Display device and head-up display device

Abstract

To provide a display device and a head-up display device capable of further enhancing a uniformity ratio.SOLUTION: A display device 10 configured to emit display light L showing an image includes: a light source 19 configured to emit illumination light IL; a third lens 53 configured to parallel the illumination light IL from the light source 19; surfaces 51i, 51o, 52i, 52o configured to distribute the illumination light IL paralleled by the third lens 53 and aligned on an optical axis of the paralleled illumination light IL; and a display surface 18a configured to receive the illumination light IL distributed at the surfaces 51i, 51o, 52i, 52o and emit the display light L, and arranged in a direction tilted to an optical axis of the emitted display light L. One of the surfaces 51i, 51o, 52i, 52o is a Fresnel lens surface disposed in a direction along the display surface 18a. One of the surfaces 51i, 51o, 52i, 52o other than the Fresnel lens surface is a cylindrical lens surface or a biconic lens array surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a display device and a head-up display device. [Background technology]

[0002] For example, a head-up display device described in Patent Document 1 includes a light source, first to third lenses through which light from the light source passes, a liquid crystal display panel that receives light that has passed through the first to third lenses and emits display light, and a concave mirror that displays a virtual image by reflecting the display light from the liquid crystal display panel toward a projection target such as a windshield. The first lens approximately collimates the light from the light source. The second and third lenses diffuse and distribute the light in accordance with the liquid crystal display panel and the visible range of the virtual image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-160293 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, there is room for improvement in the arrangement and type of each lens from the viewpoint of uniformity of illumination on the liquid crystal display panel.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and aims to provide a display device and a head-up display device that can further improve uniformity. [Means for solving the problem]

[0006] In order to achieve the above object, a display device according to a first aspect of the present disclosure comprises: A display device that emits display light representing an image, a light source that emits light; a collimating means for collimating the light from the light source; a plurality of light distribution optical surfaces that distribute the light collimated by the collimating means and are arranged on an optical axis of the collimated light; a display surface that receives light distributed by the plurality of light distribution optical surfaces and emits the display light, and is provided in an orientation inclined with respect to the optical axis of the emitted display light, a first light distributing optical surface among the plurality of light distributing optical surfaces is a Fresnel lens surface oriented along the display surface; A second light distributing optical surface of the plurality of light distributing optical surfaces is a lenticular lens surface or a biconic lens array surface.

[0007] In order to achieve the above object, a head-up display device according to a second aspect of the present disclosure includes: the display device; a mirror that reflects the display light from the display device, the mirror reflects the display light so that the upper and lower ends of the display light, which are both ends in the vertical direction, intersect; the Fresnel lens surface serving as the first light distributing optical surface is a linear Fresnel lens surface obtained by converting a convex lens having a zero curvature in the horizontal direction into a Fresnel lens, and the convex lens having a convex shape in the vertical direction, The vertical direction and the horizontal direction are set to be perpendicular to the optical axis of the collimated light and perpendicular to each other. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to further improve uniformity. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view of a head-up display device in a cross optical system according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic cross-sectional view of a display device according to an embodiment of the present disclosure, viewed from the side; [Figure 3]FIG. 1 is a perspective view of a cylindrical lens surface according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a perspective view of a concentric Fresnel lens surface according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is a cross-sectional view of a concentric Fresnel lens surface according to an embodiment of the present disclosure. [Figure 6] FIG. 10 is a schematic cross-sectional view of a display device according to a modified example of the embodiment of the present disclosure, as viewed from the side. [Figure 7] FIG. 1 is a perspective view of a horizontal light-distribution linear Fresnel lens surface according to an embodiment of the present disclosure. [Figure 8] FIG. 1 is a front view of a horizontal light-distribution linear Fresnel lens surface according to an embodiment of the present disclosure. [Figure 9] FIG. 1 is a perspective view of a vertical light distribution linear Fresnel lens surface according to an embodiment of the present disclosure. [Figure 10] FIG. 1 is a front view of a vertical light distribution linear Fresnel lens surface according to an embodiment of the present disclosure. [Figure 11] FIG. 1 is a perspective view of a biconic lens array surface according to an embodiment of the present disclosure. [Figure 12] The upper part of the figure for one embodiment of the present disclosure shows the vertical light intensity distribution in a configuration in which the cylindrical lens surface is parallel to the display surface, and the lower part shows the vertical light intensity distribution in a configuration in which the cylindrical lens surface is perpendicular to the direction of parallel light propagation. [Figure 13] 10 is a table showing the configuration of each lens surface in each lens pattern under condition B1 according to an embodiment of the present disclosure. [Figure 14] 10 is a table showing the configuration of each lens surface in each lens pattern under condition B2 according to an embodiment of the present disclosure. [Figure 15] 10 is a table showing the configuration of each lens surface in each lens pattern under condition B3 according to an embodiment of the present disclosure. [Figure 16] 10 is a table showing the configuration of each lens surface in each lens pattern under condition B4 according to an embodiment of the present disclosure. [Figure 17] The upper part of the diagram according to an embodiment of the present disclosure is a schematic diagram showing an image display area on a display surface, and the lower part is a schematic diagram showing a light source and a dimming zone. [Figure 18] FIG. 1 is a schematic cross-sectional view illustrating a portion of a Fresnel lens surface according to an embodiment of the present disclosure. [Figure 19] FIG. 10 is a schematic cross-sectional view of a head-up display device with a non-cross optical system according to a modified example of the present disclosure. [Figure 20] FIG. 10 is a schematic cross-sectional view of a display device according to a modified example of the present disclosure, as viewed from the side. [Figure 21] FIG. 1 is a perspective view of a lens having concentric Fresnel lens surfaces according to an embodiment of the present disclosure. [Figure 22] FIG. 2 is a schematic diagram illustrating an optical path of a head-up display device according to an embodiment of the present disclosure when viewed from the side. [Figure 23] FIG. 2 is a schematic diagram illustrating an optical path of a head-up display device according to an embodiment of the present disclosure when viewed from the vertical direction. DETAILED DESCRIPTION OF THE INVENTION

[0010] A head-up display device according to an embodiment of the present disclosure will be described with reference to the drawings. 1, the head-up display device 100 is installed, for example, in the dashboard of a vehicle 200. The head-up display device 100 emits display light L that represents an image toward a windshield 201, which is a projection target member of the vehicle 200, and displays a virtual image W by the display light L reflected by the windshield 201. The virtual image W is displayed in a rectangular display area that is long in the left-right direction and short in the up-down direction as seen by a viewer.

[0011] The head-up display device 100 includes a display device 10, a first mirror 21, a second mirror 22, a control unit 25, and a housing 30.

[0012] The housing 30 is formed in a box shape from a light-blocking resin or metal, etc., and houses the display device 10 and the mirrors 21, 22. An opening 30c is formed in the housing 30 at a position facing the windshield 201 in the height direction. The housing 30 is fitted into the opening 30c and has a plate-shaped window portion 31 made of a light-transmitting resin such as acrylic, through which the display light L passes.

[0013] The first mirror 21 and the second mirror 22 constitute a relay optical system that reflects the display light L from the display device 10 and guides it to the windshield 201 . The first mirror 21 reflects the display light L emitted from the display device 10 toward the second mirror 22. The first mirror 21 is a correction mirror, and is a concave mirror that is concavely curved along the height direction of the vehicle and extends linearly along the width direction of the vehicle. The first mirror 21 may be concavely curved or convexly curved in the width direction of the vehicle.

[0014] The first mirror 21 reflects the display light L from the display device 10 toward the second mirror 22 so that the display light L intersects with the first mirror 21 at a cross point CP when viewed from the width direction of the vehicle 200. The cross point CP is located between the first mirror 21 and the second mirror 22 in the optical path of the display light L. The display light L converges from the first mirror 21 to the cross point CP and diverges from the cross point CP toward the second mirror 22. That is, the display light L is formed into an image between the first mirror 21 and the second mirror 22 in the height direction.

[0015] The second mirror 22 is a concave mirror, and reflects the display light L from the display device 10 toward the windshield 201.

[0016] 2, the display device 10 includes a liquid crystal display panel 18 and an illumination device 15 that illuminates the liquid crystal display panel 18. The illumination device 15 includes a case 14, a substrate 16, a light diffusing member 17, a plurality of light sources 19, and first to third lenses 51 to 53. In the following description, the horizontal direction H is a direction corresponding in terms of the optical path to the left-right direction (vehicle width direction) of the virtual image W seen by the viewer, and the vertical direction V is a direction corresponding in terms of the optical path to the up-down direction of the virtual image W seen by the viewer. The horizontal direction H and the vertical direction V are perpendicular to each other and are each perpendicular to the parallel light traveling direction Z in which the illumination light IL collimated by the third lens 53 travels.

[0017] Case 14 is formed into a rectangular cylindrical shape from a light-blocking resin, metal, or the like. Substrate 16 and first to third lenses 51 to 53 are housed inside case 14. Liquid crystal display panel 18 is disposed in a position that covers opening 14a of case 14.

[0018] The substrate 16 has a plate shape extending along a horizontal direction H and a vertical direction V. The plurality of light sources 19 are mounted on a surface of the substrate 16 facing the third lens 53. Each light source 19 is formed, for example, by an LED (Light Emitting Diode). Specifically, the plurality of light sources 19 are arranged in a matrix in the vertical direction V and the horizontal direction H.

[0019] The liquid crystal display panel 18 has a display surface 18a that receives illumination light IL from each light source 19 and passes through first to third lenses 51 to 53, and displays an image (intermediate image). The display surface 18a is located on the surface of the liquid crystal display panel 18 from which the display light L is emitted, and has a rectangular shape that is long in the horizontal direction H and short in the vertical direction V. The display light L that shows an image is emitted from the display surface 18a of the liquid crystal display panel 18 toward the second mirror 22. The liquid crystal display panel 18 is a TFT (Thin Film Transistor) type liquid crystal panel.

[0020] The control unit 25 includes a CPU (Central Processing Unit), a GDC (Graphics Display Controller), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The control unit 25 controls the display device 10, for example, the plurality of light sources 19 and the liquid crystal display panel 18.

[0021] The control unit 25 has a local dimming function that adjusts the brightness of each of a plurality of dimming zones 18z that divide the display surface 18a in the vertical direction V and the horizontal direction H, as shown in the lower part of Fig. 17, depending on the content of the image displayed on the display surface 18a. One or a plurality of light sources 19 (LEDs) are associated with each dimming zone 18z. The control unit 25 lights up only the dimming zone 18z of the display surface 18a that corresponds to the image display area 18b (see the upper part of Fig. 17) where the content is displayed, and turns off the dimming zones 18z of the display surface 18a other than the image display area 18b. In this embodiment, the control unit 25 has a local dimming function, but it may not have the local dimming function and may turn on or off all the light sources 19 simultaneously.

[0022] 2, the first to third lenses 51 to 53 are arranged in the order of the third lens 53, the second lens 52, and the first lens 51, from the side closest to the light source 19. Illumination light IL from the light source 19 passes through the third lens 53, the second lens 52, and the first lens 51 in that order in the thickness direction. The first to third lenses 51 to 53 are each formed of a transparent optical resin or optical glass, and have a rectangular plate shape that is long in the horizontal direction H and short in the vertical direction V.

[0023] The third lens 53 collimates the light emitted from the light source 19 in the parallel light traveling direction Z. The third lens 53 includes a plurality of convex lens portions 53a. The plurality of convex lens portions 53a are arranged in a matrix so as to correspond one-to-one to the light sources 19 described above. For example, the convex lens portion 53a has a square shape when viewed from the parallel light traveling direction Z, and the length of one side of this square is set to 6 mm or less, for example, 5.6 mm. The third lens 53 is not limited to a lens, and may be a reflector as long as it is a collimating means.

[0024] The second lens 52 has an entrance surface 52i onto which the illumination light IL that has passed through the third lens 53 is incident, and an exit surface 52o from which the illumination light IL that has passed through the second lens 52 in its thickness direction emerges. The first lens 51 has an entrance surface 51i onto which the illumination light IL that has passed through the second lens 52 is incident, and an exit surface 51o from which the illumination light IL that has passed through the first lens 51 in its thickness direction emerges. In this example, the first lens 51, the second lens 52, and the liquid crystal display panel 18 are arranged parallel to one another and tilted non-orthogonally with respect to the parallel light traveling direction Z when viewed from the lateral direction H. The exit surface 52o of the second lens 52 is disposed along and facing the entrance surface 51i of the first lens 51. An exit surface 51o of the first lens 51 is disposed opposite the rear surface of the liquid crystal display panel 18 with the light diffusing member 17 interposed therebetween. The light diffusing member 17 is a diffusion plate that diffuses the illumination light IL from the exit surface 51o of the first lens 51 and emits it to the liquid crystal display panel 18. The light diffusing member 17 may be any optical member that has the function of diffusing light, and may have a surface that is made of, for example, a bead member or a fine uneven structure, or may be made of a dotted sheet or a translucent milky white sheet. The first lens 51 and the second lens 52 are provided to distribute the illumination light IL in accordance with the display surface 18a and further with the viewer's eyebox. The combination of lens types formed on each surface 51i, 51o, 52i, 52o of the first lens 51 and the second lens 52 is composed of any combination of lens patterns "No. 1" to "No. 31" shown in the tables of Figures 13 to 16.

[0025] In the lens pattern "No. 1" in Figure 13, the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a concentric Fresnel lens surface Sf, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0026] As shown in Fig. 3, the cylindrical lens surface Sc has a plurality of cylindrical lens portions Sc1. Each cylindrical lens portion Sc1 is formed in a concave shape extending in the extension direction L1, for example, a semi-cylindrical concave shape. The plurality of cylindrical lens portions Sc1 are arranged in the arrangement direction W1. For the cylindrical lens surface Sc that distributes light in the horizontal direction H, the horizontal direction H is the arrangement direction W1, and the cylindrical lens portions Sc1 are arranged in the horizontal direction H. For the cylindrical lens surface Sc that distributes light in the vertical direction V, the vertical direction V is the arrangement direction W1, and the cylindrical lens portions Sc1 are arranged in the vertical direction V. In accordance with the vertical and horizontal dimensions of display surface 18a, the light distribution angle at which cylindrical lens surface Sc distributes illumination light IL in the horizontal direction H is set to be larger than the light distribution angle at which illumination light IL is distributed in the vertical direction V. The light distribution angle of cylindrical lens surface Sc is determined by the curvature of cylindrical lens portion Sc1. In the table of Figure 13, the "cylindrical surface (large light distribution direction)" is a cylindrical lens surface Sc that distributes light in the horizontal direction H, and the "cylindrical surface (small light distribution direction)" is a cylindrical lens surface Sc that distributes light in the vertical direction V. Although the cylindrical lens portion Sc1 is formed in a concave shape extending in the extension direction L1, it may be formed in a semi-cylindrical convex shape extending in the extension direction L1.

[0027] 4 and 5, the concentric Fresnel lens surface Sf is formed in a sawtooth pattern with concentrically arranged peaks Sf1. Each peak Sf1 forms a circle centered on a lens decentering central axis O located on the concentric Fresnel lens surface Sf, and is arranged in the radial direction R of the circle. The lens decentering central axis O is located at a non-central position on the concentric Fresnel lens surface Sf. The decentering manner of the lens decentering central axis O will be described in detail later. The lens decentering central axis O may be provided at the center of the concentric Fresnel lens surface Sf. The concentric Fresnel lens surface Sf is formed with a concave surface. Specifically, the concentric Fresnel lens surface Sf is formed by dividing a hemispherical concave lens designed to be concave in the vertical direction V and the horizontal direction H in the radial direction R and arranging it at the same height, a so-called Fresnel lens. The peak portion Sf1 includes a side surface Sf3 along the lens decentering central axis O and a Fresnel inclined surface Sf2 inclined non-orthogonally to the lens decentering central axis O. The Fresnel inclined surface Sf2 connects the upper end of the side surface Sf3 (the end on the light-emission side of the concentric Fresnel lens surface Sf) to the lower end of the side surface Sf3 adjacent to the inner side of the side surface Sf3 in the radial direction R. The Fresnel inclined surface Sf2 is inclined so as to face the lens decentering central axis O more closely than the plane orthogonal to the lens decentering central axis O. Each Fresnel inclined surface Sf2 has the same width in the radial direction R. The Fresnel inclined surface Sf2 is a portion that bends light. The Fresnel slope Sf2 may be formed by a curve that faithfully reproduces the lens surface, or may be formed by an approximate curve or straight line.

[0028] In the lens pattern "No. 1," the incident surface 52i of the second lens 52 is formed as a flat surface, and therefore the illumination light is not bent at the incident surface 52i.

[0029] In the embodiment of Figure 2, the second lens 52 is arranged in a direction inclined with respect to the parallel light propagation direction Z when viewed from the horizontal direction H so as to be aligned with the first lens 51 and the liquid crystal display panel 18, but this is not limited thereto, and as shown in Figure 6, the second lens 52 may be arranged vertically, in a direction perpendicular to the parallel light propagation direction Z. The lens pattern "No. 1" can be placed not only at an angle as shown in Figure 2 but also vertically, as indicated by the "Vertical placement possible" in the "Vertical placement possible for second lens" column on the far right of the table in Figure 13.

[0030] The lens pattern "No. 1" satisfies the following condition A. (Condition A) A Fresnel lens surface (linear Fresnel lens surface or concentric Fresnel lens surface) parallel to the display surface 18a is formed on the first surface of any of surfaces 51i, 51o, 52i, and 52o of lenses 51 and 52, and a cylindrical lens surface (lenticular lens surface) or a biconic lens surface is formed on the second surface of any of surfaces 51i, 51o, 52i, and 52o. As long as this condition A is satisfied, the lens pattern is not limited to "No. 1," and may be any of the lens patterns "No. 1" to "No. 31" shown in the tables of Figures 13 to 16. By satisfying condition A, the uniformity of the illumination light IL and the display light L can be improved.

[0031] Furthermore, among the above-mentioned conditions A, the lens patterns "No. 1" to "No. 13" in the table of FIG. 13 satisfy the following condition B1. (Condition B1) A Fresnel lens surface (a linear Fresnel lens surface or a concentric Fresnel lens surface) is formed on the entrance surface 51i or the exit surface 51o of the first lens 51, and a cylindrical lens surface Sc is formed on the entrance surface 52i or the exit surface 52o of the second lens 52.

[0032] The lens patterns "No. 2" to "No. 13" will be explained below. In the lens pattern "No. 2," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a linear Fresnel lens surface SrH with horizontal light distribution, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V, and the entrance surface 52i of the second lens 52 is formed by a linear Fresnel lens surface SrV with vertical light distribution.

[0033] 7 and 8, the horizontal light distribution linear Fresnel lens surface SrH is formed in a sawtooth shape with peaks Sr1 arranged in the horizontal direction H. Each peak Sr1 extends in the vertical direction V. Therefore, the horizontal light distribution linear Fresnel lens surface SrH has a curvature of zero in the vertical direction V, and bends light in the horizontal direction H but not in the vertical direction V. The horizontal light-distribution linear Fresnel lens surface SrH is formed with a concave surface. Specifically, the horizontal light-distribution linear Fresnel lens surface SrH is formed by dividing a concave lens designed to be concave in the horizontal direction H in the horizontal direction H and arranging it at the same height, a so-called Fresnel lens. The peak portion Sr1 includes side surfaces Sr3 extending in the vertical direction V and the parallel light propagation direction Z, and Fresnel sloped surfaces Sr2 that are inclined non-orthogonally to the central plane J. The Fresnel sloped surfaces Sr2 are inclined with respect to the horizontal direction H so as to connect the upper and lower ends of two side surfaces Sr3 adjacent in the horizontal direction H. The Fresnel sloped surfaces Sr2 are inclined so as to face the central plane J more toward the central plane J than a plane perpendicular to the central plane J. The width of the Fresnel sloped surfaces Sr2 arranged in the horizontal direction H decreases with increasing distance from the central plane J in the horizontal direction H, and the inclination angle of the Fresnel sloped surfaces Sr2 with respect to a reference plane perpendicular to the central plane J increases. The Fresnel inclined surface Sr2 is a portion that bends light. Each peak Sr1 is positioned at the center of the horizontal direction H and is formed to be plane-symmetrical about a central plane J extending in the vertical direction V and the parallel light traveling direction Z.

[0034] 9 and 10, the vertical light distribution linear Fresnel lens surface SrV is formed in a sawtooth shape with peaks Sra arranged in the vertical direction V. Each peak Sra extends along the horizontal direction H. Therefore, the vertical light distribution linear Fresnel lens surface SrV has a curvature of zero in the horizontal direction H, and bends light in the vertical direction V but not in the horizontal direction H. The vertical light distribution linear Fresnel lens surface SrV is formed as a convex surface. Specifically, the vertical light distribution linear Fresnel lens surface SrV is formed by dividing a convex lens designed to be convex in the vertical direction V along the vertical direction V and arranging it at the same height, a so-called Fresnel lens. The peak portion Sra includes side surfaces Src extending in the horizontal direction H and the parallel light propagation direction Z, and Fresnel sloped surfaces Srb inclined non-orthogonally to the central plane J. The Fresnel sloped surfaces Srb are inclined with respect to the horizontal direction H so as to connect the upper and lower ends of two side surfaces Src adjacent in the vertical direction V. The Fresnel sloped surfaces Srb are inclined so as to face the opposite side from the central plane J (outside the vertical direction V) than the plane orthogonal to the central plane J. The width of the Fresnel sloped surfaces Srb aligned in the vertical direction V decreases with increasing distance from the central plane J in the vertical direction V, and the inclination angle of the Fresnel sloped surfaces Srb with respect to a reference plane orthogonal to the central plane J increases. The Fresnel slope Srb is the part that bends light. Each peak Sra is positioned at the center of the vertical direction V and is formed to be plane-symmetrical about a central plane J extending in the horizontal direction H and the parallel light traveling direction Z.

[0035] In the lens pattern "No. 3" in the table of Figure 13, the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a horizontally light-distributing linear Fresnel lens surface SrH, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0036] In the lens pattern "No. 4," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a linear Fresnel lens surface SrV with vertical light distribution, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V, and the entrance surface 52i of the second lens 52 is formed by a linear Fresnel lens surface SrH with horizontal light distribution.

[0037] In the lens pattern "No. 5," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a linear Fresnel lens surface SrV with vertical light distribution, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0038] In the lens pattern "No. 6," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a concentric Fresnel lens surface Sf, the exit surface 52o of the second lens 52 is formed by a plane, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0039] In the lens pattern "No. 7," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a linear Fresnel lens surface SrH with horizontal light distribution, the exit surface 52o of the second lens 52 is formed by a linear Fresnel lens surface SrV with vertical light distribution, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0040] In the lens pattern "No. 8," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a horizontally light-distributing linear Fresnel lens surface SrH, the exit surface 52o of the second lens 52 is formed by a plane, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0041] In the lens pattern "No. 9," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a linear Fresnel lens surface SrV with vertical light distribution, the exit surface 52o of the second lens 52 is formed by a linear Fresnel lens surface SrH with horizontal light distribution, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0042] In the lens pattern "No. 10," the exit surface 51o of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the entrance surface 51i of the first lens 51 is formed by a linear Fresnel lens surface SrV with vertical light distribution, the exit surface 52o of the second lens 52 is formed by a plane, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0043] In the lens pattern "No. 11," the exit surface 51o of the first lens 51 is formed by a concentric Fresnel lens surface Sf, the entrance surface 51i of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0044] In the lens pattern "No. 12," the exit surface 51o of the first lens 51 is formed by a concentric Fresnel lens surface Sf, the entrance surface 51i of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, and the exit surface 52o and entrance surface 52i of the second lens 52 are each formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0045] In the lens pattern "No. 13," the exit surface 51o of the first lens 51 is formed by a concentric Fresnel lens surface Sf, the entrance surface 51i of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, the exit surface 52o of the second lens 52 is formed by a plane, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0046] In addition, for lens patterns "No. 1" to "No. 14," the second lens 52 can be placed either vertically as shown in Figure 6 or at an angle as shown in Figure 2, while for lens patterns "No. 15" to "No. 31," vertical placement is not possible (inappropriate), and only an angled placement is possible (appropriate).

[0047] Furthermore, by satisfying the following condition B1-1 of the condition B1, the uniformity of the illumination light IL and the display light L is further improved. (Condition B1-1) The second lens 52 is placed vertically (see FIG. 6), and a cylindrical lens surface Sc that distributes light in the vertical direction V is formed on the entrance surface 52i or exit surface 52o of the second lens 52. In a configuration in which the cylindrical lens surfaces Sc distributing light in the vertical direction V are parallel to the display surface 18a (an inclined installation configuration that does not satisfy condition B1-1), the light distribution angle θ of the illumination light IL or display light L widens and the light intensity distribution is biased to one side of the vertical direction V, as shown in the upper part of Fig. 12. In contrast, in a configuration in which the cylindrical lens surfaces Sc distributing light in the vertical direction V are perpendicular to the parallel light traveling direction Z (a vertical installation configuration that satisfies condition B1-1), the light distribution angle θ of the illumination light IL or display light L does not widen and the light intensity distribution is not biased, as shown in the lower part of Fig. 12, resulting in a high uniformity and improved light efficiency. Therefore, it is preferable that the cylindrical lens surfaces Sc in the vertical direction V be perpendicular to the optical axis of the illumination light IL from the light source 19. The upper part of Figure 12 shows the light intensity distribution when the cylindrical lens surface Sc that distributes light in the vertical direction V is tilted by 30° with respect to the angle perpendicular to the parallel light traveling direction Z. It is known that the greater this tilt, the greater the bias in the light intensity distribution. Even when the second lens 52 is tilted (see Figure 2) so that the cylindrical lens surface Sc that distributes light in the vertical direction V is parallel to the display surface 18a, an equivalent light distribution angle can be obtained by reducing the curvature of each cylindrical lens portion Sc1 (increasing the radius of curvature).

[0048] Furthermore, among the above-mentioned conditions A, the lens patterns "No. 14" to "No. 19" in the table of FIG. 14 satisfy the following condition B2. (Condition B2) A Fresnel lens surface (a linear Fresnel lens surface or a concentric Fresnel lens surface) is formed on the entrance surface 51i or the exit surface 51o of the first lens 51, and a cylindrical lens surface Sc is formed on both the entrance surface 52i and the exit surface 52o of the second lens 52. Under condition B2, both surfaces of the second lens 52 are formed as cylindrical lens surfaces Sc, and therefore the structure of the second lens 52 is simple.

[0049] In the lens pattern "No. 14," the exit surface 51o of the first lens 51 is formed by a concentric Fresnel lens surface Sf, the entrance surface 51i of the first lens 51 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, and the exit surface 52o and entrance surface 52i of the second lens 52 are each formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0050] In the lens pattern "No. 15," the exit surface 51o of the first lens 51 is formed by a concentric Fresnel lens surface Sf, the entrance surface 51i of the first lens 51 is formed by a plane, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0051] In the lens pattern "No. 16," the exit surface 51o of the first lens 51 is formed by a horizontally light-distributing linear Fresnel lens surface SrH, the entrance surface 51i of the first lens 51 is formed by a vertically light-distributing linear Fresnel lens surface SrV, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0052] In the lens pattern "No. 17," the exit surface 51o of the first lens 51 is formed by a horizontally light-distributing linear Fresnel lens surface SrH, the entrance surface 51i of the first lens 51 is formed by a flat surface, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0053] In the lens pattern "No. 18," the exit surface 51o of the first lens 51 is formed by a vertical light distribution linear Fresnel lens surface SrV, the entrance surface 51i of the first lens 51 is formed by a horizontal light distribution linear Fresnel lens surface SrH, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0054] In the lens pattern "No. 19," the exit surface 51o of the first lens 51 is formed by a vertical light-distribution linear Fresnel lens surface SrV, the entrance surface 51i of the first lens 51 is formed by a plane, the exit surface 52o of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the horizontal direction H, and the entrance surface 52i of the second lens 52 is formed by a cylindrical lens surface Sc (lenticular lens surface) that distributes light in the vertical direction V.

[0055] Furthermore, among the above-mentioned conditions A, the lens patterns "No. 20" to "No. 27" in the table of FIG. 15 satisfy the following condition B3. (Condition B3) A Fresnel lens surface (a linear Fresnel lens surface or a concentric Fresnel lens surface) is formed on one of the entrance surface 51i and the exit surface 51o of the first lens 51, and a biconic lens array surface is formed on the other of the entrance surface 51i and the exit surface 51o. According to this condition B3, by adopting a biconic lens array surface that distributes illumination light IL in both the vertical direction V and the horizontal direction H, it becomes easier to omit lenses or to add a flat surface to any of the surfaces 51i, 51o, 52i, and 52o, thereby increasing the freedom of lens design.

[0056] As shown in FIG. 11, the biconic lens array surface Sb has a plurality of microlens portions Sb1 arranged in the vertical direction V and the horizontal direction H. Each microlens portion Sb1 is formed to have a convex shape. Each microlens portion Sb1 is convexly curved when viewed from the X direction and also convexly curved when viewed from the Y direction. Each microlens portion Sb1 is set with a conic coefficient kx in the X direction and a conic coefficient ky in the Y direction. The conic coefficients kx and ky of each microlens portion Sb1 can take any real number. In other words, both the conic coefficients kx and ky may be zero. The biconic lens array surface Sb has both the functions of a cylindrical lens surface Sc that distributes light in the horizontal direction H and the functions of a cylindrical lens surface Sc that distributes light in the vertical direction V, i.e., the function of refracting or diffusing light in both the vertical direction V and the horizontal direction H. Each microlens portion Sb1 may be formed in a concave shape.

[0057] 15, the second lens 52 is omitted, and the display device has only the first lens 51 and the third lens 53. This makes it possible to realize a simple configuration.

[0058] In the lens pattern "No. 20", the exit surface 51o of the first lens 51 is formed by a concentric Fresnel lens surface Sf, and the entrance surface 51i of the first lens 51 is formed by a biconic lens array surface Sb.

[0059] In the lens pattern "No. 21", the exit surface 51o of the first lens 51 is formed by a horizontal light-distribution linear Fresnel lens surface SrH, and the entrance surface 51i of the first lens 51 is formed by a biconic lens array surface Sb.

[0060] In the lens pattern "No. 22", the exit surface 51o of the first lens 51 is formed by a vertical light distribution linear Fresnel lens surface SrV, and the entrance surface 51i of the first lens 51 is formed by a biconic lens array surface Sb.

[0061] In the lens pattern "No. 23", the exit surface 51o of the first lens 51 is formed by a biconic lens array surface Sb, and the entrance surface 51i of the first lens 51 is formed by a concentric Fresnel lens surface Sf.

[0062] In the lens pattern "No. 24," the exit surface 51o of the first lens 51 is formed by a biconic lens array surface Sb, the entrance surface 51i of the first lens 51 is formed by a horizontal light-distribution linear Fresnel lens surface SrH, the exit surface 52o of the second lens 52 is formed by a vertical light-distribution linear Fresnel lens surface SrV, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0063] In the lens pattern "No. 25," the exit surface 51o of the first lens 51 is formed by a biconic lens array surface Sb, the entrance surface 51i of the first lens 51 is formed by a horizontal light-distribution linear Fresnel lens surface SrH, the exit surface 52o of the second lens 52 is formed by a flat surface, and the entrance surface 52i of the second lens 52 is formed by a vertical light-distribution linear Fresnel lens surface SrV.

[0064] In the lens pattern "No. 26," the exit surface 51o of the first lens 51 is formed by a biconic lens array surface Sb, the entrance surface 51i of the first lens 51 is formed by a vertical light distribution linear Fresnel lens surface SrV, the exit surface 52o of the second lens 52 is formed by a horizontal light distribution linear Fresnel lens surface SrH, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0065] In lens pattern "No. 27," exit surface 51o of first lens 51 is formed by a biconic lens array surface Sb, entrance surface 51i of first lens 51 is formed by a vertical light-distribution linear Fresnel lens surface SrV, exit surface 52o of second lens 52 is formed by a flat surface, and entrance surface 52i of second lens 52 is formed by a horizontal light-distribution linear Fresnel lens surface SrH.

[0066] Furthermore, among the above-mentioned conditions A, the lens patterns "No. 28" to "No. 31" in the table of FIG. 16 satisfy the following condition B4. (Condition B4) A Fresnel lens surface (a linear Fresnel lens surface or a concentric Fresnel lens surface) is formed on either the entrance surface 51i or the exit surface 51o of the first lens 51, and a biconic lens array surface Sb is formed on either the entrance surface 51i or the exit surface 51o of the second lens 52.

[0067] In the lens pattern "No. 28," the exit surface 51o of the first lens 51 is formed by a horizontal light-distribution linear Fresnel lens surface SrH, the entrance surface 51i of the first lens 51 is formed by a flat surface, the exit surface 52o of the second lens 52 is formed by a biconic lens array surface Sb, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0068] In the lens pattern "No. 29," the exit surface 51o of the first lens 51 is formed by a horizontal light-distribution linear Fresnel lens surface SrH, the entrance surface 51i of the first lens 51 is formed by a flat surface, the exit surface 52o of the second lens 52 is formed by a flat surface, and the entrance surface 52i of the second lens 52 is formed by a biconic lens array surface Sb.

[0069] In the lens pattern "No. 30," the exit surface 51o of the first lens 51 is formed by a vertical light distribution linear Fresnel lens surface SrV, the entrance surface 51i of the first lens 51 is formed by a flat surface, the exit surface 52o of the second lens 52 is formed by a biconic lens array surface Sb, and the entrance surface 52i of the second lens 52 is formed by a flat surface.

[0070] In the lens pattern "No. 31," the exit surface 51o of the first lens 51 is formed by a vertical light distribution linear Fresnel lens surface SrV, the entrance surface 51i of the first lens 51 is formed by a plane, the exit surface 52o of the second lens 52 is formed by a plane, and the entrance surface 52i of the second lens 52 is formed by a biconic lens array surface Sb.

[0071] In all of the lens patterns "No. 28" to "No. 31" described above, the entrance surface 51i of the first lens 51 is formed as a flat surface. Here, if a periodic structure such as a Fresnel lens or a lenticular lens is present on each of the two surfaces that are in contact or facing each other, there is a possibility that optical interference fringes will occur. However, by interposing a flat surface, the periodic structures can be spaced apart, thereby suppressing the occurrence of optical interference fringes. In this way, by employing a biconic lens array surface Sb that can distribute light in two directions, the vertical direction V and the horizontal direction H, there is room for a flat surface to suppress the occurrence of optical interference fringes.

[0072] Furthermore, among the above condition A, the lens patterns "No. 2" to "No. 5," "No. 7" to "No. 10," "No. 16" to "No. 19," "No. 21," "No. 22," and "No. 24" to "No. 31" satisfy the following condition C. (Condition C) The display light L reflected by the first mirror 21 does not intersect in the horizontal direction H, but intersects in the vertical direction V at a cross point CP, and one or more of the surfaces 51i, 51o, 52i, and 52o are linear Fresnel lens surfaces SrH, SrV.

[0073] Furthermore, among the above-mentioned conditions C, the patterns having both the linear Fresnel lens surfaces SrH and SrV satisfy the following conditions C1 and C2. (Condition C1) The horizontal light-distribution linear Fresnel lens surface SrH is formed as a concave surface (see FIG. 8). (Condition C2) The vertical light distribution linear Fresnel lens surface SrV is formed as a convex surface (see FIG. 10). This condition C2 makes it easier for the display light L to intersect with the vertical direction V and harder for it to intersect with the horizontal direction H, which is suitable for the cross optical system.

[0074] Furthermore, among the above-mentioned condition C, it is desirable that the following condition D be satisfied for the lens patterns "No. 2," "No. 4," "No. 7," "No. 9," "No. 16," "No. 18," and "No. 24" to "No. 27," which have multiple linear Fresnel lens surfaces. (Condition D) When two or more linear Fresnel lens surfaces are provided, the absolute value of the curvature of the linear Fresnel lens surface closer to display surface 18a is set to be equal to or greater than the absolute value of the curvature of the linear Fresnel lens surface farther from display surface 18a. Here, a large curvature means that the curve is sharp and the radius of curvature is small. Further, from the side closest to the display surface 18a, the order is emergent surface 51o, incident surface 51i, emergent surface 52o, and incident surface 52i. The curvature of the linear Fresnel lens surfaces SrH and SrV is the curvature before the Fresnel inclined surfaces Sr2 and Srb, which are arranged in a direction away from the central plane J, are arranged on the same curved surface, and the greater the curvature, the stronger the tendency to bend light. If linear Fresnel lens surfaces SrH, SrV, which strongly bend light, were installed far from display surface 18a, the light would bend too much over the optical path from linear Fresnel lens surfaces SrH, SrV to display surface 18a, potentially reducing the uniformity. Condition D above is set to prevent this reduction in uniformity. For example, in lens pattern "No. 2," the absolute value of the curvature of the concave surface of horizontal light-distribution linear Fresnel lens surface SrH of incident surface 51i is set to be equal to or greater than the absolute value of the curvature of the convex surface of vertical light-distribution linear Fresnel lens surface SrV of incident surface 52i.

[0075] Furthermore, it is desirable that the following condition E, among the above condition D, be satisfied. (Condition E) A linear Fresnel lens surface SrH or SrV is formed on the exit surface 51o of the first lens 51. Condition E allows the curvature of the linear Fresnel lens surface SrH or SrV formed on the exit surface 51o of the first lens 51 to be small, thereby increasing the illumination efficiency of the illumination light IL.

[0076] Furthermore, among the above-mentioned conditions A, it is preferable that the lens patterns "No. 1" to "No. 19" satisfy the following condition F. (Condition F) When two or more cylindrical lens surfaces are provided, the absolute value of the curvature of the cylindrical lens surface closer to display surface 18a is set to be equal to or greater than the absolute value of the curvature of the cylindrical lens surface farther from display surface 18a. The curvature of the cylindrical lens surface Sc is the curvature of the cylindrical lens portion Sc1. The larger the curvature of the cylindrical lens surface Sc, the stronger the property of bending light. If cylindrical lens surfaces Sc, which strongly bend light, were installed far from display surface 18a, the light would bend too much over the optical path length from cylindrical lens surfaces Sc to display surface 18a, potentially reducing the uniformity. Condition F is set to suppress such a reduction in uniformity. In particular, with the local dimming function, there are cases where only a portion of display surface 18a (dimming zone 18z) is illuminated. In this case, the discrepancy between dimming zone 18z and the actual illumination range is particularly noticeable, so it is important to set condition F to suppress this discrepancy.

[0077] Furthermore, among the above-mentioned conditions A, the lens patterns "No. 11" to "No. 15" and "No. 20" satisfy the following condition G. (Condition G) The exit surface 51o of the first lens 51 is formed of a concentric Fresnel lens surface Sf. Condition G allows the curvature of the concentric Fresnel lens surface Sf formed on the exit surface 51o of the first lens 51 to be small, thereby increasing the illumination efficiency of the illumination light IL.

[0078] Furthermore, among the above-mentioned conditions G, the present embodiment satisfies the following condition G1. (Condition G1) The concentric Fresnel lens surface Sf is formed as a concave surface (see FIG. 5). Here, the concentric Fresnel lens surface Sf being formed as a concave surface means that when the Fresnel inclined surfaces Sf2 arranged in the radial direction R are arranged on the same curved surface, they form a hemispherical concave shape before being formed into a Fresnel lens.

[0079] Furthermore, in this embodiment, the following conditions I to L are satisfied. (Condition I) The depth Dp of each of the Fresnel lens surfaces Sf, SrV, and SrH is uniform within the surface (see FIG. 18). (Condition J) The depth Dp is 0.1 mm or less, for example, 0.1 mm or 0.02 mm. (Condition K) The angle α (draft gradient) of the side surfaces Sf3, Sr3, and Src relative to the parallel light traveling direction Z is 0 to 5 degrees, for example, 1 degree. The smaller this angle α, the larger the area of ​​the Fresnel inclined surfaces Sf2, Sr2, and Srb can be, and the higher the illumination efficiency. (Condition L) The sum of the radius of curvature of the tip P1 and the radius of curvature of the base P2 of each Fresnel lens surface Sf, SrV, SrH is greater than 0% and less than or equal to 15% of the lens pitch P of each Fresnel lens surface Sf, SrV, SrH, for example, less than or equal to 12.5%. The smaller this sum is, the larger the area of ​​the Fresnel inclined surfaces Sf2, Sr2, Srb can be, and therefore the higher the illumination efficiency. (Condition M) The lens pitch P of the cylindrical lens surface Sc or the biconic lens array surface Sb is 0.3 mm or less. From the viewpoints of lens formability and preventing fringe appearance, it is preferable that the lens pitch P be set to such a value. Although FIG. 18 shows the Fresnel lens as having a convex surface, the same applies to a concave surface.

[0080] Furthermore, the relationship between the curvature C1 of the oblique Fresnel lens surface when the Fresnel lens surfaces Sf, SrH, and SrV are arranged obliquely and non-orthogonal to the parallel light traveling direction Z, the curvature C2 of the upright Fresnel lens surface when the Fresnel lens surfaces Sf, SrH, and SrV are arranged orthogonal to the parallel light traveling direction Z, and the curvature C3 of the upright toroidal surface when the toroidal surface described in Patent Document 1 is arranged orthogonal to the parallel light traveling direction Z is as follows: Curvature C1 of the oblique Fresnel lens surface < curvature C2 of the vertical Fresnel lens surface < curvature C3 of the vertical toroidal surface The smaller the distance between display surface 18a and the Fresnel lens surface or toroidal surface, the smaller the curvature required, so the curvature C1 of an oblique Fresnel lens surface is the smallest. Also, unlike a toroidal surface, the position of the parallel light propagation direction Z is the same at the edge and the center of a Fresnel lens surface, so the center and edges can be closer to display surface 18a than in the case of a toroidal surface. For this reason, the curvature C2 of an upright Fresnel lens surface can be smaller than the curvature C3 of an upright toroidal surface.

[0081] (effect) According to the above-described embodiments, the following effects are achieved. (1) Display device 10 emits display light L representing an image and includes light source 19 that emits illumination light IL, third lens 53 that is an example of collimating means that collimates illumination light IL from light source 19, surfaces 51i, 51o, 52i, and 52o that are an example of a plurality of light distributing optical surfaces that distribute the illumination light IL collimated by third lens 53 and are arranged on the optical axis of the collimated illumination light IL, and display surface 18a that receives illumination light IL distributed by surfaces 51i, 51o, 52i, and 52o and emits display light L and is provided in an orientation inclined with respect to the optical axis of the emitted display light L. Any of surfaces 51i, 51o, 52i, and 52o as a first light distributing optical surface is a Fresnel lens surface Sf, SrH, or SrV that is provided in an orientation along display surface 18a. Any of the second light distributing optical surfaces 51i, 51o, 52i, and 52o is a cylindrical lens surface Sc (lenticular lens surface) or a biconic lens array surface Sb. According to this configuration, the uniformity of the illumination light IL and the display light L can be improved by combining the Fresnel lens surfaces Sf, SrH, SrV with the cylindrical lens surface Sc or the biconic lens array surface Sb. Specifically, the configuration of Patent Document 1 has room for improvement in terms of uniformity for the following reasons (a) to (c). (a) The exit surface of the lens is a large toroidal surface, and the resulting aberration distorts the illumination shape at the edge of the LCD panel. (b) Since each lens surface that generates the divergent light is far from the liquid crystal display panel, the optical path length is long, resulting in a wide and elongated illumination shape. (c) Because the liquid crystal display panel is tilted relative to the backlight, a difference in distance occurs between the top and bottom of the liquid crystal display panel, changing the amount of illumination extension. Regarding point (a) above, the above configuration has Fresnel lens surfaces Sf, SrH, and SrV instead of toroidal surfaces, so that distortion of the illumination shape caused by the shape of the toroidal surfaces is suppressed. Regarding point (b) above, in the above configuration, the Fresnel lens surfaces Sf, SrH, and SrV are arranged at an angle along the display surface 18a, so the optical path length is unlikely to become long, and the illumination shape is prevented from extending widely. Regarding point (c) above, in the above configuration, Fresnel lens surfaces Sf, SrH, and SrV are arranged at an angle along display surface 18a, so that the change in the amount of illumination extension due to the difference in distance between display surface 18a and light source 19 is suppressed.

[0082] (2) One of the two second light distributing optical surfaces is a cylindrical lens surface Sc, which is an example of a first lenticular lens surface that distributes light in the vertical direction V. The other of the two second light distributing optical surfaces is a cylindrical lens surface Sc, which is an example of a second lenticular lens surface that distributes light in the horizontal direction H. The cylindrical lens surface Sc that distributes light in the vertical direction V is arranged perpendicular to the optical axis of the collimated illumination light IL. The vertical direction V and the horizontal direction H are set in directions that are perpendicular to each other while being perpendicular to the optical axis. According to this configuration, as described with reference to FIG. 12, the intensity distribution of the illumination light IL and the display light L is less likely to become biased, the uniformity of the illumination light IL and the display light L is improved, and the light efficiency is also improved.

[0083] (3) The absolute value of the radius of curvature of the cylindrical lens surface Sc, which is an example of a first lenticular lens surface of one of the two second light distribution optical surfaces, is set to be greater than or equal to the absolute value of the radius of curvature of the cylindrical lens surface Sc, which is an example of a second lenticular lens surface of the other of the two second light distribution optical surfaces that is located farther from the display surface 18a than the cylindrical lens surface Sc (first lenticular lens surface). According to this configuration, by positioning the cylindrical lens surface Sc having the stronger light bending property closer to the display surface 18a, it is possible to prevent the light from bending too much along the optical path from the cylindrical lens surface Sc having the stronger light bending property to the display surface 18a, thereby preventing a decrease in uniformity.

[0084] (4) The head-up display device 100 includes a display device 10 and a first mirror 21, which is an example of a mirror that reflects display light L from the display device 10. The first mirror 21 reflects the display light L so that the upper and lower ends of the display light L, which are both ends in the vertical direction V, intersect. The Fresnel lens surface, which is the first light distributing optical surface, is a vertical light distributing linear Fresnel lens surface SrV that extends linearly with zero curvature in the horizontal direction H and is obtained by Fresnelizing a convex lens that is convex in the vertical direction V. According to this configuration, in a cross optical system that crosses the display light L in the vertical direction V, a vertical light-distribution linear Fresnel lens surface SrV that is convex in the vertical direction V, where the illumination light IL is less likely to spread due to the crossing of the display light L, is suitable.

[0085] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including deletion of components) may be made as appropriate within the scope of the present disclosure. An example of such a modification is described below.

[0086] (Variation) In each of the above embodiments, the head-up display device 100 is configured as a cross optical system in which the display light L reflected by the first mirror 21 does not intersect in the horizontal direction H but intersects in the vertical direction V at a cross point CP, but is not limited to this cross optical system and may be configured as a non-cross optical system. In the case of a non-cross optical system, as shown in FIG. 19 , the first mirror 21a may be a flat mirror, and the display light L reflected by the first mirror 21a may not intersect in the vertical direction V or the horizontal direction H. The first mirror 21a is not limited to a flat mirror, but may also be a convex mirror. Alternatively, the first mirrors 21 and 21a may be omitted, and the display light L from the display device 10 may be directly projected onto the second mirror 22. In these non-cross optical systems, there is no need to cross the display light L in the vertical direction V, and there is no need to form the vertical light-distribution linear Fresnel lens surface SrV as a convex surface (convex lens converted into a Fresnel lens). Therefore, a concave concentric Fresnel lens surface Sf, which is a Fresnel lens converted from a concave lens, is optimal as the Fresnel lens surface. While this is optimal, linear Fresnel lens surfaces SrH and SrV may also be used in these non-cross optical systems.

[0087] In each of the above embodiments, the linear Fresnel lens surface SrH is a Fresnel lens formed by dividing a concave lens concave in the horizontal direction H into Fresnel lenses. However, the linear Fresnel lens surface SrV may be a Fresnel lens formed by dividing a convex lens convex in the horizontal direction H into Fresnel lenses. The linear Fresnel lens surface SrV may be a Fresnel lens formed by dividing a concave lens. The Fresnel lens surface Sf may be a Fresnel lens formed by dividing a convex lens.

[0088] In the above-described embodiments and modifications, the first lens 51 is inclined non-orthogonally with respect to the optical axes of the illumination light IL and the display light L. However, this is not limiting. Alternatively, the first lens 51 may be orthogonal to the optical axis of the illumination light IL and inclined non-orthogonally with respect to the optical axis of the display light L by changing the direction of light using a prism sheet (optical path changing means). For example, as shown in FIG. 20 , a prism sheet 59 is disposed between the first lens 51 and the liquid crystal display panel 18 and has fine prisms that reflect the illumination light IL in a direction different from the parallel light traveling direction Z. The prism sheet 59 is not limited to being disposed between the first lens 51 and the liquid crystal display panel 18, but may be disposed between the first lens 51 and the second lens 52, or between the second lens 52 and the third lens 53. Using the prism sheet 59 can reduce the size of the display device 10a. Furthermore, the illumination size Q can be increased without changing the size of the intermediate image displayed on the display surface 18a. Therefore, in the local dimming function, the number of dimming zones can be increased without changing the pitch of the light sources 19.

[0089] Of the above conditions, all conditions other than condition A do not necessarily have to be satisfied. In each of the above-described embodiments and modifications, the display device 10 may be a laser scanning display device that displays an image on a screen by scanning emitted laser light on the screen. The phrase "equal to or greater than the absolute value" in each of the above embodiments can be replaced with "greater than the absolute value."

[0090] In the above embodiment, the first to third lenses 51 to 53 are formed in the shape of rectangular plates, but are not limited to this, and may be formed in the shape of square, circular, elliptical or polygonal plates, for example. In the above embodiment, the head-up display device 100 is mounted on the vehicle 200, but it may be mounted on other vehicles such as an airplane, a ship, etc. The projection member onto which the display light L is projected is not limited to the windshield 201, but may be a dedicated combiner.

[0091] In the above-described embodiment (particularly, FIGS. 4 and 5), the concentric Fresnel lens surface Sf is formed so as to be divided in the radial direction R and arranged at the same height, but this is not limiting and the lens surface may be formed, for example, by the following method. In the first modification technique, the Fresnel lens surface may be formed so that the apexes of the peaks (for example, peaks Sf1) are arranged at equal intervals in the radial direction R. With this technique, even if the lens surface to be divided is an aspherical lens surface, the trajectory of the processing tool during mold processing can be made into a circular motion that is easy to control on the XY plane, thereby reducing the difficulty of manufacturing. In the second modification method, the Fresnel lens surface may be formed by combining the method described in the above embodiment with the first modification method. Specifically, the Fresnel lens surface may be formed by setting upper limits on both the height (depth) of the concentric Fresnel lens surface and the pitch of the peaks, and dividing the lens surface when either limit is reached. For example, in the above embodiment, an example was shown in which the upper limit on the depth was 0.1 mm and there was no limit on the pitch. However, in this modification method, the upper limit on the depth may be set to 0.1 mm, while the upper limit on the pitch may be set to 0.3 mm, for example. Note that, to reduce moiré fringe patterns, it is desirable that the upper limit on the pitch be at least 0.3 mm. In a third modification, the Fresnel lens surface may be formed so that the lens surface is divided into different regions in the surface. The method for forming the Fresnel lens surface is not limited to the above method, and any optical surface division method may be used.

[0092] (Description of an embodiment in which the lens center of the light distribution lens surface is decentered) The decentering of the lens central axis of the concentric Fresnel lens surface Sf, which is the light distribution lens surface, will be described below. As shown in Fig. 21 , the lens decentering central axis O, which is located at the center of the concentric circle of the concentric Fresnel lens surface Sf, is shifted from the lens areal center C on an HV plane that is aligned with the horizontal direction H and the vertical direction V. The lens areal center C is located at the center of the entire area of ​​the concentric Fresnel lens surface Sf (in this example, the entire area of ​​a rectangle that is long in the horizontal direction H and short in the vertical direction V). From another perspective, the lens areal center C is located at a position that is halfway along each of the lengths of the concentric Fresnel lens surface Sf in the horizontal direction H and the vertical direction V. The lens decentering central axis O is shifted from the lens areal center C in the horizontal direction H by an amount ΔH, and the lens decentering central axis O is shifted from the lens areal center C in the vertical direction V by an amount ΔV. 22 and 23, the head-up display device 100 includes light sources 19, lenses 51, 52, and 53, a liquid crystal display panel 18, and a projection optical system 205 that includes mirrors 21 and 22 and a windshield 201. Display light L from the liquid crystal display panel 18 reaches an eyebox EB through the projection optical system 205. When the viewer's viewpoint is within the eyebox EB, the viewer can view a virtual image W. 22 and 23, the concentric Fresnel lens surface Sf is shown in a non-Fresnel shape.

[0093] As shown in FIGS. 21 and 23, the amount of deviation ΔH and the direction of deviation in the horizontal direction H are determined by the emission angles αh1 and αh2 of the display light L from the liquid crystal display panel 18. The emission angles αh1 and αh2 are angles formed by the outermost rays La and Lb of the display light L in the horizontal direction H with respect to the optical axis center Lc (the central display light, a line connecting the center of the screen of the liquid crystal display panel 18 and the center of the eyebox EB, also called a Gatley). The rays La and Lb are rays of the display light L that trace back from the center position Ec of the eyebox EB. The lens area center C is located on an extension of the optical axis center Lc. The light ray La is a light ray that corresponds to a pixel at the left edge of the virtual image W as seen by the viewer, and the light ray Lb is a light ray that corresponds to a pixel at the right edge of the virtual image W as seen by the viewer. The emission angle αh1 is the angle formed by the light ray La with respect to the optical axis center Lc, and the emission angle αh2 is the angle formed by the light ray Lb with respect to the optical axis center Lc. The output angles αh1 and αh2 are different from each other due to the influence of the shape of the windshield 201, which is asymmetric in the lateral direction H, and the tilt of the projection optical system 205. The lens decentering central axis O is decentered in accordance with the different output angles αh1 and αh2. Specifically, the lens decentering central axis O is decentered from the lens area center C toward the smaller of the output angles αh1 and αh2. In the example of FIG. 21 , the output angle αh2 is set to be smaller than the output angle αh1, i.e., "αh2<αh1." Therefore, the deviation amount ΔH and the lens decentering central axis O are set closer to the light ray Lb than the lens area center C. The greater the difference between the output angles αh1 and αh2, the greater the deviation amount ΔH is set. If the exit angle αh1 is smaller than the exit angle αh2, the deviation amount ΔH and the lens decentering central axis O are set closer to the ray La side than the lens area center C. Furthermore, if the emission angles αh1 and αh2 are the same, the deviation amount ΔH is set to zero.

[0094] As shown in FIGS. 21 and 22, the amount of deviation ΔV and the direction of deviation in the vertical direction V are determined by the emission angles αv1 and αv2. The emission angles αv1 and αv2 are angles formed by the outermost rays Ld and Le of the display light L in the vertical direction V with respect to the optical axis center Lc. The light ray Ld corresponds to a pixel at the upper end of the virtual image W as seen by the viewer, and the light ray Le corresponds to a pixel at the lower end of the virtual image W as seen by the viewer. The light rays Ld and Le are rays that travel back along the display light L from the center position Ec of the eyebox EB. The emission angle αv1 is the angle formed by the light ray Ld with respect to the optical axis center Lc, and the emission angle αv2 is the angle formed by the light ray Le with respect to the optical axis center Lc. The emission angles αv1 and αv2 are different from each other due to the influence of the shape of the windshield 201, which is asymmetric with respect to the vertical direction V, and the inclination of the projection optical system 205. The lens decentering central axis O is decentered in accordance with the different emission angles αv1 and αv2. Specifically, the lens decentering central axis O is decentered from the lens area center C toward the smaller of the output angles αv1 and αv2. In the example of FIG. 21, the output angle αv1 is set to be smaller than the output angle αv2, i.e., αv1<αv2. Therefore, the deviation amount ΔV and the lens decentering central axis O are set closer to the light ray Ld side than the lens area center C. The deviation amount ΔV is set to be larger as the difference between the output angles αv1 and αv2 increases. If the exit angle αv2 is smaller than the exit angle αv1, the deviation amount ΔV and the lens decentering central axis O are set closer to the ray Le than the lens area center C. Furthermore, if the emission angles αv1 and αv2 are the same, the deviation amount ΔV is set to zero.

[0095] Next, a method for determining the lens decentering central axis O will be described. This method is carried out by experiment or simulation. First, prepare a light distributing lens whose lens eccentricity central axis O is not eccentric, and find the emission angles αh1, αh2, αv1, and αv2 of this light distributing lens. From these emission angles αh1, αh2, αv1, and αv2, find the deviation amounts ΔH and ΔV as described above, and determine the lens eccentricity central axis O.

[0096] The head-up display device 100 according to this embodiment, model 1 and model 5, is a cross optical system that folds the display light L twice in the vertical direction V by two mirrors 21 and 22, i.e., vertical folding, with two folds, and crosses the display light L in the vertical direction V at a cross point CP, as described in the first embodiment with reference to FIG. 1 . In this model 1, for example, the output angle αh1 may be set to 6.6 to 7.0°, preferably about 6.8°. The output angle αh2 may be set to 5.0 to 5.4°, preferably about 5.2°. The output angle αv1 may be set to 3.6 to 4.0°, preferably about 3.8°. The output angle αv2 may be set to 5.7 to 6.1°, preferably about 5.9°. In this model 5, for example, the output angle αh1 may be set to 1.7 to 2.1°, preferably about 1.9°. The output angle αh2 may be set to 7.0 to 7.4°, preferably about 7.2°. The output angle αv1 may be set to 6.7 to 7.1°, preferably about 6.9°. The output angle αv2 may be set to 6.9 to 7.3°, preferably about 7.1°.

[0097] Furthermore, the head-up display device 100 may be a model 2 that is vertically folded, has one folding back, and is a non-cross optical system that does not allow cross-sectional illumination of the display light L. In this model 2, for example, the emission angle αh1 may be set to 13.8° to 14.2°, preferably approximately 14.0°. The emission angle αh2 may be set to 12.7° to 13.1°, preferably approximately 12.9°. The emission angle αv1 may be set to 2.2° to 2.6°, preferably approximately 2.4°. The emission angle αv2 may be set to 2.6° to 3.0°, preferably approximately 2.8°.

[0098] Furthermore, the head-up display device 100 may be a non-cross optical system that folds vertically twice and does not allow cross-sectional illumination of the display light L, as in models 3 and 4. In model 3, for example, the emission angle αh1 may be set to 11.4° to 11.8°, preferably approximately 11.6°. The emission angle αh2 may be set to 12.0° to 12.4°, preferably approximately 12.2°. The emission angle αv1 may be set to 1.4° to 1.8°, preferably approximately 1.6°. The emission angle αv2 may be set to 1.3° to 1.7°, preferably approximately 1.5°. Furthermore, in this model 4, for example, the output angle αh1 may be set to 17.1 to 17.5°, preferably about 17.3°. The output angle αh2 may be set to 14.6 to 15.0°, preferably about 14.8°. The output angle αv1 may be set to 4.5 to 4.9°, preferably about 4.7°. The output angle αv2 may be set to 4.8 to 5.2°, preferably about 5.0°. The above numerical values ​​for models 1 to 5 are examples and can be changed as appropriate.

[0099] (Modification of the embodiment in which the lens center of the light distribution lens surface is decentered) In the above embodiment, a concentric Fresnel lens surface Sf in which a concave lens is Fresnelized is used as the light distribution lens surface (field lens surface), but it does not have to be Fresnelized. For example, the entire light distributing lens surface may have a single concave, convex, spherical, toroidal, or biconic surface. In these cases, the lens decentering central axis O passes through the lens vertex where the inclination of the lens surface with respect to the HV plane is minimum. For example, if the entire lens surface is a concave lens surface, the lens decentering central axis O passes through the deepest position of the concave lens surface, and this lens decentering central axis O is decentered from the lens area center C by a deviation amount ΔH or ΔV. For example, if the entire lens surface is a convex lens surface, the lens decentering central axis O passes through the highest position of the convex lens surface, and this lens decentering central axis O is decentered from the lens area center C by a deviation amount ΔH or ΔV. In the above embodiment, it is preferable that the light distribution lens surface in the cross optical system is formed in a convex shape, which makes it easier to cross the display light L since the light from the light distribution lens surface is converged.

[0100] In the above embodiment, either one of the two deviation amounts ΔH and ΔV may be set to zero. Specifically, the lens decentering central axis O may be separated from the lens area center C only in the horizontal direction H, or may be separated from the lens area center C only in the vertical direction V. In this case, the light distributing lens surface is not limited to a concentric Fresnel lens surface, but may also be a linear Fresnel lens surface. In a configuration in which the lens eccentricity central axis O is separated from the lens area center C only in the vertical direction V, the lens having the light distributing lens surface can be used in both left-hand drive vehicles and right-hand drive vehicles without having to be rotated. In the above embodiment, the projection optical system 205 is composed of mirrors 21 and 22 and a windshield 201, but it may be composed of one or more optical components such as lenses, mirrors, and prisms, and if it is composed of multiple components, they can be combined freely. In the above-described embodiments, the position of the light distributing lens surface can be changed as appropriate. For example, in a configuration in which a condenser lens is used as the third lens 53, a lenticular lens is used as the second lens 52, and a toroidal lens is used as the first lens 51, the above-described light distributing lens surface may be applied to the toroidal surface of the toroidal lens. Furthermore, in a configuration in which a condenser lens is used as the third lens 53, a lenticular lens is used as the second lens 52, and a Fresnel lens is used as the first lens 51, the above-described light distributing lens surface may be applied to the Fresnel lens.

[0101] According to the embodiment described above, the following effects are achieved. (1) The head-up display device 100 projects display light L onto a windshield 201 mounted on a vehicle 200, thereby displaying a virtual image W, which is an example of a projected image visible from within a visible range (eye box EB). The head-up display device 100 includes a light source 19 that emits illumination light IL, a third lens 53 that is an example of a collimating means that collimates the illumination light IL emitted from the light source 19, a concentric Fresnel lens surface Sf that is an example of a light distribution lens surface that distributes the illumination light IL in accordance with the eye box EB, a liquid crystal display panel 18 that is an example of a display panel that receives the illumination light IL and emits display light L, and a projection optical system 205 that includes the windshield 201 and guides the display light L to the eye box EB by reflecting and transmitting the display light L. The concentric Fresnel lens surface Sf is formed such that a lens eccentricity central axis O of the concentric Fresnel lens surface Sf is eccentric from a lens area center C of the entire concentric Fresnel lens surface Sf by deviation amounts ΔH and ΔV. According to this configuration, even if misalignment or unevenness occurs in the display light L due to the projection optical system 205 such as the windshield 201, this can be offset by the lens central axis of the light distribution lens surface being shifted from the center of the lens area, thereby improving the illumination efficiency.

[0102] (2) The direction of the deviation amount ΔV is the vertical direction V, which corresponds to the up-down direction of the virtual image W as seen by the viewer. According to this configuration, the concentric Fresnel lens surface Sf is formed so as to be symmetrical in the horizontal direction H, more precisely, so as to be symmetrical along the vertical direction V and the parallel light traveling direction Z, and with respect to a symmetry plane located at the center of the concentric Fresnel lens surface Sf in the horizontal direction H. This makes it possible to use the head-up display device 100 in both left-hand drive vehicles and right-hand drive vehicles.

[0103] (3) The display light L emitted by the liquid crystal display panel 18 has emission angles αh1, αh2, αv1, and αv2 that are different from one another at the pixels at both ends in the direction corresponding to the vertical direction V of the virtual image W as seen by the viewer, or at the pixels at both ends in the direction corresponding to the horizontal direction H of the virtual image W as seen by the viewer, relative to the optical axis center Lc. The direction of the deviation amount ΔH in the horizontal direction H corresponds to the pixel with the smaller emission angle αh1, αh2 among the pixels at both ends. The direction of the deviation amount ΔV corresponds to the pixel with the smaller emission angle αv1, αv2 among the pixels at both ends. According to this configuration, the decentering of the lens central axis of the light distribution lens surface can effectively offset the deterioration of illumination efficiency due to the shape and tilt of the projection optical system 205. Specifically, the farther away from the lens decentering central axis O on the lens surface, the stronger the light bending effect. Therefore, the lens surface can strengthen the light bending effect on the side where the emission angles αh1, αh2, αv1, αv2 are large, thereby improving illumination efficiency.

[0104] (4) The projection optical system 205 includes a first mirror 21, which is an example of a correction mirror that reflects the display light L and crosses one end and the other end of the display light L in a direction perpendicular to the display light traveling direction after the reflection. The light distribution lens surface of the first mirror 21 is convex. In the cross optical system, the display light L reflected by the first mirror 21 converges toward the cross point CP. For this reason, it is desirable to make the light distribution lens surface of the first mirror 21 convex so that the display light L is emitted while converging.

[0105] (5) The light distribution lens surface is formed as a Fresnel lens surface having a Fresnel shape. According to this configuration, the light distributing lens surface is Fresnel shaped, and the lens can be made thinner.

[0106] (Issues in embodiments where the lens center of the light distribution lens surface is decentered) In the configuration described in Patent Document 1, there is room for improvement in the arrangement and type of each lens from the viewpoint of uniformity of illumination on the liquid crystal display panel. More specifically, if the parallel illumination light were diffused using only a lenticular lens without a light distribution lens, the display light would be irradiated over an area wider than the eyebox, resulting in wasted light. By adding a light distribution lens, the diffused illumination light is concentrated and distributed within the visible range, resulting in efficient delivery of the display light to the eyebox, improving light efficiency. Generally, it is considered efficient to position the center of the light distribution lens on the optical axis, and this is how it is configured in Patent Document 1. However, the inventors discovered that this is not optimal in terms of illumination uniformity. The present embodiment has been made in consideration of the above-described circumstances, and aims to provide a head-up display device that can further improve uniformity.

[0107] In order to achieve the above object, the embodiments in which the light distributing lens surface is decentered include the technical ideas described in Supplementary Notes 1 to 5 below.

[0108] (Appendix 1) A head-up display device that displays a projection image visible from within an eye box by projecting display light onto a windshield mounted on a vehicle, a light source that emits illumination light; a collimating means for converting the illumination light emitted from the light source into parallel light; a light distribution lens surface that distributes the illumination light from the collimating means; a display panel that receives the illumination light from the light distribution lens surface and emits display light, the light distributing lens surface is formed such that the lens center of the light distributing lens surface is decentered by a deviation amount from the center position of the entire area of ​​the light distributing lens surface, Head-up display device.

[0109] (Appendix 2) the direction of the deviation is a vertical direction corresponding to the up-down direction of the projected image as seen by the viewer; 10. A head-up display device according to claim 1.

[0110] (Appendix 3) the display light emitted by the display has emission angles different from each other at pixels at both ends in a direction corresponding to a vertical direction or a horizontal direction of the projection image as seen by a viewer with respect to an optical axis center corresponding to the central position, the direction of the deviation amount is a direction corresponding to the pixel having the smaller emission angle among the pixels at both ends; 10. A head-up display device according to claim 1.

[0111] (Appendix 4) the head-up display device includes a projection optical system that guides the display light into the eyebox by at least one of reflecting and transmitting the display light, the projection optical system includes a correction mirror that reflects the display light and, after the reflection, crosses one end and the other end of the display light in a direction perpendicular to the display light traveling direction; The light distributing lens surface is convex. 4. A head-up display device according to any one of claims 1 to 3.

[0112] (Appendix 5) The light distribution lens surface has a Fresnel shape. 4. A head-up display device according to any one of claims 1 to 3. [Explanation of symbols]

[0113] 10,10a…display device 14...case, 14a...opening 15...Lighting equipment 16... Circuit board 17...Light diffusion member 18... liquid crystal display panel, 18a... display surface, 18b... image display area, 18z... dimming zone 19...Light source 21, 21a...first mirror, 22...second mirror 25...Control unit 30...housing, 30c...opening, 31...window 51 to 53... first to third lenses, 51i, 52i... incident surfaces, 51o, 52o... exit surfaces, 53a... convex lens portion 59...Prism sheet 100...Head-up display device 200...vehicle, 201...windshield, 205...projection optical system Sb...Biconic lens array surface, Sb1...Microlens section Sc...cylindrical lens surface, Sc1...cylindrical lens part Sf...concentric Fresnel lens surface, Sf1...ridge, Sf2...Fresnel inclined surface, Sf3...side surface SrH...Horizontal light distribution linear Fresnel lens surface, Sr1...Crown, Sr2...Fresnel inclined surface, Sr3...Side SrV: Vertical light distribution linear Fresnel lens surface, Sra: Peaks, Srb: Fresnel inclined surface, Src: Side H...horizontal direction, V...vertical direction, Z...parallel light propagation direction, θ...light distribution angle, α...angle, C...lens area center, C1, C2, C3...curvature, EB...eye box, J...center plane, L...display light, O...eccentricity central axis, P...lens pitch, Q...light size, R...radial direction, W...virtual image, W1...arrangement direction, L1...extension direction, Lc...optical axis center, CP...cross point, IL...illumination light, ΔH, ΔV...deviation amount, αh1, αh2, αv1, αv2...outgoing angle

Claims

1. A display device that emits display light representing an image, a light source that emits light; a collimating means for collimating the light from the light source; a plurality of light distribution optical surfaces that distribute the light collimated by the collimating means and are arranged on an optical axis of the collimated light; a display surface that receives light distributed by the plurality of light distribution optical surfaces and emits the display light, and is provided in an orientation inclined with respect to the optical axis of the emitted display light, a first light distributing optical surface among the plurality of light distributing optical surfaces is a Fresnel lens surface provided in an orientation along the display surface, a second light distributing optical surface among the plurality of light distributing optical surfaces is a lenticular lens surface or a biconic lens array surface; Display device.

2. There are two second light distributing optical surfaces, one of the two second light distributing optical surfaces is a first lenticular lens surface that distributes light in a vertical direction; the other of the two second light distributing optical surfaces is a second lenticular lens surface that distributes light in the horizontal direction, the first lenticular lens surface is provided in a direction perpendicular to the optical axis of the collimated light, The vertical direction and the horizontal direction are set to be perpendicular to each other while being perpendicular to the optical axis. The display device according to claim 1 .

3. There are two second light distributing optical surfaces, an absolute value of the radius of curvature of a first lenticular lens surface of one of the two second light distributing optical surfaces is set to be equal to or greater than an absolute value of the radius of curvature of a second lenticular lens surface of the other of the two second light distributing optical surfaces that is located farther from the display surface than the first lenticular lens surface; The display device according to claim 1 .

4. A display device according to any one of claims 1 to 3; a mirror that reflects the display light from the display device, the mirror reflects the display light so that the upper and lower ends of the display light, which are both ends in the vertical direction, intersect; the Fresnel lens surface serving as the first light distributing optical surface is a linear Fresnel lens surface obtained by converting a convex lens that extends linearly with zero curvature in the horizontal direction and has a convex shape in the vertical direction into a Fresnel lens, the vertical direction and the horizontal direction are set to be perpendicular to each other while being perpendicular to the optical axis of the collimated light, Head-up display device.

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