JP6675059B2 - Head-up display and moving object equipped with head-up display - Google Patents

Description

  The present disclosure relates to a head-up display that allows an observer to visually recognize a virtual image, and a moving object equipped with the head-up display.

  Patent Literature 1 discloses a display device that enables stereoscopic display. The display device includes a display panel that is an image forming unit that forms an image, an image forming optical system that forms an image formed by the image forming unit, and an incident side of the image forming optical system. An image forming position changing unit that changes a position of an image formed by the system. The imaging position variable unit includes a relay optical system that forms an intermediate image between the image forming unit and the imaging optical system, and is sequentially switched by the image forming unit by changing the position of the intermediate image by the relay optical system. The position of each of the plurality of images is changed.

JP 2008-180759 A

  The present disclosure provides a small-sized head-up display capable of presenting a virtual image on a large screen, and a moving object equipped with the head-up display.

  The head-up display of the present disclosure is a head-up display that allows a viewer to visually recognize a virtual image in a viewer's viewpoint area. The head-up display includes a display device and a first optical system. The display device has a display surface, and displays an image on the display surface. The first optical system has a concave mirror, and a lens having a light condensing function disposed between the concave mirror and the display surface. The first optical system forms an intermediate image by enlarging an image of the light beam emitted from the display surface via the lens and the concave mirror.

  A moving object according to an embodiment of the present disclosure includes the above-described head-up display and a windshield.

  The head-up display according to the present disclosure can present a large-screen virtual image while being small.

FIG. 1 is a schematic diagram illustrating a cross section of a moving body equipped with the head-up display of the present disclosure. FIG. 2 is an optical sectional view showing a configuration of the head-up display according to the first embodiment. FIG. 3 is an optical cross-sectional view showing a configuration of the screen and the first optical system according to the first embodiment. FIG. 4 is a diagram illustrating the relationship between the emission angle of light rays emitted from the display surface of the screen and the virtual image I. FIG. 5 is a diagram illustrating the relationship between the emission angle of light rays emitted from the display surface of the screen and the virtual image I. FIG. 6 is an optical sectional view showing a configuration of the head-up display according to the second embodiment. FIG. 7 is a diagram illustrating eccentricity data of each surface in the optical system of Example 1 (corresponding to Embodiment 1). FIG. 8 is a diagram showing the radius of curvature of each surface in the optical system of Example 1 (corresponding to Embodiment 1). FIG. 9 is a diagram illustrating data of the shape of a free-form surface in the optical system of Example 1 (corresponding to Embodiment 1). FIG. 10 is a diagram illustrating data of the shape of a free-form surface in the optical system of Example 1 (corresponding to Embodiment 1). FIG. 11 is a diagram illustrating data of the shape of a free-form surface in the optical system of Example 1 (corresponding to Embodiment 1). FIG. 12 is a diagram showing eccentricity data of each surface in the optical system of Example 2 (corresponding to Embodiment 2). FIG. 13 is a diagram illustrating the radius of curvature of each surface in the optical system of Example 2 (corresponding to Embodiment 2). FIG. 14 is a diagram illustrating data of the shape of a free-form surface in the optical system of Example 2 (corresponding to Embodiment 2). FIG. 15 is a diagram illustrating data of the shape of a free-form surface in the optical system of Example 2 (corresponding to Embodiment 2). FIG. 16 is a diagram illustrating data of the shape of a free-form surface in the optical system of Example 2 (corresponding to Embodiment 2). FIG. 17 is a diagram illustrating data of the head-up display according to the first and second embodiments.

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, an unnecessary detailed description may be omitted. For example, a detailed description of a well-known item or a redundant description of substantially the same configuration may be omitted. This is to prevent the following description from being unnecessarily redundant and to facilitate understanding by those skilled in the art.

  The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the claimed subject matter.

(Embodiment 1)
The first embodiment will be described below with reference to FIGS.

[1-1. Constitution]
[1-1-1. Overall configuration of head-up display and moving object]
FIG. 1 is a schematic diagram illustrating a cross section of a vehicle 200 as a moving object equipped with the head-up display 100 of the present disclosure. The vehicle 200 includes a dashboard 210 and a windshield 220. The dashboard 210 is arranged below the windshield 220. An observer D is on the vehicle 200.

  As shown in FIG. 1, the head-up display 100 is arranged inside the dashboard 210. The head-up display 100 reflects light rays from an image displayed by the display device (110 in FIG. 2) through the windshield 220, guides the light rays to the viewpoint area 300 of the observer D, and presents the virtual image I. . That is, the observer D visually recognizes the image projected by the head-up display 100 on the windshield 220 as the virtual image I. Note that the viewpoint area 300 may be called an eye box. The viewpoint area 300 is an area where the viewpoint of the observer D is located so that the observer D can visually recognize the virtual image I without missing. In the present disclosure, the viewpoint of the observer D is located at the center of the viewpoint region 300 unless otherwise specified.

[1-1-2. Configuration of head-up display]
FIG. 2 is an optical cross-sectional view illustrating a configuration of the head-up display 100 according to the first embodiment. As shown in FIG. 2, the head-up display 100 includes a display device 110, a first optical system 120, and a second optical system 130.

  The display device 110 includes a screen 111, a driving unit 112, a scanning laser 113, and a control unit.

  The screen 111 has a display surface 111a. Various display image information is displayed on the display surface 111a. Examples of the display image information include a road progress guidance display, a distance to a vehicle in front, a remaining battery level of the vehicle, and a current vehicle speed. The material of the display surface is an optical material having a diffusion characteristic.

  The scanning laser 113 is a light source of the display device 110. The scanning laser 113 is disposed behind the screen 111. The scanning laser 113 scans the display surface 111a of the screen 111 to form a display image on the display surface 111a. As a light source of the display device 110, a projector that projects an image on the screen 111 may be used instead of the scanning laser 113.

  The drive unit 112 drives the screen 111. Here, among the light beams emitted from the screen 111, the light beam that reaches the center of the viewpoint area 300 is defined as a principal light beam L. Further, among the light beams emitted from the screen 111, the light beam that passes through the center of the virtual image I and reaches the center of the viewpoint area 300 is defined as a reference principal ray Lc. The drive unit 112 moves the screen 111 along the reference principal ray Lc. By moving the screen 111 along the reference principal ray Lc, the distance from the observer D to the virtual image I can be adjusted. For example, by moving the screen 111 in a direction away from the first optical system 120, the virtual image I can be presented away from the observer D.

  Further, the drive unit 112 moves the screen 111 according to the scanning position of the scanning laser 113. Thus, the virtual image I can be drawn on an arbitrary plane regardless of the emission angle of the reference principal ray Lc of the screen 111. For example, by synchronizing the drawing cycle of the scanning laser 113 with the swing cycle of the screen 111, the virtual image I can be drawn on a plane inclined with respect to the observer D. This makes it possible to realize a technology called Augmented Reality: AR. In other words, for example, a virtual image I having a perspective suitable for the scenery can be superimposed and described on the actual scenery. Further, by moving the screen 111 back and forth in the direction of the reference principal ray Lc at several tens of Hz, the virtual image I can be displayed three-dimensionally.

  The driving unit 112 may be configured to not only move the screen 111 in the optical axis direction but also rotate or tilt the screen 111.

  The first optical system 120 forms an intermediate image M in which a light beam emitted from an image on the screen 111 is imaged to enlarge the image. The first optical system 120 includes a lens 123, a first mirror 121, and a second mirror 122. On the optical path from the screen 111 to the intermediate image M, a lens 123, a first mirror 121, and a second mirror 122 are arranged in this order.

  The lens 123 is, for example, a biconvex lens or a plano-convex lens. In addition, the lens 123 may be a lens having a meniscus shape having positive power. The lens 123 only needs to have a shape having a light condensing function. Thus, it is possible to perform a light condensing action for intermediately forming an image on the screen 111, and it is possible to reduce the size of the first mirror 121. In addition, by making the shape of the lens 123 a shape having a condensing function, the power of the first mirror 121 can be reduced, and the sensitivity to an installation error in manufacturing can be reduced. As shown in FIG. 3, the lens 123 has an incident surface 123a on which the light beam from the screen 111 is incident and an emission surface 123b from which the light beam is emitted.

  The first mirror 121 is a concave mirror. The shape of the reflection surface of the first mirror 121 is a concave shape. By making the shape of the first mirror 121 concave, the image on the screen 111 can be condensed so as to form an intermediate image. The power of the first mirror 121 is larger than the power of the lens 123. Thereby, the power of the lens 123 can be suppressed, and the chromatic aberration generated in the lens 123 can be suppressed.

  The second mirror 122 is a convex mirror. The shape of the reflection surface of the second mirror 122 is a convex shape. By setting the shape of the reflection surface of the second mirror 122 to a convex shape, asymmetric eccentric distortion generated in the first mirror 121 can be satisfactorily corrected.

  The intermediate image M is formed to be larger than the image displayed on the screen 111. This makes it possible to reduce the positive power of the fourth mirror 132 of the second optical system 130, which will be described later, while reducing the size of the screen 111. As a result, the distortion of the virtual image I projected on the windshield 220 can be suppressed. Specifically, it is desirable to set the power of the first optical system 120 so as to satisfy the following condition (1).

1.4 <β <4.0 (1)
here,
β: lateral magnification of the first optical system 120.

  The intermediate image M does not need to be formed as a good point at the position where the intermediate image M is formed, and may have spherical aberration, coma aberration, field curvature, and astigmatism.

  Further, the components of the first optical system 120 are not limited to the three elements of the first mirror 121, the second mirror 122, and the lens 123, but are only the two elements of the first mirror 121 and the lens 123. , Or four or more elements.

  The second optical system 130 projects the intermediate image M on the windshield 220. The second optical system 130 includes a third mirror 131 and a fourth mirror 132. The third mirror 131 is a convex mirror. The shape of the reflecting surface of the third mirror 131 is a convex shape. The fourth mirror 132 is a concave mirror. The shape of the reflection surface of the fourth mirror 132 is a concave shape. By setting the shape of the third mirror 131 to a convex shape, asymmetric eccentric distortion generated in the fourth mirror 132 can be favorably corrected. Further, by making the shape of the fourth mirror 132 concave, the observer D can visually recognize the virtual image I that is larger than the intermediate image M.

  In the present embodiment, the shapes of the first mirror 121, the second mirror 122, the lens 123, the third mirror 131, and the fourth mirror 132 are all free-form surfaces. This is because the distortion of the virtual image caused by the reflection is corrected so that a good virtual image I can be seen in the entire viewpoint area 300. However, for example, one of the first mirror 121 and the second mirror 122 may be a free-form surface mirror, and the other may be a plane mirror. In this case, a free-form mirror having a condensing function is used as a concave mirror. Similarly, one of the third mirror 131 and the fourth mirror 132 may be a free-form surface mirror, and the other may be a plane mirror.

[1-1-3. Light path]
The optical path of the light beam emitted from the screen 111 and reaching the viewpoint area 300 of the observer D will be described below.

  Light rays emitted from the image displayed on the screen 111 enter the first mirror 121 via the lens 123, are reflected by the first mirror 121, and then are reflected by the second mirror 122 to form the intermediate image M. Form. The intermediate image M is formed in the air. The intermediate image M formed by the first optical system 120 is reflected by the third mirror 131, then reflected by the fourth mirror 132, and projected on the windshield 220. The intermediate image M projected on the windshield 220 reaches the viewpoint area 300 of the observer D, and is visually recognized as a virtual image I by the observer D.

  Here, the reference principal ray Lc exits from the center of the image drawn on the screen 111 and enters the first mirror 121 via the lens 123. Then, the reference principal ray Lc is reflected by the first mirror 121, and reaches the center of the intermediate image M via the second mirror. Further, the reference principal ray Lc is reflected by the third mirror 131 and enters the fourth mirror 132. Then, the reference principal ray Lc is reflected by the fourth mirror 132 and is projected on the windshield 220. Then, the reference chief ray Lc passes through the center of the virtual image I projected on the windshield 220 and reaches the center of the viewpoint area 300 of the observer D.

  The principal ray L exits from an arbitrary point of the image drawn on the screen 111 and enters the first mirror 121 via the lens 123. Then, the principal ray L is reflected by the first mirror 121 and reaches a point corresponding to the image drawn on the screen 111 of the intermediate image M via the second mirror. Further, the principal ray L is reflected by the third mirror 131 and enters the fourth mirror 132. Then, the principal ray L is reflected by the fourth mirror and is projected on the windshield 220. Then, the principal ray L passes through an arbitrary center of the virtual image I projected on the windshield 220 and reaches the center of the viewpoint area 300 of the observer D.

[1-1-4. Arrangement configuration]
Hereinafter, the arrangement of the main components of the display device 110, the first optical system 120, and the second optical system 130 will be described. In describing this arrangement, the positive direction (arrow direction) of the Z axis shown in FIGS. 1 to 3 is defined as the upward direction, the negative direction is defined as the downward direction, and the positive direction of the X axis (the arrow direction). Is described as a left direction and a negative direction as a right direction.

(Overall configuration)
As shown in FIG. 2, in head-up display 100 according to Embodiment 1, the position of display device 110 is arranged below first optical system 120 and second optical system 130.

  The optical path length (interval) of the reference principal ray Lc from the first mirror 121 to the second mirror 122 is shorter than the optical path length (interval) of the reference principal ray Lc from the third mirror 131 to the fourth mirror 132. By doing so, the size of the head-up display 100 can be reduced.

  The optical path length (interval) of the reference principal ray Lc from the screen 111 to the first mirror 121 is shorter than the optical path length (interval) of the reference principal ray Lc from the first mirror 121 to the intermediate image M. By doing so, the size of the first mirror 121 can be reduced, and the size of the head-up display 100 can also be reduced.

  In addition, the upper end of the reflection surface of the first mirror 121 is located above the lower end of the reflection surface of the fourth mirror 132. 2 indicates the position of the upper end of the first mirror 121. The dotted line H is located above the lower end of the fourth mirror 132. By arranging the first mirror 121 and the fourth mirror 132 in this manner, the size of the head-up display 100 can be reduced.

  Further, in the present embodiment, the power of the lens 123 is adjusted, and the exit pupil position of the first optical system 120, that is, the center portion of the first mirror 121 is kept as far away from the screen 111 as possible. This makes it possible to reduce the difference in the emission angle between the principal ray L immediately after exiting from the screen 111 and the reference principal ray Lc from the center to the periphery of the display image area of the screen 111. That is, the principal ray L immediately after the emission from the screen 111 and the reference principal ray Lc can be made substantially parallel. This effect will be described together with the condition (3) described later.

(Screen layout)
As shown in FIG. 3, in the first embodiment, the display surface 111 a of the screen 111 of the display device 110 is directed toward the lens 123. At this time, the reference principal ray Lc emitted from the screen 111 is preferably inclined with respect to the display surface 111a of the screen 111. Accordingly, when external light that has entered the housing is reflected on the screen 111, the reflected light can be prevented from being mixed with light rays of an image displayed on the screen 111 to become stray light.

(Lens arrangement)
The lens 123 is disposed closer to the first mirror 121 than the display device 110 is. Light emitted from the screen 111 of the display device 110 enters the incident surface 123a of the lens 123, and exits from the exit surface 123b of the lens 123 toward the first mirror 121.

  It is desirable that the lens 123 be inclined with respect to the reference principal ray Lc. Specifically, as shown in FIG. 3, when a virtual tangent plane at a point where the reference principal ray Lc passes on the emission surface 123b is set as a tangent plane (virtual tangent plane) VP, the tangent plane VP is set to the reference principal plane VP. It is preferable that the lens 123 is inclined so as to intersect the light ray Lc without being orthogonal. More specifically, it is desirable that the tangent plane VP be inclined so as to face downward from the reference principal ray Lc. Thus, even when external light enters the housing and is reflected on the entrance surface 123a or the exit surface 123b of the lens 123, the reflected light can be suppressed from entering the first mirror 121. That is, it is possible to prevent the external light from being mixed into the light beam that is emitted from the screen 111 and forms the intermediate image M, and becomes stray light. In addition, by arranging the lens 123 so that the tangent plane VP is inclined below the first mirror 121, even when external light enters the lens 123, a reflection mirror other than the first mirror, that is, a second mirror 122, the third mirror 131, and the fourth mirror 132 are hardly incident. Therefore, stray light can be reduced. In addition, at least one of the entrance surface 123a and the exit surface 123b of the lens 123 has a free-form surface shape. This makes it easy to make the principal ray L immediately after exiting from the screen 111 and the reference principal ray Lc parallel.

(Arrangement configuration of first mirror)
The first mirror 121 is arranged above the display device 110 and on the viewer D side. That is, the first mirror 121 is disposed diagonally to the upper right of the display device 110, as described using the vertical and horizontal directions in the drawing of FIG. The first mirror 121 decenters its reflection surface such that an image displayed on the display device 110 enters through the lens 123 and the image is reflected by the first mirror 121 and reflected on the second mirror 122. It is arranged.

(Arrangement configuration of second mirror)
The second mirror 122 is disposed below the first mirror 121 and on the virtual image I side. That is, the second mirror 122 is disposed diagonally to the lower left of the first mirror 121 in the vertical and horizontal directions of FIG. The second mirror 122 is arranged with its reflection surface decentered so that the light reflected by the first mirror 121 enters and is reflected by the third mirror 131.

  Here, in the first optical system 120, it is desirable to dispose the screen 111, the first mirror 121, and the lens 123 so as to satisfy the following condition (2).

2 <A / B <200 (2)
here,
A: the optical path length of the reference principal ray Lc from the exit surface 123b to the first mirror 121 B: the optical path length of the reference principal ray Lc from the display surface 111a to the entrance surface 123a of the lens 123

  Condition (2) is a condition for defining the positions of the screen 111, the first mirror 121, and the lens 123. By satisfying this condition, the size of the first optical system 120 can be reduced. When the value exceeds the upper limit of the condition (2), the first mirror 121 is too far from the screen 111 and the size of the first mirror 121 is increased, so that it is difficult to provide a small head-up display 100. In addition, when the value goes below the lower limit of the condition (2), the lens 123 is too far from the screen 111, and the lens 123 becomes large, which makes it difficult to provide a small head-up display 100.

  In addition, when the condition (2-1) is satisfied, the above effects can be further achieved.

4 <A / B <75 (2-1)
Further, when the condition (2-2) is further satisfied, the above effect can be further achieved.

5 <A / B <50 (2-2)
Further, on the optical path from the display surface 111a of the screen 111 to the incident surface 123a of the lens 123, the angle formed by the principal ray L and the reference principal ray Lc preferably satisfies the following condition (3). .

θmax <5 (3)
here,
θmax: the maximum value of the angle [deg] formed by the principal ray L and the reference principal ray Lc on the optical path from the display surface 111a of the screen 111 to the incident surface 123a.

  The condition (3) is a condition for defining a light beam emitted from the screen 111 when the observer D observes the virtual image I from the center of the viewpoint area 300. Condition (3) indicates that the principal ray L and the reference principal ray Lc are substantially parallel immediately after exiting from the display surface 111a of the screen 111. When the principal ray L and the reference principal ray Lc satisfy the condition (3), the viewing angle at which the observer D views the virtual image I is constant even when the screen 111 moves along the reference principal ray Lc. Become. Therefore, the observer D can visually recognize the favorable virtual image I with little change in shape. In addition, for example, a virtual image I with a perspective that matches the actual scenery can be presented.

  In addition, when the condition (3-1) is satisfied, the above effects can be further achieved.

θmax <2 (3-1)
Further, when the condition (3-2) is satisfied, the above effect can be further achieved.

θmax <1 (3-2)
FIGS. 4 and 5 are diagrams showing the relationship between the emission angle of the light beam emitted from the display surface 111 a of the screen 111 and the virtual image I. FIG. 4 shows the lens 123 configured such that the maximum value of the angle between the principal ray L and the reference principal ray Lc satisfies the condition (3), and the principal ray L is substantially parallel to the reference principal ray Lc. FIG. 7 is a diagram showing a relationship between a position of a screen 111 and a virtual image I at the time.

  As shown in FIG. 4, by making the principal ray L immediately after exiting from the screen 111 parallel to the reference principal ray Lc, when the position of the screen 111 is moved in parallel to the reference principal ray Lc by the driving unit 112, The viewing angle at which the observer D views the virtual image I is constant. Therefore, it is possible to suppress the shape change of the virtual image I visually recognized by the observer D. In addition, for example, a virtual image I with a perspective that matches the actual scenery can be presented.

  On the other hand, FIG. 5 shows a case where the condition (3) is not satisfied and the principal ray L is not parallel to the reference principal ray Lc. When the drive unit 112 moves the position of the screen 111 along the reference principal ray Lc, the viewing angle at which the observer D views the virtual image I changes. Therefore, the shape of the virtual image I visually recognized by the observer D fluctuates. As a result, it is difficult to visually recognize a good virtual image I. In addition, it is difficult to present a virtual image I with a perspective that matches the actual scene.

  As described above, among the light rays that reach the center of the viewpoint area 300, it is preferable that the principal ray L emitted from the screen 111 is parallel to the reference principal ray Lc.

(Configuration of Third Mirror)
The third mirror 131 is disposed above the first mirror 121. The third mirror 131 is arranged with its reflection surface decentered so that the light beam reflected by the second mirror 122 is reflected on the fourth mirror 132.

(Arrangement configuration of fourth mirror)
The fourth mirror 132 is disposed closer to the virtual image I than the third mirror 131 is. That is, in the up, down, left, and right directions in FIG. 2, the fourth mirror 132 is disposed diagonally upper left of the third mirror. The fourth mirror 132 is arranged with its reflection surface decentered so that the reflected light from the third mirror 131 is reflected on the windshield 220.

[1-2. Effects]
As described above, in the present embodiment, the head-up display 100 includes the display device 110, the first optical system 120, and the second optical system 130. The intermediate image M formed by the first optical system 120 is larger than the display image displayed on the screen 111 by the display device 110. Thereby, the first optical system 120 and the second optical system 130 can be reduced in size, and the entire display device 110 can be reduced in size. Further, since the first optical system 120 includes the lens 123, the first mirror 121, and the second mirror 122, the screen 111 can be downsized while favorably correcting screen distortion. Further, since the first optical system 120 has the lens 123, the size of the first mirror 121 can be reduced. By providing the first optical system 120, the positive power of the second optical system 130 can be suppressed.

  In addition, since the screen 111 can be made smaller than the virtual image I, when adjusting the distance between the virtual image I and the observer D, the amount of movement of the screen 111 can be reduced, and the drive unit 112 can be made smaller.

In the present embodiment, the moving amount of the intermediate image M is larger than the moving amount of the screen 111. This is because the lateral magnification β of the first optical system 120 is larger than 1. At this time, with respect to the amount of movement of the screen 111, the amount of movement of the intermediate image M becomes beta ² times. In the first embodiment, since the screen 111 is moved instead of the intermediate image M, the moving amount can be reduced, and the driving unit 112 can be downsized.

  Further, in the present embodiment, the power of the lens 123 is designed so that the principal ray L immediately after exiting from the display surface 111a and the reference principal ray Lc can be made parallel. Thus, when the display surface 111a is moved along the reference principal ray Lc, the viewing angle of the observer D who views the virtual image I can be constant. Therefore, it is possible to present a virtual image I with little change in shape. In addition, a virtual image I having a sense of perspective combined with an actual scene can be provided.

(Embodiment 2)
Hereinafter, Embodiment 2 will be described with reference to FIG. In this embodiment, the arrangement position of the first optical system 120 is different from that of the first embodiment, and the other configuration is the same as that of the first embodiment. Therefore, the following description focuses on the different points, and the description of the same components is omitted.

  The first mirror 121 of the head-up display 100 according to the second embodiment is arranged at a different place from the first embodiment. The first mirror 121 of the second embodiment is disposed above the display device 110 in the vertical direction in FIG. 6 (positive direction of the Z axis) and on the virtual image I side (positive direction of the X axis). .

  In head-up display 100 according to the second embodiment, display surface 111a of screen 111 faces in the traveling direction of the vehicle. By doing so, the scanning laser 113 can be arranged on the observer D side, and interference with structures ahead of the vehicle can be avoided.

(Numerical example)
Hereinafter, numerical examples corresponding to the first and second embodiments will be described with reference to FIGS. 7 to 17.

  Hereinafter, specific examples of the display device according to the present technology will be described. In the examples described below, the unit of length in the table is (mm), and the unit of angle is (degree). The free-form surface is defined by the following equation (1).

Here, z is the sag amount at the position (x, y) from the axis defining the surface, r is the radius of curvature at the origin of the axis defining the surface, c is the curvature at the origin of the axis defining the surface, and k is conic. constant, Cj is the coefficient of the monomial ^x m ^{y n.}

  In each embodiment, the reference coordinate origin is the center of the image (display surface 111a) displayed on the display device 110, and the horizontal direction of the display surface 111a is X in the tables of FIGS. The axis and the vertical direction are shown as the Y axis, and the direction perpendicular to the display surface 111a is shown as the Z axis.

  Further, the toroidal surface is formed by a trajectory obtained by rotating a contour on the xz plane defined by the following equation 2 on an axis translated in parallel with the x-axis to a position away from the origin by the radius of curvature ry. .

  In the eccentricity data, ADE is the amount of rotation of the mirror or lens from the Z axis to the Y axis around the X axis, and BDE is the amount of rotation of the mirror or lens from the X axis to the Z axis around the Y axis. , CDE means the amount of rotation about the Z axis from the X axis direction to the Y axis direction.

[Example 1]
7 to 11 show data of the optical system of the head-up display 100 according to the first embodiment (Embodiment 1). Example 1 is an example in which the configuration of Embodiment 1 is adopted. FIGS. 7 to 11 show specific data of the optical system. FIG. 7 shows eccentricity data of each surface of each optical element of the head-up display 100. The surface number 1 is the number of the display surface of the screen 111. The surface number 2 is the number of the incident surface 123a of the lens 123, and the surface number 3 is the number of the emission surface 123b of the lens 123. The surface number 4 is the number of the reflection surface of the first mirror 121. The surface number 5 is the number of the reflection surface of the second mirror 122. The surface number 6 is the number of the reflection surface of the third mirror 131. The surface number 7 is the number of the reflection surface of the fourth mirror 132. The surface number 8 is the number of the projection surface of the windshield 220. The surface number 9 is the number of the center of the viewpoint area 300 of the observer D. FIG. 8 shows the radius of curvature of each surface. 9 to 11 show polynomial coefficients representing the shape of the free-form surface of each surface.

[Example 2]
12 to 16 show data of the optical system of the head-up display 100 according to the second embodiment (second embodiment). Numerical example 2 is an example in which the configuration of the second embodiment is adopted. Specific data of the optical system are shown in FIGS. FIG. 12 shows eccentricity data of each surface of each optical element of the head-up display 100. How to assign each surface number is the same as in Numerical Example 1. FIG. 13 shows the radius of curvature of each surface. 14 to 16 show polynomial coefficients representing the shape of the free-form surface of each surface.

  FIG. 17 is data showing the size of the virtual image I of Example 1 and Example 2 and the distance from the observer D to the virtual image I. X and Y shown in FIG. 17 are directions that define the surface of the windshield 220. The X direction is a horizontal (horizontal) direction, and the Y direction is a vertical direction.

  Table 1 below shows corresponding values of the conditional expressions (1) to (3) from the first embodiment to the second embodiment.

(Other embodiments)
As described above, Embodiments 1 and 2 have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, and the like are made. Further, it is also possible to form a new embodiment by combining the components described in the first and second embodiments.

  In the first and second embodiments, the display device 110 has been described using a projector or a scanning laser that projects an image on the screen 111. However, it is also possible to use a liquid crystal display (Liquid Crystal Display), an organic light emitting diode (electroluminescence), a plasma display, or the like as the screen 111 without using a projector or a scanning laser.

  In the first and second embodiments, the second optical system 130 includes two mirrors, a third mirror 131 and a fourth mirror 132, and a refracting optic such as a lens element having the same function. It may be constituted by an element or may be constituted only by the fourth mirror 132.

  In Embodiments 1 and 2, a mirror having a rotationally asymmetric shape is used as third mirror 131, but has a so-called saddle-shaped surface shape in which the sign of curvature differs between the X direction and the Y direction. A mirror may be used.

  In Embodiments 1 and 2, a mirror having a rotationally asymmetric shape is used as second mirror 122, but has a so-called saddle-shaped surface shape in which the sign of curvature differs between the X direction and the Y direction. An n mirror may be used.

  In the first and second embodiments, a lens having a rotationally asymmetric free-form surface is used as the lens 123. However, the present invention is not limited to this. A spherical shape, an aspherical shape, a cylindrical shape, a toroidal surface shape Alternatively, a lens having an anamorphic surface shape or a Fresnel shape may be used. The point is that the lens 123 may be any lens that can make the principal ray L immediately after exiting the screen 111 and the reference principal ray Lc parallel.

  In Embodiments 1 and 2, the lens 123 is described using a refraction function, but a diffraction function may be used.

  In Embodiments 1 and 2, the lens 123 is described using a shape having a light-condensing action, but it is not necessary to have a light-condensing action on the entire lens surface, and a surface shape having a diverging action on a part may be used. .

  In the first and second embodiments, the screen 111 has been described as being moved back and forth in the direction of the reference principal ray Lc. However, it is not always necessary to match the direction of the reference principal ray Lc. Just include the vector.

  It should be noted that the above-described embodiments are intended to exemplify the technology according to the present disclosure, and thus various changes, substitutions, additions, omissions, and the like can be made within the scope of the claims or the equivalents thereof.

  The present disclosure is applicable to a head-up display that projects on a reflective transmission member. Specifically, the present disclosure is applicable to a head-up display mounted on a moving object having a windshield.

REFERENCE SIGNS LIST 100 Head-up display 110 Display device 111 Screen 111a Display surface 112 Drive unit 113 Scanning laser 120 First optical system 121 First mirror 122 Second mirror 123 Lens 123a Incident surface 123b Exit surface 130 Second optical system 131 Third Mirror 132 fourth mirror 200 vehicle 210 dashboard 220 windshield 300 viewpoint area D observer L principal ray Lc reference principal ray M intermediate image VP tangent plane

Claims (11)

In a viewer's viewpoint area, a head-up display that allows the viewer to visually recognize a virtual image,
A display device having a display surface and displaying an image on the display surface,
A concave mirror, and a lens having a light condensing function disposed between the concave mirror and the display surface, and a light beam emitted from the display surface is enlarged through the lens and the concave mirror to enlarge the image. A first optical system that forms an image as an intermediate image;
Head-up display with. The lens has an entrance surface on which the light beam enters, and an exit surface on which the light beam exits,
The lens and the concave mirror are adjacent on the optical path of the light beam, and the distance from the display surface to the incident surface is smaller than the distance from the output surface to the concave mirror.
The head-up display according to claim 1. The lens has an entrance surface on which the light beam enters, and an exit surface on which the light beam exits,
The lens and the concave mirror are adjacent on the optical path of the light beam,
Of the light rays, when a light ray that passes through the center of the virtual image and reaches the center of the viewpoint area is used as a reference principal ray,
The head-up display according to claim 1, wherein the following condition (2) is satisfied:
2 <A / B <200 (2)
here,
A: the optical path length of the reference chief ray from the emission surface to the concave mirror B: the optical path length of the reference chief ray from the display surface to the incidence surface. The optical power of the concave mirror is stronger than the optical power of the lens,
The head-up display according to claim 1. The lens has an exit surface from which the light beam exits,
Of the light rays, a light ray that passes through the center of the virtual image and reaches the center of the viewpoint area is used as a reference principal ray,
At the point where the reference principal ray on the emission surface passes, when a virtual surface that is in contact with the emission surface is a virtual tangent plane,
The virtual tangent plane is inclined with respect to the reference chief ray.
The head-up display according to claim 1. The lens has an incident surface on which the light beam enters,
Of the light rays, a light ray that reaches the center of the viewpoint area is a principal ray,
Of the chief rays, when a ray that passes through the center of the virtual image and reaches the center of the viewpoint area is a reference chief ray,
The head-up display according to claim 1, wherein the following condition (3) is satisfied:
θmax <5 (3)
here,
θmax: the maximum value of the angle [deg] formed by the principal ray and the reference ray immediately after emission from the display surface. The lens has an incident surface on which the light beam enters,
Of the light rays, a light ray that reaches the center of the viewpoint area is a principal ray,
Of the chief rays, when a ray that passes through the center of the virtual image and reaches the center of the viewpoint area is a reference chief ray,
On an optical path from the display surface to the incident surface, the lens is configured such that the principal ray and the reference principal ray are parallel to each other.
The head-up display according to claim 1. The head-up display according to any one of claims 1 to 7 , wherein the intermediate image is formed in the air. A second optical system that is arranged on an optical path of the light beam from the intermediate image to the viewpoint area and projects the intermediate image;
The image projected on the second optical system is visually recognized by the observer as the virtual image in the viewpoint area.
Head-up display as claimed in any one of claims 1 to 8. The display surface is moved along said reference principal ray, head-up display as claimed in any one of claims 1 to 9. Moving body comprising a head-up display as claimed, a windshield to any one of claims 1 10.

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