JPH11231277A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the performance degradation of liquid crystal and emission side polarizing board caused by heat by using a transparent heat transfer substrate, which has heat conductivity higher than a specified multiple of that of transparent glass used for a liquid crystal substrate, for the supporting substrate of a polarizing board sheet. SOLUTION: This projector is composed of a transparent heat transfer substrate 1, to stick an emission side light polarizing sheet, liquid crystal panel 2, fly eye lens 3, incident side light polarizing board 7, P/S synthetic prism 8, reflector 4 provided with a lamp, projection lens 5 and casing 6. Concerning such a liquid crystal projector, the transparent head transfer substrate 1 having the heat conductivity higher than 10-fold that of transparent glass used for the liquid crystal substrate is used for the supporting substrate of the polarizing board sheet. Namely, concerning this liquid crystal projector, heat conduction is improved by using the transparent substrate, which has high heat conductivity and eliminates trouble in the arrival of light emitted from the light source at a screen, for the place of high heat load, the heat degradation of the polarizing board is prevented and a function for holding the polarizing sheet is provided as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal projector using a liquid crystal panel. More specifically, the present invention relates to a cooling structure for a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal used in a liquid crystal projector is mainly a TFT liquid crystal, and the material constituting the TFT is a-Si (amorphous silicon) to pol.
It is changing to y-Si (polycrystalline silicon).

[0003] The reason is that a large number of mounted components can be mounted on a liquid crystal substrate, and the manufacturing process has been refined, so that even if a large number of pixels are arranged on a small panel, the aperture ratio is increased as compared with the conventional one. Because it is now possible.

Conventionally, a 3-type a-Si TFT has about 310,000 pixels and an aperture ratio of about 40 to 50%. Recently, the number of pixels is about 480,000 to about 770,000 in a 0.9 to 1.3 type poly-Si, TFT liquid crystal, and the aperture ratio exceeds 50%.

Accordingly, the panel size is reduced to about 1/5 in area, and the number of pixels is increased 1.5 to 2.0 times.

Also, a technique has been developed in which a linearly polarized wave incident on a liquid crystal is efficiently divided into two linearly polarized waves from natural light before the liquid crystal is incident on the liquid crystal (1).
-146064).

[0007] In order to reduce the size of the liquid crystal panel and improve the brightness, the thermal load on the polarizing plate and the liquid crystal panel has increased. Among the polarizers, the heat load of the incident-side polarizer was reduced by the P / S separation and synthesis described above. However, with the improvement in the aperture ratio of the liquid crystal panel, the heat load when the video signal of the output-side polarizer was black was extremely large. It became big.

As a conventional example, a technique disclosed in Japanese Patent Application Laid-Open No. 6-67143 will be described with reference to FIGS.
In these figures, reference numeral 57 denotes a liquid crystal display panel, 511 denotes a liquid crystal panel mounting base, and 516 denotes a radiation fin mounted on the liquid crystal panel mounting base 511.

In this conventional example, the heat accumulated in the liquid crystal display panel is radiated from a mounting base in which a heat radiating portion provided with radiating fins is integrally formed. This conventional example is characterized in that it has both a function of attaching a liquid crystal panel and a heat radiation function.

[0010]

In the above prior art,
When the aperture ratio of the liquid crystal panel was low and the brightness on the screen was not so bright, the effect was effective even with the thermal conductivity (about 1 W / m · K) of the glass substrate (mainly quartz) of the liquid crystal panel.

Recently, the aperture ratio of the liquid crystal panel is high, and the heat load is almost always generated on the output side polarizing plate.
When the brightness level reached the SI lumen level, the temperature rose sharply, and the performance of the liquid crystal and the output side polarizing plate deteriorated.

[0012]

According to the present invention, there is provided a liquid crystal panel, a light source for irradiating the liquid crystal panel with light and projecting the liquid crystal panel on a screen, a color separation / combination means,
In a liquid crystal projector provided with a projection lens, the supporting substrate of the polarizing plate sheet provided on the emission side of the liquid crystal panel is at least 10 times smaller than the transparent glass used for the liquid crystal substrate.
A transparent heat transfer transparent substrate having a thermal conductivity twice or more is used.

According to a second aspect of the present invention, in the liquid crystal projector according to the first aspect, the heat transfer transparent substrate is made of a crystal (sapphire) of alumina (Al ₂ O ₃ ).

According to a third aspect of the present invention, in the liquid crystal projector according to the first or second aspect, an opaque heat radiating plate having better heat conductivity is provided at a portion other than the light transmitting portion of the liquid crystal panel, and the heat radiating plate is provided. In addition, another one having a convex shape is provided on the heat transfer substrate, and the heat conductive substrate has irregularities.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of a liquid crystal projector according to one embodiment. 1 is a heat transfer transparent substrate to which an exit side polarizing sheet is attached, 2 is a liquid crystal panel, 3 is a fly-eye lens, 7 is an incidence side polarizer, 8 is a P / S composite prism, 4 is a reflector including a lamp, and 5 is a projection. A lens 6 indicates a housing.

The process of applying a thermal load to the liquid crystal panel and the exit-side polarizing plate is as follows. The heat flux emitted from the lamp in the reflector 4 is converted by the fly-eye lens 3 and the P / S combining prism 8 into linearly polarized light in the transmission axis direction, which transmits natural light through the incident polarizer 7 of the liquid crystal.

At this time, assuming that the light beam of linearly polarized light that has exited the fly-eye lens 3 and the P / S combining prism 8 is 100,
The parallel light transmittance of the incident side polarizing plate 7 is approximately 80%, and 20% is absorbed by the incident side polarizing plate 7 to become heat.

The light transmitted through the incident side polarizing plate 7 is reflected and transmitted by the aperture ratio of the liquid crystal panel 2 and the reflectance of the black matrix. The aperture ratio of recent liquid crystal panels has been improved due to miniaturization of production processes. The 480,000 pixels of the black and white liquid crystal display exceed 50% for both the 1.3 type and the 0.9 type. Therefore, the following description will be made on the assumption that the aperture ratio is 50%. The heat load applied to the liquid crystal is as follows when the reflectance of the black matrix is set to about 50%.

(Incident light flux) * (non-aperture ratio) * (absorption rate of black matrix) = 80 * (1-0.5) * (1
-0.5) = 20 On the other hand, the heat load applied to the polarizing plate on the emission side is the following two types, that is, the white and black states are the minimum and maximum heat loads.

White: (luminous flux transmitted through the liquid crystal panel) * (1-
(Parallel light transmittance of polarizing plate)) = 80 * 0.50 * (1-
0.8) = 8 For black: (luminous flux transmitted through the liquid crystal panel) * (1-
(Orthogonal transmittance of polarizing plate)) = 80 * 0.50 * 1 = 40 In other words, the output-side polarizing plate has the highest heat load on an occasional basis.

The present invention focuses on this fact, and uses a transparent substrate that has good thermal conductivity at a high heat load and does not hinder the light emitted from the light source from reaching the screen. It is characterized by improving the function of the polarizing plate, preventing thermal deterioration of the polarizing plate, and also having a function of holding the polarizing sheet.

Also, depending on the method of producing the liquid crystal, the po
The ly-Si-TFT cannot effectively take measures to block the reflected light from the emission side to the TFT, and if there is reflected light after exiting the liquid crystal panel, a crosstalk phenomenon occurs due to a leak current of the TFT, resulting in poor image quality. Have a bad effect.

As a countermeasure, an exit-side polarizing plate is attached to the liquid crystal in order to minimize the non-uniform medium after exiting the liquid crystal panel in order to reduce reflected light.

The heat load at this time is due to the heat generation due to the absorption of the liquid crystal panel and the heat absorption of the exit-side polarizing plate. Since the temperature reliability of the liquid crystal panel may be low, it is very effective to efficiently dissipate heat to prevent deterioration of the liquid crystal panel due to a thermal load.

In the above embodiment, the heat transfer transparent plate is described as having a high thermal conductivity of the transparent body itself. However, a substance having a high thermal conductivity is adhered to a transparent body such as ordinary glass. It may be applied to move the amount of heat.

In the above description, the screen brightness is 0.9, which is about 600 ANSI level. However, in the future, when the liquid crystal size becomes smaller and brighter, it will be used as a mounting base for the incident side polarizing sheet. A heat transfer transparent plate having a heat dissipation function may be used.

Further, a heat transfer transparent plate may be used for radiating heat generated by the liquid crystal black matrix or the like.

FIG. 2 is an enlarged front view of the liquid crystal panel of FIG. 2, reference numeral 11 denotes a heat transfer transparent plate, and reference numeral 22 denotes a liquid crystal panel frame.

FIG. 3 is an enlarged side view of the liquid crystal panel of FIG. In FIG. 3, reference numeral 19 denotes an output side polarizing plate.

FIG. 4 shows an embodiment in which the size of the heat transfer transparent plate is increased. In FIG. 4, reference numeral 22 denotes a liquid crystal panel frame.

FIG. 5 is a view showing an example in which a heat radiating plate is attached to a heat transmitting transparent plate. In FIG. 5, reference numeral 39 denotes a heat sink.

FIG. 6 is a diagram showing an example in which a heat pipe is attached to a heat transfer transparent plate. In FIG. 6, reference numeral 43 denotes a heat pipe.

In the embodiment shown in FIGS. 3 to 6,
Although the emission side polarizing plate is attached to the glass substrate of the liquid crystal panel, a heat transfer transparent plate with a polarizing plate may be used separated from the liquid crystal panel.

Hereinafter, the thermal conductivity (K) of the main materials used in the present invention will be described.

Transparent body Quartz glass: ０．０１0.014 J / cm · SK Alumina (Al ₂ O ₃ ): ０．２0.21 J / cm · SK Sapphire: ０．４0.4 J / cm · SK Metal Al : Up to 2.3 J / cm-SK Gold: up to 3.1 J / cm-SK Silver: up to 4.0 J / cm-SK Copper: up to 3.8 J / cm-SK

[0037]

Since it is necessary to limit the temperature rise of the liquid crystal panel, the amount of light reaching the screen has conventionally been limited. That is, since the area of the small liquid crystal, for example, 0.9 type is half that of the conventional 1.3 type, assuming that the aperture ratio of the liquid crystal panel is the same, the brightness, which is the source of the heat load, is approximately 1 /. It was necessary to hold down to 2.

However, according to the present invention, since the performance is not degraded by heat, even if the area is half, it is possible to transmit a light amount substantially equal to or larger than that of the conventional case.

[Brief description of the drawings]

FIG. 1 is a side view of a liquid crystal projector of the present invention.

FIG. 2 is a front view of a liquid crystal panel and an output side polarizing plate of the present invention.

FIG. 3 is a side view of a liquid crystal panel and an output side polarizing plate of the present invention.

FIG. 4 is a view showing an embodiment in which the size of the heat transfer transparent substrate of the present invention is increased and the frame is formed of metal.

FIG. 5 is a view showing an embodiment in which a heat radiating plate is attached to the heat transfer transparent substrate of the present invention.

FIG. 6 is a view showing an embodiment in which a heat pipe is attached to the heat transfer transparent substrate of the present invention.

FIG. 7 is a side view of a conventional liquid crystal projector.

FIG. 8 is a side view of a conventional liquid crystal panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat transfer transparent substrate 2 Liquid crystal panel 7 Incident side polarizing plate 43 Heat pipe 39 Heat sink 22 Liquid crystal panel frame

Claims (3)

[Claims] 1. A liquid crystal projector comprising a liquid crystal panel, a light source for irradiating the liquid crystal panel with light and projecting the light on a screen, a color separation / synthesis unit, and a projection lens, provided on an emission side of the liquid crystal panel. A liquid crystal projector characterized by using a transparent heat transfer transparent substrate having a thermal conductivity at least 10 times higher than that of a transparent glass used for a liquid crystal substrate for heat transfer and heat dissipation of a polarizing plate and liquid crystal. 2. A liquid crystal projector according to claim 1, wherein said heat transfer transparent substrate is made of a crystal (sapphire) of alumina (Al ₂ O ₃ ). 3. The liquid crystal projector according to claim 1, further comprising an opaque heat radiator having better heat conductivity at a position other than the light transmitting portion of the liquid crystal panel, wherein the heat radiator is convex on the heat transfer substrate. A liquid crystal projector comprising a heat conductive substrate provided with an irregular shape and irregularities.