Drive circuit of light emitting element
US6097159A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 24, 1999 |
| Grant date | Aug 1, 2000 |
| Priority date | — |
| Expiry date | Feb 24, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/06808
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A drive circuit of a light emitting element capable of setting a desired constant current and capable of operating stably at a high speed while holding a forward direction voltage required for the emission of light even under a low power supply voltage, wherein there is provided an input circuit which receives differential drive signals and outputs differential signals of levels in accordance with the level of a supplied drive voltage, a differential output circuit in which an emitter-connection portion of transistors is grounded via a resistor, the differential signals and are supplied to bases, and a laser diode is connected to a collector of the transistor, a reference voltage generation circuit which generates a reference voltage, a comparison circuit which compares the voltage of the emitter-connection portion with the reference voltage and outputs a signal of the level in accordance with the result of comparison, and a variable voltage supply circuit which generates a voltage in accordance with the input level of the output signal and supplies the same as the drive voltage of the input circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.