Flash tube simmer circuitry for a film video player electronic strobe light
US4623929A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 3, 1985 |
| Grant date | Nov 18, 1986 |
| Priority date | — |
| Expiry date | May 3, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/36
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A film video player includes an electronic strobe light operable for repetitively firing a flash tube, to flash illuminate a solid state image sensor via a high-intensity light pulse projected onto photographic film at the vertical retrace rate of a standard television signal. A current sink circuit is provided for drawing a flash tube simmer current, to maintain an arc in the flash tube between sensor-illuminating pulses. Sensing circuitry, coupled to a junction common to the flash tube and the current sink circuit, produces a control signal corresponding to whether or not the flash tube is conducting simmer current. Switching circuitry, responsive to the control signal at the vertical retrace rate, (1) causes the overriding of the operation of a flash tube trigger circuit when the control signal indicates that the flash tube is conducting simmer current, and (2) causes the operating of the trigger circuit when the control signal indicates that the flash tube is not conducting simmer current. By providing for the triggering of the flash tube only when the simmer current is off, electromagnetic interference, which is produced by the flash tube trigger voltage and which can adversel…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.