Thermal head and ink transfer printer using same

A thermal line head comprising

• an electrically-insulated base member;
• plural sets of at least two electric resistance elements formed on a surface of said base member and aligned with each other, wherein one set of said plural sets of at least two electric resistance elements contains four electric resistance elements, two of said four electric resistance elements having first identical resistance values, a remaining two of said four electric resistance elements having second identical resistance values different from said first identical resistance values;
• and
• a driver circuit that selectively and electrically energizes said at least two electric resistance elements in each set in accordance with an associated digital image-pixel signal and an associated digital gradation-signal,
• wherein, when said digital image-pixel signal has a value “0”, none of said at least two electric resistance elements in a corresponding set are electrically energized, and, when said digital image-pixel signal has a value “1”, the selective and electrical energization of said at least two electric resistance elements in said corresponding set are performed in accordance with values of said digital gradation-signal, whereby a total thermal energy output of each of said plural sets of at least two electric resistance elements is stepwisely adjustable.

An ink transfer printer comprising:

• a thermal line head comprising:
• a) an electrically-insulated base member;
• plural sets of at least two electric resistance elements formed on a surface of said base member and aligned with each other;
• and
• b) a driver circuit that selectively and electrically energizes said at least two electric resistance elements in each set in accordance with an associated digital image-pixel signal and an associated digital gradation-signal,
• wherein, when said digital image-pixel signal has a value “0”, none of said at least two electric resistance elements in a corresponding set are electrically energized, and, when said digital image-pixel signal has a value “1”, the selective and electrical energization of said at least two electric resistance elements in said corresponding set are performed in accordance with values of said digital gradation-signal, whereby a total thermal energy output of each of said plural sets of at least two electric resistance elements is stepwisely adjustable;
• a frame member, having an opening, securely provided on said thermal line head such that said plural sets of at least two electric resistance elements are encompassed by said opening of said frame member;
• and
• a sheet of film that covers said frame member such that said opening of said frame member is defined as an ink space filled with ink, said film sheet including a plurality of fine pores arranged along an alignment of said plural sets of at least two electric resistance elements, at least one of said plurality of fine pores being allocated to and associated with each of said plural sets of at least two electric resistance elements,
• wherein, when the electric resistance elements in each set are selectively and electrically energized to generate thermal energy, an ink drop is formed on said film sheet from one of said plurality of fine pores corresponding to the generation of the thermal energy, with a size of said ink drop being stepwisely varied in accordance with a value of said digital gradation-signal.