Linear driving apparatus using vibration wave motor and optical apparatus

In a linear driving apparatus including a vibration wave motor, a driving target body movable in a moving direction, a transmission member which is held by the driving target body and abuts against an abutment part of a moving member to synchronously move the vibration wave motor and the driving target body, and a biasing member which gives a biasing force between the transmission member and the abutment part, the direction of a pressure contact force which a vibrator receives from a friction member and the direction of a biasing contact force which the abutment part receives from the biasing member are parallel and opposite to each other, and the load center of the distribution load of the biasing contact force falls within the range of the vibrator.

TECHNICAL FIELD

The present invention relates to a linear driving apparatus using a vibration wave motor and an optical apparatus.

BACKGROUND ART

In a conventional ultrasonic motor, a high-frequency voltage is applied to a piezoelectric element to ultrasonically vibrate a vibrator fixed to the piezoelectric element. The ultrasonic vibration of the vibrator generates a driving force between a friction member and the vibrator pressed against the friction member. This motor can maintain high output even in a compact size. For example, PTL 1 discloses an ultrasonic motor using a compact vibrator. In addition, various contrivances for the efficient transmission of a driving force to a driving target body have been introduced into the ultrasonic motor. For example, in the ultrasonic motor disclosed in PTL 2, a rolling member is clamped by the resultant force of a pressing force given to the vibrator or its reactive force and the biasing force of a transmission member supported by a driving target body.

CITATION LIST

Patent Literature

In order to downsize and simplify the ultrasonic motor disclosed in PTL 2, there is proposed a sliding structure like that shown inFIG. 16, which is provided with guide shafts600extending in the moving direction (the X direction shown inFIG. 16) of a moving member400, with sliding holes400afitted on the guide shafts600being formed in the moving member400. In this sliding structure, the guide shafts600and the sliding holes400aslidably guide the moving member400. This structure makes it possible to decide a size L in the moving direction X of the moving member400regardless of the movement amount of the moving member400, and hence to implement the moving member400having the same length as that of the vibrator main body. In addition, since rolling balls can be omitted, the apparatus can be downsized and simplified. In this arrangement, however, the resultant force of the reactive force of the pressing force given to the vibrator and the biasing force of the transmission member supported by the driving target body acts as a drag (in a direction vertical to the drawing surface) on the guide shafts600and the sliding holes400a.This increases the frictional force and decreases the driving force of the ultrasonic motor.

SUMMARY OF INVENTION

In order to solve the above problems, the present invention provides a linear driving apparatus using a vibration wave motor which can be downsized and simplified without reduction in driving force and an optical apparatus.

Technical Problem

In order to solve the above problems, a linear driving apparatus according to the present invention is characterized by comprising a vibration wave motor including a vibrator including a piezoelectric element which generates vibration, a friction member fixed to face the vibrator, a press member which gives a pressing force between the vibrator and the friction member, a moving member which is configured to move in predetermined moving direction, a coupling member which couples the vibrator to the moving member and synchronously moves the vibrator and the moving member, and a guide member which slidably guides the moving member in the moving direction, a driving target body which is configured to move in the moving direction, a transmission member which is supported by the driving target body, abuts against an abutment part of the moving member, and synchronously moves the vibration wave motor and the driving target body, and a biasing member which gives a biasing force between the transmission member and the abutment part, wherein a direction of a pressure contact force which the vibrator receives from the friction member and a direction of a biasing contact force which the abutment part receives from the biasing member are parallel and opposite directions, and a load center of a distribution load of the biasing contact force falls within a range of the vibrator.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a vibration wave motor which can be downsized and simplified without reduction in the driving force of the vibration wave motor and a linear driving apparatus using the vibration wave motor.

DESCRIPTION OF EMBODIMENTS

The arrangement of a linear driving apparatus using a vibration wave motor (ultrasonic motor)10according to the present invention will be described below with reference to the accompanying drawings. Assume that the moving direction of a vibrator1of the vibration wave motor10is defined as the X direction, the pressing direction of a press member3is defined as the Z direction, and a direction perpendicular to the X and Z directions is defined as the Y direction. With regard to all the drawings, the X, Y, and Z directions are defined as described above.

The linear driving apparatus using the vibration wave motor10according to this embodiment will be described first.FIG. 1Ais an exploded perspective view showing the linear driving apparatus using the vibration wave motor10, which is exploded in the Z direction.FIG. 1Bshows a completed linear driving apparatus. A driving target body17is a lens frame used for a photographing apparatus as a driving target. The driving target body17can reciprocally move in a moving direction X of a moving member4while being guided by guide shafts15when the vibration wave motor outputs a driving force. Although the embodiment has exemplified an optical apparatus using the linear driving apparatus with the driving target body17being a lens frame used for a photographing apparatus, the driving target body17can be applied to a component other than the lens frame.

A transmission member18is supported by a support portion17aof the driving target body17. The transmission member18is mounted on the moving member4, together with a biasing member19, so as to abut against an abutment part4dof the moving member4. The linear driving apparatus using the vibration wave motor10in the completed state shown inFIG. 1Bis configured such that a driving force is transmitted from the vibrator1as a drive source (to be described later) to a coupling member5, the moving member4, the abutment part4d,the transmission member18, and the driving target body17in the order named to reciprocally move the driving target body17in the X direction.

FIGS. 2A and 2Bare perspective views, respectively, of the transmission member18and the biasing member19.FIG. 2Ais a view seen from above in the Z direction.FIG. 2Bis a view seen from below in the Z direction.FIGS. 2C and 2Dare enlarged views, respectively, of an abutment portion where the transmission member18abuts against the abutment part4dof the moving member4.FIG. 2Cis a projection view seen from the Z direction.FIG. 2Dis a sectional view seen from the Y direction. The transmission member18is supported by the support portion17aof the driving target body17described above and abuts against the abutment part4dof the moving member4to synchronously move the moving member and the driving target body17. The transmission member18has a concave portion18a.The concave portion18ais configured to come into biasing contact with the abutment part4d.In this embodiment, the transmission member18is supported by the support portion17aso as to be freely pivotal about a shaft18b.It is however possible to select an arrangement in which the transmission member18is supported to be linearly movable. In addition, in the embodiment, a concave shape is formed on the transmission member18side, and a convex shape is formed on the abutment part4dside. It is however possible to select an arrangement in which convex and concave portions are formed on the opposite sides to those in the above arrangement.

The biasing member19is a torsion coil spring, which applies a biasing force to the transmission member18to provide a biasing contact force FB between the transmission member18and the abutment part4d.In this embodiment, the biasing member19is a torsion coil spring. However, it is possible to select a compression spring, tension spring, or leaf spring as long as it can provide the biasing contact force FB.

Referring toFIG. 2C, since the concave portion18ahas an almost V-shaped cross-section (seeFIG. 2D), the biasing contact force FB generated by the biasing member19has two distribution load areas M1and M2. A load center B of the distribution loads corresponds to the midpoint of them. Although this embodiment has exemplified the case in which there are two distribution load areas, even if the number of distribution load areas changes in accordance with the shapes of the transmission member18and the abutment part4d,the load center B of the distribution loads can be regarded in the same manner.

A portion through which the vibration wave motor10used for the linear driving apparatus according to this embodiment transmits a driving force to the driving target body17will be described next.FIG. 3Ais a plan view showing how the transmission member18is mounted on the vibration wave motor10and biased by the biasing member19.FIG. 3Bis a sectional view taken along a cut line IIIB-IIIB inFIG. 3A.FIG. 3Cis a sectional view taken along a cut line IIIC-IIIC inFIG. 3A.FIG. 3Dis a perspective view.

Referring toFIG. 3A, the distribution load areas of a pressure contact force FA between the vibrator1and a friction member2correspond to the ranges of protruding portions1bof the vibrator1. Therefore, the pressure contact force FA has two distribution load areas N1and N2. A load center A of the distribution load areas corresponds to the midpoint of the distribution loads. Although this embodiment has exemplified the case in which there are two distribution load areas, even if the number of distribution load areas changes in accordance with the number of protruding portions1bof the vibrator1, the load center A of the distribution loads can be regarded in the same manner.

FIG. 3Dshows how the pressure contact force FA and the biasing contact force FB act. If the load center A coincides with the load center B, a couple V1around the Y-axis almost perpendicular to the moving direction X can be reduced to 0. Likewise, a couple V2around the X-axis in the moving direction can be reduced to 0. Note that the load center A and the load center B are emphatically shown.

The arrangement of a vibration wave motor11according to Example 1 which is used for the linear driving apparatus according to the embodiment of the present invention will be described.FIGS. 4A and 4Bare exploded perspective views, respectively, of the vibration wave motor11.FIG. 4Ais a view seen from above in the Z direction.FIG. 4Bis a view seen from below in the Z direction.

A vibrator1is constituted by a plate portion1a,two protruding portions1b,and a piezoelectric element1c.The protruding portions1band the plate portion1acan be integrally molded or assembled as separate components. The piezoelectric element1chas a predetermined area polarized and is attached to the plate portion1a.A power feeding means (not shown) applies a high-frequency voltage to the piezoelectric element1cto generate vibration (ultrasonic vibration) with a frequency in an ultrasonic region. Since PTL 1 has described the principle of obtaining a driving force from the vibrator1by generating this vibration, a description of it will be omitted. Although Example 1 has exemplified the case in which the vibrator1has the two protruding portions1b,the number of protruding portions1bis selectable in accordance with a desired driving force. The vibrator1can reciprocally move in the X direction shown inFIGS. 4A and 4B.

A friction member2is arranged to face the vibrator1and is fixed to fixing members8. Example 1 exemplifies a case in which the friction member2has a plate-like shape. However, a round bar shape or the like can also be selected as the shape of the friction member2. In addition, a material such as a metal or ceramic material can be selected for the friction member2within a range that satisfies requirements for mechanical characteristics such as rigidity and surface properties.

Press members13are four compression springs. The lower end portions of the press members13abut against a press plate12to give pressing forces f to the vibrator1through a felt member7in the direction shown inFIGS. 4A and 4B. The felt member7is provided to prevent the attenuation of vibration. The press plate12is provided to give the pressing forces f to the entire piezoelectric element1c.Example 1 has exemplified the case in which the press members13are the compression springs. However, torsion coil springs, tension springs, leaf springs, or the like can be selected as the press members13. The number of springs can be freely selected as long as the sum of the pressing forces f of the press members13is appropriate. In addition, Example 1 exemplifies an arrangement in which areas where the press members13exist overlap an area where the vibrator1exists when being projected on an X-Y plane.

A moving member14can move in a moving direction X of the vibrator1and holds the upper end portions of the press members13. The moving member14includes sliding parts14a,14b,and14cas holes to be fitted on guide members6(to be described later) and an abutment part14dwhich abuts against a transmission member18. The sliding parts14a,14b,and14cand the abutment part14dcan be integrally molded or assembled as separate components to the moving member14.

A coupling member5is coupled to the vibrator1through first coupling portions5aor coupled to the moving member14through second coupling portions5bto couple the vibrator1to the moving member14. This makes it possible to synchronously move the vibrator1and the moving member14. The coupling member5has a property of exhibiting low rigidity in the Z direction so as not to inhibit a pressure contact force FA between the vibrator1and the friction member2and exhibiting high rigidity in the X direction to allow the vibrator1and the moving member14to synchronously move. When being coupled to the vibrator1through the first coupling portions5a,the coupling member5is fixed to portions of the vibrator1which correspond to nodes of vibration or similar portions at which vibration is small by a method like bonding or welding (not shown), so as not to inhibit vibration of the vibrator1. When being coupled to the moving member14through the second coupling portions5b,the coupling member5is fixed to the moving member14by a method like bonding, welding, or screw fastening (not shown). Example 1 has exemplified the case in which the coupling member5is formed from one member having a frame-like shape. However, the coupling member5may be formed from a plurality of members or an arbitrary material and shape can be selected for the coupling member5within a range that satisfies the requirement for the above rigidity characteristic.

The guide members6are round bars for slidably guiding the moving member14in the X direction. The guide members6are sliding guides, without rolling balls and the like, which are fitted in the sliding parts14a,14b,and14cof the moving member14. Example 1 exemplifies a case in which the round bars are used. However, square bars or plate members can be selected as long as the shapes of the sliding parts14a,14b,and14care made to comply with the guide members.

The fixing members8are supported by fixing portions (not shown), assembled in an X1direction shown inFIG. 4A, and hold the guide members6by fitting them in four holes8a.The friction member2is then fixed to the fixing members8by being fastened with screws9. As a holding method for the guide members6and a fixing method for the friction member2, arbitrary methods can be selected.

Forces generated inside the vibration wave motor11according to Example 1 will be described next.FIGS. 5A and 5Care sectional views, respectively, near an abutment portion between the moving member14and the transmission member18.FIGS. 5B and 5Dare partially enlarged views, respectively, on an X-Y plane.FIG. 5Eis a perspective view. The vibrator1, the felt member7, the press plate12, the press members13, the moving member14, the transmission member18, and a biasing member19are components which move in the X direction, to which the friction member2and the guide members6are fixed.

The pressure contact force FA between the vibrator1and the friction member2will be described first. As shown inFIG. 5A, the press members13generate pressing forces f in the direction shown inFIG. 5Ato press the vibrator1against the friction member2through the press plate12and the felt member7. Reactive forces of the pressing forces f are then generated. The vibrator1receives the reactive forces from the friction member2. That is, the pressure contact force FA is generated between the moving vibrator1and the fixed friction member2. In addition, as shown inFIG. 5B, the pressure contact force FA between the vibrator1and the friction member2has distribution load areas N1and N2, which are the projected areas of the protruding portions1bof the vibrator1. A load center A is the same as that described above.

A biasing contact force FB between the transmission member18and the abutment part14dwill be described next. As shown inFIG. 5C, when the biasing member19generates a biasing force, the transmission member18is biased by the biasing force to abut against the abutment part14d.As a result, the biasing contact force FB in the direction shown inFIG. 5Cis generated between the moving transmission member18and the abutment part14d.In addition, as shown inFIG. 5D, the biasing contact force FB between the transmission member18and the abutment part14dhas distribution load areas M1and M2, which are the projected areas of the contact areas of the abutment part14dwith respect to a concave portion18aof the transmission member18. A load center B between them is the same as that described above.

In this case, the vibrator1receives the pressing forces f from the press member13through the press plate12and the felt member7, and the moving member14directly receives forces in an opposite direction to the pressing forces f from the press member13. The vibrator1comes into contact with the friction member2, and the position of the moving member14is restricted by the guide members6. When, therefore, the five components, namely the vibrator1, the felt member7, the press plate12, the press members13, and the moving member14are regarded as an integral unit, external forces acting on the unit should balance each other (the above five components regarded as an integral unit will be referred to as a “moving body” hereinafter).

As shown inFIG. 5C, the moving body receives the pressure contact force FA between the vibrator1and the friction member2and the biasing contact force FB between the transmission member18and the abutment part14d.The directions of forces acting on the load centers A and B are opposite to each other. If the pressure contact force FA and the biasing contact force FB are equal in magnitude and the load centers A and B coincide with each other on the projections on an X-Y plane, the moving body can balance with only the pressure contact force FA and the biasing contact force FB, and no drag FR is generated between the moving body and the guide members6. If the pressure contact force FA differs in magnitude from the biasing contact force FB, the moving body cannot balance with only the pressure contact force FA and the biasing contact force FB. In this case, the drag FR corresponding to the difference between the pressure contact force FA and the biasing contact force FB is generated between the moving body and the guide members6in either of the directions inFIG. 5C, in addition to the pressure contact force FA and the biasing contact force FB, thereby allowing the moving body to balance.

Features of Example 1 will be described below. The first feature of Example 1 is that the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB are aligned on a straight line L along a direction Y perpendicular to the moving direction X and a direction Z of the pressure contact force FA, as shown inFIGS. 5B, 5D, and 5E. The second feature of Example 1 is that the direction of the pressure contact force FA and the direction of the biasing contact force FB are parallel and opposite, as shown inFIGS. 5A, 5C, and 5E.

According to the first feature, since no couple V1around the Y-axis shown inFIG. 5Eis generated in the moving body, the moving body can reciprocally move with high position accuracy without tilting around the Y-axis. In addition, according to the second feature, the drag FR generated between the moving member14and the guide members6corresponds to the difference between the pressure contact force FA and the biasing contact force FB, and the drag FR and frictional force are reduced. This can prevent a decrease in the driving force of the vibration wave motor11. In addition, making the pressure contact force FA almost equal to the biasing contact force FB can further reduce the drag FR and the frictional force. This can further prevent a decrease in the driving force of the vibration wave motor11. As a consequence, even if the sliding guide method is used as a guide method, a decrease in the driving force of the vibration wave motor11can be avoided.

As described above, the linear driving apparatus using the vibration wave motor11according to Example 1 can use the sliding guide method as a guiding method for the moving member14, which allows downsizing and simplification without decreasing the driving force of the vibration wave motor11. According to Example 1, as shown inFIGS. 5B and 5D, on the projections on the X-Y plane, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB fall within the range of the vibrator1. In addition, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB are aligned on the straight line L along the direction Y perpendicular to the moving direction X and the direction Z of the pressure contact force FA and almost coincide with each other. In this case, since the couple V2shown inFIG. 5Eis hardly generated, it is possible to reduce the drag FR and frictional force and a decrease in the driving force of the vibration wave motor11to almost 0 by making the pressure contact force FA almost equal to the biasing contact force FB.

The arrangement of a vibration wave motor21according to Example 2 used for the linear driving apparatus according to the embodiment of the present invention will be described.FIGS. 6A and 6Bare exploded perspective views of the vibration wave motor21.FIG. 6Ais a view seen from above in the Z direction.FIG. 6Bis a view seen from below in the Z direction. A vibrator1and a friction member2are the same as those in Example 1. Note however that the friction member2is fixed to a press plate22with screws9. The press plate22is provided with a shaft22aand can pivot about a straight line L22in the R direction shown inFIGS. 6A and 6B.

Press members23are two compression springs, which are assembled such that the lower end portions of the press members23are supported by fixing members8, and the upper end portions are supported by the press plate22. The press members23act on the press plate22to give pressing forces f between the vibrator1and the friction member2in the direction shown inFIGS. 6A and 6B. A moving member24can move in a moving direction X, and supports the vibrator1at a support part24ethrough a felt member7. In addition, the moving member24includes sliding parts24a,24b,and24cas holes to be fitted on guide members6and an abutment part24dagainst which a transmission member18abuts. The coupling member5and the guide members are the same as those in Example 1. The fixing members8are supported by fixing portions (not shown), and are assembled in the X1direction shown inFIG. 6Ato hold the guide members6and the press plate22by fitting them in holes8a.With regard to each component described above, other forms can be selected as in Example 1. The transmission member18and a biasing member19through which the vibration wave motor21used for the linear driving apparatus according to Example 2 transmits a driving force to a driving target body17are the same as those in Example 1, and hence a description of them will be omitted.

Forces generated inside the vibration wave motor21according to Example 2 will be described next.FIGS. 7A and 7Care sectional views, respectively, near an abutment portion between the moving member24and the transmission member18.FIGS. 7B and 7Dare partially enlarged views, respectively, on an X-Y plane.FIG. 7Eis a perspective view. The vibrator1, the felt member7, the moving member24, the transmission member18, and the biasing member19are components which move in the moving direction X, to which the friction member2, the press members23, the guide members6, and the press plate22are fixed.

A pressure contact force FA between the vibrator1and the friction member2will be described first. As shown inFIG. 7A, the press member23generates a pressing force f in the direction shown inFIG. 7Ato press the press plate22and generates a couple in the R direction shown inFIG. 7Aaround the shaft22aof the press plate22. The vibrator1then receives the pressure contact force FA from the friction member2in the direction shown inFIG. 7A. That is, the pressure contact force FA is generated between the moving vibrator1and the fixed friction member2. In addition, as shown inFIG. 7B, distribution load areas N1and N2of the pressure contact force FA between the vibrator1and the friction member2correspond to the projected areas of protruding portions1bof the vibrator1. A load center A between them is the same as that in Example 1.

A biasing contact force FB between the transmission member18and the abutment part24dwill be described next. As shown inFIG. 7C, when the biasing member19generates a biasing force, the transmission member18is biased by the biasing force to abut against the abutment part24d.As a result, the biasing contact force FB in the direction shown inFIG. 7Cis generated between the moving transmission member18and the abutment part24d.In addition, as shown inFIG. 7D, the biasing contact force FB between the transmission member18and the abutment part24dhas distribution load areas M1and M2, which are the projected areas of the contact areas of the abutment part24dwith respect to a concave portion18aof the transmission member18. A load center B between them is the same as that in Example 1.

In this case, the vibrator1receives the pressure contact force FA through the press plate22and the friction member2, and the moving member24directly receives the pressure contact force FA from the felt member7. The vibrator1comes into contact with the friction member2, and the position of the moving member24is restricted by the guide members6. When, therefore, the three components, namely the vibrator1, the felt member7, and the moving member24are regarded as an integral unit, external forces acting on the unit should balance each other (the above three components regarded as an integral unit will be referred to as a “moving body” hereinafter).

As shown inFIG. 7C, the moving body receives the pressure contact force FA between the vibrator1and the friction member2and the biasing contact force FB between the transmission member18and the abutment part24d.The directions of forces acting on the load centers A and B are opposite to each other. If the pressure contact force FA and the biasing contact force FB are equal in magnitude and the load centers A and B coincide with each other on the projections on an X-Y plane, the moving body can balance with only the pressure contact force FA and the biasing contact force FB, and no drag FR is generated between the moving body and the guide members6. If the pressure contact force FA differs in magnitude from the biasing contact force FB, the moving body cannot balance with only the pressure contact force FA and the biasing contact force FB. In this case, the drag FR corresponding to the difference between the pressure contact force FA and the biasing contact force FB is generated between the moving body and the guide members6in either of the directions inFIG. 7C, in addition to the pressure contact force FA and the biasing contact force FB, thereby allowing the moving body to balance.

Features of Example 2 will be described below. The features of the arrangement according to Example 2 are the same as the first and second features of Example 1. Therefore, since no couple V1around the Y-axis shown inFIG. 7Eis generated in the moving body, the moving body can reciprocally move with high position accuracy without tilting around the Y-axis. In addition, the drag FR generated between the moving member24and the guide members6corresponds to the difference between the pressure contact force FA and the biasing contact force FB, and the drag FR and frictional force are reduced. This can prevent a decrease in the driving force of the vibration wave motor21. In addition, making the pressure contact force FA almost equal to the biasing contact force FB can further reduce the drag FR and the frictional force. This can further prevent a decrease in the driving force of the vibration wave motor21. As a consequence, even if the sliding guide method is used as a guide method, a decrease in the driving force of the vibration wave motor21can be avoided.

As described above, the linear driving apparatus using the vibration wave motor21according to Example 2 can use the sliding guide method as a guiding method for the moving member24, which allows downsizing and simplification without decreasing the driving force of the vibration wave motor21. According to Example 2, as shown inFIGS. 7B and 7D, on the projections on the X-Y plane, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB fall within the range of the vibrator1. In addition, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB are aligned on a straight line L along a direction Y perpendicular to a moving direction X and a direction Z of the pressure contact force FA and almost coincide with each other. In this case, since the couple V2shown inFIG. 7Eis hardly generated, it is possible to reduce the drag FR and frictional force and a decrease in the driving force of the vibration wave motor21to almost 0 by making the pressure contact force FA almost equal to the biasing contact force FB.

The arrangement of a vibration wave motor31according to Example 3 used for the linear driving apparatus according to the embodiment of the present invention will be described.FIGS. 8A and 8Bare exploded perspective views, respectively, of the vibration wave motor31.FIG. 8Ais a view seen from above in the Z direction.FIG. 8Bis a view seen from below in the Z direction. A vibrator1and a friction member2are the same as those in Example 1.

Press members33are four compression springs. The lower end portions of the press members33abut against a press plate32and give pressing forces f to the vibrator1in the direction shown inFIGS. 8A and 8Bthrough a felt member7. A moving member34can move in a moving direction X, and holds the upper end portions of the press members33. In addition, the moving member34includes sliding parts34a,34b,and34cas holes to be fitted on guide members6and an abutment part34dagainst which a transmission member18abuts. A coupling member5, the guide members6, and fixing members8are the same as those in Example 1. With regard to each component described above, other forms can be selected as in Example 1. The transmission member18and a biasing member19through which the vibration wave motor31used for the linear driving apparatus according to Example 3 transmits a driving force to a driving target body17are the same as those in Example 1, and hence a description of them will be omitted.

Forces generated inside the vibration wave motor31according to Example 3 will be described next.FIGS. 9A and 9Care sectional views, respectively, near an abutment portion between the moving member34and the transmission member18.FIGS. 9B and 9Dare partially enlarged views, respectively, on an X-Y plane.FIG. 9Eis a perspective view. The vibrator1, a felt member7, the press plate32, the press members33, the moving member34, the transmission member18, and the biasing member19are components which move in the X direction, to which the friction member2and the guide members6are fixed.

A pressure contact force FA between the vibrator1and the friction member2will be described first. As shown inFIG. 9A, the press members33generate the pressing forces f in the direction shown inFIG. 9Ato press the vibrator1against the friction member2through the press plate32and the felt member7. Reactive forces of the pressing forces f are then generated. The vibrator1receives the reactive forces from the friction member2. That is, the pressure contact force FA is generated between the moving vibrator1and the fixed friction member2. In addition, as shown inFIG. 9B, distribution load areas N1and N2of the pressure contact force FA between the vibrator1and the friction member2correspond to the projected areas of protruding portions1bof the vibrator1. A load center A between them is the same as that in Example 1.

A biasing contact force FB between the transmission member18and the abutment part34dwill be described next. As shown inFIG. 9C, when the biasing member19generates a biasing force, the transmission member18is biased by the biasing force to abut against the abutment part34d.As a result, the biasing contact force FB in the direction shown inFIG. 9Cis generated between the moving transmission member18and the abutment part34d.In addition, as shown inFIG. 9D, the biasing contact force FB between the transmission member18and the abutment part34dhas distribution load areas M1and M2, which are the projected areas of the contact areas of the abutment part34dwith respect to a concave portion18aof the transmission member18. A load center B between them is the same as that in Example 1.

In this case, the vibrator1receives the pressing forces f from the press members33through the press plate32and the felt member7, and the moving member34directly receives forces in the opposite direction to the pressing forces f from the press members33. The vibrator1comes into contact with the friction member2, and the position of the moving member34is restricted by the guide members6. When, therefore, the five components, namely the vibrator1, the felt member7, the press plate32, the press members33, and the moving member34are regarded as an integral unit, external forces acting on the unit should balance each other (the above five components regarded as an integral unit will be referred to as a “moving body” hereinafter).

As shown inFIG. 9C, the moving body receives the pressure contact force FA between the vibrator1and the friction member2and the biasing contact force FB between the transmission member18and the abutment part34d.The directions of forces acting on the load centers A and B are opposite to each other. If the pressure contact force FA and the biasing contact force FB are equal in magnitude and the load centers A and B coincide with each other on the projections on an X-Y plane, the moving body can balance with only the pressure contact force FA and the biasing contact force FB, and no drag FR is generated between the moving body and the guide members6. If the pressure contact force FA differs in magnitude from the biasing contact force FB, the moving body cannot balance with only the pressure contact force FA and the biasing contact force FB. In this case, the drag FR corresponding to the difference between the pressure contact force FA and the biasing contact force FB is generated between the moving body and the guide members6in either of the directions inFIG. 9C, in addition to the pressure contact force FA and the biasing contact force FB, thereby allowing the moving body to balance.

Features of Example 3 will be described below. The features of the arrangement according to Example 3 are the same as the first and second features of Example 1. Therefore, since no couple V1around the Y-axis shown inFIG. 9Eis generated in the moving body, the moving body can reciprocally move with high position accuracy without tilting around the Y-axis. In addition, the drag FR generated between the moving member34and the guide members6corresponds to the difference between the pressure contact force FA and the biasing contact force FB, and the drag FR and frictional force are reduced. This can prevent a decrease in the driving force of the vibration wave motor31. In addition, making the pressure contact force FA almost equal to the biasing contact force FB can further reduce the drag FR and the frictional force. This can further prevent a decrease in the driving force of the vibration wave motor31. As a consequence, even if the sliding guide method is used as a guide method, a decrease in the driving force of the vibration wave motor31can be avoided.

As described above, the linear driving apparatus using the vibration wave motor31according to Example 3 can use the sliding guide method as a guiding method for the moving member34, which allows downsizing and simplification without decreasing the driving force of the vibration wave motor31. According to Example 3, as shown inFIGS. 9B and 9D, on the projections on the X-Y plane, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB fall within the range of the vibrator1. In addition, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB are aligned on a straight line L along a direction Y perpendicular to a moving direction X and a direction Z of the pressure contact force FA and almost coincide with each other. In this case, since the couple V2shown inFIG. 9Eis hardly generated, it is possible to reduce the drag FR and frictional force and a decrease in the driving force of the vibration wave motor31to almost 0 by making the pressure contact force FA almost equal to the biasing contact force FB.

The arrangement of a vibration wave motor41according to Example 4 used for the linear driving apparatus according to the embodiment of the present invention will be described.FIGS. 10A and 10Bare exploded perspective views, respectively, of the vibration wave motor41.FIG. 10Ais a view seen from above in the Z direction.FIG. 10Bis a view seen from below in the Z direction. A vibrator1and a friction member2are the same as those in Example 1.

Press members43are four compression springs. The lower end portions of the press members43abut against a press plate42and give pressing forces f to the vibrator1in the direction shown inFIGS. 10A and 10Bthrough a felt member7. A moving member44can move in a moving direction X, and holds the upper end portions of the press members43. In addition, the moving member44includes sliding parts44a,44b,and44cas holes to be fitted on guide members6and an abutment part44dagainst which a transmission member18abuts. A coupling member5, the guide members6, and fixing members8are the same as those in Example 1. With regard to each component described above, other forms can be selected as in Example 1.

The transmission member18and a biasing member19through which the vibration wave motor41used for the linear driving apparatus according to Example 4 transmits a driving force to a driving target body17are the same as those in Example 1, and hence a description of them will be omitted. In Example 4, unlike in Example 3, the press members43and the guide members6are arranged so as to overlap in the Z direction. Arranging the guide members6and press members43so as not to overlap in the Y direction in this manner can achieve downsizing in the Y direction.

Forces generated inside the vibration wave motor41according to Example 4 will be described next.FIGS. 11A and 11Care sectional views, respectively, near an abutment portion between the moving member44and the transmission member18.FIGS. 11B and 11Dare partially enlarged views, respectively, on an X-Y plane.FIG. 11Eis a perspective view. The vibrator1, the felt member7, the press plate42, the press members43, the moving member44, the transmission member18, and the biasing member19are components which move in the X direction, to which the friction member2and the guide members6are fixed.

A pressure contact force FA between the vibrator1and the friction member2will be described first. As shown inFIG. 11A, the press members43generate the pressing forces f in the direction shown inFIG. 11Ato press the vibrator1against the friction member2through the press plate42and the felt member7. Reactive forces of the pressing forces f are then generated. The vibrator1receives the reactive forces from the friction member2. That is, the pressure contact force FA is generated between the moving vibrator1and the fixed friction member2. In addition, as shown inFIG. 11B, distribution load areas N1and N2of the pressure contact force FA between the vibrator1and the friction member2correspond to the projected areas of protruding portions1bof the vibrator1. A load center A between them is the same as that in Example 1.

A biasing contact force FB between the transmission member18and the abutment part44dwill be described next. As shown inFIG. 11C, when the biasing member19generates a biasing force, the transmission member18is biased by the biasing force to abut against the abutment part44d.As a result, the biasing contact force FB in the direction shown inFIG. 11Cis generated between the moving transmission member18and the abutment part44d.In addition, as shown inFIG. 11D, the biasing contact force FB between the transmission member18and the abutment part44dhas distribution load areas M1and M2, which are the projected areas of the contact areas of the abutment part34dwith respect to a concave portion18aof the transmission member18. A load center B between them is the same as that in Example 1.

In this case, the vibrator1receives the pressing forces f from the press members43through the press plate42and the felt member7, and the moving member44directly receives forces in the opposite direction to the pressing forces f from the press members43. The vibrator1comes into contact with the friction member2, and the position of the moving member44is restricted by the guide members6. When, therefore, the five components, namely the vibrator1, the felt member7, the press plate42, the press members43, and the moving member44are regarded as an integral unit, external forces acting on the unit should balance each other (the above five components regarded as an integral unit will be referred to as a “moving body” hereinafter).

As shown inFIG. 11C, the moving body receives the pressure contact force FA between the vibrator1and the friction member2and the biasing contact force FB between the transmission member18and the abutment part44d.The directions of forces acting on the load centers A and B are opposite to each other. If the pressure contact force FA and the biasing contact force FB are equal in magnitude and the load centers A and B coincide with each other on the projections on an X-Y plane, the moving body can balance with only the pressure contact force FA and the biasing contact force FB, and no drag FR is generated between the moving body and the guide members6. If the pressure contact force FA differs in magnitude from the biasing contact force FB, the moving body cannot balance with only the pressure contact force FA and the biasing contact force FB. In this case, the drag FR corresponding to the difference between the pressure contact force FA and the biasing contact force FB is generated between the moving body and the guide members6in either of the directions inFIG. 11C, in addition to the pressure contact force FA and the biasing contact force FB, thereby allowing the moving body to balance.

Features of Example 4 will be described below. The features of the arrangement according to Example 4 are the same as the first and second features of Example 1. Therefore, since no couple V1around the Y-axis shown inFIG. 11Eis generated in the moving body, the moving body can reciprocally move with high position accuracy without tilting around the Y-axis. In addition, the drag FR generated between the moving member44and the guide members6corresponds to the difference between the pressure contact force FA and the biasing contact force FB, and the drag FR and frictional force are reduced. This can prevent a decrease in the driving force of the vibration wave motor41. In addition, making the pressure contact force FA almost equal to the biasing contact force FB can further reduce the drag FR and the frictional force. This can further prevent a decrease in the driving force of the vibration wave motor41. As a consequence, even if the sliding guide method is used as a guide method, a decrease in the driving force of the vibration wave motor41can be avoided.

As described above, the linear driving apparatus using the vibration wave motor41according to Example 4 can use the sliding guide method as a guiding method for the moving member44, which allows downsizing and simplification without decreasing the driving force of the vibration wave motor41. According to Example 4, as shown inFIGS. 11B and 11D, on the projections on the X-Y plane, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB fall within the range of the vibrator1. In addition, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB are aligned on a straight line L along a direction Y perpendicular to a moving direction X and a direction Z of the pressure contact force FA and almost coincide with each other. In this case, since the couple V2shown inFIG. 11Eis hardly generated, it is possible to reduce the drag FR and frictional force and a decrease in the driving force of the vibration wave motor41to almost 0 by making the pressure contact force FA almost equal to the biasing contact force FB.

The arrangement of a vibration wave motor51according to Example 5 used for the linear driving apparatus according to the embodiment of the present invention will be described.FIGS. 12A and 12Bare exploded perspective views, respectively, of the vibration wave motor51.FIG. 12Ais a view seen from above in the Z direction.FIG. 12Bis a view seen from below in the Z direction. A vibrator1and a friction member2are the same as those in Example 1.

Press members53are two compression springs. The lower end portions of the press members53abut against a press plate52and give pressing forces f to the vibrator1in the direction shown inFIGS. 12A and 12Bthrough a felt member7. An engaging portion52aof the press plate52engages with an engaging portion54eof a moving member54and serves as a pivot fulcrum. A moving member54can move in a moving direction X, and holds the upper end portions of the press members53. In addition, the moving member54includes sliding parts54a,54b,and54cas holes to be fitted on guide members6and an abutment part54dagainst which a transmission member18abuts. A coupling member5, the guide members6, and fixing members8are the same as those in Example 1. With regard to each component described above, other forms can be selected as in Example 1.

The transmission member18and a biasing member19through which the vibration wave motor51used for the linear driving apparatus according to Example 5 transmits a driving force to a driving target body17are the same as those in Example 1, and hence a description of them will be omitted. In Example 5, unlike in Example 1 to 4, the vibrator1, the friction member2, and the abutment part54dare arranged on the end portion of the vibration wave motor51in the Y direction. Arranging these components in this manner increases the degree of freedom of the layout of the vibration wave motor51in the linear driving apparatus.

Forces generated inside the vibration wave motor51according to Example 5 will be described next.FIGS. 13A and 13Care sectional views, respectively, near an abutment portion between the moving member54and the transmission member18.FIGS. 13B and 13Dare partially enlarged views, respectively, on an X-Y plane.FIG. 13Eis a perspective view. The vibrator1, the felt member7, the press plate52, the press members53, the moving member54, the transmission member18, and the biasing member19are components which move in the X direction, to which the friction member2and the guide members6are fixed.

A pressure contact force FA between the vibrator1and the friction member2will be described first. As shown inFIG. 13A, the press members53generate the pressing forces f in the direction shown inFIG. 13Ato press the vibrator1against the friction member2through the press plate52and the felt member7. In addition, the press members53act to generate a couple around the engaging portion52ain the R direction shown inFIG. 13A. Reactive forces of the pressing forces f are then generated. The vibrator1receives the reactive forces from the friction member2. That is, the pressure contact force FA is generated between the moving vibrator1and the fixed friction member2. In addition, as shown inFIG. 13B, distribution load areas N1and N2of the pressure contact force FA between the vibrator1and the friction member2correspond to the projected areas of protruding portions1bof the vibrator1. A load center A between them is the same as that in Example 1.

A biasing contact force FB between the transmission member18and the abutment part54dwill be described next. As shown inFIG. 13C, when the biasing member19generates a biasing force, the transmission member18is biased by the biasing force to abut against the abutment part54d.As a result, the biasing contact force FB in the direction shown inFIG. 13Cis generated between the moving transmission member18and the abutment part54d.In addition, as shown inFIG. 13D, the biasing contact force FB between the transmission member18and the abutment part54dhas distribution load areas M1and M2, which are the projected areas of the contact areas of the abutment part54dwith respect to a concave portion18aof the transmission member18. A load center B between them is the same as that in Example 1.

In this case, the vibrator1receives forces in the opposite direction to the pressure contact force FA from the press members53through the press plate52and the felt member7, and the moving member54directly receives forces in the opposite direction to the pressing forces f from the press members53. The vibrator1comes into contact with the friction member2, and the position of the moving member54is restricted by the guide members6. When, therefore, the five components, namely the vibrator1, the felt member7, the press plate52, the press members53, and the moving member54are regarded as an integral unit, external forces acting on the unit should balance each other (the above five components regarded as an integral unit will be referred to as a “moving body” hereinafter).

As shown inFIG. 13C, the moving body receives the pressure contact force FA between the vibrator1and the friction member2and the biasing contact force FB between the transmission member18and the abutment part54d.The directions of forces acting on the load centers A and B are opposite to each other. If the pressure contact force FA and the biasing contact force FB are equal in magnitude and the load centers A and B coincide with each other on the projections on an X-Y plane, the moving body can balance with only the pressure contact force FA and the biasing contact force FB, and no drag FR is generated between the moving body and the guide members6. If the pressure contact force FA differs in magnitude from the biasing contact force FB, the moving body cannot balance with only the pressure contact force FA and the biasing contact force FB. In this case, the drag FR corresponding to the difference between the pressure contact force FA and the biasing contact force FB is generated between the moving body and the guide members6in either of the directions inFIG. 13C, in addition to the pressure contact force FA and the biasing contact force FB, thereby allowing the moving body to balance.

Features of Example 5 will be described below. The features of the arrangement according to Example 5 are the same as the first and second features of Example 1. Therefore, since no couple V1in the X direction shown inFIG. 13Eis generated, the moving body can reciprocally move with high position accuracy without tilting around the X direction. In addition, the drag FR generated between the moving member54and the guide members6corresponds to the difference between the pressure contact force FA and the biasing contact force FB, and the drag FR and frictional force are reduced. This can prevent a decrease in the driving force of the vibration wave motor51. In addition, making the pressure contact force FA almost equal to the biasing contact force FB can further reduce the drag FR and the frictional force. This can further prevent a decrease in the driving force of the vibration wave motor51. As a consequence, even if the sliding guide method is used as a guide method, a decrease in the driving force of the vibration wave motor51can be avoided.

As described above, the linear driving apparatus using the vibration wave motor51according to Example 5 can use the sliding guide method as a guiding method for the moving member54, which allows downsizing and simplification without decreasing the driving force of the vibration wave motor51. According to Example 5, as shown inFIGS. 13B and 13D, on the projections on the X-Y plane, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB fall within the range of the vibrator1. In addition, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB are aligned on a straight line L along a direction Y perpendicular to a moving direction X and a direction Z of the pressure contact force FA and almost coincide with each other. In this case, since the couple V2shown inFIG. 13Eis hardly generated, it is possible to reduce the drag FR and frictional force and a decrease in the driving force of the vibration wave motor51to almost 0 by making the pressure contact force FA almost equal to the biasing contact force FB.

First Modification

FIGS. 14A and 14Bshow the first modification of Examples 1 to 5.FIG. 14Ais a sectional view near an abutment portion between the moving member4and the transmission member18.FIG. 14Bis a partially enlarged view on an X-Y plane. According to the first modification, on the projections on the X-Y plane, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB are aligned in the direction Y perpendicular to the moving direction X and the direction Z of the pressure contact force FA but are not aligned in the moving direction X. That is, the load center A and the load center B do not coincide with each other and are spaced apart from each other to a certain extent. Assume that this degree of separation is defined as a shift amount D1. Note that the shift amount D1is emphatically shown. This arrangement can obtain the effect of reducing the drag FR and frictional force and preventing a decrease in the driving force of the vibration wave motor by reducing the shift amount D1and setting the couple V2generated in the direction shown inFIGS. 14A and 14Bto a very small value. In addition, the presence of the couple V2can shift backlash around the guide members6to one side, and hence the arrangement can obtain the effect of reducing the vibration of the moving member4and preventing the generation of unnecessary vibration and noise of the apparatus.

Second Modification

In addition,FIG. 14Cshows the second modification of Examples 1 to 5.FIG. 14Cis a partially enlarged view on an X-Y plane. According to the second modification, on the projections on the X-Y plane perpendicular to the direction Z, the load center A of the distribution load of the pressure contact force FA and the load center B of the distribution load of the biasing contact force FB fall within the range of the vibrator1but are not aligned in both the moving direction X and the direction Y perpendicular to the moving direction X. Note however that a shift amount D1between the load center A and the load center B in the direction Y perpendicular to the moving direction X and a shift amount D2between them in the moving direction X are emphatically shown. This arrangement can obtain the effect of reducing the drag FR and frictional force and preventing a decrease in the driving force of the vibration wave motor by setting the shift amounts D1and D2to small values. As described above, even if the load center A of the pressure contact force FA and the load center B of the biasing contact force FB are not aligned in either or both of the moving direction X and the direction Y perpendicular to the moving direction X, similar effects can be obtained.

Third Modification

FIG. 15shows the third modification of Examples 1 to 5.FIG. 15is a perspective view of an optical apparatus using the linear driving apparatus using the vibration wave motor10. A driving target body27is a lens frame used for a photographing apparatus as a driving target, to which the vibration wave motor10outputs a driving force, and is featured in that guide holes27con one side are guided along a guide shaft25, and guide holes27bon the other side are guided along the guide member6of the vibration wave motor10. The transmission member18is held by a support portion27a.This arrangement can obtain the effect of reducing the number of components to be used and simplifying the apparatus, and can also obtain the effect of improving the linear motion accuracy because the vibration wave motor10and the driving target body27are guided by the same guide member6. According to the third modification, one guide member6is shared. However, two guide members6can be shared. In the third embodiment, other arrangements can be selected, as in Example 1.

This application claims the benefit of Japanese Patent Application No. 2015-128543, filed Jun. 26, 2015, which is hereby incorporated by reference herein in its entirety.

REFERENCE SIGNS LIST