Synchronization to a start-of-scan detection, and digital generation of variable frequencies, from a fixed-frequency fixed-phase frequency source in an image generator in order to highly accurately time the placement of pixels upon a scan line
US5477330A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 16, 1992 |
| Grant date | Dec 19, 1995 |
| Priority date | — |
| Expiry date | Oct 16, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/04794
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A highly accurate and stable, but continuous fixed-phase fixed-frequency, quartz crystal oscillator frequency source, typically of 80 Mhz frequency, is used as the primary frequency standard for (i) synchronized, and (ii) variable, pixel placement timing in a bee-scanning image generator. A fixed-frequency timing chain appropriately synchronized to the scanning energy beam is generated by selecting, in accordance with a sensed start-of-scan condition, from among a number, typically 23, of variably-phase-delayed, typically by less than 1 nanosecond and normally by 0.8 nanosecond, replications of a fixed-phase timing chain that is produced from the crystal oscillator. The synchronized fixed-frequency timing chain so derived is then converted to the required variable-frequency pixel placement timing chain by timing-data-driven recombination of variably-phase-delayed replications, typically 13 such replications at a delay of 1.5 nanoseconds one to the next, of each of (i) the source, fixed-frequency, timing chain and (ii) a 180.degree. phase-shifted version of this source timing chain. The (i) synchronized and (ii) variable-frequency pixel placement timing chain so derived from a fixed…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.