JP2007199153A - Reflective liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflective liquid crystal display having a structure wherein generation of stress generated by contraction due to curing of an adhesive used when a reflective liquid crystal display cell is fixed is eliminated, heat radiation of the reflective liquid crystal display cell is satisfactorily performed and generation of thermal stress between the reflective liquid crystal display cell and a heat radiation member can be suppressed. <P>SOLUTION: The reflective liquid crystal display has the structure wherein the reflective liquid crystal display cell is disposed on a cell fixing member having a through hole smaller than a planar shape of the reflective liquid crystal display cell in the center part thereof, at least a part of the aera in the vicinity of the through hole is fixed to the cell fixing member by using the adhesive and the heat radiation member comes in contact with a rear surface of a silicon substrate through the through hole via a heat transfer material and is fixed to the cell fixing member in a pressed state by a spring member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reflective liquid crystal display device, and more particularly, to a reflective liquid crystal display cell mounting and heat dissipation structure.

  In recent years, a reflection type liquid crystal display device is widely used as a display device for projecting an image in a projector device or a projection television. As shown in FIG. 4, the reflective liquid crystal display device includes a portion called a reflective liquid crystal display cell having a structure in which a liquid crystal layer 3 is sealed between a transparent substrate 1 and a silicon substrate 2, and the reflective liquid crystal display. The cell fixing member 4 is configured to bond and fix the cell with an adhesive 8 or the like. Further, in the reflection type liquid crystal display cell, a transparent electrode (not shown) is formed on the entire lower surface of the transparent substrate 1 facing through the liquid crystal layer 3, and an active matrix driving circuit and an active matrix driving are formed on the upper surface of the silicon substrate 2. Pixel electrodes (not shown) controlled and driven by a circuit are formed.

  In image projection, irradiation light that is linearly polarized light enters from the upper surface of the transparent substrate 1, passes through the liquid crystal layer 3, is reflected from the upper surface of the silicon substrate 2, and exits the transparent substrate 1 again. The polarization state of incident light is modulated by the liquid crystal layer 3 according to the image information voltage applied between the transparent electrode and the pixel electrode, and the irradiation light emitted from the transparent substrate 1 has image information.

  This reflective liquid crystal display cell is fixed to the cell fixing member 4 with an adhesive 8, but the adhesive used here contracts when cured, which causes the silicon substrate 2 to deform and the liquid crystal layer 3. The thickness of the film partially changes. For this reason, the polarization state of incident light fluctuates, causing a problem that the quality of the projected image deteriorates.

  Further, since this reflection type liquid crystal display cell receives extremely strong light from the light source, the temperature rises considerably due to light absorption when reflecting irradiation light and heat transfer inside the set. At this time, if the temperature of the reflective liquid crystal display cell rises excessively, the liquid crystal layer thickness (cell gap) changes due to the difference in the coefficient of linear expansion between the constituent members, and the projected image quality deteriorates. Furthermore, birefringence occurs in the transparent substrate 1 due to the thermal stress generated at this time. This birefringence partially changes the polarization state of the emitted light, which significantly degrades the quality of the projected image.

  Therefore, the reflection type liquid crystal display device suppresses the thermal stress applied to the reflection type liquid crystal display cell due to the difference in linear expansion coefficient between the members constituting the reflection type liquid crystal display device, and the reflection type liquid crystal display cell. How to dissipate heat with respect to the irradiation light of extremely strong light from the light source is an important issue for maintaining good projection image quality.

In order to solve the above problem, Patent Document 1 discloses a technique for suppressing stress generated in a reflective liquid crystal display cell. That is, in this patent document, as shown in FIG. 5, a cell fixing member 4 for fixing a reflective liquid crystal display cell composed of a silicon substrate 2, a transparent substrate 1 and a liquid crystal layer 3 is larger than the silicon substrate 2 and is transparent. A hole narrower than the first width in the first direction (width in the left-right direction) is provided, the silicon substrate 2 is disposed in the hole, and both ends of the transparent substrate 1 in the first direction are the cell fixing member 4 and the adhesive 8. The structure fixed by is adopted.
With this structure, since there is no portion where the silicon substrate 2 and the cell fixing member 4 are bonded, the stress of the silicon substrate 2 due to shrinkage that occurs when the adhesive is cured can be suppressed.

  Patent Document 2 below discloses a fixing means that suppresses deformation due to thermal stress and a structure that can efficiently dissipate heat. The first example is shown in FIG. In this structure, the reflective electro-optical device 10 is affixed to the element holder 11 which is a cell fixing member by a silicon resin adhesive applied to the entire back side of the silicon substrate, and the element holder 11 is fixed to the element holder by screws 12. It is fixed by being attached to the plate 13. The element holder fixing plate 13 is fixed to the projector main body by a structure not shown.

  At this time, the element holder 11 is formed of an aluminum alloy having excellent thermal conductivity, and has slit-shaped fin-shaped portions integrally molded in a direction parallel to the left and right sides of the reflective electro-optical device 10. Thus, by using a part of the element holder 11 that is a cell fixing member as a heat radiating means of the fin-shaped portion, the contact area with air is increased and the heat radiating effect of the cell fixing member is enhanced. Furthermore, since the silicon resin adhesive is generally more elastic than the epoxy resin adhesive, the thermal expansion difference between the reflective electro-optical device 10 and the element holder 11 can be absorbed and reduced.

As shown in FIG. 6B, the second example of the efficient heat dissipation structure disclosed in Patent Document 2 is affixed to the element holder base 14 which is a base member, as shown in FIG. The element holder base 14 is joined to a heat sink 15 as a heat radiating means by an adhesive having excellent heat conductivity. At this time, the element holder base 14 is made of a stainless material close to the linear expansion coefficient of silicon constituting the drive substrate of the reflective electro-optical device 10, and the heat sink 15 is aluminum having a thermal conductivity superior to that of the element holder base 14. It is composed of an alloy material.
Japanese Patent Laid-Open No. 10-20324 JP 2001-125200 A

  However, although Patent Document 1 is effective in suppressing the stress of the reflective liquid crystal display cell that occurs when the adhesive is cured, this structure does not sufficiently dissipate the reflective liquid crystal display cell, and there has been a demand in recent years. Light irradiation from a powerful light source for realizing a strong and bright projector has a problem that the temperature rises too much and normal operation cannot be performed.

  In the first example of Patent Document 2, since the element holder base also serves as a heat radiating member, the linear thermal expansion coefficient close to the silicon substrate required for the element holder base and the high thermal conductivity required for the heat radiating member. However, in the second example, the heat radiation from the silicon substrate is performed through the element holder base having a close linear thermal expansion coefficient. When using a metal such as stainless steel in order to bring the linear expansion coefficient of the element holder base close to that of the silicon substrate, the heat conductivity of stainless steel is as low as 1/10 or less that of aluminum, so that the overall heat dissipation capability is significantly reduced. Is.

  The present invention has been made in view of such conventional problems, and eliminates the generation of stress caused by shrinkage caused by curing of the adhesive when fixing the reflective liquid crystal display cell, and the reflective liquid crystal display cell. An object of the present invention is to provide a reflective liquid crystal display device having a structure capable of sufficiently radiating heat and suppressing generation of thermal stress between the reflective liquid crystal display cell and the heat radiating member.

The present invention includes the following configurations (1) and (2) as means for solving the above-described problems. That is,
(1) A reflection type liquid crystal display cell having a structure in which a liquid crystal layer is sealed between a transparent substrate and a silicon substrate, a cell fixing member for adhering and fixing the reflection type liquid crystal display cell, and the reflection type liquid crystal display cell In a reflective liquid crystal display device composed of a heat dissipating member for dissipating heat,
While the reflective liquid crystal display cell is bonded and fixed to the cell fixing member, the edge of the transparent substrate is closed so that the transparent substrate closes a through hole formed in the cell fixing member.
A liquid crystal layer sealed on the lower side of the transparent substrate, the silicon substrate, and a heat transfer material provided on the lower surface side of the silicon substrate are accommodated in the through hole and provided on the lower surface side of the heat transfer material. Provided is a reflection type liquid crystal display device in which the heat radiating member is fixed to the cell fixing member via a spring member.
(2) a reflective liquid crystal display cell having a structure in which a liquid crystal layer is sealed between a transparent substrate and a silicon substrate, a cell fixing member for adhering and fixing the reflective liquid crystal display cell, and the reflective liquid crystal display cell In a reflective liquid crystal display device composed of a heat dissipating member for dissipating heat,
In the reflective liquid crystal display cell, an edge of the silicon substrate is bonded and fixed to the cell fixing member so that the silicon substrate provided below the liquid crystal layer closes a through hole formed in the cell fixing member. While
The heat transfer material provided on the lower surface side of the silicon substrate and a part of the heat radiation member portion provided on the lower surface side of the heat transfer material are accommodated in the through hole, and the heat radiation member portion is disposed in the cell fixing member. A reflective liquid crystal display device is provided, which is fixed to a spring member via a spring member.

  According to the present invention, since the cell fixing member for fixing the reflective liquid crystal display cell and the heat radiating member for releasing the heat generated by the reflective liquid crystal display cell are independent, it is possible to use materials having appropriate characteristics. It becomes possible. That is, the cell fixing member can select a member that focuses on the linear expansion coefficient and dimensional stability, and the heat radiating member can perform an inexpensive member selection that focuses on the thermal conductivity. Further, since the heat radiating member is structured to be pressed directly against the lower surface of the silicon substrate by the force of the spring through the heat transfer material, it is mechanical between the heat radiating member and the silicon substrate in a direction parallel to the facing surface. Therefore, a reflective liquid crystal display device capable of efficiently radiating heat without generating thermal stress due to a difference in linear expansion coefficient can be provided.

  Hereinafter, a reflective liquid crystal display device according to each embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a reflective liquid crystal display device according to the present invention, where (a) is a plan view, (b) is a cross-sectional view along AA, (c) is a side view, and (d). Is a bottom view. FIG. 2 is a view showing a structure of a reflective liquid crystal display device according to the present invention, which is a modified example in which the heat dissipation effect is enhanced as compared with FIG. 1. FIG. 3 is a view showing a structure of a reflective liquid crystal display device according to the present invention. It is a figure of the example of a different structure of a fixed part.

First, the configuration of a reflective liquid crystal display device according to the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structural member of the same name as the said prior art example.
In FIGS. 5A, 5B, and 5C, a reflection type liquid crystal display cell in which a portion composed of a transparent substrate 1, a silicon substrate 2, and a liquid crystal layer 3 is integrated. This reflection type liquid crystal display cell is fixed to the cell fixing member 4. In this embodiment, as shown in FIG. 5C, the reflection type liquid crystal display cell is bonded and fixed to the peripheral portion of the transparent substrate 1 using an adhesive 8.

In order to adopt such a fixing method, a large through hole having a substantially similar shape that is slightly larger than the outer shape of the silicon substrate 2 is formed in the center of the cell fixing member 4. The liquid crystal layer 3 enters.
In order to bond and fix the reflective liquid crystal display cell, at least a pair of opposing sides of the transparent substrate 1 is longer than the side of the through hole, and the transparent substrate 1 is placed on the cell fixing member 4. It is fixed with.

  At this time, the material of the cell fixing member 4 to which the reflective liquid crystal display cell is fixed is preferably a material as close to the linear expansion coefficient of the transparent substrate 1 as possible. In this way, since the thermal expansion generated when the temperature of the reflective liquid crystal display cell rises can be minimized by bringing the linear expansion coefficients of the two close to each other, the transparent substrate 1 generated by the conventional generated thermal stress. It is possible to prevent a phenomenon in which the quality of the projected image is deteriorated due to the birefringence or the cell gap variation.

  For the same reason, a material whose linear expansion coefficient of the transparent substrate 1 is close to the linear expansion coefficient of the silicon substrate is used. Therefore, the linear expansion coefficient of the cell fixing member 4 is eventually a material close to the linear expansion coefficient of the silicon substrate 2. Become. In consideration of dimensional stability and chemical stability, the cell fixing member 4 is preferably a sintered material called engineering ceramics, and silicon carbide, silicon nitride, aluminum nitride, and the like are particularly preferable.

  Next, in the present embodiment, as shown in FIG. 4B, a heat radiating member 5 is attached to the lower surface of the silicon substrate 2 via a heat transfer material 6 to generate heat generated by the reflective liquid crystal display cell. It has a structure to escape. The heat radiating member 5 used here is preferably aluminum or copper having a high thermal conductivity.

The heat transfer material 6 is made of silicon grease having a particularly high thermal conductivity, or a material in which fine metal powder is mixed in silicon grease to increase the thermal conductivity. Since this material does not have an elastic component as a mechanical property, even if there is a large linear expansion coefficient separation between the silicon substrate 2 and the heat dissipation member 5, thermal stress due to the heat dissipation member 5 is generated in the reflective liquid crystal display cell. There is a feature that does not. Therefore, the heat dissipating member 5 can be made of a material that prioritizes heat dissipation as described above.
However, since the heat transfer material 6 does not have an adhesive force to hold the heat radiating member 5 like an adhesive, in this embodiment, as shown in FIGS. A structure in which the heat dissipating member 5 is held against the silicon substrate 2 is adopted.

  As described in detail above, in the configuration of the embodiment according to the present invention, the cell fixing member 4 that fixes the reflective liquid crystal display cell and the heat radiating member 5 that releases the heat generated by the reflective liquid crystal display cell are independent of each other. Therefore, it is possible to use materials having properties suitable for each. That is, the cell fixing member 4 can perform member selection paying attention to the linear expansion coefficient and dimensional stability, and the heat radiation member 5 can perform member selection paying attention to the thermal conductivity.

  Further, since the heat radiating member 5 has a structure in which the heat radiating member 5 is pressed directly against the lower surface of the silicon substrate 2 by a spring force through a heat transfer material 6 mainly having only a viscous resistance component. Since a mechanical degree of freedom is generated in the direction parallel to the opposing surface, efficient heat dissipation is possible without generating thermal stress due to the difference in linear expansion coefficient.

  Furthermore, according to the configuration of the present invention, as shown in FIG. 2, the fin portion of the heat dissipating member 5 can be arbitrarily expanded so that a structure for further enhancing the heat dissipating effect is possible, and the reflective liquid crystal display The stability of the device is improved.

  In the present embodiment, the fixing portion for fixing the reflective liquid crystal display cell to the cell fixing member 4 is performed around the transparent substrate 1, but the configuration according to the present invention is not limited to this and is shown in FIG. Thus, it is also possible to carry out at the left and right ends of the back surface of the silicon substrate 2. This is because the application site of the adhesive 8 is outside the liquid crystal layer 3 and thus is less susceptible to shrinkage when the adhesive is cured. With this structure, the present invention can be applied even when the shape of the reflective liquid crystal display cell is already determined and the shape of the transparent substrate 1 cannot be changed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows one Example of the reflective liquid crystal display device based on this invention, (a) is a top view, (b) is AA sectional drawing, (c) is a side view, (d) is a bottom view. is there. It is a figure of the modification which improves the heat dissipation effect from FIG. 1 with the structure of the reflection type liquid crystal display device which concerns on this invention. It is a figure of the structural example from which the structure of the reflection type liquid crystal display device which concerns on this invention differs in FIG. It is a block diagram of the conventional reflection type liquid crystal display device. It is a block diagram of the conventional reflection type liquid crystal display device with which one part was improved. It is a block diagram of the conventional reflection type liquid crystal display device with which one part was improved.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2 ... Silicon substrate 3 ... Liquid crystal layer 4 ... Cell fixing member 5 ... Heat radiating member 6 ... Heat-transfer material 7 ... Leaf spring 8 ... Adhesive

Claims (2)

A reflective liquid crystal display cell having a structure in which a liquid crystal layer is sealed between a transparent substrate and a silicon substrate, a cell fixing member for adhering and fixing the reflective liquid crystal display cell, and heat dissipation from the reflective liquid crystal display cell In a reflection type liquid crystal display device composed of a heat dissipation member for
While the reflective liquid crystal display cell is bonded and fixed to the cell fixing member, the edge of the transparent substrate is closed so that the transparent substrate closes a through hole formed in the cell fixing member.
A liquid crystal layer sealed on the lower side of the transparent substrate, the silicon substrate, and a heat transfer material provided on the lower surface side of the silicon substrate are accommodated in the through hole and provided on the lower surface side of the heat transfer material. A reflection type liquid crystal display device, wherein the heat radiation member is fixed to the cell fixing member via a spring member. A reflective liquid crystal display cell having a structure in which a liquid crystal layer is sealed between a transparent substrate and a silicon substrate, a cell fixing member for adhering and fixing the reflective liquid crystal display cell, and heat dissipation from the reflective liquid crystal display cell In a reflection type liquid crystal display device composed of a heat dissipation member for
In the reflective liquid crystal display cell, an edge of the silicon substrate is bonded and fixed to the cell fixing member so that the silicon substrate provided below the liquid crystal layer closes a through hole formed in the cell fixing member. While
The heat transfer material provided on the lower surface side of the silicon substrate and a part of the heat radiation member portion provided on the lower surface side of the heat transfer material are accommodated in the through hole, and the heat radiation member portion is disposed in the cell fixing member. A reflection-type liquid crystal display device, wherein the reflection-type liquid crystal display device is fixedly provided via a spring member.

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