Schaltungsanordnung zum Erzeugen von elektrischen Signalen mit stufenartigem Verlauf

摘要

1,202,602. Converting. INTERNATIONAL POLAROID CORP. 22 Aug., 1967 [22 Aug., 1966], No. 38562/67. Addition to 1,124,873. Heading H2F. [Also in Division H3] The voltage across the capacitance of a resonant circuit is repeatedly changed between two values while the inductance of the circuit is temporarily reduced, the change in one direction only being effected by a steady voltage source. The resulting wave is added to a steady EHT voltage so that the combined voltage alternates between two positive values. In Fig. 2 a pulse from a thyristor oscillator 81 renders the thyristor 58a1 conducting. This effectively shortcircuits the primary winding 54b1 raising the resonant frequency of the secondary circuit so that output capacitance 55 is charged steeply during a half-cycle of oscillation (80b, Fig. 3, not shown). Meanwhile a capacitor 591 charges and extinguishes the thyristor at about the end of the half-cycle. The resonant frequency is now much lower and the voltage across the capacitance 55 is substantially maintained (80a, Fig. 3, not shown) until thyristor 601 is fired whereupon the charge in capacitor 551 is rapidly reduced in a resonant manner while capacitor 591 discharges. The resulting substantially square wave secondary voltage is added in series with (or in parallel with, Fig. 7, not shown) a D.C. EHT voltage applied at 461 so as to provide an EHT voltage (for the target of a colour cathode ray tube) which steps between two high-voltage levels. In Fig. 4 (not shown), a single primary winding is used and in Fig. 5 (not shown), the downward step is produced by short-circuiting a tertiary winding through a resistor so as to dissipate energy stored in the inductive circuit. Transistors may he used as the switches.