JP2996504B2 - Vibration wave drive for sheet conveyance - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying vibration wave driving device using a vibration wave motor.

[Prior Art] FIG. 5 shows an example of a conventional vibration wave motor.

In FIG. 5, reference numeral 51 denotes a stator made of an elastic material such as stainless steel, and a piezoelectric element 52 such as a piezoelectric ceramic is attached on one surface with an adhesive. Piezoelectric element 52
The electrodes are arranged as shown in FIG. 6, for example, when viewed from the rotation axis direction.

Here, the electrodes marked in the figure are portions that expand when a certain voltage is applied, and the electrodes marked indicate regions that contract in reverse. When the polarity of the applied voltage is changed, the part shrinks and the part expands. The length of each individual electrode is 1/2 of the wavelength λ of the generated ultrasonic wave. These electrodes are divided into two groups A and B in the figure, and both are shifted by λ / 4. Electrode groups A and B
The electrodes E ₂ , E ₁ applied to are AC voltages that are 90 ° out of phase with respect to time. With such a configuration, two standing waves generated by the electrode groups A and B are combined, and the rotor of the stator 51 is
A traveling wave that progresses with time is generated in a portion in contact with 55.

The traveling wave drives the rotor 55 to rotate. A base 53 supports the stator 51 and the piezoelectric element 52. The rotor 55 is supported by the base 53 via a bearing 58. Also, in order for the rotor to obtain a driving force from the stator, it is necessary to apply an appropriate pressing force to the contact surface between the two.
Is in pressure contact with the stator 51 by the repulsive force of the disc spring 57 compressed between the nut 56 and the bearing 58 attached to the shaft.

FIG. 3 is a schematic perspective view of a scanning optical device using such a vibration wave motor as a sub-scanning drive source, and FIG. 4 is a longitudinal sectional view thereof.

In the drawing, reference numeral 71 denotes a sub-scanning roller, and 72 denotes a nip roller.The nip roller 72 is constantly pressed by the sub-scanning roller 71, and the nip portion holds the sheet 73. The sheet is transported in the sub-scanning direction. Reference numeral 74 denotes a polygon mirror, which receives a laser beam 75 from a laser device (not shown) via a reflection mirror 76 and a nip roller 72.
And a main scan is performed. The sub-scanning roller 71 is disposed between the opposed frames 8 and 9 of the apparatus main body, and each shaft extending to both ends is rotatably supported by bearings 7 and 19 provided on these frames 8 and 9. I have. The nip roller 72 has a bearing 63 provided on a holding lever 62 having a shaft portion 64 extending to both ends thereof spring-biased by a spring (not shown).
And is pressed against the sub-scanning roller 71 by the urging force of the spring.

The sub-scanning roller 71 has one shaft mounted directly on the roller 5 of the vibration wave motor and fixed with screws 6.

This vibration wave motor has basically the same structure as that shown in FIG. 5, in which an annular stator 1 made of an elastic material such as stainless steel is fixed to a frame 8 with screws 3 and the other end is provided. A compression coil spring 12 for pressurization is mounted on the shaft, and washers 11 and 13 are provided at both ends of the compression coil spring 12 (the washer 13 is in contact with the inner ring of the bearing 19). A spring force is applied to the compression coil spring 12 by the retaining ring 10 and a reaction force is applied to a contact surface between the stator 1 and the rotor 5 to generate a frictional force on the contact surface.
By applying an alternating electric field having a different phase as described above to the piezoelectric element 2 bonded and fixed to one surface of the stator 1, a progressive vibration wave is excited in the stator 1 and the rotor is driven to rotate in a predetermined direction. . When a vibration wave motor is used as a drive source of the sub-scanning roller of such an apparatus, for example, the vibration wave motor is small and lightweight, and can obtain a low speed and high torque, so that it can be directly connected to the sub-scanning roller. Since the speed reduction mechanism can be omitted, and the speed stability at low speed is excellent, the uniformity of the sheet conveyance speed is improved.

[Problems to be Solved by the Invention] However, in such an apparatus using a vibration wave motor as a driving source, the rotor and the stator of the vibration wave motor are always in pressure contact with each other. It is pointed out.

This is because when the sheet is sandwiched between the sub-scanning roller and the nip roller and the driving is stopped due to a trouble such as a sheet jam or a power failure, the sub-scanning roller is driven by the vibration wave motor directly connected. The rotation becomes impossible due to the holding force due to the pressure contact between the roller and the stator.

Therefore, there is a problem that the sheet cannot be removed by directly pulling the sheet.

However, when the nip roller is lifted, the binding force of the sheet can be released, but the hands of the nip roller cannot be easily reached due to the presence of the frames 8 and 9 of the apparatus main body. This is because a motor (vibration wave motor for driving the sub-scanning roller) is often arranged on the rear surface of the apparatus body, and an optical system is often arranged above the nip roller. It is possible from the frame 9 side on the front of the apparatus.

Therefore, it is possible to drive the holding lever of the nip roller by remote control from the frame 9 side, but this mechanism has a problem that the device becomes complicated.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem, to enable release of pressure between a rotor and a stator with a simple structure, and to enable the rotation of a sheet conveying roller so that a sheet can be pulled out. To provide a vibration wave driving device for use.

[Means for Solving the Problems] The configuration of a sheet conveying vibration wave driving device for realizing the object of the present invention is a pressing member for a first member having an electromechanical energy conversion element fixed to a vibrating body. And press-contact the second member, and relatively rotate the first member and the second member with a vibration wave excited by the vibrating body by applying an alternating signal to the electro-mechanical energy conversion element. A vibration wave motor that rotationally drives the rotating shaft portion, a roller that is fixed to the rotating shaft member and rotatably supported between opposed frames, and conveys a sheet; A pressing force canceling means for changing the pressing force of the pressurizing means for pressing and holding the member and the second member, wherein the second member is provided at one end side with the roller interposed therebetween; The pressure release means is provided on the other end side, The operation unit of the pressurizing force canceling means is arranged outside between the frames.

[Operation] The above-described vibration driving apparatus for conveying a sheet is configured such that the first member and the second member in a pressurized state, for example, the stator and the roller of the vibration wave motor, Release the pressing force of, and ensure the free rotation of the rotor.

[Embodiment] Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of a sheet conveying vibration wave driving device according to the present invention.

In this embodiment, the same members as those shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the front side of the apparatus main body, that is, the frame 9
Shaft that constitutes the output shaft of the vibration wave motor that protrudes to the side
4a is pressed against the rear surface (toward the frame 8) against the spring force of the compression coil spring 12, and the pressure contact between the rotor 5 and the stator 1 is released.

This press-contact release mechanism is composed of a cylindrical fixing tool 15 having a screw portion formed on the outer peripheral surface, and a bottomed knob 14 having an internal screw portion screwed into the screw portion of the fixing device 15 and fixed. Fixture 15
Is surrounded by the screw 18 so as to surround the shaft portion 4a.
It is fixed to. A steel ball 17 is attached to the bottom inner surface of the knob 14 via a cap 16 so as to face the end surface of the shaft portion 4a. Note that the knob 14 as an operation unit is disposed inside an exterior cover (not shown) of the apparatus main body, and can be operated by, for example, opening this exterior cover.

The pressing release operation by the knob 14 is performed by stopping the sub-scanning roller 4 due to jamming or power failure, for example, when removing a sheet, opening an exterior cover (not shown), and exposing the knob 14 to rotate the knob 14. Becomes possible. For example, when the knob 14 is rotated clockwise, the knob moves to the left in FIG.
Contact the right end surface of the sub-scanning roller 4. Knob 14
When the knob is rotated, the knob 14 further moves to the left in the figure,
The spring 12 is compressed to move the sub-scanning roller 4 leftward in the drawing. As a result, a gap occurs between the rotor 5 and the stator 1. Therefore, the holding force of the sub-scanning roller 4 is released, and the sub-scanning roller 4 can be easily rotated, and the sheet can be removed.

In the present embodiment, as described above, the rotor 5 and the sub-scanning roller 4 are integrated, but the vibration wave motor and the sub-scanning roller are separate bodies, and the both may be connected by a flexible coupling or the like. Good.

FIG. 2 shows another embodiment of the present invention. The difference between this embodiment shown in FIG. 2 and the above-described embodiment shown in FIG. 1 is that a frame for connecting a sub-scanning roller, a motor, a bearing, a laser rotary encoder, and a release mechanism is provided, and these are unitized. That is, it is made detachable from the apparatus body as a whole. The other parts are almost the same as those in FIG.
The same reference numerals indicate the same members.

In FIG. 2, reference numeral 21 denotes a sub-scanning roller, which is a roller portion 21a in contact with the sheet, a front shaft portion 21b in which the bearing 19 is fitted, a rear shaft portion 21c in which the bearing 7 is fitted and the rotor 5 is coupled, and a laser rotary. Rear end shaft 21 to which encoder diffraction grating 24 is coupled
Consists of d. Reference numeral 22 denotes a unit frame, which is a connecting portion 22a for holding the bearings 7, 19, fitting portions 22b, 22c fitted to the fitting portions of the frames 8, 9 of the apparatus main body, and a unit frame for fixing the frame 8 with bolts (not shown). An opening (not shown) is provided in the flange portion 22d, the housing portion 22e, and the connecting portion 22a to expose the roller portion 21a to the outside.

The left end in the figure is a laser rotary encoder section, which has a disk-shaped rotating grating 24, a semiconductor laser, a photodiode,
Optical system 25 including prism, etc., reflective optical system 26, cover 2
7, the base 28 and the like. The laser rotary encoder is small and lightweight, has a small inertia of a rotating part, and can generate a high pulse of 80,000 pulses or more per rotation. Therefore, more precise control becomes possible,
Ideal for vibration wave motors with good control response.

By unitizing the motor unit as in the present embodiment, the following effects can be simultaneously obtained in addition to the effects of the embodiment shown in FIG. The performance of the motor unit alone can be estimated in the state of use incorporated in the device by the performance evaluation of the motor unit alone, thereby facilitating quality control. When removing the motor unit from the apparatus main body, a bolt (not shown) on the flange portion 22d can be removed, and the entire unit can be pulled leftward in the figure. In this way, attachment / detachment from the apparatus main body is easy, and serviceability such as maintenance and inspection at the time of assembly or after installation is improved. In addition, since the performance can be guaranteed by the motor unit alone, the performance at the time of shipment can be reproduced simply by replacing the motor unit at the installation location even in the event of a failure.

In the above-described embodiment, the rotor is rotated. However, the reverse is also possible.

[Effect of the Invention] According to the invention according to claim 1, driving of the vibration wave motor,
Stop holding, free rotation by manual operation can be arbitrarily selected,
When the operation unit of the pressurizing force releasing means is freely rotated, the sheet holding force can be released even in a non-energized state, and the sheet can be easily pulled out when a jam occurs. In addition, the vibration wave motor and the pressing force canceling means are separately arranged on both sides of the roller, and the vibration wave motor and the drive circuit can be arranged on the side not accessed by the user to improve safety. Since the operation unit of the pressing force releasing means disposed on the opposite side is disposed outside the frame for rotatably supporting the roller, it is not necessary to perform a pressing force releasing operation by putting a hand in the back of the device, Pressing force can be easily released.

According to the second aspect of the present invention, since the pressing force of the pressing means acts in the axial direction, the configuration of the pressing force releasing means can be simplified.

According to the third aspect of the invention, quality control is easy and maintenance is easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment, FIG. 3 is a schematic perspective view of a conventional sheet feeder, FIG. 4 is a sectional view of the same, FIG. 5 is a sectional view of a conventional vibration wave motor, and FIG. 6 is a view showing an arrangement of electrodes of the piezoelectric element. DESCRIPTION OF SYMBOLS 1 ... Stator, 2 ... Piezoelectric element 4 ... Sub scanning roller, 5 ... Rotor 14 ... Knob, 17 ... Steel ball

────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiichi Kawasaki 53, Imaiue-cho, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Canon Corporation Kosugi Office (56) References JP-A 1-179056 (JP, A) −68693 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/10-2/16

Claims (3)

(57) [Claims] An alternating signal to said electromechanical energy conversion element is brought into pressure contact with a second member via a pressing means against a first member having an electromechanical energy conversion element fixed to a vibrating body. A vibration wave motor for rotating the rotation shaft by rotating the first member and the second member relative to each other with a vibration wave excited by the vibrator by applying the vibration wave, and fixed to the rotation shaft. , Rotatably supported between opposing frames, and resisting the pressing force of a roller for conveying a sheet and the pressing means for pressing and holding the first member and the second member. Pressure releasing means for changing the pressure, and the second member is provided on one end side of the roller, and the pressing force releasing means is provided on the other end side, and the operating section of the pressing force releasing means is Seat characterized by being arranged outside between frames Feed vibration wave driven apparatus. 2. The apparatus according to claim 1, wherein the pressing direction of said pressing means for pressing and holding said first member and said second member substantially coincides with the axial direction of said rotary shaft. Item 2. A sheet conveying vibration wave driving device according to Item 1. 3. The sheet conveying vibration wave driving device according to claim 1, wherein said vibration wave motor, said pressurizing means, and said pressing force releasing means are unitized.