JPH0342443A - Sheet feeder - Google Patents

Abstract

PURPOSE:To increase the conveying force of a sheet and allow the sheet with a very small friction coefficient to be conveyed by coating the sheet contact faces of vibrators with soft flexible films or layers such as rubber. CONSTITUTION:Sheet contact faces of both vibrators 18 and 19 are coated with films 22 and 23 made of a soft elastic material such as rubber. A sheet S is conveyed by a large conveying force while being firmly held between both vibrators 18 and 19. The sheet S is not smooth against the vibrators 18 and 19, thus the sheet holding force when the sheet S is stopped is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sheet feeding device for moving thin sheets such as pieces of paper, and is particularly applicable to devices such as computers, copying machines, facsimile machines, word processors, and typewriters. The present invention relates to a sheet feeding device suitable as a paper feeding device to be installed.

[Prior Art] A sheet of paper or the like is sandwiched between a pair of vibrating bodies that are excited by a vibrator such as a piezoelectric element so as to generate progressive vibration, and the vibrating body applies a propulsive force to the sheet. A sheet feeding device for moving sheets has been proposed by the present applicant; for example, Japanese Patent Laid-Open No. 177243/1983 discloses an invention of a sheet feeding device proposed by the present applicant.

FIG. 4 is a diagram showing an example of the sheet feeding device disclosed in the above-mentioned publication.

In FIG. 4, 1 and 2 are vibrating bodies, and 3 to 5 are vibrators such as electrostrictive elements fixed to the vibrating bodies 1''EL and 2, respectively (one of the four vibrators is (not shown in FIG. 4), 6 is a support member that supports the vibrating body 1 and urges the vibrating body 1 to come into pressure contact with the sheet S, and 7 is a part of the housing of the sheet feeding device. a bottom plate to which the vibrating body 2 is fixed; side plates 8 and 9 fixed to the bottom plate and fixed to the support member 6;
It is. In the above device, an alternating current voltage having a frequency near the natural frequency of the circular vibrating body (actually, the natural frequency of one of the vibrating bodies) is applied to each one of the vibrators of the circular vibrating body, and at the same time,
Each other oscillator of the circular oscillator has a π/2 phase shifter.
By applying an AC voltage with a phase shift of /2,
A progressive vibration wave is generated in each vibrating body symmetrically with respect to the sheet conveying surface. When a progressive vibration wave is generated in the vibrating body, each point on the surface opposite to the surface where the vibrator is provided performs a kind of elliptical motion, and each point on the opposite surface of the circular vibrating body moves toward the sheet conveyance. As a result of the elliptical movement symmetrical to the plane, the sheet is conveyed by frictional force.

FIG. 5 is a schematic diagram illustrating the principle of generation of sheet conveying force by such progressive vibration waves.

It is assumed that the sheet S is held between the vibrating bodies 1 and 2 with an appropriate pressing force, and that progressive vibration is generated in the vibrating bodies 1 and 2 as shown in the figure. At this time, when paying attention to a certain mass point on the surface of the circular vibrating bodies 1 and 2, the mass point generally moves in an elliptical orbit. Regarding the vibrating body 1, when the progressive vibration wave travels to the right as shown in the figure, the mass points on the vibrating body surface draw a clockwise elliptical locus. Here, since the phase of the voltage applied to the vibrator is controlled so that the phase difference between the progressive vibration waves generated in the vibrators 1 and 2 becomes 180° spatially, the progressive vibration waves of each vibrator has a symmetrical waveform with the sheet as the plane of symmetry, and the waves progress so that the convex portions toward the sheet always face each other. Furthermore, since the moving direction of the mass point in the white portion is opposite to the direction in which the vibrations of the vibrators 1 and 2 move, the sheet conveyance force is generated in the direction of the arrow in this case. On the other hand, the sheet conveying force acts in the same direction as the traveling direction in the concave parts of the sheet, but since the pressure is smaller than in the convex parts, the frictional force between the sheet and the vibrating body is also small, and therefore the sheet conveying force is also small. Therefore, the total sheet conveying force acts in the direction opposite to the traveling direction of the progressive vibration waves.

FIG. 6 shows another example of a sheet feeding device constructed based on the aforementioned sheet feeding principle, and this device is also proposed by the applicant. This sheet feeding device uses a pair of annular vibrating bodies 10 and 11 having a running track-shaped planar shape as shown in the figure as vibrating bodies, and the non-opposing surfaces of each annular vibrating body are Electrostrictive vibrators 12 and 13 such as piezoelectric elements are fixed. These electrostrictive vibrators 12 and 13 are each divided into two groups, and an alternating voltage that is 90° out of phase with the voltage applied to the other group is applied to one group. There is. When two types of AC voltages having different phases are separately applied to the two groups of electrostrictive vibrators 12 and 13, according to the above-mentioned theory, each annular vibrator 1o and 11 has a progressive tendency that advances along the circumferential direction. Bending vibration occurs, and the sheet S is moved by receiving a force from each annular vibrating body in a direction opposite to the direction in which the progressive bending vibration advances. A sheet feeding device that uses a running track-shaped annular vibrating body utilizes the progressive deflection that occurs in the straight section of the vibrating body as a sheet conveying force. The vibrating body is arranged parallel to the feeding direction. In this sheet feeding device, if the two linear portions of the annular vibrators 1o and 11 are in contact with the sheet Sll, the sheet S will simultaneously receive forces in opposite directions and will not advance. The vibrating body 1 as shown in
Only the linear portions 10a and 11 of 0 and 11 are in contact with the sheet S, and the other portions including the other linear portions tab and llb are so thin that they do not contact the sheet S.

In this device, when cyclical traveling wave vibration occurs in the annular vibrating bodies 10 and 11 in the direction of the arrow f1 shown in the figure, the sheet S moves in the direction of the arrow f2 in the opposite direction (in FIG. towards).

[Problems to be Solved by the Invention] In the conventional device described above, the sheet contact surface of each vibrating body is processed to have a mirror surface or a quasi-mirror surface.

However, if the sheet contact surface is a mirror surface or an extremely low roughness surface similar to that, (a) friction with the sheet is small, so a large conveying force cannot be obtained, and the conveying efficiency (energy efficiency) also decreases. (b) If the sheet has extremely low surface roughness, such as a resin film, an adsorption phenomenon may occur in which the sheet is attracted to the surface of the vibrating body, making it impossible to convey it. C) When stopping the seat, the friction between the vibrating body and the seat is small, so it may not be possible to stop it accurately at a predetermined position, or the force to keep the seat in a stopped state is weak, so there is a danger that the seat may move when not driven. There were problems such as

The present invention aims to solve the above problems and provide an improved sheet feeding device.

[Means for Solving the Problems] In the present invention, the above problems are solved by providing a film or layer of a flexible elastic material such as rubber on the sheet contacting surface of the vibrating body. Note that the thickness of this film or layer is desirably smaller than the amplitude of vibrations generated in the vibrating body.

[Embodiments] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of a sheet feeding device to which the present invention is applied.

In FIG. 1(a), 14 to 17 are vibrators made of piezoelectric elements, 18 and 19 are vibrating bodies whose surfaces in contact with the sheet S are covered with membranes 22 and 23 made of an elastic material such as rubber, and 2
o is an oscillator that applies a frequency voltage to the vibrators 14 to 17, and 21 is an energy absorption section.

The vibrators 14 and 15 are fixed to the vibrating body 18 with adhesive or the like. Similarly, the vibrators 16 and 17 are also fixed to the vibrating body 19 with adhesive or the like. Further, the vibrating bodies 18 and 19 are pressed against each other with an appropriate force. In this embodiment, since the vibrating bodies 18 and 19 are conductive bodies, they are connected to a ground circuit, and the oscillators 14 to 17 are connected to the ground circuit by the oscillator 20. to the frequency voltage (
By applying an alternating current electric field), the vibrating bodies 18 and 19
vibration occurs.

The vibrators 15 and 17 generate electricity as the vibrators 18 and 19 vibrate. The generated electrical energy is dissipated by an energy adsorption section 21 made of a resistor or the like. Therefore, the vibration becomes a traveling wave without being reflected. Vibrating body 18
When the bending vibration of and 19 becomes a traveling wave, 1 of the surface
If you pay attention to the point, its trajectory will draw an ellipse as described above. Therefore, the outside part of the bend always has a velocity component in the opposite direction to the traveling direction of the traveling wave, and since the sheet S is always in contact with the outside part of the bend, the velocity component is opposite to the traveling direction of the traveling wave. sent to. In FIG. 1, sheets S are fed from left to right.

In the device of this embodiment, the sheet contact surfaces of both the driving bodies 18 and 19 are made of membranes 22 and 23 made of an elastic and flexible material such as rubber.
Because the sheet S is covered with It is firmly gripped between moving objects and transported with greater transport force than conventional devices. Furthermore, since the sheet S does not slip against the vibrating body, the sheet gripping force when the sheet is stopped also increases. In addition, since the thickness of the membranes 22 and 23 is smaller than the amplitude of the bending vibration occurring in the vibrating bodies 18 and 19, even when the vibrating bodies vibrate and the 1] i22 and 23 elastically contract, the vibration is damped. do not have.

FIG. 3 shows another embodiment of the invention.

In this example, the vibrating body! 8 and! Teeth-shaped vibrating pieces 18a and 19a (vibrating protrusions) are formed on the surface of 9.
Membranes 22 and 23 made of an elastic flexible material are formed on the tip surfaces (that is, the surfaces that contact the sheet S) of the vibrating pieces 18a and 19a. Therefore, the sheet S is gripped with a large force in the same way as in the embodiment of FIG.

[Effects of the Invention] As explained above, the sheet feeding device of the present invention has the following effects:
A film or layer made of a flexible elastic material with a thickness smaller than the vibration amplitude is formed on the sheet contacting surface of the vibrating body, and the film or layer is brought into contact with the sheet, so that: (1) the sheet conveying force is increased; GD The sheet conveyance force is large, so it is possible to convey even sheets with extremely low coefficients of friction. OiD The sheet gripping force when stopping the sheet can be increased. As a result, the sheet does not move, and the stopping accuracy when stopping the feed can be improved.

[Brief explanation of drawings]

FIG. 1(a) is a schematic diagram showing a first embodiment of a sheet feeding device improved according to the present invention, and FIG.
) is an enlarged perspective view of a part of the device shown in FIG.
3 is a schematic diagram of a second embodiment of the sheet feeding device of the present invention, FIG. 4 is a perspective view of a prior art sheet feeding device proposed by the applicant, and FIG. 5 is the device of FIG. 4. 6 is a perspective view of another sheet feeding device proposed by the applicant, and FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG. 6. , is. 14-17... Vibrator 18.19... Vibrating body 20... Oscillator 22.23... (made of elastic material) ll! S... Sheet (b) Sheet (b) Sheet (b) Sheet (b)

Claims (1)

[Claims] 1. It has a vibrating body that is excited by an electrostrictive vibrator or the like to generate traveling wave vibration, and the vibrating body applies a propulsive force to a sheet that is pressed against the surface of the vibrating body. A sheet feeding device configured as described above, wherein the sheet contacting surface of the vibrating body is covered with a film or layer of a flexible elastic material such as rubber. 2. The sheet feeding device according to claim 1, wherein the thickness of the film or layer of the flexible elastic material is smaller than the maximum amplitude of traveling wave vibration generated in the vibrating body.