JPH0421169B2 - - Google Patents

Description

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

Prior Art FIG. 3 shows a conventional liquid crystal display device 51 for an overhead projector.

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 57a and 57b are drive circuits for the liquid crystal display cell 52.

Problems with the Prior Art 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 irradiation of the liquid crystal display cell 52 with the light L.

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.

OBJECTS OF THE INVENTION It is an object of the present invention 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. There is a particular thing.

Structure of the Invention 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 protective panels from above and below. The structure is characterized in that a gap is provided between the filters to form an air flow passage, and a fan is provided to circulate air through the air flow passage.

In addition, from the point of view of efficiently cooling the light irradiation surface of the transmissive liquid crystal display cell, it is preferable to form a gap between the transmissive liquid crystal display cell and the lower protection panel.

Function: In the liquid crystal display device for an overhead projector according to the present invention, a gap is provided between the liquid crystal display cell and the protective panel, and air is circulated through the gap by a fan.

Therefore, since the surface of the liquid crystal display cell directly contacts the air and is cooled, the cooling efficiency is high.

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.

Moreover, since the air flow passage is formed using the protective panel, 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.

EXAMPLES The present invention will be described in more detail below based on examples shown in the drawings. Here, FIG. 1 is an external perspective view of an overhead projector having a liquid crystal display device according to the present invention, and FIG. 2 is a schematic cross-sectional view of a liquid crystal display device for an overhead projector according to an embodiment of the present invention. be. Note that the present invention is not limited to the embodiments shown in the figures.

In FIG. 1, an overhead projector 10 has a liquid crystal display device 1 according to the present invention, and the liquid crystal display device 1 is irradiated with light emitted from a light source provided in the overhead projector 10, and the light is transmitted through the liquid crystal display device 1. This is a device that projects light onto a screen (not shown) using an optical system 11 to enlarge and display the display screen of the liquid crystal display device 1.

FIG. 2 is a schematic cross-sectional view showing the structure of the liquid crystal display device 1. As shown in FIG.

The transmissive liquid crystal display cell 2 and the upper protection filter 4 that protects its upper surface are integrally formed into a panel,
It is held horizontally by the cabinet 6.

Inside the cabinet 6, drive circuits 7a and 7b for the liquid crystal display cell 2 are built.

A protective filter 3 for protecting the lower surface of the liquid crystal display cell 2 is held by a cabinet 6 with a predetermined gap provided from the lower surface of the liquid crystal display cell 2, and the gap forms an air flow passage 8.

As shown in FIGS. 1 and 2, an air suction port 12 is provided at one end edge of the upper surface of the cabinet 6, and the air suction port 12 is connected to the air flow passage through a fan chamber 13. It is connected to 8.

On the other hand, as shown in FIG. 2, an air outlet 14 is provided on the opposite side from the air intake 12.
is provided, and its air outlet 14 communicates with the air flow passage 8.

An axial fan 9 is arranged in the fan chamber 13,
Air is circulated as shown by the arrow in Figure 2.

That is, when the axial fan 9 rotates, external air is sucked in through the air suction port 12, passes through the air flow path 8, and is discharged to the outside from the air blowout port 14.

At this time, the air flowing through the air flow path 8 comes into contact with the lower surface of the liquid crystal display cell 2 and directly cools it.
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.

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.
This is preferable in view of temperature cooling efficiency.

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

Effects of the Invention 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, a gap is provided between the transmissive liquid crystal display cell and the protective panel for air circulation. Provided is a liquid crystal display device for an overhead projector, characterized in that a fan is provided to form a channel and to circulate air in the air flow channel.
This provides the following effects.

Cooling efficiency is high because the surface of the transmissive liquid crystal display cell can be directly air cooled.

Since the air flow path is formed only in the necessary portions of the surface of the liquid crystal display cell to prevent air from flowing, 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 projected image can be made brighter.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of an overhead projector having a liquid crystal display device according to the present invention, FIG. 2 is a schematic cross-sectional view of a liquid crystal display device for an overhead projector according to an embodiment of the present invention, and FIG. 2 is a diagram corresponding to FIG. 2 of an example of a conventional liquid crystal display device for an overhead projector. (Explanation of symbols), 1... Liquid crystal display device for overhead projector, 2... Transmissive liquid crystal display cell, 3... Lower protection filter, 4... Upper protection filter, 6... Cabinet, 7a, 7b ...Liquid crystal display cell drive circuit, 8...Air flow path, 9...
...Axial flow fan, 10...Overhead projector, 11...Optical system, 12...Air inlet, 13...Fan chamber, 14...Air outlet, L...Light.

Claims (1)

[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 the protective panel to form an air flow path. 1. A liquid crystal display device for an overhead projector, characterized in that a fan is provided for circulating air in the air flow path.