U.S. patent application number 17/021151 was filed with the patent office on 2021-04-01 for rotational resistance apparatus and operation apparatus.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Junya Hirano.
Application Number | 20210096591 17/021151 |
Document ID | / |
Family ID | 1000005117181 |
Filed Date | 2021-04-01 |
United States Patent
Application |
20210096591 |
Kind Code |
A1 |
Hirano; Junya |
April 1, 2021 |
ROTATIONAL RESISTANCE APPARATUS AND OPERATION APPARATUS
Abstract
A rotational resistance apparatus includes a shaft member that
includes a first shaft and a second shaft having a diameter larger
than a diameter of the first shaft and that has magnetism, a bobbin
that is arranged on an outer periphery of the first shaft and that
does not have magnetism, a coil that is wound around the bobbin, a
case member having magnetism that covers the bobbin, the coil, and
the second shaft, a slide bearing that rotatably receives the first
shaft through a first gap and that does not have magnetism, and a
magnetic viscous fluid that is arranged between the second shaft
and the case member. The first gap is smaller than a second gap
between the case member and the first shaft.
Inventors: |
Hirano; Junya;
(Utsunomiya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
1000005117181 |
Appl. No.: |
17/021151 |
Filed: |
September 15, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16D 57/002 20130101;
G05G 2505/00 20130101; G02B 7/16 20130101; G02B 7/04 20130101; G05G
1/10 20130101; G05G 5/03 20130101 |
International
Class: |
G05G 5/03 20060101
G05G005/03; F16D 57/00 20060101 F16D057/00; G05G 1/10 20060101
G05G001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2019 |
JP |
2019-176362 |
Claims
1. A rotational resistance apparatus comprising: a shaft member
that includes a first shaft and a second shaft having a diameter
larger than a diameter of the first shaft and that has magnetism; a
bobbin that is arranged on an outer periphery of the first shaft
and that does not have magnetism; a coil that is wound around the
bobbin; a case member having magnetism that covers the bobbin, the
coil, and the second shaft; a slide bearing that rotatably receives
the first shaft through a first gap and that does not have
magnetism; and a magnetic viscous fluid that is arranged between
the second shaft and the case member, wherein the first gap is
smaller than a second gap between the case member and the first
shaft.
2. The rotational resistance apparatus according to claim 1,
wherein the first gap is smaller than a third gap between the
second shaft and the case member in a space where the magnetic
viscous fluid is arranged.
3. The rotational resistance apparatus according to claim 1,
wherein the case member has a through hole through which the first
shaft passes, and wherein the second gap is provided between an
inner circumferential surface of the through hole and an outer
circumferential surface of the first shaft.
4. The rotational resistance apparatus according to claim 1,
wherein a convex part is provided on one of an end surface of the
first shaft in a shaft direction of the first shaft and the case
member so as to abut on the other of the end surface and the case
member, and wherein the second gap is provided between the end
surface and the case member and around the convex part.
5. The rotational resistance apparatus according to claim 1,
wherein the slide bearing is formed integrally with the bobbin.
6. The rotational resistance apparatus according to claim 1,
wherein the first shafts and the coils are provided on both sides
of the second shaft in a shaft direction of the shaft member.
7. The rotational resistance apparatus according to claim 6,
wherein, by energizing the coils provided on the both sides so that
magnetic fluxes in opposite directions to each other are generated
in the first shafts provided on the both sides, a first magnetic
circuit is formed through one first shaft, the second shaft, and
the case member, and a second magnetic circuit is formed through
the other first shaft, the second shaft, and the case member.
8. The rotational resistance apparatus according to claim 1,
further comprising: a first sealing member that seals a gap between
an outer circumferential surface of the bobbin and an inner
circumferential surface of the case member; and a second sealing
member that seals a gap between an inner circumferential surface of
the bobbin and an outer circumferential surface of the first
shaft.
9. An operation apparatus comprising: an operation member that is
rotatable; and a rotational resistance apparatus that applies
resistance force to the operation member, wherein the rotational
resistance apparatus includes: a shaft member that includes a first
shaft and a second shaft having a diameter larger than a diameter
of the first shaft and that has magnetism; a bobbin that is
arranged on an outer periphery of the first shaft and that does not
have magnetism; a coil that is wound around the bobbin; a case
member having magnetism that covers the bobbin, the coil, and the
second shaft; a slide bearing that rotatably receives the first
shaft through a first gap and that does not have magnetism; and a
magnetic viscous fluid that is arranged between the second shaft
and the case member, wherein the first gap is smaller than a second
gap between the case member and the first shaft.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a rotational resistance
apparatus and an operation apparatus.
Description of the Related Art
[0002] A rotational resistance apparatus that generates resistance
to a rotation operation using a magnetic viscous fluid can present,
for example, resistance to rotation of an operation member capable
of a rotation operation to an operator as an operational feeling
(touch sensation). Japanese Patent Laid-Japanese Open No. ("JP")
2017-89732 and Japanese Patent Laid-Open No. ("JP") 2017-110756
disclose a rotational resistance apparatus adjusting a magnetic
field that is applied to a rotatable rotor and a magnetic viscous
fluid arranged around a shaft member to adjust resistance
(resistance torque) for shearing the magnetic viscous fluid.
[0003] However, the rotational resistance apparatus disclosed in JP
2017-89732 and JP 2017-110756 maintains a gap where the magnetic
viscous fluid is arranged by supporting the rotor and the shaft
member using a ball bearing, and thus increases in a radial
direction. Additionally, since components for use the rotor as part
of a magnetic circuit, the coil, and the magnetic viscous fluid are
accumulated in the radial direction, the rotational resistance
apparatus of JP 2017-89732 is not suitable for reducing a diameter.
Further, since the magnetic viscous fluid is arranged on an inner
diameter side of the apparatus, the rotational resistance apparatus
of JP 2017-110756 cannot generate the resistance torque
efficiently.
SUMMARY OF THE INVENTION
[0004] The present invention provides a rotational resistance
apparatus advantageous in, for example, generation efficiency of
rotation resistance and small size.
[0005] A rotational resistance apparatus according to one aspect of
the present invention includes a shaft member that includes a first
shaft and a second shaft having a diameter larger than a diameter
of the first shaft and that has magnetism, a bobbin that is
arranged on an outer periphery of the first shaft and that does not
have magnetism, a coil that is wound around the bobbin, a case
member having magnetism that covers the bobbin, the coil, and the
second shaft, a slide bearing that rotatably receives the first
shaft through a first gap and that does not have magnetism, and a
magnetic viscous fluid that is arranged between the second shaft
and the case member. The first gap is smaller than a second gap
between the case member and the first shaft.
[0006] An operation apparatus as another aspect of the present
invention includes an operation member that is rotatable, and a
rotational resistance apparatus that applies resistance force to
the operation member. The rotational resistance apparatus includes
a shaft member that includes a first shaft and a second shaft
having a diameter larger than a diameter of the first shaft and
that has magnetism, a bobbin that is arranged on an outer periphery
of the first shaft and that does not have magnetism, a coil that is
wound around the bobbin, a case member having magnetism that covers
the bobbin, the coil, and the second shaft, a slide bearing that
rotatably receives the first shaft through a first gap and that
does not have magnetism, and a magnetic viscous fluid that is
arranged between the second shaft and the case member. The first
gap is smaller than a second gap between the case member and the
first shaft.
[0007] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a sectional view illustrating a configuration of a
rotational resistance apparatus according to Example 1 of the
present invention.
[0009] FIG. 2 is an exploded perspective view of the rotational
resistance apparatus according to Example 1.
[0010] FIGS. 3A to 3D are diagrams illustrating a principle of
generation of resistance force of MR fluid in Example 1.
[0011] FIG. 4 is a sectional view illustrating a magnetic circuit
in the rotational resistance apparatus according to Example 1.
[0012] FIG. 5 is a sectional view illustrating a configuration of a
rotational resistance apparatus according to Example 2 of the
present invention.
[0013] FIG. 6 is a sectional view illustrating a magnetic circuit
in the rotational resistance apparatus according to Example 2.
[0014] FIG. 7 is a sectional view illustrating a configuration of a
rotational resistance apparatus according to Example 3 of the
present invention.
[0015] FIG. 8 is a sectional view illustrating a magnetic circuit
in the rotational resistance apparatus according to Example 3.
[0016] FIG. 9 is a perspective view illustrating an interchangeable
lens according to Example 4 of the present invention.
DESCRIPTION OF THE EMBODIMENTS
[0017] Referring now to the accompanying drawings, a detailed
description will be given of examples according to the present
invention.
Example 1
[0018] FIGS. 1, 2, and 4 illustrate a configuration of a rotational
resistance apparatus 100 according to Example 1 of the present
invention. The rotational resistance apparatus 100 includes a shaft
member 101 that is rotatable, a cylindrical member 102 that is
arranged to surround an outer periphery of the shaft member 101,
and first and second circular plates 103, 104 that are provided to
close openings at both ends of the cylindrical member 102. The
cylindrical member 102 and the first and second circular plate 103,
104 form a case member.
[0019] The cylindrical member 102 is formed as a magnetic material,
and has cutout parts 102a, 102b and through hole parts 102c, 102d.
The first and second circular plate 103, 104 are formed as a
magnetic material and have through hole parts 103a, 104a,
respectively.
[0020] The shaft member 101 is formed as a magnetic material, and
has first shafts 101a, 101b that are provided at both ends of the
shaft member 101 in a shaft direction and a second shaft 101c that
is provided between the first shafts 101a, 101b and that has a
diameter larger than a diameter of the first shafts 101a, 101b. In
the following description, the shaft direction of the shaft member
101 is used as a shaft direction of the rotational resistance
apparatus 100, and a direction perpendicular to the shaft direction
is referred to as a radial direction.
[0021] The first shaft 101a has a transmission shaft part 101d, in
which a diameter is reduced by forming a step 101f, on a tip side
(a side opposite to the second shaft 101c) in the shaft direction.
On the other hand, the first shaft 101b has a detection shaft part
101e, in which a diameter is reduced by forming a step 101g, on a
tip side in the shaft direction.
[0022] On an outer periphery of the first shafts 101a, 101b
provided inside the cylindrical member 102, coils 105, 106 that are
respectively wound around bobbins 107, 108 are arranged. The
cylindrical member 102 is arranged to cover an outer periphery of
the coils 105, 106 and an outer periphery of the second shaft 101c.
The first and second circular plates 103, 104 are arranged to cover
ends of outside (a side far from the second shaft 101c) of the
bobbins 107, 108 in the shaft direction.
[0023] The transmission shaft part 101d and the detection shaft
part 101e of the shaft member 101 project to an outside of the case
member through the through hole parts 103a, 104a of the first and
second circular plates 103, 104, respectively. As illustrated in
FIG. 4, a gap (second gap) Ga1 is provided between an inner
circumferential surface of the through hole part 103a and an outer
circumferential surface of the transmission shaft part 101d. A gap
(second gap) Ga2 is also provided between an inner circumferential
surface of the through hole part 104a and an outer circumferential
surface of the detection shaft part 101e.
[0024] A gear 115 is fixed to the tip of the first shaft 101a to
rotate integrally with the shaft member 101, and a detected member
116 for rotation (angle) detection is fixed to the tip of the first
shaft 101b to rotate integrally with the shaft member 101. A
detector 117 is arranged to face a side surface of the detected
member 116.
[0025] The gear 115 can transmit rotation resistance torque
generated by the rotational resistance apparatus 100 on the basis
of a principle described later to a rotation operation member (not
illustrated). The detector 117 optically or magnetically detects a
pattern (not illustrated) provided on the detected member 116 and
outputs a signal. The rotation angle of the rotation operation
member can be detected using the signal.
[0026] Both bobbins 107, 108 are formed as non-magnetic materials.
Each of the bobbins 107, 108 has, on both sides in the shaft
direction, annular end surface parts 107a, 108a that abut on an
inner circumferential surface of the cylindrical member 102.
Additionally, the bobbins 107, 108 are respectively provided with
wiring parts 107b, 108b for connecting the windings of the coils
105, 106 to an external magnetic field control apparatus (not
illustrated).
[0027] Further, slide bearings 107c, 108c that rotatably receives
the first shaft 101a (transmission shaft part 101d) and the first
shaft 101b (detection shaft part 101e) are formed on an inner
periphery of the end surface parts 107a, 108a provided outside of
the bobbins 107, 108 in the shaft direction, respectively. As
illustrated in FIG. 4, between inner circumferential surfaces of
the slide bearings 107c, 108c and outer circumferential surfaces of
the first shafts 101a, 101b, gaps (first gap) Gb1, Gb2 are formed.
Side parts (internal surfaces of the end surface parts 107a, 108a
of the bobbins 107, 108) of the slide bearings 107c, 108c
respectively abut on the steps 101f, 101g of the shaft member 101
to limit displacement in the shaft direction of the shaft member
101.
[0028] A magnetic viscous fluid (hereinafter referred to as MR
fluid) F is arranged in a gap area that is surrounded by an outer
circumferential surface and both side surfaces of the second shaft
101c, the inner circumferential surface of the cylindrical member
102, and the end surface parts 107a, 107b inside (a side near the
second shaft 101c) of the bobbins 107a, 108a. As illustrated in
FIG. 4, the gap area includes a gap (third gap) Gm provided between
the outer circumferential surface of the second shaft 101c and the
inner circumferential surface of the cylindrical member 102. The MR
fluid F is filled in the gap area from one of the through hole
parts 102c, 102d of the cylindrical member 102, and then the
through hole parts 102c, 102d are sealed by sealing members 113,
114.
[0029] In annular concave parts provided on outer circumferential
surfaces of the end surface parts 107a, 108a inside of the bobbins
107, 108 in the shaft direction, first seal rings 109, 110 to seal
a gap between the outer circumferential surfaces of the end surface
parts 107a, 108a and the inner circumferential surface of the
cylindrical member 102 are fitted and retained. Further, in annular
concave parts provided on inner circumferential surfaces of the end
surface parts 107a, 108a inside of the bobbins 107, 108 in the
shaft direction, second seal rings 111, 112 to seal a gap between
the inner circumferential surfaces of the end surface parts 107a,
108a and the inner circumferential surfaces of the first shafts
101a, 101b are fitted and retained.
[0030] The rotational resistance apparatus 100 is assembled as
follows. As illustrated in FIG. 2, the shaft member 101 and a coil
unit A (the bobbin 107, the coil 105, and the first and second seal
rings 109, 111) are inserted in this order from one side in the
shaft direction inside the cylindrical member 102, and a coil unit
B (the bobbin 108, the coil 106, and the first and second seal
rings 110, 112) is inserted from the other side in the shaft
direction inside the cylindrical member 102. Then, the first
circular plate 103 is fitted in one opening end in the shaft
direction of the cylindrical member 102, and the second circular
plate 104 is fitted in the other opening end in the shaft
direction. Then, as described above, the MR fluid F is filled from
one of the through hole parts 102c, 102d of the cylindrical member
102, and the through hole parts 102c, 102d are sealed by the
sealing members 113, 114.
[0031] In the rotational resistance apparatus 100 configured as
above, a size in the radial direction of the gap Gb1 between the
inner circumferential surface of the slide bearing 107c and the
outer circumferential surface of the transmission shaft part 101d
is smaller (that is, narrower) than that of the gap Ga1 between the
inner circumferential surface of the through hole part 103a and the
outer circumferential surface of the transmission shaft part 101d.
Additionally, the gap Gb2 between the inner circumferential surface
of the slide bearing 108c and the outer circumferential surface of
the detection shaft part 101e is narrower than the gap Ga2 between
the inner circumferential surface of the through hole part 104a and
the outer circumferential surface of the detection shaft part 101e.
Further, the gaps Gb1, Gb2 is narrower than the gap (third gap) GM
between the outer circumferential surface of the second shaft 101c
and the outer circumferential surface of the cylindrical member 102
in a space where the MR fluid F is arranged.
[0032] Referring now to FIGS. 3A to 3D, a description will be given
of a principle that the MR fluid F generates resistance force
against shear. The MR fluid F has a reversible property in which
the resistance force against shear increases when a magnetic field
M is applied and returns to the original resistance force when the
magnetic field is removed. As illustrated in FIG. 3A, in a state
where the magnetic field M is not applied, the MR fluid F is a
liquid where numberless magnetic material particles Fa are
dispersed in a solvent Fb. As illustrated in FIG. 3B, when the
magnetic field M is applied in this state, numberless clusters C,
which is aggregate of the magnetic material particles Fa, is formed
along a direction of the magnetic field. The cluster C is formed by
attracting numberless magnetic material particles Fa magnetized by
the magnetic field M to the nearby magnetic material particles
Fa.
[0033] As illustrated in FIG. 3C, when a movable part 99 (second
shaft 101c), which is movable relative to a fixing part 98
(cylindrical member 102), receives external force I in a direction
perpendicular to the magnetic field M, each cluster C gradually
extends while tilting, and is eventually cut. Until the cluster C
is cut, attraction force to attract the magnetic material particles
Fa forming the cluster C to each other becomes resistance force. As
illustrated in FIG. 3D, each cluster C, which is cut, combines with
another cluster C. By repeatedly cutting and combining each cluster
C in this way, the resistance force against shear of the fixed part
98 and the movable part 99 is maintained. By increasing the
strength of the magnetic field M, the attraction force between the
magnetic material particles Fa inside each cluster C becomes
stronger, and the generated resistance force also becomes
larger.
[0034] FIG. 4 illustrates a magnetic circuit in the rotational
resistance apparatus 100 according to this example. The magnetic
fluxes have a property of repelling each other and a property of
forming a closed loop magnetic circuit having neither a starting
point nor an ending point. In the rotational resistance apparatus
100 according to this example, currents flow from the magnetic
field control apparatus to the coils 105, 106 so that magnetic
fluxes in opposite directions flow in the first shafts 101a, 101b.
FIG. 4 illustrates a first magnetic circuit M1 in which a magnetic
flux generated by energizing the coil 105 flows and a second
magnetic circuit M2 in which a magnetic flux generated by
energizing the coil 106 flows using a closed loop curve.
[0035] The magnetic fluxes that flow from each of the first shafts
101a, 101b of the shaft member 101 to the second shaft 101c repels
in the second shaft 101c and flow toward the outer circumferential
surface of the second shaft 101c. The magnetic fluxes flowing
through from the outer circumferential surface of the second shaft
101c pass through the MR fluid F and flow in the cylindrical member
102. The magnetic fluxes generated by energizing the coil 105 of
the magnetic fluxes which flow in the cylindrical member 102 flow
in part facing the coil 105 of the cylindrical member 102 and flow
toward the first circular plate 103. Then, the magnetic fluxes
flowing out the first circular plate 103 returns to the first shaft
101a through the transmission shaft part 101d, which faces the
through hole part 103a in a non-contact manner. On the other hand,
the magnetic fluxes generated by energizing the coil 106 of the
magnetic fluxes which flow in the cylindrical member 102 flow in
part facing the coil 106 of the cylindrical member 102 and flow
toward the second circular plate 104. Then, the magnetic fluxes
flowing through the second circular plate 104 returns to the first
shaft 101b through the detection shaft part 101e, which faces the
through hole part 104a in a non-contact manner.
[0036] In this example, since almost all of the magnetic fluxes
generated by energizing the coils 105, 106 flow in the MR fluid F
through the first and second magnetic circuits M1, M2 to form
numberless clusters C in the MR fluid F, the resistance force
(rotation resistance torque) against the rotation of the shaft
member 101 can be efficiently generated. Then, changing the amount
of current flowing in the coils 105, 106 can control the strength
of the magnetic fluxes flowing in the MR fluid F to adjust the
magnitude of the rotation resistance torque.
[0037] Further, as described above, since the gaps Gb1, Gb2 are
narrower than the gaps Ga1, Ga2, Gm, the shaft member 101 is
rotatably supported in a non-contact state with the case member
(the cylindrical member 102, the first and second circular plates
103, 104). As a result, the gaps Ga1, Ga2, Gm are always kept
constant, and stable rotation resistance torque can be generated by
contacting the shaft member 101 with the case member without making
the magnetic resistance of the first and second magnetic circuits
M1, M2 unstable and changing the magnetic fluxes flowing in the MR
fluid F.
[0038] In this example, since the slide bearings 107c, 108c are
formed integrally with the bobbins 107, 108, the number of parts of
the rotational resistance apparatus 100 is smaller than that in the
case where these are separate parts, so that the configuration and
the assembly can be simplified. Further, since the number of parts
is reduced, the tolerances are less accumulated, and the gap (Ga1,
Ga2, Gm) in each magnetic circuit can be reduced. As a result, the
magnetic resistance of each magnetic circuit can be reduced, and
larger rotation resistance torque can be obtained.
[0039] Further, since the slide bearings 107c, 108c function as a
thrust bearing that sandwiches the steps 101f, 101g of the shaft
member 101, it is possible to further simplify the configuration
and the assembly.
Example 2
[0040] FIG. 5 illustrates a configuration of a rotational
resistance apparatus 200 according to Example 2 of the present
invention. In this example, components common to or similar to
those in Example 1 are given reference numerals with the first
digit 1 of the reference numeral in Example 1 changed to 2, and the
digits thereafter are the same. Further, coil units C, D
respectively correspond to the coil units A, B in Example 1. Below,
differences from the rotational resistance apparatus 100 according
to Example 1 are explained.
[0041] The rotational resistance apparatus 200 according to this
example includes a coil spring 215 that is arranged between a step
201f on an outer periphery of a first shaft 201a of a shaft member
201 and an internal surface of an end surface part 207a of a bobbin
207 and that biases the shaft member 201 on one side (a side of a
first shaft 201b) in a shaft direction as a biasing member. A
second circular plate 204 does not have a through hole part
corresponding to the through hole part 104a of the second circular
plate 104 according to Example 1, and a hemispherical convex part
201e at a tip of the first shaft 201b is pressed against the second
circular plate 204 by the biasing force E1 of the coil spring 215.
The second circular plate 204 is fixed to a cylindrical member 202
to withstand the biasing force E1. The first shaft 201b is not
provided with a detection shaft part corresponding to the detection
shaft part 101e according to Example 1.
[0042] Further, reaction force E2 against the biasing force E1 acts
on the bobbin 207 on which the coil spring 215 abuts. A first
circular plate 203 that abuts on the bobbin 207 is fixed to the
cylindrical member 202 to withstand the reaction force E2.
[0043] As illustrated in FIG. 6, a gap (first gap) Gb3 between an
inner circumferential surface of a slide bearing 207c provided on
the bobbin 207 and an outer circumferential surface of a
transmission shaft part 201d, which is rotatably received by the
slide bearing 207, of the shaft member 201 is narrow than a gap
(second gap) Ga3 between an inner circumferential surface of a
through hole part 203a of the first circular plate 203 and the
outer circumferential surface of the transmission shaft part 201d.
Additionally, a gap (first gap) Gb4 between an inner
circumferential surface of a slide bearing 208c that is provided on
the bobbin 208 and that rotatably receives the first shaft 201b and
an outer circumferential surface of the first shaft 201b is narrow
than a gap (second gap) Ga4 between an end surface of the first
shaft 201b and the second circular plate 204 formed by the convex
part 201e. Further, the gaps Gb3, Gb4 are narrow than a gap (third
gap) GM between an outer circumferential surface of a second shaft
201c and an inner circumferential surface of the cylindrical member
202 in a space where the MR fluid F is arranged.
[0044] FIG. 6 illustrates a magnetic circuit in the rotational
resistance apparatus 200 according to this example. In the
rotational resistance apparatus 200, currents flow from a magnetic
field control apparatus to coils 205, 206 so that magnetic fluxes
in opposite directions flow in the first shafts 201a, 201b. FIG. 6
illustrates a first magnetic circuit M3 in which a magnetic flux
generated by energizing the coil 205 flows and a second magnetic
circuit M4 in which a magnetic flux generated by energizing the
coil 206 flows using a closed loop curve.
[0045] The magnetic fluxes that flow from each of the first shafts
201a, 201b of the shaft member 201 to the second shaft 201c repels
in the second shaft 201c and flow toward an outer circumferential
surface of the second shaft 201c. The magnetic fluxes flowing out
from the outer circumferential surface of the second shaft 201c
pass through the MR fluid F and flow in the cylindrical member 202.
The magnetic fluxes generated by energizing the coil 205 of the
magnetic fluxes which flow in the cylindrical member 202 flow in
part facing the coil 205 of the cylindrical member 202 and flow
toward the first circular plate 203. Then, the magnetic fluxes
flowing through the first circular plate 203 returns to the first
shaft 201a through the transmission shaft part 201d, which faces
the through hole part 203 a in a non-contact manner. On the other
hand, the magnetic fluxes generated by energizing the coil 206 of
the magnetic fluxes which flow in the cylindrical member 202 flow
in part facing the coil 206 of the cylindrical member 202 and flow
toward the second circular plate 204. Then, the magnetic fluxes
flowing through the second circular plate 204 returns to the first
shaft 201b.
[0046] As described above, in this example, since almost all of the
magnetic fluxes generated by energizing the coils 205, 206 flow in
the MR fluid F through the first and second magnetic circuits M3,
M4, rotation resistance torque against the shaft member 201 can be
efficiently generated. Then, changing the amount of current flowing
in the coils 205, 206 can control the strength of the magnetic
fluxes flowing in the MR fluid F to adjust the magnitude of the
rotation resistance torque.
[0047] In this example, since the gaps Gb3, Gb4 are narrower than
the gaps Ga3, Gm, the first shaft 201a and the second shaft 201c of
the shaft member 201 are respectively rotatably supported in a
non-contact state with the circular plate 203 and the cylindrical
member 202, and the gaps Ga3, Gm are kept constant. On the other
hand, the first shaft 201b contacts the second circular plate 203
at the convex part 201e, but the gap Ga4 is kept constant by the
convex part 201e and the biasing force of the coil spring 215.
Keeping the gaps Ga3, Ga4, Gm constant can generate stable rotation
resistance torque without making the magnetic resistance of the
first and second magnetic circuits M3, M4 unstable and changing the
magnetic fluxes flowing in the MR fluid F.
[0048] In this example, since the slide bearings 207c, 208c are
formed integrally with the bobbins 207, 208, the configuration and
the assembly can be simplified. Further, the gap (Ga3, Ga4, Gm) in
each magnetic circuit can be reduced, and larger rotation
resistance torque can be obtained by reducing the magnetic
resistance of each magnetic circuit.
[0049] In addition, the shaft member 201 is biased by the coil
spring 215 in this example but may be biased by another biasing
member.
Example 3
[0050] FIG. 7 illustrates a configuration of a rotational
resistance apparatus 300 according to Example 3 of the present
invention. In this example, components common to or similar to
those in Example 1 are given reference numerals with the first
digit 1 of the reference numeral in Example 1 changed to 3, and the
digits thereafter are the same. Further, coil units G, H
respectively corresponds to the coil units A, B in Example 1.
Below, differences from the rotational resistance apparatus 100
according to Example 1 are explained.
[0051] The slide bearings 107c, 108c are integrally provided to the
bobbins 107, 108 in Example 1 but, in this example, slide bearings
315, 316, which are made of a non-magnetic material and are formed
as a separate part from bobbins 307, 308, are fixed to inner
circumferential surfaces of end surface parts 307a, 308a of the
bobbins 307, 308. As the slide bearings 315, 316, a resin bearing
made of a low friction material, and a metal bearing impregnated
with lubricating oil can be used.
[0052] In this example, as illustrated in FIG. 8, a gap (first gap)
Gb5 between an inner circumferential surface of a slide bearing 315
and an outer circumferential surface of a transmission shaft part
301d, which is rotatably received by the slide bearing 315, of a
shaft member 301 is narrow than a gap (second gap) Ga5 between an
inner circumferential surface of a through hole part 303a of a
first circular plate 303 and the outer circumferential surface of
the transmission shaft part 301d. Additionally, a gap (first gap)
Gb6 between an inner circumferential surface of a slide bearing 316
and an outer circumferential surface of a detection shaft part
301e, which is rotatably received by the slide bearing 316, of the
shaft member 301 is narrow than a gap (second gap) Ga6 between an
inner circumferential surface of a through hole part 304a of a
second circular plate 304 and the outer circumferential surface of
the detection shaft part 301e. Further, the gaps Gb5, Gb6 are
narrow than a gap (third gap) GM between an outer circumferential
surface of a second shaft 301c and an inner circumferential surface
of the cylindrical member 302 in a space where the MR fluid F is
arranged.
[0053] As illustrated in FIG. 8, first and second magnetic circuits
M5, M6 in the rotational resistance apparatus 300 according to this
example are respectively equivalent to the first and second
magnetic circuits M1, M2 in Example 1. Thus, in this example,
rotation resistance torque against the shaft member 301 can be
efficiently generated. Further, in this example, since the gaps
Gb5, Gb6 are narrower than the gaps Ga5, Ga6, Gm, the shaft member
301 is rotatably supported in a non-contact state with a case
member (the cylindrical member 302, the first and second circular
plates 303, 304). As a result, the gaps Ga5, Ga6, Gm are always
kept constant, and stable rotation resistance torque can be
generated.
[0054] Slide bearings receiving bearing members, which are
corresponding to the slide bearings 315, 316 and are fixed to a
shaft member, may be integrally provided on bobbins. In this case,
the bearing members fixed to the shaft member 301 may be regarded
as one body with the shaft member, and a gap between each bearing
member and each slide bearing of the bobbin may be a first gap.
[0055] The rotation resistance apparatuses 100, 200, 300 according
to Examples 1 to 3 described above are small in size and can
efficiently generate rotation resistance torque.
Example 4
[0056] FIG. 9 illustrates an interchangeable lens 400 as an
operation apparatus according to Example 4 of the present
invention. The interchangeable lens 400 is detachably attached to a
camera 500 as an imaging apparatus.
[0057] An imaging optical system 401 is arranged in the
interchangeable lens 400. An outer periphery of the interchangeable
lens 400 is provided with an operation ring 402 as an operation
member that allows a user to perform a rotational operation. When
the operation ring 402 rotates, a variable power lens and a focus
lens in the imaging optical system 401 move to an optical axis
direction to perform zooming and focusing.
[0058] The rotation of the operation ring 402 is transmitted
through the gear 115 to the shaft member 101 of the rotational
resistance apparatus 100 according to Example 1 arranged in the
interchangeable lens 400. As a result, the rotation resistance
torque generated in the rotational resistance apparatus 100 by the
rotational operation of the operation ring 402 is applied as an
operational feeling. The rotational resistance apparatuses 200, 300
described in Examples 2, 3 may be used instead of the rotational
resistance apparatus 100. Further, the rotation resistance
apparatus described in Examples 1 to 3 may be used in operation
apparatuses other than the interchangeable lens.
[0059] According to the above-mentioned example, for example, it is
possible to provide to a rotational resistance apparatus
advantageous in generation efficiency of rotation resistance and
small size.
[0060] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0061] This application claims the benefit of Japanese Patent
Application No. 2019-176362, filed on Sep. 27, 2019 which is hereby
incorporated by reference herein in its entirety.
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