Patent ID: 7145584

Claim:
A printer provided with a thermal head, the thermal head comprising: a substrate; an insulating layer disposed over the substrate and including a projection in a portion of the insulating layer; a plurality of heater elements arrayed on the projection and formed of an exothermic resistor; and independent electrodes and a common electrode for supplying power to the exothermic resistor, wherein at least a portion of a top surface of the substrate is coated with a protective sealing member, the sealing member being disposed closer to a base end of the substrate than the heater elements, wherein, in a state in which the heater elements are in contact with a platen disposed in a main body of the printer, the thermal head is attached to the main body such that the following conditional formulas are satisfied: H 1≦ H≦H max ; Formula 1: H max =H 1+ H 2= L tan(θ 1 +θ 3 ); and Formula 2: θ′=θ 2 −θ 1 =3±1(°) Formula 3: wherein L denotes a length between a first perpendicular line and a second perpendicular line in the arrayed direction of the heater elements, the first perpendicular line being perpendicular to the top surface of the substrate and extending through a contact point between the heater elements and the platen, the second perpendicular line being perpendicular to the top surface of the substrate and extending through a peak point of the sealing member, wherein H denotes a height from the top surface of the substrate to the peak point of the sealing member, wherein H 1 denotes a height measured along the second perpendicular line from the top surface of the substrate to a tangent line between the platen and the heater elements, the second perpendicular line being perpendicular to the top surface of the substrate and extending through the peak point of the sealing member, wherein H 2 denotes a height measured along the second perpendicular line from the tangent line between the platen and the heater elements to a conveying path of a medium used for recording disposed the closest to the thermal head, wherein θ 1 denotes an angle formed between the tangent line of the platen and the heater elements and the top surface of the substrate, wherein θ 2 denotes a slope angle of the projection with respect to the tangent line of the platen and the heater elements, wherein θ 3 denotes an angle formed between the tangent line of the platen and the heater elements and the conveying path of the medium used for recording disposed the closest to the thermal head, and wherein θ′ denotes a head-returning angle.