Cathode ray tube focus supply
US5602447A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 3, 1994 |
| Grant date | Feb 11, 1997 |
| Priority date | — |
| Expiry date | Aug 3, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/26
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A focus supply circuit, comprising: a power source for generating a high voltage for energizing a cathode ray tube, including a transformer having a high voltage winding with at least one intermediate output tap; and, a focus screen assembly, having a resistive chain with an input terminal coupled for receiving the high voltage, a focus output terminal for energizing a focus electrode of the cathode ray tube and at least one intermediate input tap between the input terminal and the focus output terminal, coupled to the at least one intermediate tap of the high voltage winding by an independent conduction path. An effective bias current for the cathode ray tube flows in the resistive chain. The voltages at the intermediate taps correspond to one another within a tolerance. The conductive path presents sufficiently low impedance to substantially inhibit variation of the high voltage due to variation of leakage current from the focus electrode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.