OPTICALLY TESTING CHIPLETS IN DISPLAY DEVICE

• US 20110043499A1
• Filed: 08/20/2009
• Published: 02/24/2011
• Est. Priority Date: 08/20/2009
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Mattern, Michael W., Hamer, John W., Cok, Ronald S.
• Granted Patent: US 8,259,095 B2
• Time in Patent Office: Days
• US Class Current: 345/205
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/2085 Special arrangements for addressing the individual elements of the matrix, other than by driving respective rows and columns in combination
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: H10K 59/129 Chiplets
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 71/70 Testing, e.g. accelerated lifetime tests

Abstract

A method of making a display includes providing a display substrate having a plurality of control electrodes in a display area; locating a plurality of chiplets responsive to a controller to provide current to the control electrodes, each chiplet having a separate substrate, at least one pixel connection pad electrically connected to a control electrode, and one or more test light emitters formed in the chiplet responsive to the current provided on the control electrodes to emit light; controlling the chiplets to pass current through one or more of the test light emitters formed in the chiplet to emit light; detecting the light emitted by the test light emitters to determine faulty chiplets or chiplet interconnections; replacing or repairing the faulty chiplets or chiplet interconnections; and forming an organic light emitting diode over the substrate in the display area connected to the control electrodes.

Claims

1. A display, comprising:

(a) a display substrate having a display area, and a plurality of chiplets having a substrate independent of the display substrate located over the display substrate in the display area, each chiplet having at least one connection pad, at least one pixel control circuit, and at least one pixel test circuit;

(b) a plurality of pixels located in the display area, each pixel including a control electrode, a second electrode, and at least one layer of light-emitting material located between the control electrode and second electrode, wherein the pixel control circuit is connected to the control electrode for driving the control electrode causing the light-emitting material to emit light;

(c) a controller connected to one or more chiplets for providing external control signals to the chiplet; and

(d) wherein the pixel test circuit includes one or more test light emitters responsive to the external control signals, the test light emitters emitting light independently of the layer of light-emitting material.

2. The display of claim 1, wherein each pixel has an independently controlled control electrode, the second electrode is common, and the pixel control circuit provides active-matrix control to the pixel.

3. The display of claim 1, wherein the pixel control circuit drives more than one pixel.

4. The display of claim 1, wherein the control electrodes and the second electrodes of a group of pixels form an array of row and column electrodes, each row and column electrode oriented in a different direction, the pixels defined by the overlapping of the control and second electrodes, and one or more of the pixel control circuits provide a passive-matrix control to the group of pixels.

5. The display of claim 1, including means for driving a test light emitter from each pixel responsive to current provided to that pixel.

6. The display of claim 1, including means for driving a test light emitter from each pixel control circuit.

7. The display of claim 1, including means for driving one test light emitter responsive to current provided to more than one pixel.

8. The display of claim 1, wherein each pixel test circuit includes a transistor for driving the test light emitter in response to current provided to at least one pixel.

9. The display of claim 1, wherein the test control circuit further includes a test signal that controls the test light emitter.

10. The display of claim 1, wherein the chiplet substrate is silicon.

11. The display of claim 1, wherein the test light-emitter is an inorganic point-source emitter.

12. A method of making a display, comprising:

(a) providing a display substrate having a display area and a plurality of control electrodes in the display area;

(b) locating a plurality of chiplets responsive to a controller to provide current to the control electrodes, each chiplet having a chiplet substrate separate from the display substrate, at least one pixel connection pad electrically connected to a control electrode, and one or more test light emitters formed in the chiplet responsive to the current provided on the control electrodes to emit light;

(c) controlling the chiplets to pass current through one or more of the test light emitters formed in the chiplet to emit light from the chiplet;

(d) detecting the light emitted by the test light emitters to determine faulty chiplets or chiplet interconnections;

(e) replacing or repairing the faulty chiplets or chiplet interconnections; and

(f) forming an organic light emitting diode over the substrate in the display area connected to the control electrodes.

13. The method of claim 12, wherein step f) includes forming at least one layer of light-emitting material over the control electrodes and forming a second electrode over the one or more layers of light-emitting material, wherein the control electrode, at least one layer of light-emitting material and second electrode form a light-emitting pixel responsive to current provided by the control electrode and the second electrode.

14. The method of claim 12 wherein the light is detected by employing an image sensor to form an image of the display area while the test light emitters are controlled to emit light.

15. The method of claim 12, further including the step of controlling the test light emitters to emit light simultaneously.

16. The method of claim 12, further including the step of controlling the test light emitters to emit light sequentially.

17. A chiplet, comprising:

(a) a chiplet substrate less than 40 microns thick;

(b) a pixel control circuit formed on or in the chiplet substrate and a pixel test circuit formed on or in the chiplet substrate;

(c) a plurality of connection pads formed over the chiplet substrate and electrically connected to the pixel control circuit;

(d) wherein the pixel control circuit responds to signals transmitted through a first connection pad to form a pixel driving signal connected to a second connection pad different from the first connection pad; and

(e) wherein the pixel test circuit is responsive to the pixel driving signal and includes one or more test light emitters, the test light emitter emitting light in response to the pixel driving signal.