JP2815223B2 - 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, it is known that a sheet-shaped recording medium such as transfer paper fed by friction of a rubber roller is conveyed to an image forming position such as a transfer position by a photoconductor by a pair of rubber rollers or a belt. ing.

In such a conventional recording medium feeding / conveying apparatus, a rubber reverse roller for combining a friction pad with a rubber feeding roller or for reversely rotating the rubber feeding roller in order to prevent a plurality of recording media from being fed together. Or a cassette for accommodating a recording medium is provided with a corner claw. 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 increases, 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 a copying machine, the belt is charged by a charging unit, and the paper stored in a paper feed tray is supported by a belt. The paper is fed out by a paper feed roller provided coaxially with the roll and electrostatically attracted to the rear belt, or the belt is directly brought into contact with the paper and electrostatically attracted and fed, and simultaneously contacted with the photoreceptor For example, Japanese Patent Application Laid-Open Nos. 59-212856, 59-224858, 59-229585, and the like have proposed that a belt is conveyed to a transfer area to be transferred.

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. A row has occurred. When double feeding occurs, the first sheet (upper side) is electrostatically attracted to the belt and conveyed.
The second and subsequent sheets (lower side) protrude from the leading end of the sheet feeding tray, and cause a jam in the next feeding (feeding) operation.

Also, paper dust is generated due to frictional contact, paper feeding failure,
Poor image quality during image formation also occurs.

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 stretched and lowered. Status and paper loading status (loading status)
However, if the uniformity is not achieved with considerable accuracy, the contact state between the belt and the sheet becomes unstable, so that the sheet tends to be skewed.

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 accuracy.

In addition, a certain amount of friction occurs between the first sheet (upper side) and the second sheet (lower side) because the belt and the roller contact the first sheet in a rotating state. Force was generated, and double feed 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 unloading the sheet from the feeding tray is not always constant and reliable as described above. Therefore, it is necessary to provide a registration means for adjusting the position and correcting the skew of the sheet, and the structure and control are still complicated.

In addition, the paper feeding unit, the registration unit, the transfer unit, the fixing unit, and the paper discharging unit of the copying machine are connected in this order with one endless belt, and the endless belt is first attached to the copy paper held by the copy paper feeding unit. JP-A-63-139846 proposes, for example, Japanese Patent Application Laid-Open No. 63-139846 to press-contact, carry out a copy sheet from a copy sheet feeding section by frictional force, and after registration, convey the copy sheet to an image forming area. 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.

[Problems to be solved by the invention]

The present invention solves the conventional problems described above, prevents skew, double feeding, and jam without the need for a registration unit, and prevents poor cleaning and uneven wear of a cleaning unit that cleans a conveyance unit. It is an object to provide a feeding device for an image forming apparatus.

[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 on which an image is to be recorded; , The endless transport means is driven at a constant speed, and is formed at a variable speed only in the vicinity of the storage means, and a cleaning means for cleaning the endless transport means is provided at a constant speed moving portion of the endless transport means. The problem is solved by a feeding device of the image forming apparatus, wherein

[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.

The transfer means is formed with an alternating 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 and form an alternating electric field pattern of a constant shape when charging at a position where the transport means moves at a constant transport speed, and is additionally moved in addition to the constant transport speed. When the transfer means is charged at a position where the relative moving speed changes, the voltage applied to the charging device changes in frequency in accordance with the change in the relative moving speed to form a constant-shaped alternating electric field pattern. You.

Even if the relative movement speed is changed, the density of the charge pattern formed independently of the relative movement speed is constant.
That is, a constant alternating electric field pattern is formed. By forming a constant alternating electric field pattern, the attraction force to the recording medium is formed uniformly, and stable transportability is obtained.

The endless conveying means cleans the surface in contact with the recording medium by the cleaning means. At this time, the cleaning unit is arranged so as to contact the endless conveying unit at the constant speed moving unit, so that the contact unit of the cleaning unit always contacts the conveying unit under a constant moving condition. Therefore, the transporting means changes the speed at the portion where the recording medium is fed from the storage means. Even when the variable speed transporting means receives a shifting action, the cleaning means is not affected by the shifting. Therefore, there is no occurrence of defective cleaning or uneven wear.

〔Example〕

 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 of a document.
A copy body 3 having a built-in image forming unit for forming an image based on information from the scanner device; and a recording medium for recording an image, for example, a paper bang device 4 containing a large number of recording papers. The scanner device 2 is placed on the paper banking device 3, and the scanner device 2 is placed on the copy main body 3.

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, an example in which the copying body 3 is formed as a separate structure separated from the copying main body 3 may be formed 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 are scanned at half the 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 aperture 22 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.
N / 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 photoconductor 31
The pattern of the potential remaining in is erased by irradiating light with the 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.

The paper feeding device 6 has a transport device 51 and a storage means, for example, a paper feeding tray or a paper feeding cassette.

The transport device 51 has an endless transport means, for example, a transport belt 53 that circulates endlessly. The transport belt 53 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 conveying belt 53 has a predetermined nip width between the driving roller 54 and the first driven roller 55, in which the photosensitive member 31 comes into contact with the image forming apparatus, for example, at the transfer position 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 are provided inside the transport belt 53.
58, for example, two pickup rollers 58 are arranged at appropriate intervals, 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. 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. 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 driven pulley fixed to a driven shaft 66 rotatably supported by the side plate 61.
62, and the drive shaft 64 is rotationally driven by the moving motor 68. A drive belt 69 is attached to each drive pulley 65 and driven pulley 67.
The drive belt 69 is attached to the slider 60 by a fixing plate 70.
Is fixed by 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 according to the movement of the first driven roller 55,
The conveyor belt 53 is formed so as to 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.

The moving speed V mm / 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 is apparently shifted to a stopped state and can be held in a stopped state by the action of the peripheral speed v mm / s and the movement degree of movement V mm / s. 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 feeding can be performed without using a registration device 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 the section extending from 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 any apparent speed fluctuation. Therefore, while the recording paper is sent to the transfer position and the fixing position by the fixing position 38, the transport belt
The peripheral speed of 53 is unchanged. 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.

The conveyor belt 53 is cleaned by a belt cleaner 72, and then a charging roller disposed near the belt cleaner 72.
A constant charge pattern is formed on the transport belt 53 by the use of the belt. When a charge pattern is formed in the speed fluctuation region of the transport belt 53, such as when the charging roller 76 is disposed in circumscribed contact with the second driven roller, the charge is applied in accordance with the feeding speed variation of the transport belt 53. By performing control such as changing the frequency of electric charges, a constant electric charge pattern can be formed on the conveyor belt 53.

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 tilted down as shown in FIG. 8, and the space between the two tray chambers 80 and 81 is opened so that the recording paper is put into one tray chamber.

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

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 finger portion 89 is locked by the protrusion-shaped locking portion 90 formed on the frame portion 52 of the paper feed tray 52 when the lower face guide 84 is turned and raised. It does not rotate above. A claw 89a is formed on the finger portion 89, and the lower face guide 83 is held at a standing position where the lower face guide 83 is prevented from turning in the overturning direction by engaging with a hook portion 91 formed on the frame portion 52a. 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 face guide 84 and the upper face guide 83 as shown in FIG. 9, in which 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 intermediate 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 216 ° range is divided into 108 ° steps, 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 smoothly curved surfaces. Connect with.

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. Then, the rotation of the stopper 104 is prevented. Locking bar 107
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 sheet feeding solenoid 110 is connected to the locking bar 107, and the locking bar 10 is
7 is rotated by the round of the support shaft 108 against the force of the spring 109, and the lock on the step portion 105 or 106 is released.

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 is locked to 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 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
Immediately after the downward movement of the tray 58, the lifting tray 82 is formed and controlled so that the contact pressure between the recording paper 77 and the conveyor belt 53 rises until the contact pressure reaches a predetermined value and then stops. 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.
, A lifting tray 82 is separately 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 121 has a driving half 121a connected to the tray motor 122 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 and contacts the outer peripheral surface of the stopper 104. At this time, the stopper 104
Has only made 1/5 rotation (72 °), so that it contacts the outer peripheral surface between the first step 105 and the second step 106. When the stopper 104 rotates exactly 120 °, the claw portion of the locking bar 107 is stopped by being locked by the second step portion 106 of the stopper 104.

At this time, the cam 99 is stopped because the surface B is 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. 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 section 44 for guiding recording paper to the paper feed tray 52 is provided as a branch path that can be switched to the paper discharge path 42 by the claw 41.

The return guide section 44 includes a reversing path 45 as a branch path, and can switch between a path to the sheet feeding tray 52 and a path to the reversing path 45 directly at the branch position 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 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 tray is inserted at 52 ", the raising 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. Second
In the case of starting from the tray 52 ", after the feeding operation of the front side copy, 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 recording paper 77 with the front side copied is inserted into the second tray 52 ″.
82 is returned to the original position to perform the back side copy feeding operation. After the back side 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 ascending tray 82 is to be lowered in the double-sided image forming mode, 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.
Paper feed tray 52 directly 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 2 and the copier main body 3, and can normally perform the function of the copier. A large number of storage means,
For example, a paper bank device 4 that can store 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 136 that is opened at the bottom of the casing of the copying body 3 and guides the recording paper fed from the paper bank device 4.
Is 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. Switching of the paper feeding path can be enabled. Paper feed path 13
6 is provided with a paper bank paper feed sensor 139 for detecting that the recording paper has been 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 feed / conveyance device 205.

The sheet feeding / conveying device 205 has endless conveying means, for example, one endless belt 218 as shown in FIGS. Endless belt 218 is a fixed position drive roller 211
, A tension roller 212 whose position can be moved, a turning roller 213 having a fixed position, a driven roller 214, a pickup roller 215, a pair of belt speed change rollers 216, and an auxiliary turning 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 rotor 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 the PB belt 218 when changing 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 236 (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 paper 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.
, 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 the small trays having a maximum stacking amount of 250 are side fences 265 for determining the position of the recording paper to be loaded (described for 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 PB belt 53 in the copying main body 3 forms a charge density pattern by a charging roller 76 and sucks and conveys the recording paper. In the paper bank device 4, the PB belt 218 forms a charge density pattern by an auxiliary turning roller 217 acting as a charging roller. Then, the recording paper is conveyed by suction. Conveyor belt 53
For this reason, the PB belt 218 is formed as an endless belt 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.

For example, as shown in FIG. 22, a high voltage power supply 131
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 perpendicular 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 acting on the unit volume of the dielectric are F. _{Assuming x} , F _y , and F _z ,

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 results of measuring the attraction force by changing the applied frequency while keeping the amplitude of the AC voltage constant, for example, 4 KV _pp . 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 attraction force was obtained. In addition, as shown in FIG.
For example, good adhesion was obtained at 2 KV _pp or more as a result of measuring the adhesion by changing the applied voltage to 26 Hz. 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 and the surface layer is a derivative film (polyester resin 20 μm, volume resistance 10
¹⁶ Ωcm), and the lower layer is constituted as an endless belt having a semiconductor layer (carbon dispersed in a polyester resin of 80 μm, volume resistance of 10 ⁸ Ωcm), and is rotatably supported by a driving roller and a plurality of supporting rollers. The charging roller 76 includes
An alternating voltage of ± 2 KV and 24 Hz is applied from the high voltage power supply 131. 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 reason for the backside of the volume resistivity of the transfer belt 53 and 10 ⁸ [Omega] cm is, in order to transfer provided transfer means on the back, 10 ⁷
This was because it had to be Ωcm or more. 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 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 for the paper feeder of the paper bank device 4 of the present invention is a two-layer type, in which the surface layer is a dielectric film (PET 50 μm), the lower layer is an aluminum endless belt, and the driving roller and It is rotatably supported by a plurality of support rollers. The volume resistance of this dielectric was 10 ¹⁶ Ωcm. The charging roller 217 has
An alternating voltage of ± 2 KV, 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. 17, the fourth PB tray 204
Before the recording paper is fed on the surface, 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 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. 17, 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.

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

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 the belt shift rollers 216a and 216b being swung by θ (rad) is: 1 = 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, when the recording paper is transported as it is, the recording paper is sequentially separated from the PB belt from the leading end. Will be lost. Therefore
The PB belt 218 descends from the paper feeding home position shown in FIG. 29 (A) to the position shown in FIG. 29 (B), comes into contact with the recording paper 77 in a stationary state, sucks it, and then moves to FIG. As shown in the drawing, while the paper feeding unit 220 is raised and returned to the paper feeding home position, the recording paper is retracted by a predetermined amount to a position where the leading end of the recording paper contacts the driven roller 214.

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 wrapping of the belt speed change roller 216 is released so as to return. Therefore, the speed of the motor 238 is controlled by setting the above-mentioned displacement speed V to 580 mm / sec.

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 due to the descending speed of 150mm / sec of the unit 220. Since this displacement is performed for 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.

〔effect〕

According to the present invention, the cleaning means always comes into contact with the conveying means subjected to the shifting action under a constant moving condition, so that the cleaning property is stabilized and uneven wear is prevented.

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.

When a belt on which an alternating 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 registration device.

[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. FIG. 16 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. 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. FIG. 31 is a view corresponding to FIG. 52: accommodation means, 53: endless conveyance means 55: driven roller 72: cleaner (cleaning means) 76: charging means, 77: recording paper

──────────────────────────────────────────────────続 き Continuing on the front page (72) Fumio Kurusumi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Tetsuya Fujioka 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) B65H 1/00-3/68

Claims (1)

(57) [Claims] 1. A sheet feeding device for an image forming apparatus, comprising: a storage means for storing a recording medium for recording an image; and an endless transport means for sucking and transporting the recording medium from the storage means to a predetermined position. The shape conveying means is driven at a constant speed, and is formed so as to have a variable moving speed only in the vicinity of the accommodation means,
A sheet feeding device for an image forming apparatus, wherein a cleaning means for cleaning the endless transport means is provided at a constant speed moving portion of the endless transport means.