JPH11281964A - Picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to waste or recycle through fractional collection of various materials without discharging them into the natural environment by adding a thin film material having a removal means between a support substrate and other structures than the support substrate. SOLUTION: A polyimide film 2 of 1 μm in thickness is formed on a glass substrate 1 on the side where picture electrodes are formed. This polyimide film 2 is spread by the spin coat method, and has been heat-annealed at 300 degrees for 30 minutes to increase heat resistance and chemical resistance to subsequent processes. On the other hand, a polyimide film 10 of 1 μm in thickness is formed also under a counter glass substrate 9 by means of the spin coat method. This film is also heat-annealed at 300 degrees for 30 minutes. When the liquid crystal display device is wasted after its life, it is possible to separate the glass substrate from the other stractural materials by lifting-off by peeling off the polarized light films 8, 15 and then, dissolving the polyimide film by hydrolysis reaction with hydrochloric acid by soaking the substrate in the hydrochloric acid solution of 30% concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin image display device.

[0002]

2. Description of the Related Art A conventional image display device is disclosed in
As in the liquid crystal display device described in Japanese Patent No. 159520, a thin film of a semiconductor, an insulator, or a metal is directly deposited on a glass substrate as a support substrate.

[0003]

In the above prior art, since a thin film of an insulator, a semiconductor, or a metal is strongly adhered to the glass substrate, the harmful effect on the glass substrate when the display device is discarded after the service life thereof is reached. It has been difficult to selectively separate a semiconductor containing an impurity or a metal thin film containing a heavy metal, separate and recover various materials without releasing them to nature, or to discard or recycle them.

[0004]

In order to solve the above problems, a feature of the present invention is to provide a thin film material having a removing means between a supporting substrate and a structure other than the supporting substrate constituting the image display device. It has been added.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a liquid crystal display device will be described below with reference to the drawings. FIG. 1 is a sectional view of an active matrix type liquid crystal display device according to the present invention. A polyimide film 2 having a thickness of 1 μm is formed on a glass substrate 1 on which a pixel electrode is to be formed. This polyimide film 2 is applied by a spin coating method, and is used for improving heat resistance and chemical resistance against the subsequent processes.
It was heat-annealed at 00 degrees for 30 minutes. A thin film transistor 3 serving as a liquid crystal driving switching element having a gate electrode (also serving as a scanning line) made of Cr, a gate insulating layer made of silicon nitride SiN, and a channel layer made of amorphous silicon a-Si on the polyimide film 2. And a signal line 4 made of Al and a pixel electrode 5 made of ITO (Indium Tin Oxide). The semiconductor and the metal thin film forming the thin film transistor 3, the signal line 4, and the pixel electrode 5 are formed by plasma CVD and sputtering, respectively, and processed into desired shapes by photolithography and dry etching. A protective film 6 formed by a plasma CVD method is formed on the thin film transistor 3 and the signal line 4.
Further, an alignment film 7 is applied on the protective film 6 and the pixel electrode 5 by a spin coating method. The back side of the substrate 1 (FIG. 1)
In the figure, a polarizing plate 8 is attached to the lower surface.

On the other hand, a 1 μm thick
m of the polyimide film 10 is also formed by the spin coating method. This film was also thermally annealed at 300 degrees for 30 minutes. Under this polyimide film 10, a black matrix light shielding layer 11 made of Cr and a color filter 1 are formed.
2, a common electrode 13 made of ITO is formed thereunder. Under the common electrode 13, an orientation film 14 is applied by a spin coating method. The back side of the substrate 9 (FIG. 1)
A polarizing plate 15 is affixed to the upper surface). The liquid crystal 16 is sealed between the alignment film 7 and the alignment film 14, and the surface of the alignment film is surface-treated, so that the liquid crystal molecules are uniformly arranged. Since the transmittance of the polyimide film to visible light is 90% at a thickness of 1 μm, the transmittance is 2%.
The attenuation ratio due to the polyimide film applied to two substrates is 2
Since it is about 0%, there is no problem in applying a polyimide film to two glass substrates for practical use of a liquid crystal display device.

As described above, when a polyimide film is added between a glass substrate of a support substrate constituting a liquid crystal display device and a structure other than the support substrate such as a thin film transistor, when the liquid crystal display device which has reached the end of its useful life is discarded, After peeling off the polarizing films 8 and 15, the polyimide film is immersed in an aqueous solution of hydrochloric acid having a concentration of 30% as shown in FIG. Structures other than the glass substrate, such as the thin film transistor 3 and the pixel electrode 5, can be easily separated. The separated glass substrate can be recycled, and Cr or ITO which does not dissolve in hydrochloric acid can be used.
Organic substances such as (including In and Sn) and other alignment films can be removed by a filtration method as shown in FIG. 2B, and it becomes easy to collect them so as not to release them to the natural world.

In the above embodiment, the thin film added between the glass substrate and the structure constituting the liquid crystal display device is made of polyimide. However, in the present invention, the display device has a removing means such as etching removal by a chemical solution. Any type can be used as long as it has physical properties such as heat resistance and strength sufficient to form the film, and transparency to visible light.

In the above embodiment, lift-off was caused by dissolution etching of polyimide with hydrochloric acid to separate the glass substrate and other component materials. In the present invention, however, the thin film between the support substrate and other component materials was removed to remove the support substrate. As long as the material can be separated from other component materials, any removal means such as dry etching using gas or melting by heating can be used.

In the above embodiments, the present invention is applied to a liquid crystal display device. However, the present invention is not limited to a plasma display device as long as it is a thin image display device using a supporting substrate such as a glass substrate, a plastic substrate or a metal substrate. Panel (PD
P), field emission display (FE
D), any applicable image display method such as an electroluminescence (EL) display.

As described above, by applying the present invention to an image display device, when the image display device is discarded after its service life has expired, recycling or recycling of the support substrate, metal and semiconductor constituting the image display device can be performed. A thin image display device that facilitates separation and collection can be manufactured.

[0012]

According to the present invention, when an image display device whose service life has expired is discarded, it is easy to recycle or separate and collect the support substrate, metal and semiconductor constituting the image display device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a liquid crystal display device to which the present invention is applied.

FIG. 2 is a diagram illustrating a method of separating a glass substrate and other structures when the liquid crystal display device is discarded.

[Explanation of symbols]

Reference numeral 1: a glass substrate on the pixel electrode side; 2, 10: a polyimide film;
3 thin film transistor, 4 signal line, 5 pixel electrode, 6
... Protective film, 7,14 ... Orientation film, 8,15 ... Polarizer, 9 ...
Opposite glass substrate, 11 ... black matrix, 12 ...
Color filter, 13: common electrode, 16: liquid crystal.

Claims (6)

[Claims] In an image display device formed using one or two support substrates, when the image display device is discarded, a thin film material between the support substrate and other component materials is removed. An image display device characterized by having a structure in which a supporting substrate and other component materials can be separated from each other by means of a liquid crystal display, and the respective materials can be separated and collected. 2. A liquid crystal display device comprising a support substrate made of glass, plastic or metal,
When the liquid crystal display device is discarded, the support substrate and other component materials can be separated by removing a thin film material between the support substrate and other component materials, and each material can be separated and collected. A liquid crystal display device characterized by the above-mentioned. 3. An image display device formed using one or two support substrates, wherein when the image display device is discarded, lift-off is performed by etching a thin film material between the support substrate and other component materials. An image display device characterized by having a structure in which a supporting substrate and other component materials can be separated from each other by means of a liquid crystal display, and the respective materials can be separated and collected. 4. A liquid crystal display device comprising a support substrate made of glass, plastic or metal,
When the liquid crystal display device is discarded, the support substrate and other component materials can be separated by lift-off by etching of a thin film material between the support substrate and other component materials, and each material can be separated and collected. A liquid crystal display device characterized by the above-mentioned. 5. A structure of an image display device formed using one or two support substrates, wherein a solution is dissolved between a support substrate and a structure other than the support substrate constituting the image display device by a chemical solution. The structure of the image display device, characterized by having a structure to which a thin film material is added. 6. A liquid crystal display device having a support substrate made of glass, plastic, or metal, wherein a liquid chemical is dissolved between the support substrate and a structure other than the support substrate which constitutes the liquid crystal display device. A liquid crystal display device having a structure to which a thin film material is added.