Variable-frequency sweep generator circuit
US3947724A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 7, 1974 |
| Grant date | Mar 30, 1976 |
| Priority date | — |
| Expiry date | Nov 7, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K4/501
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An improved sweep generator circuit suitable for deflection circuits in television receivers conventionally includes a condenser chargeable through a resistance to establish the sweep. A resistive voltage divider and a threshold comparator circuit are each arranged parallel to the condenser. The comparator circuit is triggerable to establish a low impedance discharge path across the condenser when the charging voltage across the condenser exceeds a normal reference voltage from the voltage divider. The frequency of the generator is made variable in response to a synchronization frequency within predetermined limits by shunting a resistance of the voltage divider by a control resistance through an electronic switch that is triggerable by the sync pulse train. Normally the minimum sync interval determins the heighest frequency of the sweep generator; if an additional (disturbance) pulse occurs within such minimum sync interval to prematurely establish the shunt connection of the control resistance, the condenser will not have had time to charge up to a value sufficient to reach the then-reduced reference voltage, and the comparator circuit will remain in its high impedance condition …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.