JP2009115908A - Mirror optical system and headup display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact headup display for displaying virtual images excellently corrected in aberration. <P>SOLUTION: The headup display 10 includes: a mirror optical system 22 for generating display light 21 having image information and broadening and projecting it; and a front glass for displaying the virtual images by reflecting the display light 21. The mirror optical system 22 includes: a liquid crystal panel 23 generating the display light 21; a first planar mirror 26; non-rotation symmetrical aspheric shaped concave mirror 28; and the like. The headup display 10 reflects the display light 21 on the first planar mirror 26 and guides it to the concave mirror 28. When a path of a main light beam being the center of the virtual image is regarded as a reference optical axis L1, the display light 21 is reflected to the first planar mirror 26 again so that the concave mirror 28 deflects the reference optical axis L1 in a deflection angle α (degrees) satisfying 20<α<25. The display light 21 incident on the first planar mirror 26 again is broadened and projected onto the front glass. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a head-up display device in which image display light is projected onto a windshield of an automobile or an aircraft so that a virtual image can be observed through the windshield.

  For example, Patent Document 1 discloses a head-up display device in which display light of an image is reflected toward a driver who is an observer by a windshield of an automobile so that an image of an instrument such as a speedometer can be observed as a virtual image. It has been. The instrument image is enlarged and displayed as a virtual image at a position 2m or more away from the driver through the windshield, so the driver observes the displayed image with almost no change in the line-of-sight direction or diopter with the normal front vision. can do.

  As described in Patent Document 1, the optical system unit used for such an application includes an image display panel, an illumination light source, and a projection optical system. A transmissive liquid crystal display panel is frequently used as an image display panel, and a backlight light source provided behind the transmissive liquid crystal display panel serves as an illumination light source, and image display light transmitted through the liquid crystal display panel is incident on a projection optical system. A concave mirror is used in the projection optical system, and convergent reflected light from the concave mirror enters the windshield as display light, and the display light is directed to the observer by reflection of the windshield.

  In general, since it is difficult to secure a large space in the vicinity of a windshield in an automobile or the like, there is a demand for reducing the size of, for example, an image display panel or a concave mirror. On the other hand, since the observed virtual image is at a position 2 m or more away from the observer, the image size needs to be about 150 mm at the smallest. Furthermore, the position of the driver's eyes is not necessarily constant, and in order to enable observation with both eyes even if they are shifted by about 20 mm from side to side, the size of the exit pupil should be secured at least about 100 mm and display light should be used. Considering that the windshield reflecting toward the driver is positioned approximately in the middle between the driver and the display position of the virtual image, the aperture of the concave mirror needs to be about 125 mm.

When enlarging and projecting a small display image displayed on the image display panel, L = (1 + β) × f, where L is the image distance from the concave mirror to the virtual image, β is the image magnification, and f is the focal length of the concave mirror. (Imaging formula) If the image distance L is 1100 mm, the image size on the image display panel is 15 mm, and this is projected 10 times to obtain an image of 150 mm, the focal length f of the concave mirror is 100 mm. For the above-mentioned reason, when the aperture of the concave mirror is set to 125 mm, the brightness (focal length / aperture) of the concave mirror becomes very bright as 0.8, but it is desirable to suppress the aberration as much as possible.
JP 2006-11168 A

  However, since the optical unit of the conventional head-up display device reflects display light with a large deflection angle by the concave mirror, spherical aberration and astigmatism are likely to occur. For example, in the optical system described in Patent Document 1, when the reference optical axis corresponding to the principal ray passing through the center of the image is bent by the concave mirror, the angle between the optical axes before and after bending (deflection angle α) is as high as about 60 degrees. In order to reduce aberration and obtain good imaging performance, the focal length must be increased to, for example, about 300 mm. For this reason, if an image is displayed with a size that is easy to observe, the size of the image display panel and its illumination system also increase, and an increase in space, cost, and power consumption cannot be avoided.

  The present invention has been made in consideration of the above background, a mirror optical system that can display a virtual image with an image size that is easy to observe while reducing the size of the image display panel, and is advantageous in terms of suppressing aberrations, And it aims at providing a head up display device using the same.

  The mirror optical system of the present invention is a reflective surface facing an observer at a predetermined position, reflects display light from the image display panel to the observer side, and is displayed on the image display panel through the reflective surface. A mirror optical system that enlarges and displays an image as a virtual image, and reflects the display light from the image display panel when a path of a principal ray that tracks the display light that is the center of the virtual image is a reference optical axis, A first flat mirror that deflects the reference optical axis; and a surface shape of a non-rotationally symmetric aspherical surface that is arranged eccentrically with respect to the reference optical axis and reflects the display light reflected by the first flat mirror. And a concave mirror that enlarges and projects the image displayed on the image display panel by causing the display light to enter the first flat mirror again, and the first flat mirror magnifies and projects from the concave mirror. The previous image It is reflected by the reflecting surface and displaying a virtual image.

  In addition, an angle α (degree) formed by the reference optical axis of the display light incident on the concave mirror from the first flat mirror and the reference optical axis of the display light incident on the first flat mirror from the concave mirror Satisfies 15 <α <33.

  Further, the image display panel is arranged to be inclined with respect to the reference optical axis.

  In addition, a second plane mirror is provided between the image display panel and the first plane mirror to reflect and guide the display light to the first plane mirror.

  A head-up display device according to the present invention includes the above-described mirror optical system.

  According to the present invention, the first plane mirror is provided between the image display panel and the concave mirror, and the display light incident on the concave mirror and the display light reflected by the concave mirror are reflected by the first plane mirror. According to the configuration, the deflection angle of the reference optical axis by the concave mirror can be suppressed to a range of 15 to 33 degrees, and an appropriate display image size can be obtained while the entire mirror optical system is compact, and the concave mirror can be obtained. Aberration is also particularly favorably corrected by making a rotationally asymmetric aspherical shape with respect to the reference optical axis.

  As shown in FIG. 1, the head-up display device 10 has its optical system (mirror optical system 22) arranged on the dashboard 13 of the automobile 12, and the value of the speedometer and the like are placed in front of the driver (observer) 14. The image is displayed through the windshield 18 (reflection surface).

  The head-up display device 10 enlarges and projects an image to be displayed on a built-in small liquid crystal panel on the windshield 18 and reflects the image toward the driver 14. Therefore, the image displayed by the head-up display device 10 is a virtual image 19. That is, in the head-up display device 10, an image is not formed on the windshield 18 and a real image is displayed, but a virtual image 19 is displayed on the driver 14 at a position of the distance D through the windshield 18. .

  The distance D at which the virtual image 19 is displayed is sufficiently long so that the virtual image 19 can be viewed with little eye movement during driving and almost no focus adjustment of the eyes. The distance is more than 2m from the driver.

  As shown in FIG. 2, the head-up display device 10 generates display light 21 having image information to be displayed and magnifies and projects the display light 21, and the display light 21 is observed by the driver 14 and the like. It consists of a reflective surface (front glass 18) that reflects in the direction of the person. The mirror optical system 22 includes a mirror optical system 22 including a liquid crystal panel (image display panel) 23, a light source 24, a first flat mirror 26, a second flat mirror 27, a concave mirror 28, and the like.

  The liquid crystal panel 23 is a small transmissive liquid crystal panel such as 0.8 type. The liquid crystal panel 23 displays values of various instruments such as a speedometer, a tachometer, a water temperature gauge, and a fuel gauge. The image displayed on the liquid crystal panel 23 is enlarged and projected as a virtual image in front of the windshield 18 as described above.

  The path of the principal ray that is the center of the virtual image 19 to be displayed is the reference optical axis L1, and this reference optical axis L1 is reversed from the driver 14 (or virtual image 19) side to the head-up display device 10 and the mirror optical system 22 side. In other words, the display surface of the liquid crystal panel 23 is not inclined by 90 degrees with respect to the reference optical axis L1, but is inclined by a predetermined angle.

  The inclination of the liquid crystal panel 23 with respect to the reference optical axis L1 is an inclination angle γ such that the focus of the virtual image 19 is met in all the ranges within the display range. That is, the line of sight of the driver 14 who sees the upper end of the virtual image 19 is focused on the upper end of the display surface of the liquid crystal panel 23, and the line of sight of the driver 14 who sees the lower end of the virtual image 19 is also the lower end of the display surface of the liquid crystal panel 23. The liquid crystal panel 23 is disposed so as to be inclined with respect to the reference optical axis L1 by an angle γ so that the image is in focus.

  Further, the image displayed on the liquid crystal panel 23 is an image having a shape obtained by converting the shape of the image to be displayed when the liquid crystal panel 23 is directly viewed according to the above-described tilt angle γ.

  The light source 24 is made of, for example, a white LED and is disposed on the back surface of the liquid crystal panel 23. That is, the light source 24 is a so-called backlight and uniformly illuminates illumination light from behind the liquid crystal panel 23. The illumination light from the light source 24 is emitted from the liquid crystal panel 23 as display light 21 having image information displayed on the liquid crystal panel 23 when passing through the liquid crystal panel 23. In addition, although the light source 24 consists of white LED, it can be set as the light source of not only this but a desired color. For example, it may be composed of single-color LEDs such as red, green, and blue, or a combination of several of these single-color LEDs to display an image in a desired color. Furthermore, the light source 24 is not limited to an LED, and other known lamps may be used.

  The second plane mirror 27 reflects display light emitted from the liquid crystal panel 23 and guides it to a first plane mirror 26 described later. That is, the second flat mirror 27 is disposed between the liquid crystal panel 23 and the first flat mirror 26 with the reflection surface facing the display surface side of the liquid crystal panel 23 and the reflection surface side of the first flat mirror 26. Yes.

  As described above, the second flat mirror 27 is arranged between the liquid crystal panel 23 and the first flat mirror 26, which is optical with respect to the display light 21, and is a cross-section of the head-up display device 10. If it sees, you may arrange | position above the edge part of the 1st plane mirror 26 (FIG. 2). As will be described later, the first flat mirror 26 reflects the display light 21 toward the windshield 18, but the second flat mirror 27 is arranged so that the first flat mirror 26 reflects the windshield 18. It is arranged at a position that does not overlap the range of the light 21.

  The first flat mirror 26 reflects the display light 21 reflected by the second flat mirror 27 and guides it to the concave mirror 28. Further, the display light 21 is incident on the first flat mirror 26 again from the concave mirror 28. Therefore, the first flat mirror 26 is arranged and sized so as to receive both the display light 21 from the second flat mirror 27 and the display light 21 from the concave mirror 28. Further, the display light 21 incident from the concave mirror 28 is reflected by the first flat mirror 26 and guided to the windshield 18.

  The concave mirror 28 reflects the display light 21 reflected by the first plane mirror 26 toward the first plane mirror 26. The concave mirror 28 is a mirror that magnifies, reflects, and projects an image displayed on the liquid crystal panel 23, and is disposed with the concave surface, which is a reflective surface, facing the first flat mirror 26 side. Further, the surface shape of the concave mirror 28 is not only a concave surface but also a non-rotationally symmetric aspherical shape.

  The aforementioned reference optical axis L1 is folded back toward the first plane mirror 26 by the concave mirror 28. The turning angle of the reference optical axis L1, that is, the reference optical axis L1 of the display light 21 incident on the concave mirror 28 from the first flat mirror 26 and the display light 21 incident on the first flat mirror 26 from the concave mirror 28. The head-up display device 10 is configured to satisfy 15 <α <33, where α (degrees) is an angle formed by the reference optical axis L1 (hereinafter referred to as a deflection angle).

  In the range of the deflection angle α of the reference optical axis L1, the display light 21 is reflected from the first flat mirror 26 to the concave mirror 28, returns to the first flat mirror 26, and is guided to the windshield 18. This is a condition range for maintaining a unique optical path order on the head-up display device 10 and correctly displaying the virtual image 19 on the driver 14.

  That is, when the deflection angle α of the reference optical axis L1 at the concave mirror 28 is below the lower limit of the above conditional expression, the display light 21 incident on the first flat mirror 26 from the liquid crystal panel 23 (second flat mirror 27), It becomes difficult to separate from the display light 21 that enters the first flat mirror 26 from the concave mirror 28 and is enlarged and projected in the direction of the windshield 18. For example, the display light 21 reflected by the concave mirror 28 is not reflected in the direction of the windshield 18 by the first flat mirror 26 but is reflected in the direction of the second flat mirror 27 and the liquid crystal panel 23, and the virtual image 19. Cannot be displayed.

  If the deflection angle α of the reference optical axis L1 at the concave mirror 28 exceeds the upper limit of the above conditional expression, the display light 21 reflected by the concave mirror 28 may not return to the first flat mirror 26, Alternatively, a large first flat mirror or a large concave mirror that requires a long focal length for aberration correction is required, and the head-up display device 10 is increased in size.

  The concave mirror 28 is a mirror that exhibits a so-called lens effect of enlarging and projecting the display light 21 incident from the first flat mirror 26, so that the reference optical axis L <b> 1 of the concave mirror 28 is folded back. The greater the angle α, the greater the influence of the aberration of the concave mirror 28. Therefore, if the deflection angle α of the reference optical axis L1 at the concave mirror 28 is within the range of the above-described conditional expression, the aberration caused by such a concave mirror 28 is reduced even if the head-up display device 10 is made compact. It becomes the level which hardly becomes a problem.

  Thus, the range of the deflection angle α is within the range of 15 <α <33 as described above due to the restriction that the optical path order of the head-up display device 10 is maintained and a virtual image is displayed correctly and the aberration of the concave mirror is suppressed. Is preferable, and a value within a range of 15 <α <32 is more preferable. Furthermore, the value of the polarization angle α is particularly preferably in the range of 20 <α <25.

  As shown in FIG. 3, the surface shape of the concave mirror 28 is a non-rotationally symmetric aspherical shape, a so-called free-form surface 31. The optical axis L2 of the free-form surface 31 is, for example, outside the concave mirror 28, and the concave mirror 28 does not have rotational symmetry about the reference optical axis L1. That is, the concave mirror 28 is used in an arrangement in which the free curved surface 31 is decentered. Since the concave mirror 28 has such a non-rotationally symmetric aspherical shape, the concave mirror 28 magnifies and projects the display light 21 and at the same time, corrects aberrations generated by the concave mirror 28 in the entire virtual image 19 to be displayed.

  The surface shape of the concave mirror 28 is a complete free-form surface having no symmetry, but it is not necessarily a complete free-form surface. Depending on the shape of the reflection surface for enlarging and projecting the display light, the concave mirror 28 is line-symmetric. There may be symmetry such as sex. That is, the windshield 18 for enlarging and projecting the display light 21 is tilted forward and backward with respect to the driver 14 and has an asymmetric shape on the left and right with respect to the front of the driver 14. The concave mirror 28 also has a completely free-form surface having no symmetry. However, for example, when displaying a virtual image by enlarging and projecting display light on a plane symmetrical to the left and right for an observer such as the driver 14, the surface shape of the concave mirror is set to display a normal-shaped virtual image. It is preferable that the cylindrical shape is symmetrical with respect to the reference optical axis.

  As a specific example of the head-up display device configured as described above, the most basic example in which the display light from the liquid crystal panel is directly reflected by the first plane mirror without depending on the second plane mirror is as follows. Are shown as examples.

[Example 1]
As shown in FIG. 4, the mirror optical system 22a of the head-up display device 10a includes a first flat mirror 26a, a concave mirror 28a, a liquid crystal panel 23, and the like. The head-up display device 10a is configured to display a virtual image by projecting and reflecting display light on a windshield of an automobile. Each part of the head-up display device 10a is arranged to display a virtual image at a position over the windshield 2m ahead of the driver. Further, the size of the virtual image to be displayed (width h (mm), height v (mm)) is h × so that the size of the virtual image displayed by the head-up display device 10a is sufficiently large for the driver to see. The head-up display device 10a was configured so that v = 150 × 50. At this time, the observation range in which the driver (observer) displays the virtual image displayed in both eyes, that is, the size of the entrance pupil, is 100 mm wide × 40 mm high.

  The effective size of the first plane mirror 26a involved in the display of the virtual image is that the length A in the vertical direction (the vertical direction of the head-up display device 10a as viewed from the driver) is 76 mm, and the horizontal direction (as viewed from the driver). The length in the horizontal direction of the head-up display device 10a is 122 mm. Similarly, the effective size that the concave mirror 28a is involved in the display of the virtual image is 46 mm in the vertical direction B and 122 mm in the horizontal direction.

  In order to show the detailed arrangement and the like of each part of the head-up display device 10a, the point where the reference optical axis L1 is reflected by the first plane mirror 26a is taken as the origin O of the coordinate system, and the extending direction of the reference optical axis L1 is A positive z-axis is defined. Furthermore, the x axis is defined in the direction perpendicular to the z axis and on the first plane mirror 26, and the y axis is defined in the direction perpendicular to the x axis and the z axis as the direction in which the concave mirror 28a is disposed. . Note that the positive direction of the x-axis is determined so that the coordinate system is a left-handed system.

  Table 1 shows specific coordinates of the first plane mirror 26a, the concave mirror 28a, and the liquid crystal panel 23 when the coordinate system is determined in this way. The coordinate scales shown in Table 1 are all mm. At the same time, the lower part of Table 1 also shows various conditions of the head-up display device 10a.

  As shown in Table 1, the first plane mirror 26a is inclined by 40.0 degrees from the xz plane with the x axis direction as the rotation axis so that the display light to be magnified and projected is appropriately deflected in the direction of the windshield. In addition to the arrangement, the distance from the driver to the origin O along the reference optical axis was 943 mm.

  Further, the liquid crystal panel 23 has coordinates (x, y, z) = (0.0, −36.79, −54.61) of the intersection (center of the display surface) between the display surface and the reference optical axis L1. Arranged to be. Further, the angle formed between the normal of the display surface and the z axis is 10.61 degrees, and the angle formed between the normal of the display surface and the reference optical axis L1 (inclination angle of the liquid crystal panel 23) γ is The liquid crystal panel 23 was rotated and arranged around the x-axis direction so as to be 11.4 degrees. Further, the display surface of the liquid crystal panel 23 has a size of width h (mm) × height v (mm) = 15 × 5.

  The concave mirror 28a is arranged so that the position of the optical axis L2 is (x, y, z) = (0.0, 26.37, −76.43), and the concave mirror 28a is positioned between the optical axis L2 and the y axis. The x-axis direction was rotated and arranged so that the angle formed was 71.78 degrees. The distance from the intersection with the reference optical axis L1 on the concave mirror 28a to the virtual image, that is, the optical path length L from the virtual image to the concave mirror 28a is 1020 mm. The surface shape of the concave mirror 28a is expressed by the following formula 1. Here, CX, CY, KAX, KAY, A4, K2, A6, and K3 are non-rotationally symmetric aspherical coefficients, and specific values thereof are shown in Table 2.

  In the head-up display device 10a configured as described above, the deflection angle α of the reference optical axis L1 in the concave mirror 28a is 22 degrees (Table 1), which is a value within the range of 15 <α <33, particularly 20 < The value falls within the range of α <25. Further, the projection magnification β (size of the virtual image to be displayed / image size on the liquid crystal panel) of the head-up display device 10a is 10 times, and the focal length f of the concave mirror 28a is 92.73 mm.

  Further, an XY coordinate system is defined in which the center (intersection of the display surface and the reference optical axis) of the liquid crystal panel 23 is the origin and the horizontal direction is the X axis, and the image coordinates (0.0, 2.. 5), (0.0, 0.0), (0.0, -2.5), (7.5, 2.5), (7.5, 0.0), (7.5,- The spot diagram of each point of 2.5) is shown in FIGS. Note that the scale of image coordinates is mm, and each spot diagram is indicated by a scale having a reference length (upper right of FIG. 5) of 200 μm.

[Example 2]
As shown in FIG. 6, the mirror optical system 22b of the head-up display device 10b includes a first flat mirror 26b, a concave mirror 28b, a liquid crystal panel 23, and the like. The head-up display device 10b is configured to display a virtual image through the windshield of the automobile as in the first embodiment, and displays a virtual image at a position through the windshield 2m ahead of the driver. indicate. Further, the size of the virtual image displayed by the head-up display device 10b is width h × height v = 150 mm × 50 mm, and the size of the entrance pupil is 100 mm × 40 mm.

  The effective size of the first flat mirror 26b involved in the display of the virtual image is that the length A in the vertical direction (the vertical direction of the head-up display device 10b as viewed from the driver) is 70 mm, and the horizontal direction (as viewed from the driver). The length in the horizontal direction of the head-up display device 10a is 122 mm. Similarly, the effective size that the concave mirror 28b is involved in the display of the virtual image is 46 mm in the vertical direction B and 122 mm in the horizontal direction.

  Similarly to the first embodiment, an xyz coordinate system having an origin at the intersection of the reference optical axis and the first plane mirror 26b is defined, and each of the first plane mirror 26b, the concave mirror 28b, and the liquid crystal panel 23 is specifically described. The coordinates are shown in Table 3. At the same time, the lower part of Table 3 also shows various conditions of the head-up display device 10b.

  As shown in Table 3, the first plane mirror 26b is disposed with an inclination of 40.68 degrees from the xz plane with the x-axis direction as the rotation axis, and the distance from the driver to the coordinate system origin O is 943 mm. Arranged.

  Further, the liquid crystal panel 23 has coordinates (x, y, z) = (0.00, −30.32, −57.62) of the intersection (the center of the display surface) between the display surface and the reference optical axis L1. Arranged to be. Furthermore, the angle (inclination angle of the liquid crystal panel 23) γ between the normal of the display surface and the reference optical axis L1 is such that the angle between the normal of the display surface and the z-axis is 7.77 degrees. The liquid crystal panel 23 was rotated and arranged around the x-axis direction as 10.2 degrees. The surface of the liquid crystal panel 23 has a size of width h × height v = 15 mm × 5 mm.

  The concave mirror 28b is arranged so that the position of the optical axis L2 is (x, y, z) = (0.00, 30.84, −55.18), and the optical axis L2 and the y axis are The x-axis direction was rotated and arranged so that the nucleus formed was 77.00 degrees. The distance from the intersection with the reference optical axis L1 on the concave mirror 28b to the virtual image, that is, the optical path length L from the virtual image to the concave mirror 28a is 1020 mm. The surface shape of the concave mirror 28b is expressed by the above-described equation 1 as in the first embodiment, and specific values of the non-rotationally symmetric aspheric coefficients CX, CY, KAX, KAY, A4, K2, A6, K3. Is shown in Table 4.

  Further, as in the first embodiment, an XY coordinate system is defined in which the center of the liquid crystal panel 23 (intersection of the display surface and the reference optical axis) is the origin and the horizontal direction is the X axis. Image coordinates (0.0, 2.5), (0.0, 0.0), (0.0, -2.5), (7.5, 2.5), (7.5, 0. The spot diagrams of the points 0) and (7.5, −2.5) are shown in FIGS. Note that the scale of the image coordinates is mm, and each spot diagram is indicated by a scale having a reference length (upper right of FIG. 7) of 200 μm.

  In the head-up display device 10b configured as described above, the deflection angle α of the reference optical axis L1 in the concave mirror 28b is 18 degrees (Table 3), 15 <α <33, particularly 20 <α <25. It is a value. Further, the projection magnification β of the head-up display device 10b is 10 times, and the focal length f of the concave mirror 28b is 92.73 mm.

[Example 3]
As shown in FIG. 8, the mirror optical system 22c of the head-up display device 10c includes a first flat mirror 26c, a concave mirror 28c, a liquid crystal panel 23, and the like. The head-up display device 10c is configured to display a virtual image through the windshield of the automobile as in the first and second embodiments, and displays a virtual image at a position 2m ahead of the driver. . Further, the size of the virtual image displayed by the head-up display device 10c was also set to width h × height v = 150 mm × 50 mm and the size of the entrance pupil was 100 mm × 40 mm, as in the first and second embodiments.

  The effective size of the first plane mirror 26c involved in the display of the virtual image is that the length A in the vertical direction (the vertical direction of the head-up display device 10c as viewed from the driver) is 90 mm, and the horizontal direction (as viewed from the driver). The length in the horizontal direction of the head-up display device 10c is 122 mm. Similarly, the effective size with which the concave mirror 28b is involved in the display of the virtual image is 47 mm in the vertical length B and 122 mm in the horizontal direction.

  Similarly to the first and second embodiments, an xyz coordinate system having an origin at the intersection of the reference optical axis L1 and the first flat mirror 26c is defined, and each of the first flat mirror 26c, the concave mirror 28c, and the liquid crystal panel 23 is determined. Specific coordinates are shown in Table 5. At the same time, the lower part of Table 5 also shows various conditions of the head-up display device 10c.

  As shown in Table 5, the first plane mirror 26c is disposed with an inclination of 37.15 degrees from the xz plane with the x-axis direction as the rotation axis, and the distance from the driver to the coordinate system origin is 943 mm. Arranged.

  Further, the liquid crystal panel 23 has coordinates (x, y, z) = (0.00, −48.91, −47.92) of the intersection (center of the display surface) between the display surface and the reference optical axis L1. Arranged to be. Further, the angle formed between the normal line of the display surface and the z axis is 14.30 degrees, and the angle formed between the normal line of the display surface and the reference optical axis L1 (inclination angle of the liquid crystal panel 23) γ is The liquid crystal panel 23 was rotated and arranged about the x-axis direction so as to be 15.7 degrees. The display surface of the liquid crystal panel 23 has a size of width h × height v = 15 mm × 5 mm.

  The concave mirror 28c is arranged so that the position of the optical axis L2 is (x, y, z) = (0.00, 17.19, −95.08), and the optical axis L2 and the y axis are The x-axis direction was rotated and arranged so that the angle formed was 64.86 degrees. The distance from the intersection with the reference optical axis L1 on the concave mirror 28c to the virtual image, that is, the optical path length L from the virtual image to the concave mirror 28a is 1020 mm. Further, the surface shape of the concave mirror 28c is expressed by the above-described equation 1 as in the first and second embodiments, and the non-rotationally symmetric aspheric coefficients CX, CY, KAX, KAY, A4, K2, A6, and K3 are specific. Table 6 shows the values.

  Further, as in the first and second embodiments, an XY coordinate system having the center of the liquid crystal panel 23 (intersection of the display surface and the reference optical axis) as the origin and the horizontal direction as the X axis is defined. Upper image coordinates (0.0, 2.5), (0.0, 0.0), (0.0, -2.5), (7.5, 2.5), (7.5, The spot diagrams of the points 0.0) and (7.5, −2.5) are shown in FIGS. The scale of the image coordinates is mm, and each spot diagram is indicated by a scale having a reference length (upper right of FIG. 9) of 200 μm.

  In the head-up display device 10c configured as described above, the deflection angle α of the reference optical axis L1 in the concave mirror 28c is 30 degrees (Table 5), which falls within the range of 15 <α <33, particularly 20 <α <. The value is in the range of 25. Further, the projection magnification β of the head-up display device 10c is 10, and the focal length f of the concave mirror 28c is 92.73 mm.

  As described above, the mirror optical system of the present invention and the head-up display device on which the mirror optical system is mounted have a configuration in which the reference optical axis L1 has a unique optical path order that is folded back to the first plane mirror, and the focal point of the concave mirror. Since the distance is short, a concave mirror and a liquid crystal panel (and a light source for illuminating the same) can be used. Therefore, the mirror optical system and the head-up display device on which the mirror optical system is mounted are configured compactly as a whole. Further, when each part of the head-up display device is downsized, the manufacturing cost of the head-up display device is reduced, and the power consumption during virtual image display can be suppressed. Furthermore, since the deflection angle α of the reference optical axis L1 in the concave mirror is within the range of 15 <α <33, the unique optical path order as described above is realized and the aberration due to the concave mirror is reduced. Can be improved. Further, by arranging the liquid crystal panel to be inclined with respect to the reference optical axis L1, it is possible to observe a focused virtual image at any position of the displayed virtual image. Further, by arranging the second plane mirror so that the display light from the liquid crystal panel is folded and incident on the first plane mirror, the vertical direction of the head-up display device (the head-up display as viewed from the observer) can be obtained. The length in the vertical direction), that is, the thickness can be further reduced.

  As shown in the above-described embodiments and examples, the first flat mirror, the concave mirror, and the liquid crystal panel are arranged in order from the driver (observer) side to the liquid crystal panel (second flat mirror). Although the one plane mirror and the concave mirror are arranged in this order, the arrangement order of each part constituting these head-up display devices is not limited to this. That is, in the head-up display device shown in the above-described embodiments and examples, in order to install the head-up display in a so-called horizontal position in which the longitudinal direction is arranged so as to be substantially perpendicular to the driver or the like, The arrangement is as described above. However, for example, in the case of the head-up display device 10d installed in a so-called vertical position, as shown in FIG. 5, each part of the mirror optical system 22d is connected to the light source 24d and the liquid crystal panel 23d from the observer side such as the driver. The second plane mirror 27d, the concave mirror 28d, and the first plane mirror 26d may be arranged in this order.

  In the above-described embodiment, the head-up display device of the present invention is described as an example for an automobile. However, the present invention is not limited to this, and the head-up display device of the present invention is applied to other devices such as an aircraft and a ship. It can be used suitably. Thus, when the head-up display device of the present invention is applied to a device other than an automobile, the surface shape of a non-rotationally symmetric aspheric surface is set according to the shape of a reflecting surface (a windshield in an automobile) that magnifies and projects display light. However, it is necessary to individually determine the detailed surface shape of the concave mirror. Moreover, since the state of inclination and curvature of the windshield differs depending on the vehicle type and the like, the same adjustment is necessary even when the head-up display device of the present invention is used in an automobile.

  In the above-described embodiment, an example in which the image display panel is a transmissive liquid crystal panel is described. However, the present invention is not limited thereto, and the image display panel may be a reflective liquid crystal panel. The liquid crystal mode may be selected as appropriate. Further, the image display panel is not limited to one using liquid crystal, and other known image display panels may be used as long as they can emit display light.

    Since the head-up display device is installed on a dashboard or the like of an automobile, each part constituting the head-up display device is preferably excellent in heat resistance.

It is explanatory drawing which shows the outline of a head-up display apparatus. It is a schematic sectional drawing which shows the structure of a head-up display apparatus. It is explanatory drawing which shows the surface shape of a concave mirror. FIG. 3 is a cross-sectional view illustrating a specific configuration of the head-up display device according to the first embodiment. FIG. 3 is a spot diagram of the mirror optical system of Example 1. FIG. It is sectional drawing which shows the specific structure of the head-up display apparatus of Example 2. FIG. 6 is a spot diagram of the mirror optical system of Example 2. FIG. 6 is a cross-sectional view showing a specific configuration of a head-up display device of Example 3. FIG. 10 is a spot diagram of the mirror optical system of Example 3. FIG. It is explanatory drawing which shows the example which each part of a mirror optical system becomes another arrangement | positioning.

Explanation of symbols

10, 10a-d Head-up display device 12 Car 14 Driver (observer)
18 Windshield (reflective surface)
22, 22a to d Mirror optical system 23 Liquid crystal panel (image display panel)
24 Light source 26, 26a-d First plane mirror 27 Second plane mirror 28, 28a-d Concave mirror L1 Reference optical axis L2 Concave mirror optical axis

Claims (5)

A mirror that reflects the display light from the image display panel to the viewer with a reflecting surface facing the viewer at a predetermined position, and enlarges and displays the image displayed on the image display panel as a virtual image through the reflecting surface. In the optical system,
When a principal ray path that tracks the display light that is the center of the virtual image is a reference optical axis,
A first plane mirror that reflects display light from the image display panel and deflects the reference optical axis;
The surface shape is a non-rotationally symmetric aspherical surface, which is arranged eccentrically with respect to the reference optical axis, reflects the display light reflected by the first plane mirror, and again reflects the display light to the first plane mirror. And a concave mirror that magnifies and projects the image displayed on the image display panel,
With
The first flat mirror reflects the image magnified and projected from the concave mirror by the reflecting surface and displays it as a virtual image. An angle α (degree) formed by a reference optical axis of the display light incident on the concave mirror from the first flat mirror and a reference optical axis of the display light incident on the first flat mirror from the concave mirror is 15 <Α <33
The mirror optical system according to claim 1, wherein:   3. The mirror optical system according to claim 1, wherein the image display panel is disposed to be inclined with respect to the reference optical axis.   4. The mirror optical according to claim 1, further comprising: a second plane mirror between the image display panel and the first plane mirror that reflects and guides the display light to the first plane mirror. 5. system.   A head-up display device comprising the mirror optical system according to claim 1.

Images