The present invention contains subject matter related to Japanese Patent Application No. 2004-343116 filed in the Japanese Patent Office on Nov. 26, 2004, Japanese Patent Application No. 2004-343143 filed in the Japanese Patent Office on Nov. 26, 2004, and Japanese Patent Application No. 2004-343144 filed in the Japanese Patent Office on Nov. 26, 2004, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to the structure of a vibration wave motor.
2. Description of the Related Art
In general, a vibration wave motor used for a driving unit includes a transducer (vibration body) having an energy transducer, such as a piezoelectric device, and a contact body in contact with the transducer. The vibration wave motor transduces kinetic energy caused by traveling waves or standing waves to a relative movement between the transducer and the contact body using a frictional force. In such a structure, the output of the vibration wave motor is significantly influenced by the friction on an interface between the transducer and the contact body and by the number of the transducers. Accordingly, a variety of ultrasonic motors having various contact mechanisms of transducers are proposed.
For example, Japanese Unexamined Patent Application Publication No. 11-235062 discloses such a vibration actuator device (vibration wave motor). This vibration actuator device includes a transducer that vibrates in accordance with a driving signal, a ring-shaped relative movement member in contact with the transducer to relatively move, and a pressure support member that supports the transducer and applies pressure to the transducer so as to be in contact with the relative movement member. The pressure support member includes a ring-shaped base portion, a leaf spring supported by the base portion in a cantilever fashion, and a support portion provided at a free end of the leaf spring.
A vibration actuator (transducer) disclosed in Japanese Unexamined Patent Application Publication No. 7-104166 or U.S. Pat. No. 6,078,438 generates a longitudinal vibration and a bending vibration and is in contact with a rotor to cause the rotor to perform a relative movement. The vibration actuator receives an urging force from a cantilevered leaf spring to press against the rotor.
An ultrasonic motor (vibration wave motor) disclosed in Japanese Unexamined Patent Application Publication No. 10-215588 primarily includes a stationary member, a driven member, and a transducer. The transducer is rotatably supported by the stationary member about a rotation axis. A sliding member of the transducer is urged against the driven member. While pressing against the driven member, the transducer is excited to generate ultrasonic vibration so that the driven member moves forward and backward. A pressing strength of the transducer against the driven member is obtained by urging of a leaf spring. The pressing strength is adjusted by a pressure adjusting screw provided on the top end of the leaf spring serving as a pressing strength adjustment mechanism.
According to an embodiment of the present invention, a vibration wave motor includes a rotor comprising a rotating member, at least one transducer having a node of vibration, a pair of loops at both sides of the node to generate an elliptical vibration and to be in contact with the rotor, a shaft member mounted perpendicular to the transducer at the node of vibration, a stator having grooves extending in a direction of rotation axis of the rotor in which the shaft member fits rollably and movably forward and backward in the direction of rotation axis to support the transducer, and a resilient plate member for urging the rotor in the direction of rotation axis to press the loops of the transducer against the rotor.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
Exemplary embodiments of the present invention are described with reference to the accompanying drawings.
In the following description, a rotation axis O of the vibration wave motor coincides with an optical axis O of a photographing lens when the vibration wave motor is applied to a lens barrel, which is described below. However, depending on the structure of the lens barrel, the rotation axis O of the vibration wave motor substantially coincides with the optical axis O of the photographing lens. A direction parallel to the optical axis O is referred to as the Q direction. In the Q direction, a position adjacent to a lens in the lens barrel is referred to as “front” whereas a position adjacent to a lens mount in the lens barrel is referred to as “rear”. A radial direction about the rotation axis O is referred to as the R direction. Also, a tangential direction to a circumference of a circle having the rotation axis O is referred to as the T direction.
According to this embodiment, the vibration wave motor 1, for example, is a rotary motor that can be applied to a lens barrel of a digital camera as a lens driving actuator unit. The lens barrel of a digital camera, which is one of electronic apparatuses, will be described below with reference to
The vibration wave motor 1 employs an ultrasonic range as the frequency range of vibration waves. Therefore, the vibration wave motor 1 is a so-called ultrasonic motor.
As shown in
In the case where the vibration wave motor 1 is assembled in a lens barrel 60 shown in
Each component of the vibration wave motor 1 is described in detail with reference to FIGS. 1 to 16.
The housing 2 is a ring-shaped support member. As shown in
As shown in
The rotor plate 6 is formed from a wear-resistant and high-hardness ceramic plate material (e.g., zirconia). The rotor plate 6 is in contact with a transducer 35 (more specifically, a driving element 38 shown in
The ring-shaped spacer 7 is formed from a vibration-resistant resilient plate material (e.g., elastomer or felt). On a surface of the ring-shaped spacer 7, a double-faced adhesive tape is attached. The ring-shaped spacer 7 is brought into tight contact with the rotor plate 6 and the rotor body 4 so that the ring-shaped spacer 7 is bonded and fixed to the rotor plate 6 and the rotor body 4. The double-faced adhesive tape is also formed from a vibration-resistant resilient plate material. Consequently, the double-faced adhesive tape may function as the ring-shaped spacer 7 by itself.
The ring-shaped spacer 7 is a member to insulate the vibration of the transducer 35. In addition, the spacer 7 serves as a second pressing strength adjustment means (a pressing strength adjustment mechanism). That is, by selecting a thickness of the spacer 7, the contact force between the two transducers 35 and the rotor plate 6 can be adjusted so as to obtain an appropriate frictional contact force therebetween. Also, the contact force between the roller 22 and the rotor plate 6 can be adjusted so as to obtain an appropriate frictional contact force therebetween. Since the ring-shaped spacer 7 is in tight contact with the rotor body 4, the double-faced adhesive tape can be eliminated if the frictional force caused by the contact is sufficiently higher than the driving force output from the vibration wave motor 1.
The rotor body 4 is formed from a wear-resistant and high-hardness plate material. On the surface of the rotor body 4 on the front side (adjacent to the bearing member 8), a V groove 4b is formed in which balls 9 roll along the circumference of the rotor body 4. Additionally, a protrusion 4a for connection is formed on the inner peripheral surface of the rotor body 4 while extending towards the center of the ring. Furthermore, on the outer peripheral surface of the rotor body 4, a magnetic sheet 5 (see
As shown in
In this embodiment, the rotor 3 includes three members. However, the present invention can be applied to a rotor integrated as a single resin ring member.
As shown in
The bearing holder 11 is a ring-shaped member. The bearing holder 11 is formed from a wear-resistant and high-hardness plate material. As shown in
As shown in
It should be noted that the bearing holder 11 and the retainer 10 may be formed from a resin molding member.
As shown in
The amplitude direction of bending standing wave vibration of the transducer unit 15 (hereinafter referred to as the “q direction”) is substantially perpendicular to the amplitude direction of longitudinal vibration of the transducer unit 15 (hereinafter referred to as “t direction”). In the vibration wave motor 1 with the transducer unit 15 assembled, the amplitude direction of bending standing wave vibration is substantially parallel to the rotation axis O (the Q direction), and the amplitude direction of longitudinal vibration is substantially parallel to a direction of tangent which touches a circumference of a circle whose center is the rotation axis O (the T direction).
As shown in
The piezoelectric sheets are laminated in a direction (r direction) perpendicular to the amplitude direction of the bending standing wave vibration and the amplitude direction of the longitudinal vibration. In the vibration wave motor 2 with the transducer unit 15 assembled, the direction of laminating the piezoelectric sheets is the same as the radial direction (R direction) with respect to the rotation axis O.
The structure and operation of the transducer 35 will be described in detail below with reference to FIGS. 17 to 24.
As shown in
The line N of the vibration node neither vibrates in the amplitude direction (q direction) of the bending standing wave vibration nor vibrates in the amplitude direction (t direction) of the longitudinal vibration.
In the vibration wave motor 1 with the transducer unit 15 assembled, the round support shafts 17 are disposed along the R direction, and the end surface 16a is disposed in a plane defined by the R and T directions (a plane orthogonal to the Q direction).
As shown in
In the transducer unit 15 assembled in the housing 2, if a gap S (see
In the transducer 35 disposed as described above, since the direction of the round support shafts 17 is orthogonal to the rotational direction of the rotor 3, the rotation of the rotor 3 is not disturbed by the transducer 35.
As shown in
The two ends of each of the two leaf springs 18 are attached to a front surface 25a of one of the two presser plates 25 with a setscrew 19 and a supporting shoulder screw 20. More specifically, as shown in
The presser plate 25 on which the leaf spring 18 is attached is fixed to the rear surface of the housing 2 (the surface opposed to the rotor 3) with screws. By fixing the presser plates 25 to the housing 2, the leaf spring 18 is attached, as shown in
As stated above, the oval stepped portion 18d of the leaf spring 18 is in contact with the end surface 16a of the transducer holder 16 to press against the transducer holder 16. Accordingly, the leaf spring 18 deforms, and one end of the leaf spring 18 slides on the shoulder screw 20 along the slot 18c so as to resiliently deform. A pressing strength caused by the resilient deformation presses against the transducer holder 16 and displaces the transducer holder 16 in the Q direction by substantially translating the transducer holder 16. At that time, since the leaf spring 18 deforms and extends in the T direction, the position of the oval stepped portion 18d is slightly displaced by a distance δ1. It is desirable that the oval stepped portion 18d is in contact with the middle portion of the end surface 16a in the T direction at a position determined while considering the displacement δ1. However, since it is determined that the oval stepped portion 18d is in contact with the middle portion of the end surface 16a in the amplitude direction of the longitudinal vibration of the transducer 35 (t direction) at substantially the same position as that of the node line N of the transducer 35, a stable pressing strength can be obtained even when the position is slightly shifted.
As shown in
The state of the leaf spring 18 pressing against the transducer 35 via the transducer holder 16 is described next. From the viewpoint of an assembly stage, namely, in a static pressing state, the precision of the surface of the rotor plate 6, which is in contact with the driving element 38 of the transducer 35, with respect to the presser plates 25, to which the leaf spring 18 is attached, may be low. In particular, the degree of parallelization in the direction orthogonal to the Q direction (i.e., T direction) may be low. In such a case, if the contact surface of the pressing leaf spring with the transducer is a flat surface without any protrusion, the flat surface portion of the leaf spring is inevitably in contact with one side of the contact surface of the transducer (one side of the surface 16a of the transducer holder). In this contact state, the pressing force of the leaf spring does not evenly act on the two driving elements 38. However, as shown in
On the other hand, in a pressing state when the leaf spring 18 drives the transducer, namely, in a dynamic pressing state, if the flat surface portion of the leaf spring 18 presses against the transducer, the edge of the transducer holder 16 may be in contact with the flat surface portion of the leaf spring 18, and therefore, the stable contact therebetween could not be obtained. However, in the vibration wave motor 1 according to this embodiment, the oval stepped portion 18d of the leaf spring 18 presses against the surface 16a of the transducer holder 16, as described above. Accordingly, the pressing state remains unchanged even when the transducer vibrates. Thus, the stable output can be obtained.
When the vibration wave motor 1 is driven, the transducer 35 pressed by the leaf spring 18 generates a vibration by composition of the bending standing wave vibration with longitudinal vibration, as shown in
In the above-described example, the oval stepped portion 18d of the leaf spring 18 presses against the end surface 16a of the transducer holder 16 in the Q direction. However, a structure different from that of the leaf spring 18 can be applied. For example, the leaf spring 23, which is used to press against the roller 22 shown in
As shown in
As shown in
Like the leaf spring 18, two ends of the leaf spring 23 are attached to a front surface 25a of the presser plate 25 with a setscrew 19 and a supporting shoulder screw 20. That is, the first end of the leaf spring 23 is fixed to the presser plates 25 by the setscrew 19 passing through the circular hole 23b. On the other hand, the second end of the leaf spring 23 is supported by the shoulder screw 20 passing through the slot 23c so that the second end can slide on the presser plates 25 in the T direction. The presser plates 25 on which the leaf spring 23 is attached are fixed to the rear surface of the housing 2 with screws.
The protrusion 23e of the attached leaf spring 23 is inserted into the insertion opening 2a of the housing 2 and the recess parts 23f press against the support shaft 22a of the roller 22 disposed in the housing 2 so that the roller 22 presses against the rotor plate 6 at a predetermined pressing strength (see
As described above, the three presser plates 25 are attached to the rear surface of the housing 2 with screws. Between the housing 2 and the three presser plates 25, an adjustment washer 26 serving as a spacing member, which is first pressing strength adjustment means (a pressing strength adjustment mechanism) having an appropriate thickness, is inserted as needed. By using the adjustment washer 26, the pressing strength of the two leaf springs 18 against the two transducers 35 can be independently and precisely adjusted. Also, the pressing strength of the leaf spring 23 against the roller 22 can be fine adjusted.
According to this embodiment, the vibration wave motor 1 can provide two types of pressing strength adjustment means of the leaf springs 18 and 23 against the transducer 35 and the roller 22: first pressing strength adjustment means and second pressing strength adjustment means.
The first pressing strength adjustment means can independently adjust the pressing strength of a leaf spring. In this embodiment, as described above, two types of methods are provided: (1) The structure in which the adjustment washer 21 is inserted between the leaf spring and the presser plates 25; and (2) The structure in which the adjustment washer 26 is inserted between the presser plates 25 and the housing 2. Additionally, the first pressing strength adjustment means may include both structure (1) and (2), or the first pressing strength adjustment means may include either one of the structure (1) and (2). By providing the first pressing strength adjustment means, the pressing strength of the three leaf springs can be independently adjusted. Accordingly, each of contact pressures of the transducer 35 and the roller 22 against the rotor plate 6 can be properly adjusted.
The second pressing strength adjustment means can totally adjust the pressing strength of the leaf springs. In this embodiment, by changing the thickness of the ring-shaped spacer 7, the pressing strength can be adjusted. According to this second pressing strength adjustment means, the pressing strength of the three leaf springs can be totally adjusted, thus facilitating assembly. Additionally, the first and second pressing strength adjustment means may be provided at the same time, or either one of the first and second pressing strength adjustment means may be provided.
The structures and operations of the transducer unit 15, the transducer 35, and the driving circuits thereof are described below with reference to
As shown in
Each of the piezoelectric sheets 37X and 37Y is formed from a rectangular piezoelectric device having a thickness of about 100 μm. A surface of the piezoelectric sheet 37X is divided into four areas, which are electrically insulated to each other. A silver-paradigm alloy having a thickness of about 10 μm is applied to the surfaces of the divided areas on one surface to form first internal electrodes 37Xa, 37Xc, 37Xc′, and 37Xa′, respectively. As shown in
On the other hand, a surface of the piezoelectric sheet 37Y is divided into four areas, which are electrically insulated to each other. A silver-paradigm alloy having a thickness of about 10 μm is applied to the surfaces of the divided areas on one surface to form second internal electrodes 37Yb, 37Yd, 37Yd′, and 37Yb′, respectively. As shown in
In the neighboring piezoelectric sheets 37X and 37Y, the arrangement of the first internal electrodes 37Xa, 37Xc, 37Xc′, and 37Xa′ is substantially the same as that of the second internal electrodes 37Yb, 37Yd, 37Yd′, and 37Yb′. However, the ends of the electrodes are upside down. When the piezoelectric sheets 37X and 37Y are laminated, the rectangular portions of the electrodes are arranged at different positions to each other. Two types of piezoelectric sheets 37X and 37Y having such arrangements of the electrodes are alternately layered up to about forty layers.
In
The piezoelectric sheets 37X and 37Y and the insulating sheets 37A and 37B having the same rectangular shape are arranged so that the piezoelectric sheets 37X and 37Y and the insulating sheets 37A and 37B sandwiches the above-described layered piezoelectric sheets so as to form the laminated piezoelectric substance 37. Thereafter, the laminated piezoelectric substance 37, in which the sheets are layered, is sintered, and electrodes are polarized using the above-described electrodes to form the transducer 35.
On a surface of the insulating sheet 37A of the transducer 35, electrodes 41a, 41b, 41c, 41d, 41a′, and 41b′ are formed from conductive silver paste (see
On the insulating sheet 37A, the electrodes 41a and 41b are electrically connected to the electrodes 41a′ and 41b′ via two lead wires 42e, respectively. Furthermore, a lead wire 42a is connected to the electrode 41a. A lead wire 42b is connected to the electrode 41b. A lead wire 42c is connected to the electrode 41c. A lead wire 42d is connected to the electrode 41d. These lead wires 42a, 42b, 42c, and 42d are connected to a transducer driving signal output terminal of a driving unit 47 of a transducer driving circuit 52, which is described later in
Two driving elements 38 are bonded to the front surface of the laminated piezoelectric substance 37, which forms the transducer 35, in a direction (q direction) orthogonal to the lamination direction of the laminated piezoelectric substance 37 at positions of antinodes of vibration spaced in the longitudinal direction (t direction). The driving element 38 is formed by dispersing alumina in a high-polymer material.
As stated above, the transducer holder 16 including the round support shafts 17 is bonded to the outer surfaces of the transducer 35 in the lamination direction (r direction) while bridging over the transducer 35. Each of the round support shafts 17 outwardly extends in the r direction. The middle point between the round support shafts 17 is positioned at the node of vibration. At that time, the lengthwise direction of the round support shafts 17 is positioned at substantially the middle point between the two driving elements 38. In the vibration wave motor 1 in which the transducer 35 is assembled as the transducer unit 15, the transducer 35 is disposed so that the lamination direction of the transducer 35 is parallel to the radial direction with respect to the rotation axis O. Also, in the vibration wave motor 1 in which the transducer unit 15 is assembled, the electrodes 41a, 41b, 41a′, and 41b′ on the insulating sheet 37A are arranged towards the outer periphery of the housing 2. Accordingly, the lead wires 42a, 42b, 42c, and 42d are easily led to outside the housing 2 while passing through the lead wire grooves 2c.
As shown in
To drive the vibration wave motor 1, a drive signal output from the oscillator unit 45 is phase-controlled by the driving unit 47 in the transducer drive circuit 52 controlled by the control μcom 51. The drive signal is output and applied to the electrodes 41a (41a′), 41b (41b′), 41c, and 41d of the transducer 35 via the lead wires 42a to 42d.
More specifically, the signal from the oscillator unit 45 is directly input to the signal lines A1 “+” phase and A1 “−” phase-via the driving unit 47. The signal output from the oscillator unit 45 and phase-changed by 90° by the phase-shift unit 46 is input to the signal lines A2 “+” phase and A2 “−” phase via the driving unit 47. That is, one of the signals not passing through the phase-shift unit 46 is voltage-amplified while maintaining the original phase, and is output as a first signal (A1 “+” phase). This signal is applied to the electrode 41a (41a′). The other signal not passing through the phase-shift unit 46 is voltage-amplified while the original phase is time-shifted by 180° from the first signal and the original voltage is reversed to a minus side, and is then output as a second signal (A1 “−” phase). This signal is applied to the electrode 41b (41b′).
In contrast, one of the signals passing through the phase-shift unit 46 and phase-changed by 90° is voltage-amplified while maintaining the phase, and is output as a third signal (A2 “+” phase). This signal is applied to the electrode 41c. The other signal is voltage-amplified while the phase is time-shifted by 180° from the third signal and the voltage is reversed to a minus side, and is then output as a fourth signal (A2 “−” phase). This signal is applied to the electrode 41d.
By inputting the first to fourth signals to the transducer 35, the transducer 35 generates vibration in which bending vibration is composed with longitudinal vibration. That is, the vibration in which the bending standing wave vibration is composed with the longitudinal vibration shown in
The moving direction of the transducer 35 is determined by the rotational direction of the elliptical vibrations of the driving elements 38. The rotational direction of the elliptical vibrations is determined by the phase difference determined by the phase-shift unit 46.
To detect an electric current of cycle signal applied to the transducer 35, which is a parameter indicating a vibration state, the electric current detection unit 49 in the vibration information detection unit 53 is connected to a drive signal line of the transducer 35. The phase difference detection unit 48 in the vibration information detection unit 53 is connected to the electric current detection unit 49 in order to detect a phase difference between the voltage of the cycle signal from the oscillator unit 45 and the electric current detected by the electric current detection unit 49. The control μcom 51 is connected to the phase difference detection unit 48 in order to receive the phase difference signal between the detected electric current and voltage. Furthermore, the oscillator unit 45 is connected to the control μcom 51.
The phase difference detection unit 48 detects the phase difference between the electric current and the voltage as a parameter indicating the vibration state of the transducer 35. Using the phase difference between the electric current and the voltage, the control μcom 51 detects a frequency in the vicinity of the resonance frequency of the transducer 35 whose vibration state is changed due to the external environment change. The control μcom 51 feeds back the detected frequency in the vicinity of the resonance frequency to the oscillator unit 45.
In this embodiment, the driving signal applied to the transducer 35 is a cycle signal. However, a square wave signal, a sine wave signal, or a sawtooth wave signal may be used. Also, in this embodiment, the phase difference detected by the phase difference detection unit 48 is determined to be the phase difference between the voltage of the cycle signal from the oscillator unit 45 and the electric current of the cycle signal applied to the transducer 35. However, the phase difference is not limited to such a definition. The phase difference may be determined to be the phase difference between the voltage and the electric current of the cycle signal applied to the transducer 35.
As described above, in the vibration wave motor 1, by inputting the phase difference between the electric current of the cycle signal applied to the transducer 35, which is a signal detected by the phase difference detection unit 48, and the voltage of the cycle signal from the oscillator unit 45, the frequency in the vicinity of the resonance frequency of the transducer 35 is detected when the frequency detection operation is carried out. The detection result is fed back to the oscillator unit 45 so that the frequency in the vicinity of the resonance frequency can be detected and the transducer 35 can be driven by the detected frequency even when the resonant state of the transducer 35 changes due to the change in the external environment. Accordingly, the transducer 35 can be advantageously driven in conditions that provide high drive efficiency.
The vibration wave motor 1 having such a structure is integrated into a unit, as shown in
The structure and operation of the vibration wave motor 1 is described next with reference to
An interchangeable lens barrel 60 is mounted to a camera body 55 (see
Thus, the vibration wave motor 1 is incorporated in the lens barrel 60 so that the housing 2 faces the mount 29 of the interchangeable lens barrel 60 and the rotor 3 faces the lenses. Since the rotor 3 of the vibration wave motor 1 is arranged to face the lens, which is a driving target, a driving force transfer mechanism in the lens barrel 60 can be simplified.
In addition, the connection rod 28 supported by the LD ring 27 is assembled so that the rear fork end 28a adjacent to the vibration wave motor 1 is engaged with the protrusion 4a of the rotor body 4 of the vibration wave motor 1, and a front fork end 28b is engaged with the second zoom frame 65 only relatively slidably in the Q direction. Accordingly, when the rotor 3 of the vibration wave motor 1 is driven to rotate, the connection rod 28 turns along with the LD ring 27, and therefore, the second zoom frame 65 is driven to rotate. As the second zoom frame 65 rotates, the second zoom frame 65 is driven to move forward and backward along the cam groove engaged with the cam follower 67.
As shown in
In the lens barrel 60 to which the camera body 55 is mounted, when the zoom operation ring 62 is turned, a zooming operation is performed. That is, when the cam frame 64 is turned by the zooming operation, the second zoom frame 65 moves forward or backward via the cam follower 67, and therefore, the second lens group 72 moves to a zooming position. Simultaneously, the first group lens 71, the fourth group lens 74, and the fifth group lens 75 move to the zooming positions thereof via a cam follower (not shown). However, the third group lens 73 does not move forward and backward.
If the distance operation ring 63 is turned or if a focusing operation is performed on the basis of measured distance data from a ranging unit, the group lenses at the zooming positions shown in
In this embodiment, as shown in
Furthermore, by selectively using the adjustment washer 21 inserted into the leaf spring 18, and the adjustment washer 26 and the ring-shaped spacer 7 inserted into the presser plates 25 as a pressing strength adjustment mechanism, the pressing strength can be reliably adjusted.
Still furthermore, since the vibration wave motor 1 is integrated into a unit serving as a power source, the vibration wave motor 1 can be easily assembled in a variety of types, a variety of specifications of lens barrels or electronic apparatuses.
In the above-described examples, two transducers 35 and one roller 22 are inserted into the three insertion openings 2a of the housing 2 to assemble them. However, by changing the number of the inserted transducers 35 as needed, the output of the vibration wave motor 1 can be easily increased or decreased. For example, one or three transducers can be assembled into the housing 2. At that time, by inserting the roller 22 into the insertion opening 2a to which the transducer is not inserted, in place of transducer, the pressing strength is applied to the rotor 3 in a balanced manner. Additionally, in this embodiment, since the three insertion openings 2a have the same shape, the transducer can be easily replaced with the roller.
The number of the insertion openings 2a of the housing 2 can be increased or decreased to insert the transducer 35 as needed. That is, the number of the insertion openings may be provided other than three, the transducers may be increased or decreased. Thus, the required output of the vibration wave motor 1 can be obtained.
In the first pressing strength adjustment mechanism, the pressing strength of the transducer 35 may be adjusted by either one of the adjustment washer 21 and the adjustment washer 26. Furthermore, the pressing strength of the transducer 35 may be adjusted by either one of the first pressing strength adjustment mechanism and the second pressing strength adjustment mechanism using the ring-shaped spacer 7.
Various modifications of each component of the vibration wave motor 1 of the above-described embodiment are described next. A vibration wave motor according to each modification has the same structure as the vibration wave motor 1 according to the above-described embodiment except for the points described below.
The modification of the transducer unit is described with reference to
As shown in
The transducer unit 15A including the connection FPC of this modification eliminates a lead wire that is difficult to handle for wiring, thus facilitating the assembly.
The exemplary connection of a transducer unit including a connection FPC of a modification is described with reference to a perspective view of the connection FPC in
In this example, as shown in
A transducer unit 15B of a modification in which the transducer holder 16 is eliminated from the transducer unit 15 of the above-described embodiment is described next with reference to perspective views of the transducer unit 15B in
In the transducer unit 15B of this modification, a support shaft 36 directly passes through a transducer 35B and is fixed to the transducer 35B. Like the transducer unit 15, the support shaft 36 is positioned at the node of vibration of the transducer 35B. In the vibration wave motor 1 in which the transducer unit 15B is assembled, a leaf spring having the same shape as the leaf spring 23 for the roller 22 is applied. In this case, the support shaft 36 fitted to the guide groove of the housing 2 is directly pressed by a protrusion of the leaf spring. Like the above-described embodiment, a slippery gap adjustment washer is inserted in a gap between the transducer 35B and the insertion opening 2a of the housing 2 in the R direction, thus eliminating backlash.
The transducer unit 15B of this modification eliminates the transducer holder, and therefore, the number of components can be reduced. Also, the footprint of the transducer unit can be reduced. Accordingly, the size of vibration wave motor can be advantageously reduced.
A modification of the presser plate 25 of the above-described embodiment is described next with reference to
In the vibration wave motor 1 of the above-described embodiment, the three presser plates 25 are employed. In this modification, one ring-shaped presser plate 25A is employed. In this case, the presser plate 25A is fixed to the housing 2 with three screws.
In this modification, by independently changing thicknesses of three adjustment washers inserted between the presser plate 25A and the housing 2 as a pressing strength adjustment mechanism, the pressing strength of two transducers 35 and one roller 22 can be adjusted at the same time.
In this modification, only one presser plate 25A is attached to the housing 2, thus facilitating the assembly.
A leaf spring 81, which is a modification of the leaf spring 18 of the above-described embodiment, is described next with reference to
As shown in
The leaf spring 81 is attached to the presser plate 25, as in the case of the leaf spring 18. That is, when the leaf spring 81 presses against the transducer holder 16, one end of the leaf spring 81 slightly slides on the shoulder screw 20 along the slot 81c so as to resiliently deform. A pressing strength caused by the resilient deformation presses against the transducer holder 16 and displaces the transducer holder 16 in the Q direction by substantially translating the transducer holder 16. When the pressing strength is applied or when the pressing strength is adjusted, the protrusion 81d is slightly displaced in the T direction, as shown in
When the leaf spring 81 of this modification is applied and even if the degree of parallelization among the surfaces of the presser plates 25, the leaf spring 81, and the transducer holder 16 in the T direction and even in the R direction is relatively low, the leaf spring 81 is not in contact with the transducer holder 16 at one side, since the protrusion 81d, which is a contacting portion, has a small hemispherical shape. Therefore, a normal contact between the top end of the protrusion 81d and the end surface 16a of the transducer holder 16 can be obtained.
A leaf spring 82, which is another modification of the leaf spring 18 of the above-described embodiment, is described next with reference to
Like the leaf spring 18, the leaf spring 82 of this modification is a resiliently deformable metallic leaf spring member having a shape of a both ends supported beam and extending in the T direction. A mountain-shaped protrusion 82d protruding towards the transducer unit 15 in the Q direction is formed on a middle flat section of the leaf spring 18 and serves as a pressing portion. The shapes of the other portions are similar to those of the leaf spring 18. In the leaf spring 82, both sides of the middle flat section are slightly bent and arm portions 82a, which are resiliently deformable pressurizing portions, are formed. A circular hole 82b is formed at a first end 82e, which is one end of the leaf spring 82, and a slot 82c extending in the T direction is formed at a second end 82f, which is the other end of the leaf spring 82. The mountain-shaped protrusion 82d has a ridge line on the top in the R direction. The ridge line is located at a position where a center axis of the support shaft 17 is translated in the Q direction. The ridge line of the mountain-shaped protrusion 82d is in line contact with the end surface 16a of the transducer holder 16 after assembling the leaf spring 82.
In this modification, the position where the mountain-shaped protrusion 82d is in line contact with the end surface 16a substantially coincides with the position of the node of vibration in the transducer 35.
The leaf spring 82 is attached to the presser plate 25, as in the case of the leaf spring 18. Accordingly, when the leaf spring 82 presses against the transducer holder 16, one end of the leaf spring 82 slightly slides on the shoulder screw 20 along the slot 82c so as to resiliently deform. The pressing strength of the mountain-shaped protrusion 82d caused by the resilient deformation presses against the transducer holder 16 and displaces in the Q direction while being translated. When the pressing strength is applied or when the pressing strength is adjusted, the mountain-shaped protrusion 82d is slightly displaced in the T direction, as shown in
When the leaf spring 82 of this modification is applied, the same advantage as that of the leaf spring 18 is provided. In particular, since the ridge line of the mountain-shaped protrusion 82d is in contact with the transducer holder 16, the contacting portion becomes a line. Consequently, the leaf spring 82 reliably presses against the center of the transducer holder 16 along the node of vibration of the transducer 35.
A leaf spring 83, which is another modification of the leaf spring 18 of the above-described embodiment, is described next with reference to
As shown in
The spring portions 83A, 83B, and 83C have the same shape. Here, the shape of the spring portion 83A is described. In the leaf spring 83A, on a middle flat section of the leaf spring 83A, a small hemispherical protrusion 83d is provided while protruding towards the transducer unit 15 in the Q direction and serves as a pressing portion. Both sides of the middle flat section are slightly bent and arm portions 83a, which are resiliently deformable pressurizing portions, are formed. Also, a protrusion 83g is provided, which protrudes from the middle flat section in the R direction (from the rotation axis to the outer periphery thereof) and serves as a leaf spring support mechanism and a pressing position restriction unit. Furthermore, slots 83b and 83c extending in the T direction are formed at ends of the arm portions 83a. The small hemispherical protrusion 83d is located at a position distant from the center axis of the support shaft 17 of the transducer unit 15 in the Q direction. The small hemispherical protrusion 83d is in point contact with the center of the end surface 16a of the transducer holder 16 after being assembled. The protrusion 83g fits into one of the guide grooves 2b of the insertion openings 2a of the housing 2 without backlash so as to restrict the movement of the leaf spring 83A in the T direction. That is, the protrusion 83g restricts the pressing position. It is noted that the protrusion 83g may protrude towards the inside in contrast to the above-described direction.
As will be described below, when the spring portions 83A, 83B, and 83C press against the transducer holders 16 and extend in the T direction, the connection portions 83h easily deform to absorb the expansion of the leaf spring.
As shown in
The transducer units 15 disposed in the insertion openings 2a of the housing 2 are urged by the spring portions 83A, 83B, and 83C of the leaf spring 83 from the rear, and then the presser plate 25A is fixed to the housing 2 by screws. After the presser plate 25A is fixed to the housing 2, the small hemispherical protrusions 83d press against the transducer holders 16. The pressing strength can be adjusted by changing the thicknesses of the adjustment washer 21 and the adjustment washer 26 between the presser plate 25A and the housing 2. When the leaf spring 83 presses against the transducer holders 16 or when the pressing strength is adjusted (that is, the pressing strength is changed), ends of the spring portions 83A, 83B, and 83C attached to the shoulder screw 20 slightly slide in the slots 83b and 83c, which the shoulder screws 20 pass through, so as to expand towards both sides thereof. However, since the protrusion 83g fits in the guide grooves 2b, the pressing position of the small hemispherical protrusion 83d against the transducer holder A is not shifted in the T direction. Furthermore, even when the spring portions 83A, 83B, and 83C deform, the small hemispherical protrusion 83d is only translated. Accordingly, the pressing direction does not change. Thus, the stable and superior pressing state against the transducer can be obtained.
When the leaf spring 83 of this modification is applied, the same advantage as that of the leaf spring 18 is provided. In particular, since the pressing position of the small hemispherical protrusion 83d remains unchanged, the small hemispherical protrusion 83d presses the center of the transducer holder 16 at all times. In addition, since the leaf spring 83 is formed as a single ring without being divided into three pieces, the assembly is facilitated.
Instead of the leaf spring 83 of the above-described modification, the leaf spring 84 having a shape shown in
When the leaf spring 84 presses against the transducer holder 16 and the pressing strength is further adjusted, both ends of the spring portion 84A or 84B expand. However, since the connection portion 84h easily deforms, the positional shift of the spring portion 84A or 84B becomes relatively small compared to the expansion of the ends. In addition, since, like the leaf spring 83, the protrusion 84g fits in one of the guide grooves 2b, the shift in the T direction of the pressing position of the small hemispherical protrusion 84d against the transducer holder does not occur. Furthermore, the pressing direction does not change. Thus, the stable and superior pressing state against the transducer can be obtained.
The modifications of the transducer unit 15 and the leaf spring 18 of the above-described embodiment are described next with reference to
In the transducer unit 15C of this modification, unlike the transducer unit 15, an oval stepped portion 16Ca extending in the R direction is formed on a surface of a transducer holder 16C in the Q direction, which is fixed to a transducer, as a pressed portion. The other portions are similar to those of the transducer unit 15. The oval stepped portion 16Ca is located at a position where the support shaft 17 of the transducer holder 16 is translated in the Q direction.
The leaf spring 85, which is a resilient plate member used together with the transducer unit 15C, has two arm portions 85a, a circular hole 85b, and a slot 85c as in the above-described embodiment except that the leaf spring 85 has no protrusion on a middle flat portion 85d serving as a pressing surface. The leaf spring 85 is attached to the presser plates 25 with the adjustment washer 21 therebetween by the setscrew 19 and the shoulder screw 20. Thereafter, while the middle flat portion 85d of the leaf spring 85 is in line contact with the oval stepped portion 16Ca of the transducer holder 16, the presser plates 25 is fixed to the housing 2.
In the assembled state, the middle flat portion 85d of the leaf spring 85 presses against the top of the oval stepped portion 16Ca formed on the surface of the transducer holder 16 and extending in the R direction. To adjust the pressing strength, the adjustment washers 21 and 26 are used, as for the leaf spring 18 of the above-described embodiment.
In the vibration wave motor including the transducer unit 15C and the leaf spring 85 of this modification, since the middle flat portion 85d of the leaf spring 85 is in contact with the oval stepped portion 16Ca of the transducer holder 16, the support shaft is pressed via the center of the transducer holder 16 at all times including the case where the pressing strength is adjusted. Accordingly, the two driving elements 38 of the transducer 35 are evenly in contact with the rotor plate 6 in a direction perpendicular to the friction contact surface. Thus, more stable driving state can be obtained compared to the above-described embodiment.
In the transducer unit 15D of this modification, a small hemispherical protrusion 16Da is formed on an end surface of a transducer holder 16D fixed to the transducer 35 at a position distant from the center axis of the support shaft 17 in the Q direction and serves as a pressed protrusion. To press against the transducer unit 15D, the leaf spring 85 of the above-described modification is employed (see
In a vibration wave motor including the transducer unit 15D of this modification, the middle flat portion 85d of the leaf spring 85 is in point contact with the small hemispherical protrusion 16Da of the transducer holder 16D to press against the transducer holder 16D. Accordingly, even when the degree of parallelization between the presser plates 25 and the rotor plate 6 is relatively low in the R or T direction, the leaf spring 85 is not in contact with the transducer holder 16D at one side including the case where the pressing strength is adjusted. Therefore, the transducer 35 is pressed via the small hemispherical protrusion 16Da. Accordingly, the two driving elements 38 of the transducer 35 are evenly in contact with the rotor plate 6 in a direction perpendicular to the friction contact surface. Thus, more stable driving state can be obtained compared to the above-described embodiment.
In the transducer unit 15E of this modification, a mountain-shaped protrusion 16Ea having a ridge line on the top is formed as a pressed protrusion on an end surface of a transducer holder 16E fixed to the transducer 35. The ridge line extends along the R direction and is located at a position where the center axis of the support shaft 17 is translated in the Q direction. To press against the transducer unit 15E, the leaf spring 85 of the above-described modification is employed (see
In a vibration wave motor including the transducer unit 15E of this modification, the middle flat portion 85d of the leaf spring 85 is in line contact with the mountain-shaped protrusion 16Ea of the transducer holder 16E to press against the transducer holder 16E. When the leaf spring 85 presses against the transducer holder 16E or when the pressing strength is adjusted, the leaf spring 85 is not in contact with the transducer holder 16E at one side. Therefore, the transducer 35 is pressed via the mountain-shaped protrusion 16Ea at all times. Accordingly, the two driving elements 38 of the transducer 35 are evenly in contact with the rotor plate 6 in a direction perpendicular to the friction contact surface. Thus, more stable driving state can be obtained compared to the above-described embodiment.
The transducer unit 15F of this modification includes the transducer 35 and a transducer holder 16F having a round support shaft 17F which is fixed to the transducer 35 and protrudes from both sides of the transducer 35. The support shaft 17F is located at a position of the node of vibration of the transducer 35. The transducer holder 16F and the transducer 35 rotatably fit to the presser 91 via the support shaft 17F. The presser 91 has a U-shape having an opening. At an end of the presser 91 adjacent to the opening, two notches 91a opposed to each other in the R direction are formed to serve as an engagement portion engaged with the support shaft. A flat end surface 91b is formed at the other end of the presser 91 remote from the opening. The presser 91 fits to the transducer holder 16F in the R direction without backlash. The support shaft 17F is rotatably engaged with the notches 91a. To press against the transducer unit 15F, the leaf spring 85 of the above-described modification is employed (see
The transducer unit 15F with which the presser 91 is engaged is inserted to the insertion opening 2a of the housing 2, and the support shaft 17F fits into the guide grooves 2b. Thereafter, the presser plate 25 on which the leaf spring 85 is mounted is attached to the housing 2. The end surface 91b of the presser 91 is in flat contact with the middle flat portion 85d of the leaf spring 85, thereby being pressed followed by the flat portion 85d. The transducer 35 is pressed via the support shaft 17F of the transducer holder 16F so that the driving elements 38 are in tight contact with the rotor plate 6. Adjustment of the pressing strength of the leaf spring 85 can be performed in the same manner as that described with reference to
In a vibration wave motor according to this modification, when the leaf spring 85 presses against the transducer unit 15F or when the pressing strength is adjusted, the middle flat portion 85d of the leaf spring 85 is always in flat contact with the end surface 91b of the presser 91. In addition, since the presser 91 directly presses against the support shaft 17F of the transducer 35, the two driving elements 38 of the transducer 35 are evenly in contact with the rotor plate 6 in a direction perpendicular to the friction contact surface. Thus, more stable driving state can be obtained compared to the above-described embodiment.
The transducer unit 15G of this modification includes the transducer 35 and a transducer holder 16G. The transducer holder 16G includes a support shaft 17G serving as a support rod having a prismatic shape, for example, a triangle pole. The support shaft 17G protrudes from both sides of the transducer holder 16G and is fixed to the transducer holder 16G. In this case, the position of the ridge line (vertex) of the support shaft 17G having a triangle pole shape is located at a position of the node of vibration of the transducer 35. The presser 92 rotatably fits to the transducer 35 and the transducer holder 16G fixed to the transducer via the support shaft 17G. The presser 92 has a U-shape having an opening. At an end of the presser 92 adjacent to the opening, two notches 92a opposed to each other in the R direction are formed to serve as an engagement portion engaged with the support shaft 17G. A flat end surface 92b is formed at the other end of the presser 92 remote from the opening. The presser 92 fits to the transducer holder 16G in the R direction without backlash. The presser 92 can rotate about the ridge line of the support shaft 17G having a triangle pole shape in the notches 92a. To press against the transducer unit 15G, the leaf spring 85 of the above-described modification is employed (see
The operation of a vibration wave motor including the transducer unit 15G and the presser 92 is the same as that of the modification shown in
Two modifications of the pressing strength adjustment mechanism of the transducer in the vibration wave motor 1 of the above-described embodiment are described next with reference to
The transducer-unit pressing portion including the first pressing strength adjustment means of this modification includes the transducer unit 15, the leaf spring 18, and the adjustment washer 21 serving as the pressing strength adjustment means, all of which are the same as those used in the above-described embodiment. The transducer-unit pressurizing portion further includes a plate-shaped adjustment spacer 93 also serving as the pressing strength adjustment means.
As shown in
The pressing strength of the leaf spring 18 against the transducer unit 15 can be adjusted by the thickness of the adjustment washers 21 disposed between both ends of the leaf spring 18 and the presser plates 25. In particular, as shown in
In addition, the pressing strength can be adjusted by bonding the adjustment spacer 93 having an appropriate thickness onto the end surface 16a of the transducer holder 16 and by the oval stepped portion 18d of the leaf spring 18 pressing against the transducer holder 16 with the adjustment spacer 93 therebetween. If the adjustment of the pressing direction H is not required, the pressing strength can be adjusted using only the adjustment spacer 93 without using the adjustment washer 21.
The vibration wave motor having the pressing strength adjustment mechanism of this modification includes a housing 2A, the transducer unit 15 inserted into the housing 2A, the leaf spring 18 for pressing against the transducer 35 of the transducer unit 15, a rotor 3 in contact with the transducer 35 and rotatably driven, the bearing member 8, the bearing holder 11A, and the presser plates 25.
Like the housing 2 of the above-described embodiment, the housing 2A includes the insertion openings 2a and the guide grooves 2b for inserting the transducer unit 15. The housing 2A further includes an adjustment screw (adjustment male screw) 2Ad for adjusting the pressing strength of a leaf spring on the outer periphery of the housing 2A.
The bearing holder 11A includes a V groove 11a and an adjustment screw (adjustment female screw) 11Ab screwed by the adjustment screw 2Ad of the housing 2A.
In a vibration wave motor of this modification, the transducer unit 15, the leaf spring.18, the presser plates 25 are assembled into the housing 2A. The rotor 3 and the bearing member 8 are further attached onto the front of these components. The adjustment screw 2Ad is screwed to the adjustment screw 11Ab of the bearing holder 11A.
By screwing the adjustment screw 2Ad to the adjustment screw 11Ab, the transducer holder 16 and the transducer 35 are pressed by the leaf spring 18. By changing a screwed amount, the pressing strength of the driving element 38 against the rotor plate 6 can be adjusted. When an appropriate pressing strength is obtained, the adjustment screws 2Ad and 11Ab are fixed by means of, for example, bonding.
According to the pressing strength adjustment mechanism of this modification, the pressing strength of the transducer 35 against the rotor 3 can be easily adjusted by the adjustment screws 2Ad and 11Ab. Furthermore, the pressing strength may be adjusted by using the adjustment washers 21 and 26 of the above-described embodiment in addition to the adjustment screws 2Ad and 11Ab.
The modification of the roller pressing unit using the leaf spring shown in
The roller pressing unit of this modification includes a leaf spring 98 and a roller holder 97. As shown in
As shown in
Like the vibration wave motor 1 of the above-described embodiment, in a vibration wave motor including the roller pressurizing unit of this modification, the roller 95 is pressed against the rotor plate 6 due to the urging force of the leaf spring 98. While this urging force is balanced with the pressing strength of the driving element 38 of the transducer 35 against the rotor plate 6 due to the urging force of the leaf spring 18, the rotor 3 is driven to rotate.
While, in the embodiment and modifications of the invention disclosed herein, a vibration wave motor is a motor in which a transducer generates a driving force from ultrasonic vibration (i.e., ultrasonic motor), it should be clearly understood that the present invention is equally suitable for use of a vibration wave motor in which a transducer generates a driving force from other than ultrasonic vibration, e.g., an auditory sound vibration.
Furthermore, the key structures of the vibration wave motor of the present invention can be applied to a linear actuator motor. In this case, the housing 2, the bearing member, and the bearing holder member are formed from straight members or members curved along a direction-of the driving movement.
A vibration wave motor according to the present invention is a high-efficiency vibration wave motor in which a transducer is in contact with a rotor in an appropriate condition. Furthermore, a vibration wave motor according to the present invention can be integrated into a unit that can be easily assembled into a variety of apparatuses.
Number | Date | Country | Kind |
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2004-343116 | Nov 2004 | JP | national |
2004-343143 | Nov 2004 | JP | national |
2004-343144 | Nov 2004 | JP | national |