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Smectic A compositions for use in optical devices

A composition and smectic technology, applied in the fields of optics, nonlinear optics, chemical instruments and methods, etc., can solve the problems of unusable dyeing systems

Active Publication Date: 2015-06-03
CAMBRIDGE ENTERPRISE LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Historically, the choice between using a dyed or undyed system has depended on the application instructions, but because of the bleaching issues mentioned, dyed systems have not yet been used in outdoor applications

Method used

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  • Smectic A compositions for use in optical devices
  • Smectic A compositions for use in optical devices
  • Smectic A compositions for use in optical devices

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0210] The following table shows the physical characteristics of some organic pigments that can be used in the compositions of the present invention:

[0211]

[0212] Two LC base compositions ( Component A ) is made from:

[0213] 1. Organic SmA liquid crystal mixture

[0214] 8CB / 10CB / 8OCB mixture

[0215] S1023X (Merck ltd)

[0216] or

[0217] 2. Organic SmA mixture S5a (Merck ltd)

[0218] In both cases, cetyltrimethylammonium perchlorate was used as the ion dopant.

[0219] The organic pigment samples (component (C)) were selected on the basis of high light fastness and high weather fastness, relatively small primary particle size and variety of colors (red, green, blue, purple, yellow). The basic chemical structures of the selected pigments fall into the following four categories: 1) diketopyrrolo-pyrrole (DPP); 2) Cu phthalocyanine; 3) quinacridone; 4) benzimidazolone. These pigments have excellent lightfastness (typically 8) and weatherability (typically 4-...

Embodiment 2

[0242] Example 2 - UV Lifetime Test of Pigment / SmA Mixtures

[0243] Various pigments as detailed below were incorporated into base composition 1 in Example 1 and tested for their color in a UV laboratory (INVE96) containing a UV medium pressure lamp - Zp type over a test time of 1000 hours deteriorating.

[0244] Based on the UV lamp and sunlight spectra, the aging factor is estimated from the power ratio of UV lamp rays to sunlight. It was found that 1000 hours of UV lamp radiation is equivalent to about 7 years of solar exposure (at sea level), and the calculation of equivalent years of exposure to sunlight does not take into account seasonal changes and variations in the angle of incidence of sunlight.

[0245]Five pigment compositions were prepared, each containing a total of 3% of the five pigments (8G green, A2R blue, D3G red, E3B purple, P-BFS01 blue) One, and it was found that there was little color deterioration in any pigment composition after 1000 hours exposur...

Embodiment 3

[0249] Example 3 - Switching Life Test of Pigment / SmA Mixtures

[0250] Various pigments as detailed below were incorporated into Base Composition 1 in Example 1 at 3% and tested for the number of switching cycles (clear to opaque to clear) before failure. The results so far for relatively large single pixel cells (typically 10mm x 10mm in size) are as follows:

[0251] combination life (8G) Green / SmA ~2.6 million times (BFS-01) Blue / SmA ~2.9 million times (D3G) Red / SmA ~1.9 million times

[0252] Significant improvements in lifetime and color uniformity are expected in multi-pixelated configurations with small pixel sizes (approximately 1 mm x 1 mm or less).

[0253] Thus, the device of the present invention has a lifetime corresponding to exposure to sunlight of at least 7 years and can withstand an average number of switching operations of at least 2 to 3 million.

[0254] In summary, the main features of the optical device accor...

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Abstract

A liquid crystal smectic A composition which can be brought into a first stable state (left hand block in Figure 4) and at least one second stable state (Fig. 4), the composition is more disordered in at least one second stable state than in the first state. The radiation transfer properties of the first state and the second state are different. The composition comprises: (A) a liquid crystal material having a positive dielectric anisotropy and, when in a first state, a uniformly aligned smectic A structure; (B) an ionic dopant, which is present in the liquid crystal material Negative conductivity anisotropy is provided in such that when subjected to an electric field that causes the dopant to migrate through the composition, the dopant is capable of disrupting the smectic A structure of the first state, thereby causing the composition to switch to the at least one A second state, and (C) optically anisotropic pigment particles, which have positive dielectric anisotropy, are dispersed in the composition, and the maximum size of the pigment particles is in the range of 10 nm to 1 μm. The composition, when in a first, relatively steady state, is capable of undergoing smectic dynamic scattering due to electrohydrodynamic instability under the influence of a sufficiently low frequency alternating electric field, thereby disordering liquid crystal and pigment particles, and thereby preventing Pigment particles clumped together. The composition is suitable for use in displays, and is especially resistant to degradation due to ambient light, and can therefore be used in outdoor applications.

Description

technical field [0001] The present invention relates to liquid crystal compositions having a smectic A structure, cells containing such compositions sandwiched between a pair of electrodes, optical devices containing one or more cells, and methods for switching the composition by applying an electric field to the composition method of optical properties. Background technique [0002] Smectic liquid crystals (LC) are materials that, when cooled from an isotropic (liquid) phase and before solidification, can form a liquid crystal phase with a layered structure in which liquid crystal molecules display various morphologies within each layer. The various morphologies give rise to many different smectic phases designated by the letters A, B, C, etc., the most common smectic phase being smectic A (SmA). The SmA phase has LC molecules that are orthogonal to the layer but randomly distributed within the layer, thus, it is one of the least ordered smectic phases. X-ray studies have...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K19/02C09K19/58C09K19/52C09K19/40
CPCC09K19/02C09K19/408C09K19/52C09K19/582C09K19/40C09K19/58G02F1/1333
Inventor 大平·褚H·许W·A·克罗斯兰德A·B·达维
Owner CAMBRIDGE ENTERPRISE LTD
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