Light emitting diode array current power supply
US4864216A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 19, 1989 |
| Grant date | Sep 5, 1989 |
| Priority date | — |
| Expiry date | Jan 19, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K15/1247
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A power supply circuit for an LED print head has a reference current source connected to a printer system reference voltage for providing a second reference voltage for an individual, integrated circuit chip. A plurality of substantially similar field effect transistors have their gates connected to the chip reference voltage for providing substantially similar current to each of a plurality of light emitting diodes. The current is enabled to each such LED by the presence or absence of a data signal. A reference resistor in the reference current source permits adjustment so that each of a plurality of integrated circuit chips can provide substantially similar current to each of a plurality of LED dice, or adjust the current level, if required, to achieve similar light output from each LED.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.