JP4488437B2 - Sealed polygon scanner - Google Patents

Description

  The present invention relates to a brushless motor and a sealed polygon scanner.

  Polygon scanners are required to rotate at speeds exceeding 30000 rpm with high-speed printing and high image quality in digital copiers and laser printers, etc., but the temperature caused by motor vibration and motor heat generation due to unbalanced rotating bodies The rise is a problem.

  The unbalance of the rotating body can be suppressed to a certain extent by correcting, but the unbalance of the rotating body changes due to the heat generated by the motor, and the corrected one greatly deteriorates. In addition to the above-mentioned vibration problem, the motor temperature rise shortens the life of the bearings and causes deterioration of optical components arranged in the vicinity of the motor. Has become important.

  Conventionally, on the heat generating surface, the outer periphery of the rotating body has a substantially spherical shape to reduce windage loss, or heat radiating fins are provided to reduce the temperature rise. However, when rotating at a higher speed, eddy current loss due to leakage magnetic flux from the rotor magnet becomes large, and there is a problem that such a method cannot be solved.

  For example, in the technique disclosed in Patent Document 1, in an outer rotor type polygon scanner motor, the outer diameter of the rotor is made substantially spherical, thereby reducing loss (windage loss) and increasing the temperature of the motor. I'm trying to suppress it. However, with this technology, although there is an effect of reducing the windage loss of the motor loss, in the case of the aluminum housing, the eddy current loss due to the magnetic flux leaking from the rotor magnet is large, and the temperature of the motor due to this eddy current loss is large. The rise is a problem.

  In the technique disclosed in Patent Document 2, in an outer rotor type polygon scanner, the balance correction groove is arranged at the center of the center of gravity, and the balance is corrected at one place to suppress the vibration of the motor. In this technique, there is no disclosure about the point of loss, but as far as judging from the drawings, the magnetic path of the rotor magnet is open on the outer periphery of the rotor and the housing side (downward), and the magnetic flux is applied to the housing or the cover. When leakage occurs and the housing is made of a material such as aluminum, the eddy current loss is large and the temperature rise of the motor becomes a problem.

The problem as described above 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 copying machines and laser printers, the polygon scanner is required to rotate at a high speed exceeding 30000 rpm. In order to achieve such high-speed rotation, a polygon scanner using a dynamic pressure air bearing has been conventionally used.

  In the polygon scanner using this dynamic pressure air bearing, there is a problem of increased noise due to wind cutting of the polygon mirror during high-speed rotation, an increase in load (heat generation) due to windage loss, and a bearing portion due to intrusion of dust into the air bearing portion. In order to avoid such damage, a sealed structure with a motor housing is employed.

However, since the motor housing as described above accommodates the rotating body including the polygon mirror, the bearing portion, and the motor portion, the size of the motor housing increases as a whole, which hinders the layout of the optical housing in which the optical lens and the like are installed. .
In particular, when the control circuit board is housed in the motor housing, the temperature of the entire polygon scanner increases as the temperature rises, and the problems associated with the temperature rise (for polygon scanners, increased vibration, reduced circuit element reliability, In addition, when the entire optical housing is considered, temperature deterioration of optical elements such as lenses and lasers is caused.

JP-A-8-154371 Japanese Patent Laid-Open No. 10-216331

  The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a brushless motor capable of reducing eddy current caused by a motor magnet and suppressing a rise in motor temperature at low cost. is there. The second object is to achieve miniaturization and cost reduction of the motor and motor housing while ensuring the reliability of the bearing, and to reduce the temperature rise and improve the reliability of the control circuit board. It is to provide a sealed polygon scanner. The other objects of the present invention will be clarified by the following description.

  In order to achieve the above object, a brushless motor according to the present invention is a brushless motor having a magnetic gap in the radial direction. The rotor magnet is an open magnetic path in the state of a rotating body, and the axial direction and the radial direction of the open magnetic path. A single magnetic member is arranged so that the leakage magnetic flux is interlinked.

  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, it is preferable that 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 the motor housing.

  In the brushless motor according to the present invention, a motor rotational 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 an aluminum alloy, a magnesium alloy, or 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 polygon mirror in a motor housing, a hydrodynamic air bearing that rotatably supports a rotating body, a magnetic bearing that floats and supports in the axial direction, the polygon mirror, In a hermetic polygon scanner having a motor unit for driving the body, the motor housing is made of a single metal member , and has a projecting portion at the central portion, and the outer peripheral surface of the projecting portion and the inner side of the motor housing are magnetized. covered with the body, the fixed shaft of the dynamic pressure air bearing and constant bus main solid baked on the inner peripheral portion of the protruding portion, the core subjected to motor windings fixed on the magnetic material covering the outer peripheral surface of the projecting portion, the lower end face of the core are those fixed axis and wherein the kite is located between the axial length to be fit secured baked to the motor housing.

Also, closed type polygon scanner according to the present invention, the motor housing, an opening for communicating the harness for electrically connecting the motor substrate and the control circuit board is provided to fix the control circuit board to the lower motor housing It is characterized in that the support post is integrally formed. Furthermore, the hermetic polygon scanner according to the present invention has an opening for communicating a harness for electrically connecting the motor board and the control circuit board to the motor housing , and a laser incident / exit side with respect to the optical housing mounting surface. It is preferable to provide in.

  The sealed polygon scanner according to the present invention is characterized in that a circumferential groove for removing stress is provided in the 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 used as the motor. It is preferably fixed to the lower part of the housing.

According to the present invention, the following effects can be obtained.
(1) In the dynamic pressure air bearing type polygon scanner according to the present invention, the motor housing is made of a single metal member and has a protruding portion at the central portion, and the outer peripheral surface of the protruding portion and the inner side of the motor housing Cover with magnetic material, fix the fixed shaft of the hydrodynamic air bearing to the inner peripheral part of the protruding part, and fix the core with the motor winding on the magnetic body covering the outer peripheral surface of the protruding part. Since the lower end surface of the core is positioned between the axial lengths in which the fixed shaft is fixed to the motor housing by shrinkage, it is possible to reduce eddy current loss (motor temperature rise) generated in the motor housing at low cost.
( 2 ) Further, the motor housing is provided with an opening for communicating a harness for electrically connecting the motor board and the control circuit board, and a column for fixing the control circuit board is integrally formed at the lower part of the housing. As a result, the heat generated by the control circuit board can be efficiently radiated, and the temperature rise of the entire polygon scanner can be reduced.
( 3 ) Further, the motor housing can be thinned by providing the motor housing with an opening for communicating a harness for electrically connecting the motor board and the control circuit board.
( 4 ) By providing a circumferential groove for stress relief at the projecting portion at the center of the motor housing, it is possible to prevent stress from being transmitted to the fixed shaft shrinkage portion when the caulking of the motor core is fixed. Accurate fixation is possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to 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. As shown in the figure, in the hydrodynamic air bearing type polygon scanner according to the present embodiment, the flange 2 made of an aluminum alloy having a polygon mirror portion 2a on the outer periphery of a cylindrical ceramic rotating sleeve 1 is shrunk. Or press-fitted and fixed.

  Above the rotating body A, a rotating yoke 3 (made of a magnetic body) 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, shrinkage, or bonding, and has a function of closing the upper end opening portion of the rotating sleeve 1. A rotor magnet 5 is disposed below the flange 2 and constitutes 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 like the rotary sleeve 1 and has a herringbone-shaped dynamic pressure generating groove 16a formed on the outer diameter surface thereof. The hydrodynamic bearing gap formed by the outer peripheral surface of the fixed shaft 16 and the inner peripheral surface of the rotary sleeve 1 is fitted with a few μm. A permanent magnet assembly for a magnetic bearing (consisting of a magnet 32 and upper and lower magnetic plates 30, 31) that constitutes an axial bearing is disposed on the 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 protrusion 3a of the magnetic body 3 and uses the attractive force acting between the gaps to move the rotating body A in the axial direction. Non-contact support. In addition, a fine hole that connects the upper air reservoir 34 formed by the fixed shaft 16 and the rotating body A and the outside of the rotating body A forms the air reservoir 34 such as the magnetic body 3, the lower closing member 35, or the member 4. The magnetic bearing is provided with damping characteristics (not shown).

  There are unbalance correction parts at the top and bottom of the rotating body A, the upper side is coated with an adhesive or a part thereof is cut off in the recess 2b of the flange 2, and the lower side is bonded to the flange 2 or the inner peripheral surface of the rotor magnet 5 An agent is applied or a part of the outer periphery or lower end surface portion of the flange 2 is cut off. In order to reduce vibration during high-speed rotation, the unbalance amount at each location 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 rotated by referring to the signal output from the Hall element 12 mounted on the motor board 13 as a position signal by the magnetic field of the rotor magnet 5 and switching the excitation of the stator winding by the drive circuit. . 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 an outer diameter portion thereof is held by the flange 2 so as not to be broken by a centrifugal force during high-speed rotation.

  The rotor magnet 5 may be a metal magnet having a centrifugal strength, but it is easy to reduce the thickness, and a plastic magnet is more desirable if it has the outer diameter holding mechanism as described above. Further, the rotor magnet 5 has a magnetic path open in the outer diameter and height direction other than the inner diameter, and a Hall element 12 for switching excitation of the motor is disposed in the open magnetic path.

  The magnetic body 14 has a function of shielding leakage magnetic flux 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 a magnetic body must be provided on the outer diameter side of the rotor magnet 5 in order to make this a closed magnetic path, which increases the number of parts. This is to prevent the unbalance change from increasing.

  Although it is conceivable to arrange a magnetic body on the outer diameter of the rotor magnet 5, for this purpose, the magnetic flux of the rotor magnet 5 does not leak in the outer diameter direction. It must be arranged (between the stator core 11 and the rotor magnet 5). As described above, the high-speed polygon scanner of 30000 rpm or more has a problem of shortening the start-up time. Since a large current flows at the start-up, the magnetic field of the stator core 11 causes the Hall element 12 to malfunction and cause a start-up failure. There is a problem and it is preferable to use an open magnetic path.

  Hereinafter, the magnetic part 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. This magnetic body 14 has an L-shaped cross section in order to reduce eddy currents due to leakage magnetic fluxes in both the downward and radial directions of the leakage magnetic flux of the rotor magnet 5. Conventionally, the lower leakage flux is a thin circular magnetic body, and the radial leakage flux is a thin ring-shaped magnetic body, which are arranged separately in each direction. End up.

  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 the fixing is performed by using a restoring force when the strip-shaped magnetic body is deformed into a curved surface. As a result, the assemblability is improved by integrating the magnetic material as in the present invention.

  The assembly can be easily fixed by a method such as caulking or press-fitting the inner peripheral portion of the magnetic body 14 into the outer diameter portion 15e of the motor housing convex portion. The upper end height in the radial direction of the 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, 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. In the magnetic body 214 according to the present embodiment, as compared with the magnetic body 14, a protrusion having an L-shaped cross section is also provided on the inner peripheral portion, and a motor core is fixed to that portion. 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 performed by appropriately selecting, for example, caulking, press fitting, screw fixing, and adhesion.

  Along with fixing the motor core, a coil winding (not shown) is soldered. Thereafter, since the motor assembly only needs to be inserted and fixed to the housing on which the fixed shaft is fixed, the assemblability is further simplified. In the embodiment of FIG. 1, the work is simplified when compared with the work in which the coil winding is soldered by inserting a soldering iron into the bottom of the housing.

  FIG. 3 is a partial cross-sectional side view of a hydrodynamic air bearing type polygon scanner according to still another embodiment of the present invention. The magnetic body 314 according to this embodiment is an example in which a circuit pattern is provided on the magnetic body 214 so that a Hall element, a harness, or the like can be mounted, and a motor substrate and a magnetic body are integrated. It is possible to reduce the number of parts and further simplify the assembly. By mounting up to the drive circuit element shown in FIG. 1 on the magnetic body 314, the harness can be eliminated, and the number of parts can be further reduced and the assembly can be simplified.

  Further, in the present embodiment, chatter noise due to vibration of the motor board is eliminated by integrating the motor board and the magnetic body. Conventionally, if there is a slight gap or the like on the facing surface between the motor substrate and the magnetic body, noise of the rotational frequency component and its harmonic component is generated, and thus it has been necessary to make contact with an adhesive or the like.

  On the other hand, in the outer diameter direction of the rotating body A, a motor housing 15 is disposed so as to cover the rotating body, the motor portion, and the bearing portion. The motor housing 15 is provided with an opening 15a for entering and exiting the laser. The opening 15a is shielded from the wind noise of the polygon mirror by a laser light transmitting member 18 made of a material such as glass. . In addition, a fixed shaft 16 is installed and fixed on the inner peripheral portion of the projecting portion 15b (preferably shrinkage) at the center portion of the motor housing 15, and the motor core 11 is installed and fixed on the outer peripheral portion of the projecting portion 15b (shrinkage, Caulking is preferred).

  Further, circuit elements 25 to 28 for controlling the rotational speed of the motor are mounted on the control circuit board 24 below the motor housing 15. The material of the control circuit board 24 is made of metal, and therefore, a circuit pattern is provided only on the circuit element mounting surface side.

  In the present embodiment, since the control circuit board 24 is formed of a metal substrate having a so-called single-sided pattern, the heating element can be efficiently cooled, and the circuit element and the lower surface portion 24a as a polygon scanner can be cooled. Since the circuit pattern does not exist, when the polygon scanner is mounted on the optical housing 50, even if the lower surface portion 24a contacts the optical housing 50 by mistake, there is no electrical damage and the safety is improved.

  On the other hand, the control circuit board 24 and the circuit elements 25 to 28 are electrically connected to the motor board 13 via the harness 23. Further, the support column 15c is protruded downward from the motor housing 15, and the control circuit board 24 is fixed. In order to enable the harness 23 to be connected, the motor housing 15 is provided with an opening 15d and is appropriately sealed with an adhesive, a cured resin, or the like depending on 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, or ferrite). Examples of suitable materials and specific resistance for the motor housing 15 are shown in Table 1 below.

The above materials can be die-cast and can easily form complex shapes.
On the other hand, examples of suitable materials and specific resistance as the material of the magnetic body 14 are shown in Table 2 below.

プレス加工により容易に図１〜３の磁性体１４形状を製作できる鋼板が好適である。

A steel plate capable of easily producing the shape of the magnetic body 14 shown in FIGS. 1 to 3 by pressing is suitable.

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

  However, in the hydrodynamic air bearing type polygon scanner according to the present embodiment, instead of the L-shaped magnetic body 14, a magnetic body on a circular flat plate disposed on the bottom surface of the motor housing 15, and the motor housing 15. Although the strip-shaped thin ring-shaped magnetic body attached to the inner peripheral surface of the nozzle is used, the dynamic pressure air bearing type polygon scanner according to the present embodiment functions effectively even with such a configuration. .

  In the dynamic pressure air bearing type polygon scanner according to the present 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. Since the lower end surface H1 of this is located in the axial direction of the axial length L to which the fixed shaft 16 is fixed, it is shortened also in the axial direction, which shows the fruit of miniaturization. .

  Further, in the dynamic pressure air bearing type polygon scanner according to the present embodiment, the control circuit board 24 is disposed below the housing, so that the cooling air is caused to flow through the control circuit board 24 below the optical housing 50, thereby providing circuit elements. The practical effect that further cooling is possible is obtained.

  Further, a magnetic body 14 is disposed as an L-shaped magnetic shield function on the inner peripheral side surface (outer peripheral surface side of the rotor magnet 5) of the motor housing 15, and an open magnetic path of the outer diameter portion of the rotor magnet 5. Thus, the eddy current loss generated in the motor housing 15 is prevented. 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, or ferrite). Since the eddy current loss can be reduced if the height of the magnetic body 14 is equal to or higher than that of the rotor magnet 5, the entire motor housing 15 may be made of a magnetic material.

  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. Since the basic configuration (feature) of the dynamic pressure air bearing type polygon scanner according to this embodiment is the same as that shown in the previous embodiment, only new features will be described below.

  The dynamic pressure air bearing type polygon scanner according to the present embodiment is a modified example of a motor housing and a motor substrate, and a motor core is fixed to an outer peripheral portion of a protruding portion 115a of the motor housing 115, and a fixed shaft is fixed to an inner peripheral portion. However, the fixed shaft 116 is fixed to the motor housing 115 by shrinkage, and the tilting of the fixed shaft (perpendicularity with respect to the mounting portion to the optical housing 50) affects the laser scanning position by the polygon mirror with high accuracy. It is fixed and fixed by shrinkage so that there is no change.

  However, the stress at the time of caulking and fixing the motor core to the outer diameter portion is also transmitted to the fixed shaft shrinkage part, and there is a possibility that the fixed shaft fixed with high precision shrinkage will fall down. Therefore, in the present embodiment, the circumferential groove 115b is provided so that stress is not transmitted when the motor core is caulked.

  According to the present embodiment, the effect of miniaturization can be given, and also the effect of preventing the stress from being transmitted to the fixed shaft shrinking portion when the motor core is caulked and fixing the motor core with high accuracy becomes possible. can get.

  According to the above embodiment, the motor board 113 is made of a metal material (for example, a steel plate) and has magnetism like the control circuit board 24. 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 current from the rotor magnet, the leakage magnetic flux direction of the rotor magnet, that is, the entire circumference (circular) is required. In addition, the motor substrate 13 of FIG. 5 only needs to be able to connect the terminals of the Hall element 12 and the coil winding to the motor substrate 13, so that it is not always necessary to have a full circumference as a motor substrate. It is possible to

  FIG. 6 is a partial cross-sectional side view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention. Since the basic configuration (feature) of the dynamic pressure air bearing type polygon scanner according to this embodiment is the same as that shown in the previous embodiment, only new features will be described below.

  In the dynamic pressure air bearing type polygon scanner according to the present embodiment, the harness 423 that connects the motor board and the control circuit board is connected through the opening 415 a on the side wall of the motor housing 415. The opening 415a communicates with the inside of the optical housing 50, and is positioned 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 thinned is obtained.

  Each of the above-described embodiments shows an example of the present invention, and the present invention should not be limited to these, and appropriate changes and improvements may be made within the scope of the present invention. Needless to say.

As described above with reference to the drawings, according to this example, the following effects can be obtained.
(1) In a brushless motor having a magnetic gap in the radial direction, a single magnet is used so that the rotor magnet is an open magnetic path in the state of a rotating body, and the leakage flux in the axial direction and the radial direction of the open magnetic path are linked. By arranging the members, it is possible to reduce eddy current loss (motor temperature rise) generated in the motor housing at low cost.
(2) The motor core assembly is fixed to the motor housing by fixing the motor core to the magnetic member and soldering the winding coil and circuit pattern to the motor housing, improving the soldering workability of the coil winding and improving the quality of the motor. And cost reduction.
(3) Further, by mounting the motor rotational position detecting element on the magnetic member, it is possible to reduce the number of parts (that is, the motor substrate and the magnetic member are integrated) and 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 a fixed shaft and a motor core are installed on the inner and outer peripheries of the central protrusion. The cost can be reduced by downsizing the housing and reducing the number of parts.
(5) Further, the motor housing is provided with an opening for communicating a harness for electrically connecting the motor board and the control circuit board, and a column for fixing the control circuit board is integrally formed at the lower part of the housing. As a result, the heat generated by the control circuit board can be efficiently radiated, and the temperature rise of the entire polygon scanner can be reduced.
(6) Further, the motor housing can be thinned by providing the motor housing with an opening for communicating a harness for electrically connecting the motor board and the control circuit board.
(7) By providing a circumferential groove for stress relief in the protrusion at the center of the motor housing, it is possible to prevent stress from being transmitted to the fixed shaft shrinkage portion when the motor core is caulked. Accurate fixation is possible.

1 is a partial side cross-sectional view of a dynamic pressure air bearing type polygon scanner according to an embodiment of the present invention. It is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to another embodiment of the present invention. It is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention. It is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention. It is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention. It is a partial side sectional view of a dynamic pressure air bearing type polygon scanner according to still another embodiment of the present invention. It is a partial side sectional view showing an 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 substrate, 14, 214, 314: Magnetic body, 15, 115, 215: Motor housing, 15a: Opening, 15b: Protruding portion, 115b: Circumferential groove, 16: Fixed shaft, 16a: Dynamic pressure generating groove, 22: Thin ring magnet body 24: control circuit board, 32: magnet assembly, 34: air reservoir.

Claims (5)

A sealed type comprising a dynamic pressure air bearing that rotatably supports a polygon mirror and a rotating body in a motor housing, a magnetic bearing that floats and supports in the axial direction, and a motor unit that drives the polygon mirror and the rotating body. In the polygon scanner,
The motor housing is made of a single metal member, and has a protruding portion at the center portion.
Cover the inner side of the motor housing from the outer peripheral surface of the protrusion with an integral magnetic body,
The upper end height in the radial direction of the projecting portion having an L-shaped cross section that covers the inside of the motor housing of the magnetic body has a height equal to or higher than the upper end of the rotor magnet disposed on the rotating body,
On the surface of the magnetic body between the outer peripheral surface of the protrusion and the inner side of the motor housing, a motor board on which a Hall element for switching excitation of the motor is mounted is fixed.
A fixed shaft of the hydrodynamic air bearing is fixed to the inner peripheral portion of the protruding portion.
Wherein on the outer peripheral surface of the L-shaped cross section projecting portions of the magnetic body covering the outer peripheral surface of the projecting portion is to secure the core subjected to the motor windings,
A sealed polygon scanner characterized in that the lower end surface of the core is positioned within a range of an axial length in which the fixed shaft is fixed to the motor housing by shrinkage. The motor housing is provided with an opening for communicating a harness for electrically connecting the motor board and the control circuit board, and a support column for fixing the control circuit board is integrally formed at the lower part of the motor housing. The hermetic polygon scanner according to claim 1. 2. The motor housing according to claim 1, wherein an opening for communicating a harness for electrically connecting the motor board and the control circuit board is provided on the laser incident / exit side with respect to the optical housing mounting surface. The sealed polygon scanner described in 1. 2. The hermetic polygon scanner according to claim 1, wherein a circumferential groove for removing stress is provided in a protruding portion at a central portion of the motor housing.   An optical housing in which the sealed polygon scanner according to any one of claims 1 to 4 and an optical lens are installed.

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