Patent Application
20130265292
1. Technical Field
The present disclosure relates to display panel driving technologies, and more particularly, to an apparatus for driving a display panel, and a display device using the apparatus.
2. Description of Related Art
Liquid crystal displays (LCDs) utilize liquid crystal molecules to control light transmissivity of pixel units, where the liquid crystal molecules in a pixel unit tilt to a corresponding angle in accordance with a driving voltage applied to the pixel unit. The driving voltage is normally provided by a source driver.
In order to protect the liquid crystal molecules from decay or damage, a typical LCD may employ a polarity inversion driving method. In the polarity inversion driving method, each pixel unit is provided with a positive driving voltage in a frame period, and in a next frame period, the driving voltage provided to the pixel unit is changed to be negative. In other words, the polarity inversion driving method requires the source driver to output driving voltages having two different polarities in two consecutive frame periods. This causes power consumption of the typical LCD to increase.
What is needed is a means that can overcome the above-described limitations.
The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of at least one embodiment. In the drawings, like reference numerals designate corresponding parts throughout the various views, and all the views are schematic.
Reference will be made to the drawings to describe certain exemplary embodiments of the present disclosure.
The apparatus 800 includes a source driver 100, a control switch 30, a plurality of charge sharing capacitors C1, C2, C3, . . . , C(n−1), a plurality of charge sharing switches sw1, sw2, sw3, . . . , sw(n−1), and a driving voltage output terminal 10. The output terminal 10 is electrically connected to the display panel 200, and outputs driving voltages to the display panel 200.
The source driver 100 includes a data voltage output terminal 20 for outputting data voltages. The control switch 30 is connected between the data voltage output terminal 20 and the driving voltage output terminal 10. Each of the charge sharing capacitors C1, C2, C3, . . . , C(n−1) corresponds to a charge sharing switch sw1, sw2, sw3, . . . , sw(n−1), and in this embodiment, each one of the charge sharing capacitors C1, C2, C3, . . . , C(n−1) and the corresponding charge sharing switch sw1, sw2, sw3, . . . , sw(n−1) is connected in series between the driving voltage output terminal 10 and ground, and cooperatively form a charge sharing branch. Accordingly, a plurality of charge sharing branches are connected in parallel and formed in the apparatus 800.
Referring to
At the data voltage outputting periods T1 to T(2n−1), the control switch 30 is switched on under the control of an external control signal. Thus, the data voltages V1, V2, V3, . . . , V(n−1), Vn, V(n−1), V(n−2), V(n−3) . . . , V2, V1, which are output by the source driver 100, are transmitted to the driving voltage output terminal 10 and then output to the display panel 200 for the duration of the data voltage outputting periods T1 to T(2n−1). At the charge sharing periods, the control switch 30 is switched off and the charge sharing switches sw1 to sw(n−1) are switched on in sequence under the control of the external control signal, such that the charge sharing capacitors C1 to C(n−1) feed their charges in turn to the display panel 200.
Specifically, at a first data voltage output period T1, the control switch 30 is switched on, and the first data voltage V1 provided by the source driver 100 is output to the display panel 200; after period T1, at a first charge sharing period between T1 and T2, the first charge sharing switch sw1 is switched on, and thus the first charge sharing capacitor C1 feeds the charge therein to the display panel 200; at a second data voltage output period T2, the control switch 30 is switched on again, and the second data voltage V2 provided by the source driver 100 is output to the display panel; at a second charge sharing period between T2 and T3, the second charge sharing switch sw2 is switched on, and the second charge sharing capacitor C2 feeds the charge therein to the display panel 200; the operation of the apparatus 800 repeats and cycles in the above-mentioned manner, and at a (2n−1)th data voltage outputting period T(2n−1), the control switch 30 is switched on, and the source driver 100 re-outputs the first data voltage V1 to the display panel 200.
In the display device according to the present disclosure, because the charge sharing capacitors C1, C2, C3, . . . , C(n−1) can share their charges with the display panel 200 during the charge sharing periods, the source driver 100 merely needs to output the data voltages discontinuously, during the data voltage outputting periods. As such, the power consumption of the source driver 100 is significantly reduced.
Furthermore, in the display device according to the present disclosure, the number of the charge sharing branches may be designed as needed. In one embodiment, the apparatus 800 may only include one charge sharing branch, i.e., n=2, and thus a single capacitor C1 and a single second control switch sw1 are included in the apparatus 800. Accordingly, the first control switch 30 and the second control switch sw1 are alternately switched on.
In another embodiment, the apparatus 800 may include two charge sharing branches, i.e., n=3, thus a first charge sharing branch (including a first charge sharing capacitor C1 and a first charge sharing switch sw1) and a second charge sharing branch (including a second charge sharing capacitor C2 and a second charge sharing switch sw2) are connected between the driving voltage output terminal 10 and the ground. Assuming the source driver 100 outputs sequential data voltages 30V, 15V, 0V, 15V, 30V during the respective data voltage output periods T1, T2, T3, T4, T5, and capacitance of each of the first and second charge sharing capacitors C1, C2 is substantially equal to an equivalent capacitance of the display panel 200, it can be calculated that the first and second charge sharing capacitors C1, C2 reach their saturation voltages after thirteen driving periods, and the power consumption of the source driver 100 will be reduced by 33.3% from the 14th driving period onwards. Alternatively, for the same function of the source driver 100, but the capacitance of each of the first and second charge sharing capacitors C1, C2 is about five times the equivalent capacitance of the display panel 200, it can be calculated that the first and second charge sharing capacitors C1, C2 reach their saturation voltages after forty driving periods, and the power consumption of the source driver 100 will be reduced by 45.3% from the 41th driving period onwards.
Referring to
It is to be further understood that even though numerous characteristics and advantages of preferred and exemplary embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and changes may be made in detail, especially in the matters of shape, size and arrangement of parts within the principles of the present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 101112125 | Apr 2012 | TW | national |
