CN115023887A - Linear actuator, interchangeable lens, and imaging device - Google Patents

Abstract

The disclosed device is provided with: a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke; a cylindrical movable coil which is penetrated by the fixed rod and is movable in a coupling direction of the magnet and the inner yoke with respect to the fixed rod; and an outer yoke that is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side. Accordingly, since the outer yoke, the magnet, and the inner yoke are all fixed portions and the movable coil is a movable portion, the generation of braking force and the generation of leakage magnetic flux during driving can be suppressed, the driving force can be improved, and a stable operating state of the movable body can be ensured.

Description

Linear actuator, interchangeable lens, and imaging device

Technical Field

The present technology relates to the technical field of an imaging device, and the imaging device includes: a linear actuator having a magnet and a movable coil, and operating by energizing the movable coil; a replaceable lens provided with a linear actuator; and a linear actuator.

Background

There is a linear actuator that includes a magnet and a movable coil and moves by applying a driving force to a movable body by energizing the movable coil (see, for example, patent documents 1 and 2).

Such a linear actuator is used in various electronic apparatuses including, for example, an interchangeable lens, an imaging device, and the like. In interchangeable lenses, image pickup apparatuses, and the like, for example, a movable lens that functions as a zoom lens and a focus lens, and a lens holder that holds the movable lens are provided as movable bodies, and the movable lens is moved in the optical axis direction together with the lens holder by a driving force of a linear actuator to perform zooming, focusing, and the like.

The linear actuator described in patent document 1 has the following structure: the fixed rod is inserted into the movable coil held by the yoke, and the fixed rod is moved in the axial direction relative to the movable coil by energizing the movable coil.

The linear actuator described in patent document 2 has the following structure: the magnets and the iron are alternately coupled to form a fixed rod, and the fixed rod is inserted into the movable coil held by the yoke, and the movable coil and the yoke are moved in the axial direction integrally with respect to the fixed rod by energizing the movable coil.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-86617

Patent document 2: japanese patent laid-open publication No. 2015-173580

Disclosure of Invention

However, in the linear actuator as described above, in order to ensure a stable operating state of the movable body, it is necessary to improve the driving force by providing a structure that generates a large thrust force, and it is desirable to suppress generation of a braking force (residual force) that is a magnetic attraction force generated between the magnet and the yoke. The braking force is a force generated as a torque ripple when the driving force is applied in the non-excited state.

However, in the linear actuators described in patent documents 1 and 2, a magnet is provided on one of the movable side and the fixed side, and a yoke is provided on the other of the movable side and the fixed side, and in any case, a braking force is generated during driving, and there is a possibility that the driving force is reduced.

In addition, in the linear actuator, since a decrease in thrust force due to the generation of leakage magnetic flux not only causes a decrease in driving force but also causes noise to other electronic components, it is preferable to suppress the generation of leakage magnetic flux.

Therefore, the linear actuator, the interchangeable lens, and the imaging device according to the present technology aim to suppress the generation of a braking force and the generation of leakage magnetic flux during driving, thereby improving the driving force and ensuring a stable operating state of the movable body.

The present technology provides a linear actuator including: a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke; a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and an outer yoke that is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

Thus, the fixed rod having the inner yoke and the magnet is disposed in a fixed state, and at least a part of the fixed rod and the movable coil is covered with the outer yoke disposed in a fixed state from the outer peripheral side.

2, in the above-described replacement lens of the present technology, it is preferable that the fixing lever is entirely covered by the outer yoke in the coupling direction.

Accordingly, all the magnets and the inner yoke are energized to the moving coil in a state of being covered with the outer yoke, and therefore, generation of leakage magnetic flux can be efficiently suppressed.

In the interchangeable lens according to the above-described present technology, preferably, the fixed rod is formed in a prismatic shape, and the movable coil is formed in a square tubular shape.

This makes it possible to form the fixed rod and the movable coil into flat shapes, and to simplify the shapes of the fixed rod and the movable coil.

In the interchangeable lens according to the above-described present technology, it is preferable that the fixed rod is formed in a cylindrical shape and the movable coil is formed in a cylindrical shape.

This makes it possible to minimize the sizes of the fixed lever and the movable coil, and to simplify the shapes of the fixed lever and the movable coil.

In the interchangeable lens according to the above-described present technology, it is preferable that the movable coil be provided with a 1 st arc portion and a 2 nd arc portion which are opposed to each other, and an outer peripheral surface of the fixed rod which is opposed to an inner peripheral surface of the movable coil be formed in a shape similar to the inner peripheral surface.

Thus, when the linear actuator is used for a device having a cylindrical portion, the linear actuator is arranged along the outer periphery of the cylindrical portion, and the arrangement space of the linear actuator becomes small.

In the interchangeable lens according to the above-described present technology, it is preferable that the movable coil is provided with an arc portion and a flat surface portion which are opposed to each other, a convex direction of the arc portion is a direction away from the flat surface portion, and an outer peripheral surface of the fixed rod opposed to an inner peripheral surface of the movable coil is formed in a shape similar to the inner peripheral surface.

Thus, the movable coil is not formed by winding the winding wire so as to be recessed inward, and the winding operation which is difficult to wind is not required.

In the interchangeable lens according to the above-described present technology, it is preferable that a length of the inner yoke in the coupling direction is set to 5% to 65% of a total length of the magnet and the inner yoke in the coupling direction.

This reduces variation in the thrust generated in the moving coil.

In the interchangeable lens according to the above-described present technology, it is preferable that a length of the inner yoke in the coupling direction is set to 5% to 50% of a total length of the magnet and the inner yoke in the coupling direction.

Thus, the influence of the attraction force generated between the adjacent magnets and the inner yoke on the thrust force is not excessive.

In the interchangeable lens according to the above-described present technology, it is preferable that the linear actuator includes a holder having: a web extending in the bonding direction; and a plurality of the inner yokes that are coupled to the coupling plate in a state separated in the coupling direction, and the magnets are inserted between the inner yokes adjacent to each other in the coupling direction.

Thus, the magnet is inserted into the holder which is previously coupled to the coupling plate in a state where the inner yoke is separated, and is coupled to the inner yoke.

10 th, in the interchangeable lens according to the present technology, it is preferable that the interchangeable lens is provided with a non-magnetic plate attached to the fixing lever in a state of being straddled between the inner yoke and the magnet.

Thus, the coupling force between the magnet and the inner yoke is increased by the non-magnetic plate.

11 th, in the interchangeable lens according to the present technology, it is preferable that the interchangeable lens is provided with a thin film tube for sealing the fixing rod from an outer peripheral side.

Thus, the coupling force between the magnet and the inner yoke is increased by the reinforcing effect of the thin film tube.

12 th, in the interchangeable lens according to the present technology, it is preferable that the thin film tube is formed of a material having heat shrinkability, and the thin film tube is heated in a state where the fixing rod is inserted into the thin film tube.

Thereby, the thin film tube is heated in a state where the fixing rod is inserted, and the thin film tube is brought into close contact with the fixing rod from the outer peripheral side.

In the interchangeable lens according to the above-described present technology, it is preferable that a length of at least one of the magnets in the coupling direction is set to be different from a length of the other magnets in the coupling direction, and the length of the magnet in the coupling direction is determined according to the number of the magnets coupled to the inner yoke.

Thus, the length of at least one magnet is set to be different from the other magnets depending on the number of magnets to be coupled, and the magnitude of the thrust force in the coupling direction can be suppressed, and the variation amount of the thrust force can be reduced.

In the interchangeable lens according to the above-described present technology, it is preferable that the magnet has a cross-sectional area at a center in the coupling direction larger than areas at both ends in the coupling direction.

This reduces the difference in magnetic flux density between the positions in the coupling direction, and thus suppresses the occurrence of a sharp variation state of the thrust force in the linear actuator.

In the interchangeable lens according to the above-described present technology, it is preferable that the magnet has a shape in which a cross-sectional area decreases as approaching both ends from the center in the coupling direction.

Accordingly, the sectional area of the magnet changes in the coupling direction, and therefore, the occurrence of a rapid variation state of the thrust force in the linear actuator is suppressed while achieving the reduction in size and weight of the magnet.

A 16 th aspect of the present technology provides an interchangeable lens including a movable body movable in an optical axis direction and a linear actuator for moving the movable body in the optical axis direction, the linear actuator including: a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke; a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and an outer yoke that is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

Thus, in the linear actuator, the fixed rod having the inner yoke and the magnet is disposed in a fixed state, and at least a part of the fixed rod and the movable coil is covered with the outer yoke disposed in a fixed state from an outer peripheral side.

A 17 th aspect of the present invention provides an imaging device including an imaging element for converting an optical image into an electrical signal, a movable body movable in an optical axis direction, and a linear actuator for moving the movable body in the optical axis direction, the linear actuator including: a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke; a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and an outer yoke that is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

Thus, in the linear actuator, the fixed rod having the inner yoke and the magnet is disposed in a fixed state, and at least a part of the fixed rod and the movable coil is covered with the outer yoke disposed in a fixed state from an outer peripheral side.

Drawings

Fig. 1 shows an embodiment of a linear actuator, an interchangeable lens, and an imaging device according to the present technology together with fig. 2 to 43, and this figure is a perspective view showing the interchangeable lens and the imaging device.

Fig. 2 is a perspective view showing a part of the internal structure of the replacement lens.

Fig. 3 is a perspective view showing a part of the internal structure of the replacement lens with the outer yoke separated.

Fig. 4 is a sectional view taken along line IV-IV of fig. 2.

Fig. 5 is a sectional view taken along line V-V of fig. 2.

Fig. 6 is a sectional view taken along line VI-VI of fig. 2.

Fig. 7 is a perspective view of the linear actuator.

Fig. 8 is a cross-sectional view of the linear actuator.

Fig. 9 is a conceptual diagram illustrating the structure of the moving coil.

Fig. 10 is an enlarged perspective view showing a coil mounting portion and the like of the lens holder.

Fig. 11 is a conceptual diagram illustrating a generation state of magnetic flux in the linear actuator.

Fig. 12 is a conceptual diagram illustrating a state of magnetic flux generated from the magnet.

Fig. 13 is a conceptual diagram illustrating forces generated in the magnet and the inner yoke.

Fig. 14 is a diagram for explaining the action of the outer yoke, and the upper layer is a graph in the structure with the outer yoke, and the lower layer is a graph in the structure without the outer yoke.

Fig. 15 is a perspective view showing an example of a linear actuator in which a fixing rod is formed in a cylindrical shape.

Fig. 16 is a cross-sectional view showing an example in which the moving coil is provided with two circular arc portions.

Fig. 17 is a cross-sectional view showing an example in which the moving coil is provided with one arc portion.

Fig. 18 is a graph showing the measurement results of the 1 st measurement test.

Fig. 19 is a graph showing the measurement results of the 2 nd measurement test, together with fig. 19 to 26, and this graph is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 5%.

Fig. 20 is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 10%.

Fig. 21 is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 20%.

Fig. 22 is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 30%.

Fig. 23 is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 40%.

Fig. 24 is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 50%.

Fig. 25 is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 65%.

Fig. 26 is a graph showing a case where the ratio of the length of the inner yoke to the total of the magnet and the inner yoke is 80%.

Fig. 27 is a graph showing the state of occurrence of variation in thrust force calculated from the measurement results of the 2 nd measurement test.

Fig. 28 is an exploded perspective view showing an example of a fixing rod formed by using a holder together with fig. 29 and 30, and the magnet is mounted on the holder.

Fig. 29 is a sectional view of the cage.

Fig. 30 is a perspective view showing a state in which the magnet is attached to the holder.

Fig. 31 and 32 show an example in which the nonmagnetic plate is attached to the fixed lever, and this figure is a perspective view showing a state before the nonmagnetic plate is attached to the fixed lever.

Fig. 32 is a sectional view showing a state where the nonmagnetic plate is attached to the fixed lever.

Fig. 33 is an exploded perspective view showing an example in which the membrane tube is attached to the fixing rod, together with fig. 34 and 35, and the membrane tube is attached to the fixing rod before the membrane tube is attached to the fixing rod.

Fig. 34 is a perspective view showing a state in which the thin film tube is attached to the fixing rod.

Fig. 35 is a conceptual view showing a state in which a thin film tube is attached to a fixing rod having an inclined surface.

Fig. 36 shows an example of the relationship between the length of the magnets in the coupling direction and the variation in the thrust together with fig. 37 and 38, and this figure is a conceptual diagram showing that fixed rods in which the lengths of odd-numbered magnets in the coupling direction are the same and fixed rods in which the lengths of odd-numbered magnets in the coupling direction are different are arranged.

Fig. 37 is a graph showing the magnitude of the thrust force with respect to the position of the magnet in the coupling direction.

Fig. 38 is a conceptual diagram illustrating a fixing rod in which the lengths of the even-numbered magnets in the coupling direction are set to be the same and a fixing rod in which the lengths of the even-numbered magnets in the coupling direction are set to be different.

Fig. 39 is a conceptual diagram showing an example of a relationship between the shape of the magnet and the variation of the thrust force, together with fig. 40, and this diagram shows a variation state of the thrust force in the fixed rod having the magnet having the same size in cross-sectional area in the coupling direction.

Fig. 40 is a conceptual diagram illustrating a variation state of thrust in a fixed rod having magnets with different sectional areas in the coupling direction.

Fig. 41 is a conceptual diagram showing an example of a relationship between the length of the magnet or the like in the coupling direction and the distance between the coil portions of the moving coil, together with fig. 42.

Fig. 42 is a conceptual diagram illustrating an example in the case where the length of the magnet or the like in the coupling direction is long.

Fig. 43 is a block diagram of the image pickup apparatus.

(symbol description)

100: a camera device; 104: an image pickup element; 1: replacing the lens; 15: a linear actuator; 16: fixing the rod; 17: a movable coil; 18: an outer yoke; 19: a magnet; 20: an inner yoke; 32: the 1 st circular arc part; 33: a 2 nd arc portion; 35: a circular arc portion; 36: a planar portion; 38: a holder; 39: a connecting plate; 41: a non-magnetic plate; 42: a thin film tube; 19A: a magnet; 19B: a magnet; 19C: a magnet; 98: an image pickup element.

Detailed Description

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

The embodiments described below apply the linear actuator of the present technology to a linear actuator provided in an interchangeable lens that is attached to and detached from an imaging apparatus as a still camera. The application range of the present technology is not limited to the linear actuator provided in the interchangeable lens, and the present technology can be applied to a linear actuator provided in an imaging device, and can also be applied to a linear actuator provided in various electronic apparatuses other than the imaging device.

In the following description, the directions of front, rear, up, down, left, and right are shown in the direction viewed from the photographer when shooting is performed by the imaging device. Therefore, the subject side (object side) is the front, and the image plane side is the rear. The front-back, up-down, left-right directions shown below are set for convenience of explanation, and the implementation of the present technology is not limited to these directions.

The lens group described below may be configured by a single or a plurality of lenses, and may include these single or a plurality of lenses and other optical elements such as an aperture stop and an aperture stop.

< construction of imaging apparatus >

First, a configuration of the image pickup apparatus 100 in which the interchangeable lens 1 is attached and detached will be described (see fig. 1).

The imaging apparatus 100 is configured by arranging necessary parts inside and outside the housing 101. In the housing 101, various operation sections 102, · are disposed on, for example, the upper surface and the rear surface. As the operation section 102, for example, a power button, a shutter button, a zoom knob, a mode switching knob, and the like are provided.

A display (display unit), not shown, is disposed on the rear surface of the housing 101.

A circular opening 101a is formed in the front surface of the housing 101, and an attachment ring 103 for attaching the interchangeable lens 1 is provided around the opening 101 a. The collar portion 103 includes an annular coupling ring 103a and arc-shaped collar engagement portions 103b, and 103b protruding inward from the coupling ring 103a, and the collar engagement portions 103b, and 103b are provided so as to be separated in the circumferential direction.

An imaging element 104 such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide Semiconductor) is disposed inside the housing 101, and the imaging element 104 is located behind the opening 101 a.

An arc-shaped contact portion 105 is disposed at the inner lower end of the collar portion 103.

< Structure for replacing lens >

Next, a structure of the interchangeable lens 1 will be described (see fig. 1 to 10).

The interchangeable lens 1 is attachable to and detachable from the imaging apparatus 100, and is configured by arranging necessary parts inside and outside the outer cylinder 2 (see fig. 1).

The adjustment rings 3, 3 are rotatably supported on the outer peripheral surface of the outer cylinder 2 in a state of being arranged in the front-rear direction. The adjustment rings 3 and 3 have functions of, for example, focus adjustment, zoom adjustment, light amount adjustment of the aperture stop, and the like.

Inside the outer tube 2, a plurality of lens groups 4, · · are arranged separately in the optical axis direction (front-rear direction). The lens group 4 has at least one lens, and a front lens 4a located closest to the front side and another lens located behind the front lens 4a are arranged as parts of the lens group 4 in the outer tube 2.

A lens mount 5 is attached to the rear end of the outer tube 2. In the lens mount 5, engagement projections 5a, 5a projecting outward are provided so as to be separated in the circumferential direction. A connection terminal, not shown, is provided on the rear end surface of the lens mount 5.

The interchangeable lens 1 is attached to the image pickup apparatus 100 by being coupled to the link portion 103 via the lens link 5. The replacement lens 1 can be attached to the imaging apparatus 100 by rotating the entire replacement lens 1 in the optical axis direction with respect to the imaging apparatus 100.

In a state where the interchangeable lens 1 is attached to the imaging apparatus 100, the connection terminal is connected to the contact portion 105 of the imaging apparatus 100. Therefore, the exchange of signals and the supply of electric power between the interchangeable lens 1 and the imaging apparatus 100 are enabled.

The replacement lens 1 can be detached from the imaging apparatus 100 by rotating the entire replacement lens 1 with respect to the imaging apparatus 100 in the direction opposite to the direction around the optical axis when attached, and the replacement lens 1 can be detached from the imaging apparatus 100.

A mechanism unit 6 (see fig. 2 to 6) is disposed inside the interchangeable lens 1. The mechanism unit 6 is configured by arranging or supporting necessary parts in the inner tube 7. In the interchangeable lens 1, the inner cylinder 7 may be integrally provided in the outer cylinder 2 as a part of the outer cylinder 2.

The inner tube 7 is made of a non-magnetic material such as a resin material or a magnetic material, and has a cylindrical body portion 8 having an axial direction in the optical axis direction (front-rear direction), and an inner flange portion 9 projecting inward from one end portion in the axial direction of the body portion 8.

A 1 st bearing projection 10 projecting inward is provided at one end of the body 8 in the axial direction. A 2 nd bearing projection 11 projecting inward is provided at a substantially central portion in the axial direction of the body portion 8, and the 2 nd bearing projection 11 is located on a substantially 180-degree opposite side in the circumferential direction with respect to the 1 st bearing projection 10.

Insertion holes 8a, 8a are formed in the body 8 at positions on the opposite side with respect to the central axis. The insertion holes 8a, 8a are formed at positions separated by, for example, 90 degrees in the circumferential direction with respect to the 1 st bearing projection 10 and the 2 nd bearing projection 11, and are formed from a position near one end of the body 8 in the axial direction to a position near the other end in the axial direction of the body 8. The insertion holes 8a and 8a may be formed at positions that are not separated by 90 degrees in the circumferential direction with respect to the 1 st bearing projection 10 and the 2 nd bearing projection 11.

In the inner flange portion 9, holding projections 12, 12 are provided in the vicinity of the insertion holes 8a, respectively. The holding projection 12 includes end portions 12b and 12b projecting in the same direction from both ends in the longitudinal direction of the linear base portion 12a and the base portion 12 a.

The inner flange 9 has mounting holes 9a, 9a (see fig. 4) formed at positions on the opposite side with respect to the central axis. The attachment holes 9a, 9a are formed at positions separated by, for example, 90 degrees in the circumferential direction with respect to the holding projections 12, 12. The positions where the mounting holes 9a and 9a are formed may not be separated by 90 degrees in the circumferential direction with respect to the holding projections 12 and 12. In the inner flange portion 9, screw through holes 9b and two positioning pins (not shown) are provided near the holding projections 12 and 12, respectively (see fig. 5).

Bearings 13 and 13 are attached to the 1 st bearing projection 10 and the 2 nd bearing projection 11 of the main body 8, respectively, and bearings 13 and 13 are also attached to the mounting holes 9a and 9a of the inner flange 9, respectively (see fig. 4).

Guide shafts 14 and 14 (see fig. 2 to 4) are attached to the inner cylinder 7. One guide shaft 14 is attached to the inner tube 7 via a bearing 13 attached to the 1 st bearing projection 10 and a bearing 13 attached to one attachment hole 9a, and the other guide shaft 14 is attached to the inner tube 7 via a bearing 13 attached to the 2 nd bearing projection 11 and a bearing 13 attached to the other attachment hole 9 a.

In the inner tube 7, the linear actuators 15 and 15 are disposed on opposite sides with respect to the central axis of the main body 8 (see fig. 2, 3, 5, and 6). The linear actuator 15 includes a fixed rod 16, a movable coil 17, and an outer yoke 18 (see fig. 7 and 8).

The fixing lever 16 has at least two magnets 19, 19 (e.g., four magnets 19, · · ·) and at least one inner yoke 20 (e.g., three inner yokes 20, 20), and the magnets 19, · · · · · · · · · · · · · · · · · · and the inner yokes 20, 20 are alternately joined in a straight line, for example, by bonding or the like. The cross-sectional shape of the fixing lever 16 in the direction orthogonal to the coupling direction of the magnet 19 and the inner yoke 20 is, for example, a substantially rectangular shape, and is formed in a flat shape as a whole. In the substantially rectangular cross-sectional shape, the direction in which the dimension is small is the thickness direction, and the direction in which the dimension is large is the width direction.

The N-pole and S-pole of the magnet 19 are magnetized in the direction of joining the magnet 19 and the inner yoke 20 (see fig. 8). Therefore, in the magnets 19, 19 adjacent to each other with the inner yoke 20 interposed therebetween, the same pole is coupled to the inner yoke 20 positioned between the adjacent magnets 19, and the N pole face each other or the S pole and the S pole face each other.

The lengths Lm of the magnets 19, · · · in the coupling direction are, for example, the same, and the lengths Ly of the inner yokes 20, 20 in the coupling direction are, for example, the same. The length Lm of the magnet 19 in the coupling direction is longer than the length Ly of the inner yoke 20 in the coupling direction. The magnets 19, · · are set so that boundaries 19a, · · of N poles and S poles become predetermined positions in the bonding direction. Therefore, the positions of the boundaries 19a, and · · are determined to be predetermined positions, respectively, regardless of the lengths of the magnets 19, · · and the inner yokes 20, · · in the joining direction, respectively.

The inner yoke 20 is formed of a magnetic material such as iron. The thickness of the inner yoke 20 is, for example, substantially the same as the thickness of the magnet 19, and the width is, for example, substantially the same as the width of the magnet 19.

The fixing lever 16 is provided with coupling members 21, 21 at both ends in the coupling direction, and the coupling members 21, 21 are attached to the magnets 19, respectively, by, for example, adhesion or the like (see fig. 7 and 8). Screw fixing holes 21a and positioning holes 21b, 21b are formed in the coupling member 21.

The movable coil 17 is formed in a substantially square tubular shape as a whole according to the shape of the fixed lever 16, and has a 2-phase structure. The moving coil 17 includes coil portions 17a and 17a constituting phase 1 and coil portions 17b and 17b constituting phase 2, and the coil portions 17a and 17b are alternately arranged. Therefore, in the moving coil 17, the coil portion 17a, the coil portion 17b, the coil portion 17a, and the coil portion 17b are arranged in this order in the axial direction, and a predetermined gap M, M, M (see fig. 9) for passing the windings 17c and 17d is formed between the coil portions 17a, 17b, 17a, and 17 b.

The movable coil 17 is configured by filling the gap M, M, M with an adhesive agent to sequentially join the coil portions 17a, 17b, 17a, and 17 b. The coil units 17a and 17a are supplied with drive currents in opposite directions, and the coil units 17b and 17b are also supplied with drive currents in opposite directions (the directions of the drive currents are indicated by arrows in fig. 9).

Further, as described above, in the movable coil 17, the coil portion 17a and the coil portion 17a are connected by the 1 wire 17c, and the coil portion 17b are connected by the 1 wire 17d, so that it is not necessary to form the coil portions 17a, 17b, 17a, and 17b separately and connect the coil portion 17a and the coil portion 17a as a subsequent step, and the coil portion 17b are connected, and the movable coil 17 can be formed easily and in a short time. The number of the coil portions 17a and 17b constituting the 1 st phase and the 2 nd phase is arbitrary, and may be one, or three or more.

The fixed rod 16 is inserted through the moving coil 17 (see fig. 5, 7, and 8). When the movable coil 17 is energized, thrust is generated in the driving coil 17 in relation to the magnetic flux generated by the fixed rod 16, and the movable coil 17 moves in the coupling direction (optical axis direction) of the fixed rod 16 in accordance with the direction of energization to the movable coil 17. Therefore, in the linear actuator 15, the fixed rod 16 functions as a fixed part, and the movable coil 17 functions as a movable part.

The outer yoke 18 is formed of a magnetic material such as iron. The outer yoke 18 covers at least a part of the fixed rod 16 and the movable coil 17 from the outer peripheral side, and is formed by bending a plate-like material into a predetermined shape. The outer yoke 18 includes a base surface portion 18a having the largest area and side surface portions 18b, 18b bent in the same direction orthogonal to both end edges of the base surface portion 18 a. The size in the length direction of the outer yoke 18 is substantially the same as the length of the fixing rod 16 in the coupling direction.

The fixing rods 16 and 16 of the linear actuators 15 and 15 configured as described above are attached to the inner cylinder 7 (see fig. 4 to 6). The fixing rod 16 is mounted to the inner cylinder 7 as follows: the positioning pins provided in the flange portion 9 are inserted into the positioning holes 21b, 21b of one of the coupling members 21, respectively, and positioned with respect to the inner cylinder 7, and the mounting screws 200 are inserted through the screw insertion holes 9b of the flange portion 9 and screwed into the screw fixing holes 21a of the coupling members 21. At this time, the end of one coupling member 21 is disposed in contact with the inner surface of the holding protrusion 12.

The other coupling member 21 of the fixing rod 16 is held by the holding member 22 (see fig. 5). The holding member 22 is formed of a nonmagnetic material such as a resin material, and has a flat plate-like holding base 23 and a holding frame portion 24 protruding from one surface of the holding base 23 in the thickness direction. A screw through-hole 23a penetrating in the thickness direction is formed in the holding base 23 on the inner side of the holding frame portion 24. The holding base 23 is provided with positioning pins, not shown, on the opposite side across the screw insertion holes 23 a.

The end of the other coupling member 21 is inserted into the inside of the holding frame 24 of the holding member 22, the positioning pins of the holding member 22 are inserted into the positioning holes 21b and 21b, respectively, and are positioned with respect to the coupling member 21, the mounting screw 200 is inserted through the screw insertion hole 23a of the holding member 22 and screwed into the screw fixing hole 21a of the coupling member 21, and the fixing rod 16 is held by the holding member 22.

A part of the holding member 22 holding the fixing rod 16 is fixed to an opening edge of the insertion hole 8a formed in the inner tube 7 by adhesion or the like, and the fixing rod 16 is attached to the inner tube 7 via the holding member 22. The fixed rod 16 is attached to the inner tube 7 via the holding member 22 in a state of being inserted through the movable coil 17.

The outer yoke 18 is inserted into an insertion hole 8a formed in the main body 8 of the inner tube 7 from the outer peripheral surface side of the main body 8 in a state where the fixing rod 16 is attached to the inner tube 7, and is attached to the inner tube 7 and the holding member 22 by adhesion or the like (see fig. 2 and 3). The outer yoke 18 is attached to the inner tube 7 and the holding member 22 by bonding or the like in a state where both ends in the longitudinal direction are fitted from the outside to the holding projection 12 provided to the flange portion 9 and the holding frame portion 24 provided to the holding member 22.

In this way, the outer yoke 18 is attached to the inner tube 7 and the holding member 22, and thus functions as a fixing portion. Therefore, in the linear actuator 15, the fixed rod 16 and the outer yoke 18 function as fixed portions, and the movable coil 17 functions as a movable portion.

In a state where the outer yoke 18 is attached to the inner tube 7 and the holding member 22, three surfaces of the fixed rod 16 and the movable coil 17 are covered with the outer yoke 18. That is, the fixed rod 16 and the movable coil 17 are covered with the outer yoke 18 except for the surface facing the central axis side of the inner tube 7. The outer yoke 18 may be disposed at any position with respect to the fixed rod 16 and the movable coil 17 as long as it is at a position where it does not interfere with a coil mounting portion described later.

The lens holder 25 and the lens 4b provided as movable bodies are supported on the guide shafts 14 and 14 so as to be movable in the optical axis direction (see fig. 2 to 6). The lens 4b is one of the lens groups 4, is held by the lens holder 25, and functions as a focus lens or a zoom lens, for example.

The lens holder 25 includes a frame-shaped lens holding portion 26, supported portions 27, 27 projecting in opposite directions on the outer peripheral side from the lens holding portion 26, coil mounting portions 28, 28 projecting in opposite directions on the outer peripheral side from the lens holding portion 26, and mounting protrusions 29, 29 projecting in predetermined directions on the outer peripheral side from the lens holding portion 26. The supported portions 27, 27 and the coil mounting portions 28, 28 project from the lens holding portion 26 in directions orthogonal to each other.

The lens 4b is held by the lens holding portion 26. The lens 4b is attached to the lens holding portion 26 by bonding, press-fitting, or the like.

The supported portions 27, 27 are slidably supported on the guide shafts 14, respectively. Therefore, the lens holder 25 is guided by the guide shafts 14 and 14 integrally with the lens 4b and moves in the optical axis direction.

The coil mounting portion 28 has joint portions 28a, · aligned in the optical axis direction, and the joint portions 28a, · are formed in a concave shape that opens outward in the radial direction of the lens holding portion 26 (see fig. 10). The coil portions 17a, 17b, 17a, and 17b of the moving coil 17 are attached to the joining portions 28a and 28a, and 17, respectively, by bonding or the like (see fig. 3 and 6). Therefore, when the movable coil 17 is energized, the movable coil 17 moves in the optical axis direction with respect to the fixed rod 16, the lens holder 25 and the lens 4b move in the optical axis direction together with the movable coil 17, and the movable coil 17, the lens 4b, and the lens holder 25 function as a movable body.

The lens 4b moves in the optical axis direction, for example, to perform focusing or zooming.

A detection rod 30 (see fig. 2, 3, and 6) extending in the optical axis direction is attached to the attachment projection 29. The detection rod 30 moves in the optical axis direction together with the lens holder 25.

Detectors 31, 31 are attached to the inner peripheral surface of the body 8 of the inner tube 7 at positions facing the detection rods 30, respectively. The position of the detection rod 30 when the lens holder 25 moves is detected by the detector 31, and the position of the detection rod 30 is detected, whereby the position of the lens 4b in the optical axis direction or the amount of movement in the optical axis direction is detected.

< relationship between magnetic flux and moving coil >

Next, the relationship between the magnetic flux generated in the linear actuator 15 and the moving coil 17, and the like will be described (see fig. 11 to 13). Fig. 11 to 13 are conceptual diagrams for easily explaining the relationship between the magnetic flux generated in the linear actuator 15 and the movable coil 17.

As described above, the magnets 19, · of the fixing rod 16 of the linear actuator 15 are alternately coupled to the inner yokes 20, ·, the N-pole and the S-pole of the magnet 19 are magnetized in the coupling direction, and the N-pole or the S-pole, which are the same poles, of the magnets 19, 19 adjacent to each other with the inner yoke 20 interposed therebetween are coupled to both surfaces of the inner yoke 20 (see fig. 11).

Fig. 11 shows a state in which the center of the coil portion 17a or the coil portion 17b of the driving coil 17 in the coupling direction coincides with the center of the magnet 19 or the inner yoke 20 in the coupling direction.

The magnetic flux J generated in the magnet 19 passes from the N pole through the inner yoke 20 coupled to one surface of the magnet 19, traverses the moving coil 17, passes through the outer yoke 18, passes through the inner yoke 20 coupled to the other surface of the magnet 19, and reaches the S pole. At this time, the inner yoke 20 is coupled to the N-pole side one end surface 19b of the magnet 19, the inner yoke 20 is coupled to the S-pole side other end surface 19c of the magnet 19, and the magnetic flux J is directed from the N-pole to the entire circumferential direction of the outer periphery of the one end surface 19b and from the entire circumferential direction of the outer periphery of the other end surface 19c to the S-pole (see fig. 12).

Therefore, since the magnetic flux J traverses the entire circumference of the moving coil 17, approximately 100% of the magnetic flux contributes to the thrust of the moving coil 17, and generates the thrust over the entire circumference of the moving coil 17, thereby ensuring high driving efficiency in the linear actuator 15.

Further, since the thrust force is generated over the entire circumference of the moving coil 17, high driving efficiency in the linear actuator 15 can be ensured, and accordingly, even if each part in the linear actuator 15 is made small, a sufficient driving force can be ensured, and the linear actuator 15 can be made small and light.

Further, since the magnetic flux J crossing the movable coil 17 passes through the outer yoke 18 located on the outer peripheral side of the movable coil 17 and is directed toward the S pole, the leakage of the magnetic flux can be reduced by the outer yoke 18, and the thrust of the driving coil 17 can be further improved.

In particular, the linear actuator 15 is configured such that the entire fixing rod 16 in the coupling direction is covered by the outer yoke 18.

Therefore, since the movable coil 17 is energized in a state where all of the magnets 19, ·, and the inner yokes 20, ·, are covered with the outer yoke 18, generation of leakage magnetic flux can be efficiently suppressed, and a large thrust can be generated by the movable coil 17, thereby further improving the driving force of the linear actuator 15.

Further, the same pole of the linear actuator 15 is coupled to the inner yoke 20 at the adjacent magnets 19, 19 (see fig. 13). Therefore, although the repulsive force P is generated between the adjacent magnets 19, in the linear actuator 15, since the inner yoke 20 is disposed between the adjacent magnets 19, the attracting force Q is generated between the inner yoke 20 and the magnets 19, and the repulsive force P generated between the magnets 19, 19 is reduced.

Further, since the inner yoke 20 is disposed between the adjacent magnets 19 and 19, the adjacent magnets 19 and 19 are disposed with a constant gap therebetween, and thus the repulsive force P generated between the magnets 19 and 19 is also reduced.

Therefore, difficulty in assembling the fixing rod 16 due to generation of the repulsive force P when the magnets 19, · · and the inner yokes 20, · · are coupled is reduced, and the fixing rod 16 having a structure in which the same pole of the adjacent magnets 19, 19 is coupled to the inner yoke 20 can be assembled in an easy and stable state.

Fig. 14 shows the results of measuring the magnitude of the thrust generated by the moving coil 17 in response to the presence or absence of the outer yoke 18. The graph shown in the upper tier of fig. 14 shows the thrust in the linear actuator 15 with the outer yoke 18, and the graph shown in the lower tier of fig. 14 shows the thrust in the linear actuator without the outer yoke 18.

In fig. 14, the horizontal axis represents the position of the moving coil 17 in the coupling direction, and the vertical axis represents the thrust generated by the moving coil 17. Fig. 14 shows the resultant force of the thrust generated by each of the 1 st phase and the 2 nd phase of the moving coil 17 and the thrust generated by the 1 st phase and the 2 nd phase of the moving coil 17. The 1 st phase is coil portions 17a, and the 2 nd phase is coil portions 17b, 17 b.

As shown in fig. 14, it has been demonstrated that the thrust generated in the linear actuator 15 having the outer yoke 18 is larger than the thrust generated in the linear actuator not having the outer yoke 18, the outer yoke 18 suppresses the generation of the leakage magnetic flux, and the outer yoke 18 greatly contributes to the generation of the thrust generated in the moving coil 17.

< shapes of fixed lever and movable coil >

Next, the shapes of the fixed rod 16, the movable coil 17, and the like will be described (see fig. 7, 8, 15 to 17).

As described above, the cross-sectional shape of the fixed rod 16 in the coupling direction is, for example, a substantially rectangular shape, and the moving coil 17 is formed in a substantially square tubular shape (see fig. 7 and 8).

In this way, since the fixed rod 16 is formed in a prismatic shape and the movable coil 17 is formed in a square tubular shape, the fixed rod 16 and the movable coil 17 can be formed in a flat shape, and the shapes of the fixed rod 16 and the movable coil 17 are simple, the linear actuator 15 can be thinned, and the linear actuator 15 can be easily formed.

Further, by forming the fixed rod 16 and the movable coil 17 in a flat shape, when the linear actuator 15 is used for the interchangeable lens 1 as described above, the arrangement space of the linear actuator 15 can be reduced on the outer peripheral side of the lens 4b functioning as a focus lens or a zoom lens, and the device using the linear actuator 15 can be downsized.

On the other hand, the linear actuator 15 may be formed such that the fixed rod 16 is formed in a cylindrical shape and the movable coil 17 is formed in a cylindrical shape, for example (see fig. 15).

In this way, since the fixed rod 16 is formed in a cylindrical shape and the movable coil 17 is formed in a cylindrical shape, the size of the fixed rod 16 and the size of the movable coil 17 can be minimized, and the shape of the fixed rod 16 and the shape of the movable coil 17 are simplified, the linear actuator 15 can be miniaturized, and the linear actuator 15 can be easily formed.

In the linear actuator 15, the movable coil 17 may be provided with the 1 st arc portion 32 and the 2 nd arc portion 33 which are opposed to each other, the portions of the movable coil 17 between the 1 st arc portion 32 and the 2 nd arc portion 33 may be provided as the connection portions 34 and 34, respectively, and the outer peripheral surface of the fixed rod 16 which is opposed to the inner peripheral surface of the movable coil 17 may be formed in a shape similar to the inner peripheral surface of the movable coil 17 (see fig. 16).

When the fixed rod 16 and the movable coil 17 are formed in such shapes, the outer yoke 18 is formed in a shape having portions facing the 1 st arc portion 32 and the coupling portions 34 and 34, respectively.

In this way, the movable coil 17 has the 1 st arc portion 32 and the 2 nd arc portion 33, and the fixed lever 16 is formed in a shape corresponding to the movable coil 17, so that the fixed lever 16 and the movable coil 17 are formed in an arc shape as a whole. Therefore, when the linear actuator 15 is used for a device having a cylindrical portion such as the interchangeable lens 1, the linear actuator 15 is disposed along the outer periphery of the cylindrical portion, and the device can be downsized by effectively utilizing the space.

Further, in the linear actuator 15, the movable coil 17 may be provided with the arc portion 35 and the flat surface portion 36 which are opposed to each other, the portions of the movable coil 17 between the arc portion 35 and the flat surface portion 36 may be provided as the connection portions 37 and 37, respectively, the convex direction of the arc portion 35 may be a direction away from the flat surface portion 36, and the outer peripheral surface of the fixed rod 16 which faces the inner peripheral surface of the movable coil 17 may be formed in a shape similar to the inner peripheral surface of the movable coil 17 (see fig. 17).

When the fixed rod 16 and the movable coil 17 are formed in such shapes, the outer yoke 18 is formed in a shape having portions facing the circular arc portion 35 and the coupling portions 37 and 37, respectively.

In this way, the movable coil 17 has the arc portion 35 and the flat portion 36, and the fixed lever 16 is formed in a shape corresponding to the movable coil 17, so that it is not necessary to form a concave portion inwardly in the annular shape of the movable coil 17. Therefore, the movable coil 17 does not need to be formed by winding the windings 17c and 17d so as to be recessed inward, and the movable coil 17 can be easily formed without requiring a difficult winding operation of the windings 17c and 17d, and the manufacturing cost of the linear actuator 15 can be reduced.

In addition, even when the linear actuator 15 is used for a device having a cylindrical portion such as the interchangeable lens 1, the linear actuator 15 is disposed along the outer periphery of the cylindrical portion, whereby the device can be downsized by effectively utilizing the space.

< Performance of Linear actuator >

Next, the performance of the linear actuator 15 will be described (see fig. 18 to 27).

In order to confirm the performance of the linear actuator 15, a 1 st measurement test (see fig. 18) and a 2 nd measurement test (see fig. 19 to 26) were performed, in which the relationship between "thrust generated by the moving coil 17" and "repulsive force generated between the magnets 19, 19" was measured in the 1 st measurement test, and "thrust generated by the moving coil 17" was measured in the 2 nd measurement test. The 1 st and 2 nd measurement tests were performed using a linear actuator 15 (see fig. 15) in which a fixing rod 16 is formed in a columnar shape.

In the measurement test 1, the lengths of the magnet 19 and the inner yoke 20 in the coupling direction were changed, and the magnitudes of the thrust force and the repulsive force when the ratio of the lengths of the magnet 19 and the inner yoke 20 was changed were measured (see fig. 18).

In fig. 18, the horizontal axis indicates "the ratio of the length of the inner yoke 20 in the coupling direction", specifically, indicates "the ratio of the length of the inner yoke 20 to the total length of the magnet 19 and the inner yoke 20". In fig. 18, the vertical axis represents "thrust generated by the moving coil 17" and "repulsive force generated between the magnets 19 and 19". The thrust shown in fig. 18 is an average value of the thrust generated by the coil portions 17a, 17b, and 17 b.

As shown in fig. 18, the thrust force is maximized in the vicinity of the length of the inner yoke 20 of 20%, and the thrust force is preferably 3.5 newtons or more in the range of the length of the inner yoke 20 of 5% to 50%.

As shown in fig. 18, the repulsive force is zero in the vicinity of 30% of the length of the inner yoke 20, and when the length of the inner yoke 20 is equal to or greater than this, the attracting force acts. Therefore, in a range where the ratio of the length of the inner yoke 20 is large, the force generated between the magnet 19 and the inner yoke 20 becomes an attracting force, and the fixing rod 16 is easily assembled.

In this way, the length of the inner yoke 20 in the coupling direction is set to 5% to 50% of the total length of the magnet 19 and the inner yoke 20 in the coupling direction, and thus the assemblability of the fixed rod 16 can be improved while securing a large thrust force for operating the movable coil 17.

In particular, the length of the inner yoke 20 in the coupling direction is set to 10% to 30% of the total length of the magnet 19 and the inner yoke 20 in the coupling direction, so that a large thrust force for operating the moving coil 17 can be ensured, and a favorable driving state of the linear actuator 15 can be ensured.

Further, since the length of the inner yoke 20 in the coupling direction is set to 30% or more with respect to the total length of the magnet 19 and the inner yoke 20 in the coupling direction, the repulsive force is significantly reduced, and therefore, the difficulty in assembling the fixing lever 16 due to the generation of the repulsive force P is reduced, and the fixing lever 16 having a structure in which the same pole of the adjacent magnets 19, 19 is coupled to the inner yoke 20 can be assembled in an easy and stable state.

In the 2 nd measurement test, the lengths of the magnet 19 and the inner yoke 20 in the coupling direction were changed, and the magnitude of the thrust generated by the movable coil 17 when the ratio of the lengths of the inner yoke 20 was changed was measured (see fig. 19 to 26).

In fig. 19 to 26, the horizontal axis represents "the position of the movable coil 17 in the coupling direction". In fig. 19 to 26, the vertical axis represents "thrust generated by the 1 st phase and the 2 nd phase of the moving coil 17" and "resultant force of thrust generated by the 1 st phase and the 2 nd phase of the moving coil 17". The thrust forces shown in fig. 19 to 26 are average values of the thrust forces generated by the coil portions 17a, 17b, and 17 b. The 1 st phase is coil portions 17a, and the 2 nd phase is coil portions 17b, 17 b.

Fig. 27 shows "unevenness of thrust" calculated from the results shown in fig. 19 to 26. In fig. 27, the horizontal axis indicates "the ratio of the lengths of the inner yoke 20 in the coupling direction", specifically, indicates "the ratio of the length of the inner yoke 20 to the total length of the magnet 19 and the inner yoke 20". In fig. 27, the vertical axis represents "variation in thrust force". The "variation in thrust force" is a value calculated by taking the ratio of the difference between the maximum value and the minimum value to the maximum value, among the resultant forces of thrust forces generated in the 1 st phase and the 2 nd phase of the moving coil 17. Therefore, the larger the value, the larger the "variation in thrust force".

As shown in fig. 27, the variation in the thrust force is minimized in the vicinity of the length ratio of 50% between the magnet 19 and the inner yoke 20, and the ratio of 5% to 65% between the lengths of the inner yoke 20 is a value smaller than 0.2, which yields favorable results.

In this way, the length of the inner yoke 20 in the coupling direction is set to 5% to 65% of the total length of the magnet 19 and the inner yoke 20 in the coupling direction, so that variation in the thrust generated by the moving coil 17 is reduced, and it is possible to suppress generation of variation in the thrust in the linear actuator 15 and ensure a smooth operating state of the moving coil 17.

< example of Structure relating to Linear actuator >

Next, each configuration example of the linear actuator 15 will be described (see fig. 28 to 34).

The first configuration example 1 is an example in which the magnets 19, · · and · are bonded to a previously assembled holder 38 to constitute the fixing rod 16 (see fig. 28 to 30).

The cage 38 includes a pair of coupling plates 39, 39 and the inner yokes 20, 20 coupled to the coupling plates 39, 39 (fig. 28 and 29). The connecting plate 39 is formed in a shape extending in the bonding direction by a resin material, a metal material such as aluminum or brass, or a nonmagnetic material such as carbon. The inner yoke 20 has insertion recesses 20a, 20a at both ends in a direction orthogonal to the coupling direction.

The inner yoke 20 is inserted into the coupling plates 39, 39 in the insertion recesses 20a, and is fixed to the coupling plates 39, 39 by screwing or the like. The inner yokes 20, · are present at equal intervals in the direction in which the connecting plates 39, 39 extend, and arrangement spaces 40, · are formed between the inner yokes 20, ·.

Magnets 19, and are inserted into the arrangement spaces 40, and are arranged in the holder 38, and the magnets 19, and are bonded to the adjacent inner yokes 20, and 30 by adhesion or the like (see fig. 30). Thus, the fixing rod 16 in which the magnets 19, · and the inner yokes 20, ·. are alternately combined is constituted. The magnets 19, · · · are inserted into the arrangement spaces 40, · · and then attached to the connecting plates 39, 39 by means of screws or the like to be coupled to the adjacent inner yokes 20, ·.

As described above, the linear actuator 15 is provided with the holder 38 having the connecting plates 39, 39 extending in the coupling direction and the inner yokes 20, · · connected to the connecting plates 39, 39 in a state of being separated in the coupling direction, and the magnets 19, · · are inserted between the inner yokes 20, · · adjacent in the coupling direction.

Therefore, the magnets 19, and the magnets are inserted into the arrangement spaces 40, and the holders 38 connected to the connection plates 39, 39 in advance in a state where the inner yokes 20, and are separated from each other, and are connected to the inner yokes 20, and the productivity of the linear actuator 15 can be improved.

In addition, in the case of stacking and joining the alternately-existing magnets 19, · and the inner yokes 20, ·, machining tolerances of the magnets 19, ·andthe inner yokes 20, ·, or positional accuracy regarding respective positions of the magnets 19, · · and may be degraded due to variations in thickness of the adhesive, but in the case of using the holder 38, the inner yokes 20, ·arefixed to the connecting plates 39, 39 in advance, so machining tolerances of the magnets 19, ·cannotbe accumulated.

Therefore, by using the holder 38, the positional accuracy of the magnets 19, · · · can be increased, and a favorable driving state of the linear actuator 15 can be ensured.

Further, by using the holder 38, the connecting plates 39, 39 also function as reinforcing plates for reinforcing the coupling force between the magnets 19, · · and the inner yokes 20, · · and, therefore, a high coupling force between the magnets 19, · · and the inner yokes 20, · · can be secured.

Further, since the holder 38 is connected to the connecting plates 39, 39 in a state where the inner yokes 20, · · are separated, when an external force is applied to the fixing rod 16 or deformation occurs, the force is dispersed to the inner yokes 20, · · · and, thus, high strength of the fixing rod 16 can be secured, and deformation of the fixing rod 16 can be prevented.

In addition, the retainer 38 is not configured to form a connecting hole that penetrates in the coupling direction in the magnets 19, · · and the inner yokes 20, · · and to insert a connecting member into the through hole to connect the magnets 19, · · and the inner yokes 20, · · and, therefore, a large thrust force in the linear actuator 15 can be maintained without causing a reduction in thrust force due to the formation of the through hole.

The 2 nd configuration example is an example in which the nonmagnetic plates 41 and 41 are attached to the fixed rod 16 (fig. 31 and fig. 32).

The nonmagnetic plates 41 and 41 are attached to the opposite side surfaces having the largest area of the fixed rod 16 by bonding or the like, and do not have magnetism, and therefore do not affect the thrust generated by the movable coil 17. The nonmagnetic plate 41 is formed of, for example, a resin material, a metal material such as aluminum or brass, or various materials having no magnetism such as carbon.

In a state where the nonmagnetic plate 41 is attached to the fixing rod 16, the nonmagnetic plate 41 is in a state of straddling the magnets 19, · and the inner yokes 20, ·.

Therefore, the coupling force between the magnets 19, · and the inner yokes 20, · is increased by the nonmagnetic plates 41, and the strength of the fixing lever 16 can be increased without affecting the thrust generated by the linear actuator 15.

Further, by making the non-magnetic plate 41 dark such as black or by attaching an antireflection film or the like to the surface of the non-magnetic plate 41, reflection of light on the non-magnetic plate 41 is suppressed, and it is possible to prevent occurrence of a trouble due to unnecessary reflection of light in the interchangeable lens 1 or the imaging device 100.

The 3 rd configuration example is an example in which the thin film tube 42 is attached to the fixing rod 16 (see fig. 33 to 35).

The film tube 42 is formed in a cylindrical shape from a non-magnetic film-like material, for example, having heat shrinkability (see fig. 33). The film tube 42 may be made of a thin material such as elastic rubber or resin.

The thin film tube 42 is heated in a state of covering the fixing rod 16 from the outer peripheral side, and contracts by the heating, and is brought into close contact with the outer peripheral surface of the fixing rod 16 (see fig. 34). Thus, the fixing rod 16 is sealed by the thin film tube 42 except for both end faces in the coupling direction, and the whole of the magnets 19, · and the inner yokes 20, · are sealed by the thin film tube 42.

By providing the thin film tube 42 for sealing the fixing rod 16 from the outer peripheral side in this way, the coupling force between the magnets 19, · and the inner yokes 20, · becomes high due to the reinforcing effect of the thin film tube 42, and the strength of the fixing rod 16 can be improved without affecting the thrust generated by the linear actuator 15.

The thin film tube 42 is thin and lightweight because it is thin. Therefore, the strength of the fixing rod 16 can be improved without increasing the size and weight of the linear actuator 15 by attaching the thin film tube 42 to the fixing rod 16.

Further, since the film tube 42 is formed of a heat-shrinkable material, and the film tube 42 is heated in a state where the fixing rod 16 is inserted, and the film tube 42 is in close contact with the fixing rod 16 from the outer peripheral side, the fixing rod 16 can be easily sealed in a good close contact state by the film tube 42.

Further, since the film tube 42 is shrunk by heating, there is a possibility that the positions of both ends of the film tube 42 in the axial direction may vary depending on the degree of shrinkage and the length of the film tube 42 in the axial direction before shrinking. If such a deviation occurs, the edges 42a and 42a in the axial direction are located in the vicinity of the boundary between the magnet 19 and the coupling member 21 (see the upper left view of fig. 35), and there is a possibility that a sufficient reinforcing effect of the thin film tube 42 cannot be obtained. On the other hand, if the length of the thin film tube 42 in the axial direction is increased to obtain a sufficient reinforcing effect, the end edges 42a and 42a in the axial direction may protrude outward from the fixing rod 16 (see the upper right view of fig. 35), and the protruding portion of the thin film tube 42 may need to be cut as a subsequent step.

Therefore, it is preferable to have the following structure: inclined surfaces 21c, 21c are formed at both ends of the coupling members 21, 21 in the fixing rod 16 in the coupling direction, the outer shape of which becomes smaller as the ends approach the coupling direction, and both ends of the film tube 42 are brought into close contact with the inclined surfaces 21c, respectively (see the lower drawing of fig. 35).

As described above, the inclined surfaces 21c and 21c are formed in the coupling members 21 and 21, and both end portions of the film tube 42 are brought into close contact with the inclined surfaces 21c and 21c, respectively, so that the film tube 42 is less likely to expand and contract in the coupling direction, and both end portions of the film tube 42 are easily held on the inclined surfaces 21c and 21 c.

Therefore, the end edges 42a, 42a are not located in the vicinity of the boundary between the magnet 19 and the coupling member 21, and the end edges 42a, 42a in the axial direction can be prevented from protruding outward from the fixing rod 16, so that a sufficient reinforcing effect of the thin film tube 42 with respect to the fixing rod 16 can be obtained, and a post-process of cutting a part of the thin film tube 42 can be made unnecessary.

< length of magnet in joining direction >

Next, the length of the magnet 19 in the coupling direction and the like will be described (see fig. 36 to 40).

In the linear actuator 15, the magnets 19, · · · are arranged in the coupling direction and the same poles are coupled to the inner yoke 20, and as the structure of the fixed rod 16, there are a structure in which an odd number of magnets 19 are arranged and a structure in which an even number of magnets 19 are arranged.

In the linear actuator 15 having such a configuration, magnetic fluxes generated in the adjacent magnets 19, 19 of the fixed rod 16 affect each other, and depending on the lengths of the magnets 19, · · · in the coupling direction according to the number of the magnets 19, · · disposed, there is a possibility that a variation in thrust force occurs in the coupling direction.

In the configuration in which an odd number of magnets 19 are disposed on the fixed rod 16, for example, in the configuration in which five magnets 19, · · · are disposed (see fig. 36), when the magnets 19, · · are the same length in the coupling direction (see the upper diagram of fig. 36), the variation in thrust tends to increase in the vicinity of the central magnet 19A and in the vicinity of the magnets 19B, · · located on both sides of the central magnet 19A (see the broken line of fig. 37).

Fig. 37 is a graph showing a variation state of the thrust force according to the position in the coupling direction, and the variation amount of the thrust force in the configuration in which five magnets 19, · · and having the same length are arranged is denoted by V1.

Therefore, in the linear actuator 15, it is preferable to change the lengths of the magnets 19, · · in the bonding direction depending on the position (see the lower diagram of fig. 36). Specifically, it is preferable to increase the length of the magnet 19A in the coupling direction and shorten the lengths of the magnets 19B and 19B in accordance with the increase in the length of the magnet 19A.

In this case, it is preferable that the position of the boundary 19a, · is not changed before and after changing the length of the magnet 19, ·.

In the configuration in which the length of the magnet 19A in the coupling direction is increased and the lengths of the magnets 19B and 19B are shortened in accordance with the increase in the length of the magnet 19A, the variation V2 in the thrust force is smaller than the variation V1 in the thrust force (see the solid line in fig. 37).

In order to reduce the variation of the thrust, for example, the following configuration may be adopted: the length of the magnet 19A and the magnets 19C and 19C in the coupling direction is increased, and the length of the magnets 19B and 19B is shortened by increasing the length of the magnets 19A, 19C and 19C. In this case, it is also preferable that the position of the boundary 19a, · · be not changed before and after changing the length of the magnet 19, ·.

On the other hand, in a configuration in which an even number of magnets 19 are arranged in the fixing rod 16 and the magnets 19, · · have the same length in the coupling direction (see the upper drawing of fig. 38), the variation amount of the thrust may also become large.

Therefore, for example, in a configuration in which four magnets 19, · · are arranged, it is preferable to have the following configuration: the length of the two magnets 19A, 19A positioned at the center in the coupling direction is increased, and the length of the magnets 19B, 19B positioned at both sides is shortened in accordance with the increase in the length of the magnets 19A, 19A in the coupling direction (see the lower diagram of fig. 38).

In this case, it is also preferable that the position of the boundary 19a, · is not changed before and after the length of the magnet 19, ·.

In this way, in the configuration in which the length of the magnets 19A, 19A in the coupling direction is increased and the length of the magnets 19B, 19B is shortened, variation in thrust force can be reduced as compared with the case where the lengths of the magnets 19, · · · in the coupling direction are made the same.

As described above, in the linear actuator 15, the following structure is preferably adopted: the length of at least one magnet 19 in the coupling direction is set to be different from the length of the other magnets 19 in the coupling direction, and the length of each magnet 19 in the coupling direction is determined according to the number of magnets 19 coupled to the inner yoke 20.

With such a configuration, the length of at least one magnet 19 is set to be different from the length of the other magnets 19 depending on the number of magnets 19 to be coupled, so that the magnitude of partial thrust in the coupling direction can be suppressed, the variation amount of the thrust can be reduced, and a smooth operating state of the moving coil 17 can be ensured.

In the fixing lever 16 in which the magnets 19, · · and the inner yokes 20, · · and are alternately coupled, there is a possibility that the thrust force may change abruptly when the sectional area in the direction orthogonal to the coupling direction of the magnet 19 is formed in the same shape in the coupling direction (see fig. 39), for example, when the fixing lever 16 is formed in a rectangular parallelepiped shape or a cylindrical shape (see a thrust force F1 of fig. 39). The thrust F1 is minimum near the boundary 19a of the magnet 19 and maximum near the inner yoke 20.

Therefore, in order to suppress the generation of a rapid variation state of the thrust force, the cross-sectional area of the magnet 19 at the center in the coupling direction is preferably larger than the areas at both ends in the coupling direction (see fig. 40).

With the magnet 19 configured as described above, since the difference in magnetic flux density between the positions in the coupling direction is reduced, the occurrence of a state of rapid variation in thrust in the linear actuator 15 is suppressed (see the thrust F2 in fig. 39), and a smooth operating state of the moving coil 17 can be ensured.

In particular, as shown in fig. 40, it is more preferable that the magnet 19 has a shape whose cross-sectional area decreases as it approaches both ends from the center in the coupling direction.

Since the magnet 19 is formed in such a shape, the sectional area of the magnet 19 changes in the coupling direction, and therefore, the magnet 19 can be made smaller and lighter, and the occurrence of a state of rapid variation in thrust in the linear actuator 15 can be suppressed, and a smooth operating state of the moving coil 17 can be ensured.

< Others >

In the linear actuator 15, the length of the magnet 19 and the inner yoke 20 in the coupling direction can be arbitrarily set according to a required thrust force or the like. Therefore, it is preferable that the respective positions of the coil portions 17a, 17b, 17a, and 17b of the moving coil 17 are set at predetermined positions according to the set lengths of the magnet 19 and the inner yoke 20 in the coupling direction.

For example, it is preferable that the distance S between the coil portions 17a, 17b, 17a, and 17b is made small when the length of the magnet 19 and the inner yoke 20 in the coupling direction is set short (see fig. 41), and the distance S between the coil portions 17a, 17b, 17a, and 17b is made large when the length of the magnet 19 and the inner yoke 20 in the coupling direction is set long (see fig. 42).

By setting the intervals S between the coil portions 17a, 17b, 17a, 17b in accordance with the lengths of the magnet 19 and the inner yoke 20 in the coupling direction in this way, it is possible to obtain a large thrust while suppressing variation in thrust, and to ensure a smooth operating state of the moving coil 17.

In addition, although the magnet 19 is formed in a square tubular shape or a cylindrical shape in the above description, the shape of the magnet 19 is not limited to the square tubular shape or the cylindrical shape, and may be other shapes such as a shape having an elliptical cross-sectional area.

< summary >

As described above, the linear actuator 15, the interchangeable lens 1 including the linear actuator 15, and the imaging device 100 including the linear actuator 15 include: a fixing rod 16 in which magnets 19 are alternately combined with an inner yoke 20 and the same poles of the magnets 19 located at both sides are combined with the inner yoke 20; a tubular movable coil 17 which is penetrated by the fixed rod 16 and is movable in a coupling direction with respect to the fixed rod 16; and an outer yoke 18 that is disposed in a fixed state and covers at least a part of the fixed rod 16 and the movable coil 17 from the outer peripheral side.

Thus, the inner yoke 20 and the fixed rod 16 having the magnet 19 are both arranged in a fixed state, and at least a part of the fixed rod 16 and the movable coil 17 is covered from the outer peripheral side by the outer yoke 18 arranged in a fixed state. Accordingly, since the outer yoke 18, the magnet 19, and the inner yoke 20 are all fixed portions, and the movable coil 17 is a movable portion, and a braking force is not generated between the fixed portions and the movable portion, it is possible to suppress generation of a braking force and generation of leakage magnetic flux at the time of driving, improve driving force, and ensure a stable operating state of the movable body such as the lens 4b and the lens holder 25.

< one embodiment of imaging apparatus >

An example of the configuration of an embodiment of the imaging device according to the present technology is described below (see fig. 43).

The imaging apparatus 100 includes: a camera signal processing unit 91 to which a camera block 90 having an image pickup function is attached and which performs signal processing such as analog-to-digital conversion of an image signal obtained by image pickup; and an image processing unit 92 for performing a recording/reproducing process of the image signal. Further, the imaging apparatus 100 includes: a display unit 93 for displaying the captured image; an R/W (reader/writer) 94 that performs writing and reading of image signals to and from the memory 99; a CPU (Central Processing Unit) 95 that controls the entire image pickup apparatus 100; a lens drive control unit 96 for controlling the drive of the lens disposed in the camera block 90; and operation units 97 and 102 such as various switches for performing desired operations by the user.

The camera block 90 is, for example, the interchangeable lens 1.

The imaging device 100 is provided with imaging elements 98(104) such as a CCD and a CMOS for converting an optical image captured by the camera block 90 into an electric signal.

The camera signal processing unit 91 performs various signal processing such as conversion of an output signal from the image pickup device 98 into a digital signal, noise removal, image quality correction, and conversion into a luminance and color difference signal.

The image processing unit 92 performs compression encoding, decompression decoding, conversion of data specifications such as resolution, and the like of an image signal based on a predetermined image data format.

The display unit 93 has a function of displaying various data such as an operation state of the operation unit 97 by a user and a captured image. Note that the imaging device 100 may not be provided with the display unit 93, and may be configured to display an image by transmitting captured image data to another display device.

The R/W94 writes the image data coded by the image processing unit 92 into the memory 99 and reads the image data recorded in the memory 99.

The CPU95 functions as a control processing unit that controls the circuit blocks provided in the image pickup apparatus 100, and controls the circuit blocks based on an instruction input signal or the like from the operation unit 97.

The lens drive control unit 96 controls a drive source for moving the lens in accordance with a control signal from the CPU 95.

The operation unit 97 outputs an instruction input signal corresponding to an operation performed by the user to the CPU 95.

The memory 99 is, for example, a semiconductor memory that can be attached to and detached from a slot connected to the R/W94 or a semiconductor memory embedded in the image pickup apparatus 100 in advance.

The operation of the imaging apparatus 100 will be described below.

In the standby state for shooting, under control performed by the CPU95, the shot image signal is output to the display section 93 via the camera signal processing section 91 and displayed as a camera through image. When an instruction input signal is input from the operation unit 97, the CPU95 outputs a control signal to the lens drive control unit 96, and the lens is moved under the control of the lens drive control unit 96.

When an image capturing operation is performed by an instruction input signal from the operation unit 97, the captured image signal is output from the camera signal processing unit 91 to the image processing unit 92, and is subjected to compression encoding processing and converted into digital data in a predetermined data format. The converted data is output to R/W94 and written to memory 99.

When reproducing the image data recorded in the memory 99, predetermined image data is read from the memory 99 by the R/W94 in accordance with an operation on the operation unit 97, and after performing decompression decoding processing by the image processing unit 92, the reproduced image signal is output to the display unit 93 to display the reproduced image.

In the present technology, "imaging" means a part or all of a series of processes from a photoelectric conversion process of converting light taken in by the imaging element 98 into an electric signal to a process such as conversion into a digital signal, noise removal, image quality correction, conversion into a luminance and color difference signal, etc., of an output signal from the imaging element 98 by the camera signal processing unit 91, a compression encoding and decompression decoding process of an image signal based on a predetermined image data format by the image processing unit 92, a conversion process of a data specification such as a resolution, etc., and a writing process of the image signal into the memory 99 by the R/W94.

That is, "imaging" may refer to only photoelectric conversion processing for converting light taken in by the imaging element 98 into an electric signal, may refer to processing such as conversion of light taken in by the imaging element 98 into a digital signal, noise removal, image quality correction, and conversion into a luminance and color difference signal with respect to an output signal from the imaging element 98 by the camera signal processing unit 91, or may refer to processing such as conversion into a digital signal, noise removal, image quality correction, and conversion into a luminance and color difference signal with respect to an output signal from the imaging element 98 from photoelectric conversion processing for converting light taken in by the imaging element 98 into an electric signal by the camera signal processing unit 91, to compression encoding and decompression decoding processing of an image signal based on a predetermined image data format by the image processing unit 92, or may refer to processing such as conversion into a digital signal, noise removal, image quality correction, and conversion into a luminance and color difference signal with respect to an output signal from the imaging element 98 by the camera signal processing unit 91, The conversion process of the data standard such as the resolution may be a photoelectric conversion process of converting the light taken in by the image pickup device 98 into an electric signal, a process of converting the output signal from the image pickup device 98 into a digital signal, a process of removing noise, correcting image quality, and converting the output signal into a luminance and color difference signal, which are performed by the camera signal processing section 91, a process of compression-encoding and decompression-decoding an image signal based on a predetermined image data format, and a process of converting the data standard such as the resolution, which are performed by the image processing section 92, or a process of writing the image signal into the memory 99 by the R/W94.

< present technology >

The present technology can be configured as follows.

(1) A linear actuator is provided with:

a fixing rod having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets positioned at both sides being coupled with the inner yoke;

a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and

and an outer yoke which is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

(2) The linear actuator according to the above (1), wherein,

the fixing lever is entirely covered by the outer yoke in the coupling direction.

(3) The linear actuator according to the above (1) or (2), wherein,

the fixing bars are formed in a prism shape,

the movable coil is formed in a square tube shape.

(4) The linear actuator according to the above (1) or (2), wherein,

the fixing rod is formed in a cylindrical shape,

the movable coil is formed in a cylindrical shape.

(5) The linear actuator according to the above (1) or (2), wherein,

the movable coil is provided with a 1 st arc part and a 2 nd arc part which are oppositely arranged,

an outer peripheral surface of the fixed rod facing an inner peripheral surface of the moving coil is formed in a shape similar to the inner peripheral surface.

(6) The linear actuator according to the above (1) or (2), wherein,

the movable coil is provided with an arc portion and a flat portion which are opposed to each other,

the convex direction of the arc portion is set to be a direction away from the plane portion,

an outer peripheral surface of the fixed rod facing an inner peripheral surface of the movable coil is formed in a shape similar to the inner peripheral surface.

(7) The linear actuator according to any one of the above (1) to (6), wherein,

the length of the inner yoke in the coupling direction is set to 5% to 65% of the total length of the magnet and the inner yoke in the coupling direction.

(8) The linear actuator according to any one of the above (1) to (7), wherein,

the length of the inner yoke in the coupling direction is set to 5% to 50% with respect to the total length of the magnet and the inner yoke in the coupling direction.

(9) The linear actuator according to any one of the above (1) to (8), wherein,

the linear actuator is provided with a cage having: a web extending in the bonding direction; and a plurality of inner yokes coupled to the coupling plate in a state of being separated in the coupling direction,

the magnet is inserted between the inner yokes adjacent in the coupling direction.

(10) The linear actuator according to any one of the above (1) to (8), wherein,

the linear actuator is provided with a non-magnetic plate mounted to the fixing rod in a state of spanning the inner yoke and the magnet.

(11) The linear actuator according to any one of the above (1) to (8), wherein,

the linear actuator is provided with a thin film tube sealing the fixing rod from an outer circumferential side.

(12) The linear actuator according to the above (11), wherein,

the film tube is formed of a material having heat shrinkability,

heating the thin film tube in a state where the fixing rod is inserted into the thin film tube.

(13) The linear actuator according to any one of the above (1) to (12), wherein,

the length of at least one of the magnets in the joining direction is set to a length different from the lengths of the other magnets in the joining direction,

the length of the magnet in the coupling direction is determined according to the number of coupling with the inner yoke.

(14) The linear actuator according to any one of the above (1) to (13), wherein,

the magnet is configured such that the cross-sectional area of the center in the coupling direction is larger than the areas of both ends in the coupling direction.

(15) The linear actuator according to the item (14), wherein,

the magnet is formed in a shape such that the cross-sectional area decreases as the magnet approaches both ends from the center in the coupling direction.

(16) A replacement lens includes a movable body movable in an optical axis direction and a linear actuator for moving the movable body in the optical axis direction,

the linear actuator is provided with:

a fixing rod having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets positioned at both sides being coupled with the inner yoke;

a tubular movable coil that is penetrated by the fixed rod and is movable relative to the fixed rod in a coupling direction of the magnet and the inner yoke; and

and an outer yoke which is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

(17) An imaging device includes an imaging element for converting an optical image into an electric signal, a movable body movable in an optical axis direction, and a linear actuator for moving the movable body in the optical axis direction,

the linear actuator is provided with:

a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke;

a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and

and an outer yoke which is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

Claims (17)

1. A linear actuator is provided with:

a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke;

a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and

and an outer yoke which is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

2. The linear actuator of claim 1,

the fixing lever is entirely covered by the outer yoke in the coupling direction.

3. The linear actuator of claim 1,

the fixing bars are formed in a prism shape,

the movable coil is formed in a square tube shape.

4. The linear actuator of claim 1,

the fixing rod is formed in a cylindrical shape,

the movable coil is formed in a cylindrical shape.

5. The linear actuator of claim 1,

the movable coil is provided with a 1 st arc part and a 2 nd arc part which are oppositely arranged,

an outer peripheral surface of the fixed rod facing an inner peripheral surface of the moving coil is formed in a shape similar to the inner peripheral surface.

6. The linear actuator of claim 1,

the movable coil is provided with an arc portion and a flat portion which are opposed to each other,

the convex direction of the arc portion is set to be a direction away from the plane portion,

an outer peripheral surface of the fixed rod facing an inner peripheral surface of the movable coil is formed in a shape similar to the inner peripheral surface.

7. The linear actuator of claim 1,

the length of the inner yoke in the coupling direction is set to 5% to 65% with respect to the total length of the magnet and the inner yoke in the coupling direction.

8. The linear actuator of claim 1,

the length of the inner yoke in the coupling direction is set to 5% to 50% with respect to the total length of the magnet and the inner yoke in the coupling direction.

9. The linear actuator of claim 1,

the linear actuator is provided with a cage having: a web extending in the bonding direction; and a plurality of inner yokes coupled to the coupling plate in a state of being separated in the coupling direction,

the magnet is inserted between the inner yokes adjacent in the coupling direction.

10. The linear actuator of claim 1,

the linear actuator is provided with a non-magnetic plate mounted to the fixing rod in a state of spanning the inner yoke and the magnet.

11. The linear actuator of claim 1,

the linear actuator is provided with a thin film tube sealing the fixing rod from an outer circumferential side.

12. The linear actuator of claim 11,

the film tube is formed of a material having heat shrinkability,

heating the thin film tube in a state where the fixing rod is inserted into the thin film tube.

13. The linear actuator of claim 1,

the length of at least one of the magnets in the joining direction is set to a length different from the lengths of the other magnets in the joining direction,

the length of the magnet in the coupling direction is determined according to the number of couplings with the inner yoke.

14. The linear actuator of claim 1,

the magnet is configured such that the cross-sectional area of the center in the coupling direction is larger than the areas of both ends in the coupling direction.

15. The linear actuator of claim 14,

the magnet is formed in a shape such that the cross-sectional area decreases as the magnet approaches both ends from the center in the coupling direction.

16. A replacement lens includes a movable body movable in an optical axis direction and a linear actuator for moving the movable body in the optical axis direction,

the linear actuator is provided with:

a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke;

a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and

and an outer yoke which is disposed in a fixed state and covers at least a part of the fixed rod and the movable coil from an outer peripheral side.

17. An imaging device includes an imaging element for converting an optical image into an electrical signal, a movable body movable in an optical axis direction, and a linear actuator for moving the movable body in the optical axis direction,

the linear actuator is provided with:

a fixing bar having at least two magnets and at least one inner yoke, the magnets being alternately coupled with the inner yoke, and the same poles of the magnets located at both sides being coupled with the inner yoke;

a cylindrical movable coil that is inserted through the fixed rod and is movable relative to the fixed rod in a direction in which the magnet and the inner yoke are coupled; and

and an outer yoke disposed in a fixed state and covering at least a part of the fixed rod and the movable coil from an outer circumferential side.

Images