Video clock generating circuit and horizontal synchronizing signal generating device in image forming apparatus using laser beam
US5331342A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 4, 1992 |
| Grant date | Jul 19, 1994 |
| Priority date | — |
| Expiry date | Mar 4, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/04794
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A basic clock generated from a crystal oscillator is delayed by a constant time in each of a plurality of delay elements connected in series. Consequently, internal clocks which differ in phase by a predetermined amount are outputted from the delay elements. Output signals of the delay elements are inputted to a clock selector. The clock selector selects any one of the internal clocks on the basis of a beam detection signal indicating the timing of the scanning of a photoreceptor by a laser beam to output the same as a video clock. The clock selector selects any one internal clock whose phase difference from the beam detection signal is closest to a predetermined phase difference out of the internal clocks, the phase difference from the beam detection signal meaning the time difference between the time when the beam detection signal has a predetermined phase angle and the time when the internal clock has a predetermined phase angle. A horizontal synchronizing signal is generated by counting a video clock at the timing based on the beam detection signal. The video clock outputted from the clock selector is synchronized with the beam detection signal with high precision. As a result,…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.