JP2003015115A - Polymer dispersed liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique to simply and economically eliminate any leaked display on a part other than a display part in liquid crystal displaying for the purpose of manufacturing a PN-LCD(polymer network-liquid crystal display) element with high practicability. SOLUTION: In the liquid crystal display element comprising a polymer dispersed liquid crystal filled between two transparent substrates respectively having transparent electrode films with desired electrode shapes formed on respective inside surfaces, the polymer dispersed liquid crystal display element is characterized by applying an opaque coating material containing a white pigment to the part other than the part to become liquid crystal display electrodes on the surface side transparent substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer-dispersed liquid crystal display device, and more particularly to a polymer-dispersed liquid crystal display device which does not perform unnecessary display such as flicker other than a display portion during a display operation.

[0002]

2. Description of the Related Art In recent years, polymer dispersed liquid crystals (PN-LCD) have been used for applications such as displays and light control glasses. In this PN-LCD, liquid crystal fine particles having a wavelength of light (0.5 to several μm) are dispersed in a polymer material. Depending on the presence or absence of an electric field, a light transmission state (transparent) and a light scattering state can be obtained. Change between states (white turbidity).

Since the PN-LCD utilizes light scattering, it is not necessary to use a polarizing plate used in many conventional liquid crystal elements, so that the transmittance is high and the light utilization efficiency is good. There are features. Further, in manufacturing a liquid crystal display device using a PN-LCD, it is not necessary to perform a molecular alignment treatment by rubbing, so that the manufacturing process is simplified and the area can be easily increased.

Further, since the liquid crystal material itself is in the form of a film, if a plastic film is used as a transparent substrate provided with a transparent conductive film for applying a voltage, a flexible film-like liquid crystal panel as a whole can be obtained. It has the feature that it can. Among the above features,
The fact that it is not necessary to use a polarizing plate shows the possibility of providing a liquid crystal display that is bright and has a low viewing angle dependency, and it is expected that the PN-LCD will be put to practical use as a liquid crystal display.

However, when the PN-LCD display element is used for a liquid crystal display, there is a drawback in that unnecessary display such as flickering may occur on the display portion other than the display portion, which has been a practical problem.

That is, since the PN-LCD has a characteristic that the change of the light transmission characteristic due to the piezoelectric printing is gradual and lacks in steepness, and that it has different transmittance values depending on the increase and decrease of the voltage, The liquid crystal display element used cannot display sufficiently without static drive. Then, in order to perform the static drive, it is necessary to wire each electrode corresponding to the display pixel and apply a voltage to each of these electrodes.

However, the transparent substrate used for the liquid crystal display element has an inner surface coated with an electrode-shaped transparent conductive film. This electrode shape includes display electrodes in the shape of display pixels, A connection electrode for supplying a current to the display electrode is also included. In such a state, if the necessary voltage is applied to the display electrodes (generally called common electrodes) on the back side substrate of the liquid crystal display element and the display electrodes (generally called segment electrodes) on the front side substrate of the liquid crystal display element. In addition to the display pixel to be originally displayed, for example, the display is also performed in the portion sandwiched between the common electrode and the connection electrode for flowing the current to the segment electrode. In particular, when dot matrix display is performed, the number of connection electrodes of each segment electrode becomes extremely large, and unnecessary display (hereinafter referred to as “leak display”) increases, resulting in flicker in parts other than display pixels. , There was a problem of concern.

[0008]

Therefore, in order to manufacture a highly practical PN-LCD display element, it is possible to easily and economically eliminate the leak display other than the display portion during the liquid crystal display. Was requested.

[0009]

As a result of research conducted by the present inventors to solve the above problems, the color tone of an opaque paint containing a white pigment is very similar to the appearance of the light scattering state of PN-LCD. By applying this opaque pigment to the portion other than the display pixels of the transparent substrate for liquid crystal display element,
Leak display is no longer observed, and P has a clean appearance
The present invention has been completed by finding that an N-LCD liquid crystal display device can be obtained.

That is, the present invention relates to a liquid crystal display device comprising a transparent electrode film formed in a desired electrode shape on the inner surface thereof and filled with a polymer dispersed liquid crystal between two transparent substrates. A polymer dispersed liquid crystal display device, characterized in that an opaque coating material containing a white pigment is applied to a portion other than a portion to be a display electrode.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the drawings showing the embodiments of the present invention.

FIG. 1 is a drawing showing a part of the electrode shape of a transparent substrate on the front surface side (hereinafter referred to as “segment electrode shape”) for a liquid crystal display element for dot matrix display, and FIG. 2 shows the same liquid crystal. It is drawing which shows a part of electrode shape (henceforth "common electrode shape") of the back surface side transparent substrate about a display element. In FIG. 1, 1A is a front transparent substrate, 2 is a unit segment electrode, 3 is a unit segment electrode wiring, and 4 is a segment electrode terminal. Also, FIG.
Inside, 1B is a rear transparent substrate, 5 is a unit common electrode, 6 is a common electrode wiring, and 7 is a common electrode terminal.

In the PN-LCD liquid crystal display element, the front transparent substrate 1A of FIG. 1 and the rear transparent substrate 1B of FIG. 2 are arranged such that the side provided with the transparent electrode film having a predetermined electrode shape is on the inside, and the PN is provided between them. -Manufactured by encapsulating the LCD. The unit segment electrode 2 and the unit common electrode 5 that face each other
When voltage is applied to both sides of P
The N-LCD becomes transparent, and this portion functions as a transparent display pixel (in the case of a negative type).

However, the front side transparent substrate 1A has
A segment electrode wiring 3 for supplying a current to the unit segment electrode 2 is provided, while a rear transparent substrate 1B is provided.
The unit common electrode of has a continuous strip shape.
Then, these intersect with each other with the PN-LCD layer sandwiched therebetween, and the PN-LCD layer at this intersection becomes transparent when current flows through the segment electrode wiring 3 and the common electrode 5 at the same time, thereby performing unnecessary leak display. It will be.

In order to prevent such a leak display, the present invention contains a white pigment, for example, in a shape as shown in FIG. 3 so as to cover the portion 8 (hatched portion) other than the display pixels on the front transparent substrate 1A. An opaque paint (hereinafter referred to as "white paint") is applied. This coating may be performed on the front side or the back side (inside) of the front transparent substrate 1A.

The method of applying the white paint is not particularly limited as long as it can be applied accurately only to the portions other than the display pixels, and screen printing, offset printing, gravure printing and the like can be used. The white paint used may be a paint containing a white pigment such as titanium oxide or magnesium oxide, and the coating film component of this paint may be a resin component such as an acrylic, epoxy or alkyd. Furthermore, the thickness of the coating film of white paint is such that the leak display is hidden, for example, 0.5.
It may be about 20 μm.

The PN-LCD display device of the present invention is applicable not only to the liquid crystal display device for dot matrix display shown in FIGS. 1 to 3 but also to other types of display devices such as segment type display devices. Needless to say, in this case, it is necessary to accurately apply white paint to the portions other than the segment pixels.

Further, the PN-LCD display element of the present invention is
It is prepared by a conventionally known method except that the portion other than the display pixels of the front transparent substrate is covered with the white paint as described above. For example, as the transparent substrate used, a glass plate such as float glass, Pyrex (registered trademark) glass, quartz glass, or a transparent polymer substrate such as polyester or polyethylene terephthalate can be used. As the transparent conductive film layer provided on this transparent substrate, a conventionally known tin oxide film, indium oxide film, indium oxide film (ITO film) containing a few% of tin oxide can be used. A well-known technique such as a photoresist-etching technique can also be used as a method for forming the layer into a desired electrode shape.

Further, also as a spacer for accurately holding the two transparent substrates on the front surface and the back surface, an epoxy resin or the like, an acrylic synthetic resin, a benzoguanamine / melamine / formaldehyde condensate resin, a silica coat synthetic resin or the like is used. A publicly known one can be used, and a PN filled in a liquid crystal cell formed by two transparent substrates and a spacer.
-A known LCD, for example, Tokushusho Sho 61-5
02128, JP-A-62-1223, JP-A-1-1-1
In addition to those disclosed in Japanese Patent No. 98725 and the like, commercially available products can be used.

[0020]

The PN of the present invention obtained as described above
In the LCD display element, the portion other than the display pixels is covered with the white paint, so that the leak display generated in this portion can be completely hidden. The appearance of the part coated with the white pigment is very similar to the appearance of the PN-LCD in the light-scattering state, and therefore the PN-LC of the present invention.
The appearance of the D display element is not unnatural.

Therefore, the PN-LCD display device of the present invention is
The present invention can be advantageously used for various displays by completely preventing the leak display of the conventional PN-LCD display element.

[Brief description of drawings]

FIG. 1 is a view showing a part of an electrode shape of a front transparent substrate of a PN-LCD display device of the present invention.

FIG. 2 is a view showing a part of an electrode shape of a rear transparent substrate of the PN-LCD display device of the present invention.

FIG. 3 is a view showing a part of a portion coated with white paint of the PN-LCD display device of the present invention.

[Explanation of symbols]

1 ... Transparent substrate 4 ... Segment electrode terminal 1A ... Front side transparent substrate 5 ... Unit common electrode 1B ... Back side transparent substrate 6 ... Common electrode wiring 2 ... Unit segment electrode 7 ... Common electrode terminal 3 ……… Unit segment electrode wiring 8 ……… Parts other than display pixels 9 ……… Display pixel parts and above

Claims (2)

[Claims] 1. A liquid crystal display device having a transparent electrode film formed in a desired electrode shape on its inner surface and filled with polymer-dispersed liquid crystal between two transparent substrates. A polymer-dispersed liquid crystal display device, characterized in that an opaque coating material containing a white pigment is applied to a portion other than the portion to be the above. 2. The polymer dispersed liquid crystal display device according to claim 1, wherein the electrode shape is a shape of a segment electrode and a common electrode for performing dot matrix display.