Light emitting diode array current power supply
US5099192A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 12, 1990 |
| Grant date | Mar 24, 1992 |
| Priority date | — |
| Expiry date | Oct 12, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J2/45
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
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. The reference current source is controlled by an operational amplifier, the output of which comprises the second reference voltage. A plurality of output driver FETs are biased by the reference voltage. Each output driver FET provides current to an associated LED responsive to a data signal. A plurality of control FETs are connected in parallel with each other and in series with each output driver FET for varying the LED output current responsive to programming data signals. A second group of control FETs is interposed in the feedback loop of the operational amplifier for varying the second reference voltage responsive to a different set of programming data signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.