Driving circuit for current programmed organic light-emitting diode displays

• US 10,078,984 B2
• Filed: 02/09/2006
• Issued: 09/18/2018
• Est. Priority Date: 02/10/2005
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): LAM, NELSON C
• Application Number:
  US11/350,610
• Publication Number:
  US 20060208961A1
• Time in Patent Office: 4,604 Days
• Field of Search: 345 44, 345 76- 83, 3151693
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• 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 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A load driving circuit for a load having a parasitic capacitance associated therewith is provided. The load being current programmed. The driving circuit has a data line having a voltage controlling the load, a feedback loop having a lowpass filter for monitoring the voltage of the data line; and a current source for providing a current to the data line; the current source being controlled by a signal line and an output from the lowpass filter.

Claims

1. A driving circuit for improving a settling time of current for a current programmed pixel, the current programmed pixel having a light emitting device, the light emitting device being current programmed, the driving circuit comprising:

a data line coupled to the current programmed pixel, for controlling the light emitting device;

a programmable current source for providing via the data line programming current to the current programmed pixel during a programming cycle; and

a positive feedback loop coupled to the data line including;

a first capacitor directly coupled to a node, the first capacitor acting as a low pass filter to mitigate high frequency noise, a node voltage of the node following a voltage of the data line;

a second capacitor directly coupled to the node, the second capacitor differentiating the node voltage generating a first current; and

a current mirror coupled to the node, the current mirror duplicating the first current and adding the duplicated first current to the programming current.

2. A driving circuit for improving a settling time of current for a current programmed pixel having a light emitting device, the light emitting device being current programmed, the driving circuit comprising:

a data line coupled to the current programmed pixel, for controlling the light emitting device;

a capacitor directly coupled to a node, a node voltage of the node following a voltage of the data line, the capacitor differentiating the node voltage generating a first current;

a programmable current source for providing via the data line programming current to the current programmed pixel during a programming cycle; and

a current mirror coupled to the node, the current mirror duplicating the first current and adding the duplicated first current to the programming current.

3. The driving circuit according to claim 2 wherein the light emitting device is an organic light emitting diode.

4. The driving circuit according to claim 2, wherein an illumination of the light emitting device is responsive to the programming current provided by the data line.

5. The driving circuit according to claim 2, wherein the light emitting device is controlled by a thin film transistor.

6. A display having an array of pixels each including an organic light emitting diode driven by the driving circuit according to claim 2.

7. A method of improving a settling time of current for a current programmed pixel having a light emitting device in a display, the light emitting device being current programmed, the method comprising steps of:

providing, during a programming cycle from a programmable current source, programming current via a data line to a current-programmed pixel;

in a positive feedback loop, differentiating a node voltage of a node generating a first current, the node voltage following a voltage of the data line;

low pass filtering the node voltage; and

duplicating the first current and adding the duplicated first current to the programming current.

8. The method according to claim 7, wherein the light emitting device is an organic light emitting diode.