Patent Application
20100134470
1. Field of Invention
The present invention relates to a driving circuit. More particularly, the present invention relates to a source driving circuit of a liquid crystal display.
2. Description of Related Art
In a conventional liquid crystal display, there usually includes a driver system where a source driving circuit can be designed therein, and a timing controller system where a timing controller, a gamma circuit and a common voltage circuit can be designed therein. The gamma circuit and common voltage circuit cooperate with the timing controller and transmit the gamma voltage and common voltage, respectively, to the source driving circuit.
However, since the gamma circuit and common voltage circuit both are usually designed in the timing controller system, there must be extra costs for them. Thus, there is a need to incorporate the gamma circuit and common voltage circuit or the functions thereof into the source driving circuit in order to save the costs.
In accordance with one embodiment of the present invention, a source driving circuit of a liquid crystal display is provided. The source driving circuit includes a gamma voltage generator, a common voltage generator and a driver. The gamma voltage generator receives gamma data from a timing controller through reduced swing differential signaling (RSDS) transmission interface to generate corresponding gamma voltages. The common voltage generator receives common voltage data from the timing controller to generate a corresponding common voltage. The driver receives image data from the timing controller through the RSDS transmission interface, the gamma voltages from the gamma voltage generator and the common voltage from the common voltage generator for modifying the image data using the gamma voltages and the common voltage and transmitting the modified image data to a panel of the liquid crystal display.
In accordance with another embodiment of the present invention, a liquid crystal display is provided. The liquid crystal display includes a timing controller, a display panel and a source driving circuit. The timing controller transmits image data, gamma data and common voltage data using reduced swing differential signaling (RSDS) transmission interface. The source driving circuit includes a gamma voltage generator and a driver, in which the gamma voltage generator receives the gamma data and the common voltage data from the timing controller to generate a corresponding common voltage and corresponding gamma voltages, and the driver receives the image data from the timing controller, the common voltage and the gamma voltages from the gamma voltage generator for modifying the image data in response to the common voltage and the gamma voltages and delivers the modified image data to the display panel.
It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed.
The invention can be more fully understood by reading the following detailed description of the embodiments, with reference to the accompanying drawings as follows:
In the following detailed description, the embodiments of the present invention have been shown and described. As will be realized, the invention is capable of modification in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not restrictive.
The source driving circuit 125 further includes a gamma voltage generator, a common voltage generator and a driver 150, in which the gamma voltage generator and the common voltage generator can be individually designed in the source driving circuit 125 or, for example, integrated into a gamma/common voltage generator 152 in the present embodiment. Nevertheless, the functions of the individual gamma voltage generator and the common voltage generator may be similar to those of the gamma/common voltage generator 152.
In the present embodiment, the gamma/common voltage generator 152 receives the gamma data from the timing controller 135 through the RSDS transmission interface to generate corresponding gamma voltages and also receives common voltage data from the timing controller 135 to generate a corresponding common voltage. The driver 150 receives image data from the timing controller 135 through the RSDS transmission interface, the gamma voltages and the common voltage from the gamma/common voltage generator 152, for modifying the image data using the gamma voltages and the common voltage and transmitting the modified image data to the LCD panel 110.
The gamma/common voltage generator 152 can be incorporated into the source driving circuit 125 because it includes operational amplifiers (OP) and digital-to-analog converters (DAC) like the driver 150 and functions in a similar manner to the driver 150 as well. Thus, if the timing controller 135 transmits the gamma data through the RSDS transmission interface, the gamma data can be processed only by the source driving circuit 125.
In the following embodiments, the gamma/common voltage generator which is incorporated by using the preset dummy channels are discussed, and only a few dummy channels, each of which includes a DAC and a buffer unit, are illustrated in order to simplify the discussion and should be regarded as illustrative in nature, and not restrictive.
The reference voltage generator 302 can be an R-string circuit and generate N reference voltages having different voltage levels in accordance with a voltage-divided resistance ratio. The DACs 304 receives the reference voltages and the gamma data, transmitted from the timing controller, and correspondingly generates N (N is an integer) gamma voltages according to the gamma data. In addition, one of the DACs 304 can receive one of reference voltages and the common voltage data, transmitted from the timing controller, and correspondingly generate the common voltage (VCOM) according to the common voltage data.
The buffer units 306 can be implemented by operational amplifiers (OP) and stabilize the common voltage and the gamma voltages from the DACs 304. The voltage-dividing element 308 can be an R-string circuit consisted of serially connected resistors Req, each of which is further consisted of several resistors. The voltage-dividing element 308 transforms the N gamma voltages generated by the DACs 304 into M (M is an integer) gamma voltages, where M can be larger than N; that is, the voltage-dividing element 308 is used for division of voltages to generate M gamma voltages having different voltage levels in accordance with a voltage-divided resistance ratio. Afterwards, the generated gamma voltages and common voltage are transmitted to the driver.
For the foregoing embodiments, the source driving circuit can be provided to save the extra costs in the timing controller system. In addition, the source driving circuit can thus generate dynamic gamma voltages due to receiving the dynamic gamma data transmitted from the timing controller system. In other words, the gamma data can be continually transmitted from the timing controller system to the source driving circuit, and the gamma curve performed by the source driving circuit can be thus updated continually.
As is understood by a person skilled in the art, the foregoing embodiments of the present invention are illustrative of the present invention rather than limiting of the present invention. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.
