JP2020067459A - Display unit, display system, and movable body - Google Patents

Abstract

To provide a display unit that appropriately detects scan light.SOLUTION: A display unit comprises: a light source device that has a light source element, and when the light source element is supplied with a current and lighted up, emits a laser beam output from the light source element; a scanning unit that displays an image with scan light obtained by two-dimensionally scanning the laser beam; and a light detection unit that receives the scan light. The display unit can execute time control of controlling received light quantity that is the quantity of light received by the light detection unit, with a time interval to light up the light source element while a predetermined amount of the current is supplied thereto, and the time interval when scanning the light detection unit is different according to the received light quantity.SELECTED DRAWING: Figure 17

Description

  The present invention relates to a display device, a display system and a moving body.

  In a moving body such as a vehicle, a display device such as a HUD (Head Up Display) is used as an application for allowing a driver (observer) to visually recognize various information (vehicle information, warning information, navigation information, etc.) with a small amount of eye movement. ing.

  For example, in Patent Document 1, a light source that emits light when a current is supplied and that emits laser light when a current of a threshold current value or more is supplied, and a current is supplied to the light source based on light intensity characteristics. A light source control unit that drives the light source and an external light detection unit that detects the intensity of external light are provided, and the light intensity characteristic indicates a relationship between a current supplied to the light source and a light intensity of the light source. The light source control means is represented as a straight line, and has a first straight line including a current value less than the threshold current value and a second straight line including a current value greater than or equal to the threshold current value. When the external light intensity detected by the detection means is less than a predetermined value, the initial current value is set to zero, and the drive corresponding to the required light intensity is performed based on the first straight line or the second straight line. A laser light source driving device is characterized by supplying an electric current to the light source. It is.

  An object of the present invention is to provide a display device that can appropriately detect scanning light.

  In order to solve the above-mentioned problems, the invention according to claim 1 has a light source device, a light source device that emits laser light that is output when the light source device to which a current is supplied is turned on, and the laser light. A scanning unit that displays an image by scanning light that is two-dimensionally scanned, and a photodetector that receives the scanning light, and the light source element is turned on in a state in which a predetermined amount of current is supplied by the time interval. The display device is capable of performing time control for controlling the amount of received light, which is the amount of light received by the photodetector, and the time interval when scanning the photodetector varies depending on the amount of received light.

  According to the present invention, it is possible to provide a display device capable of appropriately detecting scanning light.

It is a figure which shows an example of the system configuration of the display system which concerns on 1st Embodiment. It is a figure which shows an example of the hardware constitutions of the display apparatus which concerns on 1st Embodiment. It is a figure which shows an example of a function structure of the control apparatus which concerns on 1st Embodiment. It is a figure which shows an example of the specific structure of the light source device which concerns on 1st Embodiment. It is a figure which shows an example of the specific structure of the optical deflection apparatus which concerns on 1st Embodiment. It is a figure which shows an example of a specific structure of the screen which concerns on 1st Embodiment. It is a figure for demonstrating the difference in an operation | movement by the difference in the magnitude relationship of an incident light beam diameter and a lens diameter in a micro lens array. It is a figure which shows an example of a specific structure of the light amount adjustment apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the correspondence of the mirror of a light deflection device, and a scanning range. It is a figure which shows an example of the scanning line locus at the time of two-dimensional scanning. It is a figure which shows an example of a concrete structure of a photon detection part. It is a figure for demonstrating the synchronizing signal which a photon detection part outputs. It is a figure for input in order to explain the relationship between the amount of laser light incident on the photodetection section and the fluctuation of the synchronization signal timing. It is a figure for demonstrating the input / output characteristic (driving current-output characteristic) of a laser. It is a figure for demonstrating the relationship between the drive current of a laser, and the laser incident light quantity to a photon detection part. It is a figure for demonstrating setting of the time interval of the laser drive time according to the amount of incident laser light. It is a figure explaining the light amount control which concerns on 1st Embodiment. It is a figure for demonstrating the setting of the time interval according to a time constant. It is a figure explaining the light amount control which concerns on 2nd Embodiment. It is a flowchart which shows a light amount control flow.

  Hereinafter, modes for carrying out the invention will be described with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

System Configuration FIG. 1 is a diagram showing an example of the system configuration of the display system according to the first embodiment. The display system 1 shown in FIG. 1 has an image having a good brightness distribution while suppressing a decrease in brightness at the end of the image (virtual image 45) visually recognized by the observer 3 and a decrease in brightness when the observer moves the viewpoint. Is a system that allows the observer 3 to visually recognize.

  The display system 1 causes the observer 3 to visually recognize the display image by projecting the projection light projected from the display device 10 onto the transmissive reflection member. The display image is an image displayed as a virtual image 45 superimposed on the field of view of the observer 3. The display system 1 is provided, for example, in a moving body such as a vehicle, an aircraft or a ship, or a non-moving body such as an operation simulation system or a home theater system. In the present embodiment, a case will be described where the display system 1 is provided in an automobile, which is an example of a moving body. Note that the usage pattern of the display system 1 is not limited to this.

  The display system 1 uses, for example, navigation information (for example, vehicle speed, route information, distance to a destination, current location name, presence / absence of an object (object) in front of the vehicle) necessary for operating the vehicle via the windshield 50. The observer 3 (pilot) visually recognizes a position, a speed limit, and other signs, traffic jam information, and the like). In this case, the windshield 50 functions as a transflective member that transmits a part of the incident light and reflects at least a part of the remaining light. The distance from the viewpoint of the observer 3 to the windshield 50 is about several tens of cm to 1 m.

  The display system 1 includes a display device 10, an external light sensor 20, a free-form curved mirror 30, and a windshield 50. The display device 10 is, for example, a head-up display device (HUD device) mounted on an automobile, which is an example of a moving body. The display device 10 is arranged at an arbitrary position according to the interior design of the automobile. The display device 10 may be arranged, for example, below a dashboard of an automobile, or may be embedded in the dashboard.

  The display device 10 includes a light source device 11, a light deflection device 13, a screen 15, and a light amount adjustment device 16. The light source device 11 is a device that irradiates the laser light emitted from the light source to the outside of the device. The light source device 11 may irradiate, for example, a laser beam obtained by combining laser beams of three colors of R, G, and B. The external light sensor 20 is a sensing device provided for detecting the external light intensity of the display system 1, for example, the illuminance. As shown in FIG. 1, the external light sensor 20 is installed, for example, near the windshield 50.

  The laser light emitted from the light source device 11 enters a light amount adjusting device 16 as an example of a light amount adjusting unit. The light amount adjusting device 16 adjusts the light amount of the incident laser light. The laser light that has passed through the light quantity adjusting device 16 is guided to the reflecting surface of the light deflecting device 13.

  The light deflector 13 as an example of the light deflector is a device that changes the traveling direction of the laser light by using a MEMS (Micro Electro Mechanical Systems) or the like. The optical deflecting device 13 includes, for example, a scanning unit such as a single minute MEMS mirror that swings about two orthogonal axes, or a mirror system that includes two MEMS mirrors that swing or rotate about one axis. It is configured by using. The laser light emitted from the light deflector 13 is scanned on the screen 15. The light deflection device 13 is not limited to the MEMS mirror, and may be configured using a polygon mirror or the like.

  The screen 15 is a diverging member having a function of diverging the laser light at a predetermined divergence angle. The screen 15 is formed of a transmission type optical element having a light diffusion effect, such as a microlens array (MLA) or a diffusion plate, in the form of an EPE (Exit Pupil Expander). The screen 15 may be composed of a reflective optical element having a light diffusion effect such as a micromirror array. The screen 15 forms an intermediate image 40, which is a two-dimensional image, on the screen 15 by scanning the laser light emitted from the optical deflector 13 onto the screen 15.

  The light amount adjusting device 16 has a predetermined light transmittance and is arranged on the optical path of the laser light, and changes the light amount of the light passing through the light amount adjusting device 16. As a result, the brightness of the intermediate image 40 and the virtual image 45 is adjusted. If the external light is dark, for example, the light amount adjusting device 16 raises the transmittance to reduce the light amount of the transmitted light to darken the formed image based on the detection result of the external light sensor 20. If the external light is bright, the transmittance is decreased to increase the amount of light that is transmitted, so that the formed image is brightened.

  Here, the projection system of the display device 10 is a “panel system” in which an intermediate image 40 is formed by an imaging device such as a liquid crystal panel, a DMD panel (digital mirror device panel), or a fluorescent display tube (VFD), and a light source device 11 emits light. There is a "laser scanning method" in which the scanning means scans the generated laser light to form an intermediate image 40.

  The display device 10 according to the first embodiment employs the latter “laser scanning method”. In the “laser scanning method”, light emission or non-light emission can be assigned to each pixel, and thus a high-contrast image can be generally formed. The display device 10 may use a “panel method” as a projection method.

  The virtual image 45 projected on the free-form surface mirror 30 and the windshield 50 by the laser light (light flux) emitted from the screen 15 is enlarged and displayed from the intermediate image 40. The free-form curved mirror 30 is designed and arranged so as to cancel the inclination, distortion, positional deviation, etc. of the image due to the curved shape of the windshield 50. The free-form surface mirror 30 may be installed rotatably around a predetermined rotation axis. Thereby, the free-form surface mirror 30 can adjust the reflection direction of the laser light (light flux) emitted from the screen 15 and change the display position of the virtual image 45.

  Here, the free-form surface mirror 30 is designed using existing optical design simulation software so that the image formation position of the virtual image 45 is at a desired position and has a constant condensing power. The display device 10 sets the condensing power of the free-form surface mirror 30 so that the virtual image 45 is displayed at a position (depth position) that is, for example, 1 m or more and 30 m or less (preferably 10 m or less) from the viewpoint position of the observer 3. To be done. The free-form curved mirror 30 may be a concave mirror or a curved mirror. The free-form surface mirror 30 is an example of an imaging optical system.

  The windshield 50 is a transflective member having a function (partial reflection function) of transmitting a part of laser light (light flux) and reflecting at least a part of the rest. The windshield 50 functions as a semi-transparent mirror that allows the observer 3 to visually recognize the front scene and the virtual image 45. The virtual image 45 is image information for allowing the observer 3 to visually recognize vehicle information (speed, mileage, etc.), navigation information (route guidance, traffic information, etc.), warning information (collision warning, etc.), for example. The transflective member may be a windshield or the like provided separately from the windshield 50. The windshield 50 is an example of a reflecting member.

  The virtual image 45 may be displayed so as to overlap with the scenery in front of the windshield 50. Further, the windshield 50 is not flat but curved. Therefore, the image forming position of the virtual image 45 is determined by the curved surfaces of the free-form surface mirror 30 and the windshield 50. The windshield 50 may use a semi-transmissive mirror (combiner) as an individual transflective member having a partial reflection function.

  With such a configuration, the laser light (light flux) emitted from the screen 15 is projected toward the free-form surface mirror 30 and reflected by the windshield 50. The observer 3 can visually recognize the virtual image 45 in which the intermediate image 40 formed on the screen 15 is enlarged by the light reflected by the windshield 50.

Hardware Configuration FIG. 2 is a diagram showing an example of the hardware configuration of the display device according to the first embodiment. The hardware configuration shown in FIG. 2 may have the same configuration in each embodiment, and constituent elements may be added or deleted as necessary.

  The display device 10 has a control device 17 for controlling the operation of the display device 10. The control device 17 is a controller such as a board or an IC chip mounted inside the display device 10. The control device 17 includes an FPGA (Field-Programmable Gate Array) 1001, a CPU (Central Processing Unit) 1002, a ROM (Read Only Memory) 1003, a RAM (Random Access Memory) 1004, an I / F (Interface) 1005, and a bus line 1006. , LD driver 1008, MEMS controller 1010, motor 1011 and motor driver 1012.

  The FPGA 1001 is an integrated circuit whose setting can be changed by the designer of the display device 10. The LD driver 1008, the MEMS controller 1010, the motor driver 1012, and the motor driver 1014 generate drive signals according to the control signals from the FPGA 1001. The CPU 1002 is an integrated circuit that performs processing for controlling the entire display device 10. The ROM 1003 is a storage device that stores a program that controls the CPU 1002. The RAM 1004 is a storage device that functions as a work area for the CPU 1002. The I / F 1005 is an interface for communicating with an external device. The I / F 1005 is connected to, for example, a CAN (Controller Area Network) of an automobile.

  The LD 1007 is, for example, a semiconductor light emitting element that forms a part of the light source device 11. The LD driver 1008 is a circuit that generates a drive signal that drives the LD 1007. The MEMS 1009 is a device that constitutes a part of the optical deflector 13 and displaces the scanning mirror. The MEMS controller 1010 is a circuit that generates a drive signal that drives the MEMS 1009. The motor 1011 is an electric motor that rotates the rotating shaft of the free-form curved mirror 30. The motor driver 1012 is a circuit that generates a drive signal that drives the motor 1011. The filter drive motor 1013 is an electric motor that moves the position of the filter unit that transmits the light emitted from the light source device 11. The motor driver 1014 is a circuit that generates a drive signal that drives the filter drive motor 1013.

Functional Configuration FIG. 3 is a diagram showing an example of the functional configuration of the display device according to the first embodiment. The functions implemented by the display device 10 include a vehicle information reception unit 171, an external information reception unit 172, an image generation unit 173, an image display unit 174, a storage / readout unit 178, and a storage unit 179.

  The vehicle information receiving unit 171 has a function of receiving vehicle information (information such as speed and mileage) from a CAN or the like. The vehicle information receiving unit 171 is realized by the processing of the I / F 1005 and the CPU 1002 shown in FIG. 2, the program stored in the ROM 1003, and the like.

  The external information receiving unit 172 has a function of receiving information on the outside of the vehicle (position information from GPS, route information or traffic information from the navigation system, etc.) from the external network. The external information receiving unit 172 is realized by the processing of the I / F 1005 and the CPU 1002 shown in FIG. 2, the program stored in the ROM 1003, and the like.

  The image generation unit 173 has a function of generating image information for displaying the intermediate image 40 and the virtual image 45 based on the information input by the vehicle information reception unit 171 and the external information reception unit 172. The image generation unit 173 is realized by the processing of the CPU 1002 shown in FIG. 2, the program stored in the ROM 1003, and the like.

  The image display unit 174 forms the intermediate image 40 on the screen 15 based on the display information generated by the image generation unit 173, and projects the laser light (light flux) forming the intermediate image 40 toward the windshield 50. Function to display the virtual image 45. The image display unit 174 is realized by the processing of the CPU 1002, the FPGA 1001, the LD driver 1008, the MEMS controller 1010 and the motor driver 1012, the motor driver 1014 shown in FIG. 2, the program stored in the ROM 1003, and the like.

  The image display unit 174 includes a control unit 175, an intermediate image forming unit 176, and a projection unit 177. The control unit 175 generates a control signal for controlling the operations of the light source device 11 and the light deflecting device 13 in order to form the intermediate image 40. The control unit 175 also generates a control signal for controlling the operation of the free-form surface mirror 30 in order to display the virtual image 45 at a predetermined position.

  The intermediate image forming unit 176 forms the intermediate image 40 on the screen 15 based on the control signal generated by the control unit 175. The projection unit 177 projects the laser light forming the intermediate image 40 onto the transmissive / reflecting member (the windshield 50 or the like) in order to form the virtual image 45 visually recognized by the observer 3.

  The storage / readout unit 178 has a function of storing various data in the storage unit 179 or reading out various data from the storage unit 179. As an example, the storage unit 179 stores various condition data and the like necessary for controlling the display system 1 in advance.

Light Source Device FIG. 4 is a diagram showing an example of a specific configuration of the light source device according to the first embodiment. The light source device 11 includes light source elements 111R, 111G, and 111B (hereinafter, referred to as light source element 111 when there is no need to distinguish them), coupling lenses 112R, 112G, and 112B, apertures 113R, 113G, and 113B, and a combining element 114. , 115, 116, a light branching element 117, a lens 118, and a photodetector 119.

  The three-color (R, G, B) light source elements 111R, 111G, 111B are, for example, LDs (Laser Diodes) each having a single or a plurality of light emitting points. The light source elements 111R, 111G, and 111B radiate the laser light of the light amount corresponding to the change of the drive current supplied to each light source element. The light source elements 111R, 111G, and 111B emit laser beams (light fluxes) having different wavelengths λR, λG, and λB (for example, λR = 640 nm, λG = 530 nm, λB = 445 nm).

  The emitted laser beams (light fluxes) are coupled by coupling lenses 112R, 112G, and 112B, respectively. The coupled lasers (light fluxes) are shaped by the apertures 113R, 113G, 113B, respectively. The apertures 113R, 113G, 113B have a shape (for example, a circle, an ellipse, a rectangle, a square, etc.) according to a predetermined condition such as a divergence angle of the laser light (light flux).

  The respective laser lights (light fluxes) shaped by the apertures 113R, 113G, 113B are combined by the three combining elements 114, 115, 116. The combining elements 114, 115, and 116 are plate-shaped or prism-shaped dichroic mirrors, which reflect or transmit the laser light (light flux) according to the wavelength and are combined into one light flux, and the combined light flux is an optical branching element. It is incident on 117.

  Part of the incident light that has entered the light branching element 117 is transmitted through the light branching element 117, and the other part is reflected by the light branching element 117. That is, the combined light flux is split by the light splitting element 117 into transmitted light and reflected light.

  The transmitted light passes through the lens 118 and is applied to the light deflector 13, and is used for image drawing and virtual image display on the screen 15. That is, the transmitted light is used as image light.

  On the other hand, the reflected light is applied to the photodetector 119. The photodetector 119 outputs an electric signal according to the intensity of the irradiated laser. The output electric signal is output to the FPGA 1001 as an example, and can be used for controlling the display system 1. In this way, the reflected light is used as monitor light for adjusting the intensity of the laser light and as monitor light for adjusting the color and brightness of the virtual image displayed as a result.

Optical Deflection Device FIG. 5 is a diagram showing an example of a specific configuration of the optical deflection device according to the first embodiment. The light deflection device 13 is a MEMS mirror manufactured by a semiconductor process, and includes a mirror 130, a meandering beam portion 132, a frame member 134, and a piezoelectric member 136. The light deflection device 13 is an example of a scanning unit.

  The mirror 130 has a reflecting surface that reflects the laser light emitted from the light source device 11 toward the screen 15 side. The light deflecting device 13 forms a pair of meandering beam portions 132 with the mirror 130 interposed therebetween. The meandering beam portion 132 has a plurality of folded portions. The folded portion includes first beam portions 132a and second beam portions 132b that are alternately arranged. The meandering beam portion 132 is supported by the frame member 134. The piezoelectric member 136 is arranged so as to connect the adjacent first beam portion 132a and second beam portion 132b. The piezoelectric member 136 applies different voltages to the first beam portion 132a and the second beam portion 132b to cause the beam portions 132a and 132b to warp.

  As a result, the adjacent beam portions 132a and 132b bend in different directions. The mirror 130 rotates in the vertical direction about the axis in the left-right direction by accumulating the bending. With such a configuration, the optical deflecting device 13 can perform optical scanning in the vertical direction at a low voltage. Optical scanning in the horizontal direction about the vertical axis is performed by resonance using a torsion bar or the like connected to the mirror 130.

Screen FIG. 6 is a diagram showing an example of a specific configuration of the screen according to the first embodiment. The screen 15 forms an image of the laser light emitted from the LD 1007 forming a part of the light source device 11. The screen 15 is a diverging member that diverges at a predetermined divergence angle. The screen 15 shown in FIG. 6 has a microlens array structure in which a plurality of hexagonal microlenses 150 are arranged without gaps. The width of the microlens 150 (distance between two opposing sides) is about 200 μm. The screen 15 can arrange a plurality of microlenses 150 at high density by making the shape of the microlenses 150 hexagonal.

  The shape of the microlens 150 is not limited to the hexagon, and may be, for example, a quadrangle or a triangle. Further, although the structure in which the plurality of microlenses 150 are regularly arranged is illustrated, the arrangement of the microlenses 150 is not limited to this, and for example, the centers of the respective microlenses 150 are eccentric to each other and irregular. It may be an arbitrary array. When adopting such an eccentric arrangement, each microlens 150 has a different shape.

  FIG. 7 is a diagram for explaining the difference in action due to the difference in magnitude relationship between the incident light beam diameter and the lens diameter in the microlens array. In FIG. 7A, the screen 15 is composed of an optical plate 151 on which microlenses 150 are aligned. When the incident light 152 is scanned on the optical plate 151, the incident light 152 is diverged by the microlens 150 and becomes divergent light 153. Due to the structure of the microlens 150, the screen 15 can diverge the incident light 152 at a desired divergence angle 154. The period 155 of the microlens 150 is designed to be larger than the diameter 156a of the incident light 152. As a result, the screen 15 does not cause interference between lenses and does not generate speckle (speckle noise).

  FIG. 7B shows an optical path of divergent light when the diameter 156b of the incident light 152 is twice as large as the period 155 of the microlens 150. Incident light 152 is incident on the two microlenses 150a and 150b, and diverges light 157 and 158, respectively. At this time, since two divergent lights exist in the region 159, light interference may occur. When this interference light enters the eyes of the observer, it is visually recognized as speckle.

  In consideration of the above, in order to reduce the speckle, the cycle 155 of the microlens 150 is designed to be larger than the diameter 156 of the incident light. Although FIG. 7 has been described in the form of a convex lens, the same effect can be obtained in the form of a concave lens.

  FIG. 8 is a diagram showing an example of a specific configuration of the light amount adjustment device according to the first embodiment. At least a part of the light quantity adjusting device 16 is provided on the optical path of the laser light emitted from the light source device 11. L in FIG. 8 indicates a laser beam with which the light quantity adjusting device 16 is irradiated.

  The light amount adjustment device 16 includes a filter unit 161. The filter portion is made of a material whose light transmittance is appropriately selected. In this embodiment, the filter unit includes three ND filters 1611, 1612, 1613 having different transmittances. In the present embodiment, as an example, the filters 1611, 1612, and 1613 have transmittances of 100%, 50%, and 10%, respectively. The filter portion 161 is slid in the left-right direction in FIG. 8 by driving the filter drive motor 1013. As a result, the light quantity adjusting device 16 switches which of the filters 1611, 1612, and 1613 the laser light is transmitted through. That is, the transmittance of the filter 1611 is 100% in the case of FIG. 8A, the transmittance of the filter 1612 is 50% in the case of FIG. 8B, and the transmittance of the filter 1613 is in the case of FIG. 8C. The rate of 10% is the transmittance of the filter unit 161 and the light amount adjusting device 16. By thus selecting and switching a plurality of filters having different transmittances, the light transmittance of the light amount adjusting device 16 can be selected and switched.

  Although the case where three ND (Neutral Density) filters having different transmittances are used as the light quantity adjusting device 16 has been described, the invention is not limited to this, and a gradation type filter whose transmittance changes continuously and a polarization angle are adjusted. Therefore, a configuration for adjusting the light amount may be applied. The filter unit 161 has one filter, and the transmittance of the light quantity adjusting device 16 can be changed by switching the presence or absence of the filter on the optical path.

  In this way, the light quantity adjusting device 16 adjusts the light quantity of the laser light transmitted through the light quantity adjusting device 16. When the light amount adjusting device 16 adjusts the light amount of the laser light, the light amounts of the intermediate image 40 and the virtual image 45 displayed on the display system 1 are also adjusted. As a result, the brightness of the virtual image 45 that the observer 3 feels is changed.

  FIG. 9 is a diagram for explaining the correspondence between the mirrors of the optical deflector and the scanning range. The light emission intensity, lighting timing, and optical waveform of each light source element 111 of the light source device 11 are controlled by the FPGA 1001. Each light source element 111 of the light source device 11 is driven by the LD driver 1008 and emits a laser beam. As shown in FIG. 9, the laser light emitted from each light source element 111 and combined in the optical path is two-dimensionally deflected around the α axis and the β axis by the mirror 130 of the optical deflecting device 13, and passes through the mirror 130. The screen 15 is irradiated with scanning light. That is, the screen 15 is two-dimensionally scanned by the main scanning and the sub-scanning by the light deflecting device 13. At this time, the laser light emitted from the light source device 11 passes through the light amount adjusting device 16 and then enters the light deflecting device 13. Therefore, the light amount of the scanning light emitted from the light deflecting device 13 is adjusted by the light amount adjusting device 16.

  The scanning range is the entire range that can be scanned by the optical deflector 13. The scanning light vibrates (reciprocally scans) in the main scanning direction (X-axis direction) in the scanning range of the screen 15 at a fast frequency of about 20 to 40,000 Hz, and at a slow frequency of about several tens of Hz in the sub-scanning direction. One-way scanning is performed in the (Y-axis direction). That is, the light deflecting device 13 performs raster scanning on the screen 15. In this case, the display device 10 can perform drawing or virtual image display for each pixel by controlling light emission of each light source element 111 according to the scanning position (position of scanning light).

  The time for drawing one screen, that is, the scanning time for one frame (one cycle of two-dimensional scanning) is several tens of msec because the sub-scanning cycle is several tens Hz as described above. For example, when the main scanning cycle is 20000 Hz and the sub-scanning cycle is 50 Hz, the scanning time for one frame is 20 msec.

  FIG. 10 is a diagram showing an example of a scanning line locus during two-dimensional scanning. As shown in FIG. 10, the screen 15 has an image region R1 (effective scanning region) in which an intermediate image 40 is drawn (irradiated with light modulated according to image data) and a non-image other than the image region R1. The region R2 is included. The non-image area is, for example, a frame-shaped area surrounding the image area R1.

  The scanning range is a range in which the image region R1 and a part of the non-image region R2 on the screen 15 (portion near the outer edge of the image region R1) are combined. In FIG. 10, the loci of scanning lines in the scanning range are indicated by zigzag lines. In FIG. 9, the number of scanning lines is smaller than the actual number for convenience.

  As described above, the screen 15 is composed of a transmissive optical element having a light diffusion effect, such as the microlens array 200. The image region R1 does not have to be rectangular or flat, but may be polygonal or curved. The screen 15 can also be a reflective optical element having a light diffusion effect, such as a micromirror array, depending on the device layout. In the following description, the present embodiment will be described assuming that the screen 15 is configured by the microlens array 200.

  The screen 15 includes a photodetection sensor 60, which is a photodetector, in a peripheral region (a part of the non-image region R2) of the image region R1 in the scanning range. The light detection sensor 60 receives the scanning light and detects the amount of light received, which is the amount of light received. In FIG. 10, the light detection sensor 60 is arranged in the −X side and + Y side corners of the image region R1. The light detection sensor 60 detects the operation of the light deflection device 13 by detecting the amount of received scanning light, and outputs a synchronization signal for determining the scan start timing and the scan end timing to the FPGA 1001.

  FIG. 11 is a diagram showing an example of a specific configuration of the photodetector unit according to the first embodiment. A light detection sensor 60, which is an example of a light detection unit, includes a PD (Photo Diode) 61 for converting the received laser into an electric signal, and an integrated circuit 62 as an electric circuit. The integrated circuit 62 has a current amplifier 621 for amplifying the converted weak electric signal, a gain resistor 622 for converting the output current from the current amplifier 621 into a voltage, and the voltage-converted signal as a reference voltage (hereinafter, Vref). A comparator 623 for comparing and outputting a synchronization signal based on the comparison result is provided. Although the output destination of the synchronization signal is the FPGA 1001 in FIG. 11 as an example, the output destination is not limited to this, and may be the light source device 11 or the like.

  FIG. 12 is a diagram for explaining the synchronization signal output by the photodetector. When the light receiving surface of the PD 61 is scanned with laser light, a voltage conversion signal is input to the comparator 623 according to the intensity of the received light. When the value of the input voltage conversion signal is higher than the predetermined voltage value Vref, the Low signal is output from the comparator 623, and when it is lower than Vref, the High signal is output. The output signal from the comparator 623 is output to the FPGA 1001. By monitoring the timing at which the output signal from the comparator 623 changes from High to Low, the FPGA 1001 can grasp the timing at which the laser light, which is the scanning light, scans the light detection sensor 60. Therefore, it is possible to detect the operation of the light deflecting device 13, determine the scanning start timing and the scanning end timing, and use it as a synchronization signal for synchronizing the operation of the light deflecting device 13 with the operation of another device.

  FIG. 13 is a diagram for explaining the relationship between the amount of laser light incident on the photodetector and the variation in the synchronization signal timing. FIG. 13 shows a comparator input signal when the amount of received light is 1, the amount of light 1, the amount of light 2, and the amount of light 3 per unit time, and the synchronization signal 1, the synchronization signal 2, and the synchronization signal 3 which are output at each time. When the laser with the largest light amount 1 and the laser with the smallest light amount 3 are scanned, the timing at which the Low signal changes to the High signal, that is, the output timing fluctuation (ΔT) of the synchronization signal due to the change in the input signal to the comparator. Occur. That is, even if the scanning timing by the light deflector 13 is the same, the timing at which the photodetection sensor 60 outputs the synchronization detection signal changes according to the amount of laser light received by the PD 61. Since the display image shifts due to this timing fluctuation, the light amount of the laser light received by the light detection sensor 60 is required to have high accuracy.

  FIG. 14 is a diagram for explaining the input / output characteristics of the laser (current amount of laser driving current-laser output light amount characteristic). A laser generally has an input / output characteristic as shown in FIG. Therefore, the amount of drive current supplied to the light source element 111 can be adjusted to adjust the amount of laser light emitted from the light source device 11, and as a result, the amount of light received by the light detection sensor 60 can be controlled. As an example, the present display device can execute light amount control (hereinafter also referred to as current control) by the amount of current supplied to the light source element 111 by the image display unit 174.

  As shown in FIG. 14, a first region (hereinafter, LED region) in which the output intensity of light gradually increases and decreases with an increase and a decrease in current amount, and a second region (hereinafter, LD region) in which the output intensity of light rapidly increases and decreases. Then, there is a change point (hereinafter, Ith) between the first area and the second area. Since Ith is affected (changes) by the temperature, it is difficult to control the received light amount of the photodetection sensor 60 with high accuracy if the amount of current in the range that can be Ith (Ith region) is used. Therefore, it is preferable that the current in the Ith region does not use the synchronization signal for the photodetection sensor 60 that requires high optical output accuracy. In the following description of the graph, illustration of the Ith area may be omitted.

  FIG. 15 is a diagram for explaining the relationship between the laser drive current and the amount of laser incident light on the photodetector. FIG. 15 shows the amount of laser light incident on the light detection sensor 60 when the laser output characteristics are as shown in FIG. 14 when the transmittance of the light amount adjusting device 16 is 10%, 50%, and 100%, respectively. ing.

  As described with reference to FIG. 13, an increase or decrease in the amount of laser light incident on the light detection sensor 60, that is, the amount of light received by the light detection sensor 60 may cause a display image shift. Therefore, the amount of incident laser light needs to be within a predetermined range in order to suppress display image shift. This predetermined range is shown in FIG. 15 as the allowable incident light amount fluctuation range. The light quantity 1 is the upper limit of the allowable incident light quantity fluctuation range, and the light quantity 3 is the lower limit of the allowable incident light quantity fluctuation range. In order to perform the synchronous detection of the scanning light by the amount of laser light incident on the light detection sensor 60, the target value of the amount of laser light incident on the light detection sensor 60 is within the allowable variation range of the amount of incident light. Here, as shown in FIG. 15, with the current amount in the LED region, it is preferable to use the current amount in the LD region, because only a lower output than the allowable incident light amount fluctuation range can be obtained. Further, as described with reference to FIG. 14, in order to control the laser light amount with high accuracy, do not use the current amount in the Ith region where the characteristics may change due to factors such as temperature as the current amount of the laser drive current. Is preferred.

  On the other hand, when the transmittance is 10% or 50%, it is possible to achieve the allowable incident light amount variation range within the LD region current amount without using the Ith region current amount. On the other hand, when the transmittance is 100%, the amount of incident laser light that passes through the light amount adjusting device 16 does not decrease so much, and the amount of incident laser light to the light detection sensor 60 increases. As a result, a lower current amount is used in order to set the incident laser light amount within the allowable incident light amount fluctuation range, and as a result, the current amount used falls within the Ith region. In other words, when the amount of laser light incident on the light detection sensor 60 is largely changed by factors other than the drive current, such as the light amount adjustment by the light amount adjusting device 16 described above, for example, it is attempted to keep the amount of received light within a predetermined amount by only current control. Up to the Ith area will be used.

  Focusing on the inclination in FIG. 15, the control resolution of the incident laser light quantity is lower as the inclination of the incident laser light quantity with respect to the drive current is larger. Therefore, the control resolution of the incident laser light amount is higher in the order of transmittance 10%, 50%, 100%. Therefore, in the case of the transmittances of 10% and 50%, the current can be controlled within the allowable incident light amount variation range with the current amount outside the Ith region, but the transmittance of 10% is more advantageous from the viewpoint of the control resolution of the incident laser light amount. .

  As described above with reference to FIG. 15, when the amount of light incident on the light detection sensor 60, that is, the amount of light received by the light detection sensor 60 is set to a predetermined amount, only the control of the current amount controls the wide range dimming method. May not be available.

  FIG. 16 is a diagram for explaining the setting of the time interval of the laser drive time according to the amount of incident laser light.

  In FIG. 16A, when the filter 1613 having the smallest transmittance is selected and the transmittance of the light amount adjusting device 16 is 10%, in FIG. 16B, the filter 1612 is selected and the transmittance of the light amount adjusting device 16 is selected. Is 50%, and in FIG. 16C, when the filter 1611 is selected and the transmittance of the light amount adjusting device 16 is 100%, the amount of incident laser light incident on the light detection sensor 60, that is, Unit received light amounts P1, P2, P3 received by the light detection sensor 60 per unit time are shown. Further, FIG. 16A, FIG. 16B, and FIG. 16C respectively show the comparator input signal and the synchronizing signal at that time. Since a certain time is required for the conversion process from the optical signal to the electric signal performed by the photodetection sensor 60, the input signal to the comparator can be considered by the integrated received light amount of the laser light incident on the PD 61.

  By performing the time control so that the duty is changed as the time interval according to the unit light reception amounts P1, P2, P3, the integrated light reception amount of the light detection sensor 60 can be controlled. In FIGS. 16A, 16B, and 16C, the time interval is set according to the unit light receiving amounts P1, P2, and P3 so that the integrated light receiving amount of the light detection sensor 60 becomes substantially the same. Since it depends on the amount of light, it can be said that the amount of incident laser light corresponds to the amount of light received per unit. Further, since the incident laser light amount is determined according to the transmittance of the light amount adjusting device 16, it can be said that when it is determined to correspond to the unit received light amount, the incident laser light amount depends on the transmittance of the light amount adjusting device 16.

  FIG. 17 is a diagram illustrating the light amount control according to the first embodiment according to the first embodiment. FIG. 17A shows light detection with respect to the amount of current when a pulse lighting with a duty of 10% is applied when using an ND filter with a transmittance of 100% and when a pulse lighting with a duty of 20% is applied when using an ND filter with a transmittance of 50%. In FIG. 17B, the unit received light amount of the sensor 60 is the case where the pulse lighting of the duty of 10% is applied when the ND filter having the transmittance of 100% is used, and the pulse lighting of the duty of 20% is applied when the ND filter of the transmittance of 50% is used. In this case, it is the integrated received light amount with respect to the current amount.

  FIG. 17A shows a unit light-receiving amount when the transmittance is 50% shown in FIG. 16B, for a continuous lighting scan of the unit light-receiving amount P1 when the transmittance is 10% shown in FIG. P2) The unit received light amount P2 is 5 times as large as P1 at the time of pulse lighting scanning with a duty of 20%. 16C shows that the unit light-receiving amount P3 is 10 times the unit light-receiving amount P3 at the time of the pulse lighting scan with the unit light-receiving amount (P3) at the transmittance of 100% shown in FIG. As an example, the present display device can execute light amount control (hereinafter sometimes referred to as time control) by a time interval in which the light source element 111 is turned on in a state where a predetermined amount of current is supplied to the light source element 111 by the image display unit 174. Is. Further, the time control here may be generally called PWM control, duty control, or the like.

  The solid line in FIG. 17B shows the reference current value when the transmittance is 50% and when the transmittance is 100%, when the reference current value Ip0 is the current value at which the integrated received light amount falls within the allowable light amount fluctuation range when the transmittance is 10%. It shows that the time interval of the time control is set so that the integrated received light amount with respect to the unit received light amount falls within the allowable light amount fluctuation range when Ip0 is used.

  In FIG. 17B, a comparative example is shown by a chain double-dashed line. That is, as shown in FIG. 17A, when the unit current received light amount is P1, P2 and P3 at the same current value Ip0, the transmittance is 100%, and when the unit received light amount P3 is continuously lit, the transmittance is 50%. When continuous lighting is performed at the unit received light amount P2, the current in the Ith region is used to keep the light amount within the allowable light amount fluctuation range, that is, the control is not stable.

  On the other hand, as shown in FIG. 17A, the unit received light amounts P1, P2, P3 are made different at the same current value Ip0, and as shown by the solid line in FIG. , P3, the time control for varying the duty as the time interval can be performed to control the integrated received light amount to the light detection sensor 60.

  As described above with reference to FIGS. 16 and 17, in any of FIGS. 16A, 16B, and 16C, the integrated received light amount is controlled to be within a predetermined range, more preferably the same. As a result, even if the range of the unit received light amount to the light detection sensor 60 fluctuates more greatly, for example, when the light amount adjustment device 16 adjusts the light amount of the light reaching the screen 15, the timing fluctuation of the synchronization signal does not occur. .

  In the present embodiment, the reference current value, which is the value of the current within which the integrated received light amount falls within the predetermined range, is determined when 10%, which is the filter with the smallest transmittance among the plurality of filters, is used. When selecting a filter having another transmittance, the time interval is set so that the integrated received light amount falls within the predetermined range while using the reference current value. This is because, as shown in FIG. 17B, when a filter having a small transmittance is used, the inclination with respect to the drive current is smaller, that is, the control resolution of the amount of received light is higher. By setting such a time interval, control with high control resolution of the amount of received light can be executed.

  Although the ideal operation state in the present embodiment has been described above, the responsiveness of the laser and the IC deviates from the ideal state in the actual operation, and therefore the amount of light emitted from the light source device 11 and the light detection sensor 60 are different. It is necessary to finely adjust the amount of received light and the time interval in time control. For example, when performing the time control by the duty according to the received light amount, each received light amount is not always ideally constant. Therefore, along with the time control, a current control for keeping each received light amount within a predetermined range is executed. You may do so.

  FIG. 18 is a diagram for explaining the relationship between the time interval during the time control and the time constant of the light detection sensor.

  When the light detection sensor 60 includes an electric circuit such as the integrated circuit 62 as an example, a response speed unique to the electric circuit exists, and the response speed is represented by a time constant, a cutoff frequency, or the like. FIG. 18A shows the case where the off time during pulse lighting, that is, the time interval is set smaller than the time constant (cutoff frequency), and FIG. 18B shows the case where it is set larger than the time constant (cutoff frequency). Indicates.

  In FIG. 18A, since the laser pulse lighting off time is shorter than the time constant of the circuit, the fluctuation (ripple) of the comparator input waveform after being converted into an electric signal by the integrated circuit 62 is small, and the continuous lighting is performed. The waveform is almost the same as.

  On the other hand, in FIG. 18B, since the pulse lighting off time of the laser is longer than the time constant of the circuit, the fluctuation (ripple) of the comparator input waveform after being converted into an electric signal by the integrated circuit 62 becomes large. As a result, timing deviation and erroneous detection occur.

  As described above, the off time of the pulse lighting, that is, the time interval of the time control is set to be shorter than the time constant (cutoff frequency) of the electric circuit included in the light detection sensor 60 as shown in FIG. Therefore, the output waveform of the light detection sensor 60 can be stabilized.

  FIG. 19 is a diagram illustrating the light amount control according to the first embodiment according to the first embodiment. The relationship between the unit received light amount and the integrated received light amount when pulse lighting with a duty of 50% is performed when the transmittance is 100% and the transmittance is 50% is shown. The configuration and description described with reference to FIGS. 1 to 15 in this embodiment are common to those in the first embodiment, and a description thereof will be omitted.

  As described with reference to FIG. 18, when the pulse lighting off time of the laser is longer than the time constant of the circuit, it causes a timing shift or erroneous detection. Therefore, depending on the time constant of the light detection sensor 60 used in the display device 10, it may not be possible to perform stable control of the waveform of the synchronization signal by pulse lighting with a short time interval of 10% Duty or 20% Duty. In the present embodiment, by applying pulse lighting with a duty of 50%, which is a time interval at which the waveform of the synchronization signal of the light detection sensor 60 stabilizes at a transmittance of 100%, there is little timing variation at a transmittance of 50%, and high control is possible. The synchronization control can be performed with the resolution, and the synchronization control with less timing fluctuation can be performed when the transmittance is 100%. This will be specifically described below.

  FIG. 19A shows that the unit received light amount P5 at a transmittance of 50% is changed to the unit received light amount at a transmittance of 100% in the continuous lighting scan of the unit received light amount P4 at a transmittance of 10% of the light amount adjusting device 16. It indicates that P5 is set. At this time, the drive currents Ip1, Ip2, Ip3 are set so that the unit received light amount P5 is twice the unit received light amount P4.

  Then, FIG. 19B shows the integration with respect to the drive current when the pulse lighting with the duty of 50% is applied when the ND filter with the transmittance of 100% is applied and when the pulse lighting with the duty of 50% is applied when the ND filter of the transmittance of 50% is applied. It is the amount of received light.

  Since a certain period of time is required for the conversion processing from the optical signal to the electrical signal performed by the photodetection sensor 60, the input signal to the comparator can be considered by the integrated amount of light received by the PD 61. Therefore, as shown in FIG. 19B, when the current value Ip1 is set as the drive current in which the integrated received light amount falls within the allowable light amount fluctuation range at the transmittance of 10%, the unit is the drive current Ip2 at the transmittance of 50%. When the received light amount P5 and the transmittance are 100%, the integrated received light amount can be controlled to fall within the allowable light amount fluctuation range when the unit received light amount P5 is set in the drive current Ip2.

  As described above, in the second embodiment, even when the control using the short time interval cannot be performed due to the time constant of the light detection sensor 60, the timing is set when the transmittance of the light amount control device 16 is 100%. It is possible to perform synchronous control with little fluctuation. Further, when the transmittance is 50%, the slope of the integrated received light amount with respect to the drive current can be controlled with a gentler characteristic than when the transmittance is 100%. Therefore, when the transmittance is 50%, the timing variation is small and the synchronous control can be performed with a high control resolution for the received light amount.

  In the first embodiment, the time interval is changed to continuous lighting, Duty 20%, and Duty 10% in accordance with the different unit received light amounts P1, P2, and P3, respectively, and the integrated value of the unit received light amount in a predetermined time is used. Control is performed so that a certain integrated received light amount falls within a predetermined range. On the other hand, in the present embodiment, the time interval is continuously turned on for the unit received light amount P4 and is changed to 50% for the unit received light amount P5 so that the integrated received light amount is controlled within the predetermined range.

  Also in this embodiment, if the integrated received light amount is controlled to be within a predetermined range, more preferably the same, for example, as a result of adjusting the light amount of the light amount reaching the screen 15 by the light amount adjustment device 16, the light detection sensor 60 Even when the range of the unit received light amount largely changes, the timing change of the synchronization signal does not occur.

  Further, in the present embodiment, the time interval for obtaining a stable control waveform is limited due to the relationship with the time constant of the photodetection sensor 60, that is, the duty 10% and the duty 20% used in the first embodiment. This applies when short time intervals are not used. By making the drive current different depending on the transmittance of the light quantity adjusting device 16, it is possible to keep the integrated received light quantity within a predetermined range even if the usable time interval is limited.

  The ideal operating state in the present embodiment has been described above. However, in actual operation, the responsiveness of the laser and the IC deviates from the ideal state, so the amount of light emitted from the light source device 11 and the amount of light received by the light detection sensor 60 are different. The time interval in time control requires fine adjustment. For example, when performing the time control by the duty according to the received light amount, each received light amount is not always ideally constant. Therefore, along with the time control, a current control for keeping each received light amount within a predetermined range is executed. You may do so.

  Note that the number of filters having different transmittances is three in common in the first embodiment and the second embodiment, but the number is not limited to this, and an appropriate number may be set according to the usage pattern of the display device 10. Just set it. In the first embodiment, the drive current supplied to the light source element 111 for each filter is Ip0 in common to all the filters, and in the second embodiment, the drive current supplied to the light source element 111 for each filter is Although they are all different from Ip1, Ip2, and Ip3, they are not limited to these. That is, one display device may be supplied with a common drive current when using some different filters, and may be supplied with different drive currents when using some different filters.

  FIG. 20 is a flowchart showing a light quantity control flow. As an example, the flow starts when the optical scanning by the optical deflector 13 is started. Note that this flow can be applied to both the first embodiment and the second embodiment.

  First, the control unit 175 sets the initial value of the laser drive current (S101). As the initial value of the drive current, at least a current that is not Ith may be stored in the storage unit 179 in advance. Then, the control unit 175 executes control by current control so as to be within a predetermined integrated received / received light amount, but does not execute time control (S102). The predetermined received light amount is, for example, an allowable light amount fluctuation range. The initial value of the drive current and the allowable light amount fluctuation range may be stored in the storage unit 179 in advance.

  Next, the control unit 175 determines whether the integrated received light amount of the light detection sensor 60 is within a predetermined range without using the current in the Ith region (S103). When it is the predetermined integrated received light amount (in the case of YES), the control of step S101 is continued. That is, for example, even if the transmittance of the light quantity adjusting device 16 is changed, the control is continued so that the allowable light quantity fluctuation range is set only by the current control. On the other hand, if it is determined in step S103 that the received light amount is not the predetermined integrated received light amount (NO), the control unit 175 executes current control and time control as described with reference to FIGS. 16 to 19 (S104).

  As described above, in the control by only the current control, the drive current becomes smaller as the transmittance of the light amount adjusting device 16 becomes higher in order to control the integrated received light amount so as to be within the predetermined range. In this flow, it is determined whether the drive current is reduced to the Ith region, which is a region smaller than the LD region, in a state where only the current control is performed (step S103). Then, when the Ith region is lowered or when there is a high possibility that the Ith region is lowered, the time control is started. That is, the drive current is controlled to a predetermined current in the LD region that is not the Ith current to increase the output brightness of the light source, which is a laser, and switching to pulse lighting is performed according to the amount of light received by the photodetection sensor 60 at that predetermined current. In this way, when the transmittance of the light quantity adjusting device 16 is low, the integrated light quantity of the light detection sensor 60 can be kept constant by controlling only the current control and the time control when the transmittance is higher. it can.

  Further, the current control is more accurate than the time control. Therefore, as in step S101, by executing the current control first, it is possible to preferentially execute the current control, which is a highly accurate control, in the received light amount control of the light detection sensor 60. The flow executed to give priority to the current control is not limited to this flow. For example, the control unit 175 may be a flow executed while both the current control and the time control are being executed. The transmittance of 16 is monitored, and the transmittance that falls within the permissible fluctuation range of the light quantity only by the current control, for example, when the smallest transmittance is used in the display device 10, the current control and the time control are both performed. Alternatively, the control may be changed to only current control.

  As described in the first and second embodiments as an example, even in the case of a display device having a wide dynamic range of luminance using a plurality of filters having different transmittances, there are two types of current control and time control. By executing one of the two controls according to the transmittance of the light quantity adjusting device 16, the scanning light can be detected appropriately.

  The image forming apparatus according to the embodiment has been described above, but the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention.

1 Display System 10 Display Device 11 Light Source Device (Example of Light Source)
13 Light Deflection Device (Example of Light Deflection Unit)
15 screen (an example of diverging member)
16 Light intensity adjusting device (example of light intensity adjusting unit)
161 Filters 1611, 1612, 1613 Filter 30 Free-form surface mirror (an example of an imaging optical system)
50 Windshield (an example of a reflective member)
60 light detection sensor 60 (an example of a light detection unit)
61 PD
62 integrated circuits

Japanese Patent Laid-Open No. 2015-162526

Claims (13)

A light source device that has a light source element, and that emits a laser beam that is output by lighting the light source element that is supplied with current;
A scanning unit that displays an image by scanning light that two-dimensionally scans the laser light,
A photodetector for receiving the scanning light,
Have
It is possible to execute a time control for controlling a received light amount, which is a light amount received by the photodetector, by a time interval in which the light source element is turned on in a state where a predetermined current amount is supplied,
The display device in which the time interval when scanning the photodetector differs depending on the amount of received light. It is possible to execute current control for controlling the received light amount by the amount of current supplied to the light source element,
The display device according to claim 1, wherein, as the current control, at least the current amount when scanning the photodetector is changed.   The time interval when scanning the photodetector differs depending on the unit received light amount that is the received light amount per unit time, and the integrated received light amount that is an integrated value of the unit received light amount within a predetermined time is within a predetermined range. The display device according to claim 1, wherein the time interval is controlled so that   4. The display device according to claim 2, wherein the time control is not executed when the integrated received light amount is within the predetermined range in a state where the current control is executed and the time control is not executed. The area scanned by the scanning unit includes an image area irradiated with light according to image data and a non-image area that is not the image area,
The display device according to claim 1, wherein the light detection unit receives the scanning light in the non-image area. Light is transmitted between the light source element and the light detection unit, and a filter for changing the amount of light passing therethrough is provided,
The display device according to any one of claims 1 to 5, wherein the time interval is different according to the light transmittance of the filter.   The display device according to claim 6, further comprising a plurality of the filters having different transmissivities, and among the plurality of filters, a filter installed between the light source element and the light detection unit can be switched. Of the plurality of filters, the integrated received light amount when the filter with the smallest transmittance is selected as the reference current value is a value of the predetermined current amount within the predetermined range,
The display device according to claim 7, wherein when a filter having another transmittance is selected, the time interval is set such that the integrated received light amount falls within the predetermined range while using the reference current value. Light is transmitted between the light source element and the light detection unit, and a filter for changing the amount of light passing therethrough is provided,
6. The display device according to claim 1, wherein the amount of current supplied to the light source element varies depending on the light transmittance of the filter.   The display device according to claim 1, wherein the time interval is set according to a response speed of the light detection unit. The photodetector has an electric circuit,
The display device according to claim 10, wherein the response speed is a time constant of the electric circuit. A display device according to any one of claims 1 to 11,
A diverging member that scans the scanning light and diverges the scanning light,
A display member that reflects the divergent light that has been diverged. The display system according to claim 12,
The reflective member is a moving body that is a windshield that reflects the divergent light.