Image display device and method of driving the same

1. An image display device having a display portion formed by disposing pixel circuits in a matrix, and a signal line driving circuit and a scanning line driving circuit for driving said pixel circuits through signal lines and scanning lines of said display portion, said pixel circuit comprising:

a light emitting element;

a drive transistor for current-driving said light emitting element;

a hold capacitor; and

a write transistor adapted to be turned ON/OFF in accordance with a write signal outputted from said scanning line driving circuit, for setting a voltage developed across terminals of said hold capacitor at a voltage of corresponding one of said signal line;

wherein said signal line driving circuit alternately outputs a signal voltage, and a fixed voltage,

wherein an amplitude of the write signal is increased as compared with a case where the voltage developed across said terminals of said hold capacitor is set at the signal voltage, to turn OFF said write transistor, for making the voltage developed across said terminals of said hold capacitor variable from the fixed voltage.

2. The image display device according to claim 1 , wherein said signal line driving circuit comprises:

a first switch circuit, on a side of the signal voltage for gradation setting, configured to operate so as to be turned ON/OFF in accordance with a first control signal on a side of the voltage for gradation setting, for outputting the signal voltage for gradation setting to the corresponding one of said signal lines; and

a second switch circuit, on a side of the fixed voltage, configured to operate so as to be turned ON/OFF in accordance with a second control signal on aside of the fixed voltage, for outputting the fixed voltage to the corresponding one of said signal lines.

3. The image display device according to claim 2 , wherein said second switch circuit is composed of a P-channel transistor and an N-channel transistor which operate so as to be turned ON/OFF in accordance with the second control signal; and a gate area of said N-channel transistor is set so as to be larger than that of said P-channel transistor.

4. The image display device according to claim 2 , wherein said first switch circuit is composed of a P-channel transistor and an N-channel transistor which operate so as to be turned ON/OFF in accordance with the first control signal; said second switch circuit is composed of a P-channel transistor and an N-channel transistor which operate so as to be turned ON/OFF in accordance with the second control signal; and a ratio of a gate area of said N-channel transistor to a gate area of said P-channel transistor in said second switch circuit is set so as to be larger than that of a gate area of said N-channel transistor to a gate area of said P-channel transistor in said first switch circuit.

5. The image display device according to claim 2 , wherein said second switch circuit is composed of an N-channel transistor which operates so as to be turned ON/OFF in accordance with the first control signal; said second switch circuit is composed of an N-channel transistor which operates so as to be turned ON/OFF in accordance with the second control signal; and a gate area of said N-channel transistor in said second switch circuit is set so as to be larger than that of said N-channel transistor in said first switch circuit.

6. The image display device according to claim 2 , wherein said second switch circuit is composed of a P-channel transistor and an N-channel transistor which operate so as to be turned ON/OFF in accordance with the second control signal; and an amplitude of the second control signal in accordance with which said N-channel transistor is controlled so as to be turned ON/OFF is set so as to be larger than that of the second control signal in accordance with which said P-channel transistor is controlled so as to be turned ON/OFF.

7. The image display device according to claim 2 , wherein said first switch circuit is composed of a P-channel transistor and an N-channel transistor which operate so as to be turned ON/OFF in accordance with the first control signal; said second switch circuit is composed of a P-channel transistor and an N-channel transistor which operate so as to be turned ON/OFF in accordance with the second control signal; and a ratio of an amplitude of the second control signal in accordance with which said N-channel transistor is turned ON/OFF to an amplitude of the second control signal in accordance with which said P-channel transistor is turned ON/OFF in said second switch circuit is set so as to be larger than that of an amplitude of the first control signal in accordance with which said N-channel transistor is turned ON/OFF to an amplitude of the first control signal in accordance with which said P-channel transistor is turned ON/OFF in said first switch circuit.

8. The image display device according to claim 2 , wherein said first switch circuit is composed of an N-channel transistor which operates so as to be turned ON/OFF in accordance with the first control signal; said second switch circuit is composed of an N-channel transistor which operates so as to be turned ON/OFF in accordance with the second control signal; and an amplitude of the second control signal in accordance with which said N-channel transistor in said second switch circuit is turned ON/OFF is set so as to be larger than that of the first control signal in accordance with which said N-channel transistor in said first switch circuit is turned ON/OFF.