JPH01210931A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To easily recognize display pattern parts to display a colorful image by using a color polarizing film as one polarizing film and providing a color filter in a part corresponding to the display pattern. CONSTITUTION:Electrodes 2A and 2B and orienting films 3A and 3B are formed on substrates 1A and 1B, and light shielding films 4 are formed in parts other than the display pattern, and liquid crystal 5 is sealed in. A pair of polarizing films 7A and 7B are arranged on both faces of this liquid crystal cell, and a color filter 8 and a light source are arranged on the rear side, and a color polarizing film is used as the polarizing film 7B on the rear side. When axes of polarization of this pair of polarizing films are made parallel with each other and a red color polarizing film is used as the color polarizing film and a yellow color filter is used, yellow of the color filter is recognized in display pattern parts to which a voltage is applied, and yellowish red of the mixed color of the filter and the polarizing film is recognized in display pattern parts to which a voltage is not applied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid crystal display device that performs negative type display in which a light shielding film is formed.

[Prior Art] Conventionally, liquid crystal display devices used for displaying automobile instruments or clocks, etc., often employ a negative type display in which bright characters, figures, etc. are displayed on a dark display surface.

In a negative type liquid crystal display device, no voltage is applied to the liquid crystal layer in the background area, so the liquid crystal molecules are twisted, and the plane of polarization of the light is twisted along this, making the polarization axes of the pair of polarizing films parallel. This arrangement prevents light from passing through the background portion.

In the background area of such a negative type liquid crystal display device, light travels with a twisted plane of polarization, but since the refractive index differs depending on the color of the light, there is a problem in that a certain amount of light of a specific color passes through. For this reason, the background portion appears to be dimmed to some extent, which causes a deterioration in appearance when viewed in a dark room or at night.

In order to improve this problem, it has been considered and put into practical use to provide a light-shielding film in areas other than the areas corresponding to the display pattern of the negative liquid crystal display device to prevent light from leaking from the background area.

[Problems to be Solved] Such a negative liquid crystal display device provides high-quality display because there is no leakage of light from the background.

However, since it is a negative type liquid crystal display device, light is transmitted only through the portions to which voltage is applied. For this reason, the display pattern portion has been limited to displaying a specific color instead of black.

Furthermore, when a polarizing film with an extremely high degree of light shielding is used, it is difficult to determine which part of the display pattern is displayed when the display is off. If a polarizing film with a low degree of polarization is simply used, light will leak and the color will be the same as when the display is on, so there is a risk of misidentification.

[Means for Solving the Problems] The present invention has been made to solve these problems, and includes a nematic liquid crystal layer sandwiched between substrates provided with electrodes,
In a negative type liquid crystal display device in which a pair of polarizing films are arranged on both sides of a liquid crystal cell with a light shielding film provided in areas other than those corresponding to the display pattern, a color polarizing film is used for one polarizing film, and a color polarizing film is used for the display pattern. A liquid crystal display device characterized in that a color filter is provided in a corresponding part, and a liquid crystal display device characterized in that a color polarizing film is used for one polarizing film and a color light source is provided on the back side. The light source is placed on the back side of the polarizing film, and the nematic liquid crystal
0' twist, a pair of polarizing films are arranged so that their polarization axes are almost parallel, a color polarizing film is used as the polarizing film on the back side, and a color filter is provided between the polarizing film on the back side and the light source. The present invention provides a liquid crystal display device characterized by the following.

The present invention is a negative type liquid crystal display device in which a light-shielding film is provided in the background part, and by using a color polarizing film as one of the polarizing films and using a color filter in combination, it is possible to display a negative image regardless of whether a voltage is applied or not. .

Since the display pattern portions are always displayed in different colors, the display pattern portions are easily recognized and are less likely to be misidentified.

The present invention provides a negative-type liquid crystal display in which a nematic liquid crystal layer is sandwiched between substrates provided with electrodes, and a pair of polarizing films are arranged on both sides of a liquid crystal cell in which a light-shielding film is provided in areas other than those corresponding to the display pattern. Applies to equipment.

In other words, it can be applied to a normal negative type liquid crystal display device in which a pair of polarizing films is arranged so that light passes through the polarizing axis of the polarizing film at the voltage-applied portion, and it can also be applied to a normal negative type liquid crystal display device in which the polarizing axis of the polarizing film is set so that light passes through the part where a voltage is applied. It can also be used in highly light-shielding negative-type liquid crystal display devices, in which a pair of polarizing films are arranged so that light passes through the exposed areas, and a voltage is applied at the areas where the light is to be blocked. Be applicable.

In the present invention, by using a color polarizing film and a color filter in combination, it is possible to change the color between the mixed color of the color polarizing film and the color filter and the color of the color filter. Alternatively, by using a color polarizing film and a color filter together, it is possible to change the color between the mixed color of the color polarizing film and the color of the color light source and the color of the color light source.

The present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view showing the basic configuration of a liquid crystal display device of the present invention using color filters.

In Fig. 1, l^, IB are glass or plastic substrates, and 2A, 2B are In formed on the substrates.
These are electrodes such as 20s-3n02 (ITO) and 5nOa, and 3A and 3B are alignment films, and a light shielding film 4 is formed in a portion other than the display pattern. 5 is a peripheral seal; 6 is an enclosed liquid crystal; a pair of polarizing films 7^, 7B are placed on both sides of this liquid crystal cell; a color filter 8 and a light source 9 are placed on the back side. The polarizing film 7B on the back side is a color polarizing film.

FIG. 2 is a sectional view showing the structure of another example of the liquid crystal display device of the present invention using a color light source.

In Fig. 2, 11^, IIB is a substrate made of glass, plus deck, etc., +2A, 12B are electrodes of 1nJi-3nO* (ITO), 5nOs, etc. formed on the substrate, and 13^,! 3B is an alignment film, and a light shielding film 14 is formed in a portion other than the display pattern. I5 is a peripheral seal, 16 is a sealed liquid crystal, a pair of polarizing films +7A and 17B are arranged on both sides of this liquid crystal cell, and a color light source I9 is arranged on the back side.

The polarizing film 17B on the back side is a color polarizing film.

In the present invention, this pair of polarizing films +? Either one of the polarizing films A and 17B is a color polarizing film.

Specifically, the alignment film is formed so that it has a 90" twist, and the liquid crystal molecules twist approximately 90" when no voltage is applied.
@Twisted state, and the polarization axis of the polarizing film is parallel to the orientation direction of either substrate, and the polarization axes of the two polarizing films may be arranged so as to be parallel to each other. As a result, light will not pass through the areas where no voltage is applied.
It becomes a negative type display.

In addition, the alignment film is formed in the same way, but the polarization axis of the polarization film is
The two polarizing films are arranged so that their polarization axes are perpendicular to each other, parallel to or perpendicular to the alignment direction of each substrate, and the light is applied without applying a voltage to the electrode in the area where the light is transmitted. It is also possible to use a liquid crystal display device in which a voltage is applied to the electrodes of the portions where it is desired to cut off the voltage. This configuration of a liquid crystal display device is normally used in a positive type liquid crystal display device, but since the background part other than the display pattern part is covered with a light-shielding film, driving can be performed in reverse as described above. Therefore, a negative type liquid crystal display device with a high degree of light shielding can be obtained.6 The present invention can also be applied to such a liquid crystal display device.

However, even if this orientation direction is 90°, the twist of the liquid crystal may be 2706 or 450 m instead of 90'', or the orientation direction may not be exactly 90° but 85° or +0
It may be 0°. Further, the angle between the polarization axis and the alignment direction is not limited to being parallel or perpendicular, but may be slightly shifted from that, such as 5° or 85°.

The substrate used in the present invention may be a transparent substrate made of glass, plastic, etc., and the inner surface thereof has 1naOs-3
A transparent electrode is formed using a transparent conductive film such as nOz (1'T O) or Snow. In addition, a film of a low-resistance conductive material such as metal or conductive paste may be formed on the transparent electrode in the form of thin lines, a grid, or the like.

The alignment film is made of an organic polymer such as polyimide, polyamide, polyvinyl alcohol, etc. -5rOn-T+0. .

Any alignment film that aligns the liquid crystal, such as rubbing a film made of an inorganic material such as AIJs or diagonally depositing it, may be used.
It may be one layer or two layers as required.

The light shielding film may be provided on the inner surface or the outer surface of the liquid crystal cell. However, it is preferable to form the light-shielding film on the inner surface of the liquid crystal cell because it is less likely to cause misalignment between the display pattern and the light-shielding film when viewed from an oblique direction.

This light-shielding film is formed on the background portion of the display, and usually only needs to be formed on one substrate. Of course, it may be formed separately on both substrates, but forming on one substrate requires fewer steps and is more productive.

This light-shielding film can be formed by vapor-depositing or plating a metallic light-shielding film such as aluminum, nickel, or chromium through a transparent electrode and an insulating film, or by printing a light-shielding ink such as carbon or other pigment paste. It may be formed by forming.

In the present invention, one of the polarizing films used is a color polarizing film. When this color polarizing film is combined with a black and white polarizing film so that its polarization axes are parallel or perpendicular, when the polarization axes are parallel, light passes through and becomes transparent, and the polarization axes are perpendicular. Sometimes the light is blocked and that particular color becomes visible. In the present invention, by combining such a color polarizing film and a color filter or a color light source, the mixed color of the color polarizing film and the color filter or color light source and the color of the color filter or color light source can be changed by driving a liquid crystal cell. It is possible to change the color between

This color polarizing film may have different colors partially or may be a black and white polarizing film. The color polarizing film is preferably disposed on the back side because it has poor durability and looks better when the bonded portion is not visible.

Further, the color filter may be of a different color from the color polarizing film, and may be formed inside the cell or outside the cell. When changing the color in response to a detailed display pattern, it is preferable to form it within the cell, that is, two or so below the electrode.In other cases, it is preferable to form it on the back side of the cell, especially the back side of the color polarizing film on the back side. It is preferable to arrange it in 1 because it is easy to manufacture.

Furthermore, when using a color light source, a light source of a color different from that of the color polarizing film may be used.

These color filters and color light sources may be of one color or may be used in combination of multiple colors. When using multiple colors or when manufacturing various products with only different colors, it is preferable to use a color filter because the colors can be easily changed. In particular, by placing color filters between the color polarizing film and the light source, color filters of multiple colors can be placed side-by-side, making the connecting parts invisible, giving a good appearance and making it easy to change colors. becomes.

When using a color filter, a light source is placed on the back side of the color filter. As the light source, a light emitting source such as a lamp, a fluorescent tube, an Ell, a light emitting diode, a light guide, an external light guide, etc. can be used.

The sealing material used for the peripheral seal may be ordinary sealing material such as epoxy resin or silicone resin, and usually an opening is formed in a part of the sealing material, and after forming a cell, liquid crystal is injected through the opening. , the opening may be sealed.

The liquid crystal to be injected may be an ordinary nematic liquid crystal, which usually has a twist of approximately 90", but
A chiral substance may be added to give a twist of 0° or 450°.

In addition, active elements, fixed display portions, reflective layers, touch switches, non-reflective coating layers, etc., which are known addition means for liquid crystal display devices, may be formed inside or outside the cell.

[Function] In the present invention, by combining such a color polarizing film and a color filter or a color light source, the color polarizing film and the color filter or color light source can be mixed together depending on the voltage applied to the electrodes of the liquid crystal cell. A color change between the color and the color of the color filter or the color of the color light source is possible.

Specifically, in the example shown in Figure 1, if the polarization axes of the pair of polarizing films are made parallel, and a red color polarizing film is used as the color polarizing film, and a yellow color filter is also used, the display pattern portion to which a voltage is applied The yellow color of the color filter will be recognized, and the display pattern portion to which no voltage is applied will be recognized as a slightly yellowish red color that is a mixture of the color filter and the color polarizing film.

[Example] Example I 1 on a glass substrate having an undercoat of Sing]
0 to a thickness of 1000 mm, patterned by photoetching, and formed electrodes for the bar graph display area.
An overcoat layer for an alignment film of 500 polyimide was formed on this film, and rubbed to form an alignment pattern.
A segment electrode substrate was manufactured.

In addition, ITO was formed to a thickness of 1000 nm on the glass substrate with the undercoat of the Si port 2, buttered by photoetching, and carbon ink was used to offset the areas other than the display pattern area of the bar graph display area. A light shielding film having a thickness of approximately 2 μm and a transmittance of 0.3% was formed by printing.

Furthermore, on top of that, an insulating overcoat of SiO
An overcoat layer for an alignment film of polyimide of 500 layers was further formed. The inner and outer membranes were rubbed in a direction perpendicular to the orientation direction of the segment electrode substrate to produce a common electrode substrate.

With the configuration shown in Figure 1, Merck's ZL is used as the liquid crystal.
I-2978-000 was used, and the cell gap was 5.7 pm.

A black and white polarizing film is placed on the front side of the cell so that the orientation direction of the front substrate and its polarization axis match, and a red color polarized film is placed on the back side of the cell so that the orientation direction of the back substrate and its polarization axis are perpendicular to each other. The membrane was placed. As a result, the polarizing films on both sides are arranged so that their polarization axes are parallel to each other.

A yellow color filter was placed on the back side, and a white light source using a three-wavelength cold cathode discharge tube was placed on the back side, and driving was performed by applying a voltage of IOV.

As a result, the background area is shielded by the light-shielding film and looks good with no light leakage, yellow light passes through the bar graph display area where voltage is applied, and the OFF area where no voltage is applied has a slightly yellowish tinge. The light was transmitted in red color.

As a result, the bar graph display changes between slightly yellowish red and yellow, and the entire display part can be recognized regardless of whether it is on or off, and the on part can be easily identified by focusing on the whole part. I was able to identify it. In this case, since the OFF part and the ON part have different colors, even if light is transmitted through both parts, misidentification is less likely to occur, unlike when light of the same color leaks out.

Example 2 In addition to the bar graph display part of Example 1, a day-shaped number display part was used, a color polarizing film was placed only in the bar graph display part, and a black and white one was placed in the day-shaped number display part. A liquid crystal display device was produced in the same manner as in Example I except that the polarizing film was disposed.

In this liquid crystal display device, the bar graph display part changes between slightly yellowish red and yellow, similar to the liquid crystal display device of Example 1, and the date-shaped number display part changes between red and yellow. The display changed between black and yellow.

Example 3 The polarizing films of Example 2 were arranged so that the polarization axes of both polarizing films were perpendicular to each other. That is, the polarization axes of the color polarizing film and the black and white polarizing film on the back side were arranged to match the orientation direction of the substrate on the back side. A liquid crystal display device was produced in the same manner as in Example 2 except for this.

As a result, the background part is shielded by the light-shielding film and looks good with no light leakage, yellow light passes through the bar graph part where no voltage is applied, and the OFF part where voltage is applied has a slightly yellowish tinge. Light was transmitted in red, which was the opposite situation to that in Example 1.

Further, this liquid crystal display device has a polarizing film arranged in the same way as a positive type liquid crystal display device.

In the day-shaped number display area, yellow light was transmitted through segments where no voltage was applied, and off-segments where voltage was applied were extremely black, with almost no light passing through. .

The light leakage from the off-segment portion of the Japanese-letter-shaped numeral display portion is extremely low compared to the case of Example 2, and the ratio of light transmittance between the on-segment portion and the off-segment portion (
The contrast ratio) was 1000 or more, and a liquid crystal display device with an extremely high degree of light shielding and a high contrast ratio was obtained.

Example 4 A liquid crystal display device was produced in which a yellow color light source was placed on the back side of a color polarizing film in place of the color filter and light source of Example 1.

This liquid crystal display device was capable of displaying images similar to those of Example 1.

[Effect of the invention 1] The present invention is a negative type liquid crystal display device with a light-shielding film provided on the back, and by using a color polarizing film as one of the polarizing films and using a color filter or a color light source. The display pattern part is always displayed in a different color tone regardless of whether voltage is applied or not, so the display pattern part is easily recognized and a colorful display is possible.
In addition, misidentification due to light leakage at the display pattern portion, which occurs in ordinary black and white liquid crystal display devices, is less likely to occur.

Furthermore, by placing the color polarizing film on the back side, even if the color polarizing film is pasted, the bonded part will not be visible, and by not providing the less durable color polarizing film on the outer surface, the color polarizing film will deteriorate. Easy to prevent.

In addition to this, the present invention includes, within the scope that does not impair the effects of the present invention,
Various applications can be made to known liquid crystal display devices.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic configuration of the present invention using color filters. FIG. 2 is a sectional view showing another configuration of the present invention using a color light source. Board + IA, III, IIA,
IIB electrode = 2A, 2B, 12^,
12B alignment film: 3A, 3B, 13A,
13B light shielding film: 4.14 Peripheral seal: 5.15 Liquid crystal = 6.16 Polarizing film: 7A, 7B% +7A,
! 7+1 color filter: 8 light source: 9 color light source = 19

Claims (3)

[Claims] (1) A negative-tone liquid crystal display device in which a nematic liquid crystal layer is sandwiched between substrates provided with electrodes, and a pair of polarizing films are placed on both sides of a liquid crystal cell with a light-shielding film provided in areas other than those corresponding to the display pattern. A liquid crystal display device characterized in that one of the polarizing films is a color polarizing film, and a color filter is provided in a portion corresponding to a display pattern. (2) A nematic liquid crystal layer is sandwiched between substrates provided with electrodes, and a pair of polarizing films are placed on both sides of the liquid crystal cell, which has a light-shielding film in areas other than those corresponding to the display pattern, and the back side of the polarizing film on the back side. In a negative type liquid crystal display device in which a light source is arranged in a negative tone display device, the nematic liquid crystal is twisted approximately 90 degrees, and a pair of polarizing films are arranged so that their polarization axes are substantially parallel,
A liquid crystal display device characterized in that a color polarizing film is used as the polarizing film on the back side, and a color filter is provided between the polarizing film on the back side and the light source. (3) A negative-type liquid crystal display device in which a nematic liquid crystal layer is sandwiched between substrates provided with electrodes, and a pair of polarizing films are placed on both sides of a liquid crystal cell with a light-shielding film provided in areas other than those corresponding to the display pattern. A liquid crystal display device characterized in that one polarizing film is a color polarizing film and a color light source is provided on the back side.