6 a cross-sectional view taken along VIII-VIII of the light-emitting device 4 shown in (a) of FIG.

[0133] Through Figure 6 (a) and Figure 6 (b) of FIG., Figure 7 (a) to Figure 7 (c) of FIG., and Figure 8 the electrical connection relationship in the light-emitting device 4 will be described.

[0134] As described above, a heat dissipation substrate 100 is provided on the surface of the wiring substrate 10, and a light source 20 and capacitors 70A and 70B are provided on the surface of the heat dissipation substrate 100.

[0135] The cathode wiring 11 provided on the surface side of the wiring substrate 10 is connected to the driving unit 50 (refer to Figure 6 (a) and Figure 6(b)). The cathode wiring 11 is connected to the cathode wiring 111B provided on the back side of the heat dissipation substrate 100 by solder or the like. The cathode wiring 111B is connected to the cathode wiring 111F provided on the front side of the heat dissipation substrate 100 via the through-conductor 111V provided in the heat dissipation substrate 100. Further, the light source 20 is mounted on the cathode wiring 111F and is connected to the cathode electrode 214 of the light source 20 (see Figure 6 (b), Figure 8 ). Here, since the light source 20 is provided on the heat dissipation substrate 100 so as to be deviated toward the driving unit 50 side, the cathode wiring 11 is set to be short (see Figure 6 (a) and Figure 6 (b)).

[0136] The anode wiring 12 provided on the front side of the wiring substrate 10 is connected to the anode wiring 112B provided on the back side of the heat dissipation substrate 100 by solder or the like. The anode wiring 112B is connected to the anode wiring 112F provided on the front side of the heat dissipation substrate 100 via the through-conductor 112V provided in the heat dissipation substrate 100. Further, the anode wiring 112F is connected to the anode electrode 218 of the light source 20 via the bonding wire 23A and the bonding wire 23B (see Figure 6 (a) and Figure 6 (b)).

[0137] The reference potential wiring 13F provided on the front side of the wiring substrate 10 is connected to the reference potential wiring 13B provided on the back side of the wiring substrate 10 via the through-conductor 13V (see Figure 6 (b), Figure 8 ). The reference potential wiring 13F is connected to the reference potential wiring 113B provided on the back of the heat dissipation substrate 100 by solder or the like (see Figure 6 (a), Figure 8 ). The reference potential wiring 113B is connected to the two reference potential wirings 113F provided on the front side of the heat dissipation substrate 100 via the through-conductor 113V provided in the heat dissipation substrate 100. Further, the capacitors 70A and 70B are disposed between the reference potential wiring 113F and the anode wiring 112F. That is, within the two reference potential wirings 113F, the capacitor 70A is provided and electrically connected between the reference potential wiring 113F on one long side direction (-y direction) side of the heat dissipation substrate 100 and the anode wiring 112F. Similarly, within the two reference potential wirings 113F, the capacitor 70B is provided and electrically connected between the reference potential wiring 113F on the other long side direction (+y direction) side of the heat dissipation substrate 100 and the anode wiring 112F (see Figure 6 (a), Figure 8 ).

[0138] The area of the anode wiring 112B provided on the back side of the heat dissipation substrate 100 is smaller than that of the reference potential wiring 113B. Current (charge is supplied) flows through the anode wiring 112B from the power source 82 (refer to Figure 5 ), and the capacitors 70A and 70B are charged. Therefore, the anode wiring 112B only needs to be directly connected in DC to the anode wiring 12 provided on the surface of the wiring substrate 10 and the anode wiring 112F provided on the surface of the heat dissipation substrate 100, and the circuit inductance can also be large. That is, the circuit for charging the capacitors 70A and 70B can also be longer than the drive circuit through which the current for making the light source 20 emit light flows.

[0139] Next, Figure 8 is used to illustrate the heat dissipation path of the heat generated by the light source 20 in the light emitting device 4 to which the present embodiment is applied.

[0140] As described above, the heat generation of the light source 20 is large. Therefore, it is required that the heat generated by the light source 20 is easily dissipated. As described above, metals such as copper (Cu) used as wiring materials have a high thermal conductivity. For example, the thermal conductivity of copper (Cu) is about 360 W / m·K, which is extremely large compared to about 0.4 W / m·K of the substrate used for the wiring substrate 10. Therefore, it is better that the heat generated by the light source 20 is dissipated to the outside from the frame body or the like via the reference potential wiring 13B provided on the back side of the wiring substrate 10. In particular, the area of the reference potential wiring 13B is larger than the areas of both the cathode wiring 11 and the anode wiring 12 provided on the surface side of the wiring substrate 10. Therefore, if the heat is conducted to the reference potential wiring 13B, it is easily dissipated. That is, the heat generated by the light source 20 can be dissipated to the reference potential wiring 13B provided on the back of the wiring substrate 10 over a short distance.

[0141] As Figure 8 shown, the cathode electrode 214 of the light source 20 is provided on the cathode wiring 111F provided on the surface side of the heat dissipation substrate 100. On the other hand, the anode electrode 218 of the light source 20 is connected to the anode wiring 112F provided on the surface side of the heat dissipation substrate 100 by the bonding wires 23A and 23B. Therefore, as the path for dissipating the heat (hereinafter referred to as heat) generated by the light source 20 (hereinafter referred to as the heat dissipation path), there are a path from the cathode electrode 214 to the cathode wiring 111F, a path from the anode electrode 218 to the anode wiring 112F via the bonding wires 23A and 23B, and a path to the surrounding space (air) of the light source 20. However, the heat dissipation paths to the bonding wires 23A and 23B and to the surrounding space (air) of the light source 20 are difficult to conduct heat. Therefore, the heat is conducted using the heat dissipation path from the cathode electrode 214 to the cathode wiring 111F.

[0142] As described above, the thermal conductivity of the heat dissipation base material 100 is 10 W / m·K or more, which is larger than about 0.4 W / m·K of the base material for the wiring substrate 10. Therefore, heat is conducted from the anode wiring 112F through the heat dissipation base material 100 to the cathode wiring 111B, the anode wiring 112B, and the reference potential wiring 113B provided on the back side of the heat dissipation base material 100. However, the cathode wiring 111B and the anode wiring 112B are respectively connected to the cathode wiring 11 and the anode wiring 12 of the wiring substrate 10. And neither the cathode wiring 11 nor the anode wiring 12 is connected to the reference potential wiring 13B. That is, heat is dissipated from the cathode wiring 11 and the anode wiring 12 through the base material of the wiring substrate 10. However, as described above, the thermal conductivity of the base material of the wiring substrate 10 is small.

[0143] On the other hand, the reference potential wiring 113F is connected to the reference potential wiring 13F provided on the front side of the wiring substrate 10, and the reference potential wiring 13F is connected to the reference potential wiring 13B provided on the back side of the wiring substrate 10 through the through-conductor 13V. Therefore, the heat conducted to the reference potential wiring 113B provided on the back side of the heat dissipation base material 100 is conducted to the reference potential wiring 13B through the reference potential wiring 13F and the through-conductor 13V ( Figure 8 the path α shown).

[0144] As described above, in the light-emitting device 4 to which the present embodiment is applied, the heat generated by the light source 20 is dissipated by the following heat dissipation path, that is, in sequence through the cathode wiring 111F provided on the front side of the heat dissipation base material 100, the heat dissipation base material 100, the reference potential wiring 113B provided on the back side of the heat dissipation base material 100, the reference potential wiring 13F provided on the front surface of the wiring substrate 10, the through-conductor 13V, and then through the reference potential wiring 13B provided on the back side of the wiring substrate 10.

[0145] Here, the reference potential wiring 113B provided on the back side of the heat dissipation base material 100 and the cathode wiring 111F provided on the front side of the heat dissipation base material 100 are provided so as to overlap with a overlapping width W1o in a plan view. Therefore, the heat dissipation path for heat to be conducted from the cathode wiring 111F to the reference potential wiring 113B becomes shorter. Furthermore, the reference potential wiring 113B provided on the back side of the heat dissipation base material 100 and the light source 20 are provided so as to overlap with a overlapping width W2o in a plan view. Therefore, the heat dissipation path for heat to be conducted from the light source 20 to the reference potential wiring 113B becomes further shorter. By these, the heat generated by the light source 20 becomes easy to dissipate. Therefore, the area of the cathode wiring 111B provided on the back side of the heat dissipation base material 100 is made smaller than the area of the cathode wiring 111F provided on the front side of the heat dissipation base material 100.

[0146] If a cathode wiring 111F is provided on the surface side of the heat dissipation substrate 100 and a reference potential wiring 113B is provided on the back side, heat is conducted from the cathode wiring 111F to the reference potential wiring 113B via the heat dissipation substrate 100 having a low thermal conductivity. Therefore, the reference potential wiring 113F and the cathode wiring 111F do not necessarily need to overlap in a top view. Similarly, the reference potential wiring 113F and the light source 20 do not necessarily need to overlap in a top view.

[0147] As described above, the heat generated by the light source 20 is dissipated to the reference potential wiring 13B provided on the back side of the wiring substrate 10 via the heat dissipation substrate 100 having a high thermal conductivity. Therefore, the heat generated by the light source 20 is more easily dissipated than in the case of heat dissipation via the wiring substrate 10 having a lower thermal conductivity than the heat dissipation substrate 100.

[0148] Next, a drive circuit through which a drive current for causing the VCSEL (light source 20) to emit light flows will be described.

[0149] The drive current reaches the anode electrode 218 of the VCSEL (light source 20) from the capacitor 70A via the anode wiring 112F of the heat dissipation substrate 100 and the bonding wire 23A. And the drive current reaches the MOS transistor 51 of the drive unit 50 from the cathode electrode 214 of the VCSEL (light source 20) via the cathode wiring 111F of the heat dissipation substrate 100, the through conductor 111V, the cathode wiring 111B, and the cathode wiring 11 of the wiring substrate 10 (refer to Figure 6 of (a) and Figure 6 of (b)). Next, the drive current returns to the capacitor 70A from the MOS transistor 51 of the drive unit 50 via the reference potential wiring 13B of the wiring substrate 10, the through conductor 13V, the reference potential wiring 13F, the reference potential wiring 113B of the heat dissipation substrate 100, the through conductor 113V, and the reference potential wiring 113F. The same applies to the capacitor 70B side.

[0150] Here, the shorter the distances between the capacitor 70A, the capacitor 70B and the VCSEL (light source 20) are, the shorter the drive circuit is. That is, the circuit inductance becomes smaller and the rise time of the light emission of the VCSEL becomes shorter. In the light-emitting device 4 to which the present embodiment is applied, the light source 20, the capacitor 70A, and the capacitor 70B are provided on the surface of the heat dissipation substrate 100, so the distances between the capacitor 70A, the capacitor 70B and the light source 20 are set short. In addition, the heat generation amounts of the capacitor 70A and the capacitor 70B are smaller than that of the light source 20. Therefore, even if the capacitor 70A and the capacitor 70B are provided on the surface side of the heat dissipation substrate 100, heat dissipation does not need to be considered. In addition, since the heat generation amount of the drive unit 50 is large, it is preferable that the drive unit 50 is not provided on the heat dissipation substrate 100.

[0151] Next, a light-emitting device 4' to which the present embodiment is not applied and shown for comparison will be described.

[0152] Figure 9 (a) of Figure 9 and (b) of Figure 9 are diagrams for explaining the light-emitting device 4' to which the present embodiment is not applied. Figure 9 (a) of Figure 9 is a plan view, and (b) of

[0153] is a cross-sectional view taken along line IXB-IXB of (a) of Figure 9 . In addition, in the light-emitting device 4', for components having the same functions as those of the light-emitting device 4, even if their shapes are different, the same reference numerals are used. Hereinafter, the description of the same parts as those of the light-emitting device 4 will be omitted, and different parts will be described.

[0154] In addition, in the light-emitting device 4', similarly to the light-emitting device 4, the center Ov of the light source 20 is provided in the heat dissipation substrate 100 so as to deviate toward the driving unit 50 side. In this way, the distance between the light source 20 and the driving unit 50 becomes shorter, bringing the light source 20 closer to the driving unit 50.

[0155] Figure 10 (a) to Figure 10 (c) of Figure 10 are diagrams for explaining the wirings provided on the wiring substrate 10 and the wirings provided on the heat dissipation substrate 100 in the light-emitting device 4' to which the present embodiment is not applied. Figure 10 (a) of Figure 10 is the wiring provided on the wiring substrate 10, (b) of

[0156] is the wiring provided on the surface of the heat dissipation substrate 100, and (c) of Figure 10 is the wiring provided on the back surface of the heat dissipation substrate 100. Figure 10In (a) thereof, the outer shape of the heat dissipation substrate 100 is indicated by a dash-dot line. Figure 10 In (a) thereof, the wirings provided on the front surface side of the wiring substrate 10 are indicated by solid lines, and the wirings provided on the back surface side of the wiring substrate 10 are indicated by dashed lines.

[0157] On the front surface side of the wiring substrate 10, a cathode wiring 11, an anode wiring 12, and a reference potential wiring 13F insulated from each other are provided.

[0158] The planar shape of the -x direction side of the cathode wiring 11 is a quadrilateral, and the end portion extending in the +x direction is connected to the drive unit 50. The quadrilateral portion on the -x direction side is connected to the cathode electrode 214 of the light source 20 via the heat dissipation substrate 100 (refer to Figure 9 (a) thereof and Figure 9 (b) thereof).

[0159] The anode wiring 12 is provided so as to surround three sides (-x direction side and ±y direction sides) of the cathode wiring 11. And, the portion extending in the -x direction is connected to the + side of the power supply 82. The anode wiring 12 is connected to the anode electrode 218 of the light source 20 via the heat dissipation substrate 100, the bonding wire 23A, and the bonding wire 23B.

[0160] The planar shapes of the two reference potential wirings 13F are quadrilaterals, and they are provided on the ±y directions of the anode wiring 12.

[0161] On the back surface side of the wiring substrate 10, a reference potential wiring 13B is provided. And, the two reference potential wirings 13F provided on the front surface of the wiring substrate 10 and the reference potential wiring 13B provided on the back surface are electrically connected through a conductive through-conductor 13V (refer to Figure 11 described later). Here, the reference potential wiring 13B is provided over the entire back surface of the wiring substrate 10.

[0162] Next, the wirings provided on the heat dissipation substrate 100 shown in Figure 10 (b) thereof and Figure 10 (c) thereof will be described.

[0163] As shown in Figure 10 (b) thereof, on the front surface side of the heat dissipation substrate 100, a cathode wiring 111F and an anode wiring 112F insulated from each other are provided. On the surface of the cathode wiring 111F, the cathode electrode 214 side of the light source 20 is mounted (refer to Figure 9 (b) thereof). The anode wiring 112F is provided so as to surround three sides (-x direction side and ±y direction sides) of the cathode wiring 111F. The anode wiring 112F is connected to the anode electrode 218 of the light source 20 through the bonding wire 23A and the bonding wire 23B on the ±y direction sides (refer to Figure 9 (a) thereof).

[0164] As shown Figure 10 in (c) of FIG. , on the back side of the heat dissipation substrate 100, a cathode wiring 111B and an anode wiring 112B insulated from each other are provided. The planar shapes of the cathode wiring 111B and the anode wiring 112B are the same as those of the cathode wiring 111F and the anode wiring 112F provided on the surface side of the heat dissipation substrate 100 shown in (b) of FIG. Figure 10 The cathode wiring 111F and the cathode wiring 111B are connected via a through conductor 111V. The anode wiring 112F and the anode wiring 112B are electrically connected through a through conductor 112V.

[0165] As described above, on the heat dissipation substrate 100 of the light emitting device 4', the reference potential wirings 113F and 113B provided on the heat dissipation substrate 100 of the light emitting device 4 are not provided.

[0166] FIG. is a diagram for further explaining the light emitting device 4' to which the present embodiment is not applied.

[0167] Figure 11 FIG. is a cross-sectional view taken along line XI-XI of the light emitting device 4' shown in (a) of FIG. Figure 11 FIG. is Figure 9 a cross-sectional view of the light emitting device 4' shown in (a) of FIG.

[0168] Through Figure 9 (a) and Figure 9 (b) of FIG., Figure 10 (a) to Figure 10 (c) and Figure 11 FIG., the electrical connection relationship in the light emitting device 4' to which the present embodiment is not applied is described.

[0169] As described above, a heat dissipation substrate 100 is provided on the surface of the wiring substrate 10, and a light source 20 is provided on the surface of the heat dissipation substrate 100. The capacitors 70A and 70B are provided on the surface of the wiring substrate 10.

[0170] The cathode wiring 11 provided on the surface side of the wiring substrate 10 is connected to the driving unit 50 (see (a) and (b) of FIG. Figure 9 (a) and Figure 9 (b) of FIG.). The cathode wiring 11 is connected to the cathode wiring 111B provided on the back side of the heat dissipation substrate 100 by solder or the like. The cathode wiring 111B is connected to the cathode wiring 111F provided on the surface of the heat dissipation substrate 100 via a through conductor 111V provided in the heat dissipation substrate 100. Further, the light source 20 is mounted on the cathode wiring 111F and is connected to the cathode electrode 214 of the light source 20 (see (b) of FIG. Figure 9 (b) and Figure 11 FIG.).

[0171] The anode wiring 12 provided on the surface side of the wiring substrate 10 is connected to the anode wiring 112B provided on the back side of the heat dissipation substrate 100 by solder or the like. The anode wiring 112B is connected to the anode wiring 112F provided on the surface side of the heat dissipation substrate 100 via the through-conductor 112V provided in the heat dissipation substrate 100. Further, the anode wiring 112F is connected to the anode electrode 218 of the light source 20 via the bonding wire 23A and the bonding wire 23B (refer to Figure 9 's (a), Figure 11 ).

[0172] The reference potential wiring 13F provided on the surface side of the wiring substrate 10 is connected to the reference potential wiring 13B provided on the back side of the wiring substrate 10 via the through-conductor 13V (refer to Figure 9 's (b), Figure 11 ). Further, on the wiring substrate 10, the capacitors 70A and 70B are disposed between the reference potential wiring 13F and the anode wiring 12. That is, as shown in Figure 10 's (a), the capacitor 70A is provided and electrically connected between the reference potential wiring 13F and the anode wiring 12 on the +y side of the wiring substrate 10. Similarly, the capacitor 70B is provided and electrically connected between the reference potential wiring 13F and the anode wiring 12 on the -y side of the wiring substrate 10. Similarly, the capacitor 70B is provided and electrically connected between the reference potential wiring 113F on the +y side in the two reference potential wirings 113F and the anode wiring 112F (refer to Figure 9 's (a), Figure 11 ).

[0173] Next, the heat dissipation path of the heat generated by the light source 20 in the light-emitting device 4' will be described by Figure 11 .

[0174] As described above, the heat generated by the light source 20 is conducted through the following path, that is, from the cathode electrode 214 of the light source 20 to the cathode wiring 111F provided on the heat dissipation substrate 100. And the heat is conducted through the heat dissipation substrate 100 to the cathode wiring 111B and the anode wiring 112B provided on the back of the heat dissipation substrate 100. Further, the heat is conducted from the cathode wiring 111B and the anode wiring 112B to the cathode wiring 11 and the anode wiring 12 provided on the surface side of the wiring substrate 10. However, as described above, the thermal conductivity of the wiring substrate 10 is smaller than that of metals such as copper (Cu). Therefore, the heat will be conducted in the anode wiring 12 on the surface side of the wiring substrate 10 and conducted to the reference potential wiring 13F via the capacitors 70A and 70B (the path β1 shown in Figure 11 ). And the heat is conducted in the reference potential wiring 13F to the reference potential wiring 13B provided on the back side of the wiring substrate 10 via the through-conductor 13V (the path β2 shown in Figure 11 ).

[0175] As described above, in the light-emitting device 4', the heat generated by the light source 20 is dissipated through the following heat dissipation path. That is, it sequentially passes through the cathode wiring 111F provided on the surface side of the heat dissipation substrate 100, the heat dissipation substrate 100, the anode wiring 112F provided on the back side of the heat dissipation substrate 100, the anode wiring 112B provided on the surface side of the wiring substrate 10, the capacitors 70A and 70B, the reference potential wiring 13F, the through-conductor 13V, and via the reference potential wiring 13B provided on the back side of the wiring substrate 10. That is, in the light-emitting device 4', although the heat dissipation substrate 100 with a high thermal conductivity is used, there is no heat dissipation path that easily conducts heat to the reference potential wiring 13B provided on the back side of the wiring substrate 10. Therefore, the conduction of heat from the light source 20 is hindered.

[0176] That is, in the light-emitting device 4 to which the present embodiment is applied, by providing the reference potential wiring 113F and the reference potential wiring 113B on the heat dissipation substrate 100, a heat dissipation path is provided through which the heat generated by the light source 20 is conducted to the reference potential wiring 13B provided on the back side of the wiring substrate 10 via the reference potential wiring 13F provided on the surface side of the wiring substrate 10 and the through-conductor 13V provided on the wiring substrate 10.

[0177] In contrast, in the light-emitting device 4', neither the reference potential wiring 113F nor the reference potential wiring 113B is provided on the heat dissipation substrate 100. Therefore, it is difficult to form a heat dissipation path through which the heat generated by the light source 20 is conducted to the reference potential wiring 13B provided on the back side of the wiring substrate 10.

[0178] Next, the drive circuit through which the drive current for causing the light source 20 to emit light flows in the light-emitting device 4' to which the present embodiment is not applied will be described.

[0179] The drive current reaches the anode electrode 218 of the light source 20 (VCSEL) from the capacitor 70A via the anode wiring 12 of the wiring substrate 10, the anode wiring 112B of the heat dissipation substrate 100, the through-conductor 112V, the anode wiring 112F, and the bonding wire 23A. And the drive current reaches the MOS transistor 51 of the drive unit 50 from the cathode electrode 214 of the light source 20 (VCSEL) via the cathode wiring 111F of the heat dissipation substrate 100, the through-conductor 111V, the cathode wiring 111B, and the cathode wiring 11 of the wiring substrate 10 (refer to Figure 6 of (a) and Figure 6 of (b)). Next, the drive current returns from the MOS transistor 51 of the drive unit 50 to the capacitor 70A via the reference potential wiring 13B of the wiring substrate 10, the through-conductor 13V, and the reference potential wiring 13F. The same applies to the capacitor 70B side.

[0180] In the light-emitting device 4', the capacitors 70A and 70B are provided on the surface of the wiring substrate 10, and the light source 20 is provided on the surface of the heat dissipation substrate 100. Therefore, the distance between the capacitors 70A, 70B and the light source 20 is larger than that of the aforementioned light-emitting device 4. Therefore, even if the light source 20 is deviated toward the drive unit 50 side in the heat dissipation substrate 100 to bring the light source 20 closer to the drive unit 50 in the light-emitting device 4', the circuit inductance of the drive circuit will increase. Therefore, in the light-emitting device 4', the rise time of the light emission of the VCSEL is longer than that of the light-emitting device 4.

[0181] That is, in the light-emitting device 4 to which the present embodiment is applied, the light source 20, the capacitors 70A, and 70B are provided on the surface of the heat dissipation substrate 100. Therefore, the distance between the capacitors 70A, 70B and the light source 20 is set short. Thereby, the rise time of the light emission of the light source 20 becomes short. In addition, at least a part of one or both of the capacitors 70A and 70B may be embedded in the heat dissipation substrate 100.

[0182] As described above, in the light-emitting device 4 to which the present embodiment is applied, by providing the reference potential wiring 113F and the reference potential wiring 113B on the heat dissipation substrate 100, a heat dissipation path is provided through which the heat generated by the light source 20 is conducted to the reference potential wiring 13B provided on the back side of the wiring substrate 10 via the reference potential wiring 13F provided on the surface side of the wiring substrate 10 and the through-conductor 13V provided on the wiring substrate 10. In addition, as Figure 8 shown, as long as the heat generated by the light source 20 is conducted to the reference potential wiring 113B provided on the back side of the heat dissipation substrate 100, it is sufficient to provide the reference potential wiring 113B on the back side of the heat dissipation substrate 100.

[0183] In addition, in the light-emitting device 4 to which the present embodiment is applied, the heat dissipation substrate 100 and the drive unit 50 are provided on the surface of the wiring substrate 10, but the circuit substrate provided with the heat dissipation substrate 100 and the circuit substrate provided with the drive unit 50 may be independently formed, and they are connected by a flexible flat cable (FFC) or a flexible printed circuit (FPC).

[0184] Furthermore, in the light-emitting device 4 to which the present embodiment is applied, the heat dissipation substrate 100 may be made of silicon (Si) as a semiconductor substrate, and the drive unit 50 may be configured as a drive integrated circuit (IC) by silicon (Si), and a capacitor 70 is provided in this drive IC. In addition, flip chip connection may be performed on the light source 20 including the VCSEL. Thereby, compared with the case where the drive unit 50 and the heat dissipation substrate 100 are provided independently, the space for arranging the light-emitting device is reduced.

[0185] Moreover, in the light-emitting device 4 to which the present embodiment is applied, as an example of the optical member, a light diffusion member 30 is used, and the light diffusion member 30 changes the divergence angle of the incident light in an enlarged manner by diffusion and emits the light. The optical member may also be a diffractive optical element (DOE) or the like that emits the light by changing the direction of the light to a direction different from the incident direction. Moreover, the optical member may also be a transparent member such as a condenser lens, a microlens, or a protective cover.

Claims

1. A light-emitting device, comprising: A first substrate; A laser section provided on the first substrate; Two capacitor elements provided on the first substrate to supply a driving current to the laser section; A wiring substrate including a second substrate having a lower thermal conductivity than the first substrate and carrying the first substrate; A driving section mounted on the wiring substrate to drive the laser section; and A wiring connecting the driving section provided on the wiring substrate and the laser section, and extending in one direction from a region that coincides with the laser section in a top view to a region that coincides with the driving section in a top view, The two capacitor elements are arranged to sandwich the laser section in a direction perpendicular to the one direction.

2. The light-emitting device according to claim 1, wherein The planar shape of the first substrate has a short side direction and a long side direction, The driving section is mounted in such a manner that at least a part thereof coincides with an extension line of the short side direction and within a width range in the long side direction.

3. The light-emitting device according to claim 2, wherein The driving section is mounted in such a manner that it is entirely included within an extension line of the short side direction and within a width range in the long side direction.

4. The light-emitting device according to claim 2 or 3, wherein The laser section and the capacitor elements are arranged side by side in the long side direction.

5. The light-emitting device according to any one of claims 1 to 3, wherein The laser section is provided in the first substrate so as to be offset toward the non-driving section side.

6. The light-emitting device according to claim 5, wherein The capacitor elements are provided in the first substrate so as to be offset toward the non-driving section side.

7. The light-emitting device according to any one of claims 1 to 3, wherein The laser section includes a surface-emitting laser element array.

8. The light-emitting device according to any one of claims 1 to 3, wherein The first substrate includes a ceramic material.

9. The light-emitting device according to any one of claims 1 to 3, wherein The first substrate is a semiconductor substrate, A driving section for driving the laser section is formed within the semiconductor substrate.

10. The light-emitting device according to any one of claims 1 to 3, which Has an optical member that changes at least one of the direction and the divergence angle of the light emitted from the laser section.

11. An optical device, comprising: The light-emitting device according to any one of claims 1 to 10; And A light-receiving section that receives light emitted from the laser section included in the light-emitting device and reflected by a measurement object, The light-receiving section outputs a signal corresponding to the time from when the light is emitted from the laser section until it is received by the light-receiving section.

12. A measuring device, comprising: The optical device according to claim 11; And A three-dimensional shape determination section that determines the three-dimensional shape of the measurement object based on the light emitted from the laser section included in the optical device, reflected by the measurement object, and received by the light-receiving section included in the optical device, The measuring device measures the three-dimensional shape of the measurement object.

13. A light-emitting device, comprising: An insulating substrate having a thermal conductivity of 10 W / m·K or more; A laser section provided on the substrate; Two capacitor elements, provided on the substrate, for supplying drive current to the laser unit; and A wiring, connecting the laser unit and the drive unit, the drive unit driving the laser unit and provided outside the substrate, The two capacitor elements are arranged sandwiching the laser unit in a direction perpendicular to the extending direction of the wiring that connects the laser unit and the drive unit provided outside the substrate for driving the laser unit.

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