| 摘要 |
<p>A power supply circuit for an LED print head has a reference current source (10,11,12,Rr) connected to a printer system reference voltage (Vr) for providing a second reference voltage (Vr) for an individual, integrated circuit chip (IC). A plurality of substantially similar field effect transistors (13) have their gates connected to the chip reference voltage (Vr) for providing substantially similar current to each of a plurality of light emitting diodes (14). The current is enabled to each such LED (14) by the presence or absence of a data signal (D). A reference resistor (Rr) in the reference current source permits adjustment so that each of a plurality of integrated circuit chips (IC) 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 (14).</p> |
