JPH0331822A - Liquid crystal electrooptical device - Google Patents

Abstract

PURPOSE:To eliminate the possibility that an operator mistakes the spraying conditions of spacers together with the kinds thereof by constituting the device in such a manner that the device has plural spacers between a pair of substrates and the plural spacers are varied in colors with each of the kinds thereof. CONSTITUTION:The film of ITO is formed on soda glass and is patterned to form electrodes. A polyimide thin film is obtd. by applying polyamic acid on the electrode forming surface and heating the same. The surface of the polyimide thin film is subjected to a rubbing treatment and this substrate is stuck onto one substrate; thereafter, the spacing between the substrates is controlled by spraying the spacer materials 1 having a desired diameter, i.e. 6.2mum and the black spacer materials 2 of 5.2mum desired to deal with low-temp. bubbles. A sealing material consisting of an epoxy system is printed on the other substrate and the two substrates are stuck to each other to complete the cell. The liquid crystal 3 is injected into the formed cell and the cell is pressed by an air press machine; thereafter, the liquid crystal injection port is sealed by a UV resin. The operator is thus prevented from mistaking the spraying conditions of the white spacers and the black spacers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a spacer in a liquid crystal electro-optical device.

[Conventional technology]

Conventionally, TN type liquid crystal electro-optical devices have been applied as display devices for calculators, clocks, and the like.

This TN-type liquid crystal electro-optical device has a structure in which a 90° twisted nematic liquid crystal containing a chiral component is placed between a pair of substrates having transparent electrodes. In order to maintain a constant and uniform density, white fine particles such as Sin or borisdyrene are generally placed between the substrates as spacers.

However, the TN type liquid crystal electro-optical device cannot meet the demand for larger screens in recent years. This is because in a TN type liquid crystal electro-optical device, the contrast becomes smaller as the number of scanning lines increases.

As a countermeasure against this problem, an STNTN type liquid crystal electro-optical device in which the liquid crystal is twisted at an angle of 90' to 270° is used in display devices such as word processors.

Since the STNTN type liquid crystal electro-optical device performs display by utilizing the refractive index anisotropy of the crystal, a more uniform substrate spacing is required compared to the TN type liquid crystal electro-optical device.

It is known that in order to achieve more uniform substrate spacing, the number of spacers between the substrates can be increased. However, if the number of one type of spacer is increased, although the spacing between the substrates becomes uniform, there is no degree of freedom in the thickness direction of the substrates, so when the ambient temperature decreases and the volume of the liquid crystal decreases. , a space is created within the liquid crystal cell. (
(referred to as low-temperature bubbles) For this reason, a method of using two types of spacers with slightly different sizes has been found to be effective and has already been carried out.

[Problems with conventional technology]

As mentioned above, conventionally used spacers do not have any distinguishing marks other than size, so
If you try to spray two types of spacers, you won't be able to tell them apart, and as a result, for example, a 6.2μm spacer and a 5.8μm spacer.
When spraying spacers of 6.2 m, the worker accidentally
5.8 μm spacer is used for dispersing μm spacer, and 6.2 μm spacer is used for 5.8 μm spacer.
There is a high possibility that the spraying will be carried out under the conditions of the spacer.

Furthermore, when creating a cell using two types of spacers, when setting the spraying conditions for each spacer, we actually sprayed the spacers on the experimental substrate and used a microscope to compare the spacers that were actually sprayed. For example, as mentioned above, 6.2 μm and 5.8 μm are counted.
m spacers are difficult to distinguish even with a microscope;
Therefore, it becomes difficult to determine the spraying conditions.

[Structure of the invention]

In order to solve the above problems, the present invention provides a liquid crystal electro-optical device in which a liquid crystal is interposed between a pair of substrates having electrodes, and a plurality of spacers are provided between the pair of substrates,
The plurality of types of spacers are characterized in that each type has a different color.

To specifically explain the configuration of the present invention using the previous example, it means that, for example, a red spacer is used as a 6.2 μm spacer, and a yellow spacer is used as a 5.8 μm spacer.

[Effect]

When manufacturing the liquid crystal electro-optical device of the present invention, since the colors of the plurality of spacers are changed for each type, there is no need for an operator to mix up the dispersion conditions for each type of spacer.

Furthermore, by actually scattering multiple types of spacers on an experimental substrate and observing them using a microscope, it is possible to easily count the number of spacers with different colors.

Furthermore, in the case of liquid crystal display devices, in order to prevent contamination of the liquid crystal and substrate, it is most preferable to count the spacers after the liquid crystal injection process and injection port sealing process. Sometimes it is not possible to distinguish between white spacers and liquid crystals using a normal microscope, so counting can be done by using a polarizing microscope and making the polarizing plates parallel or nearly parallel. This is because there is no liquid crystal in the area where the spacer exists, so it is not affected by the optical anisotropy of the liquid crystal, making counting possible.

Especially when white and black spacers are sprinkled on the board,
When measuring the number of spacers after injecting the liquid crystal, by making the polarizing axes of the polarizing plate of the polarizing microscope parallel, white spacers appear white, and black spacers absorb light and appear black.

However, if the polarization axis of the polarizing plate is set at right angles, both spacers will appear black, making it difficult to count each type. Also, care must be taken as it is not possible to distinguish between liquid crystal and white spacers using a normal microscope without a polarizing function.

The present invention will be explained below with reference to Examples.

r Example 11 This example shows an example of manufacturing an STN type liquid crystal electro-optical device.

ITO is formed into a film by DC magnetron sputtering on cleaned soda glass, and patterned to form electrodes. Then, polyamic acid is applied to the electrode-forming surface using an offset printing machine and heated at 250° C. for 3 hours to obtain a polyimide thin film. Then, the surface of the polyimide thin film is rubbed with a cotton cloth.

Of the two substrates that underwent the process up to the rubbing process, a white spacer material with a diameter of 6.2 μm was placed on one of the substrates for the purpose of controlling the distance between the substrates after bonding, and a white spacer material for the purpose of preventing low-temperature bubbles. A black 5.2 μm η spacer material is spread, and an epoxy sealant is printed on the other substrate using a screen printer, and both substrates are pasted together to complete the cell. Liquid crystal is injected into the cell fabricated through the above steps using a vacuum injection method. After the liquid crystal has been injected, the liquid crystal cell is pressed using an air press machine to eliminate color unevenness caused by the gap difference between the substrates and enlargement of the liquid crystal cell due to large amounts of liquid crystal injected, and then the liquid crystal is injected with UV resin and sealed. (stop).

]-11 of the spacer material of the liquid crystal cell produced in the above process
1 The fabric density was measured using a polarizing microscope and a CCD camera connected to VF.

In this measurement, the angle of the polarization axis of the polarizing plate of the polarizing microscope was set to 0°, that is, in a parallel state. The image obtained through the CCD camera at this time was as shown in Figure 1. The white spacer (1) could be clearly observed as white and the black spacer as black, and the surrounding liquid crystal part (3) appeared yellow. Therefore, it was very easy to measure the number of each spacer.

By using this example, the operator no longer mixes up the spraying conditions for white spacers and black spacers.

r Example 2J A red spacer material with a diameter of 6.2 μm for the purpose of controlling the substrate spacing and a measure against low-temperature bubbles were placed on one of the pair of substrates that had been subjected to the rubbing process in exactly the same manner as in Example 1. Spread blue spacer material with a desired diameter of 5.2 μm, print an epoxy sealant on the other substrate using a screen printer, and bond both substrates together to complete the cell. Liquid crystal is injected into the cell manufactured by the above steps using a vacuum injection method. The liquid crystal cell that has been injected with liquid crystal eliminates color unevenness caused by the gap difference between the substrates and enlargement of the liquid crystal cell due to large amounts of liquid crystal injection. Perform sealing.

The dispersion density of the spacer material in the liquid crystal cell produced in the above process was measured using a camera connected to an ordinary microscope without a polarizing function. However, in this example, the measurement was performed through a color temperature correction filter.

In this example, since two types of spacers, red and ft color, were used, a microscope without a polarizing function can be used for counting. On the other hand, a polarized light microscope? ij,t
If f't is used, the liquid crystal part will appear colored, making it rather difficult to see.

When red and blue spacers are used as in this example, the diameter of the spacers is much smaller than when white and black are used as in Example 1, so the ease of identification is slightly inferior. It is something.

r Example 3J An epoxy sealing material is printed on one of the two substrates, which are manufactured in exactly the same manner as in Example 1 up to the ITO electrode manufacturing process, using a screen printer.

Then, polyamic acid is coated on the other substrate in the same manner as in Example 1, and then heated to obtain a polyimide film. Thereafter, the polyimide thin layer is rubbed with a cotton cloth.

Then, on the rubbed substrate, a red 2.5 μm spacer material was placed for the purpose of gear control between the substrates.
Low) A 2.071 m blue spacer material and a 5.5 μm yellow epoxy spacer material were sprayed to prevent bubbles. This epoxy spacer serves to bond the substrate together by heating, and is protected against external impact. This is indispensable for ferroelectric liquid crystal cells, which are susceptible to

After passing through the above steps, the two substrates are bonded together, ferroelectric liquid crystal is injected, and then the liquid crystal injection port is sealed to complete the cell.

Then, as in Example 2, using a normal microscope without polarization function and a color temperature correction filter, 3M! The number of each of the 11 spacers could be measured.

In this example, by using spacers of three colors, red, yellow, and blue, the respective dispersion densities could be easily measured.

〔effect〕

As described above, by changing the colors of the plurality of types of spacers that constitute the present invention, it is possible to easily measure the dispersion density of each spacer. Therefore, it is easy to determine a dispersion density that provides uniform substrate spacing and does not generate low-temperature bubbles. Then, by simply measuring the dispersion density, we will be able to obtain a liquid crystal cell with uniform substrate spacing and no low-temperature bubbles, by conducting experiments such as actually measuring the substrate spacing and leaving it in a low-temperature state. It is now possible to predict with certainty. Therefore, cells with poor distribution density can be discarded without performing any actual process such as connection with a later drive circuit, thereby reducing manufacturing costs.

Furthermore, by using the present invention, when spraying multiple types of spacers, it was possible to significantly reduce the possibility that an operator would mix up the spraying conditions and perform the spraying.

[Brief explanation of drawings]

FIG. 1 shows the state of dispersion of spacers. ■・・・White spacer 2...Black spacer 3...LCD part

Claims (1)

[Claims] 1. A liquid crystal electro-optical device in which a liquid crystal is interposed between a pair of substrates having electrodes, wherein a plurality of types of spacers are provided between the pair of substrates, and the plurality of spacers are A liquid crystal electro-optical device characterized by different colors depending on its type. 2. A liquid crystal electro-optical device according to claim 1, characterized in that there are two types of spacers between the pair of substrates, one of which is white and the other of which is black.