Film heater
A film heater has a transparent conductive portion including: at least one non-conductive portion that has electrical insulation properties and extends in a direction intersecting a vibration direction of an electric field included in a radio wave transmitted from a radio wave transmitter-receiver; and a heat generator that generates heat by being energized and that transmits light. The film heater has: a first electrode connected to the heat generator; and a second electrode connected to the heat generator. The heat generator includes at least one conductive portion that is adjacent to the non-conductive portion and generates heat by a current flowing along a direction in which the non-conductive portion extends when the heat generator is energized by the first electrode and the second electrode.
1 . A film heater comprising:
a transparent conductive portion including:
at least one non-conductive portion that has electrical insulation properties and extends in a direction intersecting a vibration direction of an electric field included in a radio wave transmitted from a radio wave transmitter-receiver; and
a heat generator that generates heat by being energized and that transmits light;
a first electrode connected to the heat generator; and
a second electrode connected to the heat generator, wherein
the heat generator includes at least one conductive portion that is adjacent to the non-conductive portion and generates heat by a current flowing along a direction in which the non-conductive portion extends when the heat generator is energized by the first electrode and the second electrode, and
the first electrode is disposed outside the heat generator with respect to the second electrode and surrounds the second electrode, the film heater further comprising:
an inter-electrode non-conductive portion having electrical insulation properties and disposed between the first electrode and the second electrode.
2 . The film heater according to claim 1 , further comprising:
a first lead wire connected to the first electrode; and
a second lead wire connected to the second electrode, wherein
the first lead wire is disposed, together with the second lead wire, on one side in the direction intersecting the vibration direction of the electric field.
3 . The film heater according to claim 1 , wherein the first electrode, the second electrode, and the inter-electrode non-conductive portion extend in a direction along an outer edge portion of the heat generator.
4 . The film heater according to claim 3 , wherein the inter-electrode non-conductive portion has a boundary portion between the inter-electrode non-conductive portion and the heat generator, and
the boundary portion is disposed between a connection portion of the first electrode at which the first electrode and the heat generator are connected to each other and an end of the second electrode.
5 . The film heater according to claim 1 , wherein the first electrode and the second electrode are disposed outside an irradiation range of the radio wave transmitted from the radio wave transmitter-receiver.
6 . The film heater according to claim 1 , wherein the transparent conductive portion includes a plurality of non-conductive portions,
the plurality of non-conductive portions is arranged in parallel in the vibration direction of the electric field,
the heat generator includes a plurality of conductive portions, and
the plurality of conductive portions is arranged in parallel in a parallel arrangement direction of the non-conductive portions.
7 . The film heater according to claim 6 , wherein a length of each of the plurality of conductive portions in a direction in which the non-conductive portions extend is changed in the parallel arrangement direction of the non-conductive portions from a center of the transparent conductive portion, and
a cross-sectional area of each of the plurality of conductive portions on a cross-section orthogonal to a direction in which currents flow through the conductive portions is changed in the parallel arrangement direction of the non-conductive portions from the center of the transparent conductive portion, in a same manner as the length of the conductive portion.