JP7090127B2 - Optical system and head-up display device - Google Patents

Description

The present invention relates to an optical system and a head-up display device.

A head-up display device is known that projects an image on a windshield (windshield) provided in a moving object such as an automobile or an aircraft, and makes it possible to observe the projected image as a virtual image through the windshield.

For example, Patent Document 1 includes, as a conventional head-up display device, a projection optical system that "irradiates light from behind a transmissive liquid crystal display panel to magnify and project an image displayed on the liquid crystal display panel (summary). Excerpt) ”The device is disclosed.

Further, Patent Document 2 states that "a first mirror and a second mirror are provided in the order of the optical path of the observer from the display device, and a virtual image is displayed by guiding the user to the viewpoint region of the observer.) Conditional expression θx> θy (Θx: incident angle in the image major axis direction in the first mirror, θy: incident angle in the image minor axis direction in the first mirror), 0.2 <D1 / Lh <0.9 (D1: image display surface of the display device) A display device (summary excerpt) that satisfies the distance between the mirror and the first mirror (the length of the optical path at the center of the viewpoint region) and Lh: the horizontal width of the virtual image visually recognized by the observer is disclosed.

Further, in Patent Document 3, "projected on the windshield so as to be provided between the windshield and the display device and to cancel the distortion caused in the image visually recognized from the eye point due to the non-planarity of the projection area. A display device for a vehicle provided with a "correction member (summary excerpt) for transmitting and correcting an image to be used" is disclosed.

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

Japanese Unexamined Patent Publication No. 2009-229552 US Patent Application Publication No. 2016/195719 US Patent Application Publication No. 2002/0894950

PIONEER R & D (Vol.22, 2013)

The head-up display device disclosed in Patent Document 2 provides a thin head-up display device by arranging the display device and the first mirror (rotational asymmetric mirror) to be horizontally displaced. However, in Example 1 of Patent Document 2, the virtual image size is as long as 140 × 70 mm, and the light flux is bent in the horizontal direction having a light flux size twice the vertical size. Therefore, the folding mirror becomes large, and it is difficult to reduce the volume of the head-up display device even with a thin head-up display device.

In the example of the head-up display device disclosed in Patent Document 3, the correction of distortion caused by the non-planarity of the projection area of the windshield is disclosed, but the distortion caused by the concave mirror disclosed in Non-Patent Document 1 is disclosed. Not considered with respect to. Also in Non-Patent Document 1, in order to correct the distortion caused by the concave mirror, the tilt of the screen and the convex lens as a field lens are arranged, but the telecentricity in the liquid crystal display panel disclosed in Patent Document 1 Not satisfied with the performance of. As described above, the actual situation 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 ensuring the required performance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to minimize the optical configuration of an optical system while ensuring the required performance, and to provide a compact head-up display device. ..

In order to solve the above-mentioned problems, the present invention includes the configurations described in the claims. As one aspect of the present invention, the image light emitted from the optical system is reflected by the windshield, and the reflected light is incident on the observer's eye. It is an optical system for displaying an imaginary image as if looking at information, and the optical system incidents a light beam from an image generation unit and displays an enlarged imaginary image of the image generated by the image generation unit. The optical system includes a concave lens, a free curved lens, and a free curved concave mirror arranged in an optical path in order from the image generation unit, and includes an emission surface of a light beam in the image generation unit. The first surface-to-plane distance between the concave lens and the facing surface facing the image generation unit is the second surface between the facing surface on which the light beam is incident and the emission surface from which the light beam is emitted from the concave lens. Shorter than the distance, the concave lens is arranged closer to the image generator than the second interplanetary distance , and in the concave lens, the incident surface of the light beam in the concave lens is the emission surface of the light beam in the image generator. It is characterized in that it is arranged so as to be substantially parallel to.

According to the present invention, it is possible to provide a compact head-up display device by minimizing the optical configuration of the optical system while ensuring the required performance. Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments.

Overall ray diagram (YZ plane) of the eyepiece optical system of the first embodiment Overall ray diagram (XZ plane) of the eyepiece optical system of the first embodiment Enlarged view of the main part of the eyepiece optical system of the first embodiment The figure which shows the lens data of the head-up display apparatus which concerns on 1st Embodiment The figure of the free-form surface coefficient of the head-up display device which concerns on 1st Embodiment The figure which shows the distortion performance seen from the center of the eye box in 1st Embodiment The figure which shows the distortion performance seen from the upper right of the eye box in 1st Embodiment The figure which shows the distortion performance seen from the upper left of the eye box in 1st Embodiment The figure which shows the distortion performance seen from the lower left of the eye box in 1st Embodiment The figure which shows the distortion performance seen from the lower right of the eye box in 1st Embodiment Spot view on the liquid crystal display panel when objects are placed on the virtual image surface Angle shift diagram of the main ray Ray1 and the virtual ray Ray0 at each angle of view position The figure which shows the angle θ of the main ray Ray1 and the virtual ray Ray0. Overall ray diagram of the eyepiece optical system of the second embodiment (YZ plane) Overall ray diagram of the eyepiece optical system of the second embodiment (XZ plane) Enlarged view of the main part of the eyepiece optical system of the second embodiment The figure which shows the lens data of the head-up display apparatus which concerns on 2nd Embodiment The figure of the free-form surface coefficient of the head-up display device which concerns on 2nd Embodiment The figure which shows the distortion performance seen from the center of the eye box in 2nd Embodiment The figure which shows the distortion performance seen from the upper right of the eye box in 2nd Embodiment The figure which shows the distortion performance seen from the upper left of the eye box in 2nd Embodiment The figure which shows the distortion performance seen from the lower left of the eye box in 2nd Embodiment The figure which shows the distortion performance seen from the lower right of the eye box in 2nd Embodiment Spot view of the head-up display device of the second embodiment Angle deviation between the main ray at each angle of view and the normal of the liquid crystal display panel The figure which shows the angle θ between the main ray and the normal line of a liquid crystal display panel. A ray diagram in which a light beam from the windshield to the light flux focusing position (exit pupil position) is projected onto the YZ cross section. A ray diagram in which a ray from a free-form surface concave mirror to a light flux condensing position (exit pupil position) is projected onto an XZ cross section. Ray tracing diagram when the aperture is placed away from the convex lens beyond the focal length of the convex lens (corresponding to a free-form surface concave mirror) A ray tracing diagram that is displayed up to the tip of the image plane to display the focused position. Ray tracing diagram with basic configuration for telecentricity and distortion correction Schematic configuration of the head-up display device Schematic configuration diagram of the image forming unit included in the head-up display device according to the third embodiment. Schematic configuration diagram of the image forming unit included in the head-up display device according to the fourth embodiment. Functional block diagram of the image forming unit Top view of a moving car as seen from the front

Hereinafter, an embodiment and various examples of the present invention will be described with reference to the drawings and the like. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these explanations, and various works by those skilled in the art are made within the scope of the technical ideas disclosed in the present specification. It can be changed and modified. Further, in all the drawings for explaining the present invention, those having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted. Hereinafter, matters common to all the embodiments will be described, and then the features of each embodiment will be described.

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

The head-up display device 30 shown in FIG. 17 reflects the image light emitted from the projection optical system 20 including the image forming unit 10 and the eyepiece optical system 5 by the windshield 6 of the automobile and incidents on the observer's eyes 9. It has a configuration to make it. With this configuration, when viewed from the observer's eye 9, it is as if the image information is being viewed on the virtual image plane 7. The direction in which the image light emitted by the image forming unit 10 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. 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, and a controller 200 for controlling the operation thereof. The image forming unit 10 irradiates the liquid crystal display panel 2 with light from the backlight 1 and emits the image information (video information) displayed on the liquid crystal display panel 2 toward the eyepiece optical system 5.

The controller 200 includes a controller 201. Various information is input to the control device 201 from an external device. For example, as an external device, a navigation device 208, which is a navigation device that generates and outputs information about the operation of a moving body equipped with a head-up display device 30, and an ECU (Electronic Control Unit) 209 that controls the operation of the moving body are controlled. It is connected to the device 201. Various sensors 210 included in the mobile body are connected to the ECU 209, and are configured to notify the detected information to the ECU 209.

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

The control device 201 includes a microcomputer 202 and a storage device 206 connected to the microcomputer 202.

The microcomputer 202 includes a RAM (Random Access Memory) 203 for storing various data from an external device, and a CPU (Central Processing Unit) that executes arithmetic processing to generate image data that is the source of an imaginary image visually recognized by an observer. It includes a 205 and a ROM (Read Only Memory) 204 that stores programs and parameters that can execute arithmetic processing in the CPU 205.

Image information is displayed on the liquid crystal display panel 2 included in the image forming unit 10 by the controller 200 having the above configuration. The image forming unit 10 emits the image information displayed on the liquid crystal display panel 2 as an image luminous flux by the luminous flux irradiated by the backlight 1.

Return to FIG. The image luminous flux formed and emitted by the image forming unit 10 is projected onto the windshield 6 by the eyepiece optical system 5. The image luminous flux projected on the windshield 6 is reflected by the windshield 6 and reaches the position of the observer's eye 9. As a result, when viewed from the observer's eye 9, the relationship is established as if the image information of the virtual image surface 7 is being viewed.

As shown in FIG. 17, consider virtual points Q1, point Q2, and point Q3 on the emission surface of the image luminous flux in the liquid crystal display panel 2. Considering the virtual points on the virtual image plane 7 to which the image luminous flux emitted from these virtual points corresponds, the points V1, the point V2, and the point V3 correspond to them as shown in FIG. The eye box 8 is a range in which the observer can visually recognize the points V1, V2, and V3 on the virtual image surface 7 even if the position of the eye 9 is moved.

FIG. 17 shows the head-up display device 30 in a side view, but since the actual configuration of the head-up display device 30 is three-dimensional, the eyebox 8 has a two-dimensional spread. As described above, 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 finder or an eyepiece of a microscope. be.

Here, an example in which the head-up display device 30 according to the present embodiment is mounted on a moving body will be described with reference to FIG. 21. FIG. 21 is a plan view of the moving vehicle 500 as viewed from the front. In the automobile 500 as shown in FIG. 21, a windshield 6 as a windshield is arranged in front of the driver's seat as a windshield.

The head-up display device 30 projects an image luminous flux onto the windshield 6 so that various information related to the operation of the automobile 500 can be visually recognized as a virtual image by an observer in the driver's seat. The position where the image luminous flux is projected is in front of or around the driver's seat. For example, the image luminous flux is projected at the position shown in the broken line rectangular region 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 and 16.

FIG. 15 is a ray diagram showing a reduced optical system when the eyepiece optical system 5 is composed of a windshield 6 and a free-form surface concave mirror 54 (a free-form surface concave mirror corresponds to a convex lens), which is the minimum necessary configuration. be. Actually, as shown in FIG. 20, the liquid crystal display panel 2 is arranged in the head-up display device 30, but in each of FIGS. 15A and 15B, the exit pupil position in the reduced optical system with the virtual image plane side as an object is shown. For the convenience of the explanation of 101, the illustration of the liquid crystal display panel is omitted, the pupil diameter is 0.001 mm, and the state of only the main ray in the state where only the windshield 6 and the free curved concave mirror 54 are configured is shown. ing.

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

FIG. 15A is a ray diagram in which light rays from the windshield 6 to the light flux focusing position 101 (exit pupil position) are projected onto the YZ cross section, and FIG. 15B is a light beam focusing position 101 (exit pupil position) from the free curved concave mirror 54. It is a ray diagram which projected the light beam to the position) on the XZ cross section.

In order to reduce the size of the head-up display device 30, it is possible to arrange the liquid crystal display panel in a place where the optical path from the windshield 6 to the free curved concave mirror 54 is avoided and as close as possible to the free curved concave mirror 54. desirable. Therefore, in the reduced optical system with the virtual image plane of FIGS. 15A and 15B as an object, the exit pupil of the eyepiece optical system 5 is located ahead of the liquid crystal display panel.

By the way, in the combination of the normal liquid crystal display panel 2 and the backlight 1, the entrance / exit side of the liquid crystal display panel is telecentric.

Here, in order to satisfy this telecentric (exit pupil distance is infinite) on the liquid crystal display panel side of FIGS. 15A and 15B, a negative refractive power (= power) is used as a field lens immediately before the liquid crystal display panel. It is necessary to place a concave lens.

The action of the field lens and the action of the free-form surface lens will be described with reference to FIGS. 16A to 16C. FIG. 16A is a ray tracing diagram when the diaphragm is arranged away from the convex lens beyond the focal length of the convex lens (corresponding to a free-form surface concave mirror). The aperture 102 is arranged away from the convex lens 103 beyond the focal length of the convex lens 103 (corresponding to the free curved concave mirror 54), and the main light ray passing through the center of the aperture 102 receives a large refractive power by the convex lens 103 and is an image. The main ray converges and is incident on the surface 104. At the same time, due to the aberration generated in the convex lens 103, the ray height H of the real ray is smaller than the height H ₀ of the paraxial ray on the image plane 104, so that barrel-shaped distortion occurs on the image plane 104.

FIG. 16B is a ray tracing diagram displayed up to the tip of the image plane 104 in order to display the condensing position 101, and it can be confirmed that the telecentricity is deteriorated.

FIG. 16C is a ray tracing diagram when a basic configuration for correcting telecentricity and distortion is used. By arranging the concave lens 51 having a focal length corresponding to the distance between the image plane 104 of FIG. 16B and the condensing position 101 immediately in front of the image plane 104, the improvement of telecentricity is mainly realized and the telecentricity is mainly arranged. The free curved lens 52 mainly corrects the distortion by bringing the ray height H of the real ray on the image plane 104 closer to the ray height H ₀ of the paraxial ray.

Here, by giving the free curved surface lens 52 itself a negative refractive power, it is possible to omit the concave lens 51, but the surface gradient of the lens surface of the free curved surface lens 52 becomes large. Therefore, by dividing the free curved surface lens 52 and the concave lens 51, the productivity of the free curved surface lens 52 is improved, and the difference between the position of the free curved surface lens 52 and the position of the concave lens 51, that is, the difference in the light beam height is. That is, the degree of freedom is effective for telecentricity and distortion correction.

The detailed definition formula will be described later, but since the free-form surface lens 52 includes an XY polynomial, it is possible to have a left-right asymmetrical / up-down asymmetrical lens action, and the left-right asymmetry generated by the windshield 6 and the left-right asymmetry. It is also effective in correcting vertically asymmetric distortion performance.

Further, the concave lens 51 is arranged so as to face the light irradiation surface of the liquid crystal display panel 2 (see FIG. 20) so that the distance from the light irradiation surface is as small as possible (when the distance is 0, the concave lens 51 is in contact with the light irradiation surface). Is desirable. Therefore, in the concave lens 51, a surface facing the light irradiation surface of the liquid crystal display panel (hereinafter referred to as “opposing surface”) is formed in a planar shape. This makes it easier to place the entire facing surface closer to the liquid crystal display panel as compared to the case where the facing surface of the concave lens 51 is formed into a concave surface. At that time, by attaching the concave lens 51 to the liquid crystal display panel 2 via the holding member 25 (see FIG. 9), it becomes easier to arrange the concave lens 51 closer to the liquid crystal display panel 2.

When the facing 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 central portion of the concave surface, so that the concave lens 51 itself needs to be arranged away from the liquid crystal display panel 2. Occurs. Further, since the displayable range of the pixels on the liquid crystal display panel 2 is larger than the effective size of the image light on the liquid crystal display panel 2 and there are structures on the outside thereof, the concave lens 51 includes them. In order to avoid structural interference, it becomes necessary to arrange the concave lens 51 further away from the liquid crystal display panel 2. From this, it is considered desirable that the surface of the concave lens 51 facing the liquid crystal display panel 2 is formed to be a flat surface rather than a concave surface.

Further, it is desirable that the concave lens 51 has optical characteristics in which the focal length of the concave lens 51 divided by the focal length of the free curved concave mirror 54 satisfies −0.6 or more and −0.3 or less.

The meaning of the condition will be described with reference to FIG. 15 in which the ray tracing is displayed by the reduced optical system. When the refractive power (= reciprocal of the focal length) of the free curved concave mirror 54 is strong, the light collecting position reflected by the free curved concave mirror 54 approaches the free curved concave mirror 54. On the contrary, when the refractive power of the free curved concave mirror 54 is weak, the light flux reflected by the free curved concave mirror 54 is separated from the free curved concave mirror 54. When the concave lens 51 for making the luminous flux into a telecentric state has a strong refractive power of the free curved concave mirror 54, it is necessary to increase the refractive power (negative value) of the concave lens 51 as well. On the contrary, when the refractive power of the free curved concave mirror 54 is weak, it is necessary to weaken the refractive power of the concave lens 51 as well. Therefore, when the focal length ratio is smaller than -0.6, the main light rays on the liquid crystal display panel 2 are in a converged state, and the main rays on the liquid crystal display panel 2 having a focal length ratio larger than -0.3 are in a divergent state. Become.

The reciprocal of the focal length is the refractive power, and a strong refractive power means that the absolute value is large, and conversely, a weak refractive power means that the absolute value is small.

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

<First Embodiment>
The first embodiment is characterized by the configuration of the eyepiece optical system 5 in the head-up display device 30 of FIG. 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 is a virtual image plane 7 in a YZ plane defined by a Z axis orthogonal to the horizontal X axis, the vertical Y axis, and the XY axis of the eye box 8. Shows how the observer sees the video information. Further, 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 of the virtual image plane 7 is viewed by the observer's eyes 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 are seen separately (see reference numeral 9 in FIG. 1B). As shown in FIG. 1A, the virtual image plane 7 is arranged at an angle with respect to the viewing direction. Specifically, the virtual image distance was increased above the field of view (on the positive side of the Y coordinate), and decreased on the lower side of the field of view (negative side of the Y coordinate). Since the windshield 6 has a shape symmetrical with respect to the left-right direction of the automobile, the range of the windshield 6 through which the effective luminous flux in the head-up display device 30 passes is displayed symmetrically.

FIG. 2 is an enlarged view of a main part of the eyepiece optical system of the first embodiment. As shown in FIG. 2, the eyepiece optical system 5 has a concave lens 51, a free curved lens 52, a folded mirror 53, and a free curved concave surface having a positive refractive power from the polarizing plate 21 (component of the liquid crystal display panel 2) side. The mirror 54 and the windshield 6 are arranged side by side. The concave lens 51 is arranged so as to face the emission 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 curved concave mirror 54. The concave lens 51 mainly realizes telecentricity, and the free-form surface lens 52 mainly corrects distortion. A head-up display device is provided by locating the folded mirror 53 under an optical path in which the light beam reflected by the windshield 6 heads toward the free curved concave mirror 54, and further by locating the free curved lens 52 under the optical path. It can be seen that the miniaturization of 30 is realized.

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 represents the case where the center position of the radius of curvature is in the traveling direction with a positive sign, and the interplane distance is the optical axis from the vertex position of each surface to the vertex position of the next surface. It represents the distance above.

As shown in FIG. 3, the facing surface 51a (see FIG. 9, FIG. 3) of the concave lens 51 facing the liquid crystal display panel 2 from the emission surface 22 of the image light in the liquid crystal display panel 2 (corresponding to the 12 surface in FIG. 3). The distance d1 between the first surfaces (see FIG. 9) up to (corresponding to the 11th surface) is 0.122, and the image light incident on the concave lens 51 from the facing surface is emitted from the concave lens 51 on the ejection surface 51b (see FIG. 9, FIG. Since the distance d2 between the second planes (see FIG. 9) up to (corresponding to the ten planes of 3) is 4.700, the distance d1 between the first planes is shorter than the distance d2 between the second planes. That is, the concave lens 51 is arranged closer to the liquid crystal display panel 2 than the thickness of the concave lens 51. The smaller the distance d1 between the first surfaces, that is, the closer the concave lens 51 is to the liquid crystal display panel 2, the more preferable it is. When d1 = 0, the concave lens 51 is arranged in contact with the liquid crystal display panel 2.

The eccentricity is the value in each of the X-axis direction, the Y-axis direction, and the Z-axis direction, the tilt is the rotation around the X-axis, the rotation around the Y-axis, and the rotation around the Z-axis. It acts in the order of eccentricity and tilt, and in "normal eccentricity", the next plane is placed at the position of the interplane distance on the new coordinate system where the eccentricity and tilt act. Decenter and return eccentricities and collapses act only in that aspect and do not affect the next aspect. The rotation around the X axis is positive when viewed from the positive direction of the X axis, the rotation around the Y axis is positive when viewed from the positive direction of the Y axis, and the rotation around the Z axis is positive when viewed from the Z axis. Counterclockwise is positive when viewed from the direction.

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

・・・（１） The second surface (windshield 6) is an anamorphic aspherical surface, and has a radius of curvature of 9686 mm (= 1 / cuy) in the Y direction and a radius of curvature of 5531 mm (= 1 / cup) in the X direction. Demanded by.

... (1)

・・・（２） FIG. 4 is a diagram of the free-form surface coefficient of the head-up display device 30 according to the first embodiment. The free-form surface coefficient in FIG. 4 is obtained by the following equation (2).

... (2)

The free-form surface coefficient C _j is a shape that is rotationally asymmetric with respect to each optical axis (Z-axis), and is a shape defined by a component of a conical term and a component of a polynomial term of XY. For example, when X is quadratic (m = 2) and Y is cubic (n = 3), the coefficient of C ₁₉ such that j = {(2 + 3) ² + 2 + 3 × 3} / 2 + 1 = 19 corresponds.

Further, the position of each optical axis of the free curved surface is determined by the amount of eccentricity / tilt in the lens data of FIG.

Below, the values such as the eyebox size and the viewing angle of the eyepiece optical system of the first embodiment are shown in the order of the horizontal direction and the vertical direction.
Eye box size 130 x 40 mm
Effective size of image light on the liquid crystal display panel 67.4 x 29.0 mm
Viewing angle (total angle of view) 10 x 4 degrees Diagonal angle 0.7 degrees Virtual image distance 16.5 m (diagonal angle direction)

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

Next, the optical performance of the first embodiment will be described with reference to FIGS. 5A to 5E, FIGS. 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 distortion diagram on the liquid crystal display panel 2 side due to a light ray passing through the center of the eye box 8 with respect to the range of the rectangular virtual image surface 7. 5B, 5C, 5D, and 5E are distortion diagrams on the liquid crystal display panel 2 side due to light rays passing through the upper right corner, upper left corner, lower left corner, and lower right corner of the eye box 8.

If an eye is positioned at each position in the eye box 8 with a rectangular image displayed on the liquid crystal display panel 2 side, the distortion opposite to that of FIGS. 5A to 5E (eg, barrel shape ⇔) Pincushion type) is observed. Since the distortion diagrams of FIGS. 5A to 5E have almost the same shape, for example, if an image matching the distortion diagrams of FIGS. 5A to 5E is displayed on the liquid crystal display panel 2, the observer has a rectangular shape without distortion. You can observe a virtual image.

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

FIG. 7A is an angle deviation diagram of the main ray Ray1 and the virtual ray Ray0 at each angle of view position. Further, FIG. 7B is a diagram showing an angle θ between the main 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 line of 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. That is, it means that the illumination optical system is tilted 13 degrees with respect to the liquid crystal display panel 2. From FIG. 7A, it can be seen that the maximum value of the angle deviation is as small as 1.9 degrees.

Therefore, according to the present embodiment, it is possible to provide a miniaturized head-up display device 30 by a projection optical system using a free curved concave mirror, a free curved lens, and a concave lens.

<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 the second embodiment, the folding mirror 53 is deleted in combination with the small liquid crystal display panel 2, and the miniaturization of the head-up display device 30 is prioritized.

FIG. 8A is an overall ray diagram of the eyepiece optical system 5 of the second embodiment, and is a virtual image plane 7 in a YZ plane defined by a Z axis orthogonal to the horizontal X axis, the vertical Y axis, and the XY axis of the eye box 8. Shows how the observer sees the video information. FIG. 8B shows how the image information of the virtual image plane 7 is viewed by the observer's eyes in the XZ plane. FIG. 9 is an enlarged view of a main part of the eyepiece optical system of the second embodiment.

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

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 of the free-form surface coefficient of the head-up display device 30 according to the second embodiment.

Below, the values such as the eyebox size and the viewing angle of the eyepiece optical system of the second embodiment are shown in the order of the horizontal direction and the vertical direction.
Eye box size 130 x 40 mm
Effective size of image light on liquid crystal display panel 39.5 x 20.4 mm
Virtual image size 240 x 90 mm
Viewing angle (total angle of view) 6.9 x 2.6 degrees Depression angle 5.1 degrees Virtual image distance 2.1 m

The value obtained by dividing the focal length of the concave lens (−90 mm) by the focal length (188 mm) of the free-form surface concave mirror is −0.48.

Next, the optical performance of the second embodiment will be described with reference to FIGS. 12A to 12E, FIGS. 13, 14A, and 14B. 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 distortion diagram on the liquid crystal display panel 2 side due to a light ray passing through the center of the eye box 8 with respect to the range of the rectangular virtual image surface 7. 12B, 12C, 12D, and 12E are distortion diagrams on the liquid crystal display panel 2 side due to light rays passing through the upper right corner, upper left corner, lower left corner, and lower right corner of the eye box 8. FIG. 13 is a spot view of the head-up display device 30 of the second embodiment. FIG. 14A is an angle deviation diagram between the main light beam at each angle of view position and the normal line of the liquid crystal display panel 2. FIG. 14B is a diagram showing an angle θ between the main light beam and the normal line of the liquid crystal display panel 2. From FIG. 14A, it can be seen that the maximum value of the angle deviation between the main ray and the normal of the liquid crystal display panel 2 is as small as 2.8 degrees.

Therefore, according to the present embodiment, it is possible to provide a miniaturized head-up display device 30 by a projection optical system using a free curved concave mirror, a free curved lens, and a concave lens.

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

In the first embodiment, the video information of 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 the image forming unit 10, a smaller liquid crystal display panel 2 is used. The image information is magnified and mapped on the screen plate (diffusing plate) by the relay optical system 3 forming the image of the light valve, and the image information is enlarged by the eyepiece optical system and displayed as a virtual image.

More specifically, the luminous flux emitted from the backlight 1 to the liquid crystal display panel 2 is incident on the relay optical system 3 as an image luminous flux including the image information displayed on the liquid crystal display panel 2. The image light is emitted from the ejection surface 401 of the screen plate 4 toward the eyepiece optical system 5. Due to the image forming 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 (diffusing plate) 4. The points P1, P2, and P3 on the liquid crystal display panel 2 correspond to the points Q1, Q2, and Q3 of the screen plate (diffusing plate) 4, respectively. By using the relay optical system 3, a liquid crystal display panel having a small display size can be used. Since the backlight 1, the liquid crystal display panel 2, the relay optical system 3, and the screen plate (diffusing plate) 4 form image information (video information) on the screen plate (diffusing plate) 4, they are collectively images. It is called a forming unit 10.

Further, the screen plate (diffusing plate) 4 is composed of a microlens array in which microlenses are arranged two-dimensionally. As a result, a diffusion action is generated, the spreading angle of the light flux emitted from the screen plate 4 is increased, and the size of the eye box 8 is set to a predetermined size. The diffusing action of the screen plate (diffusing plate) 4 can also be realized by incorporating the diffusing particles.

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

In the first embodiment, the video information of the liquid crystal display panel 2 is mapped to the screen plate 4 having a diffusion function, but instead of the configuration of the image forming unit 10, the laser light source 301 and the laser light source 301 emit light. It may be configured by using a Micro Electro Mechanical Systems (MEMS) including an optical scanning unit 302 for operating a laser beam. The optical scanning unit 302 includes a reflecting surface 302a and a reflecting surface rotation driving unit 302b. MEMS optical scans a laser to form an optical scan image on a screen plate 4 having a diffusing function. The image light is emitted from the ejection surface 401 of the screen plate 4 toward the eyepiece optical system 5. The image forming unit of the fourth embodiment arranges the position of light scanning by swinging the light beam angle with this MEMS in accordance with the position of the exit pupil. The rotation center position of the MEMS is configured according to the position assumed on the eyepiece optical system 5 side.

1 ... Backlight, 2 ... Liquid crystal display panel, 3 ... Relay optical system, 4 ... Screen plate (diffusing plate), 5 ... Eyepiece optical system, 6 ... Windshield, 7 ... Virtual image surface, 8 ... Eyebox, 9 ... Observation Human eye, 10 ... Image forming unit, 20 ... Projection optical system, 30 ... Head-up display device, 51 ... Concave lens, 52 ... Free curved lens, 53 ... Folded mirror, 54 ... Free curved concave mirror, 101 ... Condensing position , 102 ... Aperture, 103 ... Convex lens, 104 ... Image plane

Claims (12)

By reflecting the image light emitted from the optical system with the windshield and incident the reflected light on the observer's eyes, it is as if the image information is seen on the virtual image plane when viewed from the observer's eyes. It is an optical system for displaying a virtual image.
The optical system is an optical system for displaying a virtual image in which a luminous flux from an image generation unit is incident and an enlarged image of the image generated by the image generation unit is displayed.
The optical system includes a concave lens, a free-form surface lens, and a free-form surface concave mirror arranged in an optical path in order from the image generation unit.
The first surface-to-plane distance between the emission surface of the light flux in the image generation unit and the facing surface facing the image generation unit in the concave lens is such that the light beam is emitted from the facing surface on which the light beam is incident in the concave lens and the concave lens. It is shorter than the distance between the second surface and the exit surface,
The concave lens is arranged closer to the image generation unit than the second interplane distance.
The concave lens is arranged so that the incident surface of the light flux in the concave lens is substantially parallel to the emission surface of the light flux in the image generation unit.
An optical system characterized by that. The optical system according to claim 1.
The incident surface of the luminous flux in the concave lens is formed flat.
An optical system characterized by that. The optical system according to claim 1 or 2.
The value obtained by dividing the focal length of the concave lens by the focal length of the free - form surface concave mirror is −0.6 or more and −0.3 or less.
An optical system characterized by that. The optical system according to any one of claims 1, 2 and 3.
The concave lens is attached to the image generation unit via a holding member so as to face the emission surface of the light flux in the image generation unit.
An optical system characterized by that. A video generator that generates video and
It is provided with an optical system for displaying a virtual image obtained by incident a light flux from the image generation unit and enlarging the image generated by the image generation unit.
The optical system reflects the image light emitted from the optical system with a windshield and causes the reflected light to enter the observer's eye, so that the image information on the virtual image plane is viewed from the observer's eye. It is the optical system of a head-up display device that displays a virtual image as if you are looking at it.
It includes a concave lens, a free-form surface lens, and a free-form surface concave mirror arranged in the optical path in order from the image generation unit.
The first surface-to-plane distance between the emission surface of the light flux in the image generation unit and the facing surface facing the image generation unit in the concave lens is such that the light beam is emitted from the facing surface on which the light beam is incident in the concave lens and the concave lens. It is shorter than the distance between the second surface and the exit surface,
The concave lens is arranged closer to the image generation unit than the second interplane distance.
The concave lens is arranged so that the incident surface of the light flux in the concave lens is substantially parallel to the emission surface of the light flux in the image generation unit.
A head-up display device characterized by that. The head-up display device according to claim 5.
The incident surface of the luminous flux in the concave lens is formed flat.
A head-up display device characterized by that. The head-up display device according to claim 5 or 6.
The value obtained by dividing the focal length of the concave lens by the focal length of the free - form surface concave mirror is −0.6 or more and −0.3 or less.
A head-up display device characterized by that. The head-up display device according to any one of claims 5, 6 and 7.
The concave lens is attached to the image generation unit via a holding member so as to face the emission surface of the luminous flux in the image generation unit.
A head-up display device characterized by that. The head-up display device according to any one of claims 5, 6, 7, and 8.
The image generation unit includes a light source and a liquid crystal display panel, and the emission surface of the luminous flux is an emission surface of the liquid crystal display panel.
A head-up display device characterized by that. The head-up display device according to any one of claims 5, 6, 7, and 8.
The image generation unit includes a light source and a liquid crystal display panel, and the emission surface of the luminous flux is an emission surface of the liquid crystal display panel.
The liquid crystal display panel is arranged at an angle with respect to the optical axis of the luminous flux from the light source.
A head-up display device characterized by that. The head-up display device according to any one of claims 5, 6, 7, and 8.
The image generation unit includes a relay optical system and a screen plate having a diffusion function, and the emission surface of the light beam is the emission surface of the screen plate.
A head-up display device characterized by that. The head-up display device according to any one of claims 5, 6, 7, and 8.
The image generation unit includes a laser light source, an optical scanning unit that lightly scans the laser light from the laser light source by rotating a reflecting surface, and a screen plate having a diffusion function, and the emission surface of the luminous flux is the above. The exit surface of the screen plate,
A head-up display device characterized by that.

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