Recording head driving device for printer

Abstract

A printer has a recording head with a first plurality of recording elements being disposed in a main scan direction. The recording head records the first plurality of pixels on a recording sheet at a time. Each pixel has a second plurality of sub-lines disposed in a sub scan direction, and the number of dot-recorded sub-lines changes with tonal steps. A shift register has the first plurality.times.8-bit latches for latching sequentially inputted first plurality of image data as parallel data. The M image data are sent via a latch array to a comparator array, and set to respective the first plurality.times.8-bit magnitude comparators constituting the comparator array. A counter is incremented each time a platen drum holding a recording sheet is rotated by a one sub-line amount, and the position of each sub-line within one pixel is detected. Each 8-bit magnitude comparator maintains each recording element in a conduction enabled state until a count of the counter exceeds the contents of the image data. As a strobe signal is supplied to the gate array during this conduction enabled state, each recording element is powered. In a preferred embodiment, there are provided the first plurality.times.8-bit counters having a function of presetting a complement of input data and a count function, and an array of the first plurality of decoders. Each decoder maintains each recording element in a conduction enabled state until each 8-bit counter counts up to a maximum count 'of the second plurality'.