The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 23, 1996
Filed:
Aug. 04, 1994
Isamu Takahashi, Tokyo, JP;
Tadashi Oshimi, Tokyo, JP;
Tohken Industries Co., Ltd., Tokyo, JP;
Abstract
A method of testing if the wiring or state of a TFT and LCD is abnormal includes the following steps: In a first operation, a TFT is turned on for a given time period to charge the cell capacitor connected to an LCD through the data line thereof. Next, the TFT is turned off, maintaining the charged condition. Then, the TFT is turned on again for a given time period T to release the stored electric charge through the source, drain and a grounded resistor. Changes with time in the output of source current (i.sub.1) or voltage (V.sub.1) induced by the discharge are input into a computer. In a second operation, the TFT is turned on for a given time period without charging the cell capacitor through the data line. After turning off the TFT for the same time as the first operation, the TFT is turned on again for a given time period to release the stored charge through the source, drain and grounded resistor. Then, changes with time in the output of source current i.sub.2 or source voltage V.sub.2 induced by discharge are input into the computer. In a third operation, the computer calculates the integration: ##EQU1## The computer judges whether the TFT-LCD is properly wired or the state of the TFT and LCD is normal by checking whether the calculation is smaller than a reference value of V.sub.s C.sub.so (R.sub.on +R.sub.g) or I.sub.s C.sub.so (R.sub.on +R.sub.g).