JP6857015B2 - Image display device - Google Patents

Description

The present invention relates to an image display device in which an image corresponding to an intermediate image is projected onto a display area by a projection optical system, whereby a virtual image based on the projected image is formed.

The vehicle-mounted head-up display described in Patent Document 1 has a projection optical system for projecting an image displayed on a display information source toward the windshield of a vehicle, and allows the observer to see the reflected light from the windshield. It is guided into the eyeball, and in the optical path between the windshield and the display information source, a correction optical member for correcting the distortion and tilt of the image caused by the reflection of the windshield can be selectively arranged. It is composed. As a result, we are trying to provide a highly versatile in-vehicle head-up display that can observe a good image without being affected by the difference in the shape of the windshield.

Japanese Unexamined Patent Publication No. 2005-202145

In the in-vehicle head-up display described in Patent Document 1, the correction optical member constitutes a part of the projection optical system, and in the configuration shown in the embodiment, a plurality of optical members constituting the projection optical member are used. It is placed in a position where it is sandwiched. When the correction optical member is arranged at such a position, the size of the correction optical member must be increased according to the distance from the image display area, the angle of the windshield, etc., and depending on this dimension, the correction optical member must be increased. There was a problem that a part of the light was exposed from the dashboard and the reflected light from this exposed part reached the driver side.

Therefore, the present invention provides an image display device capable of displaying an image of a certain quality using the same projection optical system while suppressing a change in the size of the correction optical system even if the distance between the display area and the projection optical system changes. The purpose is to provide.

In order to solve the above problems, the image display device of the present invention includes an intermediate image display body on which an intermediate image is formed, a projection optical system that projects an image corresponding to the intermediate image onto a display area, and the intermediate image display. A correction optical system arranged at a predetermined position between the body and the projection optical system and correcting the emitted light from the intermediate image display body is provided, and the correction optical system includes a holder and a correction held by the holder. The holder has a lens, and the holder can move between a position where the correction lens faces the intermediate image display and a retracted position where the correction lens does not face the intermediate image display. The correction lens can be replaced at the same time, a virtual image visible to the subject is formed based on the image projected on the display area, and the correction lens is selected according to the conditions relating to the display area. It is characterized by that.
As a result, the same projection optical system is used even if conditions such as the distance between the display area and the projection optical system and the installation angle of the display area change depending on the environment in which the image display device is installed, for example, the type of vehicle to be installed. It is possible to display an image of a certain quality without increasing the size of the correction optical system.

In the image display device of the present invention, the conditions relating to the display area preferably include at least one of the distance between the display area and the projection optical system and the installation angle of the display area.
As a result, the same projection optical system can be used even if the distance between the display area and the projection optical system or the installation angle of the display area changes due to the difference in the environment in which the image display device is installed, and the correction optical system is large. It is possible to display an image of a certain quality by suppressing the change.

In the image display device of the present invention, the correction optical system is preferably arranged in the vicinity of the intermediate image display body.
As a result, even if the position of the eyes or face of the viewer of the projected image changes and the viewpoint or line of sight changes, the distortion of the projected image can be suppressed to the same extent as when facing the front front.

In the image display device of the present invention, the image display device is mounted in the vehicle, the target person is the driver of the vehicle, and the display area is set to the windshield of the vehicle or a combiner arranged inside the windshield. It is preferable that the virtual image is formed in front of the windshield, and the conditions regarding the display area are determined according to the type of vehicle.
As a result, the same projection optical system can be used and correction optics can be used even if conditions such as the distance between the display area and the projection optical system and the installation angle of the display area change depending on the type of vehicle in which the image display device is installed. It is possible to display an image of a certain quality while suppressing the system from becoming large.

In the image display device of the present invention, the correction optical system is held by the holder, and by mounting the holder, the correction optical system according to the conditions regarding the display area is positioned at a predetermined position between the intermediate image display body and the projection optical system. Is placed in.
This makes it possible to easily and quickly select a correction optical system suitable for the installation environment of the image display device.

In the image display device of the present invention, the projection optical system preferably has at least two projection mirrors that magnify and reflect the incident light.
As a result, in the projection optical system, the image light can be enlarged while bending the optical path, so that the size can be reduced.

According to the present invention, an image display device capable of displaying an image of a certain quality using the same projection optical system while suppressing a change in the size of the correction optical system even if the distance between the display area and the projection optical system changes. Can be provided.

It is a side view which shows the schematic structure of the head-up display device which concerns on embodiment of this invention. (A) is a perspective view showing the configuration of the correction lens shown in FIG. 1, and (B) is a side view showing the arrangement of the diffuser and the correction lens when the holders are in opposite positions. (A) is a perspective view showing the configuration of the correction lens according to the second embodiment, and (B) is a side view showing the configuration of the correction lens shown in (A). (A) is a perspective view showing the configuration of the correction lens according to the third embodiment, and (B) is a side view showing the configuration of the correction lens shown in (A). It is a side view which shows the schematic structure of the head-up display device which concerns on Comparative Example 1. FIG. (A) is a perspective view showing the configuration of the correction lens in Comparative Example 1, and (B) is a side view showing the configuration of the correction lens shown in (A). FIG. 5 is a diagram showing distortion of an image when a rectangular intermediate image is projected onto a driver's face position on a diffuser in the first embodiment. FIG. 5 is a diagram showing distortion of an image when a rectangular intermediate image is projected onto a driver's face position on a diffuser in the second embodiment. FIG. 3 is a diagram showing distortion of an image when a rectangular intermediate image is projected onto the position of the driver's face on the diffuser in the third embodiment. In Comparative Example 1, it is a figure which shows the distortion of the image when the intermediate image which made it rectangular on the diffuser is projected to the position of the driver's face. In Comparative Example 2, it is a figure which shows the distortion of the image when the intermediate image which made it rectangular on the diffuser is projected to the position of the driver's face. FIG. 3 is a diagram showing distortion of an image when a rectangular intermediate image is projected onto the position of the driver's face on the diffuser in Comparative Example 3. In Comparative Example 4, it is a figure which shows the distortion of the image when the intermediate image which made it rectangular on the diffuser is projected to the position of the driver's face.

Hereinafter, the head-up display device as an embodiment of the image display device of the present invention will be described in detail with reference to the drawings. In the present embodiment, an in-vehicle head-up display device is taken as an example, but the image display device of the present invention is not limited to this, and can be applied to a device that projects an image on a screen or the like.

FIG. 1 is a side view showing a schematic configuration of the head-up display device 10 according to the present embodiment. FIG. 2A is a perspective view showing the configuration of the correction lens 13 shown in FIG. 1, and FIG. 2B is a side view showing the arrangement of the diffuser 12 and the correction lens 13 when the holder 14 is at the facing position P1. ..
The head-up display device 10 shown in FIG. 1 includes an optical engine 11, a diffuser 12 as an intermediate image display body, a correction lens 13 as a correction optical system, a holder 14 holding the correction lens 13, and a projection optical system 20. And.

The optical engine 11 is a unit that forms an intermediate image on the diffuser 12. The optical engine 11 enters the diffuser 12 with a visible light laser or LED as a light source, a scanning mirror that reflects the light emitted from the light source, and light reflected from the scanning mirror as light parallel to the optical axis 12c of the diffuser 12. It is composed of a collimator lens to be operated, a drive circuit for driving the light source and the scanning mirror, and a storage circuit. For example, an optical engine is composed of DLP (Digital Light Processing). In the case of DLP, the scanning mirror is a DMD (Digital Mirror Device).

The diffuser 12 as an intermediate image display body is, for example, a microlens array, a diffuser plate, a random phase plate, or a diffraction grating.
Further, the optical engine 11 is driven according to the control data previously stored in the storage circuit corresponding to the intermediate image formed on the diffuser 12.

As a two-dimensional scanner, the scanning mirror of the optical engine 11 rotates its reflecting surface around two rotation axes orthogonal to each other. In this scanning mirror, one line of light is incident on the collimator lens by rotation about the first rotation axis, and after a predetermined amount of rotation about the second rotation axis, the second By rotating around the rotation axis of 1, the light for the next one line is incident on the collimator lens, and by repeating these, the light for one frame is irradiated on the collimator lens. The light applied to the collimator lens is emitted to the diffuser 12, and an intermediate image is formed on the diffuser 12.

Further, the DMD or LCOS (trademark, Liquid crystal on silicon) can be used instead of the scanning mirror. When the DMD is used, the incident light from the light source is reflected by each of the plurality of micromirrors arranged in a matrix to form an intermediate image on the diffuser 12. As the LCOS, either a transmission type or a reflection type can be used, and an intermediate image is formed on the diffuser 12 by the transmitted light or the reflected light in the LCOS.

Furthermore, instead of the optical engine 11 and the diffuser 12, a self-luminous device such as an LCD (liquid crystal display) or an EL element (electroluminescence element) can be used.

As shown in FIG. 1 or FIG. 2B, a holder is on an extension of the optical axis 12c of the diffuser 12 and on an optical path from the exit surface 12a of the diffuser 12 toward the projection optical system 20 along the direction T. The correction lens 13 held by 14 is arranged. That is, the correction lens 13 is arranged between the diffuser 12 and the projection optical system 20. The correction lens 13 is a plano-convex positive lens having a convex surface facing the projection optical system 20 side, and is arranged so that its optical axis 13c overlaps with an extension line of the optical axis 12c of the diffuser 12. More specifically, as shown in FIG. 2, the incident surface 13a on which the light emitted from the diffuser 12 is incident is formed of a plane orthogonal to the incident direction T, and the emitted surface 13b is a convex surface protruding toward the projection mirror 21. Yes, the shape of the convex surface is composed of a single spherical surface, an aspherical surface, a free curved surface, or a combination thereof according to the correction function and the condensing function of the correction lens 13. The correction lens 13 collects the light emitted from the diffuser 12 and emits it to the projection mirror 21 side located on the extension line of the optical axis 13c. Since the correction lens 13 has a condensing function, the optical path of the image light from the diffuser 12 to the projection optical system 20 can be narrowed down, and the loss of the image light can be suppressed.
Here, the direction T shown in FIG. 1 is a direction along the optical axis 12c of the diffuser 12 and the optical axis 13c of the correction lens 13, and is a direction from the correction lens 13 toward the projection mirror 21 side.

The holder 14 holds the correction lens 13 so as not to prevent the light incident on the correction lens 13 from the diffuser 12 from being emitted to the projection optical system 20 side, and is attached to the optical axis 12c of the diffuser 12 by a drive mechanism (not shown). It can move along the vertical direction D (the direction of the arrow shown in FIG. 1). The holder 14 has either one of a facing position P1 in which the diffuser 12 and the correction lens 13 face each other in the moving direction D, and a retracted position P2 in which the diffuser 12 and the correction lens 13 do not face each other when retracted from the front of the diffuser 12. Move to be located in. At the retracted position P2, it is possible to replace the holder with another holder that holds another correction lens. The configuration is not limited to this mode, and any configuration may be used as long as it can be replaced with another correction lens.

The correction lens 13 includes conditions relating to the display area WA of the windshield W, for example, the distance L (FIG. 1) between the projection lens 22 of the projection optical system 20 and the display area WA, the installation angle S of the display area WA, and the display area WA. It is selected according to at least one of the distance to the driver's face and eyes, the flat area of the display area WA, and the projection magnification, and in particular, according to at least one of the above distance L and the installation angle S. Is selected. This makes it possible to mount a holder holding a correction optical system having different configurations and optical characteristics according to the type of vehicle on which the head-up display device 10 is mounted. More specifically, the output from the intermediate image display body formed by the diffuser 12 corresponds to the difference in the distance and direction between the head-up display device 10 and the windshield W and the driver's eyes depending on the vehicle type. The emission light is corrected by the correction lens 13. Here, the correction by the correction lens 13 includes the correction of the optical path and the optical characteristics of the light emitted from the intermediate image display body. As a result, an image accurately corresponding to the intermediate image formed by the diffuser 12 can be projected onto the windshield W without changing the arrangement of the optical engine 11, the diffuser 12, and the projection optical system 20. It is possible to form a virtual image corresponding to the projected image in front of the windshield W.

As shown in FIG. 2B, when the holder 14 is in the facing position P1, the correction lens 13 is located in the vicinity of the diffuser 12. That is, the exit surface 12a of the diffuser 12 and the incident surface 13a of the correction lens 13 are at a distance such that the emission light from the emission surface 12a of the diffuser 12 is incident on the correction lens 13 at a certain ratio or more, for example, 98% or more. Facing each other. As a result, scattered light, which is the light emitted from the diffuser 12, can be completely incident on the correction lens 13 without increasing the size in the plane orthogonal to the optical axis 13c of the correction lens 13, and the correction lens 13 is mounted. The distortion of the image can be corrected according to the type of the vehicle, and therefore, the image quality of the intermediate image formed on the diffuser 12 can be given to the projection mirror 21 side without deteriorating.

The correction optical system may be composed of a plurality of lenses instead of one lens as in the correction lens 13. In this case, different lenses may have a focusing function and a distortion correction function. Further, a lens having a magnifying or reducing function may be included.

The image light including the image formed on the diffuser 12 and further corrected by the correction lens 13 is incident on the projection mirror 21 of the projection optical system 20. The projection optical system 20 includes two projection mirrors 21 and 22. By using a projection mirror as the projection optical system, it becomes easier to suppress various optical aberrations as compared with the magnifying projection optical system using a lens. Further, since the image light is enlarged while bending the optical path by using the two projection mirrors, the size of arranging the projection optical system can be suppressed to be small.

As shown in FIG. 1, the projection mirror 21 is a concave mirror (magnifying glass) having a reflecting surface 21r on the correction lens 13 side. The image light including the image corrected by the correction lens 13 is magnified and reflected by the projection mirror 21. As shown in FIG. 1, the projection mirror 22 is a concave mirror (magnifying glass) having a reflecting surface 22r on the projection mirror 21 side. The image light including the image reflected by the projection mirror 21 is magnified and reflected by the projection mirror 22.

The reflected light of the projection mirror 22 is projected onto the display area WA of the windshield W of the vehicle as the projected object. Since this windshield W functions as a semi-reflective surface, the incident image light is reflected toward the driver as the target person, and a virtual image is formed at the front position P of the windshield W, so that the driver's eyes In E, information corresponding to the intermediate image formed on the diffuser 12 appears to be displayed in front of the steering wheel.
Here, as shown in FIG. 1, the display region WA has an inclination angle S upward with respect to the horizontal plane H orthogonal to the direction of gravity. Further, the display area WA has a rectangular planar shape, and the distance from the center position to the center position of the reflection surface 22r of the projection mirror 22 is L.

The projection optical system may be configured by combining a plurality of concave mirrors and reflectors instead of the two concave mirrors as in the projection optical system 20 having the configuration shown in FIG. For example, in the case of one reflector and one concave mirror, the light emitted from the correction lens 13 is reflected by the reflector to change the traveling direction, and the light from the reflector is magnified and reflected by the concave mirror. It is projected on the windshield W. This increases the degree of freedom in arranging each member and facilitates the design of the size and shape of the device.

Further, in the above embodiment, the reflected light from the projection mirror 22 is projected onto the windshield W as the projected object, but a combiner is arranged inside the windshield W as the projected object, and the light is projected from the projection mirror 22. It is also possible to project the reflected light of the above onto the combiner. In this configuration, since the combiner functions as a semi-reflective surface, the incident image light is reflected toward the driver as the target person, and a virtual image is formed at the front position P of the windshield W.

Hereinafter, examples will be described.
(Example 1)
The correction lens arranged between the diffuser 12 and the projection mirror 21 in the first embodiment is the correction lens 13 shown in FIGS. 1 and 2 (A) and 2 (B). The correction lens 13 is assumed to be installed in an SUV (sport utility vehicle) under the following conditions.
(1) Tilt angle S of the display area WA of the windshield W with respect to the horizontal plane H: 36 degrees (2) Projection magnification: 6.0 times (3) From the center position of the display area WA to the center position of the reflection surface 22r of the projection mirror 22 Distance L: 173.7 mm
Here, the projection magnification is the ratio of the diagonal line of the image formed in the display area WA of the windshield W to the diagonal length of the image formed in the diffuser 12.

(Example 2)
FIG. 3A is a perspective view showing the configuration of the correction lens 33 in the second embodiment, and FIG. 3B is a side view showing the configuration of the correction lens 33 shown in FIG. 3A.
The correction lens in the second embodiment is the correction lens 33 shown in FIGS. 3A and 3B. The correction lens 33 is a plano-convex positive lens arranged on an optical path from the exit surface 12a of the diffuser 12 toward the projection optical system 20 along the direction T, similarly to the correction lens 13 of the first embodiment. In the correction lens 33, the incident surface 33a from the diffuser 12 side is a flat surface, the exit surface 33b to the projection optical system 20 side has a convex surface facing the projection optical system 20 side, and its optical axis 33c is the light of the diffuser 12. It is arranged so as to overlap the extension line of the shaft 12c. The correction lens 33 is assumed to be installed in the sedan under the following conditions.
(1) Tilt angle S of the display area WA of the windshield W with respect to the horizontal plane H: 34 degrees (2) Projection magnification: 5.96 times (3) From the center position of the display area WA to the center position of the reflection surface 22r of the projection mirror 22 Distance L: 170.3 mm

(Example 3)
FIG. 4A is a perspective view showing the configuration of the correction lens 43 in the third embodiment, and FIG. 4B is a side view showing the configuration of the correction lens 43 shown in FIG. 4A.
The correction lens in the third embodiment is the correction lens 43 shown in FIGS. 4A and 4B. Similar to the correction lens 13 of the first embodiment, the correction lens 43 is a plano-convex positive lens arranged on an optical path from the exit surface 12a of the diffuser 12 toward the projection optical system 20 along the direction T. In the correction lens 43, the incident surface 43a from the diffuser 12 side is a flat surface, the exit surface 43b to the projection optical system 20 side has a convex surface facing the projection optical system 20 side, and its optical axis 43c is the light of the diffuser 12. It is arranged so as to overlap the extension line of the shaft 12c. The correction lens 43 is assumed to be installed in a sports car under the following conditions.
(1) Tilt angle S of the display area WA of the windshield W with respect to the horizontal plane H: 30 degrees (2) Projection magnification: 5.5 times (3) From the center position of the display area WA to the center position of the reflection surface 22r of the projection mirror 22 Distance L: 155.4 mm

(Comparative Example 1)
FIG. 5 is a side view showing a schematic configuration of the head-up display device 100 according to Comparative Example 1. 6 (A) is a perspective view showing the configuration of the correction lens 103 in Comparative Example 1, and FIG. 6 (B) is a side view showing the configuration of the correction lens 103 shown in FIG. 6 (A).
As shown in FIG. 5, the head-up display device 100 of Comparative Example 1 does not provide the correction lens 13 and the holder 14 with respect to the head-up display device 10 shown in FIG. 1, and a window from the projection mirror 22. It has the same configuration except that the correction lens 103 is provided on the optical path to the shield W. Further, the direction R shown in FIG. 5 is a direction along the optical path from the center position of the reflection surface 22r of the projection mirror 22 to the center position of the display area WA.

It is assumed that the correction lens 103 of Comparative Example 1 is installed in the SUV under the following conditions that are the same as those of Example 1.
(1) Tilt angle S of the display area WA of the windshield W with respect to the horizontal plane H: 36 degrees (2) Projection magnification: 6.0 times (3) From the center position of the display area WA to the center position of the reflection surface 22r of the projection mirror 22 Distance L: 173.7 mm

The correction lens 103 in Comparative Example 1 is a flat-plate lens arranged on an optical path in which the reflected light from the reflecting surface 22r of the projection mirror 22 faces the windshield W. In the correction lens 103, both the incident surface 103a from the projection mirror 22 side and the exit surface 103b to the windshield W side are flat, and the optical axis 103c is arranged along the direction R.

(Comparative Examples 2 to 4)
Comparative Example 2 has a configuration in which the correction lens 13 is not provided with respect to the first embodiment.
Comparative Example 3 has a configuration in which the correction lens 33 is not provided as compared with Example 2.
Comparative Example 4 has a configuration in which the correction lens 43 is not provided as compared with Example 3.

7 to 13 are diagrams showing distortion of the image when the intermediate image formed in a rectangular shape on the diffuser 12 is projected on the position of the driver's face, and FIGS. Corresponds to ~ 4. (E) of each figure (FIG. 7 (E), FIG. 8 (E), FIG. 9 (E), FIG. 10 (E), FIG. 11 (E), FIG. 12 (E), FIG. 13 (E)) , The face is facing the front and the front, and the eye position (Eyepoint) is at the reference coordinates (X = 0, Y = 0). Here, the X coordinate is the coordinate in the horizontal direction, and the Y direction is the coordinate in the vertical direction.

On the other hand, in (A), (D), and (E) of each figure, the Y coordinate is +31.5, the position of the driver's eye is above the reference coordinate, and (C), In (F) and (I), the Y coordinate is -31.5, and the position of the driver's eye is below the reference coordinate.
Further, in (A), (B), and (C) of each figure, the X coordinate is +66.5, the position of the driver's eye is on the left side of the reference coordinate, and (G) and (H). In (I), the X coordinate is -66.5, and the position of the driver's eye is on the right side of the reference coordinate.

Looking at FIGS. 7 to 9 corresponding to the first to third embodiments, it can be seen that the distortion is small and the correction lens shows a high correction effect. Furthermore, comparing (E) in each figure with the other (A) to (D) and (F) to (I), even if the position of the driver's eyes is different, it is the same as the image in the reference coordinates. It can be seen that the distortion can be suppressed to a certain degree. Further, when each of FIGS. 7 (A) to 7 (I), each of FIGS. 8 (A) to 8 (I), and FIGS. 9 (A) to 9 (I) are compared with each other, the effects of the corrections are the same. It can be seen that the optimum correction effect can be obtained by selecting the correction lens according to the inclination angle S of the display area WA and the distance L from the display area WA to the reflection surface 22r of the projection mirror 22.

On the other hand, when FIG. 7 corresponding to Example 1 and FIG. 10 corresponding to Comparative Example 1 are compared, the area of each of the images shown in FIG. 10 is smaller than that of the image shown in FIG. , There is a lot of distortion. Therefore, it can be seen that the position of the correction lens is preferably between the diffuser 12 and the projection mirror 21 rather than between the projection mirror 22 and the windshield W.

Comparing FIGS. 7 and 11, 8 and 12, and 9 and 13, the images shown in FIGS. 11 to 13 corresponding to Comparative Examples 2 to 4 correspond to Examples 1 to 3. The area is smaller than the image to be displayed, and the distortion is large. Therefore, it can be seen that an image with suppressed distortion can be obtained by arranging the correction lens.
Although the present invention has been described with reference to the above-described embodiment, the present invention is not limited to the above-described embodiment, and can be improved or modified within the purpose of improvement or the idea of the present invention.

As described above, the image display device according to the present invention uses the same projection optical system and has a constant quality while suppressing a change in the size of the correction optical system even if the distance between the display area and the projection optical system changes. It is useful in that it can display the image of.

10 Head-up display device (image display device)
11 Optical engine 12 Diffuser (intermediate image display)
12a Exit surface 12c Optical axis 13 Correction lens (correction optical system)
13a Incident surface 13b Exit surface 13c Optical axis 14 Holder 20 Projection optical system 21, 22 Projection mirror 21r, 22r Reflection surface 33, 43 Correction lens 33a, 43a Incident surface 33b, 43b Exit surface 33c, 43c Optical axis H Horizontal plane L Distance P Forward position P1 Opposing position P2 Retracting position S Tilt angle W Windshield WA Display area

Claims (6)

An intermediate image display body on which an intermediate image is formed,
A projection optical system that projects an image corresponding to the intermediate image onto the display area,
It is provided with a correction optical system that is arranged at a predetermined position between the intermediate image display body and the projection optical system and corrects the light emitted from the intermediate image display body.
The correction optical system has a holder and a correction lens held by the holder, and the holder has a position where the correction lens faces the intermediate image display body and the correction lens is the intermediate image display body. Can be moved between the retracted position and the retracted position, and the correction lens can be replaced at the retracted position.
A virtual image visible to the subject is formed based on the image projected on the display area.
An image display device, wherein the correction lens is selected according to a condition relating to the display area. The image display device according to claim 1, wherein the condition relating to the display area includes at least one of a distance between the display area and the projection optical system and an installation angle of the display area. The image display device according to claim 1 or 2, wherein the correction optical system is arranged in the vicinity of the intermediate image display body. The image display device according to any one of claims 1 to 3, wherein the correction lens is a plano-convex positive lens in which an incident surface facing the intermediate image display body is a flat surface. The image display device is mounted in the vehicle and
The subject is the driver of the vehicle and
The display area is set in the windshield of the vehicle or a combiner arranged inside the windshield.
The virtual image is formed in front of the windshield.
The image display device according to any one of claims 1 to 4 , wherein the conditions relating to the display area are determined according to the type of the vehicle. The image display device according to any one of claims 1 to 5, wherein the projection optical system has at least two projection mirrors that magnify and reflect incident light.

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