JPH0761644A - Paper sheet carrier - Google Patents

Abstract

PURPOSE:To prevent carriage abnormality such as paper sheet folding and paper sheet jaw by automatically detecting paper sheet thickness and regulating paper sheet pressure force according to it. CONSTITUTION:Movement of an actuator which contacts with the surface of paper sheet 100 carried by a paper carrier is detected by an angle sensor 16 so as to judge the thickness of the paper sheet. A controller 15 puts on/off a solenoid 17 according to output of the angle sensor 16. A movable part of the solenoid 17 is connected to an end part of a spring 18 pressing on a pressure roller 20 and tensile force of the spring is regulated by on/off action of the solenoid 17. Namely, when the thickness of the paper sheet 100 is thick, the tensile force becomes large and when the paper sheet 100 is thin, the tensile force becomes small, so that the paper sheet 100 is carried by appropriate force according to paper sheet thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device, and more particularly to a sheet conveying device which can change the pressing pressure of a conveying roller according to the thickness of a sheet to be conveyed.

[0002]

2. Description of the Related Art An example of a sheet conveying device used in an electrophotographic apparatus, a laser printer, etc. will be described with reference to FIG. In the figure, a sheet conveyed by a drive roller (not shown) from the previous step is guided by the upper guide plate 22 and the lower guide plate 23 and guided to the conveying device.

The lower guide plate 23 is provided with a sheet conveying roller 21, and the upper guide plate 22 is provided with a pressure roller 20 paired with the sheet conveying roller 21. The sheet conveying roller 21 is rotatably supported by a bearing (not shown), and a motor (not shown) is connected as a drive source.
The pressure roller 20 is also supported by a bearing in the same manner. For example, a gap of at least one sheet is provided between the bearing and the shaft 20a of the pressure roller 20, and the pressure roller 20 extends vertically in the range of the gap. The shaft 20a is movable,
The spring 18 presses the paper transport roller 21 side.

Therefore, the sheet guided to the conveying device is sandwiched between the pressure roller 20 and the sheet conveying roller 21 by the force of the spring 18, and is conveyed to the next step.
The shafts 20a of the paper transport roller 21 and the pressure roller 20 have a paper transport direction D so that the paper is directed toward the aligning guide 19 for aligning the side edges of the paper.
Is attached at a predetermined angle with respect to.

By the way, the pressing force of the pressure roller 20 is uniquely determined by the constant of the spring 18, although the thickness of the conveyed sheet is not always constant. As a result, for example, if the pressure is weak despite the fact that the paper is thick, the paper cannot be surely aligned with the aligning guide 19, and conversely, if the pressure is too strong despite the fact that the paper is thin, The sheet may be pressed too strongly by the aligning guide 19 and may cause a sheet break.

Further, it is sufficient if the paper is simply discharged to the paper tray without the next step. For example, as shown in FIG. 9, a guide plate 31 having a curvature is provided in order to miniaturize the apparatus. In a layout in which it is arranged immediately after the conveying device and the horizontal conveying direction is changed to the vertical direction, if the pressing force is not appropriate, a paper jam or a paper break will occur at the guide plate 31. Sometimes.

In order to solve the above-mentioned problems, it is possible to adjust the pressing force according to the thickness of the paper. JP-A-63-267620, JP-A-1-24342, JP-A-2-120352, and JP-A-3-182.
Japanese Patent Laid-Open No. 445 or the like proposes a device capable of switching the pressing force according to the thickness of the sheet and the type of sheet.

[0008]

The above-mentioned conventional device has the following problems. No conventional device has a sensor for detecting the paper thickness, and the adjustment is performed manually.

Therefore, the operator had to know the thickness of the paper in advance, and the pressing force had to be manually set according to the thickness of the paper. Such a trouble is caused by preparing a sheet having a thickness different from those of other sheet feeding sections in an apparatus having a plurality of sheet feeding sections, and transporting these sheets in a mixed manner. It was particularly busy when.

For example, a document whose front cover is printed on thick paper and a text is printed on thin paper may be printed in multiple copies, or a paper already printed on one side may be reused as a so-called backing paper. In this way, problems such as paper jams may occur when sheets of different thickness are continuously conveyed, or when a layout that greatly changes the conveyance direction is used to reduce the size of the device. was there.

Despite these problems,
In the past, there was no device configured to automatically determine the thickness of the paper and adjust the pressure applied to the paper based on the result, and even attempted automation.

In view of the above situation, the present invention provides a sheet conveying device having high conveying performance, which can detect the sheet thickness and automatically adjust the pressing force in order to solve the above problems. The purpose is to do.

[0013]

SUMMARY OF THE INVENTION To solve the above problems and to achieve the object, the present invention provides a pressure adjusting means for a pressure roller, a sheet thickness detecting sensor provided on a sheet conveying path,
It is characterized in that it is provided with processing means for outputting a signal corresponding to the output signal of the detection sensor to the pressurization adjusting means as a pressing force instruction signal.

[0014]

Since the signal determined on the basis of the output of the detection sensor is supplied as an instruction signal to the pressure adjusting means of the pressure roller, the pressure force corresponding to the sheet thickness is applied to the pressure roller.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a laser beam printer including a sheet conveying device according to an embodiment of the present invention.

In FIG. 1, the printer has two sheet feeding devices, that is, a first sheet feeding tray 1 and a second sheet feeding tray 2.
And have. The first paper feed tray 1 has a thick paper 3 and a second paper
Thin paper 4 is loaded in the paper feed tray 2 of FIG. These papers 3 and 4 are respectively fed by the first paper feed roller 5a and the second paper feed roller 5b, and are conveyed to a step for print processing by a plurality of sets of first stage conveyance rollers 6. The first paper feed roller 5a and the second paper feed roller 5b are selectively driven by a command from a computer (not shown), and thick paper and thin paper are fed at arbitrary timings.

The printing section P has a developing machine 7, a laser beam generator 8, a charge corotron 9, a photosensitive drum 10, a transfer corotron 11, and a cleaner 12. Since these configurations are well known, detailed description will be omitted.

The toner image transferred to the thick paper 3 and the thin paper 4 (hereinafter referred to as the paper 100 when both are collectively referred to) in the printing section P has a heat fixing roller 13 and a heat fixing pressure roller 14 on the paper 100. It is fixed on the paper 100 when passing through the space.

The sheet 100 on which printing has been completed is the sheet 1
00 is sent to the paper transporting device C according to the present invention for transporting 00 to the paper discharge tray 24. The sheet conveying device C includes an upper guide plate 22, a lower guide plate 23, and an aligning guide 1.
9, transport roller 21, pressure roller 20, pressure spring 1
8, solenoid 17 as pressure adjusting means, paper 100
Sensor 16 for detecting the thickness of the sensor 16 and a controller 15 for giving a command to the solenoid 17 based on the output signal of the sensor 16.

An actuator 16b is rotatably provided on the shaft 16a of the sensor 16. Actuator 16b
The mounting position of the sensor 16 is adjusted so that the output signal of the sensor 16 corresponds to a linear range described later with the tip of the sensor in contact with the surface of the paper 100. The sensor 1
The operation principle of 6 will be described later.

The actuator 16b is normally held in contact with the surface of the lower guide plate 23 by the action of gravity. Then, when the sheet 100 is conveyed and the sheet 100 comes into contact with the tip of the actuator 16b, the actuator 16b is pushed up by the sheet 100, and is maintained in the pushed state until the sheet 100 passes.

The actuator 16b is preferably formed entirely of a lightweight member such as resin or light alloy, but the paper 10
In order to stabilize the contact state with 0, the weight may be increased to some extent, or a spring or the like may be used for biasing. Further, the lower surface of the actuator 16b, that is, the contact surface with the paper 100 is formed in an arc shape so that the conveyance of the paper 100 is not hindered.

Next, with reference to an enlarged view of FIG. 2, a main part of the sheet conveying device C will be described. In the figure, bearings 32 and 33 are fixed to the upper guide plate 22 by appropriate fixing means such as bolts, and the shaft 20a of the pressure roller 20 is rotatably supported by the bearings 32 and 33. Shaft 20a and bearing 3
The size is set so that a gap G slightly larger than at least one sheet 100 is formed between the sheets 2 and 33.

Between the one bearing 32 and the pressure roller 20, a pressure spring 18 for pressing the shaft 20a toward the sheet conveying roller 21 is provided. The pressurizing spring 18 is a tension coil spring, one end of which is hooked on a hooking portion 22a formed on the upper guide plate 22, and the other end of which is connected to a plunger 34 of a solenoid 17 fixed to the upper guide plate 22. To be done.

A sheet conveying roller 21 is axially supported by bearings 35 and 36 on the lower guide plate 23, and a pulley 37 for transmitting a driving force from a motor (not shown) is fixed to a shaft 21a of the sheet conveying roller 21. It

Next, the operating principle of an angle sensor suitable as the sensor 16 will be described with reference to FIG. Figure 3 (a)
3 is a connection diagram for explaining the principle of the angle sensor, FIG.
FIG. 3B is an equivalent circuit diagram thereof, and FIG. 3C is a diagram showing the relationship between the output signal of the angle sensor and the rotation angle of the shaft of the sensor.

3 (a) and 3 (b), a magnet M is fixed to the end surface of the shaft 16a of the angle sensor in a positional relationship shown in the drawing, and further, the magnet M is concentrically arranged with respect to the shaft 16a. On the other hand, the magnetoresistive element R is provided so as to face the shaft 16a with a constant air gap in the extending direction of the shaft 16a. The magnetoresistive element R is a magnetoelectric conversion element made of a semiconductor material whose resistance value increases in proportion to the strength of the magnetic field acting on it. With the terminal portion t at the center of the magnetoresistive element R as a boundary, one side forms a resistance section R1 and the other side forms a resistance section R2. A power supply 38 is connected to both ends of the magnetoresistive element R, and the voltage between the ground (GND) and the central terminal portion t becomes the sensor output Vout.

When the shaft 16a rotates in the direction of arrow 39, the magnet M also rotates together with it, and the relative positions of the magnet M and the resistance portions R1 and R2 change. As a result, the axis 16
That is, the resistance values of the resistance portion R1 and the resistance portion R2 change with the displacement of the magnet M, and the sensor output Vout according to the relative position of the magnet M and the resistance portion R1 and the resistance portion R2 is obtained.

The sensor output Vout changes as shown in FIG. 3C according to the rotation angle of the shaft 16a. For example, in the positional relationship between the magnet M and the magnetoresistive element R shown in FIG. Since the resistance value of the resistance part R1 is low and the resistance value of the resistance part R2 is high, the sensor output Vout becomes the maximum value.

Since the sensor output Vout has a linear range A as shown in FIG. 3 (c), when the angle sensor is used, each component is arranged to use the linear range A. It is better to adjust the positional relationship of.

FIG. 4 shows a hardware structure of a control device for processing the output signal of the sensor 16 to adjust the pressing force. As shown in the figure, it is desirable that the control device 15 is composed of a microcomputer. In the figure, the output signal of the sensor 16 is converted into a digital signal (A / D conversion) in the processing unit 30 for convenience of computer processing, and then C
It is input to the PU 27. The ROM 28 stores system data, programs of the microcomputer, and the like, and the RAM 29 stores data obtained by the processing, reference values, and the like.

Next, a description will be given of main functions of the control device in the paper transporting device having the above hardware configuration. In the block diagram of FIG. 5, the output signal of the sensor 16 is the processing unit 3
0, the processing unit 30 A / D-converts the input signal and outputs it to the on / off instruction unit 40. The on / off instructing unit 40 compares the signal supplied from the processing unit 30 with a threshold value for distinguishing thick paper and thin paper. In that case, an off signal is output. The ON signal and the OFF signal are output to the driver device 41. Driver device 42
When the ON signal is supplied, supplies a predetermined current to the solenoid 17 to operate it. When the OFF signal is supplied, the supply of current to the solenoid 17 is stopped.

Since the pressing spring 18 is connected to the plunger 34 of the solenoid 17, when the solenoid 17 operates and the plunger 34 is retracted, the pressing spring 1
8 is pulled and the pressing force on the pressure roller 20 increases. On the contrary, when the current supply to the solenoid 17 is stopped, the plunger 34 protrudes, the pressing spring 18 loosens, and the pressing force on the pressing roller 20 decreases. In other words, the pressing force is strengthened when the sensor 16 detects thick paper, and weakened when the thin paper is detected.

Next, the operation of the on / off instruction section 40 will be described with reference to a flow chart. In FIG.
In step S1, the output signal Vout of the sensor 16 is read. In step S2, it is determined whether the read signal, that is, the voltage Vout is larger than the threshold value. This threshold is a value for distinguishing between thick paper and thin paper.
If the output voltage Vout is larger than the threshold value, the thick paper 3
When it is determined that the current is detected, the process proceeds to step S3, and the ON signal for supplying the predetermined current to the solenoid 17 is output to the driver device 41. If the output voltage Vout is smaller than the threshold value, it is determined that the thin paper 4 has been detected, and the process proceeds to step S4 to output an OFF signal to the driver device 41 to stop the current supply to the solenoid 17.

Next, an example in which a linear actuator is used instead of the solenoid will be described. In FIG.
The same reference numerals as in the above indicate the same or equivalent portions. In FIG.
Spring adjustment data corresponding to the input signal is stored in the table 42, and the spring adjustment data is output to the driver device 41 using the digital signal supplied from the processing unit 30 as a key. The driver device 41 supplies a current according to the supplied spring adjustment data to the linear actuator 43.
Supply to. The linear actuator 43 is, for example, a voice coil type actuator, and is configured to obtain a stroke according to the current supplied to the coil.

Like the solenoid 17 shown in FIG. 2, the linear actuator 43 has a reciprocating plunger and linearly moves with a stroke proportional to the supplied current. Therefore, depending on the magnitude of the signal detected by the sensor 16, that is, the magnitude of the paper thickness, the linear actuator 4
Since the amount of the plunger pulled into 3 changes, if one end of the pressure spring 18 is connected to this plunger, the pressure roller 2 can be continuously changed according to the thickness of the sheet 100.
The applied pressure of 0 can be changed.

The means for outputting the spring adjusting data is not limited to the table 42, but may be a calculating means for calculating the pressurizing data according to the input signal according to a predetermined calculation formula.

Next, a modified example of the pressure adjusting means will be described.
In the example shown in FIG. 7, the case where the tension spring is used as the pressing spring has been described, but in the example shown below, the compression spring is arranged in the bearing 32.

In FIG. 7, the bearing 32 is provided with a recess 45 for accommodating the compression spring 44 from above. Washers 46 and 47 are arranged above and below the compression spring 44. The washer 46 is in contact with the shaft 20a from above, and one end of a rocking plate 48 is in contact with the upper surface of the washer 47. Swing plate 48
The other end is connected to the plunger 34 and swings around the shaft 49 following the movement of the plunger 34.

That is, when the plunger 34 is pulled in the direction of the arrow 50, the oscillating plate 48 swings in the direction of the arrow 51 and the compression spring 44 is compressed, and the force for pressing the pressure roller 20 in the direction 21 of the sheet conveying roller. Will increase. On the other hand, when the plunger 34 is extended in the direction opposite to the arrow 50, the swing plate 48 is returned in the direction opposite to the arrow 51, and the compression spring 44 is returned.
Expands and pushes the pressure roller 20 into the paper transport roller direction 21.
The force pressing against is reduced.

[0041]

As is apparent from the above description, according to the present invention, the thickness of the sheet conveyed on the conveying path can be automatically detected by the sheet thickness detecting sensor. Then, the pressing force of the pressure roller applied by the elastic member can be adjusted based on the detection result.

Therefore, even if thick paper or thin paper is mixed, the paper can be conveyed with an appropriate force according to each paper, and the conveyance abnormality is unlikely to occur. As a result, it is convenient for computer-controlled printing in which thick paper and thin paper are alternately used for printing according to a predetermined program, and for printing using backing paper having a non-uniform thickness.

Further, since it is possible to eliminate the conveyance abnormality even in a copying machine or a printer in which the conveyance path is set so that the conveyance direction greatly changes for the miniaturization, the miniaturization of these is facilitated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a laser beam printer including a sheet conveying device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of a sheet conveying device showing an embodiment of the present invention.

FIG. 3 is a diagram showing a principle diagram of an angle sensor and a relationship between an output and a rotation angle.

FIG. 4 is a block diagram showing a hardware configuration of a control device of the paper transport device.

FIG. 5 is a block diagram showing the main functions of the control device.

FIG. 6 is a block diagram showing the main functions of the control device.

FIG. 7 is an enlarged view of a main part of a sheet conveying device showing a modified example of the invention.

FIG. 8 is a flowchart showing the processing operation of the detection signal of the sensor.

FIG. 9 is a perspective view showing a conventional sheet conveying device.

[Explanation of symbols]

16 ... Sensor, 16b ... Actuator, 17 ... Solenoid, 18 ... Spring, 19 ... Aligning guide, 20 ... Pressure roller, 21 ... Conveying roller, 22 ...
Upper guide plate, 23 ... Lower guide plate

Claims (3)

[Claims] 1. A conveyance roller for conveying a sheet, a pressure roller paired with the conveyance roller, an elastic member for pressing the pressure roller toward the conveyance roller, and an external force applied in advance to the elastic member. The pressure adjusting means for adjusting the pressure of the pressure roller, the sheet thickness detecting sensor provided on the sheet conveying path, and the signal corresponding to the output signal of the detecting sensor is used as the pressure instruction signal. And a processing unit that outputs the sheet to the sheet conveying unit. 2. The paper thickness detection sensor includes an actuator that comes into contact with the surface of the paper, a shaft that rotatably supports the actuator, a magnet fixed to the shaft, and a magnet that is arranged to face the magnet. A resistance element, the angle sensor being configured to output as a detection signal a signal according to the resistance value of the magnetoresistive element that changes depending on the relative positional relationship between the magnetoresistive element and the magnet. The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. 3. An aligning guide is arranged along a side end of a sheet conveying path, wherein the conveying roller and the pressure roller have respective supporting shafts for directing the sheet toward the aligning guide. The sheet conveying device according to claim 1, wherein the sheet conveying device is inclined with respect to the sheet conveying direction.