Image projection device

Abstract

The present invention provides an image projection device that can suppress the temperature rise of the image illumination area due to ambient light, even when ambient light is incident at an angle close to the optical path of the image light. [Solution] An image projection device (100) for projecting a projected image onto a display unit for displaying a virtual image, comprising an image illumination unit (10) for irradiating image light, projection optical units (20, 30) for irradiating image light in the direction of the viewpoint via the display unit, and light-shielding shade units (70, 80) provided along the optical path of the image light, wherein the light-shielding shade units (70, 80) are provided with a plurality of light-scattering protrusions (71, 81) for scattering light.

Description

Technical Field

[0001] The present invention relates to an image projection device.

Background Art

[0002] Conventionally, as a device for displaying various information inside a vehicle, an instrument panel that lights up icons has been used. Also, along with an increase in the amount of information to be displayed, proposals have been made 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 front glass (windshield) of the vehicle, in order for passengers such as 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, an image projection device such as a head-up display (hereinafter referred to as HUD: Head Up Display) that projects an image onto the front glass so that information can be read when the passenger visually recognizes the front of the vehicle has been proposed. (For example, refer to Patent Documents 1 and 2).

[0004] A conventional image projection device irradiates irradiation light including an image from an image irradiation unit, reflects the irradiation light with a free-form surface mirror or the like, and causes an image to be formed in space through a display unit such as a windshield so as to reach the position of the passenger's viewpoint. Thereby, the passenger can recognize that an image is displayed at the imaging position in the depth direction by the irradiation light incident on the viewpoint.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Conventional HUD devices like this one project an image onto a windshield, which is the display unit. Therefore, they are equipped with a projection optical system that emits light from below the windshield upwards. Consequently, if ambient light, such as sunlight, enters from above the windshield, it reaches the image projection unit via the projection optical system. This ambient light reaching the image projection unit is concentrated by the optical power of the projection system, leading to degradation due to temperature increases.

[0007] To suppress the temperature rise of the image illumination unit due to such ambient light, it has been proposed to install a light-shielding member in the housing of the HUD device to cut off ambient light reaching the image illumination unit from paths other than the optical path of the projection light. However, since the light-shielding member is positioned along the optical path of the image light, if ambient light is incident at an angle close to the optical path of the image light projected by the projection optics unit, there is a possibility that ambient light reflected by the light-shielding member will reach the image illumination unit, making it difficult to suppress the temperature rise.

[0008] Therefore, the present invention has been made in view of the above-mentioned conventional problems, and aims to provide an image projection device that can suppress the temperature rise of the image irradiation area due to ambient light even when ambient light is incident at an angle close to the optical path of the image light. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides an image projection device for projecting a projection image onto a display unit for displaying a virtual image, comprising: an image illumination unit for irradiating image light; a projection optical unit for irradiating the image light in the viewpoint direction via the display unit; and a light-shielding shade unit provided along the optical path of the image light, wherein the light-shielding shade unit is provided with a plurality of light-scattering protrusions for scattering light.

[0010] In the image projection apparatus of the present invention, a light-shielding shade is provided along the optical path of the image light, and a plurality of light-scattering protrusions are provided on the light-shielding shade to scatter light. This makes it possible to suppress the temperature rise of the image illumination area due to ambient light even when ambient light is incident at an angle close to the optical path of the image light.

[0011] Furthermore, in one aspect of the present invention, the light scattering projection has at least its upper surface configured as a curved surface.

[0012] Furthermore, in one aspect of the present invention, the light scattering protrusion is composed of at least a spherical or ellipsoidal surface.

[0013] Furthermore, in one aspect of the present invention, the light scattering protrusion has a maximum diameter in the range of 1 μm to 2 mm.

[0014] Furthermore, in one aspect of the present invention, there is a housing that accommodates the image irradiation unit, the projection optical unit, and the light-shielding shade unit, and a plurality of light-scattering protrusions are also provided on a part of the housing. [Effects of the Invention]

[0015] The present invention provides an image projection device that can suppress the temperature rise of the image illumination area due to ambient light, even when ambient light is incident at an angle close to the optical path of the image light. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram showing the projection of a virtual image P using the image projection device 100 according to the first embodiment. [Figure 2] This is a schematic cross-sectional view illustrating the outline of the image projection device 100 according to the first embodiment. [Figure 3] Figure 3(a) is a schematic diagram illustrating the arrangement of light scattering protrusions 71 and the scattering of ambient light. Figure 3(b) is a schematic diagram illustrating the scattering of ambient light by curved light scattering protrusions 71. [Figure 4]It is a schematic cross-sectional view for explaining the outline of the image projection apparatus 100 according to the second embodiment. [Figure 5] It is a schematic cross-sectional view for explaining the outline of the image projection apparatus 100 according to the third embodiment. [Figure 6] It is a schematic plan view for explaining a modification example of the arrangement of the light scattering protrusions 71.

MODE FOR CARRYING OUT THE INVENTION

[0017] (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 redundant explanations will be omitted as appropriate. In the following description, a form in which the image projection apparatus 100 according to the present invention is applied to a HUD mounted on a vehicle or the like will be exemplified and described.

[0018] FIG. 1 is a schematic diagram showing the projection of a virtual image P using the image projection apparatus 100 according to the present embodiment. As shown in FIG. 1, the image light projected from the image projection apparatus 100 is reflected by the windshield WS and irradiated to the driver's viewpoint position E (instrument cluster). The driver visually recognizes a virtual image P formed at a predetermined distance (first distance) from the viewpoint position E on the extension line of the image light that has reached the viewpoint position E. The dashed line from the viewpoint position E to the virtual image P shown in FIG. 1 indicates the path of the center position of the image light, and the solid line arrow from the image projection apparatus 100 to the windshield WS indicates the range where the image light is irradiated.

[0019] The windshield WS is provided in front of the driver's seat of the vehicle and is a part that transmits visible light. The windshield WS reflects the image light incident from the image projection device 100 on the inner surface of the vehicle with respect to the viewpoint position E and transmits the light from the outside of the vehicle in the direction of the viewpoint position E, corresponding to the display unit in the present invention. Here, an example using the windshield WS as the display unit is shown, but a combiner may be prepared as the display unit separately from the windshield WS, and the light from the image projection device 100 may be reflected in the viewpoint direction. 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 viewpoint of the passenger.

[0020] The virtual image P is an image that is displayed as if it is formed in space when the image light reflected by the windshield WS reaches the viewpoint position E of the passenger. The position where the virtual image P is formed is determined by the combined focal length of the projection optical unit included in the image projection device 100 and the windshield WS. Examples of the content of the image projected as the virtual image P include auxiliary information related to driving such as an image for attracting attention and emergency information, speed, volume indicator, and travel direction guide.

[0021] FIG. 2 is a schematic cross-sectional view for explaining the outline of the image projection device 100 according to the present embodiment. As shown in FIG. 2, the image projection device 100 includes an image irradiation unit 10, a first mirror 20, a second mirror 30, a lower housing 40, an upper housing 50, a dust-proof cover 60, and light-shielding shade parts 70, 80. Further, a plurality of light-scattering protrusions 71, 81 are formed on the light-shielding shade parts 70, 80, respectively. Here, the combination of the first mirror 20 and the second mirror 30 corresponds to the projection optical unit in the present invention. The solid arrows in FIG. 2 schematically show the optical paths at the end positions of the image light.

[0022] In the image projection device 100, each part is controlled by a control unit that is connected to each part for information communication. The configuration of the control unit is not limited, but one example is one that includes a CPU (Central Processing Unit) for information processing, a memory device, a recording medium, an information communication device, etc. The control unit controls the operation of each part according to a predetermined program and sends information including images (image information) to the image projection unit 10.

[0023] The image illumination unit 10 is the part that, based on image information from the control unit, illuminates the windshield WS with image light containing an image, and illuminates the windshield WS with the image light via the first mirror 20 and the second mirror 30. The specific configuration of the image illumination unit 10 is not limited, and as an example, a structure in which an image is displayed on a liquid crystal display device and illumination light is emitted from the light source unit can be used.

[0024] The first mirror 20 is an optical element that reflects the image light arriving from the image illumination unit 10 toward the second mirror 30. In the example shown in Figure 2, the first mirror 20 is shown as a concave reflector, but a planar or convex reflector may also be used. Furthermore, when the first mirror 20 is made of a curved surface, it is not limited to a surface with a constant curvature, and a paraboloid of revolution, an ellipsoid, a free-form mirror, etc., can be used. In the example shown in Figure 2, the angle of the first mirror 20 relative to the image illumination unit 10 is fixed.

[0025] The second mirror 30 is an optical element that reflects the image light arriving from the first mirror 20 in the direction of the windshield WS. In the example shown in Figure 2, the second mirror 30 is a free-form mirror with a concave shape optically designed to project the image light as a virtual image P. In the example shown in Figure 2, the angle of the second mirror 30 relative to the windshield WS is variable.

[0026] The reflective surfaces of the first mirror 20 and the second mirror 30 are designed so that the optical diameter expands in the direction of the driver's viewpoint position E in order to project the image light as a virtual image P through the windshield WS. Here, expansion of the optical diameter in the viewpoint direction includes not only cases where the optical diameter consistently expands after reflection, but also cases where the optical diameter contracts, forms an image at an intermediate point, and then expands.

[0027] The projection optics unit, composed of a combination of a first mirror 20 and a second mirror 30, functions as an optical element that projects image light emitted from the image illumination unit 10 onto the driver's viewpoint position E via the windshield WS, and images the image light at a first distance from the viewpoint position E.

[0028] In Figure 2, the optical path at the end of the image light is depicted as a straight line. The image light is displayed in a predetermined area in the image illumination unit 10, and has a predetermined area in the direction perpendicular to the direction of propagation. The image light is reflected by the first mirror 20, and its optical diameter is reduced as it propagates, and intermediate imaging may occur at an intermediate imaging position F (not shown) between the first mirror 20 and the second mirror 30. In Figure 2, an example is shown in which the image light reflected by the first mirror 20 is intermediately imaged at the intermediate imaging position F before reaching the second mirror 30, but the image light may reach the second mirror 30 without intermediate imaging.

[0029] The lower housing 40 constitutes the outer shape of the image projection device 100 and is a housing that accommodates the other parts inside. The upper housing 50 is a housing that is positioned on top of the lower housing 40 so as to cover the parts housed inside the lower housing 40. An opening is provided in a part of the upper housing 50, and a dust cover 60 is provided in this opening to seal the interior. The materials that make up the lower housing 40 and the upper housing 50 are not limited, and light-blocking resin materials or metal materials can be used. The upper housing 50 is fixed to the lower housing 40 in a structure that does not create a gap between the two, preventing dust and dirt from entering the housing formed by the lower housing 40 and the upper housing 50. Furthermore, the structure and shape of the lower housing 40 and the upper housing 50 are not limited to those shown in Figure 2.

[0030] The dust cover 60 is made of a material that transmits image light and is positioned to cover the opening of the upper housing 50. Although not shown in Figure 2, the dust cover 60 is fixed to the upper housing 50 in a way that prevents any gaps from forming between them, thus preventing dust and dirt from entering the upper housing 50. The material that makes up the dust cover 60 is not limited, and known resin materials or glass that transmit image light can be used.

[0031] The light-shielding shade portion 70 is a part of a component housed within the lower housing 40 that extends along the optical path of the image light, and is made of a light-shielding material. The component to which the light-shielding shade portion 70 is provided is not limited, but for example, the light-shielding shade portion 70 may be formed by extending a part of the retaining member that holds the second mirror 30. Figure 2 shows an example in which the light-shielding shade portion 70 is formed integrally with the retaining member, but the light-shielding shade portion 70 may also be formed separately and attached. Figure 2 shows an example in which the light-shielding shade portion 70 is extended along the optical path of the image light that has been folded back by the first mirror 20, but the shape and structure of the light-shielding shade portion 70 are not limited as long as the shape and length do not obstruct the optical path of the image light.

[0032] The light-shielding shade portion 80 is a part of the upper housing 50 that extends inward along the optical path of the image light. Because the light-shielding shade portion 80 is provided facing inward towards the upper housing 50, even if external light such as sunlight reaches the inside of the image projection device 100 from outside the image projection device 100 through the dust cover 60, a portion of it can be blocked by the light-shielding shade portion 80. In Figure 2, an example is shown in which the light-shielding shade portion 80 is formed integrally with the upper housing 50, but it may also be constructed as a separate component and fixed to the inner wall of the upper housing 50. Also, in Figure 2, an example is shown in which the light-shielding shade portion 80 is provided on the outer edge of the dust cover 60, but it may also be provided at a position away from the dust cover 60. Also, in Figure 2, the light-shielding shade portion 80 is shown as a substantially flat plate shape, but the shape is not limited, and multiple portions may be provided. Furthermore, the light-shielding shade portion 80 may not be provided, in which case a part of the upper housing 50 functions as the light-shielding shade portion 80.

[0033] The light-scattering protrusions 71 and 81 are minute protrusions provided on the surface of the light-shielding shade portions 70 and 80, respectively. Preferably, the light-scattering protrusions 71 and 81 are made of a material that not only scatters light but also absorbs at least a portion of it, and it is preferable to use a black or dark-colored resin material. The light-scattering protrusions 71 and 81 may be formed integrally with the light-shielding shade portions 70 and 80, or they may be made separately and attached to the light-shielding shade portions 70 and 80 with an adhesive or the like.

[0034] The positions of the light scattering protrusions 71 and 81 are not limited, but it is preferable to provide them on the entire surface of the light-shielding shades 70 and 80 in order to scatter ambient light and reduce the light density reaching the image illumination unit 10. Furthermore, it is preferable to provide the light scattering protrusions 71 and 81 in areas that are visible from the outside of the dust cover 60. Also, the shape of the light scattering protrusions 71 and 81 is not limited, but it is preferable that at least the upper surface is curved in order to scatter ambient light in various directions rather than reflecting it in one direction.

[0035] Figure 3 is a schematic diagram illustrating the arrangement of light scattering protrusions 71 and the scattering of ambient light. Figure 3(a) is a schematic plan view showing an example where the light scattering protrusions 71 are arranged in a triangular lattice, and Figure 3(b) is a schematic diagram illustrating the scattering of ambient light by curved light scattering protrusions 71. In Figure 3, a portion of the light scattering protrusions 71 provided on the light-shielding shade portion 70 is shown in magnified view, but the same applies to the light scattering protrusions 81 provided on the light-shielding shade portion 80.

[0036] Figure 3(a) shows an example in which curved light-scattering protrusions 71 of the same size are arranged periodically at predetermined intervals. However, the size of each light-scattering protrusion 71 may differ, they may be arranged non-periodically, and their arrangement is not limited. In the example shown in Figure 3(a), adjacent light-scattering protrusions 71 are spaced apart, but adjacent light-scattering protrusions 71 may be in contact with each other. Also, in Figure 3(a), an example is shown in which a part of the flat light-shielding shade portion 70 is exposed between the light-scattering protrusions 71. However, the light-scattering protrusions 71 may be densely arranged so that there are no flat portions.

[0037] Figure 3(b) schematically shows the case where ambient light is incident on a single light-scattering protrusion 71 at an oblique angle, but ambient light is similarly scattered on each of the multiple light-scattering protrusions 71 provided. As shown in Figure 3(b), it is preferable that a single light-scattering protrusion 71 has a curved shape with a width W and a height H. The curvature and curved shape of the light-scattering protrusion 71 are not limited, and a sphere, a spheroid, a part of a parabolic surface, etc., can be used. Furthermore, it is preferable that all of the light-scattering protrusions 71 are curved, but they may include some flat surfaces, inclined surfaces, vertical surfaces, etc. As shown by the white arrows in the figure, when ambient light is incident on the light-shielding shade section 70 at an oblique angle, if it is a flat surface without light-scattering protrusions 71, some of the ambient light will be specularly reflected. However, as shown in Figure 3(b), in the image projection device 100 of this embodiment, multiple light-scattering protrusions 71 are provided on the light-shielding shade section 70, so the ambient light is scattered in various directions by the curved surfaces of the light-scattering protrusions 71. In this process, the density of ambient light scattered in each direction decreases.

[0038] As described above, the presence of multiple light-scattering protrusions 71 and 81 on the light-shielding shades 70 and 80 causes ambient light incident on the light-shielding shades 70 and 80 to be scattered. This reduces the light density reaching the image illumination unit 10 via the second mirror 30 or the first mirror 20, even when ambient light is incident at an angle close to the optical path of the image light, thereby suppressing the temperature rise of the image illumination unit 10.

[0039] The size of the light scattering protrusions 71 and 81 is not limited, but the maximum diameter of the width W is preferably in the range of 1 μm to 2 mm. If the width W is less than 1 μm, it becomes approximately the same as the wavelength of light, which reduces the light scattering effect and is undesirable. Also, the ambient light scattered by each light scattering protrusion 71 may interfere with each other in the same way as a diffraction grating, which may increase the light intensity in a specific direction and is undesirable. Furthermore, if the width W is greater than 2 mm, the curvature of the individual light scattering protrusions 71 becomes large, which weakens the light scattering effect and approaches specular reflection, and is undesirable.

[0040] As described above, in the image projection device 100 of this embodiment, light-shielding shades 70 and 80 are provided along the optical path of the image light, and multiple light-scattering protrusions 71 and 81 that scatter light are provided on the light-shielding shades 70 and 80. This makes it possible to suppress the temperature rise of the image irradiation unit 10 due to ambient light even when ambient light is incident at an angle close to the optical path of the image light.

[0041] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to Figure 4. Details that overlap with the first embodiment will be omitted. Figure 4 is a schematic cross-sectional view illustrating the outline of the image projection device 100 according to this embodiment. This embodiment differs from the first embodiment in that light scattering protrusions 41, 51, 52, and 53 are also provided on a part of the lower housing 40 or the upper housing 50 that constitute the enclosure.

[0042] Figure 4 is a schematic cross-sectional view illustrating the outline of the image projection device 100 according to this embodiment. As shown in Figure 4, the image projection device 100 includes an image irradiation unit 10, a first mirror 20, a second mirror 30, a lower housing 40, an upper housing 50, a dustproof cover 60, and light-shielding shade units 70 and 80. Light-scattering protrusions 41, 51, 52, and 53 are provided on parts of the inner walls of the lower housing 40 and the upper housing 50. In addition, multiple light-scattering protrusions 71, 72, 81, and 82 are formed on the light-shielding shade units 70 and 80, respectively.

[0043] The light scattering protrusion 41 is a minute protrusion provided on a part of the inner wall of the lower housing 40. The light scattering protrusion 41 may be formed integrally with the inner wall of the lower housing 40, or it may be a separate component attached to the inner wall of the lower housing 40 with an adhesive or the like. The position where the light scattering protrusion 41 is provided is not limited, but it is preferable to provide the protrusion-forming region on the inner wall of the lower housing 40 along the optical path of the image light. In the example shown in Figure 4, the light scattering protrusion 41 is provided along the optical path of the image light between the image irradiation unit 10 and the first mirror 20.

[0044] The light scattering protrusions 51, 52, and 53 are minute protrusions provided on a part of the inner wall of the upper housing 50. The light scattering protrusions 51, 52, and 53 may be formed integrally with the inner wall of the upper housing 50, or they may be constructed separately and attached to the inner wall of the upper housing 50 with an adhesive or the like. The position where the light scattering protrusions 51, 52, and 53 are provided is not limited, but it is preferable to provide the protrusion-forming region on the inner wall of the upper housing 50 along the optical path of the image light. In the example shown in Figure 4, the light scattering protrusion 51 is provided near the reflective surface of the first mirror 20, facing the optical path of the image light between the first mirror 20 and the second mirror 30. The light scattering protrusion 52 is provided near the reflective surface of the first mirror 20, facing the optical path of the image light between the image irradiation unit 10 and the first mirror 20. Furthermore, the light scattering protrusions 53 are provided near the reflective surface of the second mirror 30, facing the optical path of the image light between the second mirror 30 and the dust cover 60.

[0045] The light scattering protrusion 72 is a minute protrusion provided on the surface (back surface) of the light-shielding shade portion 70 that faces the image illumination portion 10. The light scattering protrusion 72 may be formed integrally with the light-shielding shade portion 70, or it may be a separate component attached to the light-shielding shade portion 70 with an adhesive or the like. The position where the light scattering protrusion 72 is provided is not limited, but it is preferable to provide a protrusion-forming region on the back surface of the light-shielding shade portion 70 along the optical path of the image light. In the example shown in Figure 4, the light scattering protrusion 72 is provided at the tip of the light-shielding shade portion 70, facing the optical path of the image light between the image illumination portion 10 and the first mirror 20.

[0046] The light scattering protrusions 82 are minute protrusions provided on the surface (back surface) of the light-shielding shade portion 80 that faces the first mirror 20. The light scattering protrusions 82 may be formed integrally with the light-shielding shade portion 80, or they may be formed separately and attached to the light-shielding shade portion 80 with an adhesive or the like. The position where the light scattering protrusions 82 are provided is not limited, but it is preferable to provide the protrusion-forming region on the back surface of the light-shielding shade portion 80 along the optical path of the image light. In the example shown in Figure 4, the light scattering protrusions 82 are provided over the entire area of ​​the light-shielding shade portion 80, facing the optical path of the image light between the first mirror 20 and the second mirror 30.

[0047] External light entering the image projection device 100 from outside reaches the second mirror 30 from the dust cover 60 at various angles of incidence. Therefore, external light entering the inside of the image projection device 100 may be repeatedly reflected by the inner walls of the lower housing 40 and upper housing 50 that constitute the enclosure, and may reach the image illumination unit 10 from an unintended direction. Accordingly, by providing light scattering protrusions 41, 51, 52, 53, 72, and 82 in positions that are not directly visible from outside the dust cover 60, the external light entering the image illumination unit 10 can be further suppressed, thereby suppressing the temperature rise.

[0048] As described above, in the image projection device 100 of this embodiment, light-shielding shades 70 and 80 are provided along the optical path of the image light, and multiple light-scattering protrusions 71, 72, 81, and 82 that scatter light are provided on the light-shielding shades 70 and 80, so that even when ambient light is incident at an angle close to the optical path of the image light, it is possible to suppress the temperature rise of the image irradiation unit 10 due to ambient light.

[0049] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to Figure 5. Details that overlap with the first embodiment will be omitted. Figure 5 is a schematic cross-sectional view illustrating the outline of the image projection device 100 according to this embodiment. This embodiment differs from the second embodiment in that light scattering protrusions 41, 71, 81, and 82 are provided only in certain areas within the housing. As shown in Figure 5, the light scattering protrusions 41, 71, 81, and 82 are provided only in certain areas on the inner wall of the lower housing 40, the surface of the light-shielding shade portion 70, and the front and back surfaces of the light-shielding shade portion 80, respectively.

[0050] As described above, ambient light entering the image projection device 100 from outside reaches the second mirror 30 from the dust cover 60 at various angles of incidence. However, depending on the position of the image projection device 100 in the vehicle and the internal structure of the image projection device 100, the area on the inner walls of the lower housing 40 and upper housing 50 that constitute the enclosure may be limited to the area to which ambient light can reach. Therefore, even if the light scattering protrusions 41, 71, 81, and 82 are provided only in the area to which ambient light can reach, the ambient light entering the image irradiation unit 10 can be suppressed, thereby suppressing the temperature rise.

[0051] Figure 5 shows an example in which light scattering protrusions 41, 52, 71, 81, and 82 are provided on the inner wall of the upper housing 50 and on the back side of the light-shielding shade portion 70, but light scattering protrusions 51, 53, and 72 may be provided as needed.

[0052] As described above, in the image projection device 100 of this embodiment, light-shielding shades 70 and 80 are provided along the optical path of the image light, and multiple light-scattering protrusions 71, 81, and 82 that scatter light are provided on the light-shielding shades 70 and 80. This makes it possible to suppress the temperature rise of the image irradiation unit 10 due to ambient light even when ambient light is incident at an angle close to the optical path of the image light.

[0053] (modified version) Next, a modified example of the light scattering protrusions 71 will be described using Figure 6. Content that overlaps with the first embodiment will be omitted from the explanation. Figure 6 is a schematic plan view illustrating a modified arrangement of the light scattering protrusions 71. In this modified example, the planar shape of the light scattering protrusions 71 is shown as an ellipse rather than a circle, but it may also be rectangular or polygonal.

[0054] In the example shown in Figure 6(a), the light scattering protrusions 71 have an elliptical shape in plan view and are arranged with their major axes aligned to one side. In the elliptical light scattering protrusions 71, the area of ​​the curved surface is large along the major axis and small along the minor axis. Therefore, when light reaches the light scattering protrusions 71, a large amount of light is reflected in the direction intersecting the major axis, and a small amount of light is reflected in the direction along the major axis. Thus, by constructing the light scattering protrusions 71 with an anisotropic shape and arranging them accordingly, the amount of ambient light scattered by the light scattering protrusions 71 reflected in a specific direction can be suppressed.

[0055] In the example shown in Figure 6(a), the reflection of light in the horizontal direction along the major axis of the ellipse is suppressed, while the amount of light reflected in the vertical direction along the minor axis increases. Therefore, by aligning the major axis of the light scattering protrusion 71 along the optical path of the image light, the amount of ambient light reflected toward the second mirror 30, the first mirror 20, and the image illumination unit 10 can be further suppressed.

[0056] In the example shown in Figure 6(b), the light scattering protrusions 71 have an elliptical shape in plan view, and their major and minor axes are arranged in alternating repeating patterns. As described above, the anisotropic planar shape of the light scattering protrusions 71 allows for a light distribution pattern to be created in the light reflected by each individual light scattering protrusion 71. Therefore, as shown in Figure 6(b), by creating a distribution in the arrangement of the light scattering protrusions 71, the light distribution pattern of the light scattered by multiple light scattering protrusions 71 can be adjusted.

[0057] In the example shown in Figure 6(b), light scattering protrusions 71 with an elliptical shape and their major axes aligned diagonally to the lower right of the figure are arranged in a 50:50 ratio with light scattering protrusions 71 aligned diagonally to the lower left of the figure. As a result, the amount of ambient light scattered by the light scattering protrusions 71 increases in the direction of reflection in the lower right and lower left of the figure, while the amount of light reflected in the vertical and horizontal directions decreases. Therefore, by giving anisotropy to the multiple light scattering protrusions 71 and adjusting the arrangement of the light scattering protrusions 71, the direction in which ambient light is reflected can be adjusted.

[0058] As described above, in the image projection device 100 of this embodiment, a light-shielding shade portion 70 is provided along the optical path of the image light, and a plurality of light-scattering protrusions 71 that scatter light are provided on the light-shielding shade portion 70. This makes it possible to suppress the temperature rise of the image irradiation portion 10 due to ambient light even when ambient light is incident at an angle close to the optical path of the image light.

[0059] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0060] 100…Image projection device 10…Image illumination area 20…First Mirror 30...Second Mirror 40…Lower housing 50… Upper housing 60…Dust cover 70, 80... Light-blocking shade section 41,51,52,53,71,72,81,82...Light scattering protrusion

Claims

1. An image projection device that projects a projected image onto a display unit for displaying a virtual image, An image illumination unit that emits image light, A projection optical unit that illuminates the image light in the viewing direction via the display unit, It comprises a light-shielding shade portion provided along the optical path of the image light, The image projection device is characterized in that the light-shielding shade portion is provided with a plurality of light-scattering protrusions that scatter light.

2. An image projection device according to claim 1, The image projection device is characterized in that the light scattering protrusion has at least its upper surface configured as a curved surface.

3. An image projection device according to claim 2, The image projection device is characterized in that the light scattering protrusions are composed of at least a portion of a spherical or ellipsoidal surface.

4. An image projection device according to claim 1, The image projection device is characterized in that the light scattering protrusion has a maximum diameter in the range of 1 μm to 2 mm.

5. An image projection device according to any one of claims 1 to 4, It has a housing that accommodates the image irradiation unit, the projection optical unit, and the light-shielding shade unit, An image projection device characterized in that a plurality of the light-scattering protrusions are also provided on a part of the housing.

Images