Open loop brightness control for EL lamp
US5493183A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 14, 1994 |
| Grant date | Feb 20, 1996 |
| Priority date | — |
| Expiry date | Nov 14, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/04
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An EL lamp characterized by non-linear brightness decay is driven to constant brightness for the life of the lamp by an inverter controlled by a microprocessor. The microprocessor controls the inverter in accordance with a table containing data which is the inverse function of the non-linear brightness decay. The microprocessor tracks the total on-time of the EL lamp and selects the appropriate data from the table for driving the lamp. Control can be analog or digital. If control is analog, the selected data is coupled to a D/A converter which is coupled to the inverter. If control is digital, the selected data is coupled to a counter driving a pulse width modulator which is coupled to the inverter. In accordance with another aspect of the invention, an EL lamp is dimmed a precise amount based upon the data in the table and the EL lamp can be dimmed in unison with other lamp types, each lamp type having a table containing data for dimming.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.