JPH03116016A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain the display being free from a residual image and having a high contrast without providing a complicated driving circuit by allowing a heating heater to combine a light shielding layer for masking a non-image display part. CONSTITUTION:The liquid crystal display device is provided with an electrode group in which each electrode 1, 1 is placed crossing while opposing each other by inserting and holding a liquid crystal 5, a temperature control means 7 for keeping a temperature of the liquid crystal constant, and a driving means for forming a picture element in a crossing part of each electrode by applying a voltage to the electrode group and driving the liquid crystal 5, and the temperature control means 7 is provided with an electric heat generating part for masking a non-picture element display part between each picture element, and by bringing it to electric conduction, a temperature of the liquid crystal is kept constant. In such a case, the electric heat generating part is allowed to combine a light shielding layer for masking the non-image display part (between picture elements). In such a way, a ferroelectric liquid crystal display device being free from a residual image and having a high contrast can be realized without providing a complicated driving circuit.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention aims to improve the display quality, especially in high-speed telephone liquid crystal display devices, by making the heater also serve as a light-shielding layer that hides the non-image display area. The present invention relates to a liquid crystal display device.

[Prior Art] Conventionally, a ferroelectric liquid crystal element, for example, as shown in FIG.
Pixel electrodes 1°1° (usually I
After forming a transparent electrode (using a transparent electrode such as TO) using photolithography technology, alignment treatment is performed by rubbing a polyimide film, and a ferroelectric liquid crystal (for example, C5-1014 (manufactured by Chisso Corporation)) is placed between the upper and lower glass substrates. It was composed of enclosed.

[Problems to be Solved by the Invention] However, when driving the elements of the above conventional example in a matrix,
Because the switching characteristics of ferroelectric liquid crystals are sensitive to temperature changes, it was necessary to change the drive waveform as the environmental temperature changes. Also, a method has been considered to counteract the effects of temperature changes by equalizing the temperature of the liquid crystal display element using an external heater.

On the other hand, another drawback of ferroelectric liquid crystal elements is the afterimage phenomenon when switching images, but little has been disclosed about means for reducing this phenomenon. The main cause of afterimages in ferroelectric liquid crystal elements is considered to be largely influenced by the switching characteristics of the liquid crystal located on the pixel display area 2' (hereinafter referred to as "between pixels"), which is the space between the upper and lower pixel electrodes. That is, since the part of the liquid crystal between the pixels switches with a delay of several hundred meters to several seconds after the liquid crystal on the pixel electrode, the display on the display screen is recognized as an afterimage when switching images.

In view of the problems of the prior art, an object of the present invention is to
An object of the present invention is to enable display with no afterimage and high contrast without a complicated drive circuit in a liquid crystal display device.

[Means for Solving the Problem] In order to achieve the above object, the present invention includes a liquid crystal, a group of electrodes arranged so that the electrodes intersect and face each other with the liquid crystal in between, and a temperature control device that keeps the temperature of the liquid crystal constant. In a liquid crystal display device comprising a control means and a driving means for applying a voltage to a group of electrodes to drive the liquid crystal to form a pixel at the intersection of each electrode, the temperature control means It has an electric heat generating part that hides the display part, and is configured to keep the temperature of the liquid crystal constant by supplying electricity to this part.

For example, the electric heat generating portion is formed in a stripe shape on both substrates on which electrode groups are formed facing each other with a liquid crystal in between, or in a mesh on one of the substrates on which electrode groups are formed on opposite sides with a liquid crystal in between. formed into a shape.

Ferroelectric liquid crystal is usually used as the liquid crystal.

[Function] In this configuration, when the liquid crystal display device is driven in a matrix, the switching characteristics of the ferroelectric liquid crystal change sensitively to temperature changes, but since the temperature of the liquid crystal is controlled to be constant by the heating control means, Good display can be performed without the need to change the waveform of the voltage applied to the electrode group. Also,
The liquid crystal in the non-pixel display area between each pixel switches several hundred m5ec to several seconds later than the liquid crystal in the pixel area, but
Since the electric heat generating portion hides the non-pixel display portion, no afterimage phenomenon occurs.

[Example〕 Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1(a) is a plan view schematically showing a liquid crystal display device according to an embodiment of the present invention, FIG. 1(b) is a cross-sectional view taken along line A-A', and FIG. 'This is a cross-sectional view.

As shown in the figure, this liquid crystal display device consists of a ferroelectric liquid crystal 5
, pixel electrodes 1.1', which are a group of electrodes arranged so that the electrodes intersect and face each other with the ferroelectric liquid crystal 5 in between, and temperature control means for keeping the temperature of the ferroelectric liquid crystal 5 constant (see Fig. 2). A pixel is formed at the intersection of each electrode of the pixel electrode 1.1' by applying a voltage to the temperature control section 11 and heater power supply 10) and the pixel electrode 1.1' to drive the ferroelectric liquid crystal 5. It is equipped with a display driver (shown in FIG. 2) which is a driving means for forming the display, and a heating control means is equipped with a stripe heater 7 which is an electric heat generating part that hides the non-pixel display area between each pixel. It is configured to keep the temperature of the liquid crystal constant by supplying electricity to the liquid crystal.

To explain further with reference to the actual manufacturing process, first, striped heaters (also referred to as striped heater electrodes or striped heaters) 7 are formed on the upper glass substrate 3 and the lower glass substrate 4 using a normal photolithography process. to form. The material of the heater is Cr, Ta, W, Mo.
Relatively stable metals such as In this embodiment, a Mo film with a thickness of 1000 mm formed by sputtering is used.

Next, 5i02 with a thickness of 1 μm was used as the interlayer insulating layer 6, and ITO with a thickness of 1500 μm was used as the pixel electrode 1.1'.
Similarly, continuous film formation is performed using the sputtering method.

Further, a pixel electrode pattern 1.1° is formed at a position where the stripe pattern of the heater 7 covers the space portion (between pixels) between the pixel electrodes 1.1°. After polyimide is printed on the substrate 3.sub.4 which has been subjected to these treatments, an alignment treatment is performed by rubbing, and then a ferroelectric liquid crystal 5 (C3-1014 (manufactured by Chisso)) is sealed. This completes the creation of an A4 size liquid crystal display device with 1000x100 pixels.

As shown in FIG. 2, this liquid crystal display device is driven in a matrix by a display driver 9, and during this time, a temperature controller 11 supplies electricity to the heater 7 via a heater power source 10 to control the temperature.

In this configuration, the heater 7 is energized to control the temperature of the device to 45°C ± 3.5°C to perform matrix drive, and the conventional liquid crystal display device shown in Fig. 4 is placed in a constant temperature bath. When maintaining the temperature at 45°C ± 1°C and performing matrix driving with the same drive waveform as in the case of this embodiment, and comparing the display quality of these, the afterimage time was 10 to 3
While the time was 0 seconds, in the case of the liquid crystal display element of this example, the time was 1 second or less, making it very easy to see. Furthermore, the contrast ratio was 1.4 times that of the conventional example, and the display quality was significantly improved.

Furthermore, in the case of this embodiment, since the temperature control means shown in FIG. 2 is provided, there is no need to change the drive waveform in response to changes in the environmental temperature, and there is no need to provide a complicated drive waveform generation circuit. There is also an advantage.

[Other Embodiments] FIGS. 3(a) to 3(e) are plan views of liquid crystal display devices according to other embodiments of the present invention, and sectional views taken along line AA and B of the same.
-B' sectional view. This liquid crystal display device differs from the above-described embodiment in the configuration of the heater 7, which is an electric heat generating portion that hides the non-pixel display portion between each pixel. The configuration of other parts is the same as in the above embodiment.

To explain the manufacturing process in this case, first, a mesh-like heater 7 is formed on either the upper glass substrate 3 or the lower glass substrate 4 in accordance with the pitch between the pixels of the pixel electrodes 1 and 1'. The method of forming the heater 7 and the material thereof are the same as in the above embodiment. Next, as the glabellar insulating layer 6, OC
It is formed by printing D (Tokyo Ohka Rui) with a film thickness of about 1 μm. Thereafter, the pixel electrodes 1 and 1' are formed and aligned in the same manner as in the above embodiment, and ferroelectric liquid crystal C5-1014 (manufactured by Chisso) is sealed to complete the production of an A4 size liquid crystal display element with 1000x100 pixels.

Further, in this embodiment, by cutting a part of the pattern of the mesh heater 7, the temperature distribution within the display area of the liquid crystal display element is made more uniform.

When the mesh heater of this liquid crystal display device was energized and the device temperature was controlled to perform matrix driving, the temperature became 45° C.±2.0t.

When this liquid crystal display element was evaluated in comparison with the conventional example in the same way as in the above-mentioned example, the afterimage time was 10 to 3
Compared to 0 seconds, the time in this example was less than 1 second, and the contrast ratio was 1.4 times that of the conventional example.

Note that in this embodiment as well, there is no need to provide a complicated drive waveform generation circuit as in the above-described embodiment.

[Effects of the Invention] As explained above, according to the present invention, the electric heat generating portion also serves as a light-shielding layer that hides the non-image display area (between pixels), so a ferroelectric liquid crystal display device with no afterimage and high contrast can be achieved. can be realized without a complicated drive circuit.

[Brief explanation of drawings]

FIGS. 1(a) to 1(c) are a plan view of a liquid crystal display device according to an embodiment of the present invention, a sectional view taken along line AA', and FIG.
-B' cross-sectional view; FIG. 2 is a block diagram showing the temperature control mechanism of the device in FIG. 1; FIGS. Plan view and its AA sectional view and B
-B' sectional view and FIGS. 4(a) to 4(c) are a plan view, an AA' sectional view, and a BB' sectional view of a liquid crystal display element according to a conventional example. 1.1°; pixel electrode, 2: non-image display area, 3: clay glass substrate, 4: lower glass substrate, 5: strong telephone liquid crystal, 6. interlayer insulating layer, 7: heater electrode, 8: mesh heater electrode,
9: Display driver, 10: Heater power supply, 11;
Temperature control section. Patent applicant Canon Co., Ltd. Agent

Claims (4)

[Claims] (1) A liquid crystal, a group of electrodes arranged so that the electrodes intersect and face each other with the liquid crystal in between, a temperature control means for keeping the temperature of the liquid crystal constant, and a voltage applied to the electrode group to drive the liquid crystal. In the liquid crystal display device, the temperature control means includes an electric heat generating portion that hides a non-pixel display portion between each pixel;
A liquid crystal display device characterized in that the temperature of the liquid crystal is kept constant by supplying electricity to the liquid crystal display device. (2) The liquid crystal display device according to claim 1, wherein the electric heat generating portion is formed in a stripe shape on at least one substrate on which a group of electrodes facing each other with the liquid crystal interposed therebetween are formed. (3) The liquid crystal display device according to claim 1, wherein the electric heat generating portion is formed in a mesh shape on either one of the substrates on which the electrode groups facing each other with the liquid crystal interposed therebetween are formed. (4) The liquid crystal display device according to claim 1, wherein the liquid crystal is a ferroelectric liquid crystal.