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:
Nov. 04, 1997
Filed:
Apr. 25, 1996
John R Ayres, Reigate, GB;
Martin J Edwards, Crawley, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
In an LCD or other electronic device, thin-film circuit elements on a substrate (100) form a sample-and-hold or other sampling circuit (10). The circuit (10) comprises a TFT (Ts) as a sampling transistor and preferably another TFT (T2) to compensate for displacement currents in charging and discharging the insulated gate (12) of the sampling TFT. Even when T2 is included, a slow drift in output voltage (Vo) is observed when Ts switches off, and this limits use of the circuit, especially in large area active-matrix devices. In accordance with the invention this slow drift is removed or significantly reduced by injecting minority carriers into the channel region of Ts (and T2) from a doped opposite-type region (119) or Schottky contact region (119) which is forward biased via a thin-film supply line (129). The minority carriers neutralise majority carriers which are being slowly released by thermal emission from trapping states in the TFT body.