Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-09-03
2001-05-22
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S187000
Reexamination Certificate
active
06236442
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Reference is made to commonly-assigned U.S. patent application Ser. No. 08/961,059 filed Oct. 30, 1997, entitled “Display Apparatus Using Light Patternable Conductive Traces” by Stanley W. Stephenson; U.S. patent application Ser. No. 08/961,056 filed Oct. 30, 1997, entitled “Single Sheet Display Having Patternable Conductive Traces” by Stanley W. Stephenson; U.S. patent application Ser. No. 08/990,891 filed Dec. 15, 1997, entitled “Method of Producing a Display Having Patternable conductive Traces” by Stanley W. Stephenson; U.S. patent application Ser. No. 08/990,853 filed Dec. 15, 1997, entitled “A Sheet Having Patternable Conductive Traces for Use in a Display” by Stanley W. Stephenson; U.S. patent application Ser. No. 09/027,321 filed Feb. 20, 1998, entitled “Selectively Presenting Viewable and Conductive Images” by Stanley W. Stephenson and U.S. patent application Ser. No. 09/045,016 filed Mar. 20, 1998, entitled “Selectively Presenting Viewable and Conductive Images” by Stanley W. Stephenson, the disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION
The field of invention pertains to image displays which can selectively transmit or reflect light.
BACKGROUND OF THE INVENTION
Currently, information is displayed using assembled sheets of paper carrying permanent inks or displayed on electronically modulated surfaces such as cathode ray displays or liquid crystal displays. Other sheet materials can carry magnetically writable areas to carry ticketing or financial information, however magnetically written data is not visible.
A structure is disclosed in PCT/WO 97/04398, entitled “Electronic Book With Multiple Display Pages” which is a thorough recitation of the art of thin, electronically written display technologies. Disclosed is the assembling of multiple display sheets that are bound into a “book”, each sheet provided with means to individually address each page. The patent recites prior art in forming thin, electronically written pages, including flexible sheets, image modulating material formed from a bistable liquid crystal system, and thin metallic conductor lines on each page. Various ways are disclosed to produce the conductor lines including photolithography, but not selective exposure and photographic development of traces from a photosensitive emulsion. One disadvantage of this structure is that individual pages are bound together and that many multi-layer conductors must pass across the pages and to an interconnection at the spine of the book.
Fabrication of flexible, electronically written display sheets are disclosed in U.S. Pat. No. 4,435,047. A first sheet has transparent ITO conductive areas and a second sheet has electrically conductive inks printed on display areas. The sheets can be glass, but in practice have been formed of Mylar polyester. A dispersion of liquid crystal material in a binder is coated on the first sheet, and the second sheet is pressed onto the liquid crystal material. Electrical potential applied to opposing conductive areas operate on the liquid crystal material to expose display areas. The display ceases to present an image when de-energized. Currently, Taliq products form electrical interconnection by offsetting the two sheets and contacting trace conductors from each of the two sheets.
The prior art typically requires multiple, separate layers to build up the display. The electrical traces and transparent conductive layers are typically formed through repeated vacuum deposition and photolithography of materials on the substrate. These processes are expensive and require long processing times on capital intensive equipment. Because most display structures are formed of glass, two sheets are used and are offset to permit connection to two separate and exposed sets of traces that are disposed on separate sheets.
The prior art discloses isolating each layer on separate sides of the display, and connecting the traces to drive electronics using solder connections, wire bonds or pressure contact. Such connections do require that both sets of traces be exposed on a surface for the connection process. The uniform, multi-layer structure prevents connection to the inner conductive layer.
In the case of electronic display means, power must be provided to view images. Printed sheets receive ink and cannot be rewritten. In the case of magnetically written media such as magnetic areas on the back of credit cards, the information is not readable.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a display apparatus which can be rewritten while overcoming the above noted problems.
Another object of the present invention is to provide a display device that can be formed using coating techniques.
This object is achieved in a display for presenting selected images to a viewer, comprising:
(a) a transparent substrate;
(b) a transparent, electrically conductive coating formed over the transparent substrate;
(c) a light modulating layer formed over the transparent, electrically conductive layer; and
(d) a patterned conductive layer formed over the light modulating layer which provides viewable and conductive images, the light modulating layer being effective in two conditions, in a first condition to prevent the viewing of the viewable and conductive images and in a second condition to permit the viewing of the viewable and conductive images.
The disclosed structure has the advantage of providing a reflective display using a laser patternable conductive evaporated coating over a liquid crystal, light modulating layer. A laser patternable evaporated coating is inexpensive when deposited over a liquid crystal-polymer coating created using current photographic coating technology. The display can be patterned using laser to create a display. A single large substrate of material can be coated and formed into different types of displays by exposing the light sensitive material to different patterns. Another advantage is that the display can be formed as sheets using coating methods instead of bonding methods.
REFERENCES:
patent: 4435047 (1984-03-01), Fergason
patent: 5187601 (1993-02-01), Yamazaki et al.
patent: 5695682 (1997-12-01), Doane et al.
patent: WO 97/04398 (1996-07-01), None
Hashimoto et al, Reflective Color Display Using Cholesteric Liquid Crystals, SID 98 Digest, pp. 897-900.
Colice Christopher M.
DeBoer Charles D.
Stephenson Stanley W.
Eastman Kodak Company
Owens Raymond L.
Parker Kenneth
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