Organic electroluminescent display device driving method and apparatus

• US 20030076048A1
• Filed: 10/22/2002
• Published: 04/24/2003
• Est. Priority Date: 10/23/2001
• Status: Active Grant

• Current Assignee: James C. Rutherford
• Original Assignee: James C. Rutherford
• Inventors: Rutherford, James C.
• Granted Patent: US 6,861,810 B2
• Time in Patent Office: Days
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• 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 2300/088 using a non-linear two-terminal element
• CPC Class Codes: G09G 2310/0221 with use of split matrices G09G3/3644 and G09G3/3666 take precedence
• CPC Class Codes: G09G 2310/0259 with use of an analog or digital ramp generator in the column driver or in the pixel circuit
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• 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 3/3266 Details of drivers for scan electrodes
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels

Abstract

The object of the invention is to provide an organic electroluminescent display device and driving method including an apparatus comprised of at least one organic-light-emitting diode (OLED), a rectification diode and a capacitor used as a memory device. A frame period of the display device is divided into sub-frames, which have address and light emission periods. Current mode data programming is used to address the display device in each sub-frame. In the light emission period, charge previously stored in selected capacitors during the address period, supplies the forward current for the OLEDs. A ramp waveform applied to the row electrode, during the light emission period, forces the capacitor to discharge through the OLED and controls the forward current level. The operation of the OLEDs are retained in their area of maximum performance.

Claims

1. An organic electroluminescent display device including a matrix of light-emitting apparatus wherein each light-emitting apparatus comprises:

an organic light-emitting diode, a rectification diode and a memory capacitor electrically connected together, and wherein light is produced by discharging said capacitor through said organic light-emitting diode.

2. The organic electroluminescent display device of claim 1 wherein, in each light-emitting apparatus, the capacitor is charged during an addressing period and is discharged during a light output period.

3. The organic electroluminescent display device of claim 2 wherein a ramp voltage is applied to said light-emitting apparatus for causing the discharge of said capacitor through said light-emitting diode and producing light.

4. The organic electroluminescent display device of claim 3 wherein pulse width modulation is used for controlling the charge on said capacitor during the addressing period.

5. The organic electroluminescent display device of claim 4 further comprising a current limiting device in series with said light-emitting diode.

6. The organic electroluminescent display device of claim 1 wherein a ramp voltage is applied to said light-emitting apparatus for causing the discharge of said capacitor through said light-emitting diode and producing light.

7. The organic electroluminescent display device of claim 1 wherein said capacitor is charged during an addressing period with pulse width modulation.

8. The organic electroluminescent display device of claim 1 further comprising a current limiting device in series with said light-emitting diode.

9. An organic light-emitting diode active driving system comprising:

a matrix of elements arrayed in a plurality of rows and columns, wherein each element is comprised of a organic LED, a rectifier diode and a capacitor all having one side electrically connected;

metal row electrodes electrically connected to each elements capacitor;

metal column electrodes electrically connected to each elements rectifier diode;

current mode data programming column driver ICs;

row driver ICs; and

,

a transparent front electrode electrically connected to each elements organic LED.

10. An organic light-emitting diode active driving system comprising:

a matrix of elements arrayed in a plurality of rows and columns, wherein an element is comprised of a organic LED, a rectifier diode, a current limiting device, and a capacitor;

a current limiting device with one side electrically connected to the organic LED and the other side electrically connected to the junction of the rectifier diode and the capacitor;

metal row electrodes electrically connected to each elements capacitor;

metal column electrode electrically connected to each elements rectifier diode;

current mode data programming column driver ICs;

row driver ICs; and

,

a transparent front electrode electrically connected to each elements organic LED.