Patent ID: 6411048
Filing Date: 2002-06-25
Classification: H03K,H04N

Abstract:
A device for controlling a vertical deflection circuit for the vertical scan and flyback of a spot scanning a screen, the device comprising:an output amplifier stage for controlling the vertical scan of the spot, the output amplifier stage including at least first and second transistors connected together and capable of operating in an alternating switching mode to control the vertical scan of the spot; an auxiliary voltage supply capable of delivering an overvoltage to the vertical deflection circuit; a first controllable switch connected between the auxiliary voltage supply and the output amplifier stage for regulating the delivery of the overvoltage to the vertical deflection circuit for flyback of the spot; and a second controllable switch connected to the first transistor of the output amplifier stage and for connection to a main voltage supply, for preventing delivery of the overvoltage during control of the vertical scan of the spot; wherein the first controllable switch comprises a third transistor and a third diode connected in anti-parallel with the terminals of the third transistor, an anode of the third diode being connected to the first transistor; and wherein the second controllable switch comprises a fourth transistor connected in series between the first transistor and the first terminal of the main voltage supply, and a fourth diode connected in anti-parallel with the terminals of the fourth transistor, a cathode of the fourth transistor being connected to the first transistor and an anode of the fourth transistor being connected to the first terminal of the main voltage supply, the fourth transistor being on while the third transistor is off, and vice versa.