Related arts are hereunder explained with FIGS. 12 and 13.
Firstly, the structure of a first embodiment in the related arts is explained with FIG. 12. FIG. 12 is a circuit configuration diagram of a liquid crystal display by a related art. Each of the pixels constituting a display screen 203 includes a pixel switch 202 and a liquid crystal capacitor 201, and counter electrodes of the liquid crystal capacitors 201 are connected commonly to each other. The gate of each pixel switch 202 is connected to a gate wire driver IC (Integrated Circuit) 207 via a gate wire 204 and the other terminal of each pixel switch 202 is connected to a liquid crystal driver IC 208 having a DA converter circuit via a signal wire 205.
Here, the display screen 203, the gate wires 204, and the signal wires 205 are formed on a glass substrate 206. As a pixel switch 202 which is an active element, an amorphous silicon TFT (Thin Film Transistor) is used.
Next, operations of the first embodiment in the related arts are explained.
When the liquid crystal driver IC 208 applies an analog signal voltage to the signal wires 205 on the basis of input digital image data, in synchronization with that, the gate wire driver IC 207 selects prescribed gate wires 204 and turns on the pixel switches 202 in corresponding rows. Thereby, the analog signal voltage which the liquid crystal driver IC 208 has output is written in the liquid crystal capacitors 201 of the selected pixels and an optical image is displayed.
By such a related art, it is possible to display an image on the basis of input digital image data and the related art is now widely used for a liquid crystal display using the amorphous silicon TFTs.
In the meantime, a technology on a liquid crystal display using polycrystalline silicon TFTs which is different from the aforementioned technology is also known well. The structure of such a second embodiment in the related arts is hereunder explained with FIG. 13.
FIG. 13 is a circuit configuration diagram of a liquid crystal display showing the second embodiment in the related arts. Each of the pixels constituting a display screen 203 includes a pixel switch 202 and a liquid crystal capacitor 201, and counter electrodes of the liquid crystal capacitors 201 are connected commonly to each other. The gate of each pixel switch 202 is connected to a vertical scanning circuit 210 via a gate wire 204 and the other terminal of each pixel switch 202 is connected to a DA converter circuit 211 via a signal wire 205.
Here, the display screen 203, the gate wires 204, the signal wires 205, the vertical scanning circuit 210, and the DA converter circuit 211 are formed on a glass substrate 206. Then polycrystalline silicon TFTs are used as a pixel switch 202 which is an active element and the constituent elements of the vertical scanning circuit 210 and the DA converter circuit 211.
Next, operations of the second embodiment in the related arts are explained.
When the DA converter circuit 211 applies an analog signal voltage to the signal wires 205 on the basis of input digital image data, in synchronization with that, the vertical scanning circuit 210 selects prescribed gate wires 204 and turns on the pixel switches 202 in corresponding rows. Thereby, the analog signal voltage which the DA converter circuit 211 has output is written in the liquid crystal capacitors 201 of the selected pixels and an optical image is displayed.
By such a second related art, it is possible to display an image on the basis of input digital image data and details of such a related art are described in JP-A No. 005716/2003 for example.