Image projection device

Abstract

To provide an image projection device which can achieve space-saving and improvement of the design flexibility while displaying a meter or the like and projecting an auxiliary image as a virtual image.SOLUTION: An image projection device (100) for projecting a projection image (70) to a display unit (60) for displaying a virtual image comprises: an image irradiation unit (10) which irradiates an image with light; a light branching unit (20) which branches the light irradiated on the image into at least the first image light and the second image light; first optical units (31, 32) which emit the first image light via the display unit (60) in the view point direction as a projection image (70); and a second optical unit (33) which emits the second image light in the view point direction without the display unit (60).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an image projection device, and more particularly to an image projection device that irradiates a projection image onto a display unit for displaying a virtual image.

Background Art

[0002] Conventionally, as a device for displaying various information in a vehicle, an instrument panel that lights up icons has been used. In addition, with the increase in the amount of information to be displayed, it has also been proposed to embed an image display device in the instrument panel or to configure the entire instrument panel with an image display device.

[0003] However, since the instrument panel is located below the vehicle's front glass (windshield), in order for the driver to visually recognize the information displayed on the instrument panel, it is necessary to move the line of sight downward during driving, which is not preferable. Therefore, a head-up display (hereinafter referred to as HUD: Head Up Display) that projects an image onto the front glass so that the driver can read the information when visually recognizing the front of the vehicle has also been proposed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] FIG. 6 is a schematic diagram showing a conventional information presentation method using the HUD device 1. FIG. 6(a) shows the device arrangement inside the vehicle, FIG. 6(b) shows the instrument images 2a displayed on the meter unit 2, and FIG. 6(c) shows the auxiliary image 3a projected as a virtual image 3. In the conventional information presentation method, the meter unit 2 is installed inside the vehicle separately from the HUD device 1, and the virtual image 3 is projected from the HUD device 1 through the windshield 4. Here, for the instruments defined by regulations, they are displayed as instrument images 2a on the meter unit 2. Also, the auxiliary image 3a for assisting driving is projected as a virtual image 3. In recent years, there have also been proposals to improve the design of the instruments using a liquid crystal display device or the like as the meter unit 2.

[0006] As shown in FIG. 6, during the running of the vehicle, since the virtual image 3 is projected downward by several degrees (4 degrees in FIG. 6) from the horizontal direction, the driver 5 can reduce the eye movement for visually recognizing the auxiliary information. Also, by further moving the line of sight downward (20 degrees in FIG. 6), the instruments displayed on the meter unit 2 can be visually recognized well. However, in the prior art, since it is necessary to arrange the HUD device 1 and the meter unit 2 respectively inside the instrument panel of the vehicle, it has been difficult to save space. Also, the position where the meter unit 2 is installed is inevitably determined to be a position where the driver 5 can visually recognize well, so there is a problem that the design freedom when arranging the HUD device 1 is low.

[0007] Therefore, the present invention has been made in view of the above conventional problems, and an object thereof is to provide an image projection device capable of saving space and improving the design freedom while displaying instruments and projecting an auxiliary image as a virtual image.

Means for Solving the Problems

[0008] In order to solve the above problems, an image projection apparatus of the present invention is an image projection apparatus that irradiates a projection image onto a display unit for displaying a virtual image, and includes an image irradiation unit that irradiates an image, an optical branching unit that branches the light for irradiating the image into at least a first image light and a second image light, a first optical unit that irradiates the first image light as the projection image in the viewpoint direction through the display unit, and a second optical unit that irradiates the second image light in the viewpoint direction without passing through the display unit. , the optical branching unit includes a prism disposed on a path of a part of the light irradiated from the image irradiation unit, the prism constitutes a part of the first optical unit, and an infrared light absorbing material is contained in the base material. It is characterized by this.

[0009] In such an image projection apparatus of the present invention, the image irradiated from the image irradiation unit is branched into a first image light and a second image light by the optical branching unit, the first image light is irradiated by the first optical unit through the display unit, and the second image light is irradiated by the second optical unit without passing through the display unit. Thereby, while displaying instruments with the second image light and projecting an auxiliary image as a projection image (virtual image) with the first image light, it is possible to achieve space saving and an improvement in design freedom.

[0013] Further, in order to solve the above problems, an image projection apparatus of the present invention is an image projection apparatus that irradiates a projection image onto a display unit for displaying a virtual image, and includes an image irradiation unit that irradiates an image, and a light branching unit that branches the light irradiating the image into at least a first image light and a second image light, a first optical unit that irradiates the first image light as the projection image in the viewpoint direction through the display unit, and a second optical unit that irradiates the second image light in the viewpoint direction without passing through the display unit, and the second optical unit is characterized by including a retardation film that converts the second image light into circularly polarized light.

[0014] Also, in one aspect of the present invention, Another prism is included in a part of the second optical unit.

[0015] Also, in one aspect of the present invention, the second optical unit includes a transmissive screen on the back surface of which the second image light is irradiated.

[0016] Also, in one aspect of the present invention, the second optical unit includes a magnifying optical unit that magnifies and irradiates the second image light.

Effect of the Invention

[0017] In the present invention, it is possible to provide an image projection apparatus capable of achieving space saving and an improvement in design freedom while displaying instruments and projecting an auxiliary image as a virtual image.

Brief Description of the Drawings

[0018] [FIG. 1] It is a schematic diagram showing the configuration of the image projection apparatus 100 according to the first embodiment. [FIG. 2] It is a schematic diagram showing the image irradiated from the image irradiation unit 10. [FIG. 3] It is a graph showing the relationship between the incident angle of light on the windshield 60 and the reflectance. [FIG. 4] It is a schematic diagram showing the configuration of the image projection apparatus 110 according to the second embodiment. [FIG. 5] It is a schematic diagram showing the configuration of the image projection apparatus 120 according to the third embodiment. [FIG. 6] It is a schematic diagram showing a method of presenting information using the conventionally proposed HUD device 1. Fig. 6(a) shows the arrangement of devices inside the vehicle, Fig. 6(b) shows the instrument images 2a displayed on the meter unit 2, and Fig. 6(c) shows the auxiliary image 3a projected as the virtual image 3.

Mode for Carrying Out the Invention

[0019] (First Embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and repeated explanations will be omitted as appropriate. Fig. 1 is a schematic diagram showing the configuration of the image projection apparatus 100 according to the present embodiment. As shown in Fig. 1, the image projection apparatus 100 includes an image irradiation unit 10, an optical branching unit 20, a reflecting mirror 31, a free-form surface mirror 32, a free-form surface mirror 33, a direct display unit 40, and an external light cut filter 50, and projects a virtual image 70 through a windshield (display unit) 60. Further, the image projection apparatus 100 includes a control unit that is communicably connected to each unit and controls each unit (not shown). The configuration of the control unit is not limited, but examples include a CPU (Central Processing Unit) for performing information processing, a memory device, a recording medium, an information communication device, and the like. The control unit controls the operation of each unit according to a predetermined program and sends information (image information) including an image to the image irradiation unit 10.

[0020] The image irradiation unit 10 is a part that irradiates light including an image based on the image information from the control unit. The specific configuration of the image irradiation unit 10 is not limited, and for example, a conventionally known one such as a liquid crystal display device, an organic EL display device, a combination of a laser light source and an optical modulation element, etc. can be used. In the example shown in FIG. 1, a device that irradiates light from the back side of a liquid crystal display device with a light emitting diode (LED: Light Emitting Diode) is used. As will be described later, the image irradiation unit 10 is configured to include a first region 11 and a second region 12 that respectively display a first image and a second image.

[0021] The optical branching unit 20 is an optical member that branches the light of the image irradiated from the image irradiation unit 10, and branches at least the first image displayed in the first region 11 as first image light and the second image displayed in the second region 12 as second image light. The structure of the optical branching unit 20 is not limited as long as it is an optical member that branches light. A prism may be used, or a method such as making the incident angle and reflection angle of light different with a reflecting mirror may be used. In the example shown in FIG. 1, a prism is used as the optical branching unit 20, and the prism is arranged overlapping the second region of the image irradiation unit 10. Therefore, the first image light irradiated from the first region 11 reaches the reflecting mirror 31, and the second image light irradiated from the second region 12 reaches the free-form surface mirror 33 through a path different from that of the first image light by the optical branching unit 20.

[0022] Here, arranging the optical branching unit 20 overlapping the image irradiation unit 10 means that in a plan view, the region where the optical branching unit 20 is arranged overlaps the image display region of the image irradiation unit 10. Also, both the case where the optical branching unit 20 and the image irradiation unit 10 are in contact and the case where they are not in contact are included in the overlapping arrangement. Further, even when an optical member that transmits light is interposed between the optical branching unit 20 and the image irradiation unit 10, or a holding member for maintaining the distance between the two is interposed, it is included in the overlapping arrangement.

[0023] The reflecting mirror 31 is an optical member onto which the first image light irradiated from the image irradiation unit 10 is incident and which reflects the first image light in the direction of the free-form surface mirror 32. In the example shown in FIG. 1, a flat mirror is shown as the reflecting mirror 31, but an optically designed one necessary for projecting the first image light as a virtual image 70 can be used, and a concave mirror, a convex mirror, a free-form surface mirror, etc. can be used as necessary. Further, the reflecting mirror 31 may be omitted, and the first image light from the image irradiation unit 10 may be directly incident on the free-form surface mirror 32.

[0024] The free-form surface mirror 32 is a concave mirror onto which the first image light reflected by the reflecting mirror 31 is incident and which reflects the first image light in the direction of the windshield 60. The reflecting surface of the free-form surface mirror 32 is designed such that the optical path diameter expands in the direction of the driver's viewpoint in order to project it as a virtual image 70 through the windshield 60. Here, the optical path diameter expanding in the direction of the viewpoint includes not only the case where the optical path diameter continuously expands after reflection, but also the case where the optical path diameter contracts and forms an image at an intermediate point and then expands.

[0025] The free-form surface mirror 33 is an optical member onto which the second image light is incident via the optical branching unit 20 and which reflects the second image light directly in the direction of the direct display unit 40. The free-form surface mirror 33 can display the second image on the direct display unit 40 with an area larger than the area of the second region on the image irradiation unit 10 by constituting an enlarging optical unit that causes the reflected second image light to reach the direct display unit 40 while expanding the optical path diameter.

[0026] The direct display unit 40 is an optical member into which the second image light reflected by the free-form surface mirror 33 is incident, and which allows the driver to directly view the second image light. The configuration of the direct display unit 40 is not limited as long as the driver can view the second image light that has reached the direct display unit 40, and a plate-shaped glass that transmits visible light, a retardation film, a transmissive screen, etc. can be used. When a transmissive screen is used as the direct display unit 40, since the second image light irradiated on the back surface is diffused by the transmissive screen, the visibility can be improved even when viewed through polarized glasses or from an oblique direction. When a retardation film is used as the direct display unit 40, it is preferable to make the polarization plane of the second image light different from the fast axis of the retardation film by a predetermined angle (typically 45 degrees). By making the fast axis different from the polarization plane, the second image light is converted into circularly polarized light and travels in the viewing direction, so that the visibility can be improved even when the driver uses polarized glasses.

[0027] The external light cut-off filter 50 is an optical member having a wavelength characteristic of blocking infrared light and / or ultraviolet light and transmitting visible light, and is disposed on the path of the first image light between the image irradiation unit 10 and the windshield 60. In FIG. 1, an example is shown in which the external light cut-off filter 50 is disposed between the windshield 60 and the free-form surface mirror 32, but the placement location is not limited as long as the external light incident on the image irradiation unit 10 can be cut off. By disposing the external light cut-off filter 50, the infrared light and / or ultraviolet light contained in the external light such as sunlight incident from above the windshield 60 is blocked. Thereby, it is possible to suppress the temperature rise and the deterioration of the display surface when sunlight reaches the image display area of the image irradiation unit 10 through the free-form surface mirror 32 and the reflecting mirror 31. Further, since the external light cut-off filter 50 transmits visible light, the first image light transmits well through the external light cut-off filter 50 and does not affect the projection of the virtual image 70.

[0028] The windshield 60 is a member provided in front of the driver's seat of the vehicle and transmits visible light. The windshield 60 corresponds to the display unit in the present invention because, on the inner surface of the vehicle, it reflects the first image light incident from the free-form mirror 32 in the direction of the viewing point and transmits the light from the outside of the vehicle in the direction of the viewing point. Here, an example using the windshield 60 as the display unit is shown. However, a combiner may be prepared as the display unit separately from the windshield 60, and the light from the free-form mirror 32 may be reflected in the direction of the viewing point. Further, it is not limited to being located in front of the vehicle, and it may be arranged on the side or rear as long as it projects an image with respect to the viewing point of the passenger.

[0029] The virtual image 70 is an image that is displayed as if it is formed in space when the first image light reflected by the windshield 60 reaches the viewing point (eyebox) of the driver or the like. The position where the virtual image 70 is formed is determined by the spreading angle when the light irradiated from the image irradiation unit 10 travels in the direction of the viewing point after being reflected by the reflecting mirror 31, the free-form mirror 32, and the windshield 60.

[0030] In the example shown in FIG. 1, the combination of the reflecting mirror 31, the free-form mirror 32, and the external light cut filter 50 constitutes the first optical unit in the present invention, and the first image light is irradiated in the direction of the viewing point as a projection image through the windshield (display unit) 60. Further, the combination of the optical branching unit 20, the free-form mirror 33, and the direct display unit 40 constitutes the second optical unit in the present invention, and the second image light is irradiated in the direction of the viewing point without passing through the windshield (display unit) 60. Convex lenses or concave lenses may be arranged in the first optical unit or the second optical unit as necessary to enlarge or reduce the optical path.

[0031] Figure 2 is a schematic diagram showing the image irradiated from the image irradiation unit 10. In the entire area where the image of the image irradiation unit 10 is displayed, a first image is displayed in the first area 11, and a second image is displayed in the second area 12. In the example shown in FIG. 2, as the first image displayed in the first area 11, auxiliary information related to driving such as speed and volume indicator, and travel direction guide is presented. Further, as the second image displayed in the second area 12, instruments such as a speedometer, a car navigation screen, and driving mode information are presented.

[0032] In the image projection apparatus 100 shown in FIG. 1, a prism which is the optical branching unit 20 is disposed at a position overlapping the second area 12, and the paths of the first image light from the first area 11 and the second image light from the second area 12 are branched. The first image displayed in the first area 11 reaches the driver's viewpoint via the reflecting mirror 31, the free-form surface mirror 32, the external light cut filter 50, and the windshield 60. As described above, since the first image light travels with the optical path expanding in the viewpoint direction, the driver visually recognizes that the virtual image 70 is displayed as a projected image farther than the windshield 60. Further, the second image displayed in the second area 12 reaches the driver's viewpoint via the optical branching unit 20, the free-form surface mirror 33, and the direct display unit 40. Thereby, the driver visually recognizes that the second image is displayed on the direct display unit 40.

[0033] Figure 3 is a graph showing the relationship between the incident angle of light on the windshield 60 and the reflectance. The horizontal axis of FIG. 3 indicates the incident angle of light on the windshield 60, and the vertical axis indicates the relative reflectance when the incident angle of 90 degrees is 100%. The solid line and the broken line in the figure respectively indicate the theoretical values of P-polarized light and S-polarized light, and the plotted white circles and black circles respectively indicate the measured values of P-polarized light and S-polarized light. As shown in FIG. 3, since the reflectance of P-polarized light significantly decreases in the vicinity of the incident angle of 60 degrees on the windshield 60, it is preferable to dispose the free-form surface mirror 32 at a position where the incident angle is 55 degrees or less or 65 degrees or more.

[0034] When the free-form mirror 32 is arranged so that the incident angle of the first image light on the windshield 60 is 55 degrees or less or 65 degrees or more, as shown in FIG. 3, the ratio of P-polarized light contained in the reflected light increases. Thus, even when the driver uses polarized glasses and S-polarized light is cut by the polarized glasses, the virtual image 70 projected by the first image light can be visually recognized.

[0035] As described above, in the image projection device of the present invention, the image irradiated from the image irradiation unit 10 is branched into first image light and second image light by the optical branching unit 20. The first image light is irradiated through the windshield 60 by the first optical unit, and the second image light is irradiated without passing through the windshield 60 by the second optical unit. Thereby, the first image and the second image can be displayed by one image irradiation unit 10, and space saving and improvement of the design freedom can be achieved. Further, while projecting the virtual image 70 with the first image light, since the second image light is directly displayed, it is possible to display the instruments with the second image light and project the auxiliary image as a projection image (virtual image) with the first image light, while achieving space saving and improvement of the design freedom.

[0036] In addition, by using a prism as the optical branching unit 20, the optical design becomes easy when partially covering the image irradiation unit 10 and branching a part of the light. Further, compared with the case of branching light using a reflecting mirror, by using a prism as the optical branching unit 20, the volume secured for branching light can be reduced, and the size of the device can be reduced. In particular, when the optical branching unit 20 is arranged to overlap the second region 12, since the area ratio of the second region 12 to the image irradiation unit 10 is larger than that of the first region 11, it is more advantageous to reduce the size using a prism than using a reflecting mirror. Also, although chromatic aberration occurs when using a lens or a prism, the chromatic aberration of the prism has high regularity with the angle as a parameter, and aberration correction becomes easy by performing color correction in advance by image processing.

[0037] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 4. Descriptions of the content overlapping with the first embodiment will be omitted. FIG. 4 is a schematic diagram showing the configuration of an image projection device 110 according to the present embodiment. This embodiment is different from the first embodiment in that the optical branching unit 20 is included in the first optical unit.

[0038] As shown in FIG. 4, the image projection device 110 includes an image irradiation unit 10, an optical branching unit 20, a reflecting mirror 31, a free-form surface mirror 32, a free-form surface mirror 33, and a direct display unit 40, and projects a virtual image 70 through a windshield (display unit) 60. In this embodiment, the optical branching unit 20 is disposed between the image irradiation unit 10 and the reflecting mirror 31, the optical branching unit 20 is configured by a prism, and an infrared light absorbing material is further contained in the material constituting the prism.

[0039] In the example shown in FIG. 4, the combination of the optical branching unit 20, the reflecting mirror 31, and the free-form surface mirror 32 constitutes the first optical unit in the present invention, and irradiates the first image light as a projection image in the viewpoint direction through the windshield (display unit) 60. Further, the combination of the free-form surface mirror 33 and the direct display unit 40 constitutes the second optical unit in the present invention, and irradiates the second image light in the viewpoint direction without passing through the windshield (display unit) 60.

[0040] In the image projection device 110 shown in FIG. 4, a prism that is the optical branching unit 20 is disposed at a position overlapping the first region 11, and the paths of the first image light from the first region 11 and the second image light from the second region 12 are branched. The first image displayed in the first region 11 reaches the driver's viewpoint through the optical branching unit 20, the reflecting mirror 31, the free-form surface mirror 32, and the windshield 60. As described above, since the first image light travels with an enlarged optical path in the viewpoint direction, the driver visually recognizes that the virtual image 70 is displayed as a projection image farther than the windshield 60. Further, the second image displayed in the second region 12 reaches the driver's viewpoint through the free-form surface mirror 33 and the direct display unit 40. Thereby, the driver visually recognizes that the second image is displayed on the direct display unit 40.

[0041] The prism constituting the optical branching unit 20 is made of a resin or glass that transmits visible light and has a high refractive index, and an infrared light absorbing material that absorbs infrared light is contained in the base material. Further, the optical branching unit 20 may contain an ultraviolet light absorbing material. Thereby, in the optical branching unit 20 disposed between the image irradiation unit 10 and the windshield 60, infrared light and / or ultraviolet light contained in external light such as sunlight incident from above the windshield 60 can be blocked, and the temperature rise of the image irradiation unit 10 can be suppressed.

[0042] Also in the image projection apparatus 110 of the present embodiment, the image irradiated from the image irradiation unit 10 is branched into first image light and second image light by the optical branching unit 20, the first image light is irradiated through the windshield 60 by the first optical unit, and the second image light is irradiated without passing through the windshield 60 by the second optical unit. Thereby, while displaying the instruments with the second image light and projecting the auxiliary image as a projected image (virtual image) with the first image light, it is possible to save space and improve the design freedom.

[0043] (Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. 5. Description of the content overlapping with the first embodiment will be omitted. FIG. 5 is a schematic diagram showing the configuration of an image projection apparatus 120 according to the present embodiment. This embodiment is different from the first embodiment in that it includes a plurality of optical branching units 20.

[0044] As shown in FIG. 5, the image projection apparatus 120 includes an image irradiation unit 10, optical branching units 20a and 20b, a reflecting mirror 31, a free-form surface mirror 32, a free-form surface mirror 33, a reflecting mirror 34, a free-form surface mirror 35, a direct display unit 40, and an external light cut filter 50, and projects virtual images 70a and 70b through a windshield (display unit) 60. In the present embodiment, in the display area of the image irradiation unit 10, a first image is displayed in the first area 11, a second image is displayed in the second area 12, and a third image is displayed in the third area.

[0045] The optical splitters 20a and 20b are optical members that split the light of the image irradiated from the image irradiation unit 10. In the example shown in FIG. 5, prisms are used as the optical splitters 20a and 20b, and the prisms are arranged so as to overlap the second region 12 and the third region of the image irradiation unit 10, respectively. The reflecting mirror 34 is an optical member on which the third image light irradiated from the image irradiation unit 10 is incident and which reflects the third image light in the direction of the free-form surface mirror 35. The free-form surface mirror 35 is a concave mirror on which the third image light reflected by the reflecting mirror 34 is incident and which reflects the third image light in the direction of the windshield 60. The reflecting surface of the free-form surface mirror 35 is designed such that the optical path diameter expands in the direction of the driver's viewpoint in order to project it as a virtual image 70b through the windshield 60.

[0046] In the example shown in FIG. 5, the combination of the reflecting mirror 31, the free-form surface mirror 32, and the external light cut filter 50 constitutes the first optical unit in the present invention, and the first image light is irradiated in the viewpoint direction as a projected image through the windshield (display unit) 60. Further, the combination of the optical splitter 20a, the free-form surface mirror 33, and the direct display unit 40 constitutes the second optical unit in the present invention, and the second image light is irradiated in the viewpoint direction without passing through the windshield (display unit) 60. Further, the combination of the optical splitter 20b, the reflecting mirror 31, the free-form surface mirror 32, and the external light cut filter 50 constitutes the third optical unit in the present invention, and the third image light is irradiated in the viewpoint direction as a projected image through the windshield (display unit) 60. Here, an example in which the free-form surface mirror 32 and the free-form surface mirror 35 are configured separately is shown, but a free-form surface mirror in which the two free-form surfaces are integrally formed may be used.

[0047] In the image projection device 120 shown in FIG. 5, prisms which are optical branching portions 20a and 20b are respectively disposed at positions overlapping the second region 12 and the third region, and the paths of the first image light from the first region 11, the second image light from the second region 12, and the third image light from the third region are branched. The first image displayed in the first region 11 reaches the driver's viewpoint via the reflecting mirror 31, the free-form surface mirror 32, the external light cut filter 50, and the windshield 60. Also, the second image displayed in the second region 12 reaches the driver's viewpoint via the optical branching portion 20a, the free-form surface mirror 33, and the direct display portion 40. As a result, the driver visually recognizes that the second image is displayed on the direct display portion 40. Further, the third image displayed in the third region reaches the driver's viewpoint via the optical branching portion 20b, the reflecting mirror 34, the free-form surface mirror 35, the external light cut filter 50, and the windshield 60. As described above, since the first image light and the third image light progress with the optical path diameter expanding in the viewpoint direction, the driver visually recognizes that virtual images 70a and 70b are displayed as projection images farther than the windshield 60.

[0048] Also in the image projection device 120 of the present embodiment, the image irradiated from the image irradiation unit 10 is branched into the first image light, the second image light, and the third image light by the optical branching portions 20a and 20b, the first image light and the third image light are irradiated via the windshield 60 by the first optical unit and the third optical unit respectively, and the second image light is irradiated by the second optical unit without passing through the windshield 60. Thereby, while displaying the instruments with the second image light and projecting the auxiliary image as a projection image (virtual image) with the first image light and the third image light, it is possible to achieve space saving and an improvement in the degree of design freedom.

[0049] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means respectively disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0050] 100, 110, 120... Image projection device 10... Image irradiation unit 11…First region 12…Second region 20, 20a, 20b…Optical branching unit 31, 34…Mirror 32, 33, 35…Free-form mirror 40…Direct display unit 50…External light cut filter 60…Windshield 70, 70a, 70b…Virtual image

Claims

1. An image projection device that irradiates a projection image onto a display unit for displaying a virtual image, comprising: an image irradiation unit that irradiates an image; an optical branching unit that branches the light for irradiating the image into at least first image light and second image light; a first optical unit that irradiates the first image light as the projection image in the viewpoint direction through the display unit; a second optical unit that irradiates the second image light in the viewpoint direction without passing through the display unit, wherein the optical branching unit includes a prism disposed on a path of a part of the light irradiated from the image irradiation unit, and the prism constitutes a part of the first optical unit and contains an infrared light absorbing material in a base material. The image projection device is characterized by this.

2. An image projection device that irradiates a projection image onto a display unit for displaying a virtual image, comprising: an image irradiation unit that irradiates an image; an optical branching unit that branches the light for irradiating the image into at least first image light and second image light; a first optical unit that irradiates the first image light as the projection image in the viewpoint direction through the display unit; a second optical unit that irradiates the second image light in the viewpoint direction without passing through the display unit, wherein the second optical unit includes a retardation film that converts the second image light into circularly polarized light. The image projection device is characterized by this.

3. The image projection device according to Claim 1 or 2, characterized in that another prism is included in a part of the second optical unit.

4. The image projection device according to any one of Claims 1 to 3, characterized in that the second optical unit includes a transmissive screen on the back surface of which the second image light is irradiated.

5. The image projection device according to any one of Claims 1 to 4, characterized in that the second optical unit includes a magnifying optical unit that magnifies and irradiates the second image light.

Images