Vibration actuator, lens barrel and electronic device

Abstract

To improve the durability of a resin film in a vibration actuator.SOLUTION: A vibration actuator includes a vibrator that generates vibration, and a movable body that comes into contact with the vibrator, and moves relatively to the vibrator due to the vibration. Either one of a first surface of the vibrator that comes into contact with the movable body and a second surface of the movable body that comes into contact with the vibrator is made from resin that contains a carbonized material.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vibration actuator, a lens barrel, and an electronic device. [Background technology]

[0002] In conventional vibration actuators, friction at the contact surface between the vibrator and the moving body has a large effect on the drive stability, efficiency, lifespan, etc. of the vibration actuator (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] A vibration actuator according to a first aspect of the technology disclosed in the present application includes a vibrator that generates vibrations, and a moving body that comes into contact with the vibrator and moves relative to the vibrator due to the vibrations, wherein one of a first surface of the vibrator that comes into contact with the moving body and a second surface of the moving body that comes into contact with the vibrator is A polymer alloy containing a resin including polyether ether ketone and plastic, and a carbide. It is formed from resin. Summary of the Invention

[0004] A vibration actuator, which is a first aspect of the technology disclosed in the present application, comprises a vibrator that generates vibrations, and a moving body that contacts the vibrator and moves relative to the vibrator due to the vibration, and one of a first surface of the vibrator that contacts the moving body and a second surface of the moving body that contacts the vibrator is formed from a resin containing carbide.

[0005] A lens barrel according to a second aspect of the technology disclosed in the present application includes a vibration actuator according to the first aspect of the technology disclosed in the present application.

[0006] An electronic device according to a third aspect of the technology disclosed in the present application includes the vibration actuator according to the first aspect of the technology disclosed in the present application. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram showing a camera according to the first embodiment. [Diagram 2] FIG. 2 is an external view showing the ultrasonic motor of the first embodiment. [Diagram 3] FIG. 3 is an enlarged cross-sectional view of a contact portion between an elastic body and a moving body of the ultrasonic motor of the first embodiment. [Figure 4] FIG. 4 is a table showing the measurement results of the compounding ratio of PEEK, PTFE and SiC. [Diagram 5] FIG. 5 is a graph showing the fN characteristics of ultrasonic motors with different compounding ratios of PTFE and SiC. [Figure 6] FIG. 6 is a graph showing the amount of wear of ultrasonic motors having different compounding ratios of PTFE and SiC. [Figure 7] FIG. 7 is a graph showing the holding torque of ultrasonic motors having different compounding ratios of PTFE and SiC. [Figure 8] FIG. 8 is a table showing the measurement results of the yield stress and abrasion resistance of the composite resin film. [Figure 9] FIG. 9 is a table showing the measurement results of the ratio of the average interparticle distances of the composite resin film and the ratio of the wear amount. [Figure 10] FIG. 10 is a cross-sectional view showing an ultrasonic motor according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The vibration actuator according to this embodiment has a vibrator in which an electromechanical conversion element and an elastic body are joined, and generates a progressive vibration wave (hereinafter referred to as a progressive wave) in the elastic body by utilizing the expansion and contraction of the electromechanical conversion element. The vibration actuator frictionally drives a moving body that is in pressure contact with the vibrator with an elliptical motion of about several μm by using this progressive wave. The vibration actuator will be described below with reference to the attached drawings.

[0009] [First embodiment] 1 is an explanatory diagram showing the configuration of a camera according to a first embodiment. In the first embodiment, an ultrasonic motor that uses the vibration range of ultrasonic waves is taken as an example of a vibration actuator. Also, in the first embodiment, a camera is taken as an example of an electronic device.

[0010] Camera 1 includes a camera body 2 having an image sensor 6, and a lens barrel 3. Lens barrel 3 is an interchangeable lens that is detachable from camera body 2. Note that while camera 1 of the first embodiment illustrates an example in which lens barrel 3 is an interchangeable lens, this is not limiting, and for example, lens barrel 3 may be integrated with camera body 2.

[0011] Lens barrel 3 includes a lens 4, a cam barrel 5, and an ultrasonic motor 10. In the first embodiment, ultrasonic motor 10 has, for example, a substantially circular ring shape, and is disposed within lens barrel 3 such that the direction of the central axis of the ring substantially coincides with the optical axis (the direction of arrow A in FIG. 1).

[0012] The ultrasonic motor 10 is used as a drive source that drives the lens 4 during a focusing operation of the camera 1. The driving force obtained from the ultrasonic motor 10 is transmitted to the cam barrel 5. The lens frame 4a of the lens 4 is in cam engagement with the cam barrel 5, and when the driving force of the ultrasonic motor 10 causes the cam barrel 5 to rotate around the optical axis of the lens 4, the lens 4 moves in the optical axis direction to adjust the focus. The ultrasonic motor 10 may also be used as a drive source that drives the lens 4 during a zooming operation of the camera 1.

[0013] 1, a subject image is formed on an imaging surface of an image sensor 6 by a group of lenses (including a lens 4) (not shown) provided in a lens barrel 3. The image sensor 6 converts the formed subject image into an electrical signal, and the signal is A / D converted to obtain image data.

[0014] 2 is an external view showing an ultrasonic motor 10 according to a first embodiment. The ultrasonic motor 10 includes a vibrator 13 having a piezoelectric body 11 and an elastic body 12, a moving body 15, a flexible printed circuit board 14, a vibration absorbing material 16, and a support body 17.

[0015] Piezoelectric body 11 converts electrical energy into mechanical energy. In the first embodiment, a piezoelectric element is used as piezoelectric body 11, but an electrostrictive element may also be used. Piezoelectric body 11 is fixed to support 17 provided on lens barrel 3 via vibration absorbing material 16 such as felt.

[0016] An electrode portion (not shown) is formed on the piezoelectric body 11. The piezoelectric body 11 expands and contracts in response to a drive signal supplied from a flexible printed circuit board 14 electrically connected to the electrode portion, exciting the elastic body 12 to vibrate.

[0017] The elastic body 12 is a member that generates a traveling wave by exciting the piezoelectric body 11. The elastic body 12 is made of an iron alloy such as stainless steel or Invar steel having a high elastic modulus. The elastic body 12 is made of, for example, SUS303. The elastic body 12 is a member having a substantially circular ring shape. The piezoelectric body 11 is bonded to one surface of the elastic body 12 by a conductive adhesive or the like. The other surface of the elastic body 12 is provided with a comb-tooth portion 12a formed by cutting a plurality of grooves 12b.

[0018] The tip surface of the comb-tooth portion 12a is a contact surface that comes into pressure contact with the moving body 15 described below, and the moving body 15 is rotationally driven by a traveling wave generated on this contact surface. On the tip surface of the comb-tooth portion 12a, a composite resin film 18 (see FIG. 3) is formed that is a composite of polytetrafluoroethylene (hereinafter referred to as PTFE), which is an example of a fluororesin, polyether ether ketone (hereinafter referred to as PEEK), which is an example of a binder resin, and silicon carbide (hereinafter referred to as SiC), which is an example of a carbide.

[0019] The moving body 15 is a substantially annular member made of a metal such as stainless steel. The moving body 15 is made of a stainless steel alloy. The moving body 15 is in pressure contact with the vibrator 13 (elastic body 12) and is frictionally driven by a traveling wave. A hard anodized coating layer 19 (see FIG. 3) is formed by anodizing on the contact surface of the moving body 15 with the vibrator 13.

[0020] The flexible printed circuit board 14 is electrically connected to a predetermined electrode portion of the piezoelectric body 11, and is a member that supplies a drive signal to the piezoelectric body 11. A control device 101 that controls the camera 1 is connected to the flexible printed circuit board 14.

[0021] A temperature sensor 102 is connected to the control device 101. The control device 101 adjusts the frequency of the drive signal supplied to the piezoelectric body 11 according to the detection result of the temperature sensor 102 so that the number of rotations of the moving body 15 is constant.

[0022] Fig. 3 is an enlarged cross-sectional view of a contact portion between the elastic body 12 and the moving body 15 of the ultrasonic motor 10 of the first embodiment. Note that Fig. 3 shows an enlarged view of a portion of the cross section of the ultrasonic motor 10 in the circumferential direction.

[0023] A composite resin film 18 is provided on the tip surface of the comb tooth portion 12a, which is the contact surface of the elastic body 12 with the moving body 15. A hard alumite coating layer 19 is provided on the contact surface of the moving body 15 with the elastic body 12. Therefore, the composite resin film 18 and the hard alumite coating layer 19 come into contact in the region where the vibrator 13 and the moving body 15 make frictional contact. The composite resin film 18 is a resin film that is polymer alloyed by applying paint made mainly of PTFE, PEEK, and SiC to the tip surface of the comb tooth portion 12a and baking it at about 350 degrees.

[0024] The composite resin film 18 after firing contains 42 wt% PTFE, 28 wt% PEEK, and 30 wt% SiC. The surface of the composite resin film 18 is polished to about 15 μm, for example. The surface roughness Sa (ISO25278) at that time is 1 μm (measurement range 675 μm×506 μm), and the film thickness after polishing is 30 μm, for example.

[0025] Compared to coatings made from other resins, coatings made from PEEK are superior in hardness, resistance to plastic deformation, adhesion and peel strength, stability of the friction coefficient, abrasion resistance, heat resistance, paint stability, processability, moisture resistance, etc. Furthermore, by forming the composite resin film 18 by combining PTFE and SiC, the following effects (a) to (d) can be expected.

[0026] (a) The composite resin film 18 has higher heat resistance than other resin films such as epoxy resins, which have low heat resistance (heat resistance temperature of 200 degrees or less), and therefore the wear resistance and plastic deformation resistance of the contact surface with the hard anodized coating layer 19 are improved.

[0027] (b) Since the composite resin film 18 contains SiC, which has high hardness and a high elastic modulus, the mechanical properties of the composite resin film 18 are improved.

[0028] (c) By including SiC, the heat resistance and thermal conductivity of the composite resin film 18 are improved, and deterioration of the composite resin film 18 due to frictional heat generated when the ultrasonic motor 10 is driven is suppressed.

[0029] (d) Composite resin film 18 contains PTFE, PEEK, and SiC, and therefore has improved moisture resistance, thereby preventing chemical and physical deterioration of composite resin film 18 due to moisture in the environment.

[0030] For example, if the thickness of the composite resin film 18 is 30 μm, the average particle size of the PTFE contained in the composite resin film 18 is 5 to 10 μm. However, the particle size of the PTFE may be appropriately selected according to the thickness of the composite resin film 18, the mixing characteristics with other raw materials, and the like.

[0031] This PTFE has high lubricating properties compared to other resins, and has the effect of lowering the coefficient of friction and improving the low-speed starting performance of the ultrasonic motor 10. In addition, PTFE has high water repellency compared to other solids (other types of resins and inorganic materials), and can suppress adhesion between the composite resin film 18 and the opposing hard anodized coating layer 19 under high temperature and high humidity conditions (for example, a temperature of 40 degrees or higher and a relative humidity of 80% or higher).

[0032] Since the composite resin film 18 contains SiC, it is preferable that the hard anodized coating layer 19, which is the mating material, is not made of a material that will increase wear due to sliding with the SiC. As the grain size of the SiC increases beyond 11 μm, the surface roughness increases, which becomes an obstacle when driving.

[0033] By including SiC in the composite resin film 18, the strength and density of the coating film are improved compared to when the composite resin film 18 does not include SiC, which has the effect of improving the hardness, resistance to plastic deformation, and modulus of elasticity.

[0034] In addition, the heat generated in the contact surface between the composite resin film 18 and the hard anodized aluminum coating layer 19 due to friction drive is conducted to the outside of the contact surface, so that the retention of heat in the contact surface is suppressed. This reduces the softening of the resin, and improves the drive efficiency.

[0035] Furthermore, SiC increases the coefficient of friction between the vibrator 13 and the moving body 15 (i.e., the coefficient of friction between the composite resin film 18 and the hard anodized coating layer 19), improving the transmission efficiency of the vibrator 13. This has the effect of increasing the holding torque and maximum load torque compared to a case not containing SiC.

[0036] <Example of composite resin film 18 production> The composite resin film 18 is formed through the following steps. First, a degreasing process is performed on the tip surface of the comb-tooth portion 12a of the elastic body 12, which is the contact surface with the movable body 15. At this time, a process for roughening the surface, such as blast etching, may be performed to further improve adhesion.

[0037] PEEK is mixed with PTFE, SiC, and a solvent, and the mixture is stirred to create a solution. This solution is applied to the contact surface of the elastic body 12 (the tip surface of the comb-tooth portion 12a), and after pre-baking, it is left at a high temperature of about 350°C to dry and harden. After hardening, the surface of the composite resin film 18 is polished with an abrasive such as green carborundum to make it flat and reduce the surface roughness.

[0038] On the other hand, the hard anodized coating layer 19 is formed by performing a hard anodizing process on the surface of the moving body 15 formed of an aluminum alloy (A6061). After the hard anodized coating layer 19 is formed, the surface is polished with GC (green carborundum) abrasive paper of grit size #320 to #8000 to give the hard anodized coating layer 19 a desired roughness. For example, it is preferable that the maximum height roughness of the surface of the hard anodized coating layer 19 is in the range of 0.13 to 1.3 μm. If the maximum height roughness is within this range, the composite resin film 18, which is the mating material of friction, is not worn down as much as when it is outside this range.

[0039] Next, the piezoelectric body 11 is bonded to the elastic body 12 on which the composite resin film 18 is formed, to form the vibrator 13. The vibrator 13 and the moving body 15 are arranged so that the composite resin film 18 of the vibrator 13 and the hard anodized coating layer 19 of the moving body 15 are in contact under pressure, and each component is assembled. Through these steps, the ultrasonic motor 10 is produced.

[0040] Here, ultrasonic motors 10 with different compounding ratios of PEEK, PTFE and SiC were prepared, and the f (driving frequency)-N (motor rotation speed) characteristics, the amount of wear of the composite resin film 18, and the holding torque were investigated.

[0041] 4 is a table showing the results of measuring the compounding ratios of PEEK, PTFE, and SiC. In each of Measurement Examples 1 to 7, when the PEEK content in composite resin film 18 is X [wt%], the PTFE content is Y [wt%], and the SiC content is Z [wt%], it is preferable that the following formulas (1) to (4) are satisfied. X + Y + Z = 100 [wt%] (1) 24[wt%]≦Y≦42[wt%]···(2) 15[wt%]≦Z≦30[wt%]···(3) 39[wt%]≦Y+Z≦72[wt%]···(4)

[0042] If the SiC content Z is too low, the durability of the composite resin film 18 will be poor. For example, in measurement example 8, the SiC content Z is lower than 15 [wt%], which does not satisfy the above formulas (3) and (4), and the stability of the wear coefficient was not good. Also, if the PEEK content X is lower than 28 [wt%] or the SiC content Z is higher than 30 [wt%], the performance as a resin will be reduced, and for example, the appearance will be poor.

[0043] When the above formulas (1) to (4) are satisfied, the ultrasonic motor 10 can be manufactured without compromising the durability or resin performance of the composite resin film 18. Furthermore, when 24 [wt%]≦Y≦42 [wt%] and 21 [wt%]≦Z≦30 [wt%], the measurements shown in Figures 5 to 7 below were carried out. To further improve the durability of the composite resin film 18, the SiC content Z was set to 21 [wt%] or more in the measurements shown in Figures 5 to 7.

[0044] Fig. 5 is a graph showing the fN characteristics of ultrasonic motors with different compounding ratios of PTFE and SiC. Fig. 6 is a graph showing the wear amount of ultrasonic motors with different compounding ratios of PTFE and SiC. Fig. 7 is a graph showing the holding torque of ultrasonic motors with different compounding ratios of PTFE and SiC.

[0045] 5 to 7, the horizontal axis represents the PTFE compounding ratio in the composite resin film 18, and the vertical axis represents the SiC compounding ratio in the composite resin film 18. In FIGS. 5 to 7, the center of the concentric circles for each of Measurement Examples 1 to 5 is the point where the PTFE compounding ratio and SiC compounding ratio shown in FIG. 4 are plotted. In addition, in each of Measurement Examples 1 to 5, the numerical values ​​indicating the size (diameter) of the concentric circles represent normalized measured values. The numerical values ​​in bold on the circles for each of Measurement Examples 1 to 5 represent the average values ​​of the measured values ​​for each of Measurement Examples 1 to 5.

[0046] 5 to 7, the number of prototype lots and the number of evaluation pieces differ depending on the blending ratio, so the number of measurements n differs depending on the measurement example. For example, in FIG. 5, the number of measurements n for measurement example 1 is n=2, the number of measurements n for measurement example 2 is n=4, the number of measurements n for measurement example 3 is n=2, the number of measurements n for measurement example 4 is n=1, and the number of measurements n for measurement example 5 is n=4. In FIG. 6 and FIG. 7, the number of measurements n for measurement example 1 is n=2, the number of measurements n for measurement example 2 is n=4, the number of measurements n for measurement example 3 is n=2, the number of measurements n for measurement example 4 is n=2, and the number of measurements n for measurement example 5 is n=4.

[0047] In Figure 5, the measurements showing the size of the concentric circles for Measurement Examples 1 to 5 are proportional to the range of change in the fN characteristics, with smaller measurements indicating higher stability. The number of measurements n for Measurement Example 5 is three: "2.5", "3.0", and "3.5", but since "3.5" was measured twice, the number of measurements n for Measurement Example 5 is n = 4. Looking at the average values, the order of stability is highest (smallest average value) for Measurement Examples 3, 5, 4, 1, and 2.

[0048] In Fig. 6, the size of the concentric circles in Measurement Examples 1 to 5 is proportional to the amount of wear of the composite resin film 18, and the smaller the size, the less the amount of wear, i.e., the better the result. The number of measurements n in Measurement Example 2 is three measured values ​​of "22.0", "25.0", and "35.0", but since "25.0" was measured twice, the number of measurements n in Measurement Example 2 is n = 4. Looking at the average values ​​in Fig. 6, the amount of wear is least (better) in the order of Measurement Examples 5, 4, 3, 2, and 1.

[0049] 7, the size of the concentric circles in Measurement Examples 1 to 5 is proportional to the magnitude of the holding torque of the ultrasonic motor 10, and the larger the value, the better the result is, with the target value being "10.5." The target value is, for example, the holding torque of an ultrasonic motor to which the composite resin film 18 is not applied.

[0050] The number of measurements n in measurement example 2 is three, 12.5, 13.5, and 15.0, but 13.5 was measured twice, so the number of measurements n in measurement example 2 is n = 4. The number of measurements n in measurement example 4 is one, 18.0, but 18.0 was measured twice, so the number of measurements n in measurement example 4 is n = 2. The number of measurements n in measurement example 5 is two, 13.5 and 14.0, but 13.5 was measured three times, so the number of measurements n in measurement example 4 is n = 4. In FIG. 7, the average values ​​of all of measurement examples 1 to 5 exceed the target value.

[0051] From the results shown in FIG. 5 to FIG. 7, it can be seen that Measurement Examples 3, 4, and 5 are better than Measurement Examples 1 and 2 when the fN characteristics, wear amount, and holding torque are taken into consideration.

[0052] SiC and PTFE contribute to suppressing changes in performance such as wear resistance and durability. Therefore, the more the percentage of the sum of the PTFE content Y and the SiC content Z in the overall compounding ratio of PEEK, PTFE, and SiC increases, the better the fN characteristics and wear volume become. For example, the sum of the PTFE content Y and the SiC content Z shown in FIG. 4 is 54 [wt%] in Measurement Example 1 and 45 [wt%] in Measurement Example 2, while it is 66 [wt%] in Measurement Example 3, 57 [wt%] in Measurement Example 4, and 72 [wt%] in Measurement Example 5. Therefore, the more the sum of the PTFE content Y and the SiC content Z is 57 [wt%] or more by weight (PEEK is 43 wt% or less by weight), the more stable the fN characteristics are, the more the wear volume is reduced, and the more the durability is improved.

[0053] It is also seen that the range of 36 to 42 [wt %] of PTFE, which is a fluororesin, is better, and the range of 21 to 30 [wt %] of SiC is better.

[0054] Moreover, from the results shown in Figs. 5 to 7, it can be seen that, taking into consideration the fN characteristics, wear amount, and holding torque, Measurement Example 5 is better than Measurement Examples 1 to 4. In Measurement Example 5, the PEEK content rate X is lower than each of the PTFE content rate Y and the SiC content rate Z. In other words, in Measurement Example 5, the PTFE content rate Y and the SiC content rate Z are each higher than the PEEK content rate X. Measurement Example 5, in which the PEEK content rate X is lower than each of the PTFE content rate Y and the SiC content rate Z, has stable fN characteristics, reduced wear amount, and improved durability compared to Measurement Examples 1 to 4, which are not.

[0055] In addition, if the compounding ratio (Y+Z) of PTFE and SiC is increased beyond that of Measurement Example 5 (72 [wt%]), the amount of PEEK, which is the binder component, decreases, making it difficult to form a composite material of PTFE and SiC. Therefore, 39 [wt%]%≦Y+Z≦72 [wt%] is favorable for generating the composite resin film 18.

[0056] 8 is a table showing the measurement results of the yield stress and abrasion resistance of the composite resin film 18. The composite resin film 18 interposed between the vibrator 13 and the moving body 15 is pressurized by a spring or the like. The value of the pressing force may be determined by dividing the required torque by the friction coefficient of the contact surface where the composite resin film 18 comes into contact with the hard anodized coating layer 19.

[0057] Increasing the pressure may increase wear, but it is desirable that the amount of wear in the composite resin film 18 does not become a problem even if the pressure is increased to increase the torque. Therefore, the yield contact pressure, which is one of the parameters of the strength of the composite resin film 18, was measured by indentation method. The yield contact pressure decreases as Y in the above formula (1) increases, and increases as Z increases. When Y=24[wt%] and 39[wt%]≦Y+Z≦54[wt%], the yield contact pressure is 60[MPa] or more.

[0058] For example, if the surface pressure is smaller than the yield contact pressure measured for each material (Measurement Examples 9 and 10), the material will not yield. The composite resin film 18 of Measurement Example 9 contains PEEK, which is an example of a binder resin, PTFE, and SiC, which is an example of an inorganic material (the same applies to Measurement Examples 11 and 12 described below). The compounding ratio of PEEK, PTFE, and SiC in Measurement Example 9 is the same as in Measurement Example 2.

[0059] The composite resin film 18 of Measurement Example 10 contains polyamideimide (PAI), which is an example of a binder resin, PTFE, and SiC, which is an example of an inorganic material. The compounding ratio of Measurement Example 10 is the same as that of Measurement Example 9, except that PAI is used instead of PEEK. PAI has inferior abrasion resistance to PEEK and is effective only when the applied surface pressure is smaller than its yield contact pressure, so the range of use is limited.

[0060] When the materials of Measurement Example 9 and Measurement Example 10 were subjected to friction sliding under a pressure greater than the yield contact pressure, a difference in the amount of wear was observed. Measurement Example 9 had good wear resistance, and it was revealed that the resin film of Measurement Example 9, which has the same components as this embodiment, can withstand a pressure of 50 MPa or less, even when considering the variation in the yield contact pressure.

[0061] FIG. 9 is a table showing the measurement results of the ratio of the average interparticle distance of the composite resin film 18 and the ratio of the wear amount. Measurement examples 11 and 12 are samples with the same compounding ratio of PEEK, PTFE, and SiC as measurement example 9. In measurement examples 11 and 12, among the composite resin films 18 laid on the contact surface where the composite resin film 18 of the ultrasonic motor 10 contacts the hard anodized coating layer 19, those with a wide average interparticle distance of PTFE had more wear. Even if the compounding ratio of PEEK, PTFE, and SiC is the same, the wear amount tends to increase when the interparticle distance is wide. The average interparticle distance from the center of gravity of the PTFE particles was 12 μm on average when measured by the triangulation method.

[0062] The triangulation method is a method in which observed images of PTFE particle groups are processed and computer-analyzed to generate triangles by connecting the centers of gravity of adjacent particles with lines, and the average distance between particles is calculated. The average distance between particles is the average value estimated when the distribution of interparticle distances is a log-normal distribution.

[0063] In the case of measurement example 2, the average distance between PTFE particles and the center of gravity was 9 μm on average when measured by triangulation, and the distance variance was 7 μm. The average distance between SiC particles and the center of gravity was 18 μm on average when measured by triangulation, and the distance variance was 9 μm.

[0064] In addition, in the case of measurement example 5, the average distance between the particles of PTFE from the particle center of gravity was 12 [μm] on average when measured by triangulation method, and the distance variance was 9 [μm]. The average distance between the particles of SiC from the particle center of gravity was 16 [μm] on average when measured by triangulation method, and the distance variance was 8 [μm]. Regarding the average distance between the particles of SiC from the particle center of gravity, the wider the average distance between the particles, the greater the amount of wear, so if the average distance between the particles of SiC from the particle center of gravity is in the range of 12 to 16 [μm], the wear resistance will be good, as in the case of PTFE.

[0065] In this way, the composite resin film 18 of the first embodiment contains a carbon material such as SiC, and therefore, compared to, for example, polytetrafluoroethylene resin, the durability of the composite resin film 18 is improved and wear can be reduced.

[0066] Furthermore, the composite resin film 18 is different from a SiC film made of SiC alone. In the case of a SiC film, for example, it is necessary to form a SiC film on the elastic body 12 using a PI-CVD device using plasma, but since the composite resin film 18 is a resin, it can be easily applied to the elastic body 12, for example, by brushing. This makes it easier to manufacture the ultrasonic motor 10.

[0067] Furthermore, compared to, for example, polytetrafluoroethylene resin, even if the composite resin film 18 is pressurized and pressed between the elastic body 12 and the moving body 15 and comes into contact with the opposing surface, damage and falling off of the composite resin film 18 is reduced when the moving body 15 is frictionally driven. Reducing damage and falling off of the composite resin film 18 reduces the generation of abnormal noise even if the frequency-rotation speed characteristics change when the ultrasonic motor 10 is driven. Therefore, the ultrasonic motor 10 becomes easier to start, and deterioration of the drive efficiency and service life can be suppressed.

[0068] That is, by using the composite resin film 18 for the ultrasonic motor 10, the occurrence of frictional wear under pressure contact can be suppressed, and the ultrasonic motor 10 can be kept quiet.

[0069] In addition, since the composite resin film 18 has a higher thermal conductivity and thermal diffusivity than, for example, polytetrafluoroethylene resin, the increase in the contact surface temperature due to the generated frictional heat is suppressed. Therefore, the composite resin film 18, which forms the frictional contact surface, is prevented from becoming rough, and the elliptical motion on the order of μm generated in the vibrator 13 can smoothly move the relative moving body.

[0070] Furthermore, compared to, for example, polytetrafluoroethylene resin, the composite resin film 18 can maintain the friction and wear characteristics, frequency-rotation characteristics, and thrust and torque-rotation speed characteristics as a friction material even if the mechanical characteristics change due to moisture absorption.

[0071] Therefore, in the first embodiment, it is possible to provide a vibration actuator, a lens barrel 3, and an electronic device that are easy to manufacture, do not produce abnormal noise, have good and stable driving performance, have excellent environmental resistance, and have improved durability under pressure.

[0072] [Second embodiment] 10 is a cross-sectional view showing an ultrasonic motor 20 according to the second embodiment. The ultrasonic motor 20 is provided in the lens barrel 3 of the camera 1 similar to the ultrasonic motor 10 of the first embodiment, and is used as a drive source for driving the lens 4 when performing focusing and zooming operations. The ultrasonic motor 20 differs from the first embodiment in that it transmits drive force to a cam barrel (not shown) via a gear (not shown) to drive the lens 4 held by the cam barrel.

[0073] The ultrasonic motor 20 includes a vibrator 23, a moving body 25, an output shaft 28, and a pressure unit 29. The vibrator 23 is a substantially annular member having an elastic body 22 and a piezoelectric body 21 joined to the elastic body 22. The vibrator 23 generates a traveling wave by the expansion and contraction of the piezoelectric body 21.

[0074] The elastic body 22 is a substantially annular member made of stainless steel. The piezoelectric body 21 is bonded to one surface of the elastic body 22, and the other surface is provided with a comb-tooth portion 22a formed by cutting a plurality of grooves in the circumferential direction. The tip surface of the comb-tooth portion 22a is a contact surface that is in pressure contact with the moving body 25, and drives the moving body 25 in contact with this contact surface by a traveling wave.

[0075] Similar to the vibrator 13 shown in the first embodiment, a composite resin film 31 is formed on the contact surface of the vibrator 23 with the moving body 25. The composite resin film 31 is formed of the same resin film as that in the measurement example 1 of Fig. 4. The thickness of the composite resin film 31 is 30 [μm].

[0076] The elastic body 22 has a brim-shaped flange portion 22b formed by extending in the radial direction on its inner periphery side, and is supported by a support body 26 by this flange portion 22b.

[0077] The piezoelectric body 21 has a function of converting electrical energy into mechanical energy. As in the first embodiment, a piezoelectric element is used as the piezoelectric body 21, but an electrostrictive element may also be used. An electrode portion (not shown) is formed on the piezoelectric body 21. The piezoelectric body 21 expands and contracts in response to a drive signal supplied from a flexible printed circuit board 24 electrically connected to the electrode portion, causing the elastic body 22 to vibrate.

[0078] A control device 201 that controls a camera equipped with an ultrasonic motor 20 is connected to the flexible printed circuit board 24. A temperature sensor 202 is connected to the control device 201. The control device 201 adjusts the frequency of a drive signal supplied to the piezoelectric body 21 according to the detection result of the temperature sensor 202 so that the number of rotations of the moving body 25 is constant.

[0079] The moving body 25 is in pressure contact with the vibrator 23, and is rotationally driven by elliptical motion caused by a traveling wave generated on the tip surface of the comb tooth portion 22a, which is the contact surface of the vibrator 23. The moving body 25 is a member made of stainless steel. The moving body 25 is fitted to an output shaft 28. The moving body 25 is made of an aluminum alloy, and a hard anodized coating layer 32 is formed on the contact surface of the moving body 25 with the vibrator 23. Therefore, in the region where the moving body 25 and the vibrator 23 make frictional contact, the hard anodized coating layer 32 and the composite resin film 31 are in contact with each other. The composite resin film 31 is the same resin film as the composite resin film 18 of the first embodiment.

[0080] The output shaft 28 has a substantially cylindrical shape. One end of the output shaft 28 is fitted to the moving body 25 via a rubber member 30. The other end of the output shaft 28 is rotatably attached to the support body 26 via a bearing 27. The output shaft 28 rotates integrally with the moving body 25, and transmits the rotational motion of the moving body 25 to a driven member such as a gear (not shown).

[0081] The pressure applying unit 29 is a mechanism for applying pressure to the vibrator 23 and the moving body 25. The pressure applying unit 29 has a spring 29a, a pressing ring 29b, a pressing ring 29c, and an E-ring 29d. The spring 29a generates a pressing force. The pressing ring 29b is disposed in contact with the bearing 27 and presses one end of the spring 29a. The E-ring 29d is inserted into a groove formed in the output shaft 28 and regulates the position of the pressing ring 29c.

[0082] In the ultrasonic motor 20, by forming a composite resin film 31 on the frictional contact surface of the vibrator 23, it is possible to reduce the amount of wear, reduce abnormal noise, improve durability, stabilize driving performance, and improve starting characteristics.

[0083] Furthermore, since the ultrasonic motor 20 is often manufactured as a small ultrasonic motor having a smaller diameter than the ultrasonic motor 10 of the first embodiment, heat generation becomes a problem. However, according to the second embodiment, the composite resin film 31 of measurement example 5 is excellent in heat dissipation because it uses SiC.

[0084] In addition, in each of the above embodiments, a hard alumite coating is shown as the sliding film (composite resin film 18, 31) of the movable body 15, 25, but the present invention is not limited to this, and may be a coating formed by other manufacturing methods such as surface treatments such as hard chrome plating and electroless nickel (composite) plating, PVD (vacuum deposition, sputtering, etc.), CVD, thermal spraying, epitaxial, and electrodeposition. Also, a metal (alloy) alone may be used without a coating, or a resin coating may be used. A composite coating may be used in which hard alumite or electroless nickel plating is formed on a base treatment.

[0085] In each of the above embodiments, the composite resin films 18, 31 are formed on the contact surfaces (tip surfaces of the comb teeth 12a, 22a) of the vibrators 13, 23, but the present invention is not limited to this, and the composite resin films 18, 31 may be formed on the contact surfaces of the moving bodies 15, 25. In addition, the composite resin films 18, 31 may be formed on both the contact surfaces of the vibrators 13, 23 and the contact surfaces of the moving bodies 15, 25.

[0086] Furthermore, the present invention may be applied to a vibration actuator in which the piezoelectric bodies 11, 21 and the moving bodies 15, 25 are in frictional contact with each other without using the elastic bodies 12, 22. In this case, the composite resin film 18, 31 may be formed on at least one of the contact surfaces of the piezoelectric bodies 11, 21 with the moving bodies 15, 25 and the contact surfaces of the moving bodies 15, 25 with the piezoelectric bodies 11, 21.

[0087] In the above embodiments, stainless steel is used as the material for forming the elastic bodies 12 and 22, but other iron-based materials may be used. For example, various iron and steel materials such as SUS440C, S15C, S55C, SCr445, SNCM630, etc. Copper alloys such as phosphor bronze, and aluminum-based alloys may also be used.

[0088] In addition, in each of the above embodiments, the movable bodies 15, 25 are formed from an aluminum alloy, but the present invention is not limited to this, and may be formed from an iron-based material, a stainless steel alloy, phosphor bronze, etc. For example, various steel materials such as SUS440C, S15C, S55C, SCr445, SNCM630, etc. may be used.

[0089] In addition, in each of the above embodiments, an example in which PTFE is used as the fluororesin is shown, but the present invention is not limited to this, and an appropriate fluororesin may be appropriately selected and used. For example, PFA (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PCTFE (polychloro-trifluoroethylene copolymer), ETFE (ethylene tetrafluoroethylene copolymer), ECTFE (ethylene chlorotrifluoroethylene copolymer), PVDF (polyvinylidene fluoride), PVF (polyvinylfluoride), etc. may be mentioned. Also, each functional group may be changed.

[0090] In the above-described embodiments, the composite resin film 18, 31 contains SiC as an example of a carbon material. However, the present invention is not limited to this, and may contain SiC, WC, B 4 Carbides such as C, TaC, TiC, NbC, ZrC, and VC may also be used.

[0091] In addition, the composite resin films 18, 31 in the above embodiments are formed by applying paint containing PEEK as one of the main raw materials to the tip surfaces of the comb teeth 12a, 22a and baking the paint to form a polymer alloy resin film, but modified PEEK may be used instead of PEEK. Modified PEEK is a resin in which the properties of PEEK have been modified, and is, for example, a resin in which PEEK is polymer alloyed with other resins such as PPS (Poly Phenylene Sulfide Resin) or PES (Polyethersulfone).

[0092] By using modified PEEK, the adhesion to the elastic body 12 and the hard anodized coating layer 19 is improved compared to unmodified PEEK, and the cost is reduced compared to unmodified PEEK.

[0093] In addition, in each of the above embodiments, the ultrasonic motors 10, 20 in which the moving bodies 15, 25 are rotationally driven are shown, but this is not limiting, and a linear drive type vibration actuator in which the vibrators 13, 23 or the moving bodies 15, 25 are driven in a linear direction may also be used.

[0094] Further, in each of the above embodiments, an ultrasonic motor that uses vibrations in the ultrasonic range has been described as an example, but the present invention is not limited to this and may be applied to, for example, a vibration actuator that uses vibrations outside the ultrasonic range.

[0095] In addition, in each of the above embodiments, the ultrasonic motors 10 and 20 are used as a driving source for performing a focus operation of the lens barrel 3 of the camera 1, but this is not limited thereto, and the ultrasonic motors 10 and 20 may be used, for example, as a driving source for performing a zoom operation of the lens barrel 3.

[0096] In addition, the ultrasonic motors 10, 20 may be used as driving sources or drive parts for various electronic devices other than the camera 1, such as driving sources for copiers, drive parts for steering wheel tilt devices and headrests in automobiles, drive parts for various medical devices, especially MRIs which are sensitive to the generation of magnetism, and drive parts for robots and nursing suits.

[0097] As described above, according to each of the above embodiments, it is possible to provide a vibration actuator, a lens barrel 3, and an electronic device that are easy to manufacture, reduce the generation of abnormal noise, have good and stable driving performance, and have improved durability.

[0098] The above-described embodiments and their modifications may be used in combination as appropriate, but detailed description thereof will be omitted. The present invention is not limited to the above-described embodiments. [Explanation of symbols]

[0099] 1: camera, 3: lens barrel 3, 10, 20: ultrasonic motor, 11, 21: piezoelectric body, 12, 22: elastic body, 13, 23: transducer, 15, 25: moving body, 18, 31: composite resin film

Claims

1. A vibrator that generates vibrations; a moving body that comes into contact with the vibrator and moves relative to the vibrator due to the vibration; Equipped with One of a first surface of the vibrator in contact with the moving body and a second surface of the moving body in contact with the vibrator is formed of a polymer alloy resin including a resin containing polyether ether ketone and plastic, and a carbide. Vibration actuator.

2. 2. The vibration actuator according to claim 1, The resin contains 15% by weight or more of the carbonized material. Vibration actuator.

3. 3. The vibration actuator according to claim 2, The resin contains 21 to 30% by weight of the carbonized material. Vibration actuator.

4. 4. The vibration actuator according to claim 1, The carbide is SiC. Vibration actuator.

5. 5. The vibration actuator according to claim 1, The resin includes a fluororesin. Vibration actuator.

6. 6. The vibration actuator according to claim 5, The resin contains 24% by weight or more of the fluororesin. Vibration actuator.

7. 7. The vibration actuator according to claim 6, The resin contains 36 to 42% by weight of the fluororesin. Vibration actuator.

8. 8. The vibration actuator according to claim 5, The resin contains the carbide and the fluororesin in an amount of 57% by weight or more. Vibration actuator.

9. 9. A vibration actuator according to claim 5, The content of the polyether ether ketone is lower than the content of the fluororesin and the content of the carbide. Vibration actuator.

10. 10. The vibration actuator according to claim 5, When the content of the substance other than the fluororesin and the carbide in the resin is X, the content of the fluororesin is Y, and the content of the carbide is Z, X+Y+Z=100% by weight, 24% by weight≦Y≦42% by weight, 15% by weight≦Z≦30% by weight, 39% by weight≦Y+Z≦72% by weight, Fulfilling Vibration actuator.

11. 11. The vibration actuator according to claim 5, The average distance between the particles of the fluororesin from the particle center of gravity by triangulation method is 9 to 12 μm. Vibration actuator.

12. 12. A vibration actuator according to claim 5, The average distance between particles of the carbide from the particle center of gravity by triangulation method is 12 to 16 μm. Vibration actuator.

13. A vibration actuator comprising: a vibration actuator according to any one of claims 1 to 12; Lens barrel.

14. A vibration actuator comprising: a vibration actuator according to any one of claims 1 to 12; electronic equipment.

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