Image projection unit and image projection device

Abstract

To provide an image projection unit and an image projection device which can be reduced in size while uniformly applying light to an image display part.SOLUTION: An image projection unit (10) includes: a light source part (12) for applying light in a first direction; a primary lens (13) for adjusting a light distribution of the light emitted from the light source part (12); a reflection part (14b) for reflecting the light transmitted by the primary lens (13) in a second direction intersecting with the first direction; a secondary lens (15) for adjusting a light distribution of the light reflected by the reflection part (14b); and an image display part (17) to which the light transmitted by the secondary lens (15) is applied.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image projection unit and an image projection device. [Background technology]

[0002] Conventionally, dashboards that illuminate icons have been used to display various types of information inside vehicles. As the amount of information to be displayed increases, it has been proposed to embed an image display device in the dashboard or to configure the entire dashboard with an image display device.

[0003] However, because the instrument panel is located below the vehicle's windshield, passengers such as the driver must undesirably move their eyes downward while driving in order to view the information displayed on the instrument panel. Therefore, image projection devices such as head-up displays (hereinafter referred to as HUDs) have been proposed that project images onto the windshield so that passengers can read information when they view the area ahead of the vehicle (see, for example, Patent Documents 1 and 2).

[0004] In the image projection devices disclosed in Patent Documents 1 and 2, an image projection unit emits light containing an image, which is reflected by a free-form mirror or the like, and reaches the viewpoint of the occupant so that the image is formed in space via a display unit such as a windshield. This allows the occupant to perceive the image as being displayed at the imaging position in the depth direction due to the light incident on the viewpoint. It has also been proposed to emit multiple beams of image light to form multiple virtual images at different distances from the windshield. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-119248 [Patent Document 2] Japanese Patent Application Publication No. 2019-119262 Summary of the Invention [Problem to be solved by the invention]

[0006] In such conventional image projection units, a projection image is displayed using an image display unit such as a liquid crystal display device, and the image light is projected by irradiating it with light from a light source unit disposed behind the image display unit. Furthermore, when a light-emitting element such as an LED (Light Emitting Diode) is used as the light source, the light from the light-emitting element needs to be collimated and uniformly incident on the image display unit. Therefore, it is necessary to arrange multiple lenses between the light-emitting element and the image display unit to ensure an optical distance. This makes it difficult to miniaturize the image projection unit.

[0007] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide an image projection unit and an image projection device that can be made compact while uniformly irradiating light onto the image display unit. [Means for solving the problem]

[0008] In order to solve the above problem, the image projection unit of the present invention is characterized by having a light source unit that irradiates light in a first direction, a primary lens that adjusts the distribution of the light irradiated from the light source unit, a reflecting unit that reflects the light that has passed through the primary lens in a second direction that intersects the first direction, a secondary lens that adjusts the distribution of the light reflected by the reflecting unit, and an image display unit onto which the light that has passed through the secondary lens is irradiated.

[0009] In the image projection unit of the present invention, light is emitted from the light source unit in a first direction, the light that passes through the primary lens is reflected in a second direction by the reflecting unit, and the light reflected by the reflecting unit passes through the secondary lens and is irradiated onto the image display unit.This makes it possible to irradiate light uniformly onto the image display unit while bending the optical path to ensure the optical path length and achieve miniaturization.

[0010] In one aspect of the present invention, a lower housing is provided with an inclined surface that intersects with the first direction and the second direction, and the reflecting portion is provided on the inclined surface.

[0011] In one aspect of the present invention, the reflecting portion is a reflective film formed on the inclined surface and reflects the light.

[0012] In one aspect of the present invention, the reflecting portion is a flat mirror that is disposed on the inclined surface and reflects the light.

[0013] In one aspect of the present invention, the reflecting portion is a reflective polarizing plate that is arranged on the inclined surface and reflects polarized components of the light in a predetermined direction and transmits polarized components in a direction intersecting the predetermined direction.

[0014] In one aspect of the present invention, an upper housing is provided that holds the image display unit, and the secondary lens is disposed between the upper housing and the lower housing.

[0015] In addition, in order to solve the above problem, the image projection device of the present invention is characterized by comprising an image projection unit described in any one of the above, and a projection mirror unit that projects the light irradiated from the image projection unit onto a display unit of a vehicle. [Effects of the Invention]

[0016] The present invention can provide an image projection unit and an image projection device that can be made compact while uniformly irradiating light onto an image display unit. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing projection of a virtual image P using the image projection device 100 according to the first embodiment. [Figure 2] 1 is an exploded perspective view illustrating an overview of an image projection unit 10 according to a first embodiment. [Figure 3]2 is a schematic perspective view showing an example of the configuration of a lower housing 14. FIG. [Figure 4] FIG. 2 is a schematic perspective view showing an example of the configuration of an upper housing 16. [Figure 5] FIG. 1 is a schematic perspective view illustrating an overview of an image projection unit 10 according to a first embodiment. [Figure 6] 1 is a schematic cross-sectional view for explaining the path of irradiated light within the image projection unit 10, showing the reflective portion 14b side obliquely from the heat sink 11 side. [Figure 7] 1 is a schematic cross-sectional view for explaining the path of irradiation light within the image projection unit 10, showing the light source unit 12 side obliquely from the reflecting unit 14b side. [Figure 8] 8A and 8B are schematic diagrams showing examples of the configuration of the reflecting section 14b according to the second embodiment, in which FIG. 8A shows an example in which a flat mirror 14d is provided on the inclined surface, and FIG. 8B shows an example in which a reflective polarizing plate 14e is provided on the inclined surface. DETAILED DESCRIPTION OF THE INVENTION

[0018] (First embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and redundant explanations will be omitted as appropriate. In the following explanation, an image projection device 100 according to the present invention will be described by way of example in which it is applied to a HUD mounted on a vehicle or the like.

[0019] 1 is a schematic diagram showing the projection of a virtual image P using an image projection device 100 according to this embodiment. As shown in FIG. 1, the image projection device 100 includes an image projection unit 10, a first mirror 20, a second mirror 30, a housing unit 50, and a dust cover 60. As shown in FIG. 1, image light projected from the image projection device 100 is reflected by a windshield (display unit) WS and irradiated onto a driver's viewpoint position 40. The driver visually recognizes the virtual image P formed on an extension of the optical path along which the image light is incident.

[0020] 1, each part is controlled by a control unit connected to the other parts so as to be able to communicate information with them. The configuration of the control unit is not limited, but an example includes a CPU (Central Processing Unit) for processing information, a memory device, a recording medium, an information communication device, etc. The control unit controls the operation of each part in accordance with a predetermined program, and sends information including an image (image information) to the image projection unit 10.

[0021] The image projection unit 10 is a part that irradiates image light containing an image based on image information from the control unit. The specific configuration of the image projection unit 10 is not limited, and a conventionally known device such as a liquid crystal display device or an organic EL display device can be used. As an example, a device that irradiates light from a light emitting diode (LED) on the back side of a liquid crystal display device is used.

[0022] The first mirror 20 is an optical element that receives the image light emitted from the image projection unit 10 and reflects the image light toward the second mirror 30. In the example shown in FIG. 1, the first mirror 20 is a free-form surface mirror with an optical design necessary for projecting the image light as a virtual image P. The second mirror 30 is an optical element that receives the image light reflected by the first mirror 20 and reflects the image light toward the windshield WS. In the example shown in FIG. 1, the second mirror 30 is a free-form surface mirror with an optical design necessary for projecting the image light as a virtual image P. The second mirror 30 may also be configured to have an adjustable 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.

[0023] The reflective surfaces of the first mirror 20 and the second mirror 30 are designed to expand the light diameter in the driver's line of sight in order to project the image light as a virtual image P through the windshield WS. Here, expanding the light diameter in the line of sight includes not only the case where the light diameter expands consistently after reflection, but also the case where the light diameter shrinks and then expands after forming an image at an intermediate point. The combination of the first mirror 20 and the second mirror 30 has the function of projecting the image light through the windshield WS and corresponds to the projection mirror unit in this invention.

[0024] The housing unit 50 is a housing that forms the outer shape of the image projection device 100 and houses the other components inside. An opening is provided at the top of the housing unit 50, and a dustproof cover 60 is provided over the opening to seal the interior. In FIG. 1, the cross-sectional shape of the housing unit 50 is shown as a box shape with a flat bottom and sloping sides, but the shape of the housing unit 50 is not limited. The material that forms the housing unit 50 is not limited, and a resin material or a metal material that blocks light can be used.

[0025] The dustproof cover 60 is made of a light-transmitting material and is a member disposed to cover the opening of the housing part 50. Although not shown in Fig. 1, the dustproof cover 60 is fixed to the housing part 50 in a structure that leaves no gap between them, thereby preventing dust and dirt from entering the housing part 50. There are no limitations on the material that can be used to make the dustproof cover 60, and known resin materials or glass that transmit image light can be used.

[0026] 1, the optical path of the image light is depicted as a single straight line. However, the actual image light is displayed with a predetermined area in the image projection unit 10, and has a predetermined area in the direction perpendicular to the traveling direction. The image light may also be reflected by the first mirror 20, its light diameter reduced as it travels, and may form an intermediate image at an intermediate imaging position F (not shown) between the first mirror 20 and the second mirror 30. When the image light reflected by the first mirror 20 is imaged at the intermediate imaging position F, the cross-sectional area through which the image light passes is minimized at the intermediate imaging position F between the first mirror 20 and the second mirror 30.

[0027] The windshield WS is a part of the vehicle that is provided in front of the driver's seat and transmits visible light. The windshield WS corresponds to the display unit of the present invention because the windshield WS, on the inside surface of the vehicle, reflects image light incident from the second mirror 30 toward the viewpoint and transmits light from outside the vehicle toward the viewpoint. While an example in which the windshield WS is used as the display unit is shown here, a combiner may be provided as a display unit separate from the windshield WS and reflect light from the second mirror 30 toward the viewpoint. Furthermore, the display unit is not limited to being located at the front of the vehicle, and may be located to the side or rear as long as it projects an image toward the viewpoint of the passenger.

[0028] The virtual image P is an image that appears as if it were formed in space when image light reflected by the windshield WS reaches the viewpoint (eyebox) of the driver or the like. The position at which the virtual image P is formed is determined by the spread angle of the light emitted from the image projection unit 10 as it travels toward the viewpoint after being reflected by the first mirror 20, the second mirror 30, and the windshield WS. The display content of the image projected as the virtual image P may include auxiliary information related to driving such as a warning image or emergency information, a volume indicator, a driving direction guide, etc.

[0029] Fig. 2 is an exploded perspective view illustrating an overview of the image projection unit 10 according to this embodiment. Fig. 3 is a schematic perspective view showing an example of the configuration of the lower housing 14. Fig. 4 is a schematic perspective view showing an example of the configuration of the upper housing 16.

[0030] 2, the image projection unit 10 includes a heat sink 11, a light source unit 12, a primary lens 13, a lower housing 14, a secondary lens 15, an upper housing 16, an image display unit 17, and a light blocking member 18. The light source unit 12 and the primary lens 13 are fixed together to the heat sink 11 by fastening members 19a. The lower housing 14 and the upper housing 16 are fastened together by fastening members 19b, with the secondary lens 15 disposed and sandwiched between them. The lower housing 14 and the heat sink 11 are fastened together by fastening members 19c, with the light source unit 12 and the primary lens 13 disposed between them.

[0031] The heat sink 11 is a member for dissipating heat generated by the light emitting element 12a as a result of irradiation with irradiated light via the light source unit 12, and is disposed in contact with the rear surface of the light source unit 12. The material constituting the heat sink 11 is not limited, but metal materials such as aluminum, or resins mixed with fillers having high thermal conductivity, can be used. The shape of the heat sink 11 is not limited, but it is preferable that the heat sink 11 be provided with multiple heat dissipation fins to improve heat dissipation. The light source unit 12 and primary lens 13 are fixed together to the heat sink 11 using fastening members 19a. A thermally conductive grease or the like with good thermal conductivity is disposed between the heat sink 11 and the light source unit 12.

[0032] The light source unit 12 is a component having a wiring pattern formed on one surface of a substrate, a light emitting element 12a mounted on the substrate, and emitting light in a leftward direction (first direction) in the drawing. The light source unit 12 may be equipped with electronic components for driving the light emitting element 12a to form a drive circuit. The light source unit 12 may also be provided with a terminal unit (not shown), and power and control signals may be supplied from a cable or the like connected to the terminal unit.

[0033] The light emitting elements 12a are, for example, semiconductor light emitting elements such as LEDs (Light Emitting Diodes), and are arranged in a predetermined direction. The light emitting elements 12a may be of any color, but in this embodiment, they are white, for example. In this embodiment, the light emitting elements 12a are arranged in one row, but may be arranged in two or more rows. The light irradiated from the light emitting elements 12a is unpolarized.

[0034] The primary lens 13 is an optical element disposed in the light emission direction of the light-emitting elements 12a, and has the function of concentrating the light emitted from the light-emitting elements 12a and emitting it as, for example, parallel light or light close to parallel light (hereinafter, both of these will be collectively referred to as "substantially parallel light"). FIG. 2 shows an example of the primary lens 13 in which a plurality of microlenses 13a are integrally formed on a plate-like portion. The microlenses 13a are provided at positions corresponding to the light-emitting elements 12a of the light source unit 12. Although FIG. 2 shows an example in which a plurality of microlenses 13a are arranged on the primary lens 13, the specific lens shape is not limited thereto, and a single rod-shaped lens may be used for a plurality of light-emitting elements 12a, or a plurality of TIR (Total Internal Reflection) lenses or the like may be provided.

[0035] The lower housing 14 constitutes the lower side of the image projection unit 10 and is a member that holds the secondary lens 15. In the example shown in FIGS. 2 and 3, the lower housing 14 includes a case portion 14a, a reflecting portion 14b, and a lens holding portion 14c. The case portion 14a is attached to the heat sink 11 and houses the light source portion 12 and the primary lens 13 between it and the heat sink 11. A sloped surface that is inclined with respect to the direction in which light is emitted from the light source portion 12 (first direction) is formed in a part of the case portion 14a, and the reflecting portion 14b is provided on the sloped surface.

[0036] The reflecting portion 14b is provided on the inclined surface of the housing portion 14a and reflects the irradiated light in a second direction intersecting the first direction. For example, if the first direction is the leftward direction in the figure, the second direction corresponds to the upward direction in the figure where the image display unit 17 is located. In the example shown in FIGS. 2 and 3, a reflective film is provided on the inclined surface of the housing portion 14a, and the reflective film reflects the irradiated light, thereby forming the reflecting portion 14b. The specific structure and type of the reflective film are not limited, but a metal reflective film may be formed on the inclined surface by vapor deposition or plating, or a dielectric multilayer film formed by stacking films with different refractive indices may be formed. The lens holding portion 14c is formed as part of the housing portion 14a and is a portion for mounting the secondary lens 15. In the example shown in FIGS. 2 and 3, the lens holding portions 14c are provided on both sides of the reflecting portion 14b.

[0037] The secondary lens 15 is an optical component that adjusts the light distribution of the irradiated light reflected by the reflecting portion 14b and irradiates the image display portion 17. In the example shown in FIG. 2, the secondary lens 15 includes a lens portion 15a and a fixing portion 15b. The lens portion 15a has a lens shape that refracts the irradiated light as it passes through to adjust the light distribution. The optical characteristics of the lens portion 15a are not limited, but it is preferable that the optical characteristics are such that the irradiated light is uniformly irradiated within an opening 16b of the upper housing 16, which will be described later. The fixing portions 15b are flat plate-shaped portions extending horizontally on both sides of the lens portion 15a. The fixing portions 15b are formed at positions corresponding to the lens holding portions 14c of the lower housing 14 and are sandwiched between the lens holding portions 14c and the upper housing 16. As a result, the secondary lens 15 is positioned and held between the upper housing 16 and the lower housing 14.

[0038] The upper housing 16 constitutes the upper side of the image projection unit 10 and is a member that holds the image display unit 17 and the light blocking member 18. In the example shown in FIGS. 2 and 4, the upper housing 16 includes a case portion 16a, an opening 16b, and a circuit holding portion 16c. The case portion 16a is attached to the lower housing 14 and holds the secondary lens 15 between itself and the lower housing 14. The image display unit 17 and the light blocking member 18 are disposed on the upper surface of the case portion 16a and hold both of them.

[0039] The opening 16b is an opening provided in the light-shielding surface 18a, and is a portion through which the irradiated light that has passed through the secondary lens 15 passes. The opening 16b is provided at a position corresponding to the image display area of ​​the image display unit 17, and has a shape corresponding to the image display area. The circuit holding unit 16c is a plate-like portion that stands upright above the housing unit 16a. The circuit holding unit 16c is provided at a position facing the control circuit unit 17b and the circuit holding unit 18c, and holds the control circuit unit 17b between itself and the circuit holding unit 18c.

[0040] The image display unit 17 functions as a spatial light modulator that receives illumination light transmitted through the secondary lens 15, modulates the light according to image information, and emits the modulated light from the display surface 17a. The image display unit 17 includes a control circuit 17b and a flexible cable 17c connected to the display surface 17a. The control circuit 17b controls the display surface 17a to display an image. The control circuit 17b is located at a position corresponding to the circuit holder 16c and is sandwiched between the circuit holder 18c (described later). The flexible cable 17c is wiring that transmits power and control signals from the outside to the display surface 17a and the control circuit 17b. The specific configuration of the image display unit 17 is not limited. For example, a transmissive liquid crystal display device that transmits light incident from the backside and emits it from the front side can be used. In a transmissive liquid crystal display device, only polarized light incident on the backside in a predetermined direction is transmitted.

[0041] The light-shielding member 18 is disposed in the light emission direction of the image display unit 17 and is made of a light-shielding material. In the example shown in FIG. 2, the light-shielding member 18 has a light-shielding surface 18a, an opening 18b, and a circuit holding portion 18c. The light-shielding surface 18a is a plate-like portion disposed to cover the display surface 17a of the image display unit 17. A portion of the light-shielding surface 18a extends downward to form an attachment portion for the upper housing 16. The opening 18b is an opening provided within the light-shielding surface 18a and is a portion through which image light from the display surface 17a passes. The opening 18b is provided at a position corresponding to the opening 16b provided in the upper housing 16 and has a shape corresponding to the opening 16b. The circuit holding portion 18c is a plate-like portion erected upward from the light-shielding surface 18a. The circuit holding portion 18c is provided at a position opposite the circuit holding portion 16c, and the control circuit unit 17b is disposed between the circuit holding portion 16c and the circuit holding portion 16c.

[0042] The fastening members 19a to 19c are members for fastening each member to position and fix them. Furthermore, each part fastened with the fastening members 19a to 19c has an opening or a screw hole of a shape corresponding to the fastening members 19a to 19c. The specific configuration of the fastening members 19a to 19c is not limited, and conventionally known screws or bolts can be used.

[0043] FIG. 5 is a schematic perspective view illustrating an overview of an image projection unit 10 according to this embodiment. For simplicity, fastening members 19a to 19c are not shown in FIG. 5. As shown in FIG. 5, the image projection unit 10 has a heat sink 11 attached to the rear of a lower housing 14, and an upper housing 16 attached above the lower housing 14. An image display unit 17 and a light-blocking member 18 are also disposed on the upper housing 16. In FIG. 5, the display surface 17a of the image display unit 17 is not shown because it is covered by the light-blocking surface 18a of the light-blocking member 18.

[0044] The control circuit section 17b of the image display section 17 is erected upward along the circuit holding section 16c, and the flexible cable 17c straddles the upper part of the circuit holding section 16c and is taken out rearward. The tip of the flexible cable 17c is connected to a separately provided connector (not shown) or the like. The control circuit section 17b is sandwiched and held between the circuit holding section 16c and the circuit holding section 18c. The image display area on the display surface 17a of the image display section 17 is exposed from the opening 18b of the light blocking member 18.

[0045] Image projection unit 10 is configured by combining lower housing 14, upper housing 16, and heat sink 11, and thereby houses and holds light source unit 12, primary lens 13, and secondary lens 15. Furthermore, lower housing 14, upper housing 16, and heat sink 11 are all made of materials that block visible light, so that the light emitted from light source unit 12 is projected to the outside as image light only from opening 18b of light-blocking member 18.

[0046] Fig. 6 is a schematic cross-sectional view illustrating the path of irradiated light within the image projection unit 10, showing the reflective section 14b side obliquely from the heat sink 11 side. Fig. 7 is a schematic cross-sectional view illustrating the path of irradiated light within the image projection unit 10, showing the reflective section 14b side obliquely from the light source section 12 side.

[0047] As shown in FIGS. 6 and 7 , in the image projection unit 10, the light emitted from the light-emitting element 12a of the light source unit 12 is unpolarized, meaning that the polarization direction is not limited. The light emitted in a first direction from the light source unit 12 is incident on the microlens 13a of the primary lens 13, where it is collimated, and then incident on the reflector 14b provided on the inclined surface of the lower housing 14. The light incident on the reflector 14b is reflected in a second direction, passes through the secondary lens 15, passes through the opening 16b of the upper housing 16, and is incident on the display surface 17a of the image display unit 17. The display surface 17a transmits the polarized light in a predetermined direction, becoming image light containing the image depicted in the image display area. The image light emitted from the display surface 17a passes through the opening 18b of the light-shielding member 18 and is emitted from the image projection unit 10 to the outside.

[0048] 1, in image projection device 100, image light emitted from image projection unit 10 is reflected by first mirror 20 and second mirror 30, and is then irradiated onto windshield WS via dustproof cover 60. The image light that reaches windshield WS is reflected by windshield WS and irradiated onto driver's viewpoint 40, and the driver views virtual image P formed on an extension of the optical path along which the image light entered.

[0049] 6 and 7, in image projection unit 10, reflective portion 14b reflects irradiated light from the first direction to the second direction, so that the optical path of irradiated light irradiated from light source unit 12 is bent by reflective portion 14b and reaches image display unit 17. This allows space to be effectively utilized while maintaining the optical path of the irradiated light, reducing the footprint of image projection unit 10 and achieving miniaturization and space savings. Furthermore, reflective portion 14b is located between primary lens 13 and secondary lens 15 on the optical path of the irradiated light, so it reflects the irradiated light that has been made into approximately parallel light by primary lens 13. This facilitates the optical design of primary lens 13, reflective portion 14b, and secondary lens 15.

[0050] Furthermore, since light source unit 12 and primary lens 13 are positioned and fixed collectively to heat sink 11 by fastening members 19a, it becomes easy to align the optical axes of light source unit 12 and primary lens 13 during assembly. Furthermore, since secondary lens 15 is disposed between lower housing 14 and upper housing 16, it becomes easy to align the position and optical axis of reflecting portion 14b and secondary lens 15. Furthermore, since fixing portion 15b of secondary lens 15 is configured in a position and shape that corresponds to lens holding portion 14c of lower housing 14, it becomes possible to position and align the optical axis simply by placing secondary lens 15 on case portion 14a of lower housing 14.

[0051] Furthermore, control circuit section 17b of image display section 17 is disposed outside the container formed by lower housing 14, upper housing 16, and heat sink 11. More specifically, in the example shown in Figures 2 and 5, control circuit section 17b is held by circuit holders 16c and 18c that are erected upward from a position close to heat sink 11 of casing section 16a. This means that control circuit section 17b is not located inside the container and does not obstruct the optical path of the irradiated light, making it even easier to achieve a compact and space-saving image projection unit 10.

[0052] As described above, in the image projection unit 10 and image projection device 100 of this embodiment, light is irradiated in a first direction from the light source section 12, the light that passes through the primary lens 13 is reflected in a second direction by the reflecting section 14b, and the light reflected by the reflecting section 14b passes through the secondary lens 15 and is irradiated onto the image display section 17. Therefore, it is possible to irradiate light uniformly onto the image display section 17 while bending the optical path to ensure the optical path length and achieve miniaturization.

[0053] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 8. Description of content that overlaps with the first embodiment will be omitted. FIG. 8 is a schematic diagram showing an example of the configuration of the reflector 14b according to this embodiment, where FIG. 8(a) shows an example in which a flat mirror 14d is provided on the inclined surface, and FIG. 8(b) shows an example in which a reflective polarizing plate 14e is provided on the inclined surface. In the first embodiment, an example in which a reflective film is formed on the inclined surface of the housing 14a as the reflector 14b was shown, but in this embodiment, a separately formed member is arranged on the inclined surface, which is different from the first embodiment.

[0054] 8(a), the reflecting section 14b may be configured by arranging a flat mirror 14d along the inclined surface of the housing section 14a. The flat mirror 14d is a flat member having a mirror surface that reflects visible light, and is configured as a separate body from the lower housing 14. The specific configuration of the flat mirror 14d is not limited, and it may be a conventionally known structure in which a metal reflective film such as aluminum is formed on the surface of glass or resin, or a structure in which the surface of a metal plate is mirror-polished.

[0055] As shown in FIG. 8(b), a reflective polarizer 14e may be disposed along the inclined surface of the housing 14a to form the reflector 14b. The reflective polarizer 14e is an optical member that reflects polarized light components in a predetermined direction and transmits polarized light components in a direction intersecting the predetermined direction, and is configured as a separate member from the lower housing 14. The polarization direction transmitted by the reflective polarizer 14e is not limited, but must ultimately match the polarization direction transmitted by the display surface 17a of the image display unit 17. As an example, the reflective polarizer 14e may transmit light polarized in the horizontal direction in FIG. 8 (e.g., p-polarized light) and reflect light polarized in a direction perpendicular to the paper surface (e.g., s-polarized light).

[0056] By using reflective polarizing plate 14e, even if unpolarized light is emitted from light source unit 12, the light that reaches display surface 17a of image display unit 17 has only the polarization direction that is transmitted by display surface 17a and used as image light. Therefore, the light that reaches display surface 17a does not contain any polarized component that is blocked by display surface 17a, and the amount of light that is absorbed by display surface 17a is suppressed, thereby suppressing temperature rise and deterioration of display surface 17a.

[0057] Although Figures 3 and 8 show examples of a flat reflecting surface as reflecting portion 14b, reflecting portion 14b may be configured as a convex mirror or concave mirror having a predetermined optical power, or as a free-form surface mirror whose curvature changes within the plane.

[0058] 8(a) and 8(b), the reflecting portion 14b is configured separately from the lower housing 14 and is disposed on the inclined surface of the case portion 14a. This makes it possible to accommodate various vehicle models by simply replacing the separately configured reflecting portion 14b, even if the optical characteristics required of the image projection unit 10 are different.

[0059] In addition, in the image projection unit 10 and image projection device 100 of this embodiment, light is irradiated in a first direction from the light source section 12, the light that passes through the primary lens 13 is reflected in a second direction by the flat mirror 14d or the reflective polarizing plate 14e, and the reflected light passes through the secondary lens 15 and is irradiated onto the image display section 17.Therefore, it is possible to irradiate light uniformly onto the image display section 17 while bending the optical path to ensure the optical path length and achieve miniaturization.

[0060] (Third embodiment) Next, a third embodiment of the present invention will be described. Details that overlap with the first embodiment will not be described. In the first embodiment, an example was shown in which circuit holding portions 16c and 18c were erected upward from a position close to heat sink 11 of housing portion 16a. However, the position and extending direction of control circuit portion 17b are not limited as long as it can be arranged outside the container formed by lower housing 14, upper housing 16, and heat sink 11. As an example, plate-shaped circuit holding portions 16c and 18c may extend toward lower housing 14 from a position close to opening 16b of housing portion 16a.

[0061] The present invention is not limited to the above-described embodiments, 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]

[0062] 100...Image projection device 10...Image projection unit 20...1st mirror 30...Second mirror 40...Viewpoint position 50...Housing part 60...Dustproof cover 11...Heat sink 12...Light source section 12a...light-emitting element 13...Primary lens 13a...Microlens 14...Lower housing 14a...Housing section 14b…Reflection part 14c...Lens holder 14d...Flat mirror 14e…Reflective polarizing plate 15...Secondary lens 15a...Lens section 15b…Fixed part 16...Upper housing 16a...Housing section 16b...Opening 16c...Circuit holding part 17...Image display section 17a...display surface 17b...Control circuit section 17c...flexible cable 18...Light blocking member 18a…shading surface 18b…Opening 18c...Circuit holding part 19a to 19c... Fastening members

Claims

1. a light source unit that irradiates light in a first direction; a primary lens that adjusts the light distribution of the light emitted from the light source unit; a reflecting portion that reflects the light that has passed through the primary lens in a second direction that intersects with the first direction; a secondary lens that adjusts the light distribution of the light reflected by the reflecting portion; an image display unit that is irradiated with the light that has passed through the secondary lens.

2. 2. The image projection unit according to claim 1, a lower housing having an inclined surface formed thereon that intersects with the first direction and the second direction; The image projection unit is characterized in that the reflecting portion is provided on the inclined surface.

3. 3. The image projection unit according to claim 2, The image projection unit is characterized in that the reflecting portion is a reflective film formed on the inclined surface and reflects the light.

4. 3. The image projection unit according to claim 2, The image projection unit is characterized in that the reflecting portion is a flat mirror disposed on the inclined surface and reflects the light.

5. 3. The image projection unit according to claim 2, The image projection unit is characterized in that the reflecting portion is a reflective polarizing plate that is arranged on the inclined surface and reflects polarized components of the light in a predetermined direction and transmits polarized components in a direction intersecting the predetermined direction.

6. 3. The image projection unit according to claim 2, an upper housing for holding the image display unit; The image projection unit is characterized in that the secondary lens is disposed between the upper housing and the lower housing.

7. An image projection unit according to any one of claims 1 to 6; An image projection device comprising: a projection mirror portion that projects the light emitted from the image projection unit onto a display portion of a vehicle.

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