JP2557450B2 - Paper feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device such as a printer using a piezoelectric element, and more particularly, a paper feeding device that applies a feed driving force and a pressure contact force to a paper by using a pair of piezoelectric actuators. Regarding the feeder.

2. Description of the Related Art A piezoelectric actuator is configured by combining a piezoelectric element that vibrates at a high cycle with the application of an AC voltage and an elastic body, and a driving force for moving a driven object (animal object) is generated by a traveling wave generated by the elastic body. It is known to be obtained. The animal body is attached to the piezoelectric actuator via an elastic body, and a driving force that moves in the opposite direction is given by the traveling wave generated by the elastic body. To take out this driving force,
The driving force for moving the animal body cannot be obtained only by the traveling wave generated by the elastic body. Therefore, the animal body is pressed against the elastic body of the piezoelectric actuator with a constant pressing force, and the pressing force generates a driving force in the direction opposite to the traveling direction of the traveling wave.

FIG. 7 shows a conventional piezoelectric actuator provided with a pressure contact means, and shows an example applied to a paper feeding device of a printer, for example. The piezoelectric actuator 1 is disposed on one side of the paper 100 feeding path. Piezoelectric actuator 1
Is composed of a piezoelectric element 1a and an elastic body 1b, and the paper 100 which is an animal body is attached to the elastic body 1b and is sent in the direction of the arrow together with the generation of a traveling wave due to vibration. The pressure contact means 2 for the sheet 100 is arranged on the other side of the feeding path. The pressing means 2 includes a roller 5 pivotally attached to a part of the chassis 3 via an arm 4, and the roller 5 via the arm 4 to the sheet 100.
And a leaf spring 6 that urges in the direction of pressure contact.
In the arm 4, the roller 5 is attached to the chassis 3 by the shaft 7 to form the paper.
It is rotatably supported in a direction in which it is pressed against or separated from 100. A roller 5 is rotatably supported at its free end. One end of the leaf spring 6 is fixed to the chassis 3, and the other end is hooked in the middle of the arm 4 via a pin 8. The chassis 3 moves in a direction in which the roller 5 separates from the piezoelectric actuator 1 when the paper 100 is loaded, and moves to the piezoelectric actuator 1 side when the paper 100 is loaded, and the roller 5 is elastically moved through the paper 100. Pressure contact with body 1b. The pressure contact force is due to the bias of the leaf spring 6.

When an AC voltage is applied to the piezoelectric element 1a during paper feeding, the elastic body 1b generates a traveling wave with a high cycle according to the applied voltage. On the other hand, the paper 100 that is in contact with the elastic body 1b is pressed by the roller 5 due to the urging force of the leaf spring 6 to cause the elastic body 1b to move.
Since it is pressed against, the driving force for feeding in the direction opposite to the traveling direction of the traveling wave is given by the reaction force of the pressing. As a result, the paper 100 is fed in the paper feed direction along with the vibration of the elastic body 1b.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In a paper feeding device using a conventional piezoelectric actuator as a drive source, a large frictional force is generated between the paper and the elastic body (vibrating body) of the piezoelectric actuator, and smooth feeding drive can be performed. There are no drawbacks. Therefore, as shown in the conventional example of FIG. 7, the paper pressure contact means is composed of a roller body, and the roller is pressed against the paper 100 by point contact. According to this, the roller body is pressed against the paper by point contact,
Since it rotates in the same direction as the paper feed drive,
The frictional force will definitely decrease. However, according to this configuration, the paper feed driving force is taken out from the piezoelectric actuator by the pressure contact due to the point contact of the roller body.
It is necessary to increase the pressure contact force sufficiently to obtain the necessary driving force. To this end, there is no choice but to increase the number of roller bodies or increase the diameter of the roller bodies by a certain amount or more to increase the pressure contact force. If the roller diameter is increased or the number of rollers is increased in this way, the paper feeding device becomes large, and it becomes impossible to make the paper feeding device compact and thin. By the way, even in the current device configuration, the roller diameter of the roller body alone is about 40 to 50 m / m, and if the thickness of the accompanying mechanism is added to it, it will be 50
The thickness is more than m / m. Therefore, if the roller diameter is increased or the number of rollers is increased, there arises a problem that the apparatus configuration becomes more complicated and larger, which is not a good idea.

The present invention has been proposed in view of the above-mentioned problems, and realizes a small size, a light weight, and a thin shape of a paper feeding device by performing press contact and feed driving of a paper using a pair of piezoelectric actuators. The purpose is.

Means for Solving the Problems In order to achieve the above object, the present invention provides a pair of piezoelectric actuators, at least one of which generates a traveling wave type feed wave by a combination of a plate-shaped elastic body and a piezoelectric element. Characterized in that one of them is formed as a drive means and the other is arranged as a pressure contact means so as to be opposed to each other, and a biasing means such as a leaf spring for biasing the pressure contact means to the drive means via a sheet is provided. There is.

A longitudinal vibration type piezoelectric actuator is used as the pressing means. In that case, a pressure force is applied to the sheet attached to the drive means by a wave associated with the longitudinal vibration.

In the present invention, the piezoelectric element is bonded to the flat elastic body by selecting the polarity so that one piezoelectric actuator generates a traveling wave type wave and the other piezoelectric actuator generates a longitudinal vibration type wave. . More preferably, a piezoelectric element is sandwiched and bonded between two flat plate-shaped elastic bodies to form a traveling wave generation type and a longitudinal vibration type piezoelectric actuator in a flat plate laminated structure. The sheet interposed / compressed between the drive means and the pressure contact means receives a pressing force due to the acceleration G at the top of the wave by the longitudinal vibration wave generated by the pressure contact means, and the drag force and the traveling wave generated by the drive means. And are driven and driven in the opposite direction of the traveling wave.

In feeding the working paper, the paper is interposed between the elastic body of the drive means and the elastic body of the pressure contact means, and is pressed and clamped between the two means by a biasing means such as a leaf spring.

Next, when an AC voltage of about several KHz is applied to both the piezoelectric element of the driving means and the piezoelectric element of the pressure contact means, the piezoelectric elements of the two means start vibrating at a high cycle according to the applied voltage. One of them is a traveling wave type vibration and the other is a longitudinal vibration type vibration, which vibrates in a direction orthogonal to the element surface. Due to this vibration, the elastic body (vibrating body) of the driving means generates traveling waves of the same cycle that travel (propagate) in a predetermined direction parallel to the element surface. Further, the elastic body (vibration body) of the pressure contact means generates a longitudinal vibration type wave that does not progress, that is, a wave like a standing wave in the same cycle. Then, the sheet pressed and sandwiched between the pressing means and the driving means moves in a direction opposite to the traveling (propagating) direction of the traveling wave by the synergistic effect of the traveling wave generated by the driving means and the drag force of the pressing force generated by the pressing means. Driven. The pressing force of the pressure contact means causes a reaction force to act on the paper from the drive means, and the reaction force extracts the drive force for feeding and driving the paper from the traveling wave generation portion of the drive means. That is, the paper is fed and driven by the cooperation of the traveling wave and the drag force. Since the pressing force by the pressing means is a distributed load, a uniform pressing force acts on the entire contact surface. Since the driving means and the pressure contact means have a flat plate structure, a large torque (displacement) transmission area can be obtained, and a large driving force can be obtained with a small torque (displacement) transmission force. , It is sufficient to increase only the press contact area, and the thickness does not increase.

EXAMPLES Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of a paper feeding device according to the present invention, FIG. 2 is a perspective view showing a piezoelectric actuator on the driving means side, and FIG. 3 is a perspective view showing a piezoelectric actuator on the pressure contacting means side.

The paper feeding device according to the present invention is applied to, for example, a printer, and the driving means 10 disposed on one side of the feeding drive path of the paper 100 and the driving means 10 and the paper 100 are opposed to each other. And the pressure contact means 20 that are arranged as shown in FIG. The sheet 100 is driven by the leaf spring 30 to drive the sheet 100.
It is crimped and held between the pressure contact means 20 and the pressure contact means 20, and is driven and driven in a predetermined direction by driving both means 10, 20. Paper 100 is
For example, it is a flat plate or a sheet of paper or the like applied to a printer, but is not necessarily limited to these, and the shape, size, etc. are limited as long as it can be fed and driven by this device. Widely applicable without

The driving means 10 is composed of two planar metallic elastic bodies 10.
A piezoelectric element 103 is sandwiched between 1 and 102 in a sandwich shape and is laminated in a flat plate shape to form a traveling wave type piezoelectric actuator. This piezoelectric actuator is formed in a flat plate laminated structure having a thickness of about 2 to 3 m / m, and is arranged on the base chassis 200 of the device.

The elastic bodies 101 and 102 are formed in a shape in which two elliptical loop shapes are arranged in pairs, and the piezoelectric elements 103 ... Are bonded between the linear portions 101A and 102A. Straight part 101
Three A and 102A are formed in parallel along the major axis direction of the elliptical shape, and the piezoelectric elements 103 ... Are attached to the flat surface thereof. Piezoelectric element 103 ... is a straight line portion 1
It is divided left and right with the center of 01A and 102A as the boundary. Then, when AC voltage is applied, its polarities are the same straight line portions 101A and 102A so that traveling wave type vibration is generated.
In the figure, the left side of the figure is set to +-+ and the right side is set to-+-. That is, the piezoelectric elements 103 ... Are formed of element rows whose polarities are alternately reversed. Both surfaces of each piezoelectric element 103 are electrodes, and lead wires 103a and 103b drawn from the electrodes are connected to a drive circuit 105 formed on a main circuit board or the like. The drive circuit 105 is connected to a control unit 106 that controls the operation of a device to which the present device is applied, and receives drive signals from the control unit 106 to be drive-controlled. By this drive, the drive circuit 105 applies an alternating voltage having a high cycle of several + KHz, for example, 30 to 40 KHz to the piezoelectric elements 103. Upon application of this AC voltage, the piezoelectric elements 103 ... So-called traveling wave type vibration in a direction orthogonal to the element surface at a high cycle of several + KHz depending on the arrangement of the polarities. The elastic body 10 resonates with the vibration of the piezoelectric element 103 ...
1 and 102 generate traveling waves that travel (propagate) in one of the in-plane directions. By the traveling wave generated by the elastic bodies 101 and 102,
The driving force for feeding the paper 100 under pressure is extracted from the linear portions 101A and 102A.

The pressure contact means 20 is formed in substantially the same shape as the drive means 10 with the sheet 100 sandwiched therebetween, and the piezoelectric elements 203 ... Are sandwiched between two metal elastic bodies 201, 202 each having a planar shape. It is sandwiched and formed into a flat plate shape. This constitutes a longitudinal vibration type piezoelectric actuator. This piezoelectric actuator has a thickness of 2 to
It is formed in a flat plate laminated structure of about 3 m / m and is supported by a mounting frame 110 of the device.

The elastic bodies 201 and 202 of the press contact means 20 are elastic bodies of the drive means 10.
It is formed in the same shape as 101 and 102 and in a symmetrical shape with the paper 100 sandwiched therebetween. That is, the elastic bodies 201 and 202 are made of a metal elastic material and are formed into a pair of elliptical loop shapes, and the piezoelectric element 203 is formed between the linear portions 201A and 202A.
Are pasted together. The straight line portions 201A and 202A correspond to the straight line portions 101A and 102A of the elastic bodies 101 and 102, respectively.
Three ellipses 201 and 202 are formed in parallel in the major axis direction. The piezoelectric element 203 is attached on the flat surface. Piezoelectric element 203 ... is a linear portion 201A, 202
It is divided at the left and right of the center of A as a boundary.

The respective polarities of the piezoelectric elements 203 ... Are set to + so that so-called longitudinal vibration occurs in the plane when an AC voltage is applied. Both surfaces of each piezoelectric element 203 ... Are electrodes, and lead wires 203a and 203b led out from the electrodes are connected to the drive circuit 105 described above. When the drive circuit 105 applies an alternating voltage of about 30 to 40 KHz, the piezoelectric elements 203 ... Make longitudinal vibrations according to the polarity in the element plane. The elastic body 2 resonates with the vibration of the piezoelectric element 203.
01 and 202 generate longitudinal vibration type waves in the plane, so-called non-progressive standing waves or sine curve waves.

The pressure contact means 20 is biased toward the drive means 10 by a leaf spring 30 attached to the attachment frame 110. Due to the bias of the leaf spring 30, the pressure contact means 20 is pressed against the paper 100 by surface contact. The sheet 100 is interposed between the drive means 10 and the pressure contact means 20, and is pressed and held in a surface contact state. Then, it is fed and driven by driving both means.

Next, the operation of feeding drive of the sheet 100 by this apparatus and the outline of the operation principle will be described.

When the sheet 100 is driven to be fed, the sheet 100 has an elastic body 102 of the driving means 10 and an elastic body 2 of the pressure contact means 20 as shown in FIG.
It is sandwiched between 02 and 02, and is pressed and sandwiched between both means 10 and 20 in a surface contact state by the biasing force of the leaf spring 30.

The pressure contact and release of the sheet 100 is performed by moving the entire pressure contact means 10 in the direction of pressure contact with or separation from the drive means 10 via the attachment frame 110 by the operation of the link means (not shown).

Next, in response to the control signal from the control unit 106, the drive circuit 105 provides the drive signal to the drive means 10 and the pressure contact means 20. With this drive signal, an AC voltage having a cycle of several + KHz, for example, 30 to 40 KHz is applied from the AC power source to the piezoelectric elements 103 and 203 of both the drive unit 10 and the pressure contact unit 20.
Then, the piezoelectric element 103 of the driving means 10 oscillates as a traveling wave at a high cycle according to the applied voltage, as shown in FIGS. 4 and 5. Resonating with this vibration, the elastic bodies 101 and 102 generate traveling waves propagating in the in-plane direction at the same cycle as shown in FIGS. Elastic body generating this traveling wave
Focusing on one point of 101, 102, for example, the elastic body 102 that is in direct contact with the paper 100, as shown in FIG. 5, an elliptical motion is made in the direction opposite to the traveling direction of the wave (indicated by the arrow →). By the force of this elliptic movement, a feeding force for feeding and driving the sheet 100 is extracted as described later. Paper 100 is elastic body 101, 102
Is driven in the direction opposite to the propagation direction of the traveling wave.

On the other hand, the piezoelectric element 203 of the press-contact means 20 vibrates in a longitudinal vibration direction in a direction orthogonal to the element surface at a high cycle of several + KHz according to the applied voltage by applying an AC voltage. Resonating with this vibration, the elastic bodies 201 and 202 generate longitudinal vibration type sine curve-shaped waves in the plane, that is, so-called standing waves that do not travel in the in-plane direction.

As described above, by driving the driving means 10 and the pressure contact means 20, one elastic body 101, 102 in contact with the sheet 100 generates a traveling wave, and the other elastic body 201, 201 generates a longitudinal vibration type wave. Then, with the generation of the wave, the paper 100 is pressed by the pressure contact means 20.
A pressing force is applied to press. Due to this pressing force, a drag force F is applied to the paper 100 from the contact portion of the driving means 20.
Works. The driving force for feeding and driving the paper 100 is taken out from the traveling wave generation portion of the driving means 20 by this reaction force F. This driving force is generated by the linear portions 101A, 102A, 201 of the elastic bodies 101, 102 of the driving means 10 and the elastic bodies 201, 202 of the pressure contact means 20.
A, taken from 202A. Then, the drag force F and the counterclockwise elliptical motion generated in the traveling wave generation portion cooperate to form the paper.
100 is fed and driven in the direction opposite to the propagation of the traveling wave shown by the arrows in FIGS.

The pressing force applied to the animal subject 100 by the pressure contact means 10 is a surface load and therefore a distributed load. Therefore, the pressing force can be applied over a wide area. And the pressure welding means
As shown in FIG. 5, the elastic bodies 101 and 102 of 10 come into contact with the paper 100 at the top of the longitudinal vibration type wave, and a pressing force of acceleration G accompanying vibration is applied to the paper 100 through the top of this wave. To be Since the acceleration G is accompanied by the vibration with a high cycle of about several KHz, the acceleration G becomes several hundred times or more the gravity acceleration g, and the acceleration G causes the press-contact means 20 to appear to be slightly spaced from the paper 100. It will be in a floating state. Therefore, the frictional force between the pressure contact means 20 and the paper 100 is reduced. Moreover, even though the pressure contact means 20 is apparently lifted, the pressing force of the acceleration G acts as a uniformly distributed load through the top of the wave of the vibration, so that the paper 100 is fed and driven. Time,
A uniform pressure contact force is applied over a wide area with a uniform load and sufficient pressing force. This allows the paper
The driving force without fluctuations or unevenness acts on the entire pressure contact surface of the paper 100 without being affected by the condition of the surface of the paper 100 and the like.

Further, since the displacement (torque) transmission area of the drive means 10 and the pressure contact means 20 to the sheet 100 is large and the sheet 100 receives the pressure contact force due to the distributed load, a small displacement (torque) transmission force causes a large driving force from a large area. You can take it out.

As described above, the sheet 100 is fed and driven by the traveling wave generated by the driving unit 10 and the longitudinal vibration type wave generated by the pressure contact unit 20 while being sandwiched between the both units.

EFFECTS OF THE INVENTION As is clear from the above description, according to the present invention, since the pressing force by the pressing means is a distributed load, the pressing force acts on the entire contact surface with a uniform pressing force. The driving means and the pressure contact means have a flat plate structure, a large torque (displacement) transmission area can be obtained, and a large driving force can be taken out with a small torque (displacement) transmission force. Therefore, the paper feeding device can be made much smaller, lighter and thinner than the conventional one. By the way, the total thickness of the combination of the driving means and the pressure contact means is specifically about 2 to 3 m / m at most, that is, + m / m or so due to the structure of the piezoelectric actuator. It can be said that this is significantly thinner and lighter than the conventional thickness of 50 m / m or more.

It is also possible to use a traveling wave generation type piezoelectric actuator similar to the drive means as the pressure contact means. In that case, it suffices to slightly change the arrangement of polarities of the piezoelectric element.

[Brief description of drawings]

FIG. 1 is a front view of a paper feeding device according to the present invention, FIG. 2 is a perspective view of its essential parts, FIG. 3 is a perspective view of its essential parts, and FIGS. 4 and 5 are operation principle diagrams of this device. FIG. 6 is a plan view showing a paper feeding drive operation by this apparatus, and FIG. 7 is a front view of a main part showing a conventional example. 100 ... paper, 10 ... driving means, 101,102 ... elastic body, 103 ... piezoelectric element, 20 ... pressure contact means, 201,202 ... elastic body, 203 ... piezoelectric element, 101A, 102A, 201A , 202A: straight line part, F: drag force, G: acceleration.

Claims (5)

(57) [Claims] 1. A pair of piezoelectric actuators, at least one of which generates a traveling-wave-type feed wave, are formed by a combination of a flat elastic body and a piezoelectric element, and one of them serves as a driving means and the other serves as a pressure contact means. A sheet feeding device, which is disposed opposite to each other, and is provided with a biasing means such as a leaf spring for biasing the pressure contact means to the drive means via a sheet. 2. The pressure contact means is constituted by a longitudinal vibration type piezoelectric actuator, and a pressure contact force by longitudinal vibration is applied to the sheet attached to the drive means. The paper feeder described. 3. A piezoelectric element is bonded to a plate-shaped elastic body by selecting the polarity, and one piezoelectric actuator generates a traveling wave type wave by applying an AC voltage, and the other piezoelectric actuator generates a longitudinal vibration type wave. The paper feeding device according to claim 1 or 2, wherein the paper feeding device is configured to generate. 4. A piezoelectric element is sandwiched and bonded between two plate-like elastic bodies so that the traveling wave generating type piezoelectric actuator and the longitudinal vibration type piezoelectric actuator are symmetrical with respect to each other. 3. The paper feeding device according to claim 1, wherein the paper feeding device has a flat plate laminated structure. 5. The sheet crimped between the drive means and the pressure contact means receives a pressing force by acceleration G at the top of the wave by the longitudinal vibration wave generated by the pressure contact means, and the drag force and the drive means are generated. The paper feeding device according to claim 1, wherein the paper feeding device is driven by the traveling wave in a direction opposite to the propagation direction of the traveling wave.