JP3239009B2 - Sheet material feeding device and image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, and more particularly to a sheet feeding apparatus suitable for use as an automatic document feeder and an image forming apparatus provided with the sheet feeding apparatus. It is.

[0002]

2. Description of the Related Art Conventionally, there is an automatic document feeder that is connected to a copying machine or the like and automatically conveys a sheet-shaped document (sheet material) along a predetermined conveyance path.

FIG. 12 shows a circulation type document feeder as an example of such an automatic document feeder.

[0004] The apparatus can typically perform two modes of copying (document feeding method), one of which is a switchback mode in which a document is circulated by switchback.

[0005] This switchback mode is used for copying double-sided originals or large size (A3, B4, LGR,
In the mode of LGL or the like or 2in1 or the like, the tray 4 in FIG. Do.

In the case of a half-size (A4, LTR, B5, etc.) single-sided copy that is generally used, a closed loop mode (because the original can be continuously conveyed in one direction with the original space being shortened). This is a mode that is more advantageous than the switchback mode in terms of exchange time), and achieves high productivity. In this case, the original is continuously fed in one direction according to the path indicated by arrow B. Further, in the closed loop mode, the discharge position of the exposed document is the discharge roller 22, and in this case, the tray 4 is lowered as indicated by a two-dot chain line in the figure.

[0007] The switchback and closed loop of the above configuration
There is an automatic document feeder capable of automatically switching one pass in accordance with a copy mode.

[0008]

However, when the copying operation is to be performed in the closed loop mode in which the document exchange time is short in the above-described conventional example, the tray 4 is rotated horizontally to secure a discharge space from the closed loop discharge side. Normal (switchback mode) because the original cannot be reloaded
The tray 4 is positioned at a substantially horizontal position with respect to the tray inclination angle of about 15 °, and the document is separated and fed.

In such an automatic document feeder, since the sheets are separated one by one from the lower side at the nip portion between the feed roller 7 and the separation belt 8, the feed roller 7 rotates in the normal rotation direction with the sheet feeding, and The belt 8 rotates in the reverse direction, and the friction coefficient of the feed roller 7 is slightly higher than the friction coefficient of the separation belt 8. When the sheet is separated, the sheet enters the separation nip point. At that time, since the sheet to be fed more or less comes into contact with the separation belt 8, when the sheet enters the nip point, the sheet is fed in the feeding direction. Propulsion must be applied. This propulsion force is obtained by the rotation of the paper feed auxiliary roller 6 (hereinafter, abbreviated as a half moon roller) in the paper feed direction at the time of paper feed. However, when the tray is inclined in the paper feed direction, the paper is fed by the weight of the sheet bundle. Since the component force in the paper direction is added, the value of the propulsive force in the entire paper feeding direction becomes larger when the vehicle is inclined.

Therefore, when the sheet is fed on the horizontal tray, the horizontal component force in the sheet feeding direction due to the total weight of the sheet bundle is reduced as compared with the case where the tray is inclined at 15 °, and the sheet feeding is not performed. It becomes difficult to enter the separation nip point at the time. Alternatively, since it is difficult to enter, even if the entry is made, a delay occurs, a sheet feeding time is required, or a sheet feeding condition is deteriorated.

[0011] This is because the above-mentioned apparatus can perform high productivity handling (shortening of document exchange time), duplex copying, 2-in-1 mode copying, and large-size copying in both the switchback mode and the closed loop mode. This is a configuration that is efficiently adopted in order to enable various processes in a predetermined space. Therefore, it is necessary to feed paper in two modes having different tray inclination angles.

[0012] Although completely opposite to the above problem,
If the sheet feeding propulsion force is too large, the sheet bundle itself may be stuck to the separation nip point, and the sheet feeding load may increase and the sheet may not be able to be fed. When determining the paper feed condition (feeding force of the feed roller) that can take into account the load component of the sheet due to the inclination of the tray, if the component force due to the sheet load is reduced, It was very difficult to always obtain a stable feeding power, such as a lack of power. In addition, when a sheet feeding device (automatic document feeder) having the above-described problem is used in an image forming apparatus, a sheet (document) feeding failure occurs, and the reliability of the image forming device is reduced. Failure may occur.

In view of the above, the present invention enables good sheet feeding in both the switchback mode and the closed-loop mode, and furthermore, sheet material feeding capable of reliably feeding both large-size and half-size documents. It is an object of the present invention to provide an apparatus and an image forming apparatus provided with the sheet material feeding apparatus.

[0014]

According to a first aspect of the present invention, there is provided a tray having a tray capable of changing an inclination angle of a sheet mounting surface with respect to a sheet feeding direction. In a sheet material feeding device that conveys the sheets stacked thereon one by one along a predetermined conveyance path, as the inclination angle of the sheet mounting surface becomes smaller ,
Equipped with a sheet feeding force adjustment mechanism to increase the feeding force,
The sheet feeding force adjusting mechanism includes: the tray;
Feeds the sheet by projecting from the sheet mounting surface of
A plurality of paper feed auxiliary rollers, and the plurality of paper feed auxiliary rollers.
Is selectively rotatable, and the sheet feeding force adjusting device is
The structure is adjusted according to the amount of sheets placed on the tray.
The paper feed assist roller is selectively rotated to feed paper .

According to a second aspect of the present invention, the paper feed auxiliary roller is a shutter.
A plurality of sheets are arranged in series with respect to the sheet feeding direction .

According to a third aspect of the present invention, the paper feed auxiliary roller is a shutter.
A plurality of paper trays are arranged in parallel with respect to the sheet feeding direction .

According to a fourth aspect of the present invention, there is provided a tray capable of changing the inclination angle of the sheet mounting surface with respect to the sheet feeding direction, and transporting the sheets stacked on the tray one by one along a predetermined transport path. A sheet feeding force adjusting mechanism for increasing a sheet feeding propulsion force as the inclination angle of the sheet placing surface becomes smaller, wherein the sheet feeding force adjusting mechanism is provided with the tray. And a paper feed auxiliary roller for feeding the sheets on the sheet mounting surface of the tray one by one , and changing the rotation speed of the paper auxiliary roller according to the angle of the sheet mounting surface. Features.

[0018] Claim 5 is the above-mentioned claim 1 to claim 5
4 by the sheet material feeding device according to any one of
Feed the sheets on the lay one by one along the specified transport path
An image forming apparatus for forming an image .

[0019]

[0020]

[0021]

[0022]

[0023]

According to the present invention, when the inclination angle of the tray is small or when the tray is in a horizontal state, the sheet feeding force adjusting mechanism increases the sheet feeding propulsion force of the sheet feeding auxiliary roller, and the sheet feeding when the inclination angle of the tray is large. The sheet feeding / propelling force is corrected so as to be substantially the same as the driving force, and the separation / feeding of the sheet is stably performed.

The paper feed propulsion force is increased by increasing the amount of protrusion of the paper feed auxiliary roller from the sheet stacking surface and increasing the amount of lifting of the sheet by the paper feed auxiliary roller. The contact pressure increases due to an increase in the frictional force generated between the sheet feeding auxiliary roller and the sheet.

Further, the paper feed driving force is increased by increasing the number of paper feed auxiliary rollers for feeding the sheet in the paper feed direction.

Further, the paper feed propulsion force is increased by lowering the rotation speed of the paper feed auxiliary roller and increasing the coefficient of friction of the contact portion between the paper feed auxiliary roller and the sheet.

In addition, according to the present invention, when a large sheet is placed on a tray, a part of the sheet is inclined by a sheet lift section, and the sheet feeding propulsion force of the sheet feeding force adjusting mechanism is reduced. It is set to be smaller than the sheet feeding propulsion force in the case of a sheet having a size that cannot be placed on the sheet lift.

[0028]

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

FIG. 1 shows a platen 2 of an image forming apparatus main body 1.
1 shows a sheet material feeding device 3 provided above.
A tray 4 that also serves as a sheet stacking table and a sheet discharging table that can be moved up and down by an elevating link 5
Is provided. Subsequently, a half-moon-shaped paper feeding roller 6, a conveying roller 7, a separation belt 8, and a registration roller 9 are provided, and a wide endless belt 29 is formed by a pair of rollers 10a, 10b.
And is disposed on the platen 2.

The transport path 12 and the transport paths 14 and 1 around the large roller 13 pass through a jump 11 to the left end of the platen 2.
5 is provided, and a discharge roller 16
a and 16b are provided.

When the flapper 18 is in the position indicated by the dotted line, a sheet (not shown) is moved from the conveying path 14 to the conveying path 1.
9 is turned over.
It is to be transported upward.

A transport path 21 is provided following the jump table 20 provided at the right end of the platen 2, and paper discharge rollers 22a and 22b are provided at the end of the transport path 21.

That is, as described above, the tray 4 functions as both a sheet stacking table and a sheet discharging table. The tray 4, the paper feed roller 6, the transport roller 7, the separation belt 8, the registration roller 9, and the endless belt 29 are sheet transport means, the transport path 21 is a first transport path, and the transport path 1
2, 14, and 15 are the second transport paths.

The tray 4 also functions as a sheet stacking table and a sheet discharge table on the second conveyance path in the position indicated by the solid line, and serves as a sheet discharge table on the first conveyance path in the position indicated by the dotted line.

The tray 4 takes the two positions described above by the operation of the link 5 as described above.

The above is the configuration of the sheet feeding apparatus and the flow of sheets in the apparatus.

Next, the lever means 100 will be described with reference to FIGS.

FIG. 2 is a top view of the tray 4 which also serves as a sheet stacking table and a discharge table. The sheet detection means 119 can be rotated by the motor 39 and the rotation support member 120, and detects the position of the lever means 100 by the position detection sensor 121. The sheet detecting means 119 and the lever 100 are formed integrally. The means 10
0 and 119 are usually retracted to the positions indicated by broken lines in the figure. At this time, the sheet detection means 119 is applied to the position detection sensor 121 (sensor ON state).

When image formation is started, the lever means 100 is rotated by the motor 39 and the rotation support member 120 in the direction of the arrow in the figure, and is placed on the sheet. At this time, the position detection sensor 121 does not detect the sheet detection means 119 (sensor OFF state), the motor rotates with a slight force, and the rotation of the motor stops when the partition lever is placed on the sheet. Stop. This energization time depends on the timer value.

The transported sheet (original document) always returns to the tray 4 regardless of which of the first transport path and the second transport path. Therefore, the discharged sheet is configured to overlap the lever means 100 as indicated by P (dashed line) in FIG.

Next, the configuration of the sheet feeding section in this embodiment will be described.

In FIG. 1, the tray 4 is configured to be movable up and down as described above, and is moved up and down by a rotation operation about a rotation fulcrum 4a. In the above-mentioned switchback mode, the sheet feeding operation is performed at the position of the solid line of the tray 4, and in the closed loop mode, the sheet feeding operation is performed at the position of the two-dot chain line of the tray 4. The half-moon roller 6 is configured to rotate while pressing the lowermost sheet of the placed document when feeding the sheet. Then, the half-moon roller 6 applies a paper feed propulsion force F1 (FIG. 1) to the lowermost sheet so as to guide the lowermost sheet to the nip point between the feed roller 7 and the separation belt 8.

FIGS. 4 (a) to 4 (c) show the relationship between the tray 4, the half-moon roller 6 and the separation section (the feed roller 7 and the separation belt 8) in each mode of switchback and closed loop. FIG. 4A shows a basic relationship among the tray 4, the half-moon roller 6, and the separation unit. FIG.
3B shows the position of the tray 4 in the switchback mode, and shows the state of the sheet bundle P when the rotation of the half-moon roller 6 is started. In the switchback mode, the amount of protrusion of the half-moon roller 6 from the surface of the tray 4 (sheet mounting surface 4 ₁ ) is h1, so that when the half-moon roller 6 rotates, the sheet bundle P is pushed upward. half-moon roller 6 is in contact with the sheet P ₁ in the bottom,
Feeding force to the sheet _{P 1} of the bottom _{(W 1 sinθ + μ 1 W} 1
cos θ) acts. Here, mu ₁ is the friction coefficient between the sheet P ₁ and the half-moon roller 6, W ₁ is a number indicating the contact pressure of the lowermost sheet P ₁ and the half-moon roller 6. Θ is the inclination angle of the tray 4. W _1, if the loading seat load on the tray 4 is the same, increases enough lug of half-moon roller 6 is increased. When the entire sheet bundle P is separated from the tray by the half-moon roller 6 (actually, there is a case where the entire sheet bundle P cannot be separated from the tray depending on the contact position of the half-moon roller). The total load W of P is applied to the half-moon roller 6.

FIG. 4C shows the position of the tray 4 and the state of the half-moon roller 6 and the sheet bundle P in the closed loop mode. If the stacked sheets load is the same as FIG. 4 (b), the direction of large closed loop mode of maximum lug amount h ₂ half-moon roller 6 from the sheet stacking surface 4 _1, than when the switch back mode, half moon Roller 6 to lowermost sheet P ₁
, The force in the sheet feeding direction acting on the sheet becomes large. That is, the contact pressure W with the bottom sheet P ₁ on the half-moon roller 6 and the tray 4
Tray when lugs amount from the sheet stacking surface 4 ₁ of half-moon roller 6 is (0 <X <hm) ( hm , all of the sheet bundle P is floating by semicircular roller, all of the sheet bundle P is 4), and assuming that W is a function of h:

If h ₁ <h ₂ , W (h ₁ ) <W (h ₂ ) (1).

Assuming that W (h ₁ ) = μ ₁ W ₁ (when the tray tilt is 15 °) W (h ₂ ) = μ ₁ W ₂ (when the tray tilt is 0 °) (2) The propulsive force of the sheet bundle on the tray 4 when the tray 4 is tilted by the angle θs (during the switchback mode) and when the tray 4 is tilted by θc (during the closed loop mode) is expressed as follows: Fθs = W ₁ sin θs + μ ₁ W ₁ cos θs (3) Fθc = μ ₁ W ₂ (θc ≒ 0 °) (4) (see FIGS. 5A and 5B).

[0047] In fact the paper feeding direction thrust exerted on the bottom sheet P ₁ of the sheet bundle is fed, the paper and the frictional force of the sheet (μ ₂ Wcosθ-Wsinθ), and the tray and frictional force of the paper (mu ₃ Wcos θ−Wsin θ) act as a drag against the paper feed direction propulsion force (μ ₂ is the friction coefficient between paper and paper, μ ₃ is the friction coefficient between tray 4 and paper) (see FIG. 6).

However, the equation of the force field for one sheet to be fed is as shown in FIG. In the equation of FIG. 7, w is the weight of the lowermost sheet.

As described above, when the sheet is fed in a state where the tray 4 is inclined, the propulsive force in the sheet feeding direction is larger than the case where the tray 4 is originally horizontal by the following equation (5). −μ ₃ Wcos θ (5) It takes extra time (μ ₃ is tray 4
And the coefficient of friction of the sheet bundle P, and W is the load of the sheet bundle P).

Therefore, when the horizontal sheet feeding and the sheet feeding in the inclined state are used at the same time, in order to apply the sheet feeding direction thrust in substantially the same state at the time of sheet feeding, the sheet feeding thrust by the half-moon roller 6 is set to the tray inclined state. Thus, a configuration that can be corrected is useful.

Returning to FIGS. 1 and 5, the tray 4 in the present embodiment has a structure capable of rotating around a rotation center 4a in FIG. 1, and a switchback mode indicated by a solid line in FIG. The maximum protrusion amount h ₁ (FIG. 5A) from the tray 4 (the sheet mounting surface 4 ₁ ) when the half-moon roller 6 rotates during the rotation of the half-moon roller 6 from the tray 4 when the half-moon roller 6 rotates in the closed loop mode. Is larger than the maximum protrusion amount h ₂ (FIG. 5B). That is, the position of the rotation fulcrum 4a is appropriately arranged at a position where the above configuration is possible.

Therefore, in the closed loop mode (the tray is horizontal 0 °), the driving force in the sheet bundle feeding direction is (Wsin θ−μ ₃ Wcos θ) as compared with the switchback mode (5).
Due to the shortage of the expression, the amount of protrusion of the half-moon roller 6 from the tray 4 is increased (as a result, the contact pressure of the sheet bundle P against the half-moon roller 6 is increased). By doing so, the conditions at the time of sheet feeding in both the closed loop mode and the switchback mode can be obtained in the same manner, and the sheet feeding apparatus can perform stable sheet feeding in all modes. In addition, the half-moon roller 6 and the tray 4 (the sheet placing surface 4
₁ ) together constitute the sheet feeding force adjusting mechanism 50.

Here, a brief description will be given of the fact that as the amount of protrusion of the half-moon roller 6 from the tray 4 increases, the contact pressure between the half-moon roller 6 and the sheet increases. That is, FIG.
When the sheet is fed as described above, the entire sheet bundle P is pushed upward by the half-moon roller 6 according to the rotation locus of the half-moon roller 6. At this time, the half-moon roller 6 raises the weight of the sheet P by Wα with respect to the entire weight W. In this case, as the protrusion amount h of the half-moon roller 6 increases, the component force of the total load W of the sheet bundle P increases.
Will be on your side.

That is, W = Wα + Wβ (Wα is the component force applied to the half-moon roller, Wβ is the component force applied to the tray) The operation of the sheet feeding apparatus 3 according to the present embodiment having the above configuration will be described.

First, in the switchback mode, sheet feeding is performed with the tray 4 at the position of the solid line in FIG. 1 (about 15 °). When the presence of a document is detected by an empty sensor (presence / absence of document) on the tray 4 (not shown), sheet feeding is started by an operation ON signal of a copying machine (not shown). At this time, the half-moon roller 6 and the feed roller 7 rotate in the document feeding direction, and the separation belt 8 rotates in the opposite direction.

At the time of document setting, a sheet (document) bundle is abutted against the shutter 28 and has not reached the separation nip point. The shutter 28 is retracted from the surface of the tray 4 by a drive source (not shown) in response to the sheet feed ON signal. Then, the sheet bundle P is sequentially pressed from the lowermost portion of the sheet bundle P to the separation nip point by the sheet feeding force due to the rotation of the half-moon roller 6, and is separated one by one by the rotation of the feed roller 7 and the separation belt 8. It has become. One document after the separation is completed is registered with a registration roller 9.
The document is stopped at a predetermined position on the platen 2 by the registration roller 9 and the wide belt 29. Then, after the optical exposure of the copying machine main body (not shown) is completed, the sheet is discharged onto the tray 4 again from the direction A (see FIG. 12) via the reversing path 12.

In the closed loop mode, first, the tray 4 is moved to the position indicated by the two-dot chain line (almost horizontal 0 °) in FIG. 1 by the paper feed start signal (operation ON signal).
Is lowered by the turning operation of. Reference numeral 26 denotes a tray elevating position detecting means (the driving source is not shown).

As shown in FIG. 1, the rotation fulcrum 4a of the tray 4 is located slightly to the left of the rotation center of the half-moon roller 6 in the figure. That is, the amount of protrusion of the half-moon roller 6 from the tray 4 is changed by the swinging operation of the tray 4, and the amount of protrusion of the half-moon roller 6 increases when the tray 4 is lowered. The rotation fulcrum 4a of the tray 4 may be concentric with the rotation center of the half-moon roller 6 (see FIG. 5).

At the position where the tray 4 is lowered, the shutter 2
The sheet bundle 8 is retracted from the tray 4, and the sheet bundle P is fed to the separation unit by the rotation of the half-moon roller 6 (feeding force).

At this time, since the tray 4 is horizontal, the component force in the sheet feeding direction due to the load of the sheet bundle P itself is 0 (or close to 0), but the amount of protrusion of the half-moon roller 6 becomes large (switchback). Therefore, the paper feeding force can be obtained in the same manner as in the switchback mode.

Then, hereinafter, the movement up to the platen 2 is as follows.
After the exposure, the sheet is conveyed in the direction B (see FIG. 12) and returned to the tray 4 after the exposure.

In this embodiment, in the closed loop mode,
Although the configuration in which the first sheet is fed after completely lowering the tray 4 has been described, for example, the same effect can be obtained even if the tray 4 is started to be lowered while the first sheet is being fed.

In this embodiment, the case where the present invention is applied to the paper feed unit of the automatic document feeder has been described as an example. For example, buffering represented by a two-sided intermediate tray of an image forming apparatus is described. The sheet feeding device of the above-described embodiment can be applied to the re-feeding unit in the pass.

Next, a copying machine (image forming apparatus) will be described.
Description will be made based on the cross-sectional view of FIG.

In FIG. 13, reference numeral 200 denotes an upper cassette. Sheets (recording media) in the cassette 200 are separated and fed one by one by the action of a separation claw and a feed roller 201, and are guided to a registration roller 206. Reference numeral 202 denotes a lower cassette. Sheets (recording media) in the cassette 202 are separated and fed one by one by the action of a separation claw and a feed roller 203, and are guided to registration rollers 206.
Reference numeral 204 denotes a manual feed guide, in which the sheet is one sheet at a time.
5 to the registration roller 206. Reference numeral 208 denotes a sheet stacking device (deck type) having an intermediate plate 208a which is moved up and down by a motor or the like, and the sheets on the intermediate plate are separated and fed one by one by the action of a feed roller 209 and a separating claw, and fed by a transport roller 210. It is led to.

Reference numeral 212 denotes a photosensitive drum, 213 denotes a reading optical system, 214 denotes a developing unit, 215 denotes a transfer charger, and 216 denotes a separation charger, and constitutes an image forming unit.

Reference numeral 217 denotes a conveying belt for conveying the sheet on which the image is formed, 218 denotes a fixing device, 219 denotes a conveying roller,
220 is a flapper. The sheet on which the image is formed is guided to the discharge roller 221 by the flapper 220 and is conveyed into the sorter 222. Note that a discharge tray may be mounted instead of the sorter.

Reference numeral 300 denotes an intermediate tray which temporarily stocks the sheet on which the image has been formed when forming an image on both sides of the sheet or when forming an image on one side of the sheet. 301 is a conveying roller, 302 is a conveying belt, 303 is a flapper, 304 is a conveying belt, 30
Reference numeral 5 denotes a transport roller. Pass 306 for duplex copying
To guide the sheet to the intermediate tray 300. At this time, the image surface of the sheet is facing upward. In the case of multiple copying, the sheet is guided to the intermediate tray 300 through the path 307. At this time, the sheet has the image side facing down.

The sheets stacked on the intermediate tray 300 are:
Auxiliary rollers 309, 310, forward / reverse separation roller pair 311
The sheets are separated one by one from below and fed again. The re-feeded sheets are transport rollers 313, 314,
It is guided to the image forming unit via 315, roller 210, and registration roller 206. After image formation, the paper is discharged in the same manner as described above.

In accordance with the number of copies set for one document placed on the platen glass (platen) 2,
First, single-sided copies are made, and they are stacked on the intermediate tray 300. Thereafter, the original on the platen glass 2 is turned upside down and guided again onto the platen glass 2, and the image is read by the number of copies. The read image of the document is formed on a sheet that is re-fed from the intermediate tray 300 every time the document is read. They are sorted by the sorter 222 in page order.

On the other hand, there is also a method in which each time a document is circulated by the document processing apparatus 3 having the above-mentioned paper feeder, only one copy of the document is created. According to this method, even when a plurality of copies are created, copy groups with the same page order can be obtained in order, so that the necessary number of copies can be obtained separately without a sorter. When performing double-sided copying in this way, read both sides of one original sheet continuously, copy and eject both sides of the sheet continuously, and then discharge the original sheet. If repeated, a divided double-sided copy sheet group is obtained.

FIG. 9 shows a main part of a sheet material feeding apparatus applied to the re-feeding section.

Also in this case, the configuration includes a sheet stacking tray of a buffering pass, a sheet discharge section, and a sheet re-feed section. The present embodiment has a configuration in which the tray is inclined such that the component force in the sheet feeding direction due to its own weight of a large-sized sheet is greater than the component force in the sheet feeding direction due to its own weight of a small size (as shown in FIG. When the large-size sheet is re-fed, the protrusion amount displacing means of the half-moon roller (feeding auxiliary roller) 6 (for example, a rotary solenoid RS in FIG. 10) is used. By displacing the half-moon roller 6 in the direction of reducing the amount of protrusion from the tray 4, it is possible to make the small-sized and large-sized paper feeding direction propulsive forces equal. This embodiment, as shown in FIG. 9 (a), the left side in the drawing portion of the tray 4 is inclined seat lift unit 4 ₂
The sheet lift section 42 lifts the end of the large-size sheet in the sheet feeding direction so that the component force in the sheet feeding direction due to the weight of the sheet is increased. In the present embodiment, the left side of the tray 4 in the drawing is tilted,
The length of the tray 4 in the longitudinal direction (sheet transport direction) is shortened. Note that the tray 4 of the present embodiment is
(B), the sheets loaded if a small size, the sheet lifting unit 4 ₂ is prevented from lifting the sheet.

Further, the above embodiment (see FIGS. 1 to 8)
In order to keep the feeding force in the feeding direction constant, the component force in the feeding direction due to the inclination angle of the tray 4 (depending on the sheet load)
Is configured such that the amount of protrusion of the half-moon roller 6 is changed by the raising / lowering operation of the tray 4, for example, as shown in FIG.
The configuration may be such that the half-moon roller 400 itself can be moved up and down by the rotary solenoid RS.

Further, as shown in FIG.
01, 402, these half moon rollers 401, 4
02 are connected to the drive motor M via the clutches CL1 and CL2, respectively, and are connected from the controller (CPU) to the drive motor M and the clutches (for example, electromagnetic clutches) CL1 and CL2 according to the elevating state of the tray 4 and the paper feed size. By outputting a control signal and rotating all of the meniscal rollers 401 and 402, or even selectively rotating only a part of the plurality of meniscal rollers, it is possible to adjust the paper feeding direction propulsion,
The same effects as in the above embodiment can be obtained. In the case of FIG. 11A, normally, only the half-moon roller 401 is rotated, and when the paper feeding direction driving force is required, the 402 is selectively rotated.

FIG. 11A shows a mode in which a plurality of half-moon rollers 401 and 402 are arranged in series.
As shown in (b), a plurality of pieces (for example, four pieces) are arranged in parallel.
Are arranged coaxially, two inner half-moon rollers 403 and two outer half-moon rollers 40
If each of the rollers 4 can be driven separately, it is possible to selectively rotate a plurality of half-moon rollers.

Further, as another embodiment, the half moon roller 6
The rotation speed of the half-moon roller 6 can be changed. For example, when the paper feeding force is increased, the half-moon roller 6 is driven at a low speed at which a value close to the static friction force of the half-moon roller is obtained.
In order to reduce the paper feeding force by rotating the roller, the half-moon roller 6 may be rotated at a high speed.

In addition, a plurality of conditions for the rotation speed of the half-moon roller, the number of rotations of the half-moon roller, and the amount of protrusion from the tray may be simultaneously performed.

When the tray does not swing, as shown in FIG. 14, the sheet feeding force adjusting mechanism including the tray 4 and the half-moon rollers 401 and 402 adjusts the sheet feeding force acting on the sheet. That is, when the amount of the sheets P stacked on the tray (a tray generally used at an angle of 15 degrees or more) 4 is large, the contact pressure between the half moon rollers 401 and 402 and the sheet P is high. 401, 402
The sheet is fed by rotating only one of them (401) (see FIG. 14A). On the other hand, when the amount of the sheets P stacked on the tray 4 is small, the contact pressure between the half moon rollers 401 and 402 and the sheet P is low.
Are rotated to apply a large rotational force (feeding driving force) to the sheet to feed the sheet (see FIG. 14B). In this way, by adjusting the fluctuation of the sheet feeding propulsion force caused by the change in the weight of the sheet bundle, the separation and sheet feeding of the sheet by the feed roller 7 and the separation belt 8 can be ensured.

[0080]

As is apparent from the above description, according to the present invention, when the inclination angle of the sheet mounting surface of the tray on which sheets are stacked becomes small, the sheet feeding at the sheet feeding auxiliary roller is performed by the sheet feeding force adjusting mechanism. Because the paper propulsion force can be increased and the difference in the component force in the paper feeding direction due to the weight of the sheet can be corrected, the paper feeding is always constant even if the copy mode or sheet size changes (feeding conditions change). Force can be applied to the sheet, and stable paper feeding can be realized.

In the image forming apparatus provided with the sheet material feeding device according to the present invention, the sheet is reliably fed along the predetermined conveyance path by the sheet material feeding device. And the reliability of the device can be improved.

[Brief description of the drawings]

FIG. 1 is a main sectional view of a sheet feeding apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing details of a recycling lever unit.

FIG. 3 is a sectional view showing details of a recycle lever portion.

FIG. 4 is a detailed view of a sheet feeding unit. 4A is a basic configuration diagram of the paper feeding unit, FIG. 4B is a detailed diagram of the paper feeding unit in the switchback mode, and FIG. 4C is a detailed diagram of the paper feeding unit in the closed loop mode.

FIG. 5 is an operation state diagram of a sheet feeding direction propulsion generated between a half-moon roller and a lowermost sheet bundle. FIG. 5A is a diagram illustrating the operation state of the sheet feeding direction propulsion force in the switchback mode, and FIG. 5B is a diagram illustrating the operation state of the sheet feeding direction propulsion force in the closed loop mode.

FIG. 6 is a diagram illustrating a relationship between a sheet bundle and a tray.

FIG. 7 is a diagram illustrating a force applied to a tray.

FIG. 8 is a diagram illustrating a relationship between a sheet bundle and a half-moon roller.

FIG. 9 is a simplified side view of an intermediate tray showing another embodiment of the present invention. 9A is a simplified side view of the intermediate tray in the switchback mode, and FIG. 9B is a simplified side view of the intermediate tray in the closed loop mode.

FIG. 10 is a side view of a main part of a tray showing another embodiment of the present invention.

FIG. 11 is a schematic configuration diagram showing another embodiment of the sheet feeding force adjusting mechanism of the present invention. 11A is a schematic configuration diagram when a plurality of half-moon rollers are arranged in series, and FIG. 11B is a schematic configuration diagram when a plurality of half-moon rollers are arranged in parallel.

FIG. 12 is a main sectional view of a conventional sheet material feeding device.

FIG. 13 is an overall configuration diagram of an image forming apparatus.

FIG. 14 is a side view of a main part showing still another embodiment of the sheet feeding force adjusting mechanism of the present invention. FIG. 14A is a diagram illustrating a state where the amount of stacked sheets on the tray is large, and FIG. 14B is a diagram illustrating a state where the amount of stacked sheets on the tray is small.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Sheet feeder 4 Tray 4 ₁ Sheet mounting surface 4 ₂ Sheet lift part 6 Half moon roller (paper feed auxiliary roller) 12, 14, 15, 21 Transport path 50 Sheet feeding force adjustment mechanism

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akihito Dobashi 430-1, Kobayashi, Masuho-cho, Minamikoma-gun, Yamanashi Pref. 56) References JP-A-57-160839 (JP, A) JP-A-4-344662 (JP, A) JP-A-57-151545 (JP, A) JP-A-3-74531 (JP, U) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) B65H 1/00-3/68

Claims (5)

(57) [Claims] 1. A sheet supply device that has a tray capable of changing an inclination angle of a sheet mounting surface with respect to a sheet feeding direction, and conveys sheets stacked on the tray one by one along a predetermined conveyance path. A sheet feeding force adjusting mechanism configured to increase a sheet feeding propulsion force as the inclination angle of the sheet mounting surface decreases, wherein the sheet feeding force adjusting mechanism includes the tray and the tray. A plurality of sheet feeding auxiliary rollers for feeding a sheet by projecting from the sheet mounting surface of the sheet feeding roller, wherein the plurality of sheet feeding auxiliary rollers are selectively rotatable; A sheet feeding device for selectively feeding the sheet by rotating the sheet feeding auxiliary roller in accordance with the amount of sheets placed on the tray. 2. The sheet feeding assist roller according to claim 1, wherein a plurality of the sheet feeding auxiliary rollers are arranged in series in a sheet feeding direction.
The sheet material feeding device according to the above. 3. The sheet feeding auxiliary roller according to claim 1, wherein a plurality of the sheet feeding auxiliary rollers are arranged in parallel to a sheet feeding direction.
The sheet material feeding device according to the above. 4. A sheet feeding device which has a tray capable of changing an inclination angle of a sheet mounting surface with respect to a sheet feeding direction, and conveys sheets stacked on the tray one by one along a predetermined conveying path. A sheet feeding force adjusting mechanism for increasing a sheet feeding propulsion force as the inclination angle of the sheet mounting surface decreases, the sheet feeding force adjusting mechanism comprising: the tray; A sheet feeding auxiliary roller for feeding the sheets on the sheet mounting surface one by one , wherein the rotation speed of the sheet feeding auxiliary roller is changed according to the angle of the sheet mounting surface. Material feeding device. 5. The method according to claim 1, wherein
An image forming apparatus characterized in that an image is formed by feeding the sheets on a tray one by one along a predetermined conveying path by the sheet material feeding device described in (1).