Hybrid digital image printer with halftone gray scale capability

摘要

A gray scale printer is adapted to modulate an exposure source in both amplitude and duration in accordance with an eight-bit data signal. The printer provides for modulating the amplitude of the exposure source in accordance with the six least significant bits of the data signal, and for modulating the duration of the exposure source in accordance with the two most significant bits of the data signal. Amplitude modulation may effect electrical current to the exposure source, and the duration modulation may effect pulse width of electrical current to the exposure source. The exposure source may be, for example, a laser diode or a light-emitting diode array.