Brightness adjusting device and liquid crystal display having the same
US8139019B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 2007 |
| Grant date | Mar 20, 2012 |
| Priority date | — |
| Expiry date | Dec 16, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/3927
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A brightness adjusting device includes a multiplication circuit, which multiplies a vertical signal by a predetermined multiplication ratio to output a multiplication signal, a differential circuit that distinguishes between different multiplication signals, a serrated wave generator that charges/discharges a condenser according to a signal output from the differential circuit and generates a serrated wave having constant amplitude independently of a frequency of the multiplication signal, a brightness adjusting voltage generator that generates a reference voltage to determine a pulse duty, and a comparator that outputs a pulse signal by comparing a voltage of the serrated wave with the brightness adjusting voltage. The brightness adjusting voltage generator includes a circuit that outputs a variable voltage, and the multiplication circuit includes a circuit having a variable multiplication ratio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.