Patent ID: 8259144

Claim:
A thermal printing apparatus, comprising: a first plate having an array of heating elements disposed thereon, individual heating elements within the array of heating elements separated from one another by an insulating medium; at least one additional plate having at least one additional array of heating elements disposed thereon, individual heating elements within the at least one additional array of heating elements being separated from one another by an additional insulating medium; wherein the first plate and the at least one additional plate are configured substantially adjacent to each other, with the array of heating elements and the second array of heating elements facing one another, to form a slot between the first plate and the at least one additional plate, said slot adapted to accept a thermochromic printing medium; and wherein the array of heating elements, the at least one additional array of heating elements, the insulating medium, and the at least one additional insulating medium are configured such that actuation of any one individual heating element marks the thermochromic medium and is sufficiently insulated by the insulating medium or the at least one additional insulating medium that it does not to bleed to an unintended region of the thermochromic medium.