JPH04287020A - Active substrate - Google Patents

Abstract

PURPOSE:To obviate the generation of the electrostatic destruction of active devices successively provided with 1st electrodes, ferroelectric substance layers and 2nd electrodes on an insulating substrate at the time of a rubbing treatment by connecting the 2nd electrodes on the outside of the element regions where the active devices are integrated. CONSTITUTION:The island-shaped 1st electrodes 2 are provided on the insulating substrate 1 consisting of a glass substrate and the ferroelectric substance layers 3 consisting of a vinylidene fluoride/trifluoroethylene copolymer are so provided as to cover the 1st electrodes 2. The 2nd electrodes 4 consisting of Al are so provided as to cover a part of the 1st electrodes 2 via the ferroelectric substance layer 3. The 2nd electrodes 4 are used as the common electrodes to connect the active devices in a horizontal direction in the element region where the active devices are disposed in a matrix form. Plural pieces of the common electrodes exist and the common electrodes are used as bus lines. The 2nd electrodes 4 are respectively connected in the regions exclusive of the element region and a part thereof are so provided as to enclose the element region.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device.

0002

[Prior Art] Conventionally, a first electrode 2 made of ITO was provided on an insulating substrate 1 made of a glass substrate, and a VDF/TrFE (vinylidene fluoride/trifluoroethylene) copolymer was provided on the first electrode 2. An element that integrates an active device consisting of a ferroelectric layer 3 which is provided to cover a first electrode 2, and a second electrode 4 which covers a part of the first electrode 2 through the ferroelectric layer 3. Active substrates have been known in which a second electrode is not connected to an active substrate having a region.

0003

[0006] The conventional technique has had the problem that static electricity is generated when rubbing an active substrate, and the active device is electrically destroyed.

0004

[Means for Solving the Problems] The active substrate of the present invention includes an island-shaped first electrode provided on an insulating substrate, and a ferroelectric layer provided to cover at least a portion of the first electrode. , in an active substrate having an element region integrating an active device having a second electrode provided so as to cover a part of the first electrode through the ferroelectric layer; The feature is that the connection is made in an area other than the element area.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an example of the structure of an active device used in an active substrate of the present invention. Figure 1
(a) is a top view, and (b) is a sectional view taken along the line A-A in the figure. Insulating substrate 1 made of glass substrate
An island-shaped first electrode 2 made of ITO is provided on top. A ferroelectric layer 3 made of a VDF/TrFE (vinylidene fluoride/trifluoroethylene) copolymer is provided so as to cover the first electrode 2 . A second electrode 4 made of Al is provided so as to partially cover the first electrode 2 with the ferroelectric layer 3 interposed therebetween. The active layer of the active device is a ferroelectric layer 3 sandwiched between first and second electrodes 2, 4. This active device is formed by forming a first electrode 2 on an insulating substrate 1, then forming a ferroelectric layer 3, and finally forming a second electrode 4 on the ferroelectric layer 3. Ru.

FIG. 2 shows a first active substrate according to the present invention. FIG. 2(a) is a top view, and FIG. 2(b) is a top view (
a) It is a sectional view taken along the middle A-A line. In the element region shown in FIG. 1 where the active devices are arranged in a matrix, the second electrode 4 is used as a common electrode that horizontally connects the active devices, and there are a plurality of common electrodes. The common electrode is then used as a bus line. The second electrodes 4 are connected to each other in a region other than the device region, and a portion thereof is provided so as to surround the device region. Since the connection of the second electrode 4 is formed in the same process as forming the second electrode 4, there is no need to newly use a special process.

When the active substrate shown in FIG. 2 is used as a liquid crystal element, an alignment film made of polyimide is formed at least on the element region, and then rubbed on the alignment film. The rubbing process is a process in which the alignment film is physically rubbed with absorbent cotton or the like. At this time, static electricity is generated on the alignment film. This static electricity causes electrostatic damage to the active layer of the active device.
The active device will be destroyed. This is particularly noticeable when the respective second electrodes 4 are not connected. Although the frequency of electrostatic damage varied depending on humidity and other factors, an average of about 5% of active devices were destroyed when the second electrode 4 was not connected. On the other hand, when the respective second electrodes 4 were connected, the amount of electrostatic damage caused was reduced to 0.0001% or less. This is considered to be because the voltage induced by static electricity in each active device is averaged and reduced by connecting each second electrode 4. When the respective second electrodes 4 were not connected, the voltages induced in each active device were different, and those in which a high voltage was induced were damaged by electrostatic discharge.

In FIG. 2, a terminal region is present on the active substrate. The second electrode 4 is connected in a terminal region as far away from the element region as possible. This is because it is necessary to separate the second electrode 4 when finally forming a liquid crystal element using an active substrate. The area to be separated is shown in FIG. 2 as a separation area. By providing the separation region apart from the element region (preferably at the end of the terminal region) in this manner, the limited area of the active substrate can be effectively utilized.

In FIG. 2, the insulating substrate 1 used is not limited to a glass substrate, and an organic insulating material may also be used. ITO is used for the first electrode 2 and second electrode 4.
It is not necessary to limit the electrode to Al or Al, and other transparent electrodes, metals, or superconducting materials may be used. It is not necessary to limit the copolymer of VDF and TrFE to be used for the ferroelectric layer 3;
An inorganic ferroelectric material such as iO3 or an organic ferroelectric material such as a copolymer of vinylidene fluoride and tetrafluoroethylene may be used. Materials other than polyimide, such as polyamide, PVA, PDiPF, etc., may be used as the alignment film. Alternatively, the ferroelectric layer 3 may be directly rubbed without using an alignment film.

FIG. 3 shows a second active substrate according to the present invention. Figure 3 (a) is a top view, and Figure 3 (b) is a top view (
a) It is a sectional view taken along the middle A-A line. In the element region shown in FIG. 1 where the active devices are arranged in a matrix, the second electrode 4 is used as a common electrode that horizontally connects the active devices, and there are a plurality of common electrodes. The common electrode is then used as a bus line. The second electrodes 4 are connected to each other in a region other than the device region, but a portion thereof is not provided so as to surround the device region. Similar to FIG. 2, the connection of the second electrode 4 is formed in the same process as forming the second electrode 4, so there is no need to use any special process. Similarly to FIG. 2, in FIG. 3, electrostatic damage during the rubbing process is less likely to occur, and the separation region is provided at a position away from the element region.

In FIG. 3, the same first and second electrodes 2, 4, insulating substrate 1, ferroelectric material, alignment film, and rubbing treatment as in FIG. 2 may be used.

Although FIGS. 2 and 3 show an example of a configuration for connecting the second electrode 4, the connection configuration is not limited to these, and other configurations may also be used to connect the second electrode 4. All you have to do is

FIGS. 2 and 3 are examples using the active device shown in FIG. 1, but when using an active device with another configuration, the electrodes used as bus lines may be connected to each other. An example of an active device having another configuration is one in which the positions of the first and second electrodes 2 and 4 shown in FIG. 1 are reversed.

[0014]

As explained above, the present invention makes it possible to obtain an active substrate that is less susceptible to electrostatic damage during rubbing treatment.

[Brief explanation of the drawing]

FIG. 1 shows an active device.

FIG. 2 is a diagram showing the first active substrate of the present invention.

FIG. 3 is a diagram showing a second active substrate of the present invention.

[Explanation of symbols]

1 Insulating substrate 2 First electrode 3 Ferroelectric layer 4 Second electrode 21 Separation area 22 Terminal area 23 Element area

Claims (1)

[Claims] 1. An island-shaped first electrode provided on an insulating substrate; a ferroelectric layer provided to cover at least a portion of the first electrode; In an active substrate having an element region in which active devices are integrated, the second electrode is provided with a second electrode provided so as to cover a part of the first electrode, and the second electrode is connected in a region other than the element region. Features an active board.