A contrast control circuit for a display apparatus includes first and second resistors, a first transistor, a second transistor, and a Darlington circuit. The first and second resistors, each have a first end connected to a positive supply voltage. The first transistor has an emitter connected to a second...http://www.google.de/patents/US6724380?utm_source=gb-gplus-sharePatent US6724380 - Contrast control circuit for display apparatus
