JP2018017866A - Optical scanner, image irradiation unit and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a successive adjustment of amounts of light from high luminance to low luminance thanks to a quite simple configuration.SOLUTION: An optical scanner comprises: a light source unit 11 that outputs light serving as linear polarized light; a filter 122 that has a linear polarizer formed into a fan shape from a rotary center and having a polarization transmission axis, and is arranged on an optical path of the light; a drive unit 121 that makes the filter 122 rotate and drive, and makes an incidence position of the light move in the linear polarizer; a light adjustment information input unit 8 that inputs light adjustment information; and a control unit 5 that controls the drive unit 121 so as to be a predetermined rotation angle of the filter 122 in accordance with the light adjustment information to move the filter 122, and tilts the polarization transmission axis of the linear polarizer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical scanning device, an image irradiation unit, and an image display device.

  2. Description of the Related Art Conventionally, a laser scanning type image display device that scans light two-dimensionally or three-dimensionally at high speed by laser scanning and obtains a display image using an afterimage phenomenon of the human eye has recently started to be used. A head up display (HUD) housed in a dashboard of an automobile is an example of a laser scanning type image display device.

  Since the display in the HUD is superimposed on a landscape or a road, the brightness required for the HUD needs to be a brightness that does not give a sense of incongruity to the brightness of the outside world. Specifically, a bright background such as a snowy road needs to be as bright as it can. Also, in dark nights, appropriate brightness that is not too bright is necessary.

  In Patent Document 1, a plurality of stages of neutral density filters that adjust the brightness of a projected image by changing the transmittance of irradiated laser light in stages are switched, and the amount of laser light is changed from a dark area to a bright area. A technique for changing the process up to this point is disclosed.

  However, according to the technique described in Patent Document 1, there are problems that a neutral density filter is required in multiple stages and complicated control is required, mass productivity is low, and cost is high.

  The present invention has been made in view of the above, and an optical scanning device, an image irradiation unit, and an image display that can realize continuous light amount adjustment from high luminance to low luminance with a very simple configuration. An object is to provide an apparatus.

  In order to solve the above-described problems and achieve the object, an optical scanning device of the present invention includes a light source unit that outputs light that is linearly polarized light, and linearly polarized light that is formed in a fan shape from the rotation center and has a polarization transmission axis. A dimmer having a dipole, a filter disposed in the optical path of the light, a drive unit for rotating the filter to move the incident position of the light within the linear polarizer, and dimming information for inputting dimming information An input unit; and a control unit configured to control the driving unit to move the filter so as to have a rotation angle of the filter determined in advance according to the dimming information to tilt the polarization transmission axis of the linear polarizer. It is characterized by providing.

  According to the present invention, there is an effect that continuous light amount adjustment from high luminance to low luminance can be realized with a very simple configuration.

FIG. 1 is a diagram illustrating a schematic configuration of the head-up display device according to the first embodiment. FIG. 2 is a diagram illustrating a schematic configuration of the optical scanning device. FIG. 3 is a diagram illustrating an example of a hardware configuration of the control unit. FIG. 4 is a diagram illustrating a control example of the dimming unit. FIG. 5 is a graph showing an example of the relationship between the rotation angle of the filter and the transmittance of the laser beam. FIG. 6 is a diagram illustrating an example of the relationship between the light control information input from the light control information input unit and the amount of laser light. FIG. 7 is a diagram illustrating an example of the arrangement of filters of the dimming unit according to the second embodiment.

  Embodiments of an optical scanning device, an image irradiation unit, and an image display device will be described below in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of a head-up display device 1 according to the first embodiment. As an example, a head up display device 1 as an image display device is mounted on a moving body such as a vehicle, an aircraft, and a ship. In the following, for convenience, the head-up display device 1 is referred to as “HUD1”.

  For example, the HUD 1 makes it possible to visually recognize navigation information (for example, information on speed, travel distance, etc.) and the like necessary for maneuvering the moving body via the windshield (front windshield) 50 of the moving body. In this case, the windshield 50 also functions as a transmission / reflection member that transmits part of the incident light and reflects at least part of the remaining part. Hereinafter, an example in which the HUD 1 is mounted on an automobile including the windshield 50 will be described.

  As shown in FIG. 1, the HUD 1 includes an image irradiation unit 60 that irradiates an image and a concave mirror 40. The image information emitted from the image irradiation unit 60 is image information from an image data output device such as a personal computer, a memory, a hard disk, various disk players, a video conference terminal, a tablet terminal, and a smartphone. In addition, as image information, the information regarding driving | operation, navigation, etc. of a vehicle etc. is mentioned, for example. The HUD 1 irradiates the windshield 50 through the concave mirror 40 with light based on the image irradiated from the image irradiation unit 60. As a result, the HUD 1 makes the virtual image I visible from the viewpoint of the observer A.

  The image irradiation unit 60 includes an optical scanning device 10, an optical deflector 15, a scanning mirror 20, and a screen 30.

  As will be described in detail later, the optical scanning device 10 emits laser light (synthetic light) formed by combining three laser lights from three types of laser diodes of R, G, and B to the optical deflector 15. To do.

  The optical deflector 15 is a MEMS (Micro Electro Mechanical Systems) mirror manufactured by a semiconductor process or the like, and is a single minute mirror that swings with respect to two orthogonal axes. The optical deflector 15 may be a mirror system including two mirrors that swing / rotate about one axis.

  The scanning mirror 20 turns back the light beam deflected by the optical deflector 15 and draws a two-dimensional image (intermediate image) on the screen 30 that is the surface to be scanned.

  The screen 30 has a function of diverging laser light at a desired divergence angle, and a microlens array structure is preferable. The light beam emitted from the screen 30 is projected onto the windshield 50 that is the projection surface via the single concave mirror 40. Thereby, the virtual image I is enlarged and displayed on the windshield 50.

  The single concave mirror 40 is designed and arranged so as to correct an optical distortion element in which the horizontal line of the intermediate image is convex upward or downward due to the influence of the windshield 50.

  In addition, HUD1 may be the structure which has the partial reflection mirror (combiner) which has the same function (partial reflection) as the windshield 50 as a projection surface separately from the windshield 50. FIG.

  Next, the optical scanning device 10 will be described in detail.

  Here, FIG. 2 is a diagram showing a schematic configuration of the optical scanning device 10. As shown in FIG. 2, the optical scanning device 10 includes a control unit 5, a motor driver 6, a light source driver 7, a dimming information input unit 8, and a light source unit 11.

  The dimming information input unit 8 inputs how much the luminance of the HUD 1 is, that is, dimming information that is an index of the luminance of the projected image from an external device. The dimming information changes according to the brightness of the outside world.

  The control unit 5 sends the image information to the light source driver 7. Further, the control unit 5 controls the motor driver 6 based on the dimming information input by the dimming information input unit 8.

  FIG. 3 is a diagram illustrating an example of a hardware configuration of the control unit 5. The control unit 5 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an HDD (Hard Disk Drive) 104, a network I / F (Interface) 105, and a bus 107. . The CPU 101, ROM 102, RAM 103, HDD 104, and network I / F (Interface) 105 are connected to each other via a bus 107.

  The CPU 101 executes a program. The ROM 102 stores a startup program and the like. The RAM 103 is a memory used when the CPU 101 executes a program. The HDD 104 stores an application program for operating the HUD 1 and various data. The HDD 104 may be an optical drive or a flash memory. Recording members to be read or written by the optical drive are CD-ROM (Compact Disk Read Only Memory), CD-R (Compact Disk Recordable), DVD (Digital Versatile Disk), and the like. The network I / F 105 transmits and receives various types of information to and from external devices.

  The program stored in the ROM 102 or the HDD 104 is provided as a file in an installable or executable format recorded on a computer-readable recording member such as a CD-ROM, CD-R, or DVD. You may comprise as follows.

  Further, the program stored in the ROM 102 or the HDD 104 may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Further, the program stored in the ROM 102 or the HDD 104 may be provided or distributed via a network such as the Internet.

  The control unit 5 may be constructed by hardware such as an IC.

  Hereinafter, the light source unit 11 will be described in detail.

  As shown in FIG. 2, the light source unit 11 includes a plurality of light source elements 111R, 111B, and 111G having one or a plurality of light emitting points. The light source elements 111R, 111B, and 111G are controlled by the control unit 5 via the light source driver 7. The light source elements 111R, 111B, and 111G are LDs (laser diodes: semiconductor laser elements). The light source element 111R is a red laser, and emits a light beam of red light (wavelength λR = 640 nm). The light source element 111B is a blue laser, and emits a light beam of blue light (wavelength λB = 445 nm). The light source element 111G is a green laser and emits a light beam of green light (wavelength λG = 530 nm).

  The light source unit 11 includes coupling lenses 112R, 112B, and 112G, and apertures 113R, 113B, and 113G. The coupling lens 112R and the aperture 113R are disposed on the light emission side of the light source element 111R. The coupling lens 112B and the aperture 113B are arranged on the light emission side of the light source element 111B. The coupling lens 112G and the aperture 113G are disposed on the light emission side of the light source element 111G.

  Light fluxes of wavelengths λR, λB, and λG emitted from the light source elements 111R, 111B, and 111G are coupled to subsequent optical systems by coupling lenses 112R, 112B, and 112G, respectively.

  The luminous fluxes coupled by the coupling lenses 112R, 112B, and 112G are cut into peripheral portions by the apertures 113R, 113B, and 113G provided, respectively, and shaped into a desired beam diameter. The apertures 113R, 113B, and 113G can have various shapes such as a circle, an ellipse, a rectangle, and a square according to the divergence angle of the light beam.

  As shown in FIG. 2, the light source unit 11 includes a synthesis element 115 and a lens 116. The synthesizing element 115 optically synthesizes the respective light beams shaped by the apertures 113R, 113B, and 113G. The synthesizing element 115 is a plate-like or prism-like dichroic mirror, and reflects / transmits a light beam according to the wavelength, and synthesizes it into one optical path. In addition, it is necessary to align the polarization axes of the light source elements 111R, 111B, and 111G for each color of RGB so that the combined laser beam becomes linearly polarized light.

  Note that the above-described laser light source (light source elements 111R, 111B, and 111G) is preferable as the light source light having linearly polarized light in the present embodiment, but the laser light source itself is not necessarily required. That is, light emitted from a non-polarized LED (Light Emitting Diode) or the like may be used as light source light obtained by directly extracting polarized light through a linear polarizer. Alternatively, the light source light may be generated from a light source unit that is a linearly polarized light obtained by combining a polarization beam splitter and a half-wave plate to perform polarization conversion that aligns polarized light in one direction.

  The light beam synthesized by the synthesis element 115 is guided toward the reflection surface of the optical deflector 15 by the lens 116. The lens 116 is a meniscus lens having a concave surface directed toward the optical deflector 15.

  In addition, the light source unit 11 has a dimming unit 120 that realizes dimming with respect to the laser light in an optical path after the synthesis by the synthesis element 115. The dimming unit 120 includes a rotary motor 121 that is a drive unit, and a circular filter 122 that is rotationally driven by the rotary motor 121. As shown in FIG. 2, the filter 122 of the dimming unit 120 is disposed so as to be substantially perpendicular to the laser beam emission direction X.

  The rotary motor 121 is controlled by the control unit 5 via the motor driver 6. Schematically, the control unit 5 determines the dimming rate from dimming information that is an index of the brightness of the projected image of the HUD 1. The control unit 5 determines the rotation angle of the filter 122 of the dimming unit 120 according to the dimming rate. The control unit 5 controls the drive of the rotation motor 121 so that the determined rotation angle of the filter 122 is obtained, and moves the filter 122. In this way, the HUD 1 can perform desired dimming.

  Next, the dimming means 120 will be described in detail. Here, FIG. 4 is a diagram illustrating a control example of the dimming unit 120. As shown in FIG. 4, the filter 122 includes a high transmittance region 122 a and a linear polarizer 122 b that are arranged adjacent to each other. In the present embodiment, the high transmittance region 122a and the linear polarizer 122b are formed in a fan shape having the same rotation center. Here, the rotation center coincides with the rotation shaft 121 a of the rotary motor 121.

  The linear polarizer 122b of the present embodiment is a reflective type. When the linear polarizer 122b is a reflection type, a component corresponding to the polarization transmission axis of the linear polarizer 122b is transmitted, and a component orthogonal to the polarization transmission axis is reflected. By adopting the reflective linear polarizer 122b in this way, it is possible to suppress heat generation due to absorption when the light attenuation rate is high, and the reliability of the apparatus can be improved.

  The linear polarizer 122b is a polarization beam splitter (a so-called optical thin film that uses linear reflection to create linearly polarized light by utilizing the fact that light reflected at an angle with respect to the reflecting surface is partially polarized. PBS). Further, the linear polarizer 122b may be a wire grid type polarizer having a fine lattice structure of metal.

  In addition, although the linear polarizer 122b of this Embodiment was a reflection type, it is not restricted to this, An absorption type may be sufficient. If the linear polarizer 122b is an absorption type, a component corresponding to the polarization transmission axis of the linear polarizer 122b is transmitted, and a component orthogonal to the polarization transmission axis is absorbed. Absorptive polarizers include film polarizers made of polymers.

  The control unit 5 performs control so that the laser beam (linearly polarized light) synthesized by the synthesis element 115 is incident on a desired region of the filter 122 of the dimming unit 120.

  The example shown in FIG. 4A is an example in which the rotation motor 121 is driven and controlled by the control unit 5 so that the incident position of the laser beam synthesized by the synthesis element 115 is the high transmittance region 122 a of the filter 122. . At the position of the filter 122 shown in FIG. 4A, the dimming means 120 is not dimming the laser beam.

  In the example shown in FIG. 4B, the control unit 5 drives and controls the rotary motor 121 so that the incident position of the laser beam synthesized by the synthesis element 115 is the linear polarizer 122 b of the filter 122. It is the example rotated from the state shown to Fig.4 (a).

  As described above, the laser beam synthesized by the synthesis element 115 has linearly polarized light before entering the filter 122. The polarization transmission axis of the linear polarizer 122b is a polarization transmission axis that maximizes the transmittance of the laser light at the boundary between the high transmittance region 122a and the linear polarizer 122b.

  At the position of the filter 122 shown in FIG. 4B, the polarization transmission axis of the linear polarizer 122b is in a state of being tilted to some extent from the polarization axes of the light source elements 111R, 111B, and 111G. That is, the dimming means 120 restricts the transmission of the laser light according to the rotation of the filter 122 and realizes the dimming with respect to the laser light.

  In the example shown in FIG. 4C, the rotation motor 121 is driven and controlled by the control unit 5, and the polarization transmission axis of the linear polarizer 122b is changed with respect to the linear polarization axis of the laser light from the state shown in FIG. In this example, the filter 122 is rotated to a vertical position, and the incident position of the laser beam is obtained. In this state, the linear polarization axis of the laser light and the polarization transmission axis of the linear polarizer 122b are in a so-called crossed Nicols relationship, and the transmittance of the laser light can be substantially 0%.

  That is, according to the light reducing means 120 of the present embodiment, the transmittance of the laser light can be controlled by adjusting the inclination of the linear polarizer 122b of the filter 122.

  Here, FIG. 5 is a graph showing an example of the relationship between the rotation angle of the filter 122 and the transmittance of the laser beam. The horizontal axis of the filter 122 shown in FIG. 5 represents the rotation angle (deg). The rotation angle 0 degree of the filter 122 is a boundary between the high transmittance region 122a and the linear polarizer 122b. The rotation angle of 90 degrees of the filter 122 indicates a state where the linear polarization axis of the laser beam and the polarization transmission axis of the linear polarizer 122b are perpendicular to each other and are substantially shielded from light.

  As shown in FIG. 5, the filter 122 has a laser beam transmittance at a position where the linear transmission axis of the laser beam and the polarization transmission axis of the linear polarizer 122 b have the maximum transmittance (parallel Nicol) parallel to each other. 80%. Further, as shown in FIG. 5, the filter 122 has a laser light transmittance of 0% at a position where the linear polarization axis of the laser light and the polarization transmission axis of the linear polarizer 122b are crossed Nicols. Become. Actually, light absorption and depolarization occur, and the transmittance of the laser beam does not become 0%, but here it is assumed to be 0%.

  Further, as shown in FIG. 5, the transmittance of the laser light is 100% during the rotation angle of 0 to -10 degrees of the filter 122 which is the high transmittance region 122a of the filter 122. That is, the high transmittance region 122a of the filter 122 corresponds to a case where no member is interposed. The high transmittance region 122a of the filter 122 of the present embodiment obtains a transmittance that is close to 100% by inserting a transparent glass plate or an element corresponding thereto. Further, the high transmittance region 122a of the filter 122 can be adjusted to the maximum transmittance (parallel Nicol) state of the linear polarizer 122b without depending on polarization.

  When the power of the laser beam from the light source elements 111R, 111B, and 111G is used to the maximum, the control unit 5 determines the rotation angle so that the rotation angle of the filter 122 is in the range of −10 degrees to 0 degrees. The rotation motor 121 is driven and controlled so that the determined rotation angle of the filter 122 is obtained.

  As shown in FIG. 5, the transmittance of the filter 122 decreases from 100% to 80% at the moment when the rotation angle of the filter 122 enters 0 degree. However, such a decrease in transmittance does not cause a problem because it is difficult to perceive a change in visual recognition. Further, as shown in FIG. 5, when the filter 122 is rotated, the transmittance is proportional to the square of cos θ, and is decreased from the position of 0 degrees. In this way, the control unit 5 can perform desired dimming on the laser light by controlling the rotation of the filter 122.

  Here, FIG. 6 is a diagram illustrating an example of the relationship between the light control information input by the light control information input unit 8 and the amount of laser light. FIG. 6A is a graph showing the relationship between the light control information and the amount of laser light, and FIG. 6B is a table showing the relationship between the rotation angle, the transmittance, and the light amount in each light control information. . In the example shown in FIG. 6, twelve dimming steps are set as dimming information that is an index of the brightness of the projected image of HUD1.

  As shown in FIG. 6A, the 12 light control steps set as the light control information are such that the light quantity ratio of the laser light of about one step is substantially constant. This constant value was 1/2. As a result, even if the change in the amount of light is not a linear change, it is visually felt as a step change. Note that halving the amount of laser light seems to be a relatively large amount of change, but it is sufficient visually. According to Weber-Fechner's law, the perceived intensity is proportional to the logarithm of the stimulus.

The control unit 5 stores in advance the correspondence relationship between the dimming stage shown in the table shown in FIG. 6B and the angle information of the rotation angle of the filter 122 in the HDD 104. As shown in FIG. 6B, the twelve dimming steps in the present embodiment are such that the minimum value can be reduced to 8 cd / cm ² when the maximum brightness of HUD1 is 10,000 cd / cm ^2. , The interval is divided into 10 parts.

  As shown in FIG. 6B, the rotation angle of the filter 122 has a relatively large angle change at each stage when the amount of light is large and the luminance is high. On the other hand, at the stage where the amount of light is small (such as stage 8 to stage 11), the rotation angle of the filter 122 is small in angle change at each stage. Thus, by not changing linearly with respect to the dimming step, the dimming rate can be changed logarithmically. That is, the control unit 5 controls the rotation of the filter 122 in rough steps when the light reduction rate is small and bright, and controls the rotation of the filter 122 in fine steps when the light attenuation rate is high and dark luminance. By doing so, the amount of light can be changed logarithmically. By changing logarithmically, the change level in human perception recognition can be a natural change, and HUD 1 with higher quality can be realized.

  As described above, the dimming step is changed by the rotational motion so that the change in the rotation angle of the filter 122 for each step becomes smaller as the transmittance of the laser light determined by the inclination of the polarization transmission axis of the linear polarizer 122b becomes lower. Can do. Thereby, the structure of the light reduction means 120 can be made small and HUD1 as a smaller image display apparatus can be implement | achieved.

  In the present embodiment, one stage is set to 1/2 step rotation control in which the amount of laser light is set to a value that halves, but the present invention is not limited to this. What is necessary is just to carry out rotation control so that the light quantity ratio of the laser beam before and after one step may be fixed. For example, it may be a half of 1 / √2 step. In this case, since one step is set every 12 steps, there are 23 steps. Naturally, substantially stepless light control is possible by setting the light amount ratio of the laser light around one stage as a constant value to a smaller value and making the rotation angle step as small as possible.

  As described above, according to the present embodiment, it is possible to achieve continuous light amount adjustment from high luminance to low luminance with a very simple configuration, while improving the quality of the HUD 1 as an image display device. An inexpensive image display device can be realized while maintaining high reliability with a small number of points and high productivity.

  Note that the control unit 5 may perform light control by performing current control on the light source elements 111R, 111B, and 111G for each color of RGB. Thereby, finer control becomes possible.

  In the present embodiment, the dimming means 120 is arranged in the optical path after the synthesis by the synthesis element 115, but the present invention is not limited to this. For example, the dimming means 120 may be disposed after the lens 116, or may be disposed in the optical paths of the RGB light source elements 111R, 111B, and 111G.

(Second Embodiment)
Next, a second embodiment will be described. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is also omitted.

  In the second embodiment, the filter 122 of the dimming means 120 is different from the first embodiment in that the filter 122 has a predetermined incident angle and is arranged to make the laser light incident. It has become.

  In the first embodiment, as shown in FIG. 2, the filter 122 of the dimming unit 120 is disposed so as to be substantially perpendicular to the laser beam emission direction X. In the case of the configuration shown in FIG. 2, if the linear polarizer 122b of the filter 122 is a reflection type, the reflected light from the linear polarizer 122b may return to the combining element 115 and the light source elements 111R, 111B, and 111G. In this case, unexpected problems such as heat generation of the synthesis element 115 and the light source elements 111R, 111B, and 111G may occur due to the reflected light.

  Here, FIG. 7 is a diagram illustrating an arrangement example of the filter 122 of the light reducing unit 120 according to the second embodiment. As shown in FIG. 7, in the present embodiment, the filter 122 of the dimming means 120 is disposed so as to be inclined with respect to the emission direction X of the laser beam so that the laser beam is incident with a predetermined incident angle. Has been. For this reason, it is possible to prevent the reflected light from the linear polarizer 122b from returning to the combining element 115 and the light source elements 111R, 111B, and 111G.

  Further, as shown in FIG. 7, the dimming means 120 of the present embodiment is provided with the photodetector 123 in the optical path of the reflected light from the linear polarizer 122b. Accordingly, the control unit 5 can calculate the light amount of the light emitted from the light source unit 11 by obtaining the detection amount of the light intensity of the reflected light by the photodetector 123. That is, the control unit 5 can sequentially monitor whether the light attenuation rate is a desired value.

  As described above, according to the present embodiment, since the filter 122 is arranged so as to be inclined so that the incident angle incident on the reflective linear polarizer 122b is not vertical, the combined element is generated by the return light from the filter 122. By preventing the influence on 115 and the light source elements 111R, 111B, and 111G, a highly reliable device can be realized.

  Further, according to the present embodiment, the photodetector 123 that detects the light intensity of the reflected light from the reflective linear polarizer 122b is provided, and the control unit 5 has the light intensity of the reflected light obtained by the photodetector 123. The dimming rate of the laser beam is detected based on the detected amount. Thereby, it can be determined whether it is set to the desired light attenuation rate, and HUD1 as a more reliable image display apparatus is realizable.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 5 Control part 8 Light control information input part 10 Optical scanning apparatus 11 Light source part 15 Optical deflector 20 Scanning mirror 30 Screen 40 Concave mirror 60 Image irradiation unit 121 Drive part 122 Filter 122a High transmittance area 122b Linear polarizer 123 Photodetector

JP 2014-194493 A

Claims (9)

A light source unit that outputs light that is linearly polarized light;
A linear polarizer having a polarization transmission axis formed in a fan shape from the rotation center, and a filter disposed in the optical path of the light;
A drive unit that rotates the filter and moves the incident position of the light within the linear polarizer;
A dimming information input unit for inputting dimming information;
A control unit that moves the filter to tilt the polarization transmission axis of the linear polarizer by controlling the drive unit so that the rotation angle of the filter is determined in advance according to the light control information;
An optical scanning device comprising: The filter is formed in a fan shape from the same rotation center as the linear polarizer and is disposed adjacent to the linear polarizer, and further includes a high transmittance region in which the light transmittance is higher than that of the linear polarizer. ,
The drive unit moves the incident position of the light between the high transmittance region and the linear polarizer,
The optical scanning device according to claim 1. The control unit moves the filter so that the light amount ratio of the light before and after one stage is substantially constant on the condition that a plurality of dimming stages are set as the dimming information.
The optical scanning device according to claim 1, wherein: The control unit reduces the change in rotation angle of the filter for each step as the light transmittance determined by the inclination of the polarization transmission axis of the linear polarizer decreases.
The optical scanning device according to claim 3. The linear polarizer is a reflection type that transmits the light corresponding to the polarization transmission axis and reflects the light orthogonal to the polarization transmission axis.
The optical scanning device according to claim 1, wherein the optical scanning device is an optical scanning device. The filter is disposed to be inclined with respect to an emission direction of the light so that the light is incident with a predetermined incident angle.
The optical scanning device according to claim 5. A light detector provided in the optical path of the reflected light from the linear polarizer in the filter, and further detecting a light intensity of the reflected light;
The control unit detects the light attenuation rate based on a detection amount of the light intensity of the reflected light obtained by the photodetector;
The optical scanning device according to claim 6. An optical deflector;
A screen for diverging the laser at a desired divergence angle;
The optical scanning device according to any one of claims 1 to 7, which emits light to the optical deflector;
A scanning mirror that turns back the light beam deflected by the optical deflector and draws a two-dimensional image on the screen;
An image irradiation unit comprising: An optical deflector;
A screen for diverging light at a desired divergence angle;
The optical scanning device according to any one of claims 1 to 7, which emits light to the optical deflector;
A scanning mirror that turns back the light beam deflected by the optical deflector and draws a two-dimensional image on the screen;
A concave mirror that projects the light beam emitted from the screen onto a projection surface;
An image display device comprising:

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