Heating device for heating recording material, and image forming apparatus having the same

An image forming apparatus comprising:

• an image forming unit configured to form an image;
• and
• a thermal fixing device configured to thermally fix the image onto a sheet, the thermal fixing device comprising:
• a base plate;
• a plurality of heating resistor members disposed in a longitudinal direction of said base plate;
• a plurality of power supply electrodes disposed on one longitudinal end portion of said base plate, said plurality of power supply electrodes disposed on the one longitudinal end portion of said base plate including power supply electrodes configured to independently supply electric power to heating resistor members of said plurality of heating resistor members, and also including another power supply electrode connected to said plurality of heating resistor members;
• and
• a plurality of electrically conductive parts configured to connect said plurality of heating resistor members and said plurality of power supply electrodes to one another,
• wherein said plurality of electrically conductive parts are formed such that electrically conductive parts of said plurality of electrically conductive parts that are capable of having larger amounts of current flow therethrough have larger cross-sectional areas thereof with respect to a perpendicular direction of the longitudinal direction of said base plate.

A heating device comprising:

• a base plate;
• a first heating member disposed along a longitudinal direction of said base plate;
• a second heating member disposed along the longitudinal direction of said base plate, and having such a resistance value as that a current value flowing through said second heating member is greater than a current value flowing through said first heating member;
• a first power supply electrode connected to one end portion of said first heating member so as to supply electric power to said first heating member;
• a second power supply electrode connected to one end portion of said second heating member so as to supply electric power to said second heating member independently of said first heating member;
• a third power supply electrode connected to the other end portion of said first heating member and the other end portion of said second heating member so as to supply electric power to said first heating member and said second heating member;
• a first electrically conductive part connected to between the one end portion of said first heating member and said first power supply electrode;
• a second electrically conductive part connected to the one end portion of said second heating member and having a cross-sectional area thereof with respect to a perpendicular direction to the longitudinal direction of said base plate larger than a cross-sectional area of said first electrically conductive part with respect to the perpendicular direction to the longitudinal direction of said base plate;
• and
• a third electrically conductive part connected to the other end portion of said first heating member and the other end portion of said second heating member, and having a cross-sectional area thereof with respect to the perpendicular direction to the longitudinal direction of said base plate larger than a cross-sectional area of said second electrically conductive part with respect to the perpendicular direction to the longitudinal direction of said base plate.

An image forming apparatus comprising:

• an image forming unit configured to form an image;
• and
• a thermal fixing device configured to thermally fix the image onto a sheet,
• the thermal fixing device comprising:
• a base plate;
• a first heating member disposed along a longitudinal direction of said base plate;
• a second heating member disposed along the longitudinal direction of said base plate, and having such a resistance value as that a current value flowing through said second heating member is greater than a current value flowing through said first heating member;
• a first power supply electrode connected to one end portion of said first heating member so as to supply electric power to said first heating member;
• a second power supply electrode connected to one end portion of said second heating member so as to supply electric power to said second heating member independently of said first heating member;
• a third power supply electrode connected to the other end portion of said first heating member and the other end portion of said second heating member so as to supply electric power to said first heating member and said second heating member;
• a first electrically conductive part connected to between the one end portion of said first heating member and said first power supply electrode;
• a second electrically conductive part connected to the one end portion of said second heating member and having a cross-sectional area thereof with respect to a perpendicular direction to the longitudinal direction of said base plate larger than a cross-sectional area of said first electrically conductive part with respect to the perpendicular direction to the longitudinal direction of said base plate;
• and
• a third electrically conductive part connected to the other end portion of said first heating member and the other end portion of said second heating member, and having a cross-sectional area thereof with respect to the perpendicular direction to the longitudinal direction of said base plate larger than a cross-sectional area of said second electrically conductive part with respect to the perpendicular direction to the longitudinal direction of said base plate.