JP2014212610A - Vibration type actuator, driving unit, sheet conveying device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration type actuator that can configure means for generating pressure between a vibrator and a rotating body simply at low costs, and has few constraints on the rotating body to be rotated.SOLUTION: A vibration type actuator 170 having a plate-like member 172 with a piezoelectric element 174 fixed thereto and driving the piezoelectric element 174 to rotate a rotating body 161 to which the plate-like member 172 is brought into contact, is configured as follows: the plate-like member 172 is composed of a metallic material having elasticity such as duralumin and is provided with a through-hole part 175; the through-hole part 175 is provided with two protrusions 173 that are in contact with the rotating body 161 that is arranged in the through-hole part 175 with the rotation shaft in a posture parallel with the thickness direction of the plate-like member 172; the protrusions 173 are applied with pressure toward the rotation shaft of the rotating body 161 by an elastic force due to the elastic deformation of the plate-like member 172, and is moved along an elliptical locus by the drive of the piezoelectric element 174.

Description

  The present invention relates to a vibration type actuator, a driving device including the vibration type actuator, a sheet conveying device including the driving device, and an image forming apparatus including the sheet conveying device.

Conventionally, a sheet conveying device provided in an image forming apparatus has a sheet conveyed between a pair of rollers and rollers that are rotated and driven, or a belt that rotates using suction or electric charge. Various types of sheet conveying apparatuses are known, such as those that are conveyed. In particular, roller and roller pairs are often used because of their cost and simplicity of structure, and as drive devices for rotationally driving these, motors of a type using a magnetic field and a coil such as a stepping motor and a DC motor are mainly used. is there. However, this type of motor has a drawback that if the size of the motor is reduced in order to reduce the size of the drive device, the output becomes smaller than the size.
On the other hand, there has been known a small drive device equipped with a vibration type actuator using a piezoelectric element or the like, and this vibration type actuator has a small drive that does not change in size efficiency even if the size is reduced. It is an excellent technology in the field of equipment.

The vibration type actuator generates a motion of an elliptical locus (hereinafter referred to as an elliptical motion) in a part of a vibrating body (stator), and drives the workpiece by pressing the portion that performs the elliptical motion against a workpiece that is a driving object. That's it.
As a vibration type actuator that rotates a rotor that is a rotating body, a method of generating an elliptical motion by generating a traveling wave in an annular vibrating body (hereinafter referred to as a traveling wave type) is generally used.
On the other hand, when performing linear drive, such as stage drive, a system in which two resonances are generated simultaneously in the vibrating body and the workpiece is operated by elliptical motion obtained by synthesizing the vibration profile at the time of resonance (hereinafter referred to as resonance synthesis type). Many).

  The traveling wave type has a slightly complicated structure because it is necessary to regularly attach a large number of piezoelectric elements to the stator ring, which is a vibrating body, as compared with the resonance synthesis type. In addition, since the resonance synthesis type can selectively use a portion having a large amplitude at the time of design depending on the design, the driving speed can be increased as compared with the traveling wave type. For these reasons, in recent years, a resonance synthesis type vibration actuator that rotates a rotor, which is a rotating body, has also been proposed.

For example, Patent Document 1 describes a driving device including the following vibration type actuator. Four vibrating bodies having a piezoelectric element and a rectangular plate member (reinforcing plate) to which the piezoelectric element is fixed on the front and back are joined in a cross shape so that the front and back surfaces are substantially the same surface. The center of this joint is used as the fixed point of vibration of each vibrator that vibrates in the plane direction. Each plate-like member and the piezoelectric element have the same shape, and the ground electrode is provided on the entire surface of the plate-like member side of the front and back piezoelectric elements, and the width direction (short side direction) is a groove symmetrically on the opposite side. There are three divided regions, and an application electrode is provided in each of the center and one region. The application electrodes of the two vibrators joined on the same straight line via the joint are arranged so as to be point-symmetric with respect to the fixed point of the joint, and the two adjacent vibrators are applied to the application electrodes. The region where the electrode is provided or the region where the electrode is not provided is arranged so as to face each other.
Then, by applying a predetermined alternating voltage to the application electrode of each vibration body, each region of the piezoelectric element provided with the application electrode expands and contracts in the plane, and the side of the application side of each vibration body provided with the application electrode A free end (hereinafter referred to as a contact portion) is configured to perform elliptical motion in the same direction within the surface.

In addition, two adjacent vibrating bodies are configured as two pairs, and holding members for holding the vibrating body are bonded to the front and back in the vicinity of the fixed point of the joint portion where each vibrating body is bonded. A certain shaft portion is provided.
Two support frames are provided by a spring mechanism that is a pressurizing means having a compression spring while guiding the shaft portion with a long hole provided in two support frames arranged opposite to each other as a support member of the driving device. The pressure is applied toward the rotating shaft of a cylindrical rotor that is supported rotatably. By applying pressure in this way, at least one of the contact portions of a pair of adjacent vibrators is brought into contact with the outer peripheral surface of the rotor, which is a rotating body, and the frictional force between the contact portion and the outer peripheral surface of the rotor is used. The elliptical motion of the contact portion is transmitted to the rotor and the rotor is rotated.

  Japanese Patent Application Laid-Open No. H10-228561 describes a drive device including the following vibration type actuator. A disc-shaped vibrating body (stator) using a piezoelectric element (piezoelectric ceramics) is formed of two disc members that are provided with a coaxial hole at the center and sandwich the vicinity of the inner peripheral end of the hole from the front and back sides. It is the structure which arrange | positions a rotary body (rotor) so that the center of a hole and the rotation center of a rotary body may become coaxial. In addition, the inner circumferential end of the vibrating body is provided with a contact portion that is formed obliquely on both the front and back over the entire circumference, and the two disk members constituting the rotating body are arranged obliquely on the front and back of the vibrating body. A tapered portion is formed so that the diameter increases in a direction away from the joint surface side so as to sandwich the portion. One of the disk members of the rotating body is provided with a rotation shaft that is coaxial with the center of rotation, and is screwed to the other disk at four locations, so that it is formed near the inner peripheral end of the diaphragm. Further, it is configured so that the diagonal portions of the front and back sides are sandwiched between the respective tapered portions.

In addition, each taper portion of the rotating body has a V-shape on a position near the end on the joint surface side (near the start point of the taper portion) that is on the outer peripheral side of the portion where the screw is fastened, and on a surface facing this position. A notch (hinge portion) is formed over the entire circumference. By forming a V-shaped notch in each disk member in this manner, when the screw is fastened by sandwiching the vicinity of the inner peripheral end of the vibration body, the vibration body is formed at the taper portion by the elastic force of each disk member. This is to pressurize the diagonal parts of the front and back of the.
Then, by driving the piezoelectric element included in the vibrating body, the vibration generated in the in-plane direction of the vibrating body is transmitted to the rotating body by the frictional force obtained by pressurizing the vibrating body with the tapered portion, The rotating body is rotated.

In the vibration type actuator described in Patent Document 1, the four vibrating bodies joined in a cross shape at the joint function as one vibrating body, and each piezoelectric element is divided into three divided application electrodes in the center and one region. It is considered that a plurality of resonances are generated simultaneously by applying an alternating voltage to each of the two. That is, it is considered that this is a resonance synthesis type in which two resonances are simultaneously generated in the vibrating body, and the rotating body that is the driven object is operated by the elliptical motion obtained by the synthesis of the resonance profiles.
On the other hand, although the vibration type actuator described in Patent Document 2 is not described regarding the specific arrangement of the electrodes of the piezoelectric element, the entire circumference of the contact portion of the vibrating body that performs in-plane vibration is provided on the rotating body. It is described that the rotating body rotates while being sandwiched between the tapered portions. From this, the vibration type actuator described in Patent Document 1 is a traveling wave type in which a traveling wave is generated in the vibrating body by driving a piezoelectric element to generate an elliptical motion and the rotating body is rotated. Conceivable.

Here, in any type of vibration type actuator, in order to efficiently transmit the power of the elliptical motion of the vibrating body to the rotating body, a frictional force is applied between the contact portion of the vibrating body (plate member) and the rotating body. A means for applying an appropriate pressure to be generated is essential.
In particular, the vibration type actuator disclosed in Patent Document 1 generates a frictional force by applying an appropriate pressure between the contact portion of the vibrating body and the rotating body, and causes the contact portion of the vibrating body to be generated by driving the piezoelectric element. The force in the intended direction of the elliptical motion is transmitted to the rotating body as a driving force to rotate the rotating body. On the other hand, if the applied pressure is too high, a force in the direction opposite to the intended direction of the elliptical motion is transmitted to the rotating body, the driving force in the intended direction is attenuated, and the driving speed of the rotating body is reduced. The driving speed, that is, the driving force for rotating the rotating body is not stable. Therefore, in the configuration in which the vibrating body is pressurized to the rotating body to generate pressure between the contact portion of the vibrating body and the rotating body as in Patent Document 1, an appropriate pressure is stably applied to the vibrating body. Thus, a pressurizing means such as a spring mechanism that pressurizes the vibrating body toward the rotating body is indispensable and important.

  However, the drive device described in Patent Document 1 includes a spring mechanism that is a pressurizing means as a means for generating pressure between the contact portion of the vibrating body and the rotating body. This spring mechanism is as follows. It has a complicated structure. One end of the compression spring is in contact with the shaft that is the holding member of the vibrating body, and the other end is in contact with the flat portion of the urging portion provided on the support member, and is wound around the protruding portion formed in the urging portion. The shaft portion that holds the vibrating body is pressed against the rotor that is the rotating body by the elastic force of the compression spring.

In the driving device described in Patent Document 1, the configuration of the pressurizing unit is complicated as described above, so that the number of constituent members increases, and the shafts that are the contact portions and holding members of the constituent members. Wear may occur at the frictional part between the part and the long hole of the support member. When wear occurs in a plurality of components as described above, errors overlap and a desired applied pressure, that is, a desired pressure between the contact portion of the vibrating body and the rotating body cannot be obtained, and the rotating body is stably driven to rotate. There is a risk that maintenance will be required early and durability will be reduced. Further, if the compression spring is displaced from the shaft at the contact portion between the compression spring and the shaft that is the holding member, the compression spring cannot press the shaft that is the holding member toward the rotating body, and the elliptical motion of the vibrating body This makes it impossible to rotate the rotating body.
As described above, when the configuration of the pressurizing unit is complicated and complicated, there is a possibility that the cost of the driving device is increased, the stability of the driving force for rotating the rotating body is lowered, and the durability is lowered.

  On the other hand, in the drive device described in Patent Document 2, as described above, the contact portion formed in the vicinity of the inner peripheral end of the vibrating body is sandwiched between the tapered portions provided on the two disk members constituting the rotating body. In addition, an appropriate pressure is applied between the contact portion of the vibrating body and the rotating body by the elastic force of each disk member. For this reason, it is thought that the structure which produces a pressure between the contact part of a vibrating body and a rotary body can be simplified rather than the structure of patent document 1, and the applied pressure can be stabilized.

  However, the rotating body that is rotated by the vibration type actuator described in Patent Document 2 is composed of two disk members each provided with a tapered portion that sandwiches the contact portion of the plate-like member from the front and back, and 2 There is a restriction that two disk members must be screwed together. For this reason, the vibration type actuator described in Patent Document 2 may have a limited range of use. If the range of use is limited, that is, if versatility is reduced, it is difficult to reduce costs due to mass production effects. End up.

  The present invention has been made in view of the above-described problems, and its object is to provide a simple and inexpensive means for generating pressure between the vibrating body and the rotating body, and there are few restrictions on the rotating body to be rotated. It is to provide a vibration type actuator.

  In order to achieve the above object, the invention described in claim 1 includes a plate-like member to which a piezoelectric element is fixed, and rotates the rotating body that contacts the plate-like member by driving the piezoelectric element. In the vibration type actuator, the plate-like member has elasticity and is provided with a through-hole portion, and a thickness direction of the plate-like member and a rotation axis are parallel to the through-hole portion of the plate-like member. It has a plurality of contact portions that come into contact with the rotator arranged in the through-hole portion in a posture, and each contact portion is pressed toward the rotating shaft of the rotator by elastic force due to elastic deformation of the plate-like member. The elliptical locus is moved by driving the piezoelectric element.

  The present invention can provide a simple and inexpensive means for generating pressure between a vibrating body and a rotating body, and can provide a vibration type actuator with less restrictions on the rotating body to be rotated.

1 is an overall schematic diagram of an image forming apparatus according to an embodiment. FIG. 3 is an explanatory diagram of a sheet conveying apparatus according to the first embodiment. FIG. 3 is an explanatory diagram of a drive device including the vibration type actuator according to the first embodiment. FIG. 6 is an explanatory diagram of a vibration profile of a plate-like member included in the vibrating body according to the first embodiment. Explanatory drawing of the vibration profile of the example in which each projection part performs elliptical motion of a reverse direction. Explanatory drawing at the time of each protrusion part and rotary body contact | abutting the plate-shaped member which the vibration body had. Explanatory drawing of the change by abrasion of the projection part of the plate-shaped member which it had in the vibrating body. FIG. 6 is an explanatory diagram of a sheet conveying apparatus according to a second embodiment. FIG. 6 is an explanatory diagram of a drive device including a vibration type actuator according to a second embodiment. Explanatory drawing of the structure which moves the rotary body which has a taper shape, and recovers the pressure between a vibrating body and a rotary body. Explanatory drawing of the structure which recovers the pressure between a vibrating body and a rotary body by moving a cylindrical-shaped rotary body. Explanatory drawing of the resonance frequency change detection block which detects the timing which performs the recovery | restoration operation | work of the pressure between a vibrating body and a rotary body. FIG. 6 is an explanatory diagram of a sheet conveying apparatus according to a third embodiment. FIG. 6 is an explanatory diagram of a drive device including a vibration type actuator according to a third embodiment. Explanatory drawing of the other example of a vibration type actuator.

  Hereinafter, an embodiment in which the present invention is applied to an electrophotographic color multifunction peripheral (hereinafter referred to as a multifunction peripheral 500) that is an image forming apparatus will be described with reference to the drawings. First, an overall outline of the multi-function device 500 of the present embodiment common to the respective examples will be described. Here, FIG. 1 is an overall schematic diagram of a multifunction peripheral 500 that is an image forming apparatus according to the present embodiment.

  The multi-function device 500 according to the present embodiment is a so-called tandem image forming apparatus that employs a dry two-component developing system using a dry two-component developer. The multi-function device 500 includes a multi-function device main body 100, a paper feed table 200 on which the multi-function device main body 100 is placed, a scanner 300 attached to the multi-function device main body 100, and an automatic document feeder 400 attached to the upper portion of the scanner 300. Yes. The multi-function device 500 receives image data that is image information read from the scanner 300 and print data from an external device such as a personal computer, and performs image forming processing on a sheet P such as transfer paper or an OHP sheet. As shown in the figure, the MFP main body 100 is a latent image carrier as four driven bodies for each color of yellow (Y), magenta (M), cyan (C), and black (Bk). Photosensitive drums 1Y, 1M, 1C, and 1Bk are juxtaposed. These photosensitive drums 1Y, 1M, 1C, and 1Bk are arranged along the belt moving direction so as to contact the endless belt-shaped intermediate transfer belt 5 supported by a plurality of rotatable rollers including a driving roller. Has been placed.

  Further, around the photosensitive drums 1Y, 1M, 1C, and 1Bk, the following electrophotographic process members are arranged in the order of processes. Electrophotographic process members such as chargers 2Y, 2M, 2C, 2Bk, developing devices 9Y, 9M, 9C, 9Bk corresponding to each color, cleaning devices 4Y, 4M, 4C, 4Bk, static elimination lamps 3Y, 3M, 3C, 3Bk is there. An optical writing device 17 is provided above each photosensitive drum 1. In addition, primary transfer rollers 6Y, 6M, 6C, and 6Bk, which are primary transfer units, are disposed at positions facing each other through the intermediate transfer belt 5 of each photosensitive drum 1.

  The intermediate transfer belt 5 is stretched around stretching rollers 11, 12, 13 and a tension roller 14, and is driven to rotate by the rotation of the stretching roller 12, which is a driving roller that is rotationally driven by a drive source (not shown). . Here, a belt cleaning device 19 is provided at a position facing the stretching roller 13 through the intermediate transfer belt 5, and removes residual toner remaining on the intermediate transfer belt 5 after the secondary transfer. The stretching roller 11 is a secondary transfer facing roller that faces the secondary transfer roller 7 that is a secondary transfer unit, and is interposed between the secondary transfer roller 7 and the secondary transfer roller 7 via the intermediate transfer belt 5. Forming part.

  On the downstream side of the secondary transfer nip portion in the sheet conveyance direction, a sheet conveyance belt 15 stretched around a tension roller pair 16 is provided, and the sheet P onto which the toner image has been secondarily transferred is transferred to the fixing device 18. Transport. The fixing device 18 includes a fixing roller pair 8, and heat and pressure are applied at the fixing nip portion to fix an unfixed toner image on the sheet P. A sheet reversing device 110 that reverses the sheet P to record images on both sides of the sheet P is also provided below the secondary transfer nip portion and the fixing device 18.

  Next, a copy operation of the multi-function device 500 in this embodiment will be described. When a full-color image is formed by the multifunction peripheral 500 according to the present embodiment, first, a document is set on the document table 401 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 301 of the scanner 300, and the automatic document feeder 400 is closed and pressed.

  Thereafter, when the user presses a start switch (not shown), when the document is set on the automatic document feeder 400, the document is conveyed onto the contact glass 301. Then, the scanner 300 is driven and the first traveling body 302 and the second traveling body 303 start traveling. Thereby, the light from the first traveling body 302 is reflected by the document on the contact glass 301, and the reflected light is reflected by the mirror of the second traveling body 303 and guided to the reading sensor 305 through the imaging lens 304. . In this way, the image information of the original is read.

  When the start switch is pressed by the user, a motor (not shown) is driven, and the stretching roller 12 as a driving roller is driven to rotate, so that the intermediate transfer belt 5 is driven to rotate. At the same time, the photosensitive drum 1Y is uniformly charged by the charger 2Y while being driven to rotate in the direction of the arrow in the drawing. Thereafter, a light beam Ly from the optical writing device 17 is irradiated to form a Y electrostatic latent image on the photosensitive drum 1Y. This Y electrostatic latent image is developed with Y toner in the developer by the developing device 9Y. During development, a predetermined developing bias is applied between the developing roller and the photosensitive drum 1Y, and the Y toner on the developing roller is electrostatically attracted to the Y electrostatic latent image portion on the photosensitive drum 1Y.

  The Y toner image developed and formed in this way is conveyed to a primary transfer position where the photosensitive drum 1Y and the intermediate transfer belt 5 come into contact with the rotation of the photosensitive drum 1Y. At the primary transfer position, a predetermined bias voltage is applied to the back surface of the intermediate transfer belt 5 by the primary transfer roller 6Y. The Y toner image on the photosensitive drum 1Y is drawn toward the intermediate transfer belt 5 by the primary transfer electric field generated by this bias application, and is primarily transferred onto the intermediate transfer belt 5. Thereafter, similarly, the M toner image, the C toner image, and the Bk toner image are also primarily transferred so as to sequentially overlap the Y toner image on the intermediate transfer belt 5. The transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer is removed by the belt cleaning device 19.

  When the user presses the start switch, the paper feed roller 202 of the paper feed table 200 corresponding to the sheet P selected by the user rotates, and the sheet P is sent out from one of the paper feed cassettes 201. The fed sheet P is separated into one sheet by the separation roller 203 and enters the sheet feeding path 204, and is conveyed by the conveying roller 205 to the sheet feeding path 101 in the MFP main body 100. The sheet P conveyed in this way is stopped when it hits the registration roller 102. When a sheet P not set in the sheet feeding cassette 201 is used, the sheet P set on the manual feed tray 105 is fed by the sheet feeding roller 104 and separated into one sheet by the separation roller 108, and then the manual sheet feeding path. It is conveyed through 103. Then, it stops when it hits the registration roller 102.

  The toner images having the four colors superimposed on the intermediate transfer belt 5 are conveyed to a secondary transfer position facing the secondary transfer roller 7 as the intermediate transfer belt 5 rotates. Further, the registration roller 102 starts to rotate in accordance with the timing at which the composite toner image formed on the intermediate transfer belt 5 as described above is conveyed to the secondary transfer position, and the sheet P is moved to the secondary transfer position. Transport. At this secondary transfer position, a predetermined bias voltage is applied to the back surface of the sheet P by the secondary transfer roller 7. Then, the toner image on the intermediate transfer belt 5 is secondarily transferred collectively onto the sheet P by the secondary transfer electric field generated by the bias application and the contact pressure at the secondary transfer position. Thereafter, the sheet P onto which the toner image has been secondarily transferred is conveyed to the fixing device 18 by the sheet conveying belt 15 and subjected to fixing processing by the fixing roller pair 8 provided in the fixing device 18.

  When the sheet P on which the fixing process has been performed is discharged as it is, it is discharged by the discharge roller pair 106 and stacked on the discharge tray 107. When the paper is reversed and discharged, the paper is switched by the switching claw 109 and put into the sheet reversing device 110, where the paper is reversed and discharged onto the paper discharge tray 107 by the paper discharge roller pair 106. When performing double-sided printing, it is switched by the switching claw 109 and put into the sheet reversing device 110, where it is reversed and led again to the transfer position. After the toner image is secondarily transferred to the back surface of the sheet P, it is discharged. The paper is discharged onto the paper discharge tray 107 by the paper roller pair 106.

As shown in FIG. 1, the sheet reversing device 110 mainly includes a switching claw 109, a reversing introduction path 111, a sheet reversing path 120, a single-side / double-side switching claw 112 provided on the downstream side in the sheet conveying direction of the fixing device 18. And a double-sided conveyance path 150. The switching claw 109 switches whether the sheet P on which the toner image is fixed by the fixing device 18 is guided to the paper discharge roller pair 106 or the reversal introduction path 111. The single-side / double-side switching claw 112 switches whether the reversed sheet P is guided to the paper discharge roller pair 106 or to the double-sided conveyance path 150 for performing double-sided printing. The duplex conveyance path 150 is connected to the sheet feeding path 101 and guides the reversed sheet P to the sheet feeding path 101.
A plurality of sheet conveying devices 151 that convey the sheet P are arranged in the reversal introduction path 111, the sheet reversing path 120, and the double-sided conveyance path 150, respectively.

  Here, as described above, various types of sheet conveying apparatuses are conventionally known as the sheet conveying apparatuses included in the image forming apparatus. Further, as a driving device that rotationally drives a pair of rollers and rollers included in the sheet conveying device, a motor using a magnetic field and a coil such as a stepping motor and a DC motor is mainly used.

  In recent years, diversification of applications of image forming apparatuses has been promoted due to market needs, and a wide range of products ranging from large machines close to offset printing to monochrome small machines dedicated to A4 have been put on the market. In these image forming apparatuses, the design philosophy is also greatly different. Regarding the driving device that rotationally drives a pair of rollers and rollers provided in the image forming apparatus, a large machine is a large driving apparatus, and a small machine is a small one. A drive device is often used. In addition, as in the multi-function device 500 of the present embodiment, a small-sized drive device is often used even in a multi-function device (MFP) or the like in which each device in the image forming apparatus is highly dense.

  As described above, motors of the type using a magnetic field and a coil are the mainstream as driving devices for rotating and driving a pair of rollers and rollers included in the sheet conveying device. However, when the size is reduced with this type of motor, output is achieved. Has the disadvantage of becoming smaller than the size. For this reason, in a small motor, the output efficiency with respect to size (hereinafter referred to as size efficiency) is very poor. That is, the smaller the image forming apparatus is, or the higher the density of each apparatus in the apparatus, the lower the size efficiency of the motor.

  The selling point of small image forming devices is small size, low power consumption, low price, etc. The selling point of multi-function devices is the installation space rather than installing multiple dedicated machines such as printers and copiers. It is possible to save space, reduce power consumption, and reduce price. However, when a small motor of a type using a magnetic field and a coil is used, size efficiency is poor, and it is difficult to achieve both reduction in size and space saving of the image forming apparatus and reduction in power consumption. Therefore, in order to achieve both a reduction in size and space saving of the image forming apparatus and a reduction in power consumption, it is necessary to use a driving apparatus having a vibration type actuator in a driving apparatus such as a small image forming apparatus or a multifunction peripheral. It is considered effective.

Therefore, in the multi-function device 500 of this embodiment, the piezoelectric element of the vibrating body having a piezoelectric element and a plate-like member to which the piezoelectric element is fixed is driven by the driving device of the sheet conveying device 151 to rotate the rotating body. A vibration type actuator is provided.
Next, a plurality of examples of the drive device including the vibration type actuator, which is a feature of the present embodiment, are provided in the drive device that drives the sheet conveying device 151 arranged in the sheet reversing path 120 of the sheet reversing device 110. Examples will be described.

Example 1
A description will be given from Example 1 of the present embodiment with reference to the drawings.
2A and 2B are explanatory views of the sheet conveying device 151 according to the present embodiment, where FIG. 2A is a cross-sectional explanatory view at the axial center position of the rotating shaft 153 of the driving roller 152, and FIG. 2B is a perspective view of the arrangement of the rollers. It is explanatory drawing. The two pressure rollers 154 are supported by brackets (not shown) provided on the front side plate 191 and the rear side plate 192 via the same rotation shaft, and are pressed toward the driving roller 152 by a pressure unit. However, since a known configuration can be used, the illustration is omitted in FIG.

  3A and 3B are explanatory views of the driving device 160 provided with the vibration type actuator 170 according to the present embodiment. FIG. 3A is a cross-sectional explanatory view at the axial center position of the rotating shaft 153 of the driving roller 152, and FIG. It is a plane explanatory view. 4A and 4B are explanatory diagrams of the vibration profile of the plate-like member 172 included in the vibration body 171 according to the present embodiment. FIG. 4A is an explanatory view of the vibration profile in the left-right direction, and FIG. FIG. 5 is an explanatory diagram of a vibration profile in the vertical direction, and FIG. 8C is an explanatory diagram of elliptical motion of each protrusion 173. FIG. FIG. 5 is an explanatory view of a vibration profile of an example in which each protrusion 173 performs an elliptical motion in the reverse direction. FIG. 5A is an explanatory view of the vibration profile in the left-right direction, and FIG. An explanatory view of the vibration profile in the direction, (c) is an explanatory view of the elliptical motion of each protrusion 173. FIG. 6 is an explanatory diagram when the protrusions 173 of the plate-like member 172 included in the vibrating body 171 and the rotating body 161 come into contact with each other. FIG. 6A shows the protrusions 173 and the rotating body 161 before contact with each other. FIG. 6B is an explanatory diagram after the protrusions 173 and the rotating body 161 are brought into contact with each other.

  A plurality of sheet conveying devices 151 arranged on the sheet reversing path 120 of the sheet reversing device 110 include a driving roller 152 as a plurality of conveying rollers for nipping and conveying the sheet P, as shown in FIGS. And a pressure roller 154 that is pressed toward the drive roller 152. 2B shows a state in which the sheet P is conveyed from the sheet reversing path 120 to the double-sided conveying path 150, that is, the return path in the sheet reversing path 120.

  Further, as shown in FIG. 2A, the sheet conveying device 151 includes a driving device 160 that rotationally drives a rotating shaft 153 that is a rotating shaft member of the driving roller 152, and the rotating shaft 153 is provided in the driving device 160. The rotary body 161 is press-fitted into a cylindrical hollow portion. Here, the rotating body 161 provided in the driving device 160 is a rotating body that is rotated by the vibration type actuator 170 and functions as a transmission member that transmits the rotational driving force to the driving target. Then, the piezoelectric element 174 fixed to the plate member 172 included in the vibrating body 171 of the vibration type actuator 170 provided in the driving device 160 is driven to rotate the rotating body 161, and the rotating shaft 153 press-fitted into the rotating body 161. The rotational driving force is transmitted to the driving roller 152 to rotate.

As described above, the drive device 160 of the sheet conveying device 151 includes the vibration type actuator 170, so that the drive device 160 can be reduced in size as compared with a general motor using a magnetic field and a coil. The drive device 160 with high size efficiency can be provided. The vibration type actuator 170 functions as a frame body, and one end side in the axial direction of the rotation shaft 153 of the frame 176 that is a support member for supporting the vibration body 171 is attached to the rear side plate 192 of the multifunction machine main body 100. ing. Further, the frame 176 described above also serves as the frame of the driving device 160 of the present embodiment.
Next, the vibration type actuator 170 provided in the driving device 160 provided in each sheet conveying device 151 will be described.

  As shown in FIGS. 3A and 3B, the vibration type actuator 170 includes a rectangular plate-like member 172 provided with through-hole portions 175, and plate-like members 172 in the vicinity of the four corners and symmetrically on the front and back sides. Are provided with vibrating bodies 171 each having eight plate-like piezoelectric elements 174 fixed thereto. In addition, a plate spring 178 that is a holding member that holds the vibrating body 171 (plate-like member 172) is provided, and a protrusion 173 that is a contact portion formed in the through-hole portion 175 of the plate-like member 172 is provided in the driving device 160. The rotating body 161 is contacted. In addition, as described above, the frame 176 functions as a frame of the vibration type actuator 170 and supports the vibration body 171 via the leaf spring 178.

Here, as described above, a plurality of piezoelectric elements 174 are fixed to the plate-like member 172, and by applying an alternating electric field to each piezoelectric element 174, each piezoelectric element 174 is excited, and the vibration is caused by the plate-like member. By being transmitted to 172, the plate-like member 172, that is, the vibrating body 171 is excited. That is, a piezoelectric element 174 is excited by applying a predetermined AC voltage to each piezoelectric element 174 fixed to the front and back of the plate-shaped member 172 to expand and contract in a predetermined direction, and this vibration is transmitted to the plate-shaped member 172. Thus, the plate-like member 172, that is, the vibrating body 171 is excited. Further, the plate-like member 172 has elasticity, and, as will be described in detail later, a protrusion formed in a through-hole portion 175 provided in the plate-like member 172 by applying an alternating electric field to the piezoelectric element 174 to vibrate. 173 performs an elliptical orbital motion (hereinafter referred to as elliptical motion). Further, in the vibration type actuator 170 of the present embodiment, an ultrasonic field is generated in the plate-like member 172 (protrusion 173) by applying an AC electric field to each piezoelectric element 174.
By providing the vibration type actuator 170 as described above in the driving device 160 of the sheet conveying device 151, the operation sound in the viewable area is reduced as compared with a general type using a motor using a magnetic field and a coil. Thus, quiet image formation becomes possible.

  The piezoelectric element 174 is an element that is distorted when an electric field is applied. A typical example is a piezoelectric element. Although this piezo element contains lead, it is excluded from the RoHS designation because no alternative material is currently available. In research institutions and the like, Pb-free piezoelectric elements have also been developed and are expected to be on the market in the future. In the present invention, the material of the piezoelectric element is not particularly limited, but at present, the piezoelectric element is the first candidate, and in this embodiment, the piezoelectric element is used as the piezoelectric element 174.

The plate-like member 172 and the piezoelectric element 174 of the vibrating body 171 are plate-shaped with high efficiency so that the vibration generated by the piezoelectric element 174 does not decrease and the transmission efficiency of the vibration generated by the piezoelectric element 174 does not decrease. It is firmly bonded and fixed so that it can be transmitted to the member 172. For example, strong adhesion can be realized with an epoxy adhesive or the like.
The plate-like member 172 is not particularly limited as a material, but a metal material is preferable because it is necessary to excite the vibration in the ultrasonic region without attenuating, and specifically iron, brass, aluminum, duralumin, and the like can be given. However, various alloys are used to maximize the characteristics. Therefore, since it has an elastic coefficient and specific gravity unique to the material, it has a natural frequency depending on the shape. Here, there are a plurality of natural frequencies from the profile and order of vibrations at the time of resonance.

  As shown in FIG. 3B, the plate-like member 172 included in the vibrating body 171 of the present embodiment has a substantially annular shape with a through-hole portion 175 provided at a substantially central portion thereof. . The through-hole portion 175 of the plate-like member 172 comes into contact with the rotating body 161 of the driving device 160 disposed in the through-hole portion 175 in a posture in which the thickness direction of the plate-like member 172 and the rotation axis are parallel to each other. In addition, the projection portion 173 which is two (plural) contact portions is provided. The two protrusions 173 are formed at two positions inside the through-hole portion 175, that is, inside the annular shape so as to be substantially symmetric with respect to the center axis position of the rotating body 161 when the rotating body 161 is arranged. The protrusion 173 is formed so as to contact the outer peripheral surface of the rotating body 161. The number of protrusions 173 may be three or more. However, when the number of protrusions 173 is four or more, if the rotating body 161 is cylindrical, the contact state of some protrusions 173 may become unstable if the processing accuracy is low. Therefore, in this embodiment, two protrusions 173 are formed as shown in FIG.

  The shape of the plate-like member 172 included in the vibrating body 171 has many resonance vibration profiles as described above, and has natural frequencies corresponding to the respective resonance modes. For example, there are vibration profiles as shown in FIGS. 4 (a) and 4 (b), which have specific frequencies for generating respective resonance vibrations. In the example of FIG. 4A, each protrusion 173 in contact with the rotating body 161 vibrates in the left-right direction in the drawing, and in the example of FIG. 4B, it vibrates in the vertical direction in the drawing. When these vibrations occur at the same time, two-component vibrations are applied to each projection 173, so that an elliptical motion can be generated as shown in FIG.

  That is, the vibration type actuator 170 of the present embodiment is a resonance synthesis type vibration type actuator that rotates the rotating body 161 of the driving device 160 by an elliptical motion obtained by combining vibration profiles at resonance. In this way, by making the vibration type actuator provided in the drive device 160 the resonance synthesis type vibration type actuator 170, the speed of rotating the rotating body can be made faster than that of the traveling wave type.

In order to generate two different resonance vibrations at the same time, the resonance frequency inherent to each resonance may be a close value. Resonance has a peak value at the resonance frequency, but has a bandwidth, and shows the vibration profile of the resonance even at a frequency slightly deviated from the resonance frequency. Accordingly, if there are two resonance resonance frequencies in the near frequency band, two different resonance vibrations occur simultaneously in the vicinity of the frequencies. Therefore, elliptical motion can be generated.
Since the resonance frequency of the plate-like member 172 included in the vibration body 171 changes by changing the shape of the plate-like member 172 having elasticity, two resonances can be obtained by designing the shape of the plate-like member 172 well. Can be brought to a close frequency band.

When the resonance vibration is generated at the same time, the directions of the elliptical motions of the two protrusions 173 in contact with the rotating body 161 of the driving device 160 are preferably the same direction. Otherwise, the direction in which the rotating body 161 is rotated by the two protrusions 173 is reversed, and the driving force transmission efficiency to the rotating body 161 is significantly reduced. Since the two (plural) protrusions 173 are all (all) moving along an elliptical locus in the same direction, the elliptical movements of the protrusions 173 can be strengthened without interfering with each other. Therefore, it is possible to transmit the vibration energy of the vibrating body 171 to the rotating body 161 without waste, and to obtain the driving device 160 with very high efficiency.
In order to make the elliptical motion directions of the two protrusions 173 the same, it is necessary to select a resonance vibration profile to be used.

For example, as shown in FIG. 5A, each protrusion 173 moves in the same direction in the left-right direction in the drawing and a vibration profile moves in the same direction, and as shown in FIG. 5B, each protrusion 173 shows in the drawing. The vibration profile that moves so as to contact and separate in the vertical direction is generated simultaneously. When such two vibration profiles are generated at the same time, the direction of the elliptical motion of each protrusion 173 is opposite as shown in FIG. Do not choose to combine vibration profiles as shown in (b).
Therefore, in the vibration type actuator 170 of the present embodiment, the combination of vibration profiles as shown in FIGS. 4A and 4B is selected. Specifically, as shown in FIG. 4 (a), each protrusion 173 moves in synchronization with the opposite direction in the horizontal direction in the drawing, and each protrusion 173 as shown in FIG. 4 (b). In the figure, a vibration profile that moves so as to contact and separate in the vertical direction is generated simultaneously. By simultaneously generating such two profiles, the direction of the elliptical motion of each protrusion 173 can be the same as shown in FIG.

  Further, it is desirable that the directions of the elliptical motions of the two protrusions 173 in contact with the rotating body 161 of the driving device 160 are the same direction and the phase is the same. That is, it is desirable that the motion of the elliptical locus of the two protrusions 173 of the plate-like member 172 included in the vibrating body 171 is performed with a phase that is axially symmetric with respect to the rotational axis of the rotating body 161. With this configuration, it is possible to perform the pressing operation of the rotating body 161 by the protrusions 173 with the same timing of pressing the rotating body 161 by the elliptical motion, and to drive the rotating body 161. Power transmission efficiency can be increased.

  If the timing of the pressing operation of the rotating body 161 by each protruding portion 173 is shifted, the other protruding portion 173 is retracted from the rotating body 161 at the timing when one protruding portion 173 is pressed against the rotating body 161. It will be. If the other protrusion 173 is retracted from the rotating body 161 at the timing when one of the protrusions 173 is pressed against the rotating body 161 as described above, the pressing and retracting operations are alleviated as a whole, resulting in rotation. The transmission efficiency of the driving force to the body 161 is reduced.

In order to surely perform the efficient movement of the two protrusions 173 as described above, the shape of the plate-like member 172 included in the vibrating body 171 is made symmetrical with respect to the rotational axis of the rotating body 161 as the axis of symmetry. It is desirable to do. Of course, the scope of the present invention is not limited to this, but the plate-like member 172 having an axisymmetric shape is desirable from the viewpoint of ease of design and construction.
Therefore, in the vibration type actuator 170 of the present embodiment, the two protrusions 173 are arranged so as to be in an axially symmetric position with the rotation axis of the rotating body 161 of the driving device 160 as the axis of symmetry, and the rotating body 161 has two protrusions. The unit 173 is configured to receive an axisymmetric force. That is, the pressure between the vibrating body 171 and the rotating body 161 is configured to act in opposite directions on the protrusions 173 that are arranged in axial symmetry so as to face each other.

  Here, in patent document 1 which is the above-mentioned prior art, one side of the vibrating body is pressed against the rotating body, and the elliptical motion of the vibrating body is transmitted to the rotating body. Usually, in the resonance of the vibrating body, the number of places where the amplitude is maximized is not only one place but a plurality of places. Therefore, as specified in Patent Document 1, an elliptical motion having a large amplitude occurs even in a portion not in contact with the rotating body. The elliptical motion having a large amplitude in the portion not in contact with the rotating body is not used for driving the rotating body but is converted into heat according to the damping coefficient of the vibrating body.

  On the other hand, in the vibration type actuator 170 of the present embodiment, the rotating body 161 is rotated by two protrusions 173 (the scope of the invention includes the case of three or more). For this reason, the vibration of the plate-like member 172 having the elasticity of the vibrating body 171 can be transmitted to the rotating body 161 more efficiently than at least the configuration described in Patent Document 1 described above, and as a result, heat generation can be reduced.

Here, the shape of the plate-like member 172 included in the vibrating body 171 illustrated in FIG. 3 is an example, and is not limited to the shape illustrated in FIG. 3. It may be in shape. A condition that the through hole 175 is provided in the center, the condition that the protrusion 173 formed in the through hole 175 is in contact with the rotating body 161, and the requirement described so far is satisfied It is.
Next, the rotating body 161 of the driving device 160 will be described.

As described above, the rotating body 161 of the driving device 160 is in contact with the two protruding portions 173 provided on the plate-like member 172 having the elasticity of the vibrating body 171, and the two protruding portions 173 are in contact with each other. Rotational motion is given by elliptical motion. Although it does not specifically limit as a material, Since rotation motion is given by the elliptical motion of the protrusion part 173 of two places of the plate-shaped member 172, it is preferable to use metals, such as stainless steel which are hard to wear.
Further, as described above, the rotating body 161 of the present embodiment has a rotating shaft portion that is hollow, and a rotating shaft 153 that is a rotating shaft member of the drive roller 152 included in the sheet conveying device 151 is press-fitted into the hollow portion. The rotating shaft 153 functions as the rotating shaft of the rotating body 161.
The present invention is not limited to the rotating shaft portion of the rotating body that is hollow, but the rotating shaft portion of the rotating body 161 is hollow as in the vibration type actuator 170 of the present embodiment. This has the following merits.

In a general sheet conveying device drive device, there are many cases of driving a shaft object such as a rotation shaft such as a drive roller to be driven, and a normal motor has an output shaft, and connects the output shaft and the shaft object. For this purpose, gears, pulleys, coupling means and the like are required.
On the other hand, if the rotating shaft portion of the rotating body 161 is made hollow like the driving device 160 of the present embodiment, the rotating shaft 153 of the driving roller 152 to be driven is directly fitted into the hollow portion as described above ( By press-fitting), a very simple drive transmission becomes possible. As a method of fitting, there are various methods such as press-fitting as in the present embodiment or engagement with a key or D cut.

  With this configuration, it is possible to connect the driving roller 152, which is a driving object, to the rotating shaft 153 without using a gear, a pulley, a coupling means, or the like, and the sheet conveying device 151 is simplified. And it becomes possible to comprise at low cost. Further, not only the number of parts can be reduced, but also the arrangement space can be reduced, and an ultra-small sheet conveying apparatus can be realized.

  Further, as shown in FIG. 3A, the vicinity of the portion in contact with the protrusion 173 provided on the plate-like member 172 provided on the vibrating body 171 of the rotating body 161 is centered on the rotation axis of the rotating body 161. It has a tapered shape like the side surface of a cone. And as shown to the broken-line part of Fig.6 (a), in the position where the rotary body 161 and the plate-shaped member 172 contact before the rotary body 161 is arrange | positioned inside the through-hole part 175 of the plate-shaped member 172. FIG. The outer diameter of the rotating body 161 is a size that interferes with the protrusion 173 of the plate-like member 172. That is, when the rotating body 161 is arranged inside the through-hole portion 175 of the plate-like member 172, as shown in FIG.

Accordingly, in the direction of the arrow shown in FIG. 6B, the pressing force from the plate member 172 acts on the rotating member 161 by the amount of elastic deformation of the plate member 172 having the elasticity of the vibrating body 171. A pressure is generated between each protrusion 173 of 172 and the rotating body 161.
The rotating body 161 has a tapered shape. For this reason, even when the shape of each protrusion 173 of the plate-like member 172 includes a processing error or the like, the relative position of the vibrating body 171 and the rotating body 161 in the axial direction of the rotating shaft 153 is adjusted at the time of assembling. The pressure between the protrusions 173 of the shaped member 172 and the rotating body 161 can be set to a desired value.

In order to efficiently transmit the power of the elliptical motion of the vibrating body 171, that is, the power of the elliptical motion of the protruding portion 173 of the plate-like member 172 included in the vibrating body 171, to the rotating body 161, each of the protruding parts 173 and the rotating body 161 Appropriate pressure must be applied between them. In order to efficiently transmit the power of the elliptical motion of the protrusion 173 to the rotator, an appropriate pressure is applied between the protrusion 173 and the rotator 161 so that the protrusion 173 and the rotator 161 This is because it is necessary to generate a frictional force. By applying pressure in this way, frictional force is generated and the driving force can be transmitted. On the other hand, if too much pressure is applied, even the elliptical motion in the negative direction is transmitted to the rotating body 161, and the speed of the rotating body 161 decreases. Resulting in.
Therefore, although the interference margin shown by the broken line in FIG. 6A between the rotating body 161 and each protrusion 173 of the plate-like member 172 included in the vibrating body 171 needs to be accurately managed, The following effects can be achieved.

Each protrusion of the plate-like member 172 is caused by elastic force due to elastic deformation of the plate-like member 172 acting on the protrusions 173 that are a plurality of contact portions provided in the through-hole portion 175 provided in the plate-like member 172 having elasticity. A pressure can be generated between the portion 173 (vibrating body 171) and the rotating body 161. That is, the vibration having the piezoelectric element 174 and the plate-like member 172 to which the piezoelectric element 174 is fixed by pressurizing each protrusion 173 toward the rotation axis of the rotating body 161 by the elastic force due to the elastic deformation of the plate-like member 172. A predetermined pressure can be generated between the body 171 and the rotating body 161.
Therefore, there is no need to provide a complex spring mechanism or the like composed of a plurality of constituent members such as a compression spring or a long hole provided in the support member as in Patent Document 1 which is a conventional technique, and the vibrating body 171 and the rotating body 161 are not provided. The configuration that generates pressure between the two can be a simple and inexpensive configuration.

In addition, the number of constituent members can be reduced as compared with a configuration in which a spring mechanism or the like is provided as in Patent Document 1 as the prior art, and an overlapping of errors due to wear of a plurality of constituent members is reduced, so that the vibrating body 171 and the rotating body 161 are reduced. The pressure drop between the two can be suppressed. Therefore, the stability and durability of the driving force for rotating the rotating body 161 of the driving device 160 can be improved by the vibration type actuator 170.
Therefore, a driving device that rotationally drives a rotating body that contacts the vibrating body by a plurality of resonances simultaneously generated in the vibrating body by driving a piezoelectric element, and generates pressure between the vibrating body and the rotating body The means can be configured simply and inexpensively, and a drive device having high durability and stability can be provided.

  Further, the movement of the elliptical locus of the plurality of protrusions 173 of the vibrating body 171 is configured to move in a phase that is axially symmetric with respect to the rotational axis of the rotating body 161. With this configuration, the pressing operation of the rotating body 161 by the plurality of protrusions 173 can be reliably performed, and the transmission efficiency of the driving force to the rotating body 161 can be increased.

Further, since the pressure between the vibrating body 171 and the rotating body 161 acts in the opposite directions at the protrusions 173 arranged so as to face each other, the pressure (pressing force) acts on the rotating body 171 and the rotating body 171. It becomes only the body 161, and no reaction force acts on the outside. For this reason, it becomes possible to hold the vibrating body 171 without stress, and the durability and stability of the vibration type actuator 170 which is a driving device can be further improved. That is, a plurality of contact portions are arranged so as to be axisymmetric with respect to the rotation axis of the rotating body, and each contact portion faces the pressure between the vibrating body and the rotating body via the rotation axis of the rotating body. By canceling in the direction, the durability and stability of the drive device can be further increased.
Therefore, it is possible to provide a drive device that can further improve durability and stability without applying stress due to applying pressure between the vibrating body and the rotating body to components other than the vibrating body and the rotating body.

Further, in the vibration type actuator 170 of the present embodiment, the vibration body 171 (plate-like member 172) and the frame 176 which is a support member are connected via the plate spring 178 which is a holding member as described above. The holding member is not limited to a leaf spring like the vibration type actuator 170 of the present embodiment, but a member having an appropriate elastic force is preferable, and at least rigidity is lower than that of the vibrating body 171 having elasticity. It consists of members. This is because the vibration generated in the vibrating body 171 is not transmitted to the frame 176, and the vibration body 171 and the frame 176 are rigidly connected so that the rigidity of the frame 176 does not affect the vibration of the vibrating body 171. This is because they are separated (isolated). In addition, the vibrating body 171 is properly held so as not to rotate beyond a predetermined range.
Here, since the vibration profile at the time of resonance of the plate-like member 172 included in the vibrating body 171 is used, a portion having a small amplitude is determined, and the amplitude of the plate-like member 172 included in the vibrating body 171 is small. It is desirable to hold the part with a leaf spring 178 which is a holding member.

As described above, at least the plate member 172 included in the vibrating body 171 is supported by the frame 176 serving as a support member via the plate spring 178 that is a holding member having lower rigidity than the plate member 172 having elasticity. Thus, the following effects can be achieved. Each projection 173 provided in the through hole 175 of the plate-like member 172 performs elliptical motion in the same direction by driving the piezoelectric element 174. Thus, when the plate-like member 172 in which each protrusion 173 performs an elliptical motion is supported by the frame 176 via a highly rigid holding member, the plate-like member 172 is separated from the rotary body 161 by the reaction force from the rotary body 161. It may rotate in the opposite direction. On the other hand, by supporting the plate member 172 with the frame 176 via a plate spring 178 having a lower rigidity than the plate member 172, the influence of the reaction force from the rotating body 161 is suppressed, and the plate member 172 is rotated. It can prevent rotating in the direction opposite to 161.
Therefore, the vibration energy of the vibrating body 171 can be transmitted to the rotating body 161 without waste, and a drive device with high energy transmission efficiency can be provided.

Here, the plate-like member 172 having elasticity applies pressure to the rotating body 161 by its own elastic force and generates pressure between each projection 173 and the rotating body 161. The member 172 is in contact with the rotating body 161 in an elastically deformed state. For this reason, the resonance frequency has changed compared to when the plate-like member 172 is in a free state.
Further, in a state where the rotating member 161 is being pressed while being pressurized by the elastic force of the plate-like member 172, the pressure generated between each protrusion 173 of the plate-like member 172 and the rotating member 161, or the shape of the rotating member 161. It is also known that the resonance frequency of the plate-like member 172 changes depending on the material. That is, it is known that the resonance frequency of the vibrating body 171 changes depending on the pressure generated between the vibrating body 171 and the rotating body 161, the shape of the rotating body 161, and the material.

  For these reasons, in order to form an elliptical motion with the plurality of protrusions 173 as described above, two different resonance vibrations must be generated simultaneously. For this purpose, the resonance frequencies of the two resonances are in close frequency bands. There must be. Therefore, when designing the shape of the vibrating body 171 (plate member 172), it is necessary to design the shape of the vibrating body 171 in consideration of the change in the resonance frequency as described above.

In the vibration type actuator 170 according to the present embodiment, the protrusions 173 are pressed toward the rotation axis of the rotating body 161 by the elastic force generated by the elastic deformation of the plate-like member 172 included in the vibrating body 171 as described above. A predetermined pressure is generated between each protrusion 173 and the rotating body 161. In other words, the vibrating body 171 is pressed against the rotating shaft of the rotating body 161 by the elastic force generated by the elastic deformation of the vibrating body 171 to generate a predetermined pressure between the vibrating body 171 and the rotating body 161.
Therefore, there is no restriction on the rotating body to be rotated like the traveling wave type vibration type actuator described in Patent Document 2 which is the prior art. Specifically, the rotating body is rotated like the vibration type actuator described in Patent Document 2, and is composed of two disk members each provided with a tapered portion that sandwiches the contact portion of the plate-like member from the front and back, In addition, there is no restriction that the two disk members must be screwed together.
Therefore, by applying the present invention, it is possible to provide a simple and inexpensive means for generating pressure between the vibrating body 171 and the rotating body 161, and to provide a vibrating actuator 170 with less restrictions on the rotating rotating body 161. it can.

  Further, by providing the above-described vibration type actuator 170 in the drive device 160, the drive device 160 can achieve the same effect as the above-described vibration type actuator 170. Further, by providing the driving device 160 in the sheet conveying device 151, the sheet conveying device 151 can achieve the same effects as the driving device 160. In addition, by providing the sheet transport device 151 in the multi-function device 500, the multi-function device 500 can achieve the same effects as the sheet transport device 151.

(Example 2)
Next, Example 2 of the present embodiment will be described with reference to the drawings.
FIG. 7 is an explanatory view of a change due to wear of the protrusion 173 of the plate-like member 172 included in the vibrating body 171, FIG. 8 is an explanatory view of the sheet conveying device 151 according to the present embodiment, and FIG. 9 is the present embodiment. It is explanatory drawing of the drive device 160 provided with the vibration type actuator 170 concerning. FIG. 10 is an explanatory diagram of a configuration for recovering the pressure between the vibrating body 171 and the rotating body 161 by moving the rotating body 161 having a tapered shape. 10A is a cross-sectional explanatory view in a state in which the protrusion 173 of the vibrating body 171 is worn, FIG. 10B is a cross-sectional explanatory view in a state in which the rotating body 161 provided with the taper is moved, and FIG. ) Is an explanatory plan view of the vibrating body 171 in the state of FIG.

  FIG. 11 is an explanatory diagram of a configuration in which the pressure between the vibrating body 171 and the rotating body 161a is recovered by moving the cylindrical rotating body 161a. 11A is a cross-sectional explanatory view before the rotating body 161a is worn, FIG. 11B is a cross-sectional explanatory view in a state where the rotating body 161a is worn, and FIG. 11C moves the rotating body 161a. FIG. FIG. 12 is an explanatory diagram of a resonance frequency change detection block that detects timing for performing a pressure recovery operation between the vibrating body 171 and the rotating body 161.

  Here, the sheet conveying apparatus of the first embodiment is different from the sheet conveying apparatus 151 of the present embodiment only in the following points. When the pressure between the vibrating body 171 and the rotating body 161 decreases due to wear of the rotating body 161 or the vibrating body 171 of the vibration type actuator 170 on the driving device 160 of the sheet conveying apparatus 151 of the present embodiment, the pressure decreases. It is the point provided with the structure which recovers the made pressure to the original pressure. Since the configurations and effects according to other points are the same, in the following description, the configurations and effects similar to those of the first embodiment will be omitted as appropriate, and the same constituent members will be the same. This will be described with reference numerals.

In the driving device 160 to which the present invention is applied, the vibration of the elliptical motion of the protrusion 173 provided on the plate-like member 172 provided in the vibration body 171 of the vibration type actuator 170 is caused by the frictional force between the protrusion 173 and the rotating body 161. The rotation body 161 is rotated by being transmitted to the rotation body 161. For this reason, it is inevitable that at least one of the projecting portion 173 and the rotating body 161 of the plate-like member 172 is worn over time. In other words, it is inevitable that at least one of the vibrating body 171 and the rotating body 161 is worn due to use over time.
Further, since wear due to friction between the protrusion 173 of the plate-like member 172 and the rotating body 161, a portion where pressure is generated between the protrusion 173 of the plate-like member 172 and the rotating body 161 is worn out. That is, since wear is caused by friction between the vibrating body 171 and the rotating body 161, a portion where pressure is generated between the vibrating body 171 and the rotating body 161 is worn.

  When at least one of the vibrating body 171 and the rotating body 161 is worn, for example, the vibrating body 171 and the rotating body 161 interfere from the state shown in FIG. 7A to the state shown in FIG. 7B. Will decrease. Then, the pressure between the vibrating body 171 and the rotating body 161 gradually decreases. When the pressure between the vibrating body 171 (the projecting portion 173 of the plate-like member 172) and the rotating body 161 decreases, as described above, the transmission efficiency of the driving force is reduced, and the vibration actuator 170 as a driving device is provided. The output torque will decrease.

Therefore, in the sheet conveying device 151 of the present embodiment, a taper shape formed on the rotating body 161 of the driving device 160 is used to set the pressure between the vibrating body 171 and the rotating body 161 to a predetermined value at the time of assembly. It was decided to. That is, a means for adjusting the relative position between the vibrating body 171 and the rotating body 161 is provided even after the assembly, and the pressure between the vibrating body 171 (the projection 173 of the plate-like member 172) and the rotating body 161 is recovered. It was decided to constitute as follows.
Specifically, as shown in FIGS. 8 and 9, the rotating body 161 of the driving device 160 is adjusted (finely adjusted) after assembling the position of the rotating shaft direction, that is, the axial center direction of the rotating shaft 153 of the sheet conveying device 151. Position adjusting means 180 for adjusting) is provided.

As shown in FIG. 8, the position adjusting means 180 is a disc having a donut-like hole formed on the rear plate 192 side of the rotating body 161 and rotatably connected to the rotating body 161 by a connecting portion (not shown). A position adjustment member 181 having a shape is provided. The position adjusting member 181 has an outer peripheral portion of a spiral male screw thread having a shaft center (rotation shaft of the rotating body 161) of the rotation shaft 153 of the sheet conveying device 151 passing through the formed hole as a center. Is formed. On the other hand, on the rear plate 192 side of the frame 176 that also serves as the frame of the driving device 160, a female screw thread that is screwed with the male screw thread formed on the outer periphery of the position adjusting member 181 is formed. A disc portion 182 having a boss portion is provided.
Then, by rotating the position adjusting member 181 with respect to the disk portion 182 provided on the frame 176, that is, the frame 176, for example, in the positive direction around the axis of the rotation shaft 153 of the sheet conveying device 151, the rotating body 161 and the rotary shaft 153 are moved to the front plate 191 side. On the contrary, the rotating body 161 and the rotating shaft 153 are moved toward the rear plate 192 with respect to the frame 176 by rotating in the forward direction around the axis of the rotating shaft 153 of the sheet conveying device 151.

By configuring the position adjusting means 180 as described above, it is possible to adjust the rotational axis direction of the rotating body 161 of the driving device 160 with respect to the frame 176 of the vibration type actuator 170 after assembly. Then, as shown in FIG. 7B, at least one of the protrusions 173 and the rotating body 161 provided on the plate-like member 172 of the vibration type actuator 170 is worn, and rotates with the plate-like member 172 (vibrating body 171). When the pressure between the body 161 decreases, the pressure is recovered as follows.
From the state of FIG. 10A where the pressure has decreased, the position adjusting member 181 of the position adjusting means 180 is rotated in the forward direction as shown in FIG. 10B, and the rotating body 161 is moved to the front plate 191 side. Each projection 173 is brought into contact with a portion having a large tapered diameter of the rotating body 161. By making such contact, the plate-like member 172 having elasticity as shown in FIG. 10B is elastically deformed so as to spread in the vertical direction, and according to the elastic deformation as shown in FIG. 10C. The elastic force acts in the direction of the rotation axis of the rotating body 161 and can be recovered to a desired pressure.

Therefore, even if at least one of the plate-like member 172 and the rotating body 161 is worn over time, the pressure between the protrusions 173 of the plate-like member 172 and the rotating body 161 can be recovered. By recovering in this way, it is possible to maintain the output characteristics of the rotational driving force transmitted from the rotating body 161 of the driving device 160 to the rotating shaft 153 of the sheet conveying device 151.
Further, when the surface hardness of the plate-like member 172 and the rotating body 161 is approximately the same, the plate-like member 172 is always in contact with the rotating body 161 with the same protrusion 173, so that the plate-like member 172 wears faster. Therefore, it can be said that the above configuration is effective.

On the other hand, when the surface hardness of the plate-like member 172 is significantly higher than the surface hardness of the rotating body 161, the plate-like member 172 is hardly worn, and the wear of the rotating body 161 proceeds. In such a case, it is preferable that the rotating body 161 is not a tapered shape but a simple cylindrical shape.
Then, when wear progresses as shown in FIG. 11B from the state shown in FIG. 11A, the position adjusting means 180 causes the rotating body 161 to rotate as shown in FIG. 11C. It moves to the front side board 191 side along a direction. By moving the rotating body in this way, it is possible to adjust so that a portion (new position) of the rotating body 161 that has not yet been worn comes into contact with each protrusion 173 of the plate-like member 172.
Therefore, even if the rotating body 161 is worn over time, the pressure between the projections 173 of the plate-like member 172 and the rotating body 161 can be recovered. By recovering in this way, it is possible to maintain the output characteristics of the rotational driving force transmitted from the rotating body 161 of the driving device 160 to the rotating shaft 153 of the sheet conveying device 151.

Next, the adjustment timing by the position adjusting unit 180 in the present embodiment will be described.
When the pressure between the protrusions 173 of the plate-like member 172 and the rotating body 161 decreases, the output torque of the driving device 160 decreases. After the output torque of the drive device 160 has dropped, it is slow to notice that the adjustment work by the position adjusting means 180 is performed, and the drive device 160 in a state of insufficient specifications (a state outside the appropriate pressure range). Will be used for a period of time. If a period in which the driving device 160 is used in such a state with insufficient specifications is generated, many secondary problems may occur.
Therefore, it is necessary to perform the adjustment work by the position adjusting means 180 before the pressure drop is detected promptly and the output torque of the drive device 160 is lowered.

Further, as described above, it is known that the resonance frequency of the plate-like member 172, that is, the vibrating body 171 changes when the pressure generated between each projection 173 of the plate-like member 172 and the rotating body 161 changes. The resonance frequency of the vibrating body 171 can be detected electrically by monitoring the current flowing through the piezoelectric element 174.
Therefore, in the driving device 160 of the present embodiment, a resonance frequency change detection block as shown in FIG. 12 is provided in the drive control unit, and this resonance frequency change detection block is used periodically or when the MFP 500 is started up. An operation of detecting the resonance frequency of the vibrating body 171 is performed. Thereafter, the detected resonance frequency of the vibrating body 171 is compared with an initial resonance frequency when the use of the multi-function device 500 is started (hereinafter referred to as an initial resonance frequency). When the detected resonance frequency is changed by a predetermined value or more than the initial resonance frequency, that is, when the difference between the detected resonance frequency and the initial resonance frequency is a predetermined amount or more, an alarm is issued. The adjustment work by the position adjustment means 180 is urged.

  Specifically, the piezoelectric element included in the vibrating body 171 (fixed to the plate-like member 172) is driven by the drive control unit, and the current flowing through the piezoelectric element 174 periodically or when the multi-function device 500 is started up. The value is detected by the resonance frequency detection means 184. When the difference between the detection result and the initial resonance frequency is greater than or equal to a predetermined amount, an alarm is issued to prompt adjustment work by the position adjusting means 180. On the other hand, if the difference between the detection result and the initial resonance frequency is less than a predetermined amount, the operation returns to the detection operation of the resonance frequency detection means 184 again. Here, as a means for issuing an alarm, a speaker or the like may be directly connected to the drive control unit, but an alarm is issued from the speaker or the like provided in the multifunction device main body 100 of the multifunction device 500 provided with the drive device 160. By configuring, the cost can be reduced.

  Here, the predetermined amount may be set to a level that does not deviate from the specification of the driving device 160 (the current range in which an appropriate pressure is generated). The minimum value of the pressure between the plate-like member 172 (projection 173) provided on the vibrating body 171 and the rotating body 161 necessary for obtaining the output torque of the specification of the driving device 160 is obtained, and the pressure is generated. If the resonance frequency is checked in advance, the predetermined amount is automatically determined. In the adjustment operation by the position adjusting unit 180, the detected resonance frequency is transmitted to a control unit (not shown) of the multi-function device 500 and displayed on a display / operation unit (not shown) provided in the multi-function device main body 100. The operation of adjusting to the initial value while monitoring is most preferable.

Example 3
Next, Example 3 of the present embodiment will be described with reference to the drawings.
FIG. 13 is an explanatory diagram of the sheet conveying device 151 according to the present embodiment, and FIG. 14 is an explanatory diagram of the driving device 160 including the vibration type actuator 170 according to the third embodiment.

  Here, the sheet conveying apparatus according to the first and second embodiments and the sheet conveying apparatus 151 according to the present embodiment are different only in the following points. The driving device 160 that drives the sheet conveying device 151 of this embodiment is provided with a speed detecting means for detecting the rotational speed of the rotating body 161 and performing feedback control of the vibration type actuator 170. Since the configurations and effects according to other points are the same, in the following description, the configurations and effects similar to those of the first and second embodiments will be appropriately omitted and the same components will be described. The same reference numerals are used for explanation. In the present embodiment, an example will be described in which the drive device 160 including the rotating body 161 having the tapered shape of the second embodiment is provided with an encoder 185 as speed detection means.

In the drive device 160 including the vibration type actuator 170 to which the present invention is applied, the vibration of the elliptical motion of the protrusion 173 provided on the plate-like member 172 provided on the vibration body 171 is caused to rotate on the rotation body 161 by friction force. Communicating. For this reason, the transmission efficiency varies depending on the friction coefficient between the elastic plate-like member 172 and the rotating body 161 and the elastic coefficient of the protrusion 173 and the portion of the rotating body 161 that contacts the protruding portion 173.
In general, it is clear that the rotational speed of the rotating body 161 increases when the amplitude of the elliptical motion is increased. However, controlling the rotational speed with high accuracy like a stepping motor is the configuration of the first and second embodiments. It is difficult by itself. That is, the vibration type actuators described in the first and second embodiments have only a speed control capability comparable to that of a DC motor when compared with a stepping motor.

  Therefore, in the driving device 160 that drives the sheet conveying device 151 of the present embodiment, in order to control the rotational speed of the rotating body 161 with high accuracy, a speed detection unit that detects the rotational speed of the rotating body 161 is provided. . Specifically, an encoder 185 is provided as a speed detection means, a detection unit 187 is directly connected to the frame 176 of the vibration type actuator 170, and an end surface on the drive roller 152 side of the rotating body 161 of the drive device 160 is a detection target. The detection plate 186 was directly connected. And it comprised so that the relative rotational speed of the rotary body 161 and the flame | frame 176 might be detected.

The detection result detected by the encoder 185 is input to a drive control unit (not shown) that controls the vibration type actuator 170. This drive control unit performs feedback control for controlling the AC electric field applied to each piezoelectric element 174 of the vibration type actuator 170 so as to eliminate the speed difference between the detection result detected by the encoder 185 and the target rotational speed.
In this way, by providing the detection plate 186 that is the detection portion of the encoder 185 that is the speed detection means on the rotation body 161 of the driving device 160, the rotation speed of the rotation body 161 is fed back by feeding back the rotation speed of the rotation body 161. Can be controlled with high accuracy.
In this embodiment, the encoder 185 is provided as the speed detecting means. However, any means may be used for detecting the rotational speed of the rotating body 161. However, in the rotary encoder system, an optical and magnetic detecting method is used. Etc.

  In each of the above-described embodiments, the tip portion of each protrusion 173 which is a plurality of contact portions provided on the plate-like member 172 provided on the vibrating body 171 is in contact with the rotating body 161 of the driving device 160. The example applied to the pointed substantially V-shaped thing as shown in FIG.3 (b) etc. was demonstrated. However, the present invention is not limited to such a configuration. For example, as shown in an explanatory diagram of another example of the vibration type actuator in FIG. 15, each protrusion 173 that contacts the rotating body 161 of the driving device 160 rather than each protrusion 173 described in FIG. It is applicable also to the structure which made the shape of the front-end | tip part flat.

  Due to the flat shape of the tip of each projection 173, the plate member 172 is elastically deformed by applying pressure between the plate member 172 having elasticity of the vibrating body 171 and the rotating body 161. In addition, the contact area between each protrusion 173, which is a contact portion, and the rotating body 161 increases. Accordingly, the pressure is dispersed, which is advantageous for suppressing wear due to friction between the plate-like member 172 and the rotating body 161 provided in the vibrating body 171. That is, the pressure is dispersed, which is advantageous for suppressing wear due to friction between the vibrating body 171 and the rotating body 161.

In the above-described embodiment, the example in which the present invention is applied to the multi-function device 500 that is an electrophotographic image forming apparatus has been described. However, the present invention is not limited to such a configuration. For example, by mounting the image forming apparatus on a sublimation image forming apparatus or an image forming apparatus represented by an ink jet or the like, it is possible to provide a quiet image forming apparatus that can be reduced in size and cost.
Moreover, although the example which applied this invention to the drive device 160 provided with the resonance type | mold vibration type actuator 170 was demonstrated, this invention is not limited to such a structure. For example, while increasing the number of protrusions provided on the plate-like member provided in the vibrating body, the number of piezoelectric elements is increased, and the rotating body of the driving device that contacts is rotated by the traveling wave formed by the elliptical motion of each protrusion. The present invention can also be applied to a traveling wave type vibration actuator.

In addition, the example in which the present invention is applied to the driving device 160 that is a frame body of the vibration type actuator 170 and the frame 176 that is a supporting member also serves as the frame body has been described. However, the present invention has such a structure. It is not limited. For example, the present invention can also be applied to a drive device having a structure in which a frame (frame body) of a vibration actuator provided separately is attached to a frame body of the drive device.
Further, an example in which the present invention is applied to the driving device 160 having a configuration in which a hollow portion is provided in the rotating body 161 included in the driving device 160 and the rotating shaft 153 that is the rotating shaft member of the sheet conveying device 151 is press-fitted and supported. However, the present invention is not limited to such a configuration. For example, the present invention can also be applied to a driving device having a configuration in which a rotating shaft portion is provided on a rotating body provided in the driving device, and the rotating shaft portion and the rotating shaft member of the sheet conveying device are fastened by fastening means.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A vibration that has a plate-like member such as a plate-like member 172 to which a piezoelectric element such as a piezoelectric element 174 is fixed, and rotates a rotating body such as a rotating body 161 that contacts the plate-like member by driving the piezoelectric element. In the vibration type actuator such as the type actuator 170, the plate-like member has elasticity and is provided with a through-hole portion such as a through-hole portion 175, and the plate-like member is provided in the through-hole portion of the plate-like member. A contact portion such as a plurality of protrusions 173 that contact the rotating body disposed in the through-hole portion in a posture in which the thickness direction and the rotation axis are parallel to each other. Pressure is applied toward the rotating shaft of the rotating body by elastic force due to elastic deformation, and the movement of an elliptical locus is performed by driving the piezoelectric element.

According to this, as described in the first embodiment (to 3), each contact portion is pressurized toward the rotating shaft of the rotating body by the elastic force due to the elastic deformation of the plate-like member. A predetermined pressure can be generated between the rotating body and the rotating body. That is, each contact portion is pressurized toward the rotation shaft of the rotating body by the elastic force due to the elastic deformation of the plate-like member, and the vibrating body 171 having the piezoelectric element and the plate-like member to which the piezoelectric element is fixed, etc. A predetermined pressure can be generated between the vibrating body and the rotating body.
Therefore, like the vibration type actuator described in Patent Document 1, a complex spring mechanism composed of a plurality of constituent members that presses a plurality of contact portions of a plate-like member to which a piezoelectric element is fixed toward a rotating body. Etc. need not be provided. Further, the rotating body is rotated as in the vibration type actuator described in Patent Document 2, and is configured by two disk members each provided with a tapered portion that sandwiches the contact portion of the plate-like member from the front and back, and 2 There is no restriction that the two disk members must be screwed together.
Therefore, it is possible to provide a simple and inexpensive means for generating pressure between the vibrating body and the rotating body, and to provide a vibrating actuator with less restrictions on the rotating body to be rotated.

(Aspect B)
In (Aspect A), a holding member such as a plate spring 178 that holds the plate-like member such as the plate-like member 172, and the plate-like member are supported via the holding member so as to be capable of minute relative movement. A support member such as a frame 176, and driving the piezoelectric element such as the piezoelectric element 174 to simultaneously generate a plurality of resonances in the plate-like member, thereby causing a contact portion such as the plurality of protrusions 173 to It is characterized by causing the movement of an elliptical locus.
According to this, as described in the first embodiment (to 3) described above, by using a resonance composite type vibration actuator that simultaneously generates a plurality of resonances in the plate-like member, it is more than the traveling wave type. The rotating speed of the rotating body can be increased. In addition, as compared with a configuration in which a spring mechanism or the like is provided as in the resonance synthesis type vibration type actuator described in Patent Document 1, a distance between each contact portion such as the projection 173 of the plate-like member and a rotating body such as the rotating body 161. The number of constituent members of the means for generating pressure can be reduced. Therefore, the overlap of errors due to the wear of a plurality of components is reduced, and the pressure drop between each contact portion of the plate-like member and the rotating body is suppressed as compared with a vibration type actuator provided with a conventional spring mechanism or the like. The stability and durability of the driving force for rotating the rotating body can be increased.

(Aspect C)
In (Aspect A) or (Aspect B), the movement of the elliptical locus of the contact portion such as the plurality of protrusions 173 of the plate-like member such as the plate-like member 172 is caused by the rotation of the rotary body such as the rotary body 161. It is characterized in that the movement is performed in a phase that is axially symmetric with respect to the axis of symmetry.
According to this, as described in the first embodiment (to 3) described above, it is possible to reliably perform the pressing operation of the rotating body by the plurality of contact portions, and increase the transmission efficiency of the driving force to the rotating body. Can do.

(Aspect D)
A rotating body such as a rotating body 161 that transmits a rotational driving force to a driving target such as a rotating shaft 153 of the sheet conveying device 151 and a piezoelectric element such as a piezoelectric element 174 are fixed, and a plate-like member 172 that contacts the rotating body. In a driving device such as the driving device 160 that drives the piezoelectric element to rotate the rotating body, the vibration type actuators include (Aspect A) to (Aspect C). The vibration type actuator 170 such as any one of the vibration type actuators 170) is provided.
According to this, as described in the first embodiment (to 3) described above, it is possible to provide a drive device that can achieve the same effects as any of the vibration type actuators of (Aspect A) to (Aspect C). .

(Aspect E)
In (Aspect D), the outer peripheral surface of the rotating body such as the rotating body 161 that comes into contact with the contact portions such as the plurality of protrusions 173 of the plate-like member such as the plate-like member 172 is in the direction of the rotation axis. And a position adjusting means such as a position adjusting means 180 for finely adjusting the position of the rotating body in the rotation axis direction with respect to the plurality of contact portions. is there.
According to this, as explained in the second embodiment (or 3), the following effects can be obtained. When at least one of the elastic plate-like member and the rotating body is worn and the pressure between each contact portion of the plate-like member and the rotating body is reduced, each contact of the plate-like member is performed by the position adjusting means. The position of the rotating body can be adjusted so that the part and the thick side of the outer shape of the rotating body are in contact with each other. Therefore, even if at least one of the plate-like member and the rotating body is worn over time, the pressure between the contact portions of the plate-like member and the rotating body is recovered, and the sheet conveying device 151 is rotated from the rotating body. It is possible to maintain the output characteristics of the rotational driving force transmitted in the driving symmetry of the shaft 153 and the like.

(Aspect F)
In (Aspect D), the outer peripheral surface of the rotating body such as the rotating body 161a that comes into contact with the contact portions such as the plurality of protrusions 173 of the plate-like member such as the plate-like member 172 has its rotation axis as an axis. And a position adjusting means such as a position adjusting means 180 for finely adjusting the position of the rotating body in the rotation axis direction with respect to the plurality of contact portions. .
According to this, as explained in the second embodiment (or 3), the following effects can be obtained. When the portion of the rotating body that comes into contact with each contact portion of the plate-like member is worn and the pressure between each contact portion and the rotating body decreases, the position adjusting means rotates the contact portion of the plate-like member with each contact portion. The position of the rotating body can be adjusted so that the part of the body that has not yet been worn comes into contact. By adjusting the position of the rotating body in this way, even if the rotating body wears over time, the pressure between each contact portion of the plate-like member and the rotating body is recovered, and the sheet is conveyed from the rotating body. The output characteristics of the rotational driving force transmitted to the driving target such as the rotating shaft 153 of the device 151 can be maintained.

(Aspect G)
In (Aspect E) or (Aspect F), a resonance frequency detection unit such as a resonance frequency detection unit 184 that detects a resonance frequency of the plate member such as the plate member 172 to which the piezoelectric element 174 or the like is fixed. And when the resonance frequency detected by the resonance frequency detection means changes by a predetermined value or more from the initial state, an alarm is issued and adjustment by the position adjustment means such as the position adjustment means 180 is urged. To do.
According to this, as explained in the second embodiment (or 3), the following effects can be obtained. Output of rotational driving force transmitted from the rotating body to a driving target such as the rotating shaft 153 of the sheet conveying device 151 even if wear occurs with time on a plate member having elasticity or a rotating body such as the rotating body 161. It can detect that the characteristic has changed. Therefore, feedback control is performed based on the detected detection result, and output characteristics can be efficiently maintained.

(Aspect H)
In any one of (Aspect D) to (Aspect G), the rotation body such as the rotation body 161 is detected by a detection plate 186 of a speed detection unit such as an encoder 185 that detects the rotation speed of the rotation body. A part is provided.
According to this, as described in the third embodiment, it is possible to feed back the rotation speed of the rotating body and control the rotation speed of the rotating body with high accuracy.

(Aspect I)
In any one of (Aspect D) to (Aspect H), the rotary body such as the rotary body 161 is characterized in that the rotary shaft portion is hollow.
According to this, as described in the first embodiment (to 3), the following effects can be obtained. It is possible to connect the driving object such as the rotation shaft 153 of the sheet conveying apparatus such as the sheet conveying apparatus 151 without using a gear, a pulley, a coupling means, etc., and the driving apparatus such as the driving apparatus 160 is simplified. And it becomes possible to comprise at low cost. Further, not only the number of parts can be reduced, but also the arrangement space can be reduced, and an ultra-compact driving device can be provided.

(Aspect J)
A plurality of driving rollers 152 and a pressure roller 154 such as a conveying roller for conveying a sheet such as a sheet P, and a rotating shaft member such as at least one rotating shaft 153 such as the driving roller 152 among the plurality of conveying rollers. In the sheet conveying apparatus such as the sheet conveying apparatus 151 provided with a driving device that rotationally drives the driving apparatus, a driving apparatus such as the driving apparatus 160 of any one of (Aspect D) to (Aspect I) is provided as the driving apparatus. It is characterized by.
According to this, as described in the first embodiment (to 3) described above, it is possible to provide a sheet conveying apparatus that has the same effect as any one of the driving apparatuses of (Aspect D) to (Aspect I).

(Aspect K)
In an image forming apparatus such as a multi-function machine 500 that includes one or more sheet conveying apparatuses that convey a sheet such as the sheet P in the apparatus, and that forms an image on the sheet, the one of the one or more sheet conveying apparatuses At least one of them is characterized by including a sheet conveying apparatus such as the sheet conveying apparatus 151 of (Aspect J).
According to this, as described in the above-described embodiment, it is possible to provide an image forming apparatus that has the same effect as the sheet conveying apparatus of (Aspect J).

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charger 3 Static elimination lamp 4 Cleaning apparatus 5 Intermediate transfer belt 6 Primary transfer roller 7 Secondary transfer roller 8 Fixing roller pair 9 Developing device 11, 12, 13 Stretching roller (intermediate transfer belt)
14 Tension roller (intermediate transfer belt)
15 Sheet conveying belt 16 Stretching roller pair (sheet conveying belt)
17 Optical Writing Device 18 Fixing Device 19 Belt Cleaning Device 100 Multifunction Machine Main Body 101 Paper Feed Path (Multifunction Machine Main Body)
102 Registration roller 103 Paper feed path (manual feed tray)
104 Paper feed roller (bypass tray)
105 Manual Tray 106 Paper Discharge Roller Pair 107 Paper Discharge Tray 108 Separation Roller (Manual Tray)
109 Switching claw 110 Sheet reversing device 111 Reversing introduction path 112 Single-side / double-side switching claw 120 Sheet reversing path 150 Double-sided conveying path 151 Sheet conveying apparatus 152 Driving roller 153 Rotating shaft 154 Pressing roller 160 Driving apparatus 161, 161 a Rotating body 170 Vibration type Actuator 171 Vibrating member 172 Plate member 173 Protrusion 174 Piezoelectric element 175 Through hole 176 Frame 178 Leaf spring 180 Position adjustment means 181 Position adjustment member 182 Disc (frame)
184 Resonance frequency detection means 185 Encoder 186 Detected plate (encoder)
187 Detector (encoder)
191 Front plate 192 Rear plate 200 Paper feed table 201 Paper feed cassette 202 Paper feed roller (paper feed table)
203 Separation roller (paper feed table)
204 Paper feed path (paper feed table)
205 Conveying roller 300 Scanner 301 Contact glass 302 Traveling body 303 Traveling body 304 Imaging lens 305 Reading sensor 400 Automatic document feeder 401 Original table 500 Multi-function machine

JP 2007-028761 A Japanese Patent Application Laid-Open No. 06-276763

Claims (11)

In a vibration type actuator having a plate-like member to which a piezoelectric element is fixed and rotating a rotating body that contacts the plate-like member by driving the piezoelectric element,
The plate-like member has elasticity and is provided with a through hole portion.
The through-hole portion of the plate-like member has a plurality of contact portions that come into contact with the rotating body arranged in the through-hole portion in a posture in which the thickness direction of the plate-like member and the rotation axis are parallel to each other. ,
Each of the contact portions is pressurized toward the rotating shaft of the rotating body by an elastic force due to elastic deformation of the plate-like member, and moves in an elliptical locus by driving the piezoelectric element. The vibration type actuator according to claim 1,
A holding member that holds the plate-like member, and a support member that supports the plate-like member through the holding member so that a minute relative movement is possible,
By driving the piezoelectric element, a plurality of resonances are simultaneously generated in the plate-like member, thereby causing the plurality of contact portions to perform an elliptical locus motion. In the vibration type actuator according to claim 1 or 2,
The vibration-type actuator is characterized in that the motion of the elliptical trajectory of the plurality of contact portions of the plate-shaped member is performed in a phase that is axially symmetric with respect to the rotational axis of the rotating body. A rotating body that transmits a rotational driving force to a driving target, and a vibration type actuator having a plate-like member fixed to the piezoelectric element and in contact with the rotating body, and driving the piezoelectric element to rotate the rotating body. In the drive device
A drive device comprising the vibration type actuator according to claim 1 as the vibration type actuator. The drive device according to claim 4, wherein
The outer peripheral surface of the rotating body that comes into contact with the plurality of contact portions of the plate-like member has a tapered shape that is inclined with respect to the direction of the rotation axis,
A driving apparatus comprising: a position adjusting unit that finely adjusts the position of the rotating body in the rotation axis direction with respect to the plurality of contact portions. The drive device according to claim 4, wherein
The outer peripheral surface of the rotating body that comes into contact with the plurality of contact portions of the plate-like member has a cylindrical shape with the rotation axis as an axis,
A driving apparatus comprising: a position adjusting unit that finely adjusts the position of the rotating body in the rotation axis direction with respect to the plurality of contact portions. The drive device according to claim 5 or 6,
Resonance frequency detection means for detecting the resonance frequency of the plate-like member to which the piezoelectric element is fixed,
The drive device according to claim 1, wherein when the resonance frequency detected by the resonance frequency detection means changes by a predetermined value or more from an initial state, an alarm is issued to prompt adjustment by the position adjustment means. The drive device according to any one of claims 4 to 7,
The driving device according to claim 1, wherein the rotating body is provided with a detected portion of speed detecting means for detecting a rotating speed of the rotating body. The drive device according to any one of claims 4 to 8,
The rotating device has a rotating shaft portion that is hollow. In a sheet conveying apparatus comprising: a plurality of conveying rollers that convey a sheet; and a driving device that rotationally drives at least one of the plurality of conveying rollers.
A sheet conveying apparatus comprising the driving apparatus according to claim 4 as the driving apparatus. In an image forming apparatus that includes one or more sheet conveying apparatuses that convey a sheet in the apparatus and that forms an image on the sheet,
An image forming apparatus comprising the sheet conveying device according to claim 10 as at least one of the one or more sheet conveying devices.

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