Patent Publication Number: US-11657130-B2

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

Description:
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. 
     Aspects of certain non-limiting embodiments of the present disclosure address the features discussed above and/or other features not described above. However, aspects of the non-limiting embodiments are not required to address the above features, and aspects of the non-limiting embodiments of the present disclosure may not address features described above. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG.  1    is a view illustrating an example of an information processing apparatus; 
         FIG.  2    is a block diagram illustrating a configuration of the information processing apparatus; 
         FIG.  3    is a plan view of a light source; 
         FIG.  4    is a view for illustrating a sectional structure of one VCSEL in the light source; 
         FIGS.  5 A and  5 B  are views for illustrating an example of a diffusion plate;  FIG.  5 A  is a plan view, and  FIG.  5 B  is a sectional view taken along line VB-VB of  FIG.  5 A ; 
         FIG.  6    is a view illustrating an example of an equivalent circuit for driving the light source by low side driving; 
         FIGS.  7 A and  7 B  are views for illustrating a light emitter to which a first exemplary embodiment is applied;  FIG.  7 A  is a plan view, and  FIG.  7 B  is a sectional view taken along line VIIB-VIIB in  FIG.  7 A ; 
         FIGS.  8 A and  8 B  are views for illustrating a light emitter illustrated for comparison; 
         FIG.  8 A  is a plan view, and  FIG.  8 B  is a sectional view taken along line VIIIB-VIIIB in  FIG.  8 A ; 
         FIGS.  9 A to  9 C  are plan views for illustrating a modification example of the light emitter to which the first exemplary embodiment is applied;  FIG.  9 A  is a light emitter according to Modification Example 1,  FIG.  9 B  is a light emitter according to Modification Example 2, and  FIG.  9 C  is a light emitter of Modification Example 3; 
         FIGS.  10 A and  10 B  are views for illustrating a light emitter to which a second exemplary embodiment is applied;  FIG.  10 A  is a plan view, and  FIG.  10 B  is a sectional view taken along line XB-XB in  FIG.  10 A ; 
         FIGS.  11 A and  11 B  are views for illustrating a light emitter to which a third exemplary embodiment is applied;  FIG.  11 A  is a plan view, and  FIG.  11 B  is a sectional view taken along line XIB-XIB in  FIG.  11 A ; 
         FIGS.  12 A and  12 B  are views for illustrating a light emitter which is a modification example of the light emitter to which the third exemplary embodiment is applied;  FIG.  12 A  is a plan view, and  FIG.  12 B  is a sectional view taken along line XIIB-XIIB in  FIG.  12 A ; 
         FIGS.  13 A and  13 B  are views for illustrating a light emitter to which a fourth exemplary embodiment is applied;  FIG.  13 A  is a plan view, and  FIG.  13 B  is a sectional view taken along line XIIIB-XIIIB in  FIG.  13 A ; and 
         FIG.  14    is a view for illustrating a sectional structure of an information processing apparatus that uses the light emitter. 
     
    
    
     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 Apparatus  1   
       FIG.  1    is a view illustrating an example of an information processing apparatus  1 . As described above, the information processing apparatus  1  is a portable information processing terminal as an example. 
     The information processing apparatus  1  includes: a user interface portion (hereinafter, referred to as UI portion)  2 ; and an optical device  3  that acquires the three-dimensional image. The UI portion  2  includes, 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 device  3  includes a light emitter  4  and a three-dimensional sensor (hereinafter, referred to as 3D sensor)  5 . The light emitter  4  emits light toward the measurement target whose three-dimensional image is to be acquired, specifically, the face in the example described here. The 3D sensor  5  acquires the light that is emitted from the light emitter  4 , 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 apparatus  1  is 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 apparatus  1  is operated and various types of information processing are executed. 
       FIG.  2    is a block diagram illustrating a configuration of the information processing apparatus  1 . 
     The information processing apparatus  1  includes the above-described optical device  3 , an optical device controller  8 , and a system controller  9 . The optical device controller  8  controls the optical device  3 . In addition, the optical device controller  8  includes a shape specifying section  81 . The system controller  9  controls the entire information processing apparatus  1  as a system. Further, the system controller  9  includes an authentication processing section  91 . In addition, the UI portion  2 , a speaker  92 , a two-dimensional camera (in  FIG.  2   , referred to as 2D camera)  93  and the like are connected to the system controller  9 . Further, the 3D sensor  5  is an example of a light receiving section, and the optical device controller  8  is an example of a controller. 
     Hereinafter, a more detailed description will be given. 
     The light emitter  4  includes a substrate  10 , a light source  20 , a diffusion plate  30 , a light amount monitoring light receiving element (referred as PD in  FIG.  2    and the following drawings)  40 , a driving section  50 , and a support section  60 , and a capacitor  70 . Here, two capacitors  70  are shown as an example, and in a case of distinguishing the two capacitors, the capacitors  70  will be referred to as capacitors  70 A and  70 B. The light source  20 , the PD  40 , the driving section  50 , the capacitor  70  are provided on the substrate  10 . In addition, the diffusion plate  30  is held by the support section  60  with a predetermined distance from the substrate  10 , and is provided to cover the light source  20  and the PD  40 . The diffusion plate  30  is an example of a cover section. 
     In addition, on the substrate  10 , the 3D sensor  5 , a resistive element  6 , and a capacitor  7  are mounted in addition to the above-described members. The resistive element  6  and the capacitor  7  are provided for operating the driving section  50  or the 3D sensor  5 . In addition, one resistive element  6  and one capacitor  7  are described respectively, but plural resistive elements  6  and capacitors  7  may be mounted. Further, in  FIG.  1   , the 3D sensor  5  is also provided on the substrate  10 , but the 3D sensor  5  may not be provided on the substrate  10 . 
     The light source  20  in the light emitter  4  includes 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 source  20  emits the light in a direction perpendicular to the substrate  10 . In a case of performing the three-dimensional sensing by the ToF method, it is required for the light source  20  to 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 section  50 . 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 substrate  10 , the diffusion plate  30 , the PD  40 , the driving section  50 , the support section  60 , and the capacitor  70  in the light emitter  4  will be described later. In addition, the light source  20  will be described in detail later. 
     The 3D sensor  5  includes 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 source  20 , 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 sensor  5  is 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 sensor  5  outputs 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 sensor  5  outputs a signal that corresponds to the time until the light is received by the 3D sensor  5  after the light is emitted from the light source  20 . In addition, the AD converter may be provided in the 3D sensor  5  or may be provided outside the 3D sensor  5 . 
     The shape specifying section  81  of the optical device controller  8  acquires a digital value obtained from the 3D sensor  5  in 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 section  91  of the system controller  9  performs authentication processing related to the use of the information processing apparatus  1  in a case where the 3D shape of the measurement target specified by the shape specifying section  81  has 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 apparatus  1 , as an example, is processing of determining whether or not the use of the information processing apparatus  1  which 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 apparatus  1  including various applications and the like provided by the information processing apparatus  1  is allowed. 
     The above-described shape specifying section  81  and the authentication processing section  91  include, for example, a program. Alternatively, the shape specifying section  81  and the authentication processing section  91  may include an integrated circuit, such as ASIC or FPGA. Furthermore, the shape specifying section  81  and the authentication processing section  91  may include software, such as a program, and an integrated circuit, such as ASIC. 
     In  FIG.  2   , the optical device  3 , the optical device controller  8 , and the system controller  9  are illustrated respectively, but the system controller  9  may include the optical device controller  8 . In addition, the optical device  3  may include the optical device controller  8 . Furthermore, the optical device  3 , the optical device controller  8 , and the system controller  9  may be integrally formed. 
     Before description of the light emitter  4 , the light source  20 , the diffusion plate  30 , the PD  40 , the driving section  50 , and the capacitor  70  that form the light emitter  4  will be described. 
     Configuration of Light Source  20   
       FIG.  3    is a plan view of the light source  20 . The light source  20  has 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 substrate  200  (refer to  FIG.  4    which 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 source  20  is, 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 source  20 , a common anode electrode  218  (refer to  FIG.  4    which will be described later) is provided in the plural VCSELs. In addition, the anode electrode  218  is connected to an anode wiring  11  provided on the substrate  10  via a bonding wire  21 . Further, a cathode electrode  214  (refer to  FIG.  4    which will be described later) is provided on a rear surface of the light source  20  and bonded to a cathode wiring  12 , in which the cathode electrode  214  is provided on the substrate  10 , with a conductive adhesive or the like. The conductive adhesive is, for example, a silver paste. 
     Structure of VCSEL 
       FIG.  4    is a view for illustrating a sectional structure of one VCSEL in the light source  20 . 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)  202  in which AlGaAs layers having different Al compositions alternately overlap each other, an active region  206  including a quantum well layer sandwiched between an upper spacer layer and a lower spacer layer, and a p-type upper distribution Bragg type reflecting mirror  208  in which AlGaAs layers having different Al compositions alternately overlap each other, are stacked on the semiconductor substrate  200 , such as an n-type GaAs. Hereinafter, the distribution Bragg reflecting mirror will be referred to as DBR. 
     The n-type lower DBR  202  is a stacked body in which an Al 0.9 Ga 0.1 As layer and a GaAs layer are made into one pair, the thickness of each layer is λ/4n r  (while λ, is an oscillation wavelength and n r  is 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, 3×10 18  cm −3 . 
     The active region  206  has 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 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. 
     The p-type upper DBR  208  is a stacked body in which a p-type Al 0.9 Ga 0.1 As layer and a GaAs layer are made into one pair, the thickness of each layer is λ/4n r , 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, 3×10 18  cm −3 . Preferably, on the uppermost layer of the upper DBR  208 , a contact layer made of p-type GaAs is formed, and on the lowermost or on the inside of the upper DBR  208 , a current constriction layer  210  of p-type AlAs is formed. 
     By etching the semiconductor layer stacked from the upper DBR  208  until reaching the lower DBR  202 , a cylindrical mesa M is formed on the semiconductor substrate  200 . Accordingly, the current constriction layer  210  is exposed on the side surface of the mesa M. By an oxidation step, on the current constriction layer  210 , an oxidized region  210 A oxidized from the side surface of the mesa M and a conductive region  210 B surrounded by the oxidized region  210 A 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 region  210 A is oxidized substantially at the same speed from the side surface of the mesa M inward, a planar shape parallel to the semiconductor substrate  200  of the conductive region  210 B 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 electrode  212  made of metal in which Ti/Au and the like are stacked is formed. The p-side electrode  212  is in ohmic contact with the contact layer provided on the upper DBR  208 . The inner side of the annular p-side electrode  212  is a light emission port  212 A 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 substrate  200 , and the axial direction of the mesa M is the optical axis. Furthermore, on the rear surface of the semiconductor substrate  200 , the cathode electrode  214  is formed as an n-side electrode. In addition, the surface of the upper DBR  208  on the inside of the p-side electrode  212  is a light emitting surface. 
     In addition, except for the part to which the anode electrode (anode electrode  218  which will be described later) of the p-side electrode  212  is connected and the light emission port  212 A, an insulating layer  216  is provided so as to cover the surface of the mesa M. Further, except for the light emission port  212 A, the anode electrode  218  is provided so as to be in ohmic contact with the p-side electrode  212 . In addition, the anode electrode  218  is provided in common to the plural VCSELs. In other words, each of the p-side electrodes  212  is connected to the plural VCSELs that form the light source  20  by the anode electrode  218  in 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 group  22  of an end portion in the x direction is a VCSEL positioned on the driving section  50  side illustrated in  FIGS.  7 A and  7 B  which will be described later. 
     Configuration of Diffusion Plate  30   
       FIGS.  5 A and  5 B  are views for illustrating an example of the diffusion plate  30 .  FIG.  5 A  is a plan view, and  FIG.  5 B  is a sectional view taken along line VB-VB of  FIG.  5 A . In  FIG.  5 A , 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, in  FIG.  5 B , 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 in  FIG.  5 B , the diffusion plate  30  has both surfaces parallel to each other, and includes a resin layer  32  on which irregularities for diffusing the light to one surface of a flat glass base material  31 , here, a −z direction side which is a rear surface, are formed. The diffusion plate  30  further spreads a spread angle of light incident from the VCSEL of the light source  20  and emits the light. In other words, the irregularities formed on the resin layer  32  of the diffusion plate  30 , 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 in  FIGS.  5 A and  5 B , the spread angle β of the light emitted from the diffusion plate  30  being transmitted through the diffusion plate  30  becomes greater than the spread angle α of the light emitted from the VCSEL (α&lt;β). Therefore, when the diffusion plate  30  is used, the area of the surface irradiated with the light emitted from the light source  20  is larger than when the diffusion plate  30  is 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 plate  30  has, for example, a square planar shape, a width W x  in the x direction and a longitudinal width W y  in the y direction are 1 mm to 10 mm, and a thickness t d  in the z direction is 0.1 mm to 1 mm. In addition, the end portion in the x direction is an end portion  33  of the diffusion plate  30 . As will be described in  FIGS.  7 A and  7 B  which will be described later, the end portion  33  is the driving section  50  side. In addition, the planar shape of the diffusion plate  30  may 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. 
     PD  40   
     The PD  40  is 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 PD  40  is disposed to receive the light emitted from the light source  20  and reflected by the rear surface (a surface in the −z direction in  FIG.  7 B  which will be described later) of the diffusion plate  30 . The light source  20  is controlled to maintain the predetermined light amount and emit the light based on the amount of light received by the PD  40 . In other words, as will be described later, the optical device controller  8  monitors the amount of light received by the PD  40 , controls the driving section  50 , and controls the light amount emitted from the light source  20 . 
     Driving Section  50  and Capacitor  70   
     In a case where it is desired to drive the light source  20  at 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.  6    is a view illustrating an example of an equivalent circuit for driving the light source  20  by the low side driving. In  FIG.  6   , the VCSEL of the light source  20 , the driving section  50 , the capacitor  70 , a power source  82 , the PD  40 , and a detecting resistive element  41  for detecting a current that flows through the PD  40  are illustrated. In addition, the capacitors  70 A and  70 B which are referred to in  FIG.  2   , are connected to the power source  82  in parallel. Accordingly, the capacitors  70 A and  70 B are not divided and distinguished from each other and are referred to as the capacitor  70 . 
     The power source  82  is provided in the optical device controller  8  illustrated in  FIG.  2   . The power source  82  generates 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 line  83 , and the ground potential is supplied to a ground line  84 . 
     The light source  20  has a configuration in which the plural VCSELs are connected to each other in parallel as described above. The anode electrode  218  (refer to  FIG.  4   ) of the VCSEL is connected to the power source line  83  via the anode wiring  11  provided on the substrate  10 . 
     The driving section  50  includes an n-channel MOS transistor  51  and a signal generating circuit  52  to turn on and off the MOS transistor  51 . The drain of the MOS transistor  51  is connected to the cathode electrode  214  (refer to  FIG.  4   ) of the VCSEL via the cathode wiring  12  provided on the substrate  10 . The source of the MOS transistor  51  is connected to the ground line  84 . In addition, the gate of the MOS transistor  51  is connected to the signal generating circuit  52 . In other words, the VCSEL of the light source  20  and the MOS transistor  51  of the driving section  50  are connected to each other in series between the power source line  83  and the ground line  84 . The signal generating circuit  52  generates a signal of “H level” for turning on the MOS transistor  51  and a signal of “L level” for turning off the MOS transistor  51 , by the control of the optical device controller  8 . 
     In the capacitor  70 , one terminal is connected to the power source line  83 , and the other terminal is connected to the ground line  84 . In addition, the capacitor  70  includes, for example, an electrolytic capacitor or a ceramic capacitor. 
     In the PD  40 , the cathode is connected to the power source line  83 , and the anode is connected to one terminal of the detecting resistive element  41 . In addition, the other terminal of the detecting resistive element  41  is connected to the ground line  84 . In other words, the PD  40  and the detecting resistive element  41  are connected to each other in series between the power source line  83  and the ground line  84 . Further, an output terminal  42  which is a connection point between the PD  40  and the detecting resistive element  41  is connected to the optical device controller  8 . 
     Next, a driving method of the light source  20  which is the low side driving will be described. 
     First, the signal generated by the signal generating circuit  52  in the driving section  50  is “L level”. In this case, the MOS transistor  51  is turned off. In other words, the current does not flow between the source and the drain of the MOS transistor  51 . 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 capacitor  70  is charged by the power source  82 . In other words, one terminal of the capacitor  70  is the power source potential and the other terminal is the ground potential. In the capacitor  70 , 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 circuit  52  in the driving section  50  is “H level”, the MOS transistor  51  is shifted from OFF to ON. Then, the electric charges accumulated in the capacitor  70  flow (being discharged) to the MOS transistor  51  and the VCSEL connected to each other in series, the VCSEL emits the light. 
     In addition, when the signal generated by the signal generating circuit  52  in the driving section  50  is “L level”, the MOS transistor  51  is shifted from ON to OFF. Accordingly, the light emission of the VCSEL is stopped. Then, the accumulation of the electric charges in the capacitor  70  is resumed by the power source  82 . 
     As described above, each time the signal output from the signal generating circuit  52  shifts 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 capacitor  70 , the electric charges (current) may be directly supplied from the power source  82  to the VCSEL, but by accumulating the electric charges in the capacitor  70 , discharging the accumulated electric charges by the switching of the MOS transistor  51 , 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 source  20  and the driving section  50  is reduced so that the inductance of the wiring is lowered, the light source  20  can be turned on and off at a high speed. In addition, the distance between the light source  20  and the driving section  50  may preferably be equal to or less than 1 mm. 
     The PD  40  is connected in a reverse direction via the detecting resistive element  41  between the power source line  83  and the ground line  84 . Therefore, in a state where the light is not emitted, the current does not flow. When the PD  40  receives a part of the light reflected by the diffusion plate  30  in the emitted light of the VCSEL, the current that corresponds to the amount of received light flows in the PD  40 . Accordingly, the current that flows through the PD  40  is measured by the voltage of the output terminal  42 , and the light intensity of the light source  20  is detected. Here, the optical device controller  8  performs the control such that the light intensity of the light source  20  is a predetermined light intensity according to the amount of light received by the PD  40 . In other words, in a case where the light intensity of the light source  20  is lower than the predetermined light intensity, the optical device controller  8  increases the amount of electric charges accumulated in the capacitor  70  by increasing the power source potential of the power source  82 , and increases the current that flows to the VCSEL. Meanwhile, in a case where the light intensity of the light source  20  is higher than the predetermined light intensity, by decreasing the power source potential of the power source  82 , the optical device controller  8  reduces the amount of electric charges accumulated in the capacitor  70 , and reduces the current that flows to the VCSEL. In this manner, the light intensity of the light source  20  is controlled. 
     Further, in a case where the amount of light receive by the PD  40  has been extremely decreased, there is a concern that the light emitted from the light source  20  is directly emitted to the outside, as the diffusion plate  30  is come off or damaged. In such a case, the optical device controller  8  reduces the light intensity of the light source  20 . For example, the emission of the light from the light source  20 , that is, the irradiation of the measurement target with the light, is stopped. 
     In addition, the substrate  10  is, for example, in the form of a multilayer substrate having three layers. In other words, the substrate  10  includes a first conductive layer, a second conductive layer, and a third conductive layer from the side on which the light source  20  or the driving section  50  are 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 line  83  and the second conductive layer is the ground line  84 . In addition, the first conductive layer forms a circuit pattern of a terminal or the like to which the anode wiring  11  of the light source  20 , the cathode wiring  12 , the PD  40 , the detecting resistive element  41 , the capacitor  70  (capacitors  70 A and  70 B) 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 line  83  of the third conductive layer is connected to the anode wiring  11  provided on the first conductive layer through the via, the terminal to which the power source line  83  of the capacitor  70  is connected, the terminal to which the cathode of the PD  40  is connected, and the like, through the via. Similarly, the ground line  84  of the second conductive layer is connected to the terminal to which the source of the MOS transistor  51  of the driving section  50  is connected, the terminal to which the ground line  84  of the detecting resistive element  41  is connected, and the like, through the via. Therefore, the power source line  83  made of the third conductive layer and the ground line  84  made of the second conductive layer prevent variations in the power source potential and the ground potential. 
     Light Emitter  4   
     Next, the light emitter  4  will be described in detail. 
       FIGS.  7 A and  7 B  are views for illustrating the light emitter  4  to which a first exemplary embodiment is applied.  FIG.  7 A  is a plan view, and  FIG.  7 B  is a sectional view taken along line VIIB-VIIB in  FIG.  7 A . Here, in  FIG.  7 A , 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, in  FIG.  7 B , 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 emitter  4  includes the substrate  10 , the light source  20 , the diffusion plate  30 , the PD  40 , the driving section  50 , and the support section  60 . In addition, on the substrate  10  of the light emitter  4 , the circuit member, such as the 3D sensor  5 , the resistive element  6 , and the capacitor  7 , is also mounted. In addition, on the substrate  10 , as described above, the wirings for connecting the light source  20 , the PD  40 , the driving section  50 , the 3D sensor  5 , the resistive element  6 , the capacitor  7  and the like, such as the anode wiring  11  and the cathode wiring  12 , are provided. 
     In the light emitter  4 , for example, the PD  40 , the light source  20 , and the driving section  50  are disposed in this order in the +x direction on the substrate  10 . In addition, the diffusion plate  30  is provided so as to cover the light source  20  and the PD  40 . Further, the diffusion plate  30  does not cover the driving section  50 , the 3D sensor  5 , the resistive element  6 , and the capacitor  7 . In other words, the circuit member that is not covered with the diffusion plate  30  is mounted on the substrate  10 . The diffusion plate  30  covers a part of the substrate  10  and does not cover the entire substrate  10 . 
     The light source  20  may be directly mounted on the substrate  10  on which the above-described circuit pattern or the like is formed. In addition, the light source  20  is 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 substrate  10 . Further, the light source  20  may be mounted on the substrate of which a part at which the light source  20  is mounted is recessed. Here, the substrate  10  includes a circuit board having the circuit pattern, a circuit board including a heat dissipation substrate, a substrate recessed for mounting the light source  20 , or the like. 
     As illustrated in  FIG.  7 B , the diffusion plate  30  is supported by the support section  60  with a predetermined distance from the light source  20 . The support section  60  includes wall portions  61 ,  62 , and  63 . The wall portion  61  is provided on the PD  40  side, and the wall portions  62  and  63  are provided so as to face the +y side and −y side of the light source  20 . The wall portion  61  forms a yz plane, and the wall portions  62  and  63  form a zx plane. In addition, the wall portions  61 ,  62 , and  63  are 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 section  60  is a U shape, and the driving section  50  side is an opening. In other words, between the light source  20  and the driving section  50 , the wall portion is not provided. Here, a case where the wall portion is not provided between the light source  20  and the driving section  50  is referred to as a case where the support section  60  is not provided between the light source  20  and the driving section  50 . In addition, in a case of not distinguishing the wall portions  61 ,  62 , and  63  respectively, there is a case where the wall portions  61 ,  62 , and  63  are referred to as the wall portions or walls. 
     In addition, as illustrated in  FIGS.  7 A and  7 B , the three sides of the diffusion plate  30  having a square planar shape are supported by the wall portions  61 ,  62 , and  63 . The support section  60  is, 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 section  60  is made in a black color or the like so as to absorb the light emitted from the light source  20 . Further, one end surface of the wall portion of the support section  60  is bonded to the substrate  10 , and the other end surface is bonded to the diffusion plate  30 . 
     As illustrated in  FIGS.  7 A and  7 B , between the light source  20  and the driving section  50 , the wall portion, that is, the support section  60 , is not provided. In such a structure, the light source  20  and the driving section  50  are disposed close to each other, so that the wiring for supplying the current for the light emission from the driving section  50  to the light source  20  is shortened, and the wiring inductance is reduced. Accordingly, the light source  20  is turned on and off at a high speed. 
     As illustrated in  FIG.  7 B , the PD  40  is covered with the diffusion plate  30  together with the light source  20 . Accordingly, the PD  40  receives a part of the light reflected by the diffusion plate  30  in the light emitted from the light source  20 . Therefore, as described in  FIG.  6   , the PD  40  detects (monitors) the intensity of the light emitted from the light source  20 . 
     Light Emitter  4 ′ for Comparison 
       FIGS.  8 A and  8 B  are views for illustrating a light emitter  4 ′ illustrated for comparison.  FIG.  8 A  is a plan view, and  FIG.  8 B  is a sectional view taken along line in  FIG.  8 A . Hereinafter, parts different from the light emitter  4  to which the first exemplary embodiment illustrated in  FIGS.  7 A and  7 B  is applied will be described. 
     In the light emitter  4 ′ illustrated in  FIGS.  8 A and  8 B , a support section  60 ′ includes a wall portion  64  in addition to the wall portions  61 ,  62 , and  63 . The wall portion  64  is provided on the driving section  50  side, and forms the yz plane. In addition, the wall portions  61 ,  62 ,  63 , and  64  are connected to each other on the side surface. In other words, the sectional shape of the support section  60  in the z direction forms sides of the square. In addition, the light source  20  and the PD  40  are surrounded by the wall portions  61 ,  62 ,  63 , and  64  of the support section  60 . Therefore, as compared with a case where the support section  60  supports the diffusion plate  30  by three sides in the light emitter  4 , a support section  60 ′ of the light emitter  4 ′ is likely to more reliably support the diffusion plate  30 . However, in the light emitter  4 ′, between the light source  20  and the driving section  50 , the wall portion  64  of the support section  60 ′ exists. In other words, in the light emitter  4 ′, between the light source  20  and the driving section  50 , the support section  60 ′ exists. Therefore, the distance between the light source  20  and the driving section  50  should be set to be equal to or greater than the thickness of the wall portion  64 . 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 section  50  to the light source  20  becomes longer than 300 μm that corresponds to at least the thickness of the wall portion  64 . Therefore, there is a concern that an increase in wiring inductance becomes a constraint in a case of turning on and off the light source  20  at a high speed. 
     The light emitter  4  to which the first exemplary embodiment illustrated in  FIGS.  7 A and  7 B  is applied does not include the support section between the light source  20  and the driving section  50 . Therefore, as indicated by an arrow in  FIG.  7 B , there is a concern that the light emitted to the driving section  50  side from the light source  20  is emitted to the outside without being transmitted through the diffusion plate  30 . In particular, there is a concern that the light having a high intensity is emitted to the outside from the VCSEL group  22  that is illustrated being surrounded by broken lines in  FIG.  3    and provided in the end portion on the driving section  50  side of the light source  20 . In addition, light intensity is sometimes referred to as emission intensity. 
     Here, the position of the end portion  33  on the driving section  50  side of the diffusion plate  30  may 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 group  22 , is incident on the diffusion plate  30 . With such setting, the intensity of the light emitted to the outside without being diffused by the diffusion plate  30  is 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 source  20  to the measurement target. 
     Furthermore, the position of the end portion  33  on the driving section  50  side of the diffusion plate  30  may be set such that the light having an intensity (emission intensity) of 0.1% or higher emitted by the VCSEL group  22  is incident on the diffusion plate  30 . With such setting, the intensity of the light emitted to the outside without being diffused by the diffusion plate  30  is 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 source  20  to the measurement target. In this case, when the spread angles of the light emitted by the VSCEL are the same, the diffusion plate  30  may extend to the side on which a support wall of the support section  60  is not provided, that is, the driving section  50  side. 
     Modification Example of Light Emitter  4   
     A modification example of the light emitter  4  to which the first exemplary embodiment illustrated in  FIGS.  7 A and  7 B  is applied will be described. 
     In the light emitter  4 , the diffusion plate  30  covers the light source  20  and the PD  40 , and does not cover the driving section  50 . In the modification example of the light emitter  4  to which the first exemplary embodiment is applied, the diffusion plate  30  covers a part of the driving section  50 . 
       FIGS.  9 A to  9 C  are plan views for illustrating the modification example of the light emitter  4  to which the first exemplary embodiment is applied.  FIG.  9 A  is a light emitter  4 - 1  according to Modification Example 1,  FIG.  9 B  is a light emitter  4 - 2  according to Modification Example 2, and  FIG.  9 C  is a light emitter  4 - 3  according to Modification Example 3. In addition, in  FIGS.  9 A to  9 C , only the light source  20 , the diffusion plate  30 , the PD  40 , the driving section  50 , and the support section  60  are referred to. Further, the same parts as the light emitter  4  illustrated in  FIGS.  7 A and  7 B  will be given the same reference numerals, and the description thereof will be omitted. 
     In the light emitter  4 - 1  according to Modification Example 1 illustrated in  FIG.  9 A , the diffusion plate  30  overhangs to the one end portion on the light source  20  side of the driving section  50  and also covers a part of the driving section  50 . In the light emitter  4 - 2  according to Modification Example 2 illustrated in  FIG.  9 B , the diffusion plate  30  overhangs to the center portion of the driving section  50  and covers the center portion of the driving section  50 . In the light emitters  4 - 1  and  4 - 2 , with the overhang of the diffusion plate  30 , the wall portions  62  and  63  of the support section  60  overhang to the driving section  50  side. In addition, three sides of the diffusion plate  30  are supported by the wall portions  61 ,  62 , and  63  of the support section  60 . The light emitters  4 - 1  and  4 - 2  are applied to a case where a width W C  of the driving section  50  is smaller than a width W y  of the diffusion plate  30 , and more strictly speaking, a distance L D  between the wall portions  62  and  63 . 
     In the light emitter  4 - 3  according to Modification Example 3 illustrated in  FIG.  9 C , the diffusion plate  30  also overhangs to the one end portion of the driving section  50  and covers a part of the driving section  50 . However, the wall portions  62  and  63  of the support section  60  are not provided at the part at which the diffusion plate  30  overhangs on the driving section  50 . In other words, the light emitter  4 - 3  is applied to a case where the width W C  of the driving section  50  is greater than the width W y  of the diffusion plate  30 , and more strictly speaking, the distance L D  between the wall portions  62  and  63 . 
     In the light emitters  4 - 1  to  4 - 3 , three sides of the diffusion plate  30  are supported by the wall portions  61 ,  62 , and  63  of the support section  60 , and the support wall, that is, the support section, is not provided between the light source  20  and the driving section  50 . In addition, as the diffusion plate  30  overhangs on the driving section  50  side, the distance between the VCSEL group  22  provided in the end portion on the driving section  50  side of the light source  20  and the end portion  33  of the diffusion plate  30  becomes greater. Accordingly, light with a high intensity can be easily prevented from being applied from the end portion of the diffusion plate  30 . For example, in a case where the light transmitted through the diffusion plate  30  is equal to or higher than 50%, the light emitter  4 - 1  may be used, and in a case where the light transmitted through the diffusion plate  30  is equal to or higher than 0.1%, the light emitter  4 - 2  may be used, selectively. 
     Second Exemplary Embodiment 
     In a light emitter  4 A to which a second exemplary embodiment is applied, a beam portion provided to extend to the driving section  50  side from the diffusion plate  30  side is provided on the driving section  50  side of the diffusion plate  30 . 
       FIGS.  10 A and  10 B  are views for illustrating the light emitter  4 A to which the second exemplary embodiment is applied.  FIG.  10 A  is a plan view, and  FIG.  10 B  is a sectional view taken along line XB-XB of  FIG.  10 A . The same parts as the light emitter  4  illustrated in  FIGS.  7 A and  7 B  will be given the same reference numerals, and the description thereof will be omitted. 
     As illustrated in  FIG.  10 A , the diffusion plate  30  covers the light source  20  and the PD  40 , and covers a part of the surface of the driving section  50 . In addition, a support section  60 A is provided with the wall portions  61 ,  62 , and  63  for supporting the three sides of the diffusion plate  30  with respect to the substrate  10 . Further, the light emitter  4 A includes a beam portion  65  provided toward the driving section  50  side from the one remaining side of the diffusion plate  30 . As illustrated in  FIG.  10 B , an upper surface (a surface that faces the +z direction) of the beam portion  65  is bonded to the diffusion plate  30 . In addition, in the beam portion  65 , a lower surface on the substrate  10  side (a surface that faces the −z direction) has a distance to the surface (a surface that faces the +z direction) of the driving section  50 . In addition, instead of the beam portion  65 , similar to a beam portion  65 ′ illustrated by broken lines, the beam portion may be in contact with the driving section  50 . 
     The support section  60  (wall portions  61 ,  62 , and  63 ) and the beam portion  65  (beam portion  65 ′) 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 section  60  (wall portions  61 ,  62 , and  63 ) and the beam portion  65  (beam portions  65 ′) formed as a single member will be referred to as the support section  60 A. 
     When the beam portion  65  (beam portion  65 ′) is made of a light absorbing material, light with a high intensity from the VCSEL group  22  of the end portion on the driving section  50  side of the light source  20  is prevented from going outside without being transmitted through the diffusion plate  30 . In other words, as compared with a case where the beam portion  65  ( 65 ′) is not provided, the overhang of the diffusion plate  30  to the driving section  50  side may be reduced. In other words, the area of the diffusion plate  30  is reduced. 
     Further, similar to the beam portion  65 ′, with a configuration in which the lower surface is in contact with the driving section  50 , the diffusion plate  30  is reliably supported by the wall portions  61 ,  62 , and  63  and the beam portion  65 ′ of the support section  60 . In addition, the entry of foreign matters, such as dust or dirt, to the surrounding of the light source  20  is prevented. In addition, since the support section  60 A and the beam portion  65  are formed as a single member, the number of assembling steps can be reduced. 
     Third Exemplary Embodiment 
     In the light emitter  4  to which the first exemplary embodiment is applied, the diffusion plate  30  is supported by the support section  60  with three sides. In a light emitter  4 B to which a third exemplary embodiment is applied, the diffusion plate  30  is supported by a support section  60 B with four sides. 
       FIGS.  11 A and  11 B  are plan views of the light emitter  4 B to which the third exemplary embodiment is applied.  FIG.  11 A  is a plan view, and  FIG.  11 B  is a sectional view taken along line XIB-XIB of  FIG.  11 A . The same parts as the light emitter  4  illustrated in  FIGS.  7 A and  7 B  will be given the same reference numerals, and the description thereof will be omitted. 
     In the light emitter  4 B, the light source  20 , the PD  40 , and the driving section  50  are covered with the diffusion plate  30 . In addition, the support section  60 B includes the wall portions  61 ,  62 ,  63 , and  66 , which support the diffusion plate  30  on four sides and are provided to surround the light source  20 , the PD  40 , and the driving section  50 . In addition, the support section  60 B (wall portions  61 ,  62 ,  63 , and  66 ) is formed as a single member by integral molding. The support section  60 B is made of a light absorbing material. 
     In this case, in the light source  20  of the light emitter  4 B, the optical axial direction side is covered with the diffusion plate  30 , and the side surface side is covered with the support section  60 . Since the support section  60 B is made of the light absorbing material, the light emitted from the light source  20  is prevented from leaking directly to the outside. In addition, since the support section  60 B is formed as a single member, the number of assembling steps can be reduced. 
     Modification Example of Light Emitter  4 B 
     In the light emitter  4 B to which the third exemplary embodiment is applied, the diffusion plate  30  also covers the driving section  50 . In general, in the diffusion plate  30 , the greater the area, the higher the price. In addition, the diffusion plate  30  is not required to cover the driving section  50 . Here, in a light emitter  4 B- 1  which is a modification example of the light emitter  4 B, a blocking section  67  for blocking the transmission of the light is provided at a part of the upper side of the support section  60 B of the light emitter  4 B, and the area of the diffusion plate  30  is reduced. 
       FIGS.  12 A and  12 B  are views for illustrating the light emitter  4 B- 1  which is the modification example of the light emitter  4 B to which the third exemplary embodiment is applied.  FIG.  12 A  is a plan view, and  FIG.  12 B  is a sectional view taken along line XIIB-XIIB of  FIG.  12 A . The same parts as the light emitter  4 B illustrated in  FIGS.  11 A and  11 B  will be given the same reference numerals, and the description thereof will be omitted. 
     In the light emitter  4 B- 1 , the diffusion plate  30  is provided only on the optical axial direction side of the light source  20 , and the driving section  50  is not covered with the diffusion plate  30  and is covered with the blocking section  67 . As illustrated in  FIG.  12 A , similar to the support section  60 B of the light emitter  4 B, the light emitter  4 B- 1  is provided with the wall portions  61 ,  62 ,  63 , and  66 . In addition, the blocking section  67  is provided at a part of an upper opening of the support section  60 B ( FIG.  12 A ). The blocking section  67  is on the wall portion  66  side so as to not to block the light emitted from the light source  20  and transmitted through the diffusion plate  30 , and is provided to cover the driving section  50 . In addition, the surface (a surface that faces the +z direction) of the blocking section  67  is formed as a surface flush with the surfaces of the wall portions  61 ,  62 ,  63 , and  66 . Further, the rear surface (a surface that faces the −z direction) of the blocking section  67  is provided not to be in contact with the driving section  50 . In addition, the support section  60  (wall portions  61 ,  62 ,  63 , and  66 ) and the blocking section  67  are formed as a single member by the integral molding. The diffusion plate  30  is bonded and fixed to the wall portion  61  side which is a part of the upper surfaces of the wall portions  61 ,  62 , and  63  and the surface of the blocking section  67 . In other words, the diffusion plate  30  is provided so as to seal the opening made by the wall portions  61 ,  62 , and  63  and the blocking section  67 . In this manner, the support section  60 B and the blocking section  67  which became a single member are referred to as a support section  60 B- 1 . 
     Even in the light emitter  4 B- 1 , in the light source  20 , the optical axial direction side is covered with the diffusion plate  30 , and the side surface side is covered with the support section  60 B- 1 . Since the support section  60 B- 1  includes the light absorbing material, the light emitted from the light source  20  is prevented from leaking directly to the outside. In addition, as compared with the diffusion plate  30  of the light emitter  4 B, the area of the diffusion plate  30  becomes smaller. Accordingly, the price of the optical device  3  is reduced. In addition, since the support section  60 B (wall portions  61 ,  62 ,  63 , and  66 ) and the blocking section  67  are formed as a single member, the number of assembling steps can be reduced. 
     Fourth Exemplary Embodiment 
     In the light emitters  4  and  4 - 1  to  4 - 3  to which the first exemplary embodiment is applied, the light emitter  4 A to which the second exemplary embodiment is applied, and the light emitters  4 B and  4 B- 1  to which the third exemplary embodiment is applied, the wall portion, that is, the support section, is not provided between the light source  20  and the driving section  50 . The light emitter  4 C to which the fourth exemplary embodiment is applied includes a support section  60 C provided with a wall portion  68  between the light source  20  and the driving section  50 . 
       FIGS.  13 A and  13 B  are views for illustrating the light emitter  4 C to which the fourth exemplary embodiment is applied.  FIG.  13 A  is a plan view, and  FIG.  13 B  is a sectional view taken along line XIIIB-XIIIB of  FIG.  13 A . The same parts as the light emitter  4  illustrated in  FIGS.  7 A and  7 B  will be given the same reference numerals, and the description thereof will be omitted. 
     The support section  60 C of the light emitter  4 C includes the wall portions  61 ,  62 , and  63  provided on the three sides of the diffusion plate  30 , and the wall portion  68  on the one remaining side. In addition, the wall portions  61 ,  62 , and  63  and the wall portion  68  are different from each other in thickness. Specifically, the thickness t2 of the wall portion  68  is smaller than the thickness t1 of the wall portions  61 ,  62 , and  63  (t1&gt;t2). The thick wall portions  61 ,  62 , and  63  and a thin wall portion  68  support the diffusion plate  30 . In addition, the thickness of the wall portion  68  may be set so as to reduce any influence on the inductance of the wiring that connects the light source  20  and the driving section  50  to each other. When the wall portion  68  is provided, the light from the light source  20  is prevented from going outside without passing through the diffusion plate  30 . Further, since the light source  20  is surrounded by the support section  60 C and the diffusion plate  30 , the entry of foreign matter, such as dust or dirt, to the surrounding of the light source  20  is prevented. 
     The support section  60 C became a single member to which the wall portions  61 ,  62 ,  63 , and  68  are 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 apparatus  1  that uses the light emitters  4  and  4 - 1  to  4 - 3  to which the first exemplary embodiment is applied, the light emitter  4 A to which the second exemplary embodiment is applied, the light emitters  4 B and  4 B- 1  to which the third exemplary embodiment is applied, and the light emitter  4 C to which the fourth exemplary embodiment is applied, will be described. In addition, the information processing apparatus  1  is an example of a light emitting device. 
     Sectional Structure of Information Processing Apparatus  1   
     Here, the sectional structure of the information processing apparatus  1  will be described while the information processing apparatus  1  uses the light emitter  4  to which the first exemplary embodiment is applied. In addition, the same will also be applied to a case of using other light emitters. 
       FIG.  14    is a view for illustrating the sectional structure of the information processing apparatus  1  that uses the light emitter  4 . The information processing apparatus  1  includes the optical device  3  and a housing  100 . As described above, the optical device  3  includes the light emitter  4  and the 3D sensor  5 . In other words, the housing  100  accommodates the light emitter  4 . Here, similar to the light emitter  4  illustrated in  FIGS.  7 A and  7 B , the 3D sensor  5  is mounted on the substrate  10  provided in the light emitter  4 . 
     The housing  100  includes a transmission section plate  110  through which the light emitted from the light source  20  in the light emitter  4  is transmitted, and a transmission section plate  120  through which the light received by the 3D sensor  5  is transmitted. The transmission section plate  110  is provided at a part that corresponds to a region where the light source  20  emits the light, and the transmission section plate  120  is provided at a part that corresponds to a region where the 3D sensor  5  receives the light. The housing  100  includes, for example, a metal material, such as aluminum or magnesium, or a resin material. In addition, the transmission section plates  110  and  120  each include a transparent material, such as glass or acrylic. 
     The substrate  10  is held by substrate holding means  101  for holding the substrate  10  with respect to the housing  100 . In addition, on the 3D sensor  5 , a lens  130  for converging the light transmitted through the transmission section plate  120  to the 3D sensor  5 , is provided. The lens  130  is held by lens holding means  131  for holding the lens  130  with respect to the substrate  10 . The substrate holder  101  is, for example, a fastener, such as a screw, or a fitting member, which is made of resin or the like. 
     In the information processing apparatus  1 , the distance between the light source  20  and the driving section  50  of the light emitter  4  is set to be smaller than the distance between the light source  20  and the transmission section plate  110 . 
     In addition, the transmission section plate  120  may have a function of the lens  130 . 
     After being transmitted through the diffusion plate  30 , the light emitted from the light source  20  of the light emitter  4  is transmitted through the transmission section plate  110  and is applied to the measurement target. 
     When the light emitter  4  (optical device  3 ) is accommodated in the housing  100  in this manner, the diffusion plate  30  is prevented from being damaged. In other words, application of high-intensity light directly to the outside due to damage to the diffusion plate  30  is prevented. 
     In the above-described first to fifth exemplary embodiments, the diffusion plate  30  of 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 plate  30 , 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. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.