U.S. patent application number 14/949309 was filed with the patent office on 2016-06-23 for rotary body driving apparatus.
The applicant listed for this patent is Shinano Kenshi Kabushiki Kaisha. Invention is credited to Masayuki KODANI, Nobuchika MARUYAMA.
Application Number | 20160181888 14/949309 |
Document ID | / |
Family ID | 54544913 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160181888 |
Kind Code |
A1 |
KODANI; Masayuki ; et
al. |
June 23, 2016 |
Rotary Body Driving Apparatus
Abstract
The rotary body driving apparatus comprises: a rotary body
having a plurality of reflective surfaces; a rotor being attached
to a rotor shaft together with the rotary body; a stator housing
having a bearing section; a motor substrate for detecting a
rotational position of the rotor; a circular magnetized section for
frequency generation facing the motor substrate; a circular
frequency generation pattern, which faces the magnetized section,
being provided to the motor substrate and disposed close to the
magnetized section; a position detecting section, which corresponds
to a reference reflective surface of the rotary body, being
radially outwardly or inwardly projected from a part of the
magnetized section; and a magnetic sensor, which faces the position
detecting section, being provided to the motor substrate.
Inventors: |
KODANI; Masayuki; (Ueda-shi,
JP) ; MARUYAMA; Nobuchika; (Ueda-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shinano Kenshi Kabushiki Kaisha |
Ueda-shi |
|
JP |
|
|
Family ID: |
54544913 |
Appl. No.: |
14/949309 |
Filed: |
November 23, 2015 |
Current U.S.
Class: |
310/68B |
Current CPC
Class: |
H02K 1/22 20130101; H02K
7/003 20130101; H02K 7/14 20130101; H02K 5/161 20130101; H02K
11/0094 20130101; G02B 26/121 20130101; H02K 11/21 20160101; H02K
5/163 20130101; H02K 11/215 20160101 |
International
Class: |
H02K 7/00 20060101
H02K007/00; H02K 5/16 20060101 H02K005/16; H02K 1/22 20060101
H02K001/22; H02K 11/00 20060101 H02K011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2014 |
JP |
2014-255286 |
Claims
1. A rotary body driving apparatus, comprising: a rotary body
having a plurality of reflective surfaces; a motor having a rotor
shaft; a rotor being attached to one end part of the rotor shaft
together with the rotary body; a stator housing having a bearing
section, which rotatably holds the rotor shaft; a motor substrate
for detecting a rotational position of the rotor, the motor
substrate being provided to the stator housing; a magnetized
section for frequency generation, the magnetized section being
formed into a ring shape and provided to an outer edge of an end
surface of the rotary body facing the motor substrate; a circular
frequency generation pattern, which faces the magnetized section,
being provided to the motor substrate and disposed close to the
magnetized section; a position detecting section, which is
magnetized and which corresponds to a reference reflective surface
of the rotary body, being radially outwardly or inwardly projected
from a part of the magnetized section; and a magnetic sensor, which
faces the position detecting section, being provided to the motor
substrate.
2. The rotary body driving apparatus according to claim 1, wherein
the rotary body is formed into a multiple truncated pyramid shape,
the reflective surfaces are formed in outer surfaces of the rotary
body, and the magnetized section is integrally attached along an
outer edge of an axially maximum width part of the rotary body.
3. The rotary body driving apparatus according to claim 1, wherein
the magnetized section is integrally attached to the rotary body
with a back yoke composed of a magnetic material.
4. The rotary body driving apparatus according to claim 1, wherein
the rotary body is a tilt mirror having a plurality of tilted
reflective surfaces, or a polygon mirror having a plurality of
reflective surfaces, and the tilt mirror or the polygon mirror is
integrally attached to a rotor yoke and retained in an axial
direction.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority of the prior Japanese Patent Application No. 2014-255286,
filed on Dec. 17, 2014, and the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The present invention relates to a rotary body driving
apparatus, in which a rotary body, e.g., tilt mirror, polygon
mirror, is attached to a rotor shaft together with the rotor.
BACKGROUND
[0003] In a rotor of an outer rotor-type driving apparatus, a
cup-shaped rotor yoke is integrally attached to one end part of a
rotor shaft, and the rotor shaft is rotatably held by a stator
housing. A circular rotor magnet is provided inside of a rotor
yoke, and the rotor magnet is set to face pole teeth of a stator
iron core assembled in the stator housing.
[0004] A position detecting magnet, which is separated from a rotor
magnet and which is used for detecting a rotational position of the
rotor, is provided to a part of an outer circumferential surface of
a rotor yoke. A rotational position of the position detecting
magnet is detected by a magnetic sensor, e.g., Hall IC, so that the
rotational position of the rotor can be detected (see Patent
Document 1).
PRIOR ART DOCUMENT
[0005] Patent Document 1: Japanese Laid-open Utility Model
Publication No. 61-88480
SUMMARY
[0006] However, in case of using the position detecting magnet
separated from the rotor magnet as described in Patent Document 1,
number of parts and number of production steps must be increased,
so a production cost of the rotary body driving apparatus must be
increased.
[0007] In case of providing the position detecting magnet separated
from the driving magnet, e.g., rotor magnet, or providing a
projected magnet section for detecting a rotational position of the
rotor, a torque ripple of the position detecting magnet or the
projected magnet section must be increased, and rotational
stability of the rotor will be badly influenced.
[0008] Further, in case of employing, for example, a rotary body
having a plurality of reflective surfaces as a load integrally
attached to the rotor, a reference reflective surface must be
detected.
[0009] The present invention has been invented to solve the above
described problems of the conventional technology.
[0010] Accordingly, an object of the present invention is to
provide a rotary body driving apparatus, in which a position
detecting section is provided to a part of a rotary body acting as
a load such that the position detecting section corresponds to a
reference reflective surface of the rotary body so as to improve
rotational stability and rotational controllability of the
apparatus.
[0011] To achieve the object, the present invention has following
structures.
[0012] Namely, the rotary body driving apparatus of the present
invention basically comprises:
[0013] a rotary body having a plurality of reflective surfaces;
[0014] a motor having a rotor shaft;
[0015] a rotor being attached to one end part of the rotor shaft
together with the rotary body;
[0016] a stator housing having a bearing section, which rotatably
holds the rotor shaft;
[0017] a motor substrate for detecting a rotational position of the
rotor, the motor substrate being provided to the stator
housing;
[0018] a magnetized section for frequency generation, the
magnetized section being formed into a ring shape and provided to
an outer edge of an end surface of the rotary body facing the motor
substrate;
[0019] a circular frequency generation pattern, which faces the
magnetized section, being provided to the motor substrate and
disposed close to the magnetized section;
[0020] a position detecting section, which is magnetized and which
corresponds to a reference reflective surface of the rotary body,
being radially outwardly or inwardly projected from a part of the
magnetized section; and
[0021] a magnetic sensor, which faces the position detecting
section, being provided to the motor substrate.
[0022] As described above, the position detecting section, which is
magnetized and which corresponds to the reference reflective
surface of the rotary body acting as a load, is radially outwardly
or inwardly projected from the part of the magnetized section,
which is formed into the ring shape and provided to the outer edge
of the end surface of the rotary body facing the motor substrate.
With this structure, rotational stability and rotational
controllability of the rotary body driving apparatus can be
improved by making the position detecting section, which is
provided to the part of the magnetized section, correspond to the
reference reflective surface. Further, the magnetized section is
directly provided to the outer edge of the end surface of the
rotary body facing the motor substrate, and the frequency
generation pattern is provided to the motor substrate and disposed
close to the magnetized section, so that the rotational position of
the rotor can be highly precisely detected.
[0023] In the rotary body driving apparatus, the rotary body may be
formed into a multiple truncated pyramid shape,
[0024] the reflective surfaces may be formed in outer surfaces of
the rotary body, and
[0025] the magnetized section may be integrally attached to an
outer edge of an axially maximum width part of the rotary body.
[0026] With this structure, in comparison with a case of providing
the magnetized section to a rotor yoke, an outer diameter of the
magnetized section (FG magnet) can be increased as much as
possible, number of magnetic poles of the magnetized section can be
increased, an outer diameter of the frequency generation pattern
can be increased, and numbers of generation wire elements and
connection wire elements can be increased, so that the rotational
position of the rotary body can be highly precisely detected.
[0027] Preferably, the magnetized section is integrally attached to
the rotary body with a back yoke composed of a magnetic
material.
[0028] With this structure, a magnetic flux path caused by the
magnetized section (FG magnet) can be expanded, so that number of
magnetic fluxes interlinking the frequency generation pattern (FG
pattern) can be increased and detection sensitivity can be
improved.
[0029] In the rotary body driving apparatus, the rotary body may be
a tilt mirror having a plurality of tilted reflective surfaces or a
polygon mirror having a plurality of reflective surfaces, and
[0030] the tilt mirror or the polygon mirror may be integrally
attached to a rotor yoke and retained in an axial direction.
[0031] In this case, controllability of the mirror can be improved
by highly precisely detecting the rotational position of the tilt
mirror or the polygon mirror with respect to rotational reference
surfaces thereof.
[0032] In the rotary body driving apparatus of the present
invention, the rotary body and the rotor, which act as a load, are
assembled in a state where the rotational reference positions are
correctly aligned, so that rotational stability and rotational
controllability of the rotary body driving apparatus can be
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Embodiments of the present invention will now be described
by way of examples and with reference to the accompanying drawings
which are given by way of illustration only, and thus are not
limitative of the present invention, and in which:
[0034] FIG. 1 is an axially sectional view of an optical
scanner;
[0035] FIG. 2 is a perspective view of the optical scanner shown in
FIG. 1, in which a tilt mirror is detached;
[0036] FIG. 3 is a plan view of an FG magnet shown in FIG. 1;
and
[0037] FIG. 4 is a plan view of a motor substrate shown in FIG. 1,
on which a motor is mounted.
DESCRIPTION OF THE EMBODIMENTS
[0038] Preferred embodiments of an optical scanner, which is an
example of a rotary body driving apparatus relating to the present
invention, will now be described in detail with reference to the
accompanying drawings. Firstly, the optical scanner, which reflects
and irradiates a laser beam emitted from a laser irradiation unit
in a wide range so as to measure a distance, e.g., an inter-vehicle
distance, a distance to an obstacle, will be explained.
[0039] As shown in FIG. 1, in the optical scanner 1, a tilt mirror
(rotary body) 3 having, for example, four reflective surfaces 3a,
which are outer side surfaces and whose inclination angles are
different from each other, is attached to one end part of a rotor
shaft 4 of a motor 2 (see FIG. 2) together with a rotor yoke 5. The
tilt mirror 3 and the rotor yoke 5 are prohibited from detaching
from and rotating with respect to the rotor shaft 4.
[0040] Firstly, a structure of the motor 2 will be explained. As
shown in FIG. 4, a bearing housing 7 (stator housing 7) is
integrally attached to a base plate 6. A motor substrate 8, on
which a Hall IC for detecting magnetic poles of a rotor magnet 9,
etc. are mounted, is attached on the base plate 6.
[0041] A first bearing section 10a and a second bearing section 10b
are attached in the bearing housing 7 which is formed into a
cylindrical shape. For example, the first bearing section 10a and
the second bearing section 10b are rolling bearings. A step-shaped
part 7a is formed in an outer surface of the bearing housing 7. A
stator 11 is attached to the step-shaped part 7a. In the stator 11,
a stator core 11a is covered with insulators and motor coils 11c
are respectively wound on magnetic pole teeth lib. The stator core
11a is fixed to the bearing housing 7 by press fit and
adhesive.
[0042] The rotor shaft 4 of a rotor 12 is rotatably held by the
first bearing section 10a and the second bearing section 10b which
are provided in the bearing housing 7. The cylindrical rotor yoke 5
and a rotor hub 13 are integrated with each other by caulking. A
cylindrical sleeve 13a is axially extended from a center part of
the rotor hub 13 toward the rotor yoke 5. The rotor shaft 4 is
integrally fitted into the hole of the sleeve 5c by press fit,
shrink fit, adhesive, etc. A projection 13b (see FIG. 2) is
provided on an axially opposite side of the sleeve 13a of the rotor
hub 13. A plurality of the projections 13b may be formed. The rotor
magnet 9 is integrally attached on an inner circumferential surface
of the rotor yoke 5. In the rotor magnet 9, magnetic N-poles and
magnetic S-poles are alternately formed and faced to the pole teeth
11b of the stator 11.
[0043] The tilt mirror 3 is integrated with the rotor 11. As shown
in FIG. 1, the tilt mirror 3 is formed into a multiple truncated
pyramid shape and has a plurality of the reflective surfaces (e.g.,
four reflective surfaces) 3a, which are outer side surfaces and
whose inclination angles are different from each other. A shaft
hole (through-hole) 3b, through which the rotor shaft 4 is
penetrated, is formed at a center part of the tilt mirror 3. In an
upper surface of the tilt mirror 3, a recessed part 3c is formed
around the shaft hole 3b. One end of the rotor shaft 4 is inserted
into the recessed part 3c, and a press spring 14 and a retaining
washer 15 are fitted therein so as to attach the tilt mirror 3 to
the rotor shaft 4 without being detached. With this structure, an
axial assembling space of the tilt mirror 3 can be made small.
[0044] The reflective surfaces 3a of the tilt mirror 3 are mirror
surfaces, which are formed by vapor-depositing metal on a material
of the tilt mirror 3, e.g., metallic material, resin material, or
by polishing the material. Further, in the tilt mirror 3, an
accommodating part 3d, which is a recessed part and capable of
accommodating the rotor yoke 5, is formed in a bottom surface
facing the motor 2.
[0045] As shown in FIG. 1, a circular magnetized section (FG
magnet) 16 is integrally attached to a lower surface of the tilt
mirror 3 having the reflective surfaces 3a, i.e., along an outer
edge of an axially maximum width part of the tilt mirror 3, with a
back yoke 17 composed of a magnetic material. Note that, the back
yoke 17 may be omitted. The FG magnet 16 is directly integrated
with the outer edge of the lower end surface of the tilt mirror 3,
which faces the motor substrate 8. As shown in FIG. 3, in the
circular FG magnet 16, magnetic N-poles and magnetic S-poles are
alternately formed. Number of the magnetic poles of the FG magnet
16, e.g., 120, is much greater than that of the rotor magnet 9.
[0046] As shown in FIG. 4, a frequency generation pattern (FG
pattern) 18 is formed on a surface of the motor substrate 8, which
faces the FG magnet 16. The FG pattern 18 is constituted by: a
pattern of generation wire elements 18a, which are radially formed
and arranged in a circumferential direction; and a pattern of
connection wire elements 18b, which are formed in the
circumferential direction to connect the adjacent generation wire
elements 18a to each other. The both patterns of the generation
wire elements 18a and the connection wire elements 18b are formed
like rectangular waves and alternately continued in the
circumferential direction. FG signals are outputted from a pair of
lead wires 18c and 18d. When the FG magnet 16 shown in FIG. 3 is
rotated above the FG pattern 18 of the motor substrate 8, an
induced electromotive force is induced in each of the generation
wire elements 18a of the FG pattern 18, so that the FG signals can
be detected from the pair of lead wires 18c and 18d.
[0047] As shown in FIG. 3, a position detecting projection
(position detecting section) 16a is radially outwardly projected
from a part of the circular FG magnet 16. A circumferential
position of the position detecting projection 16a and that of a
reference reflective surface (rotational reference surface) are
corresponded to each other. A magnetic pole of the position
detecting projection 16a may be N-pole or S-pole.
[0048] As shown in FIG. 2, the position detecting projection 16a
corresponds to a circumferential position of a projection 13b of
the rotor hub 13. The position detecting projection 16a is radially
outwardly projected as shown in FIG. 3. But, the position detecting
section of the present invention is not limited to the position
detecting projection 16a, so a position detecting projection 16b
which is radially inwardly projected from the FG magnet 16 may be
formed as the position detecting section. The Hall IC (magnetic
sensor) 21 detects a detection signal every time the tilt mirror 3
rotates once from the reference reflective surface. The detected
signals are used for controlling a rotational speed or a number of
rotation of the tilt mirror 3.
[0049] An example of a manner of assembling the optical scanner 1
will be explained. In FIG. 1, the motor 2 is assembled by steps of:
attaching the base plate 6 and the motor substrate 8 to the bearing
housing 7; attaching the stator 11; and inserting the rotor shaft 4
of the rotor 12 into the through-hole of the bearing housing 7 so
as to rotatably hold the rotor shaft 4 by the first and second
bearing sections 10a and 10b.
[0050] By fitting the projection 13b of the rotor 12 in a recessed
part (not shown) of the tilt mirror 3, circumferential positions of
the reference reflective surface of the tilt mirror 3 and the
circumferential position of the projection 13b of the rotor hub 13
can be aligned, the reference reflective surface of the tilt mirror
3 can be aligned with the position detecting projection 16a of the
FG magnet 16, and these members are assembled in this state.
[0051] Further, the one end of the rotor shaft 4 is penetrated
through the shaft hole 3b of the recessed part 3c formed in the
upper surface of the tilt mirror 3, and the press spring 14 and the
retaining washer 15 are fitted in the recessed part 3c, so that the
tilt mirror 3 can be attached to the rotor shaft 4 and retained
thereon. The other end of the rotor shaft 4 is retained, by a
retaining washer 20, without being detached from the bearing
housing 7 (the second bearing section 10b).
[0052] As described above, the position detecting projection 16a or
16b, which corresponds to the reference reflective surface of the
tilt mirror 3, is radially outwardly or inwardly projected from the
part of the FG magnet 16, which is provided along the outer edge of
the end surface of the tilt mirror 3, which acts as the load,
facing the motor substrate 8. By making the position detecting
projection 16a or 16b correspond to the reference reflective
surface of the tilt mirror 3, rotational stability and rotational
controllability of the rotary body driving apparatus can be
improved.
[0053] By disposing the FG pattern 18 shown in FIG. 4, which faces
the FG magnet 16 shown in FIG. 3, close to the FG magnet 16, the
rotational position of the tilt mirror 3 can be highly precisely
detected, so that controllability of the tilt mirror 3 can be
improved.
[0054] In comparison with a case of providing an FG magnet to a
rotor yoke, an outer diameter of the FG magnet 16 can be increased,
number of the magnetic poles of the FG magnet 16 can be increased,
an outer diameter of the FG pattern 18 can be increased, and
numbers of the generation wire elements 18a and the connection wire
elements 18b can be increased, so that the rotational position of
the tilt mirror 3 can be highly precisely detected.
[0055] In the above described embodiment, the rotary body is the
tilt mirror 3 having the tilted reflective surfaces 3a. But, the
present invention is not limited to the above described embodiment.
For example, the rotary body may be a polygon mirror having a
plurality of reflective surfaces.
[0056] Further, the motor of the above described embodiment is the
outer rotor-type motor. The present invention may be applied to the
rotary body driving apparatus having an inner rotor-type motor.
[0057] All examples and conditional language recited herein are
intended for pedagogical purposes to aid the reader in
understanding the invention and the concepts contributed by the
inventor to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions, nor does the organization of such examples in the
specification relate to a showing of the superiority and
inferiority of the invention. Although the embodiments of the
present invention have been described in detail, it should be
understood that the various changes, substitutions, and
alternations could be made hereto without departing from the spirit
and scope of the invention.
* * * * *