Liquid crystal display driving scaler capable of reducing electromagnetic interference
US7142187B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 6, 2003 |
| Grant date | Nov 28, 2006 |
| Priority date | — |
| Expiry date | Feb 13, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2340/0435
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An LCD driving scaler capable of reducing electromagnetic interference employs a spread spectrum phase locked loop (PLL) in which a multi-phase voltage controlled oscillator oscillates and outputs a scaler pixel clock signal and a plurality of oscillation signals of different phases. A spread spectrum processor counts clock periods of a reference pixel clock signal when a horizontal synchronization signal having an adjusted frame rate is activated, and sequentially outputs the plurality of oscillation signals in response to a decoding signal. The plurality of oscillation signals are output to a main divider, which generates the main divider signal by dividing the frequencies of the plurality of oscillation signals. A main divider signal is input into a phase frequency detector, which detects a phase difference between the predivider signal and the main divider signal and outputs the phase difference signal so that the frequency of the scaler pixel clock signal repeatedly varies.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.