Wafer based active matrix

Details Wafer based active matrix Wafer based active matrix

1994-10-18

2001-07-24

Chow, Dennis-Doon (Department: 2675)

Computer graphics processing and selective visual display system

Plural physical display element control system

Display elements arranged in matrix

C345S093000, C345S206000, C349S042000, C349S140000

Reexamination Certificate

active

06266037

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates generally to light encoding systems and more particularly to a wafer based active matrix reflective light encoding system.
During the last two decades, there have been numerous efforts to develop and commercialize light encoding systems such as flat panel displays to effectively compete with the conventional cathode ray tube (CRT) or to develop products which are not possible utilizing CRT's. Of these efforts, plasma display panels (PDP), electroluminescent displays (EL) and several types of liquid crystal displays (LCD) have clearly been the most successful and have exhibited the most dynamic growth and future potential. One specific type of display, active matrix liquid crystal displays (AMLCD), has demonstrated sufficient performance to address some major market segments.
The cost of AMLCD's is largely determined by the yield of useable devices, where the yield is the percentage of useable devices from the total produced. Yield of AMLCD's is in large part determined by the device design, manufacturing process tolerance and the display size. In general, the larger the display size, the lower the yield and hence higher the cost of the device.
The focus of efforts in recent years has been in developing direct view display sizes large enough to replace existing TV and computer monitors. Pocket TV's have been introduced having one to three inch wide display screens, with the expressed goal of producing larger displays as volume and yield increase. An intense effort is being made to produce a fourteen inch diagonal or larger display. The ultimate goal of some efforts is to produce wall size direct view displays for the TV market. This goal is very likely to be frustrated by the inherent obstacles in producing a CRT or any other type of direct view display of that size.
The AMLCD effort has concentrated on utilizing a matrix of nonlinear devices on a glass or fused silica substrate. The nonlinear devices allow individual control over each display picture element or “pixel” to provide superior optimal performance. The nonlinear devices generally are amorphous or polycrystalline silicon thin film transistors (TFT); however, thin film diodes (TFD) and metal-insulator-metal (MIM) devices also have been employed.
A transparent substrate is considered necessary for these displays, because most liquid crystal (LC) materials require a polarizer at both the front and the back of the LCD device. Further, the conventional position on color displays is that they must be transmissive rather than reflective, because of the light losses inherent in the color reflective mode.
In developing larger size displays, substrate cost becomes important. Amorphous silicon TFT AMLCD's utilize inexpensive drawn glass. Polycrystalline silicon on the other hand, requires either very high temperature glass or fused silica substrates. Either of these substrates is prohibitively expensive in widths over eight inches. The inexpensive amorphous silicon AMLCD substrates are offset by the fact that these displays require separate address devices which result in several hundred interconnections to the display substrate. Polycrystalline silicon AMLCD's allow integration of the addressing circuitry on the substrate which reduces the number of interconnections to a very few.
The first direct view AMLCD utilizing a single crystal silicon wafer was produced in the early 1970's. Work on this development continued into the early 1980's, utilizing standard crystal silicon wafers and wafer fabrication techniques. This work appears to virtually have been abandoned since the display sizes are limited to less than the available wafer size and because the wafers are not transparent. These devices utilized dynamic scattering guest-host or dyed phase change rather than conventional twisted nematic LC material, which required expensive and elaborate photolithography to produce the required diffuse reflective aluminum back surface. These devices do provide fast, high performance and stable displays with integrated address and drive circuitry.
New markets have been recognized which include home theatre high definition TV, audio visual machines and high resolution large area computer aided design (CAD) stations. Each of these markets require very large, high resolution, full color and video speed imaging. In reviewing these markets Applicant has determined that the large area dictates projection systems, either front or rear projection, that the high resolution requires integrated drivers and that projection systems do not require either transparent substrates or large display sizes. Further, these markets all essentially utilize what can be considered light encoding devices. Other types of light encoding devices include wafer or printed circuit board mask sets.
It, therefore, would be desirable to provide a wafer based active matrix reflective light encoding system having high resolution, integrated drivers and manufactured with conventional wafer fabrication techniques.
SUMMARY OF INVENTION
The disadvantages of the prior art light encoding systems and techniques are overcome in accordance with the present invention by providing a wafer based active matrix reflective light encoding system utilizing a conventional wafer.
A source of light is directed to the wafer based active matrix which imparts or encodes information onto a light beam reflected therefrom. The wafer based active matrix includes a specular reflective back surface and an LC or similar characteristic material formed thereon which is electronically altered to impart or encode the information to the light beam reflected therefrom. The LC material preferably is a solid light modulating material having bodies of LC material suspended in the solid material.
The matrix transistors can be any conventional type of crystalline based structure, such as NMOS, CMOS or PMOS. The pixel capacitor can be a junction or oxide type capacitor or a combination thereof. The matrix bit and/or word lines can include strapping to prevent open lines. The transistors can be coupled to the bit and/or word lines by fuses to prevent shorts associated with a single pixel from shorting a whole line.
The wafer based active matrix can be mated to a light directing and projecting structure to form a reflective image plane module. The reflective image plane module light projecting structure projects the reflected beam for viewing or imaging, such as through one or more lens. The reflective image plane module light directing and projecting structure is formed from a prism or mirror which passes the light or light component through a first surface to the wafer based active matrix mated to a second surface and which projects the reflected light from the first surface to be viewed or imaged.


REFERENCES:
patent: 3525566 (1970-08-01), Altman
patent: 3807831 (1974-04-01), Soref
patent: 3824003 (1974-07-01), Koda et al.
patent: 4239346 (1980-12-01), Lloyd
patent: 4368963 (1983-01-01), Stolov
patent: 4470060 (1984-09-01), Yamazaki
patent: 4519678 (1985-05-01), Komatsubara et al.
patent: 4547042 (1985-10-01), Ngo
patent: 4574282 (1986-03-01), Crossland et al.
patent: 4582395 (1986-04-01), Morozumi
patent: 4688900 (1987-08-01), Doane et al.
patent: 4716403 (1987-12-01), Morozumi
patent: 4745454 (1988-05-01), Erb
patent: 4749259 (1988-06-01), Ledubuhr
patent: 4804953 (1989-02-01), Castleberry
patent: 4818074 (1989-04-01), Yokoi et al.
patent: 4826311 (1989-05-01), Ledebuhr
patent: 4838654 (1989-06-01), Hamaguchi et al.
patent: 4839707 (1989-06-01), Shields
patent: 4908692 (1990-03-01), Kikuchi et al.
patent: 4936656 (1990-06-01), Yamashita et al.
patent: 4944576 (1990-07-01), Lacker et al.
patent: 4995703 (1991-02-01), Noguchi
patent: 5022750 (1991-06-01), Flasck
patent: 5024524 (1991-06-01), Flasck
patent: 5028121 (1991-07-01), Bauer et al.
patent: WO88/10545 (1988-12-01), None
patent: 0034409 (1981-01-01), None
patent: 0198168 (1986-02-01), None
patent: 0294899 (1988-06-01), None
patent: 0 364 043 (1990-04-01), None
Proceedin

Affiliated with

Also associated with

Rating

Wafer based active matrix does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Wafer based active matrix, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wafer based active matrix will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2438041