Liquid crystal display element and manufacturing method thereof

Abstract

The invention discloses a liquid crystal display element including: a pair of display substrates each having a support and an electrode provided on one surface of the support; and a display layer provided between the electrodes of the pair of display substrates, wherein the display layer contains gelatin and liquid crystal drops or microcapsules; and the liquid crystal drops or microcapsules are densely arrayed in a monolayer, and a method of manufacturing the liquid crystal display element, including: applying to a surface of one of the display substrates which surface has the electrode, a coating solution in which liquid crystal drops or microcapsules are dispersed in a solution containing gelatin and a solvent, thereby forming a coating layer; and evaporating the solvent in the coating layer at a temperature not less than the freezing point of the gelatin to provide a display layer between the electrodes of the display substrates.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority under 35 USC 119 from Japanese Patent Application No. 2004-72928, the disclosure of which is incorporated by reference herein. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a liquid crystal display element having a display layer including liquid crystal drops or liquid crystal microcapsules, and a manufacturing method thereof. [0004] 2. Description of the Related Art [0005] The large quantity of paper consumed mainly in offices has become problematic, owing to both the destruction of forest resources to obtain the raw material for paper pulp as well as environmental pollution arising from the disposal and incineration of refuse. However, consumption of paper meant to be short-lived documentation for temporary viewing of electronic information has tended to increase more and more with the spread of personal computers and the development of information-...

AI Technical Summary

Benefits of technology

[0030] With regard to the liquid crystal display element of the invention, monodispersed liquid crystal drops or liquid crystal microcapsules are densely arrayed in a monolayer and the surface of the display layer is flat, whereby the problem can be avoided which arises in a case where polydispersed liquid crystal drops or liquid crystal microcapsules conventionally having a curved interface such as a spherical or elliptical shape are arrayed in multilayers and surface irregularities of a display layer are large. That is, the use of cholesteric liquid crystal as the liquid crystal allows a liquid crystal display element where the effective selective reflection area within liquid crystal drops or liquid crystal microcapsules is large (selective reflection color is bright), the color purity of reflection color does not decrease, unnecessary selective reflection does not occur, and a superior display is enabled that does not suffer from a turbid black display. The use of nematic liquid crystal and guest-host liquid crystal as the liquid crystal allows a liquid crystal display element having a superior threshold steepness.

Problems solved by technology

The large quantity of paper consumed mainly in offices has become problematic, owing to both the destruction of forest resources to obtain the raw material for paper pulp as well as environmental pollution arising from the disposal and incineration of refuse.

However, consumption of paper meant to be short-lived documentation for temporary viewing of electronic information has tended to increase more and more with the spread of personal computers and the development of information-based society, as with the Internet.

However, a cholesteric liquid crystal display element having a PDLC or PDMLC structure has problems in that selective reflection color in the planar state is low in brightness and color purity so as not to allow a clear color display, and that light transmittance in the focal conic state is poor such that contrast decreases due to a turbid black display in a display element provided with a black light-absorbing layer on the back thereof.

This also results in unnecessary scattered light in the focal conic state.

However, the problem arises of surface irregularities of a display layer becoming large due to the enlarged liquid crystal drops as described below.

Drying progresses in a state where individual dispersed liquid crystal drops cannot freely move, and thus the obtained display layer has a structure in which multiple liquid crystal drops or liquid crystal microcapsules are in an accumulated state, and additionally, a leveling effect on the liquid surface does not sufficiently come to bear, whereby a film is produced which easily obtains large surface irregularities in the liquid crystal drop layer, causing a particular disadvantage which will be mentioned later.

Problems have been described so far with regard to a cholesteric liquid crystal display element.

Also with regard to the display element of a PDLC or PDMLC structure using nematic liquid crystal or guest-host liquid crystal, when the liquid crystal drops are not orderly arrayed in a monolayer, there is occasionally a problem of large surface irregularities in a liquid crystal drop layer causing incorporation of air at the time that opposite substrates are laminated, and of a varying abundance ratio of liquid crystal to a polymeric binder in the direction of thickness deteriorating threshold steepness.

Therefore, the film-forming rate is low, and the method requires much time.

Consequently this method is not suitable for manufacturing a large surface-area device.

In addition, a complicated mechanism is required, such as a feedback device for controlling the pull-up rate while observing the state of the coating film.

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