Display control apparatus
US5721570A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 16, 1997 |
| Grant date | Feb 24, 1998 |
| Priority date | — |
| Expiry date | May 16, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G5/366
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A horizontal synchronizing signal is applied as a reference signal and a voltage-controlled oscillator outputs a frequency signal on the basis of the frequency of the horizontal synchronizing signal. The period of the frequency signal is divided in accordance with a frequency-dividing value set in advance, the difference in frequency between the frequency-divided frequency signal and the horizontal synchronizing signal and the phase difference between them are obtained, and control is performed in such a manner that the frequency of the signal outputted by the voltage-controlled oscillator is decided in dependence upon the frequency difference. In an interval in which a vertical synchronizing signal turns off and the frequency of the horizontal synchronizing signal fluctuates, the input to the voltage-controlled oscillator is held fixed to prevent a fluctuation in the outputted display clock.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.