JPH0466437A - Paper feeding device - Google Patents

Abstract

PURPOSE:To make pressing force constant by measuring displacement according to abrasion of a retard roller with a strain gauge via a lever, and energizing a tension spring so as to cancel reduction of pressing force due to the abrasion based on the result thereof, in a paper feeding device of an image forming device. CONSTITUTION:When a retard roller 2 is abraded, for instance, by S in a radius, a lever 10 is turned in the arrow mark A direction by the abraded amount to reduce elongation of a tension spring 12. Therefore, pressing force N of a roller 11 pressing the retard roller 2 becomes small. This pressing force N is measured by a strain gauge 14, and sent to a control unit 21. The control unit 21, based on this signal, drives a motor 18, turns a cam 15 in clockwise direction via a pinion 18a and a gear 17, presses a perpendicular member 13a of a stay 13 in the rightward direction, returns elongation of the tension spring 12 to the original state, and keeps pressing force N for the retard roller 2 constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a paper feeding device that feeds sheets for image formation to an image forming apparatus, and specifically includes a retard roller that prevents double feeding of sheets. Regarding a paper feeding device.

(B) Prior Art A conventional paper feeding device having a retard roller is shown in FIG.

A is a stay fixed to the device, and a feed roller b having a driving means (not shown) is provided above the stay a. A retard roller C having a drive means (not shown) is provided,
Both the feed roller b and the retard roller C are designed to rotate clockwise.

Then, a shaft e is attached to a bracket d fixed to the stay a.
An L-shaped lever f is pivotally supported at its center, a roller g is pivotally supported at the tip of the horizontal part, and one end of a tension spring h is locked to the lower end of the vertical part.

The roller g or retard roller C is pressed upward with a pressing force N, and the other end of the tension spring h is applied to the lower right end of the stay a so as to bias the lever f counterclockwise. It is locked to.

In addition, the lever ratio between the horizontal part and the vertical part of lever f is I
22/Ω.

In the above configuration, when the sheet material P fed by the pick-up roller from the cassette (not shown) is one sheet, that is, only Pl, as shown in FIG. The frictional force F is almost the same as the sheet material P.

It scratches and damages the sheet material P.

Therefore, since the torque limit of the torque limiter (not shown) is smaller than the frictional force occurring between the sheet material PI and the roller C, the retard roller C rotates along with the feed roller via the sheet material P.

However, as shown in FIG. 5, if two or more sheet materials P are to be bitten, that is, the frictional force between the sheet materials Pl and P will be reduced by the feed roller b, the sheet material P1, and the retard roller. Since the friction force between C and sheet material P is smaller than the frictional force between sheet material P, feed roller b feeds sheet material P1, and retard roller C returns sheet material P2 to the cassette side.

As explained above, the torque limit of the torque limiter is smaller than the torque generated by the frictional force between the sheet material P and the rollers b and e, and the torque generated by the frictional force between the sheet materials p, p2. Is it necessary to set it larger than that?

To meet these conditions, set the tension spring h and idle torque of the torque limiter to correspond to changes in the surface friction coefficients of rollers b, c, and sheet material P, and determine the appropriate pressing force N of retard roller C. ing.

(c) Problems to be Solved by the Invention However, in the above conventional example, the feed roller b and the retard roller C rub against the sheet material P in order to prevent double feeding of the sheet material P, so they are considerably worn out. , due to a decrease in the coefficient of friction, the sheet material slips against the sheet material, resulting in paper feeding failures and double feeding. However, recently, even if it is worn out,
With the advent of materials that maintain the coefficient of friction on the roller surface, the above problems have been alleviated considerably, but as the wear and tear of rollers b and c increases, the above method of pressurizing retard roller C has the following problems. There are some drawbacks.

Generally, the retard roller C is worn more than the feed roller b, so the difference between the wear and tear of the feed roller b is S as shown in FIG. As a result, the pressing force N of the retard roller C against the feed roller b decreases from the initial setting value, so even if the friction coefficient of rollers b and c does not change, the paper feeding and conveying force decreases. Therefore, there is a drawback that paper feeding failure by the feed roller b is more likely to occur.

Furthermore, if the pressing force N is increased (stronger) in anticipation of a decrease in the pressing force N, the frictional force between the sheet materials P1 and P2 will increase, and if the torque setting value of the torque limiter is exceeded, the There is a problem in that double feeding is likely to occur. However, if the pressing force N is increased by changing the lever ratio, there are space constraints such as the length of the vertical piece of the lever f, and there is a problem in that the setting width of the appropriate pressing force becomes smaller.

Therefore, in the present invention, the other end of a spring locked to one end of a lever that urges the retard roller to be pressed is connected to a strain gauge set on a swingable support plate, and the swing support plate is connected to a cam. It is an object of the present invention to provide a sheet feeding device in which the pressing force of the retard roller is always kept constant by providing a control means for moving the retard roller and adjusting the drive of the cam based on a signal from the strain meter.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned circumstances, and for example, as shown in FIG. 1, the sheet material (P) storage container (
a pickup roller (20) that feeds the sheet material (P) from the pickup roller (20); and a pickup roller (20) that feeds the sheet material (P) from the image forming apparatus body (3).
One end is biased by a spring (12) and the other end separates and conveys the retard roller (2) and feed roller (1) to the retard roller (2) and the feed roller (1).
1), the L-shaped lever (10) is pivotally supported at the center so as to press against the spring (10);
A swing support plate (13) is provided with a strain gauge (14) connected to the swing support plate (12), and a cam (13) that drives the swing support plate (13) is provided.
15), and by the simultaneous movement of the cam (15), the swing support plate (13), the strain gauge (14), the spring (12), and the lever (
10), the pressing force (N) of the retard roller (2) against the feed roller (1) is adjusted.

The strain meter (14) also measures the retard roller (2).
The signal detecting the pressing force (N) of the cam (15
) is characterized in that it is provided with a control means (21) for controlling the drive of.

Further, at least one protrusion (16) is provided on the drive shaft (15a) that drives the cam (15), and a sensor (]8) that crosses the protrusion (16) is provided, and the protrusion is connected to the sensor (18). ) is characterized in that it includes a control means (21) for stopping the operation of the image forming apparatus main body (3) in response to a signal crossing the image forming apparatus main body (3).

(f) Based on the structure described above, the sheet material (P
) is fed by a pick-up roller (20), and the fed sheet material (P) is passed between the feed roller (1) and the feed roller (1) by a spring (12) via an L-shaped lever (10). ) is pressed by the retard roller (2)
The image forming apparatus is separated and transported to the image forming apparatus main body (3).

At this time, by adjusting the movement of the swinging support plate (13) with the cam (15), the force acting on the spring (12) is applied via the strain gauge (14) attached to the swinging support plate (13). The force is adjusted to press the retard roller (2) or the feed roller (1) via the L-shaped lever (10).

Further, the control means (21) receives a signal from the strain meter (14) that detects the pressing force of the retard roller 2, and controls the cam (15).
Adjust the drive.

Further, upon receiving a signal that the protrusion (16) provided on the shaft of the cam (15) crosses the sensor (18), the control means (21) stops the operation of the image forming apparatus main body (3).

Note that the symbols in parentheses are just examples and do not limit the configuration in any way.

(F) Examples Examples of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a feed roller, and the shaft 1a of this feed roller 1 is driven by a drive source (not shown) to rotate clockwise at a predetermined number of rotations. The feed roller 1 is made of a material such as rubber that has a large coefficient of friction.

Further, the retard roller 2 is fixed to a shaft 2a, and the retard roller 2 is fixed to a shaft 2a.
Bearing 2b etc. is attached to a. The bearing 2b is guided in the direction of the feed roller 1 by the long hole 5a of the bracket 5, and the bracket 5 is attached to a stay 4 fixed to the main body 3 of the image forming apparatus.

Further, a torque limiter 7 is attached to the shaft 2a via a coupling 6, and this torque limiter 7 is attached to the shaft 8.
It is driven by a drive source (not shown) via a drive source, and is rotated clockwise with a predetermined torque.

Also, a shaft 9 is supported by the stay 4, and this shaft 9 has an L
A letter-shaped lever 10 is pivotally supported. A roller 11 is pivotally supported at the end of the horizontal piece 10a of this lever 10, and
One end of the bow tension spring 12 is locked to the end of the vertical piece 10b.

The other end of the tension spring 12 is attached to a strain gauge 14 attached to the swing support plate 13.

This swing support plate 13 is swingably supported on the shaft 9 by a bracket 13a.

Further, a projection 16 is attached to the middle portion of the shaft 15a to which the cam 15 is attached, and a gear 17 is attached to the end portion of the shaft 15a.

The cam 15 is arranged so as to come into contact with a vertical piece 13b bent downward from the swing support plate 13, the protrusion 16 is arranged to cross the sensor 18, and the gear 17 is arranged to contact the vertical part 13b bent downward from the swing support plate 13.
The pinion 18a is engaged with the pinion 18a.

Then, the sheet material P fed from the cassette 19 by the pick-up roller 20 is held between the feed roller 1 and the retard roller 2, and is delivered to the main body 3 of the image forming apparatus 9.
Floors are being fed.

Further, the driver of the motor 18 , the sensor 18 , the strain gauge 14 , and the image forming apparatus main body 3 are connected to the control section 21 .

Next, the operation of this embodiment will be explained with reference to FIGS. 2 to 4.

The sheet material P stored in the cassette 19 is sent out by a pickup roller 20, and fed to the image forming apparatus main body 3 by a feed roller 1. If the sheet materials P are fed in duplicate, one sheet is fed by a retard roller 2. The sheet material P other than the mesh is sent back to the cassette 19 side. In addition, sheet material P
When only one sheet of sheet material P is fed by the feed roller, the retard roller 2 rotates along with the sheet material P.

At this time, both the feed roller 1 and the retard roller 2 are worn out, or the retard roller 2 is often worn out, so for example, if the retard roller 2 is worn out by a radius of S as shown in FIG. As shown by arrow A, the tension spring 12 is rotated counterclockwise, the extension of the tension spring 12 is reduced, and the pressing force N with which the roller 11 presses the retard roller 2 is reduced. This pressing force N is measured by a strain gauge 14,
Upon receiving the signal, the control unit 21 instructs the driver of the motor 18 to rotate the cam 15 clockwise via the pinion 18a, gear 17, and shaft 15a, and lift the stay 13 near the maximum lift a. The pressing force N of the retard roller 2 is kept constant by moving the vertical piece 13a to the right and returning the tension spring 12 to its original state.

When the protrusion 16 of the shaft 15a crosses the sensor 18, the control section 21 receives the signal emitted by the sensor 18.
or the copying operation of the image forming apparatus main body 3 is stopped and the rollers 1,
2 shows the replacement timing.

To do this, for example, when the top dead center a of the cam 15 comes into contact with the vertical piece 13a, a message such as "Roller Replacement Pa" is displayed and the roller l is replaced.

2, the periodic replacement period may be clearly indicated.

The flowchart in FIG. 4 shows the main part of the above operation, where FT indicates the required pressing force of the retard roller 2, and when FT is smaller than the pressing force detected by the strain gauge 14, the cam 15 is activated. When the cam 15 rotates counterclockwise, and vice versa, the cam 15 is controlled to rotate clockwise, and when the sensor 18 is turned on, the image forming apparatus main body 3 is controlled to stop. It shows that

The above is a control method in which the pressing force N of the retard roller 2 is kept constant, and if there is no decrease in the coefficient of friction between the rollers 1 and 2, a stable sheet feeding operation is always possible.

In addition, if the setting value of the pressing force of the retard roller 2 can be set manually using a key on the operation unit, the usage environment of the image forming apparatus can be adjusted.
Even a service person level can set the pressing force of the retard roller 2 corresponding to the type of paper used.

(g) As described in detail, according to the present invention, the movement of the swinging support plate is adjusted by the cam, and the acting force of the spring is measured through the strain gauge attached to the swinging support plate. The lever adjusts the pressure force with which the retard roller presses against the feed roller, so the cam can maintain a constant pressure force with which the retard roller presses the feed roller, enabling stable paper feeding. become.

In addition, a stable sheet feeding operation can be maintained at all times by automatically adjusting and maintaining the drive of the cam at a constant level by the control means that receives a signal from the detection of the pressing force of the strain gauge.

In addition, if the rotation limit of the cam is detected by a sensor and the control means that receives the symbol stops the operation of the image forming apparatus main body, the feed roller and the retard roller can be replaced in this state. The maintenance of the device can be completely performed and the maintenance of the device can be completed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG.
FIG. 4 is a side view showing the operation of the cam, FIG. 4 is a flowchart showing the operation of the strain gauge and sensor, and FIGS. 5 and 6 are side views showing the drawbacks of the conventional example.

Claims (1)

[Claims] 1. A pickup roller that feeds the sheet material from a sheet material storage container, and a retard roller and a feed roller that separate and convey the sheet material fed by the pickup roller to the main body of the image forming apparatus. , an L-shaped lever whose one end is biased by a spring and whose other end is pivoted at the center so as to press the retard roller against the feed roller, the lever being connected to the spring; A swinging support plate is provided with a strain gauge set therein, and a cam is provided for driving the swinging support plate, and the rotation of the cam causes the feed roller to move through the swinging support plate, the strain gauge, the spring, and the lever. A paper feeding device configured to adjust the pressing force of the retard roller against the retard roller. 2. The sheet feeding device according to claim 1, further comprising a control means for controlling the drive of the cam based on a signal detected by the strain meter to detect the pressing force of the retard roller. 3. At least one protrusion is provided on the drive shaft that drives the cam, and a sensor is provided that the protrusion crosses, and a control means that stops the operation of the image forming apparatus main body based on a signal that the protrusion crosses the sensor. Paper feeding device provided.