JP6984619B2 - Virtual image display device - Google Patents

Description

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

Conventionally, a virtual image display device for displaying a virtual image by projecting the display light of an image onto a projection unit is known. The virtual image display device disclosed in Patent Document 1 includes an image display element for displaying an image and a backlight unit for irradiating the image display element with light from a light source. The display area of the image display element is formed in a rectangular shape.

The backlight unit includes a light source, a lens array, a first focus lens, a second focus lens, and the like. The light source is composed of two LEDs. The lens array is a lens body in which a plurality of biconvex lenses are arranged vertically and horizontally. The arrangement pitch of this biconvex lens is sufficiently large.

Further, 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

When the image display element is provided with an illumination target portion such as a rectangular shape in which the dimension in the longitudinal direction is set larger than the dimension in the lateral direction, uneven illumination and eventually uneven brightness are reduced. In order to improve the visibility of the virtual image, it is required to configure the backlight unit corresponding to the difference in dimensions, that is, the aspect ratio.

In this regard, in Patent Document 1, by providing a toroidal surface on the focus lens, the illumination light is greatly expanded in the longitudinal corresponding direction corresponding to the longitudinal direction, and the irradiation range of the light source light is brought closer to the shape of the illumination target portion. However, in this form, the optical path length of the focus lens portion tends to be long, and in particular, the optical path length is set according to the longitudinal corresponding direction so that the light source light spreads favorably in the longitudinal corresponding direction. The physique of the device will increase.

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 a virtual image.

One of the embodiments disclosed here is a virtual image display device that displays a virtual image (VRI) by projecting the display light of an image onto a projection unit (3a).
It has an illuminated object portion (32) whose longitudinal direction (LD) dimension is set larger than the lateral direction (SD) dimension, and displays an image by using the light source light illuminated by the illuminated object portion. Image display element (31) and
It is equipped with a backlight unit (41) that irradiates the illuminated object with light from a light source.
The backlight unit is
A plurality of light source elements arranged side by side with a predetermined interval (INT) at least in the longitudinal direction (YD) corresponding to the lateral direction and the longitudinal direction (XD) corresponding to the longitudinal direction. A light source unit (42) having (43) and emitting light source light from each light source element,
A plurality of small pieces arranged on the optical path between the light source unit and the illuminated object portion and arranged 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. It has a light source lens element (52), and each small light source lens element has a small light source array lens unit (51) that behaves so as to divide the light source light from the light source unit to form a new small light source.
In each of the small light-source lens element, the absolute value of the focal length of the short side corresponding direction is rather smaller than the absolute value of the focal length of the longitudinal direction corresponding,
The backlight unit is
On the optical path, a short light condensing unit configured to collectively condense each light source light divided by each small light source lens element on the illumination target portion side of each small light source lens element in the direction corresponding to the short side. (53) and
It further has a directivity adjusting unit (57) that is arranged on the optical path between the short condensing unit and the illumination target unit and adjusts the directivity of the light source light incident through the small light source array lens unit.
The directivity adjusting unit collects the light source light in the direction corresponding to the short side and radiates the light source light in the direction corresponding to the long side .
Also, one of the embodiments disclosed here is
A virtual image display device that displays a virtual image (VRI) by projecting the display light of an image onto a projection unit (3a).
It has an illuminated object portion (32) whose longitudinal direction (LD) dimension is set larger than the lateral direction (SD) dimension, and displays an image by using the light source light illuminated by the illuminated object portion. Image display element (31) and
It is equipped with a backlight unit (41) that irradiates the illuminated object with light from a light source.
The backlight unit is
A plurality of light source elements arranged side by side with a predetermined interval (INT) at least in the longitudinal direction (YD) corresponding to the lateral direction and the longitudinal direction (XD) corresponding to the longitudinal direction. A light source unit (42) having (43) and emitting light source light from each light source element,
A plurality of small pieces arranged on the optical path between the light source unit and the illuminated object portion and arranged 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. It has a light source lens element (52), and each small light source lens element has a small light source array lens unit (51) that 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 direction corresponding to the short side is smaller than the absolute value of the focal length in the direction corresponding to the long side.
The backlight unit is
On the optical path, a short light condensing unit configured to collectively condense each light source light divided by each small light source lens element on the illumination target portion side of each small light source lens element in the direction corresponding to the short side. (53) and
It further has a directivity adjusting unit (57) that is arranged on the optical path between the short condensing unit and the illumination target unit and adjusts the directivity of the light source light incident through the small light source array lens unit.
The focal length of the short-hand condensing unit in the short-hand direction is smaller than the focal length of the directivity adjustment unit in the short-hand direction, and is smaller than the distance between the short-hand condensing unit and the directivity adjustment unit. big.

According to an aspect, such as these, a small light source array lens unit is formed by arranging a plurality of small light sources lens element. Such small light source lens elements are arranged at a pitch smaller than the distance between the light source elements, and behave as if the light source light from the light source unit is divided to form a small light source. That is, by arranging the small light sources at a small pitch in the short corresponding direction, the small light source array lens unit functions like a linear light source or a planar light source, and a plurality of small light sources arranged so as to be offset in the longitudinal corresponding direction. Due to the light source element of, it behaves like a light source having a width in the longitudinal corresponding direction.

On the other hand, in each small light source lens element, the absolute value of the focal length in the direction corresponding to the short side is smaller than the absolute value of the focal length in the direction corresponding to the long side. Due to this focal length relationship, the spread angle of the split light source light in the direction corresponding to the short side emitted from each small light source of the small light source lens element becomes relatively wide, so that the light source light can be suitably spread with a short light path length. Therefore, it is possible to realize lighting that matches the dimensions of the lighting target portion in the lateral direction. In the longitudinal direction with respect to the short direction, the spread angle of the split light source light in the longitudinal direction emitted from each small light source by the small light source lens element is relatively narrow, but the small light source array lens part is already longitudinal. It behaves like a light source with a width in the corresponding direction. Therefore, it is possible to realize illumination that matches the longitudinal dimension of the illuminated object portion without expanding the divided light source light from each small light source to the longitudinal dimension of the illuminated object portion. Therefore, it is possible to reduce the need to set a long optical path length corresponding to the longitudinal corresponding direction in which a wider range should be illuminated.

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

It should be noted that the reference numerals in parentheses exemplify the correspondence with the parts of the embodiments described later, and are not intended to limit the technical scope.

It is a figure which shows the mounting state of the HUD device of 1st Embodiment in a vehicle. It is a figure which shows the vertical cross section along the short side direction or the Y direction in the display | display of 1st Embodiment. It is a figure which shows the vertical cross section along the longitudinal direction or the X direction in the display | display of 1st Embodiment. It is a perspective view which shows the 2nd lens member and the 3rd lens member of 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, the upper part shows the vertical section along the X direction, and the lower part shows the vertical section along the Y direction. It is a schematic diagram for demonstrating the integrator of the divided light source light of 1st Embodiment. It is a schematic diagram for demonstrating the lighting characteristic of the backlight unit of 1st Embodiment. It is a graph for demonstrating the intensity of the illumination light along the VIII-VIII cross section of FIG. It is a perspective view which shows the 2nd lens member of 2nd Embodiment. It is a figure corresponding to FIG. 2 in the modification. It is a figure corresponding to FIG. 3 in the modification.

Hereinafter, a plurality of embodiments will be described with reference to the drawings. By assigning the same reference numerals to the corresponding components in each embodiment, duplicate description may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. Further, not only the combination of the configurations specified in the description of each embodiment but also the configurations of a plurality of embodiments can be partially combined even if the combination is not specified. ..

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

Examples of the various information to be displayed include information indicating the state of the vehicle 1 such as vehicle speed and remaining fuel amount, and navigation information such as visibility assist information and road information.

In the following, unless otherwise specified, each direction indicated by front, rear, up, down, left and right is described with reference to vehicle 1 on the horizontal plane HP.

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

The viewing area EB is a spatial area that can be visually recognized so that the virtual image VRI displayed by the HUD device 10 meets a predetermined standard (for example, the entire virtual image VRI has a predetermined brightness or higher), and is also referred to as an eye box. Is called. The visible area EB is typically set to overlap the irips set in the vehicle 1. The eye lip is set for each of the eyes, and is set as an ellipsoidal virtual space based on the eye range that statistically represents the spatial distribution of the occupant's eye point EP.

A specific configuration of such a HUD device 10 will be described below. The HUD device 10 includes a housing 11, a display 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 accommodating the display 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 facing the projection portion 3a. The window portion 12 is covered with, for example, a dustproof sheet 13 capable of transmitting 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 the present embodiment is a transmissive liquid crystal display. The display 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, for example, a box-shaped casing having a light-shielding property.

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

The plane mirror 22 forms a reflective surface 23, for example, by depositing aluminum on the surface of a base material made of synthetic resin or glass. The reflecting surface 23 of the plane mirror 22 is formed in a smooth planar shape. The display light incident on the plane mirror 22 from the display 30 is reflected toward the concave mirror 24 by the reflecting surface 23.

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

The display light reflected by the concave mirror 24 in this way is transmitted to the outside of the HUD device 10 by passing through the dustproof sheet 13, and is incident on 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 superimposed on the scenery outside the vehicle that is visually recognized through the windshield 3.

Further, the concave mirror 24 is rotatable around a rotation shaft 24a extending in the left-right direction according to the drive 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.

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

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

The longitudinal LD of the display screen 33 corresponds to the left-right direction of the visually recognized virtual image VRI, and the lateral 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 horizontally long in the left-right direction.

The surface of the image display element 31 on the opposite side of the main body of the image display element 31 from the display screen 33 is an illumination target surface 32 illuminated by the light source of the backlight unit 41. The illuminated surface 32 also has a shape that matches the shape of the display screen 33, and in detail, has a rectangular shape in which the dimension of the longitudinal LD is set larger than the dimension of the SD in the lateral direction.

The image display element 31 has a flat plate shape because it is 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 so that their transmission axes are orthogonal to each other. By applying a voltage for each liquid crystal pixel, the liquid crystal layer can rotate the polarization direction of the 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 unit 21 side, that is, the transmittance, for each liquid crystal pixel by rotating in the polarization direction.

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

Each liquid crystal pixel is formed by surrounding a transmissive portion provided by optically opening in the normal direction of the surfaces 32 and 33 so as to penetrate between the display screen 33 and the illuminated surface 32, and the transmissive portion. A wiring unit is provided. Therefore, each transmission portion constitutes an optical small opening. Further, since the outer periphery of the display screen 33 and the illumination target surface 32 is surrounded by the light-shielding member, the portion sandwiched between the display screen 33 and the illumination target surface 32 functions as a large optical opening.

The backlight unit 41 irradiates the light source to the illuminated surface 32. Specifically, the backlight unit 41 is composed of a light source unit 42, a first lens member 46, a second lens member 50, a third lens member 56, a diffuser plate 61, and the like. The first lens member 46, the second lens member 50, the third lens member 56, and the diffuser 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. For the light source element 43 of the present embodiment, for example, a light emitting diode element as a point light source is adopted. 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 phosphor in which a yellow fluorescent agent is mixed with a translucent synthetic resin. The blue light emitted from the blue light emitting diode according to the amount of current excites the yellow phosphor to emit yellow light, and the mixture of the blue light and the yellow light results in white (more) from each light source element 43. In detail, the light source (pseudo-white) is emitted.

Here, each light source element 43 emits light source light in a radiation angle distribution in which the light emission intensity is relatively reduced as the light emission intensity deviates from the intensity peak direction PD that maximizes the light emission intensity. The intensity peak directions PD of each light source element 43 are substantially the same direction as each other, and are in a direction 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 arranging surface 44a, the plurality of light source elements 43 are arranged so as to be arranged with a predetermined interval INT in the longitudinal corresponding direction at least in the lateral corresponding direction and the longitudinal corresponding direction.

Here, the short-handed direction is the short-handed direction on the display screen 33 or the illuminated target surface 32 when the display screen 33 or the illuminated object surface 32 is projected onto the projected object along the opposite direction of the intensity peak direction PD. Direction The vector indicating the SD means the direction indicated by the vector projected on the projective object. Similarly, the longitudinal direction means the longitudinal LD 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 opposite direction of the intensity peak direction PD. The vector indicating is the direction indicated by the vector projected on the projection target. Here, the light source arrangement surface 44a is a projective object. Hereinafter, the short side corresponding direction is referred to as Y direction YD, and the long side corresponding direction is referred to as X direction XD.

If the light source arrangement surface 44a, the display screen 33, and the illumination target surface 32 are arranged in parallel, the SD in the lateral direction and the YD in the Y direction coincide 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 tilted with respect to the light source arrangement surface 44a, the SD in the lateral direction and the YD in the Y direction may deviate from each other in accordance with the tilt, and the LD in the longitudinal direction and the LD in the longitudinal direction. It may be out of alignment with the X direction XD.

In particular, in the present embodiment, the plurality of light source elements 43 are arranged in a row along the X direction XD. The spacing INTs between the light source elements 43 are set substantially equal to each other. The light source light emitted from each light source element 43 is incident on the first lens member 46.

The first lens member 46 shown in FIGS. 2 and 3 is transparently formed of, for example, synthetic resin or glass, and has optical surfaces 46a and 46b capable of refracting the light source light. The first lens member 46 is a parallelization in which parallelizing lens elements 48 provided so as to correspond individually to each light source element 43 on a one-to-one basis are arranged according to the arrangement of the light source element 43 on the light source arrangement surface 44a. It has a part 47. Each parallelizing lens element 48 is arranged to face the corresponding light source element 43, and collects and parallelizes the light source light emitted from each light source element 43. The term "parallelization" as used herein is not limited to the case where the light source light is made closer to the parallel light flux than the state immediately after being emitted from the light source element 43, and the light source light is not limited to a completely parallel light source.

Further, in the present embodiment, the light source element 43 individually corresponding to the parallelizing lens element 48 is slightly eccentric to the center side of the light source portion 42 in the X direction XD with respect to the optical axis of each parallelizing lens element 48. The arrangement is adopted. In other words, in the X direction XD, the distance between the parallelizing lens elements 48 is set to be slightly larger than the distance INT between the light source elements 43.

The first lens member 46 of the present embodiment forms a planar optical surface 46a on the light source portion 42 side. Further, the first lens member 46 forms an optical surface 46b in which a plurality of smooth convex surfaces are arranged as a parallelization portion 47 on the side opposite to the light source portion 42, that is, on the illumination target surface 32 side. The sign at the focal length of the parallelizing lens element 48 is positive, and its value is set to be close to the distance between the parallelizing lens element 48 and the light source element 43. The light source light parallelized by the first lens member 46 is incident on the second lens member 50.

The second lens member 50 shown in FIGS. 2 to 4 is transparently formed of, for example, synthetic resin or glass, and has optical surfaces 50a and 50b capable of refracting the light source light. The second lens member 50 has a small light source array lens unit 51 on the optical surface 50a on the first lens member 46 side (in other words, the light source unit 42 side), and also has the third lens member 56 side (in other words, the illumination target surface 32). The optical surface 50b on the side) has a short light source 53.

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 with a minute pitch PIT (for example, 3 mm or less) sufficiently smaller than the interval INT in which the light source elements 43 are arranged, and are spread over each other without gaps. In particular, the small light source lens elements 52 of the present embodiment are arranged in a rectangular grid pattern in two directions, the Y direction YD and the X direction XD.

Each small light source lens element 52 has a focal length fax and a common focal length. The absolute values of the focal lengths fax and fail of each small light source lens element 52 are set to be sufficiently smaller than the absolute values of the other focal lengths fbx, fby, fcx, fcy, fdx and fdy.

In such a form, each small light source lens element 52 behaves so as to divide the light source light parallelized from the light source unit 42 through the parallelization unit 47 to form a new point-shaped small light source. That is, as shown in FIG. 5, the image points IPx and IPy of the small light source are configured in the vicinity of each small light source lens element 52 by converging or diverging the light source light incident on 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 with a 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 the present 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 portion 42 side). Due to such a surface shape, the absolute value of the focal length fair in the Y direction YD is set smaller than the absolute value of the focal length fax in the X direction XD in each small light source lens element 52. 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 Y direction YD of the circle of confusion) is the position of the image point IPx in the X direction XD (more specifically). , The position where the dimension of the X direction XD of the circle of confusion is minimized) and the position where the light source light travels back and forth. Then, in the divided light source light emitted from each small light source, the spread angle β in the Y direction YD becomes a large state with respect to the spread 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 determined as a function of the small light source array lens unit 51 alone without considering the influence of the optical element 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 as seen from the image display element 31 side through the third lens member 56 and the like are affected by the magnification of the above-mentioned optical element.

In FIGS. 2 to 4, only a part of the small light source lens element 52 is designated with a reference numeral. The small light source lens element 52 of FIGS. 2 to 4 is schematically shown, and in reality, it has a smaller size.

The short light collecting unit 53 is configured as an optical surface 50b arranged on the illumination target surface 32 side with respect to the positions of the image points IPx and IPy in each direction XD and YD of the small light source. The short light collecting unit 53 is formed in a single plane shape capable of refracting the divided light sources from each small light source. The short condensing unit 53 is configured to condense each divided light source light in at least the Y direction YD of the Y direction YD and the X direction XD.

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

In this way, the light source light divided into small light sources by the second lens member 50 and further condensed is incident on the third lens member 56.

The third lens member 56 shown in FIGS. 2 to 4 is transparently formed of, for example, synthetic resin or glass, and has optical surfaces 56a and 56b capable of refracting the light source light. The third lens member 56 has a longitudinal directionality adjusting portion 58 on the optical surface 56a on the second lens member 50 side (in other words, the light source portion 42 side), and also has a diffuser plate 61 side (in other words, the illumination target surface 32 side). ), The short-side directivity adjusting unit 59 is provided on the optical surface 56b. In the present embodiment, the longitudinal directivity adjusting unit 58 and the short directivity adjusting unit 59 are collectively referred to as a directivity adjusting unit 57.

The longitudinal directivity adjusting unit 58 adjusts the directivity of the X direction XD with respect to the light source light that has passed through the small light source array lens unit 51. Specifically, the longitudinal directional adjustment portion 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 portion 42 side) to the opposite side and curves in the X direction XD. .. In particular, the optical surface 56a by the longitudinal directional adjustment unit 58 of the present embodiment becomes an aggregate of strip-shaped divided optical surfaces extending in the Y direction YD by being divided in the X direction XD like a Fresnel lens. There is. The sign at the focal length fcx of the X-direction XD of the longitudinal directional adjustment unit 58 is negative. In this way, the longitudinal directivity adjusting unit 58 adjusts the directivity of the X direction XD by diverging the light source light in the X direction XD. By adjusting the divergence in the longitudinal directional adjustment unit 58, the visible area EB can be expanded in the left-right direction in which the eyes of the occupant are lined up.

The short-hand directivity adjusting unit 59 adjusts the directivity of the Y-direction YD with respect to the light source light that has passed through the small light source array lens unit 51. Specifically, the short-side directional adjustment unit 59 is formed in a convex cylindrical surface shape that is convex toward the diffuser plate 61 side (in other words, the illumination target surface 32 side) and curves in the Y direction YD. The sign at the focal length fdy of the Y-direction YD of the short-hand directional adjustment unit 59 is positive. In this way, the short-hand directivity adjusting unit 59 adjusts the directivity of the Y-direction YD by condensing the light source light in the Y-direction YD. By adjusting the light collection with the hand directional adjustment unit 59, it is possible to increase the brightness of the virtual image VRI by making it compact without excessively expanding the visual recognition area EB in the vertical direction in which the eyes of the occupant are not lined up.

The light source light whose directivity is adjusted by the third lens member 56 is incident on the diffuser plate 61. The diffuser plate 61 shown in FIGS. It is formed in the shape of a sheet or a plate. The diffuser 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 on the vertical cross section of the display 30 along the short side SD to the Y direction YD, the divided light source light from each small light source reaches the illumination target surface 32 , It is expanded to the dimension of SD in the lateral direction of the illumination target surface 32. The divided light source light from each small light source is superimposed between both ends of the illumination target surface 32 in the short direction SD. That is, in the Y direction YD, each divided light source is integrated to perform overall illumination.

On the other hand, as shown in FIGS. 3 and 6, when viewed on the vertical cross section of the display 30 along the longitudinal direction LD to the X direction XD, the divided light source light from each small light source reaches the illumination target surface 32. In addition, it is not extended to the dimension of the longitudinal LD of the illuminated surface 32. The expansion width at the time of arrival of the divided light source light is, for example, suppressed to a range of not more than the interval INT between the light source elements 43 and not more than twice the interval INT. Each of the divided light sources illuminates the illumination range of the illumination target surface 32 that is deviated from each other in the X direction and XD. That is, in the X direction XD, the integration of each divided light source light is regulated, and partial illumination is carried out.

In the embodiment in which the integration of the X-direction XD is regulated rather than the integration of the Y-direction YD, that is, in the embodiment in which only the Y-direction YD is an integrator optical system, as shown schematically in FIG. 7, the division from each small light source is performed. The light source is illuminated as if it were greatly stretched in the short direction SD. Therefore, the overlapping portion of the light of each divided light source is also stretched in the lateral SD direction. Therefore, not only the gradient of the illumination intensity in the lateral SD is suppressed, but also in the longitudinal direction LD, the illumination intensity can be made uniform as schematically shown in FIG.

Here, with reference to FIG. 4, the setting and relationship of the focal length between the short-hand condensing unit 53 and the short-hand directional adjustment unit 59 will be described. First, the absolute value of the focal length fby of the Y direction YD in the short light condensing unit 53 and the absolute value of the focal length fdy of the Y direction YD in the short direction adjustment unit 59 are determined by the Y direction YD in each small light source lens element 52. It is set sufficiently larger than the absolute value of the focal length of. Further, the focal length fby of the Y-direction YD in the short-hand condensing unit 53 and the focal length fdy of the Y-direction YD in the short-hand directional adjustment unit 59 are determined by the short-hand condensing unit 53 and the short-hand directional adjustment unit 59. It is set larger than the distance D between them. Further, the focal length fdy of the Y-direction YD in the short-hand directional adjustment unit 59 is set to be larger than the focal length fby of the Y-direction YD in the short-hand condensing unit 53.

By doing so, the divided light source light from each small light source constitutes a superposed state at a position closer to the illumination target surface 32 than the short directional adjustment unit 59 in the Y direction YD. Further, the illumination can be performed with the directivity suitable for the configuration in which the concave mirror 24 of the light guide unit 21 collects the display light.

Hereinafter, specific examples of the focal length and the lens arrangement will be shown. In the example of FIG. 4, the focal length fax in the X direction XD of each small light source lens element 52 is 2.03 mm. The focal length phase of each small light source lens element 52 in the Y direction YD is 1.22 mm. The focal length fbx in the X direction XD of the short light collecting unit 53 is substantially infinite. The focal length fby of the short light collecting unit 53 in the Y direction YD is 37.74 mm. The focal length fcx of the longitudinal directional adjustment unit 58 in the X direction XD is −152 mm. The focal length fcy of the longitudinal directional adjustment unit 58 in the Y direction YD is substantially infinite. The focal length fdx of the X-direction XD of the short-hand directional adjustment unit 59 is substantially infinite. The focal length fdy of the Y-direction YD of the short-hand directional adjustment unit 59 is 42.05 mm. The distance between the second lens member 50 and the third lens member 56, which can be approximated to the distance D, is 23 mm.

(Action effect)
The effects 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. Such a small light source lens element 52 is arranged with a pitch PIT smaller than the interval INT of the light source element 43, and behaves as if the light source light from the light source unit 42 is divided 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 so as to be offset in the X direction XD. 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 fail in the Y direction YD is 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 fair, 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 relatively wide, so that the light source light is preferably short in the optical path length. It can be expanded, and it is possible to realize illumination that matches the dimensions of the SD in the lateral direction of the illumination target surface 32. In the X-direction XD with respect to the Y-direction YD, the spread angle α of the split light source light in the X-direction XD emitted from each small light source by the small light source lens element 52 is relatively narrow, but the small light source array lens unit 51 is already present. Behaves like a light source with a width in the X direction and XD. Therefore, it is possible to realize the illumination according to the dimension of the longitudinal LD of the illumination target surface 32 without expanding the divided light source light from each small light source to the dimension of the longitudinal LD of the illumination target surface 32. Therefore, it is possible to reduce the need to set a long optical path length according to the X direction XD to 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 luminance unevenness of the virtual image VRI and improving the visibility of the virtual image VRI.

Further, according to the first embodiment, each small light source lens element 52 is arranged in the Y direction YD and the X direction XD, and is 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 two-dimensionally, and the small light source array lens unit 51 is a planar light source with little brightness unevenness. Can be made to work like this.

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

Further, according to the first embodiment, the short light collecting unit 53 is arranged on the illumination target surface 32 side of each small light source lens element 52 on the optical path, and collects the divided light source light in the Y direction YD. It is configured to do. By the light collection by the short light source 53, the divided light source light from each small light source lens element 52 is directed toward the illumination target surface 32, and appropriate superposition on the illumination target surface 32 is realized.

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

Further, according to the first embodiment, the directivity adjusting unit 57 is arranged on the optical path between the short condensing unit 53 and the illumination target surface 32, and the light source light incident on the small light source array lens unit 51 is provided. Adjust the directivity. The directivity for forming the visual recognition area EB is adjusted by the short condensing unit 53 at a position close to the illuminated object surface 32, that is, at a position where the superposed state of the divided light source lights is being developed. The visible area EB can be set to an appropriate range while the backlight unit 41 exerts the effect of suppressing uneven lighting on the illuminated surface 32. As a result, the visibility of the virtual image VRI is improved.

Further, according to the first embodiment, the directivity adjusting unit 57 collects 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 of the divergence, 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 easy to see with both eyes and is easy to see horizontally. As a result, the visibility of the virtual image VRI is improved.

Further, according to the first embodiment, the focal length fby of the Y-direction YD of the short-hand condensing unit 53 is smaller than the focal length fdy of the Y-direction YD of the directional adjustment unit 57, and the short-hand condensing unit 53. It is larger than the distance D between the directional adjustment unit 57 and the directional adjustment unit 57. By satisfying these conditions, the superposition 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 differences from the first embodiment.

Also in the second lens member 250 of the second embodiment, the small light source array lens unit 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) sufficiently smaller than the interval INT in which the light source elements 43 are arranged, and are spread over each other without gaps. However, the small light source lens element 252 of the second embodiment is arranged in one direction of Y direction YD. As described above, the small light source lens element 252 may be arranged in the Y direction YD in which the divided light source light is integrated among the Y direction YD and the X direction XD.

Each small light source lens element 252 has a strip shape extended 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 portion 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 bay 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 configured by each small light source lens element 252 becomes like a linear light source.

According to the second embodiment described above, each small light source lens element 252 is arranged in the Y direction YD and is formed in a cylindrical surface shape. By arranging the cylindrical small light source lens elements 252 in the Y direction YD, the difference between the absolute value of the focal length fair 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 YD in the Y direction and the optimum optical path length for XD in the X direction. Therefore, since it is easy to set the optical path length of the backlight unit 41 to an appropriate optical path length in both directions XD and YD, the HUD device 10 that suppresses the increase in physique while improving the visibility of the virtual image VRI is provided. be able to.

(Other embodiments)
Although the plurality of embodiments have been described above, the present disclosure is not construed as being limited to those embodiments, and is to be applied to various embodiments and combinations without departing from the gist of the present disclosure. Can be done.

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

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

As a modification 3, the light source unit 42 may include light source elements 43 arranged at least by a predetermined interval in the X direction XD. 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 line by being offset by a predetermined interval in the X direction XD and being offset by a different value for each light source element 43 in the Y direction YD. May be 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 alternately offset in the Y direction YD in the opposite direction.

As a modification 4, the light source unit 42 may include light source elements 43 arranged side by side with a predetermined interval INT shifted at least in the X direction XD. If a plurality of light source elements 43 are arranged two-dimensionally, a combination of light source elements 43 that are displaced from each other in the X direction XD is generated. As a specific example, a plurality of light source elements 43 may be arranged in a rectangular grid in two directions, Y direction YD and X direction XD. Further, the plurality of light source elements 43 may be arranged in a triangular grid shape, a hexagonal grid shape, or the like.

As a modification 5, the predetermined interval INT in which the light source element 43 is displaced may be modulated. In this case, the pitch PIT in which the small light source lens elements 52 are arranged may be smaller than the average interval, which is the average value of the interval INTs. However, it is more preferable that the pitch PIT is smaller than the minimum interval, which is the minimum value of each interval INT.

As the modification 6, the light source element 43 is not limited to the point light source, and a linear light source or a planar light source may be adopted. 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, for example. Further, the light source unit 42 may have a configuration in which a plurality of light source elements 43 as a planar light source are arranged so as to be separated from each other in the X direction XD.

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

As a modification 8, the diffuser plate 61 may be arranged between the second lens member 50 and the third lens member 56.

As a modification 9, the longitudinal tropism adjusting portion 58 may be formed in a single concave cylindrical surface shape instead of a Fresnel lens shape. On the contrary, the short directional adjustment unit 59 may be formed in the shape of a Fresnel lens. Further, as shown in FIGS. 10 and 11, even if at least a part of the longitudinal tropism adjusting unit 58 and the short tropism adjusting unit 59 is configured in a synthetic state by one optical surface such as a toroidal surface. good. Further, at least one of the longitudinal tropism adjusting section 58 and the short tropism adjusting section 59 may not be provided.

As a modification 10, the illumination target surface 32 as the illumination target portion of the backlight unit 41 that functions as the illumination target is not limited to a rectangular shape, but may be formed into an elliptical shape, a parallel quadrilateral shape, or the like. Further, the illuminated object portion does not have to be formed in a single surface shape, and may include a three-dimensional structure.

As a modification 11, the virtual image display device can be applied to various vehicles such as an aircraft, a ship, or a non-moving housing such as a game housing. Further, the virtual image display device can be applied to a portable information terminal such as a head-mounted display.

3a: Projection unit, 10: HUD device (imaginary image display device), 31: Image display element, 32: Illumination target surface (illumination target unit), 41: Backlight unit, 42: Light source unit, 43: Light source element, 51: Small light source array lens unit, 52: Small light source lens element, SD: Short direction, LD: Longitudinal direction, YD: Y direction (short corresponding direction), XD: X direction (longitudinal correspondence direction), INT: Spacing, PIT :pitch

Claims (7)

A virtual image display device that displays a virtual image (VRI) by projecting the display light of an image onto a projection unit (3a).
It has an illuminated object portion (32) in which the dimension in the longitudinal direction (LD) is set larger than the dimension in the lateral direction (SD), and the image is obtained by using the light source light illuminated on the illuminated object portion. The image display element (31) to be displayed and
A backlight unit (41) that irradiates the illumination target portion with the light source light is provided.
The backlight unit is
A plurality of the short-side corresponding directions (YD) corresponding to the short-side direction and the longitudinal-corresponding direction (XD) corresponding to the longitudinal direction, which are arranged with each other at least by a predetermined interval (INT) in the longitudinal-corresponding direction. A light source unit (42) having a light source element (43) and emitting the light source light from each light source element.
It is arranged on the optical path between the light source unit and the illumination target unit, and has a pitch (PIT) smaller than the interval along at least the short-side corresponding direction of the short-side corresponding direction and the long-distance corresponding direction. A small light source array lens unit having a plurality of arranged small light source lens elements (52), and each small light source lens element behaves as if the light source light from the light source unit is divided to form a new small light source. (51) and
In each the small light-source lens element, it said absolute value of the focal length of the short side corresponding direction is rather smaller than the absolute value of the focal length of the longitudinal direction corresponding,
The backlight unit is
On the optical path, the light source light divided by the small light source lens element is collectively focused on the illumination target portion side of the small light source lens element in the direction corresponding to the short side. The short light source (53) and
A directivity adjusting unit (57) arranged on the optical path between the short condensing unit and the illuminated target unit and adjusting the directivity of the light source light incident through the small light source array lens unit. Has more,
The directivity adjusting unit is a virtual image display device that collects the light source light in the direction corresponding to the short side and radiates the light source light in the direction corresponding to the longitudinal direction. The focal length of the short-hand condensing unit in the short-hand direction is smaller than the focal length of the directional adjustment unit in the short-hand direction, and the short-hand condensing unit and the directional adjustment unit The virtual image display device according to claim 1, which is larger than the distance between the two. A virtual image display device that displays a virtual image (VRI) by projecting the display light of an image onto a projection unit (3a).
It has an illuminated object portion (32) in which the dimension in the longitudinal direction (LD) is set larger than the dimension in the lateral direction (SD), and the image is obtained by using the light source light illuminated on the illuminated object portion. The image display element (31) to be displayed and
A backlight unit (41) that irradiates the illumination target portion with the light source light is provided.
The backlight unit is
A plurality of the short-side corresponding directions (YD) corresponding to the short-side direction and the longitudinal-corresponding direction (XD) corresponding to the longitudinal direction, which are arranged with each other at least by a predetermined interval (INT) in the longitudinal-corresponding direction. A light source unit (42) having a light source element (43) and emitting the light source light from each light source element.
It is arranged on the optical path between the light source unit and the illumination target unit, and has a pitch (PIT) smaller than the interval along at least the short-side corresponding direction of the short-side corresponding direction and the long-distance corresponding direction. A small light source array lens unit having a plurality of arranged small light source lens elements (52), and each small light source lens element behaves as if the light source light from the light source unit is divided to form a new small light source. (51) and
In each the small light-source lens element, it said absolute value of the focal length of the short side corresponding direction is rather smaller than the absolute value of the focal length of the longitudinal direction corresponding,
The backlight unit is
On the optical path, the light source light divided by the small light source lens element is collectively focused on the illumination target portion side of the small light source lens element in the direction corresponding to the short side. The short light source (53) and
A directivity adjusting unit (57) arranged on the optical path between the short condensing unit and the illuminated target unit and adjusting the directivity of the light source light incident through the small light source array lens unit. Has more,
The focal length of the short-hand condensing unit in the short-hand direction is smaller than the focal length of the directional adjustment unit in the short-hand direction, and the short-hand condensing unit and the directional adjustment unit A virtual image display device that is greater than the distance between. The virtual image display device according to any one of claims 1 to 3, wherein the small light source lens elements are arranged in the direction corresponding to the short side and formed in a cylindrical surface shape. The virtual image display device according to any one of claims 1 to 3 , wherein each of the small light source lens elements is arranged in the direction corresponding to the short side and the direction corresponding to the length, and is formed in a toroidal surface shape. The backlight unit integrates the light source light divided by each small light source lens element into the illuminated object portion in the direction corresponding to the short side and causes the light to be incident on the lighting target portion. The virtual image display device according to any one of claims 1 to 5 , wherein the light source is incident in a state where the integration is restricted from the direction corresponding to the short side. The small light source array lens unit constitutes an optical surface (50a) arranged on the light source side on the optical path, and the short condensing unit constitutes an optical surface arranged on the illumination target portion side on the optical path. The aspect according to any one of claims 1 to 6, wherein the small light source array lens portion and the short light collecting portion are integrally formed as a lens member (50) by forming the surface (50b). Virtual image display device.

Images