Patent Application
20140085173
The present invention relates to a driving circuit structure of a liquid crystal panel, and more particularly to a driving circuit structure of a liquid crystal panel which has gradually increasing trace widths of trace portions of gate driving COFs (chip on film) along a gate scanning direction.
A liquid crystal display (LCD) is a type of flat panel display (FPD) which displays images by the property of the liquid crystal material. In comparison with other display devices, the LCD has the advantages in lightweight, compactness, low driving voltage and low power consumption, and thus has already become the mainstream product in the whole consumer market. In a traditional process of LCD panel, it comprises a front-end array process, a mid-end cell process and a back-end modulation process. The front-end array process is used to produce thin-film transistor (TFT) substrates (also called array substrates) and color filter (CF) substrates; the mid-end cell process is used to combine the TFT substrate with the CF substrate, then fill liquid crystal into a space therebetween, and cut to form panels with a suitable product size; and the back-end modulation process is used to execute an installation process of the combined panel, a backlight module, a panel driving circuit, an outer frame, etc.
As mentioned above, LCD driver chips are the important components of the LCD, and the main function thereof is to output the needed voltage to pixels, so as to control the twist degree of liquid crystal molecules. There are two types of LCD driver chips: one is the Source driver chip arranged on X-axis, the other is the Gate driver chip arranged on Y-axis. In other words, the Source driver chips control signals of image, and the Gate driver chips control signals of gate switch, so they have different functions for the LCD panel. Simply speaking, images of LCD are formed by scanning lines one by one. The Gate driver chip controls the vertical signals. If the scanning is started from the topmost line, the first pin of the Gate driver chip is set to be switched on, and others are set to be switched off. The signals in the Source driver chip are the real signal (horizontal), and the sent signal is only accepted by horizontal pixels of the first line. After the signal of the first line is transmitted, the second line will be the next one, while the content of the Source driver chip is changed to the second line, and the second pin of the Gate driver chip is switched on, and others is switched off, so that the data is transmitted to the second line.
Furthermore, an assembly of the driver chips of the back-end modulation process is an assembling technology to combine the packaged Source driver chips and the packaged Gate driver chip with the LCD panel. There are various packaging types of the driver chip for LCD, such as quad flat package (QFP), chip on glass (COG), tape automated bonding (TAB), chip on film (COF), etc, wherein the COF structure has flexibility and smaller circuit pitches, so as to become the mainstream technology of the package of driver chips.
Referring now to
As shown in
Furthermore, as shown in
However, in actual operation, the liquid crystal panel 90 will generate one problem: the liquid crystal panel 90 will appear a boundary line between each of the gate driving COFs 81 (this phenomenon is called “H-block issue” or “Block Dim”). The main reason of this phenomenon is that: the gate driving COFs 81 are connected by wire on Array (WOA), so it causes the gate output signals of the different gate driving COFs 81 are not identical. Because a RC delay effect (by resistance and the capacitance) is produced in transmission of metal wire connection, along the gate scanning direction S, the gate output signal of a second gate driving COF 81 will be decreased than a first gate driving COF 81; and the gate output signal of a third gate driving COF 83 will be decreased than the second gate driving COF 82. Hence, when all of the liquid crystal panel 90 show an even picture, the brightness of the control regions of the three different gate driving COFs 81 will be not identical. These differences are easy to appear in the border areas between the control regions of the different gate driving COFs 81, and to form an apparent boundary line.
As a result, it is necessary to provide a driving circuit structure of a liquid crystal panel to solve the problems existing in the conventional technologies.
A primary object of the present invention is to provide a driving circuit structure of a liquid crystal panel to solve the problem existing in the conventional technologies, the problem is: when all of the liquid crystal panel shows an even picture, the brightness of the control regions of the three different gate driving will be not identical to form an apparent boundary line.
To achieve the above object, the present invention provides a driving circuit structure of a liquid crystal panel, which mainly comprises a liquid crystal panel, wherein the liquid crystal panel has an edge of a gate driving circuit and an edge of a source driving circuit; along a gate scanning direction, the edge of the gate driving circuit is provided with a first gate driver COF (chip on film), a second gate driving COF and a third gate driving COF in turn; and each of the gate driving COFs comprises:
In one embodiment of the present invention, the trace portion is a fan-out trace portion, and traces of the trace portion have a fan shape.
In one embodiment of the present invention, a trace resistance value of the trace portion of the second gate driving COF is smaller than a trace resistance value of the trace portion of the first gate driving COF; and a trace resistance value of the trace portion of the third gate driving COF is smaller than the trace resistance value of the trace portion of the second gate driving COF.
In one embodiment of the present invention, the intensity of output signals of the gate driving COFs are identical.
To achieve the above object, the present invention further provides a driving circuit structure of a liquid crystal panel, which mainly comprises a liquid crystal panel, wherein the liquid crystal panel has an edge of a gate driving circuit and an edge of a source driving circuit; along a gate scanning direction, the edge of the gate driving circuit is provided with a plurality of COFs in turn; and each of the gate driving COFs comprises:
In one embodiment of the present invention, the trace portion is a fan-out trace portion, and traces of the trace portion have a fan shape.
In one embodiment of the present invention, trace resistance values of the trace portions of the COFs are gradually decreased along a gate scanning direction.
To achieve the above object, the present invention further provides a driving circuit structure of a liquid crystal panel, which mainly comprises a liquid crystal panel, wherein the liquid crystal panel has an edge of a gate driving circuit and an edge of a source driving circuit; along a gate scanning direction, the edge of the gate driving circuit is provided with a plurality of COFs in turn; and each of the gate driving COFs comprises:
In one embodiment of the present invention, the trace portion is a fan-out trace portion, and traces of the trace portion have a fan shape.
In one embodiment of the present invention, trace widths of the trace portions of the COFs are gradually increased, and intensity of the output signals of the gate driving COFs are identical.
In the present invention, by gradually increasing the trace widths of the trace portions of the gate driving COFs along the gate scanning direction (the trace resistance values are gradually decreased), the intensity of the output signals of the gate driving COFs can be identical. Hence, it can eliminate the phenomenon of apparent boundary line that is appeared between the gate driving COFs of the liquid crystal panel, so as to increase the display quality.
The foregoing objects, features and advantages adopted by the present invention can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings. Furthermore, the directional terms described in the present invention, such as upper, lower, front, rear, left, right, inner, outer, side and etc., are only directions referring to the accompanying drawings, so that the used directional terms are used to describe and understand the present invention, but the present invention is not limited thereto.
Referring now to
As shown in
Furthermore, as shown in
In addition, the second gate driving COF 22 and the third gate driving COF 23 have structures which are similar to the structure of the first gate driving COF 21. However, the difference between the first gate driving COF 21, the second gate driving COF 22 and the third gate driving COF 23 is that: a trace width of the trace portion 223 of the second gate driving COF 22 is greater than a trace width of the trace portion 213 of the first gate driving COF 21; and a trace width of the trace portion 233 of the third gate driving COF 23 is greater than the trace width of the trace portion 223 of the second gate driving COF 22.
For detailed description, the gate driving COFs 21, 22, 23 are connected by wire on Array (WOA), so it causes the output signals of the gate driving COFs 21, 22, 23 are not identical. Because a RC delay effect (by resistance and the capacitance) is produced in transmission of metal wire connection, along the gate scanning direction S, a gate output signal of the second gate driving COF 22 will be decreased than the first gate driving COF 21; and a gate output signal of the third gate driving COF 23 will be decreased than the second gate driving COF 22.
For equalizing the output signals of the gate driving COFs 21, 22, 23, the driving circuit structure of the liquid crystal panel according to the present invention are adjusted by changing the resistance values of the traces. Specifically, because the resistance values of the traces are related to the width of the traces, the one which has a wider trace has a smaller resistance value. Hence, in the present invention, by gradually increasing the width of the traces of the gate driving COFs 21, 22, 23 along the gate scanning direction S (the trace resistance values are gradually decreased), so that the intensity of the output signals of the gate driving COFs 21, 22, 23 can be identical.
Moreover, although it is disclosed in the preferred embodiment of the present invention that the edge of the gate driving circuit 11 of the liquid crystal panel 10 is provided with three of the gate driving COFs 21, 22, 23, but it is not limited in the present invention, so that the number of the gate driving COFs can be two or more.
As described above, for the traditional COF structure, there is a phenomenon of apparent boundary line between gate driving COFs of a liquid crystal panel. In the present invention, by gradually increasing the trace widths of the trace portions of the gate driving COFs 21, 22, 23 along the gate scanning direction, the intensity of the output signals of the gate driving COFs 21, 22, 23 can be identical. Hence, the driving circuit structure of the liquid crystal panel according to the present invention can eliminate the phenomenon of apparent boundary line (“H-block issue” or “Block Dim”) that is appeared between the gate driving COFs 21, 22, 23 of the liquid crystal panel 10, so as to increase the display quality.
The present invention has been described with a preferred embodiment thereof and it is understood that many changes and modifications to the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201210365719.6 | Sep 2012 | CN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN2012/082559 | 10/8/2012 | WO | 00 | 12/10/2012 |
