A method of printing in which, when an image is divided to be printed into a plurality of lines, the feeding amount of a printing medium is equalized in each line for eliminating a feeding error of the printing medium to print a high-quality image. The image to be printed in a top line of the printing medium is formed into a printable image by ink ejection ports located at an upstream side with respect to a printing medium feeding direction of a print head, and a width of the image printed in the top line is an adjusting width for unifying the width of image printed in other lines to a specified width according to the print head.

A thermal printer includes an upstream conveying device and a downstream conveying device that are respectively arranged upstream and downstream of a recording device. The upstream conveying device conveys a recording sheet while a first half of a print region that is adjacent to a print start edge of the recording sheet is being printed on, and the downstream conveying device conveys the recording sheet while a second half of a print region that is adjacent to a print end edge of the recording sheet is being printed on, so that the entire region of the recording sheet can be printed on without leaving margins. In addition, upstream and downstream guides are provided to make the movement of the recording sheet stable during printing.

To avoid the effects of unwanted variations in the pen-to-paper spacing of a printer, deliberate and effectively randomised variations are introduced by using paper drive rollers (20) with an irregular cross-section. In one embodiment, an overdrive roller comprises rollers (23-26) the surfaces of which incorporate flattened portions (27, 28) of differing widths and spacings. The number, size and/or spacing of the portions (27, 28) differ from roller to roller. Instead or in addition, variations may be incorporated into a pinch wheel (101), platen (15) or other component of the paper drive system.