JPS63202530A - Paper feeding device - Google Patents

Abstract

PURPOSE:To stabilize conveying speed and prevent skew feeding by providing a conveying means which carries out the conveyance of a sheet of paper in cooperation with a roller. CONSTITUTION:Cut sheets 1 are stacked on a paper feeding tray 2 and the front end parts of the cut sheets 1 are pressed against feed rollers 14, 14' and rollers 15, 15' by means of a stacking board 13 which is energized by a paper feeding pressure spring 3 and rotated. When a driving shaft 17 starts to rotate, an oscillating cam is also rotated, the stacking board 13 is pushed up by means of the paper feeding pressure spring 3, and the cut sheets are pressed against the feed rollers 14, 14' and the idler rollers 15, 15'. However, since the frictional force between sheets of paper is larger than the frictional force between the idler rollers 15, 15' and the sheet of paper, the sheet of paper is not sent out. Whereas, nearly at the same time as or slightly before or after the pressing, as the outside diameter parts larger than those of the idler rollers 15, 15' of the paper feed rollers 14, 14' are rotated and brought into contact with the cut sheet, the cut sheet start to be sent out by means of the feed rollers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to paper feeding and conveyance of cut sheets in image forming apparatuses such as copying machines and printers.

[Prior Art] Conventionally, the paper feeding devices of copying machines and printers have used the method shown below to feed and convey a large number of cut sheets stacked one by one to an image forming section. .

Conventional examples are shown in FIGS. 6-8.

The transfer material 1 stacked on the paper feed tray 2 is pressed against a feed roller 4 by a paper feed pressure spring 3 . When the feeding roller 4 rotates, the transfer material 1 is caused by friction so that the leading edge of the transfer material 1 touches the paper guide 2.
′ to invade.

Friction coefficient ILs between the plurality of intruded transfer materials 1
and a friction coefficient μ3 between the feeding roller 4 and the transfer material l,
The relationship of the friction coefficient path 2 between the separation bat 6 pressed against the feeding roller 4 by the separation pressure spring 5 and the transfer material l is JL.
It is configured such that l × μ2 × μ3. The separation bat 6 of the plurality of overlapping transfer materials 1 by ILI μ 2
Conveyance stops starting from the one closest to , and finally lL*<
One sheet of transfer material 1a is conveyed by JLs passing between the feeding roller 4 and the separation pad 6. (See FIGS. 7 and 8) Immediately after passing between the feeding roller 4 and the separation bat 6, the conveying speed V at which the transfer material 1a is conveyed is intertwined! It is unstable because it changes depending on the balance of 2μ. The tip of the transfer material 1a is connected to the register roller pair 1:l
, 14, the drive of the feeding roller 4 is cut off. A one-way clutch (not shown) is attached to the feeding roller 4, and the feeding roller 4 is rotated by friction between the transfer material 1a and the feeding roller 4. When the rear end of the transfer material 1a leaves the feed roller 4, the feed roller 4 stops rotating and the next transfer material 1b is not transported.

Since the pressing force acting between the pair of register rollers 13 and 14 is sufficiently large compared to the frictional load between the transfer material 1a and the separation bat 6, the conveyance speed 2 for conveying the transfer material 1a is stable.

On the other hand, the light beam 9 emitted from the optical scanning section 8 forms an image on the photoreceptor 10 to form a latent image, and the latent image is developed with toner by a developing device. The toner image on the photoreceptor IO is transferred to the transfer material 1a at two points. The toner image on the transfer material la is fixed by a fixing device 12.

[Problem that the invention seeks to solve] However,
In the above-mentioned conventional example, paper feeding by the feeding roller 4 is performed using a separation pad 6 and the feeding roller 4 as means for separating multiple sheets of paper.
Since the frictional force p3 between the feeding roller 4 and the transfer material l is greater than the frictional force p2 between the separation pad 6 and the transfer material l, the separation pad 6 is always conveyed.
The transfer material 1 being conveyed is slipping. Therefore, a braking force is always applied to the conveying force of the feeding roller 4.

Moreover, since the braking force varies depending on the type, thickness, surface properties, and number of sheets of paper that have entered the friction member, there is a drawback that the conveyance speed v1 of the feed roller 4 is unstable. For this reason, in a conventional friction separation type paper feeding device, it is necessary to stabilize the conveyance speed vb at an image forming section that requires a stable conveyance speed, for example, an image transfer section 9 from the photoreceptor drum 10. , one pair of conveyance rollers, that is, a pair of register rollers 13 and 14 were provided between the feed roller 4 and the photosensitive drum 10. As a result, the device becomes larger, a driving force is required for the pair of register rollers 13, 14, and the provision of the pair of rollers 13, 14 leads to an increase in cost. Furthermore, even when the roller pair 13.14 is provided, the conveyance speed v4 for conveying the distance from the conveyance roller 4 to the roller pair 13.14 varies depending on the surface friction coefficient of the paper, the environment, etc. The paper could not reach roller pair 1:l, 14, resulting in poor feeding.

[Means for Solving the Problems (and Effects)] According to the present invention, in the cut sheet separation and feeding device, the cut sheet separated into one sheet after passing through the separation means is gripped by the conveying roller as soon as possible. However, by configuring the paper to feed stably, the conveying speed is stabilized and skew feeding is prevented.

[Example] 1 to 5 show embodiments using the present invention.

A large number of cut sheets 1 are stacked on a paper feed tray 2,
The leading end of the cut sheet l is moved between the feeding rollers 14 and 14 by the loading plate 13 which is biased by the feeding pressure spring 3 and rotates.
'' and is pressed by the idler rollers 15° and 15'.The feeding rollers 14 and 14' are rollers that partially have small diameter portions, and the cut sheet is placed at at least one location on one rotation (on the circumference). The roller width is set to be smaller in the width direction than the minimum paper size width fLain, as in this embodiment. You can divide it into two parts,
The feeding rollers l 4 , 14' are fixed to a drive shaft 17, and this drive shaft 17 is connected to a spring clutch 18 at the end of the shaft.
The solenoid 19 is configured to enable one-rotation control.

In addition, the maximum weight of paper size that can be passed through the drive shaft 17 is 1 wa
A swing cam 2 for swinging the loading plate 13 is located outside x.
0.20', and a cam follower 2 is provided at a position corresponding to the swing cam 20.20' on the loading plate 13.
1.21' are fixed, the stacking plate 13 moves up and down under the rotational control of the drive shaft 17, and the stacked cut sheets are selectively transferred to the feed rollers l4, 14' and the idler rollers 15. It is configured to be able to be pressed to Is'. Therefore, when the operator loads cut sheets into the apparatus, the loading plate 13 is in the lowered state as shown in FIGS. 1 and 3(a), so that the cut sheets can be loaded smoothly. Further, there is an advantage that the operator does not need to lower the loading plate 13.

Idler rollers 15 and 15' that rotate smoothly around the drive shaft 17 are arranged near both ends of the feed rollers 14 and 14' on the drive shaft 17.
The outer diameter of 5.15' is configured to be slightly smaller than the maximum diameter of the feeding rollers 14, 14', for example, by 0.5 to 1■■. The conveyance rollers 16, 16' are oscillated by a oscillating arm 22 around a drive input shaft 21, and the feeding rollers 14, 16' are oscillated by a oscillating arm 22 around a drive input shaft 21, and the feeding rollers 14, 16' are
14' idler roller is, is in pressure contact with 15'. The driving force to the conveyance rollers 16, 16' is transmitted by a drive gear 24 fixed to a drive input shaft 21 and a conveyance gear 25 fixed to the conveyance rollers 16, 16'. If the gear pair of the conveyance gear 25 is disposed at the center of the conveyance rollers 16 and 16', there will be no imbalance in the pressure contact force of the conveyance rollers due to the driving force, and stable pressure contact will be possible.

Feed rollers 14, 14' and idler roller 15. Is'
A friction member, for example, a separation bat 27 and 27' made of a rubber material containing cork, is in pressure contact with the cut sheet l, which is configured to pivotally support the center part and press the center part with a spring 26 while equalizing the part. separation. This separation bat 2
7.27' may also be divided as in this embodiment, and it is only necessary to separate the feeding path at least at the positions corresponding to the respective feeding rollers 14, 14'' and idler rollers 15, 15'. In a portion other than the butt 27.2τ portion, the cut sheet is guided by the paper guide shaped portion 28 and guided to the conveying rollers 16 and 16'.

Further, in this embodiment, a second cut sheet inlet 29 is provided at the nip portion between the conveyance rollers 16 and 16' and the idler rollers 15 and 1da, through which sheets from other than the paper feed tray 2 are introduced. This makes it possible to provide an optional feeding means such as a multi-sheet deck at the bottom of the apparatus main body and guide the sheets from the feeding means to the apparatus main body, making the apparatus highly expandable. Note that the feeding roller 14 and the roller 1
5 does not necessarily have to be a anniversary, and may be on a different axis; this is called approximately coaxial. The diameters of the rollers 14 and 15 may be approximately the same.

Conveyance rollers 16, 16' and idler rollers 15, 15
A sensor lever 30 is disposed on the downstream side of the nip portion, and this sensor lever 30 is pivotally supported by the swing arm 22 and rotates, and a photo interrupter 39 detects the leading edge of the cut sheet. This sensor is connected to sensor lever 3 as shown in the diagram.
0 and the photointerrupter 39, a transmission type sensor or a reflection type sensor may be used. After the sensor lever 30 for detecting the leading edge of the paper, the cut sheet l is guided by a guide portion 32 whose curvature is slightly larger than the curvature of the feeding rollers 14 and 14', and comes into contact with the photoreceptor drum 101 and rotates. Semi-conductive rubber roller that applies a bias of about IKVDC (104~'JΩC11)
It is guided to the nip part with the transfer roller part. The guide section 32 is connected to the developing device 10 located below the photoreceptor drum 101.
If constructed using the casing 2, it is easy to achieve precision with the drum, the number of parts is small, the assembly is easy, and the cost is low. The photoreceptor drum 101 has an exposure position A where it is exposed to laser light 202 from a laser scanning optical system section 201 on the left side of the cross-sectional view of the apparatus in FIG.
Development position B by development sleeve 103, transfer roller 33
Transfer position C by cleaning blade 105 of cleaner 104, cleaner position D by cleaning blade 105 of cleaner 104, corona charger 105
A primary charging section E using equal charging means is provided,
Perform image formation.

The cut sheet after the toner transfer that has passed through the transfer position NC is moved between a heat roller 35 having a built-in heater and a pressure roller 36 made of a heat-resistant elastic material such as silicone rubber, which applies pressure by a conveyance guide section 34 which also serves as a fixing entrance guide. The transferred image is guided to the nip section, and the transferred image is fixed by applying heat between the nips.The paper is then ejected to the outside of the apparatus by the ejecting roller 37 made of fins made of an elastic material such as rubber or Norsolex. be done.

Paper conveyance in the paper feed conveyance section of the present invention will be described in order. When a motor (not shown) serving as a drive source starts rotating before the paper feeding operation, the conveyance drive gear 38 fixed to the drive input shaft 21 of the conveyance rollers l 6 and I 6' rotates, and the drive input starts. Square axis 21. Rotation is transmitted to the conveying rollers 16 and 16' via the driving gear 24 and the conveying gear 25. The conveyance rollers 16, 16' are idler rollers 15. Since it is in pressure contact with Is', it is rotated by a pair of conveyance rollers 16 and l6' and idler rollers 15 and 15'. At that time, even if the idler roller 15.15' and the cut sheet l are in contact with each other, the frictional force between the cut sheet l and the separation pad 25.25' is greater than the frictional force between the idler roller 15.15' and the cut sheet l. Therefore, the cut sheet l will not be fed. However, during standby, as mentioned above, the a-mounting plate 13 is
．． 20' and the cam follower 21. Since the cut sheet is in the depressed position by the idler roller 1
It is not in contact with the 5,15' pair.

The feeding roller 15.15' is rotated by the rotation of the conveyance drive gear 38.
A paper feed drive gear 39 rotatably supported on the drive shaft 17 via a spring clutch 18 rotates. Solenoid 19 is OFF
In the F state, the rotation of the paper feed drive gear 39 is caused by the drive shaft 17.
A one-rotation control ring 40 is disposed in the spring clutch 18 portion that does not transmit power to the solenoid 19.
Drive transmission for one rotation is performed by the pulse. When the solenoid 19 is turned ON by the paper feed start signal, the control ring 4
When the claw o is released, the driving force of the paper feed drive gear 39 is transmitted to the drive shaft 17 via the spring clutch 18. Then, when the drive shaft 17 starts rotating, as shown in FIG. 3(b),
The swing cam 20 also rotates and is pushed up by the stacking plate 13 or the paper feed pressure spring 3, and the stacked cut sheets are pressed by the feed roller 14, 14' and the idler rollers 15, 15', but the rotation does not occur. Even if the paper is in contact with the moving idler roller, the paper will not be fed out because the frictional force between the paper and the paper is greater than the frictional force between the idler roller and the paper. The idler roller Is of 14 and 14', whose outer diameter is larger than that of 15', rotates to the part where it comes into contact with the cut sheet, so that the cut sheet is sent out by the feeding roller. Next, separation bat 2
Although the cut sheets reach the seventh section, only the topmost sheet of the cut sheets is guided to the downstream part of the separation pad 27 due to the relationship of the coefficient of friction as in the conventional example described above. after that,
The cut sheet soon reaches the driven conveyance rollers 16 and 16', and from this point on, the conveyance speed of the cut sheet is stabilized by the conveyance rollers 16 and 16', and the cut sheet reaches the next paper leading edge detection section H. By configuring the sheet to start writing one image (registration alignment) after the paper edge detection section H detects the paper edge, the cut sheet can continue to be conveyed by the conveyance rollers 16 and 16' without having to temporarily stop. . Therefore, the shock of ON/OFF of the register rollers does not appear in the image as in the conventional case. In order to control this edge detection and laser image writing, the paper path length Ll from the paper edge detection section H to the transfer section C is the circumference from the image exposure position A on the photosensitive drum 30 to the transfer section C. It must be longer than L2 (L2<L,).

In addition, if the paper sensing position by the sensor lever of the paper leading edge detection section H is placed near the inner side of the minimum paper width mark ■in on the opposite side to the reference side, it is possible for the user to accidentally Even if an attempt is made to convey a small paper, it can be blocked, and it is possible to prevent a paper smaller than the minimum paper stack size from being conveyed to the inside of the main body without being passed to the photosensitive drum. By performing this using the front end detection, image writing, and trigger sensors, image writing can be prevented, damage to the drum can be reduced, and it is also effective against dirt and the like.

[Other Embodiments] As an embodiment of the present invention, we have described the case where the minimum paper stack is Main and the maximum paper stack is l wax based on the 5-sided standard, but this is not limited to this. The method may be used. As shown in FIG. 4, the feeding rollers 14, 14', the idler rollers 15, 15', and the conveying rollers 16, 16' may have a continuous roller shape without being divided.

In FIG. 4(a), the idler roller 15 is arranged in the center, the feed rollers 14, 14' are placed at both ends, and the separation pads 27 are passed over the feed rollers 14, 14' at both ends to form an integral unit. It is also a whole. The conveyance roller 16 does not swing and apply pressure to the idler roller 15, but is supported by the bearing 4 by pressure springs 41 and 41' at both ends.
2.42', and the drive is transmitted from the conveyance drive gear 38 located outside during paper passing. Furthermore, the separation bat 24 may be pressed via the swing arm member 43. Further, as in this embodiment, the conveying roller 16 may be configured to contact only the idler roller. If configured in this way, the feeding rollers 14, 1
It is possible to avoid conveyance in a state where the paper is sandwiched between the rubber roller 4' and the conveyance roller 16, which have a high conveyance force, and it is possible to reduce the generation of paper dust and reduce the conveyance load.

In FIG. 4(b), the feeding roller 14 is arranged in the center, and idler rollers 15. Is' and its idler rollers 15 and 15' are brought into contact with the integral separation pad 27, and the conveying rollers 16 and 16' are arranged at positions corresponding to the idler rollers at both ends, and the driving force and pressure are applied to the central part. This is a method of giving from

Further, FIG. 5 shows another embodiment regarding the cross-sectional shape of the feeding roller of the present invention. In FIG. 5(a), the circular rubber portion 14 is eccentrically fixed to the drive shaft 17, which has the advantage of easy assembly and continuous and smooth contact with cut sheets, pads, etc. FIG. 5(b) has a cam-like rubber portion 14 whose diameter increases continuously.
This example also has the effect of smoothing the contact with cut sheets, pads, etc. FIG. 5(c) shows a configuration in which the feed roller is controlled not by one rotation but by half rotation at a time.

[Effects of the Invention] As explained above, by having a roller coaxially with the feeding means so as to be able to press against the roller, and having a conveying means that can obtain driving force from the roller, the materials can be loaded. The unstable paper feeding state in which only one cut sheet is separated and fed can be switched to a stable paper feeding state as quickly as possible, and stable paper feeding with less skew or lag is now possible.

In addition, as in the past, at least one
Compared to a device provided with a pair of register rollers, it is possible to obtain a paper feeding device that is more compact and inexpensive.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the device implementing the present invention, Figure 2 (a)
2(b) is a sectional view in the direction of arrow B, and FIG. 2(c) is a sectional view in the direction of arrow C. FIG. FIG. 3 is a sectional view taken in the direction of arrow D, FIG. 4(a) is a drive diagram of the paper feed system of another embodiment of the present invention, and FIG. 4(b) is a feed system drive diagram of still another embodiment of the present invention. Paper system drive diagram, FIG. 5(a) is a sectional view of the feeding roller of another embodiment (1) of the present invention, FIG. 5(b) is a feeding roller of another embodiment (2) of the present invention Cross-sectional view. Fig. 5(c) is a sectional view of the feeding roller of another embodiment (3) of the present invention, Fig. 6 is a sectional view of the conventional example, Fig. 7 is a detailed view of the separation part of the conventional example, and Fig. 8 is FIG. 3 is a detailed diagram of a separating section in a conventional example. l...cut sheet, 2...paper feed tray, 1
3... Loading plate, 14... Feeding roller, 1
5...Idler roller, 30...Sensor lever Fig. 2 (b) Fig. 2 (C) Male η Fig. /6 Fig. 5 <a>

Claims (1)

[Claims] (1) A feeding roller; Press the cut sheet against this feed roller side. a pressing means for It rotates freely almost coaxially with this feed roller. a movable roller, The cut sheet is cut in cooperation with this feeding roller. separation means for performing the separation; downstream of this separation means position, and works with the rollers to transport the paper. A paper feeding device comprising: a conveying means for carrying out