With the aspect shown in FIG. 5(e), the width of the bent portion 85b2 is constant, but a portion 85b6 having a predetermined length that includes the vertex portion is thicker, and the resistance of this portion 85b6 is smaller than the resistance of the other portion of the heating wire 8. This makes it possible to suppress locally high temperatures in the vicinity of the vertex portion of the bent portion 85b2. The thickness of this portion is preferably 1.2 to 40 μm, and more preferably 4.5 to 30 μm, for example. Also, the thickness of this portion is preferably 1.2 times or more, more preferably 1.5 times or more, and particularly preferably 2.0 times or more the thickness of the other portion thereof. However, if the thickness is excessively large, the amount of ink for printing will be too large and the ink will spread, and the heat generation suppression effect will decrease. Therefore, the thickness of this portion is preferably 3 times or less the thickness of the other portion. Note that the length L of a thick portion can be the same as that described in 4-1 above.
4-5. Aspect 5 of Bent Portion
