Method and apparatus for heating print medium in an ink-jet printer

Abstract

A method and apparatus for heating the print medium in a ink-jet printer to reduce printing defects in a relatively cold machine. The printer includes a print area heater which in a steady state condition for a given print medium is energized at a first heating level. Under cold start conditions, for an initial plot, the hater is overdriven at a second heating level. Under a multiple-pass printing mode, the hating drive is gradually reduced during an initial portion of the initial plot, until the first heating level is achieved. The heater drive level remains at the first heating level for subsequent plots in a given batch. For single-pass print modes, the heater drive level remains at the second level for the entire initial plot in a batch, and is reduced to the first level for subsequent plots. The printer has a preheater along the medium path, with an unheated area along the path between the print area and the preheater. To further improve print quality when printing along top leading edge margins, the paper is initially advanced until the leading edge is over the print area heater and left for a first time interval. The paper is then retracted to position the paper area initially located over the unheated area of the paper path during the first interval over the preheater. The paper is left in the retracted position during a second time interval, and then advanced to the print area to commence printing operations.