Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1996-11-27
2002-04-30
Jankus, Almis R. (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S096000, C345S098000, C345S100000
Reexamination Certificate
active
06380919
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention pertains generally to display devices and, more particularly, relates to driving circuits thereof. The invention can be applied to driving methods for either simple matrix or active matrix displays. The invention is also applicable to display devices including such flat-panel displays as liquid crystal displays (LCDs) and electroluminescent displays, in which light transmittance, reflectance, refractive index, luminous intensity or other properties are varied by applying electrical signals in a controlled manner, and not including cathode ray tubes (CRTs).
2. Description of the Related Art
Matrix display devices incorporating a plurality of display elements arranged in matrix form are employed particularly in flat-panel displays as large capacity display means. Conventionally known matrix display devices include simple matrix type in which individual display elements arrayed in rows and columns have no built-in actuating devices and active matrix type in which each individual display element is associated with an active device such as a transistor or a diode. In the following description, a column signal line refers to each signal line for transmitting an electrical signal which contains a video signal, and a row signal line refers to each signal line for transmitting an electrical signal which does not contain any video signal.
In either type of matrix display device, basic construction is such that peripheral driving circuits containing addressing circuits are arranged in the periphery of the matrix structure for providing signals to the row and column signal lines. These driving circuits are called the row driving circuit and column driving circuit. For example, Japanese Unexamined Patent Application No. 57-41078 discloses an arrangement employing a shift register as an addressing circuit for active matrix display devices, whereas Japanese Unexamined Patent Application No. 62-265696 discloses an arrangement employing a decoder including AND gates and NAND gates as an addressing circuit for active matrix display devices.
The peripheral driving circuit of the conventional, matrix display device used to be formed on an integrated semiconductor circuit of the prior art, and connected to the matrix structure formed on a glass substrate using such bonding technique as a tape automated bonding (TAB) operation. Spacings between individual row and column signal lines have decreased in recent years as a result of increasing demand for greater display capacity of matrix displays and more compact matrix structure. This necessitates that the peripheral driving circuit be formed on the same substrate as the matrix structure in monolithic form. It is difficult to connect the individual lines with line spaces of 100 &mgr;m or less by TAB technology since the TAB operation is based on application of mechanical pressure. In the aforementioned construction in which the peripheral driving circuit is formed on the same substrate as the matrix of display elements, it is possible to utilize photolithography. In an ideal case, photolithography enables reduction of line spacing to a level practically equal to the level of design rule requirements.
It has recently been recognized, however, that a reduction in the area of individual display elements could give rise to problems related to circuit configuration. More specifically, even when the peripheral driving circuit is formed on the same substrate as the matrix of display elements in monolithic form, a circuit for supplying electrical signals to individual signal lines should have such line widths that equal to or smaller than the spaces between the individual signal lines. As an example, each stage of a shift register contained in the peripheral driving circuit includes approximately 10 transistors, and it is essential that the circuit be designed in such a way that these transistors fall within widths of the individual signal lines. In a case where the circuit is designed based on a 5 &mgr;m design rule, for instance, permissible minimum width of each signal line is 30 &mgr;m and, therefore, dimensions of each display element become at least 30 &mgr;m by 30 &mgr;m.
According to prior art driving techniques for a matrix display device, its row signal lines are sequentially driven from top to bottom (or from bottom to top). This means that the conventional matrix display devices can not be operated by a commonly used interlaced scanning process, in which groups of odd-numbered horizontal lines and even-numbered horizontal lines are scanned in alternate vertical scans. This limitation of the matrix display devices is disadvantageous when displaying quickly moving images. Furthermore, it is essential to convert video signals from interlaced scanning to noninterlaced scanning in order to display an ordinary video input.
LCD display devices usually employ line inversion or dot inversion display techniques to prevent picture degradation due to mutual interference between accumulated charges (i.e., image information) in adjacent display elements. This requires an additional process of converting image information.
Higher-speed scanning is required as the display capacity of matrix display devices increases. As an example, the video graphics array (VGA) standard (640 by 480 pixels) requires a 9 MHz clock whereas the engineering workstation (EWS) standard requires a clock frequency of more than 30 MHz. Since the peripheral driving circuits of the matrix display devices formed in monolithic form are produced by the use of such a semiconductor material as polycrystalline silicon, which is inferior to single-crystal, an increase in operating speed is not preferable.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a solution to at least one of the aforementioned problems of the prior art.
In one form of the invention, a display device comprises a plurality of display elements arranged on a substrate to form a matrix structure, and at least first and second row driving circuits for supplying signals to individual rows of the matrix structure, the row driving circuits being located separately from and parallel to each other on the same substrate as the matrix structure, wherein a signal for any row signal line adjacent to a given row signal line to which a signal is supplied from the first row driving circuit is supplied from other than the first row driving circuit.
The above defined display device may be constructed in such a way that one of the row driving circuits is located to the left of the matrix structure while another is located to the right of the matrix structure, or all the row driving circuits are located to the left or right of the matrix structure.
In another form of the invention, a display device comprises a plurality of display elements arranged on a substrate to form a matrix structure, and at least first and second column driving circuits for supplying signals to individual columns of the matrix structure, the column driving circuits being located separately from and parallel to each other on the same substrate as the matrix structure, wherein a signal for any column signal line adjacent to a given column signal line to which a signal is supplied from the first column driving circuit is supplied from other than the first column driving circuit.
Construction of this display device may be such that one of the column driving circuits is located above the upper edge of the matrix structure while another is located below the lower edge of the matrix structure, or all the column driving circuits is located above the upper edge or below the lower edge of the matrix structure.
In either form of the invention, the display device may be constructed in such a way that all the row driving and column driving circuits employ shift registers for use as addressing circuits, or all the row driving and column driving circuits employ decoders for use as addressing circuits. Alternatively, the construction of the display device may be such that each row
Koyama Jun
Yamazaki Shunpei
Awad Amr
Fish & Richardson P.C.
Jankus Almis R.
Semiconductor Energy Laboratory Co,. Ltd.
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