Electronic circuit, optoelectronic device, method for driving optoelectronic device, and electronic apparatus

• US 8,094,144 B2
• Filed: 10/30/2007
• Issued: 01/10/2012
• Est. Priority Date: 05/31/2002
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Miyazawa, Takashi
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US11/978,620
• Publication Number:
  US 20080068361A1
• Time in Patent Office: 1,533 Days
• Field of Search: 345 87-100, 345 82- 84, 345204-215
• US Class Current: 345/207
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver

Abstract

An electronic circuit, an electronic device, and an electronic apparatus are provided that are capable of display with good quality and reducing operation delay, and a method to drive the electronic circuit. First and second switching transistors are turned on and an operation voltage Vdx and a data-current Idata are transmitted to a holding capacitor. The conduction state of a driving transistor is set according to an electrical-charge amount corresponding to the data-current Idata held in the holding capacitor and a current that passes the driving transistor is transmitted to an organic EL element. Then, a first switch is turned off, a second switch and the second switching transistor are turned on, and a reset voltage Vr is transmitted to the holding capacitor, whereby the driving transistor is turned off and the organic EL element stops emitting light.

Claims

1. An electro-optical device, comprising:

a first scanning line;

a second scanning line;

a data line;

a scanning line driving circuit that outputs a first scanning signal through the first scanning line and outputs a second scanning signal through the second scanning line;

a data line driving circuit that outputs a data signal and a reset signal through the data line; and

a pixel circuit arranged at an intersection of the first scanning line and the data line, the pixel circuit including;

an electro-optical element;

a holding element that holds a voltage that corresponds to the data signal and the reset signal that are output to the data line;

a first switching transistor connected between the data line and the holding element that outputs the data signal to the holding element, based on the first scanning signal;

a second switching transistor connected between the data line and the holding element that outputs the reset signal to the holding element, based on the second scanning signal; and

a driving transistor that outputs a driving current to the electro-optical element, based on the voltage held by the holding element,

the data signal being a signal by which the driving transistor is placed in a driving state, the data signal corresponding to a gradation and being output to the holding element through the data line in a period in which the first scanning signal is output,

the reset signal being a signal by which the driving transistor is placed in an off state, the reset signal being output to the holding element through the data line in a period in which the second scanning signal is output, and

the second scanning signal being output from the period in which the first scanning signal is output until a following first scanning signal is output.

2. A method of driving an electro-optical device, the electro-optical device including a scanning line;

a data line;

a scanning line driving circuit that outputs a scanning signal through the scanning line;

a data line driving circuit that outputs a data signal and a reset signal through the data line; and

a pixel circuit that is arranged at an intersection of the scanning line and the data line, the pixel circuit including a switching transistor, a holding element, a driving transistor, and an electro-optical element, the method comprising;

outputting the scanning signal to the scanning line from the scanning line driving circuit;

outputting the data signal to the data line from the data line driving circuit in a period in which the scanning signal is output;

outputting, by the switching transistor, the data signal to the holding element based on the scanning signal, the switching transistor connected between the data line and the holding element;

holding, by the holding element, a voltage that corresponds to the data signal;

outputting, by the driving transistor, a driving current to the electro-optical element, based on the voltage that corresponds to the data signal held by the holding element;

suspending output of the scanning signal to the scanning line;

outputting the reset signal to the data line from the data line driving circuit until a following scanning signal is output; and

holding, by the holding element, a voltage that corresponds to the reset signal, the reset signal being a signal by which the driving transistor is placed in an off state.

3. An electro-optical device, comprising:

a scanning line;

a data line;

a scanning line driving circuit that outputs a scanning signal through the scanning line; and

a data line driving circuit that outputs a data signal and a reset signal through the data line; and

a pixel circuit that is arranged at an intersection of the scanning line and the data line, the pixel circuit including;

an electro-optical element;

a holding element that holds a voltage that corresponds to the data signal and the reset signal that are output to the data line;

a switching transistor connected between the data line and the holding element and outputting the data signal to the holding element, based on the scanning signal; and

a driving transistor that outputs a driving current to the electro-optical element, based on the voltage held by the holding element,

the data signal being a signal by which the driving transistor is placed in a driving state, the data signal corresponding to a gradation and being output to the holding element through the data line in a period in which the scanning signal is output, and

the reset signal being a signal by which the driving transistor is placed in an off state, the reset signal being output to the holding element through the data line from the period in which the scanning signal is output until a following scanning signal is output.

4. The electro-optical device as set forth in claim 3, the data line driving circuit including a current generation circuit and a voltage generation circuit;

the data signal being output as a current signal from the current generation circuit through the data line; and

the reset signal being output as a voltage signal from the voltage generation circuit through the data line.

5. The electro-optical device as set forth in claim 3, further comprising:

a driving voltage source, one of a source or a drain of the driving transistor being connected to the driving voltage source; and

the holding element being connected between a gate of the driving transistor and the driving voltage source.