Patent Application
20070262946
1. Field of the Invention
The present invention relates to systems and methods for controlling a display device.
2. Description of the Prior Art
Most cellular phones on the market comprise a display device such as a liquid crystal display to show an interface through which a user can manipulate the cellular phone. When a cellular phone is powered on but not in use for a period of time, the cellular phone probably enters a stand-by mode for the sake of protecting the display device or lowering power consumption of the entire cellular phone. Two common stand-by modes are an idle mode and an eight-color mode. In addition, a cellular phone also comprises a control circuit to control the display device. However, in either an idle mode or an eight-color mode, the control circuit is required to send data to the display device to keep a stand-by image shown on the display device. In short, although a cellular phone operates in a stand-by mode, the control circuit of the cellular phone still consumes too much power.
Systems for controlling a display device are provided. An embodiment of such a system comprises a control circuit and a register. The control circuit, which is coupled to the display device, alternately enables and disables driving of the display device by referring to a first control value and a second control value to keep an image shown on the display device. The register, which is coupled to the control circuit, stores the first control value and the second control value.
Another embodiment of such a system comprises means for alternately enabling and disabling driving of the display device by referring to a first control value and a second control value to keep an image shown on the display device; and means for storing the first control value and the second control value.
Methods for controlling a display device are provided. An embodiment of such a method comprises alternately enabling and disabling driving of the display device by referring to a first control value and a second control value to keep an image shown on the display device.
Recently, a kind of thin film transistor (TFT) LCD, which is made by a low temperature poly silicon (LTPS) technology, was introduced. Compared to a conventional amorphous TFT LCD, which has a leakage current in an order of 10−5˜10−6 A, the LTPS TFT LCD has a leakage current only in an order of 10−9˜1013 A. Obviously, the leakage current of the LTPS TFT LCD is much smaller than the leakage current of the amorphous TFT LCD. Due to the characteristic of low leakage current, the data, more specifically the voltage level, on each liquid crystal cell of an LTPS TFT LCD can be kept for a longer time. In other words, when each liquid crystal cell of an LCD made by LTPS TFT is fed into data, i.e., is charged to a voltage level, an image is therefore shown on the LCD. Afterwards if the liquid crystal cells are not re-flashed, i.e., if there is no more data fed into the liquid crystal cells, the same still image will not fade out until the charges on the liquid crystal cells are drained out by the little leakage current. Consequently, without re-flashing data stored on LCD cells, an LTPS TFT LCD, compared to a conventional amorphous TFT LCD, can keep the image shown on the display for a longer time.
By utilizing the above-mentioned characteristic of low leakage current, any electronic device comprising a display device (e.g., a laptop computer, a mobile phone, a digital camera, a personal digital assistant (PDA), a desktop computer, a television, a car display or a portable DVD player) can save more power in a stand-by mode. With reference to
After the re-flashing process, the control circuit 110 again disables the driving of the display device 120 for the same time period T1 from time t3 to time t4 for saving power. Before the electronic device turns back to the normal mode again at time t6, the stand-by image requires being re-flashed again from time t4 to time t5, which also lasts for the same time period T2.
The register 130 stores several sets of control values. Each set includes a first control value and a second control value for respectively determining the non-driving time period T1 and the driving time period T2. After a set of control values is determined by the user, the control circuit 110 reads the set of control values to determine the time periods T1 and T2. Please note that the control circuit 110 disables the driving of the display device 120 by cutting off sending control signals to the display device 120 for saving power. To save more power, the control circuit 110 disables the driving of the display device 120 by powering off the control circuit 110. As a result, during time periods T1 when the display device 120 is not driven, even the control circuit 110 does not consume power.
In summary, an electronic device becomes more energy saving in a stand-by mode by alternatively enabling and disabling the driving of the display device belonging to the electronic device. A control circuit of the electronic device, which is in charge of controlling the display device, refers to control values stored in a register coupled to the control circuit to determine when and for how long a time to disable or enable the driving of the display device. The control circuit disables the driving of the display device by not sending control signals to the display device, or powering off for achieving even less power consumption.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
