JPH0326629A - Sheet feeder - Google Patents

Abstract

PURPOSE:To achieve a high precision sheet feed by providing a control means to control to output a frequency voltage to a power source means to make a frequency voltage to be applied to vibrators zero or make a sheet transfer impossible when a sheet transfer quantity information from a sheet transfer quantity detecting means reaches a predetermined transfer quantity. CONSTITUTION:When a sheet transfer quantity detecting means 8 detects that a sheet 13 reaches a predetermined transfer quantity, a controller CNT outputs a frequency voltage to a power source means to make a frequency voltage to be applied to vibrators 1-4 zero or make a sheet transfer impossible. The transfer of the sheet 13 by resilient bodies 5, 6 is stopped by this. At this time, a large braking force is given to the sheet 13 by the friction force of the resilient bodies 5, 6, thereby the sheet 13 is fed at a high precision.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a sheet feeding device installed in a computer, a copying machine, a facsimile machine, a word processor, a tie writer, and other various machines equipped with a sheet feeding mechanism, The present invention relates to a sheet feeding device that utilizes vibrational waves.

[Prior Art] Conventionally, as disclosed in Japanese Patent Laid-Open No. 59-177243, a device of this type is configured to feed the sheet by applying a traveling wave to an elastic body that clamps the sheet. It was. Here, we will discuss the third principle of sheet conveyance in the above proposal.
This will be explained using figures.

The seat 13 is supported by the elastic bodies 11 and 12 with appropriate pressure. Each of the elastic bodies 11 and 12 has a progressive bending vibration (travelling wave), and the phase difference between these traveling waves is spatially set to 1800 degrees, so each elastic body The bending vibrations 11 and 12 proceed so that the respective convex portions always face each other on the seat 13 side. At this time, if we pay attention to a point on the surface of the elastic body 11, 12, for example, where there is a convex portion, the point generally moves in an elliptical orbit. Regarding the elastic body 11 in FIG. 3, if the traveling wave moves to the right, the mass point will draw a clockwise elliptical locus as shown in the figure. Therefore, the direction of movement of the mass point of the convex portion is the elastic body 11.1
2. In both cases, the direction is opposite to the direction of vibration, and this acts as a force to transport the sheet l3. On the other hand, in the concave portion, a sheet transporting force is generated in the same direction as the traveling direction, but the pressure is smaller than that in the convex portion, so the frictional force between the sheet 13 and the elastic body 11, 12 is small, and the sheet transporting force is also small. Therefore, the total sheet transport force acts in the opposite direction to the direction of the bending vibration described above. [Problems to be Solved by the Invention] By the way, such a sheet feeding device does not require a transmission mechanism such as a gear, as compared to a sheet feeding method in which driving force from a motor is transmitted to a paper feeding roller via a transmission mechanism such as a gear. Although it is possible to achieve highly accurate sheet feeding without loss, there is a risk that the sheet feeding accuracy may decrease due to changes in the environmental atmosphere such as temperature and humidity, or uneven sheet thickness. If you stop the machine and print, it may cause uneven printing. In addition, in order to maintain high sheet feeding accuracy, for example, a comparison section that detects the difference between the target value and the current value, an operation section that converts the difference signal into a drive signal, and a There is a proposal using a sheet movement amount detection means composed of a so-called closed-loop control system consisting of a compensation section, but this constitutes a so-called position servo control system, and in order to achieve high accuracy, movement amount detection is required. The disadvantage was that the resolution needed to be increased, making the configuration complex and expensive. The object of the present invention is to take advantage of the advantages of a drive system that uses progressive vibration waves, which have excellent braking performance when the drive is stopped due to friction, and to enable highly accurate sheet feeding without configuring a complicated position servo control system. The purpose is to provide a feeding device. [Means for Solving the Problems] The gist of the present invention to achieve the object is to provide an elastic body to which a vibrator is fixed, with a conveyed object on the surface opposite to the surface to which the vibrator is fixed. When a certain sheet is pressed, a frequency voltage from a power supply means is applied to the vibrator to form a progressive vibration wave in the elastic body, and a transporting force is applied to the sheet by the vibration surface on which the traveling wave is formed. The apparatus includes a conveyance means for conveying a sheet, a sheet conveyance amount detection means for detecting the conveyance amount of the sheet, and a control means for controlling the power supply means based on sheet conveyance amount information from the sheet conveyance amount detection means. The control means outputs a frequency voltage applied to the vibrator to zero or a frequency voltage that disables sheet transport to the power supply means when the sheet transport amount information from the sheet transport amount detection means reaches a predetermined transport amount. There is a sheet feeding device characterized by controlling the sheet feeding device.

[Function] In the sheet feeding device configured as described above, when the sheet transport amount detection means detects that the sheet has reached a predetermined movement amount,
The sheet transport by the elastic body is stopped, and at this time, a large braking force is applied to the sheet due to the frictional force of the elastic body, making it possible to feed the sheet with high precision. [Embodiments] The present invention will be explained in detail below based on illustrated embodiments. FIG. 1 shows an embodiment of the present invention.
3.4 is a vibrator made of a piezoelectric element, 5.6 is an elastic body, and 7
is an oscillator, 1o is an energy absorber, and CNT is a controller. The vibrator 1.2 is fixed to the elastic body 5 with adhesive or the like. Similarly, the vibrator 3.4 is fixed to the elastic body 6 with adhesive or the like. Furthermore, the elastic bodies 5 and 6 are held down with an appropriate force. In this embodiment, the elastic bodies 5 and 6 are connected to a ground circuit as conductors, and vibration is generated in the elastic bodies 5 and 6 by applying a frequency voltage (alternating current electric field) to the vibrator 1 by an oscillator 7. do. The vibrators 2 and 4 generate electricity as the elastic bodies 5 and 6 vibrate. The generated electrical energy is dissipated by a certain energy absorbing section 10 through a resistor or the like.

Therefore, the vibration becomes a traveling wave without being reflected.

When the bending vibration of the elastic body 5.6 becomes a traveling wave, if we focus on one point on its surface, its locus depicts an ellipse. 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 13 always comes into contact with the outside part of the bend, it is different from the traveling direction of the traveling wave. In reverse feeding, in FIG. 1, sheets are fed from left to right.

8 is a rotary encoder, 11 is a roller attached to the rotating shaft of the rotary encoder, and 9 is a roller. The roller 9 has the function of pressing the sheet 13 against the roller 11 and preventing slippage between the roller 11 and the sheet 13. As the seat 13 moves, the encoder 8 sends a pulse signal to the controller CNT. The controller CNT is composed of a microcomputer and operates according to the flowchart shown in FIG. 2, and is designed to count the number of pulse signals from the encoder 8. Since the number of encoder pulse signals for a predetermined movement amount is set in advance in the controller from the outer diameter of the roller 11 of the encoder 8 and the number of pulses per rotation angle of the encoder,
The output of the oscillator 7 is stopped when a predetermined number of pulses are received. When the output of the oscillator 7 stops, the traveling wave stops and the sheet transport force disappears. Since the elastic bodies 5 and 6 are pressed against the seat 13 with a corresponding force, when the movement is stopped, a large frictional force acts between the seat and the elastic body, and this causes a force on the seat that is about to move due to inertia. Acts as a braking force.

As mentioned above, this braking force is large, so the seat stops in a short time and over a short distance, so it is positioned with high precision.
Further, even after stopping, the above-mentioned frictional force acts as a holding force, so that the stopped position is easily maintained without moving. In addition, the number of pulses per rotation angle of the encoder only needs to satisfy the resolution of 1 pulse per predetermined movement amount of the sheet, so the encoder resolution corresponding to the required resolution for sheet positioning as in a normal position servo system is not necessary,
An encoder with coarse encoder resolution, eg, one pulse per revolution, may be used.

In the above embodiment, the frequency voltage applied to the vibrator when stopping the sheet is set to zero, but the vibration amplitude of the elastic body is reduced to lower the voltage to a minute voltage that makes it impossible to transport the sheet. You can. [Effects of the Invention] As described above, according to the present invention, when the information from the sheet movement amount detection means reaches a predetermined amount of movement of the sheet, a minute voltage is generated that stops the traveling wave or disables sheet transport. By using this method, high-precision sheet feeding can be achieved at low cost with simple planning.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a sheet feeding device according to the present invention, and FIG. 2 is a flowchart explaining its operation.
FIG. 3 is a diagram illustrating the sheet conveyance principle. 1 to 4... Vibrator 5.6... Elastic body 7... Oscillator 8... Rotary encoder 9... Roller 11... ◆◆ Roller 13...
・Seat CNT...Controller and 4 other people Figure 2

Claims (1)

[Claims] 1. A sheet, which is a conveyed object, is pressed against the surface opposite to the surface to which the vibrator is fixed in an elastic body to which the vibrator is fixed, and a frequency voltage from a power supply means is applied to the vibrator. A conveying means for conveying the sheet by forming a progressive vibration wave on an elastic body and applying a conveying force to the sheet by a vibrating surface on which the traveling wave is formed, and a sheet conveyance amount detection means for detecting the conveyance amount of the sheet. and a control means for controlling the power supply means based on the sheet transport amount information from the sheet transport amount detection means, and the control means is configured to detect when the sheet transport amount information from the sheet transport amount detection means reaches a predetermined transport amount. Then, the sheet feeding device is characterized in that the power supply means is controlled to output a frequency voltage applied to the vibrator to zero or a frequency voltage that disables sheet transport.