KR20180082820A - Sheet supplying apparatus and image forming apparatus having the smae - Google Patents

Abstract

A sheet supplying apparatus according to the present invention comprises: a sheet laminating unit for laminating at least one sheet; a paper supplying roller installed at one side of the sheet laminating unit and transferring the laminated sheet to the sheet laminating unit; a feed preventing roller opposed to the paper supplying roller and preventing feeding of the sheet supplied from the sheet laminating unit; a magnetic torque limiter installed in a coaxial direction with the feed preventing roller; and a hole sensor installed at one side of the magnetic torque limiter, and detecting rotation of the magnetic torque limiter.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sheet supplying apparatus and an image forming apparatus including the sheet supplying apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sheet feeding apparatus, and more particularly, to a sheet feeding apparatus and an image forming apparatus including the sheet feeding apparatus.

Generally, an image forming apparatus is provided with a sheet feeding apparatus for feeding sheets one by one to an image forming unit. When two or more sheets stacked on the sheet feeding device are fed to the image forming unit, an appropriate image can not be formed on the sheet. Therefore, the sheet feeding apparatus is provided with the medium-feeding detecting apparatus capable of detecting the sheet feeding.

The conveyance detecting device can be divided into a simple type and a high-precision type.

An example of the simple type is disclosed in Japanese Patent Application Laid-Open No. 2000-168983 (title of the invention, sheet feeding device and image forming apparatus).

There is a problem in that the structure of the conveyance detecting device disclosed in the patent is complicated and it is necessary to individually adjust the precision of the parts, the intervals of the parts, and the sensor positions. Further, when the sheet to be used is changed, there is a problem that it is necessary to adjust it again according to the sheet. In addition, there is also a problem that the detection accuracy is low due to vibration when the sheet rushes into the retard roller.

The high-precision figure is to detect whether two or more sheets are fed by installing an ultrasonic sensor. When the ultrasonic sensor is used, the reliability is high, but the price is high. Therefore, it is difficult to apply a high-precision figure to an image forming apparatus for home use or office where cost competitiveness is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a sheet feeding apparatus having a low-cost, compact and highly reliable medium conveyance detecting function and an image forming apparatus including the same.

The present invention also relates to a sheet feeding apparatus and a sheet feeding apparatus including the sheet feeding apparatus, capable of returning a sheet to which sheet feeding has occurred to a sheet stacking unit when sheet feeding occurs.

A sheet feeding apparatus according to one aspect of the present invention includes: a sheet stacking unit for stacking at least one sheet; A sheet feeding roller installed at one side of the sheet stacking unit for feeding the sheet stacked on the sheet stacking unit; A sheet conveying roller facing the sheet feeding roller and preventing a sheet conveyed from the sheet stacking unit from being conveyed; A magnetic torque limiter provided coaxially with the conveyance prevention roller; And a Hall sensor installed at one side of the magnetic torque limiter and detecting rotation of the magnetic torque limiter.

At this time, the magnetic torque limiter may include: a plurality of permanent magnets provided circumferentially on a rotation axis of the anti-rotation roller; A housing provided to surround the plurality of permanent magnets; And a magnetic member provided on the inner surface of the housing to face the plurality of permanent magnets, wherein the plurality of permanent magnets and the magnetic member are spaced apart from each other by a predetermined distance.

The length of the magnetic member may be smaller than the length of the plurality of permanent magnets, and the Hall sensor may be installed at a position corresponding to a portion of the plurality of permanent magnets that do not overlap with the magnetic member.

Further, the magnetic member may include a plurality of slits provided in the circumferential direction, and the hall sensor may be installed at a position corresponding to the plurality of slits of the magnetic member.

The sheet supply device according to an embodiment of the present invention may include a control unit configured to determine whether a sheet is conveyed by using a signal transmitted from the hall sensor; And a sheet conveyance unit that conveys the conveyed sheet to the sheet stacking unit when conveyance occurs in the conveyance prevention roller.

Wherein the sheet conveying unit includes: a drive clutch for selectively interrupting a rotational force transmitted to the sheet feeding roller; And a drive source for rotating the conveyance prevention roller. When the control unit determines that sheet conveyance has occurred from the signal of the hall sensor, the control unit operates the drive clutch to interrupt the rotational force transmitted to the paper feed roller, The sheet conveying roller can be rotated to convey the sheet positioned between the sheet feeding roller and the sheet conveying preventing roller to the sheet stacking unit.

The Hall sensor includes a first hall sensor for outputting an A-phase pulse signal and a second Hall sensor for outputting a B-phase pulse signal later than the A-phase signal. After the order of the pulse signals is reversed, it is possible to judge that the conveyance has occurred when the reference time has elapsed.

Also, the controller may determine that the interval between the A-phase pulse signal and the B-phase pulse signal is shortened and that the short-time A-phase pulse signal and the B-phase pulse signal are output when a predetermined time has elapsed .

In addition, the controller may determine that a lag occurs when a predetermined time elapses after the output of the A-phase pulse signal and the B-phase pulse signal is stopped.

A sheet feeding apparatus according to another aspect of the present invention includes: a sheet stacking unit for stacking at least one sheet; A sheet feeding roller provided on one side of the sheet stacking unit for feeding the sheet fed from the sheet stacking unit; A sheet conveying roller facing the sheet feeding roller and preventing a sheet conveyed from the sheet stacking unit from being conveyed; A rotary encoder installed on one side of the conveyance prevention roller coaxially with the conveyance prevention roller; And a sensor installed at one side of the rotary encoder and detecting rotation of the rotary encoder.

At this time, the sensor includes two optical sensors, and the two optical sensors may be installed adjacent to each other in the circumferential direction of the rotary encoder.

In addition, the two optical sensors may be installed at intervals of 90 degrees with respect to the rotation center of the rotary encoder.

Further, the two photosensors may include a first photosensor installed on a horizontal line passing through the center of the rotary encoder; And a second photosensor mounted on a vertical line passing through the center of the rotary encoder.

When the difference between the A-phase pulse signal output from the first photosensor and the B-phase pulse signal output from the second photosensor occurs, the control unit may determine that sheet transfer has occurred.

When the difference between the voltage of the signal output from the first photosensor and the voltage of the signal output from the second photosensor is generated, the controller may determine that the sheet is conveyed.

1 schematically shows an example of a sheet feeding apparatus according to an embodiment of the present invention;
Fig. 2 is a view showing a sheet-feed preventing roller and a sheet feeding roller of the sheet feeding apparatus of Fig. 1; Fig.
3 is a sectional view showing a structure of a magnetic torque limiter of a sheet feeding apparatus according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view of the magnetic torque limiter of FIG. 3 taken along line I-I;
5 is a sectional view showing a structure of another example of a magnetic torque limiter of a sheet feeding apparatus according to an embodiment of the present invention;
FIG. 6 is a cross-sectional view of the magnetic torque limiter of FIG. 4 taken along line II-II;
FIG. 7A is a view showing a case where the sheet feeding apparatus according to the embodiment of the present invention feeds the sheet normally; FIG.
FIG. 7B shows signals output from the first Hall sensor and the second Hall sensor in the case of FIG. 7A; FIG.
8A is a view showing a case where two sheets are supplied to the anti-spoiling roller of the sheet supply device according to the embodiment of the present invention;
FIG. 8B is a diagram illustrating signals output from the first Hall sensor and the second Hall sensor in the case of FIG. 8A; FIG.
FIG. 9A is a view showing a case where three or more sheets are supplied to the sheet conveyance prevention roller according to the embodiment of the present invention; FIG.
FIG. 9B shows signals output from the first Hall sensor and the second Hall sensor in the case of FIG. 9A; FIG.
10 is a plan view schematically showing a sheet feeding apparatus according to an embodiment of the present invention having a sheet return function;
11 is a side view showing a case in which the sheet feeding apparatus of Fig. 10 does not operate;
12 is a side view showing a case where the sheet feeding apparatus of Fig. 10 feeds sheets normally; Fig.
13 is a side view showing the case where the sheet feeding apparatus of Fig. 10 returns the sheet to the retry position; Fig.
14 is a functional block diagram of a sheet feeding apparatus according to an embodiment of the present invention;
15 is a view schematically showing a sheet feeding apparatus according to another embodiment of the present invention;
Fig. 16 is a plan view showing a sheet conveyance prevention roller of the sheet supply device of Fig. 15; Fig.
Fig. 17A is a view showing a case where the sheet feeding device of Fig. 15 feeds the sheet normally; Fig.
FIG. 17B is a diagram showing signals output from the first photosensor and the second photosensor in the case of FIG. 17A; FIG.
Fig. 18A is a view showing a case where two sheets are fed to the anti-misfeed roller in the case where the anti-misprinting roller of the sheet supply device of Fig. 15 is an active roller;
FIG. 18B shows signals output from the first photosensor and the second photosensor in the case of FIG. 18A; FIG.
Fig. 19A is a view showing a case where three or more sheets are fed to the anti-scattering rollers when the anti-scattering rollers of the sheet feeding device of Fig. 15 is an active roller;
FIG. 19B shows signals output from the first photosensor and the second photosensor in the case of FIG. 19A; FIG.
20A is a view showing a case where two sheets are fed to the sheet-conveying prevention roller of the sheet feeding device including the semi-active conveyance prevention roller;
FIG. 20B shows signals output from the first photosensor and the second photosensor in the case of FIG. 20A; FIG.
21A is a view showing a case where three or more sheets are fed to the sheet-conveying prevention roller of the sheet feeding device including the semi-active conveyance prevention roller;
FIG. 21B is a diagram showing signals output from the first photosensor and the second photosensor in the case of FIG. 21A; FIG.
22 is a schematic view of a sheet feeding apparatus according to another embodiment of the present invention;
23 is a plan view showing the sheet-conveying preventing roller of the sheet feeding device of Fig. 22;
Fig. 24A is a view showing a case where the sheet feeding apparatus of Fig. 22 feeds the sheet normally; Fig.
FIG. 24B is a diagram showing signals output from the first photosensor and the second photosensor in the case of FIG. 24A; FIG.
25A is a view showing a case where two sheets are supplied to the anti-misfeeding roller when the anti-misprinting roller of the sheet supply device of Fig. 22 is an active roller;
25B is a diagram showing signals output from the first photosensor and the second photosensor in the case of FIG. 25A; FIG.
Fig. 26A is a view showing a case where three or more sheets are fed to the anti-scattering rollers when the anti-scattering rollers of the sheet feeding device of Fig. 22 is an active roller;
FIG. 26B is a diagram showing signals output from the first photosensor and the second photosensor in the case of FIG. 26A; FIG.
26C is a view showing a case where the pulse of a signal output from the first photosensor and the second photosensor is converted into a voltage in the case of FIG. 26A; FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a sheet supplying apparatus and an image forming apparatus including the same according to the present invention will be described in detail with reference to the accompanying drawings.

It is to be understood that the embodiments described below are provided for illustrative purposes only, and that the present invention may be embodied with various modifications and alterations of the embodiments described herein. In the following description, well-known functions or components are not described in detail to avoid obscuring the subject matter of the present invention. In addition, the attached drawings are not drawn to scale in order to facilitate understanding of the invention, but the dimensions of some of the components may be exaggerated.

FIG. 1 is a view schematically showing an example of a sheet feeding apparatus according to an embodiment of the present invention, and FIG. 2 is a view showing a sheet feeding roller and a sheet feeding roller of the sheet feeding apparatus of FIG.

1 and 2, a sheet feeding apparatus 1 according to an embodiment of the present invention may include a sheet stacking unit 10, a sheet feeding roller 20,

The sheet stacking unit 10 stacks at least one sheet S and picks up the stacked sheets S one by one and feeds them toward the sheet feeding roller 20. [ The sheet stacking unit 10 may include a sheet cassette 11 and a pickup roller 13 provided above the sheet cassette 11. The sheet cassette 11 is configured to accommodate a predetermined number of sheets S and the pickup roller 13 feeds the sheet S positioned at the top of the sheets S stacked on the sheet cassette 11, (20).

The sheet feeding roller 20 is provided on one side of the sheet stacking unit 10 and moves the sheet S stacked on the sheet stacking unit 10 to the conveying roller 201 side. Specifically, the sheet feeding roller 20 is formed so that the sheet S picked up by the pickup roller 13 in the sheet stacking unit 10 can be moved toward the conveying roller. The conveying roller 201 moves the sheet S fed by the sheet feeding roller 20 to the image forming unit 203. 1 shows a case where the sheet feeding apparatus 1 according to an embodiment of the present invention is installed in an image forming apparatus.

The paper feed roller 20 is rotatably installed by the driving source 100. As an example, the driving source 100 may use a driving motor. Since the structure in which the driving motor 100 rotates the paper feed roller 20 is general, the illustration and description are omitted.

The conveyance prevention roller 30 is provided so as to face the sheet feeding roller 20 and to prevent the sheet S fed from the sheet stacking unit 10 from being conveyed. Specifically, the conveyance prevention roller 30 is provided to be in contact with the sheet feeding roller 20 at a constant pressure. When the sheet S is conveyed in the sheet stacking unit 10, So that the sheet S is conveyed to the conveying roller 201 side. The carry preventing roller 30 can be elastically supported by the carry preventing roller holder 33 so that the carry preventing roller 30 can contact the paper supplying roller 20 at a constant pressure. The anti-slip roller holder 33 is elastically supported by an elastic member 35 provided on the frame 3.

When two or more sheets S are pulled in between the conveyance prevention roller 30 and the sheet feeding roller 20, the sheet S is conveyed by the sheet S between the sheet conveying prevention roller 30 and the sheet feeding roller 20 In order to prevent them from passing through. Hereinafter, prevention of the sheet S from passing between the sheet feeding roller 20 and the sheet conveyance prevention roller 30 is referred to as sheet conveyance prevention.

A magnetic torque limiter (40) is installed on the conveyance prevention roller (30) to prevent the conveyance. Specifically, the magnetic torque limiter 40 is provided on the rotary shaft 31 of the anti-rotation roller 30 and has a constant critical torque value. Therefore, when the sheet conveying frictional force generated between the sheet conveying preventing roller 30 and the sheet feeding roller 20 is larger than the threshold torque value, the sheet conveying preventing roller 30 rotates in a direction synchronized with the rotation of the sheet feeding roller 20, that is, in the sheet conveying direction. However, if the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the paper feed roller 20 is smaller than the critical torque value, the paper feed roller 20 rotates in a direction opposite to the rotation of the paper feed roller 20 or remains stationary. Therefore, when a single sheet S is pulled in between the conveyance prevention roller 30 and the sheet feeding roller 20, the sheet conveyance frictional force between the sheet conveyance prevention roller 30 and the sheet S becomes equal to or smaller than the threshold value of the magnetic torque limiter 40 The sheet S is conveyed normally because the conveyance preventing roller 30 rotates in the sheet conveying direction. However, when two or more sheets S are drawn between the conveyance prevention roller 30 and the sheet feeding roller 20, the conveyance of the sheet S is cut off.

Hereinafter, the structure of the magnetic torque limiter 40 provided on one side of the anti-scattering roller 30 will be described with reference to Figs. 3 and 4. Fig.

FIG. 3 is a sectional view showing the structure of a magnetic torque limiter of the sheet feeding apparatus according to the embodiment of the present invention, and FIG. 4 is a sectional view of the magnetic torque limiter of FIG. 3 taken along the line I-I.

3 and 4, the magnetic torque limiter 40 includes a plurality of permanent magnets 41 provided in the circumferential direction on the rotation axis 31 of the anti-rotation rollers 30. As shown in FIG. The plurality of permanent magnets 41 are formed in a rod shape and are provided on the circumferential surface of the rotary shaft 31 so that the N pole and the S pole alternate in the circumferential direction of the rotary shaft 31. In the present embodiment, a plurality of permanent magnets 41 are provided on the rotary shaft 31 of the anti-rotation roller 30. Alternatively, a plurality of permanent magnets 41 may be provided on the hollow boss, May be formed on the rotation axis 31 of the conveyance prevention roller 30. [

The magnetic torque limiter 40 may include a housing 43 enclosing a plurality of permanent magnets 41 provided on the rotary shaft 31. A housing shaft 47 is provided on one side of the housing 43 and an opening 44 through which the rotation shaft 31 of the anti-rotation roller 30 can be inserted is provided on the other side of the housing 43. A magnetic member 45 is provided on the inner surface of the housing 43 so as to face a plurality of permanent magnets 41 so that a magnetic force is generated between the plurality of permanent magnets 41 and the magnetic member 45. The magnetic member 45 is formed into a hollow cylindrical shape. The magnetic member 45 and the plurality of permanent magnets 41 are spaced apart from each other in the radial direction. The housing 43 is formed of a nonmagnetic material such as plastic. The length L1 of the magnetic member 45 is formed to be shorter than the length L2 of the housing 43. [ 3, the portions 41a of the plurality of permanent magnets 41 directly face the inner surface of the housing 43 without facing the magnetic member 45. Therefore, The magnetic force of the plurality of permanent magnets 41 is radiated to the outside of the housing 43 through the portion 43a of the housing 43 where the magnetic member 45 is not provided. The magnetic force of the plurality of permanent magnets 41 is not radiated to the outside in the portion of the housing 43 provided with the magnetic member 45.

The housing shaft 47 is rotatably supported by a rotation support member (not shown) such as a bearing. The housing shaft 47 may be configured to receive a rotational force from the driving source 100 or to receive no rotational force.

When the housing shaft 47 receives the rotational force from the driving source 100, the load preventing roller 30 is rotatable by the driving source 100. At this time, the housing shaft 47 is connected to the driving shaft of the driving source 100. The driving shaft of the housing shaft 47 and the driving source 100 can be connected using a coupling such as a universal joint. When the conveyance preventing roller 30 is configured to be rotatable by the separate driving source 100 as described above, this may be referred to as an active conveyance preventing roller. As another example, the housing shaft 47 may be provided so as to support the rotation of the conveyance prevention roller 30 without receiving power from the driving source 100. [ As described above, when the housing shaft 47 is not connected to the driving source 100, the conveyance prevention roller 30 can be rotated only by the rotation of the sheet feeding roller 20. [ This can be referred to as a semi-active conveyance prevention roller.

A sensor 50 can be installed on the outer side of the housing 43 to detect the magnetic force of a plurality of permanent magnets 41 radiated to the outside of the housing 43. As the sensor 50, a hall sensor capable of detecting magnetism can be used. The hall sensor 50 has a portion 43a of the outer circumferential surface of the housing 43 on which the magnetic member 45 is not provided, that is, a portion 41a of a plurality of permanent magnets 41 which do not overlap with the magnetic member 45, And is disposed outside the housing 43 so as to face a portion 43a of the housing 43 facing the housing 43. Therefore, as shown in FIG. 4, the hall sensor 50 is installed outside the magnetic torque limiter 40 in the radial direction of the magnetic torque limiter 40. Further, the hall sensor 50 is provided on a separate bracket 55 so as not to interfere with the magnetic torque limiter 40. Therefore, when the magnetic torque limiter 40 rotates, the hall sensor 50 does not interfere with the magnetic torque limiter 40, but detects the magnetic force emitted from the plurality of permanent magnets 41 of the magnetic torque limiter 40 can do.

The hall sensor 50 may include two hall sensors 51 and 52 installed in the circumferential direction of the magnetic torque limiter 40 so as to detect the direction of rotation of the magnetic torque limiter 40. [ For example, the first hall sensor 51 is disposed on the horizontal line H passing the rotation center C of the magnetic torque limiter 40, the second hall sensor 52 is disposed on the horizontal line H passing the rotation center C of the magnetic torque limiter 40, And may be spaced apart from the first Hall sensor 51 by a predetermined angle in the circumferential direction. If the first hall sensor 51 and the second hall sensor 52 are installed in the circumferential direction of the magnetic torque limiter 40 as described above, the magnetic torque limiter 40, that is, the rotation of the plurality of permanent magnets 41, The direction of rotation, and the displacement. Since the plurality of permanent magnets 41 are provided integrally with the conveyance preventing roller 30, the rotation of the conveyance preventing roller 30, the rotational direction, and the displacement are detected through the two hall sensors 51 and 52 .

5 and 6, another example of the magnetic torque limiter that can be used in the sheet feeding apparatus according to the embodiment of the present invention will be described.

5 is a cross-sectional view showing a structure of another example of a magnetic torque limiter of a sheet feeding apparatus according to an embodiment of the present invention, and FIG. 6 is a cross-sectional view of the magnetic torque limiter of FIG. 4 taken along line II-II.

5 and 6, the magnetic torque limiter 40 may include a plurality of permanent magnets 41, a housing 43, and a magnetic member 45 '.

The plurality of permanent magnets 41 are provided in the circumferential direction on the rotary shaft 31 of the anti-rotation roller 30. The plurality of permanent magnets 41 of the magnetic torque limiter 40 according to the embodiment shown in Figs. (41), detailed description thereof will be omitted.

The housing 43 is provided so as to surround a plurality of permanent magnets 41 provided on the rotary shaft 31 and is identical to the housing 43 of the magnetic torque limiter 40 according to the embodiment shown in Figs. A detailed description thereof will be omitted.

The magnetic member 45 'is provided on the inner surface of the housing 43 and is formed to have substantially the same length as the plurality of permanent magnets 41. A plurality of slits 46 are formed in the magnetic member 45 'in the circumferential direction. The magnetic force generated in the plurality of permanent magnets 41 is radiated to the outside of the housing 43 through the plurality of slits 46. Therefore, the hall sensor 50 is installed at a position where the plurality of slits 46 can face the outside of the housing 43 through the side surface of the housing 43. That is, the hall sensor 50 is installed outside the housing 43 so as to face the portion 43b of the housing 43 facing the plurality of slits 46. [ Therefore, when two hole sensors 51 and 52 are provided in the circumferential direction on the outer side of the magnetic torque limiter 40, that is, on the outer side of the housing 43, the hole sensors 51 and 52 are provided with a plurality of slits 46 It is possible to detect the magnetic force of the plurality of permanent magnets 41 radiated through the permanent magnets 41. [ Therefore, the magnetic torque limiter 40 and the hall sensor 50 can constitute a conveyance detecting unit capable of detecting whether or not the conveyance of the sheet S has occurred in the conveyance preventing roller 30. [

The sheet feeding apparatus 1 according to an embodiment of the present invention may include a control section 9 (see Fig. 14). The control unit 9 can determine whether the sheet conveyance prevention roller 30 of the sheet feeding apparatus 1 has generated the sheet conveyance by using the signals inputted from the hall sensors 51 and 52. [ It is possible to stop the driving source for rotating the pick-up roller 13 and the sheet feeding roller 20 of the sheet stacking unit 10 and form a control unit to inform the outside of the occurrence of the sheet feeding. When the sheet feeding apparatus 1 is installed in the image forming apparatus, the control unit 9 may be formed as a part of a control unit that controls the operation of the image forming apparatus.

Hereinafter, the operation of the sheet feeding apparatus according to one embodiment of the present invention will be described with reference to Figs. 7A to 9B.

First, a case in which the sheet feeding apparatus normally feeds one sheet will be described with reference to Figs. 7A and 7B.

FIG. 7A is a view showing a case where a sheet feeding device according to an embodiment of the present invention feeds a sheet in a normal state, FIG. 7B is a diagram showing a signal outputted from a first hall sensor and a second hall sensor in the case of FIG. FIG.

Referring to FIG. 7A, a sheet S is picked up by the pickup roller 13 and is drawn between the feeding roller 20 and the anti-slip roller 30. In this case, since the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the sheet S is larger than the critical torque value of the magnetic torque limiter 40, the conveyance prevention roller 30 is rotated by the sheet feed roller 20 . 7A, when the sheet feeding roller 20 rotates clockwise, the sheet S preventing roller 30 rotates in a counterclockwise direction due to a frictional force with the sheet, To be transported in the transport direction (arrow A direction).

At this time, the two hall sensors 51 and 52 provided on one side of the magnetic torque limiter 40 output pulse signals in the order of A phase and B phase as shown in Fig. 7B. For example, when the first hall sensor 51 outputs the A-phase pulse signal, the second hall sensor 52 outputs the B-phase pulse signal delayed by t times the A-phase pulse signal. When the A-phase signal and the B-phase signal are output from the first and second hall sensors 51 and 52 as shown in FIG. 7B, the controller 9 determines that the sheet S is normally supplied.

Next, a case where the sheet stacking unit 10 feeds two sheets S will be described with reference to Figs. 8A and 8B.

8A is a view showing a case where two sheets are fed to the anti-spoiling roller of the sheet feeding apparatus according to the embodiment of the present invention, and FIG. 8B is a diagram showing the case where the output from the first Hall sensor and the output from the second Hall sensor Fig.

8A, two sheets S are picked up by the pickup roller 13 and are drawn between the feeding roller 20 and the anti-slip roller 30. In this case, since the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the sheet S is smaller than the critical torque value of the magnetic torque limiter 40, the conveyance prevention roller 30 is rotated by the sheet feed roller 20 And is rotated by the driving source 100 connected to the conveyance prevention roller 30. [ 8A, when the sheet feeding roller 20 rotates in the clockwise direction, the conveyance preventing roller 30 is rotated clockwise by the driving source 100, (11). Therefore, when sheet conveyance occurs, the conveyance prevention roller 30 rotates in the opposite direction with respect to the direction in which the sheet S is normally conveyed.

At this time, the order of the pulse signals outputted from the two Hall sensors 51 and 52 provided on one side of the magnetic torque limiter 40 changes. For example, as shown in Fig. 8B, during the forward rotation, the pulse signals outputted in the order of A-phase and B-phase in the first and second hall sensors 51 and 52 are generated by the sheet- When the roller 30 rotates in the reverse direction, the output of the pulse signal changes in the order of the B phase and the A phase. Specifically, when the conveyance occurs, the second hall sensor 52 outputs the B-phase pulse signal, and the first hall sensor 51 outputs the A-phase pulse signal delayed by the time t from the B-phase pulse signal. When a predetermined period of time (T1 msec) elapses after the order of the A-phase signal and the B-phase signal is changed, the controller 9 stops the sheet feeding roller 20 and the sheet conveying prevention roller 30, Can be informed.

Finally, the case in which the sheet stacking unit 10 supplies three or more sheets S will be described with reference to Figs. 9A and 9B.

FIG. 9A is a view showing a case where three or more sheets are supplied to the anti-spoiling roller of the sheet feeding apparatus according to the embodiment of the present invention, FIG. Fig.

9A, a large amount of sheet S, for example, three or more sheets S is picked up by the pickup roller 13 and is drawn between the feeding roller 20 and the anti-slip roller 30. In this case, the frictional force applied to the conveyance prevention roller 30 by the large amount of sheets S inserted between the paper feed roller 20 and the conveyance prevention roller 30 is larger than the critical torque value of the magnetic torque limiter 40 The conveyance prevention roller 30 rotates in conjunction with the sheet feed roller 20. [ 9A, when the sheet feeding roller 20 rotates in the clockwise direction, the sheet conveying prevention roller 30 is moved in the sheet conveying direction (the direction of the arrow A) with a large amount of frictional force with the sheet S, That is, in the counterclockwise direction. At this time, since a large amount of sheets S are inserted between the sheet feeding roller 20 and the sheet conveying preventing roller 30, the amount of downward displacement (arrow B), which is the distance that the sheet conveying preventing roller 30 moves downward, increases. The lower displacement of the conveyance prevention roller 30 can be detected by the two hall sensors 51 and 52.

At this time, the two hall sensors 51 and 52 provided on one side of the magnetic torque limiter 40 output pulse signals in the order of A phase and B phase as shown in Fig. 9B. However, the interval between the A-phase pulse and the B-phase pulse becomes shorter than in the case of normal rotation. For example, when the conveyance prevention roller 30 rotates in the forward direction, when the first hall sensor 51 outputs the A-phase pulse signal, the second hall sensor 52 outputs B Phase pulse signal. At this time, the interval between the A-phase pulse signal and the B-phase pulse signal is T. When a large amount of sheets S are inserted between the conveyance prevention roller 30 and the sheet feeding roller 20 as shown in Fig. 9B, the A phase output from the first and second hall sensors 51, The order of the pulse signal and the B-phase pulse signal is the same, but the interval between the A-phase pulse signal and the B-phase pulse signal is shortened to T2 (msec). The controller 9 stops the feeding roller 20 and the anti-rotation roller 30 when a predetermined period (T3 msec) elapses after detecting that the pulse interval between the A-phase signal and the B- The occurrence of sheet conveyance can be informed to the outside.

Hereinafter, when the control unit 9 recognizes that the conveyance of the sheet S has occurred due to the conveyance prevention roller 30, the sheet S is returned to the sheet stacking unit 10, The case will be described with reference to Figs. 10 to 14. Fig.

10 is a plan view schematically showing a sheet feeding apparatus according to an embodiment of the present invention having a sheet return function. 11 is a side view showing the case where the sheet feeding apparatus of Fig. 10 does not operate. Fig. 12 is a side view showing the case where the sheet feeding apparatus of Fig. 10 normally feeds sheets, and Fig. 13 is a side view showing the case where the sheet feeding apparatus of Fig. 10 returns the sheet to the retrying position. 14 is a functional block diagram of the sheet feeding apparatus of Fig.

10 and 11, a sheet feeding apparatus 1 according to an embodiment of the present invention may include a sheet cassette 11 and a pickup roller 13. [ The pick-up roller 13 is provided on the upper side of the sheet cassette 11, picks up one sheet stacked on the sheet cassette 11 and feeds it to the feeding roller 20 side. The pickup roller 13 is provided on a pickup roller shaft 13a which is rotatably installed in the paper feed roller holder 21. [ A pickup roller gear 13b is provided coaxially on the pickup roller shaft 13a at one side of the pickup roller 13. [ Therefore, when the pickup roller gear 13b rotates, the pickup roller 13 rotates.

A paper feeding roller 20 is provided at one side of the pickup roller 13, that is, downstream of the sheet conveying direction. The paper feed roller 20 is provided on a paper feed roller shaft 20a which is rotatably mounted on a paper feed roller holder 21. [ A paper feeding roller gear 20b is coaxially installed in the paper feeding roller shaft 20a at one side of the paper feeding roller 20. [ At this time, the pickup roller shaft 13a and the paper feeding roller shaft 20a are provided parallel to each other, and the pickup roller gear 13b and the paper feeding roller gear 20b are spaced apart from each other. At one side of the paper feed roller holder 21, there is provided an idle gear 15 which is engaged with the pick-up roller gear 13b and the paper feed roller gear 20b. The idle gear 15 is rotatably mounted on the idle gear shaft 15a provided in the paper feed roller holder 21. [ Therefore, when the paper feeding roller gear 20b rotates, the pickup roller gear 13b rotates through the idle gear 15. [ Therefore, when the sheet feeding roller 20 rotates, the pickup roller 13 also rotates together.

A paper feed pulley 23 is provided at one end of the paper feed roller shaft 20a and at one end opposite to the side where the paper feed roller 20 is installed. A drive clutch 27 may be provided between the paper feed pulley 23 and the paper feed roller shaft 20a. The drive clutch 27 selectively blocks the rotation of the paper feed pulley 23 from being transmitted to the paper feed roller shaft 20a. For example, when the drive clutch 27 is turned on, the rotation of the paper feed pulley 23 is transmitted to the paper feed roller shaft 20a. When the drive clutch 27 is off, The rotation of the paper feeding roller 23 can be prevented from being transmitted to the paper feeding roller shaft 20a. Therefore, when the drive clutch 27 is turned off, the paper feed roller 20 does not rotate even if the paper feed pulley 23 rotates. The ON / OFF of the drive clutch 27 can be controlled by the control unit 9. [

The paper feed pulley 23 receives rotational force from the first drive motor 101 through the paper feed belt 24. [ For example, the motor shaft 101a of the first drive motor 101 may be provided with a feed drive pulley 25, and the feed drive pulley 25 and the feed pulley 23 may be connected by a feed belt 24 . Then, when the motor shaft 101a of the first drive motor 101 rotates, the paper feed drive pulley 25 rotates. The rotation of the paper feed drive pulley 25 is transmitted to the paper feed pulley 23 via the paper feed belt 24, so that the paper feed pulley 23 rotates.

A pickup roller spring 120 is provided at one side of the paper feed roller holder 21 to apply a force to pull the paper feed roller holder 21 in the upward direction. One end of the pickup roller spring 120 is fixed to a frame (not shown) where the sheet feeding device is installed, and the other end is fixed to one side of the paper feed roller holder 21. At this time, the other end of the pickup roller spring 120 is fixed to the opposite side of the pickup roller 13 about the paper feeding roller shaft 20a. Thus, the pickup roller spring 120 causes the pickup roller 13 to move downward.

On the lower side of the sheet feeding roller 20, a sheet conveying preventive roller 30 is rotatably installed. A magnetic torque limiter (40) is provided on the rotating shaft (31) of the anti-scattering roller (30). A load preventing pulley 48 is provided on the housing shaft 47 of the magnetic torque limiter 40. Therefore, when the carry preventing pulley 48 rotates, the magnetic torque limiter 40 rotates and the carry preventing roller 30 rotates.

The conveyance prevention roller 30 is rotatably installed in the conveyance prevention roller holder 33. The carry preventing roller holder 33 is installed to receive an elastic force in the upward direction by the elastic member 35. Therefore, the conveyance preventing roller 33 is kept in contact with the sheet feeding roller 20 at a constant pressure by the elastic member 35. [

A first intermediate pulley 131 is rotatably mounted on one side of the anti-rotation roller holder 33. Specifically, the first intermediate pulley 131 is provided coaxially with the intermediate shaft 130, which is rotatably installed on one side of the anti-rotation roller holder 33. The first intermediate pulley 131 is connected to the anti-spoiling pulley 48 through the anti-spoiling belt 135. Therefore, when the first intermediate pulley 131 rotates, the anti-rotation preventing pulley 48 is rotated by the anti-backing belt 135. When the conveyance prevention pulley 48 rotates, the conveyance prevention roller 30 rotates through the magnetic torque limiter 40.

At the other end of the intermediate shaft 130, a second intermediate pulley 132 is installed coaxially. Therefore, when the second intermediate pulley 132 rotates, the intermediate shaft 130 rotates, and thereby the first intermediate pulley 131 rotates. The second intermediate pulley 132 is rotatably received by the first drive motor 101 via the intermediary belt 136. For example, on the motor shaft 101a of the first drive motor 101, the anti-slip drive pulley 133 may be provided. The anti-dropping drive pulley 133 is connected to the second intermediate pulley 132 via the intermediate belt 136. Therefore, when the anti-scattering drive pulley 133 rotates, the intermediary belt 136 rotates the second intermediate pulley 132. Prevention drive pulley 133 is installed on the motor shaft 101a of the first drive motor 101 coaxially with the paper feed drive pulley 25 described above. Therefore, when the motor shaft 101a of the first drive motor 101 rotates, the feed drive pulley 25 and the anti-slip drive pulley 133 rotate integrally. Therefore, the first drive motor 101 can rotate the sheet feeding roller 20 and the sheet conveyance prevention roller 30.

The anti-scattering roller release cam 140 may be provided on one side of the anti-scattering roller holder 33. One end of the anti-scattering roller releasing cam 140 is fixed to the release cam shaft 141 and the other end is provided to be in contact with the projecting portion 33a of the anti-scattering roller holder 33. Therefore, when the anti-scattering roller releasing cam 140 rotates clockwise, the protrusion 33a of the anti-scattering roller holder 33 can be turned upward. When the projecting portion 33a is pivoted upward, the anti-rotation roller holder 33 rotates clockwise about the intermediate shaft 130, so that the anti-rotation roller 30 is moved away from the paper feeding roller 20. [ When the conveyance prevention roller releasing cam 140 rotates in the opposite direction, the force applied to the projecting portion 33a of the conveyance prevention roller holder 33 is removed, so that the conveyance prevention roller holder 33 is urged by the elastic member 35 So that the conveyance prevention roller 30 is brought close to the paper feed roller 20.

A release cam pulley 142 is provided on the opposite side of the one end of the release cam shaft 141, that is, where the spill prevention roller release cam 140 is installed. When the release cam pulley 142 rotates, the release cam shaft 141 rotates, thereby causing the anti-scattering roller release cam 140 to rotate.

The release cam pulley 142 is configured to be able to receive rotational force from the second drive motor 102. That is, the release cam drive pulley 144 is coaxially installed on the motor shaft 102a of the second drive motor 102, and the release cam drive pulley 144 is connected to the release cam pulley 142). Therefore, when the motor shaft 102a of the second drive motor 102 rotates, the release cam drive pulley 144 rotates, whereby the release cam belt 143 rotates. Then, the release cam pulley 142 is rotated by the release cam belt 143.

A pickup roller lifting cam 150 may be provided on one side of the paper feed roller holder 21. One end of the pickup roller lifting cam 150 is fixed to the lifting cam shaft 151 and the other end is set in contact with the protruding portion 21a of the paper feeding roller holder 21. [ Therefore, when the pickup roller up cam 150 rotates clockwise, the protruding portion 21a of the paper feed roller holder 21 can be pivoted downward. When the projecting portion 21a of the paper feed roller holder 21 is pivoted downward, the paper feed roller holder 21 rotates counterclockwise about the paper feed roller shaft 20a, Away from the stacked sheets. When the pickup roller up cam 150 rotates in the opposite direction, the force applied to the protruding portion 21a of the paper feed roller holder 21 is removed, so that the paper feed roller holder 21 is moved upward by the paper feed roller spring 120 The power of. Therefore, the feed roller holder 21 rotates clockwise, and the pickup roller 13 comes into contact with the sheet.

An elevating cam pulley 152 is provided on one side of the pick-up roller up-cam 150 coaxially with the up-cam shaft 151. When the up cam pulley 152 rotates, the up cam shaft 151 rotates, and thereby the pickup roller up cam 150 rotates.

The lift cam pulley 152 is configured to receive the rotational force from the second drive motor 102. That is, the motor shaft 102a of the second driving motor 102 is provided with a rising cam driving pulley 154 coaxially and the rising cam driving pulley 154 is connected to the rising cam pulley 154 152, respectively. Therefore, when the motor shaft 102a of the second drive motor 102 rotates, the up cam drive pulley 154 rotates, and thereby the up cam belt 153 rotates. Then, the lifting cam pulley 152 is rotated by the lifting cam belt 153. The lift cam drive pulley 154 is installed on the motor shaft 102a of the second drive motor 102 coaxially with the release cam drive pulley 144 described above. Therefore, when the motor shaft 102a of the second drive motor 102 rotates, the upward cam drive pulley 154 and the release cam drive pulley 144 rotate integrally. Therefore, the second drive motor 102 can simultaneously rotate the anti-scattering roller release cam 140 and the pickup roller up cam 150.

Hereinafter, the operation of the sheet feeding apparatus having the sheet conveying function will be described with reference to FIGS. 10 to 14 attached hereto.

The positions of the pickup roller 13, the feed roller 20, and the conveyance prevention roller 30 when the sheet feeding apparatus 1 does not operate are shown in Fig.

More specifically, the pickup roller lifting cam 150 is spaced apart from the protruding portion 21a of the paper feed roller holder 21, so that the paper feed roller holder 21 is rotated by the paper feed roller spring 120 to feed the paper feed roller shaft 20a So that the pickup roller 13 comes into contact with the sheet S in the clockwise direction.

Since the conveyance prevention roller releasing cam 140 pushes the projecting portion 33a of the conveyance prevention roller holder 33 upwardly, the conveyance prevention roller holder 33 rotates clockwise around the intermediate shaft 130 do. Therefore, the conveyance prevention roller 30 is spaced apart from the sheet feeding roller 20. When the conveyance prevention roller 30 and the paper feed roller 20 are separated from each other before the sheet feeding apparatus 1 stops operating, the deformation that may occur when the paper misfeed roller 30 and the paper feed roller 20 come in contact with each other for a long time Can be prevented.

In this state, when the control section 9 receives the sheet feeding instruction, the control section 9 controls the first driving motor 101 and the second driving motor 102 to change the sheet feeding apparatus 1 to the state And the sheet S is conveyed.

Specifically, the control section 9 rotates the second drive motor 102 in one direction so that the anti-scattering roller releasing cam 140 is positioned in a horizontal state. For example, in FIG. 11, the motor shaft 102a of the second driving motor 102 may be rotated clockwise so that the anti-scattering roller releasing cam 140 is positioned in a horizontal state. The elastic member 35 provided at the lower portion of the anti-rotation roller holder 33 is positioned above the anti-rotation roller holder 33 at the upper side So that the conveyance preventing roller 30 comes into contact with the sheet feeding roller 20. [

When the motor shaft 102a of the second drive motor 102 rotates clockwise, the pickup roller up cam 150 also rotates clockwise. Therefore, when the anti-scattering roller release cam 140 is positioned in the horizontal state, the pickup roller up cam 150 is also placed in the horizontal state. At this time, since the pickup roller up cam 150 does not apply a force to the protruding portion 21a of the paper feed roller holder 21, the pickup roller 13 maintains contact with the sheet S.

The control unit 9 rotates the motor shaft 101a of the first drive motor 101 in one direction so that the pickup roller 13 and the paper feed roller 20 feed the sheet S. [ For example, the control unit 9 rotates the motor shaft 101a of the first drive motor 101 clockwise. Then, the paper feed drive pulley 25 provided on the motor shaft 101a of the first drive motor 101 rotates to rotate the paper feed drive belt 24. When the paper feeding drive belt 24 rotates, the paper feeding pulley 23 provided on the paper feeding roller shaft 20a rotates clockwise. At this time, since the drive clutch 27 connecting the paper feed pulley 23 and the paper feed roller shaft 20a is in an ON state, when the paper feed pulley 23 rotates, the paper feed roller shaft 20a rotates integrally. Therefore, when the paper-feeding roller shaft 20a rotates clockwise, the paper-feeding roller gear 20b and the paper-feeding roller 20 also rotate integrally in a clockwise direction. When the feeding roller gear 20b rotates, the pickup roller gear 13b connected to the idle gear 15 rotates. At this time, when the feeding roller gear 20b rotates clockwise, the idle gear 15 rotates counterclockwise, and the pickup roller gear 13b rotates clockwise. Therefore, the pickup roller 13 provided on the pickup roller shaft 13a integrally with the pickup roller gear 13b also rotates clockwise. The sheets S stacked on the sheet cassette 11 are picked up one by the pickup roller 13 and transported between the feed roller 20 and the anti-slip roller 30. [

The sheet conveyance frictional force generated between the sheet S and the conveyance prevention roller 30 is transmitted to the magnetic torque limiter 40 when the sheet S is drawn between the conveyance prevention roller 30 and the sheet feeding roller 20. [ Is larger than the critical torque value, the conveyance prevention roller 30 is rotated in the counterclockwise direction by the sheet feeding roller 20. Therefore, the sheet S, which is drawn between the sheet feeding roller 20 and the sheet conveying prevention roller 30, is conveyed in the sheet conveying direction.

Two or more sheets S may be drawn between the sheet feeding roller 20 and the sheet conveying preventing roller 30 while the sheet stacking unit 10 picks up and transports the sheet S, At this time, the control unit 9 returns the sheet S positioned between the sheet feeding roller 20 and the conveyance prevention roller 30 to the sheet cassette 11, retry mode).

The state in which the control section 9 conveys the sheet S positioned between the sheet feeding roller 20 and the sheet conveyance preventing roller 30 to the sheet cassette 11 is shown in Fig.

Specifically, the control unit 9 rotates the motor shaft 102a of the second driving motor 102 clockwise so that the pickup roller up cam 150 moves downward the projecting portion 21a of the paper feed roller holder 21 Pressure. When the pick-up roller lifting cam 150 presses the projecting portion 21a of the paper feed roller holder 21 downward, the paper feed roller holder 21 rotates counterclockwise around the paper feed roller shaft 20a, (13) is spaced apart from the sheet cassette (11). At this time, since the conveyance prevention roller release cam 140 also rotates in the clockwise direction, the conveyance prevention roller release cam 140 is separated from the projecting portion 33a of the conveyance prevention roller holder 33. Therefore, the conveyance prevention roller holder 33 is not subjected to the force by the conveyance prevention roller release cam 140, so that the conveyance prevention roller 30 presses the paper feed roller 20.

In addition, the control unit 9 controls the drive clutch 27 provided on the paper feeding roller shaft 20a to be turned off.

In this state, the control unit 9 rotates the motor shaft 101a of the first drive motor 101 clockwise. Then, the paper feed drive pulley 25 provided on the motor shaft 101a of the first drive motor 101 rotates to rotate the paper feed drive belt 24. When the paper feeding drive belt 24 rotates, the paper feeding pulley 23 provided on the paper feeding roller shaft 20a rotates clockwise. At this time, since the drive clutch 27 connecting the paper feed pulley 23 and the paper feed roller shaft 20a is in the off state, the paper feed roller shaft 20a does not rotate even if the paper feed pulley 23 rotates. Therefore, the paper feeding roller gear 20b and the paper feeding roller 20 integrally provided on the paper feeding roller shaft 20a are not rotated either. If the feeding roller gear 20b does not rotate, the pickup roller gear 13 connected to the idle gear 15 also does not rotate. At this time, the paper feed roller 20 connected to the paper feed roller shaft 20a by the one-way clutch 20c can freely rotate in a counterclockwise direction.

When the motor shaft 101a of the first drive motor 101 rotates clockwise, the anti-slip drive pulley 133 also rotates together with the feed drive pulley 25 integrally with the motor shaft 101a. When the motor shaft 101a of the first drive motor 101 rotates in the clockwise direction, the anti-slip drive pulley 133 also rotates clockwise. The second intermediate pulley 132 provided on the intermediate shaft 130 also rotates clockwise by the anti-transfer belt 136 when the anti-rotation driving pulley 133 rotates clockwise. When the second intermediate pulley 132 rotates clockwise, the first intermediate pulley 131 provided on the intermediate shaft 130 also rotates clockwise. When the first intermediate pulley 131 rotates clockwise, the anti-rotation preventing pulley 48 installed on one side of the magnetic torque limiter 40 rotates clockwise. When the carry preventing pulley 48 rotates clockwise, the magnetic torque limiter 40 rotates clockwise to rotate the carry preventing roller 30 in the clockwise direction.

When the conveyance prevention roller 30 rotates clockwise, the conveyance prevention roller 30 and the paper feed roller 20 are rotated in the clockwise direction because the conveyance prevention roller 30 presses the paper feed roller 20 by the elastic member 35. Therefore, ) Can be transported to the sheet cassette 11. The sheet cassette 11 can be transported to the sheet cassette 11. [ At this time, the sheet feeding roller 20 rotates in the counterclockwise direction due to the frictional force between the sheet feeding preventing roller 30 and the sheet S, so that the sheet S can move in the direction opposite to the sheet feeding direction .

Therefore, the drive clutch 27 for selectively blocking the rotational force transmitted to the paper feed roller 20, the first drive motor 101 for rotating the carry preventing roller 30, and the carry preventing roller 30, It is possible to constitute a sheet conveying unit that conveys the sheet S conveyed between the conveying roller 30 and the sheet feeding roller 20 to the sheet cassette 11. [

When the operation of returning the sheet S positioned between the conveyance prevention roller 30 and the sheet feeding roller 20 to the sheet cassette 11 is completed, the control unit 9 controls the first driving motor 101, The sheet S stacked on the sheet stacking unit 10 is controlled by controlling the sheet feeding roller 102 and the sheet feeding roller 20, the pickup roller 13 and the conveyance prevention roller 30 in the state shown in Fig. To the feeding roller 20 again.

The control unit 9 controls the first drive motor 101 and the second drive motor 102 to feed the sheet S to the sheet feeding roller 20, the pickup roller 13, The prevention roller 30 is brought into the state of Fig. 11 in the state of Fig. 12 described above.

Specifically, the control section 9 rotates the second drive motor 102 in one direction so that the anti-scattering roller releasing cam 140 rotates counterclockwise. For example, in FIG. 12, the motor shaft 102a of the second driving motor 102 is rotated counterclockwise so that the anti-scattering roller releasing cam 140 rotates counterclockwise in a horizontal state. Then, the anti-scattering roller releasing cam 140 presses the projecting portion 33a of the anti-scattering roller holder 33 upward, so that the anti-scattering roller holder 33 rotates clockwise about the intermediate shaft 130 . Then, the elastic member 35 provided at the lower portion of the anti-slip roller holder 33 is compressed, and the anti-slip roller 30 is separated from the paper feeding roller 20.

When the motor shaft 102a of the second drive motor 102 rotates in the counterclockwise direction, the pickup roller up cam 150 also rotates counterclockwise. The pickup roller up cam 150 does not apply a force to the protruding portion 21a of the paper feed roller holder 21 so that the pickup roller 13 remains in contact with the sheet S. [

The control unit 9 controls the sheet feeding roller 20 and the sheet conveying preventing roller 30 so that even when the sheet S is jammed between the sheet feeding roller 20 and the sheet conveying preventing roller 30, And controls the first drive motor 101 and the second drive motor 102 so that the first drive motor 101 and the second drive motor 102 are driven.

As described above, according to the sheet feeding apparatus 1 of the embodiment of the present invention, when a sheet conveyance occurs between the conveyance prevention roller 30 and the sheet feeding roller 20, the sheet S is automatically fed to the sheet cassette 11), and then the paper feeding operation can be performed again.

The sheet feeding apparatus described above is configured to transmit the rotation of the first drive motor and the second drive motor using a belt and a pulley, but the power transmission structure is not limited thereto. It is a matter of course that the belt power transmission structure can be changed to a gear power transmission structure.

Hereinafter, a sheet feeding apparatus according to another embodiment of the present invention will be described with reference to FIGS. 15 to 16. FIG.

FIG. 15 is a view schematically showing a sheet feeding apparatus according to another embodiment of the present invention, and FIG. 16 is a plan view showing a sheet feeding preventing roller of the sheet feeding apparatus of FIG.

15 and 16, a sheet feeding apparatus 1 according to an embodiment of the present invention includes a sheet stacking unit 10, a sheet feeding roller 20, a sheet conveying preventing roller 30, and a sheet conveying detecting unit can do.

The sheet stacking unit 10 stacks at least one sheet S and picks up the stacked sheets S one by one and feeds them toward the sheet feeding roller 20. [ The sheet stacking unit 10 may include a sheet cassette 11 and a pickup roller 13 provided above the sheet cassette 11. The sheet cassette 11 is configured to receive a predetermined number of sheets S and the pickup roller 13 feeds a sheet positioned at the top of the sheets S stacked on the sheet cassette 11 to the sheet feeding roller 20, As shown in Fig.

The sheet feeding roller 20 is provided on one side of the sheet stacking unit 10 and moves the sheet S stacked on the sheet stacking unit 10 to the conveying roller 201 side. Specifically, the sheet feeding roller 20 is formed so as to move the sheet S picked up by the pickup roller 13 in the sheet stacking unit 10 to the conveying roller 201 side. The conveying roller 201 can move the sheet S fed by the sheet feeding roller 20 to an image forming unit (not shown).

The paper feed roller 20 is rotatably installed by a drive source (not shown). As one example, the driving source may use a driving motor. Since the structure in which the driving motor rotates the paper feed roller 20 is general, the illustration and description are omitted.

The conveyance prevention roller 30 is provided so as to face the sheet feeding roller 20 and to prevent the sheet S fed from the sheet stacking unit 10 from being conveyed. Specifically, the conveyance prevention roller 30 is arranged to be in contact with the sheet feeding roller 20 at a constant pressure, and a sheet S is conveyed from the sheet stacking unit 10 to the sheet conveying prevention roller 30 and the sheet feeding roller 20, The sheet S is rotated by the rotation of the sheet feeding roller 20 so that the sheet S is conveyed to the conveying roller 201 side. However, when two or more sheets S are pulled in between the conveyance prevention roller 30 and the sheet feeding roller 20, the sheet S is prevented from being conveyed by the sheet conveying prevention roller 30 and the sheet feeding roller 30 20).

A magnetic torque limiter (40) is installed on the conveyance prevention roller (30) to prevent the conveyance. Specifically, the magnetic torque limiter 40 is provided on the rotary shaft 31 of the anti-rotation roller 30 and has a constant critical torque value. The structure of the magnetic torque limiter 40 is the same as that of the above-described embodiment. Therefore, when one sheet S is drawn between the conveyance prevention roller 30 and the sheet feeding roller 20, the magnetic torque limiter 40 causes the sheet conveyance prevention roller 30 to rotate by the sheet feeding roller 20, (S) is normally transported. However, in the case where two or more sheets S are drawn between the conveyance preventing roller 30 and the sheet feeding roller 20, the magnetic torque limiter 40 blocks the sheet S from being fed.

The conveyance detecting unit may include a rotary encoder 60 coaxially installed on the rotary shaft 31 at one side of the conveyance prevention roller 30 and a sensor 65 detecting the rotation and displacement of the rotary encoder 60 . The sensor 65 may be installed on one side of the rotary encoder 60.

The rotary encoders 60 are formed in the shape of a disk, and a plurality of slots 61 are formed on the disk at regular intervals in the circumferential direction. The sensor 65 outputs a pulse signal corresponding to the rotation of the rotary encoder 60 and may be formed of an optical sensor including light emitting portions 66a and 67a and light receiving portions 66b and 67b. The light receiving portions 66b and 67b of the optical sensors 66 and 67 can output pulse signals in accordance with the rotation of the rotary encoder 60. [ The sensor 65 may include two photosensors 66, 67 to detect the direction of rotation of the rotary encoder 60. Two optical sensors, that is, a first optical sensor 66 and a second optical sensor 67 may be provided adjacent to each other in the circumferential direction of the rotary encoder 60. [ The first and second photosensors 66 and 67 may be formed as a single body.

For example, the first photosensor 66 and the second photosensor 67 can be disposed above and below the horizontal line H passing through the rotation center C of the rotary encoder 60. Thus, by providing the first photosensor 66 and the second photosensor 67 in the circumferential direction of the rotary encoder 60, it is possible to detect whether or not the rotary encoder 60 is rotating, the rotational direction, and the displacement. Since the rotary encoder 60 is integrally provided with the conveyance prevention roller 30, it is possible to detect the rotation state, the rotation direction, and the displacement of the conveyance prevention roller 30 through the two photosensors 66 and 67 . The two optical sensors 66 and 67 may be installed in a bracket 69 provided separately from the sheet feeding apparatus 1 so as not to be interfered with by the rotation of the rotary encoder 60.

Hereinafter, the operation of the sheet feeding apparatus according to the embodiment of the present invention will be described with reference to Figs. 17A to 19B.

First, a case in which the sheet feeding apparatus normally feeds one sheet will be described with reference to Figs. 17A and 17B.

17A is a view showing a case where a sheet feeding apparatus according to an embodiment of the present invention feeds a sheet in a normal manner, and FIG. 17B is a diagram showing a case in which a signal outputted from the first photosensor and the second photosensor in the case of FIG. FIG.

17A, a sheet S is picked up by the pick-up roller 13 and is drawn between the sheet feeding roller 20 and the anti-slip roller 30. In this case, since the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the sheet S is larger than the critical torque value of the magnetic torque limiter 40, the conveyance prevention roller 30 is rotated by the sheet feed roller 20 . 17A, when the sheet feeding roller 20 rotates in the clockwise direction, the sheet conveying preventive roller 30 rotates in the counterclockwise direction due to the frictional force with the sheet, To be transported in the transport direction (arrow A direction).

At this time, the two photosensors 66 and 67 provided on one side of the rotary encoder 60 output pulse signals in the order of A-phase and B-phase as shown in Fig. 17B. For example, when the first photosensor 66 outputs the A-phase pulse signal, the second photosensor 67 outputs the B-phase pulse signal delayed by t times the A-phase pulse signal. The controller 9 determines that the sheet S is normally supplied when the A-phase signal and the B-phase signal are output from the first and second photosensors 66 and 67 as shown in FIG. 17B.

Next, a case in which the sheet supplying apparatus 1 supplies two sheets S will be described with reference to Figs. 18A and 18B.

18A is a view showing a case where two sheets are fed to the sheet-conveying prevention roller of the sheet feeding apparatus according to the embodiment of the present invention, FIG. 18B shows the case where the output from the first photosensor and the output from the second photosensor in the case of FIG. Fig.

18A, two sheets S are picked up by the pick-up roller 13 and drawn into between the feed roller 20 and the anti-slip roller 30. In this case, since the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the sheet S is smaller than the critical torque value of the magnetic torque limiter 40, the conveyance prevention roller 30 is rotated by the sheet feed roller 20 And is rotated by a driving source connected to the conveyance prevention roller 30. [ 18A, when the sheet feeding roller 20 rotates clockwise, the conveyance preventing roller 30 is rotated clockwise by a driving source so that the lower sheet is conveyed to the sheet stacking unit 10 To be transported to the sheet cassette 11. Therefore, when the sheet conveyance occurs, the conveyance prevention roller 30 rotates in the opposite direction to the rotation direction when the sheet S is normally conveyed.

At this time, the order of the pulse signals output from the two optical sensors 66 and 67 provided on one side of the rotary encoder 60 changes. For example, as shown in Fig. 18B, during forward rotation, the pulse signals outputted in the order of A-phase and B-phase by the first and second photosensors 66 and 67, When the roller 30 rotates in the reverse direction, the output of the pulse signal changes in the order of the B phase and the A phase. Specifically, when the second light sensor 67 outputs the B-phase pulse signal when the conveyance occurs, the first photosensor 66 outputs the A-phase pulse signal delayed by t times the B-phase pulse signal. When a predetermined period of time (T1 msec) elapses after the order of the A-phase signal and the B-phase signal is changed, the controller 9 stops the feeding roller 20 and the conveyance prevention roller 30, .

Finally, a case in which the sheet feeding apparatus 1 supplies three or more sheets S will be described with reference to Figs. 19A and 19B.

19A is a view showing the case where three or more sheets are supplied to the sheet-conveying prevention roller of the sheet feeding apparatus according to the embodiment of the present invention, FIG. 19B is a view showing the case where the first photosensor and the second photosensor Fig.

19A, a large amount of sheets S, for example, three or more sheets are picked up by the pickup roller 13 and drawn into between the feeding roller 20 and the anti-slip roller 30. [ In this case, the frictional force applied to the conveyance prevention roller 30 by the large amount of sheets S inserted between the paper feed roller 20 and the conveyance prevention roller 30 is larger than the critical torque value of the magnetic torque limiter 40 The conveyance prevention roller 30 rotates in conjunction with the sheet feed roller 20. [ 19A, when the sheet feeding roller 20 rotates in the clockwise direction, the sheet conveying preventive roller 30 is moved in the sheet conveying direction (the direction of the arrow A) with a large amount of frictional force with the sheet S, That is, in the counterclockwise direction. At this time, since a large amount of sheets S are inserted between the sheet feeding roller 20 and the sheet conveying preventing roller 30, the amount of downward displacement (arrow B) of the sheet conveying preventing roller 30 increases. The lower displacement B of the conveyance prevention roller 30 can be detected by the two photosensors 66 and 67.

At this time, the two photosensors 66 and 67 provided on one side of the rotary encoder 60 output pulse signals in the order of A-phase and B-phase as shown in Fig. 19B. However, the interval between the A-phase pulse and the B-phase pulse is shorter than in the case of normal rotation. For example, when the anti-scattering roller 30 rotates in the forward direction, when the first photosensor 66 outputs the A-phase pulse signal, the second photosensor 67 detects the B Phase pulse signal. At this time, the interval between the A-phase pulse signal and the B-phase pulse signal is T. When a large amount of sheets S are inserted between the conveyance prevention roller 30 and the paper feed roller 20, as shown in Fig. 19B, the A phase output from the first and second photosensors 66 and 67 The order of the pulse signal and the B-phase pulse signal is the same, but the interval between the A-phase pulse signal and the B-phase pulse signal is shortened to T2 (msec). The controller 9 stops the feeding roller 20 and the anti-rotation roller 30 when a predetermined period (T3 msec) elapses after detecting that the pulse interval between the A-phase signal and the B- The occurrence of sheet conveyance is informed to the outside.

In the above, the sheet feeding device 1 which is the active conveyance prevention roller configured to rotate the conveyance prevention roller 30 by the driving source has been described. However, the sheet feeding device 1 may use a semi-active conveyance prevention roller configured not to receive power from the driving source by the conveyance prevention roller.

The structure of the sheet feeding device including the semi-active conveyance prevention roller is the same as that of the embodiment shown in Figs. 15 and 16 except that a drive shaft for transmitting rotational force from a separate driving source is not connected to the housing shaft of the magnetic torque limiter The same as the structure of the sheet feeding apparatus. Therefore, the description of the structure of the sheet feeding apparatus including the semi-active conveying prevention roller is omitted.

Hereinafter, the operation of the sheet feeding apparatus including the semi-active conveying prevention roller will be described.

First, when one sheet S is inserted between the sheet feeding roller 20 and the sheet conveying preventing roller 30, the sheet conveying preventing roller 30 is rotated by the sheet conveying frictional force, so that the two photosensors 66, And outputs the A-phase pulse signal and the B-phase pulse signal in the same manner as in Fig. 17B. The controller 9 determines that the sheet S is normally supplied when the A-phase signal and the B-phase signal are output from the first and second photosensors 66 and 67 as shown in FIG. 17B.

Next, a case where the sheet stacking unit 10 supplies two sheets S will be described with reference to Figs. 20A and 20B.

20A is a view showing a case where two sheets are supplied to the sheet-conveying prevention roller of the sheet feeding apparatus including the semi-active conveyance prevention roller of FIG. 15, FIG. 20B shows a case where the first light sensor and the second light Fig. 5 is a diagram showing signals output from the sensor. Fig.

20A, two sheets S are picked up by the pick-up roller 13 and drawn into between the feed roller 20 and the anti-slip roller 30. In this case, since the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the sheet S is smaller than the critical torque value of the magnetic torque limiter 40, the conveyance prevention roller 30 is rotated by the sheet feed roller 20 And maintains the stopped state. 20A, when the two sheets S are pulled in the case where the sheet feeding roller 20 rotates clockwise, the anti-misplacement roller 30 is rotated by the rotation of the sheet feeding roller 20 It is stopped regardless.

At this time, no pulse signal is output from the two optical sensors 66 and 67 provided on one side of the rotary encoder 60. [ For example, as shown in Fig. 20B, when forward rotation is performed, the pulse signals outputted in the order of A-phase and B-phase in the first and second photosensors 66 and 67, , The A phase pulse signal and the B phase pulse signal are not outputted unless the conveyance prevention roller 30 is rotated. When a predetermined period of time (T1 msec) elapses after the pulse signal is not output after any one of the A-phase signal and the B-phase signal is outputted, the control section 9 stops the feeding roller 20, The occurrence of sheet conveyance is informed to the outside.

Finally, the case where the sheet stacking unit 10 feeds three or more sheets S between the anti-scattering roller 30 and the sheet feeding roller 20 will be described with reference to Figs. 21A and 21B.

21A is a view showing a case where three or more sheets are supplied to the sheet-conveying prevention roller of the sheet feeding apparatus including the semi-active conveying prevention roller, and FIG. 21B is a view showing a state in which the first light sensor and the second light sensor Fig.

21A, a large amount of sheets S, for example, three or more sheets S are picked up by the pickup roller 13 and drawn into between the feeding roller 20 and the anti-slip roller 30. In this case, the frictional force applied to the conveyance prevention roller 30 by the large amount of sheets S inserted between the paper feed roller 20 and the conveyance prevention roller 30 is larger than the critical torque value of the magnetic torque limiter 40 The conveyance prevention roller 30 rotates in conjunction with the sheet feed roller 20. [ 21A, when the sheet feeding roller 20 rotates in the clockwise direction, the sheet conveying preventive roller 30 is moved in the sheet conveying direction (the direction of the arrow A) with a large amount of frictional force with the sheet S, That is, in the counterclockwise direction. At this time, since a large amount of sheets S are inserted between the sheet feeding roller 20 and the sheet conveying preventing roller 30, the amount of downward displacement (arrow B) of the sheet conveying preventing roller 30 increases. The lower displacement B of the conveyance prevention roller 30 can be detected by the two photosensors 66 and 67.

At this time, the two optical sensors 66 and 67 provided on one side of the rotary encoder 60 output pulse signals in the order of A-phase and B-phase as shown in Fig. 21B. However, the interval between the A-phase pulse and the B-phase pulse is shorter than in the case of normal rotation. For example, when the anti-scattering roller 30 rotates in the forward direction, when the first photosensor 66 outputs the A-phase pulse signal, the second photosensor 67 detects the B Phase pulse signal. At this time, the interval between the A-phase pulse signal and the B-phase pulse signal is T. When a large amount of sheets S are inserted between the conveyance prevention roller 30 and the paper feed roller 20, as shown in Fig. 19B, the A phase output from the first and second photosensors 66 and 67 The order of the pulse signal and the B-phase pulse signal is the same, but the interval between the A-phase pulse signal and the B-phase pulse signal is shortened to T2 (msec). When a predetermined period (T3 msec) elapses after detecting that the pulse interval between the A-phase signal and the B-phase signal is short, the control section 9 stops the feeding roller 20, It informs.

In the above description, two optical sensors 66 and 67 of the medium detection unit are disposed adjacent to each other. However, the arrangement of the two optical sensors 66 and 67 is not limited thereto. For example, the two photosensors 66 and 67 may be disposed at intervals of about 90 degrees. Hereinafter, a sheet feeding apparatus including a medium-conveyance detecting unit in which two optical sensors are disposed at about 90 degrees will be described with reference to Figs. 22 and 23. Fig.

FIG. 22 is a view schematically showing a sheet feeding apparatus according to another embodiment of the present invention, and FIG. 23 is a plan view showing a sheet feeding preventing roller of the sheet feeding apparatus of FIG.

22 and 23, a sheet feeding apparatus 1 according to an embodiment of the present invention includes a sheet stacking unit 10, a sheet feeding roller 20, a sheet conveying preventing roller 30, can do.

The sheet stacking unit 10, the sheet feeding roller 20, and the sheet conveying preventing roller 30 are provided in the sheet stacking unit 10, the sheet feeding roller 20, Transporting roller 30, detailed description thereof will be omitted.

The conveyance detecting unit includes a rotary encoder 70 provided coaxially with the rotary shaft 31 at one side of the conveyance prevention roller 30 and sensors 76 and 77 for detecting the rotation and displacement of the rotary encoder 60 . The sensors 76 and 77 may be installed on one side of the rotary encoder 70.

The rotary encoders 70 are formed in a disk shape, and a plurality of slots 71 are formed on the disk at regular intervals in the circumferential direction. The sensors 76 and 77 output pulse signals corresponding to the rotation of the rotary encoder 70 and may be formed as optical sensors including light emitting portions 76a and 77a and light receiving portions 76b and 77b.

The light receiving portions 76b and 77b of the optical sensors 76 and 77 can output pulse signals in accordance with the rotation of the rotary encoder 70. [ The sensor may include two optical sensors, i.e., a first optical sensor 76 and a second optical sensor 77, so as to detect the direction of rotation of the rotary encoder 70. The two photosensors 76 and 77 may be installed at intervals of about 90 degrees with respect to the rotation center C of the rotary encoder 70. [ For example, the first photosensor 76 is disposed on a horizontal line H passing through the center C of the rotary encoder 70 and the second photosensor 77 is disposed on the center of the rotary encoder 70 C on a vertical line V passing through. 22, the first photosensor 76 is installed on the left side of the rotary encoder 70 and the second photosensor 77 is installed on the lower side of the rotary encoder 70. In the case of the sheet supply apparatus 1 shown in Fig. 22, . If the first photosensor 76 and the second photosensor 77 are provided at intervals of about 90 degrees with respect to the center C of the rotary encoder 70, the rotation of the rotary encoder 70, And displacement can be detected. Since the rotary encoder 70 is provided so as to rotate integrally with the conveyance preventing roller 30, it is possible to detect whether the conveyance preventing roller 30 is rotated, rotated, and displaced via the two photosensors 76 and 77 . The two optical sensors 76 and 77 may be installed in a bracket 79 provided separately from the sheet feeding apparatus 1 so as not to be interfered by the rotation of the rotary encoder 70.

Hereinafter, the operation of the sheet feeding apparatus according to one embodiment of the present invention will be described with reference to FIGS. 24A to 26B.

24A is a view showing a case where the sheet feeding device according to the embodiment of the present invention feeds sheets in a normal manner, FIG. 24B is a diagram showing a case in which a signal outputted from the first photosensor and the second photosensor in the case of FIG. FIG.

24A, a sheet S is picked up by the pickup roller 13 and is drawn between the feeding roller 20 and the anti-slip roller 30. In this case, since the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the sheet S is larger than the critical torque value of the magnetic torque limiter 40, the conveyance prevention roller 30 is rotated by the sheet feed roller 20 . 24A, when the sheet feeding roller 20 rotates in a clockwise direction, the sheet S preventing roller 30 rotates in a counterclockwise direction due to a frictional force with the sheet, To be transported in the transport direction (arrow A direction).

At this time, the two optical sensors 76 and 77 provided on one side and the bottom side of the rotary encoder 70 output pulse signals in the order of A phase and B phase, as shown in Fig. 24B. For example, when the first photosensor 76 outputs the A-phase pulse signal, the second photosensor 77 outputs the B-phase pulse signal delayed by t times the A-phase pulse signal. The control unit 9 determines that the sheet S is normally supplied when the A-phase signal and the B-phase signal are output from the first and second photosensors 76 and 77 as shown in FIG. 24B.

Next, a case in which the sheet stacking unit 10 supplies two sheets S will be described with reference to Figs. 25A and 25B.

25A is a view showing a case where two sheets are supplied to a sheet-conveying prevention roller of a sheet feeding apparatus according to an embodiment of the present invention, Fig. 25B is a diagram showing the case where the sheet is fed from the first photosensor and the second photosensor Fig.

25A, two sheets S are picked up by the pick-up roller 13 and drawn into between the feed roller 20 and the anti-slip roller 30. In this case, since the sheet conveyance frictional force generated between the conveyance prevention roller 30 and the sheet S is smaller than the critical torque value of the magnetic torque limiter 40, the conveyance prevention roller 30 is rotated by the sheet feed roller 20 And is rotated by a driving source connected to the conveyance prevention roller 30. [ 25A, when the sheet feeding roller 20 rotates in the clockwise direction, the sheet conveying preventive roller 30 is rotated clockwise by the driving source so that the lower sheet is conveyed to the sheet stacking unit 10 To be transported to the sheet cassette 11. Therefore, when the sheet conveyance occurs, the conveyance prevention roller 30 rotates in the opposite direction to the rotation direction when the sheet S is normally conveyed.

At this time, the order of the pulse signals outputted from the two optical sensors 76 and 77 provided on one side and the lower side of the rotary encoder 70 is changed. For example, as shown in Fig. 25B, when forward rotation is performed, the pulse signals outputted in the order of A-phase and B-phase by the first and second photosensors 76 and 77 are generated by the sheet- When the roller 30 rotates in the reverse direction, the output of the pulse signal changes in the order of the B phase and the A phase. Specifically, when the second light sensor 77 outputs the B-phase pulse signal when the conveyance occurs, the first photosensor 76 outputs the A-phase pulse signal delayed by t time with respect to the B-phase pulse signal. When a certain period of time (T1 msec) elapses after the order of the A-phase signal and the B-phase signal has changed, the controller 9 determines that the sheet feeding has occurred. Then, the control unit 9 stops the feeding roller 20 and the conveyance preventing roller 30, and notifies the outside of the occurrence of sheet conveyance.

Finally, the case where the sheet stacking unit 10 supplies three or more sheets S will be described with reference to Figs. 26A and 26B.

FIG. 26A is a view showing a case where three or more sheets are supplied to the sheet-conveying prevention roller of the sheet supply apparatus according to the embodiment of the present invention, FIG. 26B is a view showing a state in which the first light sensor and the second light sensor Fig.

Referring to FIG. 26A, a large amount of sheets S, for example, three or more sheets S are picked up by the pickup roller 13 and drawn into between the feeding roller 20 and the anti- In this case, the frictional force applied to the conveyance prevention roller 30 by the large amount of sheets S inserted between the paper feed roller 20 and the conveyance prevention roller 30 is larger than the critical torque value of the magnetic torque limiter 40 The conveyance prevention roller 30 rotates in conjunction with the sheet feed roller 20. [ 26A, when the sheet feeding roller 20 rotates in the clockwise direction, the sheet conveying prevention roller 30 is moved in the sheet conveying direction (the direction of the arrow A) by the frictional force with a large amount of the sheet S, That is, in the counterclockwise direction. At this time, since a large amount of sheets S are inserted between the sheet feeding roller 20 and the sheet conveying preventing roller 30, the lower amount of displacement (arrow B) in which the sheet conveying preventing roller 30 moves downward increases. The lower displacement of the conveyance prevention roller 30 can be detected by the two photosensors 76 and 77.

At this time, the two optical sensors 76 and 77 provided at one side of the rotary encoder 70 and at the bottom side output pulse signals in the order of A phase and B phase, as shown in Fig. 26B. The interval of the A-phase pulse becomes shorter than that of the normal rotation, but the interval of the B-phase pulse is the same as that of the normal rotation. For example, when the anti-scattering roller 30 rotates in the forward direction, when the first photosensor 76 outputs the A-phase pulse signal, the second photosensor 77 detects the B Phase pulse signal. At this time, the interval between the A-phase pulse signal and the B-phase pulse signal is T. When a large number of sheets S are inserted between the conveyance prevention roller 30 and the sheet feeding roller 20, as shown in Fig. 26B, the A-phase output from the first and second photosensors 76 and 77 The order of the pulse signal and the B-phase pulse signal is the same, but the interval of the A-phase pulse signal is shortened to T2 (msec). However, since the second optical sensor 77 is disposed on the vertical line V passing the center C of the rotary encoder 70, even if the conveyance prevention roller 30 moves downward, It is not possible to detect a change in the position of the switch 71. Therefore, the second photosensor 77 outputs a normal B-phase pulse signal. When the difference between the A-phase signal and the B-phase signal occurs, the control section 9 determines that a large number of sheet conveyance has occurred.

As another example, the frequency of the pulse signal output from the first photosensor 76 and the second photosensor 77 may be converted into a voltage so as to determine the occurrence of the misfiring of a large sheet.

26C is a diagram showing a case where the frequency of a pulse signal output from the first photosensor and the second photosensor is converted into a voltage in the case of FIG. 26A. FIG.

Referring to Fig. 26C, the A phase represents the conversion of the frequency of the pulse signal on A in Fig. 26B into a voltage. When the rotary encoder 70 rotates normally, the first photosensor 76 outputs a pulse signal at time intervals of T as shown in FIG. 26B. When the pulse signal in this case is converted into a voltage, it can be represented by a voltage of? A as shown in Fig. 26C. When a conveyance of a large sheet occurs, the first photosensor 76 outputs pulse signals at T2 time intervals as shown in Fig. 26B, and the number of pulses increases. When the frequency of the pulse signal in this case is converted into a voltage, it can be shown that the voltage is increased by? B as in the portion K in Fig. 26C. Therefore, when the conveyance of a large sheet occurs, the voltage of the A-phase signal becomes? A +? B.

The B-phase pulse signal output from the second photosensor 77 does not change, as shown in Fig. 26 (b), even if a large amount of sheets are conveyed. Therefore, when the pulse signal frequency in this case is converted into a voltage, it can be represented by a voltage of? A as shown in Fig. 26C.

Therefore, when the frequency of the pulse signal output from the first photosensor 76 and the second photosensor 77 is converted into a voltage, the control unit 9 controls the first photosensor 76 and the second photosensor 76 77) output signal is Δb, it can be determined that the conveyance of a large number of sheets has occurred.

The sheet feeding device including the active conveying prevention roller configured to be rotatable by the driving source as the conveyance preventing roller 30 has been described above. However, the sheet feeding device may use a semi-active conveyance prevention roller configured not to receive the power from the driving source by the conveyance prevention roller, and its operation is similar to the above-described embodiment, and a detailed description thereof will be omitted.

As described above, the sheet feeding device according to the embodiment of the present invention can detect the rotation, the rotational direction, and the downward displacement of the conveyance prevention roller by using the magnetic torque limiter and the hall sensor installed on one side of the conveyance prevention roller, Reliable sheet conveyance detection can be achieved with a simple structure.

Further, the sheet feeding apparatus according to the embodiment of the present invention can detect the rotation, the rotational direction, and the downward displacement of the conveyance prevention roller by using the rotary encoder and the optical sensor provided on one side of the conveyance prevention roller, It is possible to detect reliable sheet conveyance. Therefore, according to the present invention, it is possible to provide a sheet feeding apparatus having a low-cost, small-sized, and highly reliable medium conveyance detecting function.

In addition, since the sheet feeding device according to the embodiment of the present invention can automatically return the sheet positioned between the sheet feeding roller and the sheet conveying prevention roller to the sheet stacking unit and then perform the sheet feeding operation again, The operating ratio of the sheet feeding apparatus according to the embodiment can be improved.

Although the sheet feeding apparatus according to an embodiment of the present invention is applied to the image forming apparatus, the sheet feeding apparatus according to an embodiment of the present invention is not limited thereto. The sheet feeding apparatus according to an embodiment of the present invention can be used for a facsimile, an automatic document reading apparatus, a large capacity paper feeding apparatus, etc. in which a large amount of sheets need to be fed.

The invention has been described above in an illustrative manner. The terms used herein are for the purpose of description and should not be construed as limiting. Various modifications and variations of the present invention are possible in light of the above teachings. Therefore, unless otherwise indicated, the present invention may be practiced freely within the scope of the claims.

One; Sheet feeder 9; The control unit
10; Sheet stacking unit 11; Sheet cassette
13; Pickup roller 15; Idle gear
20; A feed roller 21; Feed roller holder
27; A drive clutch 30; Conveying prevention roller
31; A rotating shaft 40; Magnetic torque limiter
41; Permanent magnet 43; housing
45; A magnetic member 47; Housing shaft
50, 51, 52; Hall sensor 60; Rotary encoder
61; Slots 66, 67; Light sensor
70; A rotary encoder 71; slot
76,77; Optical sensor 100; Driving source
101, 102; A driving motor 140; Dust prevention roller release cam
150; Pickup roller lifting cam 201; Conveying roller

Claims (20)

A sheet stacking unit for stacking at least one sheet;
A sheet feeding roller installed at one side of the sheet stacking unit for feeding the sheet stacked on the sheet stacking unit;
A sheet conveying roller facing the sheet feeding roller and preventing a sheet conveyed from the sheet stacking unit from being conveyed;
A magnetic torque limiter provided coaxially with the conveyance prevention roller; And
And a Hall sensor installed at one side of the magnetic torque limiter and detecting rotation of the magnetic torque limiter. The method according to claim 1,
Wherein the magnetic torque limiter comprises:
A plurality of permanent magnets provided in the circumferential direction on the rotation axis of the conveyance prevention roller;
A housing provided to surround the plurality of permanent magnets; And
And a magnetic member provided on the inner surface of the housing so as to face the plurality of permanent magnets,
And the plurality of permanent magnets and the magnetic member are spaced apart from each other by a predetermined distance. 3. The method of claim 2,
The length of the magnetic member is smaller than the length of the plurality of permanent magnets,
Wherein the hall sensor is installed at a position corresponding to a portion of the plurality of permanent magnets that do not overlap with the magnetic member. 3. The method of claim 2,
Wherein the magnetic member includes a plurality of slits provided in the circumferential direction,
And the hall sensor is installed at a position corresponding to the plurality of slits of the magnetic member. The method according to claim 1,
Wherein the Hall sensor includes two Hall sensors installed in the circumferential direction of the magnetic torque limiter. The method according to claim 1,
And a drive source which is provided at one end of the magnetic torque limiter and is capable of rotating the conveyance prevention roller. The method according to claim 1,
A control unit configured to determine whether or not the sheet is conveyed by using a signal transmitted from the hall sensor; And
And a sheet conveying unit that conveys the conveyed sheet to the sheet stacking unit when a conveyance occurs in the conveyance prevention roller. 8. The method of claim 7,
The sheet conveying unit includes:
A driving clutch selectively blocking the rotational force transmitted to the paper feed roller; And
And a driving source for rotating the conveyance prevention roller,
The control unit operates the drive clutch to cut off the rotational force transmitted to the paper feed roller and rotates the paper feed roller so as to rotate the paper feed roller and the conveyance preventive roller, To the sheet stacking unit. 8. The method of claim 7,
The Hall sensor includes a first hall sensor for outputting an A-phase pulse signal and a second Hall sensor for outputting a B-phase pulse signal later than the A-phase signal,
Wherein the control unit determines that the conveyance occurs when the reference time elapses after the order of the A-phase pulse signal and the B-phase pulse signal is reversed. 8. The method of claim 7,
The Hall sensor includes a first hall sensor for outputting an A-phase pulse signal and a second Hall sensor for outputting a B-phase pulse signal later than the A-phase signal,
Wherein the control unit determines that the interval between the A-phase pulse signal and the B-phase pulse signal is shortened and that the short-time A-phase pulse signal and the B- . 8. The method of claim 7,
The Hall sensor includes a first hall sensor for outputting an A-phase pulse signal and a second Hall sensor for outputting a B-phase pulse signal later than the A-phase signal,
Wherein the control unit determines that a conveyance occurs when a predetermined time elapses after the output of the A-phase pulse signal and the B-phase pulse signal is stopped. A sheet stacking unit for stacking at least one sheet;
A sheet feeding roller provided on one side of the sheet stacking unit for feeding the sheet fed from the sheet stacking unit;
A sheet conveying roller facing the sheet feeding roller and preventing a sheet conveyed from the sheet stacking unit from being conveyed;
A rotary encoder installed on one side of the conveyance prevention roller coaxially with the conveyance prevention roller; And
And a sensor installed at one side of the rotary encoder for detecting rotation of the rotary encoder. 13. The method of claim 12,
The sensor includes two optical sensors,
Wherein the two optical sensors are installed adjacent to each other in the circumferential direction of the rotary encoder. 13. The method of claim 12,
Wherein the sensor comprises two photosensors,
Wherein the two photosensors are installed at intervals of 90 degrees with respect to the rotation center of the rotary encoder. 15. The method of claim 14,
The two optical sensors
A first photosensor mounted on a horizontal line passing through the center of the rotary encoder; And
And a second photosensor provided on a vertical line passing through the center of the rotary encoder. 16. The method of claim 15,
Further comprising: a control unit configured to determine whether the sheets are conveyed by using the signals output from the first photosensor and the second photosensor. 17. The method of claim 16,
Wherein the control unit determines that a sheet is conveyed when a difference occurs between the A-phase pulse signal output from the first photosensor and the B-phase pulse signal output from the second photosensor. 17. The method of claim 16,
Wherein the controller determines that a sheet conveyance has occurred when a difference between a voltage of a signal output from the first photosensor and a voltage of a signal output from the second photosensor is generated. 17. The method of claim 16,
And when the sheet conveyance occurs in the conveyance prevention roller, the control unit conveys the conveyed sheet to the sheet stacking unit. A sheet feeding apparatus according to any one of claims 1 to 19, And
And an image forming unit that forms an image on a sheet fed by the sheet feeding device.

Images