Image projection device

Abstract

The present invention provides an image projection device that simplifies the assembly process of polarizing plates while maintaining high precision in the relative positional relationship of the polarizing plates with respect to the image display unit. [Solution] An image projection device for projecting a projected image onto a display unit for displaying a virtual image, comprising a polarizing member (20) that transmits polarization in a predetermined direction and blocks polarization perpendicular to the predetermined direction, and a holding member (11) that holds the polarizing member (20), wherein the polarizing member (20) is provided with a movement restricting portion (20d) that restricts the movement of the polarizing member (20) in the in-plane direction, and the holding member (11) has a support portion (11c) that restricts the movement of the polarizing member (20) in a direction intersecting the in-plane direction, an elastic deformation portion (11e) that elastically deforms upon interference with the polarizing member (20), and a mating portion (11d) provided on a part of the elastic deformation portion (11e) that mates with the movement restricting portion (20d).

Description

Technical Field

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

Background Art

[0002] Conventionally, as a device for displaying various information in a vehicle, an instrument panel that lights up icons has been used. Also, with the 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) has been proposed that projects an image onto the front glass so that information can be read when the passenger views the front of the vehicle (see, for example, 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.

[0005] In conventional image projection devices, when sunlight or other ambient light enters from the outside, the ambient light is focused onto the surface of the image display unit by a free-form mirror, potentially causing the temperature of the image display unit to rise and degrade. Therefore, it has been proposed to place an ambient light filter in the path of the ambient light to cut out ultraviolet and infrared light contained in the ambient light, thereby reducing the energy of the ambient light reaching the image display unit and suppressing the temperature rise of the image display unit (see, for example, Patent Document 3). It has also been proposed to use a polarizing plate that cuts out a predetermined polarization direction as an ambient light filter. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-119248 [Patent Document 2] Japanese Patent Publication No. 2019-119262 [Patent Document 3] Japanese Patent Publication No. 2023-055057 [Overview of the project] [Problems that the invention aims to solve]

[0007] In conventional image projection devices, some ambient light is reflected off the surface of the polarizing plate, becoming stray light that can reach the viewpoint via the free-form mirror and windshield. Therefore, measures are taken to position the polarizing plate at a predetermined angle relative to the image display unit. However, in conventional image projection devices, ensuring the positioning accuracy required by the optical properties of the polarizing plate presents a challenge, as it complicates the structure and process for fixing the polarizing plate.

[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 simplify the assembly process of the polarizing plate while maintaining high precision in the relative positional relationship of the polarizing plate with respect to the image display unit. [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: a polarizing member that transmits polarization in a predetermined direction and blocks polarization perpendicular to the predetermined direction; and a holding member that holds the polarizing member, wherein the polarizing member is provided with a movement restricting portion that restricts the movement of the polarizing member in the in-plane direction, and the holding member has a support portion that restricts the movement of the polarizing member in a direction intersecting the in-plane direction, an elastic deformation portion that elastically deforms by interfering with the polarizing member, and a mating portion provided on a part of the elastic deformation portion that mates with the movement restricting portion.

[0010] In the image projection apparatus of the present invention, the holding member has a support portion, an elastically deformable portion, and a mating portion. Movement in the in-plane direction is restricted by a movement restricting portion provided on the polarizing member, and movement in a direction intersecting the in-plane direction is restricted by the support portion. This allows for high-precision relative positional relationship of the polarizing plate with respect to the image display unit while simplifying the assembly process of the polarizing plate.

[0011] Furthermore, in one aspect of the present invention, the movement restricting portion is a through hole provided in the plane of the polarizing member, and the mating portion is a projection provided in a shape and position corresponding to the through hole.

[0012] Furthermore, in one aspect of the present invention, the elastically deformable portion is elastically deformed in a direction intersecting the plane.

[0013] Furthermore, in one aspect of the present invention, the movement restricting portion is a notch provided on the side surface of the polarizing member, and the engagement portion is a projection provided in a shape and position corresponding to the notch.

[0014] Furthermore, in one aspect of the present invention, the elastically deformable portion is elastically deformed along the in-plane direction.

[0015] In another aspect of the present invention, the support portion supports the polarizing member so that it can slide in the in-plane direction.

[0016] In one aspect of the present invention, there is provided an image irradiation unit that irradiates image light, and a projection optical unit that forms an image of the image light from a viewpoint position at a first distance via the display unit, and the polarizing member is disposed between the projection optical unit and the image irradiation unit.

Advantages of the Invention

[0017] The present invention can provide an image projection apparatus capable of simplifying the assembling process of a polarizing plate while maintaining the relative positional relationship between the polarizing plate and the image display unit with high accuracy.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram showing the projection of a virtual image P using the image projection apparatus 100 according to the first embodiment. [Figure 2] It is a schematic perspective view for explaining an overview of the image irradiation unit 10 in a state where the polarizing plate 20 is attached. [Figure 3] It is a schematic perspective view for explaining an overview of the image irradiation unit 10 before attaching the polarizing plate 20. [Figure 4] It is a schematic diagram showing the structure of the holding member 11 and the polarizing plate 20. FIG. 4(a) is a schematic plan view seen from a direction perpendicular to the polarizing plate 20, and FIG. 4(b) is a top view seen from the support portion 11c side of the holding member 11. [Figure 5] It is a schematic diagram showing the process of attaching the polarizing plate 20 to the holding member 11. FIG. 5(a) shows a state before attaching the polarizing plate 20, FIG. 5(b) shows a state where the polarizing plate 20 is inserted into the holding member 11 to about half, and FIG. 5(c) shows a state after attaching the polarizing plate 20 to the holding member 11. [Figure 6] It is a schematic diagram showing the structure of the holding member 11 and the polarizing plate 20 in the image irradiation unit 10 according to the second embodiment. FIG. 6(a) is a schematic plan view seen from a direction perpendicular to the polarizing plate 20, and FIG. 6(b) is a top view seen from the support portion 11c side of the holding member 11. [Figure 7] It is a schematic diagram showing the structure of the holding member 11 and the polarizing plate 20 in the image irradiation unit 10 according to the third embodiment.

Best 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 redundant descriptions 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. 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 projection apparatus 100 includes an image irradiation unit 10, a polarizing plate 20, a primary mirror 30, and a secondary mirror 40.

[0020] 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 panel). 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 broken line shown in FIG. 1 schematically represents the light beam of the image light irradiated from the image projection apparatus 100, the optical path of the image light reflected by the windshield WS and reaching the viewpoint position E, and its extension line. The actual image light is displayed in a predetermined area in the image irradiation unit 10 and has a predetermined area in a direction perpendicular to the traveling direction.

[0021] In the image projection apparatus 100, each unit is controlled using a control unit that is connected to each unit so as to be able to communicate information. The configuration of the control unit is not limited, but examples include those provided with 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.

[0022] 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 then illuminates the windshield WS with the image light reflected by the primary mirror 30 and the secondary mirror 40. The specific configuration of the image illumination unit 10 is not limited, and conventionally known devices such as liquid crystal displays and organic EL displays can be used. As an example, a device is used in which the illumination light is emitted from the back side of a liquid crystal display using a light-emitting diode (LED).

[0023] The polarizing plate 20 is an optical component having optical properties that transmit polarized light in the direction of the transmission axis and reflect or absorb polarized light perpendicular to the direction of the transmission axis, and a known polarizing plate or polarizing film can be used. Furthermore, it is preferable that the transmittance in the transmission axis is uniform within the plane of the polarizing plate 20. Here, the direction of the transmission axis of the polarizing plate 20 corresponds to a predetermined direction in the present invention. Furthermore, it is preferable that the transmission axis of the polarizing plate 20 is arranged to transmit P-polarized light to the windshield WS. The polarizing plate 20 corresponds to the polarizing component in the present invention.

[0024] Figure 1 shows an example in which the polarizing plate 20 is constructed as a single plate-shaped member, but it may also be constructed by laminating a polarizing sheet to a translucent substrate such as resin. Furthermore, multiple functions may be realized by laminating sheets that perform other optical functions to the polarizing plate 20, for example, by laminating an infrared light cut filter or an ultraviolet light cut filter. Details of the polarizing plate 20 will be described later.

[0025] The primary mirror 30 is an optical element that receives image light emitted from the image illumination unit 10 and reflects the image light in the direction of the secondary mirror 40. In the example shown in Figure 1, the primary mirror 30 is a free-form mirror optically designed to project the image light as a virtual image P. The secondary mirror 40 is an optical element that receives image light reflected by the primary mirror 30 and reflects the image light in the direction of the windshield WS. In the example shown in Figure 1, the secondary mirror 40 is a free-form mirror optically designed to project the image light as a virtual image P. Furthermore, the secondary mirror 40 may be made capable of changing its tilt angle with respect to the horizontal direction, thereby changing the projection direction of the image light and moving the projection position of the virtual image P in the vertical direction.

[0026] The reflective surfaces of the primary mirror 30 and the secondary mirror 40 are designed so that the optical diameter expands in the direction of the driver's viewpoint in order to project image light as a virtual image P through the windshield WS. Here, expansion of the optical diameter in the direction of the viewpoint 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. The combination of the primary mirror 30 and the secondary mirror 40 has the function of projecting image light through the windshield WS and corresponds to the projection optics unit in the present invention.

[0027] The windshield WS is a visible light-transmitting part located in front of the driver's seat of the vehicle. On the inner surface of the vehicle, the windshield WS reflects the image light incident from the secondary mirror 40 toward the viewpoint direction and transmits light from outside the vehicle toward the viewpoint direction, thus corresponding to the display unit in this invention. Here, an example using the windshield WS as the display unit is shown, but a combiner may be prepared separately as a display unit and reflect the light from the secondary mirror 40 toward the viewpoint direction. Furthermore, it is not limited to being located in front of the vehicle, but may be placed to the side or rear as long as it projects an image toward the occupant's viewpoint.

[0028] The virtual image P is an image that appears to be projected in space when the image light reflected by the windshield WS reaches the driver's or other viewpoint position E (eyebox). The position where the virtual image P is projected is determined by the angle of spread of the light emitted from the image projection unit 10 as it travels in the direction of the viewpoint after being reflected by the primary mirror 30, secondary mirror 40, and windshield WS. The content of the image projected as the virtual image P may include warning images, auxiliary driving information such as emergency information, volume indicators, and direction of travel guides.

[0029] Figure 2 is a schematic perspective view illustrating the outline of the image illumination unit 10 with the polarizing plate 20 attached. Figure 3 is a schematic perspective view illustrating the outline of the image illumination unit 10 before the polarizing plate 20 is attached. As shown in Figures 2 and 3, the image illumination unit 10 comprises a unit housing 10a, a holding member 11, and an image display unit 12. The polarizing plate 20 is inclined at a predetermined angle with respect to the image display unit 12 and is positioned and held by the holding member 11. The image display unit 12 is located at the top of the unit housing 10a and displays an image in a display area 12a, which is a part of the display surface. The display area 12a is located between the holding members 11 and below the polarizing plate 20 held by the holding members 11.

[0030] The unit housing 10a forms the outer shape of the image illumination unit 10 and is a component that holds the image display unit 12 and the polarizing plate 20 at its top, and corresponds to the housing in this invention. The unit housing 10a also houses the light source unit, primary lens and secondary lens, etc., and illuminates the image display unit 12 with light emitted from the light source unit. In addition, a heat dissipation member may be arranged on the back of the unit housing 10a to dissipate the heat generated by the light emission from the light source unit.

[0031] The holding member 11 is provided on the upper part of the unit housing 10a and is the part that positions the polarizing plate 20 by tilting it at a predetermined angle and holds it above the display area 12a. Details of the shape and structure of the holding member 11 will be described later. In the example shown in Figure 3, the holding member 11 inserts the polarizing plate 20 by sliding it along the in-plane direction in the direction of the arrow in the figure. Figures 2 and 3 show examples in which the holding member 11 and the unit housing 10a are constructed as separate parts, but the holding member 11 and the unit housing 10a may be formed as a single unit. The material that constitutes the holding member 11 is not limited, and resin materials, metal materials, etc. can be used.

[0032] The image display unit 12 functions as a spatial light modulation unit that receives incident light from the light source and emits light modulated by image information from the display area 12a. The specific configuration of the image display unit 12 is not limited, but as an example, a transmissive liquid crystal display device that transmits light incident from the back and emits it from the front can be used. In a transmissive liquid crystal display device, only polarization in a predetermined direction incident on the back side is transmitted. When a transmissive liquid crystal display device is used as the image display unit 12, the transmission axis of the polarizing plate 20 is set to a direction corresponding to the polarization direction of the image light emitted from the image display unit 12.

[0033] The display area 12a is the area on the display surface of the image display unit 12 where the image to be projected as a virtual image P is displayed. In the example shown in Figure 3, the display area 12a is a roughly rectangular area that is elongated in the width direction of the image projection unit 10, but the shape is not limited. The method of using only a part of the display surface of the image display unit 12 as the display area 12a is not limited; the image may be displayed only in a part, or a light-shielding plate with an opening of the same position and shape as the display area 12a may be placed on the display surface of the image display unit 12.

[0034] In the image illumination unit 10 shown in Figures 2 and 3, the illumination light emitted from the light-emitting unit is refracted by the primary lens and secondary lens within the unit housing 10a to obtain a predetermined light distribution and illuminates the image display unit 12. The illumination light illuminated by the image display unit 12 is modulated by the image displayed in the display area 12a and illuminates the polarizing plate 20 as image light. At this time, if the image display unit 12 is a transmissive liquid crystal display device, the image light is polarized in a predetermined direction. Since the transmission axis of the polarizing plate 20 corresponds to the polarization direction of the image light, the image light passes through the polarizing plate 20. The image light that has passed through the polarizing plate 20 is reflected by the primary mirror 30 and secondary mirror 40 as described above and illuminates the windshield WS via the dust cover.

[0035] Furthermore, in the image projection device 100 of this embodiment, ambient light arriving from above the windshield WS enters the housing through the dust cover. A portion of the ambient light is reflected by the secondary mirror 40 and reaches the primary mirror 30, and is reflected again by the primary mirror 30 and reaches the image display unit 12 via the polarizing plate 20. At this time, although the ambient light is unpolarized, the polarization direction that passes through the transmission axis of the polarizing plate 20 is limited, and the polarization component perpendicular to the transmission axis is cut off. Therefore, the amount of ambient light reaching the image display unit 12 can be halved, thereby suppressing the temperature rise of the image display unit 12.

[0036] Figure 4 is a schematic diagram showing the structure of the holding member 11 and the polarizing plate 20. Figure 4(a) is a schematic plan view taken from a direction perpendicular to the polarizing plate 20, and Figure 4(b) is a top view taken from the support portion 11c side of the holding member 11. As shown in Figures 4(a) and 4(b), the holding member 11 comprises a lower frame 11a, a lateral frame 11b, a support portion 11c, a mating portion 11d, and an elastically deformable portion 11e. The polarizing plate 20 of this embodiment comprises a polarization surface 20a, a lower end portion 20b, a slide tab portion 20c, and a movement restricting portion 20d.

[0037] The lower frame 11a is fixed to the upper surface of the unit housing 10a and is located at the lower end of the holding member 11, with lateral frames 11b erected from both ends. The width of the lower frame 11a is preferably greater than the lower end of the polarizing plate 20, and it is preferable that it abuts against the lower end of the polarizing plate 20 to support it. In addition, a slit is provided in the upper part of the lower frame 11a along the width direction, and the vicinity of the lower end of the polarizing plate 20 may be inserted into the slit.

[0038] The lateral frame 11b is a frame erected from the lower frame 11a and extends diagonally upward at a predetermined angle relative to the image display section 12. In this embodiment, a support section 11c, a fitting section 11d, and an elastic deformation section 11e are provided on the inside of the lateral frame 11b (the side facing the polarizing plate 20). The length of the lateral frame 11b may be less than the height of the polarizing plate 20, but it is preferable that it extends at least to the slide tab section 20c. In addition, although this embodiment shows an example in which the lower frame 11a and the lateral frame 11b are formed integrally, the lower frame 11a and the lateral frame 11b may be constructed as separate parts and fixed together.

[0039] The support portion 11c is provided at a position corresponding to the slide tab portion 20c and restricts movement of the polarizing plate 20 in a direction intersecting the in-plane direction, while supporting the polarizing plate 20 so that it can slide in the in-plane direction. In this embodiment, the support portion 11c is a slit shape that protrudes from the slide tab portion 20c toward the polarizing plate 20 and contacts the front and back surfaces of the slide tab portion 20c. The shape and structure of the support portion 11c are not limited, and as an example, it may be a slit provided along the length direction of the side frame 11b. In addition, although this embodiment shows an example in which the support portion 11c and the side frame 11b are formed integrally, the support portion 11c and the side frame 11b may be constructed as separate parts and fixed together.

[0040] The interlocking portion 11d is a projection provided in a shape and position corresponding to the movement restricting portion 20d. Figure 4(a) shows an example of an interlocking portion 11d that is triangular in shape with its vertex protruding in the direction of the polarizing plate 20, but the shape and structure are not limited. Figure 4(a) shows an example in which a small gap is provided between the interlocking portion 11d and the movement restricting portion 20d, but the interlocking portion 11d may be biased by the elastic deformation portion 11e to contact the movement restricting portion 20d. When the interlocking portion 11d interlocks with the movement restricting portion 20d, the movement of the polarizing plate 20 in the sliding direction at the support portion 11c is restricted.

[0041] The elastically deformable portion 11e is a part in which a mating portion 11d is formed, and which elastically deforms due to the interference between the polarizing plate 20 and the mating portion 11d. In the example shown in Figure 4(a), the elastically deformable portion 11e is shown as a leaf spring shape that elastically deforms along the in-plane direction of the polarizing plate 20 when the mating portion 11d comes into contact with the side surface of the polarizing plate 20 and interferes with it. In Figure 4(a), an example is shown in which the lateral frame 11b, the elastically deformable portion 11e, and the mating portion 11d are formed integrally, but they may also be constructed and fixed as separate parts.

[0042] The polarization plane 20a is a portion that has optical properties such as transmitting polarization in the direction of the transmission axis and reflecting or absorbing polarization perpendicular to the transmission axis when image light is incident on it. In this embodiment, the polarization plane 20a is shown as a substantially rectangular shape with the width direction of the image illumination unit 10 as the longitudinal direction. The transmission axis of the polarization plane 20a is along the short direction. Slide tabs 20c are integrally provided at both ends of the polarization plane 20a, and a movement restricting portion 20d is formed on a part of the short side. In the example shown in Figure 4(a), the polarization plane 20a has a symmetrical shape, but it may also have an asymmetrical shape.

[0043] The lower end portion 20b is the region around the lower end of the polarizing plate 20. Figure 4(a) shows an example where the entire width along the lower long side of the substantially rectangular polarization surface 20a is the lower end portion 20b, but the shape and width are not limited. In this embodiment, the end face of the lower end portion 20b abuts against the lower frame 11a, and the lower end portion 20b is inserted into a slit provided in the lower frame 11a. This restricts the downward movement of the polarizing plate 20, and the polarizing plate 20 is supported at three points in conjunction with the two support portions 11c, thereby restricting movement in a direction perpendicular to the plane.

[0044] The slide tab portion 20c is a portion that protrudes from the short sides at both ends in the width direction of the polarization plane 20a. In the example shown in Figure 4(a), the slide tab portion 20c is shown as rectangular, but its shape and size are not limited and it may be semicircular or triangular. Also, in the example shown in Figure 4(a), the position of the slide tab portion 20c is asymmetrical, but it may be provided in a symmetrical position.

[0045] The movement restricting portion 20d is a portion that restricts the movement of the polarizing plate 20 along the in-plane direction. In this embodiment, the movement restricting portion 20d is shown as a notch provided on the side surface of the polarizing plate 20, and is provided in a shape and position corresponding to the mating portion 11d.

[0046] Figure 4(a) shows an example where the slide tab portion 20c is located above the polarizing plate 20 and the movement restricting portion 20d is located near the center of the short side; however, the movement restricting portion 20d may be located above and the slide tab portion 20c may be located near the center. Also, Figure 4(a) shows an example where the support portion 11c is located above the lateral frame 11b and the mating portion 11d and elastic deformation portion 11e are located near the center of the lateral frame 11b in the longitudinal direction; however, the mating portion 11d and elastic deformation portion 11e may be located above and the support portion 11c may be located near the center. Furthermore, they may be located at the upper end or other positions near the center.

[0047] Figure 5 is a schematic diagram showing the process of attaching the polarizing plate 20 to the holding member 11. Figure 5(a) shows the state before attaching the polarizing plate 20, Figure 5(b) shows the state after the polarizing plate 20 has been inserted about halfway into the holding member 11, and Figure 5(c) shows the state after the polarizing plate 20 has been attached to the holding member 11.

[0048] In this embodiment, as shown in Figure 5(a), the polarizing plate 20 is positioned at a location corresponding to the holding member 11, and the polarizing plate 20 is inserted into the holding member 11 from above along the inclination of the lateral frame 11b. As shown in Figure 5(b), as the polarizing plate 20 is inserted into the holding member 11, the mating portion 11d comes into contact with the side surface of the polarizing plate 20, and the mating portion 11d is biased by interference with the polarizing plate 20, causing the elastic deformation portion 11e to elastically deform and the gap between the mating portions 11d on both sides to widen. In this embodiment, since the support portion 11c extends to a part of the polarization surface 20a, it is easy to insert the polarizing plate 20 while sliding it along the lateral frame 11b.

[0049] As shown in Figure 5(c), when the lower end portion 20b of the polarizing plate 20 is inserted up to the lower frame 11a, the movement restricting portion 20d and the mating portion 11d are in corresponding positions. At this time, the mating portion 11d is biased toward the polarizing plate 20 by the elastic force of the elastic deformation portion 11e, and the mating portion 11d mates with the movement restricting portion 20d. In addition, the lower end portion 20b is inserted between the slits of the lower frame 11a, and the slide tab portion 20c is supported by the support portion 11c. As a result, the movement of the polarizing plate 20 in directions intersecting the plane is restricted by the two support portions 11c and the slits of the lower frame 11a. Furthermore, the movement of the polarizing plate 20 in the in-plane direction along the lateral frame 11b is restricted by the mating of the mating portion 11d with the movement restricting portion 20d. In this case, since the movement restricting portion 20d and the mating portion 11d are provided on both sides in the width direction of the polarizing plate 20, the movement of the polarizing plate 20 in the in-plane direction along the lower frame 11a is also restricted.

[0050] As described above, in the image projection device 100 of this embodiment, the holding member 11 has a support portion 11c, an elastically deformable portion 11e, and a mating portion 11d. By restricting movement in the in-plane direction with a movement restricting portion 20d provided on the polarizing plate 20, and restricting movement in a direction intersecting the in-plane direction with the support portion 11c, the assembly process of the polarizing plate 20 can be simplified while maintaining high precision in the relative positional relationship of the polarizing plate 20 with respect to the image display unit 12.

[0051] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to Figure 6. Details that overlap with the first embodiment will be omitted. Figure 6 is a schematic diagram showing the structure of the holding member 11 and the polarizing plate 20 in the image irradiation unit 10 according to this embodiment. Figure 6(a) is a schematic plan view seen from a direction perpendicular to the polarizing plate 20, and Figure 6(b) is a top view of the holding member 11 seen from the support portion 11c side. As shown in Figures 6(a) and (b), the holding member 11 comprises a lower frame 11a, a lateral frame 11b, a support portion 11c, an elastically deformable portion 11e, and a mating portion 11f. The polarizing plate 20 in this embodiment comprises a polarization surface 20a, a lower end portion 20b, and a movement restricting portion 20e. In this embodiment, the polarizing plate 20 is substantially rectangular in shape, and there is no slide tab portion 20c. The shapes of the mating portion 11f and the movement restricting portion 20e differ from those in the first embodiment.

[0052] In this embodiment, as shown in Figure 6(a), the elastically deformable portion 11e extends from the lateral frame 11b toward the polarizing plate 20 and is formed in the shape of a leaf spring that elastically deforms in a direction intersecting the in-plane direction of the polarizing plate 20. The mating portion 11f is a projection formed in the plane of the elastically deformable portion 11e at a position and shape corresponding to the movement restricting portion 20e. The movement restricting portion 20e is a through hole formed in the polarization surface 20a at a position and shape corresponding to the mating portion 11f. Here, an example of a through hole penetrating from the front to the back of the polarizing plate 20 is shown as the movement restricting portion 20e, but the movement restricting portion 20e may be formed in a recessed shape as long as it is deep enough for the mating portion 11f to mate.

[0053] In this embodiment as well, the polarizing plate 20 is positioned at a location corresponding to the holding member 11, and the polarizing plate 20 is inserted into the holding member 11 from above along the inclination of the lateral frame 11b. As the polarizing plate 20 is inserted into the holding member 11, the mating portion 11f comes into contact with the polarization surface 20a, and the mating portion 11f is biased by interference with the polarizing plate 20, causing the elastic deformation portion 11e to elastically deform and the mating portion 11d to move in a direction perpendicular to the plane.

[0054] When the lower end portion 20b of the polarizing plate 20 is inserted up to the lower frame 11a, the movement restricting portion 20e and the mating portion 11f are in corresponding positions. At this time, as shown in Figure 6(b), the mating portion 11f is biased inward towards the movement restricting portion 20e by the elastic force of the elastic deformation portion 11e and inserted, and the mating portion 11f mates with the movement restricting portion 20e. In addition, the lower end portion 20b is inserted between the slits of the lower frame 11a, and both sides of the polarization surface 20a are partially supported by the support portions 11c. As a result, the movement of the polarizing plate 20 in directions intersecting the plane is restricted by the two support portions 11c and the slits of the lower frame 11a. Furthermore, the movement of the polarizing plate 20 in the in-plane direction along the lower frame 11a and the lateral frame 11b is restricted by the mating of the mating portion 11f with the movement restricting portion 20e.

[0055] As described above, in the image projection device 100 of this embodiment, the holding member 11 has a support portion 11c, an elastically deformable portion 11e, and a mating portion 11f. By restricting movement in the in-plane direction with a movement restricting portion 20e provided on the polarizing plate 20, and restricting movement in a direction intersecting the in-plane direction with the support portion 11c, the assembly process of the polarizing plate 20 can be simplified while maintaining high precision in the relative positional relationship of the polarizing plate 20 with respect to the image display unit 12.

[0056] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to Figure 7. Details that overlap with the first embodiment will be omitted. Figure 7 is a schematic diagram showing the structure of the holding member 11 and the polarizing plate 20 in the image irradiation unit 10 according to this embodiment. As shown in Figure 7, the holding member 11 includes a lower frame 11a, a side frame 11b, an upper frame 11g, a mating portion 11d, and an elastically deformable portion 11e. The polarizing plate 20 in this embodiment includes a polarization surface 20a, a lower end portion 20b, and a movement restricting portion 20d. This embodiment differs from the first embodiment in that a slide tab portion 20c is not provided, and the mating portion 11d, the elastically deformable portion 11e, and the movement restricting portion 20d are provided on the longer side of the upper frame 11g.

[0057] In this embodiment, the polarizing plate 20 is curved in the height or width direction, and the lower end portion 20b of the polarizing plate 20 is inserted between the slits provided in the lower frame 11a. This restricts movement in the direction in which the slits intersect the in-plane direction, instead of the support portion 11c. Alternatively, the support portion 11c may be provided separately. When the lower end portion 20b of the polarizing plate 20 is inserted into the slit of the lower frame 11a and the side surface of the polarizing plate 20 in the width direction is fitted into the lateral frame 11b, the movement restricting portion 20d and the mating portion 11d are in corresponding positions. At this time, the mating portion 11d is biased toward the polarizing plate 20 by the elastic force of the elastic deformation portion 11e, and the mating portion 11d mates with the movement restricting portion 20d. As a result, the movement of the polarizing plate 20 in the in-plane direction along the lower frame 11a and the upper frame 11g is restricted by the mating of the mating portion 11d with the movement restricting portion 20d.

[0058] As described above, in the image projection device 100 of this embodiment, the holding member 11 has a support portion 11c, an elastically deformable portion 11e, and a mating portion 11d. By restricting movement in the in-plane direction with a movement restricting portion 20d provided on the polarizing plate 20, and restricting movement in a direction intersecting the in-plane direction with the support portion 11c, the assembly process of the polarizing plate 20 can be simplified while maintaining high precision in the relative positional relationship of the polarizing plate 20 with respect to the image display unit 12.

[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…Polarizing plate 30... Primary mirror 40...Secondary mirror 10a... Unit Housing 11…Retaining member 11a... Lower frame 11b... Side frame 11c...Support part 11d,11f…Joining part 11e...Elastic deformation part 11g... Upper frame 12…Image display section 12a...display area 20a...Plane of polarization 20b…lower end 20c... Slide tab section 20d, 20e... Movement control section

Claims

1. An image projection device that projects a projected image onto a display unit for displaying a virtual image, A polarizing member that transmits polarization in a predetermined direction and blocks polarization perpendicular to the predetermined direction, The system comprises a holding member for holding the polarizing member, The polarizing member is provided with a movement restricting portion that restricts the movement of the polarizing member in the in-plane direction. The image projection device is characterized in that the holding member has a support portion that restricts the movement of the polarizing member in a direction intersecting the in-plane direction, an elastic deformation portion that elastically deforms upon interference with the polarizing member, and a mating portion provided on a part of the elastic deformation portion that mats with the movement restricting portion.

2. An image projection device according to claim 1, The movement restricting portion is a through hole provided in the plane of the polarizing member, The image projection device is characterized in that the fitting portion is a projection provided in a shape and position corresponding to the through hole.

3. An image projection device according to claim 2, The image projection device is characterized in that the elastically deformable portion is elastically deformed in a direction intersecting the plane.

4. An image projection device according to claim 1, The movement restricting portion is a notch provided on the side surface of the polarizing member, The image projection device is characterized in that the fitting portion is a projection provided in a shape and position corresponding to the notch.

5. An image projection device according to claim 4, The image projection device is characterized in that the elastically deformable portion is elastically deformed along the in-plane direction.

6. An image projection device according to claim 1, The image projection apparatus is characterized in that the support portion supports the polarizing member so that it can slide in the in-plane direction.

7. An image projection device according to any one of claims 1 to 6, An image illumination unit that emits image light, The system includes a projection optical unit that projects the image light onto a first distance from the viewpoint position via the display unit, The image projection apparatus is characterized in that the polarizing member is arranged between the projection optical unit and the image irradiation unit.

Images