Browse Prior Art Database

Power Supply

IP.com Disclosure Number: IPCOM000037309D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Kobayashi, M: AUTHOR [+3]

Abstract

Disclosed is a technique of high frequency Switching Mode Power Supply (SMPS) of a CRT display monitor.

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Power Supply

Disclosed is a technique of high frequency Switching Mode Power Supply (SMPS) of a CRT display monitor.

Fig. 1 shows a conceptual structure of the technique. The SMPS receives a horizontal sync signal from a logic or monitor circuit. The frequency of the sync signal is converted to an Nth harmonic frequency signal by a frequency converter
7. The frequency converter 7 is better placed between the sync signal source and a primary/ secondary isolation device 6, which is provided for the sync signal transfer purpose, as illustrated in Fig. 1. However, the frequency converter 7 can be provided at the back-side of isolation device 6 from the signal source, as illustrated in Fig. 2. The isolation device 6 usually uses a photo- coupler or a pulse transformer. The Nth harmonic frequency signal is inputted to a power control circuit 3.

The power control circuit 3 must be a pulse-width modulation (PWM) type controller and operates locked with the Nth harmonic frequency signal. As most of SMPS is adapting, the power control circuit can operate at a self-oscillating frequency by a self-oscillating function when the Nth harmonic frequency signal is not applied.

The power control circuit 3 also receives a voltage feedback signal from voltage sense circuit 8 through another isolation device 5 in order to stabilize an output voltage from SMPS.

The output of the control circuit 3 drives a power isolation transformer 1, into which an unregulated DC voltage is applied,...