JPH11143154A - Sheet feeder and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable sheet feeder and image forming device which decreases scratching of the front end of a thick-type sheet and jamming of the sheet caused by an auxiliary pad, and, furthermore, decreases wear on the auxiliary pad. SOLUTION: By rotating an auxiliary-pad motor 42 little by little, gears D41 and C40 are rotated to drive a gear 38 so formed as to be integrated with an auxiliary-pad holder 37, and thus the auxiliary pad 14 is gradually moved in the direction where it is drawn back from a sheet insertion face. When a top sensor 44 detects the arrival of the sheet during the process, the auxiliary- pad motor 42 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stacking sheets such as paper, postcards, envelopes, and the like, in which double feed prevention is performed by using two fixed auxiliary pads without rollers facing each other which are used in an image forming apparatus. The present invention relates to a sheet feeding device for feeding and conveying.

[0002]

2. Description of the Related Art Conventionally, in a sheet feeding apparatus for stacking, feeding, and conveying sheets such as paper, postcards, and envelopes, a separation pad pressed against and in contact with a feeding roller is fixed without an opposing roller. The sheet feeding apparatus that performs double feeding prevention by using two of the auxiliary pads is configured as follows.

FIG. 12 is a cross-sectional view of a main part schematically showing a main cross-section of the prior art. In FIG. 12, reference numeral 101 denotes a width regulating plate a which determines the position of the sheet in the width direction by abutting the sheet bundle in the width direction. Although not shown, a symmetrical width regulating plate b is also provided on the near side in the sectional view, and presses both side surfaces of the sheet bundle.

Reference numeral 102 denotes a supply tray for holding a width regulating plate, 103a and 103b denote racks a and b to which the width regulating plate 101 is connected, and rack a is a width regulating plate a101 and rack b is a regulating plate b. Are combined.

Reference numeral 104 denotes a pinion that meshes with both of the racks a and b. Reference numeral 105 denotes a supply frame that positions and holds a part related to supply such as a supply tray.
Reference numeral 06 denotes an intermediate plate that pushes up the stacked sheet bundle.
Reference numeral 07 denotes a middle plate cam which is fixed to the middle plate 106 and abuts on a cam (not shown) to determine the timing of pushing up the sheet bundle. Reference numeral 108 denotes a supply pressure spring which serves as a power for pushing up the middle plate 106.

Reference numeral 109 denotes a separation pad which is a separating means for separating a sheet to be supplied and feeding only one of the uppermost sheets. Reference numeral 110 denotes a separation pad which is fixed and can be rotated by the supply frame 105. The reference numeral 111 denotes a separation spring for pressing the separation pad holder.

Reference numeral 112 denotes a feeding roller having a D-quad shape for applying a feeding force to one of the uppermost sheets of the stacked sheets by its rotation. Reference numeral 113 denotes a feeding roller collar for holding the feeding roller 112. A feed shaft 114 fixedly holds the feed roller collar 113.

[0008] A driving unit and a control unit (not shown) rotate the feeding shaft 114 when the printing is movable, so that the feeding roller is rotated and a feeding force is applied to one of the uppermost surfaces of the stacked sheets.

Reference numeral 115 denotes a rotation of the feed shaft 114 for determining the attitude of the separation pad 110 at the D-cut retracting portion of the feed roller 112 and for minimizing the resistance at the separation portion when the feed roller is not rotating. Reference numeral 116 denotes a feeding roller freely held, 116 denotes a feeding roller that further feeds the fed sheet and is rotated by a driving unit (not shown), 117 denotes a feeding roller that nips with the feeding roller 116, and 118 denotes a feeding roller. A roller spring that presses the roller 117 in the direction of the conveying roller 116, and an upper surface guide 119 guides the upper surface of the conveyed sheet.

Reference numeral 120 denotes a back exterior of the image forming apparatus using the sheet feeding apparatus, and 121 denotes a top exterior.

FIG. 13 is a sectional view of a main part showing another section of the sheet feeding apparatus according to the prior art.

Reference numeral 122 denotes an auxiliary pad for preventing double feeding of thin sheets which cannot be separated by the separating means.
Secures the auxiliary pad 122 and supplies the supply frame 105
And an auxiliary pad holder joined to the auxiliary pad holder by means not shown.

[0013] Under the above-described configuration, the sheet is set in the following manner.

An appropriate amount of sheet bundle is put on the supply tray 102 and inserted into the sheet feeding device by the user.

Thereafter, the pinion 104 and the rack 10
By aligning both end faces of the sheet bundle with the width regulating plates whose operation is defined by 3a and 3b, the position of the sheet bundle becomes appropriate and the sheet bundle setting is completed.

Next, the operation when the supply operation is started by a control unit (not shown) will be described.

When the feed shaft 114 starts rotating,
The cam (not shown) also rotates, the intermediate plate cam 107 is released, the intermediate plate 106 receives the pressure of the supply spring 108, and the feed roller 11
The sheet bundle is pushed up in the direction of 2.

First, the sheet bundle comes into contact with the feeding roller 115, then comes into contact with the rotating feeding roller 112, and starts to be fed by the frictional force of the feeding roller 112.

The sheet which has begun to be fed first hits the auxiliary pad 122, and a resistive force is applied to the leading end, so that the sheets other than the uppermost surface are stopped in many cases.

Next, a frictional force is applied by the separation pad 110, and in most cases, except for the uppermost sheet, the frictional force and the "judgement" due to the wedge effect are stopped at this portion.

As a result, the sheets that have passed through the auxiliary pad and that have been multi-fed are also stopped, and only the uppermost sheet is fed.

Further, the fed sheet is an upper surface guide 1
The sheet is guided by the feed frame 19 and the supply frame 105, enters the nip portion between the transport roller 116 and the transport roller 117, and receives a stable transport force and is sent to an image forming apparatus (not shown) or the like.

[0023]

However, in the above conventional example, the auxiliary pad for preventing double feeding of sheets is of a fixed type, and thus has the following disadvantages.

[0024] (1) In the auxiliary pad configured to prevent the double feeding of a thin sheet such as a basis weight of 60 g / m ^2, thickness sheet or more than a basis weight 135 g / m ^2, when inserting the envelopes Generates too much resistance.

[0025] For this reason, when the leading end of the sheet abuts against the auxiliary pad, a too large resistance force causes a decrease in the supply performance such as occurrence of a jam or a flaw at the leading end.

(2) Further, when a thick sheet or the like is inserted, the auxiliary pad is rapidly worn.

For this reason, when a thin sheet is fed after a large amount of a thick sheet is supplied, the double feed prevention performance of the auxiliary pad may be deteriorated.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to reduce the occurrence of tip scratches and jams caused by auxiliary pads of a thick sheet type. Moreover, it is an object of the present invention to provide a highly reliable sheet feeding apparatus and an image forming apparatus for reducing wear of the auxiliary pad.

[0029]

According to the present invention, there is provided a feeding roller for feeding a sheet,
A separation pad urged toward the feed roller, and an auxiliary pad that applies a resistance force to the leading ends of the plurality of sheets fed to the feed roller prior to the separation pad. In a sheet feeding apparatus that separates and feeds only one sheet from a plurality of sheets fed to the feeding roller by the separation pad, the auxiliary pad is movable in a direction away from a sheet insertion surface, The position can be switched according to the thickness of the sheet.

Therefore, in the sheet feeding apparatus configured as described above, when the thick sheet or the like is inserted, the auxiliary pad moves away from the sheet insertion surface and retracts to apply resistance to the sheet. As a result, the sheet is prevented from being damaged or jammed due to excessive resistance when the leading end of the sheet hits the auxiliary pad.

When the auxiliary pad is not used, it is preferable to retract the auxiliary pad to a position where it does not come into contact with a sheet.

Accordingly, when the thick sheet is inserted and the use of the auxiliary pad is inappropriate, the auxiliary pad is evacuated, so that the wear of the auxiliary pad can be reduced.

It is preferable that the auxiliary pad is provided with a width regulating means for regulating a sheet size width, and the auxiliary pad is interlocked with a moving operation of the width regulating means.

Thus, the switching setting of the auxiliary pad can be performed by switching the sheet size width by the width regulating means.

It is preferable that the auxiliary pad is urged toward the feeding roller by an urging means.

Thus, the auxiliary pad is also movable in accordance with the resistance generated by the sheet, and the sheet can be fed according to the thickness of the sheet to be inserted.

An image forming apparatus according to the present invention includes the above-described sheet feeding apparatus, and an image forming section for forming an image on a sheet fed from the sheet feeding apparatus. Features.

Accordingly, it is possible to reduce the occurrence of a front end scratch and a jam in a thick sheet type.

[0039]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) A case of an image forming apparatus will be briefly described as an example to which a sheet feeding apparatus according to an embodiment of the present invention is applied.

FIG. 1 is a schematic sectional view of an image forming apparatus.
The configuration of the image forming apparatus 1 will be described. The optical system 64 irradiates a light image based on target image information by an exposure unit (slid image forming projection unit of a document image, a laser scanning exposure unit, etc., not shown), and a latent image is formed on a photosensitive drum 63 serving as an image carrier. Is formed, and the latent image is visualized with a developer (hereinafter, referred to as toner) to form a toner image.

In synchronism with the formation of the toner image, the sheet is conveyed from the supply tray 7 by a conveying means including a feeding roller 8 and a conveying roller 10 and the like. ,
The toner image formed on the photosensitive drum 63 is transferred to a sheet by a transfer roller 62 as a transfer unit, and the sheet is fixed by a fixing rotator 65 a and a fixing rotator 65 having a built-in heater.
The transfer toner image is conveyed to a fixing unit 65 composed of a pressure roller 65b that presses and conveys the transfer toner image to fix the transfer toner image on the sheet.

Then, the sheet is discharged to a discharge tray 67 by a discharge roller pair 66.

On the other hand, a process cartridge 53 constituting an image forming section rotates a photosensitive drum 63 having a photosensitive layer, and uniformly charges the surface thereof by applying a voltage to a charging roller 68 serving as a charging means. The light image from the light 64 is exposed to the photosensitive drum 63 via an exposure unit to form a latent image, and the latent image is developed by the developing unit 69.

Then, a voltage having a polarity opposite to that of the toner image is applied to the transfer roller 62 to transfer the toner image onto the sheet. Thereafter, the toner remaining on the photosensitive drum 63 is scraped off by the cleaning blade 70a, and the waste toner container is removed. The residual toner on the photosensitive drum 63 is removed by the cleaning means 70 which collects the toner on the photosensitive drum 63b.

FIG. 2 shows a sheet feeding apparatus according to the first embodiment.

Reference numeral 5 denotes a supply frame for positioning and holding components related to supply, such as a supply tray. Reference numeral 6 denotes an intermediate plate that pushes up a stacked sheet bundle. This is a middle plate cam that determines the timing of contact and pushing up the sheet bundle.

Reference numeral 8 denotes a feeding roller having a D-cut shape for applying a feeding force to one of the uppermost sheets of the stacked sheets by rotation thereof, and reference numeral 9 denotes a feeding shaft for fixing and holding the feeding roller 8.

Reference numeral 10 denotes a conveying roller which further conveys the supplied sheet and is rotated by a driving means (not shown). Reference numeral 11 denotes a conveying roller which nips with the conveying roller 10. Reference numeral 12 denotes a conveying roller which moves the conveying roller 11 toward the conveying roller 10. Reference numeral 13 denotes a roller spring for applying pressure, and an upper surface guide 13 guides the upper surface of the conveyed sheet.

Reference numeral 14 denotes an auxiliary pad for preventing double feeding of thin sheets, reference numeral 37 denotes an auxiliary pad holder for holding the auxiliary pad 14, and reference numeral 38 denotes a gear portion integrally formed with the auxiliary pad holder 37. , 39 are pivot axes of the auxiliary pad holder 37.

Reference numeral 40 denotes a gear C which meshes with the gear 38 to transmit the drive, 41 denotes a gear D formed integrally with the gear C40, and the gear C40 and the gear D41 denote step gears for reduction.

Reference numeral 42 denotes an auxiliary pad motor, which is a driving source controlled by a control unit (not shown). Reference numeral 43 denotes a top sensor flag which can be rotated by being pushed by the leading end of a fed sheet. Reference numeral 44 denotes a top sensor. The flag 43 indicates “O
The top sensor is set to “N / OFF”, and is set to “ON” when the sheet does not touch the top sensor flag 43.

A substrate 45 holds the top sensor 44. Reference numeral 21 denotes a back exterior of an image forming apparatus using the sheet feeding apparatus.

FIG. 3 shows a state in which a thick sheet is fed and hits the top sensor flag 43. In the figure, S is a stacked sheet bundle, and Sf is the uppermost fed sheet.

In this figure, the top sensor is “OF”
F ".

FIG. 4 is an example of an algorithm used for the operation of the first embodiment.

Climit in FIG. 4 is a constant that determines the time during which monitoring and adjustment are continued.

Under the above configuration, the supply operation and the sheet stacking operation are the same as in the prior art.

Next, an auxiliary pad adjusting mechanism which is a characteristic configuration of the first embodiment will be described.

When the feeding operation is started and the feeding roller 8 is rotated, a frictional force is applied to the uppermost sheet Sf, and the sheet starts to move forward.

However, the seat is strong and the auxiliary pad 1
When the resistance force due to the frictional force of No. 4 is very high, the sheet stops when it hits the auxiliary pad 14.

Even if a predetermined time in design has passed, the leading edge of the sheet does not hit the top sensor flag 43 and the top sensor 4
4 does not detect the leading edge of the sheet, the control shown in the flowchart of FIG. 4 is performed.

This control is performed until the leading edge of the sheet is detected.
By rotating the auxiliary pad motor 42 little by little, the gear D4
1. The gear C40 is rotated, the gear 38 formed integrally with the auxiliary pad holder 37 is driven, and the auxiliary pad 14 is gradually moved in the direction of being retracted from the insertion surface. In the process, the top sensor 44 detects the arrival of the sheet. At this point, the auxiliary pad motor 42 is stopped.

The timing for performing this control may be every supply, or only when the power is turned on and when a sheet bundle is newly set.

Therefore, by adopting the above configuration,
Since the auxiliary pad 14 is attached to a mechanism capable of automatically adjusting the degree of contact of the auxiliary pad 14 with the sheet, the double feed blocking force of the auxiliary pad 14 is reduced when a thick sheet is inserted and increased when a thin sheet is inserted. It becomes possible.

Further, since the auxiliary pad is set in accordance with the type and situation of the sheet to be actually used, it is possible to eliminate a supply jam caused by the state of the sheet in the market.

In the first embodiment, the stepless adjustment mechanism for the auxiliary pad is shown. However, the same effect can be obtained with a step adjustment mechanism having two or more steps.

(Second Embodiment) FIG. 5 is a cross-sectional view of a principal part showing the features of the second embodiment, and is provided with an auxiliary pad releasing mechanism using a link mechanism.

Since other structures and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

In FIG. 5, reference numeral 1 denotes a width regulating plate a as width regulating means for determining the position of the sheet in the width direction by abutting the sheet bundle in the width direction. Although not shown, a symmetrical width regulating plate b is also provided on the near side in the sectional view, and presses both side surfaces of the sheet bundle.

Reference numeral 2 denotes a supply tray for holding the width regulating plates. Reference numerals 3a and 3b denote racks a and b to which the width regulating plates are joined. Rack a is a width regulating plate a1 and rack b is a width regulating plate b.
Is combined with

Reference numeral 4 denotes a pinion engaged with both the racks a and b, and reference numeral 15 denotes an auxiliary pad holder for fixing the auxiliary pad 14.

The auxiliary pad holder 15 can be moved linearly by the supply frame 5, is held in a form that cannot be pulled out, and is also positioned when pressed to the sheet insertion surface side most.

A part of the auxiliary pad holder 15 has an abutting part 15a.

Reference numeral 5 a denotes a positioning portion of the auxiliary pad holder 15, which is a part of the supply frame 5.

Reference numeral 16 denotes an auxiliary pad switching cam.
In the auxiliary pad use mode, the holding portion 16a, which abuts against the butting portion 15a and supports it, and the joint portion 16b, which is an input portion of the operating force, are integrally held.

Reference numeral 17 denotes an operation rod, which integrally holds an operation section 17a operated by a user.

Reference numeral 18 denotes a rod shaft that rotatably supports the operation rod 17, 19 denotes a connection pin that connects the operation rod 17 and a joint portion of the auxiliary pad switching cam 16, and 20 denotes a hole formed in the supply frame. Reference numeral 21 denotes a rear exterior of the image forming apparatus using the sheet feeding apparatus, and reference numeral 22 denotes a top exterior.

FIG. 6 is a schematic sectional view showing a situation when the operation unit 17a according to the second embodiment is operated.

Reference numeral 5b denotes a stopper claw for holding the auxiliary pad holder 15 so as not to come off, and is a part of the supply frame 5.

Under the above configuration, the feeding operation and the sheet stacking operation are the same as in the prior art.

Here, an auxiliary pad releasing mechanism which is a characteristic configuration of the second embodiment will be described.

FIG. 5 shows a situation in which the user has selected to use the auxiliary pad 14 and operated the operation unit 17a.

At this time, the operating rod 17 is moved rightward in the drawing, and this operation causes the joint 16b linked by the connecting pin 19 to rotate leftward.

At this time, the auxiliary pad switching cam 16
It rotates counterclockwise in the figure around the feed shaft 9.

As a result, the holding portion 16a also moves, and moves to a position where it comes into contact with the butting portion 15a.

In this state, the auxiliary pad holder 15 is positioned on the abutment surface 5a of the supply frame 5, and the auxiliary pad 14 projects on the insertion surface.

FIG. 6 shows a situation in which the user selects not to use the auxiliary pad 14 and operates the operation unit 17a.

At this time, the operating rod 17 is moved to the left in the drawing, and by this operation, the joint portion 16b linked by the connecting pin 19 rotates to the right.

At this time, the auxiliary pad switching cam 16
It rotates clockwise around the feed shaft 9 in the figure.

As a result, the holding portion 16a also moves, and moves to a position where it does not come into contact with the butting portion 15a.

In this state, the auxiliary pad holder 15 moves in a direction away from the sheet passing surface until the auxiliary pad holder 15 is caught by the stopper claw 5b of the supply frame 5, and as a result, the auxiliary pad 14 waits outside the insertion surface.

The user operates the auxiliary pad releasing mechanism to release the auxiliary pad by the user's operation to prevent a supply jam and to feed a thin sheet. Can use the auxiliary pad to prevent double feeding, thereby realizing a wide and stable supply performance.

Further, it is possible to prevent the abrasion of the auxiliary pad due to a large amount of insertion of a thick sheet or the like, and as a result, the life of the auxiliary pad preventing double feed can be extended.

Although the second embodiment has been described using an auxiliary pad releasing mechanism using a link mechanism, the auxiliary pad can be released by other mechanisms and means.

In the second embodiment, the auxiliary pad 1
Although 4 is completely retracted from the sheet insertion surface, a mechanism for reducing the resistance generated by the auxiliary pad 14 by reducing the amount of protrusion of the auxiliary pad 14 may be used.

(Third Embodiment) FIG. 7 is a sectional view of a main part of a sheet feeding apparatus according to a third embodiment, and shows a situation when a wide sheet is inserted.

In the third embodiment, an auxiliary pad releasing mechanism is provided which is interlocked with width regulating means using a rack and pinion and a gear drive system.

The other configuration and operation are the same as those of the first embodiment, and therefore, the same components will be denoted by the same reference characters and description thereof will be omitted.

In FIG. 7, reference numeral 23 denotes a double rack having another rack in addition to the rack that meshes with the pinion 4, reference numeral 24a denotes a bevel pinion that meshes with the double rack 23, and reference numeral 24 denotes an integral part of the gear pinion 24a. The transmission shaft 24b is a gear A integrated with the transmission shaft 24.

25a and 25b are bearings a and b which rotatably support the transmission shaft 24, 26 is a gear B which meshes with the gear A and decelerates, and 27 is a gear which meshes with the small diameter side gear of the gear B26. It is an auxiliary pad support plate for holding the rack.

Reference numeral 28 denotes a pin for positioning the auxiliary pad support plate 27 so as to be able to move linearly. Reference numeral 29 denotes a holding plate that holds 26 to 28; 30 denotes an auxiliary pad holder B that holds the auxiliary pad 14; Denotes an abutting portion of the auxiliary pad holder B30, and 31 denotes a holding plate 2
9 is a screw connecting the supply frame 9 to the supply frame 5.

Reference numeral 32 denotes a feed roller collar for holding the feed roller 8, and reference numeral 33 denotes a P roller for determining the position of a separation pad (not shown).

FIG. 9 is a conceptual diagram of the third embodiment.
This shows a situation where an auxiliary pad having a large sheet width is used.

FIG. 8 is a schematic sectional view of the third embodiment, showing a situation where an auxiliary pad for inserting a thin sheet having a small width is not used.

FIG. 10 is a similar conceptual view showing the state of the auxiliary pad and the auxiliary pad support plate 27 in the case of a thick sheet having a small sheet width.

Under the above configuration, switching of the auxiliary pad 14 is performed as follows.

By operating the width regulating plates 1 and 1a to match the width of the sheet to be used, the double rack 23 moves in the vertical direction in FIG. 7 and in the horizontal direction in FIG.

At this time, the bevel pinion 24a also moves together, and the transmission shaft 24 also rotates. This torque is applied to the gear A24b and the gear B
26, the auxiliary pad support plate 27 is transmitted to the rack of the auxiliary pad support plate 27.
In FIG. 9, it moves left and right.

As described above, FIGS. 7 and 9 show a situation where the width regulating plates 1 and 1a are operated in accordance with a sheet having a large width.
The auxiliary pad supporting portion pushes up the abutting portion 30a of the auxiliary pad holder B30 in the sheet insertion direction, and the auxiliary pad 14 projects on the sheet insertion surface.

FIGS. 8 and 10 show a situation in which the width regulating plates 1 and 1a are operated in accordance with a thick sheet having a small width. In this case, the auxiliary pad supporting portion of the auxiliary pad supporting plate 27 is The butting portion 30a is pressed at such a height that the pad holder B30 does not protrude from the sheet insertion surface.

Therefore, the auxiliary pad 14 is located at a position where it escapes outside the sheet insertion surface.

With the above structure, the auxiliary pad is released without fail when a sheet having a small width and a strong stiffness, such as a postcard or an envelope, which is generally considered to be inserted by a general user as a thick sheet, is flown. It is possible to reliably improve the performance of feeding postcards and envelopes.

Further, since there is no need to operate the mechanism and the auxiliary pad can be released only by the conventional sheet width adjusting operation, a sheet feeding apparatus which is easy for the user to handle and has little postcard and envelope jam can be realized.

Although the third embodiment has been described using the auxiliary pad releasing mechanism using a rack and pinion and a gear drive system, for example, a rack having a cam is used instead of the double rack 23. The function of the third embodiment can be realized by another mechanism such as releasing the auxiliary pad using a rotating arm or the like.

(Fourth Embodiment) FIG. 11 is a schematic sectional view of a sheet feeding apparatus according to a fourth embodiment.

In the fourth embodiment, the auxiliary pad is urged toward the feed roller.

Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

In FIG. 11, reference numeral 34 denotes an auxiliary pad holder C according to the fourth embodiment, and reference numeral 34a denotes a holder shaft integrated with the auxiliary pad holder C34. It is pivotally supported.

Reference numeral 35 denotes an auxiliary pad pressurizing spring, and reference numeral 36 denotes an abutment surface provided on the supply frame 5, which is used for positioning the auxiliary pad holder C34 with respect to the sheet insertion surface.

The auxiliary pad pressure spring 35 presses the auxiliary pad holder C34 against the abutment surface 36 against the feed roller with a predetermined force F.

Under the above configuration, the release of the auxiliary pad 14 is performed as follows.

A normal sheet or the like that is routinely used for image formation has a weaker stiffness, so that even if the sheet is fed and collides with the auxiliary pad 14, only a pressing force smaller than F is generated.

Therefore, the auxiliary pad holder C34 does not move while being in contact with the contact surface 35.

On the other hand, when a stiff sheet such as a thick sheet, postcard, envelope, or the like is fed, the auxiliary pad 1
4, a strong pressing force is generated, and this force exceeds F, so that the auxiliary pad holder C <b> 34 is pressed down with the holder shaft 34 a as the center of rotation.

As a result, the auxiliary pad 14 is parallel to the sheet insertion surface, and the frictional force against the thick sheet is minimized.

With the above configuration, the frictional force of the auxiliary pad varies in the direction of optimization depending on the sheet being fed.

For example, when a thin sheet is inserted, the auxiliary pad applies a frictional force to prevent double feeding, and a thick sheet can apply a minimum frictional force to prevent a jam.

In addition, since the auxiliary pad is released as needed in all sheet widths, good supply performance can be realized in a wider range of sheet types without user operation.

Although the fourth embodiment uses a coil spring as the urging means, it is obvious that a similar effect can be obtained by using a leaf spring, a torsion coil spring, or the like.

[0131]

According to the present invention, the auxiliary pad can be moved in the direction away from the sheet insertion surface, and the position of the auxiliary pad can be switched according to the thickness of the sheet. It moves away from and retracts and does not apply resistance to the sheet, so the sheet is prevented from being damaged due to excessive resistance when the leading edge of the sheet hits the auxiliary pad, or a jam is prevented, and by retracting,
The wear of the auxiliary pad can be reduced, and the reliability can be improved.

When the auxiliary pad is not used, if the auxiliary pad is evacuated to a position where it does not come into contact with the sheet, contact with the sheet when a thick sheet or the like is inserted can be avoided, and the sheet may be damaged or jammed. , And abrasion of the auxiliary pad can be reduced.

A width regulating means for regulating the sheet size width is provided. When the auxiliary pad is interlocked with the movement of the width regulating means, the auxiliary pad can be switched by the sheet size width switching by the width regulating means. it can.

When the auxiliary pad is urged toward the feed roller by the urging means, the auxiliary pad also moves in accordance with the resistance force generated by the sheet, and the sheet is automatically fed according to the thickness of the inserted sheet. It becomes possible and improves work efficiency.

The image forming apparatus of the present invention includes the above-described sheet feeding apparatus and an image forming section for forming an image on a sheet fed from the sheet feeding apparatus. In addition, it is possible to reduce the occurrence of tip scratches and jams in thick sheet types.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an image forming apparatus according to a first embodiment.

FIG. 2 is a cross-sectional view illustrating a main part of the sheet feeding apparatus according to the first embodiment.

FIG. 3 is a cross-sectional view illustrating a main part of the sheet feeding apparatus according to the first embodiment when sheets are stacked;

FIG. 4 is a flowchart illustrating an algorithm used for the operation of the sheet feeding apparatus according to the first embodiment.

FIG. 5 is a cross-sectional view of a main part showing a case where an auxiliary pad of a sheet feeding device according to a second embodiment is used.

FIG. 6 is a cross-sectional view illustrating a main part of the sheet feeding device according to the second embodiment when an auxiliary pad is not used.

FIG. 7 is a cross-sectional view of a main part showing a case where an auxiliary pad of a sheet feeding device according to a third embodiment is used.

FIG. 8 is a cross-sectional view illustrating a main part of the sheet feeding device according to a third embodiment when an auxiliary pad is not used.

FIG. 9 is a conceptual diagram showing a case where an auxiliary pad of a sheet feeding device according to a third embodiment is used.

FIG. 10 is a conceptual diagram showing a case where an auxiliary pad of a sheet feeding device according to a third embodiment is not used.

FIG. 11 is a cross-sectional view illustrating a main part of a sheet feeding apparatus according to a fourth embodiment.

FIG. 12 is a cross-sectional view of a main part showing a sheet feeding apparatus according to the related art.

FIG. 13 is a cross-sectional view of a principal part showing another cross section of FIG. 12 of the sheet feeding apparatus according to the related art.

[Explanation of symbols]

 Reference Signs List 6 middle plate 8 feed roller 9 feed shaft 10 transfer roller 11 transfer roller 14 auxiliary pad 15 auxiliary pad holder 16 auxiliary pad switching cam 17 operation rod 20 supply frame hole 23 double rack 24 transmission shaft 27 auxiliary pad support plate 30 auxiliary Pad holder B 32 Feed roller collar 33 P roller 34 Auxiliary pad holder C 35 Auxiliary pad pressure spring 36 Abutment surface 37 Auxiliary pad holder 38 Gear 39 Rotating shaft 40 Gear C 41 Gear D 42 Auxiliary pad motor 43 Top sensor flag 44 Top Sensor

Claims (5)

[Claims] 1. A feeding roller for feeding a sheet, a separation pad urged toward the feeding roller, and a tip of a plurality of sheets fed to the feeding roller before the separation pad. An auxiliary pad for applying a resistance force, wherein the auxiliary pad and the separation pad separate and feed only one sheet from a plurality of sheets fed to the feed roller by the separation pad. The sheet feeding device, wherein the auxiliary pad is movable in a direction away from the sheet insertion surface, and the position can be switched and set according to the thickness of the sheet. 2. The sheet feeding device according to claim 1, wherein when the auxiliary pad is not used, the auxiliary pad is retracted to a position where the auxiliary pad does not contact the sheet. 3. The sheet feeding device according to claim 1, further comprising a width regulating unit that regulates a sheet size width, wherein the auxiliary pad is interlocked with a movement operation of the width regulating unit. 4. The sheet feeding device according to claim 1, wherein the auxiliary pad is urged toward a feeding roller by an urging means. 5. A sheet feeding device according to claim 1, further comprising: an image forming section for forming an image on a sheet fed from the sheet feeding device. Image forming apparatus.