JP2002037478A - Sheet feeding device and image forming device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeding device capable of excellently delivering a sheet, even when a feeding means of a large diameter is used, and an image forming device provided with the same. SOLUTION: By making pressed contact pressure for pressing a separating means 241 in contact with a feeding means 28 as 1.08 N to 1.47 N, rubber hardness of foamed urethane for forming the separating means 241 as 80 deg. to 850 deg. and pressed contact pressure for pressing the sheet P in contact with the feeding means 28 as 1.27 N to 1.67 N, the sheet P loaded on a sheet loading means 21 at an angle of 40 deg. to 60 deg. with a horizontal direction can be excellently delivered, even when the feeding means 28 having a D-type shape obtained by cutting a part of a circle of ϕ 38 to 46 mm in cross section and a large diameter is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder and an image forming apparatus provided with the same, and more particularly to a structure in which sheets are separated and fed one by one.

[0002]

2. Description of the Related Art Conventionally, in image forming apparatuses such as printers, copiers and facsimile machines, in addition to plain paper, thick paper such as postcards and envelopes and special sheets such as thin plastic sheets are used as sheets. The sheet is conveyed to the forming unit by manually inserting sheets one by one or automatically and continuously fed by a sheet feeding device.

Here, in a conventional paper feeder, when a sheet is fed, a sheet is separated using a separation pad. FIG. 13 shows a paper feeder having such a configuration. There is something like that. In the figure,
Reference numeral 28 denotes a paper feed roller, on which a paper feed roller rubber 282 is attached.

[0004] The separation pad 241 and the pressure plate 21 urged at a predetermined pressure by the separation pad spring 242 are urged against the sheet feed roller 28, whereby the sheet stacked on the pressure plate 21 is pressed. A sheet material P
Is sent out by the paper feed roller 28 and then separated by the separation pad 241. Note that in FIG.
Reference numeral 13 denotes a separation sheet provided at the tip of the pressure plate 21.

By the way, when the sheet material P is separated in this manner, the next highest sheet material P1 is placed with respect to the next highest sheet material P1.
2 may be sent together with the uppermost sheet material P1 due to the action of static electricity and the action of frictional force. This sheet material P2 is separated from the sheet material P1 by the following action of the separation pad 241. As a result, , Only the uppermost sheet material P1 is fed.

That is, first, the leading edge of the sheet material P2 abuts against the separation pad 241, thereby inhibiting its movement, and is separated from the uppermost sheet material P1. Next, the frictional force between the sheet feeding roller rubber 282 and the sheet material P1 is f1, the frictional force between the sheet material P2 and the separation pad 241 is f2, and the frictional force between the sheet material P1 and the sheet material P2 is f1. Assuming that f3, the paper feed roller rubber 282 and the separation pad 2 are arranged such that a relationship of f1>f2> f3 is established.
41, the movement of the next sheet material P2 is hindered by the frictional force with the separation pad 241, and the next sheet material P2 is separated from the uppermost sheet material P1.

As a result, only the uppermost sheet material P1 is fed. Then, the sheet material thus fed is transferred to a not-shown conveying means of the image forming apparatus, and is further conveyed to the image forming unit.

In such a sheet feeding device, after the sheet material P is delivered to the image forming apparatus, the sheet feeding roller 28 is not driven, so that a large back tension is caused, and the conveyance accuracy of the sheet material P is reduced. I do. In addition,
For example, a clutch mechanism may be provided to cope with such back tension, but in this case, the configuration is complicated.

In order to cope with such back tension, a part of the peripheral surface of the paper feed roller 28 is cut out to make the shape of the paper feed roller 28 D-shaped so that the sheet material P
After the transfer, the paper feed roller 28 is separated from the pressure plate 21 and the separation pad 241 to reduce the back tension.

However, if the pressure plate 21 is inclined in order to reduce the installation area of the sheet feeding device in such a configuration, the uppermost sheet material P1 is fed to the sheet feeding roller. 28, pressure plate 21 and separation pad 24
The sheet material P falls from the gap between the sheet material 1 and the sheet material P and cannot be stacked and held on the pressure plate 21.

On the other hand, when an A4-size sheet material P is stacked, as shown in FIG. 14, the effect on the device size is as follows. In FIG. 1, reference numeral 100 denotes a paper feeding device main body, and 101 denotes a paper feeding tray.

That is, the stacking angle of the sheet material P with respect to the horizontal direction is A °, the depth length B when the A4 sheet material (length 297 mm) is stacked, the sheet feeding tray 101.
When the length is 240 mm in the sheet material length direction, the depth length is Cmm, and the main body length is 100 m in the sheet material length direction.
Assuming that the depth length at the time of m is Dmm, the following Table 1 is obtained.

[0013]

[Table 1]

Here, when the sheet feeding device is mounted on the image forming apparatus, an electric component such as a power supply is often provided below the sheet feeding device.
About 0 mm is required. Therefore, from Table 1 above, if the value of A is 40 or more, it is not necessary to increase the body size.
Also, regarding the depth when the sheet material P is stacked,
When the angle is less than 40 °, the size becomes considerably large, and the installation area in actual use is increased. Further, when the user performs an operation from the front, it is easier to perform the operation if the angle is 40 ° or more.

On the other hand, when the angle A is set too high, the ratio of the weight of the sheet material P in the transport direction is as shown in E in Table 1 above. In Table 1, friction between sheet materials P is not taken into account. As is clear from E in Table 1, as the angle increases, most of the own weight is applied in the transport direction.

If most of the weight of the sheet material P is applied in the transport direction, problems such as double feeding and buckling of the leading edge of the sheet material P due to long-term stacking may occur. I do. From this, the value of A, which is an allowable range of the stacking angle of the sheet material P with respect to the horizontal direction obtained in the experiment, is 60 ° or less. From the above, it is preferable that the stacking angle A of the sheet material is set to 40 ° to 60 °.

Further, as another means for solving the back tension problem, a notch 285 is formed in the paper feed roller 28 for performing frictional separation, as shown in FIG. 15 shown in Japanese Patent Publication No. 6-76148. In some cases, a rotating roller 251 that presses the sheet material P being conveyed against the separation pad 241 at a position where the notch 285 faces the separation pad 241 is provided. By pressing the sheet material P with the rotating rollers 251 in this manner, the back tension can be set small, and double feeding of the sheet material P can be prevented.

Further, in Japanese Utility Model Application Laid-Open No. 60-137737, a return arm 26 for pushing back the protruding sheet material P is provided as shown in FIG.
A configuration has been proposed in which, when 1 is separated, the return arm 26 is rotated clockwise to push back the protruding sheet material P. The return arm 26 can return the sheet material P, which has gradually protruded in the transport direction due to its own weight, friction, static electricity, or the like, to the normal stacking position, thereby preventing double feeding.

Further, based on the above structure,
As shown by 07272, in a configuration in which the sheet feeding device is mounted on the image forming apparatus in an upright state, a device that reduces the back tension while loading and holding the sheet material P has been proposed.

[0020]

Incidentally, in such a conventional paper feeding apparatus, it is necessary to increase the size of the recording head due to the recent increase in printing speed and to provide an electric control board between the recording head and the paper feeding roller. With the diversification of the configuration, the distance from the paper feeding device to the transport roller of an image forming apparatus such as a recording device has been increased, and therefore, the diameter of the paper feeding roller needs to be increased. An appropriate value of the diameter of the paper feed roller for realizing these configurations is φ38 to 46 mm. (Conventionally φ28-33mm)

However, as the diameter of the paper feed roller is increased, the conditions for double feeding and non-feeding of the sheet material P are changed, and it is impossible to cope with the condition of the conventional diameter as it is.

Therefore, the present invention has been made in view of such a situation, and has a paper feeding roller having a large diameter (a paper feeding device capable of feeding a sheet well even with a feeding means, and a paper feeding device having the same. It is an object of the present invention to provide an image forming apparatus.

[0023]

According to the present invention, there is provided a sheet stacking means for stacking sheets at an angle of 40 ° to 60 ° with respect to the horizontal, a sheet fed to the sheet stacking means, and a section having a diameter of φ38. A feeding means having a D-shape obtained by cutting a part of a circle of up to 46 mm, wherein a pressure contact pressure of 1.08 N to 1.47 N is applied to said feeding means.
To separate the sheets fed by the feeding means one by one, separating means formed of urethane foam having a rubber hardness of 80 ° to 85 °, and pressing the sheet against the feeding means with a pressure of 1 °. .27N to 1.67N.

The present invention further comprises a regulating member provided on the sheet stacking means so as to be movable in a direction perpendicular to the sheet feeding direction so as to regulate the posture of the sheet, and the feeding means is interlocked with the regulating member. And move.

Further, the present invention is characterized in that the gap at the entrance of the wedge formed by the arc portion of the feeding means and the separating means is 0.7 to 1.2 mm.

Further, the present invention is characterized in that the coefficient of friction between the separating means and the sheet is 0.8 to 1.2.

Further, the present invention is characterized in that there is provided a return means for returning the sheet entering the wedge portion to the sheet stacking means.

Further, the present invention is characterized in that the separating means is provided with a rotating roller which abuts at a contact pressure of 0.29N to 0.49N.

Further, the present invention is characterized in that the rotating roller is provided so as to be able to contact and separate from the separating means.

Further, the present invention is characterized in that the rotating roller is separated from the separating means when the feeding means feeds out the sheet and the return means returns the sheet.

The present invention is also characterized in that the angle of entry of the sheet into the separating means is 20 ° to 30 °.

Further, the present invention is characterized in that the feeding means abuts substantially at the center of the separating means in the sheet feeding direction.

Further, the present invention is characterized in that a curvature R of 30 to 60 mm is provided in at least one direction before and after the sheet feeding direction from a position where the feeding means of the separating means abuts.

According to the present invention, there is provided an image forming apparatus including an image forming unit and a sheet feeding device for feeding a sheet to the image forming unit, wherein the sheet feeding device is as described above. It is assumed that.

The present invention is characterized in that an electric control board for the image forming section is provided between the image forming section and the feeding means.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a front view of a recording apparatus which is an example of an image forming apparatus provided with a sheet feeding apparatus according to a first embodiment of the present invention, and FIG. 2 is a side sectional view thereof. ,
1 is a recording device. The recording apparatus 1 includes a paper feeding device 2, a paper feeding unit 3, a paper discharging unit 4, a carriage unit 5, a recording head 7, and the like.

Next, the paper feeding device 2, the paper feeding unit 3, the paper discharging unit 4,
The carriage unit 5 will be described.

First, the paper feeding section 3 will be described. The paper feed unit 3 is attached to a chassis 8 made of a bent sheet metal. The paper feed unit 3 has a transport roller 36 for transporting a sheet material and a PE sensor (not shown). here,
The transport roller 36 has a configuration in which an elastic body such as rubber is wound around the surface of a metal shaft, and the metal portions of both shafts are received by a conductive bearing 38 and attached to the chassis 8. Also,
The transport roller 36 is provided with a transport roller tension spring 381 between the bearing 38 and the transport roller 36 so as to apply a load during rotation and perform stable transport. The transport roller tension spring 381 urges the transport roller 36. By doing so, a predetermined load is given.

A plurality of pinch rollers 37 are in contact with the transport roller 36, and the pinch roller 37 is pressed against the transport roller 36 to generate a sheet material transport force. The transport roller 36 is driven by an LF motor 88 so that the sheet material sent to the paper feeding unit 3 is transported below the recording head 7 constituting the image forming unit. It has become.

The recording head 7 is an easily replaceable ink jet recording head integrally formed with the ink tank, and can apply heat to the ink by a heater or the like. The ink causes film boiling due to the heat, and the pressure change caused by the growth or shrinkage of bubbles due to the film boiling causes the ink to be ejected from the nozzles of the recording head 7 to form an image on the sheet material P. I have.

Next, the carriage section 5 for moving the recording head 7 will be described. Carriage unit 5
Has a carriage 50 on which the recording head 7 is mounted. The carriage 50 has a guide shaft 81 for reciprocally scanning the recording head 7 in a direction perpendicular to the sheet material conveying direction and a rear end of the carriage 50. A guide rail 82 that holds and maintains a gap between the recording head 7 and the sheet material
Supported by

The guide shaft 81 is attached to the chassis 8, and the guide rail 82 is formed integrally with the chassis 8. As described above, by forming the guide rail 82 integrally with the chassis 8, the number of parts and the number of mounting steps can be reduced, and the cost can be reduced. In addition, since the rigidity of the chassis 8 is increased by bending the guide rail 82, the strength reliability is improved. Further, when the conventional strength is sufficient, the thickness of the sheet metal forming the chassis 8 can be reduced, so that the cost is further reduced.

On the other hand, the carriage 50 is driven via a timing belt 83 by a carriage motor 80 mounted on the chassis 8. This timing belt 83
Is stretched and supported by an idle pulley 84.

In the above configuration, when an image is formed on a sheet material, the conveying roller 36 conveys the sheet material to a line position (position in the conveying direction of the sheet material) where the image is formed, and the carriage motor 80 causes the carriage 50 to form the image. The recording head 7 is moved to a row position (a position perpendicular to the sheet material conveyance direction) where the recording head 7 is to be formed, and the recording head 7 is opposed to the image forming position. Thereafter, an image is formed by ejecting ink toward the sheet material by the recording head 7.

In FIG. 2, reference numeral 9 denotes a recording head 7;
And an electric control board for controlling the recording head provided between the recording head 7 and the paper feeding roller 28 described later. Thereby, the degree of freedom of the configuration of the recording apparatus 1 can be increased.

Next, the paper discharge unit 4 will be described. The paper discharge unit 4 includes a transfer roller 40 that contacts the transport roller 36, a discharge roller 41 that contacts the transfer roller 40, and a spur 42 that can rotate following the discharge roller 41. When the transport roller 36 rotates, the driving force of the transport roller 36 is transmitted via the transmission roller 40 to the discharge roller 41.
, Whereby the paper discharge roller 41 and the spur 42 rotate in the paper discharge direction. As a result, the sheet material on which an image has been formed by the carriage unit 5 is nipped by the nip between the discharge roller 41 and the spur 42, conveyed, and discharged to a discharge tray (not shown).

Next, the sheet feeding device 2 constituting the sheet feeding section will be described. The paper feeding device 2 includes, for example, a base 2 inclined at an angle of 40 ° to 60 ° with respect to the apparatus main body 1A.
Each component is attached to the unit 0 to form an integrated unit. Reference numeral 201 denotes a paper feed tray.

As shown in FIG. 3, the sheet feeding device 2 includes a pressure plate 21 constituting sheet stacking means for stacking sheet materials together with a sheet feeding tray 201, a sheet feeding roller 28 for feeding sheet materials, and a separation base 22. , Separation pad holder 24,
A pressure plate spring 212, a separation plate spring 242, a rotating roller 251,
A paper feed roller unit including a return lever 26 and the like is configured to be symmetrically attached to the base 20. By attaching the sheet feeding device 2 to the base 20 in this way, the sheet material is stacked on the sheet feeding tray 201 and the pressure plate 21 at an angle of 40 ° to 60 ° with respect to the horizontal.

The paper feeder 2 is of a one-side reference type having a movable side guide 23 as a regulating member, and is configured so that the reference position of the sheet material is the same even if the paper size is different. I have. In the present embodiment, the left end of the sheet material is the reference side, and the base 20 has a paper end reference 202 as a reference.

Here, the paper feed roller 28 as the feeding means has a substantially circular shape in a side view, and the outer peripheral arc portion of the paper feed roller 28 has, for example, a hardness of about 20 to 40 ° (A scale). A paper feed roller rubber 282 made of a high friction material such as EPDM rubber is attached. In the present embodiment, the sheet feeding roller 28 has a D-shaped cross section in which a part of a circle having a diameter of Φ38 to φ46 is cut.

Further, two paper feed rollers 28 are provided on the left and right, and the paper feed roller 28 on the paper end reference side is fixed to a paper feed roller shaft 281. On the other hand, the paper feed roller 28 on the movable side guide side is movable in accordance with the paper size and is formed separately from the paper feed roller shaft 281.
It can slide in one axial direction.

A groove 283 is provided in the feed roller shaft 281 in the axial direction, and a convex portion 284 corresponding to the groove 283 is provided in a fitting hole of the feed roller 28 with the shaft.
The driving force from the paper feed roller shaft 281 is transmitted to the paper feed roller 28 by the 83 and the convex portion 284.

On the other hand, the movable side guide 23 is movably provided on the pressure plate 21 to regulate the stacking position of the sheet material, and is extended toward the paper feed roller 28 and has a paper feed roller contact portion. Here, the pressure plate 21 is rotatable about a rotation shaft connected to the base 20, and is driven by a pressure plate spring 212 as two urging means provided at positions substantially corresponding to the paper feed roller 28. Is to be energized. The pressure plate spring 212 is housed in the separation base 22.

The paper feed roller 28 is configured symmetrically in the left and right direction, but the paper feed roller unit on the non-paper end reference side is connected to the movable side guide 23 attached to the pressure plate 21 and slides in the left and right direction. It is configured to be possible.
Thus, when the movable side guide 23 is moved according to the paper size, the paper feed roller 28 also follows (interlocks).
Then, it is configured to move to a predetermined position.

Therefore, regardless of the size of the sheet material, the sheet material can be conveyed at a fixed distance from the end of the sheet, whereby the sheet feeding performance of the sheet material and the left-right balance of the back tension can be improved. Rows can be reduced.

Further, the pressure plate 21 facing the paper feed roller 28
The movable sheet guide 23 is provided with a separation sheet 234 made of a material having a large coefficient of friction such as an artificial skin for preventing double feeding of the sheet material. The separation sheet 234 has the same performance as a separation pad 241 described later.

The separation base 241 is provided on the separation base 22 as separation means for separating sheet materials one by one.
A separation pad holder 24 to which the separation pad 22 is attached is rotatably mounted on a rotation shaft coupled to the separation base 22. The separation pad 241 is attached to the sheet feeding roller 28 by a separation pad spring 242 mounted on the separation base 22. Be energized.

Here, the separation pad 241 is made of a material (for example, a material such as cork) having a coefficient of friction with respect to the sheet material smaller than the coefficient of friction of the paper feed roller rubber 282. The friction coefficient between the separation pad 241 and the paper feed roller rubber 282 is made of a material having a larger friction coefficient than the friction coefficient between the sheets. That is, if the friction coefficient between the paper feed roller rubber 282 and the sheet material is μ1, the friction coefficient between the separation pad 241 and the sheet material is μ2, and the friction coefficient between the sheet materials is μ3, μ1>μ2> μ3 It has become.

The separation roller holder 24 has a rotation roller 251 rotatably mounted thereon.
The rotary roller holder 25 is provided with a rotary roller spring 252 so that the rotary roller 251 is separated from the separation pad 241.
And a predetermined pressure.

Here, the frictional force f4 between the sheet material and the separation pad 241 caused by the urging force of the rotating roller 251 is:
The back tension is set to such an extent that the conveyance accuracy is not significantly affected, and the sheet material is prevented from dropping. The urging force of the rotating roller 251 against the separation pad 241 is set to be smaller than the contact force between the separation pad 241 and the paper feed roller 28.

The contact position between the rotary roller 251 and the separation pad 241 is substantially the same as the contact position between the paper feed roller rubber 282 and the separation pad 241 in a side view. In addition, the rotating roller holder 25 is configured such that the rotating roller 251 has the separation pad 241.
The movement is regulated so as not to be separated by a predetermined amount or more in the direction away from the camera.

By regulating the rotating roller holder 25 in this way, the rotating roller 25
Even if 1 is lifted from the separation pad 241, the rotating roller 2
51 can be regulated at a predetermined position. As a result, it is possible to prevent the rotation roller 251 from entering the inside of the paper feed roller rubber 282, and the sheet material P and the paper feed roller rubber 282 or the like abut against each other, and a large back tension can be prevented.

Also, inside the left and right paper feed rollers 28, a return means for returning the sheet material P which has entered between the left and right paper feed rollers 28 and the separation pad 241 to the loading position on the pressure plate 21. A lever 26 is provided. Here, the return lever 26 is configured to be rotatable around a rotation shaft connected to the separation base 22. The return lever 26 is configured to rotate by a return lever cam 261 to which drive is transmitted by a return lever cam shaft 262.

On the other hand, as shown in FIG. 4, a release cam gear 299 for releasing the contact with the paper feed roller 28 is provided on the rotating shaft of the pressure plate 21.
When the pressure plate 21 is lowered to a predetermined position by the step 9, the notch 285 of the sheet feed roller 28 is set to a position facing the separation pad 241. Thus, the separation pad 241 can be separated from the paper feed roller 28.

In this embodiment, the release cam gear 299 contacts the sheet supply roller 28 and the separation pad 214 before the pressure plate 21 contacts the sheet supply roller 28,
After the pressure plate 21 and the feed roller 28 are separated from each other, the feed roller 2
8 and the separation pad 214 are separated from each other.

In the figure, reference numeral 295 denotes a drive switching gear, to which the forward rotation of the conveying roller 36 is transmitted via an input gear 291. FIG. 5 is a diagram for explaining the operation of the drive switching.

As shown in FIG. 5A, the drive switching gear 29
5 is transmitted to the planetary gear 298. Normally, a solenoid pin 273 that regulates the position of the planetary gear 298 acts on a regulating groove of the planetary gear arm 274 to which the planetary gear 298 is attached, thereby restricting the position of the planetary gear 298. Is not transmitted to other parts even if the motor rotates forward and backward.

On the other hand, as shown in FIG. 5B, the operation of the solenoid 271 causes the solenoid pin 273 to move in the direction indicated by the arrow C.
Moving in the direction, the planetary gear 298 is released from position regulation. Accordingly, when the drive switching gear 295 rotates forward, the planetary gear arm 274 moves in the direction of arrow A,
As a result, the planetary gear 298 acts on the idler gear 293, whereby the drive is transmitted to the paper feed roller gear 294, and the paper feed roller 28 rotates.

Here, the feed roller 28 has the notch 285 as described above, and is configured to be in phase with the release gear 229. The paper feed roller 28 has an idler gear 292 as shown in FIG.
, A release cam gear 299 for releasing or releasing the pressure plate 21 is rotated. The rotation of the release cam gear 299 causes the pressure plate 21 to be separated from the paper feed roller 28 or to be in contact with the paper feed roller 28.

As shown in FIG. 5C, when the drive switching gear 295 rotates in the reverse direction, the planetary gear 298 moves in the direction of arrow B, whereby the planetary gear 298 is attached to the return lever cam shaft 262 via the return lever cam gear 296. Acts on the return lever drive gear 297, and as a result, the return lever cam 26
1 rotates, and the return lever 26 rotates. When the operation of the solenoid 271 is released, the solenoid pin 273 is released.
Can enter the regulating groove of the planetary gear arm 274 by the urging force of the solenoid spring 272, so that the planetary gear 298 can be held at a predetermined regulating position.

Next, the paper feeding operation of the paper feeding device 2 configured as described above will be described.

In the above configuration, in the initial state shown in FIG. 6A, the release cam 299 (see FIG. 4) is
Is pushed down to a predetermined position. Thereby, the pressure plate 21
And the paper feed roller 28 are separated from each other, and the notch 285 of the paper feed roller 28 is located at a position facing the separation pad 241.
The separation pad 241 is also separated from the paper feed roller 28 by the action of the pressure plate 21.

Here, the rotating roller 251 urges the separation pad 241 at a predetermined pressure. Further, the return lever 26 has completed the return operation, and is located in a state of being retracted from the transport path of the sheet material P. In the present embodiment, for example, the contact pressure between the rotary roller 251 and the separation pad 241 is set to 0.29 N to 0.49 N, and the friction coefficient between the separation pad 241 and the recording material is set to 0.8 to 1. It is 2.

By setting the contact pressure between the rotating roller 251 and the separation pad 241 and the coefficient of friction between the separation pad 241 and the sheet material P as described above, the paper feed roller 28 The sheet material P can be held down even when the sheet material P comes off.

When the sheet feeding operation is started, in this state, the driving force of the transport roller 36 is transmitted in the direction for rotating the drive switching gear 295 forward. At this time, when the solenoid pin 273 is released by the operation of the solenoid 27 as shown in FIG. 5B, the position of the planetary gear arm 274 is released. As a result, when the drive switching gear 295 rotates forward, the planetary gear 298 comes into contact with the idler gear 292 to transmit the drive.

As a result, as shown in FIG. 6B, the feed roller 28 starts to rotate, and then immediately after the arc portion of the feed roller 28 comes into contact with the separation pad 241, the release cam gear 299 moves to the pressure plate. Since the platen 21 is separated from the platen 21, the platen 21 starts to rise. At this time, even if the loaded sheet material P becomes unstable due to the movement of the pressure plate 21, the separation pad 241 and the sheet feeding roller 28 are in contact with each other first. Do not get into it.

In this state, the feeding of the sheet material P is started. Here, since the relationship between the friction between the sheet feeding roller 28, the separation pad 241, and the sheet material P is as described above, FIG.
As shown in (c), only the uppermost sheet material P1 is fed, and the next and subsequent sheet materials P are not fed. The sheet material P thus separated one by one is fed to the sheet feeding unit 3.
The tip is detected by the PE sensor, and then fed by a predetermined amount, and is nipped by the transport roller 36 and the pinch roller 37.

On the other hand, as shown in FIG. 7A, when the feed roller 28 makes one rotation, the release cam gear 299 pushes the pressure plate 2
1 to release the sheet feed roller 28 and the pressure plate 21
Are separated. At this time, the pressure plate 21 and the paper feed roller 28
Is separated from the arc portion 285 of the paper feed roller 28 and the separation pad 241. Therefore, even if the loaded sheet material P becomes unstable due to the movement of the pressure plate 21, the separation pad 241 and the paper feed roller 28 come into contact with each other. And the sheet material P does not enter beyond the separation pad 241.

Thereafter, the operation of the solenoid 271 is released again, the planetary gear 298 is held at a predetermined position, and the driving force from the transport roller 36 is cut off in this state. In this state, as shown in FIG. 7B, the sheet material P generated by the urging force of the rotating roller 251 and the separation pad 2
Since the frictional force f4 of 41 is set to a value that minimizes the influence of the back tension on the conveyance accuracy and prevents the sheet material P from dropping, a good conveyance accuracy without the influence of the back tension is obtained. At the same time, entry of the sheet material P is prevented.

Further, the rotary roller 251 and the separation pad 24
The contact position of the sheet material P is substantially the same as the contact position of the sheet feeding roller 28 and the separation pad 241 in a side view, so that the sheet material P can be prevented from entering beyond the separation pad 241 and at the time of separation and feeding, It is possible to prevent double feed, in which the next sheet material P is sent out.

Then, after the trailing end of the sheet material P conveyed and printed by the conveying roller 36 passes through the PE sensor and further printing and discharging are completed, the solenoid 271 is actuated and the planetary gear 298 The position regulation is released, and the reverse rotation drive is transmitted to the drive switching gear 295. Here, when the drive switching gear 295 rotates in the reverse direction, the drive is returned to the return lever action cam 261.
7C, the return lever 26 rotates to return the sheet material P remaining on the separation pad 241 to the stacking position.

Thus, the separation pad 2 of the sheet material P
The function of preventing entry into the area after 41 can be further improved, and double feeding can be prevented. After that, when the return claw action cam 261 further rotates and does not act on the return lever 26, the return lever 26 is moved by its own weight as shown in FIG.
Is configured to return to the initial position.

With the above, a series of feeding operations is completed. When the next sheet material P is fed, the above operation is repeated again.

An important point in terms of performance in the above configuration is how to balance the double feeding of thin paper and the non-feeding of thick paper to secure their margins. Here, factors (parameters) shown in FIG. 8, that is, the material / hardness of the separation pad 241, the entry angle of the sheet material P into the separation pad 241, and the factors resulting from the double feeding of thin paper and the non-feeding of thick paper, The contact pressure of the separation pad against the sheet supply roller 28, the pressure plate pressure, the gap between the sheet supply roller 28 and the separation pad 241, and the contact pressure between the rotating roller 251 and the separation pad 241 are exemplified. Each of these items has the following tendency.

(1) Material / Hardness of Separation Pad: When urethane foam is used as the material of the separation pad, the higher the hardness, the easier the double feeding, and the lower the hardness, the easier the non-sending.

(2) The entry angle of the sheet material into the separation pad: a smaller one is more likely to feed multiple sheets, and a larger one is more likely to be non-feeding.

(3) Separation pad contact pressure with the paper feed roller: A smaller one is more liable to feed multiple sheets, and a larger one is more likely to be non-feeding.

(4) Pressure plate pressure: The larger the pressure, the easier it is to feed
Smaller ones are easier to send.

(5) Clearance between paper feed roller and separation pad portion:
Larger ones are easier to double feed, smaller ones are easier to reject.

(6) Contact pressure between rotating roller and separation pad:
Smaller ones are easier to double feed, and larger ones are easier to reject.

Here, in the conventional sheet feeding device, the stacking angle of the sheet material P is approximately 50 ° with respect to the horizontal angle, and the diameter of the sheet feeding roller is approximately Φ33 mm. The above parameters are as follows. (1) Urethane foam hardness 90 °,
(2) 20 ° to 30 °, (3) 0.98 N (per feed roller), (4) 1.96 N (per feed roller), (5) 0.9 mm, (6) 0 .49N (per feed roller).

However, with the above configuration, the roller diameter is simply increased by Φ due to the necessity of increasing the size of the feed roller 28 described above.
In the case where the length is set to 38 to 46 mm, the paper feed roller 28 and the separation pad 241 are inserted into the leading end of the wedge portion K.
Since the leading-edge angle of the sheet material P after the first sheet with respect to the separation pad 241 becomes small, double feeding becomes easy. On the contrary, it works advantageously for the non-delivery of cardboard. Therefore, when the outer diameter is increased, it is necessary to set the non-feed side from the setting of the above-described conventional sheet feeding device.

Therefore, the loading angle is 40 ° to 6 ° with respect to the horizontal.
The sheet material P stacked in the state of 0 ° is φ38 to 46
In order to realize the optimum feeding conditions when feeding by the paper feed roller 28 mm, of the above-mentioned six parameters, those having a degree of freedom in configuration and those greatly contributing to performance include ( Select 1), (3), (4),
For the combination, a confirmation test of double feed and non-feed was performed.

In this test method, A4 size thin paper (about 60 g / tsubo paper), which is easy to double feed, and postcard size thick paper (about 200 g / tsubo paper), which is easy to reject, are conveyed and the level is set to OK. , NG. The results are shown below.

[0096]

[Table 2]

[0097]

[Table 3]

[0098]

[Table 4]

[0099]

[Table 5]

From the above results, the cross section was φ38 to 46 mm.
Feed roller 2 having a D-shape obtained by cutting a part of the circle
8. The loading angle of the sheet material P is 40 ° to 60 ° with respect to the horizontal.
°, the separation pad 241
Is a foamed urethane with a rubber hardness of 80 ° to 85 °, a separation pad pressure of 1.08N to 1.47N, and a pressure plate pressure of 1.27N to
1.67N balances double feed and non-feed,
It was also found that this was an optimal value that could secure a margin.

The entry angle of the sheet material into the separation pad 241 in (2) is set at 20 ° to 30 ° as in the related art, so that even if the separation pad 241 made of foamed urethane is used, a good pre-separation can be performed. Can do it.

The gap between the entrance of the wedge K formed by the paper feed roller 28 and the separation pad 241 in (5) is 0.7 to 1.2 mm as in the past [nominal (design center) value 0.9 mm Accordingly, it is possible to restrict the sheet material from entering the wedge portion K due to its own weight, thereby preventing the occurrence of double feeding.

Incidentally, the rotating roller pressure of (6) is set to 0.1.
Since no difference in the test results was found between 29N and 0.49N, the difference is set to 0.29N to 0.49N. In this case, the coefficient of friction between the separation pad 241 and the general sheet material P is 0.8 to 1.2.

As described above, the loading angle is 40 ° with respect to the horizontal.
Optimum paper feeding conditions in the paper feeding roller 28 of 〜60 ° and φ38-46 mm can be realized. As a result,
A paper feeder and a recording apparatus (image forming apparatus) equipped with the paper feeder, which can secure a sufficient balance and margin between double feed and non-feed, and can perform good feeding even for various sheet materials. Can be provided.

In the above description, the rotating roller 251 is always urged against the separation pad 241. However, the present invention is not limited to this, and the sheet feed roller 28 and the separation pad 241 may contact each other to prevent the sheet material P When the return lever 26 acts on the sheet material P and returns to the stacking position, the rotating roller 251 is moved to the separation pad 241.
It is good also as composition separated from.

FIG. 9 is a diagram showing the configuration of such a paper feeder according to the second embodiment of the present invention. 2, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

In the figure, reference numeral 254 denotes a solenoid, and this solenoid 254 is connected to the rotary roller holder 25. When the solenoid 254 operates,
The rotary roller holder 25 rises and stops at a predetermined position. In this state, the rotating roller 251 and the separation pad 241 are separated.

Therefore, when the sheet feed roller 28 and the separation pad 241 are in contact with each other and the solenoid 254 is operated while the sheet material P is being fed, as shown in FIGS. And the separation pad 241 are separated from each other. In this embodiment, the operation of the solenoid 254 is released immediately before the separation of the paper feed roller 28 and the separation pad 241, and as shown in FIG.
The rotation roller 251 and the separation pad 241 are controlled so as to contact each other.

Further, as shown in FIG. 11C, when the return lever 26 starts rotating to return to the sheet material P, the solenoid 254 operates, and the separation pad 24 is actuated.
1, the rotating roller 251 is separated.

[0110] With this configuration,
While the sheet material P is being fed by the sheet feeding roller 28, the rotating roller 251 does not become a resistance, so that the sheet material P can be fed smoothly. Further, since the return operation by the return lever 26 is not hindered by the urging of the rotary roller 251, the return operation can be performed smoothly without damaging the sheet material P.

On the other hand, in the description so far, the shape of the separation pad 241 is flat, but the present invention is not limited to this. For example, a curved surface may be provided on the separation pad 241 as shown in FIG. . In the drawing, a curvature of R30 to 60 mm is provided before and after the sheet material conveyance direction from the position where the sheet feeding roller 28 and the separation pad 241 abut.

By providing a curved surface at such a position, the length of the front and rear pads 241 from the position where the paper feed roller 28 and the separation pad 241 abut while maintaining the gap between the paper feed roller 28 and the separation pad 241 is maintained. For example, it is possible to increase the degree of freedom of design and to increase the margin of conveyance, for example, the length can be increased, the entry angle can be changed, and the like.

[0113]

As described above, according to the present invention, the pressing pressure for pressing the separating means against the feeding means, the rubber hardness of the urethane foam forming the separating means, and the pressing pressure for pressing the sheet against the feeding means are described. By setting to a predetermined range, the sheet stacked on the sheet stacking means at an angle of 40 ° to 60 ° with respect to the horizontal can be formed into a D-shaped shape in which a part of a circle having a cross section of φ38 to 46 mm is cut. Satisfactorily even when a feeding means having a large size is used.

[Brief description of the drawings]

FIG. 1 is a front view of a recording apparatus that is an example of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the recording apparatus.

FIG. 3 is a front view of the paper feeding device.

FIG. 4 is a side cross-sectional view illustrating a configuration of the sheet feeding device.

FIG. 5 is a diagram illustrating a drive switching operation of the paper feeding device.

FIG. 6 is a diagram illustrating a sheet feeding operation of the sheet feeding device.

FIG. 7 is another view illustrating the sheet feeding operation of the sheet feeding device.

FIG. 8 is an explanatory diagram of parameters around a sheet feeding roller of the sheet feeding device.

FIG. 9 is a diagram illustrating a configuration of a sheet feeding device according to a second embodiment of the present invention.

FIG. 10 is a diagram illustrating a sheet feeding operation of the sheet feeding device.

FIG. 11 is another diagram illustrating a sheet feeding operation of the sheet feeding device.

FIG. 12 is an explanatory diagram illustrating a configuration around a sheet feeding roller of a sheet feeding device according to a third embodiment of the present invention.

FIG. 13 is an explanatory diagram illustrating a configuration around a sheet feeding roller of a conventional sheet feeding device.

FIG. 14 is an explanatory diagram of a factor related to a device size in a conventional sheet feeding device.

FIG. 15 is an explanatory diagram of a configuration around a paper feed roller of another conventional paper feed device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 recording device 2 paper feeder 7 recording head 21 pressure plate 23 movable side guide 26 return lever 28 paper feed roller 201 paper feed tray 212 pressure plate spring 251 rotating roller 254 solenoid K wedge P recording material

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Yoshino 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 3F343 FA02 FB01 FC01 GA02 GB01 GC01 GD01 HD17 JA03 JA14 JA19 JD08 JD33 JD35 KB05 KB17 LA04 LA15 LC14 LC17 MC23

Claims (13)

[Claims] 1. A sheet stacking means for stacking sheets at an angle of 40 ° to 60 ° with respect to the horizontal, feeding out the sheets stacked on the sheet stacking means, and having a cross section of φ38 to
A feeding means having a D-shape in which a part of a circle of 46 mm is cut, wherein said feeding means is pressed against said feeding means at a pressure of 1.08 N to 1.47 N. Means for separating the sheets fed by the means one by one, a separating means formed of urethane foam having a rubber hardness of 80 ° to 85 °, and a pressure contact pressure of 1.27N to 1.6 for the sheet to the feeding means.
And a urging means for urging the sheet stacking means so as to press the sheet at 7N. 2. The sheet stacking means includes a regulating member movably provided in a direction orthogonal to a sheet feeding direction so as to regulate a posture of the sheet, and moves the feeding means in conjunction with the regulating member. 2. The sheet feeding device according to claim 1, wherein the sheet feeding is performed. 3. A gap between an entrance of a wedge formed by an arc portion of the feeding means and the separating means is set to 0.7-1.
2. The sheet feeding device according to claim 1, wherein the length is 2 mm. 4. The sheet as claimed in claim 1, wherein the coefficient of friction between the separating means and the sheet is 0.8 to 1.2.
Paper feeder as described. 5. The sheet feeding device according to claim 3, further comprising a return unit that returns the sheet that has entered the wedge portion to the sheet stacking unit. 6. A contact pressure of 0.29 N to the separation means.
5. The sheet feeding device according to claim 1, further comprising a rotating roller abutting at 0.49N. 7. The sheet feeding device according to claim 6, wherein the rotating roller is provided so as to be able to approach and separate from the separating unit. 8. The sheet feeding apparatus according to claim 7, wherein said rotating roller is separated from said separating means when said feeding means sends out a sheet and said returning means returns said sheet. 9. The sheet rush angle to the separating means is 20.
5 to 30 °, wherein
9. The paper feeding device according to any one of 6 to 8, above. 10. The sheet feeding device according to claim 1, wherein the sheet feeding unit abuts substantially at the center of the separating unit in a sheet feeding direction. 11. The sheet feeding device according to claim 10, wherein a curvature R of 30 to 60 mm is provided in at least one direction before and after the sheet feeding direction from a position where the feeding unit of the separating unit comes into contact. 12. An image forming apparatus comprising: an image forming unit; and a sheet feeding device for feeding a sheet to the image forming unit, wherein the sheet feeding device is one according to any one of claims 1 to 11. An image forming apparatus comprising: 13. The image forming apparatus according to claim 12, wherein an electrical control board of the image forming unit is provided between the image forming unit and the feeding unit.