Light emitting element driving device and portable apparatus equipped with light emitting elements
US7157866B2 · kind B2 · utility
9Cited by
0References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 10, 2005 |
| Grant date | Jan 2, 2007 |
| Priority date | — |
| Expiry date | Jun 24, 2025 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S362/806
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A driving device for driving multiple (R-, G-, and B-) groups of LEDs operative at different voltages, utilizing a battery supplying a power supply voltage of a step-up voltage. Under normal operating conditions, R-LEDs are driven by the battery voltage, but G- and B-LEDs are driven by the step-up voltage. The battery voltage is monitored to ensure that all the LEDs are driven by the step-up voltage when the battery voltage has lowered below a predetermined level, thereby reducing the power loss by the LEDs while emitting light and extending the permissible range of the battery voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.