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Browse Prior Art Database

Serpentine Cell

IP.com Disclosure Number: IPCOM000037255D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Takano, H: AUTHOR

Abstract

A standard twisted nematic liquid crystal cell (serpentine cell) is disclosed. It is used for the measurement of refractive indices n(e), n(o), and birefringence n(e)-n(o) of the liquid crystal material. The values of these indices are substantially important to design optical properties of the liquid crystal display/printer. Cell thickness (d) of a liquid crystal display/printer is one of the key parameters which affect display/print quality. It is obtained by dividing optical path length (n(e)*d, (n(o)*d) or retardation ((n(e)-n(o))*d) by refractive indices or birefringence. Generally, refractive indices and birefringence depend on pre-tilt angle, temperature, wavelength, and cell thickness. These indices are also obtained by dividing optical path length or retardation by cell thickness (d).

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Serpentine Cell

A standard twisted nematic liquid crystal cell (serpentine cell) is disclosed. It is used for the measurement of refractive indices n(e), n(o), and birefringence n(e)-n(o) of the liquid crystal material. The values of these indices are substantially important to design optical properties of the liquid crystal display/printer. Cell thickness (d) of a liquid crystal display/printer is one of the key parameters which affect display/print quality. It is obtained by dividing optical path length (n(e)*d, (n(o)*d) or retardation ((n(e)-n(o))*d) by refractive indices or birefringence. Generally, refractive indices and birefringence depend on pre-tilt angle, temperature, wavelength, and cell thickness. These indices are also obtained by dividing optical path length or retardation by cell thickness (d). The disclosed method solve this problem.

(Image Omitted)

One of the solutions of this problem is to prepare a standard cell whose conditions are the same as those of target liquid crystal cells and whose thickness is already known. Fig. 1 shows one example of seal design of such standard cells and target cells. Two serpentine-shaped standard cells and four target cells are fabricated from a pair of upper and lower glasses simultaneously; therefore, cell condition equivalence of standard and target cells is automatically guaranteed. The details of the standard cell are shown in Fig. 2. The seal density of the standard cell is so high that glass deformation be...