Virtual image display device

Abstract

The virtual image display device of the present application is provided with: an illumination unit (40) that emits white illumination light; an image forming unit (20) that forms an image by transmitting the illumination light and emits display light of the image; and a condensing unit (30) that condenses the illumination light to the image forming unit (20). The image forming unit (20) has a plurality of pixel regions (212) arranged. The condensing unit (30) has: a front-stage lens portion (312) in which a plurality of front-stage lens portions are arranged to form a wave surface-shaped diffusion surface (313) that diffuses illumination light that has independently entered each pixel region (212) in an angle space in which the illumination light is independently condensed, and a rear-stage lens portion (322) in which a plurality of rear-stage lens portions are arranged to intermittently form a refracting surface portion in a direction orthogonal to a respective optical axis (A1), the refracting surface portion refracting the illumination light that has independently entered each pixel region (212) in an angle space in which the illumination light is independently condensed.

Description

[0001] Cross-references to related applications

[0002] This application is based on Japanese Patent Application No. 2020-122212, filed on July 16, 2020, by reference in its entirety to the contents of the base application. Technical Field

[0003] This disclosure relates to a virtual image display device. Background Technology

[0004] Previously, there were known virtual image display devices that reflected display light through light-transmitting components and could visually confirm the display of virtual images formed by the display light.

[0005] For example, the virtual image display device disclosed in Patent Document 1 includes a display that forms an image by transmitting illumination light converged by illumination lenses and emitting display light of the image. Here, the illumination lenses have an arrangement structure in which multiple illumination lenses are arranged to intermittently form lens surfaces that converge illumination light by refraction in directions orthogonal to their respective optical axes. This suppresses uneven illumination on the display.

[0006] Patent Document 1: Japanese Patent No. 6237249

[0007] However, in the virtual image display device disclosed in Patent Document 1, discontinuous surfaces with discontinuously varying surface shapes are formed at the boundaries between the arranged structures. As a result, the illumination light incident on the boundaries of the arranged structures produces sharp, luminous edge light depending on the position of the viewer's perspective, raising concerns about a reduction in the illumination quality that could affect the visibility of the left and right virtual images. Summary of the Invention

[0008] Therefore, the objective of this disclosure is to provide a virtual image display device that improves the visibility of virtual images.

[0009] The technical means of this disclosure used to solve the problem will be described below.

[0010] One aspect of this disclosure is a virtual image display device that reflects display light through a light-transmitting component and can visually confirm the display of a virtual image formed by the display light, comprising:

[0011] The lighting unit emits white light.

[0012] An image forming unit forms an image by transmitting illumination light and emits display light from the image; and

[0013] The focusing unit focuses the illumination light onto the image forming unit.

[0014] An image forming unit has multiple pixel regions arranged in a row.

[0015] The concentrating unit has:

[0016] The front-stage lens section comprises multiple such front-stage lens sections arranged to form a wave-shaped diffusion surface. This diffusion surface diffuses the independently incident illumination light within the angular space where the illumination light converges independently to each pixel region.

[0017] The rear lens section arranges multiple rear lens sections after each front lens section to form refractive surfaces intermittently in an orthogonal direction relative to the optical axis. The refractive surfaces converge illumination light that is independently incident on the angular space of each pixel area through refraction.

[0018] In a light-concentrating unit arranged in multiple rear-stage lens sections, refractive surfaces are intermittently formed in a direction orthogonal to the optical axis, so that illumination light, independently incident on each pixel region of the multiple arranged lens sections in the image forming unit, is converged by refraction within the angular space. Therefore, in a light-concentrating unit arranged in multiple front-stage lens sections, a diffusion surface is formed to diffuse the independently incident illumination light within the angular space where the independently incident illumination light converges on each pixel region. As a result, the illumination light, diffused and focused by each front-stage lens section, appears to expand within the angular space and is incident on the corresponding rear-stage lens section. Consequently, it is difficult to produce sharp edge light due to the boundaries between the rear-stage lens sections. Therefore, illumination quality can be improved, thereby enhancing the visibility of the virtual image. Attached Figure Description

[0019] Figure 1 This is a schematic diagram showing the overall structure of the virtual image display device according to the first embodiment.

[0020] Figure 2 This is a cross-sectional view showing the detailed structure of the virtual image display device according to the first embodiment.

[0021] Figure 3 yes Figure 2 View along line III-III.

[0022] Figure 4 yes Figure 2 IV-IV line view.

[0023] Figure 5 yes Figure 2 A three-dimensional view of the front lens array.

[0024] Figure 6 yes Figure 2 Enlarged sectional view.

[0025] Figure 7 yes Figure 2 View along line VII-VII.

[0026] Figure 8 yes Figure 2 Enlarged sectional view of line VIII-VIII.

[0027] Figure 9 yes Figure 2 Enlarged sectional view.

[0028] Figure 10 yes Figure 2 XX-line view.

[0029] Figure 11 It is used for Figure 3 A schematic diagram illustrating an example of lighting a panel for image formation.

[0030] Figure 12 This is a perspective view of the front-stage lens array in the second embodiment.

[0031] Figure 13 Is with Figure 2 A cross-sectional view corresponding to the virtual image display device of the third embodiment is shown.

[0032] Figure 14 Is with Figure 6 A cross-sectional view corresponding to the virtual image display device of the third embodiment is shown.

[0033] Figure 15 It means Figure 2 A cross-sectional view of a modified example.

[0034] Figure 16 yes Figure 15 Enlarged sectional view.

[0035] Figure 17 It means Figure 2 A cross-sectional view of a modified example.

[0036] Figure 18 It means Figure 2 A cross-sectional view of a modified example. Detailed Implementation

[0037] Hereinafter, several embodiments will be described based on the accompanying drawings. Furthermore, there are instances where repeated descriptions are omitted by using the same reference numerals for corresponding components in each embodiment. Additionally, when only a portion of the structure is described in each embodiment, the structures of other previously described embodiments can be applied to the remaining parts of the structure. Moreover, not only combinations of structures explicitly shown in the descriptions of each embodiment are possible, but structures of multiple embodiments can be partially combined even without explicit representation, provided that such combinations do not cause obstruction.

[0038] like Figure 1 As shown, the virtual image display device in the first embodiment is a head-up display (hereinafter referred to as HUD) 100 configured to be mounted on a vehicle 1 and housed in the dashboard 2 of the vehicle 1. Here, the term "vehicle 1" is broadly interpreted, for example, to include various means of transportation such as airplanes, ships, and stationary game consoles, in addition to automobiles and railway vehicles. In particular, the vehicle 1 in this embodiment is a four-wheeled automobile. Furthermore, the front, rear, up, down, left, and right directions of the HUD 100 are defined based on the vehicle 1 on the horizontal plane.

[0039] The HUD100 projects an image onto the windshield 3 of the vehicle 1. As a result, the reflected light from the windshield 3 reaches a visual confirmation area EB set inside the vehicle 1. An occupant whose viewpoint EP inside the vehicle 1 is located in the visual confirmation area EB will perceive the reflected light as a virtual image VRI. In this way, by displaying a virtual image VRI that can be visually confirmed by a visual observer (hereinafter referred to as a visual observer) 4 who is an occupant of the vehicle 1, the HUD100 enables the visual observer 4 to recognize various information. Among the various information displayed as a virtual image VRI by the HUD100 are, for example, information indicating the status of the vehicle 1 such as vehicle speed and fuel level, vision assistance information, road information, and navigation information.

[0040] The visual confirmation area EB is a spatial area that can be visually confirmed by the visual confirmer 4, based on the virtual image VRI displayed by the HUD100 meeting specified specifications (e.g., the virtual image VRI is at or above a specified brightness level). It is also referred to as the eye movement range (Eye box). Typically, the visual confirmation area EB is set to overlap with the eye movement range set in the vehicle 1. Based on the line of sight range that statistically represents the spatial distribution of the viewpoint EP of the visual confirmer 4, the eye movement range is set as a virtual elliptical shape.

[0041] The windshield 3 is a light-transmitting plate-shaped component, for example, made of glass or synthetic resin. The windshield 3 is located above the dashboard 2, dividing the interior and exterior of the vehicle 1. The windshield 3 is tilted so that the further it is from the dashboard 2, the more it is separated from the dashboard 2. The rear surface of the windshield 3, which forms the interior side, is formed into a smooth concave or flat surface as a reflective surface 3a that reflects light projected from the HUD 100.

[0042] Furthermore, regarding the windshield 3, a structure utilizing diffraction reflection on interference fringes instead of surface reflection is also employed by setting a reflective holographic optical element. Alternatively, instead of the windshield 3, a light-transmitting component can be installed inside the vehicle 1 using a combiner, where a reflective surface 3a is provided.

[0043] like Figure 1 As shown, the HUD100 includes a light guide unit 10, an image forming unit 20, a light focusing unit 30, and an illumination unit 40.

[0044] The light guide unit 10 forms the light path L from the image forming unit 20 to the windshield 3. The light guide unit 10 guides the display light projected from the image forming unit 20 toward the windshield 3. Preferably, the light guide unit 10 has a magnification function that magnifies the image formed by the image forming unit 20 at a predetermined optical magnification into a virtual image VRI that is visually confirmed by the visual observer 4. This is because miniaturization can be achieved through the magnification function of the light guide unit 10.

[0045] The light guide unit 10 with such function is configured to include at least one optical component 11. The light guide unit 10 is constructed by combining a plane mirror (or curved mirror) 11a, which serves as the optical component 11, and a concave mirror 11b. Here, the concave mirror 11b provides the aforementioned magnification effect. Alternatively, the light guide unit 10 may also be a structure combining a convex mirror and a concave mirror as optical components 11, or it may be constructed solely by a concave mirror as an optical component 11. The optical component 11 constituting such a light guide unit 10 can be either fixed or movable.

[0046] The image forming unit 20 forms an image that can be imaged as a virtual image (VRI) outdoors in the vehicle 1, and the display light of the formed image is emitted toward the guide light unit 10. For example... Figure 1 , Figure 2 As shown, the image forming unit 20 is configured to include an image display panel 21 and a diffusion panel 22.

[0047] The image display panel 21 is integrally formed in a plate shape. The image display panel 21 is a transmissive TFT liquid crystal panel using thin-film transistors. The image display panel 21 is an active matrix type with multiple liquid crystal pixels arranged in a two-dimensional pattern. Illumination light from the illumination unit 40 passes through the light-concentrating unit 30 and is incident on the incident surface 210, which is one side of the image display panel 21. The image display light is emitted from the exit surface 211 on the opposite side of the image display panel 21 towards the light guide unit 10 on the light path L. The image display panel 21 displays the image formed by this image display light.

[0048] In this type of image display panel 21, a pair of flat polarizers and a liquid crystal layer sandwiched between them are stacked in the thickness direction. Each polarizer has a mutually orthogonal transmission axis and a blocking axis along two surfaces 210 and 211 of the image display panel 21. Each polarizer transmits polarized light at the azimuth angle of the transmission axis and absorbs polarized light at the azimuth angle of the blocking axis. The liquid crystal layer is configured to adjust the polarization of the transmitted illumination light according to the applied voltage of each liquid crystal pixel. By adjusting the polarization of the light in the liquid crystal layer, the proportion of light transmitted through the polarizer on the emission side, i.e., the transmittance, is adjusted for each liquid crystal pixel, thereby forming an image. Here, particularly in the image display panel 21, a color image can be formed by providing a color filter in each liquid crystal pixel.

[0049] like Figure 2 , Figure 3 As shown, the image display panel 21 has a plurality of pixel regions 212 arranged in two dimensions in mutually orthogonal Xa and Ya directions with predetermined amounts. Each pixel region 212 is defined as a rectangular image forming area formed by a plurality of liquid crystal pixels arranged in two dimensions in both the Xa and Ya directions. The number of pixel regions 212 in the Xa direction can be any one of "fewer," "more," or "the same" than the number of pixel regions 212 in the Ya direction, but... Figure 3 The first embodiment shown employs a "less" structure.

[0050] like Figure 1 As shown, the diffusion panel 22 is integrally formed into a plate or film shape from a rigid transparent material such as glass or resin. The diffusion panel 22 is configured to be substantially parallel to the incident surface 210 of the image display panel 21. The diffusion panel 22 provides a diffusion effect on illumination light incident toward the image display panel 21. Alternatively, the diffusion panel 22 can be integrally formed with the image display panel 21 by providing minor irregularities to the incident surface 210 of the image display panel 21.

[0051] Figure 1 , Figure 2The light-concentrating unit 30 shown focuses the illumination light from the illumination unit 40 onto the image forming unit 20. The light-concentrating unit 30 is configured to include a front lens array 31 and a rear lens array 32.

[0052] like Figure 2 , Figure 4 As shown, the front-stage lens array 31 is integrally formed into a plate shape from a hard, transparent material such as glass or resin. The front-stage lens array 31 is a plano-convex lens array. The front-stage lens array 31 has a plurality of front-stage lens sections 312 arranged in a predetermined number in each of the mutually orthogonal Xb and Yb directions. The number of front-stage lens sections 312 arranged in the Xb direction is the same as the number of pixel regions 212 arranged in the Xa direction. The number of front-stage lens sections 312 arranged in the Yb direction is the same as the number of pixel regions 212 arranged in the Ya direction. Through these structures, each front-stage lens section 312 is established in a 1:1 correspondence with any one of the pixel regions 212.

[0053] Illumination light from illumination unit 40 is incident on front stage incident surface 310, which is one side of front stage lens section 312. Illumination light incident on front stage incident surface 310 is emitted from front stage exit surface 311, which is the opposite side of each front stage lens section 312, toward rear stage lens array 32.

[0054] Figure 2 , Figure 5 , Figure 6 The front-stage incident surface 310 of each front-stage lens section 312 shown presents a planar shape that is substantially perpendicular to the optical axis Al, which is orthogonal to the Xb and Yb directions. In each front-stage lens section 312, the front-stage exit surface 311 is formed into a composite surface structure by combining a diffusion surface 313 on a virtual base surface Sb. Figure 6 As shown, the virtual base surface Sb defined for each pre-lens unit 312 is a convex surface that is smoothly curved in any direction including the Xb and Yb directions. Each pre-lens unit 312 causes the illumination light emitted toward the rear lens array 32 to be focused in the angular space θ according to such a convex virtual base surface Sb.

[0055] To achieve this focusing effect, the function Zb representing the convex shape of the virtual basal surface Sb is given, for example, by Equation 1 below. In Equation 1, c is the curvature given by the convex shape. In Equation 1, r is the radius vector (i.e., radius) relative to the optical axis Al at any point on the convex shape. In Equation 1, k is the quadratic constant. In Equation 1, αi is the freeform surface coefficient.

[0056] [Formula 1]

[0057]

[0058] The diffusion surface 313 defined for each pre-lens unit 312 exhibits a wave-like shape, with the wave traveling outward from the virtual plane α containing the optical axis Al and extending in the Xb direction toward the Yb direction. Each pre-lens unit 312 causes the illumination light emitted toward the rear lens array 32 to diffuse in the angular space θ according to this wave-like diffusion surface 313.

[0059] To achieve this diffusion effect, the function Zw representing the wavefront shape of the diffusion surface 313 is given, for example, by Equation 2, which defines a one-dimensional planar wavefront. In Equation 2, Ay is the maximum amplitude of the wavefront shape in the Yb direction. In Equation 2, Yw is the separation distance in the Yb direction from the virtual plane α, associated with any point of the wavefront shape. In Equation 2, λy is the wavelength of the wavefront shape in the Yb direction.

[0060] [Equation 2]

[0061] Zw = Ay·cos(2π·Yw / λy)

[0062] In summary, the function Zc, representing the composite surface structure formed by the diffusion surface 313 and the virtual base surface Sb in the front-stage emission surface 311 of each front-stage lens unit 312, is given by Equation 3 below. Based on the above structure, each front-stage lens unit 312 diffuses the illumination light independently incident on its corresponding pixel region 212 in the image forming unit 20 within a range converging to its respective focusing angular space θ.

[0063] [Formula 3]

[0064] Zc=Zb+Zw

[0065] like Figure 2 , Figure 7 As shown, the rear lens array 32 is integrally formed into a plate shape from a rigid transparent material such as glass or resin. The rear lens array 32 has a plurality of rear lens units 322 arranged in a predetermined number in each of the mutually orthogonal Xc and Yc directions. The number of rear lens units 322 in the Xc direction corresponds to the number of pixel regions 212 in the Xa direction and the number of front lens units 312 in the Xb direction. The number of rear lens units 322 in the Yc direction corresponds to the number of pixel regions 212 in the Ya direction and the number of front lens units 312 in the Yb direction. Through these structures, each rear lens unit 322 is established in a 1:1 correspondence with any one of the pixel regions 212 and any one of the front lens units 312.

[0066] Each subsequent lens unit 322 is located in the subsequent stage relative to its corresponding preceding lens unit 312 and shares the optical axis A1. The image display panel 21 and the diffusion panel 22 are tilted relative to the optical axis A1 of each preceding lens unit 312 and each subsequent lens unit 322. With this tilting configuration, the Xa direction of the image display panel 21 is defined as tilted towards the lens arrays 31 and 32 relative to the Xb direction of the preceding lens array 31 and the Xc direction of the subsequent lens array 32. On the other hand, the Ya direction of the image display panel 21 is defined as substantially parallel to the Yb direction of the preceding lens array 31 and the Yc direction of the subsequent lens array 32.

[0067] Illumination light from their respective pre-lens sections 312 is incident on... Figures 7-9 The rear stage incident surface 320 is shown as one side of each rear stage lens section 322. Illumination light incident on the rear stage incident surface 320 is emitted from the rear stage exit surface 321, which is the opposite side of each rear stage lens section 322, toward their respective pixel regions 212.

[0068] exist Figure 8 In each of the rear lens sections 322 shown, the rear incident surface 320 forms a composite surface structure with alternating positive refractive surface sections 323 and negative refractive surface sections 324 arranged outwards from the optical axis Al toward the Xc direction. The plurality of positive refractive surface sections 323 are formed as stripes that are discontinuously separated from each other in the Xc direction and extend along the Yc direction (see reference). Figure 7 Each forward refractive surface 323 corresponds to any one of the segments formed by dividing the virtual base surface Si1 with a certain width in the Xc direction. Here, the virtual base surface Si1 is defined as a convex surface, for example, that protrudes towards the incident side. The plurality of reverse refractive surfaces 324 are formed as stripes that are discontinuously separated from each other in the Xc direction and extend along the Yc direction (see reference). Figure 7 Each reverse refractive surface 324 corresponds to any one of the multiple segments formed by dividing the virtual base surface Si2 in the Xc direction. Here, the virtual base surface Si2 is defined as a recessed, for example, valley-shaped slope, etc., towards the emission side. In the composite surface structure as described above, each forward refractive surface 323 converges the illumination light to the optical axis Al side in the Xc direction and parallelizes it with the optical axis Al by refraction. On the other hand, each reverse refractive surface 324 causes the illumination light to be reverse refracted and mixed into the parallelized light with respect to each forward refractive surface 323. In addition, the term "parallelization" means that the illumination light is in a state close to a parallel beam, and does not require the illumination light to be a completely parallel beam.

[0069] In each of the rear lens sections 322 of the first embodiment, the Xc direction, formed alternately and discontinuously by the forward refractive surface section 323 and the reverse refractive surface section 324, corresponds to the left-right direction Dh of the virtual image VRI (see reference). Figure 1In each of the subsequent lens sections 322, a mountain-shaped boundary 328 is formed between the reverse refractive surface 324 and the reverse refractive surface 324 of another adjacent subsequent lens section 322 in the Xc direction. Alternatively, a valley-shaped boundary 328 may be formed between the positive refractive surface 323 of each of the subsequent lens sections 322 and the positive refractive surface 323 of another adjacent subsequent lens section 322 in the Xc direction.

[0070] exist Figure 9 In each of the rear lens sections 322 shown, the rear exit surface 321 forms a composite surface structure in which positive refractive surface sections 325 and negative refractive surface sections 326 are alternately arranged on the outer side from the optical axis A1 toward the Yc direction. The plurality of positive refractive surface sections 325 are formed as stripes that are discontinuously separated from each other in the Yc direction and extend along the Xc direction (see reference). Figure 7 Each forward refractive surface 325 corresponds to any one of the multiple segments formed by dividing the virtual base surface So1 in the Yc direction. Here, the virtual base surface So1 is defined as a convex surface, for example, that protrudes towards the emission side. The multiple reverse refractive surfaces 326 are formed as stripes that are discontinuously separated from each other in the Yc direction and extend along the Xc direction (see reference). Figure 7 Each reverse refractive surface 326 corresponds to any one of the segments formed by dividing the virtual base surface So2 with a certain width in the Yc direction. Here, the virtual base surface So2 is defined as a valley-shaped slope or the like that that is concave towards the incident side. In such a composite surface structure, each forward refractive surface 325 converges the illumination light to the optical axis Al side in the Yc direction and parallels it to the optical axis Al by refraction. On the other hand, each reverse refractive surface 324 refracts the illumination light in the opposite direction to each forward refractive surface 323 and mixes it into the parallelized light.

[0071] In each of the rear lens sections 322 of the first embodiment, the Yc direction, formed alternately and discontinuously by the forward refractive surface section 325 and the reverse refractive surface section 326, corresponds to the vertical direction Dv of the virtual image VRI (see reference). Figure 1 In each of the subsequent lens sections 322, a mountain-shaped boundary 329 is formed between the reverse refractive surface 326 and the reverse refractive surface 326 of another adjacent subsequent lens section 322 in the Yc direction. Alternatively, a valley-shaped boundary 329 may be formed between the positive refractive surface 325 of each of the subsequent lens sections 322 and the positive refractive surface 325 of another adjacent subsequent lens section 322 in the Yc direction.

[0072] Based on the above structure, the light-concentrating unit 30, through cooperation with the front lens section 312 and the rear lens section 322 corresponding to each pixel region 212 in the image forming unit 20, respectively converges the illumination light that is independently incident on each pixel region 212.

[0073] Figure 1 , Figure 2 The illumination unit 40 shown emits illumination light that illuminates the image forming unit 20 after passing through the focusing unit 30. For example... Figure 1 , Figure 2 , Figure 10 As shown, the illumination unit 40 has a plurality of light source units 402 arranged in a predetermined number in each of the mutually orthogonal Xd and Yd directions. The number of light source units 402 in the Xd direction is the same as the number of pixel regions 212 in the Xa direction, the number of front lens units 312 in the Xb direction, and the number of rear lens units 322 in the Xc direction. The number of light source units 402 in the Yd direction is the same as the number of pixel regions 212 in the Ya direction, the number of front lens units 312 in the Yb direction, and the number of rear lens units 322 in the Yc direction. Through these structures, each light source unit 402 is established in a 1:1 correspondence with any one of the pixel regions 212, any one of the front lens units 312, and any one of the rear lens units 322.

[0074] Each light source unit 402 is composed of a light source element that independently emits white illumination light. The light source element of each light source unit 402 uses, for example, bare LED chips such as YAG or KSF. The illuminance of the illumination light of each light source element 402 can be independently set by adjusting the luminous intensity.

[0075] like Figure 6 As shown, the light source elements of each light source unit 402 are arranged on the common optical axis A1 of the corresponding front lens unit 312 and rear lens unit 322. Here, the light source elements of each light source unit 402 are arranged closer to the focusing unit 30 than the combined focal point of these corresponding lens units 312, 322 in the direction along the optical axis A1 of the corresponding front lens unit 312 and rear lens unit 322. At the same time, in the direction along the optical axis A1 of the corresponding front lens unit 312, the light source elements of each light source unit 402 are arranged closer to the focusing unit 30 than the focal length Pb of the virtual base plane Sb associated with the corresponding lens unit 312.

[0076] exist Figure 2In each of the light source units 402 shown, the direction of the peak intensity of the light source element, where the luminous intensity is greatest, is set to be substantially parallel along the optical axis A1 of the corresponding front lens unit 312 and rear lens unit 322. Under this setting, the Xd direction of the illumination unit 40 is defined as substantially parallel along the Xb direction of the front lens array 31 and the Xc direction of the rear lens array 32, and is defined as inclined to the Xa direction of the image display panel 21. On the other hand, the Yd direction of the illumination unit 40 is defined as substantially parallel along the Ya direction of the image display panel 21, the Yb direction of the front lens array 31, and the Yc direction of the rear lens array 32.

[0077] According to the above structure, the illumination light emitted by the light source element of each light source unit 402 is sequentially incident on the corresponding front lens unit 312 and rear lens unit 322. That is, the illumination unit 40 emits illumination light from the light source element of the light source unit 402, which is independently corresponding to each lens unit 312, 322, and each group of illumination light is independently incident on each of these lens units 312, 322.

[0078] like Figure 11 As shown in the blank space, the pixel area 212 corresponding to the light source section 402, which emits light at maximum intensity, is illuminated by white light transmission with maximum illuminance. (As shown in the blank space) Figure 11 As shown in the midpoint shadow, the pixel area 212 corresponding to the light source section 402, which emits light at an intensity lower than the maximum intensity, is illuminated by white light transmission at an illuminance lower than the maximum illuminance. (As shown in the image) Figure 11 As shown by the cross shadow, the pixel area 212 corresponding to the light source section 402 where the light source element is turned off becomes a substantially non-display area that is not illuminated.

[0079] (Effects)

[0080] The effects of the first embodiment described above will be explained below.

[0081] In the multiple rear lens sections 322 arranged in the light-concentrating unit 30 of the first embodiment, the forward refractive surface 325 is intermittently formed in the Yc direction, which is orthogonal to the optical axis A1, so that the illumination light, which is independently incident on each of the multiple pixel regions 212 arranged in the image forming unit 20, is refracted and converged. Therefore, in the multiple front lens sections 312 arranged in the light-concentrating unit 30 of the first embodiment, a diffusion surface 313 is formed so that the independently incident illumination light is diffused in the angular space θ of the converged illumination light independently incident on each pixel region 212. As a result, the illumination light, which is diffused and concentrated by each front lens section 312, appears to expand in the angular space θ and is incident on the corresponding rear lens section 322. As a result, it is difficult to produce edge light that is sharply emitted due to the boundary 329 between the rear lens sections 322. As a result, the illumination quality can be improved and the visibility of the virtual image VRI can be improved.

[0082] In the first embodiment, the diffusion surface 313 exhibits a wave-like shape with the wave direction traveling along the Yb direction, which is an orthogonal direction of the Yc direction. Therefore, in the front lens section 312, in the Yb direction along the Yc direction where the rear lens sections 322 are arranged, the apparent expansion of the illumination light can be promoted through diffusion and focusing. This effectively suppresses edge light caused by the boundary 329 between each rear lens section 322, improving the visibility of the virtual image VRI.

[0083] According to the first embodiment, the Yc direction, which is the orthogonal direction of the rear lens section 322, corresponds to the vertical direction Dv of the virtual image VRI. Therefore, in the horizontal direction Dh of the virtual image VRI, where the eye of the visual observer 4 can easily move relative to the visually confirming virtual image VRI, and in the vertical direction Dv of the virtual image VRI, where the eye is difficult to move, it is inherently difficult for variations in the brightness of the displayed light to occur. Thus, combined with the suppression of edge light, the visibility of the virtual image VRI can be improved.

[0084] In the illumination unit 40 of the first embodiment, a plurality of light source units 402 are arranged such that illumination light is emitted and independently incident on each group of pre-lens units 312 and post-lens units 322. Thus, the illumination light incident from each light source unit 402 onto the corresponding pre-lens unit 312 and subjected to diffusion and focusing effects appears to extend into the corresponding post-lens unit 322 within the angular space θ. This suppresses the incidence of edge light caused by the boundaries 329 between the post-lens units 322 in each pixel region 212, improving the visibility of the virtual image VRI.

[0085] In each of the rear lens sections 322 of the first embodiment, forward refractive surfaces 323 and 325, which parallelize the illumination light through refraction, and reverse refractive surfaces 324 and 326, which refract and mix the illumination light into the parallelized light, are alternately formed in the Xc and Yc directions, which are orthogonal directions. Therefore, in addition to the diffusion and focusing effect in the front lens section 312, the illumination light is further focused by the rear lens section 322 along with the mixing into the parallelized light, making it difficult to generate rim light caused by the boundaries 328 and 329 between the rear lens sections 322. This effectively suppresses rim light and improves the visibility of the virtual image (VRI).

[0086] (Second Implementation)

[0087] like Figure 12 As shown, the second embodiment is a variation of the first embodiment. In the second embodiment, a structure is adopted in which the number of permutations of elements 212, 312, 322, 402 in the Xa, Xb, Xc, Xd directions is "more" than the number of permutations of elements 212, 312, 322, 402 in the Ya, Yb, Yc, Yd directions. Figure 12 Only the front lens section 312 is shown in the figure.

[0088] In this second embodiment, the visual confirmation region EB corresponding to the left-right direction Dh of the virtual image VRI (in the first embodiment) is located in the left-right direction. Figure 1 The aspect ratio on the vertical direction of the paper (in the first embodiment) corresponds to the vertical direction of the visual confirmation area EB in the vertical direction of the virtual image VRI (Dv). Figure 1 The dimensions in the vertical direction are large. Therefore, the windshield 3, which is horizontally elongated in the vehicle 1, can be effectively utilized to provide a virtual image VRI display that improves the visibility in the horizontally elongated visual confirmation area EB.

[0089] (Third Implementation)

[0090] like Figure 13 , Figure 14 As shown, the third embodiment is a variation of the second embodiment. In the third embodiment, the front-stage emission surface 311 of each front-stage lens section 3312 is formed on the same virtual base surface Sb as in the first embodiment, creating a composite surface structure with a diffusion surface 3313 different from that in the first embodiment. The diffusion surface 3313 defined by each front-stage lens section 3312 exhibits a wave-like shape, with waves traveling outward from the optical axis A1 at least in the Xc direction and the Yb direction. Each front-stage lens section 3312 causes the illumination light emitted towards the rear-stage lens array 32 to diffuse within the angular space θ according to this wave-like diffusion surface 3313.

[0091] To achieve this diffusion effect, the function Zw representing the wavefront shape of the diffusion surface 3313 can, for example, be given by Equation 4, which defines a two-dimensional planar wavefront. In Equation 4, Ax and Ay are the maximum amplitudes of the wavefront shape in the Xb and Yb directions, respectively. In Equation 4, Xw is the separation distance from the virtual plane β in the Xb direction associated with any point of the wavefront shape. Here, the virtual plane β, as a surface containing the optical axis Al and extending in the Yb direction, is defined as orthogonal to the virtual plane α. In Equation 4, Yw is the separation distance from the virtual plane α in the Yb direction associated with any point of the wavefront shape. In Equation 4, λx and λy are the wavelengths of the wavefront shape in the Xb and Yb directions, respectively.

[0092] [Formula 4]

[0093] Zw=Ax·cos(2π·Xw / λx)+Ay·cos(2π·Yw / λy)

[0094] The function Zw representing the wavefront shape of the diffusion surface 3313 can also be given, for example, by the following equation 5, which defines a non-attenuating spherical wavefront. In equation 5, A is the maximum amplitude of the wavefront shape in any direction around the optical axis A1, including the Xb and Yb directions. In equation 5, Xw and Yw are the separation distances from the virtual planes β and α, respectively, in the Xb and Yb directions, associated with any point of the wavefront shape. In equation 5, λ is the wavelength of the wavefront shape in any direction around the optical axis A1, including the Xb and Yb directions.

[0095] [Formula 5]

[0096] Zw=A·cos[2π·{(Xw 2 +Yw 2 ) 1 / 2} / λ]

[0097] The function Zw representing the wavefront shape of the diffusion surface 3313 can also be given, for example, by the following equation 6, which defines the attenuating spherical wavefront. In equation 6, A is the maximum amplitude of the wavefront shape in any direction around the optical axis A1, including the Xb and Yb directions. In equation 6, Xw and Yw are the separation distances from the virtual planes β and α, respectively, in the Xb and Yb directions, associated with any point of the wavefront shape. In equation 6, λ is the wavelength of the wavefront shape in any direction around the optical axis A1, including the Xb and Yb directions.

[0098] [Formula 6]

[0099] Zw = [A / {(Xw)] 2 +Yw 2 ) 1 / 2}]·cos[2π·{(Xw 2 +Yw 2 ) 1 / 2} / λ]

[0100] The function Zw representing the wavefront shape of the diffusion surface 313 can also be given, for example, by the following equations 7 to 9, which define the sinc wavefront. In equations 8 and 9, Ax and Ay are the maximum amplitudes of the wavefront shape in the Xb and Yb directions, respectively. In equations 8 and 9, Xw and Yw are the separation distances from the virtual planes β and α in the Xb and Yb directions, respectively, associated with any point of the wavefront shape. In equations 8 and 9, λx and λy are the wavelengths of the wavefront shape in the Xb and Yb directions, respectively.

[0101] [Formula 7]

[0102] Zw=Zx+Zy

[0103] [Formula 8]

[0104] Zx=Ax·{sin(2π·Xw / λx)} / (2π·Xw / λx)

[0105] [Formula 9]

[0106] Zy=Ay·{sin(2π·Yw / λy)} / (2π·Yw / λy)

[0107] The function Zw representing the wavefront shape of the diffusion surface 3313 can also be given, for example, by the following equation 10, which specifies the synthesis of a two-dimensional planar wavefront. In equation 10, j is an integer from 1 to N, or a suffix representing that integer, where the synthesis number of the wavefront is set to N. In equation 10, Axj and Ayj are the maximum amplitudes of the wavefront shape in the Xb and Yb directions, respectively. In equation 10, Xw and Yw are the separation distances from the virtual planes β and α in the Xb and Yb directions, respectively, associated with any point of the wavefront shape. In equation 10, λx and λy are the wavelengths of the wavefront shape in the Xb and Yb directions, respectively. Furthermore, in equation 10, when N = 1, it is equivalent to equation 4 above.

[0108] [Formula 10]

[0109]

[0110] Here, in the cases of Equations 4, 7 to 9, and 10 above, the maximum amplitudes Ax and Axj in the Xb direction can be any one of "smaller," "larger," or "the same" relative to the maximum amplitudes Ay and Ayj in the Yb direction. Where the maximum amplitudes Ax and Axj are different from the maximum amplitudes Ay and Ayj, anisotropic diffusion is applied to the illumination light. Therefore, particularly in the third embodiment, the maximum amplitudes Ax and Axj in the Xb direction, corresponding to the left-right direction Dh of the virtual image VRI, can be set to be "larger" than the maximum amplitudes Ay and Ayj in the Yb direction, corresponding to the up-down direction Dv of the virtual image VRI. Thus, in the third embodiment, a highly visible virtual image VRI can be provided by efficiently diffusing the illumination light toward the horizontally elongated visual confirmation area EB described in the second embodiment.

[0111] Furthermore, the diffusion surface 3313 of the third embodiment exhibits a wave-like shape in which the wave travels at least in the Xb and Yb directions, which are a pair of mutually orthogonal directions Xc and Yc, respectively. Therefore, in the front lens section 3312, in the Xb and Yb directions along the Xc and Yc directions where the rear lens sections 322 are arranged, the apparent expansion of the illumination light can be promoted through diffusion and focusing. This effectively suppresses edge light caused by the boundaries 328 and 329 between the rear lens sections 322, improving the visibility of the virtual image VRI.

[0112] (Other implementation methods)

[0113] The above describes several embodiments, but this disclosure is not limited to these embodiments and can be applied to various embodiments without departing from the spirit of this disclosure.

[0114] like Figure 15 , Figure 16 As shown, in a modified example, in the rear lens array 32, at least one of the rear incident surface 320 and the rear exit surface 321 ( Figure 15 , Figure 16 (Example only of the output surface 321) can also be constructed from a Fresnel lens surface. In this case, instead of at least one of the reverse refractive surface 324 and the reverse refractive surface 326, a connecting surface 327 is formed that is substantially parallel to the optical axis A1, connecting the positive refractive surfaces 323 or the positive refractive surfaces 325. In addition, in this case, a valley-shaped boundary 328 or boundary 329 is formed between at least one of the positive refractive surfaces 323 and 325 in each of the output lens sections 322 and the positive refractive surface 323 or the positive refractive surface 325 of the other output lens section 322 adjacent in the Xc or Yc direction.

[0115] like Figure 17 As shown, in a modified example, the image display panel 21 and the diffusion panel 22 may be arranged substantially perpendicular to the optical axis A1 of each pre-lens section 312 and each post-lens section 322. The pre-lens array 31 in the modified example may also be a TIR lens array with a composite surface structure in which diffusion surfaces 313, 3313 and virtual base surface Sb are formed in the lens sections 312, 3312.

[0116] like Figure 18 As shown, in the modified lens sections 312 and 3312, a composite surface structure of diffusion surfaces 313 and 3313 and a virtual base surface Sb may also be formed on the front-stage incident surface 310 (this figure shows an example of diffusion surface 313). In this case, the virtual base surface Sb of the composite diffusion surfaces 313 and 3313, which are the same as in the first embodiment, may also be a planar shape that is substantially perpendicular to the optical axis A1. In addition, in this case, the front-stage exit surface 311 of the lens sections 312 and 3312 may also be a convex shape that is smoothly curved in any direction including the Xb direction and the Yb direction.

[0117] In the modified image display panel 21, the pixel regions 212 can also be arranged in a single-dimensional column along one of the Xa and Ya directions. In the modified front lens array 31, the front lens units 312 can also be arranged in a single-dimensional column along one of the Xb and Yb directions. In the modified rear lens array 32, the rear lens units 322 can also be arranged in a single-dimensional column along one of the Xc and Yc directions. In the modified example, the light source units 402 can also be arranged in a single-dimensional column along one of the Xd and Yd directions.

[0118] In the modified example, the Xa and Ya directions in the image display panel 21 can also be interchanged. Similarly, the Xc and Yc directions in the rear lens array 32 in the modified example can also be interchanged. Furthermore, the Yd direction in each of the light source units 402, 2402, and 3402 in the modified example can also be aligned with the left-right direction Dh of the virtual image VRI (refer to the first embodiment). Figure 1 )correspond.

Claims

1. A virtual image display device that displays a virtual image formed by display light by reflecting the display light with a light-transmitting member, the virtual image display device comprising: an illumination unit that emits white illumination light; an image forming unit that forms an image by transmitting the illumination light and emits the display light of the image; and a condensing unit that condenses the illumination light to the image forming unit, the image forming unit having a plurality of pixel regions arranged, the condensing unit having: a front-stage lens portion, a plurality of the front-stage lens portions being arranged to form a wave-shaped diffusion surface that diffuses the illumination light independently incident to each of the pixel regions within an angle space in which the illumination light is condensed by refraction; and a rear-stage lens portion, a plurality of the rear-stage lens portions being arranged to form a refractive surface portion intermittently in a direction orthogonal to an optical axis, the refractive surface portion condensing the illumination light independently incident to each of the pixel regions within the angle space by refraction, the diffusion surface exhibiting a wave shape in which a wave travels in a direction along the orthogonal direction.

2. The virtual image display device according to claim 1, wherein the diffusion surface exhibits a wave shape in which a wave travels in a direction along each of a pair of the orthogonal directions orthogonal to each other.

3. The virtual image display device according to claim 2, wherein a maximum amplitude of the waves is different in a direction in which the waves travel along the pair of the orthogonal directions orthogonal to each other.

4. The virtual image display device according to claim 1, wherein the orthogonal direction includes a direction corresponding to a vertical direction of the virtual image.

5. The virtual image display device according to claim 1, wherein the rear-stage lens portion alternately forms a forward refractive surface portion and a reverse refractive surface portion in the orthogonal direction, the forward refractive surface portion being the refractive surface portion that parallelizes the illumination light by refraction, and the reverse refractive surface portion mixing the illumination light into the parallelized light by refraction.

6. The virtual image display device according to any one of claims 1 to 5, wherein the illumination unit has a light source portion, a plurality of the light source portions being arranged to emit the illumination light independently incident to each of a group of the front-stage lens portions and the rear-stage lens portions. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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