JPS61215523A - Production of liquid crystal apparatus - Google Patents

Abstract

PURPOSE:To improve an uniformity and an accuracy of a dimension in a thickness of the liquid crystal layer by forming spacers composed of a photosensitive polyimide so as to correspond each other on each surfaces of a pair of electrodes which are face to face each other. CONSTITUTION:The linear upperward spacer 8a and the linear downward spacer 8b having an uniform thickness of 1-2mum are arranged over a whole surface of the electrode substrates 3, 4 so as to intersect at right angles. By the sum (d1+d2) of the thickness (d1) and (d2) of each upperward spacer 8a and the downward spacer 8b is limitted the thickness (d) of the liquid crystal layer. The upper ward spacer 8a and the downward spacer 8b compose of the high molecule film of the photosensitive polyimide. The high molecule films are formed on the whole surfaces of the electrode substrates 2, 3 respectively. The photosensitive polyimide films are optically cured by irradiating a light so as to dispose patterns of each photosensitive polyimide films in order in a right slantwise direction, and in a left slantwise direction respectively. Both substrates 2, 3 are piled up so as to contact the upperward spacer 8a and the downward spacer 8b each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a light modulation type liquid crystal device in which a liquid crystal having ferroelectricity is sealed, for example.

BACKGROUND TECHNOLOGY As a conventional display device using liquid crystal, twist
The winter magnetic field effect type is common, and is widely used in electronic desktop calculators, digital watches, etc. However, despite improvements in liquid crystal materials, cells, driving methods, etc., they lack high-speed response, and cannot be used as television image displays, portable computer display devices, or shutter devices, which have recently been attracting attention. There was a problem with its responsiveness.

In order to solve this response problem, liquid crystal modulation display devices using ferroelectric chiral smectic liquid crystals have been used, but generally it is difficult to obtain the memory properties that are characteristic of such ferroelectric liquid crystal materials. In order to achieve this, it is necessary to ensure a thickness of the liquid crystal layer of 1 to 3 μm. However, glass fiber, alumina oxide powder, glass-topped plastic beads, etc. have traditionally been used as spacers to define the thickness of the liquid crystal layer, and such spacers usually have a thickness of 5μ or more, making it difficult to achieve the desired thickness. 1-3
It is not possible to obtain the μ- dimension. Furthermore, due to variations in spacer dimensions, it has not been easy to maintain a uniform thickness of the liquid crystal layer.

Problems to be Solved by the Invention In summary, especially in light modulation type display devices using ferroelectric liquid crystal materials, conventional spacers cannot ensure the thickness of the liquid crystal layer to be less than 3 μm; Unable to maintain uniform thickness.

Therefore, it was not possible to ensure high-speed response and bistability.

The purpose of the present invention is to solve the above-mentioned technical problems, reduce the thickness of the liquid crystal layer to 3 μm or less, and make the thickness uniform to ensure high-speed response and bistability, thereby improving display quality. An object of the present invention is to provide a G1 manufacturing method for a liquid crystal device that can achieve the following objectives.

SUMMARY OF THE INVENTION The present invention provides a method of applying photosensitive polyimide to each mutually opposing surface of a pair of mutually opposing electrode substrates.

The spacers of the electrode substrates are formed so as to correspond to each other, and the space of the electrode substrate portion is defined by the corresponding spacers of each electrode substrate being in contact with each other.
This method of manufacturing a liquid crystal device is characterized in that liquid crystal is sealed in this space.

Effect According to the present invention, by using photosensitive polyimide as the material of the spacer, the thickness of the liquid crystal layer can be reduced to 3.
It is possible to ensure that the thickness is less than a μ ring, and furthermore, it is possible to improve the thickness accuracy.

Embodiment FIG. 1 is a sectional view of a liquid crystal device 1 according to the present invention. A light modulation type liquid crystal device 1 includes transparent electrodes 4.5 and alignment films 6, 7 that have been subjected to an alignment process, arranged on mutually opposing surfaces of two electrode substrates 2.3, and arranged with a sealing material 9 in between. ferroelectric chiral smectic liquid crystal 10 is sealed in the cell space defined by the sealing material 9.

Spacers 8.8 & are patterned on these electrode substrates 2.3, and by overlapping these spacers 8.8a, the thickness d of the dark liquid crystal layer of the electrode substrate 2.3 is defined. . A pair of polarizers 11 and 12 are arranged on both external sides of the transparent substrates 2 and 3, and by applying and releasing a predetermined voltage between the upper and lower transparent electrodes 4 and 5, they can function as, for example, a light shutter device. can be accomplished.

Referring to FIG. 2, the molecules 10m of the ferroelectric Kaiflusmectic liquid crystal 10 have a helical structure arranged at a tilt angle θ with respect to the helical axis direction indicated by the arrow a. The liquid crystal molecules 10a have spontaneous polarization in a direction perpendicular to each molecule. Now, when an electric field E higher than a certain critical electric field is applied to the upper and lower electrode substrates 2 and 3, the helical structure of the liquid crystal molecules 10m is dissolved, and the liquid crystal molecules 10a all face in the same direction. Since the alignment is due to spontaneous polarization, the liquid crystal molecules 10m have two alignment directions depending on the direction of the electric field, E and -E.The 10m liquid crystal molecules have a long striped shape, and have birefringence with different refractive indexes in the long axis direction and the short axis direction. To show this, polarizers 11. are placed above and below the electrode substrate 2°3.
By arranging 12 orthogonally, it is possible to obtain an optical modulation device that performs switching based on electric field polarity. This change in the arrangement of 10 m of liquid crystal molecules only changes the orientation of the molecules within the layer, so it does not involve a change in the layer structure as in the twisted nematic field effect type (therefore, it has high-speed response). It is something.

Furthermore, even in a steady state where no electric field is applied, it is possible to eliminate the helix by making the thickness d of the liquid crystal layer thinner than the helical pitch of the liquid crystal molecules 10-. Even in this case, the alignment directions of the liquid crystal molecules 10m show two directions and have bistability.Therefore, if the electric field E is applied, all the liquid crystal molecules 10m will have a tilt angle θ with respect to the helical axis direction a.
This results in a bistable orientation as shown in FIG. 2 (2), which continues to maintain this state even when the electric field is turned off. On the other hand, the electric field −
When E is applied, all the liquid crystal molecules 10a have a molecular alignment that is tilted by a tilt angle of -θ with respect to the helical axis direction a, and it is possible to obtain a stable orientation as shown in Figure #2 (2). , continues to maintain this state even if the electric field is turned off. In this way, by reducing the thickness d of the liquid crystal layer, high-speed response and bistability can be obtained at the same time.

The optical modulation method using the above birefringence phenomenon is shown in Figure 2 (
The relationship between the incident light intensity Io and the transmitted light intensity I in 2) is
The relationship in Figure 2 (3) is expressed by the second equation.
It is shown by the formula.

I=O...(1) I-(I o/2)・(S in"4θ)・(S
in”f − (Δn・d/λ))
(2) Here, Δn represents the refractive index anisotropy of the ferroelectric chiral smectic liquid crystal 10, d represents the thickness of the ferroelectric chiral smectic liquid crystal layer, and θ
represents the helical tilt angle of the ferroelectric smectic liquid crystal 10.

The state shown in Fig. 2 (2) is
Plotting the case of m, 550 points and 6501 theory is shown in Figure 3, and θ=π/8
It is clear that the transmitted light intensity I when .DELTA.n-d and wavelength input strongly depend on .DELTA.n-d. Therefore, in the visible light wavelength region, Δn-d needs to be set in the range of 0°2 to 0.3, thereby making it possible to obtain a good display element with no color distortion. Furthermore, the refractive index anisotropy Δn of the ferroelectric chiral smectifuku liquid crystal 10 is generally 0.
．． Since it is about 1 to O02, the value of the thickness d of the liquid crystal layer is 1
~3μ- is optimal. In addition, in order to obtain a bistable state, the value of the thickness d of the liquid crystal layer must be smaller than the helical pitch of the ferroelectric smectic liquid crystal 10, and from this point of view, the thickness d of the liquid crystal layer must be set to 1. It is understood that it is appropriate to choose ~3μ-.

An example of the ferroelectric chiral smectic liquid crystal 10 is as follows:
As shown in Table 1.

(The following is a margin.) FIG. 4 is a sectional view taken along the section line ff-IV in FIG. 1. 1 on the entire surface of the electrode substrates 3 and 4.
Line-shaped upper spacers 8a and lower spacers 8b having a uniform thickness of ~2 μm, preferably 1.5 μm, are formed extending in directions perpendicular to each other. Each thickness d of this upper spacer 8a and lower spacer 8b,
, d2, d, + d, defines the thickness d of the liquid crystal layer.

The upper spacer 8a and the lower spacer 8b are made of a photosensitive polyimide polymer film. A suitable material for this photosensitive polyimide is, for example, a photosensitive polymer obtained by reacting a diamine compound having a photosensitive group in its molecule with a tetracarboxylic anhydride.

For patterning the upper spacer 8a and lower spacer 8b, for example,
First, polymer films made of photosensitive polyimide are formed over the entire surface of the electrode substrates 2 and 3 by a spinner coating method, a roll coater method, or the like. The thickness of this photosensitive polyimide film is 1.5 .mu.I in this example. Next, by light irradiation, one of the photosensitive polyimide films is formed into a longitudinal shape as shown in FIG. 4, and photocured so as to be arranged in an orderly pattern diagonally to the left in FIG. Further, the other photosensitive polyimide film is also formed into a longitudinal shape as shown in FIG. 5, and is photocured so as to be patterned in an orderly manner diagonally to the right in FIG. Thereafter, the remaining portions of the polyimide film other than the photocured portions are removed, and the upper spacer 8a and the lower portion made of the elongated photosensitive polyimide film having a uniform thickness of 1.5μ are placed on the electrode substrates 2 and 3. Spacers 8b are respectively formed.

After patterning the upper spacer 8a and lower spacer 8b made of photosensitive polyimide film on the electrode substrates 2 and 3 in this way, the alignment films 6 and 8 of the electrode substrates 2 and 3 are formed.
Both substrates 2 and 3 are aligned so that the upper spacer 8a and the lower spacer 8b are in contact with each other.
Overlap.

At this time, the upper spacer 8a and the lower spacer 8b are arranged in a crossed shape as shown in FIG. 6, and the thickness of the space between the electrode substrates 2 and 3 is
, 9, each thickness d, (=1.5μ-L
The sum d of d2 (=1゜5μ-), 10d, (= 3μ-)
becomes.

The electrode substrates 2.3 stacked one on top of the other in this manner are adhered to each other by a sealing material 9, and a ferroelectric liquid crystal is sealed in the cell space thereof. Since the thickness d of this liquid crystal layer is uniformly 3μ, this ensures high-speed response and bistability of the liquid crystal layer ra1 of the optical modulation method using the ferroelectric irradial smectic liquid crystal 10, and therefore It becomes possible to improve display quality.

Furthermore, by overlapping the upper spacer 8B and the lower spacer 8b in a crossed state, it is possible to reliably prevent the thickness d of the liquid crystal layer from varying due to misalignment, etc. This will facilitate the process and improve the yield of liquid crystal cells.

Since the quantity, shape, and arrangement pattern of each spacer 8, 9 can be arbitrarily selected depending on the mode of light irradiation of the photosensitive polyimide film, it is possible to design and change the design according to the type of liquid crystal cell extremely smoothly. It is.

In the above embodiment, the photosensitive polyimide films each have a longitudinal shape (\, /) extending in an oblique direction, but the invention is not limited to this. For example, the photosensitive polyimide film may have a longitudinal shape (-1) extending vertically and horizontally. Good too.

In the first embodiment, the spacer 8 made of photosensitive polyimide
, 8a on both surfaces of electrode substrates 2 and 3! Although this pattern was formed, as another embodiment of the present invention, a spacer 8 made of photosensitive polyimide was formed on one electrode substrate 2, and a material other than polyimide was formed on the other electrode substrate 3.
For example, the spacer 8a may be formed of an electrically insulating, light-transmitting material such as silicon oxide, and the spacers 8a may be overlapped with each other to define the thickness d of the liquid crystal layer.

The method for manufacturing a liquid crystal device according to the present invention is not limited to a light modulation type display device using a ferroelectric chiral smectic liquid crystal, but can also be used in connection with a display device using a nematic liquid crystal or the like.

Effects As described above, according to the present invention, spacers made of photosensitive polyimide are formed on each of the mutually opposing surfaces of a pair of mutually opposing electrode substrates, and the spacers are formed on the corresponding surfaces of each electrode substrate. By abutting the spacers to define the space between the W pole substrates, the thickness of the liquid crystal layer can be made uniform and highly accurate. Therefore, the quick response and bistability of the liquid crystal device according to the present invention are ensured,
Be able to improve display quality.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the liquid crystal layer R1 according to the present invention, FIG. 2 is a diagram schematically showing 10 m of liquid crystal molecules, and FIG. Figure 4 is a sectional view taken from section line fV-IV in Figure 1, Figure 5 is a sectional view taken from section line ■-■ in Figure 1, and Figure 6 is a cross-sectional view taken from section line fV-IV in Figure 1. Spacer 8a and lower spacer 8
FIG.

Claims (1)

[Claims] Spacers made of photosensitive polyimide are formed on each of the mutually opposing surfaces of a pair of mutually opposing electrode substrates, and the corresponding spacers of each electrode substrate abut to define the space between the electrode substrates. A method for manufacturing a liquid crystal device, characterized in that the liquid crystal is sealed in this space.