Circuit arrangement for producing a sawtooth current through a line deflection coil in an image display apparatus

Abstract

A circuit arrangement which is the combination of a switched supply circuit and a line deflection circuit, the supply transformer being replaced by a coil.

What is claimed is: 
     
       1. Circuit arrangement for producing a sawtooth current through a line deflection coil, which coil is part of a resonance circuit comprising also a trace capacitor and a retrace capacitor, switching means applying the voltage across the trace capacitor to the deflection coil at line frequency during the trace interval of the sawtooth current, which switching means comprise a first diode and a controlled switch connected in parallel with the said diode via a second diode, and an inductive element having a winding which is connected to the resonance circuit via a third diode, current flowing through the winding and the third diode during the cutoff period of the switch, characterized in that a current which is supplied to the controlled switch by a direct-voltage source connected between the winding and the switch also flows through the winding. 
     
     
       2. Circuit arrangement as claimed in claim 1, characterized in that both the series combination of the second and third diodes, which are connected with the same pass direction, and the series combination of the winding and the collector-emitter path of the controlled switch, which takes the form of a transistor, are connected in parallel with the direct-voltage source, the first diode being connected between the junction point of the second and third diodes and the junction point of the winding and the transistor. 
     
     
       3. Circuit arrangement as claimed in claim 1, characterized in that the direct-voltage source is in the form of a capacitor, a further direct-voltage source being connected via a choke coil to the controlled switch. .Iadd. 
     
     
       4.  Circuit arrangement for producing a sawtooth current through a coil, which coil is part of a resonance circuit comprising also a first capacitor and a tuning capacitor, switching means applying the voltage across the first capacitor to the coil at line frequency during the trace interval of the sawtooth current, which switching means comprise a first diode and a controlled switch connected in parallel with the said diode via a second diode, and an inductive element having a winding which is connected to the resonance circuit via a third diode, current flowing through the winding and the third diode during the cutoff period of the switch, characterized in that a current which is supplied to the controlled switch by a direct voltage source connected between the winding and the switch also flows through the winding. .Iaddend. .Iadd. 
     
     
       5.  Circuit arrangement as claimed in claim 4, wherein both the series combination of the second and third diodes, which are connected with the same pass direction, and the series combination of the winding and the collector-emitter path of the controlled switch, which comprises a transistor, are connected in parallel with the direct-voltage source, the first diode being connected between the junction point of the second and third diodes and the junction point of the winding and the transistor. .Iaddend. .Iadd. 
     
     
       6.  Circuit arrangement as claimed in claim 4, wherein the direct-voltage source comprises a capacitor, a further direct-voltage source being connected via a choke coil to the controlled switch. .Iaddend.