JPH0638027Y2 - Paper feeding device in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a sheet feeding device in an image forming apparatus, and more specifically, to a document feeding roller sequentially from an upstream side to a downstream side in a sheet feeding direction, A conveying roller, in which an upper roller and a lower roller are alternately provided on a pair of upper and lower shafts that rotate in the same direction, and a pair of upper and lower timing rollers are arranged. The present invention relates to an improved technique for the sheet feeding device of the image forming apparatus, which is set to be slightly smaller than the sum of the radii of the lower rollers.

(Prior Art) In the sheet feeding device of the image forming apparatus disclosed in Japanese Patent Laid-Open No. 60-118151, the sheet feeding roller is initially raised as shown by the solid line in FIG.
The paper feed instruction causes the paper 102 to descend on the original document as shown by the phantom line, and starts rotating (FIG. 18). After the document is conveyed to the nip position of the registration roller 104 and further rotated for some time, the feed roller 102 stops rotating and rises, and waits until the registration roller 104 starts rotating. (Fig. 19). In this state, the cutout portion 106a of the upper roller 106 opposes the lower roller 108,
Moreover, since the lower roller 108 is a double feed prevention roller, it always rotates in the clockwise direction.

(Problems to be Solved by the Invention) In the above-mentioned prior art, in the state shown in the drawing, the uppermost paper held between the cutout portion of the upper roller and the lower roller is fed in the feeding direction (right Paper is fed due to the fact that the lower roller, which acts as a double feed prevention roller, is rotated in the clockwise direction as well as the force to return to the opposite direction It goes back in the opposite direction.

Therefore, there is a problem in that the sheet returns from the nip position of the registration roller, the leading edge timing is misaligned, skewed sheet feeding occurs, and in the worst case, sheet feeding failure occurs and JAM (paper jam) occurs. .

(Means for Solving Problems) According to the present invention, in order to solve the above-mentioned problems, according to the present invention, a paper feeding roller is sequentially provided from an upstream side to a downstream side in a paper feeding direction.
A conveying roller, in which an upper roller and a lower roller are alternately provided on a pair of upper and lower shafts that rotate in the same direction, and a pair of upper and lower timing rollers are arranged, and the dimension between the upper and lower shafts of the conveying roller is set to the upper roller. And in the paper feeder of the copying machine set slightly smaller than the sum of the radii of the lower rollers,
A cutout portion is provided on the peripheral surface of the upper roller to form a paper passage gap between the peripheral surface of the lower roller and the peripheral surface of the lower roller, and the paper feed roller and a drive shaft for driving the paper feed roller are provided. With a one-way clutch interposed therebetween, from the time when the leading edge of the paper reaches the nipping portion of the timing roller until the paper feeding roller starts the next paper feeding, and at least in the paper feeding process by the timing roller. There is provided a sheet feeding device in an image forming apparatus configured to expose a passing gap of the sheet and to press the sheet feeding roller on the sheet by its own weight.

(Operation) According to the above-described characteristic configuration, the stopper that prevents the return movement of the paper is configured by the paper feed roller that can rotate only in the direction that allows the paper feed movement of the paper. Even if the sheet is released, and the sheet passing portion of the upper roller forms a sheet passing gap, the sheet does not eliminate the loop, and the sheet may be obliquely fed or cannot be fed. Instead, the paper can be fed smoothly as usual.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the upper structure of an optical system type electrostatographic copying machine in which the sheet feeding device A according to the present invention is applied to a document feeding device.

A document table 2 is provided on the upper surface of the upper part 1 of the copying machine, and a document B transferred onto a contact glass 5 by a sheet feeding device A, which will be described later, is further transported by a transport belt 3 and its leading end is stopped by a stopper 4. When locked and stopped at a predetermined position on the contact glass 5, the optical system 6 (only the lamp 6a and the reflecting mirror 6b are shown in FIG. 1) driven by a driving device (not shown) is shown by a solid line. The document B is reciprocated from the left and right positions to the right position shown by the imaginary line,
Is exposed, and when this is completed, the stopper B of the original B is released, and the original B is sent again to the original take-out port 7 side by the conveyor belt 3.

The paper feeding device A is provided on the upstream side of the document table 2 and, as shown in FIG. 2, comprises a paper feeding roller 8, an upper roller 9 for feeding and a lower roller 10 for returning. Device 11
And a pair of upper and lower registrars 12 and 13 are arranged in that order from the upstream side to the downstream side in the paper feeding direction. These rollers 8, 9, 10, 12, 13 are the conveyor belt 3, the stopper 4, and the stopper 4, respectively. The optical system 6 and the like are configured to operate while closely adjusting their timings, the details of which will be described later.

In the figure, reference numeral 15 is an upper guide plate, and 16 is a lower guide plate, which are provided in the conveyance path of the document B.

FIG. 3 shows the mounting relationship between the paper feed roller 8 and the conveying device 11. The upper paper feeding roller 9 constituting the conveying device 11 is made of, for example, natural rubber having a large frictional resistance, and is returned. The lower roller 10 for use is made of, for example, urethane rubber having a small frictional resistance, and is provided on shafts 18 and 19 which rotate in the same direction, respectively.

As shown in FIGS. 4 and 5, the upper rollers 9 and the lower rollers 10 are arranged alternately (staggered), and the inter-axis dimension l of the vertical shafts 18 and 19 is the upper roller 9 Radius of
If r ₉ and the radius of the lower roller 10 are r ₁₀ , then l <r ₉ + r ₁₀ is set, and 0.3 ≦ r ₉ + r depending on the axial installation distance between the upper roller 9 and the lower roller 10. It is set so that ₁₀ −l ≦ 0.8 mm.

Therefore, the document B passing between the upper roller 9 and the lower roller 10 usually has a curved shape with a slight wavy shape in the width direction as shown in FIG.
The sheet is fed to the downstream side in the sheet feeding direction by receiving the feeding force due to the difference in frictional resistance of 10.

The original B may be conveyed with a difference in peripheral speed between the upper roller 9 and the lower roller 10, and the wind speeds and materials of the rollers 9 and 10 are not limited.

As shown in FIGS. 5 and 6, the lower roller 10 is provided on the peripheral surface of the upper roller 9 when both rollers 9 and 10 are set.
Paper passing section with a concave curved surface cut around the center of rotation
9a is formed, and the paper passing portion 9a constitutes a passage gap 17 of the document B between the paper passage portion 9a and the peripheral surface of the lower roller 10 when viewed in the axial direction. The original B has a shape of the paper passing portion 9a so that the nipping force of the upper and lower rollers 9 and 10 hardly acts.

Two arms 20, 20 are pivotally attached to the mounting shaft 18 of the upper roller 9 with a predetermined gap in the axial direction, with their free ends directed upstream in the paper feeding direction. Arm 20,20
The paper feed roller 8 is attached to the shaft 21 extending over the free end of the above through a one-way clutch d.

A transmission mechanism 22 such as a toothed belt is provided across the shaft 21 and the upper roller shaft 18 so that the paper feeding roller 8 is rotated in the same direction in synchronization with the upper roller 9.

A weight W is provided across the free ends of the arms 20 and 20, and the paper feed roller 8 is pressed against the document B by the gravitational force of the weight W and the like.
It is designed to send out.

Then, as shown in FIGS. 9 to 11, the cam mechanism F described later separates the paper feed roller 8 in the first state D of the document feed from the document B in the second state E of the paper feed cancellation. It can be switched to.

The concrete structure of the transmission mechanism C is shown in FIGS. In the figure, G ₁ is an input gear, G ₂ and G ₅ are counter gears loosely fitted to the counter shaft 23, G ₃ is a gear provided on the upper roller shaft 18, and is provided in the feed clutch 24. In addition, it meshes with the counter gear G ₂ .

G ₄ is a transmission gear provided on the upper roller shaft 18, and G ₆ is a transmission gear provided on the lower roller shaft 19, both of which mesh with the counter gear G ₅ .

The transmission gears G ₄ and G ₆ are designed so that the shafts 18 and 19 rotate in synchronization with each other in the same direction when the feed clutch 24 is engaged.

As shown in FIGS. 12 to 15, the feed clutch 24 is provided with two clutch claws a and b for switching the clutch 24 to the disengaged state. And the clutch pawl
The solenoid 26 is attached to the locking piece 25 that selectively locks a and b.
When the solenoid 26 is in the non-excited state, as shown in FIGS. 12 and 13, the engaging piece 25 is in a position to engage with the clutch pawl a, and the solenoid 26 By excitation, as shown in FIGS. 14 and 15, the locking piece 25 is switched to a position where it engages with the other clutch pawl b.

Then, with the engagement piece 25 engaged with the clutch claw b and in the disengaged state, as shown in FIGS. 5, 6 and 11, the paper passing portion 9a of the upper roller 9 is viewed in the axial direction. It is configured to rotate so as to face the peripheral surface of the lower roller 10 so that the first posture X that forms the document passage gap 17 between the rollers 9 and 10 appears.

On the other hand, in the transmission released state in which the locking piece 25 is locked to the clutch claw a, the upper roller 9 slightly rotates in the sheet feeding direction from the state in which the document passage gap 17 is formed, and the upper roller 9 is rotated as shown in FIGS. As shown in FIG. 9, it is configured so that a second posture Y in which the peripheral surfaces of both rollers 9 and 10 overlap in the axial direction is exposed.

As shown in FIGS. 9 to 11, the leading edge of the document B is conveyed to the nip portion of the timing roller 14 by the rotation of the upper roller 9 while switching from the second posture Y to the first posture X. Is configured.

Now, the cam mechanism F is constructed as shown in FIGS. That is, the upper roller shaft 18 and a cam shaft parallel to the upper roller shaft 18.
27 transmission gears G ₇ and G ₉ are provided respectively, and both gears are
The G _7, G ₉ and the counter gear G ₈ meshes, furthermore, two of the cam 28 is provided on the cam shaft 27. And
A cam follower 29 for the cam 28 is connected to each of the arms 20 and 20, and is configured to swing the arms 20 and 20 in synchronization with the rotation of the upper roller 9.

Specifically, the first posture X in which the leading end of the document B reaches the nipping portion of the timing roller 14 and the document passing gap 17 is formed between the upper and lower rollers 9 and 10 appears (see FIG. 11). ), The paper feed roller 8 is in the first state D, and then the upper roller 9 rotates and the second state Y shown in FIG.
The paper feed roller can be switched from the first state D to the second state E before the appearance of.

That is, the rotation of the upper roller 9 until the second posture Y appears is equivalent to the phase angle θ of the clutch pawls a and b, and the cam 28 is synchronized with the rotation of the upper roller 9 during this period. The cam 28 and the cam follower 29 are shaped so that the cam surface of the cam 28 comes into contact with the cam follower 29 by this rotation and the sheet feeding roller 8 is switched from the first state D to the second state E. It is set.

Next, as shown in FIGS. 2 and 3, a member for supporting the paper feed roller 8, specifically, a pair of arms 20, 20 pivotally attached to the upper roller shaft 18, and the arm 20. The shaft 21 extends over the free ends of the paper feed rollers 20 and 20, and the paper feed roller 8 is pivotally attached to the shaft 21 via a one-way clutch d, and the paper feed roller 8 is gravitated with the paper feed roller 8 by its own gravity. 8 is pressed against the document B on the lower guide plate 16.

As shown in FIG. 2, the one-way clutch d permits the rotation of the paper feed roller 8 only in the clockwise direction. In other words, the one-way clutch d is arranged along the lower guide plate 16 from the document table. Of the original B, and the feeding movement of the original B by the paper feed roller 8, the conveying device 11, the registration rollers 12, 13 and the like. It has the function of a stopper to prevent this from moving.

Incidentally, in FIG. 2, reference numeral 31 denotes a case where a part thereof is a transparent portion 31a, and the set state of the document B can be visually confirmed from the outside through the transparent portion 31a.

The operation of the sheet feeding device A having the above configuration will be described with reference to FIGS.
This will be described with reference to FIGS.

First, in the second state E (shown by solid lines in FIGS. 2 and 9) in which the sheet feeding roller 8 releases the sheet, the document B is set from the document table 30 to the lower guide plate 16. Also, the paper feed roller 8 is provided with the one-way clutch d. When the original B is inserted, the paper feed roller 8 is also driven to rotate clockwise, so that the original B can be set smoothly, and the original B is also fed later. The roller 8 is pressed against the upper surface of the original by gravity with the weight W, but the paper feed roller 8 is provided with a one-way clutch d that allows the original B to move in the paper feed direction. Transport can be done smoothly.

Next, turn on the start switch while document B is set.
To rotate the input gear G ₁ . In this state, since the feed clutch 24 is in the disengaged state, only the gears G ₁ , G ₂ and G ₃ are rotating.

Next, when the paper feed switch (not shown) is turned on, the solenoid 26 is excited to release the locking of the locking piece 25 with respect to the clutch claw a until the clutch claw b acts on the locking piece 25. The upper roller shaft 18 rotates, and the gears G ₄ , G ₅ ,
The lower roller shaft 19 rotates via G _6, that is, the upper roller 9
Rotates from the second posture Y to the first posture X, and
In synchronization with this, the paper feed roller 8 and the lower roller 10 also rotate.

At the same time, the cam shaft 27 also rotates synchronously, the contact of the cam 28 with the cam follower 29 is released, and the paper feed roller 8 in the second state E is switched to the first state D (FIG. 10).

Then, by the drive rotation of the paper feed roller 8 switched to the first state D, as shown in FIG. 10, the uppermost document B is sent out to the downstream side in the paper feed direction, and next, the transport device 11 As shown in FIG. 11, the leading edge of the original B is received by the registration rollers 12, 13 due to the conveying force of the upper and lower rollers 9, 10.
At the same time or a little after the leading edge of the original B arrives at the nipping portion, and the clutch claw b abuts on the locking piece 25, and the upper roller 9 moves in the first posture X. In the state where the upper and lower rollers 9 and 10 are switched to each other, that is, in the state where the document passage gap 17 is formed between the upper and lower rollers 9 and 10, the drive to the upper and lower rollers 9 and 10 and the paper feed roller 8 is cut off, and The original B swells between the rollers and 9 and 10 so that a so-called loop is formed.

Here, the flat restoring force of the original B by the loop aligns the leading edge of the original B, and at the same time, the flat restoring force tends to return the original B in the direction opposite to the paper feeding direction. The movement of the document B in the reverse direction is restricted by the stopper function of the paper feed roller 8 in the non-rotatable state by the one-way clutch d that blocks the rotation in the counterclockwise direction. Therefore, it is possible to surely prevent the trouble of the sheet feeding failure due to the skewed sheet feeding due to the unevenness of the leading edge of the document and the returning movement of the document B.

When the document B is fed by the paper feed roller 8, the second document B may be fed together.
However, the second original B is not subjected to the conveying action of the upper roller 9 at all, and the tip of the second original B is brought into contact with the lower roller 10 rotating in the returning direction, so that the second original B is not advanced any further. Thus, the so-called double feeding of the original B is prevented.

Now, after the leading edge of the original B reaches the nip portion of the registration rollers 12 and 13, the registration rollers 12 and 13 are driven at a predetermined timing time, and the registration rollers 12 and 13 are driven.
The document 13 is conveyed to the downstream side in the sheet feeding direction as if the document B is pulled out from between the upper and lower rollers 9 and 10. As described above, the upper roller is provided between the upper and lower rollers 9 and 10 of the conveying device 11. Since the document passage gap 17 is formed by the sheet passing portion 9a of 9,
Thus, the paper is smoothly fed by the registration rollers 12 and 13 without causing wavy creases or wrinkles on the original B.

Next, when the feeding process by the registration rollers 12 and 13 is completed, the solenoid 26 is demagnetized and the clutch claw b
The engagement of the engagement piece 25 with respect to is released, the upper roller 9 rotates until the other clutch claw a comes into contact with the engagement piece 25, and the original second posture Y is revealed.

With the above, one document feeding is completed, and the document B transferred to the contact glass 5 side is conveyed by the belt 3, and when the leading end of the document B contacts the stopper 4, the conveyance belt 3 Is stopped, and after that, copying is performed based on the optical system 6, and after the copying is completed, the regulation of the front end of the stopper 4 for the original B is released, and the original B is taken out by the driving of the conveying belt 3. It is discharged to.

Further, as the paper passing portion 9a provided on the upper roller 9, as shown in FIGS. 16 (a) and 16 (b), a groove shape or a dovetail groove shape may be used.

Further, in order to switch between the first posture X and the second posture Y of the upper roller 9, the locking piece 25 is selectively locked to the two clutch claws a and b having different phases. Although the clutch pawls a and b are provided on the same circumference, the solenoid 26 may be repeatedly excited for a short period of time, or may be programmed.

Further, while the upper roller 9 makes one rotation, the
The posture X and the second posture Y are made to appear. However, the upper roller 9 has a large diameter and, for example, two sheet passing portions 9a are symmetrically provided on the peripheral surface of the upper roller 9 so that It may be configured such that the first posture X and the second posture Y are exposed once for each half rotation of the roller 9, and in this case, two cams 28 are of course provided so that the document passage gap 17 is reduced. It is essential that the paper feed roller 8 is switched to the second state E in synchronization with this every time it appears.

Further, the timing for switching the upper roller 9 to the second posture Y may be any time until the next paper feeding by the paper feeding roller 8 is started.

Further, in the embodiment, the document feeding device A for the document feeding device is described, but the paper feeding of the copying machine accommodated in the cassette case and the copying machine placed on the manual feed stand, and the transfer paper in the facsimile are performed. The present invention is also applicable to paper feeding and the like, and in the present invention, these originals and copying machines are collectively referred to as paper B.

(Effect of the Invention) As described above, according to the paper feeding device in the image forming apparatus of the present invention, the paper feeding roller that allows the movement of the paper only in the paper feeding direction is provided so as to act on the upper surface of the paper. As a result, the return movement due to the loop of the sheet formed between the conveying roller and the registration roller can be surely prevented by the stopper function of the sheet feeding roller. Forming a paper passage gap in the paper to make the paper convey smoothly, while at the same time deriving according to the shape of the paper passage gap, oblique feed of paper or occurrence of paper feed failure It has come to be possible to prevent it reliably.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional front view of a document feeding device to which the present invention is applied, FIG. 2 is a vertical cross-sectional view of a main part of a paper feeding device, and FIG. 3 is a perspective view of a paper feeding roller and a feeding roller and their transmission mechanisms. FIG. 4 and FIG. 4 are partial views of the conveying roller showing a paper feeding state, and FIG.
FIG. 6 and FIG. 6 are explanatory views showing a state in which a passage gap for a document or the like is formed. FIG. 7 is a configuration diagram of the transmission mechanism, and FIG. 8 is a Z-O- of FIG.
Sectional view taken along line Z, FIGS. 9 to 11 are explanatory views of sheet feeding by a sheet feeding device and a sheet feeding roller, FIGS. 12 to 15 are explanatory diagrams of operation of a feed clutch, and FIGS. 16 (a) to 16 (b). FIG. 17 is an explanatory view showing an embodiment of a paper passing portion provided on the upper roller 9, respectively.
FIG. 19 is an explanatory diagram of sheet feeding by a conventional sheet feeding device and a sheet feeding roller. 8 ... Paper feeding roller, 9 ... Upper roller, 9a ... Paper passing portion, 10 ... Lower roller, 11 ... Conveying device, 12, 13 ... Registration roller 14,20 ... Arm, 17 ... Paper passing gap 18, 19 ...... shaft, 20, 21 ...... feed roller supporting member, b ... one-way clutch, l ...... axial dimension between, r _9, r ₁₀ ...... roller radius, B ...... paper (document )

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03G 15/00 107 8530-2H

Claims (1)

[Scope of utility model registration request] 1. A sheet feeding direction from an upstream side to a downstream side,
A feed roller, an upper roller and a lower roller are alternately arranged on a pair of upper and lower shafts that rotate in the same direction, and a pair of upper and lower timing rollers are arranged. In a sheet feeding device of a copying machine in which the radius of each of the upper roller and the lower roller is set to be slightly smaller than the sum of the radii of the upper roller and the lower roller. A cutout portion that forms a passage gap is provided, and a one-way clutch is interposed between the paper feed roller and a drive shaft that drives the paper feed roller, and the leading edge of the paper reaches the nipping portion of the timing roller. From the time point until the paper feeding roller starts the next paper feeding and at least in the paper feeding process by the timing roller, the passing gap of the paper is exposed and the paper feeding roller is self-weighted. Paper feeding device in an image forming apparatus, characterized in that are configured to allowed to pressed onto the paper Te.