JPH11249120A - Transmission type display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission type display with which heat generated on a liquid crystal display(LCD) panel and a polarizing plate can be efficiently removed without the occurrence of irregular color. SOLUTION: This device is provided with an LCD panel 1 for displaying an image, a supporting frame 2 of a high heat conductivity for supporting the LCD panel 1, a polarizing plate 3 for transmitting light polarized orthogonally to incident light and shielding parallel-polarized light, a transparent substrate 4 of a high heat conductivity for absorbing and radiating heat generated on the LCD panel 1 and the polarizing plate 3, and a filling part 5 for filling non-adhesive gel-state or liquid-state materials. Thus, heat generated on the LCD panel 1 and the polarizing plate 3 can be radiated from the transparent substrate 4 to the supporting frame 2 and the LCD panel 1 can be efficiently cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive display device used for a liquid crystal projector, a liquid crystal television and the like, and more particularly, to a device for efficiently radiating a liquid crystal display panel and a polarizing plate provided on the exit side of the liquid crystal display panel. And a suitable transmissive display device.

[0002]

2. Description of the Related Art A conventional technique will be described below with reference to FIGS. FIG. 4 is a plan view showing a schematic configuration of a conventional liquid crystal projector, and FIG. 5 is a plan view showing a configuration of a peripheral portion of a conventional liquid crystal display panel.

[0003] As shown in FIG.
For example, a light source 11 that emits a strong light source light such as a metal halide lamp, a reflecting mirror 12 that reflects light from the light source 11, a heat ray cut that removes unnecessary infrared rays of the light source light emitted from the light source 11 and the reflected light from the reflecting mirror 12 The filter 13, a condensing lens 14 for condensing light transmitted through the heat ray cut filter 13, a liquid crystal display panel 15 for displaying an image by transmitting the light condensed by the condensing lens 14, and supporting the liquid crystal display panel 15. Support frame 16 and liquid crystal display panel 15
A projection lens 17 for enlarging and projecting outgoing light emitted therefrom,
An electric fan 18 for cooling the liquid crystal display panel 15 and a polarizing plate 19 attached to the liquid crystal display panel 15 described later is provided.

Next, the operation of the liquid crystal projector will be described. First, unnecessary infrared rays are removed from the light source light from the light source 11 and the reflected light from the reflecting mirror 12 by the heat ray cut filter 13, and are emitted to the condenser lens 14. The light source light and reflected light from which unnecessary infrared rays have been removed are condensed by the condenser lens 14 and emitted to the liquid crystal display panel 15. The liquid crystal display panel 15 is supported by a support frame 16. An image signal or a scanning pulse is applied to the liquid crystal display panel 15, and light from the condenser lens 14 is transmitted to display an image on the liquid crystal panel. The support frame 16 is made of polycarbonate (P
Resins such as C) are used.

The light emitted from the liquid crystal display panel 15 is emitted to the projection lens 17 and the emitted light is
By being enlarged and projected at 7, the display image on the liquid crystal panel can be enlarged and projected on a screen (not shown). The electric fan 18 is provided with the liquid crystal display panel 15 and the polarizing plate 1 attached to the liquid crystal display panel 15 described later.
In order to suppress the temperature rise of No. 9, forced cooling is performed.

As described above, in view of projecting a display image on a small area liquid crystal panel with sufficient illuminance and projecting it on a large area screen, the liquid crystal projector is
A very powerful light source is required, and a high output light source such as a metal halide lamp is used. Therefore, since the light beam passes through the liquid crystal panel having a small area, the temperature of the liquid crystal panel tends to increase due to heat rays included in the light beam.
To suppress the temperature rise of the liquid crystal panel, unnecessary infrared rays can be removed between the light source 11 and the condenser lens 14 through the heat ray cut filter 13 or forcedly cooled by the electric fan 18 as described above. Is being done.

The above description is of a single-panel type liquid crystal projector using one liquid crystal display panel. However, instead of using a single-panel type, three liquid crystal display panels are used in correspondence to the three primary colors of RGB light source light. The basic operation is the same in the three-panel liquid crystal projector.

Next, the liquid crystal display panel 15 will be described with reference to FIG.
The liquid crystal display panel 15 used for the liquid crystal projector is
The active matrix method is the mainstream, and the drive substrate has been shifting from an amorphous silicon substrate to a small-sized polysilicon substrate in recent years. The reason for this is that the manufacturing process has been refined, a large number of pixels can be arranged in a small size, and the aperture ratio can be increased as compared with an amorphous silicon substrate. Note that, depending on the manufacturing method, the high-temperature polysilicon substrate is TF
A sufficient countermeasure against light reflected on T (thin film transistor) cannot be taken, and a crosstalk phenomenon occurs due to a leak current of the TFT, which adversely affects image quality.

Therefore, a polarizing plate 19 that transmits light orthogonally polarized with respect to incident light and blocks parallel-polarized light is directly attached to the emission side of the liquid crystal display panel 15 to reduce reflected light. . However, when the polarizing plate 19 is attached, heat is generated in the polarizing plate 19, particularly when the video signal has low luminance, and the heat is transmitted to the liquid crystal display panel 15 to cause a rise in the temperature of the liquid crystal display panel. I have. The heat generated in the polarizing plate 19 is generated by energy conversion by blocking (absorbing) the parallel polarized light.

[0010]

Heretofore, the reduction of heat rays by the heat ray cut filter has not been sufficient, and it has been necessary to reduce the output of the light source or increase the cooling capacity of the electric fan. When the output of the light source is suppressed, there is a problem that the performance of the liquid crystal projector is limited because the illuminance when projected on a large screen is insufficient.

When the cooling capacity of the electric fan is to be increased, the size of the electric fan must be increased or the number of revolutions must be increased, which leads to an increase in the size of the liquid crystal projector itself, an increase in cost, and a large noise. There was a problem that occurs. Furthermore, when the video signal has low luminance, the polarizing plate attached to the liquid crystal display panel
There is a problem that the thermal load becomes very large. The present invention has been made in view of the above problems, and provides a transmissive display device which solves these problems.

[0012]

SUMMARY OF THE INVENTION The present invention provides a liquid crystal display panel for displaying an image, a support frame having a high thermal conductivity for supporting the liquid crystal display panel, and a polarizing plate provided on the emission side of the liquid crystal display panel. And disposed on the output side of the polarizing plate,
A transparent substrate having a high thermal conductivity bonded to the support frame, and a filling provided between the transparent substrate and the polarizing plate and filled with a non-adhesive material that excludes air at the interface between the transparent substrate and the polarizing plate. Unit.

Further, the transparent substrate is formed of sapphire. Further, the filling section is filled with a liquid substance. Further, the filling section is filled with a gel-like substance. Further, the thermal conductivity of the gel-like substance or the liquid substance is 0.1 W / m · k or more. When the filling material is a liquid material, the viscosity is 10%.
cst or more. Further, the distance between the transparent substrate and the polarizing plate is set within 0.5 mm.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view showing a configuration of a peripheral portion of a liquid crystal display panel according to the present invention, and FIGS. 2 and 3 are views for explaining the present invention. In the present invention, a liquid crystal projector will be described as an example. The basic configuration of the liquid crystal projector is the same as that of the conventional example, and the description is omitted.

As shown in FIG. 1, a liquid crystal projector as an example of a transmissive display device according to the present invention includes a liquid crystal display panel 1 for displaying an image, a support frame 2 for supporting the liquid crystal display panel 1, and an incident light. A polarizing plate 3 that transmits orthogonally polarized light and blocks parallel polarized light, a liquid crystal display panel 1 and a transparent substrate 4 that absorbs and radiates heat generated by the polarizing plate 3, a gel material having no adhesive property Alternatively, a filling section 5 for filling a liquid substance is provided. In this liquid crystal projector, although not shown, a video signal and a scanning pulse are applied to the liquid crystal display panel 1.

Next, the operation of the liquid crystal projector will be described. First, high-output light having appropriate polarization enters the liquid crystal display panel 1 from the direction of the arrow shown in FIG. When the incident light passes through the liquid crystal display panel 1, the liquid crystal display panel 1 displays an image based on the above-described video signal on the liquid crystal panel. The luminous flux of the incident light passes through the liquid crystal display panel 1 having a small area, and the temperature of the liquid crystal display panel 1 tends to rise due to heat rays included in the luminous flux. In order to suppress the temperature rise of the liquid crystal panel, it is the same as in the conventional example that a heat ray cut filter is provided between the light source and the condenser lens or the electric fan is forcibly cooled.

The driving substrate of the liquid crystal display panel 1 includes:
A small polysilicon substrate is used. Depending on the manufacturing method, a high-temperature polysilicon substrate cannot take sufficient measures to shield light reflected from the emission side of the liquid crystal display panel to the TFT, and crosstalk occurs due to the leakage current of the TFT, adversely affecting image quality. Exert. Therefore, a polarizing plate 3 that transmits light orthogonal to the incident light and blocks parallel-polarized light is directly attached to the emission side surface of the liquid crystal display panel 1 to reduce reflected light.

In addition, when the video signal is low in luminance due to the attachment of the polarizing plate 3, heat is generated in the polarizing plate 3, and the heat is transmitted to the liquid crystal display panel 1, causing the temperature of the liquid crystal display panel 1 to rise. I have. The heat generated in the polarizing plate 2 is as follows.
It is generated by energy conversion by blocking (absorbing) parallel polarized light. The above is the same as the conventional example.

Therefore, in the present invention, as shown in FIG. 1, a transparent substrate 4 for absorbing and radiating heat generated in the liquid crystal display panel 1 and the polarizing plate 3 is arranged on the exit side of the polarizing plate 3. A transparent substrate 4 is joined to the support frame 2 by using a metal material having good thermal conductivity (for example, aluminum) for the support frame 2, and heat generated in the liquid crystal display panel 1 and the polarizing plate 3 is transmitted from the transparent substrate 4. The heat is radiated to the support frame 2. As a characteristic required for the transparent substrate 4, it is an essential condition that the thermal conductivity is good. As a substrate satisfying this requirement, for example, sapphire is fried. Sapphire has a thermal conductivity of 42 W / m · k, which is about 30 times that of general quartz glass (1.4 W / m · k) used for liquid crystal display panels and the like.

Next, the arrangement of the transparent substrate 4 will be described. Usually, it is conceivable that the transparent substrate 4 and the polarizing plate 3 are bonded so that air does not enter. Therefore, using the configuration of FIG. 1, an experiment was performed by filling the filling section 5 with a general acrylic UV adhesive and bonding the transparent substrate 4 and the polarizing plate 3 using sapphire. In addition,
The liquid crystal display panel used was a 0.9-inch size liquid crystal display panel.

As a result, color unevenness occurred, and even when a relatively flexible silicone rubber was used, slight color unevenness was confirmed. The cause of the color unevenness is that, due to the adhesion (hardening) between the transparent substrate 4 and the polarizing plate 3, stress is generated due to a difference in thermal expansion or Young's modulus, and the cell gap thickness changes. Therefore, it has been found that it is necessary to suppress the change in the cell gap thickness as much as possible, and it is necessary to avoid adhesion between the transparent substrate 4 and the polarizing plate 3.

Next, as a material having no adhesive property, there is a gel-like substance such as silicon gel. As a result of performing the same experiment as that of the adhesive using this silicone gel, no color unevenness occurred. Further, even when a liquid substance such as silicon oil was used, no color unevenness occurred.
Therefore, it has been found that it is necessary to fill a gel-like substance or a liquid substance having no adhesive property as a means for excluding air at the interface between the transparent substrate 4 and the polarizing plate 3 and keeping the air from entering. did.

The upper limit of the operation guarantee temperature of a general liquid crystal is about 70 ° C., and if the upper limit of the surrounding environment is 40 ° C., it is necessary to suppress the temperature rise of the liquid crystal panel within 30 ° C.
Therefore, an environment in which the temperature of the liquid crystal display panel becomes 30 ° C. is set by adjusting the light source output, the electric fan voltage, and the like. In this environment, the material of the support frame 2 and the medium to be filled in the filling portion 5 are changed to dissipate heat. Was confirmed. The configuration was as shown in FIG. 1, and sapphire was used for the transparent substrate 4 and the liquid crystal display panel was 0.9 inch in size.
The result is as shown in FIG.

In FIG. 2, PC is polycarbonate,
AL is aluminum. Since the temperature of the liquid crystal was almost the same as the temperature of the polarizing plate 3, the temperature was measured by measuring the temperature of the polarizing plate 3.

Referring to FIG. 2, the result of confirming the heat radiation effect will be described. First, without a medium to be filled in the filling portion 5 between the polarizing plate 3 and the transparent substrate 4, no heat radiation effect was observed (N
O. 1). The above result shows that the material of the support frame 2 is P
Even if C (thermal conductivity = 0.2 W / mk) was replaced with aluminum having a good thermal conductivity (AL: thermal conductivity = 236 W / mk), there was no change (see NO.2). This is because the thermal conductivity between the polarizing plate 3 and the transparent substrate 4 is very low (about 0.
02W / m · k) Because air is interposed, heat is not efficiently transmitted to the transparent substrate 4. Therefore, a colorless and transparent silicone gel (thermal conductivity = 0.17 W / m · k) is used as the medium.
The confirmation was performed using. The results are as follows.
When the material of the support frame 2 was PC, almost no heat radiation effect was recognized (see NO. 3). This result is also PC
This is because the thermal conductivity of the transparent substrate 4 is low, and heat is not dissipated from the transparent substrate 4 to the support frame 2.

Next, as a result of changing the material of the support frame 2 to AL, a significant heat radiation effect was recognized (see No. 4). In other words, in order to efficiently radiate the heat generated in the liquid crystal display panel 1 and the polarizing plate 3 to the support frame 2 via the transparent substrate 4 without causing color unevenness, the space between the transparent substrate 4 and the polarizing plate 3 is required. A gel-like substance or a liquid substance is filled so that air does not enter.
It was also found that it was necessary to use a metal material having good thermal conductivity such as aluminum.

A medium filled in the interface between the transparent substrate 4 and the polarizing plate 3 has a thermal conductivity of less than 0.1 W / m · k, such as a fluorine-based inert liquid. Poor (see No. 6). However, NO. Silicon gel shown in NO. Like the silicone oil shown in 5,
It was found that the effect was hardly changed if the material exceeded 0.1 W / mk. Therefore, it is desirable that the thermal conductivity of the gel-like substance or the liquid substance filling the interface between the transparent substrate 4 and the polarizing plate 3 is 0.1 W / m · k or more.

Further, when the substance filling the interface between the transparent substrate 4 and the polarizing plate 3 is a liquid substance, it is necessary to consider the influence of convection. The reason is that when there is convection when the image is projected on the screen, the image fluctuates. Therefore, in order to confirm the influence of convection, the interface between the transparent substrate 4 and the polarizing plate 3 is filled with a fluorine-based inert liquid having a viscosity of 1 cst and silicone oil having a viscosity of 10 cst, and projected on a 40-inch screen, and visually observed. The fluctuation was compared. The temperature of the polarizing plate 3 was 30 ° C., and the size of the liquid crystal display panel was 0.9 inch. The results are as shown in FIG.

The result will be described with reference to FIG. In the case of the fluorine-based inert liquid having a viscosity of 1 cst, slight fluctuation was confirmed when the distance (gap) between the transparent substrate 4 and the polarizing plate 3 was 0.5 mm, and fluctuation was clearly confirmed when the distance was 2 mm. In addition, with silicone oil having a high viscosity of 10 cst, no fluctuation was observed even when the distance became 2 mm. Therefore, when the substance to be filled in the interface between the transparent substrate 4 and the polarizing plate 3 is a liquid, it is found that the viscosity is preferably 10 cst or more, or the distance between the transparent substrate 4 and the polarizing plate 3 is preferably 0.5 mm or less. did. In the above description, an example was described in which sapphire was used for the transparent substrate 4. However, the present invention is not limited to sapphire, and any other material having the same thermal conductivity as sapphire can achieve the present invention. It goes without saying that.

As described above, in the transmission type display device of the present invention, the transparent substrate 4 having a high thermal conductivity using, for example, sapphire is arranged on the emission side of the polarizing plate 3, The transparent substrate 4 and the supporting frame 2 are joined by using a metal material having a high efficiency, and the transparent substrate 4 and the polarizing plate 3 are further adhered to each other with a gel-like substance or a liquid substance. The heat generated in 3 is radiated from the transparent substrate 4 to the support frame 2 to efficiently cool the liquid crystal display panel 1 without causing color unevenness.

[0031]

According to the transmission type display device of the present invention, heat generated in the liquid crystal display panel and the polarizing plate is radiated from the transparent substrate to the support frame, and the liquid crystal display panel is efficiently cooled. Therefore, a transmissive display device that can achieve high luminance and low noise can be realized without the problem of insufficient illuminance, large size of the electric fan, and generation of loud noise. According to the transmission type display device of claim 2,
Since a sufficient heat radiation effect can be obtained, the liquid crystal display panel can be more efficiently cooled.

According to the transmission type display device of the third or fourth aspect, the liquid crystal display panel can be efficiently cooled without causing color unevenness. According to the transmission type display device of the fifth aspect, the liquid crystal display panel can be efficiently cooled without lowering the heat radiation capability of the device. According to the transmission type display device of the sixth or seventh aspect, the liquid crystal display panel can be efficiently cooled without causing image fluctuation.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a liquid crystal display panel peripheral portion of a liquid crystal projector which is an example of a transmission type display device according to the present invention.

FIG. 2 is a diagram for explaining the present invention.

FIG. 3 is a diagram for explaining the present invention.

FIG. 4 is a plan view showing a schematic configuration of a conventional liquid crystal projector.

FIG. 5 is a plan view showing a configuration around a conventional liquid crystal display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Support frame 3 Polarizer 4 Transparent substrate 5 Filling part

Claims (7)

[Claims] 1. A liquid crystal display panel for displaying an image, a support frame having a high thermal conductivity for supporting the liquid crystal display panel, and a polarizing plate provided on an emission side of the liquid crystal display panel.
A transparent substrate having a high thermal conductivity, which is disposed on the emission side of the polarizing plate and is bonded to the support frame; and a transparent substrate provided between the transparent substrate and the polarizing plate to exclude air at the interface between the transparent substrate and the polarizing plate. A transmissive display device, comprising: a filling portion that is filled with a substance having no adhesive property. 2. The transmission type display device according to claim 1, wherein the transparent substrate is formed of sapphire. 3. The transmissive display device according to claim 1, wherein the filling section is filled with a liquid substance. 4. The transmissive display device according to claim 1, wherein the filling portion is filled with a gel substance. 5. The transmissive display device according to claim 3, wherein the thermal conductivity of the gel-like substance or the liquid substance is 0.1 W / m · k or more. 6. The transmission type display device according to claim 3, wherein the viscosity of the filling material is 10 cst or more. 7. The distance between the transparent substrate and the polarizing plate is set to 0.5.
The transmissive display device according to claim 3, wherein the distance is within 0.1 mm.