1. Field of the Invention
The invention relates to a timing controller, and more particularly to a timing controller capable of adjusting its timing signal.
2. Description of the Related Art
A liquid crystal display (LCD) apparatus generally includes two substrates, each having an electrode formed on an inner surface thereof, and a liquid crystal layer interposed between the two substrates. In the LCD apparatus, a voltage is applied to the electrodes to re-align liquid crystal molecules and control an amount of light transmitted through the liquid crystal layer, thereby obtaining desired images.
The refresh rate of the LCD apparatus may be kept at a high rate, but there is no need for the LCD to operate at such a speed if the user is running an application that does not require fast refresh rate. Dynamic refresh rate switching (DRRS) is applied to dynamically reduce the LCD panel's refresh rate when the system detects that the user is running applications that do not benefit from a high refresh rate, like typing a text document for example.
Furthermore, the dynamic refresh rate switching technology can save the power consumption of the electronic devices and extends the using time of the electronic devices, especially to the portable electronic devices, such as laptop, PDA or others. Compared with conventional design, the refresh rate of monitor is fixed unless user resets the refresh rate. In other words, the conventional design, the refresh rate of monitor is not auto adjusted, and this may waste too much power of the electronic device.
An embodiment of the invention provides a timing controller for receiving display signals based on an input clock signal. The timing controller comprises a frequency detector, a signal generator and a multiplexer. The frequency detector detects a status of the input clock signal to generate a select signal. The signal generator generates a first signal and a second signal, and the first signal and the second signal are one control signal with different attributes. The multiplexer receives and outputs one of the first signal and the second signal according to the decision signal.
Another embodiment of the invention provides a liquid crystal display. The liquid crystal display comprises a source driver, a gate driver and a timing controller. The timing controller controls the source driver and the gate driver. The timing controller comprises a frequency detector, a signal generator and a multiplexer. The frequency detector receives a reference clock signal and an input clock signal to generate a decision signal. The signal generator generates a first signal and a second signal. The multiplexer receives and outputs one of the first signal and the second signal according to the decision signal.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
In one embodiment, the frequency detector 24 detects the frequency change of the input clock signal by comparing the input clock signal with a reference clock signal. Please refer to
To increase the sensitivity of the frequency detector 24, an offset can be applied to the detector for detecting smaller frequency differences by the frequency detector 24. Assuming the multiplexer 25 initially outputs the second signal S2 to the driving circuit 22, the frequency of the input clock signal is f1, the frequency of the reference clock signal is f2 and the offset is fo, the frequency detector 24 will determine that the input clock signal is a high frequency clock signal when f1>f2+fo, and the multiplexer 25 will output the first signal S1 to the driving circuit 22 if the condition occurs. If the frequency f1 is not larger than the sum of frequencies f2 and fo, the multiplexer 25 still outputs the second signal S2 to the driving circuit 22.
Assuming the multiplexer 25 initially outputs the first signal S1 to the driving circuit 22, the frequency detector 24 determines that the input clock signal will change to be a low frequency clock signal when f1<f2−fo, and the multiplexer 25 will output the second signal S2 to the driving circuit 22 if the condition occurs. If the frequency f2 is not larger than the sum of frequencies f1 and fo, the multiplexer 25 still outputs the first signal S1 to the driving circuit 22.
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.