Browse Prior Art Database

Power Supply Circuit

IP.com Disclosure Number: IPCOM000035068D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Kobayashi, M: AUTHOR [+3]

Abstract

Disclosed is a power supply circuit for a cathode ray tube (CRT) display monitor in which a signal from a flyback transformer (FBT) in a monitor analog circuit is used to control the power supply circuit. Referring to Fig. 1, the power supply circuit includes a line filter, an AC-DC converter which controls the power factor and generates a stabilized DC voltage, and a DC-DC converter. AC voltage of the range between AC 120 V and AC 240 V is applied to the power supply circuit which generates a predetermined DC voltage. The power supply circuit and the monitor analog circuit are coupled by a transformer. Triple isolated wire is wound on a core of the FBT, as shown in Fig. 2.

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Power Supply Circuit

Disclosed is a power supply circuit for a cathode ray tube (CRT) display monitor in which a signal from a flyback transformer (FBT) in a monitor analog circuit is used to control the power supply circuit. Referring to Fig. 1, the power supply circuit includes a line filter, an AC-DC converter which controls the power factor and generates a stabilized DC voltage, and a DC-DC converter. AC voltage of the range between AC 120 V and AC 240 V is applied to the power supply circuit which generates a predetermined DC voltage. The power supply circuit and the monitor analog circuit are coupled by a transformer. Triple isolated wire is wound on a core of the FBT, as shown in Fig. 2. The induced signal on the wire is used as control signals stated below: Synchronizing pulse for the DC-DC converter Start/re-start trigger pulse for the AC-DC converter, and

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+B DC voltage for controlling integrated circuit in the AC-DC converter Since the control signals for the power supply circuit are supplied from the flyback transformer in the monitor analog circuit which is coupled to the power supply by the FBT, the influence of variation of the AC input voltage on the control signals is kept quite low, resulting in the power supply circuit generating stable DC voltage regardless of the variation of the AC input voltage.

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