Organic light emitting diode array drive apparatus

• US 5,719,589 A
• Filed: 01/11/1996
• Issued: 02/17/1998
• Est. Priority Date: 01/11/1996
• Status: Expired due to Term

• Current Assignee: Universal Display Corporation
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Williamson, Warren L., Norman, Michael P., Rhyne, George W.
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US08/584,827
• Time in Patent Office: 768 Days
• Field of Search: 345/44, 345/46, 345/82, 345/83, 345/206, 345/208, 345/209
• US Class Current: 345/82
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• 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 3/3216 using a passive matrix
• 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

Abstract

Drive apparatus for an array of organic LEDs including first switches connectable between a current source or a rest potential, second switches connectable to a power source, an array of LEDs with each LED having a first contact connected to one of the first switches and a second contact connected to one of the second switches, and control apparatus connecting selected switches of the first switches to the current source while retaining all remaining switches of the first switches connected to the rest potential, and periodically connecting selected switches of the second switches, one at a time, to the power source to generate a desired image on the array.

Claims

1. Drive apparatus for an array of light emitting diodes comprising:

a first plurality of switches each connectable between one of a current source and a rest potential;

a second plurality of switches each connectable to a power source;

an array including a plurality of light emitting diodes connected into rows of light emitting diodes and columns of light emitting diodes, each light emitting diode having a first contact connected to one of the first plurality of switches and a second contact connected to one of the second plurality of switches; and

control apparatus connected to the first and second pluralities of switches for connecting selected switches of the first plurality of switches to the current source while retaining all remaining switches of the first plurality of switches connected to the rest potential, and connecting selected switches of the second plurality of switches to the power source.

2. Drive apparatus for an array of light emitting diodes as claimed in claim 1 wherein the control apparatus includes circuitry for periodically connecting each switch of the second plurality of switches, one at a time, to the power source while retaining all remaining switches of the second plurality of switches connected to a row rest potential.

3. Drive apparatus for an array of light emitting diodes as claimed in claim 2 wherein the circuitry for periodically connecting each switch of the second plurality of switches includes a shift register.

4. Drive apparatus for an array of light emitting diodes as claimed in claim 1 wherein the first and second pluralities of switches include semiconductor switches.

5. Drive apparatus for an array of light emitting diodes as claimed in claim 1 wherein the plurality of light emitting diodes include organic light emitting diodes.

6. Drive apparatus for an array of light emitting diodes as claimed in claim 5 wherein the organic light emitting diodes each include one electrical contact formed of a transparent conductive material.

7. Drive apparatus for an array of light emitting diodes as claimed in claim 6 wherein the plurality of organic light emitting diodes are positioned on a transparent substrate with the transparent conductive material being formed into a plurality of columns on the surface of the substrate.

8. Drive apparatus for an array of light emitting diodes as claimed in claim 7 wherein the transparent conductive material includes indium-tin-oxide.

9. Drive apparatus for an array of light emitting diodes as claimed in claim 7 wherein the transparent conductive material formed into a plurality of columns on the surface of the substrate forms the first contact for each of the organic light emitting diodes.

10. Drive apparatus for an array of light emitting diodes as claimed in claim 1 wherein the first plurality of switches each include a first input having an individual current source coupled thereto.

11. Drive apparatus for an array of light emitting diodes as claimed in claim 10 wherein the first plurality of switches each include a second input having a rest potential coupled thereto, which rest potential is below a level where individual light emitting diodes of the plurality of light emitting diodes will turn ON.

12. Drive apparatus for an array of light emitting diodes as claimed in claim 10 wherein the power source connectable to the second plurality of switches includes a battery having a positive terminal coupled to the individual current sources and a negative terminal connectable to the second plurality of switches.

13. Drive apparatus for an array of organic light emitting diodes comprising:

a first plurality of switches each connectable between one of a first input having an individual current source coupled thereto and a second input having a column rest potential coupled thereto, the column rest potential being below a level where individual light emitting diodes of the plurality of light emitting diodes will turn ON;

a second plurality of switches each connectable between one of a first input having a power source coupled thereto and a second input connected to a row rest potential;

an array including a plurality of organic light emitting diodes connected into rows of organic light emitting diodes and columns of organic light emitting diodes, each organic light emitting diode having a first contact formed of transparent conductive material connected to one of the first plurality of switches and a second contact connected to one of the second plurality of switches; and

control apparatus connected to the first and second pluralities of switches for connecting selected switches of the first plurality of switches to the current source while retaining all remaining switches of the first plurality of switches connected to the column rest potential, and periodically connecting each switch of the second plurality of switches, one at a time, to the power source while retaining all remaining switches of the second plurality of switches connected to the row rest potential.

14. Drive apparatus for an array of organic light emitting diodes as claimed in claim 13 wherein the plurality of organic light emitting diodes are positioned on a transparent substrate with the transparent conductive material being formed into a plurality of columns on the surface of the substrate.

15. Drive apparatus for an array of organic light emitting diodes as claimed in claim 14 wherein the transparent conductive material includes indium-tin-oxide.

16. Drive apparatus for an array of organic light emitting diodes as claimed in claim 15 wherein the transparent conductive material is formed into a plurality of columns on the surface of the substrate and forms the first contact for each of the organic light emitting diodes.

17. Drive apparatus for an array of organic light emitting diodes as claimed in claim 14 wherein each of the organic light emitting diodes includes a layer of hole transporting material positioned adjacent the transparent conductive material and a layer of electron transporting material positioned adjacent the layer of hole transporting material.

18. Drive apparatus for an array of organic light emitting diodes as claimed in claim 13 wherein the power source coupled to first input of the second plurality of switches includes a battery having a positive terminal coupled to the individual current sources and a negative terminal coupled to the first input of the second plurality of switches.

19. A method of driving an array of light emitting diodes comprising the steps of:

providing an array of light emitting diodes including a plurality of light emitting diodes with each light emitting diode of the plurality of light emitting diodes having a first contact and a second contact, the plurality of light emitting diodes, each with the first contact and the second contact, defining a plurality of the first contacts and a plurality of the second contacts with the plurality of the first contacts connected into a plurality of columns of first light emitting diode contacts and the plurality of the second contacts connected into a plurality of rows of second light emitting contacts;

connecting selected columns of first light emitting diode contacts to individual current sources and a first row of second light emitting diode contacts to a power source so as to drive current into the selected columns of first light emitting diode contacts and out the first row of second light emitting diode contacts, and connecting unselected columns of first light emitting diode contacts to a column rest potential below a level where individual light emitting diodes of the plurality of light emitting diodes will turn ON and remaining rows of the plurality of rows to a row rest potential; and

periodically connecting each row of the remaining plurality of rows of light emitting diodes to the power source, one at a time, while connecting selected columns of light emitting diodes to individual current sources during each period to produce a desired image on the array, and simultaneously retaining unselected columns of first light emitting diode contacts at the column rest potential and the remaining rows of the plurality of rows connected to the row rest potential.

20. A method of driving an array of light emitting diodes as claimed in claim 19 wherein the step of providing the array of light emitting diodes includes providing an array of organic light emitting diodes positioned on a transparent substrate with a layer of transparent conductive material forming a first contact for each of the plurality of organic light emitting diodes and with the layer of transparent conductive material being formed into a plurality of columns on the surface of the substrate.