JP6705328B2 - Optical scanning device, image irradiation unit, and image display device - Google Patents

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 has recently begun to be used, in which light is two-dimensionally or three-dimensionally scanned by laser scanning at high speed to obtain a display image utilizing the afterimage phenomenon of human eyes. A head-up display (HUD) housed in the dashboard of an automobile is an example of a laser scanning type image display device.

Since the display on the HUD is superimposed on the landscape and the road, the brightness required for the HUD needs to be a brightness that does not make the viewer feel uncomfortable with the brightness of the outside world. Specifically, in a bright background such as a snowy road, it is necessary to have a brightness that is comparable to that. Also, in a dark night, appropriate brightness that is not too dazzling is required.

In Patent Document 1, a plurality of stages of neutral density filters for adjusting the brightness of an image to be projected by changing the transmittance of the emitted laser light in stages are switched, and the light amount of the laser light is changed from a dark region to a bright region. The technique of changing to is disclosed.

However, according to the technique described in Patent Document 1, there is a problem 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 adjustment of the amount of light from high brightness to low brightness with a very simple configuration. The purpose is to provide a device.

To solve the above problems and achieve the object, an optical scanning apparatus of the present invention includes a light source unit that outputs light which is linearly polarized light and the light to have a polarization transmission axis corresponds to the polarization transmission axis And a linear polarizer that is a reflection type that reflects the light that is orthogonal to the polarization transmission axis, and has a predetermined incident angle with respect to the emission direction of the light so that the light is incident. A rotatable filter that is disposed in the optical path of the light with inclination, a photodetector that is provided in the optical path of the reflected light of the linear polarizer in the filter, and detects the light intensity of the reflected light, and the filter. A driving unit that rotates and moves the incident position of the light in the linear polarizer, a dimming information input unit that inputs dimming information, and a rotation of the filter that is predetermined according to the dimming information. A control unit that controls the drive unit to move the filter so as to form an angle and tilts the polarization transmission axis of the linear polarizer.

According to the present invention, it is possible to achieve continuous adjustment of the amount of light from high brightness to low brightness with a very simple configuration.

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

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

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

The HUD 1 makes, for example, navigation information (for example, information on speed, mileage, etc.) necessary for operating the moving body visible through a windshield (front windshield) 50 of the moving body. In this case, the windshield 50 also functions as a transflective member that transmits part of the incident light and reflects at least part of the remaining light. 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, for example, image information from an image data output device such as a personal computer, a memory, a hard disk, various disc players, a video conference terminal, a tablet terminal, and a smartphone. It should be noted that examples of the image information include information on driving and operation of vehicles and the like. The HUD 1 irradiates the windshield 50 with light based on the image emitted from the image emitting unit 60 via the concave mirror 40. Thereby, 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.

The optical scanning device 10, which will be described in detail later, emits laser light (combined light) obtained 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 oscillates 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 folds the light beam deflected by the optical deflector 15 and draws a two-dimensional image (intermediate image) on the screen 30 which 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 suitable. The light flux emitted from the screen 30 is projected onto the windshield 50, which is a projection surface, via a single concave mirror 40. As a result, 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.

Note that the HUD 1 may have a configuration in which, apart from the windshield 50, a partial reflecting mirror (combiner) having the same function (partial reflection) as the windshield 50 is provided as a projection surface.

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, from an external device, dimming information which is an index of the luminance of the HUD 1, that is, the luminance of the projected image. 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 the 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 the 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, flash memory, or the like. The recording member read or written by the optical drive is a CD-ROM (Compact Disk Read Only Memory), a CD-R (Compact Disk Recordable), a DVD (Digital Versatile Disk), or the like. The network I/F 105 transmits/receives various information to/from an external device.

The programs stored in the ROM 102 and the HDD 104 are provided in a form of an installable or executable file recorded on a computer-readable recording member such as a CD-ROM, a CD-R, or a DVD. It may be configured as follows.

Further, the program stored in the ROM 102 or the HDD 104 may be stored in 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.

The light source unit 11 will be described in detail below.

As shown in FIG. 2, the light source unit 11 includes a plurality of light source elements 111R, 111B, 111G having a single or a plurality of light emitting points. The light source elements 111R, 111B, 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 red light beam (wavelength λR=640 nm). The light source element 111B is a blue laser and emits a light flux of blue light (wavelength λB=445 nm). The light source element 111G is a green laser and emits a light flux of green light (wavelength λG=530 nm).

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

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

The light fluxes coupled by the coupling lenses 112R, 112B, 112G are cut at their peripheral portions by the provided apertures 113R, 113B, 113G and shaped into a beam having a desired size. The apertures 113R, 113B, 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.

Further, as shown in FIG. 2, the light source unit 11 includes a combining element 115 and a lens 116. The combining element 115 combines the respective light fluxes shaped by the apertures 113R, 113B, 113G in the optical path. The combining element 115 is a plate-shaped or prism-shaped dichroic mirror, reflects/transmits a light beam according to a wavelength, and combines the light beams into one optical path. It should be noted that the polarization axes of the light source elements 111R, 111B, and 111G for each of the RGB colors need to be aligned so that the combined laser light becomes linearly polarized light.

Note that the laser light source (light source elements 111R, 111B, 111G) described above is suitable for the light source light having linearly polarized light in the present embodiment, but it is not necessarily the laser light source itself. That is, the light emitted from a non-polarized LED (Light Emitting Diode) or the like may be 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 combines a polarized beam splitter and a ½ wavelength plate to convert the polarized light in one direction into a linearly polarized light.

The light fluxes synthesized by the synthesizing element 115 are guided by the lens 116 toward the reflecting surface of the optical deflector 15. The lens 116 is a meniscus lens having a concave surface facing the optical deflector 15.

In addition, the light source unit 11 arranges the light reducing means 120 for realizing the light reduction for the laser light in the optical path after the combination by the combining element 115. Extinction device 120 includes a rotary motor 121 as a driving part, and a circular filter 122 is rotationally driven by the rotary motor 121 be rotatable. As shown in FIG. 2, the filter 122 of the dimming means 120 is arranged so as to be substantially perpendicular to the emission direction X of the laser light.

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 the 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 light reduction means 120 according to the light reduction rate. The control unit 5 drives and controls the rotary 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 showing an example of control of the dimming means 120. As shown in FIG. 4, the filter 122 has a high transmittance region 122a and a linear polarizer 122b 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 center of rotation coincides with the rotation shaft 121a of the rotation motor 121.

The linear polarizer 122b of the present embodiment is a reflective type. When the linear polarizer 122b is a reflection type, the component corresponding to the polarization transmission axis of the linear polarizer 122b is transmitted, and the component orthogonal to the polarization transmission axis is reflected. By employing the reflective linear polarizer 122b in this way, it is possible to suppress heat generation due to absorption when the extinction ratio is high, and it is possible to improve the reliability of the device.

The linear polarizer 122b utilizes a partial polarization of light reflected at an angle with respect to the reflection surface, and uses a multiple reflection to generate linearly polarized light. PBS). Further, the linear polarizer 122b may be a wire grid type polarizer having a fine lattice structure made of metal.

In addition, although the linear polarizer 122b of the present embodiment is described as a reflection type, it is not limited to this and may be an absorption type. If the linear polarizer 122b is an absorption type, the component corresponding to the polarization transmission axis of the linear polarizer 122b is transmitted, and the component orthogonal to the polarization transmission axis is absorbed. Absorption polarizers include film polarizers made of polymers.

The control unit 5 controls the laser light (linearly polarized light) combined by the combining element 115 to be incident on a desired region of the filter 122 of the light reduction unit 120.

The example illustrated in FIG. 4A is an example in which the rotation motor 121 is drive-controlled by the control unit 5 so that the incident position of the laser light combined by the combining element 115 is set to the high transmittance region 122 a of the filter 122. .. At the position of the filter 122 shown in FIG. 4A, the light reduction means 120 does not reduce the laser light.

In the example shown in FIG. 4B, the controller 5 drives and controls the rotary motor 121 so that the incident position of the laser light combined by the combining element 115 is the linear polarizer 122b of the filter 122. This is an example in which the state shown in FIG. 4A is rotated.

As described above, the laser light combined by the combining element 115 has linearly polarized light before entering the filter 122. The polarization transmission axis of the linear polarizer 122b is set so that the transmittance of the laser light becomes highest 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 slightly tilted from the polarization axes of the light source elements 111R, 111B, and 111G. That is, the light reduction unit 120 limits the transmission of the laser light according to the rotation of the filter 122, and realizes the light reduction for the laser light.

In the example shown in FIG. 4C, the control unit 5 drives and controls the rotary motor 121 so that the linear transmission axis of the linear polarizer 122b is changed from the state shown in FIG. In this example, the filter 122 is rotated to a vertical position so that the laser light is incident on the filter 122. In this state, the linear polarization axis of the laser light and the polarization transmission axis of the linear polarizer 122b are perpendicular to each other, which is a so-called crossed Nicol relationship, and the transmittance of the laser light can be substantially 0%.

That is, according to the light reduction 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 laser light. The horizontal axis of the filter 122 shown in FIG. 5 represents the rotation angle (deg). The rotation angle of 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 in which the linear polarization axis of the laser light and the polarization transmission axis of the linear polarizer 122b are perpendicular to each other and the light is substantially shielded.

As shown in FIG. 5, the filter 122 has a transmittance of laser light at a position where the linear polarization axis of the laser light and the polarization transmission axis of the linear polarizer 122b are parallel to each other (parallel nicol). It will be 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 perpendicular to each other in a crossed Nicols state. Become. It should be noted that although the light absorption and the depolarization do not actually occur and the transmittance of the laser light does not become 0%, it is assumed here to be 0% for the sake of explanation.

Further, as shown in FIG. 5, the transmittance of the laser light is 100% between the rotation angle of 0 degree and the rotation angle of −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 the case where no member is interposed. The high transmittance region 122a of the filter 122 of the present embodiment has a transmittance close to 100% by inserting a transparent glass plate or an element corresponding thereto. Further, the high transmittance region 122a of the filter 122 has no polarization dependency, and the transmittance can be matched with the state of the maximum transmittance (parallel nicol) of the linear polarizer 122b.

When the power of the laser light from the light source elements 111R, 111B, 111G is used to the maximum, the control unit 5 determines the rotation angle of the filter 122 so that the rotation angle is in the range of −10 degrees to 0 degrees. The rotation motor 121 is drive-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 reaches 0 degree. However, such a decrease in transmittance does not pose a problem because it is difficult to visually recognize the change. Further, as shown in FIG. 5, as the filter 122 is rotated, the transmittance becomes proportional to the square of cos θ and decreases from the position at the angle of 0 degree. As described above, the control unit 5 controls the rotation of the filter 122, so that the desired dimming of the laser light is possible.

Here, FIG. 6 is a diagram showing an example of the relationship between the light control information input by the light control information input unit 8 and the light amount of the laser light. FIG. 6A is a graph showing the relationship between dimming information and the amount of laser light, and FIG. 6B is a diagram showing a table showing the relationship between the rotation angle, the transmittance, and the amount of light in each dimming information. .. In the example shown in FIG. 6, 12 levels of light control are set as the light control information that is an index of the brightness of the projected image of the HUD 1.

As shown in FIG. 6A, in the 12 light control steps set as the light control information, the light amount ratio of the laser light before and after the first step is set to be substantially constant. This constant value was set to 1/2. As a result, the change in the amount of light is not a linear change but is visually perceived as a gradual change. It should be noted that halving the amount of laser light is considered to be a comparatively large amount of change, but is visually sufficient. According to Webber-Fechner's law, perceptual intensity is proportional to the logarithm of the stimulus.

The control unit 5 stores in the HDD 104 the correspondence relationship between the dimming stage and the angle information of the rotation angle of the filter 122, which is shown in the table shown in FIG. As shown in FIG. 6B, the 12 levels of dimming according to the present embodiment enable dimming to a minimum value of 8 cd/cm ² when the maximum brightness of HUD 1 is 10000 cd/cm ^2. , The space between them is divided into 10.

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 brightness is high. On the other hand, in a stage where the light amount is small (Stage 8 to Stage 11, etc.), the rotation angle of the filter 122 has a small change in each stage. By not linearly changing with respect to the dimming stage in this way, the dimming rate can be changed logarithmically. That is, the control unit 5 controls the rotation of the filter 122 in a rough step when the light reduction rate is small and bright, and controls the rotation of the filter 122 in a fine step when the light reduction rate is high and the brightness is dark. By doing so, the change in the light amount can be logarithmically performed. By changing logarithmically, the change level in human perceptual recognition can be a natural change, and a higher quality HUD1 can be realized.

As described above, the dimming step is changed by the rotational movement so that the angle change of 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. You can As a result, the structure of the light-attenuating means 120 can be reduced, and the HUD 1 as a smaller image display device can be realized.

It should be noted that in the present embodiment, one step is the 1/2 step rotation control in which the light amount of the laser light is set to a value at which the light quantity is halved, but the invention is not limited to this. The rotation may be controlled so that the light quantity ratio of the laser light before and after one stage is constant. For example, the number of steps may be 1/√2, which is a half. In this case, since one step is set for each of 12 steps, there are 23 steps. Naturally, stepless dimming is also possible by setting the light quantity ratio of the laser light of one stage before and after the constant value to a smaller value and making the step of the rotation angle as small as possible.

As described above, according to the present embodiment, it is possible to realize continuous adjustment of the amount of light from high brightness to low brightness with a very simple configuration, and improve the quality of the HUD 1 as an image display device while It is possible to realize an inexpensive image display device with a small number of points, high mass productivity, and high reliability.

Note that the control unit 5 may perform current control on the light source elements 111R, 111B, and 111G for each color of RGB to reduce the light. This enables finer control.

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

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

The second embodiment differs from the first embodiment in that the filter 122 of the dimming means 120 is arranged so as to make the laser light incident with a predetermined incident angle. Is becoming

In the first embodiment, as shown in FIG. 2, the filter 122 of the dimming means 120 is arranged so as to be substantially perpendicular to the emission direction X of the laser light. 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 or the light source elements 111R, 111B, 111G. In this case, the reflected light may cause an unexpected problem such as heat generation of the combining element 115 and the light source elements 111R, 111B, and 111G.

Here, FIG. 7 is a diagram showing an arrangement example of the filters 122 of the light attenuating means 120 according to the second embodiment. As shown in FIG. 7, in the present embodiment, the filter 122 of the dimming means 120 is arranged so as to be inclined with respect to the emission direction X of the laser light so that the laser light is incident with a predetermined incident angle. Has been done. Therefore, 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, in the dimming means 120 of the present embodiment, the photodetector 123 is provided in the optical path of the reflected light from the linear polarizer 122b. Thereby, the control unit 5 can calculate the light amount of the emitted light of the light source unit 11 by obtaining the detected amount of the light intensity of the reflected light by the photodetector 123. That is, the control unit 5 can sequentially monitor whether the extinction ratio has a desired value.

As described above, according to the present embodiment, the filter 122 is arranged so as to be inclined so that the incident angle of the light incident on the reflective linear polarizer 122b is not vertical. 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 control unit 5 includes the photodetector 123 that detects the light intensity of the reflected light by the reflective linear polarizer 122b, and the control unit 5 obtains the light intensity of the reflected light obtained by the photodetector 123. The extinction ratio of the laser light is detected based on the detection amount of. As a result, it is possible to determine whether or not the desired extinction ratio is set, and it is possible to realize the HUD 1 as a more reliable image display device.

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

JP, 2014-149493, A

Claims (6)

A light source unit that outputs linearly polarized light,
And have a polarization transmission axis is transmitted through the light corresponding to the to the polarization transmission axis, have a linear polarizer is a reflective for reflecting the light perpendicular to the polarization transmission axis has a predetermined angle of incidence And a rotatable filter that is arranged in the optical path of the light with an inclination with respect to the emission direction of the light so that the light is incident ,
A photodetector provided in the optical path of the reflected light at the linear polarizer in the filter, and detecting the light intensity of the reflected light,
A driving unit that rotationally drives the filter to move the incident position of the light in the linear polarizer,
A dimming information input section for inputting dimming information,
A control unit that tilts the polarization transmission axis of the linear polarizer by controlling the drive unit to move the filter so that the rotation angle of the filter is predetermined according to the dimming information.
Equipped with
The control unit detects the extinction ratio of the light based on the detection amount of the light intensity of the reflected light obtained by the photodetector,
An optical scanning device characterized by the above. The filter has the same center of rotation as the linear polarizer and is disposed adjacent to the linear polarizer, further has a high transmittance region having a higher transmittance of the light than 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, wherein: The control unit moves the filter so that the light amount ratio of the light before and after one step is substantially constant, on condition that a plurality of dimming steps are set as the dimming information.
The optical scanning device according to claim 1 or 2, characterized in that. The control unit reduces the angle change of the 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, wherein An optical deflector,
A screen that diverges the laser at the desired divergence angle,
An optical scanning device according to any one of claims 1 to emit light 4 to the optical deflector,
A scanning mirror for folding back the light beam deflected by the optical deflector and drawing a two-dimensional image on the screen;
An image irradiation unit comprising: An optical deflector,
A screen that diverges the light at the desired divergence angle,
An optical scanning device according to any one of claims 1 to emit light 4 to the optical deflector,
A scanning mirror for folding back the light beam deflected by the optical deflector and drawing 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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