JPH0517533B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a liquid crystal display device for an overhead projector, and more specifically, the present invention relates to a liquid crystal display device for an overhead projector. The present invention relates to a liquid crystal display device formed by, etc.

<Prior Art> FIG. 2 shows a perspective view of an overhead projector having a liquid crystal display device.

In FIG. 2, the overhead projector 20 has a liquid crystal display device 51 on its stage, and the liquid crystal display device 51 is irradiated with light emitted from a light source provided in the overhead projector 20, and the light is transmitted through the liquid crystal display device 51. This is a device that projects light onto a screen (not shown) using an optical system 21 to enlarge and display a display screen on a liquid crystal display device 51.

3a and 3b show a conventional liquid crystal display device 51 for an overhead projector. In addition, Fig. 3b
is a sectional view taken along line A-A in FIG.

In this liquid crystal display device 51, a liquid crystal display panel 55, which has protective filters 53 and 54 provided on the upper and lower surfaces of a transmissive liquid crystal display cell 52, is held horizontally by a cabinet 56, and light L is irradiated from below to display the liquid crystal display. The light transmitted through the panel 55 is projected onto a screen (not shown) by an optical system (not shown), so that the screen formed on the liquid crystal display cell 52 is enlarged and displayed. Note that 57 is a drive circuit for the liquid crystal display cell 52.

<Problems to be Solved by the Invention> In the case of the conventional liquid crystal display device 51 described above, there is a problem in that the temperature of the liquid crystal display cell 52 increases due to the light L being irradiated onto the liquid crystal display cell 52.

That is, if the light L is too strong, the liquid crystal display cell 5
2, the temperature rise becomes large, but this causes the problem of uneven display contrast and color.

Therefore, the light L cannot be made too strong, but if this is done, there is a problem that the image projected onto the screen will be dark.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device for an overhead projector that prevents the temperature of the liquid crystal display cell from rising and does not cause unevenness in contrast or color even when the light is intensified. .

<Means for Solving the Problems> A liquid crystal display device for an overhead projector according to the present invention is a liquid crystal display device for an overhead projector in which a transmissive liquid crystal display cell is sandwiched between upper and lower protective panels. A gap is provided between the display cell and each protective panel to form an air flow passage above and below the transmission type liquid crystal display cell, and a fan is provided to circulate air in each of the upper and lower air flow passages. The structural feature is that air flows in the opposite direction.

<Function> In the liquid display device for an overhead projector of the present invention, gaps are provided between the liquid crystal display cell and each protection panel, and air is circulated in opposite directions through the upper and lower gaps by a fan.

Therefore, since both surfaces of the liquid crystal display cell directly contact the air and are cooled, the cooling efficiency is high.

Moreover, since the air flows in opposite directions in each air flow path, the liquid crystal display cell is uniformly cooled.

Furthermore, since air is circulated through the air flow path formed by the liquid crystal display cell and the protection panel, the air flow efficiency is improved and the fan can be made smaller.

Additionally, since the protective panel is used to form the air flow path, no extra parts are required.

Therefore, the temperature rise of the liquid crystal display cell can be efficiently prevented with an overall compact configuration.

Therefore, the light can be made stronger, and the projection screen can be made brighter without causing unevenness in contrast or color.

<Example> Hereinafter, the present invention will be explained in more detail based on the example shown in the drawings. FIG. 1a is a schematic plan view of a liquid crystal display device for an overhead projector according to an embodiment of the present invention, and FIG. 1b is a sectional view taken along line A-A in FIG. Note that the present invention is not limited to the embodiments shown in the figures.

1A and 1B are a schematic plan view and a cross-sectional view showing the structure of the liquid crystal display device 1. FIG.

A transmission type liquid crystal display cell 2 and protective filters 3 and 4 that protect its upper and lower surfaces are held horizontally by a cabinet 6.

Inside the cabinet 6, a driving circuit 7 for the liquid crystal display cell 2 is built-in.

The protective filters 3 and 4 that protect the upper and lower surfaces of the liquid crystal display cell 2 are held by a cabinet 6 with a predetermined gap provided from the top and bottom surfaces of the liquid crystal display cell 2, and the gaps form air flow passages 8a and 8b. are doing.

As shown in FIG. 1b, air suction ports 10a and 10b are provided at one edge of the top and bottom surfaces of the cabinet 6, respectively, and the air suction ports 10a and 10b are connected to fan chambers 11a and 11b.
It communicates with the air flow passages 8a and 8b via 1b.

On the other hand, air outlet ports 12 are provided on the opposite side of each of the air intake ports 10a and 10b.
a, 12b are provided, and the air outlet 12
a, 12b communicate with the airflow passages 8a, 8b. The air inlets 10a, 10b and the air outlets 12a, 12b are provided on opposite sides of the upper and lower surfaces of the liquid crystal display cell 2.

Axial flow fans 9 are provided in the fan chambers 11a and 11b.
a and 9b are arranged, and air is allowed to flow in opposite directions between the upper and lower surfaces of the liquid crystal display cell 2 as indicated by the arrows in FIG.

That is, when the axial fans 9a, 9b rotate, external air is sucked in from the respective air suction ports 10a, 10b, passes through the airflow passages 8a, 8b, and is discharged to the outside from the air blowoff ports 12a, 12b.

At this time, the air flowing through the air flow passages 8a and 8b comes into contact with the upper and lower surfaces of the liquid crystal display cell 2,
Direct cooling. Moreover, since air flows in opposite directions between the upper and lower surfaces of the liquid crystal display cell 2, the liquid crystal display cell 2 is uniformly cooled. Therefore, an increase in temperature of the liquid crystal display cell 2 caused by exposure to the light L is suppressed.

In other words, since the temperature of the liquid crystal display cell 2 does not increase, contrast unevenness and color unevenness are prevented from occurring. Furthermore, since the light L can be made stronger, the brightness of the projected image can be increased.

Further, the cabinet 6 has an air inlet 10a and an air outlet 12a on the upper surface facing upward, and an air inlet 10b and an air outlet 12 on the lower surface.
b has a structure that faces downward, so the warm air coming out from the air outlet 12a on the upper surface (or lower surface) flows into the air inlet 10b on the lower surface (or upper surface).
This improves the cooling effect.

Note that although the liquid crystal display cell 1 is rectangular, the air is allowed to flow in a direction that crosses the long sides of the cell.
Although this is preferable in view of temperature cooling efficiency, it goes without saying that air may be allowed to flow in a direction that crosses the short sides.

Further, it is preferable that the fans 9a and 9b generate a wide laminar flow of air over the long sides of the rectangle, and an axial flow fan is suitable as such fans.

<Effects of the Invention> As described above, according to the present invention, in a liquid crystal display device for an overhead projector in which a transmissive liquid crystal display cell is sandwiched between upper and lower protective panels, there is no space between the transmissive liquid crystal display cell and each protective panel. A gap is provided in each of the upper and lower air flow passages to form an air flow passage, and a fan for circulating air is provided in each of the upper and lower air flow passages, and the air is circulated in opposite directions in the upper and lower air flow passages by the fans. A liquid crystal display device for an overhead projector is provided, which is characterized by the following advantages.

Since the surface of the transmissive liquid crystal display cell can be air-cooled directly and uniformly, the cooling efficiency is high.

Since air flow passages are formed and air is circulated only in necessary portions of the surface of the liquid crystal display cell, the air blowing efficiency is high and a small fan can be used.

Since the air flow path is formed using the protection panel of the transmissive liquid crystal display cell, no extra parts are required and the configuration is simple.

Since the temperature of the liquid crystal display panel 2 can be prevented from increasing by air cooling, the occurrence of contrast and color unevenness can be prevented. In other words, since the light can be made stronger, the projection screen can be made brighter.

[Brief explanation of the drawing]

FIG. 1a is a schematic plan view of a liquid crystal display device for an overhead projector according to an embodiment of the present invention, FIG. 1b is a sectional view taken along line A-A in FIG. FIGS. 3a and 3b, which are perspective views of the external appearance of an overhead projector, are views corresponding to FIG. 1 of an example of a conventional liquid crystal display device for an overhead projector. 1... Liquid crystal display device for overhead projector, 2... Transmissive liquid crystal display cell, 3... Upper protection filter, 4... Lower protection filter, 8a, 8
b... Air flow passage, 9a, 9b... Axial flow fan.

Claims (1)

[Scope of Claims] 1. In a liquid crystal display device for an overhead projector in which a transmissive liquid crystal display cell is sandwiched between protective panels from above and below, a gap is provided between the transmissive liquid crystal display cell and each protective panel to allow air to circulate. Along with forming a road,
A liquid crystal display device for an overhead projector, characterized in that the upper and lower air flow passages are each provided with a fan for circulating air, and the fans circulate air in opposite directions in the upper and lower air flow passages. .