Time expansion of pulse width modulation sequences by clock dropping
US5912712A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 11, 1998 |
| Grant date | Jun 15, 1999 |
| Priority date | — |
| Expiry date | May 11, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2340/0435
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for expanding pulse width modulation sequences that control a display system to adapt to varying video frame times. A minimal amount of extra circuitry (10) is provided that regulates a sequencer (26). After calculating the appropriate expansion factor needed to stretch a base sequence, the system control circuit (22) sends that information to the circuitry (10). The circuitry (10) includes a counter (14) that repetitively counts down a number of clock cycles and causes the clock to drop a cycle. This dropping of clock cycles causes the sequence time to be expanded, as it takes the system longer to reach the necessary number of clock cycles that determine a sequence. Several base pulse width modulation sequences could be stored in memory, each of which can be used for a range of frame times, eliminating the need for one sequence for every possible variation in the frame time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.