Computer graphics processing and selective visual display system – Display driving control circuitry
Reexamination Certificate
2000-07-21
2004-12-14
Shankar, Vijay (Department: 2673)
Computer graphics processing and selective visual display system
Display driving control circuitry
C345S050000, C345S055000, C348S458000, C348S751000
Reexamination Certificate
active
06831633
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an active-matrix electro-optical device, a method for driving the active-matrix electro-optical device, a scanning line driving circuit, and electronic equipment.
2. Description of Related Art
Active-matrix electro-optical devices typically include a plurality of scanning lines and a plurality of data lines, respectively extending horizontally and vertically, and a switching element, such as a thin-film diode (hereinafter referred to as “TFD”) or a thin-film transistor (hereinafter referred to as “TFT”) arranged at each of intersections of the scanning lines and the data lines.
The scanning lines are successively provided with a scanning signal by a scanning line driving circuit. The data lines are driven by a data line driving circuit. In synchronization with a successive supply of the scanning signal, the data line driving circuit feeds a sampling control signal to a sampling switch that samples, on a data-line-by-data-line basis, a video signal supplied to a video signal line.
In such an active-matrix electro-optical device, a vertical scanning operation on a field-by-field basis or on a frame-by-frame basis, i.e., a field scanning or a frame scanning, is performed in response to the scanning signal and the sampling control signal.
The video signal input to the electro-optical device may be a signal of any of the digital TV system and the like other than the NTSC system, the PAL system, SECAM system, and high-vision system. The number of video lines of the video signal is different from television system to television system. The electro-optical device compatible with a plurality of television systems thus includes a video line count converter. Using the video line count converter, the number of lines of the input video signal is converted to correspond with the number of scanning lines of the active matrix, and the converted video signal is used to drive the scanning line driving circuit and the data line driving circuit.
SUMMARY OF THE INVENTION
The video line count converter typically employs a field memory or a frame memory for converting the video line count, and generally increases the scale of the circuit of the entire electro-optical device. Particularly, a device, such as a video projector, in need of three processing circuits corresponding to the three RGB colors, disadvantageously requires the tripled circuit scale of the video line converter to perform process for the three colors.
The present invention has been developed at least in view of this problem, and it is an object of the present invention to at least provide an electro-optical device which converts the video line count without using a video line count converter, a method for driving the electro-optical device, a scanning line driving circuit, and electronic equipment.
One exemplary embodiment of the present invention lies in a method for driving an electro-optical device that includes a pixel including a switching element arranged at each of intersections of a plurality of scanning lines and a plurality of data lines, and a pixel electrode connected to the switching element, a scanning signal for driving each of the plurality of the scanning lines being preferably generated in accordance with the video line count per field of an input video signal and a scanning line count.
In accordance with this exemplary embodiment of the present invention, the scanning signals are generated in accordance with the video line count per field of the input video signal and the scanning line count. A decimation process is thus performed by deactivating the scanning signal for particular video lines of the video signal or a stretching process is performed by concurrently activating the scanning signal supplied to adjacent scanning lines for the particular video lines. With this arrangement, even if the video line count of the input video signal fails to coincide with the scanning line count, the input video signal is presented on the electro-optical device without the need for the converter for converting the video line count.
In the generation step of the scanning signal in the driving method, all scanning signals may be deactivated for the particular video lines predetermined in accordance with the detected video line count and the scanning line count. Since the scanning signals for the particular video lines are deactivated, the video signal of the particular video lines is not written on pixels. The particular video lines are thus decimated.
The driving of the data line is preferably suspended for the particular video line while the data lines are driven on the video lines other than the particular video lines. Since the video signal is not written on the particular video line, the data line does not need driving. The suspension of the driving of the data line for the particular video line creates no problem, and provides the advantage of reducing power consumption.
In the generation step of the scanning signal in the driving method, two scanning signals for driving adjacent scanning lines are preferably concurrently activated for the particular video lines predetermined in accordance with the detected video line count and scanning line count. Since the two scanning signals for driving the adjacent scanning lines for the particular video lines are concurrently activated, the switching elements connected to the adjacent scanning lines are concurrently turned on, and the video signal is written on the video lines corresponding to the two scanning lines. The arrangement achieves the stretching process.
Another exemplary embodiment of the present invention lies in a method for driving an electro-optical device that includes a pixel including a switching element arranged at each of intersections of a plurality of scanning lines and a plurality of data lines, and a pixel electrode connected to the switching element, the video line count per field of the input video signal being detected, the scanning signals for driving the scanning lines being successively generated when the detected video line count is equal to the scanning line count, and the scanning signals for the particular video lines predetermined in accordance with the detected video line count and the scanning line count being deactivated when the detected video line count exceeds the scanning line count, while two scanning signals for driving adjacent scanning lines being concurrently activated for the video lines other than the particular video lines.
In accordance with this exemplary embodiment of the present invention, the video signal for the particular video lines is decimated while the other lines are twice stretched. When the video signal, having the video line count equal to the scanning line count, is input, the video signal is presented without the need for the decimation process or the stretching process. When both line counts fail to coincide with each other, the decimation process or the stretching process is performed by controlling the scanning signal. For instance, when a video signal having 540 lines per field is input against a scanning line count of 720, the decimation process is carried out to decimate one line every three lines, while the stretching process for stretching the lines is performed.
Another exemplary embodiment of the present invention lies in a method for driving an electro-optical device that includes a pixel including a switching element arranged at each of intersections of a plurality of scanning lines and a plurality of data lines, and a pixel electrode connected to the switching element, the video line count per field of the input video signal being detected, the scanning signals for driving the scanning lines being successively generated when the detected video line count is equal to the scanning line count, and two scanning signals for driving adjacent scanning lines for the particular video lines predetermined in accordance with the detected video line count and the scanning line count being concurrently activated when the detected vid
Oliff & Berridg,e PLC
Seiko Epson Corporation
Shankar Vijay
Shapiro Leonid
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