OLED active matrix using a single transistor current mode pixel design

• US 6,023,259 A
• Filed: 03/13/1998
• Issued: 02/08/2000
• Est. Priority Date: 07/11/1997
• Status: Expired due to Term

• Current Assignee: eMagin Corporation (Samsung Electronics Co. Ltd.)
• Original Assignee: Fed Corp. (Samsung Electronics Co. Ltd.)
• Inventors: Prache, Olivier, Howard, Webster E.
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): LEWIS, DAVID LEE
• Application Number:
  US09/041,637
• Time in Patent Office: 697 Days
• Field of Search: 345/76, 345/77, 345/78, 345/79, 345/80
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• 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 2330/025 Reduction of instantaneous peaks of current
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• 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 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 71/841 Applying alternating current [AC] during manufacturing or treatment

Abstract

The present invention is a current driver for an active matrix organic light emitting device display. As embodied herein, the driver relies upon a single transistor, driven in a saturation regime to provide a current source for an OLED. This results in a pulse drive. The driver of the present invention is compatible with high speed integrated drivers and can be fabricated on the same substrate as the OLED. A technique for driving an OLED is disclosed that will produce a good quality gray scale image.

Claims

1. A organic light emitting device control circuit comprising:

an organic light emitting device having a first end and a second end; and

a driver connected to said organic light emitting device, said driver being operated in a current mode, wherein said driver comprises a voltage source connected to said first end of said organic light emitting device, wherein said voltage source supplies voltage to said organic light emitting device, and a transistor having a drain terminal, a source electrode, and a gate terminal, wherein said drain terminal of said transistor is connected to said second end of said organic light emitting device, wherein said gate terminal and said source electrode control the delivery of current to said organic light emitting device through said drain terminal.

2. The control circuit according to claim 1, wherein control data information for operating said control circuit is supplied to said control circuit through said at least one electrode.

3. The control circuit according to claim 1, wherein said voltage source supplies a sufficient voltage such that said transistor, when selected, is in saturation.

4. The control circuit according to claim 1, wherein said organic light emitting device is driven in pulses of current.

5. The control circuit according to claim 4, wherein the pulses are modulated by said driver to control the intensity of the at least one organic light emitting device.

6. The current driver according to 1, wherein the delivery of current is modulated to produce gray scale levels.

7. A current driver for controlling a display device in a current mode in response to data information, wherein the display device comprising at least one pixel having at least one organic light emitting device having a first end and a second end, said current driver comprising:

a voltage source connected to the first end of the at least one organic light emitting device, wherein said voltage source supplies voltage to the at least one organic light emitting device; and

a transistor having a drain terminal, a source electrode and a gate terminal, wherein said drain terminal of said transistor is connected to the second end of the at least one organic light emitting device, wherein said gate terminal, and said source electrode receive the data information and control the delivery of current to the at least one organic light emitting device through said drain terminal.

8. The current driver according to claim 7, wherein the at least one pixel comprises a plurality of pixels arranged in an array.

9. The current driver according to claim 8, wherein the plurality of pixels are arranged in at least one row and at least one column, wherein the pixels disposed in the same row are connected to the same source electrode, and the pixels disposed in the same column are connected to the same gate terminal.

10. The current driver according to 7, wherein the delivery of current is modulated to produce gray scale levels.