1. Field of the Invention
This invention generally relates to a display circuit, and more particularly to a display circuit and a display method.
2. Description of Related Art
The liquid crystal display (LCD) was applied to the electronic calculator and the electronic watch. Improvements in optoelectronics effect and driving technology have led the LCD to possess the advantages of low power consumption, light weight, and low voltage driving, and to be widely used in TV sets, mobile phones, laptop computers, personal digital assistants (PDAs), etc. The LCD display industry has been recognized to be one of the most thriving industries.
FIG. 1 shows the partial display mode of an LCD panel. Referring to FIG. 1, in the LCD, there is a display mode called the partial display mode. When the LCD works in the partial display mode, display area and non-display area are displayed on the screen. Only the display area will display the image; the non-display area will not display any image.
FIG. 2A is the internal circuit of a conventional LCD. Referring to FIG. 2A, a conventional LCD internal circuit includes a control circuit 210, a scanning driving circuit 220, a data driving circuit 230, and an LCD panel 240. A shift clock signal terminal 211 and a data signal terminal 212 of control circuit 210 are respectively coupled to data driving circuit 230. The n data lines (Y1-Yn) of the data driving circuit 230 and the m scan lines (X1-Xm) of the scanning driving circuit 220 are coupled to the LCD panel 240. The data driving circuit 230 includes the shift register set 231 and n transmission gates 232. Each transmission gate 232 has a first triggering terminal 21 and a second triggering terminal 23 coupled to the shift register set 231. A data signal input terminal 25 of each transmission gate 232 is coupled to the data signal terminal 212 and a data signal output terminal 27 of each transmission gate 232 is coupled to a data line, for example, data line Y3. The shift register set is coupled to the shift clock signal terminal 211 and turns on the transmission gates 232 based on the shift clock signal Vshift.
FIG. 2B is another data driving circuit of a conventional LCD. Referring to FIG. 2B, the data driving circuit 230 uses transistor switches 234 to replace the transmission gates 232 described with respect to FIG. 2A. In FIG. 2B, one source/drain of each transistor 234 is coupled to the shift register set 231, and the other source/drain of each transistor 234 is coupled to a data line, for example, data line Y3. Each transmission gate 232 is coupled to the data signal terminal 212.
The operation principles of the data driving circuit 230 in FIGS. 2A and 2B are the same. The following description is based on the data driving circuit in FIG. 2A. Referring to FIG. 2A, for simplicity, only one pixel circuit 250 is taken as an example for illustration. Pixel circuit 250 includes a thin film transistor (TFT) 251, a capacitor 252, and a pixel electrode 255. The traditional display circuit of the LCD operates in the same way regardless of full display mode or partial display mode. When displaying the image, scanning driving circuit 220 will turn on TFT 251. At the same time, control circuit 210 will send the shift clock signal Vshift and the data signal Vdata. Shift register set 231 decides when to turn on transmission gate 232 is on, the data signal Vdata will be sent to TFT 251. When TFT 251 is on, the data signal Vdata will charge capacitor 252 so that capacitor 252 can make pixel electrode 255 display on the screen.
In the partial display mode, although LCD panel 240 is black at the non-display area, shift register set 231 still has to send the data signal to LCD panel 240. That is, all circuits work in the same way whether they are for the display area or the non-display area. Such structure is simple, but would consume unnecessary power.