Patent Application
20090231363
1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device using multiplexers capable of providing an improvement of line mura between pixels.
2. Description of Prior Art
More and more advanced-function displays have found their applications in current consumer electronic products. In particular, liquid crystal displays (LCDs) having a high-resolution color screen, are more widely applied in various electronic devices, such as televisions, mobile phones, personal digital assistances (PDA), digital cameras, desktop computer screens, and notebook computer screens.
Referring to
As to the conventional liquid crystal display, the gate driver 14 functions as a shift register. In other words, the gate driver 16 outputs a scanning signal to the liquid crystal display 12 at a fixed interval. For instance, a liquid crystal display 12 with 1024×768 pixels and its operating frequency with 60 Hz is provided, the display interval of each frame is about 16.67 ms (i.e., 1/60 second), such that an interval between two scanning signals applied on two row adjacent lines is about 21.7 μs (i.e., 16.67 ms/768). The pixel units 20 are charged and discharged by data voltage from the source driver 16 to show corresponding gray levels in the time period of 21.7 μs accordingly.
In general, as a skilled person in this art is aware, the voltage across the two electrodes has two polarities. A voltage of the pixel electrode larger than that of the common electrode is called positive polarity, and inversely, a voltage of the common electrode larger than that of the pixel electrode is called negative polarity. If absolute values of the voltage difference across the two electrodes are identical, no matter whether the voltage value of the pixel electrode or that of the common electrode is higher, an identical gray level is obtained. However, in fact, opposed voltage difference value across the two electrodes results in the opposed alignments of the liquid crystal molecules.
From a view of long-term sum effect, if the voltage across the two electrodes tends toward either polarity for a while, the common voltage applied on the common electrode causes a voltage-drifting phenomenon. Consequently, the alignment of the liquid crystal molecules fails to be varied based on the required control voltage, resulting in displaying incorrect gray levels. In an extreme situation, it is possible that if the voltage across the two electrodes tends toward either polarity for a long while, even if no voltage is applied, the liquid crystal molecules still fail to be aligned based on a variety of electrical fields. As a result, in order to prevent the common voltage from experiencing the voltage-drifting phenomenon as the voltage applied across the two electrodes tends toward any polarity, the voltages across the two electrodes are periodically switched between positive polarity and negative polarity. Dot inversion mode, by which each pixel unit alternately varies polarity and its neighbor pixels have inversed polarities all the time, is widely used for periodically driving the voltage across the liquid crystal molecules.
With reference to
Considering the first pixel group, switch units SW11, SW12, SW13, SW14, SW15, and SW16 are coupled to pixel unit R11, G11, B11, R12, G12, and B12, respectively. Considering the second pixel group, switch units SW21, SW22, SW23, SW24, SW25, and SW26 are coupled to pixel R21, G21, B21, R22, G22, B22, respectively. The switch units SW11, SW21 are controlled by scan signal voltage SCAN™. The switch units SW12, SW22 are controlled by scan signal voltage SCAN2. The switch units SW13, SW23 are controlled by scan signal voltage SCAN3. The switch units SW14, SW24 are controlled by scan signal voltage SCAN4. The switch units SW15, SW25 are controlled by scan signal voltage SCAN5. The switch units SW16, SW26 are controlled by scan signal voltage SCAN6.
During an interval t1, when the switch unit SW11, SW21 turns on in response to the scan signal voltage SCAN™, the pixel unit R11 of the first pixel group, and the pixel unit R21 of the second pixel group shows corresponding grey levels based on the polarity signal voltage S1, S2, respectively. During an interval t2, when the switch unit SWT2, SW22 turns on in response to the scan signal voltage SCAN2, the pixel unit G11 of the first pixel group, and the pixel unit G21 of the second pixel group shows corresponding grey levels based on the polarity signal voltage S1, S2, respectively. During an interval t3, when the switch unit SW13, SW23 turns on in response to the scan signal voltage SCAN3, the pixel unit B11 of the first pixel group, and the pixel unit B21 of the second pixel group shows corresponding grey levels based on the polarity signal voltage S1, S2, respectively. During an interval t4, when the switch unit SW14, SW24 turns on in response to the scan signal voltage SCAN4, the pixel unit R12 of the first pixel group, and the pixel unit R22 of the second pixel group shows corresponding grey levels based on the polarity signal voltage S1, S2, respectively. During an interval t5, when the switch unit SW15, SW25 turns on in response to the scan signal voltage SCAN5, the pixel unit G12 of the first pixel group, and the pixel unit G22 of the second pixel group shows corresponding grey levels based on the polarity signal voltage S1, S2, respectively. During an interval t6, when the switch unit SW16, SW26 turns on in response to the scan signal voltage SCAN6, the pixel unit B12 of the first pixel group, and the pixel unit B22 of the second pixel group shows corresponding grey levels based on the polarity signal voltage S1, S2, respectively.
Nevertheless, as shown in
It is therefore an objective of the claimed invention to provide a LCD device and a related driving method to provide an improvement of crosstalk between pixels, so as to solve the above-mentioned problem.
Briefly summarized, the present invention provides a liquid crystal display (LCD) device. The LCD device comprises a gate driver, a source driver, and a LCD panel. The gate driver is used for generating a first scan signal voltage and a second scan signal voltage. The source driver is used for generating a first polarity data voltage and a second data voltage. The liquid crystal display panel comprises a plurality of first pixel groups and a plurality of second pixel groups. Each first pixel group and each second pixel group comprise a first pixel unit and a second pixel unit. Both the first pixel unit of each first pixel group and the second pixel unit of each second pixel group show grey level based on the first polarity data voltage, when receiving the first scan signal voltage. Both the second pixel unit of each first pixel group and the first pixel unit of each second pixel group show grey levels based on the second polarity data voltage, when receiving the second scan signal voltage.
According to the present invention, a method of driving a LCD panel is provided. The LCD panel comprises a plurality of first pixel groups and a plurality of second pixel groups. Each first pixel group and each second pixel group comprise a first pixel unit and a second pixel unit. The method comprises the following steps: generating a first scan signal voltage and a second scan signal voltage in order; generating a first polarity data voltage and a second data voltage, wherein a polarity of the first polarity data voltage is inversed to that of second polarity data voltage; at a first moment both the first pixel unit of each first pixel group and the second pixel unit of each second pixel group show grey level based on the first polarity data voltage, when receiving the first scan signal voltage; and at a second moment both the second pixel unit of each first pixel group and the first pixel unit of each second pixel group show grey levels based on the second polarity data voltage, when receiving the second scan signal voltage.
These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Referring to
In this embodiment, considering the first pixel group, switch units SW11, SW12, SW13, SW14, SW15, and SW16 are coupled to pixel unit R11, G11, B11, R12, G12, and B12, respectively. Considering the second pixel group, switch units SW21, SW22, SW23, SW24, SW25, and SW26 are coupled to pixel R21, G21, B21, R22, G22, B22, respectively. It is noted that the switch units SW11, SW24 are controlled by scan signal voltage SCAN™; the switch units SW12, SW25 are controlled by scan signal voltage SCAN2; the switch units SW13, SW26 are controlled by scan signal voltage SCAN3; the switch units SW14, SW21 are controlled by scan signal voltage SCAN4; the switch units SW15, SW22 are controlled by scan signal voltage SCAN5; and the switch units SW16, SW23 are controlled by scan signal voltage SCAN6.
Referring to
The first multiplexer 1081 outputs the first polarity data voltage S1 to the pixel units R11, B11, and G12 of the first pixel group in response to the first selecting signal SEL1, or outputs the second polarity data voltage S2 to the pixel units G11, R12, and B12 of the first pixel group in response to the second selecting signal SEL2. The second multiplexer 1082 outputs the second polarity data voltage S2 to the pixel units R21, B21, and G22 of the second pixel group in response to the first selecting signal SEL1, or outputs the second polarity data voltage S2 to the pixel units G21, R22, and B22 of the second pixel group in response to the second selecting signal SEL2. It is noted that the first polarity data voltage S1 in response to the first selecting signal SEL1 has inversed polarity to that in response to the second selecting signal SEL2. For example, the first polarity data voltage S1 in response to the first selecting signal SEL1 is positive polarity, while the first polarity data voltage S1 in response to the second selecting signal SEL2 is negative polarity. Conversely, the first polarity data voltage S1 in response to the first selecting signal SEL1 is negative polarity, while the first polarity data voltage S1 in response to the second selecting signal SEL2 is positive polarity. Similarly, the second polarity data voltage S2 in response to the first selecting signal SEL1 has inversed polarity to that in response to the second selecting signal SEL2.
Referring to
Please note that the functional block diagram of the LCD devices 100, 200 shown in
In contrast to prior art, the present inventive LCD device incorporating 1 to 6*N multiplexer scheme can provide an improvement of line mura between pixel units under dot inversion mode.
While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 097108757 | Mar 2008 | TW | national |
