DISPLAY APPARATUS AND DRIVING METHOD OF DISPLAY APPARATUS

• US 20140320549A1
• Filed: 04/16/2014
• Published: 10/30/2014
• Est. Priority Date: 04/25/2013
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: KUMETA, Masayuki, OKUNO, Takeshi, KANDA, Eiji, ISHII, Ryo, KOMIYA, Naoaki
• Granted Patent: US 9,514,674 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2300/0847 being a dynamic memory without any storage capacitor, i.e. with use of parasitic capacitances as storage elements
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3225 using an active matrix

Abstract

A display device includes a driving transistor in a pixel circuit. A signal line is connected to a source or drain of the driving transistor. The source or drain of the driving transistor receives a power source voltage, an initialization voltage, and a data voltage through the signal line during different periods of operation. The periods of operation include a emission and non-emission periods.

Claims

1. A display apparatus, comprising:

a first P-type transistor configured to control an amount of current of a light emitting diode, one of source or drain terminals of the first P-type transistor being connected to an anode of the light emitting diode;

a first control line connected to the other of the source or drain terminals of the first P-type transistor, the first control line to supply a gray scale data voltage to set a gate voltage of the first P-type transistor, an initialization voltage to initialize a gate voltage of the first P-type transistor, and an anode voltage for light emission of the light emitting diode;

a second P-type transistor configured to selectively connect the one terminal of the first P-type transistor and a gate terminal of the first P-type transistor;

a second control line to supply different levels of voltages; and

a capacitive element having a first electrode connected to the gate terminal of the first P-type transistor and a second electrode connected to the second control line.

2. The display apparatus as claimed in claim 1, further comprising:

a control circuit to;

set the light emitting diode to a non-light emitting state by controlling the cathode voltage of the light emitting diode during a non-light emitting period of the light emitting diode, the non-light emitting period including an initialization period of the gate voltage and a data program period following the initialization period,

supply the initialization voltage to the first control line and supply a second voltage higher than a first voltage to the second control line after the first voltage is supplied to the second control line during the initialization period, the control circuit turning the P-type second transistor on,

supply the gray scale voltage to the first control line and turn the second P-type transistor on when a gate voltage of the first P-type transistor is set to the gray scale voltage during the program period, and

turn off the second transistor, control the cathode voltage of the light emitting diode to set the light emitting diode to a light emitting state and control an operation of supplying the anode voltage to the first control line during a light emitting period of the light emitting diode.

3. The display apparatus as claimed in claim 2, wherein:

a compensation voltage between the initialization voltage and the gray scale data voltage is further supplied to the first control line,

during a compensation period between the initialization period and the data program period, the control circuit is to turn the second P-type transistor on and is to supply the compensation voltage to the first control line.

4. A display apparatus, comprising:

a first N-type transistor configured to control an amount of current of a light emitting diode, one of source or drain terminals of the first N-type transistor being connected to a cathode of the light emitting diode;

a first control line connected to the other of the source or drain terminals of the first N-type transistor and to supply a gray scale data voltage to set a gate voltage of the first N-type transistor, an initialization voltage to initialize a gate voltage of the first N-type transistor, and a cathode voltage for light emission of the light emitting diode;

a second N-type transistor configured to selectively connect the one terminal of the first N-type transistor and a gate terminal of the first N-type transistor;

a second control line to supply two levels of voltages; and

a capacitive element having a first electrode connected to the gate terminal of the first N-type transistor and a second electrode connected to the second control line.

5. The display apparatus as claimed in claim 4, further comprising:

a control circuit to;

control the light emitting diode to a non-light emitting state by controlling an anode voltage of the light emitting diode during a non-light emitting period of the light emitting diode, the non-light emitting period including an initialization period of the gate voltage and a data program period following the initialization period,

turn the second N-type transistor on, supply the initialization voltage to the first control line, and supply a second voltage higher than a first voltage to the second control line after the first voltage is supplied to the second control line during the initialization period,

supply the gray scale voltage to the first control line and turn the second transistor on when a gate voltage of the first N-type transistor is set to the gray scale voltage during the program period, and

turn the second N-type transistor off, control the anode voltage of the light emitting diode to set the light emitting diode to a light emitting state, and control an operation of supplying the cathode voltage to the first control line during a light emitting period of the light emitting diode.

6. The display apparatus as claimed in claim 5, wherein:

a compensation voltage between the initialization voltage and the gray scale data voltage is supplied to the first control line,

the control circuit turns the second N-type transistor on and supplies the compensation voltage to the first control line during a compensation period between the initialization period and the data program period.

7. A method of driving a display apparatus, the method comprising:

setting a light emitting diode to a non-light emitting state by controlling a cathode voltage of the light emitting diode during a non-light emitting period, the non-light emitting period including an initialization period of a gate voltage of a first transistor and a data program period following the initialization period;

turning on a second P-type transistor during the initialization period, supplying an initialization voltage to a first control line and a second voltage higher than a first voltage a second control line after the first voltage is supplied to the second control line;

supplying a gray scale voltage to the first control line and turning on the second transistor on when a gate voltage of the first transistor is set to the gray scale voltage during the data program period; and

turning off the second transistor and controlling the cathode voltage of the light emitting diode to set the light emitting diode a light emitting state, and supplying the anode voltage to the first control line during a light emitting period.

8. The method as claimed in claim 7, further comprising:

supplying a compensation voltage to the first control line, the compensation voltage being between the initialization and gray scale data voltage, and

turning on the second transistor and supplying the compensation voltage to the first control line during a compensation period between the initialization period and the data program period.

9. A method of driving a display apparatus, the method comprising:

setting a light emitting diode to a non-light emitting state by controlling the anode voltage of the light emitting diode during a non-light emitting period, the non-light emitting period including an initialization period of a gate voltage of a first transistor and a data program period following the initialization period;

turning on a second transistor, supplying an initialization voltage to a first control line, and supplying a second voltage higher than a first voltage to a second control line after the first voltage is supplied to the second control line during the initialization period;

supplying a gray scale voltage to the first control line and turning on the second transistor when a gate voltage of the first transistor is set to the gray scale voltage during the data program period; and

turning off the second transistor, controlling the anode voltage of the light emitting diode to set the light emitting diode to a light emitting state, and supplying the cathode voltage to the first control line during a light emitting period.

10. The method as claimed in claim 9, further comprising:

supplying a compensation voltage to the first control line, the compensation voltage being between the initialization and gray scale data voltages, and

turning on the second transistor and supplying the compensation voltage to the first control line during a compensation period between the initialization period and the data program period.

11. An apparatus, comprising:

a pixel circuit;

a driving transistor in the pixel circuit; and

a signal line connected to a source or drain of the driving transistor,

wherein the source or drain of the driving transistor receives a power source voltage, an initialization voltage, and a data voltage through the signal line during different periods of operation.

12. The apparatus as claimed in claim 11, wherein:

the initialization voltage and data voltage are received through the signal line during a non-light-emission period, and

the power source voltage is received during a light-emission period.

13. The apparatus as claimed in claim 11, further comprising:

a switching transistor coupled to a gate of the driving transistor,

wherein the switching transistor is to place the driving transistor in a diode-connected state during a non-light-emission period based on a scan signal.

14. The apparatus as claimed in claim 13, wherein the driving transistor and the switching transistor are the only transistors in the pixel circuit.

15. The apparatus as claimed in claim 13, further comprising:

a capacitor connected to the gate of the driving transistor,

wherein the switching transistor is connected to the gate of the driving transistor at a location between the gate of the driving transistor and the capacitor.

16. The apparatus as claimed in claim 15, wherein the capacitor receives the data voltage along a data path which passes through the driving transistor and the switching transistor.

17. The apparatus as claimed in claim 11, wherein the source or drain of the driving transistor receives a compensation voltage through the signal line during a compensation period.

18. The apparatus as claimed in claim 17, wherein the compensation voltage is between the power source voltage and the initialization voltage.

19. The apparatus as claimed in claim 18, wherein the compensation voltage is less than the data voltage.

20. The apparatus as claimed in claim 17, wherein the compensation period is between an initialization period and a data program period of non-light-emission period.