Patent ID: 9655170
Date: 2017-05-16
CPC Classifications: B28B,F23Q,H05B,Y10T

Claim:
1. A ceramic heater comprising: a resistor which generates heat when energized; and a base member which extends along an axial direction and in which the resistor is embedded, the base member being formed of a ceramic material which is lower in electrical conductivity than the resistor, wherein the resistor includes a first portion extending from a forward end portion of the base member toward a rear end portion thereof, a second portion spaced from the first portion and extending from the forward end portion of the base member toward the rear end portion thereof, and a connection portion embedded in the forward end portion of the base member and connecting the first portion and the second portion; and in a cross section of the ceramic heater taken orthogonal to the axial direction, a first resistor cross section taken through the first portion of the resistor and a second resistor cross section taken through the second portion of the resistor, the first cross-section being spaced from the second cross-section, with two straight lines which are in contact with both a peripheral contour of the first resistor cross section and a peripheral contour of the second resistor cross section and which pass between the first resistor cross section and the second resistor cross section in the cross section of the ceramic heater being defined as a first straight line and a second straight line, the first resistor cross section has no protrusion on a first inner portion, the first inner portion being that portion of the contour of the first resistor cross section that is located on the side of the first resistor cross section that faces toward the second resistor cross section, the first inner portion extending from a first position at which the contour of the first resistor cross section is in contact with the first straight line to a second position at which the contour of the first resistor cross section is in contact with the second straight line, and the first resistor cross section has two or more protrusions on a first outer portion, the first outer portion being that portion of the contour of the first resistor cross section that is located on the side opposite of the first resistor cross section that faces the second resistor cross section, the first outer portion extending from the first position to the second position the protrusions in the first resistor cross section are provided near both sides of the first portion in an orthogonal direction that is perpendicular to both the axial direction of the base member and a direction where the first portion and the second portion face each other.