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Light sensitive displayLight sensitive display description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050285985, Light sensitive display. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application claims the benefit of U.S. Patent Application Ser. No. 60/359,263, filed Feb. 20, 2002. BACKGROUND OF THE INVENTION [0002] The present invention relates to touch sensitive displays. [0003] Touch sensitive screens ("touch screens") are devices that typically mount over a display such as a cathode ray tube. With a touch screen, a user can select from options displayed on the display's viewing surface by touching the surface adjacent to the desired option, or, in some designs, touching the option directly. Common techniques employed in these devices for detecting the location of a touch include mechanical buttons, crossed beams of infrared light, acoustic surface waves, capacitance sensing, and resistive membranes. [0004] For example, Kasday, U.S. Pat. No. 4,484,179 discloses an optically-based touch screen comprising a flexible clear membrane supported above a glass screen whose edges are fitted with photodiodes. When the membrane is flexed into contact with the screen by a touch, light which previously would have passed through the membrane and glass screen is trapped between the screen surfaces by total internal reflection. This trapped light travels to the edge of the glass screen where it is detected by the photodiodes which produce a corresponding output signal. The touch position is determined by coordinating the position of the CRT raster beam with the timing of the output signals from the several photodiodes. The optically-based touch screen increases the expense of the display, and increases the complexity of the display. [0005] Denlinger, U.S. Pat. No. 4,782,328 on the other hand, relies on reflection of ambient light from the actual touch source, such as a finger or pointer, into a pair of photosensors mounted at comers of the touch screen. By measuring the intensity of the reflected light received by each photosensor, a computer calculates the location of the touch source with reference to the screen. The inclusion of the photosensors and associated computer increases the expense of the display, and increases the complexity of the display. [0006] May, U.S. Pat. No. 5,105,186, discloses a liquid crystal touch screen that includes an upper glass sheet and a lower glass sheet separated by spacers. Sandwiched between the glass sheets is a thin layer of liquid crystal material. The inner surface of each piece of glass is coated with a transparent, conductive layer of metal oxide. Affixed to the outer surface of the upper glass sheet is an upper polarizer which comprises the display's viewing surface. Affixed to the outer surface of glass sheet is a lower polarizer. Forming the back surface of the liquid crystal display is a transflector adjacent to the lower polarizer. A transflector transmits some of the light striking its surface and reflects some light. Adjacent to transflector is a light detecting array of light dependent resistors whose resistance varies with the intensity of light detected. The resistance increases as the light intensity decreases, such as occurs when a shadow is cast on the viewing surface. The light detecting array detect a change in the light transmitted through the transflector caused by a touching of viewing surface. Similar to touch sensitive structures affixed to the front of the liquid crystal stack, the light sensitive material affixed to the rear of the liquid crystal stack similarly pose potential problems limiting contrast of the display, increasing the expense of the display, and increasing the complexity of the display. [0007] Touch screens that have a transparent surface which mounts between the user and the display's viewing surface have several drawbacks. For example, the transparent surface, and other layers between the liquid crystal material and the transparent surface may result in multiple reflections which decreases the display's contrast and produces glare. Moreover, adding an additional touch panel to the display increases the manufacturing expense of the display and increases the complexity of the display. Also, the incorporation of the touch screen reduces the overall manufacturing yield of the display. [0008] Accordingly, what is desired is a touch screen that does not significantly decrease the contrast ratio, does not significantly increase the glare, does not significantly increase the expense of the display, and does not significantly increase the complexity of the display. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a cross sectional view of a traditional active matrix liquid crystal display. [0010] FIG. 2 is a schematic of the thin film transistor array. [0011] FIG. 3 is a layout of the thin film transistor array of FIG. 2. [0012] FIGS. 4A-4H is a set of steps suitable for constructing pixel electrodes and amorphous silicon thin-film transistors. [0013] FIG. 5 illustrates pixel electrodes, color filters, and a black matrix. [0014] FIG. 6 illustrates a schematic of the active matrix elements, pixel electrode, photo TFT, readout TFT, and a black matrix. [0015] FIG. 7 illustrates a pixel electrode, photo TFT, readout TFT, and a black matrix. [0016] FIG. 8 is a layout of the thin film transistor array of FIGS. 6 and 7. [0017] FIG. 9 is a graph of the capacitive charge on the light sensitive elements as a result of touching the display at high ambient lighting conditions. [0018] FIG. 10 is a graph of the capacitive charge on the light sensitive elements as a result of touching the display at low ambient lighting conditions. [0019] FIG. 11 is a graph of the photo-currents in an amorphous silicon TFT array. [0020] FIG. 12 is a graph of the capacitive charge on the light sensitive elements as a result of touching the display and providing light from a light wand. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0021] Referring to FIG. 1, a liquid crystal display (LCD) 50 (indicated by a bracket) comprises generally, a backlight 52 and a light valve 54 (indicated by a bracket). Since liquid crystals do not emit light, most LCD panels are backlit with flourescent tubes or arrays of light-emitting diodes (LEDs) that are built into the sides or back of the panel. To disperse the light and obtain a more uniform intensity over the surface of the display, light from the backlight 52 typically passes through a diffuser 56 before impinging on the light valve 54. Continue reading about Light sensitive display... Full patent description for Light sensitive display Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Light sensitive display patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Light sensitive display or other areas of interest. ### Previous Patent Application: Thin film transistor electrostatic discharge protective circuit Next Patent Application: Liquid crystal display device Industry Class: Liquid crystal cells, elements and systems ### FreshPatents.com Support Thank you for viewing the Light sensitive display patent info. IP-related news and info Results in 0.27357 seconds Other interesting Feshpatents.com categories: Tyco , Unilever , Warner-lambert , 3m 174 |
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