JP2003171026A - Paper feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve conveying power without giving unnecessary load to paper, prevent occurrence of failure such as overlapped feed, no feed, wrinkling, or folding, and improve conveying power even if the paper is curled or wavy. <P>SOLUTION: A paper feeding roller shaft 141 of which the rotation is driven by a driving source not illustrated is fitted with a solid rubber paper feeder 4 at a position corresponding to the central section of printing paper 62 in the width direction, on both sides of which hollow rubber auxiliary paper feeding rollers 142 are provided. The auxiliary paper feeding rollers 142 correct curls without giving unnecessary load to the printing paper 62 by means of its deforming function, thus improving the conveying power. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for separating sheets one by one and feeding them, a copying machine having the sheet feeding device,
The present invention relates to an image forming apparatus such as a printer, a facsimile, and a printing apparatus.

[0002]

2. Description of the Related Art In this type of paper feeding device, as shown in FIG. 13, for example, a paper feed table 200 on which paper P is loaded and an upper surface of the paper P loaded on the paper feed tray 200 are pressed into contact with each other. It has one sheet feeding roller 201 which is driven to rotate in a state and serves both for sheet feeding and separation. The paper feed table 200 is supported rotatably up and down with a shaft 202 as a fulcrum, and the paper P is fed by the urging force of the paper feed table pressing spring 203.
It is designed to press 1. A separation member 204 such as a separation pad is pressed against the paper feed roller 201 by the urging force of a spring 205, whereby the paper P is separated one by one from the top and fed toward the registration roller pair 206. To be done. As shown in FIG.
Is supported by a paper feed roller shaft 207 extending in the paper width direction orthogonal to the paper feed direction of the paper P, and one is provided at the central portion in the paper width direction. A configuration is also known in which a plurality of paper feed rollers 201 having the same structure are provided on the paper feed roller shaft 207 in two or three rows.

As shown in FIGS. 15 and 16, there is also known a structure having sheet feeding rollers for separating and calling.
Paper feed roller 201 for separation and paper feed roller 208 for calling
Have the same structure and have a U-shaped cross section.
It is housed in 9. The calling paper feed roller 208 is supported by a shaft 210 supported between the side plates of the paper feed arm 209, and the shaft 210 and the paper feed roller shaft 207 are configured to rotate synchronously by a drive transmission belt 211. . The paper feed arm 209 is vertically rotatable about a paper feed roller shaft 207 as a fulcrum, and a pressure arm 212 is in contact with the upper surface of the paper feed arm 209. Pressure arm 21
2 is rotatably provided about a shaft 213 as a fulcrum,
The sheet feeding roller 208 for calling is pressed against the upper surface of the sheet P by the urging force of the pressure spring 214. The paper feed pressure can be adjusted by adjusting the biasing force of the pressure spring 214. The paper feed tray 215 is provided so as to be movable up and down, and presses the upper surface of the paper P against the paper feed roller 208. As shown in FIG. 17, in the registration roller pair 206, the drive shaft 206 a has the drive belt 216 and the registration motor 2
The sheet feeding roller 201 for separation and the sheet feeding roller 208 for calling are rotated by being driven to rotate by the sheet feeding roller shaft 207 via the driving belt 218.
It is rotated by being rotationally driven by 19. FIG. 17
The paper feed arm 209 is omitted.

Disk-shaped paper pressing members are arranged on both sides on the same axis of the paper feeding roller arranged in the central portion, and when the paper is curled upward, the paper pressing members correct the curl of the paper. There is also known a configuration in which the sheet is made to enter the guide plate entrance. There is also a paper pressing member in which a rubber ring is wound around the outer circumference. JP-A-6-34
Japanese Patent No. 0343 discloses a configuration in which a central portion is a normal paper feeding roller and large diameter hollow rollers are integrally formed on both sides in the axial direction thereof. At the time of paper feeding, the hollow portions on both sides are crushed to increase the peripheral speed of both side portions from the central portion, so that the central portion of the paper is bid up to improve the separation performance.

[0005]

The paper to be fed has a smooth front surface (the surface contacting the paper feed roller) and a low friction coefficient, and the back surface is rugged and has a high friction coefficient or curled or wavy paper. In the case of paper, in the conventional configuration in which one paper feed roller is arranged, a sufficient conveying force cannot be obtained, and a non-feed is likely to occur. Even if the pressure of the paper feed roller is increased to make up for the lack of conveyance power of the paper feed rollers, the force pushing between the paper sheets also increases, which increases the adhesive force between the paper sheets and easily causes double feed. . In a printing process using ink such as stencil printing, there is a tendency that the ink causes waves on the paper and the friction coefficient between the papers becomes high. Waves are generated in the area where the ink is transferred because the paper easily expands due to the water content of the ink. Therefore, when a load is applied to the paper at the time of paper feeding, the paper feeding performance is likely to be deteriorated (double feeding, non-feeding, wrinkles, folds, etc.).

In a configuration in which a plurality of paper feed rollers having the same structure are arranged or a disc-shaped paper pressing member having high rigidity is provided, if the paper feed pressure is increased to prevent non-feeding, unnecessary load is applied to the paper. And double feed and wrinkles are likely to occur. With such a configuration, the carrying force is high, but when the paper is curled upward or corrugated, the contact of the rollers becomes insufficient and the carrying force decreases. Further, the pressing force of the roller locally acts on the one-side contact of the rollers, so that the sheets are brought into close contact with each other and double feeding easily occurs. Also, in the configuration provided with a disk-shaped paper pressing member, when the number of sheets of paper loaded is large or the paper is stiff, the disk part becomes overloaded and problems such as non-feeding, wrinkling, and double feeding occur. It was easy. In the configuration described in Japanese Patent Application Laid-Open No. 6-340343, the paper is deformed by the crushing of the hollow rollers on both sides, which may cause an unnecessary load on the paper and increase the occurrence of wrinkles and folds.

Therefore, the present invention is directed to a sheet feeding device capable of improving the carrying force without giving unnecessary load to the sheets and without increasing the adhesion force between the sheets, and an image forming apparatus having the sheet feeding device. Providing is its main purpose.

[0008]

In order to achieve the above object, in the invention according to claim 1, the paper feed table on which the paper is stacked and the upper surface of the paper stacked on the paper feed table are pressed into contact with each other. In a paper feeding device having a paper feeding roller that is driven to rotate in a state and serves both for paper feeding and for separation, the paper feeding roller is provided at a central portion in the width direction of the paper, and the paper feeding rollers are provided on both sides of the paper feeding roller. A configuration is adopted in which auxiliary paper feed rollers having a rigidity lower than that of the paper feed rollers are coaxially provided at intervals in the width direction.

According to a second aspect of the present invention, in the sheet feeding device according to the first aspect, a plurality of the auxiliary sheet feeding rollers are provided on both sides of the sheet feeding roller.

According to the third aspect of the present invention, the sheet feed table on which the sheets are stacked and the sheet feed table loaded on the sheet feed table are rotationally driven in a state of being pressedly contacted and provided with a space in the sheet feeding direction. In the sheet feeding device having the separating and calling sheet feeding rollers, the sheet feeding rollers are provided in the central portion in the width direction of the sheet, and the sheet feeding rollers are provided on both sides of the sheet feeding roller for calling. A configuration is adopted in which auxiliary sheet feed rollers having a rigidity lower than that of the sheet feed roller for calling are coaxially provided at intervals in the width direction.

According to a fourth aspect of the invention, in the sheet feeding apparatus according to the third aspect, a plurality of the auxiliary sheet feeding rollers are provided on both sides of the calling sheet feeding roller. .

According to the invention of claim 5, claims 1 to 4 are provided.
In the paper feeding apparatus described in any one of 1 to 3, the auxiliary paper feeding roller has a hollow structure.

According to a sixth aspect of the invention, the first to fifth aspects of the invention are provided.
In the sheet feeding device described in any one of 1 to 3, the auxiliary sheet feeding roller is provided so that the position of the sheet in the width direction can be adjusted.

According to a seventh aspect of the present invention, a sheet feed table on which sheets are stacked is provided, and the sheet is stacked on the sheet feed table. In the paper feeding device having the separating and calling paper feeding rollers, a plurality of the calling paper feeding rollers are provided at intervals in the width direction of the paper, and these calling paper feeding rollers are provided. Is configured so as to be independently movable in the direction of approaching and separating from the paper.

According to an eighth aspect of the present invention, in the sheet feeding device according to the seventh aspect, the contact pressure of each of the sheet feeding rollers for calling can be independently set. .

In the invention described in claim 9, claim 7 or 8
In the paper feeding device described above, the calling paper feeding roller has a low-rigidity structure except for the one located at the central portion,
Is adopted.

According to a tenth aspect of the present invention, in the sheet feeding device according to the ninth aspect, the calling sheet feeding roller not located at the central portion has a hollow structure.

According to an eleventh aspect of the invention, in the sheet feeding device according to the ninth or tenth aspect, the sheet feeding roller for calling which is not located in the central portion is provided so that the position in the width direction of the sheet can be adjusted. Is adopted.

According to a twelfth aspect of the invention, in the image forming apparatus for separating the sheets one by one by the sheet feeding device and sending the sheets to the transfer section, and transferring the image to the sheet at the transfer section, According to any one of items 1 to 11,
Is adopted.

[0020]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. First, based on FIG. 4, an overall configuration of a stencil printing apparatus as an image forming apparatus and an outline of a stencil printing process will be described. A document reading unit 80 is provided on the upper portion of the apparatus main body 50, and a porous printing drum 101 is provided on the lower center portion thereof.
The print drum unit 100 having the above is provided. A plate making device 90 is provided on the upper right side of the printing drum unit 100.
A plate discharge unit 70 is provided on the upper left side of the printing drum unit 100. Further, below the plate making device 90, the paper feeding device 11 is provided.
0 is the printing pressure unit 120 below the printing drum unit 100,
Paper discharge units 130 are provided below the plate discharge unit 70 (claim 12).

Next, the printing operation of the stencil printing machine having the above structure will be described. First, a document 60 having an image to be printed is placed on a document placing table (not shown) arranged above the document reading section 80, and a plate making start key on the operation panel (not shown) is pressed. With the press of this plate-making start key,
First, the plate discharging process is executed. That is, in this state, the used heat-sensitive stencil master 6 used in the previous printing on the outer peripheral surface of the printing drum 101 of the printing drum unit 100.
1b remains attached.

The print drum 101 rotates counterclockwise,
When the rear end portion of the used heat-sensitive stencil master 61b on the outer peripheral surface of the printing drum 101 approaches the plate discharging / peeling roller pair 71a, 71b, the plate discharging / peeling roller pair 71a, 71b rotates and one plate discharging / peeling roller pair 71a rotates. The rear end of the used heat-sensitive stencil master 61b is scooped up. The used heat-sensitive stencil master 61b is composed of a pair of plate discharge peeling rollers 71a, 71.
Into the plate discharge box 74 while being conveyed in the arrow Y1 direction by the plate discharge conveyance belt pair 72a, 72b which is wound around the plate discharge roller pair 73a, 73b arranged on the left side of b and the plate separation roller pair 71a, 71b. Ejected and printed drum 101
The plate is peeled off from the outer peripheral surface, and the plate discharging process is completed. At this time, the print drum 101 continues to rotate in the counterclockwise direction. The used heat-sensitive stencil master 61b that has been peeled and discharged is then removed by the compression plate 75 from the plate discharge box 74.
Compressed inside.

In parallel with the plate discharging step, the original reading section 80 reads the original. That is, the original document 60 placed on the original document placing table (not shown) is rotated by the separation roller 81, the front original document conveying roller pair 82a and 82b, and the rear original document conveying roller pair 83a and 83b, respectively.
It is used for exposure reading while being conveyed in three directions. At this time, when there are many originals 60, only the lowermost original is conveyed by the action of the separating blade 84. The image of the original 60 is read by a CCD (charge coupled device) through a lens 88 by reflecting light reflected from the surface of the original 60 illuminated by a fluorescent lamp 86 while being conveyed on the contact glass 85 by a mirror 87. This is performed by making the light incident on the image sensor 89. That is, the original 60 is read by a well-known reduction type original reading method, and the original 60 from which the image is read is discharged onto the original tray 80A. The electric signal photoelectrically converted by the image sensor 89 is input to an analog / digital (A / D) conversion substrate (not shown) in the apparatus body 50 and converted into a digital image signal.

On the other hand, in parallel with this image reading operation,
A plate making process and a plate supplying process are performed based on the image information converted into a digital signal. That is, the roll-shaped heat-sensitive stencil master 61 set at a predetermined portion of the plate making device 90 is pulled out from the roll state, and is pressed by the thermal head 91 via the heat-sensitive stencil master 61.
2, and the pair of tension rollers 93a and 93b are rotated to convey to the downstream side of the conveying path. With respect to the heat-sensitive stencil master 61 conveyed in this manner, a plurality of minute heat generating portions arranged in a line on the thermal head 91 respond to a digital image signal sent from an A / D conversion board (not shown). Then, the thermoplastic resin film (described later) of the heat-sensitive stencil master 61, which selectively generates heat and is in contact with the heat-generating portion that generated heat, is melt-punched. In this way, by the position-selective melting perforation of the heat-sensitive stencil master 61 according to the image information,
The image information is written as a perforation pattern.

The front end of the plate-making heat-sensitive stencil master 61a in which the image information is written is sent toward the outer peripheral side of the printing drum 101 by the plate feeding roller pair 94a, 94b, and is moved downward by a guide member (not shown). To the master clamper 102 (shown in phantom) where the printing drum 101 is in the plate feeding position shown in FIG. At this time, the used heat-sensitive stencil master 61b has already been removed from the printing drum 101 by the plate discharging process.

The tip of the plate-made heat-sensitive stencil master 61a is
When the printing drum 101 is clamped by the master clamper 102 at a constant timing, the printing drum 101 gradually winds the plate-made heat-sensitive stencil master 61a around the outer peripheral surface while rotating in the direction A (clockwise direction) in the drawing. The rear end of the plate-made heat-sensitive stencil master 61a is cut into a certain length by a cutter 95.

When one plate-made heat-sensitive stencil master 61a is wound around the outer peripheral surface of the printing drum 101, the plate making and plate feeding steps are completed and the printing step is started. First, the paper feed table 51
The uppermost one of the printing papers 62 as the papers stacked on the uppermost one of the printing papers 62 is the registration roller pair 1 by the paper feeding roller 140.
It is sent out in the direction of the arrow Y4 toward 42, and is further sent to the printing pressure part (image transfer part) 120 by the registration roller pair 142 at a predetermined timing synchronized with the rotation of the drum part 100. The printing paper 62 sent out is the printing drum 1.
01 between the press roller 103 and the press roller 103, the press roller 103 was separated below the outer peripheral surface of the printing drum 101.
Is moved upward, so that it is pressed by the plate-prepared heat-sensitive stencil master 61a wound around the outer peripheral surface of the printing drum 101. In this way, ink oozes out from the perforated part of the printing drum 101 and the perforation pattern part (both not shown) of the plate-making heat-sensitive stencil master 61a, and this oozing ink is transferred to the surface of the printing paper 62 to produce a printed image. Is formed.

At this time, on the inner peripheral side of the printing drum 101, an ink reservoir 107 formed between the ink supply pipe 104 and the ink roller 105 and the doctor roller 106.
The ink is supplied to the inner surface of the print drum 101 while rotating in the same direction as the print drum 101 and in synchronization with the rotation speed of the print drum 101. Supplied to the circumference side.

The printing paper 62 on which the printing image is formed in the printing unit 120 is peeled off from the printing drum 101 by the paper ejection peeling claw 114, and is adsorbed by the adsorption fan 118, while adsorbing and ejecting the inlet roller 115 and the adsorption and ejection. By the counterclockwise rotation of the conveyor belt 117 that is stretched around the paper outlet roller 116, the conveyor belt 117 is conveyed toward the paper ejection unit 130 as indicated by arrow Y5, and is sequentially ejected and stacked on the paper ejection tray 52. In this way, so-called test printing is completed. Next, set the number of prints with a numeric keypad (not shown), and press a print start key (not shown) to repeat the steps of paper feeding, printing, and paper discharge by the set number of prints in the same process as the above-mentioned test printing. The whole process of stencil printing is completed.

The sheet feeding device 110 is provided with a sheet feeding table 51 which is supported so as to be able to move up and down and on which printing sheets 62 are stacked, and a detection / control section (not shown) which controls the stopping of the sheet feeding table 51 at an appropriate height. A paper feed roller 1 that feeds the printing papers 62 stacked on the paper feed tray 51 at an appropriate paper feed height to the downstream side in order from the uppermost one.
40, a front plate 143 for aligning the leading ends of the printing papers 62 stacked on the paper feed table 51 in the transport direction, and a pair of registration rollers 142.
And so on. Similar to the conventional configuration shown in FIG. 13, there is no sheet feeding roller for calling, and the sheet feeding roller 140 serves both for sheet feeding and separation. Although not shown, the separation pad is pressed against the paper feed roller 140 by a spring, and the printing papers 62 are separated one by one in this separation unit in order from the uppermost one. The driving structure of the paper feed roller 140 is
As in the case shown in FIG. 17, the sheet feeding motor (not shown) which is a stepping motor is rotationally driven. Similarly, the registration roller pair 142 is rotationally driven by a registration motor (not shown) which is a stepping motor.

As shown in FIG. 1, the paper feed roller 140 is a paper feed roller shaft 1 rotatably driven by a paper feed motor (not shown).
41, it is provided so as to be located in the center of the printing paper 62 in the width direction, and has an auxiliary rigidity lower than that of the paper feeding roller 140 at both sides of the paper feeding roller 140 at intervals in the width direction of the printing paper 62. The paper feed roller 142 is provided coaxially with the paper feed roller 140 (not shown in FIG. 1; claim 1). The paper feed roller 140 and the auxiliary paper feed roller 142 have substantially the same diameter. As shown in FIG. 2, the paper feed roller 140 has a core metal 144 having an annular groove 144a on the outer circumference and a shaft insertion hole 144b for the paper feed roller shaft 141 at the center.
And a roller body 145 made of solid rubber fitted in the annular groove 144a of the core metal 144. Core 14
One-way clutch 146 is built in 4 so that it can rotate only in one direction.

As shown in FIG. 3, the auxiliary sheet feeding roller 142 has a core metal 147 having an annular groove 147a on the outer periphery and a shaft insertion hole 147b for the paper feeding roller shaft 141 at the center, and the core metal 147. It has a roller body 148 made of a hollow rubber and fitted in the annular groove 147a. That is, the rigidity of the paper feed roller 140 is reduced by the hollow structure (claim 5). A one-way clutch 149 is built in the core metal 147 so that it can rotate only in one direction, which is the same direction as the paper feed roller 140. Although not shown, the auxiliary sheet feeding roller 142 can be fixed in position at an arbitrary position in the axial direction of the sheet feeding roller shaft 141 by a stopper (not shown). That is, the auxiliary paper feed roller 142 is provided so that its position can be adjusted in the width direction of the printing paper 62 (claim 6). As the stopper structure, for example, a structure that can be fixed to an arbitrary position on the paper feed roller shaft 141 with a screw may be arranged on both sides of the auxiliary paper feed roller 142. Further, a structure may be used in which the auxiliary paper feed roller 142 is rotatably supported by a bearing or the like and can be fixed to an arbitrary position on the paper feed roller shaft 141 by a screw.

FIG. 5 shows a paper feed state when the printing paper 62 is curled upward. Since the auxiliary paper feed rollers 142 on both sides are deformed according to the curl of the printing paper 62, it is possible to convey the printing paper 62 without applying an unnecessary load while suppressing the curl. As described above, since the auxiliary paper feed roller 142 can be moved to an arbitrary position, by moving the auxiliary paper feed roller 142 according to the size and the deformed state of the printing paper 62, it is possible to always feed paper in an optimum state. It will be possible. FIG. 6 shows a paper feeding state when the printing paper 62 is wavy. Also in this case, since the auxiliary paper feed rollers 142 on both sides are deformed along the convex portions of the wave, it is possible to convey the printing paper 62 without applying an unnecessary load while suppressing the wave. In the case of wave, as in the case of curl, the printing paper 62
By moving the auxiliary paper feed roller 142 according to the size and deformation state of the paper, it is possible to always feed paper in the optimum state.

The lowering of the rigidity of the auxiliary sheet feeding roller 142 is not limited to the hollow structure, and may be embodied by a foaming material such as sponge or urethane foam. In the case of the hollow structure, the inside is not gradually clogged and the low rigidity is not hindered as compared with the foamed material, so that it is advantageous in that the pressure on the printing paper 62 can be made uniform regardless of the degree of deformation. . Also,
The hollow structure can also be realized by making a large number of holes on the side surface of the solid paper feed roller or by removing the meat. The pressure of the auxiliary paper feed roller 142 can be adjusted by the number of holes to be opened. In the above-described embodiment, one auxiliary sheet feeding roller 142 is provided on each side of the sheet feeding roller 140, but as shown in FIG. 7, two auxiliary feeding rollers 142 may be provided on each side. (Second embodiment. Claim 2).

Next, a third embodiment will be described with reference to FIGS. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and unless otherwise necessary, the description of the configuration and the function that has already been made will be omitted and only the main parts will be described (the same applies to other embodiments below). The configuration in this embodiment is
This is a type having the separating and calling (feeding) feed rollers shown in FIG. Paper feed roller 140 for separation
The sheet feeding rollers 150 for calling are provided at intervals in the sheet feeding direction. The calling paper feed roller 150 is supported by a shaft 152 supported between the side plates of the paper feed arm 151, and the shaft 152 and the paper feed roller shaft 141 are configured to rotate synchronously by a drive transmission belt 153. . On both sides of the calling paper feed roller 150, auxiliary paper feed rollers 154 having a rigidity lower than that of the paper feed roller 150 are coaxially arranged independently of the paper feed roller 150 at intervals in the width direction of the printing paper 62. (Claim 3). Paper feed roller 14 for separation
0, paper feeding roller 150 for calling, auxiliary paper feeding roller 154
Have approximately the same diameter. Paper feed roller 140 and paper feed roller 15
0 has the same structure and the same function, and the auxiliary paper feeding roller 154
Has the same structure and the same function as the auxiliary paper feeding roller 142 in the first embodiment. That is, the paper feed roller 1
40 and the paper feed roller 150 have a solid structure, and the auxiliary paper feed roller 154 has a hollow structure.

The paper feed arm 151 is vertically rotatable about a paper feed roller shaft 141 as a fulcrum, and a pressure arm 155 similar to that shown in FIG. 15 is provided on the upper surface of the paper feed arm 151. It is in contact (omitted in FIG. 8). The pressure arm 155 is rotatably provided with a shaft 156 as a fulcrum, and the calling paper feed roller 150 and the auxiliary paper feed roller 154 are pressed against the upper surface of the printing paper 62 by the urging force of the pressure spring 157. By adjusting the biasing force of the pressure spring 157, the sheet feeding pressure can be adjusted. The biasing force of the pressure spring 157 can be adjusted, for example, by moving the rack with a stepping motor and changing the length of the pressure spring 157 according to the movement of the rack. In this embodiment, one auxiliary sheet feeding roller 154 is provided on each side of the sheet feeding roller 150, but two auxiliary sheets (a plurality of sheets) may be provided on each side (claim 4). Also in this embodiment, the auxiliary paper feed roller 154 can be moved in the width direction of the printing paper 62. Therefore, it is possible to always feed paper in an optimum state according to the size and the deformation state of the printing paper 62.

Next, a fourth embodiment will be described with reference to FIGS. In the present embodiment, as shown in FIG. 11, the separation roller 140 and the calling roller 150 are housed in the sheet feeding arm 158 to form a triple connection. Therefore, a plurality of paper feed rollers 150 for calling are provided at intervals in the width direction of the printing paper 62, and these paper feeding rollers 150 for calling are independent in the direction of approaching and separating from the printing paper 62. And is provided so as to be movable (claim 7). In the present embodiment, the contact pressure of each calling paper feed roller 150 with respect to the printing paper 62 can be set independently (claim 8). Each of the pressure springs 157 may be configured to be manually adjusted by a lever. As shown in FIG. 10, each pressure spring 157 has a motor (stepping motor) M1, M.
2 and M3 are adjusted independently. As shown in FIG. 12, when the adjustment amount is input through the operation panel 161, the control unit 160 controls M1, M2, and M3 based on the input information, and the paper feed rollers for calling the print paper 62 are provided. Adjust the contact pressure of 150. The control means 160 includes a CPU, ROM, RAM, I /
It is a microcomputer including an O interface and the like. The control unit 160 can also serve as the main controller of the stencil printing apparatus. Each sensor detects the amount of movement of the pressure arm (amount pushed up by the paper) and automatically sets the contact pressure (for example, when the amount of push-up is large, the pressure is small, and when the amount of push-up is small, the pressure is small). Can be large).

In FIG. 11, a paper feed roller 140 for separation is provided.
May be only one in the central part. Further, the paper feeding roller 150 for calling may be configured to have a low rigidity structure except for the one located at the center (claim 9). That is, the paper feed rollers 150 on both sides may have the same hollow structure as the auxiliary paper feed roller 154 (claim 10). In this case, the paper feed arm units on both sides (paper feed arm 15
8, paper feed roller 140, paper feed roller 150) as printing paper 62
The position may be adjusted by the stopper configuration in the width direction of the (claim 11). With this configuration, as in the above-described embodiment, it is possible to always feed paper in an optimal state according to the size and the deformed state of the printing paper 62.

[0039]

According to the invention of claim 1 or 12,
In a paper feeding device having a paper feed table on which paper is stacked and a paper feed roller which is rotationally driven in a state of being in pressure contact with the upper surface of the paper stacked on the paper feed table and serving both as a paper feed and a separation, A paper roller is provided at the central portion in the width direction of the paper, and auxiliary feeding rollers having a rigidity lower than that of the paper feeding roller are coaxially provided on both sides of the paper feeding roller at intervals in the width direction of the paper. Since the configuration is adopted, the pressure on the paper can be suppressed as low as possible in the auxiliary paper feed rollers on both sides as compared to the paper feed roller in the central portion, and the peripheral speed difference is less likely to occur. Therefore, it is possible to improve the conveying force of the paper feed rollers without deforming the sheets and without increasing the adhesion between the sheets, and it is possible to prevent double feeding, non-feeding, wrinkles, and folds. Further, it is possible to reduce the non-feeding due to the curl correction of the paper in the upward curl or the double-sided printing and the multicolor printing.

According to the invention described in claim 2 or 12, in the paper feeding device according to claim 1, the plurality of auxiliary paper feeding rollers are provided on both sides of the paper feeding roller, respectively. The conveying force can be further improved without giving unnecessary load to the sheet.

According to the third or twelfth aspect of the present invention, the paper feed table on which the sheets are stacked, and the upper surface of the sheets stacked on the paper feed table are rotationally driven in a state of being pressed and in contact with each other in the sheet feeding direction. In a sheet feeding device having separate sheet feeding rollers for calling and sheet feeding, the sheet feeding rollers are provided at the central portion in the width direction of the sheet, and both sides of the sheet feeding roller for calling are provided. Since a supplementary sheet feeding roller having a rigidity lower than that of the sheet feeding roller for calling is provided on the same axis at intervals in the width direction of the sheet, it is possible to obtain stable transportability. In the lower part, it is possible to improve the conveying force of the sheet feed rollers without deforming the sheets and without increasing the adhesive force between the sheets, and it is possible to prevent double feeding, non-feeding, wrinkles, and folds.

According to the invention of claim 4 or 12, in the paper feeding device of claim 3, a plurality of the auxiliary paper feed rollers are provided on both sides of the calling paper feed roller. Therefore, the carrying force can be further improved without giving unnecessary load to the paper.

According to the invention described in claim 5 or 12, in the paper feeding device according to any one of claims 1 to 4, the auxiliary paper feeding roller has a hollow structure.
The pressing force on the paper can be made uniform, and an unnecessary load on the paper can always be prevented.

According to the sixth or twelfth aspect of the invention, in the sheet feeding device according to any one of the first to fifth aspects, the auxiliary sheet feeding roller is provided so that the position of the sheet in the width direction can be adjusted. With this configuration, the position of the auxiliary paper feed roller can be adjusted according to the paper size and the deformed state of the paper, and the paper can always be fed in the optimum state.

According to the seventh or twelfth aspect of the present invention, the paper feed table on which the sheets are stacked is driven and rotated in a state of pressingly contacting the upper surface of the paper stacked on the paper feed table, and is spaced in the paper feeding direction. In a sheet feeding device having separate sheet feeding rollers for calling and separating, a plurality of sheet feeding rollers for calling are provided at intervals in the width direction of the sheet, and for calling these sheets. Since the paper feed rollers are configured so that they can move independently in the direction of contact with and away from the paper, there is no unnecessary load between the paper even if the paper has a large curl or wave. , The non-feeding prevention function can be improved.

According to the eighth or twelfth aspect of the present invention, in the sheet feeding device according to the seventh aspect, the contact pressure of each of the sheet feeding rollers for calling can be independently set. Therefore, the contact pressure can be adjusted according to the deformed state of the sheet, and the sheet can always be fed in the optimum state.

According to the ninth or twelfth aspect of the present invention, in the sheet feeding device according to the seventh or eighth aspect, the calling sheet feeding rollers have a low-rigidity structure except those located at the central portion. Since the configuration is adopted, the pressure on the paper can be suppressed as low as possible in the paper feed rollers on both sides as compared with the paper feed roller in the central portion, and the peripheral speed difference is less likely to occur. Therefore, it is possible to improve the carrying force of the paper feed roller without deforming the paper and without increasing the adhesive force between the paper, and to perform the double feeding,
It can prevent misfeeds, wrinkles, and breaks. Further, it is possible to reduce the non-feeding due to the curl correction of the paper in the upward curl or the double-sided printing and the multicolor printing.

According to the invention of claim 10 or 12,
The sheet feeding device according to claim 9, wherein the sheet feeding roller for calling which is not located in the central portion has a hollow structure, so that the pressing force against the sheet can be made uniform and It can always prevent unnecessary load.

According to the invention of claim 11 or 12,
The sheet feeding device according to claim 9 or 10, wherein the call-up sheet feeding roller that is not located in the central portion is provided so that the position in the width direction of the sheet can be adjusted. The position of the auxiliary paper feed roller can be adjusted according to the deformed state, and the paper can always be fed in the optimum state.

[Brief description of drawings]

FIG. 1 is a schematic side view of a main part of a paper feeding device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a paper feed roller.

FIG. 3 is a schematic sectional view of an auxiliary paper feed roller.

FIG. 4 is a schematic front view of a stencil printing apparatus as an image forming apparatus.

FIG. 5 is a schematic side view showing a paper feed state when the paper is curled upward.

FIG. 6 is a schematic side view showing a paper feed state when paper is wavy.

FIG. 7 is a schematic side view of a main part of a paper feeding device according to a second embodiment.

FIG. 8 is a schematic perspective view around a paper feed roller in the third embodiment.

FIG. 9 is a schematic side view of the vicinity of a paper feed roller in the third embodiment.

FIG. 10 is a schematic side view around a sheet feeding roller in a fourth embodiment.

FIG. 11 is a schematic plan view of the periphery of a paper feed roller in the fourth embodiment.

FIG. 12 is a control block diagram according to a fourth embodiment.

FIG. 13 is a schematic front view of a sheet feeding device of the type having one sheet feeding roller that doubles as sheet feeding and separation in the related art.

FIG. 14 is a schematic plan view showing the position of the paper feed roller with respect to the paper in the configuration shown in FIG.

FIG. 15 is a schematic front view of a sheet feeding device of a type having a sheet feeding roller for separation and a sheet feeding roller for calling in the related art.

16 is a schematic side view of the configuration shown in FIG.

17 is a schematic perspective view showing a drive mechanism in the configuration shown in FIG.

[Explanation of symbols]

51 paper tray 62 printing paper as paper 140 Paper feed roller for both paper feed and separation 142,154 Auxiliary paper feed rollers 150 paper feed rollers for calling

Claims (12)

[Claims] 1. A paper feed having a paper feed tray on which paper is loaded, and a paper feed roller that is rotatably driven in a state of pressingly contacting the upper surface of the paper loaded on the paper feed tray and that serves both as a paper feed and a paper feed. In the apparatus, the paper feed roller is provided in the widthwise central portion of the paper, and
A sheet feeding device, characterized in that auxiliary sheet feeding rollers having a rigidity lower than that of the sheet feeding roller are coaxially provided on both sides of the sheet feeding roller at intervals in the width direction of the sheet. 2. The paper feeding device according to claim 1, wherein a plurality of the auxiliary paper feeding rollers are provided on both sides of the paper feeding roller. 3. A sheet feeding table on which sheets are stacked, and a separation table which is rotationally driven in a state of pressingly contacting the upper surface of the sheets stacked on the sheet feeding table and provided at intervals in the sheet feeding direction. In a paper feeding device having respective paper feeding rollers for feeding, the above-mentioned paper feeding rollers are provided at the central portion in the width direction of the paper, and there is a space in the width direction of the paper on both sides of the paper feeding roller for calling. Further, the auxiliary paper feeding roller having a rigidity lower than that of the paper feeding roller for calling is coaxially provided. 4. The paper feeding device according to claim 3, wherein a plurality of the auxiliary paper feeding rollers are provided on both sides of the calling paper feeding roller. 5. The paper feeding device according to claim 1, wherein the auxiliary paper feeding roller has a hollow structure. 6. The sheet feeding device according to claim 1, wherein the auxiliary sheet feeding roller is provided so that the position in the width direction of the sheet can be adjusted. . 7. A sheet feeding table on which sheets are stacked, and a sheet separating table which is rotatably driven in a state of being in pressure contact with the upper surface of the sheets stacked on the sheet feeding table and provided at intervals in the sheet feeding direction. In a paper feeding device having paper feeding rollers for calling, a plurality of paper feeding rollers for calling are provided at intervals in the width direction of the paper, and the paper feeding rollers for calling are in contact with the paper. A sheet feeding device, which is provided so as to be movable independently in the separating direction. 8. The paper feeding device according to claim 7, wherein the contact pressures of the calling paper feeding rollers with respect to the paper can be independently set. 9. The paper feeding device according to claim 7, wherein the paper feeding roller for calling has a low-rigidity structure except for a centrally located paper feeding roller. 10. The paper feeding device according to claim 9, wherein the calling paper feeding roller not located at the central portion has a hollow structure. 11. The paper feeding device according to claim 9, wherein the calling paper feed roller not located at the central portion is provided so that the position in the width direction of the paper can be adjusted. Paper feeding device. 12. An image forming apparatus that separates sheets one by one by a sheet feeding device and sends the sheets to a transfer unit, and the image is transferred to the sheet by the transfer unit, wherein the sheet feeding device is any one of claims 1 to 11. An image forming apparatus according to claim 1.