Electricity: motive power systems – Switched reluctance motor commutation control
Reexamination Certificate
2002-03-27
2004-07-13
Mullins, Burton S. (Department: 2834)
Electricity: motive power systems
Switched reluctance motor commutation control
C310S06800R, C310S06800R, C318S286000, C318S626000, C318S466000
Reexamination Certificate
active
06762574
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a brushless motor, a control method for the brushless motor, a light deflection device, and a control method for the light deflection device, which are rich in expandability of drive control.
Generally, in an image-forming apparatus such as a laser printer, a laser copier, a laser facsimile, and a composite device thereof, a light beam emitted from a light source such as a semiconductor laser is reflected and deflected by the mirror surface of a polygonal mirror rotating at a predetermined speed, scanned on an image recording medium such as a photosensitive drum, thereby records and forms an image.
The polygonal mirror is installed on the rotor of a brushless motor so as to structure a light deflection device and arranged in an image-writing system of an image-forming apparatus. A plurality of drive coils for acting rotary power to the rotor are controlled by a control signal from a drive circuit, thus the light deflection device controls the rotation of the polygonal mirror.
Therefore, the brushless motor constituting the light deflection device has a wire connection means, serving as a connecting port, for electrically connecting between the drive circuit and the drive coils and when the light deflection device is to be arranged in the writing unit, the wire connection means is electrically connected to the drive circuit.
Conventionally, the drive control of the brushless motor is executed by the drive circuit connected to the wire connection means, so that there is a disadvantage that the control function held by the drive circuit connected to the wire connection means is restricted.
Therefore, for example, when the drive coils are electrically connected to the drive circuit for controlling start-up operation and steady-rotating operation, the start-up operation and steady-rotating operation are just controlled by the drive circuit, so that when a request for a function for rapidly reducing the rotation of the motor is generated later, it is necessary to remove the drive coils together with the drive circuit, replace the drive circuit with a drive circuit additionally having a brake control function, and electrically connect it to the drive coils newly, thus a very complicated operation must be forcibly performed.
SUMMARY OF THE INVENTION
To overcome the abovementioned drawbacks in conventional brushless motors, the first object of the present invention is to provide a brushless motor rich in expandability of a control function capable of easily adding control, which cannot be executed by one drive circuit.
Further, the second object of the present invention is to provide a control method for a brushless motor capable of executing optimal drive control respectively in each mode from control of start-up operation and steady-rotating operation to control of deceleration and improving the efficiency and reliability of the motor.
Still further, the third object of the present invention is to provide a light deflection device rich in expandability of a control function capable of easily adding control, which cannot be executed by a single drive circuit.
Still further, the fourth object of the present invention is to provide a control method for a light deflection device capable of respectively executing optimal drive control in each mode from control of start-up operation and steady-rotating operation to control of deceleration and improving the efficiency and reliability of the motor.
Accordingly, to overcome the cited shortcomings, the abovementioned objects of the present invention can be attained by light deflection devices and brushless motors described as follow.
(1) A light deflection device for deflecting a light beam, comprising: a polygon mirror to reflect the light beam; a rotor, having a magnet, to rotate the polygon mirror attached to the rotor; a stator on which a plurality of drive coils are fixed so as to generate a rotational force between the magnet and the drive coils; and a plurality of connecting ports through which the plurality of drive coils are electronically coupled to a plurality of drive circuits, each of which drives the drive coils while controlling the rotational force to be generated between the magnet and the drive coils.
(2) The light deflection device of item 1, wherein the plurality of connecting ports include a first connecting port to which a first drive circuit is coupled, and a second connecting port to which a second drive circuit is coupled; and wherein the first drive circuit controls the rotational force during a start-up operation and a steady-rotating operation of the rotor, while the second drive circuit controls the rotational force during a decelerating operation of the rotor.
(3) The light deflection device of item 1, wherein the plurality of connecting ports include a first connecting port to which a first drive circuit is coupled, and a second connecting port to which a second drive circuit is coupled; and wherein the first drive circuit controls the rotational force during a start-up operation and a steady-rotating operation of the rotor, while the second drive circuit also controls the rotational force during the start-up operation of the rotor, serving as an auxiliary driving source.
(4) The light deflection device of item 1, wherein the plurality of connecting ports include a first connecting port to which a first drive circuit is coupled, a second connecting port to which a second drive circuit is coupled, and a third connecting port to which a third drive circuit is coupled; and wherein the first drive circuit controls the rotational force during a start-up operation and a steady-rotating operation of the rotor, while the second drive circuit controls the rotational force during a decelerating operation of the rotor, and further, the third drive circuit also controls the rotational force during the start-up operation of the rotor, serving as an auxiliary driving source.
(5) The light deflection device of item 1, wherein the light deflection device is employed in an image-writing system of an image-forming apparatus.
(6) A method for controlling a light deflection device, which comprises a polygon mirror to reflect a light beam, a rotor having a magnet, to rotate the polygon mirror attached to the rotor, a stator on which a plurality of drive coils are fixed so as to generate a rotational force between the magnet and the drive coils and a plurality of connecting ports through which the plurality of drive coils are electronically coupled to a plurality of drive circuits, the method comprising the steps of: controlling the rotational force during a start-up operation and a steady-rotating operation of the rotor by a first drive circuit included in the plurality of drive circuits; and controlling the rotational force during a decelerating operation of the rotor by a second drive circuit included in the plurality of drive circuits.
(7) A method for controlling a light deflection device, which comprises a polygon mirror to reflect a light beam, a rotor having a magnet, to rotate the polygon mirror attached to the rotor, a stator on which a plurality of drive coils are fixed so as to generate a rotational force between the magnet and the drive coils and a plurality of connecting ports through which the plurality of drive coils are electronically coupled to a plurality of drive circuits, the method comprising the steps of: controlling the rotational force during a start-up operation and a steady-rotating operation of the rotor by a first drive circuit included in the plurality of drive circuits; and controlling the rotational force during the start-up operation of the rotor by a second drive circuit included in the plurality of drive circuits, in such a manner that the second drive circuit serves as an auxiliary driving source.
(8) A method for controlling a light deflection device, which comprises a polygon mirror to reflect a light beam, a rotor having a magnet, to rotate the polygon mirror attached to the rotor, a stator on which a plurality of drive coils are fixed
Kobayashi Hiroshi
Kurosawa Takaaki
Frishauf Holtz Goodman & Chick P.C.
Konica Corporation
Mullins Burton S.
Pham Leda T.
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