US 4,069,443 AGranted

Integrated vertical-sweep generator for television receiver

AssigneeSGS-ATES Componenti Elettronici S.p.A.

InventorLuigi Venutti

Life of this patent

Estimating the term…

Loading patent…

Abstract

A vertical-sweep generator for a deflection yoke of a cathode-ray tube in a television receiver comprises a monolithic integrated semiconductor chip including transistors and resistors defining, together with external circuit elements, a free-running multivibrator (O, O.sub.1), an associated synchronizing circuit (O.sub.2), and a ramp-current generator (RC, RC.sub.1) controlled by the multivibrator in order to regulate the yoke current by way of a power amplifier (PA) and a flyback circuit (FG). The multivibrator generates short switching pulses, of a duration equaling about one-fourth of the flyback period, whose disappearance coincides with the start of the ramp current; these switching pulses are triggered by externally applied synchronizing pulses and cause the blocking of a discharge loop for a sweep capacitor in series with the yoke, charged in the second half of the flyback period, whereby the discharge current flowing at the end of a sweep cycle is directed into a storage circuit (C109, C110) during the first half of the next flyback period preparatorily to a recharging of the sweep capacitor. Upon termination of the switching pulse, the blocking of the discharge loop is maintained during the remainder of the flyback period by a clamping circuit (PA.sub.2) responsive to a voltage differential between the storage circuit and the power supply.

A vertical-sweep generator for a cathode-ray tube of a television receiver, comprising:

oscillator means for generating a periodic switching pulse to start a recurrent sweep cycle divided into a relatively short retrace period and a relatively long trace period;
a ramp-current generator connected to said oscillator means for producing an output current returning to a base level in response to said switching pulse and varying monotonically from said level upon the termination of said switching pulse;
a source of direct current;
a scanning circuit including a deflection coil and a sweep capacitor in series, said scanning circuit forming a supply path for the feeding of charging current from said source via said coil to said sweep capacitor and a discharge loop for passing reverse current from said sweep capacitor through said coil;
amplifier means in said scanning circuit for regulating said charging and reverse currents under the control of said output current;
electronic switch means controlled by said oscillator means for temporarily blocking the flow of reverse current in said discharge loop at the end of a sweep cycle and starting the retrace period of a new cycle in response to said switching pulse;
capacitive storage means chargeable by said source and connected to said scanning circuit for receiving residual reverse current from said sweep capacitor in a first part of said retrace period, upon a blocking of said discharge loop by said switch means, and delivering a charging current via said supply path to said sweep capacitor in a second part of said retrace period;
and
clamping means responsive to a voltage difference between said source and said storage means for maintaining the blocking of said discharge loop over a period exceeding the duration of said switching pulse until the disappearance of said voltage difference, due to the flow of said charging current, at the end of the retrace period.

6 more elements

Abstract

Claims10