Patent Application
20070040794
This application claims priority by virtue of Korean Patent Application No. 2005-75025 filed Aug. 17, 2005.
The present invention relates to a liquid crystal display (LCD) device and, more particularly, to a low power consumption LCD device that can repair a defect and then determine whether a repair is successful.
An LCD display includes a matrix of signal lines such as gate lines and data lines and liquid crystal cells that display images by using an electric field to control the liquid crystal's light transmittance. The driving circuit for supplying the electric field includes a plurality of integrated circuits (ICs) for driving the gate lines and a data lines. The ICs, packaged on tape carrier packages (TCPs) may be connected to the LCD panel by a tape automated bonding (TAB) method or packaged on the LCD panel by a chip-on-glass (COG) method. In the connection process sometimes open-circuit defects occur in the signal lines, data lines or gate lines which decrease the yield of acceptable devices.
In order to detect and repair such open circuits, a signal line and a repair line are shorted and an operational amplifier installed on the printed circuit board supplies a pixel voltage signal to repair the line. In this case, since the operational amplifier always consumes power irrespective of whether the shorted signal line has been repaired or not, there is inefficient power consumption.
In accordance with an aspect of the present invention an LCD device is provided that can detect whether a repair process is successful or not during a testing process. In accordance with an aspect of the present invention, if a signal line is opened, amplifiers of the first and last integrated circuits are enabled, and amplifiers of the other integrated circuits are disabled. Further, if a signal line is opened, a common line connected between a power voltage terminal and a repair amplification terminal of each of the amplifiers is connected to enable the amplifiers. The LCD device further includes a second passing line connected between output terminals of the first and last driving integrated circuits and the second repair line.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawing in which:
Referring to
Each data driver IC 104 includes two operational amplifiers such as amplifier 128 shown in
When the power voltage terminal Vcc and repair amplification terminal RA are commonly connected by the U-shaped common line 126, even if a pixel voltage signal is supplied to the input terminal IT, the operational amplifier 128 is in a disabled state. On the other hand, when the common line 126 is opened by a laser cutting process, if the pixel voltage signal is supplied to the input terminal IT, the operational amplifier 128 becomes an enabled state which generates a repair pixel voltage signal by amplifying the pixel voltage signal.
The repair pixel voltage signal is supplied to the passing line 124 through the output terminal OT of the operational amplifier 128. Such an operational amplifier 128 prevents a delay of the repair pixel voltage signal caused by a second repair line 114 which is formed to detour a display region. As shown in
An LCD panel 110 includes the thin film transistor substrate 106 and a color filter substrate 108 which face each other, and a liquid crystal injected between the two substrates 106 and 108. The color filter (upper) substrate 108 includes color filters for separating the color filters from one another and reflecting external light, a common electrode for supplying a reference voltage Vcom to liquid crystal cells CLC, and an alignment film. The thin film transistor substrate 106 includes gate lines GL, data lines DL, thin film transistors TFT switching elements at intersections of the gate lines GL and data lines DL, pixel electrodes connected to the thin film transistors TFT.
The thin film transistor substrate 106 includes first and second repair lines 112 and 114 for repairing opened data lines. The first repair lines 112 are selectively connected to the input terminals IT of the operational amplifiers 128 included in each data driver IC 104. During a repair process, the first repair lines 112 are connected to one part of an opened data line. The second repair lines 114 are connected to the passing lines 124 and formed to detour the display region. During a repair process, the second repair lines 114 are connected to the other part of the opened data line.
The repair process of the LCD device will now be described with reference to
On the other hand, the LCD device according to the first embodiment of the present invention necessarily demands the laser cutting process for enabling the operational amplifier 128 corresponding to the opened data line. However, since the opened data line DLi is not fixed, the operational amplifier 128 necessitating the laser cutting process is not fixed either. In this case, there is strong probability that another operational amplifier other than the corresponding operational amplifier is subject to the laser cutting process by mistake.
Moreover, the test process performed before the data driver IC and FPC are packaged cannot determine whether the repair process is successful or not. In other words, despite the fact that the operational amplifier 128 corresponding to the opened data line DLi should be selectively enabled, the LCD device according to the first embodiment of the present invention can not selectively enable the operational amplifier 128 packaged in a test unit. Furthermore, if all the operational amplifiers 128 packaged in the test unit operate, a determination cannot be made of whether a signal supplied to the second repair line 114 is a pixel voltage signal or a noise signal. This is because the output terminals of the operational amplifiers 128 are commonly connected to the passing line 124 and thus a repair pixel voltage signal amplified by the operational amplifier corresponding to the opened data line or a noise signal generated from the operational amplifier corresponding to a non-opened data line may be supplied to the second repair line 114.
When the power voltage terminal Vcc and repair amplification terminal RA are commonly connected to the common line 126, even if a pixel voltage signal is supplied to the input terminal IT of the operational amplifier 128, the operational amplifier 128 remains in a disabled state. On the other hand, when the common line 126 is opened by a laser cutting process, if the pixel voltage signal is supplied to the input terminal IT of the operational amplifier 128, the operational amplifier 128 will be enabled and can amplify the pixel voltage signal. If an opened data line is detected, the first data driver IC 104A and the last data driver IC 104B are enabled (by opening their corresponding common line 126. The other data driver ICs 104C remain disabled.
The repair pixel voltage signal amplified through the operational amplifiers 128 included in the first and last data driver ICs 104A and 104B is supplied to the opened data line through the output terminals OT of the operational amplifiers 128, the second passing line 124 and the second repair line 114. The input terminals of the operational amplifiers 128 included in the respective data driver ICs 104 are commonly connected to the first passing line 122 through the first repair line 112.
The second passing line 124 is connected between each of the output terminals of the operational amplifiers 128 included in the first and last data driver ICs 104A and 104B and the second repair line 114.
The first and second passing lines 122 and 124 are formed on the FPC 120 and the printed circuit board 130. The thin film substrate 106 of the LCD panel 110 includes the first and second repair lines 112 and 114 for repairing opened data lines.
The first repair lines 112 are selectively connected to the input terminals IT of the operational amplifiers 128 included in the respective data driver ICs 104 and cross the data lines DL. The first repair lines 112 corresponding to the respective data driver ICs 104 are commonly connected to the first passing line 122 formed on the printed circuit board 130 and the FPC 120. If the data line is opened, the first repair line 112 is connected to the upper part of the opened data line by a laser repair process.
The second repair lines 114 are connected to the second passing lines 124 formed on the printed circuit board and the FPC 120 and formed to detour the display region. Especially, the second repair lines 114 connected through the second passing lines 124 to the output terminals of the first data driver IC 104A are formed to detour one side A1 of the display region. The second repair lines 114 connected through the second passing lines 124 to the output terminals of the last data driver IC 104B is formed to detour the other side A2 of the display region. If the data line is opened, the second repair line 114 is connected to the lower part of the opened data line by the laser repair process.
The thin film transistor substrate 106 of the LCD panel 110 according to the second embodiment of the present invention further includes, as shown in
The FPC pad 140 connected to the FPC 120 supplies the IC input pad 132 with a data control signal and pixel data generated from the timing controller packaged on the printed circuit board 130 and a driving voltage generated from a power supply.
The passing input pad 148 is connected through the first repair line 112 and the first passing line 122 to the input terminals IT of the operational amplifiers 128 included in the data driver ICs 104C except the first and last data driver ICs 104A and 104B. A pixel voltage signal received from the first repair lines 112 corresponding to the data driver ICs 104C except the first and last data driver ICs 104A and 104B is supplied to the passing input pad 148.
The passing output pad 142 is connected to the input terminals IT of the operational amplifiers 128 included in the first and last data driver ICs 104A and 104B through the first repair line 112 and the first passing line 122. The passing output pad 142 supplies a pixel voltage signal received from the passing input pad 148 to the input terminals of the operational amplifiers 128 included in the first and last data driver ICs 104A and 104B.
The FPC repair pad 144 is extended from the first repair output pad 136 connected to the output terminals OT of the operational amplifiers 128 included in the first and last data driver ICs 104A and 104B. The FPC repair pad 144 supplies a repair pixel voltage signal generated from the operational amplifiers 128 included in the first and last data driver ICs 104A and 104B to the second passing line 124 formed on the FPC 120. The second repair pad 146 is extended from the second repair line 114. The second repair pad 146 is connected to the second passing line 124 formed on the FPC 120 and supplies a repair pixel voltage signal generated from the operational amplifiers 128 included in the first and last data driver ICs 104A and 104B to the second repair line 124.
The IC input pad 132 supplies pixel data, a control signal and a power signal generated from the timing controller and power supply packaged on the printed circuit board 130 to the data driver ICs 104 through the FPC output pad 140.
The first repair input pad 138 supplies a pixel voltage signal received from the first repair line 112 to the input terminal IT of the operational amplifier 128 included in the first or last data driver IC 104A or 104B. In this case, the first repair line 112 is shorted by a laser repair process together with the data line DL corresponding to the first or last data driver IC 104A or 104B. The IC output pad 134 is extended from the data line DL and supplies a pixel voltage signal generated from the data driver IC 104 to the data line DL.
The first repair output pad 136 supplies a repair pixel voltage signal amplified by the operational amplifier 128 included in the first or last data driver IC 104A or 104B to the FPC repair pad 144.
In the LCD device according to the second embodiment of the present invention, a determination is made of whether the LCD panel has a defect by supplying a test signal to the data line before the driver IC is packaged on the substrate and the FPC is attached to the LCD panel. A description will be made of a test process of the above-mentioned LCD device with reference to
For the test process, a test signal is supplied to the data lines DL, and a test unit is provided in which a plurality of amplifiers for amplifying a pixel voltage signal is installed. The amplifiers are installed by the unit of data driver ICs to be connected to the data lines. Among the plurality of amplifiers installed in the test unit, amplifiers connected to data lines corresponding to the first and last data driver ICs become an enabled state, and the other amplifiers connected to data lines corresponding to the other data driver ICs become a disabled state.
By using this test unit, the LCD device is driven. While the LCD device is driven, a determination is made of whether a repair pixel voltage signal amplified by the operational amplifier is supplied to a opened data line through the second repair line 114. If the repair pixel voltage signal is supplied to the opened data line, it is concluded that the LCD panel has good quality because the repair process of the opened data line is judged to successful.
At least one of the data driver IC and the gate driver IC is packaged on the LCD device which has obtained good quality, as illustrated in
A repair process of such an LCD device will now be described with reference to
Input terminals of the operational amplifiers included in the respective data driver ICs 104 are commonly connected to the passing lines 122 through the first repair line 112. Since the passing lines 122 are formed on the thin film transistor substrate 106, their length becomes shorter than the passing lines 122 shown in
A repair process of such an LCD device will now be described with reference to
On the other hand, it is possible that in the LCD devices of
Although the present invention has described the case that the data line is opened, it is also applicable to the case that the gate line is opened. That is, the gate driver IC may include operational amplifiers of which input terminals are commonly connected to each other, and only the first and last gate driver ICs may be selectively enabled when the gate line is opened. As described above, the LCD device according to the present invention includes the operational amplifiers which are included in the driver ICs and of which input terminals are commonly connected to the passing line. Among these operational amplifiers, the operational amplifiers included in the first and last driver ICs become an enabled state during a repair process. Then since the first and last driver ICs selectively become the enabled state during the repair process, power consumption can be minimized. Furthermore, since the LCD device according to the present invention fixedly enables operational amplifiers corresponding to the first and last driver ICs installed in the test unit by a laser cutting process, a worker's mistake can be minimized. Hence, the LCD device can detect whether the repair process is successful or not during a test process and thus yield is improved.
While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-75025 | Aug 2005 | KR | national |
