JPH0453435B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary of the Invention] By providing a diffuser plate outside the focal position of the lens, the point reflection of the light source light on the diffuser plate is magnified by the lens and clearly projected onto the projection plane. This eliminates glare and provides a highly visible display without glare. Furthermore, by providing a diffuser plate on the reflecting mirror surface, the diffusion effect and display brightness are improved.

[Industrial application field]

In the present invention, a liquid crystal display cell that allows light from a light source to be incident on the back side is arranged within the focal position of a lens, and the light from the light source is transmitted through the liquid crystal display cell to display images on the liquid crystal display cell. The present invention relates to a display device in which a displayed image is enlarged by the lens and projected onto a projection surface.

[Problems to be solved by conventional technology and invention]

Among the above-mentioned display devices, a vehicle display device using a half mirror on the projection surface and generally referred to as a head-up display is disclosed in, for example, Japanese Utility Model Application Publication No. 8576/1983.

4 and 5 show the above-mentioned known display device, in which 1 is a vehicle, 2 is a windshield of the vehicle 1, 3 is a liquid crystal display (LCD) cell, and 4 is a display device in which speed information of the vehicle 1 is inputted. an LCD drive circuit 5 that causes the LCD cell 3 to display segments according to the
is a convex lens, and 6 is a light source. The above LCD cell 3,
The drive circuit 4, convex lens 5, and light source 6 are housed in a case 7, and the case 7 is attached to the instrument panel 1a of the vehicle 1.

Further, reference numeral 8 denotes a projection surface having appropriate reflectance and transmittance, which is mounted on the dash board of the instrument panel 1a by a mounting device (not shown) so that it can be rotated at an appropriate angle with respect to the axis Y-Y of the convex lens 5. half mirror, 9 is the driver,
9a indicates the driver's eyes, and XX indicates the line of sight of the driver 9. Numeral 10 is a virtual image formed by the image Q displayed on the LCD cell 3 by the convex lens 5, and 11 is a virtual image formed by the half mirror 8 in front of the driver 9. Note that 12 is a steering wheel of the vehicle 1.

In the above device, the display pattern created by the LCD cell 3 passes through the convex lens 5 and is reflected by the half mirror 8 placed in front of the driver, so that a virtual image 11 is formed in front of the half mirror 8. As a result, the image is displayed superimposed on the external field of view. Therefore, the driver 9 understands that the virtual image 11 is the driver's 9 line of sight
By appropriately adjusting the mounting angle of the half mirror 8 so that it is connected on the X, necessary information can be visually observed without moving the head.

However, in the case of the above-described configuration, there is a large difference in display brightness between the portion corresponding to the center of the light source 6 and the other portions, making it impossible to obtain a preferable display.
Therefore, as shown in FIG. 6, between the LCD cell 3 and the light source 6, a diffusion plate 12 made of a transparent plate with a roughened surface is provided adjacent to the LCD cell 3 to diffuse the light from the light source 6. Attempts have been made to reduce the display brightness difference by transmitting light through the LCD cell 3.

However, by arranging the diffuser plate 12 adjacent to the LCD cell 3, the diffuser plate 12 is also positioned within the focal position F of the lens 5, and the diffuser plate 12
Point reflections from minute portions on the surface are magnified into particles by the lens 5 and projected onto the projection surface, which causes glare on the display surface.
It degrades display quality and significantly reduces visibility.

[Means for solving problems]

In view of the above-mentioned conventional problems, the present invention aims to provide a display device that can obtain a display with uniform display brightness without deteriorating display quality.
A device made to achieve this purpose is to install a diffuser plate that diffuses and transmits the light from the light source outside the focal point of the lens between the light source and the liquid crystal display cell, or to connect the light source and the liquid crystal display cell. It is characterized in that a reflecting mirror is installed outside the focal point of the lens between the cells and the reflecting surface, and a diffuser plate that diffuses and transmits the light from the light source is attached to the reflecting surface.

[Effect]

Because the diffuser plate is not at the focal point of the lens,
Point reflections on the diffuser plate are no longer emphasized and projected onto the projection surface, resulting in a clear display. In addition, since the diffuser plate is attached to the reflective mirror surface, the light incident on the diffuser plate is effectively diffused, and all of the diffused light is incident on the liquid crystal display cell, which improves the diffusion effect and the display. Brightness can be improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings, in which the same reference numerals are given to the same parts as those described above with reference to FIGS. 4 to 6.

FIG. 1 shows an embodiment of the present invention, in which the diffuser plate 12 is installed outside the lens focal point F between the light source 6 and the LCD cell 3, which is sufficiently distant from the focal point F of the convex lens 5. There is. By separating the diffusion plate 12 and the LCD cell 3 in this way,
When the focus of the lens 5 is adjusted to the display of the LCD cell 3, point reflections on the surface of the diffuser plate 12 are not clearly projected onto the projection surface 8, and there is no glare on the display surface.

FIG. 2 shows another embodiment in which the light from the light source 6 is not directly incident on the LCD cell 3, but is reflected by a reflecting mirror 13, and the diffuser plate 12 is located at the focal point F.
It is attached to the reflective surface side of the reflective mirror 13 provided at a position away from the mirror. In this configuration, the third
As shown in the figure, part of the light from the light source is diffusely reflected on the surface of the diffuser plate 12, and the remaining part that passes through the diffuser plate 12 is completely reflected by the reflective mirror surface on the back of the diffuser plate 12 and diffused again. Since the light is diffusely reflected when transmitted through the plate 12, the diffusion effect is significantly improved compared to the case of using only a diffuser plate. Moreover, the light 1 reflected on the surface of the diffuser plate 12
Both the light 2a and the light 13a transmitted through the diffuser plate 12 and reflected by the reflector 13 are now incident on the LCD cell 3, and there is no loss of light due to the diffuser plate 12, and the display surface of the LCD cell 3 is sufficiently illuminated. It is also possible to obtain brighter brightness.

In the above example, a half mirror is used as the projection surface 8, but the projection surface 8 may also be a windshield of a vehicle.
In addition, if it is not configured as a vehicle display device,
It may also be an opaque screen.

〔effect〕

As explained above, according to one configuration of the present invention, since the diffuser plate is not located at the focal point of the lens, point reflections on the diffuser plate are not displayed as glare on the projection plane, and a clear display can be obtained. Further, according to another configuration of the present invention, the diffusion plate is adhered to the reflecting mirror surface, so that effects such as improvement of the light diffusion effect and reduction of light loss can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the device according to the present invention, FIG. 2 is a diagram showing another embodiment of the device according to the present invention, and FIG. 3 is an enlarged sectional view of a part of FIG.
FIGS. 4 to 6 are diagrams showing examples of conventional devices. 3...LCD cell, 5...Convex lens, 6...Light source, 8...Projection surface, 12...Diffusion plate, 13...Reflector, F...Focus position.

Claims (1)

[Scope of Claims] 1. A liquid crystal display cell whose back side receives light from a light source is arranged within the focal position of a lens, and the light transmitted from the light source and transmitted through the liquid crystal display cell displays a display on the liquid crystal display cell. In a display device configured to project an image onto a projection surface, a diffusion plate is installed outside the focal point of the lens between the light source and the liquid crystal display cell to diffuse and transmit light from the light source. A display device characterized by: 2. A liquid crystal display cell whose back side receives light from a light source is placed within the focal point of a lens, and the displayed image on the liquid crystal display cell is projected onto a projection surface by the light transmitted through the liquid crystal display cell from the light source. In the display device according to the present invention, a reflecting mirror is provided outside the focal point of the lens between the light source and the liquid crystal display cell, and a reflecting mirror is attached to a reflective surface thereof to diffuse and transmit the light from the light source. A display device characterized by being installed with.