JP6410094B2 - Head-up display - Google Patents

Description

  The present invention relates to a head-up display that allows a viewer to visually recognize a virtual image.

  A conventional head-up display, as an illumination optical system, for example, as disclosed in Patent Document 1, emits a light beam from a light source, and a condenser lens collects the light beam from the light source into a substantially parallel light. The lens array receives light from the lens, generates a plurality of intermediate images of the light source, and irradiates the display member with light from the intermediate image at a predetermined angle by the field lens, thereby displaying the display image emitted from the display member Is uniformly distributed over the entire eye box.

JP 2012-203176 A

  However, the illumination optical system of the display member used in such a head-up display has a large size along the optical axis because a plurality of optical members such as lenses are arranged along the optical axis of the light beam emitted from the light source. There was a risk of becoming.

  In addition, by adding a reflection part and bending the light beam, the size increase in the optical axis direction can be suppressed, but adding the reflection part increases the cost and further increases the overall volume. There's a problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a head-up display that can uniformly distribute light to an eyebox while keeping the size small.

  In order to achieve the above object, the head-up display according to the first aspect of the present invention emits display light 200 emitted from a display device including the illumination optical system 10 and the display element 20 to a projection member (concave mirror 40, windshield 2). (Transmission reflection surface)) is a head-up display that guides to the eye box 3 to visually recognize the virtual image W, and the illumination optical system 10 includes a light source 11 that emits illumination light 100 that illuminates the display element 20, and The lens array 13 that divides the light emitted from the light source 11 to generate a plurality of images of the light source 11 and the illumination light 100 emitted from the image of the light source 11 are condensed so as to correspond to the display area of the display element 20. Condensing means (curved surface reflecting portion 14 and field lens 15), and the condensing means includes curved surface reflecting portion 14 and field lens 15, Part 14 is one having an incident optical axis A1 of the illumination light 100 from the lens array 13, a plane consisting of the emission light axis A2 Metropolitan of the illumination light 100 to the field lens 15 a free-form surface shape which is symmetric.

  In the head-up display according to the second aspect of the invention, the apex of the curved reflecting portion 14 is eccentrically arranged at a position close to the lens array 13 side and a position away from the field lens 15 side.

  The head-up display according to the third aspect of the invention further includes a second case body 18 that holds the lens array 13 and has an opening 181 on the incident optical axis A1 from the lens array 13. The second case body 18 is engaged so as to close the opening 181.

  According to the first invention, the illumination light 100 from the lens array 13 is reflected by the curved reflecting portion 14 so as to be condensed on the surface of the display element 20, and the illumination light 100 to the display element 20 is reflected by the field lens 15. Since the incident angle can be adjusted, it is possible to reduce the field lens condensed on the display element 20, and to reduce the size of the light source 11 of the illumination optical system 10 in the optical axis direction. Further, since the curved reflecting portion 14 has a free curved surface shape that is symmetric in the direction perpendicular to the incident optical axis A1 and the outgoing optical axis A2, the display element 20 can be illuminated uniformly without unevenness. .

  In addition, according to the second invention, the apex of the curved reflecting portion 14 is decentered to a position close to the lens array 13 side and a position away from the field lens 15 side, so that the display element 20 can be made uniform. Uniform illumination is possible.

  In addition, according to the third invention, the curved reflection portion 14 is not configured to be housed in the case body, but the curved reflection portion 14 is engaged so as to close the opening 181 of the second case body 18, Usually, the curved reflecting portion 14 can play the role of the wall of the second case body that is required to block the optical path of the illumination light 100, and the size of the second case body 18 can be kept small.

It is a schematic sectional drawing explaining the structure of HUD in embodiment of this invention. It is a schematic sectional drawing of the illumination optical system in the said embodiment. It is a figure for demonstrating the position of the vertex of the curved-surface reflection part in the said embodiment.

  An embodiment of a head-up display (hereinafter, HUD) of the present invention will be described with reference to the drawings.

  The HUD 1 in this embodiment includes an illumination optical system 10, a display element 20, a plane mirror 30 that is a projection optical system, a concave mirror 40, and a housing 50. Illumination light 100 emitted from the illumination optical system 10 is spatially light modulated by the display element 20 into display light 200 indicating a display image (not shown). The display light 200 is directed to the windshield 2 (reflection / transmission surface) outside the HUD 1 by the plane mirror 30 and the concave mirror 40 which are projection optical systems. The display light 200 reflected by the windshield 2 is distributed to the eye box 3. If the observer's viewpoint is in the eye box 3, it is possible to make the observer visually recognize the virtual image of the display image generated by the display element 20 with a desired luminance. Specifically, the eye box 3 is, for example, a rectangular region having a horizontal direction of 120 mm and a vertical direction of 60 mm as viewed from the observer. If it is in this eye box 3, HUD1 adjusts the light distribution of the display light 200 so that the observer can visually recognize the virtual image W of substantially constant luminance.

The display element 20 is a transmissive spatial light modulation element such as a liquid crystal display (LCD). The display element 20 receives illumination light 100 from the illumination optical system 10 on the back surface, and receives the illumination light 100 based on an image signal input from the outside. By performing spatial light modulation, display light 200 indicating a display image (not shown) is emitted from the surface side. The display area of the display element 20 has a horizontally long aspect ratio that is longer in the horizontal direction than the vertical direction, and the display light 200 emitted from the display element 20 is also distributed to the horizontally long eyebox 3. In addition, the incident angle of the illumination light 100 incident from the back surface of the display element 20 is different for each region of the display element 20, and therefore, the emission angle (orientation direction) of the display light 200 emitted from the surface side of the display element 20. This also differs for each region of the display element 20. In this way, the display light 200 emitted from each region of the display element 20 after the display light 200 has passed through the projection optical system (concave mirror 40 and the windshield 2) having a curved surface is spread over the entire eye box 3. It can be adjusted so that the light distribution is substantially uniform.
The illumination optical system 10 according to the present embodiment adjusts the emission angle (orientation angle) of the display light 200 emitted from the display element 20 by adjusting the angle of the illumination light 100 incident on the display element 20. The display light 200 emitted from each of the 20 regions is adjusted so as to be distributed substantially evenly over the entire eye box 3 after passing through the plane mirror 30, the concave mirror 40 and the windshield 2 which are projection optical systems. . The illumination optical system 10 will be described in detail later.

Next, the plane mirror 30 and the concave mirror 40 which are projection optical systems will be described.
The plane mirror 30 is a planar reflecting member and reflects the display light 200 incident from the display element 20 toward the concave mirror 40.
The concave mirror 40 is a reflecting member having a free curved surface with a concave reflecting surface, and emits the display light 200 incident from the plane mirror 30 toward the windshield 2 (reflection / transmission surface) outside the HUD 1. The concave mirror 40 enlarges the display image generated by the display element 20 and further corrects the display light 200 so as to suppress distortion of the virtual image W when viewed as a virtual image W by an observer, thereby correcting the windshield 2. Turn to.

  The housing 50 is formed of, for example, black light-blocking synthetic resin, and is a case that houses the display element 20, the plane mirror 30, the concave mirror 40, and the like on the inside, and the illumination optical system 10 is attached on the outside. The housing 50 includes an illumination light opening 51 for taking in the illumination light 100 from the illumination optical system 10 and a display light opening 52 for emitting the display light 200 to the outside.

  The above is the configuration of the HUD 1 in the present embodiment, and the illumination optical system 10 in the present embodiment will be described with reference to FIGS. FIG. 2 is a diagram showing a schematic cross-sectional view of the illumination optical system 10, and FIG. 3 is a diagram for explaining the position P of the apex of the curved reflecting portion 14. In the drawing, the optical axis of the illumination light 100 emitted from the light source 11 is the A1 axis (incident optical axis), and the optical axis of the illumination light 100 emitted from the illumination optical system 10 toward the display element 20 is the A2 axis. (Emitted optical axis), and the normal direction of the plane composed of the incident optical axis A1 and the incident optical axis A2 is defined as the A3 axis.

  The illumination optical system 10 is a so-called Koehler illumination optical system. As shown in FIG. 2, the light source 11, the condenser lens 12, the lens array 13, the curved reflector 14, the field lens 15, and the light source 11 are generated. A heat radiating member 16 that radiates heat to the outside, a first case body 17 that holds the light source 11 and the condenser lens 12, a second case body that holds the lens array 13, the curved reflection portion 14, and the field lens 15. 18. The illumination optical system 10 irradiates the display area of the display element 20 with illumination light 100 emitted from the light source 11 uniformly, and passes through the projection optical system (plane mirror 30, concave mirror 40, windshield 2) in the eye box 3. The orientation angle of the display light 200 is adjusted so that the display light 200 is distributed substantially evenly.

  The light source 11 includes a light emitting element such as an LED mounted on the circuit board 11a, and emits illumination light 100. The circuit board 11a on which the light source 11 is mounted is connected to a heat radiating member 16 to be described later so that heat can be easily exchanged, and the heat generated by the light source 11 is released to the outside through the heat radiating member 16.

The condenser lens 12 is a convex lens made of an optical resin, collects the illumination light 100 emitted from the light source 11, and is incident on the incident optical axis A <b> 1 of the illumination light 100 from the light source 11 to the curved reflection portion 14 described later. Have the function of parallelizing.
A modification of the condenser lens 12 is shown below. The condenser lens 12 corresponds to one light source 11, and when a plurality of light sources 11 are used, the condenser lens 12 takes the form of a collective lens in which a plurality of convex lens portions are arranged. The condenser lens 12 may be replaced with a collimating lens that collimates the illumination light 100. Further, a configuration in which a plurality of lenses are arranged on the optical path of the illumination light 100 may be adopted. Further, in the drawing, the condenser lens 12 is illustrated with curved surfaces on both the incident side and the outgoing side, but the incident side or the outgoing side may be a flat surface. The curved surface shape may be a spherical surface or an aspherical surface, and may be composed of a symmetric lens or an asymmetric lens. The condenser lens 12 may be made of heat-resistant optical glass in order to suppress deterioration due to heat from the light source 11.

The lens array 13 is an optical member formed by regularly arranging a plurality of rectangular minute convex lenses made of an optical resin on both surfaces (incident side and outgoing side) perpendicular to the incident optical axis A1. The illumination light 100 collimated by the lens 12 is divided according to the number of arrays and has a role of connecting an intermediate image near the light receiving surface of the display element 20. This intermediate image is an image obtained by dividing the enlarged image of the light source 11 generated by the condenser lens 12 by the number of arrays. The lens array 13 adjusts the numerical aperture (Numerical Aperture) of the illumination light 100 emitted from the intermediate image plane by adjusting the vertical curvature and the horizontal curvature of each microlens differently. And the horizontal direction can be optimized differently. The ratio of the vertical and horizontal widths of each microlens (vertical width: horizontal width) is set to be substantially equal to the aspect ratio of the display element 20 (vertical and horizontal size ratio of the display area). Thereby, the shape of the intermediate image generated by the lens array 13 is similar to the shape of the display area of the display element 20, and the illumination efficiency when the display element 20 is incident can be improved. Further, the thickness of the lens array 13, that is, the distance between the curved surface vertex of the incident side microlens and the curved surface vertex of the exit side microlens is the illumination incident on the lens array 13 with reference to the incident side curved surface of the microlens. The position where the paraxial ray of the light 100 is refracted and condensed (by design, this position is equal to the intermediate image plane) is defined as the exit-side curved surface. Note that the curved surface on the incident side and the curved surface on the output side of the lens array 13 have the same radius of curvature with opposite directions.
A modification of the lens array 13 is shown below. In the lens array 13 of the present embodiment, the curved surface shape of each micro lens is a toroidal surface in which the curvature in the vertical direction and the curvature in the horizontal direction are different from each other. It is good. Alternatively, the microlenses may be arranged in a honeycomb shape such as a hexagonal shape. Further, the lens array 13 of the present embodiment may be replaced with a lenticular lens array or the like.

The curved reflecting portion 14 has a free-form reflecting surface 141 and collects and reflects the illumination light 100 incident from the lens array 13 toward the field lens 15. The curved surface shape of the reflecting surface 141 is a symmetric curved surface having a plane formed by the incident optical axis A1 of the illumination light 100 incident from the lens array 13 and the output optical axis A2 of the illumination light 100 emitted to the field lens 15 as a symmetric surface. Is a free-form surface. The curved reflection portion 14 is arranged off-axis so that the incident optical axis A1 of the illumination light 100 is incident on a position shifted from the apex P of the curved reflection portion 14. Specifically, the apex P of the reference spherical surface of the curved reflecting surface 14 that is a free curved surface (the position through which the optical axis Z on the reflecting surface 141 of the curved reflecting surface 14 passes) is the incident optical axis A1 as shown in FIG. Is located on the plane composed of the output optical axis A2 but shifted from the position Q of the reflecting surface 141 through which the incident optical axis A1 passes to a position closer to the lens array 13 side and away from the field lens 15 side. Is done.
Further, the curved reflecting portion 14 is integrally formed around the reflecting surface 141 of the curved reflecting portion 14 for engaging with a second case body 18 that holds a lens array 13 and the like to be described later. Have

The curved surface shape of the curved reflecting portion 14 is a direction perpendicular to the plane formed by the incident optical axis A1 and the outgoing optical axis A2 with the normal direction of the reflecting surface 141 at the apex P of the reference spherical surface of the curved reflecting portion 14 being the Z axis. When the X axis and the direction perpendicular to the X axis and the Z axis are defined as the Y axis, the free surface is formed based on an XY polynomial that satisfies the following expression (1). Z indicates the displacement amount (sag amount) in the Z-axis direction when z = 0 at the apex P (x = 0, y = 0) of the reference spherical surface of the curved reflecting portion 14, and c indicates the amount at the apex P. Indicates a curvature (c = 1 / R, R = radius of curvature), k indicates a conic coefficient which is a conical coefficient, r ² indicates x ² + y ² , and C _j indicates an aspheric coefficient . C _j is defined as shown in Table 1 below.

As described above, in the present embodiment, since the aspheric coefficient C _j of the odd-order term of x is 0, the curved reflecting portion 14 has a curved shape that is symmetric in the X-axis direction. Further, the curved surface reflecting portion 14 in the present embodiment has a position where the apex P of the reference spherical surface is closer to the lens array 13 side than the position Q of the reflecting surface 141 through which the incident optical axis A1 passes and away from the field lens 15 side. By off-axis so as to deviate from each other, the entire display area of the display element 20 can be illuminated substantially uniformly in cooperation with the field lens 15, and the display light 200 emitted from the display element 20 can be arranged. The light angle can be adjusted appropriately.

  The field lens 15 is a spherical convex lens made of an optical resin. The field lens 15 adjusts the light distribution angle of the illumination light 100 that irradiates the back surface of the display element 20 in cooperation with the curved reflector 14. Thereby, the light distribution angle of the display light 200 emitted from the display element 20 can be adjusted, and the display light 200 can be distributed substantially uniformly over the entire eye box 3.

  The heat radiating member 16 is made of, for example, aluminum, and is configured by a heat sink or the like whose surface is anodized in order to improve the emissivity. The heat dissipating member 16 engages with a first engagement portion 171 of the first case body 17 (not shown) and engages with a third engagement portion 182 of the second case body 18 (not shown). And the first case body 17 and the second case body 18 are engaged with the respective engagement portions of the heat radiating member 16, so that the light source 11, the condenser lens 12, and the lens array are engaged. 13, the curved reflecting portion 14 and the field lens 15 are indirectly positioned and held. Further, the heat dissipation member 16 is engaged with the outside of the housing 50.

  The first case body 17 is made of, for example, black light-shielding synthetic resin, holds the light source 11 mounted 11 a and the condenser lens 12, and engages the first engagement portion 171 with the heat dissipation member 16. Thus, the light source 11 and the condenser lens 12 are positioned and fixed with respect to the heat radiating member 16.

  The second case body 18 is formed of, for example, a black light-shielding synthetic resin, and holds the lens array 13, the curved reflection portion 14, and the field lens 15. The second case body 18 has an opening 181 in the traveling direction of the illumination light 100 from the lens array 13 (the direction along the incident optical axis A1), and a second engagement provided around the opening 181. The curved reflecting portion 14 is held by engaging the fitting portion 182 with the mounting portion 142 of the curved reflecting portion 14 by the mounting member 142a. In the present embodiment, the curved reflection portion 14 is engaged with the opening 181 by the mounting member 142a such as a screw. However, the mounting member 142a such as a screw from the direction substantially along the opening 181. Thus, the second case body 18 may be engaged. Further, the second case body 18 has a third engaging portion 183, and the third engaging portion 183 is engaged with the heat radiating member 16, whereby the lens array 13, The curved reflector 14 and the field lens 15 are positioned and fixed.

That is, the illumination optical system 10 in the present embodiment divides the collimated illumination light 100 from the condenser lens 12 by the lens array 13 to generate each intermediate image, and illumination light emitted from each generated intermediate image. Each of 100 is enlarged by the curved reflecting portion 14 and the field lens 15 so that the entire surface of the display element 20 (a plane passing through the center line in the thickness direction of the liquid crystal layer) is irradiated. In addition, the illumination optical system 10 adjusts the light distribution angle of the illumination light 100 incident on the display element 20 by the curved reflecting portion 14 and the field lens 15. Thereby, since each display light 200 emitted from each region of the display element 20 is distributed almost uniformly over the entire eye box 3, the uniformity of the virtual image W accompanying the movement of the viewpoint in the eye box 3 is kept low. Can do. The light distribution angle on the surface of the display element 20 is obtained by connecting a ray group connecting the eye box 3 and the virtual image W whose position is determined in advance via the projection optical system of the HUD 1 (in the present embodiment, the windshield 2 and the concave mirror 40). Therefore, it is obtained by tracing back rays.

  In addition, this invention is not limited to said embodiment, A various deformation | transformation is possible.

  In the above-described embodiment, the display element 20 is a transmissive spatial light modulator, but a reflective spatial light modulator such as DMD (Digital Mirror Device) or LCoS (registered trademark: Liquid Crystal on Silicon) may be used. Good.

  In the above-described embodiment, the circuit board 11a, the condenser lens 12, the lens array 13, the curved reflection portion 14, and the field lens 15 are attached to the separate first case body 17 and second case body 18, respectively, and then radiated heat. Although engaged with the member 16, one or three or more case bodies may be used. Moreover, you may engage a part with the heat radiating member 16 directly.

  Moreover, in the said embodiment, although the windshield 2 was mentioned as an example of the permeation | transmission reflection part which directs the display light 200 to the eye box 3, it is not limited to this. The HUD 1 may be provided with a dedicated combiner, and the observer may visually recognize the virtual image W by reflecting the display light 200 with the combiner.

1 HUD (head-up display)
2 Windshield (reflection / transmission part)
DESCRIPTION OF SYMBOLS 3 Eye box 10 Illumination optical system 11 Light source 11a Circuit board 12 Condenser lens 13 Lens array 14 Curved surface reflection part 15 Field lens 16 Heat radiating member 17 First case body 18 Second case body 20 Display element 30 Plane mirror (projection optical system)
40 Concave mirror (projection optical system)
50 Housing 100 Illuminating light 141 Reflecting surface 142 Mounting portion 171 First engaging portion 181 Opening portion 182 Second engaging portion 183 Third engaging portion 200 Display light

A1 incident optical axis A2 outgoing optical axis A3 axis P vertex W virtual image

Claims (3)

Display light emitted from a display device including an illumination optical system and a display element, through a projection member,
A head-up display that leads to a viewpoint area and visually recognizes a virtual image,
The illumination optical system includes:
A light source that emits light for illuminating the display element;
A lens array that divides light emitted from the light source to generate a plurality of images of the light source;
Condensing means for condensing the light emitted from the image of the light source so as to correspond to the display area of the display element,
The condensing means includes a curved surface reflection part and a field lens,
The head-up display, wherein the curved reflecting portion has a free curved surface shape that is symmetrical with respect to a plane composed of an incident optical axis of light from the lens array and an optical axis of light emitted to the field lens. .   2. The head-up display according to claim 1, wherein the apex of the curved reflecting portion is eccentrically arranged at a position close to the lens array side and a position away from the field lens side. It said lens array holds, further comprising a case body having an opening on the incident light axis from the lens array,
The head-up display according to claim 1, wherein the curved reflecting portion is engaged with the case body so as to close the opening.

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