JP7314873B2 - virtual image display - Google Patents

Description

The present disclosure relates to virtual image display devices.

2. Description of the Related Art A virtual image display device that reflects display light with a translucent member and visually displays a virtual image of the display light is conventionally known.

For example, the virtual image display device disclosed in Patent Document 1 has a liquid crystal panel that forms an image by transmission of illumination light condensed by a two-stage lens and emits display light of the image. Here, illumination light is generated from a set of light source elements with different emission colors. This makes it possible to adjust the display color of the virtual image.

JP 2019-164285 A

However, in the virtual image display device disclosed in Japanese Patent Laid-Open No. 2002-200010, illumination light is condensed over the entire area of the liquid crystal panel by a two-stage lens common to all light source elements. Therefore, the illumination light from the light source element located close to the optical axis of the two-stage lens and the illumination light from the light source element located far away from the optical axis are insufficiently mixed in color, which causes color unevenness or color shift in the display light, thereby reducing the visibility of the virtual image.

Accordingly, an object of the present disclosure is to provide a virtual image display device that enhances the visibility of virtual images.

Technical means of the present disclosure for solving the problems will be described below. It should be noted that the symbols in parentheses described in the claims and this column indicate the correspondence with specific means described in the embodiments described in detail later, and do not limit the technical scope of the present disclosure.

One aspect of the present disclosure is
A virtual image display device (100) for visibly displaying a virtual image (VRI) by the display light by reflecting the display light with a translucent member (3),
a lighting unit (40) that emits illumination light;
an image forming unit (20) that forms an image by transmission of illumination light and emits display light of the image;
a light collecting unit (30) for collecting the illumination light toward the image forming unit;
The lighting unit has a light source group (403, 2403) consisting of a set of light source elements (403R, 403G, 403B) that independently emit illumination light of three primary colors, and a light source section (402, 2402 ) that emits illumination light from the light source group to enter the light collection unit,
the light collecting unit has a lens portion ( 31-2) forming a wave-like diffusing surface ( 31-3) so as to diffuse the illumination light within an angular space (θ) for condensing the illumination light incident on the image forming unit;
The light source elements of the three primary colors in the light source group of each light source unit are arranged side by side in the linear direction (Yd),
The diffusing surface presents a wavefront shape in which waves travel along a straight line.
Another aspect of the present disclosure is
A virtual image display device (100) for visibly displaying a virtual image (VRI) by the display light by reflecting the display light with a translucent member (3),
a lighting unit (40) that emits illumination light;
an image forming unit (20) that forms an image by transmission of illumination light and emits display light of the image;
a light collecting unit (30) for collecting the illumination light toward the image forming unit;
The lighting unit has a light source group (3403) consisting of a set of light source elements (403R, 403G, 403B) that independently emit illumination light of three primary colors, and a light source section (3402) that emits illumination light incident on the light collection unit from the light source group,
The light collecting unit has a lens portion (3312) forming a wave-like diffusing surface (3313) so as to diffuse the illumination light within an angular space (θ) for condensing the illumination light incident on the image forming unit,
The light source elements of the three primary colors in the light source group of each light source unit are arranged to be shifted in at least one of the linear direction (Yd) and the orthogonal direction (Xd),
The diffusing surface presents a wavy surface in which waves travel along a straight line direction and an orthogonal direction.

In the illumination unit of these aspects, the three primary colors of illumination light incident on the condensing unit are independently emitted from the respective optical elements forming the light source group of the light source section. At this time, in the condensing unit of one aspect, the illuminating light is diffused by the wavy diffusion surface formed by the lens portion in the angular space in which the illuminating light incident on the image forming unit is condensed. Therefore, the illumination light from the light source elements of at least two primary colors in the light source group is color-mixed by such a diffusing and condensing action in the incident lens portion, so that color unevenness and color shift are less likely to occur when emitted as display light from the incident condensing unit. Therefore, it is possible to improve the visibility of the virtual image.

1 is a schematic diagram showing the overall configuration of a virtual image display device according to a first embodiment; FIG. 2 is a cross-sectional view showing the detailed configuration of the virtual image display device according to the first embodiment; FIG. FIG. 3 is a view taken along line III-III in FIG. 2; FIG. 3 is a view taken along line IV-IV in FIG. 2; 3 is a perspective view of the front stage lens array of FIG. 2; FIG. 3 is an enlarged sectional view of FIG. 2; FIG. FIG. 3 is a view taken along line VII-VII of FIG. 2; 3 is an enlarged cross-sectional view taken along line VIII-VIII of FIG. 2; FIG. 3 is an enlarged sectional view of FIG. 2; FIG. FIG. 3 is a view taken along line XX of FIG. 2; 4 is a schematic diagram for explaining an illumination example of the image forming panel of FIG. 3; FIG. FIG. 11 is a diagram showing a virtual image display device according to a second embodiment corresponding to FIG. 10; 3 is a sectional view showing the virtual image display device according to the third embodiment corresponding to FIG. 2; FIG. FIG. 11 is a diagram showing a virtual image display device according to a third embodiment, corresponding to FIG. 10; FIG. 15 is a cross-sectional view showing a modification of FIG. 14; FIG. 7 is a sectional view showing the virtual image display device according to the third embodiment corresponding to FIG. 6; FIG. 3 is a sectional view showing a modification of FIG. 2; FIG. 3 is a sectional view showing a modification of FIG. 2; FIG. 3 is a sectional view showing a modification of FIG. 2; FIG. 3 is a sectional view showing a modification of FIG. 2;

A plurality of embodiments will be described below with reference to the drawings. Note that redundant description may be omitted by assigning the same reference numerals to corresponding components in each embodiment. Moreover, when only a part of the configuration is described in each embodiment, the configurations of the other embodiments previously described can be applied to the other portions of the configuration. Furthermore, not only the combinations of the configurations explicitly specified in the description of each embodiment, but also the configurations of the multiple embodiments can be partially combined even if they are not explicitly specified unless there is a particular problem with the combination.

As shown in FIG. 1, the virtual image display device of 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 an instrument panel 2 of the vehicle 1. Here, the vehicle 1 is understood in a broad sense to include various vehicles such as automobiles, railroad vehicles, aircraft, ships, and non-moving game cabinets. In particular, the vehicle 1 of this embodiment is a four-wheel automobile. The front, rear, up, down, left, and right directions of the HUD 100 are defined with respect to the vehicle 1 on the horizontal plane.

The HUD 100 projects image display light toward the windshield 3 of the vehicle 1 . As a result, the display light reflected by the windshield 3 reaches the visible area EB set in the interior of the vehicle 1 . An occupant whose eye point EP is positioned in the visual recognition area EB in the interior of the vehicle 1 perceives the display light that has reached the visual recognition area EB as a virtual image VRI. In this manner, the HUD 100 displays a virtual image VRI that can be visually recognized by a viewer (hereinafter simply referred to as a viewer) 4 who is an occupant of the vehicle 1, thereby making it possible for the viewer 4 to recognize various types of information. Various types of information displayed by the HUD 100 as a virtual image VRI include, for example, information indicating the state of the vehicle 1 such as vehicle speed and remaining amount of fuel, visibility assistance information, road information, navigation information, and the like.

The visible area EB is a spatial area that can be visually recognized by the viewer 4 when the virtual image VRI displayed by the HUD 100 satisfies a predetermined specification (for example, the entire virtual image VRI has a predetermined brightness or more), and is also called an eye box. The visual recognition area EB is typically set so as to overlap the eyelip set on the vehicle 1 . The eyelip is set in a virtual ellipsoidal shape based on the eye range that statistically represents the spatial distribution of the eyepoints EP of the viewer 4 .

The windshield 3 is a translucent member made of, for example, glass or synthetic resin and formed into a translucent plate. The windshield 3 is positioned above the instrument panel 2 to separate the interior and exterior of the vehicle 1 . The windshield 3 is inclined so as to be spaced apart from the instrument panel 2 from the front to the rear. The rear surface of the windshield 3, which faces the room, forms a smooth concave or flat reflecting surface 3a on which display light projected from the HUD 100 is reflected.

The windshield 3 may be provided with a reflective holographic optical element so as to utilize diffraction reflection with interference fringes instead of surface reflection. Instead of the windshield 3, a combiner as a translucent member may be installed inside the vehicle 1 so that the combiner is provided with the reflecting surface 3a.

As shown in FIG. 1, the HUD 100 includes a light guiding unit 10, an image forming unit 20, a condensing unit 30, and an illumination unit 40. As shown in FIG.

The light guide unit 10 constitutes an optical path L from the image forming unit 20 to the windshield 3 . The light guide unit 10 guides display light projected from the image forming unit 20 toward the windshield 3 . The light guiding unit 10 preferably has an enlarging action of enlarging the image formed by the image forming unit 20 to the virtual image VRI visually recognized by the viewer 4 by a predetermined optical magnification. This is because the magnifying action of the light guide unit 10 contributes to miniaturization.

The light guide unit 10 having such functions includes at least one optical member 11 . The light guide unit 10 is configured by combining a plane mirror (or a curved mirror) 11a and a concave mirror 11b as optical members 11 one by one. Here, the concave mirror 11b provides the above-described magnifying action. Alternatively, for example, the light guide unit 10 may be configured by combining one convex mirror and one concave mirror as the optical member 11, or may be configured by one concave mirror as the optical member 11, or the like. The optical member 11 that constitutes the light guide unit 10 may be fixed or movable.

The image forming unit 20 forms an image that can be formed as a virtual image VRI outside the vehicle 1 and emits display light of the formed image toward the light guide unit 10 . As shown in FIGS. 1 and 2, the image forming unit 20 includes an image display panel 21 and a diffusion panel 22. As shown in FIG.

The image display panel 21 is formed in a plate shape as a whole. The image display panel 21 is a transmissive TFT liquid crystal panel using thin film transistors. The image display panel 21 is of an active matrix type having a plurality of two-dimensionally arranged liquid crystal pixels. Illumination light from the illumination unit 40 is incident on the incident surface 210 , which is one side of the image display panel 21 , through the light collecting unit 30 . Image display light is emitted toward the light guide unit 10 on the optical path L from the exit surface 211 on the opposite side of the image display panel 21 . The image display panel 21 displays and forms an image that becomes this display light.

In the image display panel 21 having such functions, a pair of flat polarizers and a liquid crystal layer sandwiched between the polarizers are laminated in the plate thickness direction. Each polarizer has a transmission axis and a cutoff axis that are orthogonal to each other along both surfaces 210 and 211 of the image display panel 21 . Each polarizer transmits polarized light at azimuthal angles of the transmission axis and absorbs polarized light at azimuthal angles of the block axis. The liquid crystal layer is configured to be able to adjust the polarization of illumination light to be transmitted according to the voltage applied to each liquid crystal pixel. An image is formed by adjusting the ratio of light passing through the polarizer on the exit side, ie, the transmittance, by adjusting the polarization in the liquid crystal layer for each liquid crystal pixel. Particularly in the image display panel 21, a color image can be formed by providing a color filter for each liquid crystal pixel.

As shown in FIGS. 2 and 3, the image display panel 21 is provided with a plurality of pixel regions 212 that are two-dimensionally arranged in predetermined numbers in Xa and Ya directions that are orthogonal to each other. Each pixel area 212 is defined as a rectangular image forming area in which a plurality of liquid crystal pixels are arranged two-dimensionally in the Xa direction and the Ya direction. The number of arrays of pixel regions 212 in the Xa direction may be either “less”, “more”, or “same” as the number of arrays of pixel regions 212 in the Ya direction, but “less” is adopted in the example of FIG.

As shown in FIG. 1, the diffusion panel 22 is made of a rigid transparent material such as glass or resin and formed in a plate-like or thin-film shape as a whole. The diffusion panel 22 is arranged substantially parallel along the entrance surface 210 of the image display panel 21 . The diffusion panel 22 diffuses illumination light incident on the image display panel 21 . Incidentally, the diffusion panel 22 may be configured integrally with the image display panel 21 by providing the incident surface 210 of the image display panel 21 with minute irregularities.

The light collection unit 30 shown in FIGS. 1 and 2 collects the illumination light from the illumination unit 40 toward the image forming unit 20 . The condensing unit 30 includes a front lens array 31 and a rear lens array 32 .

As shown in FIGS. 2 and 4, the front-stage lens array 31 is made of a rigid transparent material such as glass or resin and formed in a plate shape as a whole. The front-stage lens array 31 is a plano-convex lens array. The front lens array 31 has a plurality of front lens portions 312 arranged two-dimensionally in a predetermined number each in the Xb direction and the Yb direction that are orthogonal to each other. The number of arrays of the front-stage lens units 312 in the Xb direction matches the number of arrays of the pixel regions 212 in the Xa direction. The number of arrays of front-stage lens units 312 in the Yb direction matches the number of arrays of pixel regions 212 in the Ya direction. With these configurations, each front lens section 312 is associated with one of the pixel regions 212 at 1:1.

Illumination light from the illumination unit 40 is incident on the front incidence surface 310 that is one side of the front lens portion 312 . Illumination light incident on the front entrance surface 310 is emitted toward the rear lens array 32 from the front exit surface 311 , which is the opposite surface of each front lens portion 312 .

A front entrance surface 310 of each front lens portion 312 shown in FIGS. 2, 5, and 6 has a planar shape substantially perpendicular to the optical axis Al orthogonal to the Xb direction and the Yb direction. The front exit surface 311 of each front lens portion 312 forms a composite surface structure in which the diffusion surface 313 is combined with the virtual base surface Sb. As shown in FIG. 6, the virtual base surface Sb defined for each front lens portion 312 has a convex shape that smoothly curves in any direction including the Xb direction and the Yb direction. Each front-stage lens unit 312 converges the emitted illumination light toward the rear-stage lens array 32 within the angle space θ according to the convex virtual base surface Sb.

A function Zb that expresses the convexity of the virtual base surface Sb in order to exhibit such a light condensing effect is given by the following equation 1, for example. In Equation 1, c is the curvature given to the convex surface. In Equation 1, r is a radius vector (that is, radius) from the optical axis Al for any point on the convex surface. k in Equation 1 is a conic constant. αi in Equation 1 is a free-form surface coefficient.

A diffusion surface 313 defined in each front-stage lens portion 312 presents a wavefront shape in which waves travel outward in the Yb direction from a virtual plane α that includes the optical axis Al and spreads in the Xb direction. Each front-stage lens section 312 diffuses the emitted illumination light toward the rear-stage lens array 32 within the angular space θ according to the wavefront-like diffusion surface 313 .

A function Zw representing the wavefront shape of the diffusion surface 313 for exhibiting such a diffusion action is given by the following equation 2, which defines, for example, a one-dimensional plane wavefront. In Equation 2, Ay is the maximum wavefront amplitude in the Yb direction. In Expression 2, Yw is the separation distance in the Yb direction from the virtual plane α with respect to any point on the wavefront. λy in Equation 2 is the wavefront wavelength in the Yb direction.

From the above, the function Zc representing the composite surface structure in which the diffusion surface 313 is combined with the virtual base surface Sb on the front exit surface 311 of each front lens portion 312 is given by the following equation (3). With the configuration described above, each front lens section 312 diffuses the illumination light incident on the corresponding pixel region 212 of the image forming unit 20 within the range of the angle space θ where the light is collected individually.

As shown in FIGS. 2 and 7, the rear-stage lens array 32 is made of a hard transparent material such as glass or resin and formed in a plate shape as a whole. The rear-stage lens array 32 has a plurality of rear-stage lens sections 322 that are two-dimensionally arranged in predetermined numbers each in the Xc direction and the Yc direction that are orthogonal to each other. The number of arrays of the rear lens sections 322 in the Xc direction matches the number of arrays of the pixel regions 212 in the Xa direction and the number of arrays of the front lens sections 312 in the Xb direction. The number of arrays of the rear lens sections 322 in the Yc direction matches the number of arrays of the pixel regions 212 in the Ya direction and the number of arrays of the front lens sections 312 in the Yb direction. With these configurations, each rear lens section 322 is associated 1:1 with one of the pixel regions 212 and one of the front lens sections 312 .

Each rear lens portion 322 is positioned behind the corresponding front lens portion 312 and shares the optical axis Al. The image display panel 21 and the diffusion panel 22 are inclined with respect to the optical axis Al of each front lens section 312 and each rear lens section 322 . With this inclined arrangement, the Xa direction of the image display panel 21 is defined to be inclined toward the lens arrays 31 and 32 with respect to the Xb direction of the front lens array 31 and the Xc direction of the rear lens array 32 . On the other hand, the Ya direction of the image display panel 21 is defined substantially parallel to the Yb direction of the front lens array 31 and the Yc direction of the rear lens array 32 .

Illumination light from the corresponding front lens portion 312 is incident on the rear entrance surface 320, which is one surface of each rear lens portion 322 shown in FIGS. Illumination light incident on the rear entrance surface 320 is emitted from the rear exit surface 321 , which is the opposite surface of each rear lens unit 322 , toward the corresponding pixel regions 212 .

The rear entrance surface 320 of each rear lens portion 322 shown in FIG. 8 forms a compound surface structure in which forward refractive surface portions 323 and reverse refractive surface portions 324 are alternately arranged outward in the Xc direction from the optical axis Al. The plurality of forward refracting surface portions 323 are formed in stripes (see FIG. 7) that are spaced apart from each other in the Xc direction and extend along the Yc direction. Each forward refracting surface portion 323 corresponds to one of divided portions obtained by dividing the virtual base surface Si1 in the Xc direction with a constant width. Here, the virtual base surface Si1 is defined to be convex on the incident side, for example, in a convex shape. The plurality of reverse refracting surface portions 324 are formed in stripes (see FIG. 7) that are spaced apart from each other in the Xc direction and extend in the Yc direction. Each reverse refracting surface portion 324 corresponds to one of divided portions obtained by dividing the virtual base surface Si2 in the Xc direction. Here, the imaginary base surface Si2 is defined to be concave on the exit side, for example, in the shape of a valley-shaped slope. In the composite surface structure as described above, each forward refracting surface portion 323 refracts the illumination light toward the optical axis Al side in the Xc direction and collimates it to the optical axis Al, while each reverse refracting surface portion 324 refracts the illumination light in the direction opposite to each forward refracting surface portion 323 and mixes it into the collimated light. Note that the collimation means that the illumination light becomes a parallel light flux, and the illumination light does not have to be a perfectly parallel light flux.

The rear exit surface 321 of each rear lens portion 322 shown in FIG. 9 forms a compound surface structure in which forward refractive surface portions 325 and reverse refractive surface portions 326 are alternately arranged outward in the Yc direction from the optical axis Al. The plurality of forward refracting surface portions 325 are formed in stripes (see FIG. 7) that are spaced apart from each other in the Yc direction and extend along the Xc direction. Each forward refracting surface portion 325 corresponds to one of divided portions obtained by dividing the virtual base surface So1 in the Yc direction. Here, the virtual base surface So1 is defined to be convex toward the exit side, for example, in a convex shape. The plurality of reverse refracting surface portions 326 are formed in stripes (see FIG. 7) that are spaced apart from each other in the Yc direction and extend in the Xc direction. Each reverse refracting surface portion 326 corresponds to one of divided portions obtained by dividing the virtual base surface So2 in the Yc direction by a constant width. Here, the virtual base surface So2 is defined to be concave on the incident side, for example, in the shape of a valley-shaped slope. In the composite surface structure as described above, each forward refracting surface portion 325 refracts the illumination light toward the optical axis Al side in the Yc direction and collimates it to the optical axis Al, while each reverse refracting surface portion 324 refracts the illumination light in the direction opposite to each forward refracting surface portion 323 and mixes it into the collimated light.

From the above configuration, the light collecting unit 30 individually collects illumination light incident on each of the pixel regions 212 in the image forming unit 20 by the cooperation of the front lens portion 312 and the rear lens portion 322 corresponding to the respective pixel regions 212.

The illumination unit 40 shown in FIGS. 1 and 2 emits illumination light that illuminates the image forming unit 20 through the light collecting unit 30 . As shown in FIGS. 1, 2, and 10, the illumination unit 40 has a plurality of light source sections 402 that are two-dimensionally arranged in predetermined numbers in the Xd direction and the Yd direction that are orthogonal to each other. The number of arrays of the light source units 402 in the Xd direction matches the number of arrays of the pixel regions 212 in the Xa direction, the number of arrays of the front lens units 312 in the Xb direction, and the number of arrays of the rear lens units 322 in the Xc direction. The number of arrays of the light source units 402 in the Yd direction matches the number of arrays of the pixel regions 212 in the Ya direction, the number of arrays of the front lens units 312 in the Yb direction, and the number of arrays of the rear lens units 322 in the Yc direction. With these configurations, each light source unit 402 is associated 1:1 with one of the pixel regions 212 , one of the front lens units 312 , and one of the rear lens units 322 .

As shown in FIGS. 2 and 10, each light source unit 402 is composed of a group of light sources 403 having the same configuration. A light source group 403 of each light source unit 402 is defined by a set of light source elements 403R, 403G, and 403B that independently emit illumination light of three primary colors of red, green, and blue (RGB). In each light source unit 402, the three primary color light source elements 403R, 403G, and 403B forming the light source group 403 are formed of individual LED bare chips and packaged in common.

In each light source section 402, RGB three primary color light source elements 403R, 403G, and 403B are arranged one-dimensionally along the Yd direction as a linear direction. In particular, the Yd direction in which the light source elements 403R, 403G, and 403B are aligned on a straight line corresponds to the vertical direction Dv (see FIG. 1) of the virtual image VRI. Among the light source elements 403R, 403G, and 403B, the one primary color light source element (403G in FIGS. 2 and 6) located in the middle in the Yd direction is arranged on the common optical axis Al of the corresponding front lens section 312 and rear lens section 322.

Further, the light source elements 403R, 403G, and 403B are arranged closer to the condensing unit 30 than the combined focal point of the corresponding front lens section 312 and rear lens section 322 in the direction along the optical axis Al of the corresponding front lens section 312 and rear lens section 322, respectively. In addition, the light source elements 403R, 403G, and 403B are arranged closer to the light collecting unit 30 in the direction along the optical axis Al of the corresponding front lens portion 312 than the focal length Pb (see FIG. 6) of the virtual base surface Sb for the corresponding lens portion 312.

In the light source group 403 of each light source unit 402 shown in FIG. 2, the intensity peak directions in which the light emission intensities of the light source elements 403R, 403G, and 403B are maximized are set substantially parallel along the optical axis Al of the corresponding front-stage lens unit 312 and rear-stage lens unit 322. Under this setting, the Xd direction of the illumination unit 40 is defined substantially parallel to the Xb direction of the front lens array 31 and the Xc direction of the rear lens array 32, and is defined to be inclined with respect to the Xa direction of the image display panel 21. On the other hand, the Yd direction of the illumination unit 40 is defined substantially parallel to 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 .

In the light source group 403 of each light source unit 402, illumination light emitted from at least one primary color light source element among the three primary color light source elements 403R, 403G, and 403B is sequentially incident on the corresponding front lens unit 312 and rear lens unit 322. That is, the lighting unit 40 emits illumination light sequentially incident on each pair of corresponding lens portions 312 and 322 from the light source group 403 of the light source portion 402 individually corresponding to each of the lens portions 312 and 322 .

As shown by white in FIG. 11, a pixel region 212 corresponding to the light source unit 402 in which all the light source elements 403R, 403G, and 403B of the three primary colors in the light source group 403 emit light is illuminated by white light in which the three primary colors are mixed. As indicated by dot hatching in FIG. 11, among the light source elements 403R, 403G, and 403B in the light source group 403, a pixel region 212 corresponding to the light source section 402 in which the two primary color light source elements emit light and the one primary color light source element turns off is illuminated by the mixed light of the two primary colors. As shown by cross hatching in FIG. 11, among the light source elements 403R, 403G, and 403B in the light source group 403, a pixel region 212 corresponding to the light source section 402 in which the light source element of one primary color emits light and the light source element of two primary colors is extinguished is illuminated by the monochromatic light of the one primary color.

(Effect)
The effects of the first embodiment described above will be described below.

In the lighting unit 40 of the first embodiment, three primary color illumination lights incident on the light collection unit 30 are independently emitted from the optical elements 403R, 403G, and 403B forming the light source group 403 of the light source section 402 . At this time, in the condensing unit 30 of the first embodiment, the illumination light is diffused by the wavefront diffusion surface 313 formed by the front lens portion 312 in the angle space θ in which the illumination light incident on the image forming unit 20 is condensed. Therefore, the illumination light from the light source elements of at least two primary colors in the light source group 403 is color-mixed by such a diffusion and condensing action of the incident lens portion 312, so that color unevenness and color shift are less likely to occur when emitted as display light from the incident light collecting unit 30. Therefore, it is possible to improve the visibility of the virtual image VRI.

According to the first embodiment, the light source elements 403R, 403G, and 403B of the three primary colors in the light source group 403 of each light source section 402 are arranged side by side in the Yd direction as the linear direction. Therefore, in the front-stage lens portion 312 that exhibits a diffusing and condensing action, illumination light is easily mixed in the Yb direction along the Yd direction in which the light source elements 403R, 403G, and 403B are aligned. Therefore, color unevenness and color shift are less likely to occur in the mixed display light, and the visibility of the virtual image VRI can be improved.

According to the first embodiment, the diffusing surface 313 exhibits a wavy surface shape in which waves travel in the Yb direction along the Yd direction as the linear direction. As a result, in the front lens section 312, the light source elements 403R, 403G, and 403B can promote the color mixing of the illumination light in the Yd direction in which the light source elements 403R, 403G, and 403B are arranged side by side by the diffusing and condensing action. Therefore, it is possible to effectively suppress the color unevenness and color deviation of the mixed display light, and improve the visibility of the virtual image VRI.

According to the first embodiment, the Yd direction as the linear direction in which the light source elements 403R, 403G, and 403B of the three primary colors are arranged in the light source group 403 of each light source unit 402 corresponds to the vertical direction Dv of the virtual image VRI. According to this, in the vertical direction Dv in which the eyeball of the viewer 4 viewing the virtual image VRI is difficult to move, color shift due to the movement of the mixed display light is less likely to occur. On the other hand, the three primary color light source elements 403R, 403G, and 403B in the light source group 403 are not aligned in the Xd direction corresponding to the left-right direction Dh (see FIG. 1) of the virtual image VRI in which the eyeball of the viewer 4 tends to move. Therefore, in the mixed display light, a color shift caused by the movement of the eyeball of the viewer 4 is unlikely to occur in the first place. For these reasons, it is possible to ensure the reliability of the effect of enhancing the visibility of the virtual image VRI.

According to the condensing unit 30 of the first embodiment, a plurality of front-stage lens portions 312 are arranged so as to form a diffusion surface 313 for diffusing the individually condensed illumination light within the angular space θ for individually condensing the illumination light incident on each pixel region 212 arranged in the image forming unit 20. Here, in the lighting unit 40 of the first embodiment, a plurality of light source sections 402 are arranged so that illumination light incident on each front lens section 312 is emitted from individual light source groups 403 . As a result, in the light source group 403 of each light source unit 402, all of the light source elements 403R, 403G, and 403B that independently emit illumination light of the three primary colors can be arranged as close to the optical axis Al of the incident lens unit 312 as possible.

Therefore, when illumination light from at least two primary color light source elements in the light source group 403 of each light source unit 402 is mixed by diffused light collection in the incident lens unit 312 and emitted as display light from the incident pixel region 212, it is difficult to cause color unevenness and color shift in each pixel region 212. In addition, when the illumination light from at least one primary color light source element in the light source group 403 of each light source unit 402 is collected by the diffusing and condensing action of the incident lens unit 312 and emitted as display light from the incident pixel region 212, it is difficult to cause color unevenness and color shift between the pixel regions 212. Furthermore, with the illumination light from the light source elements of one primary color in the light source group 403 of each light source unit 402, the chromaticity of the display light emitted from the incident pixel region 212 becomes vivid. For these reasons, it is possible to improve the visibility of the virtual image VRI.

According to the first embodiment, a plurality of rear lens units 322 are arranged after each front lens unit 312 so that the illumination light incident on each pixel region 212 is separately collected together with the front lens unit 312 . Therefore, in each rear-stage lens portion 322, forward refraction surface portions 325 that collimate the illumination light by refraction and reverse refraction surface portions 326 that refract the illumination light and mix it into the collimated light are alternately formed in the Yd direction as a linear direction. According to this, the illumination light from the light source elements of at least two primary colors in the light source group 403 of each light source unit 402 is easily mixed in the Yd direction in which the elements are arranged due to the diffusing and condensing action of the front lens section 312 and the condensing action of the rear lens section 322 accompanied by mixing into collimated light. Therefore, it is possible to suppress color unevenness and color shift of the display light in each pixel region 212 in particular, and to improve the visibility of the virtual image VRI.

(Second embodiment)
As shown in FIG. 12, the second embodiment is a modification of the first embodiment. In each light source unit 2402 of the second embodiment, the light source elements 403R, 403G, and 403B of the three primary colors forming the light source group 2403 are configured by individual LED bare chips and individually packaged.

According to the second embodiment, the light source elements 403R, 403G, and 403B of the three primary colors in the light source group 2403 of each light source section 2402 are packaged independently of each other. As a result, in the light source group 2403 of each light source unit 2402, the position of the independent packaging as close as possible to the optical axis Al of the incident lens unit 312 can be individually adjusted with high precision as the positions for arranging the three primary color light source elements 403R, 403G, and 403B. Therefore, it is possible to secure the reliability of the effect of increasing the visibility of the virtual image VRI.

(Third embodiment)
As shown in FIGS. 13 and 14, the third embodiment is a modification of the first embodiment. The light source elements 403R, 403G, and 403B of the three primary colors forming the light source group 3403 in each light source unit 3402 of the third embodiment are arranged two-dimensionally with a shift in at least one of the Yd direction, which is the linear direction, and the Xd direction, which is the orthogonal direction. Here, FIGS. 13 and 14 show an example in which two primary color light source elements (examples of 403R and 403G in the figure) are displaced only in the Xd direction, and the remaining one primary color light source element (example of 403B in the figure) is displaced in both the Xd and Yd directions with respect to the two primary color light source elements.

Here, in particular, the Yd direction in which the light source elements of the two primary colors are arranged to be shifted corresponds to the vertical direction Dv of the virtual image VRI (see FIG. 1 of the first embodiment). In addition, for example, the center of gravity of the triangular area (inside the two-dot chain line in FIG. 14) whose vertices are the centers of the light source elements 403R, 403G, and 403B is arranged on the common optical axis Al (see FIG. 13) of the corresponding front-stage lens portion 312 and rear-stage lens portion 322. In addition to the above, for example, as shown in FIG. 15, the two primary color light source elements (examples of 403R and 403G in the drawing) may be shifted only in the Yd direction, and the remaining one primary color light source element (example of 403B in the drawing) may be shifted in both the Xd and Yd directions with respect to the two primary color light source elements. The light source elements 403R, 403G, and 403B in the light source group 3403 of each light source unit 3402 are commonly packaged as in the first embodiment, but may be independently packaged according to the second embodiment.

A front exit surface 311 of each front lens portion 3312 shown in FIG. 16 forms a composite surface structure in which a virtual base surface Sb similar to that of the first embodiment is combined with a diffusion surface 3313 different from that of the first embodiment. A diffusing surface 3313 defined in each front lens portion 3312 exhibits a wavefront shape in which waves travel outward at least in the Xc direction and the Yb direction from the optical axis Al. Each front-stage lens portion 3312 diffuses the emitted illumination light toward the rear-stage lens array 32 within the angular space θ according to the wavefront diffusion surface 3313 .

A function Zw representing the wavefront shape of the diffusing surface 3313 to exhibit such a diffusing action may be given by the following equation 4, which defines, for example, a two-dimensional plane wavefront. In Equation 4, Ax and Ay are the wavefront maximum amplitudes in the Xb and Yb directions, respectively. In Equation 4, Xw is the separation distance in the Xb direction from the virtual plane β for any point on the wavefront. Here, the virtual plane β is defined orthogonal to the virtual plane α as a plane including the optical axis Al and extending in the Yb direction. In Equation 4, Yw is the separation distance in the Yb direction from the virtual plane α for any point on the wavefront. In Equation 4, λx and λy are wavefront wavelengths in the Xb and Yb directions, respectively.

The function Zw, which describes the wavefront shape of the diffusing surface 3313, may be given by Equation 5 below, which defines, for example, a non-attenuating spherical wavefront. In Expression 5, A is the maximum wavefront amplitude in any direction around the optical axis Al including the Xb and Yb directions. In Expression 5, Xw and Yw are distances in the Xb and Yb directions from the virtual planes β and α regarding arbitrary points on the wavefront. In Equation 5, λ is the wavefront wavelength in any direction around the optical axis Al including the Xb and Yb directions.

The function Zw, which describes the wavefront shape of the diffusing surface 3313, may be given by Equation 6 below, which defines, for example, an attenuating spherical wavefront. In Equation 6, A is the maximum wavefront amplitude in any direction around the optical axis Al including the Xb and Yb directions. In Equation 6, Xw and Yw are distances in the Xb and Yb directions from virtual planes β and α with respect to arbitrary points on the wavefront. In Equation 6, λ is the wavefront wavelength in any direction around the optical axis Al including the Xb and Yb directions.

A function Zw representing the wavefront shape of the diffusing surface 3313 may be given by Equations 7-9 below, which define, for example, a sinc wavefront. In Equations 8 and 9, Ax and Ay are the wavefront maximum amplitudes in the Xb and Yb directions, respectively. In Equations 8 and 9, Xw and Yw are distances in the Xb and Yb directions, respectively, from the virtual planes β and α regarding arbitrary points on the wavefront. In Equations 8 and 9, λx and λy are wavefront wavelengths in the Xb and Yb directions, respectively.

A function Zw representing the wavefront shape of the diffuser surface 3313 may be given by the following equation (10), which defines, for example, a composite two-dimensional plane wavefront. In Equation 10, j is an integer from 1 to N, or a suffix represented by the integer, where N is the composite number of wavefronts. In Equation 10, Axj and Ayj are the wavefront maximum amplitudes in the Xb and Yb directions, respectively. In Equation 10, Xw and Yw are the separation distances in the Xb and Yb directions from the virtual planes β and α regarding arbitrary points on the wavefront. In Equation 10, λx and λy are wavefront wavelengths in the Xb and Yb directions, respectively. Note that when N=1 in Equation 10, it corresponds to Equation 4 above.

Here, in the case of the above equations 4, 7 to 9, 10, the maximum amplitudes Ax, Axj in the Xb direction may be different from the maximum amplitudes Ay, Ayj in the Yb direction, which is "smaller", "larger", or "same". If the maximum amplitudes Ax and Axj are different from the maximum amplitudes Ay and Ayj, the illumination light is given an anisotropic diffusion effect.

According to the third embodiment, the light source elements 403R, 403G, and 403B of the three primary colors in the light source group 3403 of each light source unit 3402 are arranged to be shifted in at least one of the Yd direction, which is the linear direction, and the Xd direction, which is the orthogonal direction. Therefore, in the front lens section 3312 having the diffusing surface 3313 and exerting a diffusing and condensing action, the illumination colors are easily mixed in the Yb and Xb directions along the mutually shifted directions of the light source elements 403R, 403G, and 403B. Therefore, color unevenness and color shift are less likely to occur in the mixed display light, and the visibility of the virtual image VRI can be improved.

Furthermore, the diffusing surface 3313 according to the third embodiment presents a wavy surface in which waves travel in Yb and Xb directions along the Yd direction as the linear direction and the Xd direction as the orthogonal direction. As a result, in the front lens portion 3312 having the diffusion surface 3313, the light source elements 403R, 403G, and 403B can promote the color mixing of the illumination light in the mutually shifted directions by the diffusing and condensing action. Therefore, it is possible to effectively suppress the color unevenness and color deviation of the mixed display light, and improve the visibility of the virtual image VRI.

(Other embodiments)
Although a plurality of embodiments have been described above, the present disclosure is not to be construed as being limited to those embodiments, and can be applied to various embodiments within the scope of the present disclosure.

In the modification shown in FIG. 17, the rear lens array 32 may not be provided. As shown in FIG. 18, in a modification, at least one of the rear entrance surface 320 and the rear exit surface 321 in the rear lens array 32 may be configured by a Fresnel lens surface. As shown in FIG. 19 , in a modification, the image display panel 21 and the diffusion panel 22 may be arranged substantially perpendicular to the optical axis Al of each front lens section 312 and each rear lens section 322 .

As shown in FIG. 20, in the lens portions 312 and 3312 of the modified example, a composite surface structure of the diffusion surfaces 313 and 3313 and the virtual base surface Sb may be formed on the front incident surface 310 (this figure is an example of the diffusion surface 313). In this case, the virtual base surface Sb on which the diffusion surfaces 313 and 3313 similar to those in the first embodiment are synthesized may have a planar shape substantially perpendicular to the optical axis Al. Further, in this case, the front exit surface 311 of the lens portions 312 and 3312 may have a convex shape that curves smoothly in any direction including the Xb direction and the Yb direction.

The front-stage lens array 31 of the modified example may be a TIR lens array in which a compound surface structure of diffusion surfaces 313, 3313 and a virtual base surface Sb is formed in lens portions 312, 3312. FIG. A diffusion surface 3313 according to the third embodiment may be applied to the front lens portion 312 of the modified example. The diffusion surface 313 according to the first embodiment may be applied to the front lens portion 3312 of the modified example.

In the image display panel 21 of the modified example, the pixel regions 212 may be one-dimensionally arranged in one row in one of the Xa direction and the Ya direction. In the front lens array 31 of the modified example, the front lens portions 312 may be one-dimensionally arranged in one row in one of the Xb direction and the Yb direction. In the rear lens array 32 of the modified example, the rear lens portions 322 may be one-dimensionally arranged in one row in one of the Xc direction and the Yc direction. In a modification, the light source units 402 may be one-dimensionally arranged in one row in one of the Xd direction and the Yd direction.

The Xa direction and the Ya direction in the image display panel 21 of the modified example may be exchanged with each other. The Xc direction and the Yc direction in the rear-stage lens array 32 of the modified example may be exchanged with each other. The Yd direction in each of the light source units 402, 2402, 3402 of the modified example may correspond to the horizontal direction Dh of the virtual image VRI (see FIG. 1 of the first embodiment).

3 translucent member 20 image forming unit 30 light collecting unit 40 lighting unit 100 HUD 212 pixel region 312, 3312 front lens section 313, 3313 diffusion surface 322 rear lens section 325 forward refraction surface section 326 reverse refraction surface section 402, 2402, 3402 light source section 403, 2403, 340 3 light source group 403B, 403G, 403R light source element Dv vertical direction VRI virtual image θ angle space

Claims (6)

A virtual image display device (100) for visibly displaying a virtual image (VRI) of the display light by reflecting the display light with a translucent member (3),
a lighting unit (40) that emits illumination light;
an image forming unit (20) that forms an image by transmission of the illumination light and emits the display light of the image;
a light collecting unit (30) for collecting the illumination light toward the image forming unit;
The lighting unit has a light source group (403, 2403) consisting of a set of light source elements (403R, 403G, 403B) that independently emit the illumination light of the three primary colors, and a light source section (402, 2402 ) that emits the illumination light incident on the light collecting unit from the light source group,
the condensing unit has a lens portion ( 31-2) forming a wave-like diffusing surface ( 31-3) so as to diffuse the illumination light within an angular space (θ) for condensing the illumination light incident on the image forming unit ;
the light source elements of the three primary colors in the light source group of each light source unit are arranged side by side in a linear direction (Yd);
The virtual image display device , wherein the diffusing surface has a wavefront shape in which waves travel along the straight line direction . The virtual image display device according to claim 1 , wherein the linear direction corresponds to the vertical direction (Dv) of the virtual image. A virtual image display device (100) for visibly displaying a virtual image (VRI) of the display light by reflecting the display light with a translucent member (3),
a lighting unit (40) that emits illumination light;
an image forming unit (20) that forms an image by transmission of the illumination light and emits the display light of the image;
a light collecting unit (30) for collecting the illumination light toward the image forming unit;
The lighting unit has a light source group (3403) made up of a group of light source elements (403R, 403G, 403B) that independently emit the illumination light of the three primary colors, and a light source section (3402) that emits the illumination light incident on the light collection unit from the light source group,
The light collection unit has a lens section (3312) forming a wave-like diffusing surface (3313) so as to diffuse the illumination light within an angular space (θ) for condensing the illumination light incident on the image forming unit,
the light source elements of the three primary colors in the light source group of each of the light source units are displaced from each other in at least one of a linear direction (Yd) and an orthogonal direction (Xd);
The virtual image display device , wherein the diffusing surface exhibits a wave surface shape in which waves travel along the linear direction and the orthogonal direction . The image forming unit has a plurality of pixel regions (212) arranged,
The light collecting unit has a plurality of lens units arranged so as to form the diffusion surfaces (313, 3313) for diffusing the individually collected illumination light within the angle space for individually collecting the illumination light incident on each pixel region,
The virtual image display device according to any one of claims 1 to 3 , wherein the illumination unit has a plurality of the light source units (402, 2402, 3402) arranged so that the illumination light incident on each lens unit is emitted from the individual light source groups (403, 2403, 3403). The condensing unit has a plurality of rear lens sections (322) arranged in a rear stage of the front lens section as the lens section so that the illumination light incident on each pixel region is individually collected together with the front lens section,
5. The virtual image display device according to claim 4 , wherein the rear lens section forms a forward refraction surface section (325) for collimating the illumination light by refraction and a reverse refraction surface section (326) for mixing the illumination light with the collimated light by refraction in the linear direction in which the light source elements of the three primary colors are arranged in the light source groups (403, 2403) of each of the light source sections (402, 2402) alternately. 6. The virtual image display device according to claim 4 , wherein the condensing unit has a plurality of rear lens sections (322) arranged behind the front lens section as the lens section so that the illumination light incident on each pixel region is individually collected together with the front lens section.