Loading patent…
AssigneeHoechst Aktiengesellschaft
InventorsDietmar Jungbauer, Heinz-Joachim Rieger, Claus Escher, Gerhard Illian, Kazuya Nagao, Mikio Murakami, Tsuyoshi Uemura, Hiroyuki Ohnishi, Shozo Fujiwara
Estimating the term…
A process for the stabilization of the spatial alignment of the smectic layers in an FLC switching and/or display element, in which the original position of the smectic layers has been modified by electrical field treatment, which comprises alternately switching the elements during non-operation and/or when a certain temperature is exceeded which is above a predetermined temperature range which includes the operating temperature region and/or when the temperature falls below a certain temperature which is below a predetermined temperature range which includes the operating temperature region. Use of the process according to the invention ensures long-term functioning of the switching and display device, even in the case of repeated regeneration of the quasi-bookshelf geometry, and prevents worsening in the contrast and brightness and the occurrence of ghost images.
A process for the stabilization of the spatial alignment of the smectic layers in the display plane in an FLC switching and/or display element (display), in which an original chevron geometry of the smectic layers has been converted into a quasi-bookshelf geometry by electrical field treatment, which comprises:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
Based on orientation effects in which the liquid crystal remains transparent: using ferroelectric liquid crystals
By control of light from an independent source: using liquid crystals
Constructional arrangements; Manufacturing methods: heating or cooling of liquid crystal cells other than for activation, e.g. circuits or…
Maintaining the quality of display appearance: temperature compensation
Term ended 12 Jan 2016 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
Switching and display devices containing ferroelectric liquid-crystal mixtures are disclosed, for example, in EP-B 0 032 362 (=U.S. Pat. No. 4,367,924). Liquid-crystal light valves are devices which modify their optical transmission properties, for example due to electrical switching, in such a way that light which is incident (and possibly reflected again) is intensity- or phase-modulated. A number of such light valves can be combined to form liquid-crystal displays (LCDs). Examples are the known watch and calculator displays or liquid-crystal displays in the OA (office automation) and TV sectors. However, these also include light shutters, as employed in photocopiers, printers, etc. So-called "spatial light modulators" are also within the area of application of liquid-crystal light valves (see Liquid Crystal Device Handbook, Nikkan Kogyo Shimbun, Tokyo, 1989; ISBN 4-526-02590-9C 3054 and the papers cited therein).
Electro-optical switching and display devices are constructed in such a way that the FLC layer is included on both sides by layers which are usually, in this sequence starting from the FLC layer, at least one alignment layer, electrodes and a limiting plate (for example made of glass). In addition, they contain a polarizer if they are operated in "guest-host" mode or in reflective mode, or two polarizers if the transmissive birefringence mode is used. The switching and display elements may, if desired, contain further auxiliary layers, such as, for example, diffusion barrier or insulation layers.
Together with a distance between the limiting plates which is chosen to be sufficiently small, such alignment layers bring the FLC molecules of the FLC mixture into a configuration in which the molecules lie with their long axes parallel to one another and the smectic planes arranged perpendicular or inclined to the alignment layer. In this arrangement, the molecules are known to have two equivalent alignments, between which they can be switched by applying an electrical field in a pulsed manner, ie. FLC displays are capable of bistable switching. The response times are inversely proportional to the spontaneous polarization of the FLC mixture and are in the range of microseconds.
The invention is explained in more detail by means of the examples:
The following FLC mixture is used for the examples: (The numerical data represent mol %) ##STR1##
mixture has the phase sequence: S.sub.c * 62.5 S.sub.A 69 N* 83 I.