Patent ID: 8110783

Claim:
A tubular heater comprising: a tubular insulating substrate; a continuous heat-generating resistance element formed in a predetermined pattern on one surface of the insulating substrate; and a first lead wire connected to one end of the heat-generating resistance element and a second lead wire connected to an opposite end of the heat-generating resistance element, the first and second lead wires extending from one end of the tubular insulating substrate in a common axial direction of the tubular insulating substrate, wherein the first and second lead wires are disposed in diametrically opposed relation to each other about a central axis of the tubular insulating substrate, wherein when viewed in a development view, the pattern of the heat-generating resistance element is arranged such that the heat-generating resistance element runs from one of the first and second lead wires in a direction way from the other of the first and second lead wires and returns to the other of the first and second lead wire, and wherein the heat-generating resistance element has a first meandering portion extending in a circumferential direction of the tubular insulating substrate from the first lead wire toward the second lead wire, a second meandering portion extending in the circumferential direction of the tubular insulating substrate from the second lead wire in a direction away from the first lead wire, and a linear connecting portion extending in the circumferential direction of the tubular insulating substrate between ends of the first and second meandering portions which are located remote from the first and second lead wires, respectively.