JP2005049558A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which a liquid crystal display panel can be efficiently heated by a panel heater and high-quality liquid crystal display is realized at a low cost as a result. <P>SOLUTION: The liquid crystal display has a panel heater stuck with a cohesive material to the outside surface in the thickness direction of the liquid crystal display panel, wherein the thermal conductivity of the cohesive material 18 is specified to ≥0.5 (W/m×K). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Industrial application fields]
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a panel heater for warming a liquid crystal display panel is adhered to an outer surface in a thickness direction of the liquid crystal display panel through an adhesive material.
[0002]
[Prior art]
Conventionally, in a liquid crystal display device used for in-vehicle use or the like, a panel heater for warming the liquid crystal of the liquid crystal display panel has been mounted in order to improve the response speed of the liquid crystal at a low temperature.
[0003]
In general, the panel heater has a transparent conductive film made of indium tin oxide (ITO) or the like on a heater substrate made of glass or the like, and an electrode provided in the panel heater is connected to the transparent conductive film. The transparent conductive film is caused to generate heat by applying a voltage. Then, the heat of the transparent conductive film moves to the liquid crystal display panel side, so that the liquid crystal display panel is warmed.
[0004]
Further, as an example, the panel heater is mounted on a liquid crystal display device by being adhered to the surface of the liquid crystal display panel opposite to the viewing side via an adhesive material.
[0005]
As an adhesive material used for adhesion of such a panel heater, conventionally, an adhesive material having an adhesive layer made of an acrylic polymer on both surfaces of a base material made of a polyester film has been used.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-235732
[Problems to be solved by the invention]
By the way, in the liquid crystal display device in which the panel heater is adhered to the liquid crystal display panel through the adhesive material as described above, heat transfer is performed if the heating surface of the panel heater and the facing surface of the liquid crystal display panel are in close contact with each other. However, if there is a partial contact portion, display defects such as interference fringes will occur. For this reason, a gap is provided between the heat generating surface of the panel heater and the facing surface of the liquid crystal display panel. Therefore, the heat transfer of the panel heater to the liquid crystal display panel side is performed by heat transfer through the air in the gap existing between the heat generating surface of the panel heater and the facing surface of the liquid crystal display panel. It is also done by heat conduction through adhesive.
[0008]
However, in the conventional liquid crystal display device, since the thermal conductivity of the adhesive material was low, the liquid crystal display panel could not be efficiently warmed through the heat conduction of the air layer and the adhesive material in the gap, and the rate of temperature increase was improved. In addition, there is a problem that power consumption cannot be reduced.
[0009]
On the other hand, it is conceivable to form a transparent conductive film directly on the surface of the substrate of the liquid crystal display panel. However, in this case, the polarizing plate is directly warmed, so that appropriate polarization can be obtained by thermal deformation of the polarizing plate. However, there is a concern that the display quality may be impaired.
[0010]
The present invention has been made in view of such a problem, and a liquid crystal display device capable of efficiently heating a liquid crystal display panel by a panel heater and thus realizing a high-quality liquid crystal display at a low cost. It is intended to provide.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the liquid crystal display device according to claim 1 of the present invention is characterized in that a panel heater for heating the liquid crystal display panel is adhered to the outer surface in the thickness direction of the liquid crystal display panel through an adhesive material. In the liquid crystal display device, the thermal conductivity of the adhesive material is 0.5 (unit: W / m · K, hereinafter omitted) or more.
[0012]
And according to such a structure, since heat conduction through an adhesive material can be improved, it becomes possible to warm a liquid crystal display panel efficiently with a panel heater.
[0013]
The liquid crystal display device according to claim 2 is characterized in that, in claim 1, the adhesive material has an adhesive layer in which at least aluminum oxide is mixed in an acrylic polymer.
[0014]
And according to such a structure, the outstanding heat conduction through an adhesive material can be obtained easily, and also it becomes possible to reduce cost.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a liquid crystal display device according to the present invention will be described with reference to FIGS.
[0016]
As shown in FIG. 1, the liquid crystal display device 1 in the present embodiment has a panel heater 3 for warming the liquid crystal display panel 2 on the non-viewing side of the liquid crystal display panel 2.
[0017]
The liquid crystal display panel 2 includes two substrates 5 and 6 on the viewing side and the non-viewing side made of glass or the like bonded to each other via a seal 4. A liquid crystal 7 is sealed in the enclosed space.
[0018]
A pair of display electrodes 8 and 9 made of indium tin oxide (ITO) or the like is formed on the inner side in the thickness direction of both substrates 5 and 6, and an alignment film or the like is formed on the inner side of both display electrodes 8 and 9. A thin film layer (not shown) is formed.
[0019]
Further, a terminal portion 6a having a lead terminal 9a for the display electrode 9 is formed on the substrate 6 on the counter-viewing side, and a driver IC 11 for driving liquid crystal is mounted on the terminal portion 6a. . Not only the above-mentioned COG system but a flexible wiring board may be connected to the terminal portion 6a.
[0020]
Polarizing plates 12 and 13 are formed outside the two substrates 5 and 6 in the thickness direction, and the polarizing directions 12 and 13 regulate the vibration direction of the transmitted light that passes through the liquid crystal 7. It has become.
[0021]
The panel heater 3 has a transparent conductive film 16 made of indium tin oxide or the like on the surface of the heater substrate 15 made of glass or the like (the surface on the viewing side in FIG. 1). 3 is a heating surface.
[0022]
The transparent conductive film 16 generates heat based on thermal resistance by applying a voltage from an external drive circuit via an electrode (not shown) formed on the transparent conductive film 16.
[0023]
As shown in FIG. 2, the panel heater 3 is adhered to the polarizing plate 13 on the non-viewing side of the liquid crystal display panel 2 through a planar frame-shaped adhesive material 18.
[0024]
Alternatively, the outer shape of the polarizing plate 13 on the anti-viewing side may be formed small in advance, and the flat frame-shaped adhesive material 18 may be adhered to the substrate 6 on the anti-viewing side of the liquid crystal display panel 2.
[0025]
In the present embodiment, the adhesive material 18 has a thermal conductivity of 0.5 or more.
[0026]
In addition, as the said adhesive material 18, you may use a heat conductive adhesive transfer tape (No. 9882, 9885, 9880) (Sumitomo 3M Co., Ltd.) etc., for example.
[0027]
Therefore, the heat of the panel heater 3 can be effectively transferred to the liquid crystal display panel 2 side through the heat conduction by the adhesive material 18, and the liquid crystal display panel 2 can be efficiently warmed.
[0028]
In addition, by providing a certain gap corresponding to the thickness of the adhesive material 18 between the liquid crystal display panel 2 and the panel heater 3, thermal deformation of the polarizing plate 13 can be avoided.
[0029]
Furthermore, in this embodiment, the adhesive material 18 has an adhesive layer 19 in which aluminum oxide is mixed in an acrylic polymer. The composition ratio of the adhesive layer 19 is preferably 20 to 45% by weight of acrylic polymer and 55 to 80% by weight of aluminum oxide.
[0030]
In this way, the manufacturing cost can be further reduced by simply configuring the pressure-sensitive adhesive layer 19 having excellent thermal conductivity.
[0031]
Next, the operation of this embodiment will be described.
[0032]
In the present embodiment, in order to warm the liquid crystal display panel 2 by the panel heater 3, a voltage is applied to the transparent conductive film 16 of the panel heater 3 via an electrode provided on the panel heater, whereby the transparent The conductive film 16 generates heat.
[0033]
The heat of the transparent conductive film 16 moves to the liquid crystal display panel 2 side mainly by heat transfer through the gap between the panel heater 3 and the liquid crystal display panel 2 and heat conduction through the adhesive material 18.
[0034]
At this time, since the adhesive 18 has a high thermal conductivity of 0.5 or more, the heat of the panel heater 3 can be efficiently transferred to the liquid crystal display panel 2 side.
[0035]
As a result, the temperature increase rate of the liquid crystal 7 is improved, and the response speed of the liquid crystal 7 is improved at a low temperature. Therefore, the liquid crystal display panel 2 can be appropriately driven while suppressing the power consumption required for driving the panel heater. .
[0036]
Therefore, according to the present embodiment, the liquid crystal display panel 2 can be efficiently warmed by the panel heater 3 by using the inexpensive adhesive material 18 having excellent thermal conductivity. The display device can be driven inexpensively and appropriately.
[0037]
In addition, this invention is not limited to the thing of the said embodiment, A various change is possible as needed.
[0038]
For example, the adhesive material may be formed by providing the adhesive layer 19 on both surfaces of an aluminum foil or a copper foil. In this case, it is possible to further improve the thermal conductivity of the adhesive material. Examples of such an adhesive material include a heat conductive double-sided tape (# 8530AD, # 8535ADC) (Dainippon Ink and Chemicals).
[0039]
Moreover, you may make it form an adhesive material by providing the said adhesion layer 19 on both surfaces of the thin base material which consists of polyesters. Even in this case, the liquid crystal display panel 2 can be efficiently warmed by the high thermal conductivity of the adhesive.
[0040]
Furthermore, you may make it form the adhesion layer 19 by mixing powder, such as silicon carbide, with an aluminum oxide in an acrylic polymer.
[0041]
Further, the present invention can be applied to any liquid crystal display device of transmissive type and reflective type or transflective type.
[0042]
【The invention's effect】
As described above, according to the liquid crystal display device of the first aspect of the present invention, a liquid crystal display device excellent in display quality particularly at low temperatures can be realized at low cost.
[0043]
According to the liquid crystal display device according to the second aspect, in addition to the effect of the liquid crystal display device according to the first aspect, a liquid crystal display device excellent in display quality particularly at a low temperature can be realized at a lower cost.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view schematically showing an embodiment of a liquid crystal display device according to the present invention. FIG. 2 is a schematic plan view of FIG.
DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal display panel 3 Panel heater 13 Polarizing plate 18 Adhesive material 19 Adhesive layer

Claims (2)

In the liquid crystal display device in which a panel heater for warming the liquid crystal display panel is adhered to the outer surface in the thickness direction of the liquid crystal display panel via an adhesive material,
The adhesive material has a thermal conductivity of 0.5 (unit: W / m · K) or more. The liquid crystal display device according to claim 1, wherein the adhesive material has an adhesive layer in which at least aluminum oxide is mixed in an acrylic polymer.

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