Image display device
An object of the present invention is to provide an image display device that is capable of displaying an image with high brightness and low power. The above object is achieved by controlling, by use of a common switch control line 9 , a pair of switching means 7, 8 for alternatively selecting and inputting one of the video signal voltage from a signal line DAT and the pixel driving voltage from a signal line SWP.
1 . An image display device comprising:
means for generating a video signal voltage;
means for generating a pixel driving voltage;
a pixel that includes a light emitting element whose brightness is controlled by the potential difference between the video signal voltage and the pixel driving voltage, and control means for controlling the brightness of the light emitting element; and
a display unit on which a plurality of pixels are arranged;
wherein:
the pixel includes a pair of switching means for alternatively selecting and inputting one of the video signal voltage and the pixel driving voltage; and
the pair of switching means have a structure that is controlled by a common switch control line.
2 . The image display device according to claim 1 , wherein the light emitting element is an organic EL element.
3 . The image display device according to claim 1 , wherein the pair of switching means are polycrystalline Si-TFTs.
4 . The image display device according to claim 1 , wherein the pixel is formed on an insulating substrate.
5 . The image display device according to claim 1 , wherein:
the brightness control means that is formed on each pixel includes:
a capacitance, one end of which has the pair of switching means;
a drive TFT whose gate is connected to the other end of the capacitance;
a power line that is connected to one end of a source-drain path of the drive TFT; and
a reset TFT that is connected to the light emitting element that is connected to the other end of the source-drain path of the drive TFT, and that is connected to a point between a gate of the drive TFT and the other end of the source-drain path of the drive TFT.
6 . The image display device according to claim 5 , wherein the reset TFT is an n-type TFT.
7 . The image display device according to claim 5 , wherein a plurality of the reset TFTs are serially connected.
8 . The image display device according to claim 1 , wherein:
the pair of switching means that are formed on each pixel includes a p-type TFT for inputting the video signal voltage, and an n-type TFT for inputting the pixel driving voltage; and
when the switch control line is switched, the pixel driving voltage generation means sets the pixel driving voltage to a voltage higher than or equal to the video signal voltage.
9 . The image display device according to claim 8 , wherein both of the TFTs that constitute the pair of switching means are enhancement type TFTs.
10 . The image display device according to claim 1 , wherein:
the pair of switching means that are formed on each pixel includes an n-type TFT for inputting the video signal voltage, and a p-type TFT for inputting the pixel driving voltage; and
when the switch control line is switched, the pixel driving voltage generation means sets the pixel driving voltage to a voltage lower than or equal to the video signal voltage.
11 . The image display device according to claim 10 , wherein both of the TFTs that constitute the pair of switching means are enhancement type TFTs.
12 . The image display device according to claim 1 , wherein the pixel driving voltage has a substantially triangular wave form.
13 . The image display device according to claim 1 , wherein a phase of a wave form of the pixel driving voltage differs for each pixel row that is parallel to the switch control line.
14 . The image display device according to claim 1 , wherein when switching is performed by the selected switch control line, the pixel driving voltage input in a pixel through the switch control line is constant.
15 . The image display device according to claim 1 , wherein the pixel driving voltage is always constant.
16 . The image display device according to claim 1 , wherein the video signal voltage generation means is formed of a monocrystal Si-IC.
17 . An image display device comprising:
means for storing a video signal;
means for generating a power-supply voltage;
means for generating a video signal voltage;
means for generating a pixel driving voltage;
a pixel that includes a light emitting element whose brightness is controlled by the potential difference between the video signal voltage and the pixel driving voltage, and control means for controlling the brightness of the light emitting element; and
a display unit on which a plurality of pixels are arranged;
wherein:
the pixel includes a pair of switching means for alternatively selecting and inputting one of the video signal voltage and the pixel driving voltage; and
the pair of switching means have a structure that is controlled by a common switch control line.