JP2003048638A - Cassette and sheet feeder and image forming device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cassette and a sheet feeder offering simple construction permitting sheets to be stably fed, independently of the rigidity of the sheets, and an image forming device equipped therewith. SOLUTION: A separating plate 4 constituting a separating slope is turnably provided at the end of sheet storage means 2 in a sheet feeding direction, the separating plate 4 being turnable in abutment with the sheets S delivered by sheet feeding means 3. The sheets S delivered by the sheet feeding means 3 are separated one by one by the separating plate 4, before fed. The separating plate 4 is energized in opposition to the sheet feeding direction by energizing means, and the separating plate 4 is held to abut on the sheets delivered by the sheet feeding means 3 in certain attitude. Furthermore, the energizing force of the energizing means 22 on the separating plate 3 is adjusted corresponding to the rigidity of the sheets S by energizing force adjusting means 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette, a sheet feeding device, and an image forming apparatus having the same, and more particularly to a structure of a separating unit for separating sheets one by one.

[0002]

2. Description of the Related Art Conventional image forming apparatuses such as printers and copying machines are equipped with a sheet feeding device for feeding sheets to an image forming section. As such a sheet feeding device, for example, there is one in which the sheets stacked in the sheet storing means are fed out by the sheet feeding means, and then separated one by one by the separation slope and fed.

Here, FIG. 8 is a diagram showing an example of such a conventional sheet feeding device, and in the figure, 100 is a sheet feeding device. The sheet feeding device 100 is attachable to and detachable from the sheet feeding device and stores a sheet S in a substantially horizontal state.
And a sheet feeding roller 107 having a cutout 107a as a feeding means for feeding the sheets S stored in the cassette 101 to the image forming unit (not shown) in order from the uppermost sheet. There is.

In this cassette, a tray 104 on which the sheets S are stacked in a substantially horizontal state, and the tray 10 are provided.
4 and tray arms 102 and 103 combined in a pantograph shape for raising and lowering while keeping them substantially horizontal, and tray 1.
A push-up spring 105 for urging 04 upward is provided. As shown in FIG. 9, two tray arms 102 and 103 are provided at both ends in the sheet width direction which is a direction orthogonal to the sheet feeding direction (feeding direction).

Further, at the front end side of the cassette 101, when the sheet S is sent out, it is pressed by the sheet S and is inclined, thereby forming a separation plate for separating the sheets S stacked on the tray. 120 is the cassette 10
It is rotatably attached to a separation guide plate 121 which is fixed to the sheet feeding direction side end of the sheet 1.

When the separation plate 120 is inclined, the sheet contact surface, which is a separation slope, has a plurality of ribs 1 arranged at predetermined intervals in the sheet width direction as shown in FIG.
It is composed of 20a. Also, this separation plate 120
And the separation guide plate 121, the separation plate 120 is biased and pressed against a stopper (not shown) to hold the separation plate 120 in a substantially vertical state.
Is attached.

On the other hand, the paper feed roller 107 is the cassette 10
1 is fixed to a paper feed roller shaft 108 provided above Here, the drive from the transport roller shaft (not shown) is transmitted to the paper feed roller shaft 108 through a gear train (not shown), and thereby the paper feed roller 107 rotates clockwise in FIG. It is like this.

By the way, FIG. 8 shows a state at the time of feeding standby. At this time, the paper feed roller 107 has the notch 107a at a position facing the sheet S, and the tray arm 10 combined in a pantograph shape.
The tray shaft 110, which is the center of rotation of 2, 103, is the tray cam 1.
It is pressed downward by the cam portion 109a of 09. As a result, the sheets S stacked on the tray are held in a state of being separated from the sheet feeding roller 107.

When a sheet feed start command is input in this state, the sheet feed roller 107 in the state shown in FIG. 8 starts rotating, and the tray roller cam is driven by the sheet feed roller 107 via a gear train (not shown). Then, the tray cam 109 rotates in synchronization with the paper feed roller 107.

When the tray cam 109 is rotated in this way, the pressing by the cam portion 109a that is holding the tray shaft 110 so as not to rise is released, and the push-up spring 105 causes the tray 104 to rise and the tray 104 to move to the tray 104. The stacked sheets S are pressed against the paper feed roller 107. Then, when the sheet S is pressed against the sheet feeding roller 107 in this way, the uppermost sheet S stacked on the tray is rotated by the rotation of the sheet feeding roller 107.
Are sent out by the frictional force of the paper feed roller 107.

By the way, when the sheet S is further sent out by the sheet feeding roller 107 thereafter, the sheet S is urged by the separating plate spring 122 and abuts on the separating plate 120 which is held in a substantially vertical state, The separating plate 120 is pressed in the sheet feeding direction.

When the sheet S is pressed by the sheet S in this manner, the separating plate 120 falls down to some extent according to the rigidity of the sheet S. Here, since the separating plate spring 122 has a preset spring force (constant), if the separating plate 120 is tilted in this way, the force for returning the separating plate 120 to the substantially vertical direction becomes strong.

For this reason, after that, it is further sent out to
The sheet S of the first sheet is bent while tilting the separation plate 120, and as a result, the force pressing the separation plate 120 is increased.
When it becomes smaller than the force to return 20 to the original state,
The separation plate 120 tries to return to the original state by the urging force of the separation plate spring 122, and as a result, the first sheet S1 obliquely goes upward as shown in FIG. Like

When the separating plate 120 is going to return to its original state in this way, as shown in the figure, the separating plate 120 is fed to the first sheet S1 of the second and subsequent sheets S2. It will collide with the tip. Here, since the second and subsequent sheets S2 are not in direct contact with the sheet feeding roller 107, they do not have a feeding force enough to get over the separation plate 120, and therefore do not get over the separation plate 120. It is pushed back to the separation plate 120 and loaded on the tray 104.

Note that FIG. 11 shows a state in which a sheet S having a low rigidity is fed, and in this case, the separation plate 120 does not fall over a sheet having a high rigidity, and the first sheet S1 and the second sheet S1 do not fall. The sheet S2 after the eyes can be separated.

The separating plate 12 having the above-mentioned structure
0 and the separating portion including the separating leaf spring 122 causes the sheet S
After 1 is separated and sent out, the paper feed roller 107
When it rotates, the tray cam 109 also makes one rotation and the tray shaft 1 rotates.
Since the tray 10 and the sheet S are pushed down, the tray 104 and the sheet S are separated from the paper feed roller 107 again, and the standby state is set.

[0017]

However, in the conventional sheet feeding device having the separating portion having such a structure, when separating a sheet having high rigidity such as a thick sheet, the urging force of the separating plate 120 is applied. Needs to be larger,
When the urging force of the separating plate 120 is increased in this way, the conveyance load when getting over the separating plate 120 becomes large, which is likely to cause a defective sheet feeding.

Therefore, if the biasing force of the separating plate 120 is reduced to reduce the feeding load so as to eliminate such a defective feeding, the sheet S having a low rigidity such as a thin sheet is fed. Since it is easy to get over the separation plate 120, a plurality of sheets are easily conveyed at the same time, which causes double feeding.

Since the urging force of the separating plate 120 is due to the separating plate spring 122, the type of sheets that can be separated is determined by the spring constant of the separating plate spring 122. That is, the type of sheets that can be separated is determined by the spring constant of the separation leaf spring 122.

However, in recent years, the types of sheets used in the image forming apparatus have been diversified, and the range of rigidity of the sheets used has been widened accordingly. When the range of the rigidity of the sheet to be used is widened in this way, the sheet cannot be separated by the separation plate 120 depending on the rigidity of the sheet, resulting in double feeding or defective feeding. There is.

Therefore, the present invention has been made in view of the above circumstances, and is provided with a cassette and a sheet feeding device which are capable of stably feeding sheets regardless of the rigidity of the sheets with a simple structure, and the same. An image forming apparatus is provided.

[0022]

SUMMARY OF THE INVENTION The present invention relates to a sheet feeding device in which sheets stacked in a sheet storing means are fed by a sheet feeding means and then separated one by one by a separating slope. A separation plate, which is rotatably provided at an end portion of the sheet storage means on the side of the sheet feeding direction, abuts against the sheet fed by the sheet feeding means, and rotates to form the separation slope; Urging means for urging the plate in a direction opposite to the sheet feeding direction and holding the separating plate so as to abut on the sheet fed by the sheet feeding means in a fixed posture; and the separation of the urging means. And a biasing force adjusting means for adjusting the biasing force to the plate to a magnitude corresponding to the rigidity of the seat.

The present invention further comprises a holding member which holds one end of the biasing means and is provided so as to be able to approach or separate from the separating plate, and the biasing force adjusting means is the biasing means. The holding member is moved to a position where the urging force of the urging means becomes a magnitude corresponding to the rigidity of the seat, and the urging force of the urging means is adjusted.

Further, according to the present invention, the urging force adjusting means moves the holding member by manual operation to a position where the urging force of the urging means has a magnitude corresponding to the rigidity of the seat. It is a feature.

Further, according to the present invention, the urging force adjusting means is driven by the driving means to move the holding member to a position such that the urging force of the urging means has a magnitude corresponding to the rigidity of the seat. It is characterized by being.

The present invention is also characterized in that the driving means is a stepping motor.

Further, the present invention is characterized in that the biasing force adjusting means moves the holding member to a position corresponding to the rigidity of the seat via a cam member.

Further, according to the present invention, in an image forming apparatus provided with an image forming section and a sheet feeding apparatus for feeding a sheet to the image forming section, the sheet feeding apparatus is any one of the above. It is what Further, according to the present invention, in a cassette, a separating means is provided rotatably at an end portion on a sheet feeding direction side of a main body, and comes into contact with a sheet fed by a sheet feeding means to rotate to form a separation slope. Urging means for urging the separating means in a direction opposite to the sheet feeding direction, and holding the separating means so as to contact the sheet fed by the sheet feeding means in a fixed posture, and the urging means. And an urging force adjusting means for adjusting the urging force to the separating means to a magnitude according to the rigidity of the seat.

Further, the present invention is characterized by comprising manual operation means for moving the urging force of the urging means to a position such that the urging force has a magnitude corresponding to the rigidity of the seat.

Further, the present invention is an image forming apparatus comprising an image forming section and a sheet feeding means for feeding the sheets stacked in the cassette to the image forming section, wherein the cassette is any one of the above. It is characterized by

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a schematic construction of an ink jet printer which is an example of an image forming apparatus provided with a sheet feeding device according to a first embodiment of the present invention.

In the figure, reference numeral 200 is an ink jet printer, and this ink jet printer 200 is
The image forming unit 201 and the sheet S on the image forming unit 201.
Sheets are separated and fed one by one, and the sheet storing means, for example, the cassette 2, and the sheet feeding means for feeding the sheets stacked and stored in the cassette 2, for example, the cutout portion 3a.
And a sheet feeding device 15 having a separating plate 4 or the like as separating means for separating the sheet S fed by the sheet feeding roller 3.

Here, the image forming unit 201 is arranged in parallel in the sheet conveying direction indicated by an arrow, and a head row 204 in which a large number of ink jet heads 204a are arranged in a direction orthogonal to the sheet conveying direction, and a sheet feeding device 15. And a conveyance belt 213 for placing the sheet S conveyed by the above and passing below the head row 204.

The conveyor belt 213 is connected to the drive shaft 2
12, the driven pulley 215, and the drive pulley 220, and the drive pulley 220 is driven to rotate by the drive motor 219 to make a circular movement in the sheet conveying direction.

Next, the image forming operation of the ink jet printer 1 thus constructed will be described.

When the sheet feeding operation is started, the uppermost sheet S1 of the sheets S stored in the cassette 2 detachably attached to the ink jet printer 200 is first sent out by the sheet feeding roller 3 and then the cassette S1. The sheets are separated one by one by a separation plate 4 provided at the end of the main body 2A in the sheet feeding direction. Then, after this, the sheets S1 separated one by one are, for example, the roller unit 20 as skew feeding correction means.
After the skew feeding correction is performed by 6, the sheet is curled by the roller unit 207 as a curling unit and conveyed to the image forming unit 201.

Next, the sheet S conveyed to the image forming section 201 in this manner is placed on the conveyance belt in a state of being pressed by the front pinch roller 216, the pinch roller 217 and the spur unit 214, and this conveyance is carried out. The belt 213 passes under each head row 204 by the revolving movement of the belt 213.

When the sheet S1 passes under each head row 204 in this way, a control device (not shown) controls the ink jet heads 204a of each head row 204 to cause the ink to project, so that the surface of the sheet S1 is exposed. Form an image. In addition, after the image is formed on the surface of the sheet S1 in this manner, the sheet S1 is moved to the apparatus main body 20 by the paper ejection spur 218.
The paper is discharged onto the paper discharge tray 221 provided on the side wall surface of 0A.

By the way, FIG. 2 is a diagram showing the structure of the sheet feeding device 15. As shown in FIG. 2, the sheet feeding device 15 can move up and down to the cassette 2, the sheet feeding roller 3, the separating plate 4 and the cassette 2. The sheet stacking tray 11 is a sheet stacking member provided on the sheet stacking member, and the sheet stacking member elevating means for elevating the sheet stacking tray 11 includes, for example, an elevating mechanism 12.

Here, the elevating mechanism 12 includes the first and second frames 1 projectingly provided on the lower surface of the sheet placing tray 11.
1a and 11b, third and fourth frames 1a and 1b that are provided to project from the bottom surface of the cassette 2 and are parallel to the first and second frames 11a and 11b, and the first and the same lengths that intersect at the center. At least a pair of link mechanisms 14 including the second tray arms 5 and 6 are provided.

It should be noted that one end 6a of the second tray arm 6 is rotatably supported by the first frame 11a, and the other end 6b is provided at the other end 6b via a shaft (not shown) projecting from the fourth frame 1.
While being slidably held in a slide groove 1c formed in b, one end 5a of the first tray arm 5 is rotatably supported by the third frame 1a, and the other end 5b is projectingly provided at the other end 5b. It is slidably held in a slide groove 11c formed in the second frame 11b via a shaft (not shown).

By the way, in the present embodiment, the link mechanism 14 having such a structure is provided at both ends in the sheet width direction between the cassette 2 and the sheet loading tray 11, as shown in FIG. ing.

The pair of link mechanisms 14 are connected by a shaft (hereinafter referred to as a through shaft) 8 which is a connecting member penetrating the rotation centers of the first and second tray arms 5, 6. When the shaft 8 is moved in the vertical direction, the first and second tray arms 5 and 6 move into the slide grooves 1c and 11
Rotate while sliding laterally along c,
As a result, the sheet placing tray 11 can be raised and lowered while maintaining a horizontal (or substantially horizontal) state.

In FIG. 2, reference numeral 7 denotes a compression spring which is provided in each of the pair of link mechanisms 14 and urges the sheet loading tray 11. The compression spring 7 causes the sheet loading tray 11 to always move upward. Is urged by.
On the other hand, the tray cam moves the through shaft to oppose the compression spring.

Further, the lifting mechanism 12 is provided with, for example, a tray cam 9 as a moving means for moving the penetrating shaft 8 of the first and second tray arms 5 and 6 in the vertical direction. Then, by rotating the tray cam 9, the penetrating shaft 8 can be moved in the vertical direction, and by moving the penetrating shaft 8 in the vertical direction in this manner, the link mechanism 1
4 allows the sheet placing tray 11 to move up and down while maintaining the horizontal state.

Here, the tray cam 9 rotates in synchronization with the paper feed roller 3 by a drive system (not shown), and rotates once when the paper feed roller 3 makes one rotation. In addition,
The tray cam 9 is at the position shown in FIG. 4 until the sheet feeding operation is started. When the tray cam 9 is at this position, the penetrating shaft 8 is pushed down by the tray cam 9 and the sheet loading tray 11 is kept in the parallel state. It will be in a state of descending while keeping it. Then, at this time, the sheet S is separated from the sheet feeding roller 3. In this state, by stacking the sheets S, the sheets S can be easily stored.

On the other hand, when the paper feed roller 3 rotates, the tray cam 9 rotates in conjunction with this, and the penetrating shaft 8 is released from the tray cam 9. Therefore, the sheet loading tray 11 is moved by the compression spring 7 to a position where the sheet can be delivered. And the sheet S comes into contact with the sheet S as shown in FIG. When the paper feed roller 3 further sends out the sheet S and then the paper feed roller 3 further rotates, the tray cam 9 again pushes down the tray shaft 8 at a predetermined timing, and the sheet loading tray 11 is lowered. Has become.

Here, the separating plate 4 that comes into contact with the sheet S sent out by the sheet feeding roller 3 and separates the uppermost sheet S1 is a downstream side of the cassette 2 in the sheet sending-out direction as shown in FIG. 2 or 4. It is rotatably held on the upper end of a separation guide plate 21 provided at the end through a rotary shaft 25.

A separation plate spring holder 23, which is a holding member, is rotatably held on the separation guide plate 21 via a rotation shaft 25 as shown in FIG. And
Between the separation plate spring holder 23 and the separation plate 4, for example, a separation plate spring 22 is provided as a biasing means in a state where one end is held by the separation plate spring holder 23 and the other end is picked up by the separation plate spring holder 23. The separating plate spring 22 biases the separating plate 4 in a direction opposite to the sheet feeding direction.
The cassette 2 is provided with a stopper (not shown), and the stopper holds the separation plate 4 in a substantially vertical state.

In the figure, reference numeral 24 denotes, for example, a separating plate lever as an urging force adjusting means, and the separating plate lever 24 is rotatably supported by a frame (not shown) provided in the apparatus main body or the cassette 2. Separated plate cam shaft 27
Is stuck to. Further, the separation plate cam shaft 27 has
The separation leaf spring holder 23 is pressed to press the separation leaf spring holder 23.
A separating plate cam 26 is fixed as a cam member that moves and sets the position of the position S to a position corresponding to the rigidity of the sheet S.

Accordingly, when the separating plate lever 24 is rotated, the separating plate lever 24 is moved from the position shown in FIG. 4 to the position shown in FIG.
At the same time, the separation plate cam 26 rotates, and accordingly, the separation plate spring holder 23 rotates (moves) to a position corresponding to the rigidity of the sheet S. Here, when the position of the separation leaf spring holder 23 changes in this way, the separation leaf spring holder 2
The urging force of the separation plate 4 caused by the compression of the separation plate spring
The extension changes the size according to the rigidity of the sheet S.

In the present embodiment, when a sheet such as a thick sheet having a rigidity greater than a predetermined rigidity is fed, the separating plate lever 24 is operated to raise the separating plate spring holder 23. The separating plate spring 22 is compressed so that the separating plate spring 22 is compressed, the urging force of the separating plate spring on the separating plate 4 is increased, and a sheet having a rigidity larger than a predetermined rigidity is reliably separated. Will be able to. On the other hand, when feeding a sheet such as a thin sheet having a rigidity smaller than a predetermined rigidity, the separating plate lever 24 is operated counterclockwise (in the direction opposite to the arrow in the drawing) to lay the separating plate spring holder 23 to the side. So as to move away from the separating plate 4, so that the separating plate spring 22 expands,
The urging force of the separating plate spring on the separating plate 4 is reduced, and it becomes possible to reliably separate the sheet having a rigidity smaller than a predetermined rigidity.

Next, the sheet feeding operation of the sheet feeding device having the separating portion thus constructed will be described.

When the sheet feeding operation is started and the sheet feeding roller 3 is rotated in the clockwise direction accordingly, the sheet S is sent out by the sheet feeding roller 3, and the sheet S is urged by the separation leaf spring 22 to be separated. It abuts the plate 4 and presses the separating plate 4 in a substantially vertical state. As a result, the separation plate 4 falls horizontally while resisting the separation plate spring 22 to form a separation slope.

At this time, when the rigidity of the sheet S is large, the separation plate 4 is largely collapsed. Here, since the separating plate spring 22 has a preset spring constant, if it falls down in the horizontal direction, the force for returning the separating plate 4 in the substantially vertical direction becomes strong.

For this reason, after this, it is sent further and
The sheet S of the first sheet is bent while tilting the separation plate 4, and thereafter, when the force for pressing the separation plate 4 becomes smaller than the force for returning the separation plate 4 to the original state, the separation plate 4 is separated. The urging force of the leaf spring 22 tries to return to the original state, which causes the first sheet S1 to move diagonally upward (see FIG.
(See 0), the sheet is fed over the separating plate 4.

When the leading edge of the sheet S passes through the separating plate 4 in this manner, the separating plate 4 tries to return to its original state by the urging force of the separating plate spring 22. Then, when the separating plate 4 tries to return to the predetermined angle in this way, it comes into collision with the leading ends of the second and subsequent sheets fed to the first sheet S.

Here, since the second and subsequent sheets are not in direct contact with the paper feed roller 3, it is not possible to obtain the feeding force for overcoming the separating plate 4, and therefore the separating plate 4 cannot be overridden. As a result, the sheet is pushed back to the separating plate 4 and stacked on the sheet placing tray 11. After this,
Since the tray cam 9 pushes down the penetrating shaft 8 again while the paper feed roller 3 makes one rotation, the tray 11 is lowered.

When sending out a sheet having a low rigidity such as a thin sheet, the separating plate 4 does not fall in the horizontal direction as much as a sheet having a high rigidity, and the first sheet S and the second and subsequent sheets S are positioned at a position where the separating plate 4 does not collapse. Can be separated.

By the way, for example, when separating a sheet having rigidity such that the sheet S cannot be reliably separated within the range of the preset spring constant of the separating plate spring 22, the separating plate lever 24 is used. Figure 2 by hand
The rotation operation is performed in the direction of arrow A. By rotating the separation plate lever 24 in this manner, the separation plate cam shaft 27 rotates, and the separation plate cam 26 fixed to the separation plate cam shaft 27 rotates accordingly.

When the separating plate cam 26 rotates in this manner, the separating plate cam 26 presses the separating plate spring holder 23 to rotate to the separating plate side as shown in FIG.
As a result, the separating plate spring 22 is compressed, and the urging force on the separating plate 4 increases. By increasing the urging force on the separating plate 4 in this way, even a sheet having high rigidity that cannot be separated by the preset spring constant of the separating plate spring 22 can be reliably separated by the separating plate 4.

As described above, the position of the separating plate spring holder 23 is changed by operating the separating plate lever 24, and the urging force of the separating plate spring 22 with respect to the separating plate 4 is changed. The size can be set according to the rigidity of S, and thus stable feeding can be performed regardless of the rigidity of the sheet S. Further, by enabling stable separation and feeding of the sheet S with such a simple configuration, not only the number of parts can be reduced, but also reliability can be secured and the price can be suppressed. be able to.

In the present embodiment, the position of the separating plate spring holder 23 can be switched in two steps depending on the shape of the separating plate cam 26. However, by changing the shape of the separating plate cam 26, etc. Many switches are possible. Thereby, the biasing force of the separating plate spring 22 with respect to the separating plate 4 can be set more finely.

By the way, in the above description, the case where the separating plate lever 24 is manually operated to change the position of the separating plate spring holder 23 has been described, but the present invention is not limited to this, and the separating plate spring holder 23 is separated by a motor or the like. By driving the plate cam shaft 27 and automatically changing the position of the separating plate spring holder 23, the urging force of the separating plate spring 22 against the separating plate 4 is changed to a magnitude corresponding to the rigidity of the sheet S. May be.

Next, the second embodiment according to the present invention will be described.

FIG. 6 is a diagram showing a schematic structure of the sheet feeding device according to the present embodiment, and FIG. 7 is a plan view thereof. In the figure, the same reference numerals as those in FIGS. 2 and 3 indicate the same or corresponding portions.

In the figure, reference numeral 302 denotes a driving means, which is constituted by a stepping motor (not shown), for example. Thirty
A worm gear unit 3 is rotated by a stepping motor 302. This worm gear unit 30
The rotation of 3 is transmitted to the separation plate spring holder 23 via the separation plate cam shaft 27 and the separation plate cam 26, whereby the position of the separation plate spring holder 23 is changed. The stepping motor 302 is driven according to the rigidity of the sheet selected by a printer driver of a PC (not shown).

For example, when feeding a sheet having a rigidity higher than a predetermined rigidity, the stepping motor 3 is adjusted according to the rigidity of the sheet selected by the printer driver of the PC.
02 is driven by a predetermined amount. By driving the stepping motor 302 by a predetermined amount in this way, the worm gear unit 303, the separation plate cam shaft 27, and the separation plate cam 26 are driven, and the separation plate spring holder 23 rotates to the separation plate side. As a result, the separating plate spring 22 is compressed, and the urging force on the separating plate 4 increases. If the control is reversed, the separating leaf spring 22 is stretched, the urging force is reduced, and it becomes suitable for feeding a sheet having low rigidity.

By increasing the urging force on the separating plate 4 in this way, it is possible to surely separate even the sheet having high rigidity which cannot be separated by the preset spring constant of the separating plate spring 22 by the separating plate 4. You can

[0071]

As described above, according to the present invention, the size of the urging force of the urging means for urging the separating plate can be easily adjusted by the urging force adjusting means according to the rigidity of the seat. With such a configuration, stable paper feeding can be performed regardless of the rigidity of the sheet.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an inkjet printer which is an example of an image forming apparatus including a sheet feeding device according to a first embodiment of the invention.

FIG. 2 is a side sectional view showing the configuration of the paper feeding device.

FIG. 3 is a plan view showing the configuration of the paper feeding device.

FIG. 4 is a diagram showing a state before the paper feeding operation of the paper feeding device is started.

FIG. 5 is a diagram showing a state in which a sheet having a high rigidity in a separation unit provided in the sheet feeding device is fed.

FIG. 6 is a diagram showing a schematic configuration of a paper feeding device according to a second embodiment of the invention.

FIG. 7 is a plan view showing the configuration of the paper feeding device.

FIG. 8 is a cross-sectional view showing the configuration of a conventional paper feeding device.

FIG. 9 is a plan view showing the configuration of the paper feeding device.

FIG. 10 is a detailed schematic diagram showing a state of separating and feeding a sheet having high rigidity in a conventional sheet feeding device.

FIG. 11 is a detailed schematic diagram showing a state of separating and feeding a sheet having low rigidity in a conventional sheet feeding device.

[Explanation of symbols]

2 cassettes 2A cassette body 3 paper feed rollers 4 separation plates 21 Separation guide plate 22 Separate leaf spring 23 Separate leaf spring holder 24 Separation plate lever 26 Separation plate cam 200 inkjet printer 201 Image forming unit 302 stepping motor 303 Worm gear unit S sheet

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Claims (10)

[Claims] 1. A sheet feeding device configured to feed sheets stacked in a sheet storing means by a sheet feeding means, and then separate and feed the sheets one by one by a separation slope, wherein the sheet feeding means of the sheet storing means A separation plate that is rotatably provided at the end on the side of the direction and that rotates by contacting the sheet sent out by the sheet feeding means and that constitutes the separation slope, and a separation plate that is opposite to the sheet sending direction. Urging means for urging the separating plate so that the separating plate abuts against the sheet delivered by the sheet feeding means in a constant posture, and the urging force of the urging means with respect to the separating plate of the sheet. A sheet feeding device comprising: an urging force adjusting unit that adjusts the size according to the rigidity. 2. A holding member which holds one end of the biasing means and is provided so as to be able to approach or separate from the separating plate, wherein the biasing force adjusting means is a biasing force of the biasing means. 2. The sheet feeding device according to claim 1, wherein the holding member is moved to a position where the sheet has a size corresponding to the rigidity of the sheet to adjust the urging force of the urging means. 3. The urging force adjusting means is configured to move the holding member by manual operation to a position where the urging force of the urging means has a magnitude corresponding to the rigidity of the seat. The sheet feeding device according to claim 2. 4. The urging force adjusting means is driven by a driving means to move the holding member to a position such that the urging force of the urging means has a magnitude corresponding to the rigidity of the seat. The sheet feeding device according to claim 2, wherein the sheet feeding device is a sheet feeding device. 5. The sheet feeding device according to claim 4, wherein the driving unit is a stepping motor. 6. The urging force adjusting means moves the holding member to a position corresponding to the rigidity of the seat via a cam member, according to any one of claims 2 to 5. The paper feeder described in. 7. An image forming apparatus comprising an image forming unit and a paper feeding device for feeding a sheet to the image forming unit, wherein the paper feeding device is the device according to any one of claims 1 to 6. An image forming apparatus characterized in that there is. 8. Separation means that is rotatably provided at an end portion of the main body in the sheet feeding direction and that rotates by contacting the sheet fed by the sheet feeding means and that constitutes the separation slope. Urging means for urging the means in a direction opposite to the sheet feeding direction and holding the separating means so as to contact the sheet fed by the sheet feeding means in a fixed posture, and the separating of the urging means. And a biasing force adjusting means for adjusting the biasing force to the means to a magnitude corresponding to the rigidity of the sheet. 9. The cassette according to claim 8, further comprising manual operation means for moving the urging force of the urging means to a position such that the urging force has a magnitude corresponding to the rigidity of the sheet. 10. An image forming apparatus, comprising: an image forming unit; and a sheet feeding unit for feeding the sheets stacked in the cassette to the image forming unit, wherein the cassette is any one of claims 8 to 9. An image forming apparatus, characterized in that