Light emitter, light emitting device, optical device, and information processing apparatus

A light emitter includes: a substrate; a driving section provided on the substrate; a light source that is provided on the substrate and is driven by the driving section; a cover section through which light emitted from the light source is transmitted and that is disposed in an optical axial direction of the light source; and a support section that is provided on a part of the substrate excluding a part between the driving section and the light source and supports the cover section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2019-034456 filed Feb. 27, 2019.

BACKGROUND

(i) Technical Field

The present disclosure relates to a light emitter, a light emitting device, an optical device, and an information processing apparatus.

(ii) Related Art

JP-A-2018-32654 discloses that a vertical resonator-type light emitting element module including plural vertical resonator type light emitting elements arranged on a plane has a joining surface disposed in a region between laser beams from the vertical resonator-type light emitting elements adjacent to each other on a substrate and located on an emitting direction side of the laser beam; and an outer wall facing a beam space through which the laser beam is transmitted.

Incidentally, in order to improve the measurement accuracy, it is necessary for a light source for performing three-dimensional sensing by the time of flight (ToF) method to turn on and off a large current at a higher speed. Therefore, when the wall that supports a diffusion plate that diffuses light from the light source is provided between a driving section and the light source, it is difficult to make the driving section and the light source close to each other because the wall becomes an obstacle. Therefore, it is difficult to reduce the wiring inductance between the driving section and the light source, and the light source becomes a constraint in a case of turning on and off the light source at a high speed.

SUMMARY

Aspects of non-limiting embodiments of the present disclosure relate to providing a light emitter in which a light source and a driving section can be set close to each other as compared with a case where a wall that supports a diffusion plate is also provided between the light source and the driving section, similar to walls at other parts.

According to an aspect of the present disclosure, there is provided a light emitter including: a substrate; a driving section provided on the substrate; a light source that is provided on the substrate and is driven by the driving section; a cover section through which light emitted from the light source is transmitted and that is disposed in an optical axial direction of the light source; and a support section that is provided on a part of the substrate excluding a part between the driving section and the light source and supports the cover section.

DETAILED DESCRIPTION

Hereinafter, a description will be given in detail of exemplary embodiments of the disclosure with reference to the attached drawings.

The information processing apparatus identifies whether or not the user who accessed the information processing apparatus is allowed to access, and only in a case where the user is authenticated as a user who is allowed to access, the use of the apparatus (information processing apparatus) is allowed in many cases. So far, a method of authenticating the user using passwords, fingerprint, iris or the like, has been adapted. In recent years, it has been required to adapt an authentication method having higher security. As this method, authentication using a three-dimensional image, such as the shape of the face of the user or the like, is performed.

Here, the information processing apparatus is described as a portable information processing terminal as an example, and is described as an apparatus that authenticates the user by recognizing the shape of the face captured as a three-dimensional image. In addition, the information processing apparatus may be applied to an information processing apparatus, such as a personal computer (PC), in addition to the portable information terminal.

Furthermore, the configuration, functions, methods, and the like, which are described in the present exemplary embodiment, may also be applied to the recognition of the three-dimensional shape in addition to the recognition of the shape of the face. In other words, the present exemplary embodiment may also be applied to the recognition of the shape of the object other than the face. In addition, the distance to a measurement target does not matter.

First Exemplary Embodiment

Information Processing Apparatus1

FIG.1is a view illustrating an example of an information processing apparatus1. As described above, the information processing apparatus1is a portable information processing terminal as an example.

The information processing apparatus1includes: a user interface portion (hereinafter, referred to as UI portion)2; and an optical device3that acquires the three-dimensional image. The UI portion2includes, for example, a display device that displays information to the user and an input device with which an instruction for information processing is input by an operation of the user, which are integrated with each other. The display device is, for example, a liquid crystal display or an organic EL display, and the input device is, for example, a touch panel.

The optical device3includes a light emitter4and a three-dimensional sensor (hereinafter, referred to as 3D sensor)5. The light emitter4emits light toward the measurement target whose three-dimensional image is to be acquired, specifically, the face in the example described here. The 3D sensor5acquires the light that is emitted from the light emitter4, is reflected by the face, and has returned. Here, the three-dimensional image of the face is acquired based on a so-called time of flight (ToF) method using the flight time of the light. Hereinafter, even in a case of acquiring the three-dimensional image of the face, the face will be referred to as the measurement target. In addition, a three-dimensional image other than the face may be acquired. Acquiring the three-dimensional image, is referred to as 3D sensing in some cases.

In addition, the information processing apparatus1is configured as a computer including CPU, ROM, RAM and the like. Further, the ROM includes a non-volatile rewritable memory, such as a flash memory. In addition, the accumulated programs or constants in the ROM are developed in the RAM, and by executing the CPU, the information processing apparatus1is operated and various types of information processing are executed.

FIG.2is a block diagram illustrating a configuration of the information processing apparatus1.

The information processing apparatus1includes the above-described optical device3, an optical device controller8, and a system controller9. The optical device controller8controls the optical device3. In addition, the optical device controller8includes a shape specifying section81. The system controller9controls the entire information processing apparatus1as a system. Further, the system controller9includes an authentication processing section91. In addition, the UI portion2, a speaker92, a two-dimensional camera (inFIG.2, referred to as 2D camera)93and the like are connected to the system controller9. Further, the 3D sensor5is an example of a light receiving section, and the optical device controller8is an example of a controller.

Hereinafter, a more detailed description will be given.

The light emitter4includes a substrate10, a light source20, a diffusion plate30, a light amount monitoring light receiving element (referred as PD inFIG.2and the following drawings)40, a driving section50, and a support section60, and a capacitor70. Here, two capacitors70are shown as an example, and in a case of distinguishing the two capacitors, the capacitors70will be referred to as capacitors70A and70B. The light source20, the PD40, the driving section50, the capacitor70are provided on the substrate10. In addition, the diffusion plate30is held by the support section60with a predetermined distance from the substrate10, and is provided to cover the light source20and the PD40. The diffusion plate30is an example of a cover section.

In addition, on the substrate10, the 3D sensor5, a resistive element6, and a capacitor7are mounted in addition to the above-described members. The resistive element6and the capacitor7are provided for operating the driving section50or the 3D sensor5. In addition, one resistive element6and one capacitor7are described respectively, but plural resistive elements6and capacitors7may be mounted. Further, inFIG.1, the 3D sensor5is also provided on the substrate10, but the 3D sensor5may not be provided on the substrate10.

The light source20in the light emitter4includes plural light emitting elements arranged two-dimensionally in the form of a light emitting element array. The light emitting element is a vertical resonator surface light emitting laser element VCSEL (Vertical Cavity Surface Emitting Laser) as an example. Hereinafter, the light emitting element will be described as a vertical resonator surface light emitting laser element VCSEL. The vertical resonator surface light emitting laser element VCSEL will be referred to as VCSEL. The light source20emits the light in a direction perpendicular to the substrate10. In a case of performing the three-dimensional sensing by the ToF method, it is required for the light source20to emit pulsed light that is equal to or larger than 100 MHz and has a rise time of 1 ns or less, for example, by the driving section50. Hereinafter, the emitted pulsed light is referred to as emitted light pulse. In addition, in a case where the face authentication is an example, the distance by which the light is emitted is from approximately 10 cm to approximately 1 m. Further, a range for measuring the 3D shape of the measurement target is approximately 1 square meters. Hereinafter, the distance by which the light is emitted is referred to as a measurement distance, and the range for measuring the 3D shape of the measurement target is referred to as a measurement range or an irradiation range. Further, a surface virtually provided in the measurement range or the irradiation range is referred to as an irradiation surface.

The substrate10, the diffusion plate30, the PD40, the driving section50, the support section60, and the capacitor70in the light emitter4will be described later. In addition, the light source20will be described in detail later.

The 3D sensor5includes plural light receiving cells. For example, each of the light receiving cells is configured to receive the reflected light from the measurement target with respect to the emission light pulse from the light source20, and accumulate electric charges that correspond to the time until the reflection light is received for each light receiving cell. Hereinafter, the received reflected light will be referred to as light receiving pulse. The 3D sensor5is configured as a device of a CMOS structure in which each light receiving cell includes two gates and a charge accumulation section corresponding to the two gates. In addition, by adding the pulse alternately to the two gates, the generated photoelectrons are transferred to any of the two charge accumulation sections at a high speed. In the two charge accumulation sections, electric charges that correspond to a phase difference between the emission light pulse and the light receiving pulse are accumulated. Further, the 3D sensor5outputs a digital value that corresponds to the phase difference between the emission light pulse and the light receiving pulse for each light receiving cell, as a signal, via an AD converter. In other words, the 3D sensor5outputs a signal that corresponds to the time until the light is received by the 3D sensor5after the light is emitted from the light source20. In addition, the AD converter may be provided in the 3D sensor5or may be provided outside the 3D sensor5.

The shape specifying section81of the optical device controller8acquires a digital value obtained from the 3D sensor5in each light receiving cell, and calculates the distance to the measurement target for each light receiving cell. In addition, based on the calculated distance, the 3D shape of the measurement target is specified.

The authentication processing section91of the system controller9performs authentication processing related to the use of the information processing apparatus1in a case where the 3D shape of the measurement target specified by the shape specifying section81has the 3D shapes accumulated in advance in the ROM or the like. In addition, the authentication processing related to the use of the information processing apparatus1, as an example, is processing of determining whether or not the use of the information processing apparatus1which is the apparatus is allowed. For example, in a case where it is determined that the 3D shape of the face which is the measurement target matches the face shape stored in a storage member, such as the ROM, the use of the information processing apparatus1including various applications and the like provided by the information processing apparatus1is allowed.

The above-described shape specifying section81and the authentication processing section91include, for example, a program. Alternatively, the shape specifying section81and the authentication processing section91may include an integrated circuit, such as ASIC or FPGA. Furthermore, the shape specifying section81and the authentication processing section91may include software, such as a program, and an integrated circuit, such as ASIC.

InFIG.2, the optical device3, the optical device controller8, and the system controller9are illustrated respectively, but the system controller9may include the optical device controller8. In addition, the optical device3may include the optical device controller8. Furthermore, the optical device3, the optical device controller8, and the system controller9may be integrally formed.

Before description of the light emitter4, the light source20, the diffusion plate30, the PD40, the driving section50, and the capacitor70that form the light emitter4will be described.

Configuration of Light Source20

FIG.3is a plan view of the light source20. The light source20has a configuration in which plural VCSELs are arranged in a two-dimensional array. A rightward direction of a paper surface is an x direction, and an upward direction of the paper surface is a y direction. A direction orthogonal to the x and y directions counterclockwisely is a z direction.

The VCSEL is a light emitting element which is provided with an active region that is a light emitting region between a lower multilayer film reflecting mirror and an upper multilayer film reflecting mirror which are stacked on a semiconductor substrate200(refer toFIG.4which will be described later), and which emits the laser light in a direction perpendicular to the semiconductor substrate. Therefore, it is easy to form a two-dimensional array. The number of VCSEL in the light source20is, for example, 100 to 1000. In addition, the plural VCSELs are connected to each other in parallel, and are driven in parallel. Further, the above number of VCSELs is an example, and the number of VCSELs may be set in accordance with the measurement distance and measurement range.

On the surface of the light source20, a common anode electrode218(refer toFIG.4which will be described later) is provided in the plural VCSELs. In addition, the anode electrode218is connected to an anode wiring11provided on the substrate10via a bonding wire21. Further, a cathode electrode214(refer toFIG.4which will be described later) is provided on a rear surface of the light source20and bonded to a cathode wiring12, in which the cathode electrode214is provided on the substrate10, with a conductive adhesive or the like. The conductive adhesive is, for example, a silver paste.

Structure of VCSEL

FIG.4is a view for illustrating a sectional structure of one VCSEL in the light source20. The VCSEL is a VCSEL having a λ, resonator structure. The upward direction of the paper surface is the z direction.

The VCSEL has a configuration in which an n-type lower part distribution Bragg type reflecting mirror (DBR: Distributed Bragg Reflector)202in which AlGaAs layers having different Al compositions alternately overlap each other, an active region206including a quantum well layer sandwiched between an upper spacer layer and a lower spacer layer, and a p-type upper distribution Bragg type reflecting mirror208in which AlGaAs layers having different Al compositions alternately overlap each other, are stacked on the semiconductor substrate200, such as an n-type GaAs. Hereinafter, the distribution Bragg reflecting mirror will be referred to as DBR.

The n-type lower DBR202is a stacked body in which an Al0.9Ga0.1As layer and a GaAs layer are made into one pair, the thickness of each layer is λ/4nr(while λ, is an oscillation wavelength and nris a refractive index of a medium), and the layers are stacked alternately in 40 cycles. After doping with silicon, which is an n-type impurity, the carrier concentration is, for example, 3×1018cm−3.

The active region206has a configuration in which the lower spacer layer, the quantum well active layer, and the upper spacer layer are stacked. For example, the lower spacer layer is an undoped Al0.6Ga0.4As 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 Al0.6Ga0.4As layer.

The p-type upper DBR208is a stacked body in which a p-type Al0.9Ga0.1As layer and a GaAs layer are made into one pair, the thickness of each layer is λ/4nr, and the layers are stacked alternately in 29 cycles. The carrier concentration after doping with carbon which is a p-type impurity is, for example, 3×1018cm−3. Preferably, on the uppermost layer of the upper DBR208, a contact layer made of p-type GaAs is formed, and on the lowermost or on the inside of the upper DBR208, a current constriction layer210of p-type AlAs is formed.

By etching the semiconductor layer stacked from the upper DBR208until reaching the lower DBR202, a cylindrical mesa M is formed on the semiconductor substrate200. Accordingly, the current constriction layer210is exposed on the side surface of the mesa M. By an oxidation step, on the current constriction layer210, an oxidized region210A oxidized from the side surface of the mesa M and a conductive region210B surrounded by the oxidized region210A are formed. In addition, in the oxidation step, since an AlAs layer has a high oxidation speed than that of the AlGaAs layer and the oxidized region210A is oxidized substantially at the same speed from the side surface of the mesa M inward, a planar shape parallel to the semiconductor substrate200of the conductive region210B has a shape reflecting the outer shape of the mesa M, that is, a circular shape, and the center thereof substantially matches an axial direction (one-dot chain line) of the mesa M. In addition, in the exemplary embodiment, the mesa M has a columnar structure.

On the uppermost layer of the mesa M, an annular p-side electrode212made of metal in which Ti/Au and the like are stacked is formed. The p-side electrode212is in ohmic contact with the contact layer provided on the upper DBR208. The inner side of the annular p-side electrode212is a light emission port212A through which the laser light is emitted to the outside. In other words, in the VCSEL, the light is emitted in a direction perpendicular to the semiconductor substrate200, and the axial direction of the mesa M is the optical axis. Furthermore, on the rear surface of the semiconductor substrate200, the cathode electrode214is formed as an n-side electrode. In addition, the surface of the upper DBR208on the inside of the p-side electrode212is a light emitting surface.

In addition, except for the part to which the anode electrode (anode electrode218which will be described later) of the p-side electrode212is connected and the light emission port212A, an insulating layer216is provided so as to cover the surface of the mesa M. Further, except for the light emission port212A, the anode electrode218is provided so as to be in ohmic contact with the p-side electrode212. In addition, the anode electrode218is provided in common to the plural VCSELs. In other words, each of the p-side electrodes212is connected to the plural VCSELs that form the light source20by the anode electrode218in parallel.

In addition, the VCSEL may oscillate in a single transverse mode, and may oscillate in a multiple transverse mode (multi-mode). As an example, the light output of one of the VCSEL is 4 mW to 8 mW.

A VCSEL group22of an end portion in the x direction is a VCSEL positioned on the driving section50side illustrated inFIGS.7A and7Bwhich will be described later.

Configuration of Diffusion Plate30

FIGS.5A and5Bare views for illustrating an example of the diffusion plate30.FIG.5Ais a plan view, andFIG.5Bis a sectional view taken along line VB-VB ofFIG.5A. InFIG.5A, a rightward direction of the paper surface is the x direction, and an upward direction of the paper surface is the y direction. A direction orthogonal to the x and y directions counterclockwisely is a z direction. Accordingly, inFIG.5B, a rightward direction of the paper surface is the x direction, and an upward direction of the paper surface is the z direction.

As illustrated inFIG.5B, the diffusion plate30has both surfaces parallel to each other, and includes a resin layer32on which irregularities for diffusing the light to one surface of a flat glass base material31, here, a −z direction side which is a rear surface, are formed. The diffusion plate30further spreads a spread angle of light incident from the VCSEL of the light source20and emits the light. In other words, the irregularities formed on the resin layer32of the diffusion plate30, refract or scatter the light, and make a spread angle β of the emitted light greater than a spread angle α of the incident light. In other words, as illustrated inFIGS.5A and5B, the spread angle β of the light emitted from the diffusion plate30being transmitted through the diffusion plate30becomes greater than the spread angle α of the light emitted from the VCSEL (α<β). Therefore, when the diffusion plate30is used, the area of the surface irradiated with the light emitted from the light source20is larger than when the diffusion plate30is not used. Further, the light density on the irradiated surface decreases. In addition, the light density refers to an irradiance per unit area, and the spread angles α and β are a full width at half maximum (FWHM).

Further, the diffusion plate30has, for example, a square planar shape, a width Wxin the x direction and a longitudinal width Wyin the y direction are 1 mm to 10 mm, and a thickness tdin the z direction is 0.1 mm to 1 mm. In addition, the end portion in the x direction is an end portion33of the diffusion plate30. As will be described inFIGS.7A and7Bwhich will be described later, the end portion33is the driving section50side. In addition, the planar shape of the diffusion plate30may be other shapes, such as a polygonal shape or a circular shape. Further, in a case of the size and shape described above, in particular, a light diffusing member that is appropriate for the face authentication of the portable information terminal or the measurements of relatively short distances which are approximately several meters, is provided.

The PD40is a photodiode that is made from silicon or the like for outputting electric signals that correspond to the amount of light received by it (hereinafter, referred to as the amount of received light). The PD40is disposed to receive the light emitted from the light source20and reflected by the rear surface (a surface in the −z direction inFIG.7Bwhich will be described later) of the diffusion plate30. The light source20is controlled to maintain the predetermined light amount and emit the light based on the amount of light received by the PD40. In other words, as will be described later, the optical device controller8monitors the amount of light received by the PD40, controls the driving section50, and controls the light amount emitted from the light source20.

In a case where it is desired to drive the light source20at a higher speed, it is preferable to perform low side driving. The low side driving indicates a configuration in which driving elements, such as a MOS transistor, is positioned on the downstream side of a current path with respect to a driving target, such as a VCSEL. Conversely, the configuration in which the driving element is positioned on the upstream side is referred to as high side driving.

FIG.6is a view illustrating an example of an equivalent circuit for driving the light source20by the low side driving. InFIG.6, the VCSEL of the light source20, the driving section50, the capacitor70, a power source82, the PD40, and a detecting resistive element41for detecting a current that flows through the PD40are illustrated. In addition, the capacitors70A and70B which are referred to inFIG.2, are connected to the power source82in parallel. Accordingly, the capacitors70A and70B are not divided and distinguished from each other and are referred to as the capacitor70.

The power source82is provided in the optical device controller8illustrated inFIG.2. The power source82generates a DC voltage while a +side is a power source potential and a −side is a ground potential. The power source potential is supplied to a power source line83, and the ground potential is supplied to a ground line84.

The light source20has a configuration in which the plural VCSELs are connected to each other in parallel as described above. The anode electrode218(refer toFIG.4) of the VCSEL is connected to the power source line83via the anode wiring11provided on the substrate10.

The driving section50includes an n-channel MOS transistor51and a signal generating circuit52to turn on and off the MOS transistor51. The drain of the MOS transistor51is connected to the cathode electrode214(refer toFIG.4) of the VCSEL via the cathode wiring12provided on the substrate10. The source of the MOS transistor51is connected to the ground line84. In addition, the gate of the MOS transistor51is connected to the signal generating circuit52. In other words, the VCSEL of the light source20and the MOS transistor51of the driving section50are connected to each other in series between the power source line83and the ground line84. The signal generating circuit52generates a signal of “H level” for turning on the MOS transistor51and a signal of “L level” for turning off the MOS transistor51, by the control of the optical device controller8.

In the capacitor70, one terminal is connected to the power source line83, and the other terminal is connected to the ground line84. In addition, the capacitor70includes, for example, an electrolytic capacitor or a ceramic capacitor.

In the PD40, the cathode is connected to the power source line83, and the anode is connected to one terminal of the detecting resistive element41. In addition, the other terminal of the detecting resistive element41is connected to the ground line84. In other words, the PD40and the detecting resistive element41are connected to each other in series between the power source line83and the ground line84. Further, an output terminal42which is a connection point between the PD40and the detecting resistive element41is connected to the optical device controller8.

Next, a driving method of the light source20which is the low side driving will be described.

First, the signal generated by the signal generating circuit52in the driving section50is “L level”. In this case, the MOS transistor51is turned off. In other words, the current does not flow between the source and the drain of the MOS transistor51. Accordingly, the current does not flow to the VCSEL which are connected to each other in series. The VCSEL is a light non-emitting state.

At this time, the capacitor70is charged by the power source82. In other words, one terminal of the capacitor70is the power source potential and the other terminal is the ground potential. In the capacitor70, the electric charges determined by the capacity, the power source voltage (power source potential−ground potential), and the time, are accumulated.

Next, when the signal generated by the signal generating circuit52in the driving section50is “H level”, the MOS transistor51is shifted from OFF to ON. Then, the electric charges accumulated in the capacitor70flow (being discharged) to the MOS transistor51and the VCSEL connected to each other in series, the VCSEL emits the light.

In addition, when the signal generated by the signal generating circuit52in the driving section50is “L level”, the MOS transistor51is shifted from ON to OFF. Accordingly, the light emission of the VCSEL is stopped. Then, the accumulation of the electric charges in the capacitor70is resumed by the power source82.

As described above, each time the signal output from the signal generating circuit52shifts to “L level” and “H level”, the light non-emission which is the stop of the light emission of the VCSEL and the light emission are repeated. In other words, the light pulse from the VCSEL is emitted.

In addition, without providing the capacitor70, the electric charges (current) may be directly supplied from the power source82to the VCSEL, but by accumulating the electric charges in the capacitor70, discharging the accumulated electric charges by the switching of the MOS transistor51, and rapidly supplying the current to the VCSEL, the rise time of the light emission of the VCSEL is shortened. Furthermore, when the distance between the light source20and the driving section50is reduced so that the inductance of the wiring is lowered, the light source20can be turned on and off at a high speed. In addition, the distance between the light source20and the driving section50may preferably be equal to or less than 1 mm.

The PD40is connected in a reverse direction via the detecting resistive element41between the power source line83and the ground line84. Therefore, in a state where the light is not emitted, the current does not flow. When the PD40receives a part of the light reflected by the diffusion plate30in the emitted light of the VCSEL, the current that corresponds to the amount of received light flows in the PD40. Accordingly, the current that flows through the PD40is measured by the voltage of the output terminal42, and the light intensity of the light source20is detected. Here, the optical device controller8performs the control such that the light intensity of the light source20is a predetermined light intensity according to the amount of light received by the PD40. In other words, in a case where the light intensity of the light source20is lower than the predetermined light intensity, the optical device controller8increases the amount of electric charges accumulated in the capacitor70by increasing the power source potential of the power source82, and increases the current that flows to the VCSEL. Meanwhile, in a case where the light intensity of the light source20is higher than the predetermined light intensity, by decreasing the power source potential of the power source82, the optical device controller8reduces the amount of electric charges accumulated in the capacitor70, and reduces the current that flows to the VCSEL. In this manner, the light intensity of the light source20is controlled.

Further, in a case where the amount of light receive by the PD40has been extremely decreased, there is a concern that the light emitted from the light source20is directly emitted to the outside, as the diffusion plate30is come off or damaged. In such a case, the optical device controller8reduces the light intensity of the light source20. For example, the emission of the light from the light source20, that is, the irradiation of the measurement target with the light, is stopped.

In addition, the substrate10is, for example, in the form of a multilayer substrate having three layers. In other words, the substrate10includes a first conductive layer, a second conductive layer, and a third conductive layer from the side on which the light source20or the driving section50are mounted. In addition, between the first conductive layer and the second conductive layer and between the second conductive layer and the third conductive layer, the insulating layer is provided. For example, the third conductive layer is the power source line83and the second conductive layer is the ground line84. In addition, the first conductive layer forms a circuit pattern of a terminal or the like to which the anode wiring11of the light source20, the cathode wiring12, the PD40, the detecting resistive element41, the capacitor70(capacitors70A and70B) and the like are connected. The first conductive layer, the second conductive layer, and the third conductive layer are made of metal, such as copper (Cu) or silver (Ag) or a conductive material, such as a conductive paste containing the metal. The insulating layer is made of, for example, an epoxy resin or a ceramic.

The power source line83of the third conductive layer is connected to the anode wiring11provided on the first conductive layer through the via, the terminal to which the power source line83of the capacitor70is connected, the terminal to which the cathode of the PD40is connected, and the like, through the via. Similarly, the ground line84of the second conductive layer is connected to the terminal to which the source of the MOS transistor51of the driving section50is connected, the terminal to which the ground line84of the detecting resistive element41is connected, and the like, through the via. Therefore, the power source line83made of the third conductive layer and the ground line84made of the second conductive layer prevent variations in the power source potential and the ground potential.

Next, the light emitter4will be described in detail.

FIGS.7A and7Bare views for illustrating the light emitter4to which a first exemplary embodiment is applied.FIG.7Ais a plan view, andFIG.7Bis a sectional view taken along line VIIB-VIIB inFIG.7A. Here, inFIG.7A, a rightward direction of the paper surface is the x direction, and an upward direction of the paper surface is the y direction. A direction orthogonal to the x and y directions counterclockwisely is a z direction. Accordingly, inFIG.7B, a rightward direction of the paper surface is the x direction, and an upward direction of the paper surface is the z direction. The same will also be applied in similar drawings below.

As described above, the light emitter4includes the substrate10, the light source20, the diffusion plate30, the PD40, the driving section50, and the support section60. In addition, on the substrate10of the light emitter4, the circuit member, such as the 3D sensor5, the resistive element6, and the capacitor7, is also mounted. In addition, on the substrate10, as described above, the wirings for connecting the light source20, the PD40, the driving section50, the 3D sensor5, the resistive element6, the capacitor7and the like, such as the anode wiring11and the cathode wiring12, are provided.

In the light emitter4, for example, the PD40, the light source20, and the driving section50are disposed in this order in the +x direction on the substrate10. In addition, the diffusion plate30is provided so as to cover the light source20and the PD40. Further, the diffusion plate30does not cover the driving section50, the 3D sensor5, the resistive element6, and the capacitor7. In other words, the circuit member that is not covered with the diffusion plate30is mounted on the substrate10. The diffusion plate30covers a part of the substrate10and does not cover the entire substrate10.

The light source20may be directly mounted on the substrate10on which the above-described circuit pattern or the like is formed. In addition, the light source20is provided on a heat dissipation substrate made of a heat dissipation base material, such as aluminum oxide or aluminum nitride, and the heat dissipation substrate may be mounted on the substrate10. Further, the light source20may be mounted on the substrate of which a part at which the light source20is mounted is recessed. Here, the substrate10includes a circuit board having the circuit pattern, a circuit board including a heat dissipation substrate, a substrate recessed for mounting the light source20, or the like.

As illustrated inFIG.7B, the diffusion plate30is supported by the support section60with a predetermined distance from the light source20. The support section60includes wall portions61,62, and63. The wall portion61is provided on the PD40side, and the wall portions62and63are provided so as to face the +y side and −y side of the light source20. The wall portion61forms a yz plane, and the wall portions62and63form a zx plane. In addition, the wall portions61,62, and63are connected to each other on the side surface. In other words, in a case of being viewed in the −z direction, a sectional shape on an xy plane of the support section60is a U shape, and the driving section50side is an opening. In other words, between the light source20and the driving section50, the wall portion is not provided. Here, a case where the wall portion is not provided between the light source20and the driving section50is referred to as a case where the support section60is not provided between the light source20and the driving section50. In addition, in a case of not distinguishing the wall portions61,62, and63respectively, there is a case where the wall portions61,62, and63are referred to as the wall portions or walls.

In addition, as illustrated inFIGS.7A and7B, the three sides of the diffusion plate30having a square planar shape are supported by the wall portions61,62, and63. The support section60is, for example, a single member integrally molded with a resin material such as a liquid crystal polymer or a ceramic, the thickness of the wall portion is 300 μm, and the height of the wall portion is 450 to 550 μm. In addition, the support section60is made in a black color or the like so as to absorb the light emitted from the light source20. Further, one end surface of the wall portion of the support section60is bonded to the substrate10, and the other end surface is bonded to the diffusion plate30.

As illustrated inFIGS.7A and7B, between the light source20and the driving section50, the wall portion, that is, the support section60, is not provided. In such a structure, the light source20and the driving section50are disposed close to each other, so that the wiring for supplying the current for the light emission from the driving section50to the light source20is shortened, and the wiring inductance is reduced. Accordingly, the light source20is turned on and off at a high speed.

As illustrated inFIG.7B, the PD40is covered with the diffusion plate30together with the light source20. Accordingly, the PD40receives a part of the light reflected by the diffusion plate30in the light emitted from the light source20. Therefore, as described inFIG.6, the PD40detects (monitors) the intensity of the light emitted from the light source20.

Light Emitter4′ for Comparison

FIGS.8A and8Bare views for illustrating a light emitter4′ illustrated for comparison.FIG.8Ais a plan view, andFIG.8Bis a sectional view taken along line inFIG.8A. Hereinafter, parts different from the light emitter4to which the first exemplary embodiment illustrated inFIGS.7A and7Bis applied will be described.

In the light emitter4′ illustrated inFIGS.8A and8B, a support section60′ includes a wall portion64in addition to the wall portions61,62, and63. The wall portion64is provided on the driving section50side, and forms the yz plane. In addition, the wall portions61,62,63, and64are connected to each other on the side surface. In other words, the sectional shape of the support section60in the z direction forms sides of the square. In addition, the light source20and the PD40are surrounded by the wall portions61,62,63, and64of the support section60. Therefore, as compared with a case where the support section60supports the diffusion plate30by three sides in the light emitter4, a support section60′ of the light emitter4′ is likely to more reliably support the diffusion plate30. However, in the light emitter4′, between the light source20and the driving section50, the wall portion64of the support section60′ exists. In other words, in the light emitter4′, between the light source20and the driving section50, the support section60′ exists. Therefore, the distance between the light source20and the driving section50should be set to be equal to or greater than the thickness of the wall portion64. As described above, when the thickness of the wall portion is 300 μm, the wiring for supplying the current for the light emission from the driving section50to the light source20becomes longer than 300 μm that corresponds to at least the thickness of the wall portion64. Therefore, there is a concern that an increase in wiring inductance becomes a constraint in a case of turning on and off the light source20at a high speed.

The light emitter4to which the first exemplary embodiment illustrated inFIGS.7A and7Bis applied does not include the support section between the light source20and the driving section50. Therefore, as indicated by an arrow inFIG.7B, there is a concern that the light emitted to the driving section50side from the light source20is emitted to the outside without being transmitted through the diffusion plate30. In particular, there is a concern that the light having a high intensity is emitted to the outside from the VCSEL group22that is illustrated being surrounded by broken lines inFIG.3and provided in the end portion on the driving section50side of the light source20. In addition, light intensity is sometimes referred to as emission intensity.

Here, the position of the end portion33on the driving section50side of the diffusion plate30may be set such that the light having an emission intensity of 50% or higher, which is the intensity of the light emitted by the VCSEL group22, is incident on the diffusion plate30. With such setting, the intensity of the light emitted to the outside without being diffused by the diffusion plate30is set to be lower than 50% of the intensity (emission intensity) of the light emitted by the VCSEL. With such setting, light with a high intensity is prevented from being applied from the light source20to the measurement target.

Furthermore, the position of the end portion33on the driving section50side of the diffusion plate30may be set such that the light having an intensity (emission intensity) of 0.1% or higher emitted by the VCSEL group22is incident on the diffusion plate30. With such setting, the intensity of the light emitted to the outside without being diffused by the diffusion plate30is set to be lower than 0.1% of the intensity (emission intensity) of the light emitted by the VCSEL. With such setting, light with a high intensity is prevented from being applied from the light source20to the measurement target. In this case, when the spread angles of the light emitted by the VSCEL are the same, the diffusion plate30may extend to the side on which a support wall of the support section60is not provided, that is, the driving section50side.

Modification Example of Light Emitter4

A modification example of the light emitter4to which the first exemplary embodiment illustrated inFIGS.7A and7Bis applied will be described.

In the light emitter4, the diffusion plate30covers the light source20and the PD40, and does not cover the driving section50. In the modification example of the light emitter4to which the first exemplary embodiment is applied, the diffusion plate30covers a part of the driving section50.

FIGS.9A to9Care plan views for illustrating the modification example of the light emitter4to which the first exemplary embodiment is applied.FIG.9Ais a light emitter4-1according to Modification Example 1,FIG.9Bis a light emitter4-2according to Modification Example 2, andFIG.9Cis a light emitter4-3according to Modification Example 3. In addition, inFIGS.9A to9C, only the light source20, the diffusion plate30, the PD40, the driving section50, and the support section60are referred to. Further, the same parts as the light emitter4illustrated inFIGS.7A and7Bwill be given the same reference numerals, and the description thereof will be omitted.

In the light emitter4-1according to Modification Example 1 illustrated inFIG.9A, the diffusion plate30overhangs to the one end portion on the light source20side of the driving section50and also covers a part of the driving section50. In the light emitter4-2according to Modification Example 2 illustrated inFIG.9B, the diffusion plate30overhangs to the center portion of the driving section50and covers the center portion of the driving section50. In the light emitters4-1and4-2, with the overhang of the diffusion plate30, the wall portions62and63of the support section60overhang to the driving section50side. In addition, three sides of the diffusion plate30are supported by the wall portions61,62, and63of the support section60. The light emitters4-1and4-2are applied to a case where a width WCof the driving section50is smaller than a width Wyof the diffusion plate30, and more strictly speaking, a distance LDbetween the wall portions62and63.

In the light emitter4-3according to Modification Example 3 illustrated inFIG.9C, the diffusion plate30also overhangs to the one end portion of the driving section50and covers a part of the driving section50. However, the wall portions62and63of the support section60are not provided at the part at which the diffusion plate30overhangs on the driving section50. In other words, the light emitter4-3is applied to a case where the width WCof the driving section50is greater than the width Wyof the diffusion plate30, and more strictly speaking, the distance LDbetween the wall portions62and63.

In the light emitters4-1to4-3, three sides of the diffusion plate30are supported by the wall portions61,62, and63of the support section60, and the support wall, that is, the support section, is not provided between the light source20and the driving section50. In addition, as the diffusion plate30overhangs on the driving section50side, the distance between the VCSEL group22provided in the end portion on the driving section50side of the light source20and the end portion33of the diffusion plate30becomes greater. Accordingly, light with a high intensity can be easily prevented from being applied from the end portion of the diffusion plate30. For example, in a case where the light transmitted through the diffusion plate30is equal to or higher than 50%, the light emitter4-1may be used, and in a case where the light transmitted through the diffusion plate30is equal to or higher than 0.1%, the light emitter4-2may be used, selectively.

Second Exemplary Embodiment

In a light emitter4A to which a second exemplary embodiment is applied, a beam portion provided to extend to the driving section50side from the diffusion plate30side is provided on the driving section50side of the diffusion plate30.

FIGS.10A and10Bare views for illustrating the light emitter4A to which the second exemplary embodiment is applied.FIG.10Ais a plan view, andFIG.10Bis a sectional view taken along line XB-XB ofFIG.10A. The same parts as the light emitter4illustrated inFIGS.7A and7Bwill be given the same reference numerals, and the description thereof will be omitted.

As illustrated inFIG.10A, the diffusion plate30covers the light source20and the PD40, and covers a part of the surface of the driving section50. In addition, a support section60A is provided with the wall portions61,62, and63for supporting the three sides of the diffusion plate30with respect to the substrate10. Further, the light emitter4A includes a beam portion65provided toward the driving section50side from the one remaining side of the diffusion plate30. As illustrated inFIG.10B, an upper surface (a surface that faces the +z direction) of the beam portion65is bonded to the diffusion plate30. In addition, in the beam portion65, a lower surface on the substrate10side (a surface that faces the −z direction) has a distance to the surface (a surface that faces the +z direction) of the driving section50. In addition, instead of the beam portion65, similar to a beam portion65′ illustrated by broken lines, the beam portion may be in contact with the driving section50.

The support section60(wall portions61,62, and63) and the beam portion65(beam portion65′) may be formed as a single member by the integral molding. Accordingly, as compared with a case of assembling plural support members, the number of assembling steps is reduced. In addition, the support section60(wall portions61,62, and63) and the beam portion65(beam portions65′) formed as a single member will be referred to as the support section60A.

When the beam portion65(beam portion65′) is made of a light absorbing material, light with a high intensity from the VCSEL group22of the end portion on the driving section50side of the light source20is prevented from going outside without being transmitted through the diffusion plate30. In other words, as compared with a case where the beam portion65(65′) is not provided, the overhang of the diffusion plate30to the driving section50side may be reduced. In other words, the area of the diffusion plate30is reduced.

Further, similar to the beam portion65′, with a configuration in which the lower surface is in contact with the driving section50, the diffusion plate30is reliably supported by the wall portions61,62, and63and the beam portion65′ of the support section60. In addition, the entry of foreign matters, such as dust or dirt, to the surrounding of the light source20is prevented. In addition, since the support section60A and the beam portion65are formed as a single member, the number of assembling steps can be reduced.

Third Exemplary Embodiment

In the light emitter4to which the first exemplary embodiment is applied, the diffusion plate30is supported by the support section60with three sides. In a light emitter4B to which a third exemplary embodiment is applied, the diffusion plate30is supported by a support section60B with four sides.

FIGS.11A and11Bare plan views of the light emitter4B to which the third exemplary embodiment is applied.FIG.11Ais a plan view, andFIG.11Bis a sectional view taken along line XIB-XIB ofFIG.11A. The same parts as the light emitter4illustrated inFIGS.7A and7Bwill be given the same reference numerals, and the description thereof will be omitted.

In the light emitter4B, the light source20, the PD40, and the driving section50are covered with the diffusion plate30. In addition, the support section60B includes the wall portions61,62,63, and66, which support the diffusion plate30on four sides and are provided to surround the light source20, the PD40, and the driving section50. In addition, the support section60B (wall portions61,62,63, and66) is formed as a single member by integral molding. The support section60B is made of a light absorbing material.

In this case, in the light source20of the light emitter4B, the optical axial direction side is covered with the diffusion plate30, and the side surface side is covered with the support section60. Since the support section60B is made of the light absorbing material, the light emitted from the light source20is prevented from leaking directly to the outside. In addition, since the support section60B is formed as a single member, the number of assembling steps can be reduced.

Modification Example of Light Emitter4B

In the light emitter4B to which the third exemplary embodiment is applied, the diffusion plate30also covers the driving section50. In general, in the diffusion plate30, the greater the area, the higher the price. In addition, the diffusion plate30is not required to cover the driving section50. Here, in a light emitter4B-1which is a modification example of the light emitter4B, a blocking section67for blocking the transmission of the light is provided at a part of the upper side of the support section60B of the light emitter4B, and the area of the diffusion plate30is reduced.

FIGS.12A and12Bare views for illustrating the light emitter4B-1which is the modification example of the light emitter4B to which the third exemplary embodiment is applied.FIG.12Ais a plan view, andFIG.12Bis a sectional view taken along line XIIB-XIIB ofFIG.12A. The same parts as the light emitter4B illustrated inFIGS.11A and11Bwill be given the same reference numerals, and the description thereof will be omitted.

In the light emitter4B-1, the diffusion plate30is provided only on the optical axial direction side of the light source20, and the driving section50is not covered with the diffusion plate30and is covered with the blocking section67. As illustrated inFIG.12A, similar to the support section60B of the light emitter4B, the light emitter4B-1is provided with the wall portions61,62,63, and66. In addition, the blocking section67is provided at a part of an upper opening of the support section60B (FIG.12A). The blocking section67is on the wall portion66side so as to not to block the light emitted from the light source20and transmitted through the diffusion plate30, and is provided to cover the driving section50. In addition, the surface (a surface that faces the +z direction) of the blocking section67is formed as a surface flush with the surfaces of the wall portions61,62,63, and66. Further, the rear surface (a surface that faces the −z direction) of the blocking section67is provided not to be in contact with the driving section50. In addition, the support section60(wall portions61,62,63, and66) and the blocking section67are formed as a single member by the integral molding. The diffusion plate30is bonded and fixed to the wall portion61side which is a part of the upper surfaces of the wall portions61,62, and63and the surface of the blocking section67. In other words, the diffusion plate30is provided so as to seal the opening made by the wall portions61,62, and63and the blocking section67. In this manner, the support section60B and the blocking section67which became a single member are referred to as a support section60B-1.

Even in the light emitter4B-1, in the light source20, the optical axial direction side is covered with the diffusion plate30, and the side surface side is covered with the support section60B-1. Since the support section60B-1includes the light absorbing material, the light emitted from the light source20is prevented from leaking directly to the outside. In addition, as compared with the diffusion plate30of the light emitter4B, the area of the diffusion plate30becomes smaller. Accordingly, the price of the optical device3is reduced. In addition, since the support section60B (wall portions61,62,63, and66) and the blocking section67are formed as a single member, the number of assembling steps can be reduced.

Fourth Exemplary Embodiment

In the light emitters4and4-1to4-3to which the first exemplary embodiment is applied, the light emitter4A to which the second exemplary embodiment is applied, and the light emitters4B and4B-1to which the third exemplary embodiment is applied, the wall portion, that is, the support section, is not provided between the light source20and the driving section50. The light emitter4C to which the fourth exemplary embodiment is applied includes a support section60C provided with a wall portion68between the light source20and the driving section50.

FIGS.13A and13Bare views for illustrating the light emitter4C to which the fourth exemplary embodiment is applied.FIG.13Ais a plan view, andFIG.13Bis a sectional view taken along line XIIIB-XIIIB ofFIG.13A. The same parts as the light emitter4illustrated inFIGS.7A and7Bwill be given the same reference numerals, and the description thereof will be omitted.

The support section60C of the light emitter4C includes the wall portions61,62, and63provided on the three sides of the diffusion plate30, and the wall portion68on the one remaining side. In addition, the wall portions61,62, and63and the wall portion68are different from each other in thickness. Specifically, the thickness t2 of the wall portion68is smaller than the thickness t1 of the wall portions61,62, and63(t1>t2). The thick wall portions61,62, and63and a thin wall portion68support the diffusion plate30. In addition, the thickness of the wall portion68may be set so as to reduce any influence on the inductance of the wiring that connects the light source20and the driving section50to each other. When the wall portion68is provided, the light from the light source20is prevented from going outside without passing through the diffusion plate30. Further, since the light source20is surrounded by the support section60C and the diffusion plate30, the entry of foreign matter, such as dust or dirt, to the surrounding of the light source20is prevented.

The support section60C became a single member to which the wall portions61,62,63, and68are continuous to each other by the integral molding. Accordingly, as compared with a case of assembling plural support members, the number of assembling steps is reduced.

Fifth Exemplary Embodiment

A sectional structure of the information processing apparatus1that uses the light emitters4and4-1to4-3to which the first exemplary embodiment is applied, the light emitter4A to which the second exemplary embodiment is applied, the light emitters4B and4B-1to which the third exemplary embodiment is applied, and the light emitter4C to which the fourth exemplary embodiment is applied, will be described. In addition, the information processing apparatus1is an example of a light emitting device.

Sectional Structure of Information Processing Apparatus1

Here, the sectional structure of the information processing apparatus1will be described while the information processing apparatus1uses the light emitter4to which the first exemplary embodiment is applied. In addition, the same will also be applied to a case of using other light emitters.

FIG.14is a view for illustrating the sectional structure of the information processing apparatus1that uses the light emitter4. The information processing apparatus1includes the optical device3and a housing100. As described above, the optical device3includes the light emitter4and the 3D sensor5. In other words, the housing100accommodates the light emitter4. Here, similar to the light emitter4illustrated inFIGS.7A and7B, the 3D sensor5is mounted on the substrate10provided in the light emitter4.

The housing100includes a transmission section plate110through which the light emitted from the light source20in the light emitter4is transmitted, and a transmission section plate120through which the light received by the 3D sensor5is transmitted. The transmission section plate110is provided at a part that corresponds to a region where the light source20emits the light, and the transmission section plate120is provided at a part that corresponds to a region where the 3D sensor5receives the light. The housing100includes, for example, a metal material, such as aluminum or magnesium, or a resin material. In addition, the transmission section plates110and120each include a transparent material, such as glass or acrylic.

The substrate10is held by substrate holding means101for holding the substrate10with respect to the housing100. In addition, on the 3D sensor5, a lens130for converging the light transmitted through the transmission section plate120to the 3D sensor5, is provided. The lens130is held by lens holding means131for holding the lens130with respect to the substrate10. The substrate holder101is, for example, a fastener, such as a screw, or a fitting member, which is made of resin or the like.

In the information processing apparatus1, the distance between the light source20and the driving section50of the light emitter4is set to be smaller than the distance between the light source20and the transmission section plate110.

In addition, the transmission section plate120may have a function of the lens130.

After being transmitted through the diffusion plate30, the light emitted from the light source20of the light emitter4is transmitted through the transmission section plate110and is applied to the measurement target.

When the light emitter4(optical device3) is accommodated in the housing100in this manner, the diffusion plate30is prevented from being damaged. In other words, application of high-intensity light directly to the outside due to damage to the diffusion plate30is prevented.

In the above-described first to fifth exemplary embodiments, the diffusion plate30of which the spread angle of the light emitted by the light emitting element increases are described as an example of the cover section. Instead of the diffusion plate30, the cover section may be a member through which the light is transmitted, for example, a transparent base material, such as a cover for protection, an optical member, such as a converging lens and a microlens array having a converging action to reduce the spread angle in the opposite, or the like. Here, the cover section including the members is adopted.