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Bias Voltage Generating Circuit

IP.com Disclosure Number: IPCOM000035067D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Kobayashi, M: AUTHOR

Abstract

Disclosed is a bias voltage generating circuit for generating bias voltages for a first grid (G1) and second grid (G2) of a cathode ray tube (CRT). In the figure a flyback transformer (FBT) has a secondary winding W1 from which a voltage for an anode of the CRT and a focus control voltage are supplied. A floating winding W2 is additionally provided in the FBT to generate a floating flyback pulse voltage. A diode D2 and a capacitor C1 operate as a rectifying and smoothing circuit to generate a floating DC voltage. A positive output terminal is connected to the grid G1 of the CRT, and a negative output terminal is connected to the grid G2 of the CRT. A resistor network including resistors R1 and R2 and a potentiometer VR is connected across the terminals G1 and G2.

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Bias Voltage Generating Circuit

Disclosed is a bias voltage generating circuit for generating bias voltages for a first grid (G1) and second grid (G2) of a cathode ray tube (CRT). In the figure a flyback transformer (FBT) has a secondary winding W1 from which a voltage for an anode of the CRT and a focus control voltage are supplied. A floating winding W2 is additionally provided in the FBT to generate a floating flyback pulse voltage. A diode D2 and a capacitor C1 operate as a rectifying and smoothing circuit to generate a floating DC voltage. A positive output terminal is connected to the grid G1 of the CRT, and a negative output terminal is connected to the grid G2 of the CRT. A resistor network including resistors R1 and R2 and a potentiometer VR is connected across the terminals G1 and G2. A variable terminal of the VR is connected to a DC voltage or ground. Capacitors C2 and C3 are connected for stabilizing the DC voltage. By adjusting the potentiometer VR, the voltages supplied to the grids G1 and G2 are varied against the ground level, keeping the voltage difference between the G1 and G2, whereby the cut-off bias voltage of the CRT is adjusted by the potentiometer VR.

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