JP4670367B2 - Display device - Google Patents

Description

  The present invention relates to a display device in which video information projected from an optical unit is visible as a virtual image or a real image.

  In general, a display device is known in which video information projected from an optical unit is visible as a virtual image or a real image. Such a display device is useful as an information providing device for entertainment such as games and vehicles. When the display device is used for a vehicle, for example, a display device can be installed in the instrument panel to display information such as a meter and route guidance as a virtual image or a real image. Further, if the video information projected from the optical unit is reflected by a translucent reflecting means and the video information is superimposed on the foreground as a virtual image by the reflecting means from the viewpoint, it can be used as a so-called head-up display.

  FIG. 21 is a schematic view of a vehicle equipped with a conventional head-up display. The optical unit 10 disposed in the instrument panel 50 in the vehicle interior includes a display device 20 including a liquid crystal display, a CRT, and the like, a concave mirror 30 that reflects light emitted from the display device 20, and the optical unit 10. And a dustproof cover 40 that prevents dust and dust from entering.

  In such a head-up display, the light emitted from the display device 20 is reflected by the concave mirror 30, passes through the dust-proof cover 40 installed in the opening provided in the upper part of the optical unit 10, and then passes through the windshield 60. Incident on the inner surface. Then, the incident light is reflected by the inner surface of the windshield 60, so that display information is presented as a virtual image 61 formed in front of the vehicle with respect to the windshield 60. The concave mirror 30 is installed inside the optical unit 10 in a state where the concave mirror 30 is inclined at an angle θ with respect to the vertical direction.

  FIG. 22 is a diagram showing an optical path of light emitted from the display 20 shown in FIG. As shown in FIG. 22, the light emitted from the center B1 point of the display device 20 is reflected at the point B2 of the concave mirror 30, passes through the point B4 of the dust cover 40, and is reflected at the point B5 of the windshield 60. To view 70. Here, a point B3 shown in FIG. 22 is a point corresponding to a virtual image by the concave mirror 30, and a point B6 is a point corresponding to a virtual image by the windshield 60, that is, a virtual image viewed from the viewpoint 70. In addition, the path | route of the light radiate | emitted from edge part A1, C1 of the indicator 20 is also illustrated similarly.

  In the arrangement state as described above, if the virtual image 61 displayed in front of the vehicle is the width d6 (distance between A6 and C6), the optical path width at the concave mirror 30 is d2 (distance between A2 and C2). The optical path width is required by d1 (distance between A1 and C1). Therefore, when trying to enlarge the size of the virtual image 61 displayed in front of the vehicle, the optical path width d2 at the concave mirror 30 and the optical path width d1 at the display 20 increase, and as a result, the size of the optical unit 10 increases. .

  However, in order to facilitate the mounting of the optical unit 10 on the instrument panel 50, the optical unit 10 needs to be small.

  Therefore, in Japanese Patent Application Laid-Open No. 6-55957, the optical unit includes a display and N (for example, three) deflecting means, and the optical path between the display and the first deflecting means and the second There is disclosed a head-up display arranged so that an optical path between the first and third deflecting means intersects in a horizontal plane.

  In this head-up display, since a large number of deflecting means are provided in the plane of the optical unit, the optical path length is increased. However, since the optical path width in the deflecting means immediately before the light is emitted from the optical unit eventually needs an optical path width equal to d2 shown in FIG. 22, even if the optical path length can be obtained, The vertical size cannot be reduced. In addition, since a plurality of deflecting means are used, it is not always sufficient to meet the demand for downsizing in consideration of these arrangement locations.

  Japanese Laid-Open Patent Publication No. 9-318906 discloses a head-up display that is made compact by molding a resin or glass transparent member into a block shape so that light reciprocates in the block. However, also in this head-up display, the optical path width in the deflecting means immediately before the light is emitted from the optical unit eventually requires an optical path width equal to d2 shown in FIG. Furthermore, it is very difficult to uniformly mold this block without optical stagnation.

  Japanese Patent Application Laid-Open No. 2004-20605 discloses a head-up display in which a prism sheet is provided between a display and a reflecting means such as a windshield to reduce the optical path width in the optical unit. However, the display image is colored due to the chromatic aberration generated by the prism sheet, and the display quality is remarkably deteriorated. This phenomenon becomes more prominent as the angle of refraction by the prism sheet is increased.

  Furthermore, Japanese Patent Laid-Open No. 2000-180967 also includes a total reflection prism sheet used for a projection display device. This apparatus forms an image projected from a projector as a real image on a projection screen made of a total reflection prism sheet. However, when this total reflection prism sheet is used in a virtual image display or when a real image is formed on a space rather than on a screen, an apparent image formation spot becomes large and the image may be blurred and visibility may deteriorate.

  In view of the above, the present invention has an object to provide a display device with high visibility while reducing the size of an optical unit.

  In order to achieve the above object, according to the first aspect of the present invention, when the light projected from the display (20) is incident on the sheet-like optical element (80), the traveling direction of the light is the minute prism (82). It is characterized in that it is bent and emitted by.

  As described above, the optical unit includes the sheet-like optical element provided with the minute prism. Thereby, since the optical path of the light projected from the display can be bent, the degree of freedom in handling the optical system arrangement can be increased. Further, since the sheet-like optical element is thin and the optical path width can be narrowed, the display device can be miniaturized. Furthermore, since the microprism includes a total reflection surface, it is possible to reduce the energy loss of the light reflected in the microprism and increase the luminance, thereby improving the visibility of the image.

In the first aspect of the present invention, the incident angle Θin of the light incident on the sheet-like optical element after the image light projected from the display is reflected by the concave mirror is emitted through the sheet-like optical element. It is characterized by being larger than the emission angle Θout. Thus, Θin> Θout. Thereby, the length of the height component of the image emitted from the display, that is, the optical path width can be reduced by cos (Θin) / cos (Θout), and the optical unit can be miniaturized. On the other hand, the length in the height direction of the virtual image displayed in front of the user can be enlarged by cos (Θout) / cos (Θin). Thereby, it is possible to display a larger screen while maintaining the size of the optical unit.

Further, the invention described in claim 1 is characterized in that the imaging position of the virtual image or the real image is a place other than the sheet-like optical element. Thus, the imaging position of the virtual image or real image is set to a place other than the sheet-like optical element. As a result, the display image can be shown to the user as if it is floating in the space. For this reason, it is possible to realize an effective display that can be superimposed on the foreground object, or that only the display can be seen in an empty place.

In the first aspect of the invention, in the microprism, the incident angle of the light with respect to the incident surface is equal to the outgoing angle of the light with respect to the outgoing surface, or in the prism sheet, the incident angle and the outgoing angle of the light with respect to the incident surface. The light emission angle with respect to the surface is perpendicular.

In this way, the incident angle and the outgoing angle of light are set. Thereby, it is possible to improve the image quality such as coloring due to the chromatic aberration of the minute prism. In addition, since the reflection at the interface of the minute prisms can be suppressed, the brightness can be increased.
In the first aspect of the present invention, the video information projected from the optical unit is a virtual image, and the even number of total reflection surfaces are included in the microprisms of the prism sheet, or the projection is performed from the optical unit. The video information to be displayed is a real image, and the micro prisms of the prism sheet include an odd number of total reflection surfaces. In this way, when displaying a virtual image or a real image, the number of total reflection surfaces included in the minute prism is set. As a result, a macroscopic image formed by each adjacent microprism, that is, a macro image can be formed as a virtual image or a real image.
Further, in the first aspect of the invention, when the pitch of the plurality of micro prisms is p and the optical path length from the sheet-like optical element to the place where it is visually recognized is L1, arctan (p / L1) is less than the eye resolution. Or, if the size of the imaging spot by a plurality of micro prisms is S and the optical path length from the imaging spot to the place where it is visually recognized is L2, arctan (S / L2) is below the eye resolution, It is characterized by. In this way, each value is set to be less than the resolution of the human eye. Thereby, since the stripes of the minute prism are not visually recognized, the image quality can be improved. In addition, since the sharpness of the display image is increased, visibility can be improved.
According to the first aspect of the present invention, when the distance from the light spot on the display to the minute prism provided in the prism sheet is a and M = cos (Θout) / cos (Θin), the focal length f of the prism Ri is f = [M / (M- 1)] · a der, further characterized in that at least one micro-prism surface is a curved surface. Thereby, the position of the macro image and the microscopic image formed by each adjacent micro prism, that is, the position of the micro image coincides with each other, and the sharpness of the display image increases, so that the visibility can be improved. Further, even if the micro prism surface is a curved surface, the macro image formation and the micro image formation position coincide with each other, and the visibility of the display image is increased, so that the visibility can be improved.

In the invention according to claim 2 , on the incident surface to the sheet-like optical element, on the surface of the sheet-like optical element, parallel to the surface of the vector and on the exit surface to the sheet-like optical element, the sheet-like optical It is characterized in that the signs of the vectors parallel to the surface of the element are opposite to each other.

  Thus, the sign of the light vector incident on the sheet-like optical element and the sign of the emitted light vector are opposite to each other. Thereby, in an optical unit, the freedom degree of management of optical system arrangement | positioning can be improved.

The invention according to claim 3 is characterized in that the microprisms are provided on the front and back surfaces of the prism sheet in the sheet-like optical element. Thus, the micro prisms are provided on both the front and back surfaces of the prism sheet. Thereby, the freedom degree of the setting of the incident angle of light and an emission angle with respect to a sheet-like optical element can be improved.

The invention according to claim 4 is characterized in that the traveling direction of light passing through the inside of the sheet-like optical element is the normal direction of the sheet-like optical element. In this way, the light passing through the inside of the sheet-like optical element is set in the normal direction of the sheet-like optical element. Accordingly, for example, when a plurality of prism sheets are used, the upper and lower prism sheets can be easily aligned. In addition, it is possible to reduce image quality degradation when a lens such as a lenticular lens or a Fresnel lens is sandwiched between the upper and lower prism sheets.

The invention according to claim 5 is characterized in that the pitch of the plurality of micro prisms is set so that arctan (S / L2) is equal to or less than the resolution of the eye. In this way, the pitch of the minute prisms is set. Thereby, the sharpness of the display image is increased, and thus visibility can be improved. Moreover, since the pitch of each micro prism is only set small, an increase in cost can be suppressed.

In the invention described in claim 6 , the sheet-like optical element includes at least two prism sheets, a lenticular lens (83) is provided between the two prism sheets, and the lenticular lens is provided on the prism sheet. The microlens array is formed in parallel with the microprism, or a microlens array is formed between the two prism sheets.

  Thus, a lenticular lens or a microarray lens is provided between the two prism sheets. By providing a lenticular lens between the two prism sheets, the positions of the macro image formation and the micro image formation coincide with each other, and the sharpness of the display image increases, so that the visibility can be improved. Further, by providing the microlens array between the two prism sheets, the positions of the macro image formation and the micro image formation coincide, and astigmatism can be suppressed, so that the image quality can be improved.

According to a seventh aspect of the invention, the microlens array has a lenticular lens shape in the cross-sectional direction of the prism sheet, and a linear Fresnel lens shape in a direction perpendicular to the cross-sectional direction. It is said. In this way, the shape of the microlens array is set. Thereby, the positions of the macro image formation and the micro image formation coincide with each other and the astigmatism can be suppressed, so that the image quality can be improved.

The invention according to claim 8 is characterized in that the sheet-like optical element includes at least one Fresnel lens and two prism sheets, and the Fresnel lens is disposed between the two prism sheets.

  As described above, the sheet-like optical element includes the Fresnel lens. Thereby, since the Fresnel lens has a magnifying action, a large screen image can be formed. In addition, the integrated structure can reduce the cost.

The invention according to claim 9 is characterized in that the optical unit includes an optical element having a vertical magnification smaller than the horizontal magnification. Thereby, since astigmatism can be suppressed, image quality can be improved.

The invention according to claim 10 is characterized in that the optical element is a mirror or a lens. Thereby, since astigmatism can be suppressed, image quality can be improved.

The invention according to claim 11 is characterized in that the prism sheet is arcuate, or the apex angle of the prism sheet differs depending on the location. As a result, the optical conditions are optimized depending on the location of the prism sheet, so that the image quality can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Needless to say, the embodiments of the present invention are not limited to the following and can take various forms as long as they belong to the technical scope of the present invention. In the drawings shown below, the same components as those shown in FIGS. 21 and 22 are denoted by the same reference numerals.

  FIG. 1 is a diagram illustrating a state in which the display device according to the first embodiment of the present invention is mounted on a vehicle as a head-up display. As shown in FIG. 1, the head-up display has an optical unit 10. The optical unit 10 includes a display 20, a concave mirror 30, and a sheet-like optical element 80. In addition, a dustproof cover 40 made of, for example, a transparent resin is attached to the opening at the top of the optical unit 10. Such an optical unit 10 is housed inside the instrument panel 50.

  The display 20 displays an image. Each image output from the display 20 is applied to the concave mirror 30. For example, a liquid crystal display (LCD) is employed as the display device 20.

  The concave mirror 30 enlarges an image directly incident from the display device 20 and guides the image light of the enlarged image to the windshield 60 through a sheet-like optical element 80 and a dustproof cover 40 described later. Here, the length (optical path width) of the concave mirror 30 in the height direction is d, and the concave mirror 30 is installed with an inclination of θ with respect to the vertical direction.

  The sheet-like optical element 80 emits light with the traveling direction of incident light bent. A specific configuration of the sheet-like optical element 80 having such a function is shown in FIG. FIG. 2 is a perspective view of the sheet-like optical element 80 shown in FIG. As shown in FIG. 2, in the present embodiment, the sheet-like optical element 80 includes, for example, one prism sheet 81 and a large number of microprisms 82 provided on the surface of the prism sheet 81. It is configured.

  The prism sheet 81 is a transparent substrate such as plastic or glass. Examples of the plastic material include acrylic and polycarbonate. The microprisms 82 reflect light incident on the inside at the end face, and a plurality of microprisms 82 are provided on the front and back surfaces of the prism sheet 81. Such a microprism 82 is formed as a projection by cutting the front and back surfaces of the prism sheet into a sawtooth shape, and each of these projections acts as a microprism 82.

  Next, the optical action of the sheet-like optical element 80 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the sheet-like optical element 80 shown in FIG. As shown in FIG. 3, the prism sheet is configured by combining a plurality of microprisms 82 on the upper and lower surfaces of the transparent substrate. The light reflected by the concave mirror 30 enters the microprism 80a of the prism sheet at an incident angle Θin. At this time, the light enters from the surface A-1 on the concave mirror 30 side in the micro prism 82, is totally reflected by the surface A-2 on the opposite side to the surface A-1, and then passes through the prism sheet 81 to provide a dust-proof cover. In the 40-side micro prism 82, the light is totally reflected by the surface B-2 on the concave mirror 30 side and emitted from the surface B-1 on the opposite side to the surface B-2. This light is emitted at an emission angle Θout with respect to the vertical direction of the prism sheet 81.

In the prism sheet 81, the angle of the surface A-1 of the micro prism 82 with respect to the vertical direction is α _A1 , the angle of the surface A-2 is α _A2 , the angle of the surface B-1 is α _B1 , and the angle of the surface B-2 is α _B2. The incident angle of light with respect to the surface A-1 is φin, and the outgoing angle of light with respect to the surface B-1 is φout. Further, in the prism sheet 81, when the angle of light with respect to the vertical direction is γ and the refractive index of the prism sheet 81 is n, the following relationship is established.

α _A1 = 90−Θin−φin
α _A2 = (1/2) · [90−α _A1 −arcsin (sin φin / n) + γ]
α _B1 = 90−Θout−φout
α _B2 = (1/2) · [90−α _B1 -arcsin (sin φout / n) + γ]
The incident angle α _A1 to the surface A-1 and the exit angle α _B1 from the surface B-1 are not necessarily equal.

  Surface A-2 and surface B-2 are total reflection surfaces, and the following relationship is established.

β _A > arcsin (1 / n)
β _B > arcsin (1 / n)
If α _A1 , α _A2 , α _B1 , and α _B2 are set so as to have the above relationship, the light enters the prism sheet 81 at the incident angle Θin and exits at the exit angle Θout. It can be bent. However, you may change the angle of each surface A-1, A-2, B-1, B-2 within the sheet-like optical element 80. FIG.

Based on the above, it will be described with reference to FIG. 4 that the optical unit 10 can be miniaturized by using the sheet-like optical element 80. FIG. 4 is a diagram illustrating an optical path of light emitted from the display device 20. Light from the center B1 point of the display 20 is reflected at the point B2 of the concave mirror 30, refracted at the point B8 of the sheet-like optical element 80, transmitted through the point B4 of the dust cover 40, and reflected at the point B5 of the windshield 60. Then proceed to the viewpoint 70 direction. Here, point B3 is a point corresponding to a virtual image by the concave mirror 30, and point B6 is a point corresponding to a virtual image by the windshield 60, that is, a virtual image viewed from the viewpoint 70. The light path from the end portions A1 and C1 of the display device 20 is also shown in FIG. The distance between A1 and C1 is the optical path width d1.

  If the width of the virtual image 61 displayed in front of the driver is d6 (distance between A6 and C6), the optical path widths in the windshield 60 and the dustproof cover 40 are equal. However, if Θin> Θout, the required optical path width d2 (distance between A2 and C2) in the concave mirror 30 is reduced by cos (Θin) / cos (Θout). Due to this effect, the optical unit 10 can be miniaturized. Conversely, the width d6 of the virtual image 61 displayed in front of the driver is enlarged by cos (Θout) / cos (Θin). Thereby, it is possible to display a larger screen while maintaining the size of the optical unit 10.

  Here, when the sheet-like optical element 80 having the stripe-like microstructure formed by the minute prism 82 is used, the stripe shape may be observed in a stripe shape, which may deteriorate visibility. . Therefore, it is desirable that the stripe pitch in the microprism 82 is small. Specifically, if the pitch of each microprism 82 is p, and the optical path length from the position of the observer's (driver's) eye to the sheet-like optical element 80 is L, the angle arctan (p / L) formed is It only needs to be smaller than the resolution. In general, since the resolution of the eye is arctan (1 / 7.4 / 254) = 0.030 °, arctan (p / L) <0.030 ° may be satisfied.

  Further, when the sheet-like optical element 80 is used, an apparent imaging spot may become large and the image may be blurred to deteriorate visibility. This point will be described with reference to FIG.

  FIG. 5 is a schematic view showing the display 20 and the sheet-like optical element 80 in the optical unit 10. As shown in FIG. 5, light emitted from a certain light spot (for example, one pixel) on the display 20 enters each microprism 82, and the optical path shown in FIG. 3 within the sheet-like optical element 80. Are emitted from each microprism 82.

  Here, it is assumed that the distance a from the light spot on the display device 20 to the microprisms 82 is very large compared to the pitch p of each microprism 82. Further, the spread angle of the light incident on each microprism 82 is Δψ, and the angle formed by the light incident on the adjacent microprism 82 is Δξ. Since the light incident on each microprism 82 is only totally reflected inside each microprism 82, the size of the image is neither enlarged nor reduced. Therefore, a virtual image of the light spot on the display 20 by each microprism 82 is formed at a distance a from the microprism 82. This image formation by each micro prism 82 is called micro image formation.

  At this time, the spread of the light of the micro image formed by each microprism 82 remains Δψ. Further, since the angle Δξ formed by the light incident on the adjacent microprisms 82 is also maintained without change, the macroscopic appearance image of each adjacent microprism 82 is M = cos (Θout) / cos (Θin). Only formed far away. The image formed in this way is called macro image formation.

  When the observer observes a virtual image of the light spot on the display 20 by the sheet-like optical element 80, a macro image is observed instead of a micro image. However, since the spread angle of light for micro imaging by each microprism 82 is Δψ, the spot size S at the position of macro imaging is S = (M−1) × a × Δψ. This spot size S is larger than the size of the light spot of the display device 20 and there are many light spots on the display device 20, so that the spot size S that has become larger due to the light spread angle Δψ overlaps. The image appears blurred.

  In order to reduce the spot size S, the pitch p of each microprism 82 of the sheet-like optical element 80 may be reduced. FIG. 6 is a schematic diagram showing the display 20 and the sheet-like optical element 80 in the optical unit 10 and corresponds to a case where the pitch of each microprism 82 shown in FIG. 5 is made smaller. As shown in FIG. 6, when the pitch p is narrowed, the spread angle of light incident on each microprism 82, that is, the spread angle Δψ of light of micro imaging by each microprism 82 is reduced. For this reason, the spot size S of the formed macro image is reduced. Desirably, the angle formed by the observer (driver) 's eyes with this spot size S or an enlarged (reduced) image of the spot size S formed by the optical system after the light passes through the sheet-like optical element 80. It may be 0.030 or less.

  Next, the operation of the head-up display shown in FIG. 1 will be described. First, the light emitted from the display device 20 is reflected by the concave mirror 30 to form a virtual image 31. Subsequently, the light enters the sheet-like optical element 80 and its traveling direction is bent to form a virtual image 90. Therefore, the virtual image 90 does not exist on the sheet-like optical element 80. The light that has passed through the sheet-like optical element 80 and the dust-proof cover 40 is reflected by the windshield 60 so that display information (video information) is presented as a virtual image 61 formed forward by the windshield 60.

  As described above, the present embodiment is characterized in that the optical unit 10 includes the sheet-like optical element 80 provided with the microprisms 82. Thereby, since the optical path of the light projected from the display device 20 can be bent, the degree of freedom in handling the optical system arrangement can be increased. Further, since the sheet-like optical element 80 can be thinned and the optical path width can be narrowed, the size of the display device can be reduced. Further, since the microprism 82 includes a total reflection surface, the loss of light energy reflected in the microprism 82 can be reduced to increase the brightness, and the visibility of the image can be improved.

(Second Embodiment)
In the present embodiment, only different parts from the first embodiment will be described. FIG. 7 is a schematic cross-sectional view of the sheet-like optical element 80 used in the present embodiment. In FIG. 7, parts that are the same or equivalent to the sheet-like optical element 80 shown in FIG. 3 are given the same reference numerals in FIG. 7 for the sake of simplicity.

  As shown in FIG. 7, in the light guided from the concave mirror 30 to the sheet-like optical element 80, the incident angle φin to the surface A-1 of the microprism 82 and the exit angle φout from the surface B-1 are equal. In the present embodiment, the incident angle φin and the outgoing angle φout are perpendicular to the incident surface A-1 and the outgoing surface B-1. The light passing through the inside of the sheet-like optical element 80 is perpendicular to the sheet-like optical element 80, that is, perpendicular to the front or back surface of a prism sheet (not shown). Therefore, the following relationship holds.

φin = 0
φout = 0
γ = 0
Thereby, the following relationship is established.

α _A1 = 90−Θin
α _A2 = (1/2) · [90−α _A1 ]
α _B1 = 90−Θout
α _B2 = (1/2) · [90−α _B1 ]
In addition, since the surfaces A-2 and B-2 are total reflection surfaces in the microprism 82, the following relationship is established.

β _A > arcsin (1 / n)
β _B > arcsin (1 / n)
If α _A1 , α _A2 , α _B1 , and α _B2 are determined so as to satisfy the above relationship, light is incident on the surface of the prism sheet 81 at an incident angle Θin and is emitted at an output angle Θout with respect to the back surface. Thus, the optical path can be bent.

As described above, when the sheet-like optical element 80 has the structure shown in FIG. 7, the following effects can be expected in addition to the effects shown in the first embodiment. That is, since the incident angle α _A1 to the surface A-1 of the microprism 82 and the exit angle α _B1 from the surface B-1 are both equal to 0, chromatic aberration does not occur and light loss due to surface reflection is small. . In particular, chromatic aberration is not a problem when only a single wavelength is used as a light source. However, in the case of a light source including a plurality of wavelengths such as a full-color display, the display image looks colored due to chromatic aberration, and the display quality is reduced. It may deteriorate significantly. Therefore, when the sheet-like optical element 80 has the structure shown in FIG. 7, chromatic aberration does not occur and good display quality can be maintained.

(Third embodiment)
In the present embodiment, only different portions from the above embodiment will be described. FIG. 8 is a diagram illustrating an example in which the display device according to the present embodiment is applied to a vehicle as a head-up display. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  In the present embodiment, as shown in FIG. 8, in the optical unit 10, the light emitted from the display device 20 is directly guided to the sheet-like optical element 80. Here, as shown in FIG. 8, if the cross section of the optical unit 10 is defined as the YZ plane, and the incident surface and the exit surface to the sheet-like optical element 80 are on the YZ plane, the sheet-like optical element 80 is obtained. Of the vector (Y vector) parallel to the sheet-like optical element 80 and the vector (Y vector) parallel to the sheet-like optical element 80 on the exit surface to the sheet-like optical element 80. Are opposite to each other. That is, in FIG. 8, the light emitted from the display device 20 toward the vehicle front side is bent toward the driver by the sheet-like optical element 80 disposed on the vehicle front side from the display device 20.

  FIG. 9 is a schematic cross-sectional view of the sheet-like optical element 80 used in the present embodiment. In FIG. 9, the traveling direction of light is depicted in reverse in FIG. 8. As shown in FIG. 9, the light emitted from the display device 20 enters the minute prism 82 of the sheet-like optical element 80 at an incident angle Θin. At this time, in the sheet-like optical element 80, the light enters the surface A-1 of the micro prism 82 on the road surface side, is totally reflected by the surface A-2, passes through the prism sheet 81, and passes through the prism sheet 81. The light is totally reflected by the surface B-2 of the prism 82 and is emitted from the surface B-1. The light emitted from the surface B-1 of the microprism 82 is emitted to the prism sheet 81 at an emission angle Θout. Thus, in this embodiment, the signs of the Y component of the light incident vector and the Y vector of the outgoing vector with respect to the prism sheet 81 are opposite to each other.

  If the sheet-like optical element 80 as described above is used, even when another device (such as an engine) that interferes with the optical unit 10 is in the vehicle front direction of the optical unit 10, the degree of freedom in handling the optical path increases. Mounting on the vehicle becomes easy.

(Fourth embodiment)
In the present embodiment, only different parts from the first embodiment will be described. FIG. 10 is a schematic cross-sectional view of the sheet-like optical element according to the present embodiment. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  As shown in FIG. 10, in this embodiment, light is incident on the prism sheet 81 at an incident angle Θin. At this time, the light enters from the surface A-1 of the micro prism 82 on the ground side of the sheet-like optical element 80, is totally reflected by the surface A-2, passes through the prism sheet 81, and then passes through the prism sheet 81. The light is emitted from the surface B-1 to the prism sheet 81 at an emission angle Θout.

The angle of the surface A-1 with respect to the perpendicular of the prism sheet 81 is α _A1 , the angle of the surface A-2 is α _A2 , the angle of the surface B-1 is α _B1 , the incident angle with respect to the surface A-1 is φin, and the surface B− The exit angle for 1 is φout. Further, when the angle in the light direction inside the prism sheet 81 is γ and the refractive index of the prism sheet 81 is n, the following relationship is established.

α _A1 = 90−Θin−φin
α _A2 = (1/2) · [90−α _A1 −arcsin (sin φin / n) + γ]
α _B1 = 90−Θout−φout
The incident angle α _A1 to the surface A-1 and the exit angle α _B1 from the surface B-1 are not necessarily equal.

  Further, since the surface A-2 of the micro prism 82 on the ground side is a total reflection surface, the following relationship is established.

β _A > arcsin (1 / n)
If α _A1 , α _A2 , and α _B1 are determined so as to have such a relationship, it is possible to bend the optical path so that light enters the prism sheet 81 at an incident angle Θin and exits at an exit angle Θout. Become.

(Fifth embodiment)
In the present embodiment, only different parts from the second embodiment will be described. FIG. 11 is a schematic cross-sectional view of the sheet-like optical element according to the present embodiment. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  In the present embodiment, in the sheet-like optical element 80, the incident angle of light to the surface A-1 of the micro prism 82 on the ground side is equal to the emission angle of light from the surface B-1. In particular, in the structure shown in FIG. 11, the traveling direction of light is perpendicular to the incident surface A-1 and the outgoing surface B-1. Thereby, the following relationship is established.

φin = 0
φout = 0
In addition, the following relationship holds.

α _A1 = 90−Θin
α _A2 = (1/2) · [90−α _A1 + γ]
α _B1 = 90−Θout
Furthermore, since the surface A-2 is a total reflection surface, the following relationship is established.

β _A > arcsin (1 / n)
If α _A1 , α _A2 , and α _B1 are determined so as to have the above relationship, the light path can be bent so that light enters the prism sheet 81 at the incident angle Θin and exits at the exit angle Θout. It becomes.

When the structure of the sheet-like optical element 80 shown in FIG. 11 is adopted, the following effects can be expected in addition to the effects described in the second embodiment. That is, in the sheet-like optical element 80, since the incident angle α _A1 of the light to the surface A-1 and the outgoing angle α _B1 of the light from the surface B-1 are both equal to 0, no chromatic aberration occurs and the surface There is little loss of light due to reflection. In particular, chromatic aberration is not a problem when only a single wavelength is used as a light source. However, in the case of a light source including a plurality of wavelengths such as a full-color display, the display image looks colored due to chromatic aberration, and the display quality is reduced. It may deteriorate significantly. For this reason as well, if the sheet-like optical element 80 used in the present embodiment is employed, chromatic aberration does not occur in the head-up display, and good display quality can be maintained.

(Sixth embodiment)
In the present embodiment, only different portions from the above embodiment will be described. FIG. 12 is a diagram showing an example in which the display device according to the present embodiment is applied to an automobile. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  FIG. 13 is a schematic cross-sectional view of the sheet-like optical element according to the present embodiment. As shown in FIG. 13, the light enters the prism sheet 81 at an incident angle Θin. At this time, the light enters from the surface A-1 of the microprism 82 provided on the ground side of the prism sheet 81, is totally reflected by the surface A-2, passes through the prism sheet 81, and passes through the ceiling of the prism sheet 81. The light is totally reflected by the surfaces B-2 and B-3 of the microprism 82 provided on the side, and is emitted from the surface B-1 with respect to the prism sheet 81 at an emission angle Θout.

Here, the angle of the surface A-1 with respect to the perpendicular of the prism sheet 81 is α _A1 , the angle of the surface A-2 is α _A2 , the angle of the surface B-1 is α _B1 , the angle of the surface B-2 is α _B2 , the surface the angle B3 and alpha _B3, .phi.in the incident angle to the plane a-1, the exit angle with respect to the plane B-1 and .phi.out. The angle of the light direction inside the prism sheet 81 is γ, and the refractive index of the prism sheet 81 is n. In the structure of FIG. 13, the angle of light with respect to the incident surface and the exit surface of the prism sheet 81 is vertical. Further, the light passing through the sheet-like optical element 80 is perpendicular to the prism sheet 81. Therefore, the following relationship holds.

φin = 0
φout = 0
γ = 0
Thereby, the following relationship is established.

α _A1 = 90−Θin
α _A2 = (1/2) · [90−α _A1 ]
α _B1 = 90−Θout
α _B2 = α _B3 −Θout / 2
Further, since the surfaces A-2, B-2, and B-3 are total reflection surfaces, the following relationship is established.

β _A > arcsin (1 / n)
β _B1 > arcsin (1 / n)
β _B2 > arcsin (1 / n)
If α _A1 , α _A2 , α _B1 , α _B2 , and α _B3 are determined so as to have the above relationship, light is incident on the prism sheet 81 at an incident angle Θin and is emitted at an output angle Θout. The optical path can be bent.

  Next, micro imaging and macro imaging will be described. In the above embodiment, in the structure of the prism sheet 81 shown in FIG. 7, the total reflection surface of the microprism 82 is two (even number). Here, FIG. 14 and FIG. 15 are schematic views showing the display 20 and the sheet-like optical element 80 in the optical unit 10. When the total reflection surface of the micro prism 81 is two, both the micro image and the macro image are virtual images as shown in FIG.

  On the other hand, in the structure of the prism sheet 81 shown in FIG. 13, the total reflection surface of the microprism 82 is three (odd number). In such a case, as shown in FIG. 15, the micro image is a virtual image, but the macro image is a real image, and is formed on the opposite side of the display 20 with respect to the prism sheet 81.

  When an observer (driver) visually recognizes an image, macro image formation is observed. Therefore, in the configuration of the head-up display shown in FIGS. 12 and 13, the display is visually recognized as a real image. As described above, whether the macro image formed by the prism sheet 81 becomes a real image or a virtual image changes depending on the number of total reflection surfaces of the microprism 82, so it is desirable to use them properly according to the application.

(Seventh embodiment)
In the present embodiment, only different parts from the first embodiment will be described. FIG. 16 is a schematic cross-sectional view of the sheet-like optical element according to the present embodiment. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  First, in the above embodiment, as described with reference to FIG. 5, the deviation of the imaging distance between the micro image formed by each micro prism 82 and the macro image formed by the adjacent micro prism 82 is the image. It becomes blurred. Therefore, if the positions of the micro image formation and the macro image formation are matched, the spot size S at the macro image formation position is minimized. In other words, it is only necessary to enlarge the microscopic image far away.

  As shown in FIG. 16, in the present embodiment, the sheet-like optical element 80 includes a first sheet-like optical element 80a on the ground side and a second sheet-like optical element 80b on the ceiling side. Yes. Then, stripe-shaped microlenses, that is, a plurality of lenticular lenses 83 are formed on the surface where the second sheet-like optical element 80b contacts the first sheet-like optical element 80a. With this lenticular lens 83, the imaging position of the micro imaging may be enlarged by M times so as to coincide with the macro imaging. For this purpose, if the focal length of each microlens of the lenticular lens 83 is f, then f = [M / (M−1)] · a.

  FIG. 17 is a schematic diagram showing the display 20 and the sheet-like optical element 80 in the present embodiment. If the above setting is performed, as shown in FIG. 17, the positions of the micro image and the macro image coincide with each other, and an image without blur can be obtained.

(Eighth embodiment)
In the present embodiment, only different parts from the first embodiment will be described. FIG. 18 is a schematic cross-sectional view of the sheet-like optical element according to the present embodiment. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  As described in the above embodiment, a shift in image formation distance between the micro image formed by each micro prism 82 and the macro image formed by the adjacent micro prism 82 is an image blur. Therefore, if the positions of the micro image formation and the macro image formation are matched, the spot size S at the macro image formation position is minimized. In other words, it is only necessary to enlarge the microscopic image far away.

In the present embodiment, as shown in FIG. 18 , the microprism 82 has a structure in which the lens effect is provided by making the surface A-1 a curved surface. Due to this lens effect, the imaging position of the micro imaging may be enlarged by M times so as to coincide with the macro imaging. For this reason, if the focal length of the surface A-1 is f, f = [M / (M-1)] · a.

  In this way, as shown in FIG. 17, the positions of the micro image and the macro image coincide with each other, and an image without blur is obtained. In the microprism 82, it is needless to say that the surface that gives the lens effect is not limited to the surface A-1.

(Ninth embodiment)
In the present embodiment, only different parts from the first embodiment will be described. FIG. 19 is a schematic cross-sectional view of the sheet-like optical element according to the present embodiment. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  As shown in FIG. 19, in the present embodiment, the sheet-like optical element 80 includes a first sheet-like optical element 80a on the ground side, a second sheet-like optical element 80b on the ceiling side, and first and second sheets. And a Fresnel lens 84 sandwiched between the optical elements 80a and 80b. Thus, by using the Fresnel lens 84, the video on the display device 20 can be enlarged and displayed. In particular, when light passing through the sheet-like optical element 80 travels in a direction perpendicular to the sheet-like optical element 80, light enters the Fresnel lens 84 perpendicularly, so that aberration is suppressed and a good image is obtained. Obtainable.

(10th Embodiment)
In the present embodiment, only different parts from the first embodiment will be described. As described above, when the traveling direction of light is bent by the sheet-like optical element 80, the light in the incident / exit surface direction is expanded to the position of macro image formation. However, since the sheet-like optical element 80 does not have an expansion action in a direction perpendicular to the incident / exit surface, astigmatism occurs and image quality deteriorates.

  Therefore, in the present embodiment, the vertical magnification and the horizontal magnification of the reflecting mirror 30 are set to different values. In the reflecting mirror 30, if the magnification in the incident / exit plane direction is the vertical magnification, the vertical magnification is set to a value smaller than the horizontal magnification, and the total magnification by the reflecting mirror 30 and the sheet-like optical element 80 is made equal to the vertical direction and the horizontal direction. That's fine. In order to have such an action, a lens may be used instead of the reflecting mirror 30.

(Eleventh embodiment)
In the present embodiment, only different parts from the first embodiment will be described. FIG. 20 is a schematic cross-sectional view of the sheet-like optical element according to the present embodiment. FIG. 20 corresponds to a view particularly when viewing an axis parallel to the vehicle traveling direction, that is, the Y-axis direction. In the drawings used in the present embodiment, the same or equivalent parts as those shown in the drawings used in the above-described embodiment are denoted by the same reference numerals in order to simplify the description.

  In the present embodiment, in the sheet-like optical element 80 shown in FIG. 20, the YZ section has a structure as shown in FIG. The effect of the so-called lenticular lens structure in the YZ cross section shown in FIG. 16 is as shown in the seventh embodiment.

  The XZ cross-sectional shape shown in FIG. 20 has a linear Fresnel lens structure. With this shape, the XZ cross-sectional direction is imaged far away. If this imaging magnification is made equal to the magnification of macro imaging on the YZ section, astigmatism can be suppressed and image quality deterioration can be suppressed.

(Other embodiments)
In the above embodiment, the display device is mounted on a vehicle and used as a head-up display. However, the display device may be used at a place other than the vehicle.

  In the above embodiment, the sheet-like optical element 80 may be the dust cover 40. Further, the shape of the micro prism 82 may be a curved shape instead of a linear shape. In this case, since the optical conditions are optimal in the sheet-like optical element 80, the image quality may be improved.

  In the above embodiment, a microlens array may be installed between the two prism sheets 81.

It is the figure which showed the state which mounted the display apparatus which concerns on 1st Embodiment of this invention in the vehicle as a head-up display. It is a perspective view of the sheet-like optical element shown by FIG. It is sectional drawing of the sheet-like optical element shown by FIG. It is the figure which showed the optical path of the light radiate | emitted from a display. It is the schematic which showed the indicator and the sheet-like optical element in the optical unit. It is the figure which showed the state which made the pitch of each microprism shown by FIG. 5 smaller. It is a schematic sectional drawing of the sheet-like optical element used by 2nd Embodiment. It is the figure which showed the example which applied the display apparatus which concerns on 3rd Embodiment to the motor vehicle as a head-up display. It is a schematic sectional drawing of the sheet-like optical element shown by FIG. It is a schematic sectional drawing of the sheet-like optical element which concerns on 4th Embodiment. It is a schematic sectional drawing of the sheet-like optical element which concerns on 5th Embodiment. It is the figure which showed the example which applied the display apparatus which concerns on 6th Embodiment to the motor vehicle. It is a schematic sectional drawing of the sheet-like optical element shown by FIG. It is the schematic which showed the indicator and the sheet-like optical element in the optical unit. It is the schematic which showed the indicator and the sheet-like optical element in the optical unit. It is a schematic sectional drawing of the sheet-like optical element which concerns on 7th Embodiment. In 7th Embodiment, it is the schematic which showed the indicator and the sheet-like optical element. It is a schematic sectional drawing of the sheet-like optical element which concerns on 8th Embodiment. It is a schematic sectional drawing of the sheet-like optical element which concerns on 9th Embodiment. It is a schematic sectional drawing of the sheet-like optical element which concerns on 11th Embodiment. It is the schematic of the vehicle carrying the conventional head-up display. It is the figure which showed the optical path of the light radiate | emitted from the display shown by FIG.

Explanation of symbols

10 ... Optical unit, 20 ... Display, 60 ... Windshield,
80: sheet-like optical element, 81: prism sheet, 82: microprism,
83 ... Lenticular lens.

Claims (11)

A display device having an optical unit (10) for projecting image light of an image, and visually recognizing an image projected from the optical unit as a virtual image or a real image,
The optical unit is
A display (20) for projecting image light of the image;
A concave mirror (30) for magnifying the image;
A sheet-like sheet having a prism sheet (81), which is a plate-like transparent member, and a microprism (82) provided at least on the surface or on the surface opposite to the surface and including at least one total reflection surface An optical element (80),
The incident angle Θin of the light incident on the sheet-like optical element after the image light projected from the display is reflected by the concave mirror is larger than the emission angle Θout emitted through the sheet-like optical element. Has been enlarged,
The imaging position of the virtual image or the real image is a place other than the sheet-like optical element,
In the micro prism, the incident angle of light with respect to the incident surface is equal to the outgoing angle of light with respect to the outgoing surface, or in the prism sheet, the incident angle of light with respect to the incident surface is perpendicular to the outgoing angle of light with respect to the outgoing surface. Yes,
The image information projected from the optical unit is a virtual image, and the micro prisms of the prism sheet include an even number of total reflection surfaces,
Alternatively, the video information projected from the optical unit is a real image, and the micro prisms of the prism sheet include an odd number of total reflection surfaces,
If the pitch of the plurality of minute prisms is p and the optical path length from the sheet-like optical element to the place where it is visually recognized is L1, arctan (p / L1) is less than the resolution of the eye, or the plurality of minute prisms When the size of the imaging spot by the prism is S and the optical path length from the imaging spot to the place where it is visually recognized is L2, arctan (S / L2) is below the eye resolution,
At least one of said micro-prism surface is a curved surface,
The distance from the light spot on said display to said micro prisms provided in the prism sheet is a, when the M = cos (Θout) / cos (Θin), the focal length f of the micro prism f = [M / (M-1)] · a . It is on the incident surface to the sheet-like optical element and is a vector sign parallel to the surface of the sheet-like optical element, and on the emission surface to the sheet-like optical element, and is parallel to the surface of the sheet-like optical element. The display device according to claim 1, wherein the signs of the vectors are opposite to each other. It said micro prisms, a display device according to claim 1 or 2, characterized in that in the sheet-like optical element is provided on the front and back surfaces of the prism sheet. The traveling direction of light passing through the inside of the sheet-like optical element, a display device according to any one of claims 1 to 3, characterized in that is a normal direction of the sheet-like optical element. The way arctan (S / L2) is equal to or less than the resolution of the eye, the display device according to claim 1, characterized in that the pitch of the plurality of micro prisms are set. The sheet-like optical element includes at least two prism sheets, and a lenticular lens (83) is provided between the two prism sheets. The lenticular lens is formed in parallel with the microprism provided on the prism sheet. display device according to any one of claims 1 to 5, characterized in that the microlens array is formed between the are being or have, or two prism sheets are. The microlens array, the has the shape of lenticular lens in the cross direction of the prism sheet in a direction perpendicular to the cross direction in claim 6, characterized in that it has a shape of linear Fresnel lens The display device described. The sheet-like optical element includes at least one Fresnel lens and two prism sheets, claims 1, characterized in that the Fresnel lens between the two prism sheets are disposed 7 either 1 The display device described in one. The optical unit, the display device according to any one of claims 1 to 8, characterized in that the longitudinal magnification is provided with a small optical element than the transverse magnification. The display device according to claim 9 , wherein the optical element is a mirror or a lens. Wherein it prism sheet is arcuate, or display device as claimed in any one of claims 1 to 10 apex angle of the prism sheet are different from each other depending on the location.

Images