JPH0748092B2 - Display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to improvement of a screen of a non-emissive display device such as a liquid crystal display device.

[Conventional technology]

Generally, display devices can be roughly classified into active type (light emitting type) and passive type (non-light emitting type). What is active type (light emitting type)?
Display is performed by emitting light from itself such as a light emitting diode, a plasma display, an electroluminescent display and the like. On the other hand, the passive type does not emit light by itself such as a liquid crystal display device, an electrochromic display device, or an electrochromic display device, but controls the light transmittance or reflectance to allow natural light or another illumination source. Modulates the light emitted from
The pattern is displayed. Therefore, the passive type has a problem that the display becomes difficult to see unless the illumination means is provided when the surroundings are dark.

FIG. 4 shows the configuration of a conventional display device disclosed in, for example, Japanese Utility Model Publication No. 60-44076. (A) is an exploded perspective view,
(B) is a side view. In the figure, (1) is a fluorescent discharge tube as a light source, (2) is a diffuse reflector, (3) is a liquid crystal display panel, (4) and (5) are the fluorescent discharge tube (1) and a liquid crystal display panel (3). Between the screen) and a diffuse transmission plate provided for uniform brightness. This screen (4) comprises a transparent film (6) and a thin metal film (7) such as Al provided on the transparent film (6) as shown in FIG. This metal thin film (7)
Are patterned like a mosaic or a mesh photograph, and a part of incident light is reflected and the rest is transmitted. In this case, the light transmission rate is set such that the area ratio of the reflecting surface is set to be larger than the area ratio of the transmitting surface in the region close to the fluorescent discharge tube (1), and the area ratio of the reflecting surface increases as the distance from the fluorescent discharge tube (1) increases. Is made small and the area ratio of the transmission surface is made large, so as to achieve uniform brightness on the display surface of the liquid crystal display panel (3). The area ratio of the reflecting surface and the transmitting surface is determined by the density of the metal thin film attached on the transparent film (6), and the amount of transmitted light is controlled and set according to the area ratio. The light reflected by the screen (4) is reflected by the diffuse reflection plate (2) on the back side, and again the screen (4)
Is incident on. The light transmitted through the screen (4) is scattered by the diffuse transmission plate (5) and guided to the display panel (5), so that uniform luminance display is performed.

[Problems to be Solved by the Invention]

Since the screen (4) in the conventional display device has been focused on the effect of uniforming the brightness, the pattern of the metal film (7) attached on the transparent film (6) is, for example, as shown in FIG. Broken, especially fluorescent discharge tube (1)
In the area away from, there was no connection between the patterns. Therefore, it is impossible to keep all the patterns of the metal film (7) at the ground potential, and the screen (4) cannot have the shield effect. As a result, noise radio waves emitted from the fluorescent discharge tube (1) pass through the screen (4) and the diffuse transmission plate (5) and reach the liquid crystal display panel (3), which causes a problem that display quality is deteriorated. was there.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a display device in which noise radio waves are suppressed on the screen and the image quality is less deteriorated.

[Means for Solving the Problems]

In the display device according to the present invention, between the display panel and the light source, the metal thin film is patterned in a continuous mesh pattern or a mosaic pattern while keeping the density close to the effective illumination surface, and the periphery is solidly patterned and connected. The screen is held at the ground potential.

[Action]

The screen in the display device configured as described above prevents noise radio waves from leaking from the screen to the diffuse transmission plate side by grounding.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which (a) is an exploded perspective view and (b) is a side view. Since (1) to (3) and (5) are the same as those of the conventional example shown in FIG. 4, description thereof will be omitted. (8) is a screen, as shown in FIG. 2 (a), a thin metal film (9) of Al or the like is formed into a continuous mesh pattern on a transparent film (6), and a solid pattern region () of a thin metal film provided in the periphery ( 10) is connected to. The mesh continuous pattern is formed such that the density of the metal thin film (9) is dense in the area near the light source and coarse in the area far from the light source.

The density of the pattern of the metal thin film (9) is shown in FIG.
As shown in (c), it may be created by the thickness of the lines of the mesh or mosaic-like figure, or by the size of the unit figure of the mesh or mosaic figure, or a combination thereof.

In the display device configured as described above, when the continuous mesh pattern is held at the ground potential through the solid pattern area (10) of the metal thin film (9) and the fluorescent discharge tube (1) is turned on. The noise electric wave emitted from the fluorescent discharge tube (1) is weakened by the shield effect of the screen (8).
As a result, it is possible to prevent the image quality of the liquid crystal display panel (3) from deteriorating and to minimize the radio wave interference to peripheral devices.

Further, since the pattern of the metal thin film (9) is made continuous, the heat conduction of the screen (8) is increased as compared with the conventional screen (4), whereby the surface of the diffusion transmission plate (5) in contact with the back surface of the screen (8). Since the temperature distribution is more uniform than that of the conventional display device, it is possible to prevent the deterioration of image quality due to the temperature unevenness of the liquid crystal display panel (3).

It is desirable that the number of ground points in the solid pattern area (10) is one or more as many as possible.

In the above embodiment, the screen (8) having the metal thin films (9) and (10) on the transparent film (6) is installed between the light source (1) and the diffuse transmission plate (5) to obtain uniform light. Although the metal thin film (12) is made to have a high efficiency and a shielding effect, the metal thin film (12) may be directly patterned and adhered onto the diffuse transmission plate (5) as shown in FIG.

〔The invention's effect〕

Since the present invention is configured as described above,
The screen held at the ground potential shields noise radio waves and provides good image quality.

[Brief description of drawings]

1 (a) and 1 (b) are an exploded perspective view and a side view showing a display device according to an embodiment of the present invention, and FIGS.
(B) and (c) are an overall view of a screen constituting a main part of the display device in FIG. 1 and an enlarged view of a main part showing details of a mesh in detail. 3 (a) and 3 (b) are exploded perspective views and side views showing a display device according to another embodiment of the present invention, and FIGS. 4 (a) and 4 (b) are exploded perspective views showing a conventional display device. FIG. 5 is a side view and FIG. 5 is a view showing a screen used in a conventional display device. In the figure, (1) is a light source, (2) is a diffuse reflector, and (3)
Is a display panel, (4) is a screen, and (5) is a diffuse transmission plate. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A non-luminous display panel which requires illumination, a light source which is arranged behind the display panel and irradiates the display panel with light, and a metal thin film which is provided between the light source and the display panel. Scatters light from the light source provided between the screen and the display panel, which is held at the ground potential by patterning in a continuous mesh pattern or mosaic pattern and connecting the peripheral areas in a solid pattern. A display device, comprising: a diffuse transmission plate that leads to the display panel.