JP2001061266A - Dc brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polygonal scanner equipped with a printed board, which suppresses dispersion of the rotational position of a rotor and also is easy to wire a drive circuit. SOLUTION: This motor suppresses the positional dispersion of a bearing to a mounting reference plane to be small, and suppress the dispersion of the rotational position (radial direction and vertical direction) of the rotor small, by providing a mounting reference to a radial dynamic pressure air bearing and an axial bearing integrally with the mounting reference plane made at a housing 101, and attaching each fixed part directly to a housing 101. Moreover, the circuit design of the board is facilitated by equipped itself with a board 104, which blocks the through part 101b of the housing 101 from the outside, a position detecting element 103 which is mounted on the board, and a drive circuit board 122 which is connected to a board via a connector 123 mounted on the board, and also cooling effect is enhanced by arranging a drive element outside the sealed space, and it can be used even at high revolution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC brushless motor, and more particularly, to a polygon scanner which is a DC brushless motor for high-speed rotation used in a space where a rotating body is closed.

[0002]

2. Description of the Related Art A dynamic pressure air bearing type polygon scanner will be described below as an example of a DC brushless motor according to the present invention.

An electrophotographic recording apparatus using a laser writing system, such as a digital copying machine and a laser printer,
Due to excellent features such as high printing quality, high-speed printing, low noise, and low price, it is rapidly spreading. The polygon scanner, which is a component of the laser writing system of these recording apparatuses, is required to have a rotation speed according to the printing speed and the pixel density of the recording apparatus. In recent years, with the increase in print speed and pixel density, polygon scanners have been required to rotate at a high speed of 20,000 rpm or more. Conventional ball bearing types are required in terms of bearing life and bearing noise. Quality cannot be satisfied. Therefore, as a polygon scanner for high-speed rotation, a scanner using a dynamic pressure air bearing has been put to practical use.

[0004] Such a polygon scanner for high-speed rotation is an optical component for preventing noise leakage due to the wind, reducing the amount of agitating air to reduce the load (windage loss) of the motor, or an optical component. It is used in a closed space to prevent the polygon mirror from being soiled by dust.

As such a brushless motor, there is one described in Japanese Patent Application Laid-Open No. 08-266030.

[0006]

However, in the above-mentioned conventional brushless motor, a harness for connecting two printed circuit boards (a driving circuit and a printed circuit board of the motor) is required, which increases the cost.

In addition, since the magnet of the vertical repulsion type magnetic bearing is fixed to the tip of the fixed shaft, the axial position of the polygon mirror with respect to the mounting reference surface formed on the housing tends to vary. In order to ensure the positional accuracy of the polygon mirror, the dimensional accuracy of the magnet fixing portion at the tip of the fixed shaft must be strict, and the positional accuracy must be ensured by accurately assembling the fixed shaft to the housing.

In order to solve such a problem, the following polygon scanner can be considered.

That is, a rotating body to which a polygon mirror is fixed is rotatably supported in a radial direction and an axial direction by a radial dynamic pressure air bearing and an axial bearing, and a motor for driving the rotating body and a housing having a mounting reference surface are provided. A fixed part of a radial dynamic pressure air bearing and an axial bearing are fixed to a bearing mounting reference part integrally formed by connecting a plurality of beams to a substantially central part of the housing. The part is directly fixed, in a use state attached to the optical box, so that the space in which the rotating body is arranged is shut off from the outside and sealed,
An outer peripheral portion and an inner peripheral portion of a fixed portion of the motor are a hydrodynamic air bearing type polygon scanner fixed in close contact with a housing.

However, even with such a polygon scanner, the printed circuit board (the fixed portion of the motor) has a donut shape, and a hole is formed in the center of the printed circuit board. And the size of the printed circuit board is inevitably increased. As a result, there is a problem that the outer diameter of the motor increases and the cost of the printed circuit board also increases.

The present invention has the following objects.

1. The mounting reference for the radial dynamic pressure air bearing and the axial bearing are provided integrally with the mounting reference surface formed on the housing, and the fixing parts are directly mounted on the housing to minimize variations in the bearing position relative to the mounting reference surface. Specifically, variations in the rotational position (radial direction, vertical direction) of the rotating body are suppressed to be small.

2. In the use state, a sealed state of the space where the rotating body is arranged is ensured.

3. The drive element is arranged outside the closed space, so that the cooling effect by the air blowing is high, and the drive element can be used even at high speed rotation where heat is generated by the drive element.

4. It facilitates the layout of mounting components and the design of wiring patterns for the drive circuit, and reduces the size and cost of the printed circuit board and the outer diameter of the motor.

5. Due to the leakage flux of the motor permanent magnet,
This prevents eddy currents from being generated in the housing made of a conductive material, thereby reducing the efficiency of the motor.

6. A harness for connecting two printed boards (a printed circuit board for a drive circuit and a motor) is not required,
Reduce costs and reduce flatness.

[7] A polygon scanner having the above characteristics is provided.

8. Provided is a polygon scanner in which a rotating body is housed in a closed space and has good handleability as a polygon scanner.

[0020]

According to the first aspect of the present invention,
In order to solve the above problem, a rotating body is supported in a radial direction and an axial bearing in a radial direction and an axial direction, respectively, a permanent magnet is fixed to the rotating body, and a magnetic gap is formed in a radial direction. A radial bearing, an axial bearing, and a radial gap type DC brushless motor in which a fixed portion of the motor is fixed at a central portion of a housing provided with a mounting portion, wherein the mounting portion of the housing and a rotation center shaft are fixed. A penetrating portion is formed therebetween, and a substrate fixed to the housing so as to close the penetrating portion from the outside; and a motor position detection element mounted on the substrate so as to be disposed in the penetrating portion. It is characterized by the following.

According to a second aspect of the present invention, there is provided a brushless motor according to the first aspect, wherein the housing is made of a conductive material, and a surface of the housing facing the permanent magnet is made of a ferromagnetic material. Wherein the magnetic plate is fixed.

According to a third aspect of the present invention, there is provided a DC brushless motor according to the first or second aspect, wherein a first connector is mounted on a substrate on which the position detecting element is mounted. The second connector is mounted on the drive circuit of (1), and the first connector and the second connector are directly fitted and connected.

According to a fourth aspect of the present invention, there is provided a DC brushless motor according to any one of the first to third aspects, wherein a polygon mirror is fixed to the rotating body. Things.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problem, in the brushless motor according to the fourth aspect, the housing has a cover provided with a laser beam input / output unit, and the rotating body is provided with a cover. It is characterized by being housed in a closed space.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the configuration and operation of a polygon scanner will be described with reference to FIGS.

A reference surface 21a for attachment to an optical housing (not shown) is formed in the housing 21 in a brim shape. A printed circuit board 22 constituting a motor unit is disposed inside the housing 21 and is fixed to the housing 21 with screws or an adhesive. Printed circuit board 22
, A stator core 23 wound with a winding coil and a Hall element 24 are attached and patterned. The motor system uses a rotor magnet 27 attached to a rotating body 26.
A radial gap outer rotor type brushless motor in which a stator core 23 wound with a winding coil 23a faces in a direction perpendicular to the rotation axis. Printed circuit board 22
The outer peripheral portion 22a is in close contact with the housing 21 circumferentially, and the inner peripheral portion is in close contact with the base 23b of the stator core 23.
3b is in close contact with the housing 21 and, together with the cover 39, shuts off the space in which the rotating body 26 is arranged and the outside, and seals the space in which the rotating body 26 is arranged.

At the center of the housing 21, there is formed a cylindrical bearing mounting reference portion 21c which is connected to a plurality of beams 21b extending from the periphery and is integrally formed, and a hydrodynamic air bearing is formed with reference to the outer cylindrical surface 21d. Are fixed by adhesive. On the cylindrical surface of the fixed shaft 28, a groove 28a for forming a dynamic pressure air bearing is formed. Rotating body 2
When the rotation starts, the pressure of the air in the gap between the hollow rotary shaft 29 and the fixed shaft 28 increases, and the rotary body 26 is supported in the radial direction (radial direction) without contact.

Inside the fixed shaft 28, a fixed portion 33 of a suction type magnetic bearing is embedded with reference to an end face 21e of a cylindrical bearing mounting reference portion 21c formed in the center of the housing 21. The fixed portion 33 of the attraction type magnetic bearing is made of a ferromagnetic material having a ring-shaped permanent magnet 30 magnetized in two poles in the direction of the rotation axis and a center circle smaller than the inner diameter of the ring-shaped permanent magnet 30. And a second fixed yoke plate 3 made of a ferromagnetic material in which a center circle similarly smaller than the inner diameter of the ring-shaped permanent magnet 30 is formed.
Consists of two. The first fixed yoke plate 31 and the second fixed yoke plate 32 sandwich the ring-shaped permanent magnet 30 in the axial direction, and the center circle of the first fixed yoke plate 31 and the center circle of the second fixed yoke plate 32 rotate. The elastic member 34 is disposed so as to be coaxial with the central axis and is embedded in the concave portion at the tip of the fixed shaft 28.
Or it is fixed with an adhesive or the like. As a material of the ring-shaped permanent magnet 30, a rare earth permanent magnet is mainly used. Steel plates are used for the fixed yoke plates 31 and 32. The fixed shaft 28 is made of a non-magnetic material.

The rotary body 26 has a flange 36 fixed to the outside of the hollow rotary shaft 29, and a rotary portion 35 of a magnetic attracting bearing is press-fitted into the center of the flange 36 and fixed to the flange 36. The rotating portion 35 of the attraction type magnetic bearing has an outer cylindrical surface that forms a magnetic gap between the center circle of the first fixed yoke plate 31 and the center circle of the second fixed yoke plate 32, and the outer cylindrical surface thereof. Are arranged coaxially with the rotation center axis. A permanent magnet or a steel-based ferromagnetic material is used for the rotating part 35 of the attraction type magnetic bearing. A polygon mirror 37 is mounted on the upper surface of the flange 36, and the screw is tightened into a screw hole formed in the rotating portion 35 with a leaf spring 38 interposed therebetween, whereby the polygon mirror 37 is pressed and fixed. . Further, a fine hole 36a is formed in the flange 36 to attenuate vertical vibration by utilizing viscous resistance when air passes.

The rotor magnet 27 for the motor is adhesively fixed below the flange 36.

At the top of the scanner, a cover 39 whose inside is cut out so as to surround the rotating body 26 is fixed to the housing 21 with screws. In the cover 39, a glass window is fixed to an opening for inputting and outputting laser light from a semiconductor laser (not shown) with a double-sided tape or an adhesive, and is sealed.

A drive circuit is integrally provided on the printed circuit board 22 constituting the motor section, and according to a position detection signal of the Hall element 24, the energization of the winding coil is sequentially switched to rotate the rotating body 26. Constant speed control is performed. The driving element 40 is disposed and mounted between the beams 21b formed on the housing 21 outside the closed space in which the rotating body is disposed. The drive element 40 and other circuit components 41 are cooled by a blower fan attached to a main body (not shown).

The balance correction is performed on the upper and lower two correction surfaces 37a and 36b of the rotating body 26 so that the unbalanced vibration of the rotating body 26 is at a very small level.

Since the printed board 22 in this example has a hole at the center, it is difficult to design the mounting component layout and the wiring pattern of the drive circuit, and the size of the printed board increases outside. As a result, the outer diameter of the motor increases and the cost of the printed circuit board also increases.

An embodiment of the present invention is shown in FIGS. 3 and 4, and the configuration and operation will be described below.

A reference surface 101a for attachment to an optical housing (not shown) is formed in the housing 101 in a brim shape. A stator core 102 is fixed at the center of the inside of the housing 101. A penetrating portion 101b is formed in the housing 101, and a Hall element 103, which is a position detecting element of a motor, is mounted and arranged on a printed circuit board 104. Further, a winding coil 105 wound around the stator core 102 is also connected to the printed circuit board 104. The printed circuit board 104 is arranged inside the mounting hole of the optical housing, is fixed so as to cover the through portion 101b of the housing 101 from the outside, and seals the space where the rotating body 107 is arranged together with the cover 106. The motor system is a radial gap outer rotor type brushless motor in which a rotor magnet 108 attached to a rotating body 107 and a stator core 102 around which a winding coil 105 is wound face in a direction perpendicular to the rotation axis.

At the center of the housing 101, a fixed sleeve 109 constituting a dynamic pressure air bearing is fixed. A dynamic pressure air bearing surface is formed on the inner cylinder surface of the fixed sleeve 109. When the rotating body 107 starts rotating, the pressure of the air increases in the bearing clearance between the hollow rotating shaft 110 and the fixed sleeve 109, and the rotating body 107 is supported in a radial direction (radial direction) without contact. The fixing sleeve 109 has a high-precision cylindrical surface formed of an aluminum alloy surface-treated or a ceramic material.

The rotating body 107 has a flange 111 fixed to one end of the hollow rotating shaft 110 by shrink fitting or press fitting.
A polygon mirror 112 is mounted on the upper surface of the flange 111, and a mirror press 113 formed of a steel plate is pressed into the inner cylinder of the hollow rotary shaft 110 from above, thereby pressing and fixing the polygon mirror 112 elastically. I have. Flange 11
A rotor magnet 108 for a motor is press-fitted and fixed below 1. A non-magnetic material such as an aluminum alloy surface-treated or a ceramic material is used for the hollow rotary shaft 110. For the flange 111, an aluminum alloy, steel, or the like is used.

A dynamic pressure air bearing surface is formed on the outer cylinder surface of the hollow rotary shaft 110, and a groove 11 for enhancing the dynamic pressure effect is formed in a part thereof.
0a is formed. At one end of the hollow rotary shaft 110, a shrink fit portion of a flange 111 is formed continuously with the same diameter as the dynamic pressure air bearing, and the external shape of the hollow rotary shaft 110 is a simple hollow cylinder. As described above, by forming the hollow rotary shaft 110 as a simple hollow cylinder, high-precision outer diameter machining of the dynamic pressure air bearing surface is facilitated, and cost reduction can be achieved. Particularly, in the case of a ceramic material, since a complicated shape is difficult to process, a simple hollow cylinder is highly effective in reducing costs.

A flange 11 is provided at one end of the hollow rotary shaft 110.
1 can be used as an adapter to mount a polygon mirror having a different mounting shape.
Since 0 is a simple hollow cylinder, it is easy to make the dynamic pressure air bearing a standard part or a common part, and the cost can be reduced.

Further, by providing a shrink-fit portion of the flange 111 at one end of the hollow rotary shaft 110, Japanese Patent Laid-Open No. 07-19 / 07
Since there is almost no deformation of the bearing surface due to shrink fitting as described in 0047, there is no need to finish the bearing surface by post-processing, and the bearing surface can be used as it is. Also, Japanese Patent Application Laid-Open No. 07-
The shrink-fit diameter can be made smaller than when shrink-fitting a member having a dynamic pressure bearing surface formed on the inner diameter as in the configuration of 190047, and the cylindrical surface can be finished with the same high precision as the dynamic pressure bearing surface. Therefore, it is highly effective in preventing loosening and falling off due to a change in operating temperature and improving reliability.

The inner cylindrical portion of the hollow rotary shaft 110 has a ring-shaped permanent magnet 114 magnetized in two poles in the direction of the rotary shaft, and a ferromagnetic member having a center circle smaller than the inner diameter of the ring-shaped permanent magnet 114. A first yoke plate 115 made of a material, and a second yoke plate 1 made of a ferromagnetic material similarly having a center circle smaller than the inner diameter of the ring-shaped permanent magnet 114 are formed.
The rotating part 117 of the attraction type magnetic bearing is fixed. First yoke plate 115 and second yoke plate 1
Numeral 16 sandwiches the ring-shaped permanent magnet 114 in the axial direction, and is arranged such that the center circle of the first yoke plate 115 and the center circle of the second yoke plate 116 are coaxial with the rotation center axis. As a material of the ring-shaped permanent magnet 114, a rare-earth permanent magnet is mainly used. Yoke plates 115, 11
6 is a steel plate.

The fixing portion 118 of the attraction type magnetic bearing has an outer cylinder surface forming a magnetic gap between the center circle of the first yoke plate 115 and the center circle of the second yoke plate 116, and the outer cylinder Placed so that the surface is coaxial with the rotation center axis,
It is fixed to the housing 101. A permanent magnet or a steel-based ferromagnetic material is used for the fixing portion 118 of the attraction type magnetic bearing.

A cap member 119 is press-fitted and fixed to the inner cylindrical portion of the hollow rotary shaft 110. Cap member 1
19, a fine hole 119a is formed to attenuate vertical vibration by utilizing viscous resistance when air passes. Similarly, the cap member 11 is provided on the inner cylindrical portion of the hollow rotary shaft 110.
The stopper 120 is press-fitted and fixed with the rotating part 117 of the suction type magnetic bearing in the axial direction together with the stopper 9. Both the cap member 119 and the stopper 120 are made of a nonmagnetic material such as a stainless steel plate.

At the top of the scanner, a cover 106 whose inside is cut out so as to surround the rotator 107 is mounted on the housing 1.
01 is fixed with a screw. An opening 106a through which laser light enters and exits is formed in the cover 106, and the glass window 121 is fixed and sealed with a double-sided tape or an adhesive.

The drive circuit board 122 facing the printed circuit board 104 includes the connector 12 mounted on each board.
At 3,124, they are directly fitted and connected. The drive circuit board 122 is fixed to the housing 101 with a screw, and is connected to the Hall element 103 and the winding coil 105 through a connector. According to the position detection signal of the Hall element 103, the energization of the winding coil 105 is sequentially switched. The rotation speed of the rotating body 107 is controlled at a constant speed.
The two substrates are directly connected by a connector, so that miniaturization and cost reduction can be achieved. At the same time, since there is no extra harness, radiation noise generated by switching the current supply to the winding coil 105 is minimized. The drive circuit board 122 is fixed inside the mounting reference surface 101a, and a large-sized mounting component is arranged and mounted on the outer peripheral portion of the upper surface of the drive circuit board 122 to reduce the flatness of the scanner. Further, by forming the lower surface as a solder surface and using a single-sided substrate, the cost of manufacturing the substrate can be reduced.

The rotating body 107 is unbalanced.
The rotating body 107 is set so that the vibration is at a very small level.
The balance correction is performed on the upper and lower two correction surfaces 113a and 108a.

The rotator is configured so that the center of gravity of the rotator overlaps the dynamic pressure air bearing surface in the axial direction. The unbalanced vibration in the angular displacement mode centered on the center of gravity of the rotating body is divided into components acting in opposite directions with respect to the center axis, and the unbalanced vibration of the rotating body transmitted to the outside from the fixed sleeve of the dynamic pressure air bearing. Is a dynamic pressure air bearing type motor in which the pressure is reduced.

In order to lower the position of the center of gravity of the rotating body,
The motor unit is disposed below. The motor part of the rotating body is composed of a rotor magnet 108 and a rotor yoke 125, and is divided and connected to the flange 111 at a position overlapping the dynamic pressure air bearing surface. The division and connection of the motor unit facilitates machining of the polygon mirror mounting surface with reference to the bearing surface. That is, in cutting or grinding the polygon mirror mounting surface, chucking on the bearing surface is facilitated. When the flange 111 and the motor are integrated, chucking on the bearing surface becomes difficult. Flange 11
1 and the motor unit are connected by press-fitting, shrink fit, or the like. The rotor yoke 125 may be made of a nonmagnetic material such as an aluminum alloy. However, by using a ferromagnetic material having a relatively large specific gravity, such as steel or stainless steel, the effect of lowering the position of the center of gravity of the rotating body is high. In addition, the size of the rotating body can be reduced, and the magnetic force of the rotor magnet 108 can be effectively used.

The material of the housing 101 is a metal such as aluminum die cast. In this case, the aluminum alloy is a conductive material, and the housing 101 and the rotor magnet 108 are disposed relatively close to each other.
1, an eddy current is generated, and the loss of the motor increases. Particularly at high speed rotation, the frequency of the alternating magnetic field increases, so that the loss due to the eddy current increases and the efficiency of the motor decreases. Therefore, a magnetic plate 126 made of a ferromagnetic material is disposed and fixed on the surface of the housing 101 facing the rotor magnet 108 so that the efficiency of the motor is not reduced even at a high speed rotation, thereby preventing an eddy current from flowing through the housing 101. However, the efficiency of the motor is prevented from lowering. As the magnetic plate 126, a soft magnetic material such as a silicon steel plate or soft ferrite is used.

[0051]

According to the first aspect of the present invention, the mounting reference of the radial dynamic pressure air bearing and the axial bearing is provided integrally with the mounting reference surface formed on the housing, and the respective fixing portions are directly mounted on the housing. Thus, it is possible to suppress the variation in the position of the bearing with respect to the mounting reference plane, and finally, to reduce the variation in the rotational position (radial direction, vertical direction) of the rotating body.

Further, in the state of use, the sealed state of the space in which the rotating body is arranged can be ensured.

The driving element can be arranged outside the closed space, and the cooling effect by the air blowing is high, and the driving element can be used even at high speed rotation where the heat generation of the driving element is large.

The layout of the mounted components and the wiring pattern of the drive circuit can be easily designed, the printed circuit board can be reduced in size and cost, and the outer diameter of the motor can be reduced.

According to the second aspect of the present invention, it is possible to prevent the eddy current from being generated in the housing made of a conductive material due to the leakage magnetic flux of the motor permanent magnet, thereby reducing the efficiency of the motor.

According to the third aspect of the present invention, a harness for connecting two printed boards (a printed circuit board for a drive circuit and a motor) is not required, so that cost reduction and flattened downsizing can be achieved.

According to the invention set forth in claim 4, claims 1 to
A polygon scanner having the following three features can be provided.

According to the fifth aspect of the present invention, it is possible to provide a polygon scanner in which the rotating body is housed in a closed space and which has good handleability as a polygon scanner.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a polygon scanner.

FIG. 2 is an exploded perspective view of a main part of one embodiment.

FIG. 3 is a sectional view showing an embodiment of a polygon scanner.

FIG. 4 is an exploded perspective view of a main part of one embodiment.

[Description of Signs] 21 Housing 21a Mounting reference surface 21b Beam 21c Bearing mounting reference portion 21d Outer cylinder surface 21e End surface 22 Printed circuit board 22a Outer peripheral portion 23 Stator core 23a Winding coil 23b Base 24 Hall element 26 Rotating body 27 Rotor magnet 28 Fixed Shaft 28a Groove 29 Hollow rotating shaft 30 Ring-shaped permanent magnet 31 First fixed yoke plate 32 Second fixed yoke plate 33 Fixed portion 34 Elastic member 35 Rotating portion 36 Flange 36a Micro hole 36b Correction surface 37 Polygon mirror 37a Correction surface 38 Leaf spring 39 Cover 40 Driving element 41 Circuit component 101 Housing 101a Mounting reference plane 101b Penetrating part 102 Stator core 103 Hall element 104 Printed circuit board 105 Winding coil 106 Cover 106a Opening 107 Rotating body 10 8 Rotor magnet 108a Correcting surface 109 Fixed sleeve 110 Hollow rotating shaft 110a Groove 111 Flange 112 Polygon mirror 113 Mirror holding 113a Correcting surface 114 Ring-shaped permanent magnet 115 First yoke plate 116 Second yoke plate 117 Rotation of attractive magnetic bearing Part 118 Fixing part of suction type magnetic bearing 119 Cap member 119a Microhole 120 Stopper 121 Glass window 122 Drive circuit board 123 Connector 124 Connector 125 Rotor yoke 126 Magnetic plate

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2H045 AA13 AA24 AA54 AA59 3J011 AA04 BA02 BA08 CA02 3J102 AA01 CA01 DA03 DA09 DB05 5H019 AA05 AA10 BB05 BB15 BB20 CC04 DD01 EE14 FF01 FF03 5H621 GA01 J04K10 J01K04J11

Claims (5)

[Claims] 1. A rotating body is supported by a radial bearing and an axial bearing in a radial direction and an axial bearing, respectively, a permanent magnet is fixed to the rotating body, and a magnetic gap is formed in a radial direction to drive the rotating body. A radial gap type direct current brushless motor comprising a motor, and a radial bearing, an axial bearing, and a fixed portion of the motor fixed to a central portion of a housing provided with a mounting portion, wherein the brush is provided between the mounting portion of the housing and a rotation center shaft. A through-hole, a board fixed to the housing so as to cover the through-hole from the outside, and a motor position detection element mounted on the board so as to be disposed in the through-hole. DC brushless motor. 2. The brushless motor according to claim 1, wherein said housing is made of a conductive material, and a magnetic plate made of a ferromagnetic material is fixed to a surface of said housing facing said permanent magnet. motor. 3. The DC brushless motor according to claim 1, wherein a first connector is mounted on a board on which the position detecting element is mounted, and a second connector is mounted on a drive circuit of the motor. A direct current brushless motor, wherein a first connector and a second connector are directly fitted and connected. 4. The DC brushless motor according to claim 1, wherein a polygon mirror is fixed to the rotating body. 5. The brushless motor according to claim 4, wherein said housing has a cover provided with a laser beam input / output section, and said rotating body is housed in a closed space. .