JPH05289065A - Liquid crystal panel - Google Patents

Abstract

PURPOSE:To make color display without color filters by changing the film thickness of at last one electrode of the liquid crystal panel holding a chiral nematic liquid crystal, thereby forming plural pieces of level differences. CONSTITUTION:Plural pieces of the level differences are formed by changing the film thickness of at least one electrode 8 of the liquid crystal panel constituted by holding the chiral nematic liquid crystal 6 subjected to twist orientation between two sheets of the substrates with the electrodes. The transparent conductive films varying in the film thickness can be formed by repeating, many times, the formation of the transparent conductive films by a DC sputtering method and the processing of the transparent conductive films by photolithography. The distance between the upper and lower panels is changed by changing the film thickness of at least one electrode 8 of the liquid crystal panel and forming plural pieces of the level differences and, therefore, the straight use of the effect of the double refractions of the supertwisted nematic type liquid crystal panel is possible and the execution of the color display without the color filters is possible. The color liquid crystal panel is thus inexpensively produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel used for a liquid crystal display device, an optical shutter or the like.

[0002]

2. Description of the Related Art Super twisted nematic liquid crystal panels (STN panels) conventionally used in word processors and the like are colored by the effect of birefringence. And white (blue
Mode) or yellow when no voltage is applied, and black (yellow mode) when voltage is applied.

In order to colorize these panels,
As shown in FIG. 6, it was necessary to superimpose the retardation film 13 or the phase film on the STN panel for black and white display, and to form the color filter 14 inside or outside the panel.

Color without using a color filter
A display method (Japanese Patent Laid-Open No. 63-231314) has also been devised, but this method is limited to the ferroelectric liquid crystal. Further, a method of changing the thickness of the liquid crystal layer according to the spectral transmission characteristics of the color filter (Japanese Patent Laid-Open No. 60-159823).
(Japanese Patent Application Laid-Open No. 60-159824) (Japanese Patent Application Laid-Open No. 60-159830), which is essentially different from the present patent in that a color filter is used. Is.

[0005]

In order to perform STN liquid crystal color display on the conventional liquid crystal panel as described above, it is necessary to install a retardation plate and a color filter on the liquid crystal panel. However, since the color filter is expensive and has a problem in heat resistance, it has been a factor that hinders cost reduction and reliability of the liquid crystal panel.

An object of the present invention is to solve the above problems and to produce a color liquid crystal panel at low cost by performing color display without using a color filter.

[0007]

In order to solve the above problems, the liquid crystal panel of the present invention has at least one electrode of a liquid crystal panel in which a chiral nematic liquid crystal having a twist orientation is sandwiched between two substrates with electrodes. A plurality of steps are formed by changing the film thickness.

[0008]

According to the present invention, since the distance between the upper and lower panels is changed by changing the film thickness of at least one electrode of the liquid crystal panel and forming a plurality of steps, the effect of the birefringence of the STN panel is maintained. The color liquid crystal panel can be used, color display can be performed without a color filter, and a color liquid crystal panel can be manufactured at low cost.

[0009]

【Example】

(Example 1) Twist angle of liquid crystal molecules (twist angle) 23
5 °, tilt angle (pretilt angle) of liquid crystal molecule with respect to substrate surface 5 °, refractive index of extraordinary ray 1.63, refractive index of ordinary ray 1.5, made by liquid crystal molecule of incident light plane and polarization axis of polarizer The transmittance with respect to the panel gap of the STN panel when the angle is 45 ° and the angle formed by the polarization axes of the liquid crystal molecules on the incident light surface and the analyzer is 100 ° (FIG. 5) is shown in FIG.

In FIG. 4, 1 is blue (wavelength 0.45).
μm), 2 represents the transmittance for green (wavelength 0.55 μm), and 3 represents the transmittance for red (wavelength 0.65 μm). That is, when no voltage is applied, a panel gap of 5.3 μm results in blue color, a panel gap of 6.5 μm results in green color, and a panel gap of 7.6 μm results in red color.

FIG. 1 shows a first embodiment of the present invention.
A transparent conductive film (IT
An O film 8 is formed, and a transparent conductive film (ITO film) 3 having the same thickness is formed on the other glass substrate 2. The method of forming the transparent conductive film having different film thickness can be performed by repeating the formation of the transparent conductive film by the DC sputtering method and the processing of the transparent conductive film by the photolithography many times. Moreover, the film thickness distribution of the transparent conductive film can be controlled within ± 5% in the present forming technology, for example, in a display substrate having a diagonal size of about 20 inches.

After cleaning the glass substrates 2 and 9, a photosensitive polyimide is formed as a spacer 11 on one substrate 9 by photolithography. On top of that, SiO films are formed as the alignment films 4 and 7 by oblique vapor deposition. The seal resin 5 is printed on the edge of the surface of the glass substrate 2 on which the alignment film 4 is provided, and the two substrates 2 and 9 are laminated and heated so that the alignment film surfaces face each other and heated. The resin 5 is cured. After that, vacuum deaeration is performed, and the liquid crystal 6 is injected between the two glass substrates 2 and 9. Panel gap is 5.3μm, 6.5μm, 7.6μm at each electrode
So that When a polarizer and an analyzer are attached to this panel as shown in (Fig. 5), the transmittance in each panel gap is as shown in (Fig. 4), so when voltage is applied to all pixels, all pixels are black, When no voltage is applied, white is produced when only pixels with a gap of 5.3 μm are not applied, and when the pixels with a gap of 6.5 μm are not applied, it is green. When only pixels with a gap of 7.6 μm are not applied, red is produced. Thus, color display can be performed without using a color filter.

Although the film thickness of the electrodes on one of the substrates is changed in this embodiment, electrodes having different film thickness may be formed on both substrates.

(Embodiment 2) (FIG. 2) shows a second embodiment of the present invention. A transparent conductive film (ITO) is formed on the glass substrates 2 and 9.
Films 3 and 8 are formed, and the insulating film 1 is formed on one transparent conductive film 8.
2, photosensitive polyimide is formed by photolithography. At this time, the film thickness is changed by repeating photolithography several times to form at least two kinds of films having different film thicknesses. That is, the distance between the upper and lower panels is made different at least at three places.

After cleaning the glass substrates 2 and 9, a photosensitive polyimide is formed as a spacer 11 on one substrate 9 by photolithography. On top of that, SiO films are formed as the alignment films 4 and 7 by oblique vapor deposition. The seal resin 5 is printed on the edge of the surface of the glass substrate 2 on which the alignment film 4 is provided, and the two substrates 2 and 9 are laminated and heated so that the alignment film surfaces face each other and heated. The resin 5 is cured. After that, vacuum deaeration is performed, and the liquid crystal 6 is injected between the two glass substrates 2 and 9.

The panel gap is set to 5.3 μm, 6.5 μm and 7.6 μm at each electrode. When a polarizing plate is attached to this panel as shown in (Fig. 5), the transmittance in each panel gap is as shown in (Fig. 4), so when voltage is applied to all pixels, it is black, and no voltage is applied to all pixels. That is, white is blue when only pixels with a gap of 5.3 μm are not applied, blue is shown when pixels with a gap of 6.5 μm are not applied, and red when only pixels with a gap of 7.6 μm are not applied. Thus, color display can be performed without using a color filter.

(Embodiment 3) A third embodiment of the present invention will be described. A photosensitive polyimide is formed as an insulating film 12 on one glass substrate 9 by photolithography. At this time, the film thickness is changed by repeating photolithography several times to form at least two kinds of films having different film thicknesses. That is, the distance between the upper and lower panels is made different at least at three places.

On the glass substrates 2 and 9, a transparent conductive film (I
After forming and cleaning TO films 3 and 8, a photosensitive polyimide is formed as a spacer 11 on one substrate 9 by photolithography. On top of that, SiO films are formed as the alignment films 4 and 7 by oblique vapor deposition. The seal resin 5 is printed on the edge of the surface of the glass substrate 2 on which the alignment film 4 is provided, and the two substrates 2 and 9 are laminated and heated so that the alignment film surfaces face each other and heated. The resin 5 is cured. After that, vacuum deaeration is performed, and the liquid crystal 6 is injected between the two glass substrates 2 and 9.

The panel gap is set to 5.3 μm, 6.5 μm, and 7.6 μm at each electrode. When a polarizing plate is attached to this panel as shown in (Fig. 5), the transmittance in each panel gap is as shown in (Fig. 4), so when voltage is applied to all pixels, it is black, and no voltage is applied to all pixels. That is, white is blue when only pixels with a gap of 5.3 μm are not applied, blue is shown when pixels with a gap of 6.5 μm are not applied, and red when only pixels with a gap of 7.6 μm are not applied. Thus, color display can be performed without using a color filter.

Although the orientation film is formed by the oblique evaporation method in this embodiment, it may be formed by the rubbing method after applying the polyimide resin or the like. Further, the panel structure is not limited to the transmissive type, but may be the reflective type. Further, in this embodiment, 3
Although three types of steps are provided to display the primary colors, two types of steps may be provided if only two colors are needed, and four or more types of steps may be provided if more than four colors are displayed. It is also possible to display colors other than the primary colors by combining the panel gaps. Further, in order to utilize the effect of birefringence, the twist angle of the liquid crystal molecules (twist angle) is preferably 180 ° or more.

[0021]

As described above, according to the present invention, the film thickness of at least one electrode of a liquid crystal panel in which a chiral nematic liquid crystal that is twisted and oriented is sandwiched between two substrates with electrodes is changed, and a plurality of electrodes are formed. By forming the step, it is possible to perform color display without a color filter, and it is possible to inexpensively produce a color liquid crystal panel.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a liquid crystal panel according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a liquid crystal panel according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a liquid crystal panel according to a third embodiment of the present invention.

FIG. 4 is a graph showing the relationship between panel gap and transmittance.

FIG. 5 is a schematic diagram showing the structure of an STN panel.

FIG. 6 is a sectional view showing the structure of a conventional liquid crystal panel.

[Explanation of symbols]

 1 Analyzer 2,9 Glass Substrate 3,8 Electrodes 4,7 Alignment Film 5 Seal Resin 6 Liquid Crystal 10 Polarizer 11 Spacer

Claims (5)

[Claims] 1. A liquid crystal panel in which a plurality of steps are formed by changing the film thickness of at least one electrode of a liquid crystal panel in which a twisted and aligned chiral nematic liquid crystal is sandwiched between two substrates with electrodes. 2. A plurality of insulating films having different thicknesses are formed on at least one electrode of a liquid crystal panel in which a twisted and aligned chiral nematic liquid crystal is sandwiched between two substrates with electrodes. Liquid crystal panel with steps. 3. A plurality of insulating films having different thicknesses are formed under at least one electrode of a liquid crystal panel having a chiral nematic liquid crystal which is twisted and aligned between two substrates with electrodes. Liquid crystal panel with steps. 4. The liquid crystal panel according to claim 1, wherein a step is set so that blue, green, and red light is mainly transmitted on each electrode. 5. A twist angle of liquid crystal molecules is set to 1
The liquid crystal panel according to claim 1, 2 or 3, wherein the liquid crystal panel has an angle of 80 ° or more.