Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1998-11-16
2001-04-24
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
Reexamination Certificate
active
06222301
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a motor control apparatus and an image forming apparatus using it.
2. Related Background Art
In an apparatus using a motor as a driving source, generally, it is required that a driving member which is driven by the motor is repetitively operated while keeping a predetermined precision level. Particularly, in an image forming apparatus in an electrophotographic system, to form an image of high precision, it is required to use a motor having higher rotating precision as a motor for driving a photosensitive member or for driving a transfer member. To accomplish such an object, an ultrasonic motor is used as a motor for driving the photosensitive member or for driving the transfer member.
The ultrasonic motor, is a motor using an ultrasonic vibration, proposed by JP-A-58-14682. As described in detail in JP-A-63-1379, JP-A-60-176470, JP-A-59-204477, or the like with respect to the driving of such a motor, a stable rotating performance of a constant speed is realized by periodically adjusting the drive frequency or the driving voltage and the pulse width of the driving voltage in accordance with a signal of speed detecting means, such as an encoder signal or the like.
On the other hand, abrasion of the motor of the apparatus and motor driving members, due to their use over a long period of time, which is caused by the occurrence of friction between the members when the motor of the apparatus and the motor driving members which are driven by the motor are made operative, is unavoidable. Even if a motor having high precision driving characteristics, such as an ultrasonic motor is used, such abrasion is not exceptional. Therefore, hitherto, when the abrasion of the motor driving members progresses and a stable constant speed rotation at a target speed in the stationary state becomes impossible, a countermeasure, such as replacement, reparation, or the like, by a serviceman or the like, is performed.
However, in the conventional motor control apparatus as mentioned above, the stable driving of the apparatus main body becomes disabled for a period of time until a countermeasure, such as replacement, reparation, or the like, by a serviceman or the like is performed after the stable rotation of the motor driving members becomes impossible due to the abrasion of the members. Particularly, in the case of an image forming apparatus having such a motor control apparatus, high quality image formation cannot be performed for such a period of time. It is therefore impossible to meet a requirement by the operator to form an image in urgent for the period of time until a countermeasure, such as replacement, reparation, or the like by a serviceman, is performed.
In an image forming apparatus for a business use or the like in which it is required that the apparatus always operates without a halt, there is a problem such that the usefulness of the apparatus is diminished due to the occurrence of the inoperative time.
SUMMARY OF THE INVENTION
The invention is made to solve the foregoing problems and it is an object to provide a motor control apparatus in which, when a stable rotation of a motor becomes impossible, the apparatus main body can be tentatively driven even for a period of time until a countermeasure such as replacement, reparation, or the like by a serviceman or the like is performed and to provide an image forming apparatus having such a motor control apparatus.
The motor control apparatus and image forming apparatus of the invention are constructed as follows.
(1) A motor control apparatus comprises: rotation control means for controlling a rotational speed of a motor; detecting means for detecting a rotation error of the motor; and alarm means for warning an operator when the rotation error of the motor is detected, wherein when the rotation error of the motor is detected, the rotational speed of the motor is switched to a different speed and the motor is driven and the other portions of the apparatus main body are also driven in accordance with the switched speed.
(2) In the motor control apparatus according to the above item (1), the rotation control means can switch the rotational speed of the motor to two or more speeds.
(3) In the motor control apparatus according to the above item (1) or (2), the apparatus has memory means constructed in a manner such that when the rotational speed of the motor is switched to the different speed and the motor is driven, two or more drive control conditions to drive the other portions of the apparatus main body in accordance with the switched speed have been stored.
(4) In the motor control apparatus according to any one of the above items (1) to (3), the rotation control means controls the rotational speed of the motor by a speed feedback control using a rotational speed detection signal.
(5) In the motor control apparatus according to any one of the above items (1) to (4), the detecting means detects the rotation error of the motor on the basis of the occurrence of a difference between the rotational speed which is obtained from a rotational speed detection signal, which is used in the rotation control of the motor, and the target rotational speed.
(6) In the motor control apparatus according to any one of the above items (1) to (5), the motor is an ultrasonic motor controlled by an ultrasonic vibration control.
(7) In the motor control apparatus according to the above item (6), a rotational speed detection signal, which is used for the rotation control of the ultrasonic motor, is an encoder output signal.
(8) In the motor control apparatus according to the above item (6) or (7), a control amount by the rotation control means is either one of or both of an ultrasonic wave pulse width and an ultrasonic wave frequency.
(9) In the motor control apparatus according to any one of the above items (1) and (3) to (8), the rotation control means continuously changes the rotational speed of the motor in such a direction as to be decelerated when the rotation error of the motor is detected.
(10) In the motor control apparatus according to the above item (9), when the rotational speed of the motor is switched to the different rotational speed and the motor is driven, a rule to calculate various set values, which are necessary to decide driving conditions for driving the other portions of the apparatus main body in accordance with the switched speed, has been stored as a predetermined formula into memory means, and the driving conditions, to drive the other portions of the apparatus main body, are continuously changed in accordance with the rotational speed of the motor.
(11) In the motor control apparatus according to any one of the above items (1) to (9) in response to an alarm by the alarm means, the apparatus has selecting means for enabling the operator to select whether the driving of the apparatus is interrupted or continued, thereby enabling the operator to select whether the driving of the apparatus by the speed switching is executed or not.
(12) In the motor control apparatus according to any one of the above items (1) to (11), the alarm means is provided for an operation panel annexed to the apparatus main body.
(13) In the motor control apparatus according to any one of the above items (1) to (12), the alarm means is a public telephone line communication terminal connected to the apparatus main body.
(14) In the motor control apparatus according to any one of the above items (1) to (13), the alarm means is a network communication terminal connected to the apparatus main body.
(15) An image forming apparatus for performing an image forming operation has a motor control apparatus comprising: rotation control means for controlling a rotational speed of a motor; detecting means for detecting a rotation error of the motor; and alarm means for warning an operator when the rotation error of the motor is detected, wherein when the rotation error of the motor is detected, the rotational speed of the motor is switched to a different speed and the motor is driven and the other por
Canon Kabushiki Kaisha
Dougherty Thomas M.
Fitzpatrick ,Cella, Harper & Scinto
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