Electric heater

An electric heater comprising:

• a substrate;
• and
• a plane heating element located at a surface of the substrate and defines a part of a circular area having a center,
• wherein the plane heating element comprises a pattern portion comprising:
• a plurality tracks that define arc shapes about the center and are spaced apart from one another in a radial direction of the circular area, wherein a length of one of the plurality of tracks arranged at an outer side is greater than a length of another of the plurality of tracks arranged at an inner side relative to the outer side in the radial direction,
• a plurality of bridges that connect first and second tracks among the plurality of tracks in series, the plurality of bridges comprising a first bridge that connects the first track to one end of the second track in series, and
• a pair of electrodes that are connected to the pattern portion and define an electrode gap therebetween,
• wherein each of the plurality of tracks, the plurality of bridges, and the pair of electrodes is symmetrical with respect to a reference line that passes through the center, and
• wherein the pattern portion defines a gap between any two bridges among the plurality of bridges that face each other with respect to the reference line, the gap being narrower than the electrode gap.