Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1994-08-04
1996-07-23
Karlsen, Ernest F.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
324678, G01R 3100
Patent
active
055393268
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).
REFERENCES:
patent: 5073754 (1991-12-01), Henley
patent: 5081687 (1992-01-01), Henley et al.
patent: 5262720 (1993-11-01), Senn et al.
patent: 5377030 (1994-12-01), Suzuki et al.
patent: 5428300 (1995-06-01), Takahashi et al.
patent: 5432461 (1995-07-01), Henley
Oshimi Tadashi
Takahashi Isamu
Karlsen Ernest F.
Kobert Russell M.
Tohken Industries Co., Ltd.
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