Computer graphics processing and selective visual display system – Display driving control circuitry – Display power source
Reexamination Certificate
2001-03-27
2003-12-09
Lao, Lun-Yi (Department: 2673)
Computer graphics processing and selective visual display system
Display driving control circuitry
Display power source
C345S204000, C345S100000
Reexamination Certificate
active
06661413
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a wiring structure in like a liquid crystal display (LCD), and more particularly to a structure, apparatus and method for supplying an averaged voltage to a plurality of LSIs that are connected in a chain-like manner (i.e., one after another).
BACKGROUND OF THE INVENTION
In recent years, a liquid crystal panel (LCD panel) on which an image is displayed is required to be low in cost. As one means to keep the cost down, Chip On Glass (COG) is commonly known. COG is the technique to mount a couple of or dozens of LCD driver LSI chips, which are provided for one LCD panel, intact on a glass substrate. Also suggested is the combination of COG being combined with Wiring On Array (WOA) that implements the wiring on the glass. According to the COG&WOA technique, it becomes possible to attach the LSI itself directly to the glass substrate, and at the same time, omit the wiring that is presently put on the printed circuit board, so that the cost of production can be vastly lowered and can be granted the requests for a narrow frame in recent years.
On the other hand, there have been some proposals as to the method for achieving the wiring of LCD driver LSIs on glass substrates. For example, one of them is to reduce the number of input signals of LCD driver LSIs to reduce a necessary wiring area, in order to achieve the wiring in frame portions of glass substrates. In addition, the present applicant previously proposed a technique that achieves a fast serial video transfer peculiar to LCD driver LSIs by means of cascade connections (Japanese Patent Application No. Hei 11-351784). Furthermore, there has been proposed a technique to reduce the number of wiring for reference voltage, which must be provided on glass substrates, by generating a reference voltage for y compensation in LCD driver LSIs.
By using the WOA technique, external PCB or Flexible Printed Circuit (FPC) that have been used for the wiring of LCD driver LSIs are no longer needed, whereby drastic cost reduction can be achieved. Also, since mechanical connections are reduced drastically, good results are expected about yield rate.
However, in conventional liquid crystal panels, generally a wiring on glass substrates consists of a very thin metal (2500 Å) and results in high resistance wiring whose sheet resistance is about
0.16&OHgr;/&mgr;m. With this high resistance wiring, it is impossible to supply uniform voltage to a plurality of LCD driver LSIs, whereby tens to hundreds mV of voltage difference occurs on the voltages which individual LCD driver LSIs receive, due to the voltage drop in the wiring paths. In case of supplying the reference voltage for y compensation, this voltage difference appears as a gradation difference of every LCD driver LSI, whereby uniformity of outputs can not be maintained due to this gradation difference, which results in significant deterioration in image quality. In light of that, in conventional liquid crystal panels, the wiring to supply the reference voltage for &ggr; compensation can not be provided on the glass substrate, so there has been little choice but to configure in a manner where the wiring with sufficiently low resistance is provided on the external PCB (Printed Circuit Board) or FPC, in order to supply the reference voltage to each LCD driver LSI
On the other hand, a method for supplying the uniform voltage is conceivable by making the thickness of metal wiring sufficiently thick or making wiring widths sufficiently wide on the glass substrate, in order to ensure low resistance. However, making the thickness sufficiently thick can cause an increase of process occupied time or other adverse effects on the yield rate of TFT arrays for the production of LCD panels. In case of making wiring widths sufficiently wide, it is necessary to make frame portions of TFT arrays larger in order to secure a wiring space, which greatly runs counter to the requests in recent years. Namely, thought it is possible to provide wiring with low resistance with changing thickness or materials of wiring, which can not sufficiently lead to cost savings and a narrow frame, resulting in no use in employing WOA technique.
Furthermore, in order to generate a reference voltage for &ggr; compensation, a technique is commonly used where an input voltage is divided by ladder resistors provided in the LCD driver LSIs to generate an intended voltage. In this technique, when the wiring of the reference voltage for &ggr; compensation is done by low resistance wiring, a practically unquestionable performance can be achieved, however, with the conventional wiring on the glass, which has high resistance, it is impossible to deliver its thorough performance.
In light of these above technical problems, it is an object of the present invention to reduce the difference of voltages that each LSI receives, in the individual LSIs connected in a chain-like manner (i.e., one after another).
SUMMARY OF INVENTION
The present invention is directed to an apparatus for supplying a voltage for &ggr; compensation to a plurality of driver LSIs mounted on the same substrate as the one on which liquid crystal cells are formed, by using a wiring structure of high resistivity formed on the same substrate. Namely, an LCD module according to the present invention consists of liquid crystal cells forming an image display area on a substrate; a plurality of driver LSIs mounted on this substrate for applying voltages to the liquid crystal cells; and a wiring structure formed on this substrate for supplying a voltage to the plurality of driver LSIs, wherein this wiring structure supplies the voltage to the plurality of driver LSIs, with the wiring whose resistance gradually changing from a voltage supply point. Also, it is characterized in that this wiring structure supplies the voltage to the plurality of driver LSIs via a forward wiring and a backward wiring. Furthermore, it is characterized in that the forward wiring and the backward wiring are connected like a single stroke of the brush to supply the voltage to the plurality of driver LSIs. Note, considering the present invention as a computer, such as a notebook-sized personal computer, the present invention further includes a host for executing an application, and a plurality of driver LSIs mounted on the substrate for applying voltages to the liquid crystal cells based on a signal from the host.
In another aspect of the present invention, a liquid crystal display according to the invention consists of liquid crystal cells forming a image display area on a substrate; a plurality of driver LSIs mounted on this substrate for applying voltages to the liquid crystal cells; and a wiring structure formed on this substrate for supplying a voltage supplied from a voltage supply point to the plurality of driver LSIs; wherein this wiring structure consists of a forward wiring that starts wiring of the driver LSIs from a driver LSI located near the voltage supply point up to a downstream driver LSI in order, thereby supplying the voltage to the driver LSIs; and a backward wiring that starts wiring of the driver LSIs from the downstream driver LSI up to the driver LSI located near the voltage supply point in order, thereby supplying the voltage to the driver LSIs; wherein the directions of voltage drop in the forward wiring and the backward wiring are opposite.
The wiring structure is characterized in that, in the forward wiring, a wiring width is gradually reduced from the wiring for the driver LSI located near the voltage supply point to the wiring for the downstream driver LSI, whereas in the backward wiring, a wiring width is gradually reduced from the wiring for the downstream driver LSI to the wiring for the driver LSI located near the voltage supply point, thereby enabling to gradually change the wiring resistance by means of wiring widths, so that the slope of voltage drop is controlled with a simple wiring structure on the substrate.
It is also characterized in that, the plurality of driver LSIs includes input pads and output pads f
Jennings Derek S.
Lao Lun-Yi
LandOfFree
Wiring structure and method thereof for a LCD module does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Wiring structure and method thereof for a LCD module, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wiring structure and method thereof for a LCD module will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3159568