JP2002272077A - Brushless motor and sealed polygon scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an eddy current caused by a motor magnet and to suppress a motor temperature rise at a low cost, and to reduce the size and cost of the brushless motor using the brushless motor and to increase the temperature of a control circuit board. To provide a sealed polygon scanner capable of reducing and improving reliability. SOLUTION: In a brushless motor having a magnetic gap in a radial direction, a rotor magnet 5 is used as an open magnetic path in a state of a rotating body, and a single leakage magnetic flux is linked to an axial direction of the open magnetic path in a radial direction. A brushless motor characterized by disposing one magnetic body 14, a sealed polygon scanner using the same, a motor housing is formed of a single metal member, and a fixed shaft is provided in a holding portion provided at a central portion thereof. The structure to be fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a brushless motor and a sealed polygon scanner.

[0002]

2. Description of the Related Art Along with high-speed printing and high image quality of digital copiers and laser printers, polygon scanners are required to rotate at a high speed exceeding 30,000 rpm, but motor vibration caused by imbalance of a rotating body is required. And the temperature rise due to the heat generated by the motor is a problem.

The imbalance of the rotating body can be suppressed to some extent by correcting it, but the imbalance of the rotating body changes due to the heat generated by the motor, and the corrected one greatly deteriorates. In addition, besides the above-mentioned vibration problem, the rise in the temperature of the motor shortens the life of the bearings and causes deterioration of optical components arranged near the motor. Is becoming more important.

Conventionally, on the heat generating surface, the outer periphery of the rotating body has been made substantially spherical so as to reduce windage loss or to provide a radiation fin to reduce the temperature rise. However, when rotating at a higher speed, the eddy current loss due to the leakage magnetic flux from the rotor magnet becomes large, and there is a problem that such a method cannot solve the problem.

For example, in the technique disclosed in Japanese Patent Application Laid-Open No. 8-154371, in an outer rotor type polygon scanner motor, loss (windage loss) is reduced by making the outer diameter of the rotor a substantially spherical shape. It is trying to reduce the temperature rise of the motor. However, this technology has the effect of reducing windage loss among motor losses, but in the case of an aluminum housing, the eddy current loss due to magnetic flux leaking from the rotor magnet is large, and the motor temperature due to this eddy current loss is large. The rise is a problem.

According to the technique disclosed in Japanese Patent Application Laid-Open No. 10-221631, in an outer rotor type polygon scanner, a balance correction groove is arranged at the center of gravity, the balance is corrected at one location, and vibration of the motor is reduced. Trying to suppress. This technique does not disclose the loss point, but as judged from the drawings, the magnetic path of the rotor magnet is open on the outer periphery of the rotor and on the housing side (downward), and magnetic flux is applied to the housing or the cover. If the housing is made of aluminum or the like due to leakage, eddy current loss is large, and a rise in motor temperature becomes a problem.

[0007] The above-mentioned problem is also in the same situation in a sealed polygon scanner using a brushless motor. That is, with high-speed printing and high image quality of digital copiers and laser printers, polygon scanners are required to rotate at a high speed exceeding 30,000 rpm. In order to achieve such high-speed rotation, a polygon scanner using a dynamic pressure air bearing has been conventionally used.

[0008] In the polygon scanner using the dynamic pressure air bearing, there is a problem that noise is increased due to wind breaking of the polygon mirror at the time of high speed rotation, a load (heat generation) is increased due to windage loss, and further, dust enters the air bearing portion. In order to avoid damage to the bearing part due to the motor housing, a sealed structure using a motor housing is adopted.

However, the above-mentioned motor housing accommodates a rotating body including a polygon mirror, a bearing portion, and a motor portion, and therefore, becomes large as a whole, and hinders the layout of the optical housing in which an optical lens and the like are installed. I'm coming. In particular, if the control circuit board is housed in the motor housing, the temperature of the polygon scanner as a whole increases as the temperature rises, and the temperature rise causes problems (for the polygon scanner, vibration increases, circuit element reliability decreases, In addition, considering the entire optical housing, it causes temperature degradation to optical elements such as lenses and lasers.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a first object of the present invention is to reduce eddy currents caused by motor magnets and suppress motor temperature rise at low cost. It is to provide a possible brushless motor.

A second object is to reduce the size and cost of the motor and the motor housing while ensuring the reliability of the bearing, and to reduce the temperature rise and the reliability of the control circuit board. It is an object of the present invention to provide a closed type polygon scanner capable of performing the above. Other objects of the present invention will be clarified by the following description.

[0012]

In order to achieve the above object, a brushless motor according to the present invention is a brushless motor having a magnetic gap in a radial direction, wherein a rotor magnet is used as an open magnetic path in a state of a rotating body. It is characterized in that a single magnetic member is arranged such that the leakage flux in the axial direction of the magnetic path and the radial direction interlink.

Further, in the brushless motor according to the present invention, a motor core is fixed to the magnetic member. In the brushless motor according to the present invention, a motor core assembly in which a motor core is fixed to the magnetic member, and a winding coil and a circuit pattern are soldered,
Preferably, it is fixed to the motor housing.

Further, in the brushless motor according to the present invention, a motor rotation position detecting element is mounted on the magnetic member. In the brushless motor according to the present invention, it is preferable that the motor housing is made of any one of an aluminum alloy, a magnesium alloy, and a zinc alloy, and the magnetic member is made of a pressed steel plate.

On the other hand, a sealed polygon scanner according to the present invention includes a dynamic pressure air bearing rotatably supporting a polygon mirror and a rotating body, a magnetic bearing floatingly supported in an axial direction, and the polygon mirror and rotating body. What is claimed is: 1. A polygon scanner having a motor unit to be driven, comprising: a motor housing having a projecting portion in a central portion, a hole for shrinking a fixed shaft on an inner circumferential side of the projecting portion, and a motor It has an outer peripheral surface for fixing a wound core, and a lower end surface of the core is a single metal member positioned between axial lengths to be fixed by shrink fitting. It is assumed that.

In the hermetically-sealed polygon scanner according to the present invention, an opening for communicating a harness for electrically connecting the motor board and the control circuit board is provided in the motor housing, and the control circuit board is provided below the housing. Is characterized in that a support column for fixing the head is integrally formed. Further, in the hermetically sealed polygon scanner according to the present invention, the motor housing has an opening for communicating a harness for electrically connecting the motor board and the control circuit board with the laser input / output surface with respect to the optical housing mounting surface. It is preferably provided on the side.

Further, in the hermetically sealed polygon scanner according to the present invention, a circumferential groove for removing stress is provided at a projecting portion at the center of the motor housing. further,
In the sealed polygon scanner according to the present invention, the motor board and the control circuit board are electrically connected via a harness, the motor board is housed in the motor housing, and the control circuit board made of a metal board is placed under the motor housing. It is preferable that it is fixed to.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a partial side sectional view of a polygon scanner of a dynamic pressure air bearing type according to an embodiment of the present invention.
As shown in the drawing, in the dynamic pressure air bearing type polygon scanner according to this embodiment, a flange 2 made of an aluminum alloy and having a polygon mirror portion 2a on the outer periphery of a cylindrical rotating sleeve 1 made of ceramic is shrink-fitted. Or it is press-fitted and fixed.

Above the rotating body A, a rotating yoke 3 (made of a magnetic material) constituting a magnetic bearing is fixed to the center of a member 4 made of an aluminum alloy. The member 4 is fixed to the upper portion of the flange 2 by press-fitting, shrink-fitting, or bonding, and also has a function of closing the opening at the upper end of the rotating sleeve 1. A rotor magnet 5 is arranged below the flange 2 and forms an outer rotor type brushless motor together with the stator core 11.

The fixed shaft 16 constituting the radial dynamic pressure bearing is made of a cylindrical ceramic material similarly to the rotary sleeve 1, and a herringbone-shaped dynamic pressure generating groove 16a is formed on the outer diameter surface thereof. ing. The fixed shaft 16
The dynamic pressure bearing gap formed by the outer peripheral surface of the rotating sleeve 1 and the inner peripheral surface of the rotary sleeve 1 is fitted with a size of several μm. A permanent magnet assembly for a magnetic bearing (consisting of a magnet 32 and upper and lower magnetic plates 30 and 31) constituting an axial bearing is arranged on an inner peripheral portion of the fixed shaft 16.

The above-described permanent magnet assembly for a magnetic bearing has a magnetic gap in the radial direction between the projection 3a of the magnetic body 3 and the rotating body A by utilizing the attractive force acting between the gaps. Non-contact support in the axial direction. An upper air reservoir 34 formed by the fixed shaft 16 and the rotating body A.
A minute hole (not shown) is formed in a member forming the air reservoir 34, such as the magnetic body 3, the lower closing member 35, or the member 4, which communicates with the outside of the rotating body A,
The magnetic bearing has damping characteristics.

The upper and lower portions of the rotating body A are provided with an unbalance correcting portion. The upper portion is coated with an adhesive or cut off a part of the recess 2b of the flange 2, and the lower portion is the inner circumference of the flange 2 or the rotor magnet 5. Apply adhesive to the surface or flange 2
A part of the outer circumference or lower end face portion is cut off. In order to reduce vibration during high-speed rotation, the unbalance amount at each point is kept at 1 mg or less. The rotating body A is substantially sealed by the motor housing 15 and the upper cover 17 so as to cover the rotating body.

The motor is driven by using the magnetic field of the rotor magnet 5 to refer to a signal output from the Hall element 12 mounted on the motor board 13 as a position signal, and to perform excitation switching of the stator winding by a drive circuit. To rotate. Here, the rotor magnet 5 is magnetized in the radial direction, and generates rotational torque between the rotor magnet 5 and the outer periphery of the stator core 11 to rotate. The rotor magnet 5 is a plastic magnet, and has a structure in which its outer diameter portion is held by the flange 2 so that destruction due to centrifugal force during high-speed rotation does not occur.

Although the rotor magnet 5 may be a metal magnet having a centrifugal proof strength, a plastic magnet is preferable if it is easy to reduce the wall thickness and has the above-described outer diameter holding mechanism. Further, the rotor magnet 5 has a magnetic path open in the outer diameter and the height direction other than the inner diameter, and the Hall element 12 for switching the excitation of the motor is arranged in the open magnetic path.

The magnetic body 14 has a function of shielding magnetic flux leaking from the rotor magnet 5 and prevents eddy current from flowing through the motor housing 15. Here, the reason for making the rotor magnet 5 an open magnetic path is that in order to make it a closed magnetic path, a magnetic body must be provided on the outer diameter side of the rotor magnet 5, thereby increasing the number of parts. This is to prevent the unbalance change from increasing.

It is also conceivable to arrange a magnetic material on the outer diameter of the rotor magnet 5, but for this purpose, the magnetic flux of the rotor magnet 5 does not leak in the outer diameter direction.
Inner circumference of rotor magnet 5 (stator core 11 and rotor magnet 5
Between). As mentioned earlier, 30
For high-speed polygon scanners of 000 rpm or more, shortening the start-up time is also an issue.
There is a problem that the magnetic field of the stator core 11 malfunctions the Hall element 12 to cause a start-up failure, and it is preferable to use an open magnetic path.

Hereinafter, the magnetic portion of the present invention will be described in detail. A magnetic body 14 for reducing eddy current to the motor housing 15 is disposed in the open magnetic path. The magnetic body 14 has an L-shaped cross section in order to reduce eddy current due to leakage flux in both the downward and radial directions of the leakage flux of the rotor magnet 5. In the past, the lower leakage flux was a thin circular magnetic body, and the radial leakage magnetic flux was a thin ring-shaped magnetic body, which was separately arranged in each direction, but the parts and assembly cost became expensive. I will.

For example, the thin ring-shaped magnetic body 22 of the conventional example shown in FIG. 7 is fixed to the inner peripheral surface of the motor housing 15, but is fixed by a restoring force when the rectangular magnetic body is deformed into a curved surface. In this case, the magnetic material is integrated as in the present invention, thereby improving the assembling property.

The assembling can be easily fixed by caulking or press-fitting the inner peripheral portion of the magnetic body 14 to the outer diameter portion 15e of the motor housing convex portion. Magnetic body 14
May be equal to or higher than the upper end of the rotor magnet 5. Further, by cutting out a portion corresponding to the harness portion 23, the harness connection with the circuit board 24 is facilitated.

FIG. 2 is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to another embodiment of the present invention. The magnetic material 214 according to the present embodiment includes the magnetic material 1
As compared with 4, a projection having an L-shaped cross section is also provided on the inner peripheral portion, and the motor core is fixed to that portion. The assembling is performed by fixing the motor substrate to the magnetic body 214 in advance, and then fixing the motor core to the magnetic body 214. Each fixing is appropriately selected and performed, such as caulking, press-fitting, screw fixing, and adhesion.

At the same time as fixing the motor core, soldering of a coil winding (not shown) is performed. Then, since the motor assembly only needs to be inserted and fixed to the housing to which the fixed shaft is fixed, assemblability is further simplified. This simplifies the work in the embodiment of FIG. 1 as compared with the work in which the soldering of the coil winding is performed by inserting a soldering iron into the bottom of the housing.

FIG. 3 is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention. The magnetic body 314 according to the present embodiment is an example in which a circuit pattern is formed on the magnetic body 214 so that a Hall element, a harness, and the like can be mounted on the magnetic body 214. The motor body and the magnetic body are integrated. The number of parts can be reduced, and the assemblability can be further simplified. By mounting the drive circuit elements shown in FIG. 1 on the magnetic body 314, the harness can also be omitted, and the number of parts can be further reduced and assembly can be simplified.

Further, in this embodiment, since the motor substrate and the magnetic body are integrated, generation of chatter noise due to vibration of the motor substrate is eliminated. Conventionally, if there is a slight gap or the like between the opposing surface of the motor substrate and the magnetic body, noise of the rotation frequency component and its harmonic component is generated, so that it has been necessary to make close contact with an adhesive or the like.

On the other hand, in the radial direction of the rotating body A, the rotating body,
The motor housing 15 is arranged so as to cover the motor and the bearing. The motor housing 15 is provided with an opening 15a for entering and exiting a laser.
The opening 15a is shielded from the wind noise of the polygon mirror by a laser beam transmitting member 18 made of a material such as glass. In the center of the motor housing 15,
A fixed shaft 16 is installed and fixed (preferably shrink fit) on the inner peripheral portion of the protruding portion 15b, and the motor core 11 is fixed and mounted (preferably shrink fit and caulking) on the outer peripheral portion of the protruding portion 15b.

Below the motor housing 15,
Circuit elements 25 to 28 for controlling the rotation speed of the motor are mounted on the control circuit board 24. Control circuit board 2
The material No. 4 is made of metal, and therefore, the circuit pattern is applied only to the circuit element mounting surface side.

In this embodiment, the control circuit board 24
Is constituted by a so-called one-sided metal substrate, it is possible to efficiently cool the heating element, and since there are no circuit elements and circuit patterns on the lower surface portion 24a as a polygon scanner, the polygon scanner is Even when the lower surface portion 24a contacts the optical housing 50 by mistake when mounted on the optical housing 50, the optical housing 50 is not electrically damaged and the safety is improved.

On the other hand, the control circuit board 24 and the circuit element 2
5 to 28 are electrically connected to the motor board 13 via the harness 23. Further, the column 15 c is projected downward from the motor housing 15 so that the control circuit board 24
Is fixed. An opening 15d is provided in the motor housing 15 so that the harness 23 can be connected, and the motor housing 15 is appropriately sealed with an adhesive, a cured resin, or the like according to the degree of sealing in the motor housing 15.

The magnetic body 14 is made of a magnetic material having a high specific resistance (for example, a soft magnetic material such as carbon steel, silicon steel, and ferrite). Table 1 below shows examples of suitable materials and specific resistances for the motor housing 15.

[Table 1]

The above-mentioned materials can be formed by a die-casting method and can be easily formed into a complicated shape. On the other hand, examples of suitable materials and specific resistances for the material of the magnetic body 14 are shown in Table 2 below.

[Table 2] A steel plate which can easily produce the shape of the magnetic body 14 shown in FIGS. 1 to 3 by press working is preferable.

FIG. 4 is a partial side cross-sectional view of a dynamic air bearing polygon scanner according to still another embodiment of the present invention. The basic configuration (features) of the dynamic pressure air bearing type polygon scanner according to the present embodiment is the same as that shown in the previous embodiment, so only the new features are provided.
This will be described below.

However, in the dynamic pressure air bearing type polygon scanner according to this embodiment, the magnetic member 14 having an L-shaped cross section is used.
Instead of using a magnetic body on a circular flat plate disposed on the bottom surface of the motor housing 15 and a strip-shaped thin ring-shaped magnetic body attached to the inner peripheral surface of the motor housing 15, The dynamic pressure air bearing type polygon scanner according to the present embodiment effectively functions even in such a configuration.

In the dynamic pressure air bearing type polygon scanner according to this embodiment, as described above, the fixed shaft 16 and the stator core 11 are installed on the inner and outer circumferences of the protruding portion 15b. And the stator core 11
Since the lower end surface H1 is located in the axial direction inside of the axial length L to which the fixed shaft 16 is fixed, the lower end surface H1 is also shortened in the axial direction, which is a fruit of miniaturization. .

Further, in the dynamic pressure air bearing type polygon scanner according to the present embodiment, the control circuit board 24 is provided below the housing, so that the cooling air flows through the control circuit board 24 below the optical housing 50. Thus, a practical effect that the circuit element can be further cooled can be obtained.

Further, on the inner peripheral side surface of the motor housing 15 (outer peripheral surface side of the rotor magnet 5), a magnetic body 14 is disposed as an L-shaped magnetic shield function, and an outer diameter portion of the rotor magnet 5 is formed. The motor housing 1 has an open magnetic path.
5 is to prevent eddy current loss occurring at 5. The magnetic body 14 is made of a magnetic material having a high specific resistance (for example, a soft magnetic material such as carbon steel, silicon steel, and ferrite). If the height of the magnetic body 14 is equal to or higher than that of the rotor magnet 5, the eddy current loss can be reduced. Therefore, the entire motor housing 15 may be made of a magnetic material.

FIG. 5 is a partial side sectional view of a dynamic air bearing type polygon scanner according to still another embodiment of the present invention. The basic configuration (features) of the dynamic pressure air bearing type polygon scanner according to the present embodiment is also the same as that shown in the previous embodiment, so only the new features are provided.
This will be described below.

The dynamic pressure air bearing type polygon scanner according to this embodiment is a modified example of the motor housing and the motor board, and the protrusion 115 of the motor housing 115 is provided.
A fixed shaft is fixed to the outer periphery of the motor core at the inner periphery, and the fixed shaft 116 is fixed to the motor housing 115 by shrinkage shrinkage, and the fixed shaft falls down (with respect to the attachment portion to the optical housing 50). The squareness is fixed with high accuracy because it affects the laser scanning position by the polygon mirror, and shrink fit is fixed so as not to change.

However, the stress generated when the motor core is fixed by caulking to the outer diameter portion is transmitted to the fixed shaft shrinkage fitting portion, and the fixed shaft fixed by shrinkage fixing with high precision may fall down. Therefore, in the present embodiment, the circumferential groove 115b is provided so that stress is not transmitted when the motor core is fixed by caulking.

According to the present embodiment, a reduction in size can be achieved, and at the same time, stress is prevented from being transmitted to the fixed shaft shrink fitting portion when the motor core is fixed by crimping, so that the motor core can be fixed with high precision. The effect is also obtained.

According to the above-described embodiment, the motor board 113 is made of a metal material (for example, a steel plate), like the control circuit board 24, and has magnetism. By using a metal substrate having magnetism, it is not necessary to provide the magnetic body 14 described with reference to FIG. However, since this is to prevent eddy currents from the rotor magnet, the leakage flux direction of the rotor magnet, that is, the entire circumference (circle) is required. Further, the motor substrate 13 shown in FIG. 5 need only be capable of connecting the terminals of the Hall element 12 and the coil windings to the motor substrate 13, so that the motor substrate does not necessarily have to cover the entire circumference. It is possible to

FIG. 6 is a partial side sectional view of a dynamic air bearing polygon scanner according to still another embodiment of the present invention. The basic configuration (features) of the dynamic pressure air bearing type polygon scanner according to the present embodiment is also the same as that shown in the previous embodiment, so only the new features are provided.
This will be described below.

In the dynamic pressure air bearing type polygon scanner according to the present embodiment, the harness 223 connecting the motor board and the control circuit board is connected through the opening 215 a in the side wall of the motor housing 215. Opening 2
Reference numeral 15a communicates with the inside of the optical housing 50 and is located between the motor housing mounting portion and the laser input / output opening.

According to this embodiment, in addition to the above-described effects, an effect that the motor housing 215 can be made thinner can be obtained.

Each of the above embodiments is merely an example of the present invention, and the present invention should not be limited to these embodiments. Even if appropriate modifications and improvements are made within the scope of the present invention. It goes without saying that it is good.

[0055]

As described above, according to the present invention, the following effects can be obtained. (1) In a brushless motor having a magnetic gap in a radial direction, a rotor magnet is set as an open magnetic path in a state of a rotating body,
By arranging a single magnetic member so that the leakage flux in the axial direction and the radial direction of the open magnetic path interlinks, reduction of eddy current loss (motor temperature rise) generated in the motor housing can be realized at low cost. . (2) The motor core is fixed to the magnetic member, and the motor core assembly in which the winding coil and the circuit pattern are soldered is fixed to the motor housing, so that the workability of soldering the coil winding is improved and the quality of the motor is improved. And cost reduction. (3) Further, by mounting the motor rotation position detecting element on the magnetic member, it is possible to reduce the number of components (that is, to integrate the motor substrate and the magnetic member) and reduce noise caused by the motor substrate.

(4) In the dynamic pressure air bearing type polygon scanner according to the present invention, the motor housing is provided with an opening for laser input / output, and the fixed shaft and the motor core are provided on the inner and outer circumferences of the central projection. Accordingly, it is possible to reduce the size of the motor housing and the cost by reducing the number of parts. (5) Further, an opening for communicating a harness for electrically connecting the motor board and the control circuit board is provided in the motor housing, and a column for fixing the control circuit board is integrally formed at a lower portion of the housing. This makes it possible to efficiently radiate the heat generated by the control circuit board and reduce the temperature rise of the entire polygon scanner. (6) Since the motor housing is provided with an opening for communicating a harness for electrically connecting the motor board and the control circuit board, the motor housing can be made thinner. (7) By providing a circumferential groove for removing stress at the protruding portion at the center of the motor housing, it is possible to prevent stress from being transmitted to the fixed shaft shrink fitting portion when fixing the motor core by caulking. Accurate fixation becomes possible.

[Brief description of the drawings]

FIG. 1 is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional side view of a dynamic pressure air bearing type polygon scanner according to another embodiment of the present invention.

FIG. 3 is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention.

FIG. 4 is a partial side sectional view of a dynamic air bearing polygon scanner according to still another embodiment of the present invention.

FIG. 5 is a partial side cross-sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention.

FIG. 6 is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention.

FIG. 7 is a partial side sectional view showing one example of a conventional dynamic pressure air bearing type polygon scanner.

[Explanation of symbols]

 A Rotating body 1 Rotating sleeve 2 Flange 2a Polygon mirror part 2b Flange recess 3 Magnetic body 5 Rotor magnet 11 Status core 13 Motor board 14, 214, 314 Magnetic body 15, 115, 215 Motor housing 15a Opening 15b Projecting portion 115b Circle Circumferential groove 16 Fixed shaft 16a Dynamic pressure generating groove 22 Thin ring-shaped magnet body 24 Control circuit board 32 Magnet assembly 34 Air pocket

Continued on the front page F term (reference) 5H019 AA04 AA06 BB05 BB15 BB20 BB23 CC04 DD01 EE07 EE09 EE14 5H605 AA01 AA03 BB05 BB14 BB17 BB19 CC01 CC06 CC08 CC09 DD09 DD36 EA15 EC01 EC20 5H607 AA04 BB01 DD01 DDBB01 GG12 HH01 HH03

Claims (10)

[Claims] In a brushless motor having a magnetic gap in a radial direction, a rotor magnet is set as an open magnetic path in a state of a rotating body, and a single leakage magnetic flux is linked to an axial direction of the open magnetic path in a radial direction. A brushless motor, wherein one magnetic member is arranged. 2. The brushless motor according to claim 1, wherein a motor core is fixed to said magnetic member. 3. The brushless motor according to claim 1, wherein a motor core assembly in which a motor core is fixed to the magnetic member and a winding coil and a circuit pattern are soldered is fixed to a motor housing. 4. The brushless motor according to claim 1, wherein a motor rotation position detecting element is mounted on the magnetic member. 5. The brushless motor according to claim 1, wherein the motor housing is made of one of an aluminum alloy, a magnesium alloy, and a zinc alloy, and the magnetic member is made of a pressed steel plate. 6. A polygon scanner comprising a polygon mirror, a dynamic pressure air bearing rotatably supporting a rotating body, a magnetic bearing floatingly supported in an axial direction, and a motor unit for driving the polygon mirror and the rotating body. In the above, the motor housing has a protruding portion in the center portion, a hole for shrink-fitting the fixed shaft on the inner peripheral side of the protruding portion, and a core for fixing the motor winding on the protruding portion. An enclosed polygon scanner having an outer peripheral surface, wherein a lower end surface of the core is a single metal member positioned between axial lengths to be fixed by shrink fitting. 7. An opening for communicating a harness for electrically connecting the motor board to the control circuit board is provided in the motor housing, and a support column for fixing the control circuit board is integrally formed at a lower portion of the housing. The hermetically-sealed polygon scanner according to claim 6, wherein: 8. The motor housing is provided with an opening for communicating a harness for electrically connecting the motor board and the control circuit board on a laser input / output side with respect to the optical housing mounting surface. 7. The sealed polygon scanner according to claim 6, wherein: 9. The hermetically-sealed polygon scanner according to claim 6, wherein a circumferential groove for removing stress is provided in a protruding portion at a central portion of the motor housing. 10. The motor board and the control circuit board are electrically connected via a harness, the motor board is housed in a motor housing, and the control circuit board made of a metal board is fixed to a lower portion of the motor housing. And a closed polygon scanner.