JP3056768B2 - Feeding device for image forming apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium feeding device in an image forming apparatus such as a copying machine, a laser printer, and a facsimile.

(Prior art)

2. Description of the Related Art In an image forming apparatus such as a copying machine, a sheet-shaped recording medium such as transfer paper picked up by a frictional action of a rubber roller is transported to an image forming position such as a transfer position on a photoconductor using a pair of rubber rollers or a belt. That is being done.

In such a conventional feeding device for a recording medium, in order to prevent a so-called double feeding in which a plurality of recording media are fed in an overlapping manner, a friction pad is combined with a rubber feeding roller, or a reverse rotation is performed. It has been practiced to combine a rubber reverse roller or a cassette accommodating a recording medium with a corner claw.

However, in the conventional feeding method, there is a problem that a jam or a skew occurs during the conveyance, and in addition to the double feeding, the conventional apparatus still has a problem in the reliability of the feeding.

Further, the structure becomes complicated, the control becomes complicated, and the cost increases, and the problems of simplification of the apparatus and cost reduction have not been solved.

In order to solve these conventional problems, an insulative endless belt is wrapped around almost all transport systems in a copying machine, the belt is charged using a charging unit, and the paper stored in a paper feed tray is discharged. After the paper is fed by a paper feed roller provided coaxially with the belt support roll, the belt is electrostatically attracted to the belt, or the belt is directly contacted with the paper to be electrostatically fed, and at the same time, is brought into contact with the photoconductor. Conveying using a belt to a transfer area to be transferred is proposed in, for example, JP-A-59-212856, JP-A-59-224858, JP-A-59-229585, etc. For example, Japanese Patent Application Laid-Open No. 63-139846 proposes that a sheet is conveyed by utilizing the frictional force described above.

However, in these prior arts, when the paper stored in the paper feed tray is fed out with an endless belt or a paper feed roller provided coaxially with the drive shaft of the insulative endless belt, the endless belt or roller makes frictional contact with the paper. , The paper may be skewed.
When double feeding occurs, the first sheet (uppermost side) is conveyed by being electrostatically attracted or frictionally contacted with the belt, but the second and subsequent sheets (multiply feeding) of the first sheet are fed. The lower side protrudes from the leading end of the paper feed tray, and causes a jam in the next feeding (feeding) operation.

In addition, paper dust is generated due to frictional contact, paper feeding failure,
There is also a problem of poor image quality during image formation.

When the paper stored in the paper feed tray is directly fed by the charged insulative endless belt, the belt comes into contact with the paper in a rotating state during normal image formation, so that the belt is If the tensioning, descending state, and the paper loading state (loading state) are not uniform with considerable accuracy, the contact state between the belt and the paper becomes unstable, and even in this case, the paper is skewed. Is more likely to occur. Therefore, in order to stabilize the contact state between the belt and the paper, the belt,
It is necessary that both sheets be placed in the apparatus with high precision.

Even in the above configuration, a certain amount of frictional force is applied between the first sheet (upper side) and the second sheet (lower side) because the belt contacts the first sheet in a rotating state. And double feed may occur, and a certain amount of paper dust was generated.

Even if a roller or a belt is used as the paper feeding means, the paper transport state from the paper feed tray is always constant and difficult to ensure as described above. It is indispensable to provide a registration means for adjusting the position with respect to the leading edge of the image and correcting the skew of the sheet, which is still complicated in structure and control.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a feeding device for an image forming apparatus which prevents skew, double feeding, and jam without requiring a registration unit.

[Means for solving the problem]

SUMMARY OF THE INVENTION The present invention is directed to a feeding device for an image forming apparatus, comprising: a storage unit that stores a recording medium for recording an image; and an endless transport unit that suctions and transports the recording medium from the storage unit to a predetermined position. The endless transport means has a belt wound around a driving roller and a driven roller, and is held in a non-contact state with respect to the recording medium when not transported,
In a feeding device configured to be displaceable such that only a part of the belt is in contact with the recording medium during suction conveyance, an additional moving unit that changes a circulation path of the belt is provided, and the additional moving units form a pair. This problem has been solved by a feeding device for an image forming apparatus, comprising a movable adjusting roller, wherein a belt portion in contact with the recording medium generates a variable speed by the movement of the adjusting roller.

[Action]

According to the present invention, the endless transport means performs a transport movement at a constant speed, and at this time, only a part of the endless transport means is in the horizontal direction
Or additional movement in the horizontal and vertical directions or simultaneously in the horizontal and vertical directions, and depending on the selection of the movement speed, the endless transport means locally reduces the speed relative to the stationary member, for example, the recording medium, or stops, or reverses. Move to

If the recording medium is brought into contact with the recording medium in a state where the relative speed is zero, the recording medium can be fed while being stored.
At this time, there is no relative displacement between the endless conveyance means and the recording medium.

〔Example〕

The details of the present invention will be described based on an embodiment shown in the drawings.
First, the configuration and operation of the entire image forming apparatus will be described.

In FIG. 1, a copying machine 1 as an example of an image forming apparatus including a paper feeding apparatus according to the present invention includes a scanner 2 for reading an image of a document, and an image for forming an image based on information from the scanner. Copying body 3 with built-in forming unit
And a recording medium for recording an image, for example, a paper bank device 4 for accommodating a large number of recording papers. The copying main body 3 is placed on the paper bank device 4, and the scanner device 2 is placed on the copying main body 3. Is placed.

The copying main body 3 has an image forming unit 5 and a paper feeding device 6 in FIG.

The scanner device 2 placed on the copying main body 3 is
As shown in FIG. 3 and FIG. 3, in addition to the case where it is formed as a separate structure separated from the copying main body 3, it may be configured as an integral structure.

The scanner device 2 includes a contact glass on which a document is placed.
An optical device includes an original holder 11, an original holder 12 for pressing and mounting an original on a contact glass 11, and fixing the original. The optical device includes a lamp 13 for illuminating and scanning the original on the contact glass 11.
A first mirror 14 that scans with the lamp 13 and reflects light reflected from the original; a second mirror 15 and a third mirror 16 that sequentially reflect light reflected from the first mirror 14; And a lens 17 for imaging the reflected light from the three mirrors 16 on the CCD 18. The second mirror 15 and the third mirror 16 scan at a speed half the reading scanning speed of the lamp 13.

The image forming unit 5 incorporated in the copying main body 3 includes a writing optical device 7. The writing optical device 7 is shown in FIGS.
In the figure, a semiconductor laser 21 and a collimating lens for converting a laser beam emitted by the semiconductor laser 21 into a parallel light speed
22 and an aperture 23 for shaping the light beam into a light beam of a certain shape
And a cylinder lens 24 that enters the polygon mirror 25 with the beam shaped from the aperture 23 compressed in the sub-scanning direction. An accurate polygon mirror 25 is rotated at a constant speed in a certain direction by a polygon motor 26, and the incident laser light is deflected by the rotation of the polygon mirror 25, and the deflected laser light is converted to an fθ lens.
Light is incident on 27a, 27b, and 27c. The rotation speed of the polygon mirror 25 is controlled by the image information holding unit 31 of the image forming unit 5, for example, a photoconductor.
It is determined by the speed, writing density, and number of planes.

The fθ lenses 27a, 27b and 27c convert the scanning light having a constant angular velocity so as to scan at a constant speed on the photoconductor 31, form an image on the photoconductor 31 so as to have a minimum light spot, and further correct surface tilt. Has a function.

The light after passing through the fθ lens 27 (27a, 27b, 27c) is reflected by the mirror 28, and the light outside the image area is guided to the synchronization detection sensor 30 by the synchronization detection mirror 29 to output a cue signal in the main scanning direction. Emits a signal. A fixed time after the synchronization signal is output from the synchronization detection sensor 30, one line of image data is output based on image information read from the scanner device 2.
Light as image data is reflected by the mirror 28 and forms an image on the photosensitive member 31 at the exposure position. By repeating this, an image is sequentially exposed on the photoconductor 31.

The photoconductor 31 has a drum shape, and has a surface coated with a photosensitive layer. Organic photoconductors (OPC), α-Si, Se-Te, and the like are known as photoconductors sensitive to the wavelength of the semiconductor laser of 780 nm. In this embodiment, the organic photoconductor is used.

Generally, in the case of laser writing, light is applied to the image area.
P (negative / positive) process and P / P that shines light on the background
There is a (positive / positive) process, which is an N / P process in this embodiment.

The charging charger 32 uniformly (-) charges the surface of the photosensitive member 31 by a scorotron method having a grid on the photosensitive member side, and irradiates the photosensitive portion with laser light to lower the potential. This allows
-750 to -800 V on the background of the photoreceptor 31, -5 on the image
An electrostatic latent image of about 0 V is formed. The electrostatic latent image is developed by developing the (−) charged toner while a bias voltage of −500 to −600 V is applied to the developing roller 33 a by the developing device 33.

The image visualized by the developing device 33 is a recording medium sent in synchronization with the photoconductor 31 by the conveyance belt 53 of the paper feeding device 6,
For example, (+) charge is applied by the transfer charger 34 from the back surface of the transport belt 53 onto a recording paper surface such as a transfer paper and transferred.

The toner remaining on the photoreceptor without being transferred to the recording paper is scraped off from the photoreceptor 31 by the cleaning device 35 and collected in a tank in the cleaning device 35. Further, the potential pattern remaining on the photoreceptor 31 is erased by irradiating light with a neutralization lamp 36.

The reflection density of the photoreceptor surface is measured by a photosensor 37 provided at a position immediately after the development by the developing device 33. The photo sensor 37 is composed of a combination of a light receiving element and a light emitting element. To measure the reflection density, a writing optical device 7 writes a constant pattern (for example, a pattern of black or halftone dots) at a position corresponding to the reading position of the photosensor, develops the pattern, and reflects the reflectance of the pattern portion and the sensitivity of the portions other than the pattern portion. The density of the image is determined from the ratio of the reflectance of the body, and if the image is light, a toner supply signal is output. In addition, the fact that the density does not increase even after replenishment can be used to detect the lack of the remaining amount of toner.

The recording paper on which the image has been transferred is separated in curvature by a driving roller 54 wound around a transport belt 53 and sent to a fixing device 38. In the fixing device 38, the toner on the surface of the recording paper is fixed by a fixing roller including a pair of a heat roller 39 and a pressure roller 40. During normal image formation, for example, copying, the fixed recording paper is guided to a paper discharge path 42 by a nail 41 and discharged by a paper discharge roller 43.

Next, a paper feeding device 6 which is a first embodiment of the paper feeding device according to the present invention will be described. The paper feeding device 6 is a transport device.
51 and a storage means, for example, a paper feed tray or a paper feed cassette.

The transport device 51 has an endless transport means, for example, an endless circulation traveling through transport belt 53, which is sequentially wound around a driving roller 54, a first driven roller 55, a second driven roller 56, and an adjusting roller 57. . The transport belt 53 is transported at a substantially constant speed by the drive roller 54. The transfer belt 53 has a predetermined nip width between the driving roller 54 and the first driven roller 55 at the image forming position, that is, the transfer position, where the photosensitive member 31 contacts from the outside. The transfer charger 34 facing the photoreceptor 31 is arranged facing the inner side surface of the transport belt 53.

Between the first driven roller 55 and the second driven roller 56, an appropriate number of pickup rollers 5
8, for example, two pickup rollers 58 are arranged at appropriate intervals, and each pickup roller 58 is formed to be vertically movable. The distance between the pickup rollers 85 can be changed as needed by moving one or a plurality of pickup rollers. The first driven roller 55 and the adjusting roller 57 are formed so as to be movable in a substantially horizontal direction, and the adjusting roller 57 is formed so as to receive the tension of the spring 59 and always apply a predetermined tension to the transport belt 53.

As shown in FIGS. 5 and 6, the first driven roller 55 rotatably supports shaft portions 55a at both ends by bearings 60.
0 is formed as a slider slidably supported on a guide shaft 62 fixed to the side plate 61. The shaft portion 55a may be fixed to the bearing 60 so that the first driven roller 55 is rotatably supported by the shaft portion 55a. The first driven roller 55, that is, the bearing 60, is reciprocated along the guide shaft 62 by the moving device 63. When the drive roller 54 conveys and moves the conveyance belt 53, the movement device 63 causes the conveyance belt 53 to perform a unique movement, and functions as a feed transmission device. A moving device 63, which is a particularly important element of the present invention, is fixed to a driving pulley 65 fixed to a driving shaft 64 rotatably supported by the side plate 61, and a driven shaft 66 rotatably supported to the side plate 61. Driven pulley 67
And the drive shaft 64 is rotationally driven by the moving motor 68. A drive belt 69 is wound around each drive pulley 65 and driven pulley 67, and the drive belt 69 is fixed to the slider 60 by a fixing plate 70. The drive belt 69 is moved forward / reverse by the forward / reverse rotation of the moving motor 68, and the first driven roller 55 is moved in a substantially horizontal direction by moving the slider 60 along the guide shaft 62.

When the first driven roller 55 is at the home position, which is the right end position in the figure, it is detected by the home sensor 71. The adjusting roller 57 also moves in accordance with or against the tension of the spring 59 in accordance with the movement of the first driven roller 55, so that the transport belt 53 can be maintained at a constant tension. Therefore, the adjusting roller 57 generally moves in a direction opposite to that of the driven roller 55 so as to correspond to the amount of belt pulled or reduced by the first driven roller.

The moving speed Vmm / s of the first driven roller 55 is set to the conveying speed of the conveying belt 53, that is, 1/2 of the peripheral moving speed v mm / s, that is, V = v
When the first driven roller 55 moves to the left in the figure, the transport belt 53 traveling in the direction of the arrow moves from the adjusting roller 57 to the first driven roller 55 via the second driven roller 56, that is, the speed fluctuation. In the region, the conveyor belt 53 can be apparently shifted to a stopped state and held in a stopped state by the action of the peripheral movement speed v mm / s and the movement speed Vmm / s. If the recording paper is sucked from the paper feed tray 52 while the feeding speed indicated by the apparent speed is zero, the paper can be fed without registration error without using a registration device. In addition, since the suction position is always the same, there is no deviation due to the belt conveyance, and it is not necessary to perform a registration stop operation by a registration device specially provided for image alignment. Thus, it is only necessary to control the paper feed timing and the image formation start timing.

In the speed fluctuation region which is a part of the transport belt 53 due to the movement of the first driven roller 55, a speed change operation is performed in which the first driven roller 55 apparently stops at one end and returns to a predetermined speed. In a section extending from the transfer position to the adjustment roller 57 via the drive roller 54, that is, in the constant speed region, the transport belt 53 moves at a constant speed without any apparent speed fluctuation. Therefore, the recording paper is transferred to the transfer position,
The peripheral speed of the reflection belt 53 is not changed during the feeding to the fixing position by the fixing device 38. This means that an apparent speed change occurs in a part of the transport belt 53, and another recording sheet is transported by the same transport belt 53 during the paper feed operation while being stopped, causing any effect on transfer, separation, and fixing. Can be done without. In the constant speed region where the transport belt 53 always runs at a constant speed, for example, if cleaning is performed by a belt cleaner 72 provided below the drive roller 54, no cleaning failure occurs.

When the conveyance belt 53 attracts the recording paper from the paper feed tray 52, the first driven roller 55 is moved to the right side in the drawing and returned to the home position. At this time, the adjusting roller 57 is also moved.

When the first driven roller 55 returns to the home position,
The apparent speed in the speed fluctuation region of the conveyor belt 55, that is, the feeding speed, increases to twice the speed of the constant speed region.

An upper pressing roller 73 is disposed above the first driven roller 55 in FIG. 2, and a lower pressing roller 74 is disposed below and to the right of the first driven roller 55 in FIG.
A guide plate 75 is provided between the lower press roller 74 and the lower press roller 74.
It assists the conveyance so as to be able to smoothly turn along the first driven roller 55.

After the transfer belt 53 is cleaned of dirt by the belt cleaner 72, a fixed charge pattern is formed on the transfer belt 53 by the charging roller 76 disposed near the belt cleaner 72. Unlike the arrangement shown in the drawing, the charging roller 76 is provided so as to circumscribe the second driven roller 56, as shown in FIG.
When a charge pattern is formed in the speed fluctuation region of the transfer belt 53, a constant amount of charge is applied to the transfer belt 53 by performing control such as changing the frequency of the applied charge in accordance with the feeding speed change of the transfer belt 53. A charge pattern can be formed.

The paper feed tray 52 is a front-loading type recording paper stacking device. By pulling out the paper feed tray 52 from the front of the copier 1, setting the recording paper 77, and pushing the paper feed tray 52 into the copier 1. Recording paper can be supplied.

The paper feed tray 52 has a recording paper size series (for example, A series,
B series, letter size, etc.). Here, the sequence A will be described, but the same applies to other sequences.

A central fence 78 is provided in the center of the paper feed tray 52, and a right fence 79 is provided on the right side. The central fence 78 is a retractable type as shown in FIG. When setting A4 size recording paper, set the central fence 78 as shown in Fig. 7,
The trays are placed in two tray chambers 80 and 81 formed on the left and right, respectively. When setting the A3 size, the central fence 78 is opened between the two tray chambers 80 and 81 as shown in FIG.

Below the sheet feed tray 52, an ascending tray 82 is provided in each of the tray chambers 80 and 81 formed on the left and right of the central fence 78.

When the central fence 78 is erected, the tray formed by the right tray chamber 80 and the rising tray 82 in FIG. Called two trays 52 ″.

7 to 9, the central fence 78 has an upper face guide 83 and a lower face guide 84, and corner guides 85 are provided at both ends of the upper face guide 83 and both ends of the lower face guide 84, respectively. This prevents the recording paper 77 from shifting laterally. The upper face guide 83 is inserted into the groove of the lower face guide 84 so as to be slidable up and down, and the spring 86 is
And the lower face guide 84. A groove may be formed in the upper face guide 84 so that the lower face guide 84 is inserted. Due to the action of the spring 86, when no load is applied, the upper face guide 83 is maintained at a predetermined relative position with respect to the lower face guide 84.

A notch 87 is formed at the center of the upper edge of the upper face guide 83 so that the operator's hand does not touch when the recording paper 77 is set.

The lower face guide 84 is rotatably supported by a frame of the paper feed tray 52 by a support shaft 88. The lower end of the lower face guide 84 has a finger portion 89 formed in an L shape. The lower face guide 84 is stopped at a substantially vertical position when the fingers 89 are engaged with the projection-shaped engaging portions 90 formed on the frame portion 52a of the paper feed tray 52 when the lower face guide 84 is rotated and stands. It does not rotate above. A nail 89a is formed on the finger 89,
The lower face guide 84 is prevented from rotating in the falling direction by being locked to the hook 91 formed on the frame 52a, and is held at the upright position. When the claw 89a pushes the upper face guide 83 sideways with such a force that the hook 91 is disengaged by the elastic deformation, the central fence 78 rotates clockwise in the figure and falls down, and as shown in FIG. The space between the chamber 80 and the left tray chamber 81 is opened. When the central fence 78 falls, the rising tray
The upper face guide 83 and the lower face guide 84 are formed so as to be buried in a concave portion 92 formed in the frame portion 52a of the paper feed tray 52 so as not to obstruct the recording paper placed on the 82. The fact that the center fence 78 has fallen and the right tray chamber 80 and the left tray chamber 81 are in communication with each other is detected by the claw 89a of the fallen lower face guide 84 pressing the switch 93 as a paper size sensor. .

A paper end sensor 94 is provided on the upper surface of the ascending tray 82 to detect the presence or absence of a recording sheet.

The central fence 78 can be removable instead of the retractable structure shown. The size detection at this time can be performed by providing a sensor for detecting the presence or absence of the central fence 78.

The right fence 79 can also be formed by the lower fence guide 84 and the upper face guide 83 as shown in FIG. In this case, the right fence 79 does not need to be overturned.

One of the pickup rollers 58 that presses the transport belt 53 against the recording paper 77 in the paper feed tray 52 is disposed directly above the face guide 83 on the central fence 78, and another Is located right above the face guide 83 on the right fence 79.

As shown in FIG. 10, one pickup roller 58 disposed immediately above each face guide 83 and one or more other pickup rollers 58 are formed as a set, for example, as a support plate.
It is rotatably supported by 95. In the illustrated example, two pickup rollers 58 are supported as a set on the support plate 95. Each set of pickup rollers 58 is supported at the same height. Carrier plate
95 is always pulled up to a fixed position by a tension spring 96, and the transport belt 53 is in a state separated from the upper end surface of the upper face guide 83. The holding plate 95 is in contact with a pressing device 97, for example, a cam device by the force of a spring 96. From the time of non-feeding shown in FIG. 10, the holding plate 95 is pushed down by the operation of the pressing device 97, for example, by the rotation of the cam 99, and one of the pickup rollers 58 contacts the upper face guide 83 as shown in FIG. , Then push down the face guide 83. Carrier plate 95
Is pushed down until the conveyor belt 53 comes into contact with the recording paper 77 and becomes in a state of sucking.

As shown in FIG. 12, the pressing device 97 has, in the case of a cam device, a paper feed cam 99 fixed in the same posture at a predetermined interval on a shaft 98. As an example, as shown in FIG. 13, the paper feed cam 99 forms a range of 144 ° in the outer peripheral shape as a circular surface B having a radius R ₁ from the center of the shaft 98, for example, a radius of 10 mm,
The remaining area of 216 ° is distributed by 108 °, and the distribution center point A is a point located at a position of radius R ₂ , for example, 6 mm from the center of the axis 98, and the arc surface B and the center point A are formed by a smooth curved surface. tie.

The shaft 98 is connected to a pulley 101 via a spring clutch 100.
Are connected to the fixed drive shaft 102. The pulley 101 is driven by a motor via a timing belt 103 and a speed reducer (not shown). A stopper 104 is fixed to the shaft 98. As shown in FIG. 14, the stopper 104 is formed by a substantially spiral ratchet having two step portions 105 and 106 on the outer periphery, and the claw portion of the locking bar 107 is engaged with one step portion 105. Locking bar 107 for stopping rotation of the stopper 104
Is rotatably supported by a support shaft 108, and is always held at an engagement position with respect to the step portion 105 or 106 by a spring 109.
A plunger of a locking solenoid 110 is connected to the locking bar 107, and when the solenoid is urged, the locking bar 10
7 is rotated around the support shaft 108 against the force of the spring 109 to release the engagement with the step portion 105 or 106.

When the stopper 104 rotates, the second
The angle up to the step 106 is set to 120 °, and when the locking bar 107 is unlocked at the time of locking at the first step 105, the stopper 104 rotates 120 ° and the second step 106 is rotated. The rotation of the shaft 98 is stopped by being locked by the locking bar 107. 1st step part 1
In the state where the locking bar 107 is locked at 05, the sheet feeding cam 99 is in contact with the support plate 95 at the point A as shown in FIG. 10, and the support plate 95 is in the pulled-up position.

The rotation of the pulley 101, which is driven by a motor (not shown) and transmitted at 120 rpm, is transmitted to a stopper 104 via a spring clutch 100.
10 is urged, the stopper 104 is released, and the stopper 104, which has always been receiving the rotational moment, starts rotating because the lock is released.After 0.25 sec, the paper feed solenoid 110 is deenergized, and the locking bar 107 is released. It comes into contact with the outer peripheral surface of the stopper 104 again. At this time, since the stopper 104 has already rotated half a turn (180 °), the second step portion 106 has passed, and the claw of the locking bar 107 locks the first step 105 of the stopper 104 at the time of one rotation. Then, the stopper 104 is stopped. This operation causes cam 9
9 rotates once in 0.5 seconds. The pickup roller 58 moves down by 4 mm in 0.15 sec together with the supporting plate 95 and stops for 0.2 sec. At this time, as shown in FIG. 11, the arc surface B of the cam 99 is in contact with the support plate 95, and the support plate 95 is being pushed down. After stopping for 0.2 sec, it returns to the original position in 0.15 sec. The pickup roller 58 and a means for pushing down the pickup roller 58, for example, the pressing device 97 and the holding plate 95 function as suction operation means for operating the conveyance belt 53.

The gap between the non-feeding conveyance belt 53 and the recording paper 77 is about 4 mm, and the gap between the upper face guide 83 and 2 mm. Accordingly, when the pickup roller 58 moves downward, the pickup roller 58 descends by 2 mm, contacts the upper face guide 83, and descends by 2 mm while further pushing down the upper face guide 83. At this lowered position, the conveyance belt 53 contacts the recording paper 77. At this time, the recording paper 77 is attracted to the transport belt 53 by the uneven electric field due to the charge pattern formed on the outer peripheral surface of the transport belt 53 by the charging roller 76 in advance. Pickup roller
The rising tray 82 is formed and controlled so that the rising tray 83 stops after the contact pressure between the recording paper 77 and the conveyance belt 53 reaches a predetermined value immediately after the 58 moves downward.
This makes it possible to correct a change in which the upper surface position of the recording paper 77 is lowered due to paper feeding, and the paper feeding position can always be kept at the same height.

The transport belt 53 has a feeding function of feeding the recording paper from the paper feed tray 52, a transport function of transporting the recording paper to the transfer position, and a transfer function of contributing to the transfer to the recording paper at the transfer position.

Since the transport belt 53 is suction-fed by suction force due to uneven electric field instead of friction force, there is no deviation of recording paper, it has a registration function, there is no generation of paper dust during conveyance, and it is necessary to remove electricity after transfer There is no.

The second step portion 106 of the stopper 104 is used when recording paper is supplied to the paper feed tray 52 as described later.

As shown in FIGS. 2 and 15, the right tray chamber 80 and the left tray chamber 81 divided by the central fence 78 of the paper feed tray 52.
, The ascending trays 82 are individually arranged. Each lifting tray 82
The lifting device 123 which moves up and down has wires 111 fixed to the lifting tray 82 at four locations as shown in FIGS. 15 and 16, respectively. The first wire 111a of the four wires 111
Is turned by a first guide pulley 112 and a second guide pulley 113 and the end is wound around a first drive pulley 114. The first driving pulley 114 is fixed to a shaft 115 rotatably supported by the frame 52a of the paper feed tray 52. One end of a second wire 111b is wound around the same first driving pulley 114, and the second wire 111b is turned and guided by a second guide pulley 113 on the way.

The third wire 111c and the fourth wire 111d fixed to the ascending tray 82 on the side opposite to the first wire 111a and the second wire 111b are wound around a second drive pulley 116 having ends fixed to the shaft 115, respectively. Can be The third wire 111c is the first wire 1
Similarly to 11a, the third guide pulley 117 and the fourth guide pulley 11
8 and wound around the second drive pulley 116,
Like the second wire 111b, the fourth wire 111d is turned only by the fourth guide pulley 118 and wound around the second drive pulley 116.

One end of the shaft 115 is connected to the output side of the electromagnetic clutch 119,
An encoder 120 is fixed to the other end. The input side of the electromagnetic clutch 119 is connected to the tray motor 122 via the coupling 121. The coupling 112 has a driving half 121a connected to the tray motor 112 and a driven half 121b connected to the electromagnetic clutch 119.

The lifting tray 82 and the lifting device 123 are formed in the same structure for the right tray chamber 80 and for the left tray chamber 81, but are formed substantially symmetrically with respect to the center fence 78 in the example shown. Lift tray 82 for right tray chamber 80 and lift tray for left tray chamber 81
82 can be driven by a separate tray motor 122. If it is necessary to distinguish between the right tray room 80 and the left tray room 81, the right tray room 80
Is distinguished by adding B after the code for the left tray chamber.

The electromagnetic clutch 119 transmits drive only when the output torque is less than or equal to a predetermined value in one rotation direction, and slips and does not transmit drive when the output torque is greater than or equal to a predetermined value. I have. As a result, the rising tray 82 on which the recording paper 77 is placed is raised by the rotation of the tray motor 122, but when the uppermost surface of the recording paper 77 comes into contact with the conveyor belt 53 and receives pressure, the slipping action of the electromagnetic clutch 119 occurs. As a result, the ascending tray 82 is no longer lifted, and after a predetermined time, the tray motor 122 stops, and the top surface of the recording paper 77 is always kept at a constant height.

When replenishing the recording paper 77, set the paper feed tray 52 to the copier 1
At this time, the drive half 121a of the coupling attached to the copying machine 1 side and the paper feed tray 52
The driven half 121b of the coupling attached to the side comes off, and the ascending tray 82 is lowered by its own weight to the lowest position. At the same time, the tray open / close sensor 124 (FIG. 2) detects that the paper feed tray 52 has been pulled out.

After the recording paper 77 is replenished, the paper feed tray 52 is pushed into the copying machine 1, and the driving half 121a of the coupling attached to the copying machine and the driven half of the coupling mounted on the paper feeding tray. The bodies 121b are engaged, and at the same time, the tray open / close sensor 124 detects that the sheet feed tray 52 has been set.

When the paper supply solenoid 110 is operated to rotate the locking bar 107 clockwise in FIG. 14, the claw portion of the locking bar 107 is disengaged from the first step portion 105 of the stopper 104. The stopper 104, which has always received the clockwise (right) rotational moment by the spring clutch 100, starts to rotate clockwise (right) because the regulating member has disappeared.

After 0.1 sec, the sheet feeding solenoid 110 is released, and the locking bar 107 is again applied with a rotational moment in the counterclockwise direction to come into contact with the outer peripheral surface of the stopper 104. At this time, since the stopper 104 has been rotated only 1/5 (72 °), the first stepped portion 1
It comes into contact with the outer peripheral surface between 05 and the second step portion 106. Stopper 1
When the 04 rotates just 120 °, the hook of the locking bar 107 stops.
It stops by stopping on the second step 106 of 104.

At this time, the cam 99 comes into contact with the supporting plate 95 on the surface B and is stopped, and the transport belt 53 is at the sheet feeding position.

Next, the tray motor 122 operates to raise the lifting tray 82 together with the recording paper 77. When the uppermost surface of the recording paper 77 comes into contact with the transport belt 53 and receives pressure, the recording paper 77 is stopped by the action of the electromagnetic brake 119. After a predetermined time, the tray motor 122 stops. Then, the paper feeding solenoid 110 is operated and the locking bar 107 is operated.
Turn clockwise. Then, the claw portion of the locking bar 107 comes off the second step portion 106 of the stopper 104. The stopper 104, which has always received the clockwise (right) rotational moment by the spring clutch 100, starts to rotate rightward because the regulating member has been removed.

After 0.1 sec, the sheet feeding solenoid 110 is released, and the locking bar 107 is again applied with a rotational moment in the counterclockwise direction to come into contact with the outer peripheral surface of the stopper 104. The locking bar 107 for which the stopper 104 rotates exactly 240 ° is again used as the first step portion 10 of the stopper 104.
Stop after hitting 5. At this time, the transport belt 53 returns to the position where paper is not fed.

As described above, the recording paper can be separately supplied to the first tray 52 'and the second tray 52 ". The central fence 78 is folded down and A3 extends over the first tray 52' and the second tray 52".
When a size of recording paper is set in the paper tray 52,
The above-described ascending tray operation and cam operation are performed by the first tray 52 '.
Are performed simultaneously on the second tray 52 ″. Thereby, the contact area of the transport belt 53 at the time of paper feeding is widened to stabilize the paper feeding.

As described above, at the time of normal image formation, the recording paper fixed by the fixing device 38 in FIG.
The paper is guided to the paper discharge path 42 and is discharged by the paper discharge roller 43.However, at the time of double-sided copying in which both sides of the recording paper are copied, the recording paper after fixing is turned upside down to the transfer position by the photoconductor 31. You need to feed paper.

Therefore, after the fixing device 38, a return guide path 44 for guiding the recording sheet to the sheet feed tray 52 is provided as a branch path that can be switched to the sheet discharge path 42 by the claw 41.

The return guide path 44 includes a reversing path 45 as a branch path, and the path to the sheet feeding tray 52 and the path to the reversing path 45 can be switched by the first switching claw 46a at the branch position. The recording paper sent to the return guide path 44 is sent to the first switching claw 46a by the feed roller 47, and the recording paper guided to the reversing path 45 is nipped by the reversing roller 48 and sent to the rear end of the recording paper. Is detected by the reversing sensor 125, the sheet is fed backward by the reverse rotation of the reversing roller 48. The reversely fed recording paper is guided by the second switching claw 46b toward the feed roller 49 of the return guide path 44, and is fed to the paper feed tray 52.
Is discharged over

Like the A3 copy, the first tray 52 'and the second tray 52 "
When both are used, after the feeding operation of the front side copy, the ascending tray 82 is lowered by a fixed amount by the reverse rotation of the tray motor 122 (the descending amount (moving amount) is stored by an encoder (not shown)), and After the recording paper 77 with the front side copied is inserted into the tray 52, the ascending tray 82 is returned to the original position, and the feeding operation of the back side copy is performed. After the back side copy, the recording paper 77 is discharged from the paper discharge path.

Like the A4 copy, the first tray 52 'and the second tray 52 "
When using any one of the above, when the front copy is fed from the first tray 52 ', the rising tray 82 of the second tray 52 "is lowered in advance by a predetermined amount by the reverse rotation of the tray motor 122 (an encoder (not shown)). The amount of movement (movement amount) is stored in the second tray.
After the 52 ″ is inserted, the raising tray 82 is returned to the original position, and the feeding operation of the back side copy is performed. After the back side copy, the recording paper 77 is discharged from the paper discharge path. In the case of starting from the second tray 52 ", after the front copy feeding operation, the ascending tray 82 of the second tray 52" is lowered by a fixed amount by the reverse rotation of the tray motor 122 (the descending amount (moving amount) is stored by an encoder not shown). After the front side copied recording paper 77 is inserted into the second tray 52 ", the raising tray 82 is returned to the original position, the back side copy feeding operation is performed, and after the back side copy, the recording paper 77 is discharged. It is discharged from the paper path.

A recording paper upper limit sensor 126 is provided above the second tray 52 ", and in the screen image forming mode, if the recording paper is full even if the ascending tray 82 is to be lowered, the operation panel cannot perform double-sided copying. Is displayed.

When it is desired to repeat the formation of a plurality of images on the same side, such as a combined copy, instead of a two-sided copy, the recording paper is placed on the reversing path 45.
Without being guided by the first sheet feed tray 52 by the first switching claw 46a.
Can be sent to

In some cases, the user may want to manually feed recording paper in contrast to the automatic paper feeding by the paper feed tray 52. For this purpose, a manual sheet feeding device 130 is provided.

The manual paper feeder includes a manual feed door (not shown) provided on the machine frame of the copying main body 3, guide plates 131 and 132 for guiding recording paper inserted from the manual feed door, and a manual paper feed roller 13.
With 3.

When you open the manual feed door, it switches to manual feed mode,
The first driven roller 55 is returned to the manual feed home position,
When the presence of the recording paper in the manual paper feeder 130 is detected by the manual feed sensor 134, a manual feed clutch (not shown) is operated, and the recording paper is transported onto the transport belt 53 by the rotation of the manual paper feed roller 133.

The copier 1 has a minimum unit composed of the scanner device 2 and the copier main body 3 and can normally function as a copier. However, when using various types of recording paper, For example, a paper bank device 4 that can store a large number of storage means, for example, a paper feed tray or a paper feed cassette, and includes a tray that can store a large number of recording papers can be used. In this case, the copying main body 3 is placed on the paper bank device 4 as shown in FIG. A paper feed path that opens at the bottom of the casing of the copying body 3 and guides the recording paper fed from the paper bank device 4
136 are provided. The paper feed path 136 is formed so as to be able to feed recording paper to a home position, for example, a nip position between the first driven roller 55 and the lower pressing roller 74 at a manual home position. A branch path 137 is provided in the paper supply path 136, the recording paper is formed so as to be able to be fed toward the first tray 52 ′ of the paper supply tray 52, and a switching claw 138 is provided at a branch position to the branch path 137 to perform recording. The paper feed path can be switched. Paper feed path 13
6 is provided with a paper bank paper feed sensor 139 for detecting that the recording paper is fed from the paper bank device 4. The paper bank is abbreviated as PB as needed.

The paper bank apparatus 4 is equipped with a three-stage tray including a first PB tray 201, a second PB tray 202, and a third PB tray 203 having a maximum loading capacity of 250 sheets, and a fourth PB tray 204 having a maximum loading capacity of 2,000 sheets. . Paper feed from each of the PB trays 201 to 204 is performed by one paper feeder 205.

The sheet feeding / conveying device 205, which is another configuration of the present invention, has another endless conveying means, for example, one endless belt 218 as shown in FIGS. The endless belt 218 includes a fixed position driving roller 211, a position movable tension roller 212, a fixed position turning roller 213, a driven roller 214, a pickup roller 215, a pair of belt speed change rollers 216, and an auxiliary turning. It is wound around the entire roller 217.

17 to 19, the front plate 205 and the rear plate 206 of the paper bank device 4 are almost vertically
The paper feed unit 220 is vertically guided by the guide rod 207. Paper feed unit 220 is guide rod 2
The sheet feeding unit includes a sheet feeding unit front side plate 222 and a sheet feeding unit rear side plate 223 to which a bearing 221 slidably mounted is fixed.
A driven roller 214, a pickup roller 215, and an auxiliary turning roller 217 are arranged such that both ends are supported by the sheet feeding unit front plate 222 and the sheet feeding unit rear plate 223, respectively.

The pickup auxiliary roller 2 is pressed so as to press the transport belt, that is, the PB endless belt 218 against the driven roller 214.
19 are disposed opposite to each other, and are rotatably supported by the sheet feeding unit front plate 222 and the sheet feeding unit back plate 223. The pickup auxiliary roller 219 serves to prevent the recording paper from peeling off from the PB belt 218 when changing to the transport direction.

Shaft 215a rotatably supporting pickup roller 215
Are supported by a long hole 224 formed in the sheet feeding unit front side plate 222 and a long hole 225 formed in the sheet feeding unit rear side plate 223 so as to be movable in a substantially horizontal direction. Further, both ends of the shaft 215a of the pickup roller 215 are fixed to the timing belt 226 by fixing fittings 227, respectively. The timing belt 226 is wound around a driving pulley 228 and a driven pulley 229, respectively. The drive pulley 228 has a common drive shaft 231 driven by a motor 230.
The drive shaft 231 is rotatably supported by the sheet feeding unit front plate 222 and the sheet feeding unit back plate 223. The driven pulleys 229 are rotatably supported by shafts individually mounted on the sheet feeding unit front side plate 222 and the sheet feeding unit back side plate 223, respectively. The pickup roller 215 is reciprocated along the elongated holes 224 and 225 by the forward / reverse driving of the motor 230. A home position feeler 232 and an upper end detection sensor 233 for detecting the upper end of the recording paper are provided on the shaft 215a of the pickup roller 215.
The mounting bracket 234 is attached. When the home position sensor 235 attached to the paper feed unit rear side plate 223 is operated by the home position feeler 232, it is detected that the pickup roller 215 is at the home position. The upper end detection sensor 233 detects that the paper feeding surface of the PB belt 218 has reached a height of 5 mm from the upper end of the recording paper,
The sheet feeding operation is performed from this position.

The elevating device 250 that moves the paper feeding unit 220 up and down is rotatably supported by the motor 251 fixed to the back plate 206 of the paper bank device, the back plate 206 and the front plate 205, and the motor 25
1, a drive shaft 252, two drive pulleys 253 fixed to the drive shaft 252, a rear plate 206 and a front plate 20.
5 has a driven pulley 253 rotatably supported on each of them, and two timing belts 254 wound around the driving pulley 252 and the driven pulley 253, respectively. Timing belt 254
Are the paper feed unit front plate 222 and the paper feed unit back plate 2
The sheet feeding unit 220, that is, the sheet feeding unit front side plate 222 and the sheet feeding unit back side plate 223 are moved up and down when the timing belt 254 is moved by the forward / reverse rotation of the motor 251.

Front shaft 2 rotatably supported by paper feed unit front side plate 222
A bracket 237 is fixed to each of the rear shaft 236b rotatably supported by the paper feed unit rear plate 223, and a pair of belt speed change rollers 216 (216a, 21
Both ends of 6b) are supported. That is, the first belt speed change roller 216a and the second belt speed change roller 216b are
PB belt 218 supported between the two belt transmission rollers 216a and 216b by the rotation of the shaft 236 (236a, 236b)
Displacement relative to. The shaft 216 (the front shaft 236a and the rear shaft 236b) is driven to rotate by a motor 238 to which the rear shaft 236b is connected. A feeler 239 is fixed to the rear shaft 236b,
The home position of the belt speed change roller 216 is detected by the feeler 239 operating the sensor 240 fixed to the sheet feeding unit rear side plate 223. The belt speed change roller 216 rotates the shaft 236 so that a part of the PB belt 218 is wound around the first belt speed change roller 216a and the second belt speed change roller 216b before the sheet feeding operation. Axis 236
Is rotated in the opposite direction to return the wound PB belt 218, thereby returning the PB belt to its original state.
Control the feeding speed of

The conveyance drive of the PB belt 218 is performed by a transmission device having a gear 242 driven by a motor 241 attached to the rear plate 206 and a gear 244 meshed with the gear 242 and fixed to the shaft 243 of the drive roller 211. This is performed by rotating the 211.

In order to adsorb and transport the recording paper, the PB belt 218 is provided with a charging roller for forming a charge density pattern. In the illustrated example, the auxiliary turning roller 217 is used as a charging roller, but may be provided separately. An AC voltage, for example, ± 2 KV _PP , 26 Hz, is applied to the charging roller 217 at a position before coming into contact with the recording paper from the high voltage power supply 245, whereby charge density −σ, + σ is alternately applied to the surface of the PB belt 218 by, for example, 5 mm.
, A stripe-shaped charge density pattern is formed.

The paper feeding unit 220 is moved up and down in accordance with the position of the PB trays 201 to 204 for feeding paper, and the adjusting roller 212 is moved in accordance with the movement of the driven roller 214 at that time so that the tension is always kept constant. I do. The adjustment roller 212 has an end supported by the front plate 205 and an end supported by the back plate 206 connected to a spring 247 via a wire 246, respectively, and is pulled in a direction for applying tension to the PB belt 218.

In the machine frame of the paper bank device 4, the first PB tray 201 to
Open / close sensors 261, 262, 26 for each of the fourth PB tray 204
3, 264 are provided, and the opening and closing of each of the PB trays 201 to 204 is detected.

For example, as shown in FIG. 20, the first PB tray 201 to the third PB tray 203 as small trays having a maximum loading capacity of 250 sheets are side fences 265 for determining the position of the recording paper to be loaded (to be described with respect to the first PB tray 201). And has an end fence 266. The side fence 265 and the end fence 266 guide the recording paper in three directions. A fence can be provided at the front end in the sheet feeding direction as long as it does not interfere with sheet feeding. Side fence 265 and end fence 266
Can be moved in the direction of the arrow according to the size of the paper. A handle 267 may be provided on the front wall of the PB tray 201 for access.

In FIG. 21, for example, the fourth PB tray 204 as a large tray having a maximum loading capacity of 2000 can be provided with a side fence 268, an end fence 269, and a handle 267 similarly to the first PB tray 201 in FIG. Since the fourth PB tray 204 has a large paper capacity, it is preferable that the side fence 268 be formed in an L shape so as to guide the paper front, rear, left and right so that the paper does not shift. In this case, the L-shaped side fence 268 has a shape that does not hinder sheet feeding.

The transport belt 53 in the copying main body 3 forms a charge density pattern by the charging roller 76 and sucks and transports the recording paper. In the paper bank device 4, the PB belt 218 forms a charge density pattern by the auxiliary turning roller 217 acting as a charging roller. Then, the recording paper is conveyed by suction. Conveyor belt
For this reason, the 53 and the PB belt 218 are formed as endless belts having a dielectric layer 53a capable of holding electric charges on the surface layer and a semiconductor layer 53b on the back surface. Transport belts 53, 21
At least one of the rollers supporting 8, for example roller 5
6, 215 are grounded and arranged to be in contact with the back of the belt.

As shown in FIG. 22, for example, only the charging roller 76 is shown in FIG.
The alternating electric field (AHz) is applied so as to oppose the ground roller 56. The transport belt 53 is moved at a constant speed Umm / s in the direction of the arrow by the drive roller 54, and the position of the pickup roller for contacting and sucking the recording paper is higher than the position of contact with the charging roller 76 in the moving direction of the transport belt 53. It is on the downstream side. Therefore, an AC voltage is applied to the conveyor belt 53 from the high voltage power supply 131 via the charging roller 76 before the recording paper comes into contact with the surface. As a result, a stripe-shaped charge density pattern in which the charge densities-[sigma] and + [sigma] are alternately arranged at a period of U / Amm is formed on the surface of the transport belt 53. Conveyor belt
In the semiconductor layer on the back surface of 53, charges of opposite polarity are induced by the charge density formed on the surface of the conveyor belt.

When the charge density pattern as shown in FIG. 22 is formed, unequal charges 132 are formed near the surface of the transport belt 53 as shown in FIG. Maxwell (Maxw)
ell) can also be obtained.
The recording paper 77 is electrostatically attracted to the transport belt 53 by a force Fx in a direction perpendicular to the surface of the recording paper 77, that is, the sheet, is held without being shifted, and is fed and transported by the transport belt 53. .

When the direction orthogonal to the sheet surface is x, the conveying direction is y, and the direction perpendicular to the conveying direction in the sheet surface is z, the component forces in the x, y, and z directions of the force acting on the unit volume of the dielectric are F. _{Assuming x} , F _y , and F _z ,

Maxwell's stress tensor Force acting on unit volume This adsorption principle is different from a generally known force of attracting charges of different signs, and the recording paper can be adsorbed using the above method without giving any electric charge to the recording paper. For this reason, there is no influence on the transfer process even when the device is used in the paper feeder of the electrostatic recording device.

Although the example of the charge density pattern is shown as a stripe pattern, a checkerboard pattern may be used, and an appropriate pattern can be used.

As shown in Fig. 24, A3 size plain paper is fed to the transport belt, and when the contact length becomes 100 mm, a spring scale 133 is attached to the rear end of the paper, and the suction force is set as the tensile strength. As a result of the measurement, the result shown in FIG. 25 was obtained. At this time, the adsorption area is 300 cm ² .

FIG. 25 shows the result of measuring the attraction force while changing the amplitude of the AC voltage to a constant value, for example, 4 KV _PP , and changing the applied frequency. As a result, in the present invention, a sufficient attraction force was obtained when the period of the stripe shape was set to 20 mm or less, particularly 10 mm or less. Further, as shown in FIG. 26, the applied frequency constant, for example, from the results of measurement of the attraction force varying the applied voltage in the 26H _z, good adsorption force 2KV _PP above were obtained. At this time, it was found from the measurement of the surface potential that the charge density pattern was not formed on the belt at the applied voltage at which no attraction force was generated. For this reason, in order to generate the attraction force, at least an applied voltage higher than the charging start voltage is required.

The same applies to the case where a DC component is superimposed on an AC voltage or a case where a non-uniform alternating voltage is applied from a power supply that outputs a non-uniform alternating voltage.

FIG. 22 shows a belt configuration used in the sheet feeding and conveying device of the present invention. The transport belt 53 is a two-layer type having a surface layer made of a dielectric film (polyester resin 20 μm, volume resistance 10 μm).
¹⁶ Ω · cm), and the lower layer is an endless belt composed of a semiconductor layer (80 μm of carbon dispersed in polyester resin, volume resistance of 10 ⁸ Ω · cm), and is rotatably supported by a driving roller and a plurality of supporting rollers. I have. The charging roller 76, ± from the high voltage power supply 131 2KV, alternating voltage 24H _z is applied. In addition, the transport belt 53 is moved at a constant speed of 120 mm / s in the direction of the arrow by the drive roller. It is. Therefore, before the recording paper is fed to the surface of the conveyor belt 53, a charge density pattern is formed on the surface of the conveyor belt at a cycle of 5 mm. Here, the volume resistance of the back surface of the transport belt 53 is set to 10 ⁸ Ω.
The reason for using cm is that the transfer means had to be 10 ⁷ Ω · cm or more in order to transfer the image on the back surface. In addition, the reason for the difference in resistance from the surface layer was that the attraction force was increased, and the above resistance was selected. However, there is no problem in function as long as the volume resistance of the back surface is practically in the range of 10 ⁷ Ω · cm to 10 ¹¹ Ω · cm.

The paper bank device 4 of the present invention is the same as the transport belt 53.
The PB belt 218 used for the paper feeder is a two-layer type, the surface layer of which is composed of a dielectric film (PET 50 μm), the lower layer of which is an endless belt of aluminum evaporation, and is rotatably supported by a driving roller and a plurality of supporting rollers. ing. The volume resistance of this derivative was 10 ¹⁶ Ωcm. Charging roller 21
7, an alternating voltage of ± 2 KV and 26 Hz is applied from the high voltage power supply B. The PB belt 218 is moved by the driving roller at a constant speed of 130 mm / s in the direction of the arrow, and the sheet feeding position of the recording paper is downstream of the contact position of the electrode of the charging roller 217 with respect to the moving direction of the PB belt. . Therefore, before the recording paper is fed to the surface of the PB belt, a charge density pattern is formed on the surface of the PB belt at a cycle of 5 mm.

The PB belt 218 in the paper bank device 4 sucks and feeds recording paper from the first PB tray 201 to the fourth PB tray 204. For this purpose, the elevating device 250 is operated, and the sheet feeding unit 2
20 moves up and down in front of the first PB tray 201 to the third PB tray 203, and stops at the sheet feeding home position of the first PB tray 201 to the third PB tray 203. In FIG. 2, the fourth PB tray 204
Are displaced with respect to the first PB tray 201 to the third PB tray 203, and the sheet feeding unit 220 can directly move on the recording paper in the fourth PB tray, but the first PB tray 201 to the third PB tray
The fourth PB tray 204 may be arranged in the same row as the tray 203 so as to move up and down in front of the fourth PB tray 204.

The paper feed home position is set at a position above the upper end of the recording paper by a fixed distance, for example, 5 mm above any of the PB trays, and when the paper feed unit 220 moves to the paper feed home position of the selected PB tray, the PB belt 218 is moved. Is located 5 mm above the top edge of the recording paper.

When the PB belt 218 comes into contact with the recording paper and sucks and feeds the paper, a part of the PB belt, that is, a part in contact with the recording paper is shifted until the relative speed with respect to the recording paper becomes almost zero.

In order to change the feed speed of a part of the PB belt 218, that is, the speed relative to the stationary recording paper, a feed speed change unit, for example, a pair of belt speed change rollers 216 (216a and 216b) is used.

In FIG. 27, each of the belt speed change rollers 216a and 216b is a roller having a diameter of 8 mm as an example.
The distance between the centers of a and 216b is
The belt speed change rollers 216a and 216b are turned by the motor 238 around the substantially center point between the axes of the
The 218 is wound around the belt speed change rollers 216a and 216b and unwound. Belt variable speed roller 216a around the center O ₁ in FIG. 27, PB belt showing the 216b by the solid line is simply turning angle θ from the release position in contact.

When the PB belt 218 itself is not conveyed, the amount of movement 1 of the PB belt caused by turning the belt speed change rollers 216a and 216b by θ (rad) is as follows: l = 2γθ + 12 (1-cos θ) Is the winding radius of the belt speed change rollers 216a and 216b.

From the relationship θ = ωt, the transition speed V is represented by the time derivative, and V = 2γω + 12ωsin ωt. Here, ω is the rotational angular velocity.

When the PB belt 218 moves at a constant speed of 130 mm / sec and the paper feeding unit 220 descends at 150 mm / sec, the PB belt 218
Since the contact area with the recording paper moves at 280 mm / sec, this speed needs to be canceled in order to stop the PB belt 218 in the contact area with the recording paper. Therefore, if the displacement speed V is set to 280 mm / sec, the angular speed ω, that is, the drive speed of the motor 238 rotating the shaft 236 can be obtained. That is, in the case of the first PB tray 201 to the third PB tray 203, the paper feeding unit 220 is moved from the paper feeding home position shown in FIG. 28A to the position where it comes into contact with the recording paper shown in FIG. 28B.
At a speed of 50 mm / sec, the belt speed change roller 216 is moved to the belt speed change rollers 216a and 216b as shown in FIG.
The belt speed change rollers 216a, 216a are moved in a direction in which the belt 218 is wound around the belt
6b is turned. The portion of the PB belt 218 that comes into contact with the recording paper is almost stationary, and the recording paper is electrostatically attracted by the charge density pattern of the PB belt 218. Thereafter, the sheet feeding unit 220 is returned to the sheet feeding home position shown in FIG. 28C.

In the case of the fourth PB tray 204, the recording paper 77 is supplied by suction in the same manner. In the case of the fourth PB tray 204, since the leading end of the recording paper 77 is sucked away from the contact area of the PB belt 218, if the recording paper is transported as it is, the recording paper is nipped by the driven roller 214 and the auxiliary roller 219. Instead of the tip
You will be away from the PB belt. So PB belt
218 is the second position from the paper feeding home position shown in FIG.
9 Lower to the position shown in FIG.
After the paper feed unit 220 is lifted and returned to the paper feed home position, as shown in FIG. 29C, the recording paper is retracted by a certain amount to a position where the leading end of the recording paper contacts the driven roller 214 as shown in FIG. Let it.

For example, if the paper feeding unit 220 is moved backward by 20 mm, the time required for the paper feeding unit 220 to return to the paper feeding home position is 5 (mm) / 150 (mm / sec) = 0.033 (sec). The speed is 20 (mm) /0.033 (sec) = 600 (mm / sec). Since the PB belt 218 is driven at a constant speed of 130 mm / sec, when the paper feeding unit 220 moves up at 150 mm / sec, the PB belt 218 is 600 + 130−150 = 580 mm / sec at the contact surface with the recording paper. The belt speed change roller 216 makes the winding release turning movement so as to be returned. For this reason, the above transition speed V is set to 580 mm / sec.
Is set to control the speed of the motor 238.

In preparation for the deceleration of the recording paper contact area of the PB belt 218 in the next recording paper feeding step, the belt speed change roller 216 is swung in the range between adjacent recording papers to be conveyed.

In contrast to the structure shown in FIGS. 27 to 29, in which two rollers are pivoted, as shown in FIGS. 30 and 31, two fixed rollers 216 'and one transmission roller disposed therebetween are provided. No. 216 ″.
The drawing shows the first PB tray 210 to the third PB tray 2 as shown in FIG.
FIG. 31 shows an example used for the fourth PB tray 204 as shown in FIG. 29. In FIG. 30, the speed change roller 21 is shown.
6 "moves to the paper feeding home position shown by the solid line, and moves down to the left in the figure while descending from that position to the position in contact with the recording paper to reduce or stop the speed of the recording paper contact area of the PB belt, At the position where the sheet returns to the sheet feeding home position, the displacement roller 216 "is displaced to the leftmost position in the drawing.

FIG. 31 is different from the example of FIG. 30 in that the recording paper contact area of the PB belt is displaced backward in the opposite direction.

Paper feed unit 220 is 150mm / s from paper feed home position
The time required to descend 5 mm in ec and contact the recording paper is 5 (mm) / 150 (mm / sec) = 0.033 sec. During this time, the PB belt 218 is driven at a constant speed of 130 mm / sec and fed The displacement roller 216 ″ is displaced in the negative direction at 280mm / sec in order to cancel the descending displacement by the descending speed of 150mm / sec of the unit 220. Since the displacement is performed in 0.033sec, the displacement amount is 280 (mm / sec). × 0.033 (sec) = 9.3 (mm) For this purpose, the displacement roller 216 ″ is 9.3 (mm) / 2 = 4.7 (mm) at a speed of 280 (mm / sec) / 2 = 140 (mm / sec). It is only necessary to move at a constant speed to the left in the figure.

In FIG. 31, since the leading end of the recording paper is further fed back to the position of the driven roller 214, the displacement roller 216 ″ has a speed of 290 mm.
It moves at a constant speed to the left in the figure with a displacement of 9.7 mm per second.

The speed change operation is performed by constant speed control during a period from the line connecting the axis of the fixed roller 216 'to the point where the axis of the displacement roller 216 "advances to the left, that is, a total displacement of 14.4 mm.

Next, although there is a part which is not directly related to the present invention, the electrical equipment and the like of the new copying machine will be described.

In FIG. 32, the main control board 401 has a CPU inside,
It consists of ROM, RAM, timer, I / O port, serial, etc. A one-chip CPU including these functions may be used. The entire sequence control is performed by the main control board 401.

The apparatus will be described by separating it into a copy main body side and a paper bank side.

First, the electrical system on the main body side will be described. The main unit can be roughly divided into functions according to functions, such as image formation, 1st PB tray,
It is related to the 2nd PB tray, related to both sides, related to transport, and other related.

First, other relations will be described. Reference numeral 402 denotes an operation display board, which is capable of serial communication with the main control board and exchanges commands or data. Reference numeral 2 denotes a scanner unit, and the scanner control board 408 transmits and receives read image data and transmits and receives commands and data. The description of the scanner section is omitted because it is not directly related to the present invention.

Next, a description will be given of image formation. Reference numeral 403 denotes a main motor, which is a motor for driving a photosensitive member, a fixing device, a cleaner, and other driving rollers of a transport device, and a driver 405. Reference numeral 406 denotes a fixing temperature controller for keeping the fixing temperature constant.

The image data read by the scanner is sent to the semiconductor laser 21 and its beam signal is main-scanned by the polygon motor 26 driven by the polygon motor driver 407. The synchronization detection sensor 30 is a sensor that takes image data writing timing.

The charge removing lamp 36 removes the charge of the photoconductor. 41
Reference numerals 0 and 409 denote a developing motor and its driver. A photo sensor 37 detects a standard pattern. Reference numeral 411 denotes an image forming system high-voltage power supply, which can individually turn on / off a charging corona, a developing bias, a transfer corona, and a cleaning bias.

Next, electrical components related to the first tray 52 'of the feeding tray 52 will be described. 110A is a paper feeding solenoid, 119A is a powder clutch, 122A and 415 are a PB tray motor and its driving driver, and the motor uses a stepping motor. Upon receiving a pulse signal from the main control board, the drive driver excites the stepping motor so as to control the moving amount by the number of pulses and the moving speed by the pulse frequency. In this example, the motor is used in the self-starting frequency range. However, when the load torque is large, slow-up and slow-down control may be performed.

The encoder 120A is used for detecting the remaining amount of paper, that is, the remaining amount of recording paper. 94A is a paper end sensor,
This is a sensor for detecting the presence or absence of recording paper on the first tray.

110B, 119B, 122B, 416, 94B, 120B is the second tray 52 ″
This is an electrical system that performs the sheet-related operation of the first tray, and has the same configuration and function as the first tray.

Next, the transport related will be described. Manual clutch 13
6 is driven at the time of manual paper feeding to convey the recording paper. The manual feed sensor 134 is a sensor that detects the paper position at the time of paper feeding.

125 and 412 are a belt drive motor and its driver,
The transport belt 53 is rotated at a constant speed, and in this example, a rotation operation is performed by a pulse signal from the main control board using a stepping motor.

The registration sensor 135 detects the leading edge of the recording paper fed and conveyed from each of the trays 52 'and 52 ", calculates the laser writing start timing from this, and turns on / off the image forming system and the duplex conveying system. The timing is determined.

Reference numerals 68 and 413 denote roller moving drive motors and their drivers, which perform a rotating operation in response to a pulse signal from the main control board, similarly to the belt drive motor 125. However, the pulse input to the driver to reduce the transport speed of the transport belt to zero is applied to the belt drive motor driver 41.
The belt can be stopped by giving a pulse signal of 1/2 frequency of the pulse signal applied to 2. further,
The roller movement direction can be controlled by the CW / CCW switching signal. In this case, the CW (clockwise) side is the direction when the belt is temporarily stopped, and the CCW (counterclockwise) side is the direction when the roller is retracted to the home position.

The home sensor 71 detects the home position of the roller.

Reference numeral 414 denotes a high-voltage power supply (A) that generates an AC high-voltage power supply, and applies a high voltage to the belt as the transport belt 53 moves to form positive and negative charge patterns on the belt. An uneven electric field is formed by this charge pattern, and the recording paper can be electrostatically adsorbed on the belt. The attraction force of the positive and negative charge patterns depends on the pitch and the applied voltage level. The maximum suction force is obtained at an appropriate pitch interval, and the sheet is conveyed in the region of the maximum suction force. That is, the applied frequency at which the maximum attraction force is obtained with respect to the belt speed is determined. Further, when the pitch interval is reduced, that is, when the applied frequency is increased, there is a pitch interval at which the attraction force becomes zero, which has the same effect as discharging the belt. This power supply is 3
Controlled by these signal lines, it performs suction of the recording paper, static elimination on the belt, and switching of the high voltage level for the thick paper.

The paper upper limit sensor 126, the tray open / close sensor 124, and the paper size sensor 93 relate to the paper feed tray 52 or the first tray 52 'and the second tray 52 ".

Next, the screen image forming-related will be described. 417, 41
Reference numerals 8, 125, 420, and 419 denote electrical systems related to both sides, a double-side switching solenoid 417 performs switching of the pawl 41, and an inversion switching solenoid 418 includes first switching claws 46a and second switching claws 46b.
Is switched. The reversing sensor 125 detects the presence or absence of the recording paper on both sides, and takes the timing of the reversing signal given to the reversing motor 420 and its driver 419.
This forward / reverse reversing motor is formed by a motor that rotates forward / reverse at a linear speed faster than the image forming / transporting system.

Reference numeral 421 denotes a supply solenoid, which is a solenoid for switching the switching claw 13 for supplying recording paper from the paper bank device 4 onto the first tray 52 '. The paper bank paper feed sensor 139 detects the leading edge of the recording paper from the paper bank side and adjusts the ON / OFF timing of each load on the main body side based on the detection.

 Next, the electrical system on the paper bank side will be described.

Reference numerals 241 and 425 denote a PB belt driving motor and its driver, which have a function of conveying the recording paper to the main body side. Here, a stepping motor is used.

Reference numerals 251 and 422 denote a paper feed unit drive motor and a driver, which move the paper feed unit 220 up and down. Reference numeral 256 denotes a sheet feeding unit position sensor, which performs position control based on the sensor.

Reference numerals 230 and 423 denote a pickup drive motor and a driver, which perform a recording paper pickup operation using a stepping motor. The pickup sensor (the home position sensor) 235 is a reference sensor for controlling the position of the pickup roller.

238 and 424 are PB belt variable speed motors and drivers,
An operation of temporarily stopping the belt to hold the recording paper by suction is performed. 240 is a PB belt variable speed reference sensor that detects a reference position.

Reference numeral 233 denotes a paper upper end detection sensor, which sets the position of the paper feed unit 220 with respect to the recording paper.

Reference numeral 427 denotes a high-voltage power supply (B), which applies a high voltage to the PB belt similarly to the high-voltage power supply (A) to generate an attraction force on recording paper.

A paper size sensor 426 detects a paper size on the first, second, third, and fourth PB trays. Reference numerals 261, 262, 263, and 264 denote tray open / close sensors, which detect open / close of the PB tray.

In the printer mode, the apparatus is instructed by a control command from a host computer that sends out print data. On the other hand, when a copying machine is provided with a reading scanner, an operation unit having input keys for giving instructions and a mode indicator is required. Main input keys are print, stop key to support start and stop of the copier, 10 keys to set the number of copies, automatic density to adjust copy density, density adjustment key, scaling to specify magnification, zoom key, etc. Having. The operation unit is constituted by an LCD panel indicating the input state.

As shown in FIG. 33, the operation unit 600 has an operation panel 601 and, in addition to the above-mentioned various keys, a continuous page copy for continuously copying a two-page spread document such as a book on two recording sheets. Key 603, double-sided key 604 for copying on both sides of recording paper, continuous paper feed key 605 for continuously feeding recording paper
A replenishment key 606 for transporting the paper in the B tray to the upper stage is provided.
When each mode is set by the key input, the LCDs 608 to 61 provided corresponding to the respective keys are set.
1 lights up. The continuous page mode, the duplex mode, and the continuous paper feed mode are independently established. When the three modes are designated together, the continuous page continuous mode is set, and high-speed copying of a book document is performed. The replenishment mode is to convey and replenish the recording paper to the short upper tray of the transport path when the apparatus is not operating at a predetermined time such as at night, and this can be set by key input or performed automatically. good. The thick paper display 607 is turned on by inputting the thick paper key 602, and the paper feeding conditions (for example, charge pattern intensity, charge pattern area, etc.) from the paper feed tray and paper bank are changed.

The multi-stage paper feeder of this machine uses the paper display section 6
Appears on 13. The recording paper sizes stored in the paper trays of each stage are displayed on the respective size indicators 614 to 619,
The remaining amount of paper in each row is also displayed. In the figure, the fourth PB
A4 size is selected for the tray 619. In addition, a tray for feeding paper is sequentially selected by key input of the paper selection key 621, and the selected tray is displayed on the paper display unit 613. On the other hand, when the manual feed door of the manual feed unit 130 is opened, the manual feed display 620 is turned on, the paper is fed preferentially by the manual feed unit 130, and the selected tray display of the paper display unit 613 is turned off.

The operation of the present apparatus will be described based on a flowchart and a time chart.

In FIG. 34, after the power is turned on, initialization is performed, and the roller movement initial operation is performed. This is an operation of retracting the first driven roller 55 to the home position. Thereafter, a paper feeding initial operation is performed based on FIG.

After the initial paper feeding operation, a new mode is set if the mode is changed. The mode change is input to the main control board as coded serial data by key input of the operation display board. As a result, a reception interrupt occurs and serial data is determined. FIG. 36 shows a flowchart of the reception interrupt.

After the mode is set, it is determined whether or not the paper feed initial operation needs to be executed again. The first is when the paper supply tray is pulled out and the recording paper is resupplied by the user's hand and reset, and the second is when the replenishment operation is completed and
The third is when the duplex mode is set. In either case, the process returns to the previous state by setting or resetting the flag, and determines whether or not to perform the sheet feeding initial operation.

After that, size detection, heater temperature control, remaining amount detection, paper feed priority, suction voltage setting, replenishment processing, double-sided possible number detection, page continuous copying double-sided number possible detection, various sensor inputs,
After executing a subroutine group of processes outside the pulse operation such as setting and resetting of the flag, it is determined by the flag whether or not the print SW has been pressed. If the print SW has not been pressed, the process returns to the mode change process again and the print SW
Repeat the loop until is pressed. When the print SW is pressed, the pulse counter is reset and starts counting. The pulse counter here is a counter that counts up by a timer interrupt shown in FIG. 37, is an internal interrupt that occurs in the CPU at regular intervals, and an interrupt time is set by initial setting.

After the start of counting, a pulse table corresponding to each mode is set, and comparison with a pulse count value is performed.
Here, the pulse table corresponding to each mode is a table in which the number of pulses at the ON / OFF timing of each load divided for each mode. If the table value and the counter value do not match, the process branches off to execute the above-described non-pulse operation process. If the final copy process has not been completed, the process returns to the previous step. When the table value and the counter value match, a subroutine on the pulse table is executed, the pulse table is incremented, a process outside the pulse operation is executed, and if the final copy process has been completed, the process returns to the previous step and repeats the loop.

In the paper feeding initial operation, in FIG. 35, pulse output is performed from the main control board to the roller movement motor 68, the belt drive motor, and the respective drivers. In this case, the number of pulses corresponding to the moving amount and the pulse frequency corresponding to the moving speed are set in advance. Next, after the paper feeding solenoid 110 is turned on, the paper feeding timer counter is reset to start counting.
The paper feed counter is a counter that is incremented by the timer interrupt, and determines whether 0.1 seconds have elapsed from this count value, and turns off the paper feed solenoid 110 after the elapse. After that, the encoder timer counter is reset and counting is started. This encoder is a tray motor 12
A sensor 120 attached to a drive shaft 115 driven by a second shaft via a powder clutch 119. Then, after the powder clutch is turned on, a pulse is output to the tray motor drive driver. The number of pulses at this time may be such that the rising tray 82 on which no recording paper is loaded comes into contact with the conveyance belt 53 at the lowering position of the recording paper contact portion of the conveyance belt 53. The frequency may be set to a high level that does not need to be changed. afterwards,
When the encoder interrupt shown in FIG. 38 does not come in, it is determined that the counting is completed, and the counter value is stored in the RAM. The counter value and the remaining amount of recording paper on the tray are in an inverse relationship, and the remaining amount of recording paper can be detected based on this value. After the pulse output to the tray motor, the sheet feeding solenoid 110 is turned ON / OFF as described above, and after the pulse output to the belt moving motor 68, the rotation direction of the belt moving motor is switched to, for example, CCW (counterclockwise), and Pulse output and retracted to home position and home sensor 71
Is detected, the pulse output is stopped, and the process ends.

A timing chart showing the above operation is shown in FIG.

Incidentally, the initial sheet feeding operation is performed for the first tray 52 'and the second tray 5'.
2 ″ are performed individually.

 The fed recording paper is transferred and fixed in a known manner.

Although the following is not necessarily directly related to the present invention, various operation modes will be described.

[Continuous paper feed mode]

In the continuous paper feed mode, serial data indicating the continuous paper feed mode is transmitted from the operation display board by input of the continuous paper feed key 605 on the operation unit shown in FIG. Upon receiving this, the main control board generates a reception interrupt (FIG. 36) and sets the continuous paper feed flag.

When the continuous paper feed flag is set, a new mode is set in the main flowchart of FIG. 34, and when the print SW is pressed, ON / OFF of each load is turned on and off according to the pulse table shown in the timing chart of FIG. 46. Execute the sequence operation. Before describing the timing chart, the paper feed priority will be described. This means that when a recording sheet having the same size, the same direction, and the same paper quality as the first tray 52 'is selected, feeding is performed prior to the first tray 52'. It is set in the external processing subroutine group. This aims to shorten the first copy time and increase productivity. No. 39
The figure shows a paper feed priority flowchart.

Next, a timing chart of the continuous copy mode shown in FIG. 45 will be described.

When print SW is pressed (Step 1), main, developing motor, charging corona, cleaning bias (CL bias)
Is turned on (step 2). At the same time, a pulse is output to the belt drive motor (Step 3), the conveyor belt 53 is driven, the high-voltage power supply (A) is turned on at the suction frequency (Step 4), and the charge roller 26 forms a charge density pattern. Done. Thereafter, pulse output to the roller movement motor 68 (Step 6), forward / reverse rotation in the clockwise direction (CW) and counterclockwise (CCW) (Step 7), detection of the home sensor 71 (Step 8), paper feed solenoid 110A ON (process 9), powder clutch 119A
ON (step 10) and the pulse output to the PB tray motor 122A (step 11), the sheet feeding operation is performed. When the first tray 52 'and the second tray 52 "are used at the same time, such as A3 size recording paper, the feed solenoid 110B is turned on (step 12), the powder clutch 119B is turned on (step 13), and the tray motor 122B is turned on.
(Step 14) is performed simultaneously. FIG. 46 shows a detailed timing chart of the sheet feeding operation.

In FIG. 46, a pulse output of clockwise (CW direction) rotation is output to the roller moving motor 68. While this output is being performed, the belt is in a stopped state. Feed solenoid in synchronization with pulse output to roller movement motor 68
When 110 is turned on, the conveyor belt descends from the normal position to the descending position in 0.15 seconds as shown in the descending movement diagram. After that, a pulse output to the tray motor 122 is given to press the recording paper against the transport belt 53 to perform suction. At this time, the number of pulses given to the tray motor 122A may be a number of pulses having a thickness for one recording sheet plus a margin for pressing because the tray has already been raised by the initial paper feeding operation.

After the sheet is fed, the roller movement motor 68 is switched in the CCW direction to output a pulse to retract the pickup roller to the home position, and returns to the home position detected by the home sensor 71.

In the case of continuous paper feed, the paper feed operation is started at a timing when the trailing edge of the fed recording paper passes the right fence 79 of the paper feed tray, so that the paper feed is almost zero.

Referring back to FIG. 46, after the paper feeding operation is completed, the recording paper is detected by the registration sensor (step 15). Thereafter, the subsequent pulses are counted and the ON / OFF timing of each load is set. Thus, the ON / OFF timing of the write gate, the developing bias, and the transfer corona is set to perform image formation (steps 16, 17, and 18). The timing chart of FIG. 45 shows that the A4 size recording is sequentially performed from the first tray 52 '. In this example, three sheets are fed and conveyed to form an image.

The suction OFF timing of the high voltage power supply (A) is turned off at the timing when a charge pattern is formed up to the rear end of the final recording sheet, the charge elimination is turned on, the adsorption charge pattern on the belt is erased, For example, the recording paper is prevented from being attracted by the initial paper feeding operation. For this reason, the machine is stopped when the final recording paper is discharged out of the machine or when the static elimination of the suction area is completed, whichever is longer.

[Page continuous shooting mode]

FIG. 47 shows a timing chart of the continuous page shooting mode.
The page continuous shooting mode is a mode in which the sheet feeding operation of the first tray 52 'and the two trays 52 "is simultaneously performed, and two recording sheets are simultaneously attracted and conveyed on the conveying belt to form an image.
The timing chart is an example in which the simultaneous sheet feeding operation is performed twice to form a total of four images. In the same manner as in the continuous paper feed operation mode, a reception interrupt is input by inputting a page continuous shooting key from the operation unit, and a new mode is set by a page continuous shooting flag set. In FIG. 47, the image formation is basically the same as in the continuous paper feed mode, and the difference is that the first tray
The sheet feeding operation is performed by synchronizing the timings of steps 9, 10, and 11 relating to 52 'and steps 12, 13 and 14 relating to the second tray 52 ".
110A and 110B are operated synchronously, the recording paper contact area of the conveyor belt 53 is simultaneously lowered, and the rising tray of the first tray 52 'is raised.
82A and the ascending tray 82B of the second tray 52 "rise in synchronization, and simultaneously suction and transport the recording paper of the first tray 52 'and the recording paper of the second tray 52".

Further, the timing of the next paper feed operation may be set after the trailing edge of the recording paper fed from the second tray has passed through the right fence 79 in contact with the leading edge of the recording paper on the first tray. Therefore, ON / OFF or detection timing as in steps 6, 7, and 8 is obtained. Steps 4 and 5 have timings as shown in the figure for the adsorption of the recording paper area and the charge elimination.

[Continuous feed duplex mode]

In the continuous paper feeding duplex mode, after forming an image on the front surface, the recording paper is reversed by a reversing device and temporarily stored on the second tray 52 ″, and after a few sheets are stored on the second tray 52 ″, the second Tray 5
2 ", and the back side image is formed. The problem here is that the second recording sheet is stored on the second tray 52". The number of double-sided prints (the number of stackable prints in the second tray 52 ″) is determined from the remaining amount. The remaining amount is detected in the above-described main flowchart.
Here, detection of the number of double-sided copies is described with reference to the flowchart of FIG.

In the main flowchart, when the double-sided flag is set, the sheet supply initial operation is performed as described above. Thus, the encoder count value is set in the RAM. This value is a for the first tray and b for the second tray. The detection of the number of double-sided printable sheets is set in a subroutine group of processing outside the pulse operation in the main flowchart. When executed, first, the state of the double-sided flag is determined, and if it is not set, the process is terminated. If it is set, the number c of double-sided printable sheets is calculated from the remaining amount b of the second tray. In this process, the number of double-sided prints may be sequentially calculated by calculation, or the number of double-sided printable sheets may be called for a value b preset in the table. Next, it is determined whether or not the number of pieces> c. If YES, an error is displayed on the operation display board, and the number of pieces is c.
Transmission is performed so as to display an instruction to set the following. Thereafter, the processing after the print SW flag invalidation processing (the processing does not start even if the print SW is pressed in this state) is terminated. When the user sets the number of copies to be equal to or less than c and performs the double-sided number detection again, the number of copies is no more than c.
Is sent to the operation display board, the error display cancellation is transmitted, the print SW flag validity processing is executed, and the processing is terminated.

When the print SW is pressed in this state, the operation is performed as shown in the timing chart of FIG. Print SW
Is pressed, steps 2, 3, and 4 are performed in the same manner as in the continuous paper feed mode shown in FIG. The difference is that the powder clutch 119B in step 13 is turned off, and the raising tray 82B of the second tray 52 ″ is lowered.

Thereby, a space for accommodating the recording paper on which the surface image has been formed is secured. The timing chart shown in FIG. 48 shows an example of two-sided continuous sheet feeding of two sheets. The sheet feeding operation in Steps 6 to 11 and the image forming-related operation in Steps 15 to 18 are the same as those in the continuous sheet feeding mode, and a description thereof will be omitted. Thereafter, the double-side switching solenoid is turned ON when the leading end of the recording paper on which the surface image is formed exits the fixing device 38 (step 19), and the two continuously fed recording papers are guided to the return path 44.

Next, the sheet is conveyed to the reversing path 45 by the roller 47. When the first sheet of recording paper is guided to the reversing roller 48, the forward / reverse reversing motor has already rotated at high speed on the forward side (the side to be fed to the reversing tray 45a) (step 21), and is quickly fed by the reversing roller 48. It is. Next, the tip of the second recording paper is
When detected at 125 (Step 20), the forward / reverse reversing motor is reversed at high speed (Step 21). In synchronization with this, the inversion switching solenoid is turned on (step 22). The reverse rotation operation is performed until the rear end of the first recording sheet passes the reverse roller 48, and then the operation is switched to the normal rotation operation. In this way, the second recording paper is also guided on the reverse PB tray, and when this is the last recording paper, the reverse rotation operation is performed by the timer count.
The recording paper is stored in the second tray 52 ″. Here, (linear speed of the reversing roller 48)> (linear speed of the roller 47), (linear speed of the reversing roller 48) = (linear speed of the roller 49). This time, a sheet feeding operation is performed from the second tray 52 ″ for backside image formation. The back side feeding operation is basically the same as the front side operation, except for the powder clutch 119B.
The pulse output (step 14) to the tray motor 122B is set to be the same as the number of pulses given in the sheet feeding initial operation at the same time as the ON (step 13), so that the tray can be raised from the lowered position and the sheet feeding operation can be performed. Subsequent backside image formation is the same as in the continuous paper feed mode.

[Continuous Page Continuous Shooting Double-Sided Mode] The continuous page continuous shooting double-sided mode is selected by a page continuous shooting key and a double-sided key on the operation unit 600 in FIG. As in the case of a book document, this is a mode in which an image is formed so that the front and back sides are in a relationship. In this mode, two sheets of recording paper are continuously fed and conveyed, and pages 1 and 2 of the book document are copied. Is copied on the first recording paper, the second page is copied on the next recording paper, the first page is discharged as it is, and the recording paper on which the second page is copied is stored in a reverse sheet, the second tray 52 ″. You.

The third page of the document is fed to the back side of the recording paper stored in the second tray 52 "for copying the third page of the document, and new recording paper is continuously fed to copy the fourth page of the document. The recording paper on which the third page has been copied is discharged as it is, and the recording paper on which the fourth page has been copied is inverted as in the case of the second page, and then the second tray 52 "
Is stored in. Thereafter, this is repeated. For this reason, in this mode, there is a limit on the number of copies. This is because the transfer belt, the return path, the reverse path, the second tray 52 "
It is determined according to the number of recording papers entering the transport path up. In this example, A4 is a distance for inserting four sheets, and A3 is a distance for inserting two sheets. In other words, the detection of the possibility of the continuous printing of several pages on both sides according to the recording paper size is performed. This is performed according to the flowchart shown in FIG.

First, it is determined whether or not the page continuous double-sided mode has been entered according to the flag, and the set number of sheets is compared according to the recording paper size.
If the value is equal to or more than the set value, an error display and an instruction display for setting the number of sheets to be equal to or less than the set value are performed. If the set value is satisfied, cancel the display and accept the print SW.
When the print SW is received, the operation is performed according to the timing chart shown in FIG. FIG. 49 shows a case in which paper is fed and conveyed only from the second tray 52 ", in which the first sheet of continuous recording paper is discharged and the second sheet is stored in the second tray 52".
The operations shown in 19, 20, 21, and 22 are performed. After that,
The operation is similar to the continuous double-sided mode.

(Thick paper mode)

When the cardboard key is pressed from the operation unit, a reception interrupt occurs on the main control side. Here, the thick paper flag is set. Attraction voltage setting is performed in a subroutine group other than the pulse operation in the main flowchart. FIG. 42 shows a flowchart of the attraction voltage setting. First, it is determined whether or not the cardboard flag is set. If the cardboard flag is set, the signal line for switching the suction voltage of the voltage power supply (A) is turned on to set a high voltage level suitable for cardboard suction. If the flag is not set, the signal line is off, and the high voltage level is suitable for normal plain paper suction.

(Supply mode)

When the replenishment key is pressed from the operation unit, a reception interrupt occurs on the main control side. Here, the supply flag is set. The replenishment process is performed in the subroutine group outside the pulse operation in the main flowchart. FIG. 43 shows a flowchart of the supply process. First, the number of sheets d to be supplied to the first tray 52 'is calculated. After that, supply solenoid
Turn ON to perform the paper feeding operation from the paper bank.

When the number of sheets actually fed becomes d or more, the replenishment process is terminated.

[Transfer of recording paper from the paper bank]

The transfer of the recording paper from the paper bank to the main body side can be performed smoothly without any slack or tension by making the transport speeds of the transport belt and the PB belt equal. For example, since the speed of the transport belt 53 on the main body side is 120 mm / sec, it can be realized by setting the linear speed of the PB belt 218 to 120 mm / sec. However, in this example, a case will be described in which the linear velocity of the PB belt is set to 130 mm / sec in order to increase the productivity on the paper bank side.

If (PB belt linear velocity)> (transport belt linear velocity), the first
By moving the driven roller 55 from left to right in FIG. 2 when the recording paper is transferred from the PB belt 218 to the conveyance belt, the conveyance belt and the recording paper apparently come into contact with each other at zero relative speed, and the charge turns. And is conveyed to complete the delivery. A timing chart showing this situation is shown in FIG. When the recording paper is conveyed from the paper bank side, the paper bank paper feed sensor (PB paper feed sensor) 139 is turned on, and the delivery operation is performed based on this. In addition, a pulse is output to the roller moving motor, and the forward and reverse rotation of the roller moving motor is performed. This pulse frequency has a linear velocity difference of 10 mm / sec (130 mm /
A pulse frequency of the speed at which the roller moves at (sec-120 mm / sec) may be given. Also, the number of pulses at this time may be given by the amount of retreat to the home position detected by the home sensor. After retreating to the home position, a pulse is given on the CW side.

As a result, apparently, the recording paper comes into contact with the transport belt,
Delivery takes place. Thereafter, the tip is detected by the registration sensor. Thereby, the subsequent timing related to image formation is determined.

Fig. 50 shows the timing of the transfer of two sheets. After the transfer of the first sheet is completed, the moving roller is switched to CCW to return the moving roller to the initial position, and the number of pulses may be the same as before, The frequency is set to a somewhat higher frequency to increase productivity.

The first tray 52 'and the second tray 52 "in the copying body 3
The paper feeding operation at the time of various copying operations performed by the paper feeding is as described above. On the other hand, paper bank device 4
The operation of the copier by feeding more recording paper is as follows.

The paper bank 4 includes the first PB tray 201 to the fourth PB tray 2
04 tray open / close sensor 261-6 to detect each open / close
It has 34. When the opening / closing operation of each PB tray is detected, the following initial operation is performed assuming that the paper is supplied to the PB tray.

In the paper bank device 4, the positions of the PB trays 201 to 204 are fixed, and the paper is fed from the corresponding PB tray by one moving paper feed unit 220. Even if the remaining amount of paper on the PB tray changes due to feeding, the paper position based on the remaining amount of paper is stored so that the paper position, that is, the position of the topmost paper, does not change, and the paper position is adjusted to the paper supply position High-speed PB tray changing means.

After detecting the opening and closing of the first PB tray 201 to the fourth PB tray 204, respectively, at the highest point of the PB tray that is first selected for feeding, the sheet feeding unit 220 is moved vertically by the paper bank unit lifting / lowering device drive motor 251. Be moved. Here, the highest point of each PB tray is from the first PB tray 202 to the third PB tray.
5 from the height when the maximum loading number of 250 sheets is loaded on the tray 203 or the maximum loading number of 2000 sheets is loaded on the fourth PB tray 204
About 1 mm above, the first to third PB trays are located at a position 30 mm from the bottom plate, and the fourth PB tray is located at a position 205 mm from the bottom plate. The position is defined as the home position of each PB tray.
Also, the upper and lower home positions of the sheet feeding unit 220 are
The home position is the same as the home position of the first PB tray 201 at the top, and the position is controlled downward by a stepping motor from there according to the pulse number. Paper feed unit at this time
The vertical movement speed of the 220 is, for example, 150 mm / sec, and moves up and down by the forward / reverse rotation of the stepping motor. The paper feed unit 220 descends from the home position of each PB tray until it is detected by the paper upper end detection sensor 233 provided in the paper feed unit 220, and the PB belt stops at a position 5 mm above the detected paper upper end. Then, the sheet feeding operation is repeated with that position as the home position of the sheet feeding operation.

Even if the selected PB tray is changed, always
Is stored in the nonvolatile RAM in the main control board 401 as the pulse amount from the home position of the stepping motor. This also allows each PB
The remaining amount of paper in the tray can be determined. Then, the position is set as an initial position at which the sheet feeding unit 220 starts sheet feeding next.
When the paper is selected again, the paper feeding unit 220 is moved from the upper end of the stacked paper below the home position of the PB tray.
It moves directly to a position that is 5 mm above and is detected by the paper upper end sensor attached to the paper feeding unit 220, and repeats the paper feeding operation using that position as the home position of the paper feeding operation.
As a result, even when the remaining amount of paper is small, the selection of the PB tray is changed quickly.

Further, if the paper is not detected by the paper upper end detection sensor 233 at the home position of the paper feeding operation during the continuous paper feeding, the paper feeding unit drive motor 251 feeds the paper to a position where the paper is detected by the paper upper end detection sensor 233. The unit 220 is moved downward to repeat sheet feeding. As described above, the paper feeding unit 220 repeats the paper feeding process from the fixed PB tray while descending as the paper feeding progresses.

The operation of paper feed selection is shown in the flowchart of FIG. When a certain PB tray is selected by the paper selection, it is determined whether or not the first paper supply after opening and closing the PB tray. In the first case, since the remaining amount of paper is not known and the paper feeding position is not determined, since the paper loading amount is already known at the uppermost position B of each of the PB trays, the last paper feeding home position at the last time D is set as the target position X of the paper feeding unit 220, the current position of the paper feeding unit 220 is compared, and the paper feeding unit 220 is moved up and down.

Here, the pickup roller 215 is already in the paper feeding unit 220 in preparation for the vertical movement of the paper feeding unit 220. When the sheet feeding unit 220 reaches the target position, the pickup roller 215 is moved in the sheet direction in preparation for sheet feeding. Next, the upper end of the sheet is detected by the sheet upper end detection sensor 233, and the sheet feeding unit 220 is lowered to reach the sheet feeding home position.
For the second and subsequent times, this operation cannot be performed because the paper feeding unit 220 has reached the last final paper feeding home position position D. At this time, the home position of the paper feeding is stored in the memory buffer D, and the paper feeding operation is used. On the other hand, when the sheet feeding unit 220 reaches the sheet feeding home position, the print display is turned on and the copying is started. Thereafter, the above-described second and subsequent operations are repeated during paper feeding, and the paper feeding unit
The 220 stores the position in the memory buffer D while descending.

The pickup roller 215 of the paper feeding unit 220 attracts the paper in the PB tray to the PB belt 218 during paper feeding,
It is displaced together with the PB belt 218 by a fixed amount, for example, 100 mm in the paper direction. On the other hand, when the paper feed unit 220 is moved up and down due to paper selection, the pickup roller 215 is moved to the right home position and retracted. The movement of the pickup roller 215 is controlled by the PB pickup sensor 2
Paper feed unit 22 from the home position detected at 35
This is performed by the PB pickup drive motor 230 attached to 0. PB
The pickup drive motor 230 is a stepping motor,
Position control is performed according to the number of pulses.

Since the paper bank device 4 feeds paper from the fixed PB tray by the paper feed unit 220 that moves up and down, the paper feed position differs depending on the level of the PB tray to be fed and the paper stacking amount. The transport timing from the paper feed timing to the main body is calculated as follows. PB belt 218 is a stepping motor PB
The paper is conveyed at a constant speed of 130 mm / sec by the belt drive motor 241, and the paper after the operation of the PB belt variable speed motor 238 is 130 mm / s.
Transported by EC. The transport distance changes depending on the vertical position of the sheet feeding unit, and is determined by the number of steps N from the home position of the sheet feeding unit drive motor 251. Since the paper feed unit drive motor 251 moves 0.2 mm in one step, the transport path L of each PB tray is represented by L = N × 0.2 + P. Here, P is a distance fixed by the PB tray, 200 mm for the first to third PB trays, and 120 mm for the fourth PB tray, and the difference depends on the transport distance in the horizontal direction.
Therefore, the transport time T is represented by T = L / 130. The sum of the transport time T and the paper feed time is the time required for feeding the first sheet, and continuous paper feed from the second sheet is independent of the transport time. Further, the paper feeding operation of the continuous paper feeding may be repeated at a constant interval, and A4 size printing can be repeated at 3 seconds / cycle to print at 20 PPM.

The paper feeding operation will be described with reference to the operation transition diagrams of FIG. 28 and FIG. Here, an example is shown in which two belt speed change rollers 216a and 216b are used for the deceleration and stop mechanism of the PB belt 218. FIG. 28 shows the case of feeding from the first PB tray 201 to the third PB tray 203, and FIG. 29 shows the case of feeding from the fourth PB tray 204.

The paper feed unit 220 is located at a position 5 mm above the stacked paper below the home position of the PB tray, and the position detected by the paper upper end sensor 223 attached to the paper feed unit 220 is set as the home position of the paper feed operation. Repeat the paper feed operation. At this time, the pickup roller 215 and the PB belt 218
The flat portion stretched between the pickup roller 215 and the driven roller 214 is located 5 mm above the upper end of the paper stack. Next, the pickup roller 215 of the paper feeding unit 220 is displaced together with the PB belt 218 by 100 mm in the paper direction in order to attract the paper in the PB tray to the PB belt 218 during paper feeding.

In order to attract one top sheet of paper in the PB tray to the PB belt 218, a charge pattern is formed on the PB belt 218 by the charging roller 217 in synchronization with the paper feed timing by an amount equivalent to the paper size before paper feeding.

Lower the paper feed unit 220 by 5 mm and set a PB belt on the upper end of the paper.
Contact 218. At this time, the aforementioned belt speed change roller 216
Is operated so that the feeding speed of the PB belt 218 on the paper contact surface is set to zero. This is performed to improve the adsorptivity of the stopped recording paper in order to adsorb and convey only the recording paper at the highest position, and reduce the conveyance speed of the PB belt 218 to a speed of 130se or less. They may be brought into contact with each other and sucked and conveyed.

In the case of paper feeding from the first PB tray 201 to the third PB tray 203,
Paper, that is, it is adsorbed from the leading edge of the recording paper, and uses the belt speed change roller 216 to transport the paper in the horizontal direction.
While keeping the feeding speed of the PB belt 218 on the paper contact surface at zero,
The paper feeding unit 220 is raised to the home position of the paper feeding operation at a point 5 mm above the paper.

Thereafter, the bending by the belt speed change roller 216 is released, and PB
The paper is transported with the vertical transport moving portion of the belt 218 being straight. At this time, 130 mm / s by the PB belt drive motor 241
The paper is conveyed at a constant speed while being attracted to the PB belt 218 moving at a constant speed of ec.

The winding means of the belt speed change roller is operated between the sheets of the continuous feeding in which the conveyed sheet has passed the belt speed change roller 216 to prepare for the deceleration in the next paper feed process. At this time, the PB belt 218 on the paper feed surface is accelerated, but there is no problem because it is not in contact with the paper.

On the other hand, when the paper is fed from the fourth PB tray 204, the paper is sucked from a position about 20 mm from the leading end of the paper, and the belt
First, the paper is conveyed horizontally leftward. That is, the feeding unit 220 is raised to the home position of the feeding operation at a point 5 mm above the sheet while the feeding speed of the sheet contact area of the PB belt 218 is set to minus (movement in the reverse direction). As described above, in the case of the fourth PB tray 204 as well, the sheet feeding and conveyance can be performed stably since the PB belt 218 absorbs the sheet to the leading end of the sheet.

The PB belt speed change motor 238 for rotating the belt speed change roller 216 is constituted by a stepping motor, and the main control of the timer value corresponding to the drive speed of the PB speed change motor 238 for each time in the belt speed change operation obtained as described above. It is stored in advance in the ROM in the board 401, and the speed control of the PB belt speed change motor 238 is performed while calling it,
And control of forward / reverse rotation.

On the other hand, in preparation for the deceleration in the next paper feed process, the winding operation of the belt transmission mechanism between the papers of the continuous paper supply in which the conveyed paper has passed through the belt transmission roller 216 usually takes about 150 mm between the A4 size papers. For some reasons, the PB belt motor 238 may perform the winding operation at a constant speed.

The sheet feeding operation in the first PB tray 201 to the third PB tray 203 is performed according to, for example, a timing chart shown in FIG. 52,
The sheet feeding operation in the fourth PB tray 204 is performed according to, for example, a timing chart shown in FIG. FIG. 52 shows an example of feeding A3 size recording paper, and FIG. 53 shows an example of feeding A4 landscape size recording paper.

In FIG. 52, the PB belt drive motor 241 is turned on to perform constant speed rotation. Next, the high-voltage power supply B for applying a voltage to the charging roller 217 is operated in accordance with the sheet feeding timing. This start timing is set so that the charge pattern is formed upstream of the position where the PB belt 218 is adsorbed.
A value calculated from the linear velocity is pre-programmed as the position where the charge pattern of 218 is formed. In this example, this value is about 1.48 sec before the suction operation, and this time is the fourth PB tray.
Only 204 is different. Next, prior to the sheet feeding operation, the PB belt speed change motor 238 is rotated forward, and the belt speed change roller 216 or the displacement roller 216 ″ is moved to stand by. At the sheet feeding timing, the sheet feeding unit drive motor 251 is rotated forward. At the same time, the PB belt speed change motor 238 is reversely rotated at a high speed, and the speed in the area of the sheet suction surface of the PB belt 218 is set to zero, and the PB belt
The B belt 218 is brought into contact. Further, the PB belt speed change motor 238 is further rotated in the reverse direction to rotate the belt speed change roller 216 or the displacement roller.
The PB belt 218 is vertically conveyed by retracting the 216 ″ to the left. The paper to be fed and conveyed is provided in the main body paper feed path.
It is detected by the PB paper feed sensor 139 for about 3.2 seconds. The operation end timing of the high-voltage power supply (B) 427 is PB
Since the acceleration and deceleration operations of the belt 218 have occurred, this is the same as the case where the constant speed operation is performed by subtraction, and the belt 218 is operated for a period of 3.2 seconds. When the linear velocity of the PB belt 218 at the charge pattern forming position changes, that is, when the PB belt speed change motor 238
During the operation, the frequency applied by the high voltage power supply (B) 427 is changed so that the charge pattern period of the PB belt 218 is constant. When the linear velocity of the PB belt 218 at the charge pattern formation position is equal to or less than zero, the operation of the high-voltage power supply (B) 427 is optional.
Has FF.

In FIG. 53, the basic operation is the same as in FIG. In the fourth PB tray 204, in order to cause the PB belt 218 to adsorb to the leading end of the sheet, the sheet feeding unit drive motor 251 includes a displacement operation of the adsorption surface of the PB belt 218 in the minus direction.
The reverse rotation of the PB belt speed change motor 238 is further performed at the time of reverse rotation to realize a linear velocity of the sheet feeding surface of -600 mm / sec. The operation timing of the high-voltage power supply (B) 427 is about 1.98 sec before suction because the layout is different from that of other PB trays.
Due to the four sizes, the operation stops while the PB belt 218 at the charge pattern forming position moves at high speed.

As described above, the PB belt 218 has a length equal to the paper size.
The PB belt 218 can be sucked and transported to the charge pattern forming position while the PB belt 218 is stopped.

As a suction device, in addition to the above-described method based on the charge pattern, an ordinary vacuum suction device can be used in some cases.

〔effect〕

According to the present invention, generation of skew during feeding and conveyance of a recording medium can be prevented without providing a registration unit, double feeding can be prevented, and conveyance reliability without jams is extremely high. A feeding device was obtained.

According to the present invention, the frictional force applied to the recording medium by the conveying unit can be reduced to zero or reduced as much as possible, the generation of paper dust can be suppressed, the recording medium conveyance failure due to the paper dust, and the image quality defect at the time of image formation. And a highly reliable feeding / conveying device was obtained.

According to the present invention, the feeding state of the recording medium from the storage means is always constant and reliable, and a special recording medium conveying state adjusting device and a recording medium conveying means other than the conveying means are not required, and the structure is simple, A low-cost feeder was obtained.

According to the present invention, it is possible to always maintain a constant and reliable transfer from the storage unit without changing the entire endless transfer speed from the feeding from the storage unit to the image forming unit, and thus without reducing the copy production speed per unit time. A feeding device capable of feeding was obtained.

By performing a return movement after the trailing end of the sheet feeding medium has passed through the additional moving device, it is possible to prevent external force from being applied to the recording medium being conveyed, and it is possible to reliably prevent all skew jams.

[Brief description of the drawings]

1 is an overall perspective view of an example of an image forming apparatus according to the present invention, FIG. 2 is a schematic front view, FIG. 3 is a schematic illustration of a scanner, FIG. FIG. 5 is a plan view of the conveying means transmission, FIG. 6 is a perspective view of the conveying means transmission, FIG. 7 is a front sectional view of a part of the storage means, and FIG. 8 tilts the partitioning means of FIG. 9 is a perspective view of the partitioning means, FIG. 10 is a schematic front cross-sectional view showing the storage means and a conveying means pressing device as a suction operating means, and FIG. 11 is a view of the conveying means pressing device. No. 10 indicating operating status
FIG. 12 is a perspective view showing a drive system of the conveying unit pressing device, FIG. 13 is a front view of the cam, FIG. 14 is an explanatory diagram of a stopper of the driving system of the conveying unit pressing device, FIG. Is an overall perspective view of the storage means, FIG. 16 is a perspective view showing a drive system of a lifting tray of the storage means, FIG. 17 is a schematic front view of a paper bank device, FIG. 18 is a perspective view of a paper feeding unit, FIG. FIG. 20 is a plan view of a sheet feeding unit, FIG. 20 is a perspective view of an example of a storage unit, and FIG.
The figure is a perspective view of another example of the accommodating means, FIG. 22 is a perspective view for explaining the formation of an alternating electric field on the conveying means, FIG. 23 is a front view for explaining the formation of the alternating electric field, and FIG. FIG. 25 is an explanatory diagram of the test method, FIG. 25 is a diagram showing a relationship between a pitch of an alternating electric field and a tensile force indicating an attractive force, FIG. 26 is a diagram showing a relationship between an applied voltage of an alternating electric field and a tensile force, and FIG. FIG. 28 is an explanatory view of another example of the conveying means transmission device, FIG. 28 is an operation diagram sequentially showing A, B, and C of the operation state of the conveying means transmission device according to FIG. 27, and FIG. FIG. 30 is a diagram corresponding to FIG. 28 of an example in which the relative positions of the gears are different, FIG. 30 is an explanatory diagram of another example of the conveying means transmission, and FIG. 30 is a diagram corresponding to FIG. 30, FIG. 32 is a block diagram of an electrical system of the control device, FIG. 33 is a partial view of an operation unit, FIG. 34 to FIG. 43 are flowcharts, and FIG. Shows a ~ FIG. 50 is a time chart, FIG. 51 is a control flow chart of paper bank device, 52 view and FIG. 53 is a time chart in the control of the 51 views. 52: accommodation means, 53: endless conveyance means 55: driven roller, 63: additional moving device 77: recording paper, 201: accommodation means 202: accommodation means, 203: accommodation means 204 ... Accommodation means, 218 endless conveyance means 216 additional movement means

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuya Fujioka 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Fumio Kurizumi 1-3-6 Nakamagome, Ota-ku, Tokyo No. In Ricoh Co., Ltd. (56) References JP-A-63-242835 (JP, A) JP-A 63-157050 (JP, U) JP-A 60-85543 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B65H 1/00-3/68

Claims (3)

(57) [Claims] A feeder for an image forming apparatus, comprising: a storage unit for storing a recording medium on which an image is to be recorded; and an endless conveyance unit for suction-conveying the recording medium from the storage unit to a predetermined position. The endless conveying means has a belt wound around a drive roller and a driven roller, and is held in a non-contact state with the recording medium when not conveyed, and only a part of the belt is conveyed during suction conveyance. A feeding device configured to be displaceable so as to be in contact with, comprising an additional moving unit that changes a circulation path of the belt,
The additional moving means includes a pair of movable adjusting rollers, and a belt portion in contact with the recording medium generates a variable speed by moving the adjusting rollers. . 2. The image forming apparatus according to claim 1, wherein a belt portion in contact with the recording medium by the movement of the adjustment roller can contact the recording medium in the storage means at a relative speed of zero. Feeding device. 3. The image forming apparatus according to claim 1, wherein a belt portion in contact with the recording medium is decelerated, stopped, or movable in a reverse direction by movement of the adjustment roller. apparatus.