JP3001678B2 - Feeding device for image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a sheet-shaped recording medium such as a transfer paper fed by friction of a rubber roller is transported to an image forming position such as a transfer position by a photoreceptor by a pair of rubber rollers or a belt. It is known to

In such a conventional recording medium feeding / conveying apparatus, a rubber pad for combining or reversing a friction pad with a rubber feeding roller is used in order to prevent a plurality of recording media from being fed one upon another. There is a practice of combining a reverse roller made of paper or providing a corner claw on a cassette containing a recording medium. However, the conventional recording method has a problem that a jam or a skew occurs during the conveyance, and the conventional apparatus has a problem in the reliability of the feeding and conveyance together with the multi-feed.

Further, the structure becomes complicated and the control becomes complicated, so that the cost is increased, and the problems of simplification of the apparatus and reduction of the cost have not been solved.

In order to solve these conventional problems,
An insulative endless belt is wrapped around almost all transport systems in the copying machine, the belt is charged by charging means, and the paper stored in the paper feed tray is sent out by a paper feed roller provided coaxially with the belt support roll. After that, the belt can be electrostatically adsorbed, or the belt can be directly contacted with the paper and electrostatically adsorbed and fed, and at the same time, conveyed by the belt to the transfer area where the photoconductor is contacted and transferred. See, for example,
Japanese Patent No. 212856, Japanese Patent Application Laid-Open Nos. 59-224858 and 59-229585, and the like.

However, in these prior arts, when the paper stored in the paper feed tray is fed by a paper feed roller provided coaxially with the drive shaft of the insulating endless belt, the roller feeds the paper by frictional contact. Paper skew has occurred. When double feeding occurs, the first sheet (upper side) is electrostatically attracted to the belt and conveyed, but the second and subsequent sheets (lower side) multi-fed to the first sheet are fed. It protrudes from the tip of the paper tray, and causes a jam in the next feeding (feeding) operation.

Further, paper dust is generated due to frictional contact, which causes poor paper feeding and poor image quality during image formation.

[0008] Directly by the charged insulating endless belt,
When the paper stored in the paper feed tray is fed, the belt comes into contact with the paper in the rotating state during normal image formation, so that the belt is stretched, lowered, the paper is loaded (the loading state). ) Is not homogenized with great accuracy,
When the contact state between the belt and the paper becomes unstable, skew of the paper tends to occur.

Here, in order to stabilize the contact state between the belt and the paper, it is necessary to arrange both the belt and the paper in the apparatus with high precision.

[0010] Further, since the belt and the roller contact the first sheet (upper side) and the second sheet (lower side) in a rotating state, the first sheet (upper side) and the second sheet (lower side) contact each other. Frictional force was generated, and double feeding could occur.

Further, although the paper is not carried out by frictional separation, a rotating belt comes into contact with the paper, so that a frictional force is generated here and a certain amount of paper dust is generated.

Even if a roller or a belt is used as the sheet feeding means, the state of the sheet being ejected from the sheet feeding tray is not always constant and reliable as described above. It is necessary to provide registration means for adjusting the position with respect to the leading edge of the image and correcting the skew of the sheet, and the structure and control are still complicated.

[0013] Further, a paper feed unit, a resist unit, a transfer unit,
The fixing unit and the paper discharge unit are tied by a single endless belt in this order. First, the endless belt is pressed against the copy paper held in the copy paper feed unit, and the copy paper is frictionally moved from the copy paper feed unit. For example, Japanese Patent Application Laid-Open No. 63-139846 proposes that the sheet is carried out and then transferred to an image forming area after registration. However, according to this conventional technique, when the paper stored in the copy paper feed unit (feed tray) is fed out by the belt, the rollers separate and feed the paper by frictional contact, so that skew or double feeding of the paper occurs. In addition, paper dust is generated due to frictional contact, which causes poor paper feeding and poor image quality during image formation. Further, since the state of feeding the paper from the paper feed tray is always constant and not reliable, it is necessary to provide registration means for adjusting the position of the leading edge of the paper and the leading edge of the image copied on the paper and correcting the skew of the paper. The structure and control were still complicated.

[0014]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a feeding device for an image forming apparatus in which skew, double feeding, and jam are prevented without requiring a registration means. The challenge is to do.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems by providing a storage means for storing a recording medium for recording an image, and an endless conveying means for feeding the recording medium from the storage means to a predetermined position. In the feeding device of the image forming apparatus having
The transfer means has a means for additionally moving only a part in at least one direction of the horizontal direction and the vertical direction, the transfer speed of the part is made variable, and the uneven electric field pattern is formed on the transfer means. The problem has been solved by a feeding device of an image forming apparatus, wherein a charging means for forming is provided, and a non-uniform electric field pattern having a predetermined shape is formed on the conveying means.

[0016]

According to the present invention, the endless transfer means performs a transfer movement at a constant speed, and only a part of the endless transfer means is additionally moved in the horizontal or vertical direction or simultaneously in the horizontal and vertical directions. Depending on the selection of the moving speed, the endless conveying means locally reduces or stops the relative speed with respect to the stationary member, for example, the recording medium, or moves in the opposite direction.

When 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.

The transfer means is formed with an uneven electric field pattern by the charging device, and moves to a feeding position from the storage means.
The charging device is disposed upstream of the storage means in the moving direction of the transfer means. The charging device is configured to apply a high voltage of a constant frequency to form a non-uniform electric field pattern of a constant shape, for example, an alternating electric field pattern when the charging means is charged at a position where the conveying means moves at a constant conveying speed. In addition, when the transfer means is charged at a position where the relative movement speed changes due to additional movement, the voltage applied to the charging device is changed in frequency in accordance with the change in the relative movement speed, and the uneven electric field pattern having a constant shape is obtained. Is formed.

Even if the relative movement speed changes, the density of the charge pattern formed independently of the transfer means is constant, that is, a uniform uneven electric field pattern is formed. By forming a uniform non-uniform electric field pattern, the attraction force to the recording medium is formed uniformly, and stable transportability is obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on an embodiment shown in the drawings.

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

In FIG. 2, the copying body 3 is an image forming section 5
And a paper feeding device 6.

As shown in FIGS. 1 and 3, the scanner device 2 mounted on the copying main body 3 has an integral structure in contrast to an example in which the scanner device 2 is formed as a separate structure separate from the copying main body 3. You can also.

The scanner device 2 has a contact glass 11 on which a document is placed, a document holder 12 for pressing and fixing the document against the contact glass 11, and an optical device. The optical device illuminates and scans the original on the contact glass 11, a lamp 13 that scans and moves with the lamp 13 and reflects light reflected from the original, and reflected light from the first mirror 14. , A second mirror 15 and a third mirror 16 that sequentially reflect the light, and a lens 17 that forms an image of the light reflected from the third mirror 16 on the CCD 18. The second mirror 1 is rotated at half the reading scanning speed of the lamp 13.
The fifth and third mirrors 16 are scanned.

The image forming section 5 built in the copying main body 3 includes a writing optical device 7. The writing optical device 7 is shown in FIG.
4A and 4B, a semiconductor laser 21, a collimator lens 22 for converting a laser beam emitted from the semiconductor laser 21 into a parallel light beam, an aperture 23 for shaping a light beam into a light beam having a constant shape, and a shaping by the aperture 23. And a cylinder lens 24 that enters the polygon mirror 25 with the compressed beam in the sub-scanning direction. The polygon mirror 25 having a precise polygon is rotated at a constant speed in a fixed 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 into fθ lenses 27a, 27b, 27c. The rotation speed of the polygon mirror 25 is
Image information holding means 31, for example, the speed of the photoconductor 31;
It is determined by the writing density and the number of surfaces.

The fθ lenses 27a, 27b and 27c convert the scanning light having a constant angular velocity so as to scan the photosensitive member 31 at a constant speed, and form an image on the photosensitive member 31 so as to have a minimum light spot. It has a tilt correction function.

The fθ lens 27 (27a, 27b, 27
The light after passing through c) 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, and emits a synchronization signal for generating a cue signal in the main scanning direction.
A fixed time after the synchronization signal is output from the synchronization detection sensor 30, image data for one line is output based on image information read from the scanner device 2. The 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 photoreceptor 31 has a drum shape, and has a surface coated with a photosensitive layer. An organic photoconductor (OP) is a photoconductor sensitive to a wavelength of 780 nm of a semiconductor laser.
C), α-Si, Se—Te and the like are known, but in this embodiment, an organic photoreceptor is used.

In general, in the case of laser writing, there are an N / P (negative / positive) process in which light is applied to an image portion and a P / P (positive / positive) process in which light is applied to a background portion. This is a P process.

The charging charger 32 uniformly (-) charges the surface of the photoreceptor 31 by a scorotron method having a grid on the photoreceptor side, and irradiates the photosensitive portion with laser light to lower the potential. As a result, −750 is applied to the background portion of the surface of the photoconductor 31.
An electrostatic latent image of about -800 V and about -50 V is formed on the image area. The electrostatic latent image is developed by a developing device 33 by a developing roller 33a.
With a bias voltage of -500 to -600 V applied, the toner charged to (-) is developed and visualized.

The image visualized by the developing device 33 is transferred onto a recording medium, for example, a transfer sheet or the like, which has been conveyed in synchronization with the photosensitive member 31 by the conveying belt 53 of the sheet feeding device 6, and is conveyed by the conveying belt 53. From the back side of the transfer charger 34 (+)
Is transferred and transferred.

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

The reflection density on the surface of the photoreceptor is measured by a photosensor 37 provided 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. The measurement of the reflection density is performed by writing a constant pattern (for example, a pattern of black or halftone dots) at a position corresponding to the reading position of the photosensor by the writing optical device 7.
The density of the image is determined from the ratio of the reflectance of the pattern portion after development to the reflectance of the photosensitive member other than the pattern portion. 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 transport belt 53
Is separated by the driving roller 54 around which the fixing device 3 is wound.
8 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.

The paper feeding device 6 includes a transport device 51, a housing means,
For example, it has a paper feed tray or a paper feed cassette.

The transport device 51 has an endless transport means, for example, a transport belt 53 that runs endlessly, and the transport belt 53 includes a driving roller 54, a first driven roller 55, and a second driven roller 55.
It is wound around the driven roller 56 and the adjusting roller 57 sequentially. The transport belt 53 is transported at a substantially constant speed by a driving roller 54. The transport belt 53 is a drive roller 5
The photosensitive member 31 contacts from the outside at an image forming position, for example, a transfer position, between the fourth driven roller 55 and the first driven roller 55, and has a predetermined nip width. A transfer charger 34 facing the photoreceptor 31 is arranged facing the inner side surface of the transport belt 53.

First driven roller 55 and second driven roller 56
A suitable number of pickup rollers 58, for example, two pickup rollers 58, are arranged at appropriate intervals inside the conveyor belt 53, and each pickup roller 58 is formed to be vertically movable. The interval between the pickup rollers 58 can be changed as needed by moving one or a plurality of pickup rollers. First driven roller 55 and adjustment roller 57
Is formed so as to be movable in a substantially horizontal direction,
Is formed so that a predetermined tension can always be applied to the transport belt 53 by receiving the tension of the spring 59.

As shown in FIGS. 5 and 6, the first driven roller 55 is rotatably supported by shafts 55a at both ends by bearings 60. The bearings 60 can slide on guide shafts 62 fixed to side plates 61. Is formed as a slider supported by the slider. The shaft 55a may be fixed to the bearing 60, and the first driven roller 55 may be rotatably supported by the shaft 55a. The first driven roller 55, that is, the bearing 60 is reciprocated along the guide shaft 62 by the moving device 63. The moving device 63 performs additional movement of the transport belt 53 in addition to the transport by the drive roller 54, and is used as a feed transmission device. The moving device 63 includes a drive pulley 65 fixed to a drive shaft 64 rotatably supported by the side plate 61, and a side plate 61.
And a driven pulley 67 fixed to a driven shaft 66 that is rotatably supported by the driving shaft 64. The driving shaft 64 is rotationally driven by a 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 substantially horizontally by the slider 60 moving 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 the movement of the first driven roller 55, and is formed so that the transport belt 53 can be maintained at a constant tension. Therefore, the adjusting roller generally moves in the direction opposite to the first driven roller by the same distance as the moving distance of the first driven roller.

Assuming that the moving speed Vmm / s of the first driven roller 55 is 搬 送 of the conveying speed of the conveying belt 53, that is, 周 of the peripheral moving speed vmm / s, that is, V = v / 2, the first driven roller 55 is When moving to the left, the conveyor belt 53 traveling in the direction of the arrow moves from the adjusting roller 57 to the second driven roller 56.
In the section extending to the first driven roller 55 through the above, that is, in the speed fluctuation region, the conveying belt 53 may be apparently shifted to the stopped state and held in the stopped state by the action of the peripheral speed vmm / s and the moving speed Vmm / s. it can. If the recording paper is sucked from the paper supply tray 52 while the apparent 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 one end is apparently stopped and the speed returns to a predetermined speed. In the section extending from the transfer position and passing through the transfer position to the adjustment roller 57 via the driving roller 54, that is, in the constant speed region, the transport belt 53 moves at a constant speed without apparent speed fluctuation. Therefore, the peripheral speed of the transport belt 53 does not change while the recording paper is sent to the transfer position and 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 the recording sheet is stopped, and another recording sheet is transported by the same transport belt 53 during the paper feeding operation, so that transfer, separation, and fixing are affected. Can be done without. In the constant speed region in which the transport belt 53 always travels 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 rightward in the drawing and returned to the home position. At this time, the adjustment roller 57 is also moved.

When the first driven roller 55 returns to the home position, the apparent speed of the speed fluctuation region of the transport 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 on the lower right side of the first driven roller 55 in FIG.
A guide plate 75 is provided between the upper pressing roller 73 and the lower pressing roller 74 so that the recording paper conveyed by the conveying belt 53 from the paper feed tray 52 can be smoothly turned along the first driven roller 55. To assist in transportation.

After the conveyer belt 53 is cleaned of dirt by the belt cleaner 72, a constant charge pattern is formed on the conveyer belt 53 by the charging roller 76 disposed near the belt cleaner 72. As in the case where the charging roller 76 is disposed so as to circumscribe the second driven roller,
In the case where a charge pattern is formed in the speed fluctuation region 3, a constant charge is applied on the conveyance belt 53 by performing control such as changing the frequency of the applied charge in accordance with the feeding speed fluctuation of the conveyance belt 53. A charge pattern can be formed.

The paper feed tray 52 is a recording paper stacking device of a front loading type. The paper feed tray 52 is pulled out from the front of the copying machine 1 and the recording paper 77 is set.
Is pushed into the copying machine 1 to supply recording paper.

The paper feed tray 52 is prepared for each size series of recording paper (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 7 is provided at the center of the paper feed tray 52.
8. On the right side, a right fence 79 is provided, and the central fence 78 is foldable as shown in FIG. When setting A4 size recording paper, place the central fence 78 in FIG.
And put them into two tray chambers 80 and 81 formed on the left and right, respectively. When the A3 size is set, the central fence 78 is opened between the two tray chambers 80 and 81 as shown in FIG.

The central fence 7 is located below the paper feed tray 52.
An ascending tray 82 is provided in each of the tray chambers 80 and 81 formed on the left and right sides of the tray 8.

When the central fence 78 is erected, the tray constituted by the right tray chamber 80 and the rising tray 82 in FIG. 2 is replaced by the first tray 52 'and the tray constituted by the left tray chamber 81 and the rising tray 82. To the second tray 5
Call it 2 ″.

The center fence 78 has an upper face guide 83 and a lower face guide 84 as shown in FIGS.
Corner guides 85 are provided at both ends of the recording paper 4 to prevent 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.
Is installed between 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, the upper face guide 83 is maintained at a predetermined relative position with respect to the lower face guide 84 when there is no load.

A notch 87 is formed at the center of the upper edge of the upper face guide 83 so as to prevent the operator's hand from touching 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. An L-shaped finger 89 is provided at the lower end of the lower face guide 84.
Having. The lower face guide 84 is stopped at a substantially vertical position when the lower face guide 84 is turned upright by being locked by the finger portion 89 being locked by the protrusion-shaped locking portion 90 formed on the frame portion 52a of the sheet feeding tray 52. It does not rotate above. A claw 89a is formed on the finger portion 89, and the lower face guide 84 is prevented from turning in the falling direction by being locked to a hook portion 91 formed on the frame portion 52a, and is held at the standing position. When the claw 89a pushes the upper face guide 83 sideways with such a force that the hook portion 91 is disengaged by the elastic deformation, the central fence 78 turns clockwise in FIG.
The space between the right tray chamber 80 and the left tray chamber 81 is opened as shown in FIG. When the center fence 78 falls, the upper face guide 83 and the lower face guide 84 do not interfere with the recording paper placed on the rising tray 82. It is formed to be buried inside. 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 lifting tray 82 to detect the presence or absence of a recording sheet.

The central fence 78 may be of a detachable type 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 face 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 provided on the upper face guide 8 of the intermediate fence 78.
3 and also another one is a right fence 79
Is disposed directly above the upper face guide 83.

As shown in FIG. 10, each face guide 83
One pickup roller 58 and one or a plurality of other pickup rollers 58 disposed directly above are rotatably supported as a set, for example, on a support plate 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. The support 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 supporting plate 95 is provided with a pressing device 97, for example, a cam device and a spring 96.
Contact by the force of. 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. Press down the upper face guide 83. Carrier plate 9
5 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, in the case of a cam device, the pressing device 97 has 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 extends the range of 144 ° in the outer peripheral shape from the center of the shaft 98 to a radius R ₁ , for example, 10 mm in radius.
And the remaining 216 ° range is set to 10
The distribution center point A is set to a point located at a position of a radius R ₂ , for example, 6 mm from the center of the shaft 98, and the arc surface B and the center point A are connected by a smooth curved surface.

The shaft 98 is connected via a spring clutch 100 to a drive shaft 102 to which a pulley 101 is fixed. 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 has two step portions 1 on the outer periphery.
The stepped portion 105 is formed by a substantially spiral-shaped ratchet wheel, and the claw portion of the locking bar 107 is engaged with one step portion 105 to prevent the stopper 104 from rotating. Lock bar 10
7 is rotatably supported by a support shaft 108 and a spring 109
Thus, it is always held at the engagement position with the step portion 105 or 106. The locking bar 107 has a sheet feeding solenoid 11
When the plunger No. 0 is connected and the solenoid is urged, the locking bar 107 is rotated around the support shaft 108 against the force of the spring 109, and the step portion 105 or 10
6 is released.

When the stopper 104 rotates, the angle between the first step 105 and the second step 106 is set to 120 °, and the locking of the locking bar 107 is released when the first step 105 is locked. Then, the stopper 104 rotates 120 °, the second step 106 is locked to the locking bar 107, and the rotation of the shaft 98 is stopped. In a state where the locking bar 107 is locked to the first step portion 105, the sheet feeding cam 99
The point is in contact with the support plate 95 as shown in FIG. 10, and the support plate 95 is in the pulled up position.

Driven by a motor (not shown)
The rotation of the pulley 101 to which the rotation of pm is transmitted is transmitted to the stopper 104 via the spring clutch 100,
At the time of paper feeding, the paper feeding solenoid 110 is urged to release the stopper 104, and the stopper 104, which has always received the rotational moment, starts rotating because the locking is released,
After 0.25 sec, the paper feeding solenoid 110 is deenergized, and the locking bar 107 contacts 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 stepped portion 106 has passed, and at the time of one rotation, the claw of the locking bar 107 is moved to the first position of the stopper 104.
The stopper 104 is engaged with the step 105 and the stopper 104 is stopped. By this operation, the cam 99 makes one rotation in 0.5 sec. The pickup roller 58 is 4 m in 0.15 sec together with the supporting plate 95.
m descends and stops for 0.2 seconds. At this time, the arc surface B of the cam 99 comes into contact with the supporting plate 95 as shown in FIG.
The holding plate 95 is being pushed down. After stopping for 0.2 seconds, it returns to the original position in 0.15 seconds. A pickup roller 58 and means for pushing down the pickup roller 58;
For example, the pressing device 97 and the holding plate 95 function as suction operating means for operating the suction of the transport belt 53.

The transport belt 53 and the recording paper 77 in the non-feeding state
Is about 4 mm, and the gap with the upper face guide 83 is 2 mm. Therefore, the pickup roller 58
Is moved down by 2mm and the upper face guide 8
3 and descends 2 mm while pushing down the upper face guide 83. At this lowered position, the conveyor belt 53 contacts the recording paper 77. At this time, the recording paper 77 is applied to the transport belt 53 by an uneven electric field due to a charge pattern previously formed on the outer peripheral surface of the transport belt 53 by the charging roller 76.
Is adsorbed. Immediately after the pickup roller 58 moves downward, the rising tray 82 is formed so that the rising tray 82 rises and stops later until the contact pressure between the recording paper 77 and the conveyance belt 53 reaches a predetermined value. And control. 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 for feeding the recording paper from the paper feed tray 52, a transport function for transporting to the transfer position, and a transfer function for contributing to the transfer to the recording paper at the transfer position.

Since the conveyance belt 53 is suction-fed by suction force due to an uneven electric field instead of frictional force, there is no deviation of the recording paper, it has a registration function, there is no generation of paper dust during conveyance, and there is no transfer paper after transfer. There is no need for static elimination.

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

As shown in FIG. 2 and FIG.
Right tray room 80 divided by two central fences 78
And an ascending tray 82 is individually arranged in the left tray chamber 81. As shown in FIGS. 15 and 16, the lifting device 123 that moves the lifting tray 82 up and down has wires 111 fixed to the lifting tray 82 at four locations. Of the four wires 111, the first wire 111a is turned by the first guide pulley 112 and the second guide pulley 113, and the end is wound around the first drive pulley 114. The first drive pulley 114 is fixed to a shaft 115 rotatably supported by the frame 52 a 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
3 is guided to turn.

First wire 111a, second wire 111b
On the opposite side, the third wire 111c and the fourth wire 111d fixed to the ascending tray 82 are respectively wound around a second drive pulley 116 whose ends are fixed to the shaft 115. The third wire 111c is turned and guided by the third guide pulley 117 and the fourth guide pulley 118 similarly to the first wire 111a, and is wound around the second drive pulley 116,
The fourth wire 111d is the fourth wire similar to the second wire 111b.
The guide is turned only by the guide pulley 118 and wound around the second drive pulley 116.

The shaft 115 has one end connected to the output side of the electromagnetic clutch 119 and the other end fixed to the encoder 120. The input side of the electromagnetic clutch 119 is connected to the tray motor 122 via the coupling 121.
The coupling 121 has a driving half 121 a connected to the tray motor 122 and a driven half 121 b 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 the left tray chamber 81, but are formed substantially symmetrically with respect to the center fence 78 in the illustrated example. A rising tray 82 for the right tray chamber 80,
It can be driven by a separate tray motor 122 from the lift tray 82 for the left tray chamber 81. Right tray room 8
When it is necessary to distinguish between 0 and for the left tray chamber 81, A is added after the code for the right tray chamber 80, and B is added after the code for the left tray chamber.

The electromagnetic clutch 119 transmits drive only when the output torque is less than a predetermined value in one rotation direction, and slips when the output torque is more than a predetermined value so as not to transmit the drive. It has become. As a result, the rising tray 82 on which the recording paper 77 is placed is moved from the tray motor 1
However, when the top surface of the recording paper 77 comes into contact with the transport belt 53 and receives pressure, the electromagnetic clutch 119 causes the tray 82 to rise further.
Does not rise, the tray motor 122 stops after a predetermined time, and the top surface of the recording paper 77 is always kept at a constant height.

When replenishing the recording paper 77, the paper feed tray 52 is pulled out from the front of the copying machine 1. At this time, the driving half 121 of the coupling attached to the copying machine 1 is used.
a and the driven half 121b of the coupling attached to the paper feed tray 52 is disengaged, and the lifting tray 82 is lowered to its lowest position by its own weight. 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 has been replenished,
Is pushed into the copying machine 1, the driving half 121a of the coupling attached to the copying machine and the driven half 121b of the coupling attached to the paper feed tray engage with each other. It detects that the paper tray 52 has been set.

When the feed solenoid 110 is operated to rotate the locking bar 107 clockwise in FIG.
07 is disengaged from the first step 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 paper 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 only made a 1/5 rotation (72 °), the first step 105 and the second step
6 comes into contact with the outer peripheral surface. Stopper 104 is exactly 12
When rotated by 0 °, the claw portion of the locking bar 107 becomes the stopper 104.
And stops at the second step 106.

At this time, the cam 99 is stopped with the surface B in contact with the support plate 95, 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. Recording paper 77
When the uppermost surface is contacted with the conveyor belt 53 and receives pressure, the electromagnetic brake 119 stops the operation. After a predetermined time, the tray motor 122 stops. Then, the paper feeding solenoid 110 is operated to rotate the locking bar 107 clockwise. Then, the claw portion of the locking bar 107 is
From the second step 106. 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 paper 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. When the stopper 104 rotates just 240 °, the locking bar 107 is rotated.
Again hits the first step 105 of the stopper 104 and stops. 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 ".
When the A3 size recording paper is set on the paper feed tray 52 over the first tray 52 'and the second tray 52 "by laying down the central fence 78, the above-described ascending tray operation and cam operation are performed with the first tray 52'. Are performed simultaneously on the second tray 52 ". Thereby, the conveyance belt 5 at the time of sheet feeding is
The contact area of No. 3 is widened to stabilize sheet feeding and conveyance.

As described above, at the time of normal image formation, the recording paper, for example, the transfer paper fixed by the fixing device 38 in FIG.
In the case of double-sided copying in which copying is performed on both sides of the recording paper, it is necessary to reverse the recording paper after fixing and feed it to the transfer position by the photoconductor 31.

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 has a reversing path 45 as a branch path, and at the branch position, 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. The recording paper sent to the return guide path 44 is sent to the first switching claw 46a by the feed roller 47, and
5 is nipped by the reversing roller 48 and sent, and when the reversing sensor 125 detects the trailing end of the recording paper,
The sheet is fed backward by the reverse rotation of the reversing roller 48. The recording paper that is reversely fed is guided by the second switching claw 46b toward the feed roller 49 of the return guide path 44, and is discharged onto the paper feed tray 52.

When the first tray 52 'and the second tray 52 "are used at the same time as in the case of A3 copying, the tray 82 is rotated in reverse by the reverse rotation of the tray motor 122 after the sheet feeding operation for the front side copy. (The lowering amount (moving amount) is stored by an encoder (not shown).) After the front side copied recording paper 77 is inserted into the paper feed tray 52, the raising tray 82 is returned to the original position, and the back side copy is fed. After the operation is performed and the back side is copied, the recording paper 77 is discharged from the paper discharge path.

When using either the first tray 52 'or the second tray 52 "as in the case of A4 copy, when the front copy is to be fed from the first tray 52', the tray motor 122 is previously rotated in reverse. As a result, the ascending tray 82 of the second tray 52 "is lowered by a fixed amount (the descending amount (movement amount) is stored by an encoder (not shown)), and the recording paper 77 with the front side copied is inserted into the second tray 52". Then, the ascending tray 82 is returned to the original position, and the back side copy feeding operation is performed, and after the back side copy, the recording paper 77 is discharged from the paper discharge path. ″, The tray motor 12 is fed after the front copy feeding operation.
2, the ascending tray 82 of the second tray 52 "is lowered by a fixed amount (the descending amount (moving amount) is stored by an encoder (not shown)), and the recording paper 77 on which the front surface copy has been performed is moved to the second tray 52". After the insertion, the ascending tray 82 is returned to the original position, and the feeding operation of the backside copy is performed. After the backside copy, the recording paper 77 is discharged from the paper discharge path.

A recording paper upper limit sensor 126 is provided above the second tray 52 ″. When the recording paper is full even if the raising tray 82 is to be lowered in the double-sided image forming mode,
Displays on the operation panel that duplex copying is not possible.

Instead of double-sided copy, like composite copy,
When it is desired to form a plurality of images on the same surface, the recording sheet is not guided to the reversing path 45 but can be sent directly to the sheet feed tray 52 by the first switching claw 46a.

In some cases, it is desired to manually feed recording paper in response to automatic paper feeding by the paper feed tray 52. For this purpose, a manual paper feeder 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 133. Have.

When the manual feed door is opened, the mode is switched to the manual feed mode, the first driven roller 55 is returned to the manual feed home position, and the presence of recording paper in the manual feed device 130 is detected by the manual feed sensor 134. When the manual feed clutch is not operated, the recording paper is transported onto the transport belt 53 by the rotation of the manual 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, when performing a copying process, a paper bank device 4 that can store a large number of storage units, 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. The casing of the copying body 3 is provided with a paper feed path 136 that is opened at the bottom surface and guides the recording paper fed from the paper bank device 4. The paper feed path 136 is formed so that the recording paper can be fed to a home position, for example, a nip position between the first driven roller 55 and the lower pressing roller 74 at a manual feed home position. In the paper feed path 136, the branch path 1
37, and the recording paper is supplied to the first tray 5 of the paper feed tray 52.
2 'is formed so as to be able to be fed, and a switching claw 138 is provided at a branch position to the branch path 137 to enable switching of the recording paper feed path. A paper bank paper feed sensor 139 that detects that the recording paper from the paper bank device 4 has been fed to the paper feed path 136 is provided. The paper bank is abbreviated as PB as needed.

The paper bank device 4 has a maximum loading capacity of 250.
A three-stage tray including a first PB tray 201, a second PB tray 202, and a third PB tray 203, and a fourth PB tray 204 having a maximum loading capacity of 2,000 sheets are provided. Paper feed from each of the PB trays 201 to 204 is performed by one paper feed / conveyance device 205.

As shown in FIGS. 2 and 17, the sheet feeding and conveying device 205 has endless conveying means, for example, one endless belt 218. 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, a guide rod 207 is provided substantially vertically on the front plate 205 and the back plate 206 of the paper bank device 4, respectively.
The sheet feeding unit 220 is vertically slid and guided by 7. The paper feeding unit 220 includes a paper feeding unit front side plate 222 to which a bearing 221 slidably mounted on the guide rod 207 is fixed.
And a sheet feeding unit rear side plate 223. A driven roller 214, a pickup roller 215, and an auxiliary turning roller 217 are arranged so that both ends are supported by the sheet feeding unit front plate 222 and the sheet feeding unit back plate 223, respectively.

A pickup auxiliary roller 219 is disposed so as to oppose a conveying belt, that is, a PB endless belt 218, against the driven roller 214, and is rotatably supported by the sheet feeding unit front side plate 222 and the sheet feeding unit back side plate 223. The pickup auxiliary roller 219 serves to prevent the recording paper from peeling off the PB belt 218 when changing the transport direction.

Both ends of a shaft 215a rotatably supporting the pickup roller 215 are moved in a substantially horizontal direction by a long hole 224 formed in the front plate 222 of the paper feeding unit and a long hole 225 formed in the rear plate 223 of the paper feeding unit. Supported as possible. 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 is fixed to a common drive shaft 231 driven by a motor 230, and the drive shaft 231 is rotatably supported by the paper supply unit front plate 222 and the paper supply unit back plate 223. The driven pulleys 229 are rotatably supported by shafts individually attached to the sheet feeding unit front plate 222 and the sheet feeding unit back plate 223, respectively. The pickup roller 215 is driven by the forward / reverse rotation of the motor 230 so that the elongated hole 224 is formed.
225 is reciprocated. Pickup roller 2
The home position feeler 23 is provided on the 15 shaft 215a.
2 and a bracket 234 for mounting an upper end detection sensor 233 for detecting the upper end of the recording paper. When the home position feeler 232 operates the home position sensor 235 attached to the sheet feeding unit rear side plate 223, it is detected that the pickup roller 215 is at the home position. The upper end detection sensor 233 is PB
It detects that the sheet feeding surface of the belt 218 has reached a height of 5 mm from the upper end of the recording sheet, and starts the sheet feeding operation from this position.

An elevating device 250 for moving 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 and the back plate 206 and the front plate 205, and is rotated by the motor 251. A drive shaft 252 to be driven, two drive pulleys 253 fixed to the drive shaft 252, a driven pulley 253 rotatably supported by the rear plate 206 and the front plate 205, respectively, a drive pulley 252 and a driven pulley 253 and 2
And two timing belts 254. The timing belt 254 is fixed to the sheet feeding unit front side plate 222 and the sheet feeding unit back side plate 223, respectively. When the timing belt 254 moves by the forward / reverse rotation of the motor 251, the sheet feeding unit 220, that is, the sheet feeding unit front side plate 222
Then, the sheet feeding unit rear side plate 223 is moved up and down.

Brackets 237 are fixed to a front shaft 236a rotatably supported by the front plate 222 of the paper feeding unit and a rear shaft 236b rotatably supported by the rear plate 223 of the paper feeding unit. 237 support both ends of a pair of belt speed change rollers 216 (216a, 216b). That is, the first belt speed change roller 216a
And the second belt speed change roller 216 b
And the relative position with respect to the PB belt 218 running between the two belt speed change rollers 216a and 216b is displaced by the rotation of the shaft 236 (236a, 236b).
The shaft 236 (the front shaft 236a and the rear shaft 236b) is the rear shaft 2
36b is rotationally driven by a motor 238 connected thereto. A feeler 239 is fixed to the rear shaft 236b, and the feeler 239 activates a sensor 240 fixed to the rear plate 223 of the sheet feeding unit, whereby the belt speed change roller 2 is moved.
Sixteen home positions are detected. The belt transmission roller 216 rotates a shaft 236 to move a part of the PB belt 218 before the paper feeding operation to the first belt transmission roller 216.
a and the second belt speed change roller 216b, the shaft 236 is rotated in the opposite direction during the sheet feeding operation to return the wound PB belt 218, and the PB belt is returned to the original position. The feeding speed of the belt 218 is controlled.

The transport driving of the PB belt 218 is performed by the rear side plate 2.
06, a gear 242 driven by a motor 241 attached to the driving roller 211,
The driving is performed by rotating the driving roller 211 with a transmission having a gear 244 fixed to the shaft 243 of the motor.

In order to adsorb and convey 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 KVp, 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. , 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 to keep the tension constant. To be done. 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 P
Open / close sensors 261, 262, 263, and 264 for each of the B tray 201 to the fourth PB tray 204 are provided, and open / close 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 load capacity of 250 sheets are used to determine the position of the recording paper to be loaded (to be described with respect to the first PB tray 201). It has a side fence 265 and 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 convenient access.

In FIG. 21, for example, the maximum load capacity 2000
The fourth PB tray 204 as a large tray of sheets can be provided with a side fence 268, an end fence 269, and a handle 267, similarly to the first PB tray 201 of 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, an L-shaped side fence 268
Is shaped so as not to interfere with paper feeding.

The charge density pattern is formed on the PB belt 53 of the copying main body 3 by the charging roller 76, and the recording paper is attracted and conveyed. In the paper bank device 4, the PB belt 218 acts as the charging roller.
A charge density pattern is formed by 17 and the recording paper is conveyed by suction. For this reason, the transport belt 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. At least one of the rollers supporting the conveyor belts 53, 218, for example, the rollers 56, 215, is grounded and arranged so as to contact the back surface of the belt.

As shown in FIG. 22, for example, as shown in FIG. 22, an uneven electric field, for example, an alternating electric field (AHz) is applied to the charging rollers 76 and 217 (only the charging roller 76 is shown) from the high voltage power supply 131 so as to face the ground roller 56. Is done.
The transport belt 53 is moved by the driving roller 54 in the direction of the arrow at a constant speed Umm / s, 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 transport belt 53 from the high voltage power supply 131 via the charging roller 76 before the recording paper comes into contact with the surface. Thereby, the transport belt 53
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. In the semiconductor layer on the rear surface of the transport belt 53, charges of opposite polarity are induced by the charge density formed on the surface of the transport belt.

When the charge density pattern as shown in FIG. 22 is formed, unequal charges 132 are formed near the surface of the conveyor belt 53 as shown in FIG. The force acting on the unit volume of the body can also be obtained by using Maxwell's stress tensor. The recording paper 77 is electrostatically attracted to the conveyance belt 53 by a force Fx in a direction perpendicular to the surface of the recording paper 77, that is, the sheet, and is held without being shifted.
And are fed and conveyed.

The direction orthogonal to the sheet surface is x, the conveying direction is y,
When the direction perpendicular to the conveying direction in the sheet plane is z, the component force in each of the x, y, and z directions acting on the unit volume of the dielectric is F.
_Assuming that _X , F _y , and F _Z , the following is obtained.

Maxwell's stress tensor

[0109]

(Equation 1)

Force acting on unit volume

[0111]

(Equation 2)

This adsorption principle is different from the 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 charge density pattern is shown as an example in the form of a stripe, it may be a checkered pattern, and an appropriate pattern can be used.

As shown in FIG. 24, plain paper of A3 size is fed to the conveyor belt, and when the contact length becomes 100 mm, a spring scale 133 is attached to the rear end of the paper to increase the suction force. As a result, a result as shown in FIG. 25 was obtained. The adsorption area at this time is 300 cm ²
It is.

FIG. 25 shows the result of measuring the attraction force by changing the applied frequency while keeping the amplitude of the AC voltage constant, for example, 4 KVp. Thus, in the present invention, when the period of the stripe shape was set to 20 mm or less, particularly 10 mm or less, a sufficient suction force was obtained. Further, as shown in FIG. 26, when the applied frequency was kept constant, for example, 26 Hz, and the applied voltage was changed to measure the attraction force, a good attraction force was obtained at 2 KVp or more. 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 a 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 which outputs a non-uniform alternating voltage.

In FIG. 22, an unequal electric field is generated in the vicinity of the belt surface by applying an AC voltage to the charging roller 76, while as shown in FIG.
Is connected to a DC high-voltage power supply 131 'via a switch 131'a, and by repeatedly turning on and off the switch 131'a, a stripe-shaped charge density pattern can be similarly formed.

Further, as shown in FIGS. 28 and 29, the concave portions 76'a are formed at predetermined intervals in the axial direction and the circumferential direction, and when expanded, the concave portions and the convex portions form a checkerboard pattern. The charging roller 76 ′ alternately arranged in the direction and the circumferential direction is arranged to face the ground roller 56,
By applying a high voltage to DC power supply 6 'by DC power supply 131', a checkered charge density pattern can be formed near the surface of transport belt 53 (the same applies to PB belt 218).

In FIG. 27, a horizontal stripe charge density pattern is formed. On the other hand, as shown in FIGS. 30 and 31, a charging roller 76 having annular projections 76 ″ a formed at predetermined intervals in the axial direction is used. ”Is disposed opposite the ground roller 56,
By applying a high voltage to the charging roller 76 ″ by a DC power supply 131 ′, a vertical stripe-shaped charge density pattern can be formed. Assuming that the interval is c ', the width of the annular projection 76 "a of the charging roller is a, the interval between the adjacent annular projections 76" a is b, and b> a, and c {c'} ( a + b) / 2.

In contrast to the charging roller 76 ″ of FIG. 30, FIG.
As shown in FIG. 2, a comb-shaped electrode plate 376 can be used. The width of the protruding teeth 376a of the comb tooth is a, and the protruding teeth 3
A vertical stripe-shaped charge density pattern can be formed on the transport belt 53 by setting the interval of 76a to b and configuring the same relationship as in the case of the charging roller 76 ″ in FIG.
The tip of the protruding tooth portion 376a is in contact with the transport belt 53.

As described above, the recording paper 77 can be attracted by generating an uneven electric field near the belt surface.

The voltage applied to the charging roller may be an alternating voltage having a rectangular shape, a triangular shape, a saw shape, or the like instead of the above-described AC voltage, or a voltage in which a DC component is superimposed on the AC voltage and biased to either positive or negative. Can also be applied.

FIG. 22 shows the configuration of a belt used in the sheet feeding / conveying apparatus of the present invention. The transport belt 53 is a two-layer type and the surface layer is a dielectric film (polyester resin 20).
μm, volume resistance 10 ¹⁶ Ωcm), the lower layer being a semiconductor layer (carbon dispersed in polyester resin 80 μm, volume resistance 10
^It is configured as an endless belt of ⁸ Ωcm) and is rotatably supported by a driving roller and a plurality of supporting rollers. ± 2K from the high voltage power supply 131
V, 24 Hz alternating voltage is applied. The transport belt 53 is driven at a constant speed 1 in the direction of the arrow by a driving roller.
It moves at a speed of 20 mm / s, and the paper feed position of the recording paper is downstream of the contact position of the electrode of the charging roller 76 with respect to the moving direction of the transport belt 53. 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 reason why the volume resistance of the back surface of the conveyor belt 53 is set to 10 ⁸ Ωcm is that the transfer means is provided on the back surface and the transfer is performed by one transfer.
This was because it had to be not less than 0 ⁷ Ωcm. In addition, the above-described resistance was selected because the adsorption force was increased when there was a difference in resistance from the surface layer. However, there is no functional problem if the volume resistance of the back surface is practically in the range of 10 ⁷ Ωcm to 10 ¹¹ Ωcm.

In FIG. 23, the PB belt 218 used in the paper feeder of the paper bank device 4 of the present invention is of a two-layer type. The surface layer is a dielectric film (PET 50 μm) and the lower layer is an aluminum endless belt. It is rotatably supported by a roller and a plurality of support rollers. The volume resistance of this dielectric was 10 ¹⁶ Ωcm.
The charging roller 217 has a voltage of ± 2 KV, 26
Hz alternating voltage is applied. In addition, PB belt 2
Reference numeral 18 denotes a constant speed of 130 mm /
The recording paper feed position 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 period of 5 mm.

The PB belt 218 in the paper bank device 4 includes the first PB tray 201 to the fourth PB tray 204.
The recording paper is sucked and fed. For this purpose, the lifting device 2
50 is operated, and the paper feeding unit 220 moves up and down in front of the first PB tray 201 to the third PB tray 203,
It stops at the paper feed home position of the PB tray 201 to the third PB tray 203. In FIG. 17, before the recording paper is fed to the surface of the fourth PB tray 204, a charge density pattern is formed at a cycle of 5 mm on the surface of the PB belt.

The PB belt 218 in the paper banking device 4 includes the first PB tray 201 to the fourth PB tray 204.
The recording paper is sucked and fed. For this purpose, the lifting device 2
50 is operated, and the paper feeding unit 220 moves up and down in front of the first PB tray 201 to the third PB tray 203,
It stops at the paper feed home position of the PB tray 201 to the third PB tray 203. In FIG. 17, a fourth PB tray 204 includes a first PB tray 201 to a third PB tray 2.
3, the sheet feeding unit 220 can directly move on the recording paper in the fourth PB tray, but is arranged in the same row as the first PB tray 201 to the third PB tray 203, and the fourth PB tray It may be configured to move up and down in front of 204.

The paper feed home position is set at a position above the upper end of the recording paper by a predetermined 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, PB
The belt 218 is located 5 mm above the upper end 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 means, for example, a pair of belt speed change rollers 216 (2)
16a and 216b) are used.

In FIG. 33, the belt speed change roller 216
a and 216b are each a roller having a diameter of 8 mm as an example,
The distance between the centers of the belt speed change rollers 216a and 216b is set to 1
The PB belt 218 is wound around the belt transmission rollers 216a and 216b by the motor 238, and the PB belt 218 is wound around the belt transmission rollers 216a and 216b. Or In FIG. 33, the center O
_The angle θ from the release position where the PB belt simply contacts the belt speed change rollers 216a and 216b indicated by solid lines around _1.
Just swirled.

When the PB belt 218 itself is not moving, the belt speed change rollers 216a and 216b
The amount of movement L of the PB belt caused by turning by (rad) is as follows: L = 2γθ + 12 (1−cos θ) where γ 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 a speed of 150 mm / sec, the contact area of the PB belt 218 with the recording paper moves at a speed of 280 mm / sec. In order to stop the PB belt 218 in the contact area with the recording paper, it is necessary to cancel this speed. Therefore, if the displacement speed V is set to 280 mm / sec, the angular velocity ω,
That is, the driving speed of the motor 238 that rotates the shaft 236 is obtained. That is, in the case of the first PB tray 201 to the third PB tray 203, the feed unit 220 is driven at 150 mm / sec from the feed home position shown in FIG. Descended,
At this time, the belt speed change roller 216 moves in a direction in which the PB belt 218 is wound around the belt speed change rollers 216a and 216b as shown in FIG. 216
a and 216b are turned. The portion of the PB belt 218 that contacts the recording paper is almost stationary, and the recording paper is
Electrostatic adsorption is performed according to the charge density pattern of the B belt 218. Thereafter, the sheet feeding unit 220 is returned to the sheet feeding home position shown in FIG.

In the case of the fourth PB tray 204, the recording paper 77 is supplied by suction in the same manner. The fourth PB tray 20
In the case of No. 4, since the leading end of the recording paper 77 is sucked while being separated from the contact area of the PB belt 218, if the recording paper is transported as it is, the recording paper will be sequentially separated from the PB belt from the leading end. . Then, the PB belt 218 is moved from the sheet feeding home position shown in FIG.
After lowering to the position shown in (B) and contacting and sucking the recording paper 77 in a stationary state, while the paper feeding unit 220 is raised and returned to the paper feeding home position as shown in FIG. 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.

For example, assuming that 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 linear velocity in the direction 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 is moved 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 is swung so that the belt speed change roller 216 is returned. Therefore, the above-mentioned displacement speed V is set to 580 mm.
/ Sec to control the speed of the motor 238.

PB in the paper feed process for the next recording paper
In preparation for deceleration of the recording paper contact area of the belt 218, the belt speed change roller 216 is provided in a range between adjacent recording papers to be conveyed.
Is swiveled.

As shown in FIGS. 36 and 37, two fixed rollers 216 'and one transmission roller disposed between them are provided for the structure in which the two rollers are pivoted as in the examples shown in FIGS. FIG. 36 shows an example used for the first PB tray 210 to the third PB tray 203 as shown in FIG. 34, and FIG. 37 shows an example used for the fourth PB tray 204 as shown in FIG. In Fig. 36, the speed change roller 216 "moves to the paper feeding home position shown by the solid line, and moves to the left in the figure while descending from that position to the position in contact with the recording paper to move the PB belt. The speed of the recording paper contact area is reduced or stopped, and the displacement roller 21 is returned to the paper feeding home position again.
6 "is displaced to the leftmost position in the figure.

FIG. 37 is different from the example shown in FIG. 36 in that the recording paper contact area of the PB belt is moved backward in the opposite direction.

The time required for the paper supply unit 220 to descend from the paper supply home position by 5 mm at 150 mm / sec and come into contact with the recording paper is 5 (mm) / 150 (mm / sec) = 0.033 sec. , The PB belt 218 is driven at a constant speed of 130 mm / sec, and the lowering speed of the paper feeding unit 220 is 150 mm.
280mm / sec to cancel the downward displacement due to
To displace the displacement roller 216 "in the minus direction. This displacement is performed for 0.033 seconds, so that the displacement amount is 280 (mm / sec) .times.0.033 (sec) = 9.3 (mm). The roller 216 "may be moved at a constant speed of 9.3 (mm) /2=4.7 (mm) at a speed of 280 (mm / sec) / 2 = 140 (mm / sec) to the left in the drawing.

In FIG. 37, since the leading end of the recording paper is further fed back to the position of the driven roller 214,
6 "moves at a constant speed of 290 mm / sec and a displacement of 9.7 mm to the left in the figure.

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

[0142]

According to the present invention, the charging device always forms a uniform charge pattern or a non-uniform electric field pattern on the conveying means by the charging device, so that the attraction force of the conveying means on the recording medium is uniform. As a result, the recording medium can be fed from the storage means in a constant and reliable state, and the reliability of feeding and transportability has been improved.

According to the present invention, the occurrence of skew during the feeding and conveyance of the recording medium can be prevented without the provision of the registration means, the double feeding does not occur, and the conveyance reliability without the occurrence of jams. Of the feeding / conveying device having a very high value.

According to the present invention, the frictional force exerted on the recording medium by the conveying means can be reduced to zero or reduced as much as possible, so that the generation of paper dust can be suppressed. And a highly reliable feeding / conveying apparatus can be obtained.

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

According to the present invention, the transfer speed of the entire endless conveyance from the feeding from the storage means to the image forming section is not changed, and therefore the copy production speed per unit time is always kept constant from the storage means. As a result, a feeding device capable of performing reliable feeding was obtained.

When a belt on which an uneven electric field is formed is used as the endless transport means, it is possible to stably and surely adsorb the recording medium to the transport means, and it is not necessary to provide a special resist device. Was.

[Brief description of the drawings]

FIG. 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 explanatory view of a scanner device.

FIG. 4 is an explanatory plan view of the writing optical device.

FIG. 5 is a plan view of the conveyance unit transmission.

FIG. 6 is a perspective view of a conveyance unit transmission.

FIG. 7 is a front sectional view of a part of the storage means.

FIG. 8 is a front sectional view showing a state in which the partition means of FIG. 7 is tilted.

FIG. 9 is a perspective view of the partitioning means.

FIG. 10 is a schematic front sectional view showing a housing means and a conveying means pressing device as a suction operation means.

FIG. 11 is a view corresponding to FIG. 10 and illustrating an operation state of the conveying unit pressing device.

FIG. 12 is a perspective view showing a drive system of a conveying unit pressing device.

FIG. 13 is a front view of the cam.

FIG. 14 is an explanatory diagram of a stopper of a drive system of the conveying unit pressing device.

FIG. 15 is an overall perspective view of a housing unit.

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 sheet feeding unit.

FIG. 19 is a plan view of a sheet feeding unit.

FIG. 20 is a perspective view of an example of a storage unit.

FIG. 21 is a perspective view of another example of the storage means.

FIG. 22 is an explanatory perspective view of formation of an uneven electric field on a conveying means.

FIG. 23 is an explanatory front view of formation of an uneven electric field.

FIG. 24 is an explanatory diagram of a test method of a suction force by an uneven electric field.

FIG. 25 is a diagram showing a relationship between a pitch of an uneven electric field and a tensile force indicating an attractive force.

FIG. 26 is a diagram showing a relationship between an applied voltage of an uneven electric field and a tensile force.

FIG. 27 is a perspective view of another example of forming an uneven electric field.

FIG. 28 is a perspective view of still another example of forming an uneven electric field.

FIG. 29 is a view showing a charging roller, wherein A is a perspective view and B is a cross-sectional view.

FIG. 30 is a perspective view of still another example of forming an uneven electric field.

FIG. 31 is a plan view of FIG. 30.

FIG. 32 is a perspective view of a charging plate replacing the charging roller.

FIG. 33 is an explanatory diagram of another example of the conveyance unit transmission.

FIG. 34 is an operation diagram sequentially showing operation states of A, B, and C of the conveyance unit transmission shown in FIG. 33;

FIG. 35 is a view corresponding to FIG. 34 of an example in which the relative position between the transporting means and the storage means is different from that in FIG. 34;

FIG. 36 is an explanatory diagram of another example of the conveyance unit transmission.

FIG. 37 is a diagram corresponding to FIG. 36, in which the shift step is modified from FIG. 36;

[Explanation of symbols]

 52 accommodation means 53 endless conveyance means 55 driven roller 63 additional movement device 76 charging means 77 recording paper 201 accommodation means 202 accommodation means 203 accommodation means 204 accommodation means 218 endless conveyance means 216 additional movement means 217 charging means

Continued on the front page (72) Inventor Tetsuya Fujioka 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Fumio Kurumi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company (58) Field surveyed (Int. Cl. ⁷ , DB name) B65H 5/00 B65H 1/00-3/68

Claims (3)

(57) [Claims] 1. A feeding device 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 conveying unit for feeding the recording medium to a predetermined position from the storage unit. The means has a means for additionally moving only a part in at least one of the horizontal direction and the vertical direction, and has a partly variable transport speed, and forms an uneven electric field pattern on the transport means. A feeding device for an image forming apparatus, wherein a charging unit is provided, and a non-uniform electric field pattern having a predetermined shape is formed on the conveying unit. 2. The image according to claim 1, wherein the charging unit is arranged at a position where a conveying unit upstream of the storage unit moves at a constant speed in a feeding direction of the conveying unit. Forming device feeding device. 3. The charging device according to claim 1, wherein the charging unit is disposed at a position where a relative moving speed of the charging unit changes in a direction upstream of the storage unit in a feeding direction of the conveying unit. 2. The feeding device of the image forming apparatus according to claim 1, wherein an applied frequency to the image forming apparatus is variable.