JP2753181B2 - Polygon scanner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygon scanner, and more particularly, to a polygon scanner capable of reducing the cost by devising a structure of a motor for rotating a polygon mirror.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a laser printer or a digital copier is provided with a polygon scanner for deflecting and scanning a beam. High speed rotation is required to meet the demand. As a conventional polygon scanner of this type, for example, there is one as shown in FIG. In FIG. 5, reference numeral 10 denotes a motor housing, 11 denotes a fixed shaft pedestal that forms the bottom of the motor housing 10, and a fixed shaft 13 is vertically fitted and fixed to the center of the fixed shaft pedestal 11.

The outer periphery of the fixed shaft 13 has a radial bearing surface 14
(Dynamic pressure air bearings) are provided, and a pair of herringbone grooves 16 and 17 for generating dynamic pressure are formed on the radial bearing surface 14 at regular intervals in the circumferential direction. Further, the radial bearing surface 14 faces the inner peripheral surface 21a of the cylindrical rotary shaft 21,
The rotation shaft 21 is rotatable with respect to the fixed shaft 13 by separating the radial bearing surface 21 from the inner peripheral surface at a predetermined interval.

A mirror receiving flange is provided above the rotating shaft 21.
22 is formed, and a mirror holder 23 and a polygon mirror 25 are attached. The mirror retainer 23 holds a magnet 32 constituting the axial magnetic bearing 30 at the center thereof. The axial bearing 30 is composed of three magnets 31, 32, 33 repelling each other on the axis of the fixed shaft 13, and the magnet 31 is located above the magnet 32 in an upper case.
When the magnet 33 is fixed to the upper end of the fixed shaft 13, the rotating body 20 including the rotating shaft 21, the mirror holder 23, the polygon mirror 25 and the magnet 32 is fixed to the fixed shaft 13.
It is urged to float upward from 13 and is supported without contact.

On the other hand, reference numeral 50 denotes an axial gap type surface-facing brushless motor for driving the polygon mirror 25. The motor 50 has a rotor magnet assembly 51 fixed to the rotating shaft 21 and an armature coil portion 52 opposed to the lower surface thereof and spaced apart from the rotor magnet assembly 51 by a predetermined distance in the axial direction. And a hall element 53, and the rotor magnet assembly 51 is provided with a field magnet 51a.
Are integrally mounted on the rotating shaft 21 by the yoke 51b. Reference numeral 56 denotes a fixed yoke.

The stator coil section 52 is mounted on a coil board 54, and the coil board 54 is connected to a motor driving circuit element (not shown) via a harness 55. For this reason, the stator coil section 52 can be excited by the motor drive circuit element in a predetermined excitation method to rotate the rotor magnet assembly 51 and rotate the rotating shaft 21 and the polygon mirror 25 (the rotating body 20). .

[0007]

However, in such a conventional polygon scanner, a printed circuit board 54 on which a stator coil 52 and a hall element 53 are mounted is provided independently of a motor driving circuit element. Since the printed circuit board 54 and the motor driving circuit element were connected via the harness 55, the harness 55 became longer,
There is a problem that the cost of the polygon scanner increases.

In addition, the printed circuit board and the circuit element for driving the motor must be separately inspected and managed, which causes a problem that the inspection and management costs increase. In view of the above, according to the present invention, a harness can be greatly reduced and cost can be reduced by integrally mounting a driving circuit element for driving a motor unit on a polygon scanner, and inspection and management can be facilitated by simplifying inspection and management. It is an object of the present invention to provide a scanner motor that can reduce management costs.

[0009]

According to the first aspect of the present invention,
In order to solve the above problems, a rotating shaft having a field magnet and a polygon mirror on an outer peripheral portion, a coil substrate on which a plurality of drive coils are fixed opposite to the field magnet, and a dynamic pressure air bearing are provided. a stationary shaft for rotatably supporting the rotary shaft Te, a housing for supporting the said fixed shaft, said dynamic
It is arranged on the outer periphery of the rotating shaft so as to surround the compressed air bearing.
And is fixed to the housing.
A cover that hermetically seals the dynamic pressure air bearing, and a polygon scanner constituting a motor unit for rotating a rotating shaft by a field magnet and a drive coil, wherein a concave portion is formed at an end of the housing,
The drive circuit element is housed in the recess by attaching a control circuit board having a drive circuit element to an end face of an outer peripheral portion of the housing surrounding the recess.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, a rotating shaft having a field magnet and a polygon mirror on an outer peripheral portion, and a plurality of drive coils opposed to the field magnet are fixed. A coil substrate, a magneto-electric conversion element mounted on the coil substrate and detecting that a drive coil is excited, a fixed shaft rotatably supporting a rotating shaft via a dynamic pressure air bearing, and the dynamic pressure air. I will surround the bearing
Comprising a cover disposed on the outer periphery of the sea urchin rotation axis, a magnetic-field magnet, the polygon scanner which constitutes the motor portion for rotating the rotary shaft by the drive coil and the magneto-electric transducer, of the coil substrate- Part of the cover
A motor extends outward from the outer peripheral portion and a motor
Attach a drive circuit element to drive the
An elastic member is interposed between the oil substrates .

[0011]

According to the first aspect of the present invention, the concave portion is formed at the end portion of the housing, and the control circuit board having the driving circuit element is attached to the end surface of the outer peripheral portion of the housing surrounding the concave portion, whereby the driving portion is formed. The circuit element is housed in the recess. Therefore, there is no need to extend the harness from the motor unit to the outside as in the conventional case, and the length of the harness is significantly reduced, and the cost of the polygon scanner is reduced. In addition, since the driving circuit elements are integrally attached to the polygon scanner, the inspection and management of the polygon scanner become very easy, and the inspection and management costs are reduced. In addition, since the polygon scanner having the dynamic pressure air bearing is used for high-speed rotation, the temperature of the motor unit rises sharply. However, according to the present invention, the control having the driving circuit element on the end surface of the outer peripheral portion of the housing surrounding the recess is performed. Since the circuit board is mounted, the surface area of the housing can be enlarged, and the outer peripheral portion of the housing can function as a heat radiating portion, and the heat radiating effect can be enhanced. In addition, the motor current increases due to the high speed rotation of the polygon scanner, and a large drive circuit element is required.In the present invention, however, the drive circuit element is housed in a recess formed at the end of the housing, so that a large drive circuit element is required. The area of the control circuit board can be reduced by mounting the drive circuit element upright on the control circuit board, and the polygon scanner can be reduced in size by bringing the end surface of the recess close to the control circuit board. . In addition, dynamic pressure air shaft
A cover is arranged on the outer periphery of the rotating shaft to surround the receiver,
The cover is fixed to the housing and the housing is
Since the air bearing is sealed, dust
Etc. can be prevented from being mixed in,
Reliability can be improved.

According to the second aspect of the present invention, one of the coil substrates is provided.
Extending outward from the outer peripheral portion of the cover, and
A drive circuit element for driving the motor was mounted
In the conventional manner is not necessary to extend the harness from the motor unit to the outside, the harness is not required, the cost of the polygon scanner is reduced. In addition, since the driving circuit elements are integrally attached to the polygon scanner, the inspection and management of the polygon scanner become very easy, and the inspection and management costs are reduced. Also, large motor current
Drive circuit elements that generate a large amount of heat are required
However, this drive circuit element is disposed on the outer peripheral portion of the cover.
Therefore, the rise in temperature inside the cover can be reduced.
Wear. An elastic member is interposed between the cover and the coil substrate.
To prevent dust from entering the dynamic pressure air bearing from the outside.
Can prevent the dynamic pressure air bearing damage or bearing
To prevent polygon scanners from deteriorating
Can be improved. In addition, field magnets
The drive coil facing the
Sealed from the outside by an elastic member,
Dynamic pressure air shaft without interposing other elastic members between drive coils
Since dust can be prevented from entering the receiver,
Data efficiency can be prevented from lowering.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
1 to 4 show an embodiment of the polygon scanner according to the first or second aspect of the present invention. First, the configuration will be described. In FIG. 1, reference numeral 61 denotes a motor housing, and a recess 61a is formed in the outer peripheral portion on the bottom rear surface of the housing 61. Reference numeral 62 denotes a fixed shaft pedestal that forms the bottom of the motor housing 61. A fixed shaft 63 is vertically fitted and fixed to the center of the fixed shaft pedestal 61.

On the outer periphery of the fixed shaft 63, a radial bearing surface 64
(Dynamic pressure air bearings) are provided, and a pair of herringbone grooves 65 and 66 for generating dynamic pressure are formed on the radial bearing surface 64 at regular intervals in the circumferential direction. Further, the radial bearing surface 64 faces the inner peripheral surface 67a of the cylindrical rotating shaft 67,
The rotation shaft 67 is rotatable with respect to the fixed shaft 63 when the inner peripheral surface of the radial bearing surface 64 is separated from the inner peripheral surface by a predetermined distance.

A mirror receiving flange is provided above the rotating shaft 67.
A mirror holder 69 and a polygon mirror 70 are attached while a 68 is formed. The polygon mirror 70 is fitted on the upper outer peripheral surface 67b of the rotating shaft 67, and a bolt 71 screwed to the upper portion of the rotating shaft 67 presses the polygon mirror 70 against the flange 68 via a mirror retainer 69. The mirror retainer 69 has a magnet 73 constituting an axial magnetic bearing 72 at the center thereof, and a balance correction groove 69a for correcting imbalance of the rotating body R is formed on an upper surface thereof.

The axial bearing 72 comprises three magnets 73, 74, 75 repelling each other on the axis of the fixed shaft 63,
The magnet 75 is positioned above the magnet 73 in the radial bearing surface 64
Is mounted on the upper case 76 as a cover arranged on the outer periphery of the rotating shaft 67 so as to surround the
By being fixed to the upper end of 63, the rotating body R including the rotating shaft 67, the mirror retainer 69, the polygon mirror 70, and the magnet 73 is urged to float upward from the fixed shaft 63, and is supported without contact. I have. Also, upper case 76
The radial bearing surface 64 is fixed to the
You. Note that a deflection window 77 is provided in the peripheral wall portion 76a of the upper case 76, and the deflection window 77 allows laser light to enter and exit the polygon mirror.

On the other hand, reference numeral 80 denotes an axial gap type face-to-face brushless motor (motor unit) for driving the polygon mirror 70. This motor 80, as shown in FIG.
A rotor magnet assembly 81 fixed to the rotating shaft 67, and a drive coil unit 82 opposed to the lower surface thereof and spaced apart from the rotor magnet assembly 81 by a predetermined distance in the axial direction, and a Hall element (magnetoelectric conversion element) 83a to 83c, and the rotor magnet assembly 81 includes a field magnet 81a.
Are integrally mounted on the rotating shaft 67 via the yoke 81b.

The field magnet 81a has a plurality of magnetic poles alternately magnetized at the same open angle of N and S, and has a cutout 81c extending in the circumferential direction at the outer periphery. Have been. The notch 81c and the yoke 81b
A concave portion 81d is formed in the inner peripheral portion of the
Constitutes a groove for correcting balance when the rotating body R rotating together with the field magnet 81a rotates.

The drive coil section 82 includes six coreless armature coils (drive coils) 82a to 82c disposed on a coil board 84.
The armature coils 82a to 82f are provided at equal intervals in the magnetic path of the field magnet 81a with an open angle that does not overlap each other. Further, a stator yoke 89 for providing a closed magnetic circuit is provided below the drive coil unit 82.

As shown in FIG. 3A, the armature coil 82a is connected to the facing armature 82d, and the armature 82b is connected to the armature 82d.
e, and the armature 82c is connected to the armature 82f via a conductor, respectively.
Hall elements 83a to 83c are provided in d and 82f, respectively, forming a U phase, a V phase and a W phase as shown in FIG.

The connection system may be a parallel system as shown in FIG. 3B, in addition to the serial system as shown in FIG. 3A. This connection method may be appropriately selected according to the number of rotations and the mounting space. The Hall elements 83a to 83c have a switch function of detecting that the armature coils 82a to 82f are excited. The coil substrate 84 is connected to a driving printed circuit board 86 (control circuit board) via a plurality of motor driving harnesses 85, and the printed circuit board 86 side of the harness 85 is connected to a power supply harness (not shown). It is connected. The drive printed circuit board 86 has a transistor,
A plurality of drive circuit elements 87 such as ICs are mounted, and the printed circuit board 86 is provided on the housing 61 surrounding the recess 61a.
It is fixed to the lower surface of the outer peripheral portion by a bolt 88. Further, since the concave portion 61a is formed on the back surface of the housing 61, the circuit element 87 is housed in the concave portion 61a,
Some of the members 87 having a height are mounted on the printed circuit board 86 so as to stand upright on the concave portions 61a.

A notch 84a is formed in the coil substrate 84, and the notch 84a is attached to the housing 61 by a bolt (not shown). The notch 84a is formed by a conductor 84b.
The housing 61 is grounded via a conductor 84b, a harness 85, and a power harness. Next, the operation will be described.

First, when assembling the polygon scanner into the copying machine, the polygon scanner is fixed to a predetermined installation space of the copying machine with bolts or the like, and then a power supply harness is attached to a power supply unit in the copying machine body. Thereafter, in order to operate the polygon scanner, when current is sequentially supplied from the driving circuit element 87 to the predetermined armature coils 82a to 82f facing each other, the predetermined armature coils 82a to 82f
82f is excited and the rotor magnet assembly 81 rotates,
The rotation shaft 67 and the polygon mirror 70 (rotator R) rotate. When the polygon mirror 70 rotates, the air between the fixed shaft 63 and the rotating shaft 67 while the air in the herringbone grooves 65 and 66 formed on the radial bearing surface 64 of the fixed shaft 63 is pushed in the rotating direction of the rotating shaft 67. It is scraped out in the bearing gap and generates dynamic pressure.

When the dynamic pressure reaches a predetermined pressure, the rotating shaft 67 completely floats (in the radial direction) from the fixed shaft 63, becomes non-contact, and enters a high-speed rotating state. Since the balance of the rotating body R is corrected by the balance correcting groove 69a and the concave portion 81d, the polygon scanner is stably rotated with low vibration during high-speed rotation. In this embodiment, since the printed circuit board 86 having the driving circuit element 87 for driving the brushless motor is attached to the lower surface of the housing 61, it is not necessary to extend the harness from the motor unit to the outside as in the related art. 85 can be greatly shortened, and the cost of the polygon scanner can be reduced. Also, since the driving circuit element 87 is integrally attached to the polygon scanner,
Inspection and management of the polygon scanner can be performed very easily, and inspection and management costs can be reduced. Further, since the polygon scanner having the radial bearing surface 64 is used for high-speed rotation, the temperature of the motor part rises sharply. In this embodiment, however, the driving circuit element is provided on the end face of the outer peripheral part of the housing 61 surrounding the concave part 61a. Since the printed circuit board 86 having the 87 is attached, the surface area of the housing 61 can be enlarged, and the outer peripheral portion of the housing 61 can function as a heat radiating portion, and the heat radiating effect can be enhanced. Also,
Since the polygon scanner rotates at high speed, the motor current increases and a large circuit element 87 is required.In this embodiment, the circuit element 87 is housed in the concave portion 61a formed at the end of the housing 61, so that the large Printed circuit board for circuit element 87
The area of the printed board 86 can be reduced by mounting it upright on the board 86, and the size of the polygon scanner can be reduced by bringing the upper surface of the recess 64 close to the printed board 86. In addition, to surround the radial bearing surface 64
An upper case 76 is provided on the outer periphery of the rotating shaft 67, and the upper case 76
76 is fixed to the housing 61 to seal the radial bearing surface 64
This prevents dust from entering the radial bearing surface 64.
Can improve the reliability of the radial bearing surface 64
be able to.

In this embodiment, the driving circuit element 87 is mounted on the lower surface of the housing 61. However, the present invention is not limited to this.
FIG. 4 corresponding to the second aspect of the present invention may be adopted. That is, the same effect as that of the above-described embodiment can be obtained by providing the coil substrate 84 with the extending portion 84c extending outside the polygon scanner and providing the driving circuit element 90 in this extending portion. Harnesses can be eliminated.

At this time, the upper case 76 and the coil substrate 84
An elastic member 91 is interposed therebetween. Like this
If a large motor current is required,
A driving circuit element 90 is required.
Is arranged on the outer periphery of the upper case 76,
In other words, reduce the rise in temperature inside the polygon scanner.
Can be Also, between the upper case 76 and the coil board 84
The elastic member 91 is interposed between the radial bearing surface 64
Radiation can be prevented from entering
This prevents the bearing surface 64 from being damaged and the bearing from deteriorating.
Can improve the reliability of the polygon scanner
You. Furthermore, a coreless opposed to the field magnet 81a
Armature coils 82a to 82f are arranged in upper case 76 to
The case 76 is sealed from the outside with an elastic member 91, and the magnetic field
Between the gnet 81a and the coreless armature coils 82a-82f
Dust or the like may be mixed on the radial bearing surface 64 without interposing any other elastic members.
Motor efficiency.
Can be prevented from falling.

[0027]

According to the first aspect of the present invention, there is no need to extend the harness from the motor unit to the outside as in the prior art, and the harness can be greatly shortened, thereby reducing the cost of the polygon scanner. be able to. Further, since the driving circuit elements are integrally mounted on the polygon scanner, the inspection and management of the polygon scanner can be performed very easily, and the inspection and management costs can be reduced. In addition, since the control circuit board having the driving circuit element is mounted on the end surface of the outer peripheral portion of the housing surrounding the recess, the surface area of the housing can be enlarged, and the outer peripheral portion of the housing can act as a heat radiating portion, thereby enhancing the heat radiating effect. be able to. Further, since the driving circuit element is housed in the recess formed at the end of the housing, the area of the control circuit board can be reduced by mounting the large driving circuit element upright on the control circuit board. above,
The size of the polygon scanner can be reduced by bringing the end surface of the concave portion close to the control circuit board. In addition, a dynamic air bearing
A cover is arranged on the outer periphery of the rotating shaft so as to surround
To the housing and the dynamic pressure air shaft together with the housing.
The receiver is sealed, so that dust and the like are mixed in the dynamic pressure air bearing.
And the reliability of the dynamic pressure air bearing can be prevented.
Can be improved.

According to the second aspect of the present invention, it is not necessary to extend the harness from the motor unit to the outside as in the prior art, and the harness can be greatly shortened, and the cost of the polygon scanner can be reduced. Can be. Further, since the driving circuit elements are integrally mounted on the polygon scanner, the inspection and management of the polygon scanner can be performed very easily, and the inspection and management costs can be reduced. Also, because a large motor current is required
A drive circuit element that generates a large amount of heat is required.
Since the road elements are arranged on the outer periphery of the cover,
Can be prevented from rising. Also,
Since an elastic member is interposed between the bar and the coil substrate, dynamic pressure
It is possible to prevent dust from entering the air bearing from the outside.
Can damage the dynamic air bearing and reduce the bearing performance.
To improve polygon scanner reliability.
Can be. In addition, drive opposing the field magnet
The coil is placed inside the cover and the inside of the cover is
Sealed from the outside, and between the field magnet and the drive coil.
Dust is mixed in the dynamic pressure air bearing without interposing any other elastic members
Motor efficiency is reduced.
Can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of a polygon scanner according to the present invention, and is a cross-sectional view illustrating an entire configuration thereof.

FIG. 2A is a configuration diagram of an armature coil according to an embodiment, and FIG. 2B is a configuration diagram of a field magnet.

FIGS. 3A and 3B are diagrams illustrating a method of connecting armature coils according to an embodiment, wherein FIG. 3A is a diagram illustrating a series system and FIG. 3B is a diagram illustrating a parallel system.

FIG. 4 is a cross-sectional view illustrating the entire configuration of another embodiment of the polygon scanner.

FIG. 5 is a cross-sectional view showing the entire configuration of a conventional polygon scanner.

[Explanation of symbols]

 61 Motor housing (housing) 63 Fixed shaft 64 Radial bearing surface (dynamic air bearing) 67 Rotating shaft 70 Polygon mirror 80 Brushless motor (motor unit) 81a Field magnet 82a to 82f Coreless armature coil (drive coil) 83a to 83c Hall element (magnetoelectric conversion element) 84 Coil board 84c Coil board extension 86 Printed circuit board (control circuit board) 87, 90 Drive circuit element

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Hashimoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Mutsumi Yamamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor ▲ Taka ▼ Yoshihiro Hashi 3-1 Shinmei-do, Nakana Ichibata, Shibata-cho, Shibata-gun, Miyagi Prefecture Tohoku Ricoh Co., Ltd. JP-A-3-87715 (JP, A) JP-A-1-245217 (JP, A) JP-A-1-123473 (JP, U) JP-A-2-64915 (JP, U) JP-A-60- 51776 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02K 29/00-29/14

Claims (2)

(57) [Claims] 1. A rotary shaft having a field magnet and a polygon mirror on an outer peripheral portion, a coil substrate on which a plurality of drive coils are fixed opposite to the field magnet, and a rotary shaft via a dynamic pressure air bearing. A rotatable support shaft, a housing for supporting the fixed shaft, and the hydrodynamic air bearing.
It is arranged on the outer periphery of the rotating shaft so as to surround and
A dynamic air shaft fixed to the housing and together with the housing
A polygonal scanner comprising a motor for rotating the rotating shaft by a field magnet and a driving coil, the cavity including a cover for closing the receiver, and a recess formed at an end of the housing and surrounding the recess. A polygon scanner motor, wherein a control circuit board having a driving circuit element is mounted on an end surface of an outer peripheral portion of a housing, so that the driving circuit element is housed in a concave portion. 2. A rotary shaft having a field magnet and a polygon mirror on an outer peripheral portion, a coil substrate having a plurality of drive coils fixed to face the field magnet, and a drive coil mounted on the coil substrate. A magneto-electric conversion element for detecting that the magnetic field has been excited, a fixed shaft rotatably supporting the rotating shaft via a dynamic pressure air bearing, and an outer peripheral portion of the rotating shaft surrounding the dynamic pressure air bearing With a cover,
In a polygon scanner constituting a motor unit for rotating a rotating shaft by a field magnet, a drive coil, and a magnetoelectric conversion element, a part of the coil substrate is extended outward from an outer peripheral portion of a cover, and the extension is performed. A polygon scanner, wherein a driving circuit element for driving a motor unit is mounted on the unit, and an elastic member is interposed between the cover and the coil substrate.