JPH03107123A - Panel heater - Google Patents

Abstract

PURPOSE:To obtain the panel heater of a less temp. distribution by forming the electrode shape of the panel heater to a stripe shape and forming the electrodes wider in a part of the width thereof than the end part on one side. CONSTITUTION:The SnO2 electrodes 2 for heat generation and the Al electrodes 3 for voltage impression are formed on one surface of a glass substrate 1 and the taking-out electrodes 4 are formed on the rear surface in the broadest part (b) of the SnO2 electrodes 2. A liquid crystal cell is connected to a driving circuit in the taking-out electrode part and are driven by incorporating the same into a housing. The heater is simultaneously energized. The tendency to an increase in the temp. nearer the taking-out electrodes of the liquid crystal cell by the heat generation of a driving IC or the like is adjusted in this way and the nearly uniform temp. having a temp. difference as slight as about + or -2 deg.C over the entire surface of the substrate is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin panel heater, and more particularly to a panel heater used for controlling the temperature of a strongly electrostatic liquid crystal display device.

[Prior Art] Various methods are used for panel heaters depending on their purpose, but for example, one used for controlling the temperature of a liquid crystal display device, etc. is a method in which a conductive thin film is deposited on almost the entire surface of a substrate such as glass. A simple method is common, in which the battery is turned on and energized.

[Problem to be solved by the invention] However, with a simple surface heater, heat tends to concentrate at the center of the substrate due to heat diffusion and radiation, and when a large amount of heat is generated or a large area substrate, the temperature distribution within the plane becomes difficult. The problem was that it was difficult to control.

Furthermore, when used to control the temperature of a liquid crystal display device, heat is generated from the mounted electrodes, drive IC, backlight, etc., and it is extremely difficult to uniformly control the temperature of the liquid crystal cell within the housing that contains these elements. Met.

In order to solve this problem, a method has been used in which some or several electrodes are formed in a meandering manner on the substrate and then energized.
- Since the electrode becomes longer, the wiring resistance increases and the amount of heat generated at the same voltage decreases. Particularly in transparent panel heaters used to control the temperature of transmissive liquid crystal display cells, the transmittance of the heater itself is an important factor due to its nature, so it is desirable that the thickness of the transparent electrode be as thin as possible. It is difficult to reduce the amount of heat generated, and when generating a large amount of heat, a high voltage is inevitably required.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and provide a panel heater with uniform temperature distribution on a large-area substrate and relatively low voltage.

[Means and effects for solving the problem] According to the present invention, the electrode shape of the panel heater is striped, and a part of the electrode width is made wider than at least one end, so that the same film thickness can be achieved. By changing the resistance value within the electrode and changing the amount of heat generated, it is possible to reduce the effects of heat diffusion, differences in heat radiation, or other heat sources, thereby stably obtaining a panel heater with uniform temperature distribution. becomes possible.

[Example] Fig. 1 is an example of the electrode shape in the present invention, and in the figure, a is the electrode end width, b is the electrode width at the widest point, and C
is the electrode length, d is the length from the electrode end to the widest electrode width, and p is the pitch between adjacent electrodes.

Further, FIG. 2 shows an example of a panel heater using the electrode shape shown in FIG. 1, in which a plurality of band-shaped electrodes 2 shown in FIG. Formed in stripes. Electric 8i! A low-resistance extraction electrode 3 for applying a voltage is connected to both ends of the electrode 2 .

ITO with specific resistance ρ = 3.0 x 10-' Ωcm was deposited on a glass substrate with dimensions of 300 x 300 mm and thickness of 1 mm by sputtering.
After forming 300 films, photolithography was used to form a film with a=0.5 mm, b=0.
7mm, 0.8mm.

0.9mm, and the side closer to the center of the board is wider, and c=
290mm, d=145mm, p=1.0mm, 1.1
The electrode 2 is formed on almost the entire surface of the substrate so that the electrode 2 is larger near the center of the substrate, corresponding to b in mm and 1.2 mm.

Further, as the voltage applying electrode 3, AC 30 Hz electrodes were connected to both ends of the transparent heat generating electrode to create a panel heater.

When the panel heater was placed in a box with no other heat generation source and AC 30Hz, 100V was applied to the An electrode, a good temperature distribution of 85±1.5°C was obtained for the substrate temperature over the entire surface. .

As another embodiment of the present invention, an example in which the panel heater of the present invention is used to control the temperature of a ferroelectric liquid crystal cell of a liquid crystal display device is shown in FIG.

When a liquid crystal cell is assembled into a housing and driven, the temperature tends to be higher near the lead-out electrode of the liquid crystal cell due to heat generation of the drive IC and the like.

Considering this point, 280x250xt1.1 (mm)
Resistivity 3.5XIO-'Ωc on glass substrate by CVD method
After forming 500 m of SnO2 films, the heating electrode 2 was formed by the same means as in the previous embodiment. The electrode shape is a=1
．． 0mm, b = 1.2mm, 1.4mm, 1.6mm, the closer to the center of the board is wider, c = 240mm, d
=20mm%p=1.4mm11.6mm, 1.8mm
The transparent electrode 2 is formed so that it is larger near the center of the substrate corresponding to b. Furthermore, on the back side of the transparent panel heater on which the An electrode 3 for voltage application was formed, a striped transparent electrode for display was formed on the opposite side with the glass of part b sandwiched therebetween, and a substrate was formed so that an extraction electrode was formed. Two sheets were created and bonded together to create a liquid crystal cell.

A schematic diagram of this liquid crystal cell is shown in FIG.

In FIG. 3, a heat generating Sn is provided on one side of the glass substrate 1.
An O2 electrode 2 and an Aρ electrode 3 for voltage application are formed, and although only one side is shown in the figure, an extraction electrode 4 is formed on the back surface of the widest part (b) of the SnO2 electrode 2.

Take out the liquid crystal cell, connect it to the drive circuit at the electrode part, install it in the casing, and drive it.At the same time, connect the heater to AC30.
When a current of 50 V at Hz was applied, the temperature distribution of the liquid crystal cell in the driving state was 5°C±2°C.

[Effects of the Invention] As explained above, by making the electrode shape of the panel heater into a stripe shape and making a part of the electrode width wider than at least one end, relatively low voltage can be achieved on a large area board. With this, it is possible to create a panel heater that is efficient and has a small temperature distribution.

Further, according to the present invention, it is possible to heat and maintain a large panel using a strong electrostatic liquid crystal at a uniform temperature, so that there is no unevenness in electro-optic response and high-speed driving is possible. Ta.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an example of the electrode shape according to the present invention. FIG. 2 is an explanatory diagram of an example of a panel heater using the electrode shape of FIG. 1. FIG. 3 is an explanatory diagram of an example of the panel heater according to the present invention. It is an explanatory view of an example. Substrate, 2: Heat generation electrode, 3: Voltage application electrode.

Claims (1)

[Scope of Claims] (1) A panel heater in which a plurality of strip-shaped electrodes made of conductive thin films are arranged in parallel on a substrate in a striped manner, and the width of each electrode varies along the longitudinal direction. A panel heater characterized by having a width portion wider than the width of an end portion of the panel heater. (2) The maximum width of the electrode is 1.1 to 3 of the width of one end.
．． The panel heater according to claim 1, wherein the panel heater is 0 times. (3) The panel heater according to claim 1, wherein the electrode is a transparent electrode.(4) Claim 3, wherein the transparent electrode is made of ITO or SnO_2. Panel heater as described. (5) A panel heater in which a plurality of strip-shaped electrodes made of conductive thin films are arranged in parallel on a substrate in a striped manner, and the width of each electrode changes along the longitudinal direction, and the width of each electrode changes from the width of one end. Panel heater for ferroelectric liquid crystal elements with wide parts. (6) The maximum width of the electrode is 1.1 to 3 of the width of one end.
．． A panel heater for a ferroelectric liquid crystal element according to claim 5, characterized in that the temperature is 0 times. (7) A panel heater for a ferroelectric liquid crystal element according to claim 5, wherein the electrode is a transparent electrode. (8) The panel heater for a ferroelectric liquid crystal element according to claim 7, wherein the transparent electrode is made of ITO or SnO_2.