JP7655764B2 - Actuator - Google Patents

Description

The present invention relates to an actuator that connects a movable body and a support body by a connection mechanism that includes a viscoelastic body.

Such an actuator is described in Patent Document 1. The actuator in this document includes a support having a cylindrical case, and a movable body housed in the case. The movable body includes a shaft portion that protrudes in the axial direction along the axis of the case. The actuator also includes a connection mechanism that connects the support and the movable body so that they can move relatively in the axial direction, and a magnetic drive mechanism that moves the support and the movable body relatively.

The connection mechanism comprises an annular inner frame member that holds the shaft portion from the outer periphery, an annular outer frame member that is fixed to the case and surrounds the inner frame member from the radially outer side, and a viscoelastic body that connects the inner frame member and the outer frame member. The viscoelastic body is annular and made of silicone gel. The viscoelastic body is connected to the inner frame member and the outer frame member by its own adhesive force. The magnetic drive mechanism comprises a coil fixed to the support and a magnet fixed to the movable body.

Such actuators have vibration characteristics in which the acceleration of the movable body is greatest when the axial resonant frequency at which the movable body vibrates matches the frequency of the drive current passed through the coil. Therefore, in the actuator, the magnetic drive mechanism is driven at a frequency close to the axial resonant frequency to generate vibrations efficiently. The resonant frequency is a value that depends on the weight of the movable body and the spring constant of the viscoelastic body.

JP 2020-195247 A

The actuator of Patent Document 1 has multiple resonant frequencies. The higher-order resonant frequencies are the first-order resonant frequency, which is the axial resonant frequency, and the second-order resonant frequency, which is the radial resonant frequency perpendicular to the vibration direction.

When the device in which the actuator is mounted communicates with an external device, a phenomenon may occur in which noise is carried over the communication if the secondary resonance frequency is within a specific frequency band. In addition, depending on the device in which the actuator is mounted, if the secondary resonance frequency is within a specific frequency band, vibrations due to the secondary resonance frequency may occur, and the axial vibration may not be the desired vibration.

In view of the above problems, the objective of the present invention is to provide an actuator that can shift the resonant frequency in the direction perpendicular to the axial direction to a higher frequency than before while suppressing changes in the resonant frequency in the axial direction, which is the vibration direction.

In order to solve the above problem, the actuator of the present invention comprises a movable body having an axis portion, a support having a case that houses the movable body, a connection mechanism that connects the movable body and the support so as to be movable relatively in an axial direction along the axis of the axis portion, and a magnetic drive mechanism that has a coil fixed to one of the movable body and the support and a magnet fixed to the other, and moves the movable body and the support relatively, wherein the connection mechanism comprises an inner frame member that holds the axis portion from an outer periphery side, an outer frame member that is fixed to the case and surrounds the inner frame member from the radial outside, an intermediate ring positioned between the inner frame member and the outer frame member in the radial direction, and a viscoelastic body that has an inner annular portion positioned between the inner frame member and the intermediate ring and an outer annular portion positioned between the intermediate ring and the outer frame member, and connects the inner frame member and the outer frame member via the intermediate ring.

According to the present invention, the connection mechanism for connecting the movable body and the support includes an intermediate ring between an inner frame member fixed to the movable body and an outer frame member fixed to the support, and a viscoelastic body connecting the inner ring and the outer ring via the intermediate ring. Therefore, when the movable body moves to one side in the radial direction, the inner annular portion of the viscoelastic body expands in the radial direction on one side of the radial direction of the axis, and the outer annular portion of the viscoelastic body is compressed in the radial direction. Also, when the movable body moves to one side in the radial direction, the inner annular portion of the viscoelastic body is compressed on the other side of the radial direction of the axis, and the outer annular portion of the viscoelastic body expands in the radial direction. As a result, the radial spring constant of the viscoelastic body is higher than when the intermediate ring is not provided. Here, the resonance frequency depends on the spring constant of the viscoelastic body. Therefore, in the actuator, the radial resonance frequency is higher. On the other hand, the movement of the movable body vibrating in the axial direction is the movement of the viscoelastic body in the shear direction. Therefore, the axial spring constant of the viscoelastic body does not change significantly compared to when the intermediate ring is not provided between the inner frame member and the outer frame member. This makes it possible to suppress changes in the resonant frequency in the axial direction, which is the vibration direction, while increasing the resonant frequency in the direction perpendicular to the vibration direction compared to conventional methods.

In the present invention, the intermediate ring is cylindrical, the central axis of the intermediate ring coincides with the axis, and a first annular end face on one side of the intermediate ring in the axial direction and a second annular end face on the other side are each exposed in the axial direction from the viscoelastic body. In this way, it is easy to increase the radial spring constant of the viscoelastic body compared to a case where no intermediate ring is provided between the inner frame member and the outer frame member.

In the present invention, the intermediate ring can be made of metal. In this way, it is easier to reduce the thickness of the cylindrical intermediate ring compared to when the intermediate ring is made of resin or the like. Here, by making the cylindrical intermediate ring thin, it is easier to reduce the effect of the intermediate ring placed between the inner frame member and the outer frame member on the axial resonance frequency.

In the present invention, the intermediate ring can be made of resin. This can reduce the manufacturing costs of the intermediate ring.

In the present invention, the viscoelastic body can be a silicone gel.

FIG. 1 is a perspective view of an actuator according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA of FIG. 1. This is a cross-sectional view taken along line B-B of FIG. FIG.

(Overall composition)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view of an actuator 1 according to an embodiment of the present invention. Fig. 2 is an exploded perspective view of the actuator 1 shown in Fig. 1. Figs. 3 and 4 are cross-sectional views of the actuator 1 shown in Fig. 1. Fig. 3 is a cross-sectional view taken at position A-A in Fig. 1. Fig. 4 is a cross-sectional view taken at position B-B in Fig. 1. Fig. 4 is a cross-sectional view taken in a direction perpendicular to Fig. 3. Fig. 5 is a cross-sectional view of a first connection mechanism.

As shown in FIG. 1, the actuator 1 has a cylindrical appearance. As shown in FIG. 3 and FIG. 4, the actuator 1 includes a support 2 having a cylindrical case 5, and a movable body 3 housed in the case 5. As shown in FIG. 2, the movable body 3 includes a support shaft 30 that passes through its center. The axis L of the support shaft 30 coincides with the axis of the case 5. The actuator 1 also includes a first connection mechanism 11 and a second connection mechanism 12 that connect the support 2 and the movable body 3 so as to be relatively movable in the axial direction X along the axis L of the support shaft 30. The first connection mechanism 11 connects the movable body 3 and the support 2 at one end in the axial direction X within the case 5. The second connection mechanism 12 connects the movable body 3 and the support 2 at the other end in the axial direction within the case 5.

The actuator 1 further includes a magnetic drive mechanism 6 that moves the movable body 3 in the axial direction X. The magnetic drive mechanism 6 includes a magnet 61 disposed on the movable body 3 and a coil 62 disposed on the support body 2. In the following description, one side of the axial direction X is referred to as the first direction X1, and the other side of the axial direction X is referred to as the second direction X2.

(First Connection Member and Second Connection Mechanism)
3 and 4 , the first connection mechanism 11 includes an annular first inner frame member 36 that holds the first end portion 30a (shaft portion) in the X1 direction of the support shaft 30 from the outer periphery, and an annular first outer frame member 51 that is fixed to the end portion in the X1 direction of the case 5 radially outside the first inner frame member 36. The outer periphery surface of the first inner frame member 36 is annular. The inner periphery surface of the first outer frame member 51 is annular.

The first connection mechanism 11 also includes a cylindrical intermediate ring 55 disposed between the first inner frame member 36 and the first outer frame member 51 in the radial direction. The intermediate ring 55 can be made of metal such as stainless steel or iron. The intermediate ring 55 can also be made of resin such as polybutylene terephthalate resin. In this example, the intermediate ring 55 is made of iron. The first inner frame member 36, the first outer frame member 51, and the intermediate ring 55 are disposed coaxially, and their central axes coincide with the axis L. The intermediate ring 55 is located in the center portion between the first inner frame member 36 and the first outer frame member 51 in the radial direction.

Furthermore, the first connection mechanism 11 includes a viscoelastic body 10 that connects the first inner frame member 36 and the first outer frame member 51 via the intermediate ring 55. The viscoelastic body 10 has an inner annular portion 10a located between the first inner frame member 36 and the intermediate ring 55, and an outer annular portion 10b located between the intermediate ring 55 and the first outer frame member 51. The viscoelastic body 10 is bonded to the first inner frame member 36, the intermediate ring 55, and the first outer frame member 51 by its own adhesiveness. Here, the first annular end surface 55a in the X1 direction of the intermediate ring 55 and the second annular end surface 55b in the X2 direction are each exposed in the axial direction X from the viscoelastic body 10. That is, the height dimension in the axial direction X of the intermediate ring 55 is the same as the thickness dimension in the axial direction X of the viscoelastic body 10.

The second connection mechanism 12 has a similar configuration to the first connection mechanism 11. That is, as shown in Figs. 2, 3, and 4, the second connection mechanism 12 includes an annular second inner frame member 37 that holds the second end portion 30b (shaft portion) in the X2 direction of the support shaft 30 from the outer circumferential side, and an annular second outer frame member 52 that is fixed to the end portion in the X2 direction of the case 5 on the radial outside of the second inner frame member 37. The second connection mechanism 12 also includes an intermediate ring 55 that is disposed between the second inner frame member 37 and the second outer frame member 52 in the radial direction. Furthermore, the second connection mechanism 12 includes a viscoelastic body 10 that connects the second inner frame member 37 and the second outer frame member 52 via the intermediate ring 55. The viscoelastic body 10 has an inner annular portion 10a that is located between the second inner frame member 37 and the intermediate ring 55, and an outer annular portion 10b that is located between the intermediate ring 55 and the second outer frame member 52. A first annular end face 55a in the X2 direction of the intermediate ring 55 and a second annular end face 55b in the X1 direction are each exposed in the axial direction X from the viscoelastic body 10. The viscoelastic body 10 is bonded to the second inner frame member 37, the intermediate ring 55, and the second outer frame member 52 by its own adhesiveness.

The viscoelastic body 10 may be a gel-like material such as silicone gel, natural rubber, diene rubber (e.g., styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, etc.), non-diene rubber (e.g., butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, urethane rubber, silicone rubber, fluororubber, etc.), thermoplastic elastomer, or any of a variety of rubber materials and modified materials thereof. The viscoelastic body 10 may also be a gel-like material made of silicone gel containing a filler.

(Support)
The support 2 includes a case 5 and a coil holder 4 fixed to the inside of the case 5. As shown in Fig. 2, the case 5 includes a cylindrical tubular member 20, a first cover member 21 that closes an opening of the tubular member 20 in the first direction X1, and a second cover member 22 that closes an opening of the tubular member 20 in the second direction X2. The coil holder 4 is tubular and arranged coaxially with the case 5. The coil holder 4 is located between the first cover member 21 and the second cover member 22 on the inner periphery side of the tubular member 20. As shown in Figs. 3 and 4, the coil holder 4 holds the coil 62 and also holds the first outer frame member 51 of the first connection mechanism 11.

The support body 2 also includes an annular connection member holding portion 25 that protrudes from the inner peripheral surface of the tubular member 20. The connection member holding portion 25 is located between the coil holder 4 and the second cover member 22 in the axial direction X. The connection member holding portion 25 holds the second outer frame member 52 of the second connection mechanism 12.

(Cylindrical member, first cover member, and second cover member)
The cylindrical member 20 is made of resin. As shown in FIG. 2, the cylindrical member 20 has a notch portion 65 formed by cutting an edge in the first direction X1 in the second direction X2. The cylindrical member 20 also has locking protrusions 91 protruding inward at three circumferential positions on the edge in the first direction X1 and three circumferential positions on the edge in the second direction X2. The cylindrical member 20 also has a board holding portion 69 in the second direction X2 of the notch portion 65. A wiring board 7 is fixed to the board holding portion 69. A power supply lead wire 8 is electrically connected to the wiring board 7. A lead wire holding portion 70 for holding the lead wire 8 is provided at a position adjacent to the wiring board 7 in the circumferential direction. The lead wire 8 is connected to the coil 62 via the wiring board 7.

The first cover member 21 is made of resin. The first cover member 21 includes a circular first end plate portion 211 and an annular first side plate portion 212 extending in the second direction X2 from the outer periphery of the first end plate portion 211. The first end plate portion 211 includes an annular rib 213 protruding in the second direction X2 on the inner periphery side of the first side plate portion 212. The rib 213 is coaxial with the first side plate portion 212. A plurality of protrusions 214 protruding in the second direction X2 are provided at equal angular intervals on the end surface of the rib 213 in the second direction. In this example, three protrusions 214 are provided. A cover portion 66 protruding in the second direction X2 is provided at a part of the circumference of the first side plate portion 212. In addition, locking portions 81 are provided at three locations in the circumference of the first side plate portion 212. Each locking portion 81 is a claw that extends at an angle from the X2 edge of the first side plate portion 212 in the X1 direction, widening outward toward the outer periphery.

As shown in FIG. 1, the first cover member 21 is inserted into the tubular member 20 from the first direction X1 side and fixed to the end portion of the tubular member 20 in the first direction X1. When the first cover member 21 is inserted into the tubular member 20 from the first direction X1 side, the cover portion 66 is inserted into the notch portion 65 from the first direction X1 side. When the cover portion 66 is inserted into the notch portion 65, a gap is formed between the end edge of the cover portion 66 in the second direction X2 and the notch portion 65, which is the wiring pull-out portion 60 for pulling the coil wire 63 of the coil 62 to the outside of the case 5. When the first cover member 21 is inserted into the tubular member 20 from the first direction X1 side, each locking portion 81 is elastically deformed in the radial direction and is pushed into the inner periphery of the tubular member 20 together with the first side plate portion 212. Here, the X1-direction ends of each locking portion 81 abut against the locking projections 91 provided on the X1-direction edge of the tubular member 20 from the X1-direction side. This prevents the first lid member 21 from falling off the tubular member 20 in the X1 direction. The first lid member 21 is fixed to the tubular member 20 by adhesive with each locking projection 91 abutting against each locking portion 81.

The second cover member 22 is made of resin. The second cover member 22 has a circular second end plate portion 221 and an annular second side plate portion 222 extending in the first direction X1 from the outer periphery of the second end plate portion 221. As shown in Figs. 3 and 4, the second cover member 22 has an annular rib 223 on the second end plate portion 221. The rib 223 is coaxial with the second side plate portion 222 and protrudes in the first direction X1. Three protrusions 224 protruding in the first direction X1 are provided at equal angular intervals on the end surface of the rib 223 in the second direction. In addition, locking portions 81 are provided at three locations in the circumferential direction of the second side plate portion 222. Each locking portion 81 is a claw that extends from the X1-direction edge of the second side plate portion 222 in the X2 direction at an angle in a direction expanding toward the outer periphery.

The second cover member 22 is inserted into the tubular member 20 from the second direction X2 side and fixed to the end portion of the tubular member 20 in the second direction X2. When the second cover member 22 is inserted into the tubular member 20 from the second direction X2 side, each locking portion 81 is elastically deformed in the radial direction and is pushed into the inner periphery of the tubular member 20 together with the second side plate portion 222. Here, the locking protrusions 91 provided on the end edge of the tubular member 20 in the X2 direction abut against the X2 end of each locking portion 81 from the X2 direction side. This prevents the second cover member 22 from falling off from the tubular member 20 in the X1 direction. The second cover member 22 is fixed to the tubular member 20 by adhesive with each locking protrusion 91 abutting against each locking portion 81.

(coil holder)
2, the coil holder 4 includes a coil holding portion 40 that holds the coil 62, and a connection member holding portion 41 that holds the first outer frame member 51 of the first connection mechanism 11 in the first direction X1 of the coil holding portion 40. As shown in Figures 3 and 4, the coil 62 held by the coil holding portion 40 is located at the center of the case 5 in the axial direction X.

The connection member holding portion 41 is annular. The inner peripheral surface of the connection member holding portion 41 is provided with a first annular recess 43 cut out from the first direction X1 and inner peripheral side. A first step 44 is provided at the end portion of the first recess 43 in the second direction X2. The first outer frame member 51 of the first connection mechanism 11 is pressed into the first recess 43 from the first direction X1 side. During the press-fitting, the first step 44 abuts against the first outer frame member 51 from the second direction X2 side, positioning the first outer frame member 51 in the axial direction X. As a result, the coil holder 4 holds the first outer frame member 51 of the first connection mechanism 11 from the outer peripheral side and the second direction X2 side.

As shown in Figures 2 and 3, two terminal pins 64 protrude outward from the outer circumferential surface of the connection member holding portion 41. Ends of a coil wire 63 drawn from a coil 62 are wound around the two terminal pins 64. When the coil holder 4 is fixed to the case 5, the two terminal pins 64 protrude outward from the case 5 via the wiring draw-out portion 60. Here, as shown in Figures 1, 2, and 3, the two terminal pins 64 protruding outward from the case 5 pass through two holes 71 provided in the wiring board 7 and are electrically connected to lands provided on the edges of the holes 71. This electrically connects the coil wire 63 to the power supply lead wire 8.

As shown in Figures 3 and 4, when the first lid member 21 is fixed to the tubular member 20, the protrusion 214 of the first lid member 21 abuts against the first outer frame member 51 from the first direction X1 side. In other words, the protrusion 214 of the first lid member 21 is an abutting portion that abuts against the first outer frame member 51 from the first direction X1 side. When the first lid member 21 is fixed to the tubular member 20, the first lid member 21 prevents the first outer frame member 51 from moving in the first direction X1. In addition, the first lid member 21 prevents the viscoelastic body 10 of the first connection mechanism 11 from being exposed to the outside.

(Connection member holding portion)
The connection member holding portion 25 is located in the second direction X2 of the coil holder 4. The connection member holding portion 25 is annular. An annular second recess 46 is provided on the inner peripheral surface of the connection member holding portion 25, which is cut out from the second direction X2 and inner peripheral side. A second step portion 45 is provided at an end portion of the second recess 46 in the first direction X1. The second outer frame member 52 of the second connection mechanism 12 is press-fitted into the second recess 46 from the second direction X2 side. During the press-fitting, the second step portion 45 abuts against the second outer frame member 52 from the first direction X1 side, and positions the second outer frame member 52 in the axial direction X. As a result, the connection member holding portion 25 holds the second outer frame member 52 of the second connection mechanism 12 from the outer peripheral side and the first direction X1 side.

Here, when the second lid member 22 is fixed to the tubular member 20, the protrusion 214 of the second lid member 22 abuts against the second outer frame member 52 from the second direction X2 side. That is, the protrusion 214 of the second lid member 22 is an abutment portion that abuts against the second outer frame member 52 from the second direction X2 side. When the second lid member 22 is fixed to the tubular member 20, the second lid member 22 prevents the second outer frame member 52 from moving in the second direction X2. In addition, the second lid member 22 prevents the viscoelastic body 10 of the second connection mechanism 12 from being exposed to the outside.

(Movable body)
2 to 4, the movable body 3 has a support shaft 30 that extends in the axial direction X at the radial center of the support body 2. The support shaft 30 is a metal round bar. The axis of the support shaft 30 is the axis of the movable body 3 and coincides with the axis L of the case 5. A magnet 61 is supported by the support shaft 30. The magnet 61 has an axial hole 610 in its center, through which the support shaft 30 passes.

The support shaft 30 also supports a yoke 35. The yoke 35 includes a first yoke 31 that overlaps with the magnet 61 in a first direction X1 of the axial direction X, and a second yoke 32 that overlaps with the magnet 61 in a second direction X2.

The first yoke 31 is disk-shaped with a predetermined thickness. The first yoke 31 has an axial hole 310 in the center through which the support shaft 30 passes. The first yoke 31 is fixed to the surface of the magnet 61 in the first direction X1 by a method such as gluing. Here, the outer diameter dimension of the first yoke 31 is larger than the outer diameter dimension of the magnet 61. Therefore, the outer peripheral surface of the first yoke 31 protrudes radially outward beyond the outer peripheral surface of the magnet 61.

The second yoke 32 is composed of two members, a cup-shaped first magnetic member 33 and a disk-shaped second magnetic member 34. The first magnetic member 33 includes a circular end plate portion 331 having an axial hole 330 through which the support shaft 30 penetrates at its center, a bent portion 332 bent in the first direction X1 from the outer edge of the end plate portion 331, and a cylindrical portion 333 extending in the first direction X1 from the bent portion 332. The end plate portion 331 of the first magnetic member 33 is fixed to an end surface of the magnet 61 in the second direction X2. The second magnetic member 34 has an axial hole 340 through which the support shaft 30 penetrates at its center. The second magnetic member 34 is fixed to the end plate portion 331 of the first magnetic member 33 from the side opposite to the magnet 61. As shown in FIG. 2, the second magnetic member 34 has a plurality of through holes penetrating in the axial direction X on the outer periphery side of the axial hole 340. Each through hole is a weight adjustment portion 38 for adjusting the weight of the movable body 3.

Here, as shown in Figures 3 and 4, the first inner frame member 36 of the first connection mechanism 11 is fixed to the first end portion 30a of the support shaft 30 located in the first direction X1 of the first yoke 31. More specifically, an annular protrusion 361 that protrudes radially inward is provided on the inner peripheral surface of the first inner frame member 36 at the end in the second direction X2, and the first end portion 30a is press-fitted into the center hole of the annular protrusion 361. In this way, the first inner frame member 36 is fixed to the support shaft 30.

The second inner frame member 37 of the second connection mechanism 12 is fixed to the second end portion 30b of the support shaft 30 located in the second direction X2 of the second yoke 32. More specifically, an annular protrusion 371 that protrudes radially inward is provided on the inner peripheral surface of the second inner frame member 37 at the end in the first direction X1, and the second end portion 30b is press-fitted into the center hole of the annular protrusion 371. This fixes the second inner frame member 37 to the support shaft 30.

When the first inner frame member 36 and the second inner frame member 37 are fixed to the support shaft 30, the first inner frame member 36 abuts against the first yoke 31 from the side in the first direction X1. The second inner frame member 37 abuts against the second magnetic member 34 from the side in the second direction X2. Therefore, the magnet 61 and the yoke 35 supported by the support shaft 30 are fixed to the support shaft 30 from both sides in the axial direction X by the first inner frame member 36 and the second inner frame member 37.

When the magnet 61 and the yoke 35 are fixed to the support shaft 30, the magnet 61 and the yoke 35 are located at the center of the support shaft 30 in the axial direction X. The cylindrical portion 333 of the second yoke 32 is located radially outwardly of the outer circumferential surface of the magnet 61 and the first yoke 31 at a position spaced radially outwardly from the outer circumferential surface of the magnet 61 and the outer circumferential surface of the first yoke 31. Here, when the support body 2 and the movable body 3 are connected via the first connection mechanism 11 and the second connection mechanism, a part of the coil 62 of the movable body 3 is located between the cylindrical portion 333 of the second yoke 32 and the outer circumferential surface of the magnet 61. A part of the coil 62 of the movable body 3 is located between the cylindrical portion 333 of the second yoke 32 and the outer circumferential surface of the first yoke 31.

(Actuator Operation)
In the actuator 1, when electricity is applied to the coil 62, the magnetic drive mechanism 6 exerts a driving force that moves the movable body 3 in the axial direction X. When electricity is cut off from the coil 62, the movable body 3 returns to the origin position due to the return force of the viscoelastic body 10. Therefore, when a driving current (AC current) of a predetermined frequency is applied to the coil 62, the movable body 3 vibrates in the axial direction X. In addition, by adjusting the waveform of the driving current applied to the coil 62, the acceleration at which the movable body 3 moves in the X1 direction can be made different from the acceleration at which the movable body 3 moves in the X2 direction. Therefore, a person holding an instrument to which the actuator 1 is attached as a haptic device can feel a vibration having a directional property in the axial direction X.

(Regarding the actuator's resonant frequency)
The actuator 1 of this embodiment has a vibration characteristic in which the acceleration of the movable body 3 is greatest when the resonant frequency in the axial direction X at which the movable body 3 vibrates coincides with the frequency of the drive current passed through the coil 62. Therefore, in the actuator 1, the magnetic drive mechanism is driven at a frequency close to the resonant frequency in the axial direction X to efficiently generate vibrations. The resonant frequency is a value that depends on the weight of the movable body 3 and the spring constant of the viscoelastic body.

The actuator 1 of this embodiment has a plurality of resonant frequencies. The higher-order resonant frequencies are a first-order resonant frequency, which is a resonant frequency in the axial direction X, and a second-order resonant frequency, which is a resonant frequency in the radial direction perpendicular to the vibration direction. To vibrate the actuator 1 in the axial direction X, the magnetic drive mechanism is driven at a frequency close to the first-order resonant frequency.

When the device in which the actuator 1 is mounted communicates with an external device, a phenomenon may occur in which noise is carried over the communication if the secondary resonance frequency is within a specific frequency band. In addition, depending on the device in which the actuator 1 is mounted, if the secondary resonance frequency is within a specific frequency band, vibrations due to the secondary resonance frequency may occur, and the vibration in the axial direction X may not be the desired vibration.

In contrast, in this example, the first connection mechanism 11 that connects the movable body 3 and the support includes an intermediate ring 55 between the first inner frame member 36 fixed to the movable body 3 and the first outer frame member 51 fixed to the support 2. The first connection mechanism 11 also includes an inner annular portion 10a located between the first inner frame member 36 and the intermediate ring 55 and an outer annular portion 10b located between the intermediate ring 55 and the first outer frame member 51, and includes a viscoelastic body 10 that connects the first inner frame member 36 and the first outer frame member 51 via the intermediate ring 55.

Therefore, when the movable body 3 moves to one side in the radial direction, the inner annular portion 10a of the viscoelastic body 10 expands in the radial direction on one side of the radial direction of the axis, and the outer annular portion of the viscoelastic body 10 is compressed in the radial direction. Also, when the movable body 3 moves to one side in the radial direction, the inner annular portion 10a of the viscoelastic body 10 is compressed on the other side of the radial direction of the axis, and the outer annular portion of the viscoelastic body 10 expands in the radial direction. As a result, the radial spring constant of the viscoelastic body 10 is higher than when the intermediate ring 55 is not provided. Here, the resonance frequency depends on the spring constant of the viscoelastic body 10. Therefore, in the actuator 1, the radial resonance frequency is higher. On the other hand, the movement of the movable body 3 vibrating in the axial direction X is the movement in the shear direction of the viscoelastic body 10. Therefore, the spring constant of the axial direction X of the viscoelastic body 10 does not change significantly compared to when the intermediate ring 55 is not provided between the first inner frame member 36 and the first outer frame member 51. Therefore, while suppressing changes in the resonant frequency in the axial direction X, which is the vibration direction, the resonant frequency in the radial direction perpendicular to the vibration direction can be made higher than before.

Figure 5 is a table showing the resonance frequency of the actuator 1 when the first connection mechanism 11 includes the intermediate ring 55 and when the first connection mechanism 11 does not include the intermediate ring 55. The resonance frequency shown in Figure 5 was calculated by simulation. As shown in the first and second rows of Figure 5, when the first connection mechanism 11 includes the intermediate ring 55, the primary resonance frequency is around 63.5 Hz, regardless of whether the intermediate ring 55 is made of resin or iron. The secondary resonance frequency is 122 Hz. On the other hand, in a conventional configuration in which the first connection mechanism 11 does not include the intermediate ring 55 and the first inner frame member 36 and the first outer frame member 51 are connected only by the viscoelastic body 10, the primary resonance frequency is 58.4 Hz. The secondary resonance frequency is 105 Hz.

According to the results of the simulation shown in FIG. 5, when the first connection mechanism 11 includes the intermediate ring 55, the first resonance frequency changes by 5 Hz, while the second resonance frequency changes by 17 Hz, compared to when the first connection mechanism 11 does not include the intermediate ring 55. Therefore, according to this example, compared to when the first connection mechanism 11 does not include the intermediate ring 55, it is possible to move the resonance frequency in the direction perpendicular to the axial direction X to a higher frequency than before while suppressing the change in the resonance frequency in the axial direction X, which is the vibration direction. Therefore, it is possible to move the second resonance frequency outside a specific frequency band without changing the frequency at which the magnetic drive mechanism is driven. This makes it possible to prevent or suppress the occurrence of phenomena such as noise being carried over to communication and vibration in the axial direction X not being the desired vibration.

(Modification)
In the present invention, the intermediate ring 55 may be made of resin, which can reduce the manufacturing cost of the intermediate ring 55.

In addition, the magnetic drive mechanism 6 can hold a magnet 61 on the support 2 side and a coil 62 on the movable body 3 side.

1...actuator, 2...support, 3...movable body, 4...coil holder, 5...case, 6...magnetic drive mechanism, 7...wiring board, 8...lead wire, 10...viscoelastic body, 10a...inner annular portion, 10b...outer annular portion, 11...first connection mechanism, 12...second connection mechanism, 20...tubular member, 21...first cover member, 22...second cover member, 25...connection member holding portion, 30...support shaft, 30a...first end portion, 30b...second end portion, 31...first yoke, 32...second yoke, 33...first magnetic member, 34...second magnetic member, 35...yoke, 36...first inner frame member, 37...second inner frame member, 38...weight adjustment portion, 40...coil holding portion, 41...connection member holding portion, 43...first recess, 44...first step portion, 45...second step portion, 46...second recess, 51 ...first outer frame member, 52...first outer frame member, 52...second outer frame member, 55...intermediate ring, 55a...first annular end face, 55b...second annular end face, 60...wiring pull-out portion, 61...magnet, 62...coil, 63...coil wire, 64...terminal pin, 65...notch portion, 66...cover portion, 69...board holding portion, 70...lead wire holding portion, 71...hole, 81...locking portion, 9 1... locking protrusion, 211... first end plate portion, 212... first side plate portion, 213... rib, 214... protrusion, 221... second end plate portion, 222... second side plate portion, 223... rib, 224... protrusion, 310... shaft hole, 330... shaft hole, 331... end plate portion, 332... bent portion, 333... cylindrical portion, 340... shaft hole, 361... annular protrusion, 371... annular protrusion, 610... shaft hole, X... axial direction

Claims (4)

A movable body having a shaft portion;
A support body having a case that houses the movable body;
a connection mechanism that connects the movable body and the support body so as to be relatively movable in an axial direction along the axis of the shaft portion;
a magnetic drive mechanism including a coil fixed to one of the movable body and the support and a magnet fixed to the other of the movable body and the support, for moving the movable body and the support relatively;
the connection mechanism comprises an inner frame member that holds the shaft portion from an outer periphery side, an outer frame member that is fixed to the case and surrounds the inner frame member from the radial outside, an intermediate ring positioned between the inner frame member and the outer frame member in the radial direction, and a viscoelastic body that has an inner annular portion positioned between the inner frame member and the intermediate ring and an outer annular portion positioned between the intermediate ring and the outer frame member, and connects the inner frame member and the outer frame member via the intermediate ring ,
The intermediate ring is cylindrical;
The central axis of the intermediate ring coincides with the axis;
a first annular end surface on one side of the intermediate ring in the axial direction and a second annular end surface on the other side of the intermediate ring are exposed in the axial direction from the viscoelastic body,
The actuator, wherein the inner annular portion and the outer annular portion are provided separately . The actuator according to claim 1, characterized in that the intermediate ring is made of metal. The actuator according to claim 1, characterized in that the intermediate ring is made of resin. 4. The actuator according to claim 1 , wherein the viscoelastic body is a silicone gel.

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