JP5239305B2 - Motor and electronic device using the same - Google Patents

Description

  The present invention relates to a motor and an electronic device using the motor.

  In an electronic device such as a laser printer, a paper feeding roller (driven body) provided in a main body case is connected to a motor, and the paper feeding roller is rotated by driving the motor to feed paper to a predetermined portion. ing.

  The motor includes a stator having a plurality of magnetic poles arranged on the outer periphery at a first predetermined interval and a rotor arranged on the outer periphery of the stator. The inner periphery of the rotor is different at every second predetermined interval. It has a structure in which magnets magnetized on the poles are arranged.

  Further, the magnetic pole of the stator is formed with an extended portion extending from the magnetic pole base portion in a direction substantially parallel to the magnet, thereby increasing driving efficiency.

That is, the width of the magnet (in the direction orthogonal to the circumferential direction) is larger than the width in the same direction of the magnetic pole base of the stator so as to be as close as possible to the magnetic detection element that magnetically detects the rotation of the rotor. For this reason, conventionally, an extension called an end plate extending in a direction substantially parallel to the magnet is formed from the magnetic pole base of the stator, thereby increasing the facing area between the magnetic pole of the stator and the magnet, thereby It is trying to increase driving force and driving efficiency. A technique similar to this is described in, for example, Patent Document 1 below.
Japanese Patent Laid-Open No. 9-285044

  As described above, in the conventional motor in which the extension extending from the magnetic pole base portion of the stator magnetic pole in a direction substantially parallel to the magnet is formed, the facing area between the rotor magnet and the magnetic pole of the stator is increased. Has a large driving force and was able to increase the driving efficiency.

  However, with such a configuration, there is a possibility that the rotation detection of the rotor by the magnetic detection element may be difficult due to the influence of the extension. That is, by providing such an extension, it is possible to enhance the magnetic flux collection effect, but since the magnetic flux from the magnet is easily drawn into the stator by the extension, sufficient magnetic flux is not transmitted to the magnetic detection element. . Further, since the magnetism generated in the stator is released as a magnetic flux from the extension portion, such a magnetic flux affects the magnetic detection element as noise.

  Therefore, an object of the present invention is to improve the magnetic detection accuracy of a magnetic detection element while maintaining efficient driving using an extension.

  In order to achieve the above object, a motor of the present invention includes a stator mounted on a substrate and having a plurality of magnetic poles arranged at a first predetermined interval on an outer peripheral portion, and a rotor arranged rotatably on the outer periphery of the stator. A magnet magnetized with a different polarity is arranged on the inner circumference of the rotor at every second predetermined interval, a magnetism detecting element is arranged on the substrate surface so as to face the magnet, and the outer circumference of the stator magnetic pole At the end, an extension is formed that extends from both sides of the magnetic pole base toward one of the substrate side and the other on the opposite side, and one of the extensions extending toward the other and the other. The distance between the extended portion and the magnet at the distal end is larger than the distance between the extended portion and the magnet at the other end, thereby achieving the intended purpose.

  As described above, the present invention has a configuration in which one extension portion on the substrate side and the other extension portion are provided on the magnetic pole of the stator, so that the magnetism collecting effect can be enhanced, and thus the driving efficiency is enhanced. Can do. Further, at the outer peripheral end of the magnetic pole of the stator, an extension is formed extending from both sides of the magnetic pole base toward one of the substrate side and the other on the opposite side, and extends toward the one and the other. Among the extended portions, the distance from the magnet at the distal end portion of one of the extended portions is larger than the distance from the magnet at the distal end portion of the extended portion extended to the other. As a result, it is possible to improve the magnetic detection accuracy of the magnetic detection element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
In this embodiment, an example of a paper feed motor incorporated in a laser printer as one of electronic devices will be described. The motor in the present embodiment is placed together with various electronic components on a substrate disposed in a horizontal direction in a main body case (not shown) of the laser printer.

  FIG. 1 is a cross-sectional view of a motor according to an embodiment of the present invention. FIG. 2 is a perspective view of the stator of the motor according to the embodiment of the present invention. First, an example of the configuration and operation of the motor will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the motor 12 of this embodiment includes a stator 13 mounted on a wiring board 11 as a board via a fixture (not shown), and is rotatably disposed on the outer periphery of the stator 13. And a cylindrical rotor 14 whose lower surface is open. Further, a ring-shaped magnet 15 magnetized alternately in N and S poles (adjacent poles are different from each other) is integrally fixed to the inner periphery of the rotor 14 at predetermined intervals. The stator 13 is formed as a laminated body in which a plurality of plate-like bodies are laminated. As shown in FIG. 2, a plurality of magnetic poles 13a are arranged at predetermined intervals in the circumferential direction on the outer peripheral portion of the stator 13, and a magnetic circuit portion inside each magnetic pole 13a has an electromagnet coil. 16 is wound.

  That is, by applying AC power to the coil 16, each magnetic pole 13a is alternately magnetized to the N pole and the S pole, and an attractive force and a repulsive force are generated between the magnet 15 existing on the outer periphery thereof, and this is the rotor. It is comprised so that it may become 14 rotational drive force.

  The stator 13 is fixed to the wiring board 11 via a holding portion (not shown), and a bearing 17 is provided on the inner periphery of the stator 13. A drive shaft 18 is provided through the bearing 17 in the vertical direction, and the upper end of the drive shaft 18 is fixed to the top surface 14 a of the rotor 14. In the present embodiment, the direction in which the rotor 14 is present will be described with respect to the wiring board 11 as the upward direction, and vice versa. That is, in the drive shaft 18, the end portion in the direction of the rotor 14 from the wiring board 11 is an upper end portion, and the opposite end portion is a lower end portion. Further, in the wiring board 11, the side where the rotor 14 is located is described as an upper surface, and the back side is described as a lower surface as appropriate.

  With the above configuration, AC power is applied to the coil 16 to magnetize the magnetic poles 13a alternately with N and S poles, and generate attractive and repulsive forces between the magnetic poles 13a and the magnet 15. In this case, the rotor 14 rotates about the drive shaft 18 and the rotational force is transmitted to the paper feed roller via the drive shaft 18.

  Specifically, in the present embodiment, the lower end of the drive shaft 18 passes through a through hole (not shown) of the wiring board 11 and extends below the wiring board 11, and a gear (not shown) is provided below the drive shaft 18. And a gear box (not shown) is connected to the gear, whereby a plurality of paper feed rollers (not shown) in the laser printer are rotated to feed the paper. Yes. That is, the laser printer as the electronic apparatus of the present embodiment includes a main body case, a paper feed roller as a driven body provided in the main body case, and the motor 12 coupled to the driven body. Prepare.

  In addition, a Hall IC 19 is mounted as a magnetic detection element at a portion corresponding to the lower end of the magnet 15 on the wiring board 11. That is, the Hall IC 19 is disposed on the surface of the wiring board 11 so as to face the magnet 15. As is well known, the Hall IC 19 detects the rotation speed and rotation amount of the rotor 14 and controls the rotation speed of the motor 12 using the detected rotation information.

  In particular, in the present embodiment, the Hall IC 19 is arranged on the lower surface of the wiring board 11. That is, the Hall IC 19 is disposed on the surface of the wiring board 11 opposite to the surface on the rotor 14 side. By adopting such a configuration, it is possible to suppress the occurrence of problems such that the Hall IC 19 and the rotating magnet 15 are in contact with each other. Furthermore, the magnet 15 has a shape in which the lower end thereof extends to the Hall IC 19, that is, the vicinity of the upper surface of the wiring board 11 in order to be as close as possible to the Hall IC 19.

  As a conclusion, the vertical dimension of the magnet 15 is large, and accordingly, in this embodiment, as shown in FIGS. 1 and 2, the magnetic pole base portion is provided at the outer peripheral end of each magnetic pole 13a of the stator 13 as shown in FIGS. From both sides of 13d toward the outside, an extension portion 13b extending upward in the direction substantially parallel to the magnet 15, that is, the axial direction of the drive shaft 18, and an extension portion 13c extending downward are integrally formed. ing.

  Specifically, the extension portions 13b and 13c are the outermost layers of a plurality of stacked plate-like bodies constituting the stator 13, and the outer peripheral portion of the two plate-like bodies including the lower surface is replaced with the magnet 15. And bent in such a manner that they are substantially parallel to each other and upward and downward.

  Of the plurality of stacked plate-like bodies constituting the stator 13 in this manner, the outer peripheral portion of the upper and lower surfaces (each including the outermost layer) is substantially parallel to the magnet 15. If the extension portions 13b and 13c are formed by bending them upward and downward, respectively, the area facing the magnet 15 extended upward and downward is increased as shown in FIG. A driving force is given. Such extension portions 13b and 13c are called end plates, and can increase the magnetic flux drawn into the plate-like body of the stator 13 by the magnetic flux collecting effect of the end plates. Can be given.

  In particular, in the motor according to the present embodiment, as shown in FIG. 1, the extension portions 13 b and 13 c have an asymmetric cross-sectional shape in comparison of the cross-sectional shapes of the extension portion 13 b and the extension portion 13 c. Thus, the magnetic base 13d has a structure extending outward from both sides. In FIG. 1, as an example of the extension 13 b and the extension 13 c having an asymmetric cross-sectional shape, one extension 13 c on the wiring board 11 side is the other extension 13 c on the top surface 14 a side of the rotor 14. Compared to the extension portion 13 b, the bent tip portion of the extension portion is arranged to be closer to the inner side of the stator 13.

  As a more specific structure of the extension portion 13b and the extension portion 13c, first, the extension portion 13b extended in the direction of the top surface 14a of the rotor 14 is substantially parallel to the magnet 15, that is, the magnetic pole base at the outer peripheral end of the magnetic pole 13a. The structure is bent at a right angle upward from 13d. On the other hand, as shown in FIG. 1, the extension portion 13 c extending in the direction of the wiring substrate 11 has a tip portion further inward of the stator 13 than the extension portion 13 b that is substantially perpendicular. It is made into the structure bent so that may be arranged.

  By the way, as described above, by providing an extension portion called an end plate at the end portion facing the magnet of the stator 13, more magnetic flux from the magnet of the rotor can be taken into the plate-like body of the stator 13. it can. However, when the magnetic flux taken into the stator 13 is increased, the magnetic flux supplied to the magnetic detection element is reduced, and as a result, the accuracy of detection of the rotational speed and position by the magnetic detection element is reduced.

  Therefore, in the motor of the present embodiment, as described above, the extension 13c on the side on which the Hall IC 19 as the magnetic detection element is mounted is used to suppress a decrease in accuracy of the magnetic detection element due to such an end plate. Compared to the other extension portion 13b, the tip end portion is arranged to be closer to the inner side of the stator 13. In other words, the bent tip of one extension 13c on the wiring board 11 side is arranged so that the distance from the magnet 15 is wider than the bent tip of the other extension 13b. For this reason, the magnetic flux taken into the extension part 13c on the side where the Hall IC 19 as the magnetic detection element is mounted is, for example, compared to a case where the extension part 13c is bent substantially perpendicularly downward from the magnetic pole base part 13d. Less. For this reason, the magnetic flux component reduced in the magnetic flux taken into the extension part 13c is supplied to the Hall IC 19.

  Further, when the extension portion 13b and the extension portion 13c are provided so that the cross-sectional shape in both the upper and lower directions is asymmetric as in the present embodiment, the magnetic center is shifted from the vertical center of the stator 13. The balance between the suction and repulsion force between the upper and lower portions of the stator 13 is also asymmetrical in the vertical direction, which may cause deterioration of rotational accuracy and generation of noise vibration.

  For this reason, the motor according to the present embodiment has the following configuration. That is, the magnet end on the side of the wiring board 11 protrudes in the direction of the wiring board 11 from the tip of the extension part 13c. More specifically, as shown in FIG. 1, the downward length Lc of the magnet 15 is longer than the upward length Lb of the magnet 15 from the vertical center line AA ′ of the stator 13. The lower end portion of the magnet 15 is configured to protrude further in the direction of the wiring substrate 11 from the position facing the bent tip portion of the extension portion 13c so as to be longer. In the present embodiment, with respect to the direction of the extension portion 13b, a configuration example is given in which the facing positions of the upper end portion of the magnet 15 and the bent tip portion of the extension portion 13b substantially coincide.

  Thus, by making the magnet 15 overhang only on the Hall IC 19 side, it is possible to correct the magnetic center shift due to the difference in the amount of magnetic flux between the upper extension 13b and the lower extension 13c. It is possible to suppress the deterioration of rotational accuracy based on the asymmetrical extension, and to reduce noise and vibration. Further, as a specific method for correcting the deviation of the magnetic center, for example, the difference in magnetic flux amount between the average gap of the Lb portion and the average gap of the Lc portion is calculated by permeance calculation.

  Next, another example of the motor of the present embodiment will be described. As described above, the cross-sectional shapes of one extension extending toward the wiring board 11 and the other extension extending toward the top surface 14a of the rotor 14 are asymmetrical toward the outer sides on both sides of the magnetic pole base 13d. And the bending tip of one extension is arranged so that the distance from the magnet 15 is wider than the bending tip of the other extension, while minimizing the reduction in driving force. The Hall IC 19 can be supplied with a magnetic flux sufficient to obtain detection accuracy necessary for detection of rotation or the like. For this reason, implementations other than the configuration shown in FIG. 1 are possible.

  3 and 4 are cross-sectional views of other examples of the motor according to the present embodiment. In these drawings, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  First, FIG. 3 shows a configuration example in which one extension 23c on the wiring board 11 side is arranged so that the number of plate-like bodies constituting the extension is smaller than the other extension 13b. Yes. Specifically, the two laminated plate-like bodies each including the outermost layer of the extension portion 13 b are bent in a direction substantially parallel to the magnet 15 so as to be substantially parallel to the magnet 15.

  Further, the one plate-like body having the extension 23 c as the outermost layer is bent in a direction substantially parallel to the magnet 15 so as to be substantially parallel to the magnet 15. In addition, for example, the extension portion 13b has a structure including three stacked plate-like bodies including the outermost layer, and the extension portion 23c includes two stacked plate-like bodies including the outermost layer. May be.

  In any case, the distance between the tip of the extension 23c and the magnet 15 is larger than the distance between the tip of the extension 13b and the magnet 15.

  Next, FIG. 4 shows that in the plate-like body constituting one extension portion 33c on the wiring board 11 side, the length of the extension portion of the plate-like body closest to the magnet 15 is the extension of the other plate-like body. The example of a structure arrange | positioned so that it may become shorter than the length of a part is shown. Specifically, the extension portion 33 c is composed of two laminated plate-like bodies including the outermost layer, and is bent in a direction substantially parallel to the magnet 15 so as to be substantially parallel to the magnet 15. . Furthermore, in the length from the magnetic pole base portion 13d extended to the wiring board 11 side of the extension portion 33c to the tip portion, the length of the plate-like body extension portion close to the magnet 15 is longer than that of the other plate-like body extension portions. The structure is shorter than the length. Further, in this case, the length of each plate-shaped body constituting the stator 13 is the same length, and, for example, by simply folding two sheets from the outermost layer, the plate-shaped body of the outermost layer is formed by bending. The length of the extension by is longer than the length of the extension by the plate of the next layer. As described above, in the case of the configuration shown in FIG. 4, since the plate-like body including the extension 33c may have the same length, that is, the same shape, the production efficiency can be improved, for example, it can be produced with the same mold.

  This embodiment is also characterized in that the distance between the tip of the extension 33c and the magnet 15 is larger than the distance between the tip of the extension 13b and the magnet 15.

  Also, in the configuration shown in FIG. 3 and FIG. 4, as in the configuration shown in FIG. 1, compared to the upward length Lb of the magnet 15 from the vertical center line AA ′ of the stator 13, A structure in which the lower end portion of the magnet 15 protrudes further in the direction of the wiring board 11 from the position facing the bent tip of the extension portions 23c and 33c so that the downward length Lc of the magnet 15 is longer. Yes. As a result, deterioration of rotational accuracy based on the asymmetrical extension is suppressed, and noise vibration is reduced.

  In addition, as another embodiment, for example, one extension portion on the wiring board 11 side is configured so that the length of the extension portion is shorter than the other extension portion, etc. Various modifications are possible.

  As described above, even with the structure shown in FIGS. 3 and 4 and the like, the magnetic flux taken into the extension 23c and the extension 33c is smaller than that of the extension 13b, for example. For this reason, of the magnetic fluxes taken into the extension portions 23c and 33c, the magnetic flux component reduced by such a structure is supplied to the Hall IC 19.

  As described above, in the motor of the present invention, the outer peripheral end of the magnetic pole is extended from both sides of the magnetic pole base to the outside so as to be asymmetric in cross-section in the direction substantially parallel to the magnet. The extension portion is formed, so that the bent tip portion of one extension portion on the substrate side can be more widely spaced from the magnet than the bent tip portion of the other extension portion. The magnetic flux component reduced in the magnetic flux taken into the extended portion can be supplied to the magnetic detection element such as the Hall IC. Therefore, according to the motor of the present invention, it is possible to improve the magnetic detection accuracy of the magnetic detection element while maintaining efficient driving using the extension. Further, by incorporating the motor of the present invention into an electronic device such as a laser printer, for example, it is possible to provide an electronic device capable of efficiently driving the motor while suppressing uneven rotation and noise.

  For example, the extension 13b may be deformed to the magnet 15 side due to some stress during long-term use, and may be in contact with the rotor 14 when it rotates. In order to cope with such a case, instead of the configuration in which the extension portion 13b is substantially parallel to the magnet 15, the bending tip side of the extension portion 13b is also arranged on the inner side of the stator 13 compared to the bending root portion. It is good also as a structure which enlarges the amount of bendings.

  Similarly, when such an extension portion is deformed to the magnet 15 side and there is a risk of contact when the rotor 14 rotates, the extension portion is slightly moved inward of the stator 13 from the position shown in FIG. You may start up from that position.

  Moreover, in the said embodiment, the structural example which formed the extension part mainly using two plate-shaped bodies from the outermost layer among several laminated | stacked plate-shaped bodies which comprise the stator 13 is given. As described above, in the case of corresponding to the configuration of FIG. 1, a configuration in which one or a plurality of plate-like bodies are used may be used. In addition, in the case of corresponding to the configuration of FIG. 2, an extension is formed by using a plurality of plate-like bodies from the uppermost outermost layer, and on the lower side, a plate-like shape having a number equal to or lower than the uppermost number The structure which forms an extension part using a body may be sufficient. Furthermore, in the case of corresponding to the configuration of FIG. 3, a configuration in which a plurality of upper and lower plate-like bodies are used may be used.

  According to the present invention, it is possible to provide a motor that improves the magnetic detection accuracy of the magnetic detection element while maintaining efficient driving. Therefore, the present invention is suitable for motors used in electronic devices such as laser printers and laser copying machines. is there.

Sectional drawing of the motor in embodiment of this invention The perspective view of the stator of the motor in embodiment of this invention Sectional drawing of the other Example of the motor in embodiment of this invention Sectional drawing of the further another Example of the motor in embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Wiring board 12 Motor 13 Stator 13a Magnetic pole 13b, 13c, 23c, 33c Extension part 13d Magnetic pole base 14 Rotor 15 Magnet 16 Coil 17 Bearing 18 Drive shaft 19 Hall IC

Claims (10)

A stator mounted on the upper surface of the substrate and having a plurality of magnetic poles wound with a coil around the outer periphery at a first predetermined interval; and a rotor rotatably disposed on the outer periphery of the stator. Around the circumference, a magnet magnetized with a different polarity is arranged at every second predetermined interval, and a magnetic detection element is arranged on the lower surface of the substrate so as to face the magnet with the substrate interposed therebetween, the outer peripheral end portion of the magnetic poles of the stator, from both sides of the base of the pole, one of the substrate side, to form an extension extended toward the other of the opposite side, extended towards these one and the other of extension, the motor, characterized in that the distance between the magnets in the tip portion of the one of the extension, is larger than a distance between the magnet at the distal end of the other extension. 2. The stator according to claim 1, wherein the stator is formed by laminating plate-like bodies, and an extension portion is formed by bending at least the outermost plate-like body of the laminate body in a direction substantially parallel to the magnet. The motor described. The stator is formed by laminating plate-like bodies, and a plurality of laminated plate-like bodies including at least the outermost layer of this laminate are bent in a direction substantially parallel to the magnet to form an extension. The motor according to claim 1. 4. The motor according to claim 2, wherein one of the extension portions is disposed such that a bent tip end portion of the extension portion is located on an inward side of the stator as compared with the other extension portion. 4. The motor according to claim 3, wherein the one extension portion is arranged so that the number of plate-like bodies constituting the extension portion is smaller than that of the other extension portion. One of the extension portions is arranged such that in the plate-like body constituting the extension portion, the length of the plate-like body closest to the magnet is shorter than the length of the other plate-like body. The motor according to claim 3. 4. The motor according to claim 2, wherein one of the extension portions is disposed so that the length of the extension portion is shorter than that of the other extension portion. The motor according to any one of claims 1 to 7, wherein a magnet end portion on the substrate side is protruded in a substrate direction from a tip portion of one of the extension portions. The motor according to claim 1 , wherein a Hall IC is used as the magnetic detection element. An electronic apparatus comprising a main body case, a driven body provided in the main body case, and a motor connected to the driven body, wherein the motor according to any one of claims 1 to 9 is used as the motor. .

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