JP4720694B2 - Vehicle display device - Google Patents

Description

  The present invention relates to a vehicle display device.

  2. Description of the Related Art Conventionally, a vehicular display device that displays a formed image of a liquid crystal panel that is transmitted and illuminated by light from a backlight is known. For example, a head-up display that displays a formed image of a liquid crystal panel on a combiner is one type. As such a display device for vehicles, in order to improve the irradiation efficiency to the liquid crystal panel, a device in which light from a backlight is collected by a projection lens and projected onto the liquid crystal panel is proposed in Patent Document 1 and the like.

Now, in the technique of projecting the light of the backlight onto the liquid crystal panel by the projection lens, the convex lens 120 is usually disposed on the optical axis 130 connecting the backlight 100 and the liquid crystal panel 110 as shown in FIG. The convex lens 120 is used as a projection lens.
JP 2005-153811 A

  However, when the convex lens 120 is used as shown in FIG. 9, it has been found that the following problems occur when trying to meet the recent demand for enlargement of the image forming area for the liquid crystal panel. The problem is that the convex lens 120 and the backlight 100 need to be enlarged in the direction perpendicular to the optical axis 130, or the convex lens 120 needs to be enlarged in the optical axis 130 direction. Such an increase in size is not desirable because it deteriorates, for example, the mountability of the vehicle display device on the vehicle.

  Accordingly, an object of the present invention is to provide a vehicle display device that can be miniaturized.

According to the first to fifth aspects of the present invention, a liquid crystal panel that forms an image to be displayed on a vehicle, a backlight that emits light to transmit and illuminate the liquid crystal panel, and a liquid that collects light incident from the backlight. In a vehicular display device that includes a projection lens that projects onto a panel, the projection lens has a convex lens surface that is convex toward the liquid crystal panel with the optical axis connecting the backlight and the liquid crystal panel as the central axis, and a convex lens. It is provided on the backlight side of the surface, and is inclined with respect to the optical axis so as to move away from the optical axis from the backlight side toward the convex lens surface side, and reflects incident light from the backlight toward the convex lens surface side. And a light reflector is provided on the outer peripheral side of the reflective surface, and is formed by the outer peripheral surface of the projection lens so that incident light from the backlight is directed to the convex lens surface side. The tilt angle of the reflecting surface that totally reflects is set so as to satisfy θi = arcsin (1 / n), where n is the refractive index of the projection lens and θi is the incident angle of light from the backlight to the reflecting surface. It is characterized by that.

In such a fifth aspect of the invention, on the convex lens surface having the optical axis connecting the backlight and the liquid crystal panel as the central axis, in addition to the incident light from the backlight, it goes from the backlight side to the convex lens surface side. The reflected light from the reflecting surface that is inclined so as to be further away from the optical axis is guided. As a result, the light guided directly from the backlight to the convex lens surface and the light guided from the backlight via the reflecting surface to the convex lens surface are collected by refraction at the convex lens surface convex to the liquid crystal panel side. And projected onto the liquid crystal panel. Here, the light guided to the convex lens surface via the reflecting surface is light that can be guided to the convex lens surface only when the convex lens surface and the backlight are enlarged if the projection lens is a conventional convex lens. In other words, since the projection lens and the backlight can be made smaller than before, even if the image forming area of the liquid crystal panel is enlarged, the display device for vehicles is made as small as possible to be mounted on a vehicle, for example. Can be increased.
In addition, according to the first to fifth aspects of the present invention, since the reflecting surface is formed by the outer peripheral surface of the projection lens, the reflecting surface can be easily formed using the refractive index of the lens material of the projection lens. it can. Furthermore, according to the invention described in claims 1 to 5 , since the reflection surface totally reflects the incident light from the backlight toward the convex lens surface side, the light projection efficiency to the liquid crystal panel, that is, the irradiation efficiency of the liquid crystal panel is improved. It can be enhanced by a simple configuration.
Furthermore, according to the first to fifth aspects of the present invention, since the light reflector is provided on the outer peripheral side of the reflecting surface, the light transmitted through the reflecting surface can be reflected by the light reflector. Therefore, the light projection efficiency to the liquid crystal panel, that is, the irradiation efficiency of the liquid crystal panel is increased.

According to the invention described in claim 2, planar reflective surface, for one side of the rectangular liquid crystal panel, since it is parallel to, the sides of the liquid crystal panel due to light passing through the reflective surface It is possible to suppress the occurrence of luminance unevenness in the stretching direction.

According to the invention described in claim 3, the pair of reflecting surfaces, for the two sides facing the rectangular liquid crystal panel, since it is arranged parallel to each of the projection lens and the backlight in the opposing direction of the two sides It can be made sufficiently small.

As the “backlight”, a backlight composed of only a light source may be adopted. For example, as in the invention described in claim 4 , the light emitted from the light source and the light source is diffused to the projection lens. It is desirable to employ one having an incident diffusing member. In this case, it is possible to suppress the occurrence of luminance unevenness in the liquid crystal panel due to light emission unevenness of the light source.

Since the invention described in claim 5 is a head-up display that displays a formed image of the liquid crystal panel on a combiner, a downsizing as described above, for example, can be highly mounted on a vehicle.

  Note that the “combiner” may be constituted by, for example, a windshield of a vehicle, or may be constituted by a dedicated member other than the windshield.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment.

(First embodiment)
FIG. 2 schematically shows the configuration of a head-up display (hereinafter referred to as “HUD”) 10 according to the first embodiment of the present invention.

  The HUD 10 is mounted on a vehicle and arranged in an instrument panel (not shown) in front of the passenger compartment. The HUD 10 includes a display 12 and an optical system 14. The display 12 forms vehicle information as an image. The optical system 14 is composed of, for example, a mirror, a lens, and the like, and guides the image light of the image formed on the display 12 to the windshield 16 in front of the passenger compartment. As a result, the image light incident on the windshield 16 is imaged on the surface of the windshield 16 on the vehicle interior side and displayed as a virtual image.

  FIG. 3 shows a specific configuration of the display 12 in a cross-sectional view. Note that the vertical direction in FIG. 3 substantially matches the vertical direction when the vehicle is mounted.

  The display device 12 includes a casing 20, a backlight 22, a projection lens 24, and a liquid crystal panel 26. The casing 20 is formed in a box shape and accommodates a backlight 22, a projection lens 24, and a liquid crystal panel 26.

  The backlight 22 includes a light source 30, an inner lens 32, a diffusion plate 34, and the like. The light source 30 is a light emitting diode in the present embodiment, but may be a xenon lamp, a fluorescent display tube, or the like. The inner lens 32 is composed of a convex lens, collects light emitted from the light source 30 that has emitted light over a wide area, and enters the diffuser plate 34. The diffuser plate 34 has a light emitting surface 36 on the opposite side to the inner lens 32, and diffuses incident light from the inner lens 32 and emits it from the light emitting surface 36. The light emitting surface 36 of the present embodiment is formed in a planar shape and functions as a uniform light source surface in which uneven brightness is suppressed.

  The projection lens 24 is made of a high refractive index material such as resin, and is disposed between the backlight 22 and the liquid crystal panel 26. Light emitted from the diffusion plate 34 is incident on the backlight 22 side of the projection lens 24. The projection lens 24 collects incident light from the backlight 22 and projects it onto the liquid crystal panel 26.

  The liquid crystal panel 26 has a screen 40 on the side opposite to the projection lens 24, and forms an image on the screen 40 according to an input signal from the outside. The liquid crystal panel 26 is a transmissive type, and is illuminated by being projected from the projection lens 24. Here, the liquid crystal panel 26 exposes the screen 40 to the outside through the display window 42 of the casing 20, and outputs a formed image on the screen 40 to the optical system 14 (see FIG. 2) by transmitted illumination.

  FIG. 1 schematically shows a characteristic part of the display 12. The vertical direction in FIG. 1 corresponds to the vertical direction in FIG.

  The projection lens 24 has a convex lens surface 50 and a pair of reflecting surfaces 52 and 54. The convex lens surface 50 is formed in a curved surface that is convex toward the liquid crystal panel 26 side. The convex lens surface 50 is disposed with the optical axis 56 connecting the light emitting surface 36 of the backlight 22 and the screen 40 of the liquid crystal panel 26 as the central axis, and thereby refracts light toward the optical axis 56. The refracted light is projected onto the screen 40 of the liquid crystal panel 26. The projection angle θp to the liquid crystal panel 26 is set according to the required viewing angle θv required for the screen 40.

  The reflection surfaces 52 and 54 are provided closer to the backlight 22 than the convex lens surface 50, and sandwich the optical axis 56 in the vertical direction of the vehicle. As shown in FIG. 4, the reflecting surfaces 52 and 54 are formed in a planar shape by the outer peripheral surface of the projection lens 24, and are respectively opposed to two sides 62 and 64 that are vertically opposed to the liquid crystal panel 26 that has a rectangular shape in plan view. They are arranged in parallel. As shown in FIG. 1, the reflecting surfaces 52 and 54 of the present embodiment are inclined with respect to the optical axis 56 so as to be gradually separated from the optical axis 56 toward the convex lens surface 50 side from the backlight 22 side. Yes. As a result, the reflecting surfaces 52 and 54 reflect part of the incident light from the backlight 22 toward the convex lens surface 50 as shown by a two-dot chain line in FIG.

Here, the inclination angle θt of the reflecting surfaces 52 and 54 with respect to the optical axis 56 is set so as to totally reflect the incident light from the backlight 22 toward the convex lens surface 50 side. Specifically, the reflection angle equal to the incident angle θi so that the incident angle θi of the light to the reflecting surfaces 52 and 54 satisfies the following expression (1) with respect to the refractive index n determined by the forming material of the projection lens 24. The inclination angle θt of the reflecting surfaces 52 and 54 is set so that the projection angle θp is realized by θr. The inclination angles θt of the reflecting surfaces 52 and 54 may be different from each other or the same.
θi ≧ arcsin (1 / n) (1)

As shown by a two-dot chain line in FIG. 1, the light totally reflected by the reflecting surfaces 52 and 54 is guided to the convex lens surface 50 and projected onto the liquid crystal panel 26. Further, of the incident light from the backlight 22, the light guided to the convex lens surface 50 through the optical path not passing through the reflecting surfaces 52 and 54 as shown by the one-dot chain line in FIG. 1 is also projected onto the liquid crystal panel 26. FIG. 5 shows the reflection angle θr dependence of the luminance unevenness generated on the screen 40 of the liquid crystal panel 26 as a result of such projection, but the luminance unevenness is minimized when the reflection angle θr is arcsin (1 / n). I understand. That is, regarding the reflection surfaces 52 and 54 parallel to the two sides 62 and 64 of the liquid crystal panel 26, the irradiation angle of the liquid crystal panel 26 is such that the incident angle θi equal to the reflection angle θr satisfies the following expression (2). It is the most desirable for increasing efficiency.
θi = arcsin (1 / n) (2)

  In the projection lens 24 having such a configuration, conventionally, as shown by a broken line in FIG. 6, the light that can realize the projection angle θp only when the convex lens 120 and the backlight 100 are enlarged in the direction orthogonal to the optical axis 130. Obtained by the reflecting surfaces 52 and 54. In addition, as a secondary effect, conventionally required meat is removed on the outer peripheral sides of the reflecting surfaces 52 and 54. Further, in the projection lens 24, conventionally, light that can realize the projection angle θp is obtained by the reflecting surfaces 52 and 54 only when the convex lens 120 is enlarged in the direction of the optical axis 130 as shown by a broken line in FIG.

  For these reasons, according to the first embodiment, since the size of the projection lens 24 and the backlight 22 can be reduced as compared with the conventional size, the HUD 10 can be used even if the area of the screen 40 of the liquid crystal panel 26 is increased. The size can be reduced as much as possible. Therefore, the vehicle mountability and cost performance of the HUD 10 can be improved, and the weight of the HUD 10 can be reduced.

  In the first embodiment described above, the HUD 10 corresponds to a “vehicle display device”, the diffusion plate 34 corresponds to a “diffusion member”, and the vehicle windshield 16 corresponds to a “combiner”.

(Second embodiment)
As shown in FIG. 8, the second embodiment of the present invention is a modification of the first embodiment. In the second embodiment, optical reflectors 72 and 74 are provided on the outer peripheral sides of the reflecting surfaces 52 and 54, respectively. Therefore, even if the incident angle θi of light on the reflecting surfaces 52 and 54 cannot satisfy the above expression (1), the light transmitted through the reflecting surfaces 52 and 54 is reflected and guided to the convex lens surface 50. be able to.

  In addition, about the optical reflectors 72 and 74, a metal etc. may be vapor-deposited on the outer peripheral side of each reflective surface 52 and 54, and you may form with the said vapor deposition film, for example. Alternatively, the light reflectors 72 and 74 may be formed of a resin or the like in which a light reflecting agent is blended, and fixed to the outer peripheral side of the reflecting surfaces 52 and 54.

  Although a plurality of embodiments of the present invention have been described so far, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. be able to.

  For example, in the projection lens 24, at least one of the reflecting surfaces 52 and 54 may be formed in a curved surface shape. In the projection lens 24, either one of the reflection surfaces 52 and 54 may be provided. Further, in the projection lens 24, a pair of reflecting surfaces that sandwich the optical axis 56 in the lateral direction of the vehicle or any one of them is provided instead of or in addition to the reflecting surfaces 52, 54. It may be. In addition, about each reflective surface when pinching | interposing the optical axis 56 to a horizontal direction, you may form at least one among them in a curved surface form, but with respect to two sides opposite to the horizontal direction of the liquid crystal panel 26 which exhibits a rectangle. It is desirable to form them in parallel planes.

  As the backlight 22, in addition to a combination of the light source 30 with the inner lens 32 and the diffusion plate 34, for example, a combination of the light source 30 with only the diffusion plate 34 or a combination of the light source 30 alone may be used. . In either case, the number of light sources 30 may be set as appropriate according to the specifications.

  As a combiner for displaying a formed image of the display device 12 as a virtual image, a dedicated one may be provided in the HUD 10 other than the one using the vehicle windshield 16.

  In addition to the HUD, the present invention may be applied to a vehicle display device such as a combination meter.

It is a schematic diagram which shows the characteristic part of the display device of HUD by 1st embodiment of this invention. It is a schematic diagram which shows the structure of HUD by 1st embodiment of this invention. It is sectional drawing which shows the specific structure of the indicator by 1st embodiment of this invention. It is the IV-IV sectional view taken on the line of FIG. It is a schematic diagram for demonstrating the characteristic of the indicator by 1st embodiment of this invention. It is a schematic diagram for demonstrating the effect of the indicator by 1st embodiment of this invention. It is a schematic diagram for demonstrating the effect of the indicator by 1st embodiment of this invention. It is a schematic diagram which shows the characteristic part of the indicator of HUD by 2nd embodiment of this invention. It is a schematic diagram for demonstrating a prior art.

Explanation of symbols

10 HUD (vehicle display device), 12 display, 14 optical system, 16 windshield (combiner), 20 casing, 22 backlight, 24 projection lens, 26 liquid crystal panel, 30 light source, 32 inner lens, 34 diffuser plate ( Diffuser member), 36 light emitting surface, 40 screen, 42 display window, 50 convex lens surface, 52, 54 reflecting surface, 56 optical axis, 62, 64 sides, 72, 74 light reflector, 100 backlight, 110 liquid crystal panel, 120 convex lens , 130 Optical axis, θi incident angle, θp projection angle, θr reflection angle, θt tilt angle, θv required viewing angle

Claims (5)

A liquid crystal panel that forms an image to be displayed on a vehicle, a backlight that emits light to transmit and illuminate the liquid crystal panel, and a projection lens that collects light incident from the backlight and projects the light onto the liquid crystal panel In a vehicle display device comprising:
The projection lens is
A convex lens surface that is convex toward the liquid crystal panel, with the optical axis connecting the backlight and the liquid crystal panel as the central axis;
Provided on the backlight side with respect to the convex lens surface, and is inclined with respect to the optical axis so as to move away from the optical axis from the backlight side toward the convex lens surface side, and incident light from the backlight is A reflective surface that reflects toward the convex lens surface;
Have
An optical reflector is provided on the outer peripheral side of the reflecting surface,
The inclination angle of the reflection surface that is formed by the outer peripheral surface of the projection lens and totally reflects the incident light from the backlight toward the convex lens surface side is n as the refractive index of the projection lens and the reflection surface from the backlight. The vehicle display device is set so as to satisfy θi = arcsin (1 / n), where θi is an incident angle of light.   The vehicle display device according to claim 1, wherein the planar reflection surface is arranged in parallel to one side of the rectangular liquid crystal panel.   The vehicle display device according to claim 2, wherein the pair of reflective surfaces are arranged in parallel with each of two opposing sides of the liquid crystal panel. The backlight is
A light source;
The vehicle display device according to claim 1, further comprising: a diffusion member that diffuses light emitted from the light source and enters the projection lens . 5. The vehicle display device according to claim 1, wherein the display device is a head-up display that causes a combiner to display a virtual image of an image formed on the liquid crystal panel .

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