Head controller of thermal printer and thermal printer printing method

A printer printing an image by a line head, comprising a line head controller, wherein the line head controller controls:

• generating gradation data representing image gradations by stages;
• alternately selecting each image data the number of which corresponds to the number of head elements of said line head, and data of value 0, and switching selection as to which data is to be selected, the image data or the data of value 0, every time a value of said gradation data changes;
• and
• feeding a signal indicating a comparison result of comparing said selected data with said gradation data to said line head.

The line head controller of a thermal printer printing an image by a line head, comprising:

• gradation generation means for generating gradation data representing image gradations by stages;
• selection means for alternately selecting each image data the number of which corresponds to the number of head elements of said line head, and data of value 0, and for switching selection as to which data is to be selected, the image data or the data of value 0, every time a value of said gradation data changes;
• and
• comparison means for feeding a signal indicating a comparison result of comparing said selected data with said gradation data to said line head.

A thermal printer printing an image by a line head, comprising a line head controller, said line head controller comprising:

• gradation generation means for generating gradation data representing image gradations by stages;
• selection means for alternately selecting each image data the number of which corresponds to the number of head elements of said line head, and data of value 0, and for switching selection as to which data is to be selected, the image data or the data of value 0, every time a value of said gradation data changes;
• and
• comparison means for feeding a signal indicating a comparison result of comparing said selected data with said gradation data to said line head.

A printer printing method of printing an image by a line head, comprising:

• a gradation generation step of generating gradation data representing image gradations by stages;
• a selection step of alternately selecting each image data the number of which corresponds to the number of head elements of said line head, and data of value 0, and of switching selection as to which data is to be selected, the image data or the data of value 0, every time a value of said gradation data changes;
• and
• a comparison step of feeding a signal indicating a comparison result of comparing said selected data with said gradation data to said line head.