JPS6045238B2 - liquid crystal display device - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in liquid crystal display devices.

It is known that a liquid crystal display device in which a nematic liquid crystal containing a pleochroic dye is interposed between a pair of electrode layers, at least one of which is transparent, can perform color switching by applying voltage.

However, pleochroic dyes that can be added to and mixed with the nematic liquid crystal (have solubility) have not been put to practical use because they are easily degraded by light, especially ultraviolet rays and heat. That is, azo dyes, merocyanine dyes, and the like are known as the above-mentioned pleochroic dyes, but when these dyes are used in liquid crystal display devices, their lifespans range from several hours to 100 hours, and the display color changes. It could not be put to practical use because the color fading or change to other hues resulted in a significant decrease in display contrast.
Accordingly, it is an object of the present invention to provide a color display type liquid crystal display device that exhibits stable functions even when exposed to light and heat.

To explain the present invention in detail below, the present invention provides a liquid crystal material layer containing at least one member selected from the group of metallocenes and metallocene derivatives having pleochroism between a pair of electrode layers, at least one of which is transparent. This is a liquid crystal display device characterized in that it is made of a liquid crystal display.

That is, the present invention is characterized in that, in a color display type liquid crystal display device, at least one member selected from the group of metallocene and metallocene derivatives is added to the liquid crystal material.

In the present invention, metallocenes and metallocene derivatives to be added and mixed into the liquid crystal material include, for example, di-π-diclopentadienyl iron, di-π-cyclopentadienyl nickel, di-π-cyclopentadienylinolet, 1
Examples include 1-di-n-butynolefuerocene and acetylferrocene, and the amount of these added may be about 0.1 to 1% by weight based on the liquid crystal material.

Further, the liquid crystal material that can be used may be one exhibiting a nematic phase, a cholesteric phase, a smectic phase, or a mixture thereof.

Next, examples of the present invention will be described.

Two glass plates each having a transparent electrode were prepared, and on the electrode-forming surfaces of these glass plates, an oblique vapor deposition layer of silicon oxide was provided, and in addition, a vertical alignment layer was provided on each of the glass plates.

Thereafter, the two glass plates were arranged so that the treated surfaces faced each other, and a spacer and a liquid crystal material were inserted between the opposing surfaces, and then sealed to form a liquid crystal display device as shown in cross section in the attached drawing. . In the figure, 1,1'' indicates a glass plate, 2,2''
″ is a transparent electrode 3, 3″ is a vapor deposited layer of silicon oxide, 4,
4'' is a vertical alignment layer, 5 is a spacer, and 6 is a liquid crystal material layer.The liquid crystal material layer 6 in the above is made of nematic phases 9A (a mixture of aromatic esters with negative dielectric anisotropy). It is made by adding 1% by weight of G-cyclopentadienyl iron to the product (trade name, Merck & Co., Ltd.).In the liquid crystal display device with the above structure, when no voltage is applied, the liquid crystal molecules are arranged almost vertically. The particles were arranged in an array, and the color was white.

However, when a voltage was applied through the transparent electrode, when the applied voltage exceeded 7 V, the color began to change to two orange colors, and color switching was possible by switching on and off the power supply. Further, in this case, when one polarizing plate was used, a clearer hue was obtained. As a life test, the liquid crystal display device having the above configuration was irradiated with ultraviolet rays with an output of 2.6 W to observe fading and changes in hue, but no fading or changes in hue were observed even after 5 (4) hours of irradiation.

Furthermore, when a performance test was conducted by heating the sheet at 80° C., no deterioration in display performance was observed even after 50 seconds. This resistance to fading and deterioration is such that conventionally known color display type liquid crystal display devices undergo fading or change in hue within one hour of UV irradiation, and display performance deteriorates after 200 hours of heating at 80°C. This can be said to be a significant difference compared to the current situation. As is clear from the above embodiments, the liquid crystal display device according to the present invention is hardly affected by ultraviolet rays or heat and can maintain and exhibit the required display function for a long time.

This, together with the fact that there are no particularly complicated operations or strict conditions in the manufacturing process, makes it suitable for practical use.

[Brief explanation of drawings]

The accompanying drawing is a sectional view showing an example of the structure of a liquid crystal display device according to the present invention. 1,1″・・・Glass plate, 2,2″・・・・・・
Transparent electrode, 3,3″...Vapour-deposited layer of silicon oxide, 4,
4″... Vertical alignment layer, 5... Spacer, 6... Liquid crystal material layer.

Claims (1)

[Claims] 1. A liquid crystal display characterized by interposing a liquid crystal material layer containing at least one member selected from the group of pleochroic metallocenes and metallocene derivatives between a pair of electrode layers, at least one of which is transparent. Device.