Light source unit and image display device

Abstract

A light source unit is provided with: a display device capable of displaying an image; a first prism sheet on which light emitted from the display device is incident; and an imaging optical system. The imaging optical system includes an input element to which the light emitted from the first prism sheet is incident and an output element to which the light passing through the input element is incident, and forms a first image corresponding to the image with the light emitted from the output element. The imaging optical system has great telecentricity on the first image side. The light emitted from the display device has a substantially Lambert-type light distribution.

Description

Technical Field

[0001] Embodiments relate to a light source unit and an image display device. Background Art

[0002] Patent document 1 discloses a technology that sequentially reflects light emitted from a display device capable of displaying an image using a plurality of reflectors, and further reflects the light reflected by the last reflector toward a user using a reflective member such as a windshield, so that the user can recognize a virtual image corresponding to the image displayed by the display device. This device is expected to be miniaturized.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2016 / 208195 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] The embodiments of the present invention have been made in view of the above-mentioned problems, and an object of the present invention is to provide a light source unit and an image display device that can be miniaturized.

[0008] Technical solutions for solving technical problems

[0009] An embodiment of the present invention provides a light source unit, which includes: a display device capable of displaying an image; a first prism sheet into which light emitted from the display device is incident; and an imaging optical system. The imaging optical system includes an input element into which light emitted from the first prism sheet is incident, and an output element into which light passing through the input element is incident, so that light emitted from the output element forms a first image corresponding to the image. The imaging optical system has a substantially telecentric property on the first image side. The light emitted from the display device has a substantially Lambertian light distribution.

[0010] An embodiment of the present invention provides an image display device, comprising: the light source unit; and a reflection unit separated from the light source unit and reflecting light emitted from the imaging optical system. The first image is formed between the light source unit and the reflection unit.

[0011] Effects of the Invention

[0012] According to the embodiment, a light source unit and an image display device that can be miniaturized can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is an end view showing an image display device according to a first embodiment.

[0014] FIG. 2 is a plan view of a display device showing a light source unit according to the first embodiment.

[0015] FIG. 3A is a perspective view showing a first prism sheet of the light source unit according to the first embodiment.

[0016] 3B is an end view showing the first prism sheet of the light source unit according to the first embodiment.

[0017] 3C is an end view showing the first prism sheet of the light source unit according to the first embodiment.

[0018] FIG. 4 is an end view showing the display device of the image display device according to the first embodiment.

[0019] FIG. 5A is an optical diagram showing the function of the second prism in the first embodiment.

[0020] FIG. 5B is a diagram showing a pixel of a display device.

[0021] FIG. 5C is a diagram showing a pixel enlarged by the first prism.

[0022] FIG. 5D is a diagram showing a pixel further enlarged by the second prism.

[0023] FIG. 6 is a schematic diagram showing a scene viewed from a viewer in a driver's seat in the first embodiment.

[0024] FIG. 7A is a schematic diagram illustrating the principle of the light source unit according to the first embodiment.

[0025] FIG. 7B is a schematic diagram showing the principle of a light source unit according to a reference example.

[0026] FIG. 8A is a graph showing light distribution patterns of light emitted from one light emitting region in Examples 1, 11, and the reference example.

[0027] FIG. 8B is a graph showing the uniformity of brightness of the second image in Examples 1 to 12 and the reference example.

[0028] FIG. 9 is a plan view showing a display device according to a second embodiment.

[0029] FIG. 10A is a plan view showing a prism sheet in the second embodiment.

[0030] FIG. 10B is an end view taken along the line XB-XB shown in FIG. 10A .

[0031] FIG. 11 is a plan view showing a display device and a prism sheet according to the second embodiment.

[0032] FIG. 12A is a diagram showing a state in which some pixels in a display device are lit.

[0033] FIG. 12B is a diagram showing a pixel enlarged by the first prism.

[0034] FIG. 13A is an end view showing a display device and a first prism sheet according to the second embodiment.

[0035] FIG. 13B is an optical diagram showing the first prism according to this embodiment.

[0036] FIG. 13C is a mathematical formula showing the relationship among distance, prism angle, refractive index, and pixel displacement.

[0037] FIG13D is a graph showing the relationship between the distance required to obtain a desired pixel shift amount and the prism angle, with the horizontal axis representing the pixel shift amount and the vertical axis representing the prism angle.

[0038] FIG. 14A is a diagram showing the distribution of light transmitted through the first prism sheet, and shows a case where the ratio of the prism pitch to the distance is 1.5%.

[0039] FIG. 14B is a diagram showing the distribution of light transmitted through the first prism sheet, and shows a case where the ratio of the prism pitch to the distance is 5.0%.

[0040] FIG. 15 is a plan view showing a first prism sheet according to a third embodiment.

[0041] FIG. 16A is a diagram showing one pixel in the third embodiment.

[0042] FIG. 16B is a diagram showing a pixel enlarged by the first prism.

[0043] FIG. 16C is a diagram showing a pixel further enlarged by the second prism.

[0044] FIG. 17A is a diagram showing an image displayed on a display device in the third embodiment.

[0045] FIG. 17B is a diagram showing an image magnified by the first prism.

[0046] FIG. 17C is a diagram showing an image further magnified by the second prism.

[0047] 18A is a side view showing a display device, a first prism sheet, and a second prism sheet of a light source unit according to a fourth embodiment.

[0048] FIG. 18B is a plan view showing a first prism sheet according to the fourth embodiment.

[0049] FIG. 18C is a plan view showing a second prism sheet according to the fourth embodiment.

[0050] 19 is a side view showing a display device, a first prism sheet, a second prism sheet, and a third prism sheet of a light source unit according to a fifth embodiment.

[0051] FIG. 20A is a plan view showing a first prism sheet according to the fifth embodiment.

[0052] FIG. 20B is a plan view showing a second prism sheet according to the fifth embodiment.

[0053] FIG. 20C is a plan view showing a third prism sheet according to the fifth embodiment.

[0054] FIG. 21A is a schematic diagram showing the operation of the fifth embodiment.

[0055] FIG. 21B is a schematic diagram showing the operation of the fifth embodiment.

[0056] FIG. 21C is a schematic diagram showing the operation of the fifth embodiment.

[0057] FIG. 21D is a schematic diagram showing the operation of the fifth embodiment.

[0058] FIG. 22 is a perspective view showing a first prism sheet according to the sixth embodiment.

[0059] FIG. 23 is an end view showing an image display device according to the seventh embodiment.

[0060] FIG. 24 is a schematic diagram showing a scene viewed from a viewer in a driver's seat in the seventh embodiment.

[0061] FIG. 25 is an end view showing an image display device according to the eighth embodiment.

[0062] FIG. 26 is a cross-sectional view showing, in an enlarged manner, a portion of the display device and the reflective polarization element shown in FIG. 25 .

[0063] FIG. 27 is a side view showing a light source unit according to a ninth embodiment.

[0064] FIG. 28 is a side view showing a light source unit according to a modification of the ninth embodiment. DETAILED DESCRIPTION

[0065] Below, each embodiment and its modified examples are described with reference to the accompanying drawings. It should be noted that the accompanying drawings are schematic or conceptual drawings, which are appropriately emphasized or simplified. For example, the relationship between the thickness and width of each part, the ratio of the size between the parts, etc. are not necessarily the same as in reality. In addition, even when representing the same part, the mutual dimensions or ratios are sometimes represented differently according to the accompanying drawings. Moreover, in this specification and the accompanying drawings, the same figure marks are marked for the elements that are the same as those described in the drawings that have been shown, and the detailed description is appropriately omitted.

[0066] <First embodiment>

[0067] First, the first embodiment will be described.

[0068] FIG. 1 is an end view showing an image display device according to the present embodiment.

[0069] FIG. 2 is a plan view of a display device showing a light source unit according to the present embodiment.

[0070] FIG. 3A is a perspective view showing a first prism sheet of the light source unit according to the present embodiment.

[0071] 3B and 3C are end views showing the first prism sheet of the light source unit according to the present embodiment.

[0072] As shown in FIG1 , the image display device 10 of the present embodiment includes a light source unit 11 and a reflection unit 12. The light source unit 11 includes a display device 110, an imaging optical system 120, and a first prism sheet 130. The display device 110 includes a plurality of pixels and is capable of displaying an image. Light emitted from the display device 110 is incident on the first prism sheet 130. The imaging optical system 120 is incident with light emitted from the first prism sheet 130 to form a first image IM1 corresponding to the image displayed by the display device 110. The first image IM1 is a real image and an intermediate image. The reflection unit 12 is separated from the light source unit 11 and reflects light emitted from the imaging optical system 120.

[0073] The image display device 10 is mounted on, for example, a car 1000 and constitutes a HUD (Head Up Display). The car 1000 includes a vehicle 13 and the image display device 10 fixed to the vehicle 13. The identifier 14 is a passenger of the car 1000, such as a driver.

[0074] The display device 110 of the light source unit 11 displays an image that the identifier 14 wants to recognize through the HUD. The first prism sheet 130 refracts the light emitted from each pixel of the display device 110 to enlarge the area reached by the light emitted from each pixel. This mechanism will be described later. The imaging optical system 120 outputs the light emitted from the first prism sheet 130 to the reflection unit 12, and forms a first image IM1 between the light source unit 11 and the reflection unit 12. The reflection unit 12 reflects the light emitted from the light source unit 11 toward the front windshield 13a of the vehicle 13. The front windshield 13a includes, for example, glass.

[0075] The front windshield 13a reflects the light reaching from the reflection unit 12 on its inner surface, and makes it incident on the eye movement range 14a of the identifier 14. As a result, the identifier 14 can identify the second image IM2 corresponding to the image displayed by the display device 110 on the opposite side of the front windshield 13a. The second image IM2 is a virtual image larger than the first image IM1. The "eye movement range" refers to the range in the space in front of the eyes of the identifier where the virtual image can be identified.

[0076] In order to make the description easier to understand, the configuration and structure of each part are described below using the XYZ rectangular coordinate system. In the present embodiment, the front-to-back direction of the vehicle 13 is set as the "X direction", the left-to-right direction of the vehicle 13 is set as the "Y direction", and the up-down direction of the vehicle 13 is set as the "Z direction". The XY plane is a horizontal plane of the vehicle 13. The direction of the arrow in the X direction (front) is called the "+X direction", and the opposite direction (rear) is also called the "-X direction". In addition, the direction of the arrow in the Y direction (left) is called the "+Y direction", and the opposite direction (right) is also called the "-Y direction". In addition, the direction of the arrow in the Z direction (upward) is called the "+Z direction", and the opposite direction (downward) is also called the "-Z direction".

[0077] In addition, in FIG. 1 , the position where the first image IM1 is formed is indicated by a circular mark. As with the first image IM1, the position where the second image IM2 is formed is also indicated by a circular mark. On the other hand, the position where the principal light ray L that reaches each mark of the first image IM1 in the display device 110 is emitted is indicated by a quadrilateral mark. In this way, in order to make the description easy to understand, the emission position on the display device 110 of each principal light ray L is indicated by a mark different from the imaging position of the first image IM1 and the imaging position of the second image IM2, but the image displayed on the display device 110, the first image IM1, and the second image IM2 have a roughly similar relationship.

[0078] As shown in FIG. 2 , unit areas 110u along the third direction and the fourth direction are arranged in a matrix on the display device 110, and pixels 110p are arranged in every other unit area 110u in the third direction and the fourth direction. Thus, one pixel 110p is arranged for every four unit areas 110u of 2 rows and 2 columns. In this way, in the display device 110, a plurality of pixels 110p are arranged in a staggered manner along the third direction and the fourth direction.

[0079] The fourth direction intersects, for example, is orthogonal to the third direction. For example, the third direction is the horizontal direction of the image, and the fourth direction is the vertical direction of the image. In this embodiment, the third direction is set to the X direction, and the fourth direction is set to the Y direction. The light emitted from the display device 110 has a substantially Lambertian light distribution. The specific structure of the display device 110 and the Lambertian light distribution are described in detail below.

[0080] As shown in Fig. 3A to Fig. 3C, the first prism sheet 130 has a first surface 130a for incident light emitted from the display device 110 and a second surface 130b on the opposite side of the first surface 130a. The second surface 130b emits light toward the imaging optical system 120. A strip-shaped first prism 130p1 extending in the fourth direction (Y direction) is formed on the first surface 130a of the first prism sheet 130, and a strip-shaped second prism 130p2 extending in the third direction (X direction) is formed on the second surface 130b.

[0081] When viewed from the -Z direction, the first prism sheet 130 is the same as or larger than the display device 110, and covers the display device 110. In addition, the arrangement period of the first prisms 130p1 in the X direction is shorter than the arrangement period of the unit area 110u of the display device 110 in the X direction. Similarly, the arrangement period of the second prisms 130p2 in the Y direction is shorter than the arrangement period of the unit area 110u in the Y direction. Therefore, the light emitted from each pixel 110p of the display device 110 must be incident on one or more first prisms 130p1 and one or more second prisms 130p2.

[0082] Next, the configuration other than that described above in the image display device 10 will be described.

[0083] First, the display device 110 will be described.

[0084] FIG. 4 is an end view showing the display device of the image display device according to the present embodiment.

[0085] The display device 110 of the light source unit 11 is an LED display. In the display device 110 , a plurality of LED elements 112 are arranged in a staggered manner. One or more LED elements 112 are arranged on each pixel 110 p of the display device 110 .

[0086] As shown in FIG4 , in the display device 110, each LED element 112 is mounted on the substrate 111 facing downward. However, each LED element may also be mounted on the substrate facing upward. Each LED element 112 has a semiconductor stack 112a, an anode electrode 112b, and a cathode electrode 112c. The substrate 111 uses an insulating material such as resin or glass. In addition, the substrate 111 can also use a silicon semiconductor chip for driving each LED element 112.

[0087] The semiconductor stack 112a includes a p-type semiconductor layer 112p1, an active layer 112p2 disposed on the p-type semiconductor layer 112p1, and an n-type semiconductor layer 112p3 disposed on the active layer 112p2. X Al Y Ga 1－X－YN (0≤X, 0≤Y, X+Y<1) represents a gallium nitride compound semiconductor. The light emitted by the LED element 112 is visible light in the present embodiment.

[0088] The anode electrode 112b is electrically connected to the p-type semiconductor layer 112p1. The anode electrode 112b is electrically connected to the wiring 118b. The cathode electrode 112c is electrically connected to the n-type semiconductor layer 112p3. The cathode electrode 112c is electrically connected to another wiring 118a. Each electrode 112b and 112c can be made of, for example, a metal material.

[0089] In this embodiment, a plurality of recesses 112t are provided on the light emitting surface 112s of each LED element 112. In this specification, the "light emitting surface of the LED element" refers to a surface of the surface of the LED element from which light incident on the imaging optical system 120 is mainly emitted. In this embodiment, the surface of the n-type semiconductor layer 112p3 located on the opposite side to the surface facing the active layer 112p2 corresponds to the light emitting surface 112s.

[0090] Hereinafter, the optical axis of light emitted from each pixel 110p will be referred to as "optical axis C". Optical axis C is, for example, a straight line connecting point a1 and point a2, where point a1 is a point with the highest brightness within the range irradiated by light from one pixel 110p on a first plane P1 that is parallel to the XY plane in which the plurality of pixels 110p are arranged and located on the light emitting side of the display device 110, and point a2 is a point with the highest brightness within the range irradiated by light from the pixel 110p on a second plane P2 that is parallel to the XY plane and separated from the first plane P1. When there are multiple points with the highest brightness, for example, the center point of these points may also be set as the point with the highest brightness. It should be noted that from a production point of view, it is preferred that the optical axis C is parallel to the Z axis.

[0091] Thus, by providing a plurality of recesses 112t on the light emitting surface 112s of each LED element 112, the light emitted from each LED element 112, that is, the light emitted from each pixel 110p, has a substantially Lambertian light distribution as shown by the dotted line in FIG. 4. Here, “the light emitted from each pixel has a substantially Lambertian light distribution” means that the light intensity in the direction at an angle θ relative to the optical axis C of each pixel can be reduced to cosine of the light intensity on the optical axis C when n is set to a value greater than 0. n Here, n is preferably less than 11, and more preferably 1. It should be noted that there are multiple planes containing the optical axis C of the light emitted from one pixel 110p, but the light distribution pattern of the light emitted from the pixel 110p in each plane is a roughly Lambertian light distribution, and the value of n is also roughly equal.

[0092] Next, the imaging optical system 120 will be described in detail.

[0093] As shown in FIG1 , the imaging optical system 120 of the light source unit 11 is an optical system including all optical elements required to image the first image IM1 at a predetermined position. In the present embodiment, there is an input element 121 for incident light emitted from the second surface 130b of the first prism sheet 130, an intermediate element 122 for incident light reflected by the input element 121, and an output element 123 for incident light reflected by the intermediate element 122. The light emitted from the output element 123 forms the first image IM1. It should be noted that as long as the light via the input element 121 is incident on the output element 123, the intermediate element 122 may not be provided.

[0094] The imaging optical system 120 is substantially telecentric on the side of the first image IM1. Here, “the imaging optical system 120 is substantially telecentric on the side of the first image IM1” means that, as shown in FIG1 , a plurality of principal light rays L emitted from different positions in the display device 110 and reaching the first image IM1 via the imaging optical system 120 are substantially parallel to each other in front of and behind the first image IM1. Different positions refer to, for example, different pixels 110p of the display device 110. “A plurality of principal light rays L are substantially parallel to each other” means that they are substantially parallel within a practical range that allows errors such as those caused by the manufacturing accuracy or assembly accuracy of the components of the light source unit 11. In the case of “a plurality of principal light rays L are substantially parallel to each other”, for example, the angle formed by the principal light rays L is less than 10 degrees.

[0095] When the imaging optical system 120 has a substantially telecentric property on the first image IM1 side, a plurality of principal light rays L intersect each other before entering the input element 121. Hereinafter, the point where the plurality of principal light rays L intersect each other is referred to as a "focus F". Therefore, whether the imaging optical system 120 has a substantially telecentric property on the first image IM1 side can be confirmed by the following method, for example, using the reverse travel of light. First, a light source such as a laser light source that can emit parallel light is arranged near the position where the first image IM1 is formed. The light emitted from the light source is irradiated onto the output element 123 of the imaging optical system 120. The light emitted from the light source and passing through the output element 123 is incident on the input element 121. Moreover, when there is a point of convergence, i.e., a focus F, before the light emitted from the input element 121 reaches the display device 110, it can be determined that the imaging optical system 120 has a substantially telecentric property on the first image IM1 side.

[0096] Since the imaging optical system 120 is substantially telecentric on the first image IM1 side, light that passes through the focal point F and its vicinity among the light emitted from each pixel of the display device 110 mainly enters the imaging optical system 120. Next, each optical element constituting the imaging optical system 120 will be described.

[0097] The input element 121 is located on the −Z side of the display device 110 and is disposed to face the display device 110 . The input element 121 is a reflector having a concave reflective mirror surface 121 a . The input element 121 reflects light emitted from the display device 110 .

[0098] The intermediate element 122 is located on the −X side of the display device 110 and the input element 121 and is disposed to face the input element 121 . The intermediate element 122 is a reflector having a concave reflective mirror surface 122 a . The intermediate element 122 further reflects the light reflected by the input element 121 .

[0099] The input element 121 and the intermediate element 122 constitute a curved portion 120a, and the curved portion 120a bends a plurality of principal rays L emitted from different positions of the display device 110 so as to be substantially parallel to each other. The reflective mirror surfaces 121a and 122a are biconical surfaces in this embodiment. However, the reflective mirror surface may be a part of a spherical surface or a free-form surface.

[0100] The output element 123 is located on the +X side of the display device 110 and the input element 121, and is arranged to face the intermediate element 122. The output element 123 is a reflector having a flat reflective mirror surface 123a. The output element 123 reflects the light passing through the input element 121 and the intermediate element 122 toward the formation position of the first image IM1. Specifically, a plurality of principal rays L that are substantially parallel through the curved portion 120a are incident on the output element 123. The reflective mirror surface 123a is inclined relative to the horizontal plane of the vehicle 13, that is, the XY plane, in a manner that the closer it is to the -Z direction, the closer it is to the +X direction. Thus, the output element 123 reflects the light reflected by the intermediate element 122 in a direction that is inclined relative to the Z direction in a manner that the closer it is to the -Z direction, the closer it is to the +X direction. As shown in FIG. 1 , the output element 123 constitutes a direction changing portion 120b that changes the directions of the plurality of principal rays L so that the plurality of principal rays L that are substantially parallel through the curved portion 120a are directed toward the formation position P of the first image IM1.

[0101] In the present embodiment, the optical path between the input element 121 and the intermediate element 122 extends in a direction intersecting the XY plane. In addition, the optical path between the intermediate element 122 and the output element 123 extends in a direction along the XY plane. Since a portion of the optical path in the imaging optical system 120 extends in a direction intersecting the XY plane, the light source unit 11 can be miniaturized to a certain extent in the direction along the XY plane. In addition, since another portion of the optical path in the imaging optical system 120 extends in a direction along the XY plane, the light source unit 11 can be miniaturized to a certain extent in the Z direction.

[0102] In addition, the optical path between the display device 110 and the input element 121 intersects with the optical path between the intermediate element 122 and the output element 123. Thus, by making the optical paths intersect with each other in the light source unit 11, the light source unit 11 can be miniaturized.

[0103] However, the optical paths in the light source unit are not limited to the above. For example, all optical paths in the imaging optical system may extend in the direction along the XY plane or in the direction intersecting the XY plane. In addition, the optical paths in the light source unit may not intersect with each other.

[0104] The input element 121, the intermediate element 122, and the output element 123 may also be respectively composed of a main body component made of glass or resin material, and a reflective film such as a metal film or a dielectric multilayer film provided on the surface of the main body component and constituting the reflective mirror surfaces 121a, 122a, 123a. In addition, the input element 121, the intermediate element 122, and the output element 123 may also be respectively composed of a metal material as a whole.

[0105] As shown in FIG. 1 , in the present embodiment, the light source unit 11 is disposed on the top 13b of the vehicle 13. The light source unit 11 is, for example, disposed on the inner side of a wall 13s1 exposed to the inside of the vehicle in the top 13b. A through hole 13h1 is provided on the wall 13s1 through which the light emitted from the output element 123 of the light source unit 11 can pass. The light emitted from the output element 123 passes through the through hole 13h1 and irradiates the space between the identifier 14 and the front windshield 13a. However, the light source unit may also be mounted on the top surface. A transparent or translucent cover with a small haze value may also be provided in the through hole 13h1. The haze value is preferably less than 50%, and more preferably less than 20%.

[0106] As described above, the imaging optical system 120 is described, but the structure and position of the coupling optical system are not limited to the above as long as it has a substantially telecentric property on the first image side. For example, the number of optical elements constituting the direction changing section may be two or more.

[0107] Next, the reflection unit 12 will be described.

[0108] As shown in Figure 1, in the present embodiment, the reflection unit 12 includes a reflector 131 having a concave reflector surface 131a. The reflector 131 is arranged in a manner opposite to the front windshield 13a. The reflector 131 reflects the light emitted from the output element 123 and irradiates the light to the front windshield 13a. The reflector 131 can also be composed of a main body component composed of glass or resin materials, and a reflective film such as a metal film or a dielectric multilayer film provided on the surface of the main body component and constituting the reflector surface 131a. In addition, the reflector 131 can also be composed of a metal material as a whole. In one example, the reflector surface 131a is a biconical surface. However, the reflector surface can be a part of a spherical surface or a free-form surface.

[0109] The light irradiated to the windshield 13a is reflected by the inner surface of the windshield 13a and enters the eye movement range 14a of the viewer 14. Thus, the viewer 14 views the second image IM2 corresponding to the image displayed on the display device 110 on the opposite side of the windshield 13a.

[0110] In the present embodiment, the reflection unit 12 is provided in the instrument panel portion 13c of the vehicle 13. The reflection unit 12 is, for example, arranged on the inner side of a wall 13s2 exposed inside the vehicle in the instrument panel portion 13c of the vehicle 13. The wall 13s2 is provided with a through hole 13h2 through which the light emitted from the output element 123 of the light source unit 11 can pass. After the light emitted from the output element 123 forms the first image IM1 through the through hole 13h1, it is irradiated toward the reflection unit 12 through the through hole 13h2. However, the reflection unit may also be mounted on the upper surface of the instrument panel portion. In addition, the reflection unit may be arranged on the top, and the light source unit may be arranged on the instrument panel portion.

[0111] The path of light from the inner surface of the front windshield 13a toward the eye movement range 14a is approximately horizontal, completely horizontal, or slightly inclined in a manner that the eye movement range 14a side becomes higher. That is, the path is approximately parallel to the XY plane. Moreover, in this embodiment, the light source unit 11 is arranged above (+Z direction) and the reflection unit 12 is arranged below (-Z direction) with the XY plane containing the path of the light as a reference. That is, the light source unit 11 and the reflection unit 12 are separated by the XY plane.

[0112] The above description is about the reflection unit 12, but the structure and position of the reflection unit are not limited to the above. For example, the number of optical elements such as reflectors constituting the reflection unit may be more than two. It should be noted that the reflection unit 12 needs to be configured so that, for example, sunlight irradiated from the outside of the vehicle through the front windshield 13a is not reflected toward the eye movement range 14a.

[0113] Next, the operation of the image display device 10 according to this embodiment will be described.

[0114] FIG. 5A is an optical diagram showing the function of the second prism 130p2 in this embodiment.

[0115] FIG. 5B is a diagram showing a pixel 110 p of the display device 110 .

[0116] FIG. 5C is a diagram showing a pixel enlarged by the first prism 130p1.

[0117] FIG5D is a diagram showing a pixel further enlarged by the second prism 130p2.

[0118] FIG. 6 is a schematic diagram showing a scene viewed from a viewer in a driver's seat in the present embodiment.

[0119] As shown in FIG5A , light emitted from a pixel 110p of the display device 110 is separated in the Y direction by the second prism 130p2 of the first prism sheet 130, and the area to which the light reaches expands in the Y direction. Similarly, light emitted from the pixel 110p is separated in the X direction by the first prism 130p1, and the area to which the light reaches expands in the X direction. Therefore, if the light emitted from the pixel 110p is transmitted through the first prism sheet 130, the area to which the light reaches expands in the X direction and the Y direction.

[0120] 5B shows two pixels 110p of the display device 110. As described above, the pixels 110p are separated from each other.

[0121] When the light emitted from the two pixels 110p enters the first prism 130p1 of the first prism sheet 130, it is separated in the X direction as shown in FIG5C. Therefore, when viewed from the viewer 14 side, each pixel 110p can be seen to be separated into two pixels 110p along the X direction. Hereinafter, in this specification, the situation where the light emitted from one pixel is separated by the prism and the pixel separation can be seen from the viewer 14 side is referred to as "pixel separation".

[0122] If the light expanded by the first prism 130p1 is incident on the second prism 130p2, it is separated in the Y direction as shown in FIG5D. Therefore, if observed from the identifier 14 side, it can be seen that each pixel 110p shown in FIG5C is separated into two pixels 110p along the Y direction. Therefore, the light emitted from the pixel 110p is expanded in the X direction and the Y direction by the action of the first prism 130p1 and the second prism 130p2, and the area of ​​the area reached by the light is, for example, 4 times the area of ​​the pixel 110p.

[0123] In this way, the light L is emitted from the first prism sheet 130. At this time, although the area reached by the light emitted from each pixel 110p is enlarged in the X direction and the Y direction, the positional relationship between the pixels 110p does not change, so the image displayed by the display device 110 is maintained as it is. Based on this image, the imaging optical system 120 of the light source unit 11 forms a first image IM1 as a real image at the position P. In addition, the light forming the first image IM1 is reflected by the reflection unit 12 and the front windshield 13a and enters the eye movement range 14a of the recognizer 14.

[0124] 6 , the recognizer 14 recognizes the second image IM2 as a virtual image on the opposite side of the front windshield 13a. It should be noted that in FIG6 , the second image IM2 is represented by a character string "information", but the second image IM2 is not limited to a character string and may be a video or the like.

[0125] Next, the effects of this embodiment will be described.

[0126] In this embodiment, as shown in FIG. 2 , in the display device 110, pixels 110p are arranged every other unit area 110u in the X direction and the Y direction. Thus, the display device 110 can be enlarged without increasing the number of pixels 110p, and the image displayed by the display device 110 can be enlarged. Thus, the magnification of the image, that is, the ratio of the size of the second image IM2 to the size of the image displayed by the display device 110, can be reduced, and the imaging optical system 120 can be miniaturized. As a result, by enlarging the display device 110 but miniaturizing the imaging optical system 120, the light source unit 11 can be miniaturized as a whole. Therefore, the image display device 10 can also be miniaturized.

[0127] In addition, by amplifying the light emitted from each pixel 110p of the display device 110 using the first prism sheet 130, the separation of the pixels 110p of the display device 110 is difficult to recognize in the second image IM2. As a result, even if the pixels 110p are separated from each other, the quality of the second image IM2 can be the same as that in the case where the pixels 110p are not separated from each other. It should be noted that although it is also possible to use a diffusion sheet or the like to amplify the light emitted from the pixel, by using a prism sheet as in the present embodiment, it is possible to suppress the reduction in brightness while amplifying the emitted light.

[0128] It should be noted that it is also conceivable to arrange the pixels 110 p without any gaps in a large display device 110 , but in this case, the number of LED elements 112 will increase, and the cost will increase.

[0129] In this embodiment, the following example is shown: in the display device 110, a pixel 110p is arranged in every other unit area 110u in the X direction and the Y direction, and the first prism sheet 130 makes the area where the light emitted from the pixel 110p reaches double in the X direction and the Y direction. However, it is not limited to this. For example, it is also possible that in the display device 110, a pixel 110p is arranged only in every other unit area 110u in the X direction, and the pixel 110p is arranged in all the unit areas 110u arranged continuously in the Y direction, and only the first prism 130p1 is provided on the first prism sheet 130 without providing the second prism 130p2. Similarly, it is also possible that in the display device 110, a pixel 110p is arranged only in every other unit area 110u in the Y direction, and the pixel 110p is arranged in all the unit areas 110u arranged continuously in the X direction, and only the second prism 130p2 is provided on the first prism sheet 130 without providing the first prism 130p1. Alternatively, one pixel 110 p may be arranged every two or more unit regions 110 u in the X and Y directions, and the first prism sheet 130 may triple or more the area where light emitted from the pixel 110 p reaches in the X and Y directions.

[0130] In addition, in the present embodiment, an example is shown in which the first prism 130p1 and the second prism 130p2 are provided in one first prism sheet 130, but the present invention is not limited thereto, and the first prism 130p1 and the second prism 130p2 may be provided in two separate prism sheets.

[0131] In addition, in this embodiment, since the imaging optical system 120 has a substantially telecentric property on the first image IM1 side, the light source unit 11 and the image display device 10 can be miniaturized while displaying a high-quality image. This effect will be described in detail below.

[0132] FIG. 7A is a schematic diagram illustrating the principle of the light source unit according to the present embodiment.

[0133] FIG. 7B is a schematic diagram showing the principle of a light source unit according to a reference example.

[0134] In Fig. 7A, the light distribution pattern of light emitted from two pixels 110p among the plurality of pixels 110p of the display device 110 in the present embodiment is indicated by a dotted line. Similarly, in Fig. 7B, the light distribution pattern of light emitted from two pixels 2110p among the plurality of pixels 2110p of the display device 2110 in the reference example is indicated by a dotted line. In addition, in Figs. 7A and 7B, the imaging optical systems 120 and 2120 are simplified.

[0135] As shown in FIG7B , in the light source unit 2011 of the reference example, the display device 2110 is an LCD (Liquid Crystal Display) including a plurality of pixels 2110p. As shown by the dotted line in FIG7B , the light emitted from each pixel 2110p is mainly distributed in the normal direction of the light emitting surface 2110s. In addition, there are a plurality of planes including the optical axis of the light emitted from one pixel 2110p, but in the LCD, i.e., the display device 2110, the distribution pattern of the light emitted from one pixel 2110p in each plane is different from each other. Moreover, in one of the plurality of planes, the light emitted from each pixel 2110p has a luminous intensity in a direction that makes an angle θ with respect to the optical axis and is cosine-co ... 20 The light distribution pattern is approximately theta times.

[0136] In such a display device 2110, even light emitted from the same position of the display device 2110 will have a different luminance or chromaticity depending on the viewing angle of the viewer. Therefore, if the imaging optical system 2120 takes in light emitted from each pixel 2110p in a direction other than the normal direction, even if the brightness of the light emitted from all pixels 2110p is made uniform, a deviation in brightness or chromaticity will occur in the first image IM1. That is, the quality of the first image IM1 is reduced. Therefore, in order not to reduce the quality of the first image IM1, it is necessary to take in light emitted from each pixel 2110p of the display device 2110 in the normal direction. As a result, the imaging optical system 2120 is enlarged.

[0137] In contrast, in the light source unit 11 of the present embodiment, the imaging optical system 120 has a substantially telecentric property on the side of the first image IM1, and the light emitted from the display device 110 has a substantially Lambertian distribution. Therefore, the light source unit 11 can be miniaturized while improving the quality of the first image IM1. Specifically, the display device 110 is an LED display having a plurality of LED elements 112, and by providing a recess 112t on the LED element 112, the light emitted from each LED element 112 has a substantially Lambertian distribution. Therefore, the luminance or chromaticity of the light emitted from each pixel 110p of the display device 110 has a lower dependence on the angle than the luminance or chromaticity of the light emitted from each pixel 2110p of the display device 2110 in the reference example. In particular, the closer to the strict Lambertian distribution, that is, the approximate formula of the light distribution pattern, i.e., cos n As n of θ approaches 1, the luminance or chromaticity of light emitted from each pixel 110p of the display device 110 becomes less dependent on the angle and becomes substantially uniform. Therefore, as shown in FIG7A , even if the imaging optical system 120 takes in light passing through the focal point F, that is, even if it takes in light from a direction other than the normal direction, it is possible to suppress the deviation of the brightness or chromaticity of the first image IM1 and improve the quality of the first image IM1.

[0138] In addition, the imaging optical system 120 mainly uses the light passing through the focal point F to form the first image IM1, so the expansion of the optical path of the light incident on the imaging optical system 120 can be suppressed. As a result, the input element 121 can be miniaturized. Moreover, the multiple main light rays L emitted from the output element 123 are substantially parallel to each other. The fact that the multiple main light rays L emitted from the output element 123 are substantially parallel to each other means that the range of light that is irradiated in the output element 123 and contributes to the imaging is substantially the same as the size of the first image IM1. Therefore, the output element 123 of the imaging optical system 120 can also be miniaturized. As described above, a light source unit 11 that is compact and capable of forming a high-quality first image IM1 can be provided.

[0139] In addition, the image display device 10 of the present embodiment includes a light source unit 11, and a reflection unit 12 that is separated from the light source unit 11 and reflects light emitted from the imaging optical system 120. The first image IM1 is formed between the light source unit 11 and the reflection unit 12. In this case, light emitted from a certain point of the display device 110 is focused at the formation position of the first image IM1 after passing through the output element 123. On the other hand, in the case where the first image IM1 is not formed between the light source unit 11 and the reflection unit 12, the light path of the light emitted from a certain point of the display device 110 gradually expands from the input element 121 toward the reflection unit 12. Therefore, compared with the case where the first image IM1 is not formed, in the present embodiment, the range of the light emitted from a certain point of the display device 110 in the output element 123 that is irradiated can be reduced. Therefore, the output element 123 can be miniaturized.

[0140] Furthermore, since the light source unit 11 of the present embodiment is compact, when the light source unit 11 is mounted on the vehicle 13 and used as a head-up display, the light source unit 11 can be easily disposed in a limited space in the vehicle 13 .

[0141] In addition, the imaging optical system 120 in this embodiment has a curved portion 120a and a direction changing portion 120b. Thus, in the imaging optical system 120, by separating the portion having the function of making the principal rays L parallel to each other and the portion forming the first image IM1 at a desired position, the design of the imaging optical system 120 becomes easy.

[0142] In addition, a part of the optical path in the imaging optical system 120 extends in a direction intersecting the XY plane. Therefore, the imaging optical system 120 can be miniaturized to a certain extent in the direction along the XY plane. In addition, another part of the optical path in the imaging optical system 120 extends in a direction along the XY plane. Therefore, the imaging optical system 120 can be miniaturized to a certain extent in the Z direction.

[0143] <Example>

[0144] Next, light source units according to the embodiment and reference examples are described.

[0145] FIG. 8A is a graph showing light distribution patterns of light emitted from one light emitting region in Examples 1, 11, and the reference example.

[0146] FIG. 8B is a graph showing the uniformity of brightness of the second image in Examples 1 to 12 and the reference example.

[0147] The image display devices of Examples 1 to 12 and the reference example include a light source unit and a reflection unit, and the light source unit is set on the simulation software to include a plurality of light emitting regions arranged in a matrix and an imaging optical system. Each light emitting region corresponds to each pixel 110p of the display device 110 in the above embodiment.

[0148] In FIG8A, the horizontal axis is the angle of the light-emitting region relative to the optical axis, and the vertical axis is the luminance normalized by dividing the luminance at the angle by the luminance on the optical axis. As for the display device of Example 1, as shown in FIG8A, the light emitted from each light-emitting region is set on the simulation software in such a manner that the luminance in the direction forming an angle θ relative to the optical axis is expressed as cosθ times the luminance on the optical axis. That is, in Example 1, the light emitted from each light-emitting region has a strict Lambertian luminance distribution.

[0149] In Examples 2 to 12, the light emitted from each light emitting region has a luminous intensity in a direction that makes an angle θ with respect to the optical axis and a cosine of the luminous intensity on the optical axis. n The light distribution pattern represented by θ times is set on the simulation software. It should be noted that in Example 2, n=2, and n is set to be gradually increased from Example 2 to Example 12.

[0150] In addition, the light distribution pattern of the light emitted from the pixels of the LCD in one plane is investigated, and it is found that it is a light distribution pattern as shown by the thin dotted line in FIG. 8A. And, as mentioned above, it is found that the light distribution pattern can be adjusted by the cosine of the light intensity on the optical axis with respect to the light intensity in the direction forming an angle θ with respect to the optical axis. 20 Therefore, in the reference example, the luminous intensity in the direction having an angle θ with respect to the optical axis of each light emitting region is calculated by cosine of the luminous intensity on the optical axis. 20 The method of expressing the light distribution pattern in θ-fold is set on the simulation software.

[0151] It is assumed that the imaging optical systems in Examples 1 to 12 and the reference example all have telecentricity on the first image side.

[0152] Next, for each of Examples 1 to 12 and the reference example, the brightness distribution of the second image formed when the brightness of the entire light-emitting area is kept constant was simulated. At this time, the second image is a rectangle with a long side of 111.2 mm and a short side of 27.8 mm. In addition, at this time, the plane forming the second image is divided into square areas with a side of 1 mm, and the brightness value of each area is simulated.

[0153] In addition, the uniformity of the brightness of the second image at this time was evaluated. Here, "uniformity of brightness" refers to a value expressing the ratio of the minimum brightness value to the maximum brightness value in the second image in percentage. The results are shown in FIG8B. It should be noted that in FIG8B, the horizontal axis is each embodiment and reference example, and the vertical axis is the uniformity of brightness.

[0154] As shown in FIG8B , it can be seen that the larger n is, the lower the uniformity of brightness is. This is because the larger n is, the lower the brightness is at the position far from the center in the second image. In particular, it can be seen that in Example 11, that is, when n=11, the uniformity of brightness is 30%. Because it is easy for the viewer to distinguish the second image and the area where the second image is not formed, it is also considered that the uniformity of brightness of the second image only needs to be 30% or more.

[0155] Therefore, it can be seen that when the imaging optical system is configured to have a substantially telecentric property, in order to suppress the uneven brightness of the first image and the second image, it is preferable that the light emitted from the display device has a substantially Lambertian light distribution. Specifically, it can be seen that the approximate formula of the light distribution pattern, i.e., cos n The value n of θ is preferably less than 11, and more preferably 1. It should be noted that, as described above, the uniformity of the brightness of the second image IM2 decreases as n moves away from 1, but a predetermined brightness distribution can be set in advance for the display brightness of the display device 110 to compensate for such brightness non-uniformity. For example, since the light emitted from each pixel 110p of the display device 110 passes through the imaging optical system 120, when the brightness of the outer edge of the second image IM2 is likely to be lower than that of the center, the display device 110 can also be controlled so that the output of the LED element 112 of the pixel 110p on the outer edge side of the display device 110 is greater than the output of the LED element 112 of the pixel 110p on the center side.

[0156] <Second embodiment>

[0157] Next, a second embodiment will be described.

[0158] FIG. 9 is a plan view showing the display device in this embodiment.

[0159] FIG. 10A is a plan view showing a prism sheet in this embodiment.

[0160] FIG. 10B is an end view taken along the line XB-XB shown in FIG. 10A .

[0161] FIG. 11 is a plan view showing a display device and a prism sheet in this embodiment.

[0162] As shown in Fig. 9, in the display device 210 of the present embodiment, the pixels 210p are arranged in a matrix along the third direction (X direction) and the fourth direction (Y direction). That is, in the first embodiment, as shown in Fig. 2, the pixels 110p are arranged for every four unit areas 110u, but in the present embodiment, the pixels 210p are arranged in all the unit areas.

[0163] As shown in FIG. 10A and FIG. 10B , the first prism sheet 230 of the present embodiment has a first surface 230a for incident light emitted from the display device 210 and a second surface 230b for emitting light toward the input element 121. A strip-shaped first prism 230p1 extending in a first direction is formed on the first surface 230a. No prism is formed on the second surface 230b, which is flat. The first direction is a direction inclined 45 degrees relative to the third direction. In addition, the arrangement direction of the first prism 230p1 is set to the second direction. The second direction is a direction inclined 45 degrees relative to the fourth direction.

[0164] As shown in FIG. 10A, FIG. 10B and FIG. 11, in the present embodiment, the third direction of the display device 210 in which the pixels 210p are arranged is the X direction, and the fourth direction in which the pixels 210p are arranged is the Y direction. Moreover, the first direction in which the first prism 230p1 of the first prism sheet 230 extends is represented as the V direction, and the second direction in which a plurality of first prisms 230p1 are arranged is represented as the W direction. The angle formed by the V direction and the W direction is 90 degrees, and the V direction and the W direction are orthogonal to the Z direction. Therefore, the X direction (third direction), the Y direction (fourth direction), the U direction (first direction), and the V direction (second direction) are parallel to the second surface 230b of the first prism sheet 230. In addition, as shown in FIG. 11, the arrangement period of the first prism 230p1 is shorter than the arrangement period of the pixels 210p.

[0165] Next, the operation of this embodiment will be described.

[0166] FIG. 12A is a diagram showing a state in which some pixels 210 p in the display device 210 are lit.

[0167] FIG. 12B is a diagram showing a pixel enlarged by the first prism 230p1.

[0168] As shown in Fig. 12A, the display device 210 selectively lights up the pixels 210p. In the example shown in Fig. 12A, four pixels 210p are lit, and the other pixels 210p are turned off.

[0169] As shown in FIG12B , if the light emitted from each pixel 210p is incident on the first prism 230p1 of the first prism sheet 230, the light is separated along the W direction. Thus, when observed from the side of the identifier 14, it can be seen that each pixel 210p is separated into two in the W direction. However, in the present embodiment, the two separated pixels 210p are not separated from each other, and a part of them overlap each other. The area where the two pixels 210p overlap is relatively brightened. There is a relatively dark area around the bright area where only one pixel 210p is configured. Thus, the light emitted from each pixel 210p is diffused along the W direction in a manner having a peak. As a result, the image displayed by the display device 210 becomes smooth.

[0170] Next, the relationship between the dimensions of the various components of the light source unit 11 will be described.

[0171] FIG. 13A is an end view showing the display device 210 and the first prism sheet 230 according to the present embodiment.

[0172] FIG. 13B is an optical diagram showing the first prism 230p1 according to this embodiment.

[0173] FIG13C is a mathematical formula showing the relationship among the distance D, the prism angle θp, the refractive indices n0 and n1, and the pixel shift amount y.

[0174] 13D is a graph showing the relationship between the distance D required to obtain a desired pixel shift amount y and the prism angle θp, with the horizontal axis representing the pixel shift amount y and the vertical axis representing the prism angle θp.

[0175] 13A , the distance between the display device 210 and the first prism sheet 230 is set to D. The arrangement period (pixel pitch) of the pixels 210 p in the display device 210 is set to Pa. The arrangement period (prism pitch) of the first prisms 230 p 1 in the first prism sheet 230 is set to P2.

[0176] As shown in FIG13B , the angle formed by the surface of the first prism 230p1 and the second surface 230b is set to the prism angle θp. The vertex angle of the first prism 230p1 is (180-2θp) degrees. The prism angle θp is greater than 0 degrees and less than 45 degrees, preferably greater than 1 degree and less than 40 degrees. Therefore, the vertex angle of the first prism 230p1 is greater than 90 degrees and less than 180 degrees, preferably greater than 100 degrees and less than 178 degrees. In addition, the refractive index of the first prism sheet 230 is set to n1, the refractive index of the environment in which the first prism sheet 230 is placed, such as the atmosphere, is set to n0, and the amount by which the pixel 210p is to be displaced (pixel displacement amount) is set to y.

[0177] In order to miniaturize the light source unit 11, it is preferred that the distance D is short. However, if the distance D is too short, the proportion of light totally reflected by the surface of the first prism 230p1 increases, and the light utilization efficiency decreases. In order to suppress total reflection, it is sufficient to reduce the prism angle θp, but if the prism angle θp is reduced, it is difficult to obtain the pixel displacement amount y. In other words, for the desired pixel displacement amount y, there is a trade-off relationship between shortening the distance D and reducing the prism angle θp.

[0178] The pixel displacement y can be expressed as a function of the distance D, the prism angle θp, and the refractive indexes n0 and n1 as shown in equation (1) shown in Fig. 13C. If equation (1) is plotted against some distances D and refractive indexes n0 and n1, it is as shown in Fig. 13D.

[0179] As shown in FIG13D , in order to increase the pixel displacement y, it is necessary to extend the distance D or increase the prism angle θp. For example, when the pixel pitch Pa is 0.1 mm, if the area to be illuminated is to be displaced by half the pixel pitch Pa, the pixel displacement y is 0.05 mm. In this case, if the distance D is 1.50 mm, the prism angle θp is about 4 degrees, and if the distance D is 0.50 mm, the prism angle θp is about 11 degrees.

[0180] The ratio of the prism pitch Pb to the distance D is preferably 10% or less, more preferably 7.5% or less, more preferably 5% or less, and more preferably 2.5% or less.

[0181] 14A and 14B are diagrams showing distribution of light transmitted through the first prism sheet 230 . FIG. 14A shows a case where the ratio (Pb / D) of the prism pitch Pb to the distance D is 1.5%, and FIG. 14B shows a case where the ratio (Pb / D) is 5.0%.

[0182] As shown in FIG14A , when the ratio (Pb / D) is 1.5%, the prism pitch Pb is hardly reflected in the distribution of light transmitted through the first prism sheet 230, and as shown in FIG14B , when the ratio (Pb / D) is 5.0%, the prism pitch Pb is clearly reflected in the distribution of light transmitted through the first prism sheet 230. Therefore, the smaller the ratio (Pb / D) is, the better the quality of the image after transmitting through the first prism sheet 230.

[0183] Next, the effects of this embodiment will be described.

[0184] According to this embodiment, the image can be smoothed by separating the light emitted from each pixel 210p of the display device 210 into two pixels partially overlapping each other by the first prism 230p1. The structure, operation and effects other than the above in this embodiment are the same as those in the first embodiment.

[0185] <Third embodiment>

[0186] Next, a third embodiment will be described.

[0187] FIG. 15 is a plan view showing the first prism sheet 330 according to the present embodiment.

[0188] As shown in FIG. 15 , in this embodiment, a first prism sheet 330 is provided instead of the first prism sheet 230 in the second embodiment.

[0189] The first prism sheet 330 has a first surface 330a for incident light emitted from the display device 210 and a second surface 330b for emitting light toward the input element 121. A strip-shaped first prism 330p1 extending in a first direction (V direction) is formed on the first surface 330a. A strip-shaped second prism 330p2 extending in a second direction (W direction) is formed on the second surface 330b. The first direction (V direction) is inclined 45 degrees relative to the third direction (X direction), and the second direction (W direction) is inclined 45 degrees relative to the fourth direction (Y direction). Therefore, the second direction (W direction) is orthogonal to the first direction (V direction).

[0190] Next, the operation of this embodiment will be described.

[0191] FIG. 16A is a diagram showing one pixel 210 p in this embodiment.

[0192] FIG. 16B is a diagram showing a pixel enlarged by the first prism 330p1.

[0193] FIG. 16C is a diagram showing a pixel further enlarged by the second prism 330p2.

[0194] FIG. 17A is a diagram showing an image displayed on the display device 210 in this embodiment.

[0195] FIG. 17B is a diagram showing an image magnified by the first prism 330p1.

[0196] FIG. 17C is a diagram showing an image further enlarged by the second prism 330p2.

[0197] First, one pixel will be described.

[0198] As shown in FIG. 16A , one pixel 210 p of the display device 210 is lit.

[0199] As shown in FIG16B , when the light emitted from the pixel 210 p enters the first prism 330 p 1 , it is separated into two pixels 210 p along the direction W. At this time, the two pixels 210 p are separated so that they partially overlap each other. For example, the two pixels 210 p are displaced by 0.5 pixels.

[0200] As shown in FIG16C , the two pixels 210p separated by the first prism 330p1 are further separated into two pixels 210p by the second prism 330p2 along the V direction. The pixel displacement at this time is also the amount of the degree to which parts of the two pixels 210p overlap each other, for example, 0.5 pixels. Thus, the light emitted from one pixel 210p is amplified in the area where four pixels 210p overlap.

[0201] Next, the entire image will be described.

[0202] As shown in FIG. 17A , the display device 210 displays a certain image G1 .

[0203] 17B , the light emitted from the plurality of pixels 210p constituting the image G1 is separated by the first prism 330p1 by, for example, 0.5 pixels in the direction W. Thus, two images G1 of the same shape are shifted by 0.5 pixels and a superimposed image G2 is synthesized.

[0204] As shown in FIG17C , the light separated by the first prism 330p1 is separated by the second prism 330p2 by, for example, 0.5 pixels along the V direction. As a result, two images G2 of the same shape are offset by 0.5 pixels to form an overlapping image G3. Image G3 is an image in which four images G1 overlap. As a result, the image G1 displayed by the display device 210 becomes smooth by passing through the first prism sheet 330.

[0205] Next, the effects of this embodiment will be described.

[0206] In this embodiment, since the first prism 330p1 is provided on the first surface 330a of the first prism sheet 330, and the second prism 330p2 is provided on the second surface, the image is separated along the two directions of the W direction and the V direction. As a result, the image becomes smoother than in the second embodiment. The structures, actions and effects other than the above in this embodiment are the same as those in the second embodiment.

[0207] <Fourth embodiment>

[0208] Next, a fourth embodiment will be described.

[0209] FIG. 18A is a side view showing the display device 210 , the first prism sheet 431 , and the second prism sheet 432 of the light source unit according to the present embodiment.

[0210] FIG. 18B is a plan view showing the first prism sheet 431 according to this embodiment.

[0211] FIG. 18C is a plan view showing the second prism sheet 432 according to this embodiment.

[0212] 18A to 18C , the present embodiment is different from the third embodiment in that the first prism 330p1 and the second prism 330p2 are configured as two prism sheets. The light source unit of the present embodiment is provided with a first prism sheet 431 and a second prism sheet 432 , and the second prism sheet 432 is configured between the first prism sheet 431 and the input element 121 .

[0213] Furthermore, the first prism 330p1 is disposed on the first surface 431a of the first prism sheet 431, and the second prism 330p2 is disposed on the first surface 432a of the second prism sheet 432. The first prism 330p1 extends in a strip shape along the first direction (V direction), and the second prism 330p2 extends in a strip shape along the second direction (W direction). The first surface 431a of the first prism sheet 431 and the first surface 432a of the second prism sheet 432 are surfaces facing the display device 210.

[0214] It should be noted that the first prism 330p1 may be disposed on the second surface 431b of the first prism sheet 431, and the second prism 330c2 may be disposed on the second surface 432b of the second prism sheet 432. The second surface 431b of the first prism sheet 431 and the second surface 432b of the second prism sheet 432 are surfaces facing the input element 121.

[0215] As in the third embodiment, this embodiment can also make the image displayed by the display device 210 smooth. The structure, operation, and effects other than those described above in this embodiment are the same as those in the third embodiment.

[0216] <Fifth embodiment>

[0217] Next, a fifth embodiment will be described.

[0218] 19 is a side view showing the display device 210 , the first prism sheet 531 , the second prism sheet 532 , and the third prism sheet 533 of the light source unit according to the present embodiment.

[0219] FIG. 20A is a plan view showing the first prism sheet 531 according to this embodiment.

[0220] FIG. 20B is a plan view showing the second prism sheet 532 according to this embodiment.

[0221] FIG. 20C is a plan view showing the third prism sheet 533 according to the present embodiment.

[0222] 19 , in this embodiment, three prism sheets are provided between the display device 210 and the input element 121. That is, a first prism sheet 531, a second prism sheet 532, and a third prism sheet 533 are sequentially arranged in the direction from the display device 210 toward the input element 121.

[0223] Moreover, a first prism 531p is formed on the first prism sheet 531, a second prism 532p is formed on the second prism sheet 532, and a third prism 533p is formed on the third prism sheet 533. The first prism 531p, the second prism 532p, and the third prism 533p are all strip-shaped, forming an angle of 120 degrees with each other. It should be noted that each prism can also be formed on any surface of each prism sheet. In addition, two prisms can also be formed on both surfaces of a prism sheet.

[0224] Next, the operation of this embodiment will be described.

[0225] 21A to 21D are schematic diagrams showing the operation of this embodiment.

[0226] As shown in FIG. 21A , one pixel 210 p is lit.

[0227] As indicated by arrow E1 in FIG. 21B , light emitted from the pixel 210 p is split by the first prism 531 p and is separated into two pixels 210 p .

[0228] As indicated by arrow E2 in FIG. 21C , the two pixels 210 p are separated into two by the second prism 532 p , and are separated into four pixels 210 p .

[0229] As shown by arrow E3 in Fig. 21D, the four pixels 210p are further separated into two by the third prism 533p. However, at this time, the two pixels 210p overlap at one place, so there are finally seven pixels 210p. Thus, the light emitted from one pixel 210p is separated into seven pixels 210p.

[0230] Thus, according to this embodiment, the light emitted from the pixel can be amplified in three directions forming an angle of 120 degrees with each other, and the image can be made smoother. The structure, operation and effect of this embodiment other than the above are the same as those of the fourth embodiment.

[0231] <Sixth embodiment>

[0232] Next, a sixth embodiment will be described.

[0233] FIG. 22 is a perspective view showing a first prism sheet according to the present embodiment.

[0234] As shown in FIG. 22 , in the present embodiment, a first prism sheet 630 is provided. A first prism 630p is formed in the first prism sheet 630. The first prism 630p is not in a strip shape, but is, for example, a convex portion. A plurality of first prisms 630p are arranged in a matrix along a first direction (V direction) and a second direction (W direction). In the example shown in FIG. 22 , the shape of the first prism 630p is a pyramid shape (a quadrangular pyramid shape). However, the shape of the first prism 630p is not limited thereto, and may be, for example, a cone shape or a hexagonal pyramid shape. The first prism 630p may also be a concave portion.

[0235] Furthermore, the arrangement direction of the first prisms 630p is not limited to the V direction and the W direction, but may be the same as the X direction and the Y direction, that is, the arrangement direction of the pixels of the display device. The structure, operation and effect other than the above in this embodiment are the same as those in the third embodiment.

[0236] <Seventh embodiment>

[0237] Next, a seventh embodiment will be described.

[0238] FIG. 23 is an end view showing the image display device according to the present embodiment.

[0239] FIG. 24 is a schematic diagram showing a scene viewed from a viewer in a driver's seat in the present embodiment.

[0240] As shown in Fig. 23, the automobile 1000 of the present embodiment includes a vehicle 13 and an image display device 20 fixed to the vehicle 13. The image display device 20 includes a light source unit 11 and a reflection unit 22. The image display device 20 of the present embodiment is different from the image display device 10 of the first embodiment in that a reflection mirror surface 322a of a reflection mirror 322 of the reflection unit 22 also serves as a reflection surface for allowing the identifier 14 to recognize the second image IM2.

[0241] The structure of the light source unit 11 in the image display device 20 is the same as that of the first embodiment. The light source unit 11 is arranged on the top 13b of the vehicle 13. The reflection unit 22 is arranged on the dashboard portion 13c of the vehicle 13. The reflection unit 22 has a reflector 322. The reflector surface 322a of the reflector 322 is, for example, a concave surface. When the identifier 14 is located in the driver's seat of the vehicle 13, the reflector surface 322a is arranged at a position and angle opposite to the eye movement range 14a of the identifier 14. For example, the reflector surface 322a faces a direction between the -X direction (rearward) and the +Z direction (upward). The angle of the reflector surface 322a can be finely adjusted according to the position of the eye movement range 14a of the identifier 14.

[0242] Next, the operation of this embodiment will be described.

[0243] The principal light ray L emitted from the light source unit 11 travels in a direction between the +X direction (forward) and the -Z direction (downward), is reflected by the reflective mirror surface 322a of the reflective mirror 322 of the reflective unit 22, and travels in a direction between the -X direction (backward) and the +Z direction (upward), and enters the eye movement range 14a of the identifier 14. The path of the principal light ray L from the light source unit 11 toward the reflective unit 12 is located on the inner side of the front windshield 13a of the vehicle 13, and is roughly along the front windshield 13a. The principal light ray L forms a first image IM1 at a position P between the light source unit 11 and the reflective unit 22. At this time, due to the action of the first prism sheet 130, the first image IM1 becomes smooth.

[0244] Thus, as shown in Figures 23 and 24, the recognizer 14 can recognize the second image IM2 as a virtual image on the back side of the reflective mirror surface 322a of the instrument panel portion 13c. The second image IM2 is formed at a distance of the reflective mirror surface 322a, for example, 3m in front. Therefore, the recognizer 14 can see the second image IM2 without significantly changing the focal length of the eye from the state of observing the distant scenery through the front windshield 13a.

[0245] Next, the effects of this embodiment will be described.

[0246] As in the first embodiment, the image display device 20 of this embodiment is divided into the light source unit 11 and the reflection unit 22 and fixed to another position in the vehicle 13. The image display device 20 requires a long optical path in order to image the second image IM2 at a position several meters ahead, but by configuring the light source unit 11 and the reflection unit 22 separately, a part of the optical path can be formed by using the internal space of the vehicle 13. As a result, it is not necessary to form the entire required optical path inside the image display device 20, and the image display device 20 can be miniaturized.

[0247] In the image display device 20, only the reflecting mirror 322 is provided in the reflecting unit 22. Thus, the structure of the reflecting unit 22 can be simplified, and the reflecting unit 22 can be miniaturized.

[0248] Furthermore, by using the reflective mirror surface 322a disposed on the instrument panel portion 13c as a reflective surface, the viewer 14 can reliably view the second image IM2 without being affected by the background of the reflective surface. The configuration, operation, and effects other than those described above in this embodiment are the same as those of the first embodiment.

[0249] It should be noted that the reflector 322 of the reflection unit 22 may also be composed of a half mirror or a transparent plate. In this case, if the interior of the instrument panel portion 13c is darkened, it is also possible to prevent the identifier 14 from seeing the interior of the instrument panel portion 13c. Alternatively, the reflector surface 322a of the reflector 322 may also be black to the extent that it fully reflects the main light L emitted from the light source unit 11. Thus, it is possible to prevent the reduction in visibility caused by external light or the like being reflected by the reflector surface 322a of the reflector 322. In addition, the reflector 322 may also be arranged continuously with the surface of the instrument panel portion 13c. Thus, there is no need to open a hole in the instrument panel portion 13c, and the design of the interior of the automobile 1000 is improved.

[0250] <Eighth Embodiment>

[0251] Next, an eighth embodiment will be described.

[0252] FIG. 25 is an end view showing the image display device according to the present embodiment.

[0253] FIG. 26 is a cross-sectional view showing, in an enlarged manner, a portion of the display device and the reflective polarization element shown in FIG. 25 .

[0254] As shown in FIG. 25 and FIG. 26 , the image display device 70A of this embodiment is different from the image display device 10 of the first embodiment in that it is provided with a display device 710A instead of the display device 110 and is also provided with a reflective polarization element 740. The display device 710A of this embodiment is different from the display device 110 of the first embodiment in that the light emitting surface of the LED element 712 is substantially flat and is also provided with a protective layer 714, a wavelength conversion component 715 and a light scattering component 716A. The other structures of the display device 710A are the same as those of the display device 110 of the first embodiment. In addition, like the light source unit 11 of the first embodiment, the light source unit 71A of this embodiment has a first prism sheet 130. However, the illustration of the first prism sheet 130 is omitted in FIG. 25 .

[0255] The protective layer 714 covers the plurality of LED elements 712 arranged in a matrix. The protective layer 714 can be made of a light-transmitting material such as a polymer material having a substituent containing sulfur (S) or a group containing a phosphorus (P) atom, or a high-refractive-index nanocomposite material having inorganic nanoparticles with a high refractive index introduced into a polymer matrix such as polyimide.

[0256] The wavelength conversion component 715 is disposed on the protective layer 714. The wavelength conversion component 715 includes one or more wavelength conversion materials such as general phosphor materials, perovskite phosphor materials, or quantum dots (Quantum Dot: QD). The light emitted from each LED element 712 is incident on the wavelength conversion component 715. The wavelength conversion material included in the wavelength conversion component 715 emits light of a peak emission wavelength different from the peak emission wavelength of each LED element 712 by allowing the light emitted from each LED element 712 to be incident. The light emitted by the wavelength conversion component 715 has a substantially Lambertian light distribution.

[0257] The light scattering component 716A includes, for example, a resin component having light transmittance and light scattering particles or pores disposed in the resin component. As the resin component, for example, polycarbonate can be cited. As the light scattering particles, for example, materials having a refractive index difference with the resin component such as titanium oxide can be cited. It should be noted that the light scattering component 716A can also obtain a light scattering effect by roughening its surface and providing concavoconvexity.

[0258] As the reflective polarizing element 740, for example, a multi-layer thin film laminated polarizing plate in which thin film layers having different polarization characteristics are laminated can be used. The reflective polarizing element 740 is disposed on the display device 710A. In the present embodiment, the reflective polarizing element 740 is disposed on the light scattering component 716A. Therefore, the light emitted from the LED element 712 and the wavelength conversion component 715 is incident on the reflective polarizing element 740. The reflective polarizing element 740 transmits the first polarized light 710p of the light emitted from the display device 710A, and reflects the second polarized light 710s toward the display device 710A. The vibration direction of the electric field of the second polarized light 710s is substantially orthogonal to the vibration direction of the electric field of the first polarized light 710p.

[0259] In this embodiment, the first polarized light 710p is P polarized light, and the second polarized light 710s is S polarized light. Here, "P polarized light" refers to light whose electric field vibration direction is substantially parallel to the XY plane. In addition, "S polarized light" refers to light whose electric field vibration direction is substantially perpendicular to the XY plane containing the incident light and the reflected light.

[0260] In order to reduce the glare of sunlight or the like reflected by the accumulated water or the like in front of the vehicle 13 and transmitted through the front windshield 13a, the identifier 14 who is driving the vehicle 13 may sometimes wear polarized sunglasses 14b. In this case, since the component of the sunlight or the like reflected by the accumulated water or the like that is equivalent to the P polarized light seen from the front windshield 13a during reflection is particularly small, the polarized sunglasses 14b are designed to block most of the S polarized light. Therefore, when the identifier 14 wears the polarized sunglasses 14b, most of the S polarized light contained in the light emitted by the display device 710A will also be blocked by the polarized sunglasses 14b, and the identifier 14 may have difficulty in identifying the second image IM2. It should be noted that the P polarized light and the S polarized light in this specification are physically defined by the presence of the above-mentioned reflective objects such as accumulated water.

[0261] In this embodiment, the reflective polarizing element 740 transmits the first polarized light 710p of the light emitted from the display device 710A, and reflects the second polarized light 710s. Most of the first polarized light 710p transmitted through the reflective polarizing element 740 is not blocked by the polarized sunglasses 14b and enters the eye movement range 14a after passing through the imaging optical system 120, the reflection unit 12 and the inner surface of the front windshield 13a. It should be noted that the incident angle of the first polarized light 710p when entering the inner surface of the front windshield 13a is set to an angle different from the Brewster angle.

[0262] Specifically, as shown in FIG. 26 , the light emitted from the LED element 712 is irradiated toward the wavelength conversion component 715. As a result, the wavelength conversion component 715 is excited to emit light having a peak wavelength longer than the peak wavelength of the light emitted from the LED element 712. In the present embodiment, the light emitted from the display device 710A includes the light emitted from the LED element 712 and the light emitted from the wavelength conversion component 715. Hereinafter, the light emitted from the LED element 712 among the light emitted from the display device 710A is referred to as “short wavelength light”, and the light emitted from the wavelength conversion component 715 is also referred to as “long wavelength light”. However, most of the light emitted from the LED element 712 may also be absorbed by the wavelength conversion component 715.

[0263] Most of the first polarized light 710p included in these short-wavelength light and long-wavelength light is transmitted through the reflective polarization element 740 and emitted from the imaging optical system 120. In addition, most of the second polarized light 710s included in these short-wavelength light and long-wavelength light is reflected by the reflective polarization element 740. A part of the second polarized light 710s reflected by the reflective polarization element 740 is scattered and reflected in the components of the display device 710A such as the light scattering component 716A or the wavelength conversion component 715. Through scattered reflection, a part of the second polarized light 710s is converted into the first polarized light 710p. A part of the first polarized light 710p converted from the second polarized light 710s is transmitted through the reflective polarization element 740 and emitted from the light source unit 71A. Therefore, it is possible to increase the ratio of the first polarized light 710p included in the light emitted from the light source unit 71A, and at the same time increase the brightness of the first image IM1. Since the brightness of the first image IM1 is increased, the brightness of the second image IM2 is also increased. As a result, the recognizer 14 can easily recognize the second image IM2.

[0264] In addition, a portion of the short-wavelength light included in the second polarized light 710s may also be incident on the wavelength conversion component 715 after being reflected by the reflective polarization element 740. In this case, it is expected that the wavelength conversion component 715 absorbs the short-wavelength light of the second polarized light 710s and re-emits the long-wavelength light. These scattered reflected light and emitted light both have a roughly Lambertian light distribution. In addition, the reflective polarization element 740 itself may also scatter and reflect the second polarized light 710s. In this case, by scattering and reflecting, a portion of the second polarized light 710s is also converted into the first polarized light 710p.

[0265] In the present embodiment, one reflective polarizing element 740 covers all pixels of the display device 710A. However, it is also possible that the light source unit has a plurality of reflective polarizing elements, each of which is disposed on each pixel. In addition, the structure of the display device used in combination with the reflective polarizing element is not limited to the above. For example, by using the scattering reflection effect of light possessed by the wavelength conversion component, the display device may be set to a structure in which a light scattering component is not provided. In addition, by using the scattering reflection effect of the light scattering component, the display device may be set to a structure in which a wavelength conversion component is not provided. In addition, as in the first embodiment, by using the scattering reflection effect of light realized by a plurality of concave portions or a plurality of convex portions provided on the light emitting surface of the LED element, the display device may be set to a structure in which neither a wavelength conversion component nor a light scattering component is provided.

[0266] Next, the effects of this embodiment will be described.

[0267] The light source unit 71A of this embodiment further includes a reflective polarizing element 740, which is disposed on the display device 710A and transmits the first polarized light 710p in the light emitted from the display device 710A and reflects the second polarized light 710s in the light emitted from the display device 710A. Therefore, the ratio of the first polarized light 710p included in the light emitted from the light source unit 71A can be increased, and the brightness of the first image IM1 can be increased.

[0268] In addition, the light emitted from the reflective polarizing element 740 also has a roughly Lambertian light distribution. Therefore, in this embodiment, a light source unit 71A that is small and can form a high-quality first image IM1 can also be provided. It should be noted that because the plurality of LED elements 712 are discretely mounted on the substrate 111, the first image IM1 sometimes has a granular feel. The wavelength conversion component 715 has the effect of alleviating the granular feel. Moreover, the light scattering component 716A can further enhance the effect of alleviating the granular feel. The structures, actions, and effects other than those described above in this embodiment are the same as those in the first embodiment.

[0269] <Ninth embodiment>

[0270] Next, a ninth embodiment will be described.

[0271] FIG. 27 is a side view showing a light source unit according to the present embodiment.

[0272] As shown in FIG27 , the image display device 70B of this embodiment is different from the image display device 10 of the first embodiment in that the light source unit 71B includes a display device 710A having the same structure as that of the eighth embodiment instead of the display device 110, and further includes a reflective polarizing element 750 and a light shielding member 760. It should be noted that FIG27 shows only the light shielding member 760 in cross section.

[0273] The reflective polarization element 750 can be, for example, a wire grid type reflective polarization element using a plurality of metal nanowires. The reflective polarization element 750 is disposed at a portion where a plurality of principal light rays L are substantially parallel to each other in the optical path from the display device 710A to the reflective unit 12. In the present embodiment, the plurality of principal light rays L are substantially parallel to each other in the optical path from the intermediate element 122 to the reflective unit 12, and the reflective polarization element 750 is disposed between the intermediate element 122 and the output element 123.

[0274] The reflective polarizing element 750 transmits the first polarized light 710p, which is the P polarized light, and reflects the second polarized light 710s, which is the S polarized light, to return it to the display device 710A. Specifically, the light 710a including the first polarized light 710p and the second polarized light 710s is emitted from the display device 710A. The light 710a enters the reflective polarizing element 750 after passing through the input element 121 and the intermediate element 122.

[0275] The reflective polarization element 750 transmits most of the first polarized light 710 p included in the light 710 a . Most of the first polarized light 710 p that has passed through the reflective polarization element 750 passes through the output element 123 and then is emitted from the reflection unit 12 .

[0276] The reflective polarizing element 750 reflects most of the second polarized light 710s included in the light 710a so as to return the light path from the display device 710A to the reflective polarizing element 750. Specifically, the reflective polarizing element 750 is in the shape of a flat plate. The reflective polarizing element 750 is arranged to be substantially orthogonal to the principal light ray L. The reflective polarizing element 750 performs regular reflection on most of the second polarized light 710s. Therefore, most of the second polarized light 710s reflected by the reflective polarizing element 750 returns to the display device 710A after passing through the intermediate element 122 and the input element 121 in sequence.

[0277] A portion of the second polarized light 710s returned to the display device 710A is scattered and reflected by components of the display device 710A such as the light scattering component 716A or the wavelength conversion component 715. Through scattered reflection, a portion of the second polarized light 710s is converted into the first polarized light 710p. A portion of the first polarized light 710p converted from the second polarized light 710s passes through the reflective polarization element 750 after passing through the input element 121 and the intermediate element 122. Most of the first polarized light 710p that has passed through the reflective polarization element 750 passes through the output element 123 and is emitted from the reflection unit 12. Therefore, it is possible to increase the ratio of the first polarized light 710p contained in the light emitted from the image display device 70B, and at the same time increase the brightness of the second image IM2. As a result, the recognizer 14 can easily recognize the second image IM2.

[0278] In addition, similarly to the eighth embodiment, a portion of the short-wavelength light included in the second polarized light 710s returned to the display device 710A may be irradiated to the wavelength conversion member 715. In this case, similarly to the eighth embodiment, the effect of the wavelength conversion member 715 absorbing the short-wavelength light of the second polarized light 710s and re-emitting the long-wavelength light can be expected.

[0279] The light shielding member 760 is disposed between the display device 710A and the input element 121 of the imaging optical system 120. The shape of the light shielding member 760 is, for example, a flat plate substantially parallel to the XY plane. The light shielding member 760 is provided with an opening 761 that penetrates the light shielding member 760 in the Z direction. The focal point F of the imaging optical system 120 is located in the opening 761.

[0280] Among the light emitted from the display device 710A, the light passing through the focal point F and its vicinity enters the input element 121 through the opening 761 of the light shielding member 760, and most of the other light is blocked by the light shielding member 760. In addition, among the second polarized light 710s reflected by the reflective polarizing element 750, the light along the optical path, that is, the light passing through the focal point F and its vicinity returns to the display device 710A through the opening 761 of the light shielding member 760. On the other hand, among the second polarized light 710s reflected by the reflective polarizing element 750, the light not along the optical path and heading toward the display device 710A is blocked by the light shielding member 760.

[0281] Next, the effects of this embodiment will be described.

[0282] The image display device 70B of this embodiment further includes a reflective polarization element 750. The reflective polarization element 750 is disposed in a portion of the optical path from the display device 710A to the reflection unit 12 where a plurality of principal light rays L emitted from different positions in the display device 710A and passing through the first image IM1 are substantially parallel to each other, transmits the first polarized light 710p in the light emitted from the display device 710A, and reflects the second polarized light 710s in the light emitted from the display device 710A to return it to the display device 710A. Therefore, the ratio of the first polarized light 710p included in the light emitted from the image display device 70B can be increased, and the brightness of the second image IM2 can be increased.

[0283] In addition, a light shielding member 760 is provided between the display device 710A and the input element 121. The light shielding member 760 is provided with an opening 761 through which the second polarized light 710s that returns to the display device 710A along the optical path passes. Therefore, it is possible to allow the light along the optical path of the second polarized light 710s reflected by the reflective polarizing element 750 to return to the display device 710A, while suppressing the stray light that does not follow the optical path of the second polarized light 710s reflected by the reflective polarizing element 750 from heading toward the display device 710A. Thus, the quality of the first image IM1 and the second image IM2 can be improved. In addition, the light shielding member 760 can suppress the stray light that does not follow the optical path of the light emitted from the display device 710A from being reflected by the reflective polarizing element 750 or the optical element of the imaging optical system 120 and being re-excited or scattered and reflected at an unexpected place toward the display device 710A.

[0284] It should be noted that the light shielding component 760 may not be provided in the image display device 70B. In addition, the reflective polarization element 740 described in the eighth embodiment may be further provided on the display device 710A of the image display device 70B. In this case, the second polarized light 710s that has not been fully reflected by the reflective polarization element 740 on the display device 710A can be reflected by the reflective polarization element 750. Therefore, the proportion of the first polarized light 710p contained in the light emitted from the image display device 70B can be increased, and the brightness of the second image IM2 can be increased. The structures, actions and effects other than the above in this embodiment are the same as those in the eighth embodiment.

[0285] <Modification of Ninth Embodiment>

[0286] Next, a modification of the ninth embodiment will be described.

[0287] FIG. 28 is a side view showing a light source unit according to this modification.

[0288] FIG. 28 also shows only the cross section of the light shielding member 760 .

[0289] As shown in FIG28, in this modification, the reflective polarization element 750 is arranged between the output element 123 and the reflection unit 12. It should be noted that, although FIG28 shows an example in which the reflective polarization element 750 is located between the output element 123 and the first image IM1, the reflective polarization element 570 may also be arranged between the first image IM1 and the reflection unit 12. The structure, operation and effect other than the above in this modification are the same as those of the ninth embodiment.

[0290] The above-mentioned embodiments and their variations are examples of specific implementations of the present invention, and the present invention is not limited to these embodiments and variations. For example, in the above-mentioned embodiments and variations, embodiments and variations in which some components or processes are added, deleted or changed are also included in the present invention. In addition, the above-mentioned embodiments and variations can be implemented in combination with each other.

[0291] The embodiments include the following aspects.

[0292] (Note 1)

[0293] A light source unit, comprising:

[0294] A display device capable of displaying images;

[0295] a first prism sheet into which light emitted from the display device is incident;

[0296] an imaging optical system including an input element for incident light emitted from the first prism sheet and an output element for incident light via the input element, so that the light emitted from the output element forms a first image corresponding to the image,

[0297] The imaging optical system has a substantially telecentric property on the first image side.

[0298] The light emitted from the display device has a substantially Lambertian light distribution.

[0299] (Note 2)

[0300] The light source unit according to Supplement 1, wherein:

[0301] The first prism sheet has a first surface for incident light emitted from the display device and a second surface for emitting light toward the input element.

[0302] A strip-shaped first prism extending in a first direction is formed on the first surface.

[0303] The second surface includes a stripe-shaped second prism extending in a second direction intersecting the first direction.

[0304] (Note 3)

[0305] The light source unit according to Supplement 2, wherein:

[0306] The display device has a plurality of pixels arranged along a third direction and a fourth direction orthogonal to the third direction.

[0307] The first direction is inclined by 45 degrees relative to the third direction.

[0308] The second direction is inclined at 45 degrees with respect to the fourth direction.

[0309] (Note 4)

[0310] The light source unit according to Supplement 1, wherein:

[0311] It also includes a second prism sheet, which is arranged between the first prism sheet and the input element.

[0312] A strip-shaped first prism extending along a first direction is formed on the first prism sheet.

[0313] The second prism sheet includes stripe-shaped second prisms extending in a second direction intersecting the first direction.

[0314] (Note 5)

[0315] The light source unit according to Supplement 4, wherein:

[0316] The display device has a plurality of pixels arranged along a third direction and a fourth direction orthogonal to the third direction.

[0317] The first direction is inclined by 45 degrees relative to the third direction.

[0318] The second direction is inclined at 45 degrees with respect to the fourth direction.

[0319] (Note 6)

[0320] The light source unit according to any one of Supplementary Notes 1 to 5, wherein:

[0321] The light emitted from the display device has a luminous intensity in a direction which forms an angle θ with respect to the optical axis of the light emitted from the display device and is equal to the cosine of the luminous intensity on the optical axis. n The light distribution pattern is similar to θ times.

[0322] The above n is a value greater than 0.

[0323] (Note 7)

[0324] The light source unit according to Supplementary Note 6, wherein:

[0325] The above n is 11 or less.

[0326] (Note 8)

[0327] The light source unit according to any one of Supplementary Notes 1 to 7, wherein:

[0328] The display device is an LED display having a plurality of LED elements.

[0329] (Note 9)

[0330] The light source unit according to Supplementary Note 8, wherein:

[0331] The light emitted from the LED element has a substantially Lambertian light distribution.

[0332] (Note 10)

[0333] The light source unit according to Supplement 8 or 9, wherein:

[0334] The display device further includes a wavelength conversion member, which is disposed on the LED element and on which light emitted from the LED element is incident.

[0335] (Note 11)

[0336] The light source unit according to any one of Supplementary Notes 1 to 10, wherein:

[0337] The imaging optical system includes a bending portion and a direction changing portion, the bending portion includes the input element, and the direction changing portion includes the output element.

[0338] The bending portion bends the plurality of principal rays so that the plurality of principal rays are substantially parallel to each other in front of and behind the first image, the plurality of principal rays are emitted from different positions in the display device, and cross each other before entering the input element to reach the first image.

[0339] The direction changing unit changes the traveling directions of the plurality of principal rays so that the plurality of principal rays passing through the curved portion are directed toward a formation position of the first image.

[0340] (Note 12)

[0341] The light source unit according to any one of Supplementary Notes 1 to 10, wherein:

[0342] A light shielding component is also provided, which is arranged between the above-mentioned display device and the above-mentioned imaging optical system, has an opening for allowing a part of the light from the above-mentioned display device toward the above-mentioned imaging optical system to pass through, and shields another part of the light from the above-mentioned display device toward the above-mentioned imaging optical system.

[0343] (Note 13)

[0344] An image display device comprising:

[0345] The light source unit according to any one of supplementary notes 1 to 12;

[0346] a reflection unit, which is separated from the light source unit and reflects the light emitted from the imaging optical system,

[0347] The first image is formed between the light source unit and the reflection unit.

[0348] (Note 14)

[0349] The image display device according to Supplement 13, wherein:

[0350] A reflective polarization element is further provided, which is arranged on the optical path from the above-mentioned display device to the above-mentioned reflection unit, transmits the first polarized light in the light emitted from the above-mentioned display device, and reflects the second polarized light in the light emitted from the above-mentioned display device to return it to the above-mentioned display device.

[0351] (Note 15)

[0352] A car comprising:

[0353] vehicle;

[0354] The image display device described in Supplementary Note 13 or 14 is fixed to the above-mentioned vehicle.

[0355] Industrial Applicability

[0356] The present invention can be used, for example, in a head-up display.

[0357] Description of Reference Numerals

[0358] 10: Image display device

[0359] 11: Light source unit

[0360] 12: Reflection unit

[0361] 13: Vehicles

[0362] 13a: Front windshield

[0363] 13b: Top

[0364] 13c: Instrument panel

[0365] 13h1: Through hole

[0366] 13h2: Through hole

[0367] 13s1: wall

[0368] 13s2: wall

[0369] 14: Identifier

[0370] 14a: Eye Movement Range

[0371] 14b: Polarized Sunglasses

[0372] 15: Wavelength conversion components

[0373] 20: Image display device

[0374] 22: Reflection unit

[0375] 70A, 70B: Image display device

[0376] 71A, 71B: Light source unit

[0377] 110: Display device

[0378] 110p: Pixel

[0379] 110u: unit area

[0380] 111: Substrate

[0381] 112: LED components

[0382] 112a: Semiconductor stack

[0383] 112b: Anode electrode

[0384] 112c: cathode electrode

[0385] 112p1: p-type semiconductor layer

[0386] 112p2: Active layer

[0387] 112p3: n-type semiconductor layer

[0388] 112s: light exit surface

[0389] 112t: concave part

[0390] 118a, 118b: Wiring

[0391] 120: Imaging optical system

[0392] 120a: Bend

[0393] 120b: Direction change unit

[0394] 121: Input element

[0395] 121a: Reflective mirror

[0396] 122: Intermediate components

[0397] 122a: Reflective mirror

[0398] 123: Output element

[0399] 123a: Reflective mirror

[0400] 130: First prism

[0401] 130a: Side 1

[0402] 130b: Side 2

[0403] 130p1: First Prism

[0404] 130p2: Second prism

[0405] 131: Reflector

[0406] 131a: Reflective mirror

[0407] 210: Display device

[0408] 210p: Pixel

[0409] 230: First prism

[0410] 230a: Side 1

[0411] 230b: Side 2

[0412] 230p1: First Prism

[0413] 230p2: Second prism

[0414] 322: Reflector

[0415] 322a: Reflective mirror

[0416] 330: First prism

[0417] 330a: Side 1

[0418] 330b: Side 2

[0419] 330p1: First Prism

[0420] 330p2: Second prism

[0421] 431: First prism

[0422] 431a: Side 1

[0423] 431b: Side 2

[0424] 432: Second prism

[0425] 432a: Side 1

[0426] 432b: Side 2

[0427] 531: First prism

[0428] 531p: First Prism

[0429] 532: Second prism

[0430] 532p: Second Prism

[0431] 533: The third prism

[0432] 533p: The Third Prism

[0433] 570: Reflective polarizing element

[0434] 630: First prism

[0435] 630p: First Prism

[0436] 710A: Display device

[0437] 710a: light

[0438] 710p: First polarized light

[0439] 710s: Second polarized light

[0440] 712: LED components

[0441] 714: Protective layer

[0442] 715: Wavelength conversion components

[0443] 716A: Light scattering components

[0444] 740: Reflective polarizing element

[0445] 750: Reflective polarizing element

[0446] 760: Light shielding parts

[0447] 761: Opening

[0448] 1000: Cars

[0449] 2011: Light source unit

[0450] 2110: Display device

[0451] 2110p: Pixel

[0452] 2110s: light exit surface

[0453] 2120: Imaging Optical Systems

[0454] C: Optical axis

[0455] D: Distance

[0456] F: Focus

[0457] IM1: First Image

[0458] IM2: Second Image

[0459] L: Main ray

[0460] P: Position

[0461] P1: First plane

[0462] P2: Second Plane

[0463] Pa: pixel pitch

[0464] Pb: Prism pitch

[0465] a1: point

[0466] a2: point

[0467] n0, n1: refractive index

[0468] y: pixel displacement

[0469] θ: Angle

[0470] θp: prism angle

Claims

1. A light source unit, characterized in that: have: A display device capable of displaying images; a first prism sheet into which light emitted from the display device is incident; an imaging optical system including an input element for incident light emitted from the first prism sheet and an output element for incident light via the input element, so that the light emitted from the output element forms a first image corresponding to the image, The imaging optical system has a substantially telecentric property on the first image side, Light emitted from the display device has a substantially Lambertian light distribution.

2. The light source unit according to claim 1, wherein: The first prism sheet has a first surface for incident light emitted from the display device and a second surface for emitting light toward the input element. A strip-shaped first prism extending along a first direction is formed on the first surface. The second surface has stripe-shaped second prisms extending in a second direction intersecting the first direction.

3. The light source unit according to claim 2, wherein: The display device has a plurality of pixels arranged along a third direction and a fourth direction orthogonal to the third direction. The first direction is inclined by 45 degrees relative to the third direction, The second direction is inclined by 45 degrees with respect to the fourth direction.

4. The light source unit according to claim 1, wherein: further comprising a second prism sheet disposed between the first prism sheet and the input element, A strip-shaped first prism extending along a first direction is formed on the first prism sheet. The second prism sheet has strip-shaped second prisms extending in a second direction intersecting the first direction.

5. The light source unit according to claim 4, wherein: The display device has a plurality of pixels arranged along a third direction and a fourth direction orthogonal to the third direction. The first direction is inclined by 45 degrees relative to the third direction, The second direction is inclined by 45 degrees with respect to the fourth direction.

6. The light source unit according to any one of claims 1 to 5, wherein: The light emitted from the display device has a luminance in a direction at an angle θ relative to the optical axis of the light emitted from the display device and a value corresponding to the cosine of the luminance on the optical axis. n The light distribution pattern is similar to θ times. The n is a value greater than 0.

7. The light source unit according to claim 6, wherein: The n is 11 or less.

8. The light source unit according to any one of claims 1 to 7, wherein: The display device is an LED display having a plurality of LED elements.

9. The light source unit according to claim 8, wherein: The light emitted from the LED element has a substantially Lambertian light distribution.

10. The light source unit according to claim 8 or 9, wherein: The display device further includes a wavelength conversion member that is disposed on the LED element and into which light emitted from the LED element is incident.

11. The light source unit according to any one of claims 1 to 10, wherein: The imaging optical system includes a bending portion and a direction changing portion, the bending portion includes the input element, and the direction changing portion includes the output element. The bending portion bends a plurality of principal rays so that the plurality of principal rays are substantially parallel to each other in front of and behind the first image, the plurality of principal rays are emitted from different positions in the display device, and cross each other before entering the input element to reach the first image, The direction changing unit changes the traveling directions of the plurality of principal rays so that the plurality of principal rays passing through the curved portion are directed toward a formation position of the first image.

12. The light source unit according to any one of claims 1 to 10, wherein: A light shielding member is further provided, which is arranged between the display device and the imaging optical system, has an opening for allowing a part of the light from the display device toward the imaging optical system to pass through, and shields another part of the light from the display device toward the imaging optical system.

13. An image display device, characterized in that: have: The light source unit according to any one of claims 1 to 12; a reflection unit, which is separated from the light source unit and reflects the light emitted from the imaging optical system, The first image is formed between the light source unit and the reflection unit.

14. The image display device according to claim 13, wherein: A reflective polarization element is further provided, which is arranged on an optical path from the display device to the reflection unit, transmits a first polarized light among the light emitted from the display device, and reflects a second polarized light among the light emitted from the display device to return it to the display device.

15. A car, characterized in that: have: vehicle; The image display device according to claim 13 or 14 is fixed to the vehicle.

Images