Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-02-02
2003-05-06
Cuchlinski, Jr., William A. (Department: 3661)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S075200, C345S055000
Reexamination Certificate
active
06559818
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to matrix addressable display devices, and more particularly to a method for testing the emission of the displays.
BACKGROUND OF THE INVENTION
Quality assurance requires the testing of manufactured products to determine if they will function over a given set of parameters. Testing is performed on a random sampling of products from the production lines, or in some industries, on every product which is manufactured.
Optical measurements are currently performed on display devices at the final stages of display testing. Optical measurement is accomplished by turning on all the cathode emitters in a pixel, and visually observing them. This method is extremely subjective, as it relies on the judgement of the individual peering at the screen.
Photon Dynamics of Milipitas, Calif. employs a method in which photons from a full display (i.e., substantially all of the pixels are turned “on” at the same time) are measured. A completed display device is optically tested by measuring the light emitted from the display.
There are several drawbacks to the above described optical method. For example, the process is very expensive, as it requires sophisticated optics and processing algorithms in order to determine the relative number of functional pixels.
Additionally, the optical systems require closely spaced anodes with respect to the cathode in order for the inspection optics to obtain accurate measurements. Therefore, the optical systems are not practical for testing display base-plates prior to their assembly in a field emission device.
Other methods used to measure current emitted by field emitter devices employ a positively biased electrode. However, these methods also measure the total current emitted by substantially all of the pixels in the completed unit. Therefore, these methods are also limited to measuring the operation of the device as a whole.
There still exists a need for a method to measure the current emitted by individual pixels in the display in order to determine their functionality, as well as the total number of functioning pixels (also known as the “yield”). Additionally, manufacturing realities require that the functionality of the individual pixels is measured in a rapid fashion.
SUMMARY OF THE INVENTION
The functionality of individual pixels in an addressable emissive cathode is determined by measuring the emitted current from a single pixel or from a small group of pixels. The current is measured on an anode screen disposed above the cathode emitters, thereby enabling the anode to collect electrons emitted from the cathodes. The collected current is compared to known parameters in order to determine whether the individual pixel site is functional.
The method of the present invention allows for the testing of cathode emitters in a vacuum chamber through the use of probe cards or sockets, and an anode. This format allows for the testing of approximately 100,000 pixels in less than 30 seconds, thereby expanding testing capabilities. Not only does the present technique permit faster testing, but also a less expensive alternative to the functionality tests used for individual pixels.
One advantage of the test method of the present invention is that it enables rapid determination of individual pixel functionality of the cathode emitters used in field emission type displays, or other similarly addressed matrix displays. For example, the present test method is suitable for displays that are actively or passively addressed.
The method of the present invention permits testing of the cathode emitters either as a baseplate or an assembled display device. Additionally, the use of an anode which luminesces under electron bombardment permits the measurement of emitted photons to determine pixel functionality.
The present invention is employed to sequence through all of the pixels, one or more at a time. Additionally, there is no required spacing for the anode in order to achieve accurate measurement. Further the present invention can be used with current optical methods to enhance the value of those methods.
One embodiment of the present invention is a method of testing cathode emitters by measuring the current emitted from the emitters. A group of cathode emitters comprises a pixel.
Another embodiment of the present invention is a method for measuring functionality in an addressable matrix used in a display device by addressing a single pixel, thereby creating an output. The output of the single pixel is then measured to determine functionality of that particular pixel.
A further embodiment of the present invention is a method for determining functionality of cathode emitters in which at least one pixel is addressed, thereby producing a current. The pixel is comprised of at least one cathode emitter. Collecting the current using an anode which is disposed opposite said at least one pixel. Measuring the current, and comparing the current to an expected value.
REFERENCES:
patent: 4763187 (1988-08-01), Biberian
patent: 5006792 (1991-04-01), Malhi et al.
patent: 5008657 (1991-04-01), Hanson et al.
patent: 5015912 (1991-05-01), Spindt et al.
patent: 5099178 (1992-03-01), Bozzer et al.
patent: 5103144 (1992-04-01), Dunham
patent: 5155413 (1992-10-01), Bozzer et al.
patent: 5194780 (1993-03-01), Meyer
patent: 5262698 (1993-11-01), Dunham
patent: 5283500 (1994-02-01), Kochanski
patent: 5300862 (1994-04-01), Parker et al.
patent: 5336992 (1994-08-01), Saito et al.
patent: 5382961 (1995-01-01), Gale, Jr.
patent: 5432461 (1995-07-01), Henley
patent: 5459409 (1995-10-01), Henley
patent: 5459410 (1995-10-01), Henley
patent: 5459480 (1995-10-01), Browning et al.
patent: 5475281 (1995-12-01), Heijboer
patent: 5475317 (1995-12-01), Smith
patent: 5491427 (1996-02-01), Ueno et al.
patent: 5493236 (1996-02-01), Ishii et al.
patent: 5541478 (1996-07-01), Troxell et al.
patent: 5542866 (1996-08-01), Tsai
patent: 5638086 (1997-06-01), Lee et al.
patent: 5721472 (1998-02-01), Browing et al.
patent: 5730634 (1998-03-01), Seko
patent: 5751262 (1998-05-01), Browning et al.
patent: 5942849 (1999-08-01), Cade
patent: 6064217 (2000-05-01), Smith
patent: WO85/05491 (1985-05-01), None
patent: 85/05491 (1985-05-01), None
Busta, H.H., “Vacuum microelectronics—1992”,J. Micromech. Microeng., pp. 43-74, (1992).
Schwoebel, et al., “Filed-Emitter Array Performance Enhancement Using Glow Discharge Processing”, IVMC Technical Digest, Jul. 12-15, 1993, p. 14.
Sokolich, et al., “A Study of the Emission Characteristics of All-metal Cold Cathodes”, IVMC Technical Digest, Jul. 12-15, 1993, pp. 19, 20.
R. Cummins et al., “Evaluating Image Quality and Defect Characterization Flat-Panel”, Journal, pp. 29-32.
Francois Henley et al., “A High Speed Plat Panel In-Process Test System for TFT Array Using Electro-Optic Effects”, Journal, pp. 64-67.
Glenn D. Houser, “In-Process Testing of LCD Panels by Voltage Imaging TM: Methods and Capabilities”, Journal.
Brochure, “FIS Flat Panel Inspection System”, Photon Dynamics.
Heinz H. Busta, “Vacuum microelectronics—1992”, Journal, pp. 43-74.
M. Miller et al., “A Flat-Panel-In-Process Test System Using Voltage Imaging”, Journal, pp. 27-31.
J. R. Monkowski et al., “Detection and Measurement of Low Contrast Mura Defects in Flat-Panel Displays”, Journal, pp. 51-52.
Busta, H.H., “Vacuum microelectronics—1992”,J. Micromech. Microeng., pp. 43-74, (1992).
Cuchlinski Jr. William A.
Marc-Coleman Marthe
Schwegman Lundberg Woessner & Kluth P.A.
LandOfFree
Method of testing addressable emissive cathodes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of testing addressable emissive cathodes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of testing addressable emissive cathodes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3016103