Patent ID: 9037023
Filing Date: 2015-05-19
Classification: G03G

Abstract:
1. A fixing device comprising: a heating rotating member for heating a paper sheet to which toner is transferred; a pressing rotating member which is pressed to the heating rotating member so as to form a nip; a motor which is rotatable in forward and backward directions; a fixing pressure adjustment mechanism which is driven by the motor and moves a rotating member to be moved as one of the heating rotating member and the pressing rotating member in a pressure increasing direction and in a pressure decreasing direction between predetermined first and second positions, in accordance with a rotation direction of the motor, so as to adjust a fixing pressure as a pressure of the nip; a control section including a control device which issues an instruction of voltage to be applied to the motor by software control in accordance with the rotation direction of the motor; a motor drive section which controls the voltage to be applied to the motor on the basis of the instruction from the control section; a detecting member which detects that the rotating member to be moved that has been moved by the fixing pressure adjustment mechanism reaches the first position and which is not connected to the control device; and a stop control circuit which receives an output of the detecting member and stops the motor without software control when the detecting member detects that the rotating member to be moved reaches the first position, wherein the motor has at least two terminals, one of which is connected to a first signal line while the other terminal is connected to a second signal line, the first signal line and the second signal line are connected to the motor drive section, when the motor drive section rotates the motor in a direction such that the rotating member to be moved is directed to the first position, the motor drive section applies a voltage to the first signal line and connects the second signal line to the ground, when the motor drive section rotates the motor in a direction such that the rotating member to be moved is directed to the second position, the motor drive section connects the first signal line to the ground and applies a voltage to the second signal line, the stop control circuit is connected to the first signal line, works when a voltage is applied to the first signal line, and is not connected to the second signal line, the stop control circuit includes a first transistor connected to the first signal line and a second transistor connected to the first transistor in series with respect to the first signal line, the first transistor is turned on until the rotating member to be moved reaches the first position, so as to apply a voltage to the motor to rotate in the direction such that the rotating member to be moved is directed to the first position, and is turned off to stop to apply the voltage to the motor when the detecting member detects that the rotating member to be moved reaches the first position, and the second transistor becomes turned on when the first transistor is turned off, so as to permit current to flow when the motor stops.