JP2018165782A - Display device, optical element, and moving body equipped with display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device, capable of preventing degradation of quality of projection image, an optical element, and a moving body equipped with the display device.SOLUTION: A display device 10 includes an image forming part 2 and an optical element 4. The image forming part 2 is configured to output a beam of light for forming images. The optical element 4 is configured to reflect output light from the image forming part 2 and to project the images. The optical element 4 has a first plane 41 and a second plane 42 different from the first plane 41. The optical element 4 is configured to reflect the output light from the image forming part 2 incident on the optical element 4 through the first plane 41 by the second plane 42 and to output the same from the optical element 4 through the first plane 41.SELECTED DRAWING: Figure 1

Description

  The present disclosure generally relates to a display device, an optical element, and a moving body including the display device, and more specifically, a display device that projects an image by reflecting output light of an image forming unit by the optical element, an optical element, And a moving body including a display device.

  2. Description of the Related Art Conventionally, a display device such as a head-up display that projects an image (video) on a windshield (front glass) of a vehicle and allows a driver to visually recognize the virtual image and a transmission background is known (for example, Patent Documents). 1).

  The display device described in Patent Document 1 includes display means including a liquid crystal element and a light source, and deflection means including a mirror or the like. The output light (display light) displayed by the display means is projected onto the deflecting means and deflected toward the windshield by the deflecting means. The windshield reflects output light from the display device toward the driver and forms a virtual image of the display image. In Patent Document 1, in order to make the double image (ghost) inconspicuous even when the output light is reflected by the windshield in which the inner glass and the outer glass are bonded via the intermediate film, the display means is the main display. A display image is generated by superimposing one or more auxiliary elements on the element.

JP 2012-83534 A

  It is an object of the present invention to provide a display device, an optical element, and a moving body including a display device that can reduce deterioration in quality of a projected image.

  A display device according to a first aspect includes an image forming unit and an optical element. The image forming unit outputs light for forming an image. The optical element projects the image by reflecting the output light of the image forming unit. The optical element has a first surface and a second surface different from the first surface. The optical element is configured to reflect the output light incident on the optical element through the first surface at the second surface and to emit from the optical element through the first surface.

  The display device according to a second aspect is the display device according to the first aspect, wherein the thickness of the optical element in the opposing direction of the first surface and the second surface is at least one direction of the vertical direction and the horizontal direction of the image. Changes.

  In the display device according to the third aspect, in the first or second aspect, the first surface and the second surface are different in shape from each other.

  In the display device according to a fourth aspect, in any one of the first to third aspects, the optical element further includes a reflective film formed on the second surface.

  In the display device according to a fifth aspect, in any one of the first to fourth aspects, the first surface includes an incident surface and an output surface that are different from each other. The optical element totally reflects the output light incident on the optical element through the incident surface of the first surface on the second surface and emits the light from the optical element through the emission surface of the first surface. It is configured as follows.

  An optical element according to a sixth aspect is an element that projects the image by reflecting output light from an image forming unit that outputs light for forming an image. The optical element includes a base material having a first surface and a second surface different from the first surface. The optical element is configured to reflect the output light incident on the base material through the first surface at the second surface and emit the light from the base material through the first surface.

  A moving body according to a seventh aspect includes the display device according to any one of the first to fifth aspects, and a reflecting member on which the image is projected.

  The present disclosure has an advantage that it is possible to reduce deterioration of the quality of the projected image.

FIG. 1 is a conceptual diagram illustrating a configuration of a display device according to the first embodiment. FIG. 2 is a conceptual diagram of an automobile provided with the above display device. FIG. 3 is a conceptual diagram showing a user's field of view when the display device is used. FIG. 4A is a side view of an optical element of the above display device. 4B is a cross-sectional view showing a cross section of a region Z1 in FIG. 4A for the optical element same as above. FIG. 5 is a conceptual diagram illustrating a configuration of a display device according to a comparative example of the first embodiment. 6A to 6D are conceptual diagrams illustrating optical elements of the display device according to the first modification of the first embodiment. FIG. 7 is a conceptual diagram illustrating a configuration of a display device according to a second modification of the first embodiment. FIG. 8 is a conceptual diagram illustrating a configuration of a display device according to a third modification of the first embodiment. FIG. 9 is a conceptual diagram illustrating a configuration of the display device according to the second embodiment.

  In general, in a display device such as a head-up display (HUD), an optical element (mirror) that reflects light is used as means for projecting an image onto an object (for example, a windshield). Usually, an optical element used for image projection is a surface reflecting mirror in which a reflective film made of a metal film or the like is formed on the surface of a base material by vapor deposition or the like. However, when a surface reflecting mirror is used as an optical element, there is a problem that, for example, dirt, surface roughness, or scratches on the reflecting film directly leads to a reduction in the quality of the projected image. The present disclosure has been made in view of such a reason, and reduces the deterioration of the quality of the projected image due to dirt, surface roughness, scratches, or the like of the optical element.

(Embodiment 1)
(1) Outline As shown in FIGS. 1 and 2, the display device 10 according to the present embodiment is a head-up display used in an automobile 100 as a moving body, for example.

  The display device 10 is installed in the vehicle interior of the automobile 100 so as to project an image onto the windshield 101 of the automobile 100 from below. In the example of FIG. 2, the display device 10 is disposed in the dashboard 102 below the windshield 101. When an image is projected on the windshield 101 from the display device 10, the image reflected by the windshield 101 as a reflecting member is visually recognized by the user 200 (driver) in the eye box 201. The “eye box 201” here is a range in which the user 200 can visually recognize the image without lacking in the vehicle interior.

  According to such a display device 10, the user 200 visually recognizes the virtual image 300 projected on the target space 400 set in front of the automobile 100 (outside the vehicle) through the windshield 101. As used herein, the “virtual image” means an image that is connected so that an object is actually present by the divergent light when the light emitted from the display device 10 diverges by a reflector such as the windshield 101. Therefore, as shown in FIG. 3, the user 200 driving the automobile 100 can see the virtual image 300 projected on the display device 10 so as to overlap the real space spreading in front of the automobile 100. Therefore, according to the display device 10, for example, various driving support information such as vehicle speed information, navigation information, pedestrian information, forward vehicle information, lane departure information, and vehicle condition information is displayed as the virtual image 300, and the user 200 can be visually recognized. In FIG. 3, the virtual image 300 is vehicle speed information, and information “53 km / h” is displayed as an example. As a result, the user 200 can visually acquire the driving support information by only a slight line-of-sight movement from a state where the line-of-sight is directed in front of the windshield 101.

  In the display device 10, the virtual image 300 formed in the target space 400 is formed on a virtual plane 501 that intersects the optical axis 500 of the display device 10. In the present embodiment, the optical axis 500 is along the road surface 600 in front of the automobile 100 in the target space 400 in front of the automobile 100. A virtual surface 501 on which the virtual image 300 is formed is substantially perpendicular to the road surface 600. For example, when the road surface 600 is a horizontal plane, the virtual image 300 is displayed along the vertical plane.

  Here, in the display device 10 according to the present embodiment, the projection optical system 3 (see FIG. 1) for projecting an image onto an object (windshield 101) is an optical element 4 (see FIG. 1) composed of a back reflector. 1). The optical element 4 has a first surface 41 and a second surface 42. The optical element 4 is configured so that light incident on the optical element 4 through the first surface 41 is reflected by the second surface 42 and emitted from the optical element 4 through the first surface 41. That is, the optical element 4 takes light into the optical element 4 and reflects it within the optical element 4, unlike a surface reflecting mirror in which a reflective film made of a metal film or the like is formed on the surface of the substrate by vapor deposition or the like.

  The display device 10 according to the present embodiment uses such an optical element 4 for the projection optical system 3, and therefore, due to dirt, surface roughness, scratches, or the like of the optical element 4 compared to the case where a surface reflecting mirror is used. There is an advantage that the deterioration of the quality of the projected image can be reduced.

(2) Configuration (2.1) Overall Configuration of Display Device As shown in FIG. 1, the display device 10 according to the present embodiment includes an image forming unit 2 and a projection optical system 3. The projection optical system 3 includes an optical element 4. The display device 10 further includes a control unit 5 that controls the image forming unit 2. In the drawings other than FIG. 1, illustration of the control unit 5 is omitted.

  The image forming unit 2 outputs light for forming an image. In the present embodiment, as an example, the image forming unit 2 includes a liquid crystal panel 21 (LCD: Liquid Crystal Display) and a light source device 22 as shown in FIG. The liquid crystal panel 21 is disposed in front of the light source device 22. The light source device 22 is used as a backlight of the liquid crystal panel 21. The light source device 22 is a so-called surface light source. The light source device 22 is a sidelight type light source device using a solid light emitting element such as a light emitting diode or a laser diode. Light from the light source device 22 passes through the liquid crystal panel 21 and is output from the image forming unit 2.

  In the image forming unit 2, when the light source device 22 emits light in a state where an image is displayed on the liquid crystal panel 21, the light output forward from the light source device 22 is transmitted through the liquid crystal panel 21, and the liquid crystal panel 21 is output forward from the front surface of 21. At this time, the light output forward from the front surface of the liquid crystal panel 21 is the light reflecting the image displayed on the liquid crystal panel 21, and as a result, the light that forms the image is “from the image forming unit 2. It is output as “output light”. In FIG. 1, an optical path P1 of light output from one point (a certain pixel point) of an image displayed on the front surface of the image forming unit 2 (front surface of the liquid crystal panel 21) is schematically shown.

  Here, the vertical direction of the liquid crystal panel 21 is the vertical direction of the projected image, and the horizontal direction of the liquid crystal panel 21 is the horizontal direction of the projected image. The vertical direction of the projected image is the vertical direction of the virtual image 300 (see FIG. 2) projected onto the target space 400 (see FIG. 2), that is, the direction along the vertical direction in the visual field of the user 200 (see FIG. 2). It is. The vertical direction of the projected image is the horizontal direction of the virtual image 300 projected onto the target space 400, that is, the direction along the horizontal direction in the visual field of the user 200.

  The control unit 5 controls the image forming unit 2 (the liquid crystal panel 21 and the light source device 22). The control unit 5 is composed of, for example, a microcomputer having a CPU (Central Processing Unit) and a memory as main components. In other words, the control unit 5 is realized by a computer having a CPU and a memory, and the computer functions as the control unit 5 when the CPU executes a program stored in the memory. Here, the program is recorded in advance in the memory of the control unit 5, but may be provided through a telecommunication line such as the Internet or recorded in a recording medium such as a memory card.

  The projection optical system 3 projects an image by reflecting the output light of the image forming unit 2. In the present embodiment, the display device 10 is a head-up display as described above, and projects an image onto the windshield 101 (see FIG. 2), so the projection optical system 3 applies to an object made up of the windshield 101. Project the image.

  In this embodiment, as an example, the projection optical system 3 includes a first mirror 31 and a second mirror 32 as shown in FIG. The first mirror 31 and the second mirror 32 are arranged in the order of the first mirror 31 and the second mirror 32 on the optical path of the light output from the image forming unit 2. In the present embodiment, the image forming unit 2, the first mirror 31, and the second mirror 32 are arranged at the apex positions of triangles formed in the vertical plane. Here, the “vertical plane” is a plane including the vertical direction (vertical direction) of the image formed by the image forming unit 2 and the traveling direction (optical axis) of the output light. The projection optical system 3 first reflects the output light of the image forming unit 2 by the first mirror 31, further reflects by the second mirror 32, and emits the light toward the object (windshield 101).

  That is, the first mirror 31 is disposed on the opposite side of the light source device 22 as viewed from the liquid crystal panel 21, that is, in front of the liquid crystal panel 21 so that the output light of the image forming unit 2 is incident. The first mirror 31 reflects the output light of the image forming unit 2 toward the second mirror 32. The second mirror 32 is disposed at a position where the output light of the image forming unit 2 reflected by the first mirror 31 is incident. The second mirror 32 reflects the output light of the image forming unit 2 reflected by the first mirror 31 toward the object (windshield 101). In the present embodiment, the first mirror 31 is a convex mirror, and the second mirror 32 is a concave mirror. In other words, the first mirror 31 has a negative power as a whole, and the second mirror 32 has a positive power as a whole. The reflecting surfaces of the first mirror 31 and the second mirror 32 may be configured as free-form surfaces. In this case, the reflecting surfaces of the first mirror 31 and the second mirror 32 are locally supplied to the entire power. May have different power. For example, the reflecting surface of the first mirror 31 having negative power as a whole may locally have positive power.

  With the configuration as described above, the projection optical system 3 projects the image formed by the image forming unit 2 to an appropriate size and projects it on the object (windshield 101) as a projection image. A virtual image 300 (see FIG. 2) is projected onto 400 (see FIG. 2). That is, in the field of view of the user 200 who is driving the automobile 100, the virtual image 300 projected on the display device 10 can be seen superimposed on the real space spreading in front of the automobile 100.

  Incidentally, in the present embodiment, the second mirror 32 included in the projection optical system 3 is formed on the surface 321 of the base 320 made of glass or synthetic resin, for example, by vapor deposition of a reflective film made of a metal film or the like. It is a surface reflector. In the example of FIG. 1, the second mirror 32 has a plate-like base material 320. The surface 321 of the second mirror 32 is a surface facing the first mirror 31 side among both surfaces in the thickness direction of the base material 320. Therefore, the second mirror 32 reflects the output light (visible light) of the image forming unit 2 reflected by the first mirror 31 on the surface 321 of the base material 320 without taking it into the base material 320.

  On the other hand, the 1st mirror 31 is comprised with the optical element 4 which consists of a back surface reflecting mirror.

  The optical element 4 has a first surface 41 and a second surface 42. The second surface 42 is a surface different from the first surface 41. The optical element 4 is configured so that the output light of the image forming unit 2 that has entered the optical element 4 through the first surface 41 is reflected by the second surface 42 and is emitted from the optical element 4 through the first surface 41. Yes. Specifically, the optical element 4 includes a base material 40 having high transparency to visible light. The base material 40 is made of, for example, glass or transparent synthetic resin. In the example of FIG. 1, the substrate 40 is plate-shaped, and both surfaces in the thickness direction of the substrate 40 constitute a first surface 41 and a second surface 42, respectively. The first surface 41 is a surface facing the image forming unit 2 and the second mirror 32, that is, the “surface” of the first mirror 31. The second surface 42 is a surface facing away from the image forming unit 2 and the second mirror 32, that is, the “back surface” of the first mirror 31.

  That is, the first mirror 31 (optical element 4) is different from the second mirror 32 made of a surface reflecting mirror, and takes the output light (visible light) of the image forming unit 2 into the base material 40 to enter the base material 40. Reflected by (second surface 42). In other words, light taken into the first mirror 31 from the first surface 41 that is the “front surface” of the first mirror 31 is reflected by the second surface 42 that is the “back surface” of the first mirror 31, and the first The light is emitted from the first surface 41 which is the “surface” of the mirror 31 (see the optical path P1 in FIG. 1). Thus, in the optical element 4, the second surface 42, which is the “back surface”, functions as a reflecting surface that mainly reflects light.

  In the optical element 4 having such a configuration, unlike the surface reflecting mirror, most of the light incident on the first surface 41 is transmitted through the first surface 41 and reflected by the second surface 42 as a reflecting surface. . However, strictly speaking, a part of the light incident on the first surface 41 may be reflected (Fresnel reflection) on the first surface 41 serving as a boundary surface between the base material 40 and the air. Therefore, the first surface 41 can also be considered as a kind of reflecting surface, but in the optical element 4, the reflectance of the first surface 41 and the reflectance of the second surface 42 satisfy at least the following relationship. That is, when the reflectance of the first surface 41 with respect to visible light is “R1” and the reflectance of the second surface 42 with respect to visible light is “R2”, the reflectance R1 is smaller than the reflectance R2 (R1 <R2 ). Here, the difference between the reflectance R1 and the reflectance R2 is preferably set as large as possible, and at least the reflectance R2 is preferably 1.5 times or more of the reflectance R1.

  Thereby, even if a part of the light is reflected by the first surface 41, most of the light incident on the first surface 41 is transmitted through the first surface 41 and the second surface 42 as a reflecting surface. Will be reflected. Therefore, the light reflected by the optical element 4 is incident on the optical element 4 through the first surface 41, reflected by the second surface 42, and emitted through the first surface 41. Become.

  Here, the output light of the image forming unit 2 is not limited to the configuration in which the output light of the image forming unit 2 is directly incident on the first surface 41 of the optical element 4. Alternatively, the light may be reflected by a mirror other than the optical element 4 and indirectly incident. As an example, when the optical element 4 is used for the second mirror 32 as described in the section “(3.3) Third Modification”, the first surface 41 of the optical element 4 has an image forming unit. The second output light is indirectly incident by being reflected by the first mirror 31.

  The display device 10 according to the present embodiment uses such an optical element 4 for the projection optical system 3, and therefore, due to dirt, surface roughness, scratches, or the like of the optical element 4 compared to the case where a surface reflecting mirror is used. There is an advantage that the deterioration of the quality of the projected image can be reduced. By reducing the deterioration of the quality of the projected image projected on the object (windshield 101), the quality of the virtual image 300 (see FIG. 2) projected on the target space 400 (see FIG. 2) is also reduced. The

(2.2) Details of Optical Element Hereinafter, the optical element 4 constituting the first mirror 31 will be described in more detail with reference to FIGS. 4A and 4B.

  The optical element 4 further includes a reflective film 43 formed on the second surface 42 as shown in FIG. 4B. FIG. 4B is a cross-sectional view of the region Z1 in FIG. 4A. Except for FIG. 4B, the illustration of the reflective film 43 is omitted. The reflective film 43 is formed by applying a metal material such as silver, aluminum, or copper to the second surface 42 of the substrate 40. Since application by spray or the like can be easily performed as compared with vapor deposition or the like, according to this configuration, it is possible to reduce the manufacturing cost as compared with the surface reflecting mirror. Moreover, since the optical element 4 is a back reflector, the surface roughness of the reflective film 43 itself does not directly affect the reflectance of the optical element 4, and even if the reflective film 43 is formed by coating or the like, Sufficient reflectance can be realized. Such a reflective film 43 is formed only on the second surface 42 of both surfaces of the base material 40 in the thickness direction, and the first surface 41 has no reflective film. However, for example, an antireflection film may be formed on the first surface 41. Thereby, reflection (Fresnel reflection) on the first surface 41 is reduced.

  Moreover, in this embodiment, since the 1st mirror 31 is a convex mirror as mentioned above, the 2nd surface 42 used as at least a main reflective surface is a curved surface which becomes convex at the 1st surface 41 side. Here, it is assumed that the second surface 42 is a curved surface having a certain curvature. On the other hand, the first surface 41 has a shape based on the virtual curved surface S <b> 1 having the same shape as the second surface 42. The virtual curved surface S1 is a virtual surface that does not actually exist, and is indicated by an imaginary line (two-dot chain line) in FIG. 4A. The virtual curved surface S1 is a curved surface that has the same curvature as the second surface 42 and is convex on the opposite side of the second surface 42.

  The shape of the first surface 41 is set so as to add an aberration correction function to the virtual curved surface S1. Therefore, the first surface 41 and the second surface 42 have different shapes. Specifically, the first surface 41 has a shape in which the virtual curved surface S1 is partially brought closer to the second surface 42 side by weakening the convex component (that is, adding a concave component) for at least a part of the virtual curved surface S1. It is said that. In other words, the base material 40 between the first surface 41 and the second surface 42 acts as a concave lens having a negative power that is thicker at the outer peripheral portion than at the central portion. With such shapes of the first surface 41 and the second surface 42, the optical element 4 can reduce aberrations. According to this configuration, since the base material 40 of the optical element 4 is also used as an aspherical lens for correcting aberrations, a surface reflecting mirror is used as the first mirror 31 and combined with an aspherical lens for correcting aberrations. As compared with the above, the first mirror 31 can be made thinner by the thickness of the base material 40.

  Further, the thickness of the optical element 4 in the facing direction of the first surface 41 and the second surface 42 changes in at least one direction of the vertical direction and the horizontal direction of the image. That is, the thickness of the base material 40 is not constant, and in the present embodiment, the thickness of the base material 40 changes at least in the vertical direction of the image. Specifically, as shown in FIG. 4A, the other end portion in the vertical direction of the image (the lower end portion in FIG. 4A) with respect to the thickness D1 of the substrate 40 at one end portion in the vertical direction of the image (upper end portion in FIG. 4A). The thickness of the base material 40 is set so that the thickness D2 of the base material 40 in () increases (D1 <D2). In other words, the base material 40 is formed in a wedge shape (substantially V-shaped) whose one end is thin when viewed from the side.

  The inclination angle θ of the second surface 42 with respect to the first surface 41 is preferably 5 degrees or more. The inclination angle θ is preferably 30 degrees or less. In the example of FIG. 4A, the inclination angle θ is set to about 20 degrees as an example. Here, for example, the inclination angle θ is represented by an angle between a tangent plane of a reference ray (for example, the optical path P1 in FIG. 1) on the first surface 41 and a tangent plane of the reference ray on the second surface 42. . In FIG. 4A, an angle between a plane passing through both ends in the vertical direction of the image on the first surface 41 and a plane passing through both ends in the vertical direction of the image on the second surface 42 is defined as an inclination angle θ.

  With such a shape, for example, it is possible to reduce the occurrence rate of a double image (ghost) in which a plurality of images shifted from each other are projected in an overlapping manner. That is, the double image is generated due to the above-described reflection on the first surface 41 (Fresnel reflection) or multiple reflection caused by reflection on two or more reflection surfaces. This point will be described in detail while comparing with the display device 10H according to the comparative example shown in FIG.

  As shown in FIG. 5, the display device 10 </ b> H according to the comparative example is different from the display device 10 according to the present embodiment in the shape of the optical element 4 </ b> H constituting the first mirror 31 in the projection optical system 3. In the optical element 4H of the comparative example, the first surface 41H and the second surface 42H are each planar, and the first surface 41H is parallel to the second surface 42H. In other words, the thickness of the optical element 4H is constant. Even in such an optical element 4H, the light incident on the optical element 4H through the first surface 41H is reflected by the second surface 42H and emitted from the optical element 4H through the first surface 41H (FIG. 5). (See optical path P1). However, when Fresnel reflection occurs on the first surface 41H, an optical path P2 that is substantially parallel to the optical path P1 may occur as shown in FIG. Similarly, when multiple reflection occurs on the first surface 41H and the second surface 42H, an optical path P3 substantially parallel to the optical path P1 may be generated as shown in FIG. As a result, the light reflected by Fresnel on the first surface 41H and the light reflected by the first surface 41H and the second surface 42H are reflected by the second mirror 32 and projected onto the object (windshield 101). And may produce a double image.

  On the other hand, in the display device 10 according to the present embodiment, as shown in FIG. 1, the light that is Fresnel reflected by the first surface 41 and the light that is multiple-reflected by the first surface 41 and the second surface 42 are reflected. It is possible to deflect from the second mirror 32. In short, the optical element 4 has a configuration in which the thickness is not constant and the thickness changes in at least one of the vertical direction and the horizontal direction of the image. Therefore, due to refraction of light on the first surface 41 or reflection of light between the first surface 41 and the second surface 42, an optical path P1 and an optical path P2 of light reflected by the Fresnel on the first surface 41, The optical path P3 of the light that is multiple-reflected by the first surface 41 and the second surface 42 is scattered. As described above, the optical element 4 enters the optical element 4 through the first surface 41, reflects off the second surface 42, and directs the light (optical path P <b> 1) emitted through the first surface 41 toward the second mirror 32. However, other light (optical paths P2, P3) can be deflected from the second mirror 32. As a result, compared to the comparative example, the probability that the light reflected by the first surface 41 and the light multiple-reflected by the first surface 41 and the second surface 42 are projected onto the object (windshield 101). And the incidence of double images can be reduced.

(3) Modification Example 1 is only one of various embodiments of the present disclosure. The first embodiment can be variously modified according to the design or the like as long as the object of the present disclosure can be achieved. Furthermore, the aspect according to the first embodiment is not limited to being embodied by a single display device. For example, the aspect according to the first embodiment may be embodied by a system, a display device control method, a computer program, or a storage medium storing the program. The modifications described below can be applied in appropriate combinations.

(3.1) First Modification A display device 10 according to a first modification is different from the display device 10 according to the first embodiment in the shape of an optical element made of a back reflector. 6A to 6D show the optical elements (4A to 4D) of the display device 10 according to the first modification.

  6A, in the optical element 4A, the first surface 41A and the second surface 42A are each planar, and the first surface 41A is inclined with respect to the second surface 42A. In other words, the thickness of the optical element 4A in the opposing direction of the first surface 41A and the second surface 42A is not constant but varies in the vertical direction of the image. Further, the optical element 4A may be an optical element having the same shape as the optical element 4H of the comparative example shown in FIG. 5 in which the planar first surface 41A and the second surface 42A are arranged in parallel.

  In the example of FIG. 6B, the first surface 41B and the second surface 42B of the optical element 4B are curved, and the first surface 41B is inclined with respect to the second surface 42B. In other words, the thickness of the optical element 4B in the opposing direction of the first surface 41B and the second surface 42B is not constant but varies in the vertical direction of the image. The curvature of the first surface 41B and the curvature of the second surface 42B are the same. This optical element 4B is an optical element having the same shape as that obtained by replacing the first surface 41 of the optical element 4 in the first embodiment with a virtual curved surface S1.

  In the example of FIG. 6C, in the optical element 4C, the first surface 41C and the second surface 42C are curved, and the thickness of the optical element 4C in the opposing direction of the first surface 41C and the second surface 42C is constant. It is. In other words, the first surface 41C is parallel to the second surface 42C.

  In the example of FIG. 6D, as in FIG. 6B, the optical element 4D includes a first surface 41D and a second surface 42D that are curved, and the first surface 41D is inclined with respect to the second surface 42D. Yes. However, the curvature of the first surface 41D is different from the curvature of the second surface 42D, and the curvature of the first surface 41D is smaller than the curvature of the second surface 42D. That is, the first surface 41D has a shape in which the convex component is weakened over the entire area. Even in this configuration, the base material 40D of the optical element 4D is thicker at the outer peripheral portion than the central portion, and thus acts as a concave lens, and aberration may be reduced.

(3.2) Second Modification A display device 10E according to a second modification is different from the display device 10 according to the first embodiment in the arrangement of the projection optical system 3, as shown in FIG. That is, in the first embodiment, the image forming unit 2, the first mirror 31, and the second mirror 32 are arranged so as to be aligned in the vertical plane, whereas in the second modification, the image forming unit 2 is arranged. The first mirror 31E and the second mirror 32E are arranged in a horizontal plane. Here, the “horizontal plane” is a plane including the horizontal direction (horizontal direction) of the projection image and the traveling direction (optical axis) of light.

  Also in the second modified example, as in the first embodiment, the projection optical system 3 first reflects the output light of the image forming unit 2 by the first mirror 31E, and further reflects by the second mirror 32E. It emits toward (windshield 101). Even in this case, the optical element 4E enters the optical element 4E through the first surface 41E, reflects off the second surface 42E, and directs the light (optical path P1) emitted through the first surface 41E toward the second mirror 32E. However, other light (optical paths P2 and P3) is diverted from the second mirror 32E.

(3.3) Third Modification As shown in FIG. 8, the display device 10 </ b> F according to the third modification is an embodiment in that not only the first mirror 31 but also the second mirror 32 is a back surface reflecting mirror. 1 is different from the display device 10 according to FIG.

  In other words, in the third modification, the second mirror 32 includes the first surface 41F and the second surface 42F, and includes the optical element 4F that reflects light on the second surface 42F. The first surface 41F is a surface facing the first mirror 31 side, that is, the “surface” of the second mirror 32. The second surface 42 </ b> F is a surface facing away from the first mirror 31, that is, the “back surface” of the second mirror 32. In the example of FIG. 8, the optical element 4H used as the first mirror 31 is an optical element having the same shape as the optical element 4H of the comparative example shown in FIG.

  The optical element 4F as the second mirror 32 has a reflective film 43 formed on the second surface 42F. The optical element 4F is configured to reflect the output light of the image forming unit 2 incident on the optical element 4F through the first surface 41F by the second surface 42F and to emit the light from the optical element 4F through the first surface 41F. Yes. Here, the output light of the image forming unit 2 is indirectly incident on the first surface 41 </ b> F of the optical element 4 </ b> F by being reflected by the first mirror 31.

  Here, in the optical element 4 </ b> F as the second mirror 32, the first surface 41 </ b> F and the second surface 42 </ b> F are curved surfaces (concave surfaces) that are convex on the side opposite to the first mirror 31, and The first surface 41F is inclined with respect to the second surface 42F. In other words, the thickness of the optical element 4F in the opposing direction of the first surface 41F and the second surface 42F is not constant but varies in the vertical direction of the image.

  As a result, the optical element 4F enters the optical element 4F through the first surface 41F, reflects off the second surface 42F, and directs the light (optical path P1) emitted through the first surface 41F toward the opening 103. Other light (optical paths P <b> 2 and P <b> 3) can be diverted from the opening 103. That is, the light reflected by the second mirror 32 is projected from the opening 103 of the dashboard 102 onto the windshield 101, but the light reflected by the first surface 41F and the first surface 41F and the second surface. The light multiple-reflected by 42F is blocked by the dashboard 102.

  Further, with respect to the second mirror 32, the positive power of the second mirror 32 can be increased by making the curvature of the first surface 41F larger than the curvature of the second surface 42F. Can be realized.

(3.4) Other Modifications Modifications other than the first modification to the third modification of the first embodiment are listed below.

  The image forming unit 2 is not limited to the configuration having the liquid crystal panel 21 and the light source device 22. For example, the image forming unit 2 may be configured to draw an image on a screen by scanning a diffuse transmission screen with laser light from behind the screen. The image forming unit 2 may be configured to project an image with a projector from behind the screen, for example, on a diffuse transmission screen. The image forming unit 2 may be a self-luminous display panel such as an OLED (Organic Light Emitting Diode).

  The reflective film 43 of the optical element 4 is not limited to coating, and may be formed by, for example, film sticking, plating, or vapor deposition on the second surface 42.

  Further, the first surface 41 and the second surface 42 in the optical element 4 may be surfaces facing different directions, and it is not essential that the first surface 41 and the second surface 42 are separated, For example, the first surface 41 and the second surface 42 may be continuously connected by a curved surface.

  The thickness of the optical element 4 in the opposing direction of the first surface 41 and the second surface 42 is not limited to a configuration that changes only in the vertical direction of the image, but changes in at least one direction of the vertical direction and the horizontal direction of the image. do it. That is, the thickness of the optical element 4 may change only in the horizontal direction of the image, or may change in both the vertical direction and the horizontal direction of the image.

  The projection optical system 3 only needs to have at least the optical element 4, and it is not essential to have the two mirrors of the first mirror 31 and the second mirror 32, but only one or three mirrors. You may have more. Furthermore, the projection optical system 3 may have optical components other than the mirror, such as a lens. The projection optical system 3 may include a relay optical system for forming an intermediate image, or may not include a relay optical system.

  Further, the optical element 4 serves as a means for reducing the incidence of double images, the light Fresnel reflected by the first surface 41 and the light multiple-reflected by the first surface 41 and the second surface 42, It is not essential to deflect from the second mirror 32. In short, it is sufficient that the light reflected by the first surface 41 and the light reflected by the first surface 41 and the second surface 42 deviate from the eye box 201 (see FIG. 2). It may be blocked by the dashboard 102 as an example.

  In addition, the display device 10 is not limited to the configuration that projects the virtual image 300 onto the target space 400 set in front of the traveling direction of the automobile 100, for example, the virtual image on the side, rear, or upward in the traveling direction of the automobile 100. 300 may be projected.

  The display device 10 is not limited to the head-up display used in the automobile 100, and can be applied to a mobile body other than the automobile 100 such as a motorcycle, a train, an aircraft, a construction machine, and a ship. Furthermore, the display device 10 is not limited to a mobile object, and may be used in an amusement facility, for example, as a wearable terminal such as a head mounted display (HMD), a medical facility, or a stationary device. May be. The display device 10 may be, for example, a projector, a prompter, or the like, or may be used as an electronic viewfinder or the like by being incorporated in a device such as a digital camera.

(Embodiment 2)
As shown in FIG. 9, the display device 10 </ b> G according to the present embodiment is different from the display device 10 according to the first embodiment in the configuration of the projection optical system 3. Hereinafter, the same configurations as those of the first embodiment are denoted by common reference numerals, and description thereof is omitted as appropriate.

  In the present embodiment, the optical element 4G used as the first mirror 31 is configured to reflect the output light of the image forming unit 2 using total reflection on the second surface 42G. However, “total reflection” here refers to a light reflection phenomenon that occurs when the incident angle of light with respect to the second surface 42G is greater than or equal to the critical angle. The critical angle is an angle determined by the refractive index of the base material 40G of the optical element 4G and the refractive index of air. Therefore, not only the case where the light is totally reflected without passing through the second surface 42G, but also the case where a part of the light is diffusely transmitted due to the surface roughness of the second surface 42G, for example, is referred to as “total reflection”. include.

  In the present embodiment, the first surface 41G includes an entrance surface 411 and an exit surface 412 that are oriented in different directions. The base material 40G is formed in a triangular prism shape having the horizontal direction of the image as the axial direction. In other words, the base material 40G is formed in a triangular shape when viewed from the side. The three side surfaces of the base material 40G constitute an entrance surface 411, an exit surface 412, and a second surface 42G, respectively. The incident surface 411 of the first surface 41G is a surface facing the image forming unit 2 side, and the exit surface 412 of the first surface 41G is a surface facing the second mirror 32 side. The second surface 42G is a surface facing away from the image forming unit 2 and the second mirror 32, that is, the “back surface” of the first mirror 31. In the present embodiment, the reflective film 43 (see FIG. 4B) as in the first embodiment is not formed on the second surface 42G.

  The optical element 4G totally reflects the image forming unit 2 output light incident on the optical element 4G through the incident surface 411 of the first surface 41G on the second surface 42G, and passes through the emission surface 412 of the first surface 41G. It is comprised so that it may radiate | emit from. That is, even in the optical element 4G of the present embodiment, unlike the surface reflector, most of the light incident on the first surface 41G is transmitted through the first surface 41G, unlike the first embodiment. Reflected by the second surface 42G as a reflecting surface. The light reflected by the optical element 4G enters the optical element 4G through the first surface 41G (incident surface 411), is reflected by the second surface 42G, and is emitted through the first surface 41G (exit surface 412). In the optical path P1.

  According to the configuration of the present embodiment, since the optical element 4G uses total reflection, the attenuation of light on the reflection surface (second surface 42G) can be reduced, and light can be reflected with high efficiency. Moreover, since the reflective film 43 is unnecessary on the second surface 42G, it is possible to keep the manufacturing cost low.

  However, in the display device 10G according to the second embodiment, it is not essential that the reflective film 43 is omitted, and the reflective film 43 may be formed on the second surface 42G.

  In addition, it is not essential that the incident surface 411 and the exit surface 412 of the first surface 41G are separated. For example, the entrance surface 411 and the exit surface 412 may be continuously connected by a curved surface.

  The configuration (including the modification) of the display device 10G according to the second embodiment can be appropriately combined with the configuration of the first embodiment (including the modification).

(Summary)
As described above, the display device (10, 10E to 10H) according to the first aspect includes the image forming unit (2) and the optical elements (4, 4A to 4H). The image forming unit (2) outputs light for forming an image. The optical elements (4, 4A to 4H) project an image by reflecting the output light of the image forming unit (2). The optical elements (4, 4A to 4H) include a first surface (41, 41A to 41H) and a second surface (42, 42A to 42H) different from the first surface (41, 41A to 41H). Have. The optical elements (4, 4A to 4H) output light incident on the optical elements (4, 4A to 4H) through the first surfaces (41, 41A to 41H) on the second surfaces (42, 42A to 42H). The light is reflected and emitted from the optical element (4, 4A to 4H) through the first surface (41, 41A to 41H).

  According to this configuration, the optical element (4, 4A to 4H) is different from the surface reflecting mirror in which the reflecting film made of a metal film or the like is formed on the surface of the base material by vapor deposition or the like. The output light is taken into the optical element (4, 4A to 4H) and reflected within the optical element (4, 4A to 4H). Therefore, in the display device (10, 10E to 10H), the quality of the projected image is deteriorated due to dirt, surface roughness, scratches, or the like of the optical element (4, 4A to 4H) as compared with the case where the surface reflecting mirror is used. There is an advantage that can be reduced.

  In the display device (10, 10E to 10H) according to the second aspect, in the first aspect, the optical in the opposing direction of the first surface (41, 41A to 41H) and the second surface (42, 42A to 42H). The thickness of the element (4, 4A to 4H) changes in at least one of the vertical direction and the horizontal direction of the image.

  According to this configuration, the light reflected by the first surface (41, 41A to 41H) and the multiple reflections by the first surface (41, 41A to 41H) and the second surface (42, 42A to 42H). The probability that light is projected onto the object is reduced, and the occurrence rate of double images can be reduced.

  In the display device (10, 10E to 10H) according to the third aspect, in the first or second aspect, the first surface (41, 41A to 41H) and the second surface (42, 42A to 42H) are mutually The shape is different.

  According to this configuration, it is possible to reduce aberration by combining the first surface (41, 41A to 41H) and the second surface (42, 42A to 42H).

  In the display device (10, 10E to 10H) according to the fourth aspect, in any one of the first to third aspects, the optical element (4, 4A to 4H) is disposed on the second surface (42, 42A to 42H). It further has a formed reflective film (43).

  According to this configuration, even when the reflective film (43) is formed, for example, by applying a metal material, a sufficient reflectance can be realized.

  In the display device (10, 10E to 10H) according to the fifth aspect, in any one of the first to fourth aspects, the first surface (41, 41A to 41H) includes an incident surface (411) and an orientation surface different from each other. Including an exit surface (412). The optical element (4, 4A to 4H) outputs the output light incident on the optical element (4, 4A to 4H) through the incident surface (411) of the first surface (41, 41A to 41H) to the second surface (42, 42A to 42H) and totally reflected from the optical element (4, 4A to 4H) through the emission surface (412) of the first surface (41, 41A to 41H).

  According to this configuration, since the optical elements (4, 4A to 4H) use total reflection, attenuation of light on the second surfaces (42, 42A to 42H) serving as the reflection surface can be reduced, and high efficiency is achieved. Can reflect light.

  The optical elements (4, 4A to 4H) according to the sixth aspect are elements that project an image by reflecting the output light from the image forming section (2) that outputs light for forming an image. The optical elements (4, 4A to 4H) include a first surface (41, 41A to 41H) and a second surface (42, 42A to 42H) different from the first surface (41, 41A to 41H). The base material (40, 40D, 40G) which has is provided. The optical elements (4, 4A to 4H) reflect the output light incident on the base material through the first surface (41, 41A to 41H) by the second surface (42, 42A to 42H), and the first surface ( 41, 41A to 41H) and the substrate (40, 40D, 40G).

  According to this configuration, the optical element (4, 4A to 4H) is different from the surface reflecting mirror in which the reflecting film made of a metal film or the like is formed on the surface of the base material by vapor deposition or the like. The output light is taken into the optical element (4, 4A to 4H) and reflected within the optical element (4, 4A to 4H). Therefore, in the display device (10, 10E to 10H), the quality of the projected image is deteriorated due to dirt, surface roughness, scratches, or the like of the optical element (4, 4A to 4H) as compared with the case where the surface reflecting mirror is used. There is an advantage that can be reduced.

  The mobile body (for example, automobile 100) according to the seventh aspect includes a display device (10, 10E to 10H) according to any one of the first to fifth aspects, and a reflective member (for example, windshield 101) on which an image is projected. And comprising.

  According to this configuration, the optical element (4, 4A to 4H) is different from the surface reflecting mirror in which the reflecting film made of a metal film or the like is formed on the surface of the base material by vapor deposition or the like. The output light is taken into the optical element (4, 4A to 4H) and reflected within the optical element (4, 4A to 4H). Therefore, in the display device (10, 10E to 10H), the quality of the projected image is deteriorated due to dirt, surface roughness, scratches, or the like of the optical element (4, 4A to 4H) as compared with the case where the surface reflecting mirror is used. There is an advantage that can be reduced.

  Moreover, the 2nd-5th aspect is not an essential structure for a display apparatus (10, 10E-10H), and can be abbreviate | omitted suitably.

  The drawings shown in the above embodiments are merely conceptual diagrams for explaining an example of the display device 10, and the shape, size, positional relationship, and the like of each part are appropriately different from those of the actual display device 10.

  The present disclosure is applicable to an apparatus that projects an image via an optical element that reflects light. Specifically, the present disclosure can be applied to a head-up display, a head-mounted display, a medical facility, a projector, a prompter, an electronic viewfinder, and the like.

10, 10E to 10H Display device 2 Image forming unit 4, 4A to 4H Optical element 40, 40D, 40G Base material 41, 41A to 41H First surface 42, 42A to 42H Second surface 43 Reflective film 100 Automobile (moving body)
101 Windshield (reflective member)
411 entrance surface 412 exit surface

Claims (7)

An image forming unit that outputs light for forming an image;
An optical element that projects the image by reflecting the output light of the image forming unit,
The optical element has a first surface and a second surface different from the first surface,
The display device is configured to reflect the output light incident on the optical element through the first surface by the second surface and emit the output light from the optical element through the first surface. The display device according to claim 1, wherein a thickness of the optical element in a facing direction between the first surface and the second surface changes in at least one of a vertical direction and a horizontal direction of the image. The display device according to claim 1, wherein the first surface and the second surface have different shapes. The display device according to claim 1, wherein the optical element further includes a reflective film formed on the second surface. The first surface includes an entrance surface and an exit surface in different directions,
The optical element totally reflects the output light incident on the optical element through the incident surface of the first surface on the second surface and emits the light from the optical element through the emission surface of the first surface. It is comprised as follows. The display apparatus of any one of Claims 1-4. An optical element that projects the image by reflecting output light from an image forming unit that outputs light for forming an image,
A base material having a first surface and a second surface different from the first surface;
The optical element configured to reflect the output light incident on the base material through the first surface by the second surface and to exit the base material through the first surface. A display device according to any one of claims 1 to 5,
And a reflecting member on which the image is projected.

Images