Liquid crystal cells – elements and systems – Liquid crystal optical element – Beam dividing switch formed from liquid crystal cell
Reexamination Certificate
1997-04-25
2001-02-06
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Liquid crystal optical element
Beam dividing switch formed from liquid crystal cell
C349S117000, C349S075000
Reexamination Certificate
active
06184969
ABSTRACT:
CROSS REFERENCE TO RELATED PATENTS AND PATENT APPLICATIONS
Reference is made to commonly owned co-pending U.S. patent application Ser. No. 08/187,162, U.S. Pat. No. 5,541,745, Ser. No. 08/187,050, U.S. Pat. No. 5,532,854 and Ser. No. 08/187,163 which has abandoned, filed Jan. 25, 1994; Ser. No. 08/275,907, U.S. Pat. No. 5,519,524, filed Jul. 5, 1994; Ser. No. 08/328,375, U.S. Pat. No. 5,537,256, filed Oct. 25, 1994; Ser. No. 08/392,055, U.S. Pat. No. 5,537,324, filed Feb. 22, 1995; Ser. No. 08/398,292, U.S. Pat. No. 5,715,029 filed Mar. 3, 1995; Ser. No. 08/295,383, U.S. Pat. No. 5,621,572 filed Aug. 24, 1994; Ser. No. 08/328,371, U.S. Pat. No. 5,808,589 filed Oct. 25, 1994; Ser. No. 08/383,466, U.S. Pat. No. 5,606,458 filed Feb. 3, 1995; and provisional patent applications Ser. No. 60/002,780 entitled Optical system and method for a head mounted display providing both front and peripheral fields of view and Ser. No. 60/002,779 entitled Monocular viewing device with retroreflector display system, telecommunication system, and method, both filed Jul. 19, 1995. The entire disclosures thereof hereby are incorporated by reference.
TECHNICAL FIELD
The present invention relates generally, as is indicated, to optical display system and method, active and passive dithering using birefringence, color image superpositioning, and display enhancement with phase coordinated polarization switching. The present invention also relates to dithering systems for optical displays and methods, and, more particularly, to passive dithering systems and methods for changing the location of an optical signal and for improving an optical display. The present invention also relates to the enhancing of optical displays and methods to enhance such displays, and, more particularly, to enhancing optical displays and methods by coordinating the phase of switching light with the dynamic operation of the displayed image developing device.
BACKGROUND
Dithering systems have been used in a number of technologies in the past. The objective of a dithering system is to change a characteristic of a particular signal in a periodic (or random) fashion in order to provide a useful output. As is described in further detail, the dithering system of the invention may be used to change the relative location of an optical signal.
The present invention may be used with various types of displays and systems. Exemplary displays are a CRT (sometimes referred to herein as cathode ray tube) display, a liquid crystal display (sometimes referred to herein as “LCD”), especially those which modulate light transmitted therethrough, reflective liquid crystal displays, light emitting displays, such as electroluminescent displays, plasma displays and so on.
Conventional optical displays typically display graphic visual information, such as computer generated graphics, and pictures generated from video signals, such as from a VCR, from a broadcast television signal, etc.; the pictures may be static or still or they may be moving pictures, as in a movie or in a cartoon, for example. Conventional displays also may present visual information of the alphanumeric type, such as numbers, letters, words, and/or other symbols (whether in the English language or in another language). Visual information viewed by a person (or by a machine or detector) usually is in the form of visible light. Such visible light is referred to as a light signal or an optical signal. The term optical signal with which the invention may be used includes visible light, infrared light, and ultraviolet light, the latter two sometimes being referred to as electromagnetic radiation rather than light. The optical signal may be in the form of a single light ray, a light beam made up of a plurality of light rays, a light signal such as a logic one or a logic zero signal used in an optical computer, for example, or the above-mentioned alphanumeric or graphics type display. Thus, as the invention is described herein, it is useful with optical signals of various types used for various purposes. Therefore, in the present invention reference to optical signal, light ray, light beam, light signal, visual information, etc., may be used generally equivalently and interchangeably.
In an exemplary liquid crystal display sometimes referred to as an image source, there usually are a plurality of picture elements, sometimes referred to as pixels or pels, and these pixels can be selectively operated to produce a visual output in the form of a picture, alphanumeric information, etc. Various techniques are used to provide signals to the pixels. One technique is to use a common electrode on one plate of a liquid crystal cell which forms the display and an active matrix electrode array, such as that formed by thin film transistors (TFT), on the other plate of the liquid crystal cell. Various techniques are used to provide electrical signals to the TFT array to cause a particular type of optical output from respective pixels. Another technique to provide signals to the pixels is to use two arrays of crossed electrodes on respective substrates of an LCD; by applying or not applying a voltage or electric field between a pair of crossed electrodes, a particular optical output can be obtained.
One factor in determining resolution of a liquid crystal display is the number of pixels per unit area of the liquid crystal display. For example, Sony Corporation recently announced a 1.35 inch diagonal high resolution liquid crystal display which has 513,000 pixels arranged in 480 rows of 1,068 pixels per row.
Another factor affecting resolution is the space between adjacent pixels sometimes referred to “as optical dead space”. Such space ordinarily is not useful to produce an optical signal output. The space usually is provided to afford a separation between the adjacent pixels to avoid electrical communication between them. The space also is provided to accommodate circuitry, leads, and various electrical components, such as capacitors, resistors, and even transistors or parts of transistors. The proportion of optical dead space to useful space of pixels that can produce optical output tends to increase as the physical size of the image source is decreased, for the space required to convey electrical signals, for example, may remain approximately constant although the actual size of the useful space of the pixels to produce optical output can be reduced because of anticipated image magnification. However, upon magnification of the image produced by such a miniature image source both the optical dead space and the useful optical space of the pixels are magnified. Thus, resolution tends to be decreased, especially upon such magnification.
The picture elements (pixels or pels) may be discrete pixels, blocks or areas where an optical signal can be developed by emission, reflection, transmission, etc. such as the numerous pixels in the miniature image source of Sony Corporation mentioned above. The optical signal referred to may mean that light is “on” or provided as an output from the device, or that the pixel has its other condition of not producing or providing a light output, e.g., “off”; and the optical signal also may be various brightnesses of light or shades of gray. Alternatively, the optical output or optical signal produced by a pixel may be a color or light of a particular color.
The pixels may be a plurality of blocks or dots arranged in a number of lines or may be a number of blocks or dots randomly located or grouped in a pattern on the display or image source (source of the optical signal). The pixels may be a number of lines or locations along the raster lines that are scanned in a CRT type device or the pixels may be one or a group of phosphor dots or the like at particular locations, such as along a line in a CRT or other device. The optical signal produced by one or more pixels may be the delivery of light from that pixel or the non-delivery of light from that pixel, or various brightnesses or shades of gray. To obtain operation of a pixel, for example, the pixel may be energized or not. In so
Renner , Otto, Boisselle & Sklar, LLP
Sikes William L.
Ton Toan
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