JP7485828B2 - vehicle - Google Patents

Description

The present invention relates to a vehicle.

2. Description of the Related Art Head-up display devices are known that project an image onto a windshield of a moving body such as an automobile or an aircraft, allowing the projected image to be observed as a virtual image through the windshield.

For example, Patent Document 1 discloses a conventional head-up display device that "includes a projection optical system that irradiates light from behind a transmissive liquid crystal display panel and enlarges and projects an image displayed on the liquid crystal display panel (summary excerpt)."

In addition, in Patent Document 2, "a first mirror and a second mirror are provided in the order of an optical path from a display device to an observer, and a virtual image is displayed by guiding the first mirror to the viewpoint area of the observer, and the conditional formula θx>θy(θ
x: angle of incidence in the image long axis direction on the first mirror, θy: angle of incidence in the image short axis direction on the first mirror), 0.2<D1/Lh<0.9 (D1: distance between the image display surface of the display device and the first mirror (optical path length at the center of the viewpoint area), Lh: horizontal width of the virtual image viewed by the observer) is satisfied (summary excerpt)."

Furthermore, in Patent Document 3, "a projection lens is provided between the windshield and the display device to offset distortions that occur in an image viewed from the eye point due to non-flatness of the projection area,
The document discloses a display device for a vehicle that includes a correction member that transmits and corrects an image projected onto the windshield (abstract excerpt).

Furthermore, Non-Patent Document 1 discloses a head-up display device including a configuration in which a screen is tilted and a convex lens is arranged as a field lens in order to correct distortion caused by a concave mirror.

JP 2009-229552 A US Patent Application Publication No. 2016/195719 US Patent Application Publication No. 2002/084950

PIONEER R&D (Vol. 22, 2013)

In the head-up display device disclosed in Patent Document 2, a display device and a first mirror (a rotationally asymmetric mirror) are arranged to be shifted in the horizontal direction, thereby providing a thin head-up display device. However, in Example 1 of Patent Document 2, the virtual image size is 140
The horizontal dimension is 70 mm x 70 mm, and the light beam is folded in the horizontal direction with a light beam size twice the vertical size. Therefore, the folding mirror is large, and it is difficult to reduce the volume of the head-up display device even if it is a thin head-up display device.

The example of a head-up display device disclosed in Patent Document 3 discloses correction of distortion caused by non-flatness of the projection area of the windshield, but does not take into consideration the distortion caused by the concave mirror disclosed in Non-Patent Document 1. In Non-Patent Document 1, the screen is tilted and a convex lens is arranged as a field lens to correct the distortion caused by the concave mirror, but the telecentric performance of the liquid crystal display panel disclosed in Patent Document 1 is not satisfied. Thus, the reality is that there is room for further improvement in the projection optical system and the head-up display device in order to reduce the size of the device while maintaining the required performance.

The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a vehicle equipped with a small head-up display device that minimizes the optical configuration of the optical system while ensuring the necessary performance.

In order to solve the above problems, the present invention has the configuration described in the claims. One aspect of the present invention is a vehicle that includes a head-up display device having a windshield, an image generating unit that generates an image, and an optical system that receives light from the image generating unit and displays a virtual image that is an enlarged version of the image generated by the image generating unit. The optical system reflects the image light emitted from the optical system on the windshield and causes the reflected light to enter the driver's eye, thereby displaying a virtual image as if the driver were viewing image information on a virtual image surface. The optical system includes a concave lens, a free-form lens, and a free-form concave mirror arranged in the optical path in this order from the image generating unit, and a first inter-surface distance between the exit surface of the image generating unit from the light beam and the opposing surface of the concave lens that faces the image generating unit is shorter than a second inter-surface distance between the opposing surface of the concave lens where the light beam is incident and the exit surface from which the light beam is emitted from the concave lens, the concave lens is arranged closer to the image generating unit than the second inter-surface distance, and the concave lens is arranged so that the entrance surface of the light beam in the concave lens is approximately parallel to the exit surface of the light beam in the image generating unit.

According to the present invention, it is possible to provide a vehicle equipped with a small head-up display device by minimizing the optical configuration of the optical system while ensuring the required performance. Note that problems, configurations, and effects other than those described above will become apparent from the description of the following embodiments.

FIG. 1 is a ray diagram of the entire eyepiece optical system according to the first embodiment (YZ plane); FIG. 1 is an overall ray diagram (XZ plane) of the eyepiece optical system of the first embodiment; FIG. 1 is an enlarged view of a main portion of an eyepiece optical system according to a first embodiment. FIG. 1 is a diagram showing lens data of the head-up display device according to the first embodiment; FIG. 1 is a diagram showing free-form surface coefficients of the head-up display device according to the first embodiment; FIG. 13 is a diagram showing distortion performance as viewed from the center of the eye box in the first embodiment. FIG. 13 is a diagram showing distortion performance as viewed from the upper right of the eye box in the first embodiment. FIG. 13 is a diagram showing distortion performance when viewed from the upper left of the eye box in the first embodiment. FIG. 13 is a diagram showing distortion performance as viewed from the bottom left of the eye box in the first embodiment. FIG. 13 is a diagram showing distortion performance as viewed from the lower right of the eye box in the first embodiment. Spot diagram on the LCD panel when an object point is placed on the virtual image plane Diagram of the angle deviation between the principal ray Ray1 and the virtual ray Ray0 at each angle of view A diagram showing the angle θ between the principal ray Ray1 and the virtual ray Ray0 FIG. 11 is a ray diagram of the entire eyepiece optical system according to the second embodiment (YZ plane); FIG. 11 is a ray diagram of the entire eyepiece optical system according to the second embodiment (XZ plane); FIG. 13 is an enlarged view of a main portion of an eyepiece optical system according to a second embodiment. FIG. 13 is a diagram showing lens data of the head-up display device according to the second embodiment; FIG. 11 is a diagram showing free-form surface coefficients of the head-up display device according to the second embodiment. FIG. 13 is a diagram showing distortion performance as viewed from the center of the eye box in the second embodiment. FIG. 13 is a diagram showing distortion performance as viewed from the upper right of the eye box in the second embodiment. FIG. 13 is a diagram showing distortion performance when viewed from the upper left of the eye box in the second embodiment. FIG. 13 is a diagram showing distortion performance as viewed from the bottom left of the eye box in the second embodiment. FIG. 13 is a diagram showing distortion performance as viewed from the lower right of the eye box in the second embodiment. Spot diagram of the head-up display device of the second embodiment Diagram of the angle deviation between the chief ray and the normal line of the LCD panel at each angle of view A diagram showing the angle θ between the chief ray and the normal to the liquid crystal display panel. Ray diagram showing the rays from the windshield to the condensing position (exit pupil position) of the light beam projected onto the YZ cross section. Ray diagram showing the light rays projected on the XZ cross section from the free-form concave mirror to the light beam focusing position (exit pupil position). Ray tracing diagram when the aperture is placed farther away from a convex lens (corresponding to a free-form concave mirror) than the focal length of the convex lens. Ray tracing diagram showing the focus beyond the image plane Ray tracing diagram using the basic configuration to correct telecentricity and distortion Schematic diagram of a head-up display device FIG. 13 is a schematic configuration diagram of an image forming unit included in a head-up display device according to a third embodiment. FIG. 13 is a schematic configuration diagram of an image forming unit included in a head-up display device according to a fourth embodiment. Functional block diagram of the image forming unit A plan view of a moving vehicle, a car, seen from the front

Hereinafter, an embodiment of the present invention and various examples will be described with reference to the drawings. The following description shows a specific example of the contents of the present invention, and the present invention is not limited to these descriptions. Various changes and modifications are possible by those skilled in the art within the scope of the technical ideas disclosed in this specification. In addition, in all drawings for explaining the present invention, parts having the same functions are given the same reference numerals, and repeated explanations may be omitted. Below, matters common to all embodiments will be described, followed by the features of each embodiment.

The basic configuration of the head-up display device 30 will be described with reference to Fig. 17. Fig. 17 is a schematic diagram of the head-up display device 30.

The head-up display device 30 shown in Fig. 17 has a configuration in which image light emitted from a projection optical system 20 including an image forming unit 10 and an eyepiece optical system 5 is reflected by a windshield 6 of a vehicle and made to enter an observer's eye 9. With this configuration, when viewed from the observer's eye 9, it appears as if the observer is viewing image information on a virtual image plane 7.
The direction in which the image light emitted at 0 passes through the eyepiece optical system 5 and is reflected by the windshield 6 corresponds to the emission direction of the image light.

First, the image forming unit 10 will be described with reference to Fig. 20. Fig. 20 is a functional block diagram of the image forming unit. As shown in Fig. 20, the image forming unit 10 includes a liquid crystal display panel 2, a backlight 1, a controller 200 that controls the operations of these, and
The image forming unit 10 irradiates light from the backlight 1 onto the liquid crystal display panel 2 , and outputs image information (video information) displayed on the liquid crystal display panel 2 towards the eyepiece optical system 5 .

The controller 200 includes a control device 201. Various information is input to the control device 201 from external devices. For example, the external devices include a navigation device 208 that generates and outputs information related to the operation of a mobile object equipped with the head-up display device 30, and an ECU (Electronic Control Unit) that controls the operation of the mobile object.
A vehicle control unit (ECU) 209 is connected to the control device 201. The ECU 209 is connected to various sensors 210 provided in the vehicle, and configured to notify the ECU 209 of detected information.

The controller 200 includes a control device 201 that processes various data from the external devices described above, and a backlight drive circuit 207 that drives the backlight 1 .

The control device 201 includes a microcomputer 202 and a memory device 206 connected thereto.

The microcomputer 202 includes a RAM (Random Access Memory) for storing various data from external devices.
A central processing unit (CPU) 203 executes calculations to generate image data that is the basis of a virtual image that is visually recognized by an observer.
and a ROM (Read Only Memory) 204 that stores programs and parameters that can execute the arithmetic processing in the CPU 205.

The controller 200 having the above configuration displays image information on the liquid crystal display panel 2 included in the image forming unit 10. The image forming unit 10 outputs the image information displayed on the liquid crystal display panel 2 as an image light beam by using a light beam irradiated by the backlight 1.

Returning to Fig. 17, the image light beam formed and emitted by the image forming unit 10 is projected onto the windshield 6 by the eyepiece optical system 5. The image light beam projected onto the windshield 6 is reflected by the windshield 6 and reaches the position of the observer's eye 9. This creates a relationship as if the observer were looking at the image information on the virtual image plane 7 when looking through the observer's eye 9.

As shown in FIG. 17, on the exit surface of the liquid crystal display panel 2 for the image light beam, points Q1 and Q
Consider virtual points Q1, Q2, and Q3 on the virtual image plane 7. If we consider the virtual points on the virtual image plane 7 to which the image light beams emitted from these virtual points correspond, they are points V1, V2, and V3 as shown in Figure 17. The range in which the observer can view points V1, V2, and V3 on the virtual image plane 7 even if he or she moves the position of his or her eye 9 is the eye box 8.

17 illustrates the head-up display device 30 from a side view, but the actual configuration of the head-up display device 30 is three-dimensional, so the eye box 8 has a two-dimensional expansion. In this manner, the eyepiece optical system 5 is an optical system that displays an image (virtual image) of an object (spatial image) in front of the observer's eye, similar to the eyepiece of a camera viewfinder or the eyepiece of a microscope.

Here, an example of a case where the head-up display device 30 according to this embodiment is mounted on a moving body will be described with reference to Fig. 21. Fig. 21 is a plan view of an automobile 500, which is a moving body, as seen from the front. In the automobile 500 shown in Fig. 21, a windshield 6, which is a front glass as a windshield, is disposed in front of the driver's seat.

The head-up display device 30 projects an image light beam onto the windshield 6, allowing an observer in the driver's seat to visually recognize various information related to the operation of the automobile 500 as a virtual image. The image light beam is projected onto a position in front of or around the driver's seat. For example, the image light beam is projected onto a position shown in a dashed rectangular area R1.

The conditions of the pupil position required for the eyepiece optical system 5 of the head-up display device 30 will be described with reference to FIGS.

15 is a ray diagram showing a reduced optical system in which the eyepiece optical system 5 is configured with the minimum necessary components, a windshield 6 and a free-form concave mirror 54 (a free-form concave mirror corresponds to a convex lens).
15A and 15B omit the illustration of the liquid crystal display panel for the convenience of explaining the exit pupil position 101 in a reduction optical system in which the virtual image surface side is the object, and illustrate the state of only the chief ray in a configuration in which the pupil diameter is 0.001 mm and only the windshield 6 and free-form concave mirror 54 are used.

In the coordinate system of FIGS. 15A and 15B, the horizontal direction of the eye box 8 is the X axis, the vertical direction is the Y axis,
The direction perpendicular to the XY plane is defined as the Z axis.

FIG. 15A is a ray diagram showing the light rays projected from the windshield 6 to the focusing position 101 (exit pupil position) of the light beam onto the YZ cross section, and FIG. 15B is a ray diagram showing the light rays projected from the free-form concave mirror 54 to the focusing position 101 (exit pupil position) of the light beam onto the XZ cross section.

In order to reduce the size of the head-up display device 30, it is desirable to place the liquid crystal display panel in a location that avoids the optical path from the windshield 6 to the free-form concave mirror 54 and is as close to the free-form concave mirror 54 as possible. Therefore, in the reduction optical system in which the virtual image plane of Figures 15A and 15B is the object, the exit pupil of the eyepiece optical system 5 is located past the liquid crystal display panel.

Incidentally, a typical combination of a liquid crystal display panel 2 and a backlight 1 is telecentric on the input and output sides of the liquid crystal display panel.

Here, in order to achieve this telecentricity (exit pupil distance is infinite) on the liquid crystal display panel side in Figures 15A and 15B, it is necessary to place a concave lens with negative refractive power (= power) as a field lens immediately before the liquid crystal display panel.

The action of the field lens and the action of the free curved lens will be described with reference to Figures 16A to 16C. Figure 16A is a ray tracing diagram in the case where the diaphragm is placed away from the convex lens (corresponding to a free curved concave mirror) at a distance greater than the focal length of the convex lens.
The aperture 102 is disposed at a distance from the convex lens 103 that is greater than the focal length of the aperture 102 (corresponding to the free-form concave mirror 54). The principal ray passing through the center of the aperture 102 is subjected to a large refractive power by the convex lens 103.
The chief ray is converged and incident on the image plane 104. At the same time, due to aberration occurring in the convex lens 103, the ray height H of the actual ray is smaller than the ray height _H0 of the paraxial ray on the image plane 104, so that a barrel-shaped distortion occurs on the image plane 104.

FIG. 16B is a ray tracing diagram showing the light collection position 101 up to the image plane 104, and it can be seen that the telecentricity has deteriorated.

Fig. 16C is a ray tracing diagram when using a basic configuration for correcting telecentricity and distortion. By arranging a concave lens 51 having a focal length equivalent to the distance between the image plane 104 and the light collecting position 101 in Fig. 16B immediately before the image plane 104, mainly improvement of telecentricity is realized, and by arranging a free-form surface lens 52 in front of the concave lens 51, the ray height H of the real ray on the image plane 104 is made close to the ray height _H0 of the paraxial ray, mainly distortion is corrected.

Here, it is possible to omit the concave lens 51 by giving the free-form surface lens 52 itself a negative refractive power, but this would increase the surface gradient of the lens surface of the free-form surface lens 52. Therefore, by separating the free-form surface lens 52 from the concave lens 51, the productivity of the free-form surface lens 52 is improved, and the difference between the positions of the free-form surface lens 52 and the concave lens 51, i.e., the difference in ray height, i.e., the degree of freedom, is effective for telecentricity and distortion correction.

Although the detailed defining formula will be explained later, because the free-form surface lens 52 includes an XY polynomial, it is possible to give it a lens action that is asymmetric left-right and up-down, and it is also effective in correcting the asymmetric left-right and up-down distortion performance that occurs in the windshield 6.

In addition, it is desirable to place the concave lens 51 facing the light irradiation surface of the liquid crystal display panel 2 (see FIG. 20) with the distance from the light irradiation surface as small as possible (when the distance is 0, the concave lens 51 is in contact with the light irradiation surface).
In this case, the concave lens 51 is attached to the liquid crystal display panel 2 via a holding member 25 (see FIG. 9 ), which makes it easier to position the concave lens 51 closer to the liquid crystal display panel 2 than when the concave lens 51 has a concave facing surface.

In addition, when the opposing surface of the concave lens 51 is formed as a concave surface, the end portion of the concave surface is closer to the liquid crystal display panel 2 than the center portion of the concave surface, so that it becomes necessary to dispose the concave lens 51 itself away from the liquid crystal display panel 2. Furthermore, if the effective size of the image light on the liquid crystal display panel 2 is larger than the effective size of the image light on the liquid crystal display panel 2,
The displayable range of the pixels in the liquid crystal display panel 2 is large, and there are structures outside of that range. In order to avoid structural interference with the concave lens 51, including those structures, the concave lens 51 is further
It becomes necessary to place the concave lens 51 away from the liquid crystal display panel 2.
It is considered desirable that the surface of the liquid crystal display device 2 facing the liquid crystal display panel 2 be formed as a flat surface rather than a concave surface.

Moreover, it is desirable for the concave lens 51 to have optical characteristics such that the value obtained by dividing the focal length of the concave lens 51 by the focal length of the free curved concave mirror 54 is equal to or greater than −0.6 and equal to or less than −0.3.

The meaning of the condition will be explained using FIG. 15 showing ray tracing in a reduction optical system. When the refractive power (= the reciprocal of the focal length) of the free-form concave mirror 54 is strong, the focusing position of the light beam reflected by the free-form concave mirror 54 approaches the free-form concave mirror 54. Conversely, when the refractive power of the free-form concave mirror 54 is weak, the focusing position of the light beam reflected by the free-form concave mirror 54 moves away from the free-form concave mirror 54. And, when the refractive power of the free-form concave mirror 54 is strong, the refractive power (negative value) of the concave lens 51 for making the light beam telecentric needs to be strong. Conversely, when the refractive power of the free-form concave mirror 54 is weak, the refractive power of the concave lens 51 needs to be weak. Therefore, when the focal length ratio is smaller than -0.6, the chief ray at the liquid crystal display panel 2 is in a convergent state, and when the focal length ratio is greater than -0.3, the chief ray at the liquid crystal display panel 2 is in a divergent state.

Incidentally, the reciprocal of the focal length is the refractive power, and strong refractive power means that its absolute value is large, while weak refractive power means that its absolute value is small.

Next, a free-form concave mirror 54 that can realize a small head-up display device 30 is
A first embodiment of a projection optical system using a free curved surface lens 52 and a concave lens 51 will be described.

First Embodiment
The first embodiment is characterized by the configuration of the eyepiece optical system 5 of the head-up display device 30 in Fig. 17. The windshield 6 and the eyepiece optical system 5 constituting the projection optical system will be described with reference to Fig. 1. Fig. 1A is an overall ray diagram of the eyepiece optical system 5 of the first embodiment, and shows a state in which the image information on the virtual image surface 7 is viewed by the observer's eye in the YZ plane defined by the horizontal X-axis, vertical Y-axis, and Z-axis perpendicular to the XY-axis of the eyebox 8. Fig. 1B is an overall ray diagram of the eyepiece optical system 5 of the first embodiment, and shows a state in which the image information on the virtual image surface 7 is viewed by the observer's eye in the XZ plane.

In the YZ plane, the right eye and the left eye overlap (see reference numeral 9 in FIG. 1A), and in the XZ plane, the right eye and the left eye see separately (see reference numeral 9 in FIG. 1B). As shown in FIG. 1A, the virtual image surface 7 is disposed at an angle to the direction of the field of view. Specifically, the virtual image distance is made larger in the upper part of the field of view (positive side of the Y coordinate) and smaller in the lower part of the field of view (negative side of the Y coordinate). Windshield 6
Since the head-up display device 30 has a symmetrical shape with respect to the left-right direction of the vehicle,
The range of the windshield 6 through which the effective light beam passes is shown symmetrically.

2 is an enlarged view of the main part of the eyepiece optical system of the first embodiment. As shown in FIG. 2, the eyepiece optical system 5 is configured by arranging a concave lens 51, a free-form surface lens 52, a return mirror 53, a free-form surface concave mirror 54 with positive refractive power, and a windshield 6 from the polarizing plate 21 (a component of the liquid crystal display panel 2) side. The concave lens 51 is arranged facing the exit surface 22 of the image light of the liquid crystal display panel 2. The refractive power of the eyepiece optical system 5 is mainly borne by the free-form surface concave mirror 54. The concave lens 51 mainly realizes telecentricity, and the free-form surface lens 52 mainly corrects distortion. It can be seen that the return mirror 53 is located under the optical path of the light beam reflected by the windshield 6 toward the free-form surface concave mirror 54, and the free-form surface lens 52 is further located under the optical path, thereby realizing the miniaturization of the head-up display device 30.

Fig. 3 is a diagram showing lens data of the head-up display device 30 according to the first embodiment. In the lens data shown in Fig. 3, the radius of curvature is indicated by a positive sign when the center position of the radius of curvature is in the traveling direction, and the inter-surface distance indicates the distance on the optical axis from the vertex position of each surface to the vertex position of the next surface.

As shown in FIG. 3, the first inter-surface distance d1 (see FIG. 9) from the exit surface 22 (corresponding to surface 12 in FIG. 3) of the image light in the liquid crystal display panel 2 to the facing surface 51a (see FIG. 9, corresponding to surface 11 in FIG. 3) of the concave lens 51 facing the liquid crystal display panel 2 is 0.122, and the second inter-surface distance d2 (see FIG. 9) from the facing surface to the exit surface 51b (see FIG. 9, corresponding to surface 10 in FIG. 3) from which the image light incident on the concave lens 51 exits from the concave lens 51 is 4.700, so that the first inter-surface distance d1 is shorter than the second inter-surface distance d2. That is, the concave lens 51 is disposed closer to the liquid crystal display panel 2 than the thickness of the concave lens 51. The smaller the first inter-surface distance d1 is, that is, the closer the concave lens 51 is to the liquid crystal display panel 2, the more preferable it is, and when d1=0, the concave lens 51 is disposed in contact with the liquid crystal display panel 2.

The eccentricity is the value in the X-axis, Y-axis, and Z-axis directions, and the tilt is the rotation around the X-axis and the Y-axis.
Rotation around the axis and rotation around the Z axis. Eccentricity and tilt act on the relevant surface in the order of eccentricity and tilt. In "normal eccentricity", the next surface is placed at the position of the inter-surface distance on the new coordinate system where the eccentricity and tilt acted. In decenter and return, eccentricity and tilt act only on that surface.
It does not affect the next surface. Note that rotation around the X-axis is positive when viewed from the positive direction of the X-axis, rotation around the Y-axis is positive when viewed from the positive direction of the Y-axis, and rotation around the Z-axis is positive when viewed from the positive direction of the Z-axis.

The glass material name 50.30 indicates a material with a refractive index of 1.50 and an Abbe number of 30, and the glass material name 52.60 indicates a material with a refractive index of 1.52 and an Abbe number of 60.

・・・（１） The second surface (windshield 6) is an anamorphic aspheric surface with a radius of curvature of 9 in the Y direction.
Using the radius of curvature in the X direction of 686 mm (=1/cuy) and the radius of curvature in the X direction of 5531 mm (=1/cux), the value can be calculated using the following formula (1).

... (1)

・・・（２） Fig. 4 is a diagram of free-form surface coefficients of the head-up display device 30 according to the first embodiment. The free-form surface coefficients in Fig. 4 are calculated by the following formula (2).

... (2)

The free curved surface coefficient _Cj is a shape that is rotationally asymmetric with respect to each optical axis (Z axis) and is a shape defined by the components of the cone term and the components of the polynomial term of XY. For example, when X is quadratic (m=2
) and Y is cubic (n=3), then there are ₁₉ coefficients in C, where j={(2+3) ² +2+3×3}/2+1=19.

Furthermore, the position of each optical axis of the free curved surface is determined by the amount of decentering and tilting in the lens data of FIG.

Below, values such as the eyebox size and the viewing angle of the eyepiece optical system of the first embodiment are shown in the horizontal and vertical directions.
Eye box size: 130 x 40 mm
Effective size of image light on LCD panel: 67.4 x 29.0 mm
Field of view (full field of view): 10 x 4 degrees Dip angle: 0.7 degrees Virtual image distance: 16.5 m (dip direction)

The focal length of the concave lens (-143 mm) is the focal length of the free-form concave mirror (355 mm).
The value divided by this is −0.40.

Next, the optical performance of the first embodiment will be described with reference to FIGS. 5A to 5E, 6, 7A, and 7B.

5A to 5E are diagrams showing the distortion performance of the head-up display device 30 of the first embodiment. More specifically, Fig. 5A is a diagram showing distortion on the liquid crystal display panel 2 side caused by a ray passing through the center of the eye box 8 for the range of the rectangular virtual image surface 7.
5D and 5E are diagrams showing distortions on the liquid crystal display panel 2 side caused by light rays passing through the upper right corner, upper left corner, lower left corner, and lower right corner of the eye box 8. FIG.

If a rectangular image is displayed on the liquid crystal display panel 2 and the eye is positioned at each position within the eye box 8, the opposite distortion (e.g. barrel shape ⇔ pincushion shape) to that shown in Figures 5A to 5E will be observed.
If an image conforming to the distortion diagram of E is displayed on the liquid crystal display panel 2, the observer can observe a rectangular virtual image without distortion.

FIG. 6 is a spot diagram of the head-up display device 30 of the first embodiment.
is a spot diagram on the liquid crystal display panel 2 when an object point is placed on the virtual image plane. The spot diagram of the light beam passing through the entire eye box 8 is shown in Fig. 1 for red (650 nm) and green (550 nm).
) and blue (450 nm) separately. In this spot diagram, the size of the eye box 8 is 130 mm horizontally × 40 mm vertically for the total luminous flux, and in the case of a virtual image seen by an actual observer, the spot diagram for the size of the iris of the human eye (said to be φ7 mm at maximum) is significantly improved. Here, the spot diagram is a diagram in which the spot diagram at each position of the liquid crystal display panel 2 in a reduced optical system with the virtual image as the object surface is magnified and emphasized by 5 times.

Fig. 7A is a diagram showing the angle deviation between the principal ray Ray1 and the virtual ray Ray0 at each angle of view. Fig. 7B is a diagram showing the angle θ between the principal ray Ray1 and the virtual ray Ray0. As shown in Fig. 7B, the virtual ray Ray0 is a straight line obtained by rotating the normal to the liquid crystal display panel 2 by 13 degrees around a rotation axis parallel to the long side of the liquid crystal display panel 2. In other words, this means that the illumination optical system is disposed with an inclination of 13 degrees with respect to the liquid crystal display panel 2. Fig. 7A shows that the maximum angle deviation is small, at 1.9 degrees.

Therefore, according to this embodiment, a projection optical system using a free-form concave mirror, a free-form lens, and a concave lens can provide a compact head-up display device 30.

Second Embodiment
The second embodiment is characterized in that the configuration of the eyepiece optical system 5 is different from that of the first embodiment.
In this embodiment, a small-sized liquid crystal display panel 2 is combined with the head-up display device 30, and the folding mirror 53 is omitted, giving priority to miniaturization of the head-up display device 30.

Fig. 8A is an overall ray diagram of the eyepiece optical system 5 of the second embodiment, and shows the state in which the image information on the virtual image surface 7 is viewed by the observer's eye in the YZ plane defined by the horizontal X-axis, vertical Y-axis, and Z-axis perpendicular to the XY-axis of the eyebox 8. Fig. 8B shows the state in which the image information on the virtual image surface 7 is viewed by the observer's eye in the XZ plane. Fig. 9 is an enlarged view of the main part of the eyepiece optical system of the second embodiment.

As shown in Figures 8A, 8B, and 9, the eyepiece optical system 5 is arranged, from the polarizing plate 21 (a component of the liquid crystal display panel 2) side, with a concave lens 51, a free-form surface lens 52, and a free-form concave mirror 54 with positive refractive power, followed by a windshield.

Fig. 10 is a diagram showing lens data of the head-up display device 30 according to the second embodiment. Fig. 11 is a diagram showing free-form surface coefficients of the head-up display device 30 according to the second embodiment.

The eyebox size, viewing angle, and other values of the eyepiece optical system of the second embodiment are shown below in the horizontal and vertical directions.
Eye box size: 130 x 40 mm
Effective size of image light on LCD panel: 39.5 x 20.4 mm
Virtual image size: 240 x 90 mm
Field of view (full field of view): 6.9 x 2.6 degrees Dip angle: 5.1 degrees Virtual image distance: 2.1 m

The focal length of the concave lens (-90 mm) divided by the focal length of the free-form concave mirror (188 mm) is -0.48.

Next, the optical performance of the second embodiment will be described with reference to FIGS. 12A to 12E, 13, 14A, and 1
4B. Figs. 12A to 12E are diagrams showing the distortion performance of the head-up display device 30 of the second embodiment. More specifically, Fig. 12A is a diagram showing distortion on the liquid crystal display panel 2 side caused by a ray of light passing through the center of the eye box 8 for the range of the rectangular virtual image surface 7. Figs. 12B, 12C, 12D, and 12E are diagrams showing distortion on the liquid crystal display panel 2 side caused by a ray of light passing through each of the upper right corner, upper left corner, lower left corner, and lower right corner of the eye box 8. Fig. 13 is a spot diagram of the head-up display device 30 of the second embodiment. Fig. 14A is a
14A is a diagram showing the angle deviation between the chief ray and the normal line to the liquid crystal display panel 2 at each view angle position. Fig. 14B is a diagram showing the angle θ between the chief ray and the normal line to the liquid crystal display panel 2. It can be seen from Fig. 14A that the maximum angle deviation between the chief ray and the normal line to the liquid crystal display panel 2 is small at 2.8 degrees.

Therefore, according to this embodiment, a projection optical system using a free-form concave mirror, a free-form lens, and a concave lens can provide a compact head-up display device 30.

Third Embodiment
The third embodiment is characterized in that the configuration of the image forming unit 10 is different from that of the first and second embodiments. The third embodiment will be described with reference to FIG. 18. FIG.
FIG. 2 is a schematic configuration diagram of an image forming unit included in the head-up display device according to the embodiment.

In the first embodiment, the image information on the liquid crystal display panel 2 is directly enlarged by the eyepiece optical system 5 and displayed as a virtual image, but instead of the configuration of this image forming unit 10, a smaller liquid crystal display panel 2 is used, and the image information is enlarged and projected onto a screen plate (diffusion plate) by the relay optical system 3 that forms an image of the light valve, and the image information is then enlarged by the eyepiece optical system and displayed as a virtual image.

More specifically, the light beam irradiated from the backlight 1 to the liquid crystal display panel 2 enters the relay optical system 3 as an image light beam containing image information displayed on the liquid crystal display panel 2. The image light is emitted from the exit surface 401 of the screen plate 4 toward the eyepiece optical system 5. Due to the imaging action of the relay optical system 3, the image information on the liquid crystal display panel 2 is enlarged and projected on the screen plate (diffusion plate) 4. Points P1, P2, and P3 on the liquid crystal display panel 2 correspond to points Q1, Q2, and Q3 on the screen plate (diffusion plate) 4, respectively. By using the relay optical system 3,
A liquid crystal display panel with a small display size can be used. The backlight 1, the liquid crystal display panel 2, the relay optical system 3, and the screen plate (diffusion plate) 4 are
4, image information (video information) is formed on the image forming unit 10.

The screen plate (diffusion plate) 4 is composed of a microlens array in which microlenses are arranged two-dimensionally, which creates a diffusing effect, increasing the spread angle of the light beam emitted from the screen plate 4 and making the size of the eye box 8 a predetermined size.
The diffusing effect of the screen plate (diffusing plate) 4 can also be realized by incorporating diffusing particles therein.

Fourth Embodiment
The fourth embodiment is characterized in that the configuration of the image forming unit 10 is different from that of the first and second embodiments. The fourth embodiment will be described with reference to FIG. 19. FIG.
FIG. 2 is a schematic configuration diagram of an image forming unit included in the head-up display device according to the embodiment.

In the first embodiment, the image information of the liquid crystal display panel 2 is projected onto the screen plate 4 having a diffusion function. However, instead of the configuration of the image forming unit 10, a micro electro mechanical system (MEMS: Micro Electro Mechanical System) including a laser light source 301 and an optical scanning unit 302 that manipulates the laser light emitted from the laser light source 301 may be used.
The fourth embodiment may be configured using a MEMS. The optical scanning unit 302 includes a reflecting surface 302a and a reflecting surface rotation drive unit 302b. The MEMS optically scans a laser to form an optically scanned image on a screen plate 4 having a diffusion function. The image light is emitted from an exit surface 401 of the screen plate 4 towards the eyepiece optical system 5. The image forming unit of the fourth embodiment positions the optical scanning position to match the exit pupil position by changing the light ray angle with the MEMS. The rotation center position of the MEMS is configured to match the position assumed on the eyepiece optical system 5 side.

1...backlight, 2...liquid crystal display panel, 3...relay optical system, 4...screen plate (diffusion plate), 5...ocular optical system, 6...windshield, 7...virtual image surface, 8...eye box, 9...observer's eye, 10...image forming unit, 20...projection optical system, 30...head-up display device, 51...concave lens, 52...free-form lens, 53...folding mirror, 54...free-form concave mirror, 101...focus position, 102...aperture, 103...convex lens, 104...image surface

Claims (8)

A vehicle,
Windshield and
a head-up display device including an image generating unit that generates an image, and an optical system that receives a light beam from the image generating unit and displays a virtual image by enlarging the image generated by the image generating unit,
the optical system reflects image light emitted from the optical system by the windshield and causes the reflected light to enter the driver's eye, thereby displaying a virtual image as if the driver were viewing image information on a virtual image plane, when viewed by the driver's eye;
The optical system includes a concave lens, a free-form lens, and a free-form concave mirror arranged in this order from the image generating unit to the optical path,
a first inter-surface distance between an emission surface of the image generating unit from which the light beam is emitted and an opposing surface of the concave lens facing the image generating unit is shorter than a second inter-surface distance between the opposing surface of the concave lens, on which the light beam is incident, and an emission surface from which the light beam is emitted from the concave lens;
the concave lens is disposed closer to the image generating unit than the second inter-surface distance,
the concave lens is disposed so that an incident surface of the concave lens for receiving a light beam is substantially parallel to an exit surface of the image generating unit for receiving a light beam.
vehicle. 2. A vehicle as claimed in claim 1,
The concave lens has a plane on which the light beam is incident.
vehicle. 2. A vehicle as claimed in claim 1,
a value obtained by dividing the focal length of the concave lens by the focal length of the free-form concave mirror is equal to or greater than −0.6 and equal to or less than −0.3;
vehicle. 2. A vehicle as claimed in claim 1,
the concave lens is attached to the image generating unit via a holding member so as to face the exit surface of the image generating unit for the light beam;
vehicle. 2. A vehicle as claimed in claim 1,
The image generating unit includes a light source and a display panel, and the exit surface of the light beam is an exit surface of the display panel.
vehicle. 2. A vehicle as claimed in claim 1,
the image generating unit includes a light source and a display panel, the exit surface of the light beam is an exit surface of the display panel,
the display panel is disposed at an angle with respect to an optical axis of a light beam from the light source.
vehicle. 2. A vehicle as claimed in claim 1,
The image generating unit includes a relay optical system and a screen plate having a diffusion function, and the exit surface of the light beam is the exit surface of the screen plate.
vehicle. 2. A vehicle as claimed in claim 1,
The image generating unit includes a laser light source, a light scanning unit that optically scans the laser light from the laser light source by rotating a reflection surface, and a screen plate having a diffusion function, and the exit surface of the light beam is the exit surface of the screen plate.
vehicle.