Display Apparatus and Driving Method Therefor

• US 20090091562A1
• Filed: 11/28/2007
• Published: 04/09/2009
• Est. Priority Date: 01/15/2007
• Status: Active Grant

• Current Assignee: JDI Design and Development GK
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamamoto, Tetsuro, Uchino, Katsuhide
• Granted Patent: US 7,903,057 B2
• Time in Patent Office: Days
• US Class Current: 345/214
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A sampling transistor T1 is brought into conduction in accordance with a control signal supplied from a scanning line WS, and writes to a holding capacitor C1 a video signal supplied from a signal line SL. A driving transistor T2 outputs a driving current to an output node S in accordance with a signal potential of the video signal written to the holding capacitor C1. A switching transistor T3 is arranged between the output node S and a light-emitting device EL. In a predetermined light-emission period, the switching transistor T3 is in an on-state, and supplies the driving current to the light-emitting device EL to cause the light-emitting device EL to emit light at a brightness corresponding to the video signal. In contrast, in a non-light-emission period, the switching transistor T3 is turned off to disconnect the light-emitting device EL from the output node S, so that a potential generated at the output node S due to an operation of a pixel 2 performed in the non-light-emission period is prevented from being applied as a reverse-bias voltage to the light-emitting device EL of a diode type.

Claims

1. A display apparatus characterized by comprising scanning lines in rows, signal lines in columns, and pixels arranged in a matrix in portions where the scanning lines and the signal lines intersect with each other,

wherein the pixels each include at least a sampling transistor, a driving transistor having an input node and an output node, a switching transistor, a light-emitting device, a holding capacitor, and an auxiliary capacitor,

wherein the sampling transistor is arranged between the signal line and the input node, is brought into conduction in accordance with a control signal supplied from the scanning line, and writes to the holding capacitor a video signal supplied from the signal line,

wherein the driving transistor outputs a driving current to the output node in accordance with a signal potential of the video signal written to the holding capacitor,

wherein the holding capacitor is arranged between the input node and the output node,

wherein the auxiliary capacitor is connected to the output node, and

wherein the switching transistor is arranged between the output node and the light-emitting device, and in a predetermined light-emission period, the switching transistor is in an on-state and supplies the driving current to the light-emitting device to cause the light-emitting device to emit light at a brightness corresponding to the video signal, whereas in a non-light-emission period, the switching transistor is turned off to disconnect the light-emitting device from the output node, so that a potential generated at the output node due to an operation of the pixel performed in the non-light-emission period is prevented from being applied as a reverse-bias voltage to the light-emitting device of a diode type.

2. The display apparatus according to claim 1, characterized in that:

a gate of the driving transistor is connected to the input node, a drain of the driving transistor is connected to a power supply line, and a source of the driving transistor is connected to the output node;

an anode of the light-emitting device is connected to the output node with the switching transistor therebetween, and a cathode of the light-emitting device is connected to a ground line; and

the auxiliary capacitor is connected between the output node and the ground line.

3. The display apparatus according to claim 1, characterized in that:

the pixels each include threshold-voltage correction means; and

the threshold-voltage correction means operates in the non-light-emission period, and in a state where a potential exceeding the reverse-bias voltage is applied to the output node, the threshold-voltage correction means causes a voltage corresponding to a threshold voltage of the driving transistor to be held in the holding capacitor between the input node and the output node.

4. The display apparatus according to claim 1, characterized in that the pixels each include mobility correction means, the mobility correction means operates when the video signal is being written in the non-light-emission period, and in a state where electricity exceeding the reverse-bias voltage is applied to the output node, the mobility correction means negatively feeds back the driving current from the output node to the holding capacitor, thereby applying correction corresponding to a mobility of the driving transistor.

5. A driving method for a display apparatus including scanning lines in rows, signal lines in columns, and pixels arranged in a matrix in portions where the scanning lines and the signal lines intersect with each other,

wherein the pixels each include at least a sampling transistor, a driving transistor having an input node and an output node, a switching transistor, a light-emitting device, a holding capacitor, and an auxiliary capacitor,

wherein the sampling transistor is arranged between the signal line and the input node,

wherein the switching transistor is arranged between the output node and the light-emitting device,

wherein the holding capacitor is arranged between the input node and the output node, and

wherein the auxiliary capacitor is connected to the output node, the driving method being characterized in that:

the sampling transistor is brought into conduction in accordance with a control signal supplied from the scanning line, and writes to the holding capacitor a video signal supplied from the signal line;

the driving transistor outputs a driving current to the output node in accordance with a signal potential of the video signal written to the holding capacitor; and

in a predetermined light-emission period, the switching transistor is in an on-state and supplies the driving current to the light-emitting device to cause the light-emitting device to emit light at a brightness corresponding to the video signal, whereas in a non-light-emission period, the switching transistor is turned off to disconnect the light-emitting device from the output node, so that a potential generated at the output node due to an operation of the pixel performed in the non-light-emission period is prevented from being applied as a reverse-bias voltage to the light-emitting device of a diode type.