Apparatus and method for testing an active matrix pixel display

Details Apparatus and method for testing an active matrix pixel display Apparatus and method for testing an active matrix pixel display

1991-09-18

1993-02-02

Harvey, Jack B.

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

324681, 324 731, 324158R, 324158T, 340765, 340784, G01R 3102, G01R 2702

Patent

active

051840820

ABSTRACT:
Apparatus and an associated method are described for testing liquid crystal matrix displays that can be performed prior to the assembly of the display. This display procedure involves applying of square wave signal to the control elements and a sine wave signal to the input terminal of an active element associated with the pixel under test. By selection of the sine wave signal frequency, the modulation products resulting from the combination of the square wave signals and the sine wave signal fall between the components resulting from the application of the square wave signal alone. As a result of the symmetry of the modulation components, a comb filter can be used to select the modulation components. The power of the transmitted modulation products provides a figure of merit for the active element associated with the pixel. A capacitor can be included along with the active element in the matrix display which couples the output signal of each active element to a row (control terminal) electrode on the same substrate as the active element. The capacitor provides an increase in the test result signal to noise level and permits testing of the active matrix substrate prior to display assembly.

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patent: 4819038 (1989-04-01), Alt
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patent: 4843312 (1989-06-01), Hartman et al.
patent: 5113134 (1992-05-01), Plus et al.

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