WO2020158258A1

WO2020158258A1 - Virtual image display device

Info

Publication number: WO2020158258A1
Application number: PCT/JP2019/050528
Authority: WO
Inventors: 潤也横江
Original assignee: 株式会社デンソー
Priority date: 2019-01-28
Filing date: 2019-12-24
Publication date: 2020-08-06
Also published as: JP2020118935A; JP6984619B2

Abstract

Provided is a virtual image display device that displays a virtual image by projecting the display light of an image onto a projection unit. This virtual image display device comprises: an image display element that has a portion to be illuminated which has longitudinal dimensions larger than lateral dimensions, and displays an image; and a backlight unit that irradiates the portion to be illuminated with light-source light. The backlight unit is equipped with: a light source unit that has light source elements aligned with each other at predetermined intervals in a longitudinal corresponding direction (XD) which corresponds to the longitudinal direction; and a small light source array lens unit (51) that is disposed on the optical path between the light source unit and the portion to be illuminated and has small light source lens elements (52) arranged at a pitch (PIT) smaller than the predetermined interval along a lateral corresponding direction (YD) which corresponds to the lateral direction. In the small light source lens elements (52), the absolute value of the focal length (fay) in the lateral corresponding direction is smaller than the absolute value of the focal length (fax) in the longitudinal corresponding direction.

Description

Virtual image display

Cross-reference to related application

This application is based on Japanese Patent Application No. 2019-012363 filed on January 28, 2019, the description of which is incorporated herein by reference.

The disclosure by this specification relates to a virtual image display device.

Conventionally, a virtual image display device that displays a virtual image by projecting display light of an image on a projection unit is known. The virtual image display device disclosed in Patent Document 1 includes an image display element that displays an image, and a backlight unit that irradiates the image display element with light source light. The display area of the image display element is formed in a rectangular shape.

The backlight unit has a light source, a lens array, a first focus lens, a second focus lens, and the like. The light source is composed of two light emitting diodes (LEDs). The lens array is a lens body formed by arranging a plurality of biconvex lenses vertically and horizontally. The array pitch of these biconvex lenses is sufficiently large.

The backlight unit has at least one of the four surfaces of the first focus lens and the second focus lens as a toroidal surface, and irradiates the light source light according to the shape of the rectangular display area. There is.

Japanese Patent No. 6248473

In the image display device, when an illumination target portion whose longitudinal dimension is set to be larger than its lateral dimension, such as a rectangular shape, is provided, illumination unevenness, and consequently brightness unevenness is reduced. In order to improve the visibility of the virtual image, it is necessary to configure the backlight unit corresponding to the difference in size, that is, the aspect ratio.

In this regard, in Patent Document 1, by providing the focus lens with a toroidal surface, the illumination light is greatly expanded in the longitudinal direction corresponding to the longitudinal direction, and the irradiation range of the light source light is brought close to the shape of the illumination target portion. However, as a result of a detailed study by the inventor, in this embodiment, the optical path length of the focus lens portion tends to be long, and in particular, the optical path aligned with the longitudinal corresponding direction is preferably arranged so that the light source light suitably spreads in the longitudinal corresponding direction. Since the length is set, the problem that the physical size of the device increases is found.

One of the purposes of the disclosure of this specification is to provide a virtual image display device that suppresses an increase in physique while enhancing the visibility of the virtual image.

One of the aspects disclosed herein is a virtual image display device that displays a virtual image by projecting display light of an image onto a projection unit,
An image display element that has an illumination target portion in which the dimension in the longitudinal direction is set to be large with respect to the dimension in the lateral direction, and that displays an image by using the light source light illuminated on the illumination target portion,
A backlight unit for irradiating the illumination target portion with light from the light source;
The backlight unit is
A plurality of light source elements are arranged side by side at a predetermined interval in at least the longitudinal corresponding direction of the lateral corresponding direction corresponding to the lateral direction and the longitudinal corresponding direction corresponding to the longitudinal direction. A light source section that emits light,
A plurality of small light source lens elements arranged on the optical path between the light source section and the illumination target section and arranged at a pitch smaller than the interval along at least the short-side corresponding direction of the short-side corresponding direction and the long-side corresponding direction. And a small light source array lens unit in which each small light source lens element behaves so as to divide the light source light from the light source unit to form a new small light source,
In each small light source lens element, the absolute value of the focal length in the lateral corresponding direction is smaller than the absolute value of the focal length in the longitudinal corresponding direction.

According to such a mode, the small light source array lens unit is formed by arranging a plurality of small light source lens elements. Such small light source lens elements are arranged at a pitch smaller than the distance between the light source elements, and behave so as to divide the light source light from the light source unit to form a small light source. That is, by arranging the small light sources in the direction corresponding to the short side at a small pitch, the small light source array lens unit functions like a linear light source or a planar light source, and the small light source array lens unit is arranged in a plurality of rows aligned in the longitudinal corresponding direction. The light source element behaves like a light source having a width in the longitudinal direction.

On the other hand, in each small light source lens element, the absolute value of the focal length in the lateral direction is smaller than the absolute value of the focal length in the longitudinal direction. Due to the relationship of the focal lengths, the spread angle of the split light source light emitted from each small light source of the small light source lens element in the direction corresponding to the short side becomes a relatively wide angle, so that the light source light can be appropriately spread with a short optical path length. Therefore, it is possible to realize the illumination that matches the dimension of the illumination target portion in the lateral direction. In the longitudinal direction with respect to the lateral direction, the divergence angle of the split light source light emitted from each small light source by the small light source lens element in the longitudinal direction becomes a relatively narrow angle, but the small light source array lens part is already long. It behaves like a light source with a width in the corresponding direction. Therefore, it is possible to realize illumination matched to the dimension of the illumination target portion in the longitudinal direction without spreading the divided light source light from each small light source to the dimension of the illumination target portion in the longitudinal direction. Therefore, it is possible to reduce the necessity of setting a long optical path length in accordance with the longitudinal corresponding direction to illuminate a wider range.

As described above, it is possible to provide a virtual image display device that suppresses the increase in physique while reducing the occurrence of brightness unevenness in the virtual image and increasing the visibility of the virtual image.

It is a figure which shows the mounting state in the vehicle of the head-up display device of 1st Embodiment. FIG. 3 is a diagram showing a vertical cross section along a lateral direction or a Y direction in the display device of the first embodiment. FIG. 3 is a diagram showing a vertical cross section along the longitudinal direction or the X direction in the display device of the first embodiment. It is a perspective view showing the 2nd lens member and the 3rd lens member of a 1st embodiment. It is a figure which shows typically the image point of the small light source by the small light source lens element of 1st Embodiment, an upper stage shows the vertical cross section along an X direction, and a lower stage shows the vertical cross section along a Y direction. It is a schematic diagram for explaining the integrator of the split light source light of the first embodiment. It is a schematic diagram for demonstrating the illumination characteristic of the backlight unit of 1st Embodiment. 8 is a graph for explaining the intensity of illumination light along the VIII-VIII cross section of FIG. 7. It is a perspective view showing the 2nd lens member of a 2nd embodiment. It is a figure corresponding to FIG. 2 in a modification. It is a figure corresponding to FIG. 3 in a modification.

A plurality of embodiments will be described below with reference to the drawings. It should be noted that, in each of the embodiments, corresponding components may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiments described above can be applied to the other part of the configuration. Further, not only the combination of the configurations explicitly described in the description of each embodiment, but unless the combination is particularly hindered, the configurations of the plurality of embodiments can be partially combined even if not explicitly stated. ..

(First embodiment)
As shown in FIG. 1, the virtual image display device according to the first embodiment of the present disclosure is used in a vehicle 1, and a head-up display device (hereinafter, a HUD device) 10 housed in an instrument panel 2 of the vehicle 1 is provided. Is. The HUD device 10 projects the display light of the image toward the projection unit 3 a provided on the windshield 3 of the vehicle 1. Accordingly, the HUD device 10 displays the image as a virtual image VRI that can be visually recognized by an occupant as a viewer. That is, when the display light of the image reflected by the projection unit 3a reaches the visual recognition area EB set inside the vehicle 1, the occupant whose eyepoint EP is located in the visual recognition area EB recognizes various information. be able to.

The various information displayed includes, for example, information indicating the state of the vehicle 1 such as vehicle speed and remaining fuel amount, or navigation information such as visibility assistance information and road information.

In the following, unless otherwise specified, the directions of front, rear, upper, lower, left and right are described with reference to the vehicle 1 on the horizontal plane HP.

The windshield 3 of the vehicle 1 is a transmissive member formed of, for example, glass or synthetic resin in a translucent plate shape, and is arranged above the instrument panel 2. The windshield 3 is arranged so as to be inclined from the instrument panel 2 as it goes from the front to the rear. The windshield 3 forms a projection portion 3a on which the display light of the image is projected in a smooth concave shape or a flat shape. The projection unit 3a does not have to be provided on the windshield 3. For example, a combiner separate from the vehicle 1 may be installed in the vehicle 1, and the combiner may be provided with the projection unit 3a.

The visual recognition area EB is a spatial area that can be visually recognized so that the virtual image VRI displayed by the HUD device 10 satisfies a predetermined standard (for example, the entire virtual image VRI has a predetermined luminance or more), and is also an eye box. Is called. The visual recognition area EB is typically set so as to overlap with the eye lip set in the vehicle 1. The eye lip is set for each eye, and is set as an ellipsoidal virtual space based on the eye range that statistically represents the spatial distribution of the eye point EP of the occupant.

A specific configuration of such a HUD device 10 will be described below. The HUD device 10 includes a housing 11, a display unit 30, a light guide unit 21, and the like.

The housing 11 is made of, for example, synthetic resin or metal and has a hollow shape for housing the display unit 30, the light guide portion 21, and the like, and is installed in the instrument panel 2 of the vehicle 1. The housing 11 has a window portion 12 that is optically opened on the upper surface portion that faces the projection portion 3a. The window 12 is covered with, for example, a dustproof sheet 13 that can transmit display light.

The display 30 displays an image on the display screen 33 and projects the display light of the image toward the light guide unit 21. The display 30 of this embodiment is a transmissive liquid crystal display. The display device 30 has an image display element 31 and a backlight unit 41, and is configured by exposing the display screen 33 to the outside of the casing while accommodating them in a box-shaped casing having a light shielding property.

The light guide section 21 forms an optical path for guiding the display light emitted from the display screen 33 of the display 30. The light guide section 21 has, for example, a plane mirror 22 and a concave mirror 24. The sign of the combined focal length of the light guide section 21 is positive.

The plane mirror 22 has a reflecting surface 23 formed by evaporating aluminum on the surface of a base material made of, for example, synthetic resin or glass. The reflecting surface 23 of the plane mirror 22 is formed into a smooth flat surface. Display light that has entered the plane mirror 22 from the display device 30 is reflected by the reflecting surface 23 toward the concave mirror 24.

The concave mirror 24 has a reflecting surface 25 formed by, for example, depositing aluminum on the surface of a base material made of synthetic resin or glass. The reflecting surface 25 of the concave mirror 24 is formed in a smooth concave shape by being curved in a concave shape. Display light that has entered the concave mirror 24 from the plane mirror 22 is reflected by the reflecting surface 23 toward the projection unit 3 a. Here, the virtual image VRI can be magnified with respect to the image on the display screen 33 by reflection on the reflecting surface 25 of the concave mirror 24 having positive optical power.

The display light thus reflected by the concave mirror 24 is emitted to the outside of the HUD device 10 by passing through the dustproof sheet 13, and enters the projection portion 3a of the windshield 3. When the display light reflected by the projection unit 3a reaches the occupant's eye point EP, the occupant can visually recognize the virtual image VRI. Here, since the projection unit 3a is provided on the windshield 3 as a transmissive member, the virtual image VRI is displayed so as to be superimposed on the scenery outside the vehicle viewed through the windshield 3.

Moreover, the concave mirror 24 is rotatable around a rotary shaft 24a extending in the left-right direction in response to the driving of the stepping motor. By such rotation, the display position of the virtual image VRI can be adjusted so as to be displaced in the vertical direction.

The display device 30 of this embodiment will be described in detail below. As shown in FIGS. 2 and 3, the image display element 31 of the display unit 30 is a TFT liquid crystal panel using a thin film transistor (TFT), and includes, for example, a plurality of liquid crystal pixels arranged in a two-dimensional array. It is an active matrix type liquid crystal panel forming a.

The image display element 31 has a rectangular shape having a longitudinal direction LD and a lateral direction SD, that is, a rectangular shape. Since the liquid crystal pixels are arranged in the longitudinal direction LD and the lateral direction SD, the display screen 33 that faces the light guide portion 21 and emits the display light of the image also has the longitudinal direction LD with respect to the dimension in the lateral direction SD. It has a rectangular shape with a large size.

The longitudinal direction LD of the display screen 33 corresponds to the horizontal direction of the visually recognized virtual image VRI, and the lateral direction SD of the display screen 33 corresponds to the vertical direction of the visually recognized virtual image VRI. In this way, the virtual image VRI can be displayed in a horizontally long shape in the left-right direction.

The surface opposite to the display screen 33 across the body of the image display element 31 is an illumination target surface 32 illuminated by the light source light of the backlight unit 41. The illumination target surface 32 also has a shape matching the shape of the display screen 33, specifically, a rectangular shape in which the dimension in the longitudinal direction LD is set larger than the dimension in the lateral direction SD.

The image display element 31 has a flat plate shape by being formed by laminating a pair of polarizing plates and a liquid crystal layer sandwiched between the pair of polarizing plates. Each polarizing plate has a transmission axis and an absorption axis orthogonal to each other, and has a property of transmitting light polarized in the transmission axis direction and absorbing light polarized in the absorption axis direction. The pair of polarizing plates are arranged with their transmission axes orthogonal to each other. By applying a voltage to each liquid crystal pixel, the liquid crystal layer can rotate the polarization direction of light incident on the liquid crystal layer according to the applied voltage. In this way, the image display element 31 can change the ratio of light transmitted through the polarizing plate on the light guide 21 side, that is, the transmittance for each liquid crystal pixel by rotating the polarization direction.

Therefore, the image display element 31 controls the transmittance of each liquid crystal pixel in response to the incidence of the light source light through the illumination target surface 32, so that the image is displayed on the display screen 33 by using the light source light. indicate. Adjacent liquid crystal pixels are provided with color filters of different colors (for example, red, green, and blue), and various colors can be reproduced by combining these.

Each liquid crystal pixel is formed so as to penetrate between the display screen 33 and the surface 32 to be illuminated, and to be formed so as to surround the transparent portion and a transparent portion that is optically opened in the normal direction of the

surfaces

32 and 33. And a wiring part. Therefore, each transmission part constitutes an optical small opening. Further, since the outer peripheries of the display screen 33 and the illumination target surface 32 are surrounded by the light shielding member, the portion sandwiched between the display screen 33 and the illumination target surface 32 functions as an optical large opening.

The backlight unit 41 irradiates the illumination target surface 32 with the light source light. Specifically, the backlight unit 41 includes a light source unit 42, a first lens member 46, a second lens member 50, a third lens member 56, a diffusion plate 61 and the like. The first lens member 46, the second lens member 50, the third lens member 56, and the diffusion plate 61 are arranged on the optical path between the light source unit 42 and the illumination target surface 32 of the image display element 31.

The light source unit 42 is formed by arranging a plurality of light source elements 43 on a light source circuit board 44. The light source element 43 of this embodiment employs a light emitting diode element as a point light source, for example. Each light source element 43 is electrically connected to a power source through a wiring pattern on the light source circuit board 44. More specifically, each light source element 43 is formed by sealing a chip-shaped blue light emitting diode with a yellow fluorescent material in which a yellow fluorescent agent is mixed with a transparent synthetic resin. The blue light emitted from the blue light emitting diode in accordance with the amount of current excites the yellow phosphor to emit yellow light, and as a result of the mixing of the blue light and the yellow light, the white light from each light source element 43 (more In detail, pseudo white light source light is emitted.

Here, each light source element 43 emits the light source light in a radiation angle distribution in which the emission intensity relatively decreases as it deviates from the intensity peak direction PD in which the emission intensity becomes maximum. The intensity peak directions PD of the light source elements 43 are substantially the same as each other, and are substantially perpendicular to the surface of the light source circuit board 44 (this is referred to as a light source arrangement surface 44a).

On the light source arrangement surface 44a, the plurality of light source elements 43 are arranged side by side so as to be displaced by at least a predetermined interval INT in at least the longitudinal corresponding direction of the lateral corresponding direction and the longitudinal corresponding direction.

Here, the lateral direction corresponds to the lateral direction on the display screen 33 or the illumination target surface 32 when the display screen 33 or the illumination target surface 32 is projected onto the projection target along the direction opposite to the intensity peak direction PD. The vector indicating the direction SD means the direction indicated by the vector projected onto the projection target. Similarly, the longitudinal corresponding direction means that when the display screen 33 or the illumination target surface 32 is projected onto the projection target along the direction opposite to the intensity peak direction PD, the longitudinal direction LD on the display screen 33 or the illumination target surface 32. Means the direction indicated by the vector projected onto the projection target. Here, the light source arrangement surface 44a is the projection target. Hereinafter, the lateral corresponding direction is referred to as Y direction YD and the longitudinal corresponding direction is referred to as X direction XD.

If the light source arrangement surface 44a and the display screen 33 and the illumination target surface 32 are arranged in parallel, the lateral direction SD and the Y direction YD coincide with each other, and the longitudinal direction LD and the direction are coincident with each other, as shown in FIGS. It coincides with the X direction XD. If the display screen 33 and the illumination target surface 32 are arranged to be inclined with respect to the light source arrangement surface 44a, the lateral direction SD and the Y direction YD may deviate in correspondence with the inclination, and the longitudinal direction LD and The X direction XD may deviate.

In particular, in this embodiment, the plurality of light source elements 43 are arranged in one line along the X direction XD. The intervals INT between the light source elements 43 are set to be substantially equal to each other. The light source light emitted from each light source element 43 enters the first lens member 46.

The first lens member 46 shown in FIGS. 2 and 3 is made of, for example, synthetic resin or glass so as to be translucent, and has

optical surfaces

46a and 46b capable of refracting light from the light source. The first lens member 46 includes parallelizing lens elements 48 arranged so as to individually correspond to the light source elements 43 in a one-to-one correspondence and arranged in line with the arrangement of the light source elements 43 on the light source arrangement surface 44 a. It has a part 47. Each collimating lens element 48 is arranged so as to face the corresponding light source element 43, and collects and collimates the light source light emitted from each light source element 43. The collimation here means that the light source light is closer to the parallel light flux than the state immediately after being emitted from the light source element 43, and is not limited to the perfect light flux.

Further, in this embodiment, the light source elements 43 individually corresponding to the collimating lens elements 48 are slightly decentered with respect to the optical axis of each collimating lens element 48 toward the center side of the light source unit 42 in the X direction XD. The arrangement is made to be adopted. In other words, the distance between the collimating lens elements 48 in the X direction XD is set to be slightly larger than the distance INT between the light source elements 43.

The first lens member 46 of this embodiment has a planar optical surface 46a formed on the light source 42 side. Further, the first lens member 46 has an optical surface 46b having a plurality of smooth convex surfaces arranged as a parallelizing portion 47 on the side opposite to the light source portion 42, that is, on the illumination target surface 32 side. The sign of the focal length of the collimating lens element 48 is positive, and its value is set to be close to the distance between the collimating lens element 48 and the light source element 43. The light source light collimated by the first lens member 46 in this manner enters the second lens member 50.

The second lens member 50 shown in FIGS. 2 to 4 is formed of a translucent material, for example, synthetic resin or glass, and has

optical surfaces

50a and 50b capable of refracting the light from the light source. The second lens member 50 has the small light source array lens section 51 on the optical surface 50a on the first lens member 46 side (in other words, the light source section 42 side), and also has the third lens member 56 side (in other words, the illumination target surface 32). The short side light condensing portion 53 is provided on the optical surface 50b (on the side).

The small light source array lens unit 51 is formed by arranging a plurality of small light source lens elements 52. The small light source lens elements 52 are arranged at a minute pitch PIT (for example, 3 mm or less) that is sufficiently smaller than the interval INT in which the light source elements 43 are arranged, and the small light source lens elements 52 are spread with no space therebetween. In particular, the small light source lens elements 52 of the present embodiment are arranged in a rectangular lattice shape in two directions of Y direction YD and X direction XD.

The small light source lens elements 52 have common focal lengths fax and fay. The absolute values of the focal lengths fax and fay of each small light source lens element 52 are set sufficiently smaller than the absolute values of the other focal lengths fbx, fby, fcx, fcy, fdx and fdy.

With such a configuration, each small light source lens element 52 behaves so as to divide the light source light that is collimated from the light source unit 42 through the collimation unit 47 to form a new point-shaped small light source. That is, as shown in FIG. 5, by converging or diverging the light source light incident on each small light source lens element 52, image points IPx and IPy of the small light source are formed in the vicinity of each small light source lens element 52. .. Since the image points IPx and IPy of the small light source, which can be said to be virtual, are arranged at the small pitch PIT, the small light source array lens unit 51 functions as a whole to create a virtual planar light source.

In particular, in this embodiment, each small light source lens element 52 is formed in a toroidal surface shape that is convex toward the first lens member 46 side (in other words, the light source section 42 side). With such a surface shape, in each small light source lens element 52, the absolute value of the focal length fay in the Y direction YD is set to be smaller than the absolute value of the focal length fax in the X direction XD. Therefore, in each small light source, the position of the image point IPy in the Y direction YD (more specifically, the position that minimizes the dimension of the circle of confusion in the Y direction YD) is the position of the image point IPx in the X direction XD (more specifically, , The position at which the dimension of the circle of confusion in the X direction XD is minimized), and is shifted back and forth in the traveling direction of the light source light. Then, in the divided light source light emitted from each small light source, the divergence angle β in the Y direction YD becomes larger than the divergence angle α in the X direction XD. In other words, in each small light source lens element 52, the F value in the Y direction YD is smaller than the F value in the X direction XD.

The positions of the image points IPx and IPy are positions determined by the function of the small light source array lens unit 51 alone without considering the influence of the optical elements arranged on the illumination target surface 32 side of the small light source array lens unit 51. .. That is, the positions of the image points IPx and IPy viewed from the image display element 31 side through the third lens member 56 and the like are affected by the magnification of the optical element described above.

Note that in FIGS. 2 to 4, reference numerals are given only to a part of the small light source lens element 52. The small light source lens element 52 of FIGS. 2 to 4 is schematically illustrated, and has a smaller size in reality.

The short-side light condensing unit 53 is configured as an optical surface 50b arranged closer to the illumination target surface 32 than the positions of the image points IPx and IPy in the respective directions XD and YD of the small light source. The short-side light condensing unit 53 is formed in a single plane shape that is capable of collectively refracting the divided light source light from each small light source. The short-side light collecting unit 53 is configured to collect each divided light source light in at least the Y direction YD among the Y direction YD and the X direction XD.

Specifically, in this embodiment, the short-side light collecting portion 53 is formed in a convex cylindrical surface shape that is convex on the third lens member 56 side (in other words, the illumination target surface 32 side) and curved in the Y direction YD. .. The sign of the focal length fby in the Y direction YD of the short-side light collecting unit 53 is positive.

Thus, the second lens member 50 divides the light source into small light sources, and the condensed light source light is incident on the third lens member 56.

The third lens member 56 shown in FIGS. 2 to 4 is made of, for example, synthetic resin or glass so as to be translucent, and has

optical surfaces

56a and 56b capable of refracting the light from the light source. The third lens member 56 has the longitudinal directivity adjusting section 58 on the optical surface 56a on the second lens member 50 side (in other words, the light source section 42 side), and also has the diffusion plate 61 side (in other words, the illumination target surface 32 side). The short side directivity adjusting section 59 is provided on the optical surface 56b). In the present embodiment, the longitudinal directivity adjusting unit 58 and the lateral directivity adjusting unit 59 are collectively referred to as a directivity adjusting unit 57.

The longitudinal directivity adjustment unit 58 adjusts the directivity in the X direction XD of the light source light that has passed through the small light source array lens unit 51. Specifically, the longitudinal directivity adjusting section 58 is formed in a concave cylindrical surface shape that is recessed from the second lens member 50 side (in other words, the light source section 42 side) to the opposite side and curved in the X direction XD. .. In particular, the optical surface 56a formed by the longitudinal directivity adjusting unit 58 of the present embodiment is a Fresnel lens-shaped division in the X direction XD, thereby forming a collection of strip-shaped division optical surfaces extending in the Y direction YD. There is. The sign of the focal length fcx of the longitudinal directivity adjusting unit 58 in the X direction XD is negative. In this way, the longitudinal directivity adjustment unit 58 adjusts the directivity in the X direction XD by diverging the light source light in the X direction XD. By adjusting the divergence in the longitudinal directivity adjusting unit 58, the visible region EB can be expanded in the left-right direction in which the eyes of the occupant are lined up.

The short-sided directivity adjustment unit 59 adjusts the directivity in the Y direction YD of the light source light that has passed through the small light source array lens unit 51. Specifically, the short-side directivity adjusting unit 59 is formed in a convex cylindrical surface shape that is convex on the diffusion plate 61 side (in other words, the illumination target surface 32 side) and curved in the Y direction YD. The sign of the focal length fdy in the Y direction YD of the lateral directivity adjusting unit 59 is positive. In this way, the short-side directivity adjustment unit 59 adjusts the directivity in the Y direction YD by condensing the light source light in the Y direction YD. By the light-convergence adjustment by the short-side directivity adjusting unit 59, it is possible to increase the brightness of the virtual image VRI by making the visible region EB compact without excessively enlarging the visible region EB in the vertical direction in which the eyes of the occupant are not aligned.

The light source light whose directivity is adjusted by the third lens member 56 in this way is incident on the diffusion plate 61. The diffusing plate 61 shown in FIGS. 2 and 3 is arranged so as to be in a state of being close to or in a state of being bonded to the illumination target surface 32, and for example, diffusing particles such as microbeads are mixed with a base material made of a transparent synthetic resin. Is formed into a sheet or plate. The diffusion plate 61 diffuses the light source light incident from the third lens member 56 side to illuminate the illumination target surface 32.

As shown in FIGS. 2 and 6, when viewed in a vertical section along the short-side direction SD or the Y-direction YD of the display device 30, the divided light source lights from the respective small light sources reach by the illumination target surface 32. , Is extended to the dimension of the illumination target surface 32 in the lateral direction SD. Split light source lights from the respective small light sources are superposed between both ends of the illumination target surface 32 in the lateral direction SD. That is, in the Y direction YD, the respective divided light source lights are integrated, and overall illumination is performed.

On the other hand, as shown in FIGS. 3 and 6, when viewed in a vertical section along the longitudinal direction LD or the X direction XD of the display device 30, the divided light source light from each small light source reaches the illumination target surface 32. In addition, the dimension of the illumination target surface 32 in the longitudinal direction LD is not expanded. The expansion width when the divided light source light arrives is, for example, more than or equal to the interval INT between the respective light source elements 43 and is suppressed to a range not more than twice the interval INT. Each of the divided light source lights illuminates an illumination range on the illumination target surface 32 that is displaced from each other in the X direction XD. That is, in the X direction XD, the integration of each split light source light is regulated, and partial illumination is performed.

In a mode in which the integration in the X direction XD is regulated rather than the integration in the Y direction YD, that is, in the mode in which only the Y direction YD is the integrator optical system, as shown schematically in FIG. It is illuminated as if the light from the light source was greatly stretched in the lateral direction SD. Therefore, the overlapping portion of the respective divided light source lights also seems to be stretched in the lateral direction SD. Therefore, not only the gradient of the illumination intensity in the lateral direction SD is suppressed, but also in the longitudinal direction LD, the illumination intensity is made uniform as schematically shown in FIG.

Here, the setting and relationship of the focal lengths of the short-side light condensing unit 53 and the short-side directivity adjusting unit 59 will be described with reference to FIG. First, the absolute value of the focal length fby in the Y direction YD in the short-side light converging unit 53 and the absolute value of the focal length fdy in the Y-direction YD in the short-side directivity adjusting unit 59 are the Y-direction YD in each small light source lens element 52. Is set to be sufficiently larger than the absolute value of the focal length “fay”. The focal length fby in the Y direction YD of the short-side light converging unit 53 and the focal length fdy in the Y-direction YD of the short-side directivity adjusting unit 59 are the same as those of the short-side light converging unit 53 and the short-side directivity adjusting unit 59. It is set larger than the distance D between them. Further, the focal length fdy in the Y direction YD in the short-side directivity adjusting unit 59 is set to be larger than the focal length fby in the Y direction YD in the short-side light converging unit 53.

By doing so, the divided light source lights from the respective small light sources form an overlapping state in the Y direction YD at a position closer to the illumination target surface 32 than the short-side directivity adjusting unit 59. Furthermore, the illumination can be performed with the directivity adapted to the configuration in which the concave mirror 24 of the light guide section 21 condenses the display light.

The following are specific examples of focal length and lens arrangement. In the example of FIG. 4, the focal length fax of each small light source lens element 52 in the X direction XD is 2.03 mm. The focal length face in the Y direction YD of each small light source lens element 52 is 1.22 mm. The focal length fbx of the lateral light collecting portion 53 in the X direction XD is substantially infinite. The focal length fby in the Y direction YD of the short light focusing portion 53 is 37.74 mm. The focal length fcx of the longitudinal directivity adjusting unit 58 in the X direction XD is −152 mm. The focal length fcy of the longitudinal directivity adjusting unit 58 in the Y direction YD is substantially infinite. The focal length fdx in the X direction XD of the lateral directivity adjusting unit 59 is substantially infinite. The focal length fdy in the Y direction YD of the short-side directivity adjusting unit 59 is 42.05 mm. The distance between the second lens member 50 and the third lens member 56 that can be approximated to the distance D is 23 mm.

(Action effect)
The operation and effect of the first embodiment described above will be described again below.

According to the first embodiment, the small light source array lens unit 51 is formed by arranging a plurality of small light source lens elements 52. The small light source lens elements 52 are arranged at a pitch PIT smaller than the interval INT of the light source elements 43, and behave so as to divide the light source light from the light source unit 42 to form a small light source. That is, by arranging the small light sources in the Y direction YD with a small pitch PIT, the small light source array lens unit 51 functions like a linear light source or a planar light source, and they are arranged in the X direction XD with a shift. The plurality of light source elements 43 behave like a light source having a width in the X direction XD.

On the other hand, in each small light source lens element 52, the absolute value of the focal length fax in the Y direction YD is made smaller than the absolute value of the focal length fax in the X direction XD. Due to the relationship between the focal lengths fax and face, the spread angle β of the divided light source light in the Y direction YD emitted from each small light source of the small light source lens element 52 becomes a relatively wide angle, so that the light source light is preferably used with a short optical path length. It becomes possible to expand, and it is possible to realize illumination that matches the dimension of the illumination target surface 32 in the lateral direction SD. In the X direction XD with respect to the Y direction YD, the divergence angle α of the divided light source light in the X direction XD emitted from each small light source by the small light source lens element 52 becomes a relatively small angle, but the small light source array lens unit 51 has already been formed. Behaves like a light source with a width in the X direction XD. Therefore, it is possible to realize the illumination matched to the dimension of the illumination target surface 32 in the longitudinal direction LD without expanding the divided light source light from each small light source to the dimension of the illumination target surface 32 in the longitudinal direction LD. Therefore, it is possible to reduce the need to set a long optical path length according to the X-direction XD that should illuminate a wider range.

As described above, it is possible to provide the HUD device 10 that suppresses the increase in physique while reducing the occurrence of brightness unevenness in the virtual image VRI to improve the visibility of the virtual image VRI.

Further, according to the first embodiment, the small light source lens elements 52 are arranged in the Y direction YD and the X direction XD, and are formed in a toroidal surface shape. By arranging the toroidal surface-shaped small light source lens elements 52 in two directions, it is possible to form a large number of small light sources in a two-dimensional manner, and the small light source array lens unit 51 is used as a planar light source with less uneven brightness. Can be made to work.

Further, according to the first embodiment, the split light source light incident on the illumination target surface 32 is integrated in the Y direction YD, and is regulated in the X direction XD more than in the Y direction YD. Since it is not necessary to expand the split light source light in the X direction XD to the dimension of the illumination target surface 32 in the longitudinal direction LD, it is possible to set the optical path length according to the integration in the Y direction YD. Therefore, the optical path length of the backlight unit 41 can be shortened, and the increase in the size of the device 10 can be suppressed.

Further, according to the first embodiment, the short-side light condensing unit 53 is arranged on the optical path on the illumination target surface 32 side of each small light source lens element 52, and collectively collects the divided light source lights in the Y direction YD. Is configured to. Due to the light condensing by the short-side light condensing unit 53, the divided light source light from each small light source lens element 52 is directed toward the illumination target surface 32, and proper superposition on the illumination target surface 32 is realized.

Further, according to the first embodiment, the small light source array lens portion 51 constitutes the optical surface 50a arranged on the light source portion 42 side, and the short light condensing portion 53 is arranged on the illumination target surface 32 side. By configuring 50b, the small light source array lens portion 51 and the short light focusing portion 53 are integrally formed as the second lens member 50. By doing so, it is possible to improve the alignment accuracy between the small light source array lens unit 51 and the short-side light converging unit 53, and thus the illumination accuracy, and also improve the transmittance. At the same time, since the number of parts can be suppressed, expansion of the physique of the device 10 can be suppressed.

Further, according to the first embodiment, the directivity adjusting unit 57 is disposed on the optical path between the short-side light collecting unit 53 and the illumination target surface 32, and the light source light incident through the small light source array lens unit 51 is incident on the directivity adjusting unit 57. Adjust the directivity. Directivity for forming the visible region EB is adjusted at a position close to the illumination target surface 32 by the short-side light collecting unit 53, that is, at a position where the overlapping state of the divided light source lights is being created. The visible region EB can be set to an appropriate range while the backlight unit 41 exerts the effect of suppressing the uneven illumination on the illumination target surface 32. As a result, the visibility of the virtual image VRI is enhanced.

Further, according to the first embodiment, the directivity adjusting unit 57 condenses the light source light in the Y direction YD and diverges the light source light in the X direction XD. Since the visual recognition area EB is enlarged in the direction in which the diverging action is applied, the longitudinal direction of the visual recognition area EB and the longitudinal direction LD of the image can be matched. Therefore, when the alignment direction of both eyes is aligned with the longitudinal direction of the visual recognition area EB, it is possible to realize a virtual image VRI that is easily viewed by both eyes and that is horizontally long. As a result, the visibility of the virtual image VRI is enhanced.

Further, according to the first embodiment, the focal length fby in the Y direction YD of the short-side light collecting unit 53 is smaller than the focal length fdy in the Y-direction YD of the directivity adjusting unit 57, and the short-side light collecting unit 53. Is larger than the distance D between the directivity adjusting unit 57 and the directivity adjusting unit 57. By satisfying these conditions, the overlapping state of the divided light source light is realized on the illumination target surface 32 side of the directivity adjusting unit 57.

(Second embodiment)
As shown in FIG. 9, the second embodiment is a modification of the first embodiment. The second embodiment will be described focusing on the points different from the first embodiment.

Also in the second lens member 250 of the second embodiment, the small light source array lens section 251 is formed by arranging a plurality of small light source lens elements 252 as in the first embodiment. The small light source lens elements 252 are arranged at a pitch PIT (for example, 3 mm or less) that is sufficiently smaller than the interval INT in which the light source elements 43 are arranged, and they are spread without any gap therebetween. However, the small light source lens elements 252 of the second embodiment are arranged in one direction of the Y direction YD. As described above, the small light source lens elements 252 may be arranged in the Y direction YD in which the divided light source light is integrated, of the Y direction YD and the X direction XD.

Each small light source lens element 252 has a strip shape extending in the X direction XD, and is formed in a convex cylindrical surface shape that is convex toward the first lens member 46 side (in other words, the light source section 42 side). In such a small light source lens element 252 having a cylindrical surface, the focal length fax in the X direction XD is substantially infinite. Therefore, as in the first embodiment, in each small light source lens element 252, the relationship that the absolute value of the focal length fay in the Y direction YD is smaller than the absolute value of the focal length fax in the X direction XD is established. In such a second embodiment, the small light source formed by each small light source lens element 252 is like a linear light source.

According to the second embodiment described above, the small light source lens elements 252 are arranged in the Y direction YD and formed in a cylindrical surface shape. By arranging the cylindrical light source lens elements 252 in the Y direction YD, the difference between the absolute value of the focal length fay in the Y direction YD and the absolute value of the focal length fax in the X direction XD can be increased. Therefore, it is possible to reduce the difference between the optimum optical path length for the Y direction YD and the optimum optical path length for the X direction XD. Therefore, since it becomes easy to set the optical path length of the backlight unit 41 to an appropriate optical path length in both directions XD and YD, it is possible to provide the HUD device 10 in which the physical size is suppressed while enhancing the visibility of the virtual image VRI. be able to.

(Other embodiments)
Although a plurality of embodiments have been described above, the present disclosure should not be construed as being limited to those embodiments, and may be applied to various embodiments and combinations without departing from the scope of the present disclosure. You can

Specifically, as a modified example 1, as shown in FIGS. 10 and 11, the small light source array lens unit 51 and the short-side light collecting unit 53 may be separately formed.

As a second modification, at least one of the sign of the focal length fax in the X direction XD and the sign of the focal length fay in the Y direction YD of each small light source lens element 52 may be negative.

As a third modification, the light source unit 42 may include the light source elements 43 arranged at least in the X direction XD by a predetermined distance and arranged side by side. The plurality of light source elements 43 may not be arranged in a straight line along the X direction XD. As a specific example, the plurality of light source elements 43 are arranged in a curved shape by being offset by a predetermined distance in the X direction XD and being offset in the Y direction YD by a different value for each light source element 43. Good. Further, the plurality of light source elements 43 may be arranged in a zigzag manner by being offset in the X direction XD by a predetermined interval and being offset in the Y direction YD alternately in the opposite direction.

As a fourth modification, the light source unit 42 may include the light source elements 43 arranged at least in the X direction XD by a predetermined interval INT and arranged side by side. If the plurality of light source elements 43 are arranged two-dimensionally, a combination of the light source elements 43 that are displaced from each other in the X direction XD occurs. As a specific example, the plurality of light source elements 43 may be arranged in a rectangular lattice shape in two directions of the Y direction YD and the X direction XD. Further, the plurality of light source elements 43 may be arranged in a triangular lattice shape, a hexagonal lattice shape, or the like.

As a fifth modification, the predetermined interval INT at which the light source element 43 is displaced may be modulated. In this case, the pitch PIT at which the small light source lens elements 52 are arranged may be smaller than the average interval which is the average value of the intervals INT. However, it is more preferable that the pitch PIT is smaller than the minimum value of the intervals INT, which is the minimum value.

As a sixth modification, the light source element 43 is not limited to the point light source, and may be a linear light source or a planar light source. The light source unit 42 may have a configuration in which a plurality of light source elements 43 as linear light sources extending in the Y direction YD are arranged in the X direction XD. Further, the light source unit 42 may have a configuration in which a plurality of light source elements 43 serving as a planar light source are arranged so as to be separated from each other in the X direction XD.

As a modified example 7, the light guide section 21 may have a convex mirror instead of the plane mirror 22 or by adding a new optical element. Even when the light guide section 21 includes a convex mirror, the sign of the combined focal length of the light guide section 21 is preferably positive. In this configuration, the focal length fby of the short-side light converging unit 53 in the Y direction YD may be set to a value substantially equal to the focal length fdy of the short-direction directivity adjusting unit 59 in the Y direction YD.

As a modified example 8, the diffusion plate 61 may be arranged between the second lens member 50 and the third lens member 56.

As a modified example 9, the longitudinal directivity adjusting portion 58 may be formed in a single concave cylindrical surface shape instead of the Fresnel lens shape. On the contrary, the lateral directivity adjusting section 59 may be formed in a Fresnel lens shape. In addition, as shown in FIGS. 10 and 11, at least a part of the longitudinal directivity adjusting unit 58 and the lateral directivity adjusting unit 59 may be configured in a combined state by one optical surface such as a toroidal surface. Good. Furthermore, at least one of the longitudinal directivity adjusting unit 58 and the lateral directivity adjusting unit 59 may not be provided.

As a tenth modification, the illumination target surface 32 as the illumination target portion that functions as the illumination target of the backlight unit 41 is not limited to a rectangular shape, and may be formed in an elliptical shape, a parallelogram shape, or the like. Further, the illumination target portion may not be formed in a single plane shape and may include a three-dimensional structure.

As a modified example 11, the virtual image display device can be applied to various vehicles such as an aircraft, a ship, and a case that does not move such as a game case. Further, the virtual image display device can be applied to a mobile information terminal such as a head mounted display.

Claims

A virtual image display device for displaying a virtual image (VRI) by projecting display light of an image onto a projection unit (3a),
There is an illumination target part (32) whose dimension in the longitudinal direction (LD) is set larger than the dimension in the lateral direction (SD), and the image is displayed using the light source light illuminated by the illumination target part. An image display element (31) for displaying,
A backlight unit (41) for irradiating the illumination target portion with the light source light,
The backlight unit is
A plurality of a plurality of elements arranged side by side by at least a predetermined interval (INT) in at least the longitudinal corresponding direction among the lateral corresponding direction (YD) corresponding to the lateral direction and the longitudinal corresponding direction (XD) corresponding to the longitudinal direction. A light source section (42) for emitting the light source light from each of the light source elements,
It is arranged on an optical path between the light source unit and the illumination target unit, and at a pitch (PIT) smaller than the interval along at least the short side corresponding direction of the short side corresponding direction and the long side corresponding direction. A small light source array lens section that has a plurality of small light source lens elements (52) arranged, and each small light source lens element behaves so as to divide the light source light from the light source section to form a new small light source. (51) and,
In each of the small light source lens elements, the virtual image display device in which the absolute value of the focal length in the lateral corresponding direction is smaller than the absolute value of the focal length in the longitudinal corresponding direction.
The virtual image display device according to claim 1, wherein each of the small light source lens elements is arranged in the direction corresponding to the lateral direction and formed into a cylindrical surface shape.
The virtual image display device according to claim 1, wherein each of the small light source lens elements is arranged in the direction corresponding to the lateral direction and the direction corresponding to the longitudinal direction and is formed in a toroidal surface shape.
The backlight unit integrates each of the light source lights divided by each of the small light source lens elements into the illumination target portion in the short-side corresponding direction and causes the light source light to enter in the long-side corresponding direction. 4. The virtual image display device according to claim 1, wherein the virtual image display device is made incident in a state in which the integration is regulated more than in the lateral direction.
In the backlight unit, the light source light divided by the small light source lens elements is collectively collected in the short-side corresponding direction on the optical path closer to the illumination target portion than the small light source lens elements. The virtual image display device according to any one of claims 1 to 4, further comprising a short-side light collecting portion (53) configured to emit light.
An optical system in which the small light source array lens unit constitutes an optical surface (50a) arranged on the light source unit side on the optical path, and the short light condensing unit is arranged on the illumination target unit side on the optical path. The virtual image display device according to claim 5, wherein the small light source array lens unit and the short light condensing unit are integrally formed as a lens member (50) by forming a surface (50b).
The backlight unit is disposed on the optical path between the short light converging unit and the illumination target unit, and is a directivity adjustment that adjusts the directivity of the light source light that has entered through the small light source array lens unit. The virtual image display device according to claim 5, further comprising a unit (57).
The virtual image display device according to claim 7, wherein the directivity adjusting unit collects the light source light in the direction corresponding to the lateral direction and diverges the light source light in the direction corresponding to the longitudinal direction.
A focal length of the short-side light converging portion in the short-side corresponding direction is smaller than a focal length of the directivity adjusting portion in the short-side corresponding direction, and the short-side light converging portion and the directivity adjusting portion. The virtual image display device according to claim 7, wherein the virtual image display device is larger than the distance between them.