JP2006335545A - Paper feeding device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeding device capable of forming deformation quantity of paper before a resist roller in a stable state even when a slip rate of the paper is changed by paper feeding pressure and separation pressure and of reducing paper feeding failure, jam, skew and the like. <P>SOLUTION: Based on paper feeding pressure and separation pressure in a paper feeding/separating part 50, paper feeding drive quantity (rotating quantity of a paper feeding roller 11a: drive pulse) is adjusted, and deformation quantity of the paper before the resist roller is controlled. A control means determines corresponding drive pulse data from a relation data table between set values of the paper feeding pressure and separation pressure and the paper feeding drive quantity of the paper feeding/separating part 50, which is obtained beforehand by experiment etc., and controls a paper feeding roller drive motor based on the drive pulse data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet feeding device that separates and feeds stacked sheets (recording media) one by one, and an image forming apparatus such as a copying machine, a printer, a facsimile, a plotter, and a printing machine having the sheet feeding device.

In this type of image forming apparatus, the leading edge of the paper fed from the paper feed tray (paper feed table) is abutted against the nip of the pair of registration rollers to form the paper deflection by overfeeding, and the paper is fed by the elastic force of the deflection portion. The sheet skew is corrected by forcing the leading edge of the sheet along the nip line, and then the registration roller pair is driven to convey the sheet to the image forming portion at a predetermined timing.
The deflection amount of the sheet affects the quality of the skew correction, and consequently the image position shift, and so on, and is preferably constant.
In general, a paper leading edge detection sensor that detects the leading edge of a sheet is provided in the vicinity of the upstream side of the registration roller pair in the sheet conveyance direction, and control is performed based on the point in time when the leading edge of the sheet is detected by the sheet leading edge detection sensor.

Japanese Patent Application Laid-Open No. 11-309844 discloses a method of correcting the transport amount from the detection time point to the registration roller nip by the printing speed.
Japanese Laid-Open Patent Publication No. 10-35911 discloses a method for correcting the paper conveyance amount from the paper leading edge detection sensor based on the detected paper state and size.
Japanese Laid-Open Patent Publication No. 4-53973 discloses a method for correcting the transport amount from the paper leading edge detection sensor according to the type of paper.

Japanese Patent Laid-Open No. 11-309844 JP-A-10-35911 JP-A-4-53973 Japanese Patent Laid-Open No. 9-233503 JP 2001-310828 A JP 2002-351281 A

In the above-described prior art, the influence of paper feed pressure and separation pressure is not taken into account in the formation of paper deflection, so the paper deflection at the registration roller section varies, causing paper jam, non-feed, skew, etc. was there.
That is, when the paper feed pressure or the separation pressure changes, the slip ratio of the paper changes, and a predetermined transport amount cannot be obtained, causing non-feeding, skew, and the like.
Further, when the sheet feeding pressure or the separation pressure is set outside the usable range, there is a problem that non-feeding, double feeding, etc. are likely to occur.

According to the present invention, the amount of deflection of the sheet before the registration roller can be made constant even if the slip rate of the sheet changes due to the sheet feeding pressure or the separation pressure, and non-feeding, jamming, skew, etc. can be reduced. An object of the present invention is to provide a paper feeding device that can be used and an image forming apparatus having the same.
It is another object of the present invention to provide a paper feeding device and an image forming apparatus having the paper feeding device that can prevent an unnecessary jam that occurs when the paper feeding pressure or the separation pressure is set outside the usable range.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a sheet feeding table that can be moved up and down, and a sheet feeding separation unit that separates and feeds the sheets stacked on the sheet feeding table one by one. A registration roller unit that conveys the sheet fed by the sheet feeding separation unit to the image forming unit, and a leading end of the sheet fed from the sheet feeding separation unit provided upstream of the registration roller unit in the sheet conveyance direction A sheet leading edge detecting means for detecting the sheet deflection, and controlling the amount of sheet deflection at the upstream side of the registration roller portion in the sheet conveying direction by controlling the sheet conveying amount from the time point detected by the sheet leading edge detecting means. In the paper apparatus, the amount of paper deflection is controlled by adjusting a paper feed drive amount of the paper feed separator based on a paper feed pressure and a separation pressure in the paper feed separator.

  According to a second aspect of the present invention, in the paper feeding device according to the first aspect, a paper feeding pressure setting unit that sets the paper feeding pressure, a separation pressure setting unit that sets the separation pressure, and the paper feeding pressure. A paper feed pressure adjusting means for adjusting the paper feed pressure according to a value set by the setting means, a separation pressure adjusting means for adjusting the separation pressure according to a value set by the separation pressure setting means, and a setting And a control means for controlling a deflection amount of the sheet based on the sheet feeding pressure and the separation pressure.

  According to a third aspect of the present invention, in the paper feeding device of the second aspect, the set values of the paper feed pressure and the separation pressure and the paper feed drive amount of the paper feed separation unit, which are obtained in advance through experiments or the like. The control means adjusts the paper feed drive amount of the paper feed separation unit based on the relation data table.

  According to a fourth aspect of the present invention, in the paper feeding device according to the third aspect, display means for displaying the paper feed driving amount selected from the relational data table, and changing the displayed paper feed driving amount. It has a possible sheet feed drive amount change means.

  According to a fifth aspect of the present invention, in the paper feeding device according to any one of the second to fourth aspects, if the set value of the paper feeding pressure or the separation pressure exceeds a usable range, The control means issues a warning.

  According to a sixth aspect of the present invention, in the paper feeding device according to the fifth aspect, the control unit performs the control to perform the warning and to prohibit the paper feeding operation in the paper feeding separation unit. To do.

  According to a seventh aspect of the present invention, in the image forming apparatus having a paper feeding device, the paper feeding device is one of the first to sixth aspects.

According to the first, second, or seventh aspect of the invention, since the paper feed drive amount is adjusted in consideration of the paper feed pressure and the separation pressure, the amount of deflection of the paper before the registration roller can always be made constant. Therefore, it is possible to prevent image positional deviation in the printing unit with high accuracy.
According to the third or seventh aspect of the present invention, it is possible to easily determine the paper feed driving amount in accordance with the actual use, and to always keep the deflection amount of the paper before the registration roller constant. Can be prevented with high accuracy.

According to the fourth or seventh aspect of the present invention, the sheet feed drive amount can be changed according to the sheet feed pressure and the separation pressure in accordance with the situation used by the user. Therefore, it is possible to prevent the image position shift in the printing unit with higher accuracy.
According to the invention described in claim 5 or 7, a warning is displayed even if an inappropriate paper feed pressure or separation pressure is set. Can be prevented.
According to the invention described in claim 6 or 7, even if an inappropriate paper feed pressure or separation pressure is set, a paper feed operation cannot be accepted together with a warning display. It is possible to reliably prevent a paper feed failure due to.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a stencil printing apparatus 1 as a printing apparatus mainly includes a scanner unit 2, a plate making unit 3, a plate discharging unit 4, a paper feeding device 5, an image forming unit 6, and a paper discharge unit 7. .
The scanner unit 2 is a part that reads a set original as image information. The plate making unit 3 writes the read image information on a master (stencil sheet) M to perform plate making, conveys the master M thus made to the printing drum 8 of the image forming unit 6, and places the master M on the outer peripheral surface of the printing drum 8. It is the part to wrap.
The plate removal unit 4 is a part that peels off the master M wound around the outer peripheral surface of the printing drum 8 that is no longer necessary after the printing is finished, and stocks the discharged master M.

The paper feeding device 5 is a part that separates the set paper into one and conveys it to the image forming unit 6. Hereinafter, the sheet feeder 5 will be described in detail. A paper feed tray 10 as a paper feed tray is loaded with printing paper P as paper, and is supported by the stencil printing apparatus main body so as to be movable up and down. The paper feed tray 10 is moved up and down by a paper feed table raising / lowering motor 53 (see FIG. 4) and a raising / lowering mechanism as a driving source in conjunction with the stacking height of the printing paper P (paper upper limit detection).
The paper feed roller 11a and the separation roller 11b are provided so as to contact the uppermost printing paper P, and each roller is a rotation driving means (not shown), for example, a drive for controlling the driving force from the main motor with an electromagnetic clutch. It is rotationally driven by a configuration or an independent drive configuration with a stepping motor or the like.

As shown in FIG. 2, the separation roller drive shaft 27 connected to the rotation drive means is connected to the paper supply roller shaft 28 by a belt 26 (connection may be a gear or the like). By rotating the sheet feeding roller shaft 28, the separation roller 11b having the one-way clutch and the sheet feeding roller 11a rotate at the same time.
The paper feed roller shaft 28 is rotatably supported by the paper feed arm 29, and the paper feed arm 29 is rotatable about the separation roller drive shaft 27 as a fulcrum. 11a is configured to be rotatable.
A separation pad 12 urged by a pressure spring 18 is in contact with the separation roller 11b. The printing paper P drawn by the paper supply roller 11a is separated into one sheet between the separation roller 11b and the separation pad 12.
A paper feed separation unit 50 is configured by the paper feed roller 11a, the separation roller 11b, the separation pad 12, and the like.
As the paper upper limit detection method, it is common to use either a detection mechanism that detects the height of the leading edge of the paper or a detection mechanism (not shown) that detects the height of the paper feed roller 11a. However, if both methods are used together, the detection accuracy is further improved.

In the present embodiment, description will be made with a paper tip height detection mechanism. As shown in FIG. 1, a rectangular paper upper limit detection filler 31 is fixed to a support bracket (not shown) fixed to the paper feed stay 40 by a stepped screw (not shown). . Further, a roller is rotatably disposed at the paper contact portion of the paper upper limit detection filler 31, and the roller contacts the front end portion of the paper. The roller is fixed to the shaft crimped by the paper upper limit detection filler 31 with an E-type retaining ring.
Further, the opposite end of the paper upper limit detection filler 31 is detected by a paper upper limit detection sensor 41 disposed in the paper feed stay 40. Here, the filler is used as the detection mechanism, but it is merely an example, and another method using a reflective sensor or the like may be used.

Based on FIG. 2, the paper feed pressure adjusting means 118 will be described. The configuration of the paper feed pressure adjusting means 118 is the same as that described in Japanese Patent Laid-Open No. 2001-341900 filed earlier by the present applicant.
The paper feed pressure adjusting means 118 is for adjusting the paper feed pressure in the paper feed separator 50, and is provided in the vicinity of the upper side of the separation roller 11b.
The paper feed pressure adjusting means 118 includes a paper feed pressure spring (tensile spring) 113 serving as a paper feed pressure source having one end locked to the paper feed arm 29 and the other end locked to the slider 114, and a rack portion 114a. And a slider 114 that is guided in a vertical direction by guide means (not shown), and a pinion gear 115 that meshes with the rack portion 114a is fixed to the output shaft 117, and includes a stepping motor that moves the slider 114 in the vertical direction. 116 and a paper feed pressure detection sensor group 118 as paper feed pressure detection means for detecting the paper feed pressure by detecting the movement amount of the slider 114.

The urging force of the paper feed pressure spring 113 causes a rotation moment to act on the paper feed roller 11a via the paper feed arm 29, and a paper feed pressure is generated. When the slider 114 is moved upward in FIG. 2 by the rotational driving of the paper feed pressure variable motor 116, the pulling length of the paper feed pressure spring 113 is increased, so that the urging force is increased and the paper feed pressure is increased. Become.
Therefore, the sheet feeding pressure can be adjusted in five steps by the rotational driving of the sheet feeding pressure variable motor 116. The paper feed pressure detection sensor group 118 includes, for example, five separation pressure position detection sensors 118a, 118b, 118c, 118d, and 118e in order to detect the amount of movement of the slider 114.
Each of the separation pressure position detection sensors 118a, 118b, 118c, 118d, and 118e of the paper feed pressure detection sensor group 118 is composed of, for example, a transmission type optical sensor, and is selected as a light shielding piece that protrudes and is attached to the left side wall of the slider 114. The sheet feeding pressure (value) is indirectly detected by engaging the target.
The paper feed pressure detection means 118 is not limited to the paper feed pressure detection sensor group 118, but is similar to the position detection substrate 52 of the paper feed pressure adjustment mechanism 22 shown in FIG. The amount of movement of the slider 114 may be detected by the sensor configuration.

The separation pressure adjusting means 120 will be described with reference to FIG. The separation pressure adjusting means 120 is
This is for adjusting the separation pressure in the paper feed separation unit 50.
The separation pad 12 is attached to an upper portion of a pad holder 121 that can slide in the vertical direction. A separation pressure adjusting means 120 for adjusting the separation pressure is disposed around the pad holder 121.
The separation pressure adjusting means 120 has one end locked to a pad holder 121 and the other end locked to a pressure plate 124 (to be described later) as a separation pressure source (compression spring) 18 and two slides. Are supported so as to be movable in the vertical direction via stepped screws 125, 125, and are rotatably supported by a pressure plate 124 having a rack portion 124b and a paper feed front plate 60 (see FIG. 2). 124b, a pinion gear 131 that meshes with the pinion gear 131, a worm wheel 130 that is coaxial with the pinion gear 131, a worm 129 that meshes with the worm wheel 130, and an output shaft 127 that is fixed to the paper feed front plate 60 and has the worm 129 fixed thereto. The separation pressure variable motor 126 and the separation pressure detection sensor group 128 for detecting the separation pressure by detecting the amount of movement of the pressure plate 124. It is.

As the material of the separation pad 12, an ethylene / propylene rubber (EPDM) type or urethane type material having a predetermined friction coefficient is used. The pad holder 121 is integrally formed of a synthetic resin such as polyacetal resin (POM) or polyamide resin (PA), and the inside thereof is hollowed out. The pressure plate 124 is formed with a long hole 124a that is long in the vertical direction.
The pressure plate 124 includes two stepped screws 125 and 125 inserted into the long holes 124a and screwed into the sheet feeding front plate 60, whereby a guide formed by a combination of these stepped screws 125 and 125 and the long holes 124a. It is guided in a vertical direction by means and is slidable.

The separation pressure variable motor 126 is composed of a stepping motor and has a function as a separation pressure variable drive means for changing the separation pressure. Each of the separation pressure detection sensors 128a to 128e includes a transmissive optical sensor having a light emitting unit and a light receiving unit. The separation pressure detection sensor group 128 detects the amount of movement of the pressure plate 124 by selectively engaging each of the separation pressure detection sensors 128a to 128e with a light shielding piece 124c formed to protrude below the pressure plate 124. Thereby, the separation pressure (value) is indirectly detected.
The upper part of the separation pad 12 protrudes from the square hole 60 a of the sheet feeding front plate 60 and is in contact with the separation roller 11 b, and the separation pad 12 is pressed against the separation roller 11 b by the pressure of the pressure spring 18. A separation pressure is generated.

The rotational driving force of the separation pressure variable motor 126 is transmitted to the worm 129, the worm wheel 130, the pinion gear 131, and the rack portion 124b, and the pressure plate 124 is guided and supported by the stepped screws 125 and 125. When moving upward in FIG. 3, the compression length of the pressure spring 18 is shortened (decreased), so that the pressure (compression load) increases and the separation pressure increases.
On the other hand, when the pressure plate 124 moves downward in FIG. 3 due to the rotational drive of the separation pressure variable motor 126, the compression length of the pressure spring 18 becomes longer (larger), so that the pressure (compression) Load) decreases, and the separation pressure decreases.
Therefore, the separation pressure can be adjusted stepwise by the rotational drive of the separation pressure variable motor 126, and the separation pressure detection sensor group 128 including the separation pressure variable motor 126 and the five separation pressure detection sensors 128a to 128e. The separation pressure can be adjusted in five steps.

  If it is desired to automatically switch the separation pressure in a multi-step manner as described above, the separation pressure detection sensor of the group of separation pressure detection sensors is increased and the separation pressure variable motor 126 is controlled accordingly. do it. Further, not limited to the separation pressure detection sensor group 128, for example, the separation pressure variable motor 126 may be provided with a photo encoder and one home position detection sensor for detecting the home position of the pressure plate 124. Further, if the separation pressure variable motor 126 can be controlled in an open loop, the separation pressure variable motor 126 may be provided with only a photo encoder. The same applies to the paper feed pressure detection sensor group 118 in the paper feed pressure adjusting means 118 described above.

As shown in FIG. 1, a registration roller pair 13 as a registration roller portion is disposed downstream of the separation roller 11b in the paper conveyance direction. The registration roller pair 13 holds the leading end of the conveyed printing paper P between the rollers, and conveys it between the outer peripheral surface of the printing drum 8 and a press roller 9 described later (image transfer portion) at a timing.
The upper guide plate 14 and the lower guide plate 15 are fixed to the side plates of the stencil printing apparatus main body, and guide the feeding of the printing paper P.
A paper leading edge detection sensor 20 as a paper leading edge detection means is disposed in front of the registration roller pair 13 (upstream side in the paper transport direction), detects the leading edge position of the fed paper P, and then feeds it. Is controlled so that the amount of deflection of the sheet at the registration roller pair 13 is constant.
Here, the sheet deflection at the registration roller pair 13 portion has an important function of correcting the contact state and skew of the sheet tip to the nip of the registration roller pair 13, and it is possible to prevent the image position deviation by keeping the deflection amount optimal. It is a well-known fact that this is an important matter. The control of the deflection amount will be described later.
Here, the pair configuration of the rollers is exemplified as the registration roller portion, but a configuration including one roller and a face plate facing the roller may be employed.

The image forming unit 6 includes a printing drum 8 and a press roller 9, and presses the conveyed paper P against the printing drum 8 by the press roller 9, so that the image of the master M wound around the printing drum 8 is the paper. Is transferred to.
The paper discharge unit 7 has a suction conveyance device 16 for peeling the printed paper P from the printing drum 8 and discharging it to the paper discharge table 17, and a paper discharge table 17 for stocking the printed paper. Yes.
The suction conveyance device 16 includes a conveyance belt, a driving source (not shown), and a fan for sucking the sheet to the conveyance belt. The sheet discharge detection for detecting the sheet below the sheet conveyance surface of the conveyance belt. A sensor 21 is arranged.
Usually, the paper leading edge detection sensor 20 and the paper discharge detection sensor 21 are sensors such as a reflection type, a transmission type, and a filler type.

The control of the deflection amount of the sheet will be described in detail with reference to the control block diagram of FIG. For example, when the sheet feeding pressure is set to 3 by the sheet feeding pressure setting unit 201 on the operation panel 200, the sheet feeding pressure is detected until the sheet feeding pressure detection sensor 118 detects the sheet feeding pressure 3 (118c in FIG. 2) by the control unit 300. The pressure drive motor 116 is driven.
Next, when the separation pressure is set to 3, for example, by the separation pressure setting means 202 on the operation panel 200, the separation pressure drive motor until the separation pressure detection sensor 128 detects the separation pressure 3 (128c in FIG. 3) by the control means 300. 126 is driven.
The memory 220 stores a relational data table of paper feed pressure and separation pressure obtained in advance by experiments and the like and paper feed drive amount (paper deflection amount) corresponding thereto, and paper feed based on the data. The number of driving steps of the roller driving motor (here, the stepping motor) 52 is selected and driven.
In this embodiment, the related data table is stored in the external memory 220, but of course, it may be stored in a ROM or RAM as an internal memory of the control means 300.

FIG. 5 shows an example of a relational data table of drive pulse data (paper feed drive amount) corresponding to the paper feed pressure and separation pressure.
For example, if the distance from the paper leading edge sensor 20 to the registration roller pair 13 is 5 mm and the driving amount per pulse of the paper feed stepping motor 52 is 0.5 mm, the paper feed pressure 3 and the separation pressure 3 are 20 pulses. The theoretical sheet transport distance from the leading edge detection sensor 20 is 10 mm.
However, in reality, a loss such as slip occurs several millimeters, and the amount of deflection becomes the optimum several millimeters. The table in FIG. 5 is merely an example, and it goes without saying that it varies depending on the position of the detection sensor, the paper feed pressure, the load level due to the separation pressure, the slip amount, etc. The slip tends to increase as the pressure increases, and conversely, the slip tends to decrease as the paper feed pressure increases and the separation pressure decreases.

  Since the configuration is as described above, in the present embodiment, the optimum amount of deflection of the sheet according to the setting of the sheet feeding pressure and the separation pressure can always be kept constant. As a result, the sheet at the registration roller pair 13 can be kept constant. Not only can the feeding time be accurately performed, but also the skew correction processing of the paper is reliably performed, and the image position deviation in the printing unit can be prevented with high accuracy.

Next, a second embodiment will be described based on FIGS. 4 and 6. Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and unless otherwise specified, description of the configuration and functions already described is omitted, and only the main part will be described (the same applies to other embodiments below).
In this embodiment, as shown in FIG. 4, for example, the operation panel 200 has a feed roller driving amount changing unit 203 as a feeding drive amount changing unit, and thereby the sheet feeding shown in FIG. The driving pulse data according to the pressure and the separation pressure can be changed.
As shown in FIG. 6, a touch panel type liquid crystal display unit 200a serving as a display unit on the operation panel 200 includes a sheet feeding pressure setting key 201 serving as a sheet feeding pressure setting unit and a separation pressure setting key serving as a separation pressure setting unit. 202 is provided.
When the paper feed pressure setting key 201 is pressed, the paper feed pressure is displayed in multiple stages on the screen, and the paper feed pressure is set by pressing a desired numerical value. Similarly, when the separation pressure setting key 202 is pressed, the separation pressure is displayed in multiple stages on the screen, and the separation pressure is set by pressing a desired numerical value.

When the paper feed pressure and the separation pressure are set, the drive pulse data corresponding to this is displayed. For example, if the paper feed pressure is set to 2 and the separation pressure is set to 2, the drive pulse data is displayed as 20.
In this state, when the paper feed roller drive amount change key 203 as the paper feed roller drive amount change means is pressed, the drive pulse data can be changed. The change is made, for example, using the numeric keypad 51 on the operation panel 200. When the paper feed roller drive amount change key 203 is pressed again after inputting the change value, the drive pulse is determined based on the changed value. You may make it confirm with the confirmation key which is not shown in figure.
In this embodiment, fine adjustment can be made even when drive pulse data based on a relational data table stored in the memory in advance does not match the actual use situation of the user, and the paper deflection can be achieved in any use environment and situation. The quantity can always be kept constant.

A third embodiment will be described based on FIGS. 4 and 7.
The present embodiment is characterized in that a warning is issued when the paper feed pressure or the separation pressure or at least one of the paper feed pressure and the separation pressure exceeds the usable range due to the characteristics of the apparatus.
As shown in FIG. 4, the operation panel 200 is provided with a paper feed condition suitability display unit 210. In the present embodiment, the liquid crystal display unit 200a also serves as the paper feed condition suitability display unit 210.
When the set paper feed pressure or separation pressure is outside the proper use range, the control means 300 warns on the liquid crystal display unit 200a that, for example, “setting of paper feed pressure and separation pressure is inappropriate”. Display. The operator resets the paper feed pressure and separation pressure according to the warning display.

The warning display may be arbitrarily set. In this case, for example, the * key of the numeric keypad 51 may be used as an on / off key for warning display.
FIG. 7 shows an example of a relational data table incorporating a warning display. In general, when the difference between the sheet feeding pressure and the separation pressure is extremely large, or when both the sheet feeding pressure and the separation pressure are extremely large, sheet feeding non-feeding and sheet double feeding (multi-sheet feeding) are likely to occur.
In the present embodiment, even if an inappropriate paper feed pressure or separation pressure is set, a warning is displayed, so that it is possible to prevent a paper feed failure due to an obvious mistake in setting the paper feed pressure or separation pressure.

Next, a fourth embodiment will be described.
In the present embodiment, when the set sheet feeding pressure or separation pressure is outside the proper use range, the control unit 300 uses the sheet feeding condition suitability display unit 210 to indicate, for example, “setting of sheet feeding pressure and separation pressure is inappropriate. And the like, and a paper feed operation is prohibited (not accepted).
As a result, even if an inappropriate paper feed pressure or separation pressure is set, a paper feed operation cannot be accepted together with a warning display, thus completely preventing a paper feed failure due to an obvious mistake in setting the paper feed pressure or separation pressure. Can do.

In each of the above embodiments, the mechanism for electrically changing the paper feed pressure and the separation pressure has been described. However, many low-cost machines can change the paper feed pressure and the separation pressure with a manual lever. For example, those described in JP-A-9-86692, JP-A-11-199070, and JP-A-2004-224459 by the present applicant.
Such a manual method may be used as the paper feed pressure adjusting means and the separation pressure adjusting means. In this case, the set pressure detection mechanism may be the same as that in the case of the electric motor, and can be easily added to the existing manual method.

1 is a schematic front view of a stencil printing apparatus according to a first embodiment of the present invention. FIG. 5 is a detailed view of a sheet feeding separation unit and a sheet feeding pressure adjusting unit. FIG. 3 is a detailed view of the separation pressure adjusting means, as viewed from the VA direction in FIG. 2. It is a control block diagram. It is a figure which shows a related data table. It is a figure which shows the change operation of the paper feed drive amount in 2nd Embodiment. It is a figure which shows the relationship data table in 3rd Embodiment.

Explanation of symbols

Reference Signs List 6 Image forming unit 10 Paper feed tray as paper feed tray 13 Registration roller pair as registration roller unit 20 Paper leading edge detection sensor as paper leading edge detection means 50 Paper feed separation part 118 Paper feed pressure adjustment means 128 Separation pressure adjustment means 200a Liquid crystal display unit 201 as display means 201 Paper feed pressure setting means 202 Separation pressure setting means 203 Paper feed roller drive amount change means 300 as paper feed drive amount change means 300 Control means

Claims (7)

A sheet feeding table that can be moved up and down, a sheet feeding separation unit that separates and feeds sheets stacked on the sheet feeding table one by one, and a sheet fed by the sheet feeding separation unit to the image forming unit A registration roller unit that conveys; and a sheet leading end detection unit that is provided upstream of the registration roller unit in the sheet transport direction and detects the leading end of the sheet fed from the sheet feeding separation unit. In the paper feeding device that controls the amount of deflection of the paper on the upstream side in the paper conveyance direction of the registration roller unit by controlling the paper conveyance amount from the detection time point,
A paper feeding device that adjusts a paper feed drive amount of the paper feed separation unit based on a paper feed pressure and a separation pressure in the paper feed separation unit to control a deflection amount of the paper. The sheet feeding device according to claim 1,
A paper feed pressure setting means for setting the paper feed pressure, a separation pressure setting means for setting the separation pressure, and a paper feed pressure for adjusting the paper feed pressure in accordance with a value set by the paper feed pressure setting means. An adjustment unit, a separation pressure adjusting unit that adjusts the separation pressure according to a value set by the separation pressure setting unit, and a deflection amount of the sheet based on the set sheet feeding pressure and the separation pressure. A sheet feeding device having control means for performing The sheet feeding device according to claim 2,
A relational data table that is obtained in advance through experiments or the like, and has a relational data table between the set values of the paper feeding pressure and the separation pressure and the paper feed driving amount of the paper feeding / separating unit; A sheet feeding device that adjusts a sheet feeding drive amount of the sheet feeding separation unit. The sheet feeding device according to claim 3.
The sheet feeding device includes display means for displaying the sheet feeding driving amount selected from the relation data table, and sheet feeding driving amount changing means capable of changing the displayed sheet feeding driving amount. apparatus. In the paper feeding device according to any one of claims 2 to 4,
The sheet feeding device, wherein the control unit issues a warning when the set value of the sheet feeding pressure or the separation pressure exceeds a usable range. In the paper feeding device according to claim 5,
The sheet feeding device, wherein the control unit performs the control to perform the warning and prohibit the sheet feeding operation in the sheet feeding / separating unit. In an image forming apparatus having a paper feeding device,
7. The image forming apparatus according to claim 1, wherein the sheet feeding device is one according to any one of claims 1 to 6.

Images