US 7,321,738 B2
Fixing apparatus with current control to heater
Hajime Kaji, Abiko (Japan); Toshifumi Kakutani, Toride (Japan); Satoru Ishikawa, Ryugasaki (Japan); Kazunori Miyake, Toride (Japan); and Satoru Kanno, Kashiwa (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Sep. 01, 2005, as Appl. No. 11/215,972.
Claims priority of application No. 2004-258712 (JP), filed on Sep. 06, 2004; and application No. 2004-337701 (JP), filed on Nov. 22, 2004.
Prior Publication US 2006/0051118 A1, Mar. 09, 2006
Int. Cl. G03G 15/20 (2006.01)
U.S. Cl. 399—69  [399/70; 399/328; 219/486] 1 Claim
OG exemplary drawing
 
1. A fixing apparatus including a heating portion for heat fixing an unfixed developer borne on a recording material, comprising:
a first heating member and a second heating member provided in the heating portion; and
a current control unit which controls an AC current to be supplied to the heating portion;
wherein the current control unit executes a wave number control, on the AC current supplied to the heating portion, in a unit of predetermined number of half-waves in such a manner that;
an AC current to the first heating member is supplied in a positive-negative symmetrical pattern in the unit of predetermined number of half-waves;
an AC current to the second heating member is supplied in a positive-negative symmetrical pattern in the unit of predetermined number of half-waves; and
AC currents to the first and second heating members are supplied in a positive-negative symmetrical pattern in total in the unit of predetermined number of half-waves;
the current control unit executes a wave number control in a unit of predetermined number of half-waves at each of duty ratios, at a pitch of a predetermined percentage, of the AC current supplied to the heating portion, and maintains a same duty ratio in the AC currents supplied to the first heating member and the second heating member in the unit of predetermined number of half-waves, at specified duty ratios;
the current control unit increases the duty ratio for either of the first heating member and the second heating member in the unit of predetermined number of half-waves, at a duty ratio other than the specified duty ratios; and
the current control unit increases the duty ratio alternately for the first heating member and the second heating member.