JP3019511B2 - Paper guide device for transfer material carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine having a transfer material carrier such as a transfer drum, and more particularly, to a sheet for transferring a toner image onto such a transfer material carrier. To a paper guide device.

[0002]

2. Description of the Related Art For example, one type of electrophotographic copying machine that performs multiple transfer uses a transfer drum that electrostatically attracts a copy sheet on which a toner image is to be transferred and conveys it to a transfer position. The operation of the transfer drum will be briefly described with reference to FIG.

In FIG. 11, a main charger, an exposing device, a toner developing device for four colors of black, magenta, cyan, and yellow, a cleaning device, and the like, which are not shown, are arranged around the photosensitive drum 1. The electrostatic latent images of the applied images are sequentially formed, and the toner images developed with the toner of the corresponding color are sequentially transferred onto the copy paper P adsorbed on the peripheral surface of the transfer drum 2. The transfer drum 2 has 150 drums
μm thin PET (polyethylene terephthalate)
Or formed by winding an insulating film made of PVdF (polyvinylidene fluoride) or the like into a drum shape,
Around the inside and inside thereof, a suction opposing roll 3, a suction corotron 4, a transfer corotron 5, a charge removing corotron 6, a peeling corotron 7, a cleaning device 8, a transfer drum charge removing corotron 9, a registration roll 10, and the like are arranged as shown. I have. The suction opposing roll 3 is made of a conductive material, is grounded, and is configured to be in contact with the transfer drum 2. Further, the cleaning device 8 is formed of a fur brush or the like, and is configured so as to be in contact with and separated from the transfer drum 2. The attraction corotron 4 charges the transfer paper P sent from the registration roll 10 at a timing to the transfer drum 2 by charging a charge having a polarity opposite to the polarity of the toner transferred onto the inner surface of the transfer drum 2. At this time, the suction opposing roll 3 is brought into contact with the transfer drum 2 to hold down the paper P and to inject charges having a polarity opposite to the charge charged by the suction corotron 4 onto the surface of the paper P. At the transfer position from the photosensitive drum 1, the transfer drum 2 having attracted the paper P has its inner surface further charged by a transfer corotron 5 with a charge having a polarity opposite to that of the toner, and the toner image on the surface of the photosensitive drum 1 is transferred to the transfer drum 2. Is transferred onto the sheet of paper P that is attracted to the sheet.
Then, the transfer toner image on the inner surface of the transfer drum 2 is neutralized by the neutralization corotron 6, and the toner image of the next color is similarly transferred. However, during this time, the suction opposing roll 3 and the cleaning device 8 are separated from the transfer drum 2. When the toner image of the last color is transferred, the peeling corotron 7 operates to peel off the sheet P adsorbed on the transfer drum 2 and is sent to a fixing device (not shown). In the figure, reference numeral 11 is used.
Is a discharge regulating baffle that regulates the charging area at the position of the adsorption corotron 4.

[0004]

However, when the paper P sent from the registration roll 10 to the suction position composed of the suction opposing roll 3 and the suction corotron 4 is, for example, moisture-absorbed and becomes a water-containing paper, the schematic diagram of FIG. As shown in the perspective view, the tip PS may undulate in a direction perpendicular to the traveling direction. When the paper P enters the nip between the suction opposing roll 3 and the transfer drum 2 in this undulating state, the undulated paper P deforms the thin insulating film of the transfer drum 2. After passing through the suction opposing roll 3, a non-sucking area indicated by b occurs between the suction areas indicated by a in FIG. 12, and a transfer failure of the toner image may occur in the area b. Further, for example, the paper P feed speed is faster than the peripheral speed of the transfer drum 2 and the registration roll 10
When a meandering loop of the sheet P is formed between the sheet P and the suction opposing roll 3, or when the leading end PS of the sheet P bends toward the transfer drum 2, the meandering portion of the sheet P or the leading end PS of the sheet P advances.
Strikes the thin insulating film of the transfer drum 2 and deforms it, and the sheet P is sucked in a state where the deformation remains, similarly causing uneven suction and causing transfer failure.

Conventionally, in order to prevent such a transfer failure due to the waving of a sheet, the suction opposing roll is formed into a barrel shape with an expanded middle portion, and the waving is pushed out to the periphery (Japanese Patent Laid-Open No. 15779/1990). Japanese Patent Application Laid-Open No. 63-177181 proposes that the peripheral speed of the suction opposing roll is made slower than the paper feed speed to eliminate the slack of the paper.
All were inadequate.

The present invention has been made in view of such a situation, and an object of the present invention is to improve the structure of a sheet guide device for guiding a transfer sheet to a transfer material carrier such as a transfer drum, thereby achieving a suction position. It is to remove the waving of the paper which causes transfer failure before or at the position, and send the paper to a transfer material carrier such as a transfer drum to prevent the transfer failure caused by the wavy.

[0007]

According to the first aspect of the present invention, there is provided a sheet guide device for a transfer material carrier, which comprises a thin insulating sheet, and electrostatically transfers a toner image onto a sheet. In order to guide the paper to the suction position of the transfer material carrier that sucks and conveys the paper, plate-shaped guide members are provided on both sides of the paper transport path near the suction position, and the suction opposition holds the paper at the suction position of the transfer material carrier. A roll is provided, and the paper guide path reaching the nip position between the suction opposing roll and the transfer material carrier by the guide member, has a shape in which it once meanders in a direction away from the transfer material carrier and then reaches the nip position. It is characterized by having become. The second paper guide device for the transfer material carrier of the present invention is a thin sheet of an insulating sheet, which electrostatically attracts the paper for electrostatically transferring the toner image to the attracting position of the transfer material carrier. In order to guide the paper, plate-like guide members are provided on both sides of the paper transport path near the suction position, and suction opposing rolls that press the paper at the suction position of the transfer material carrier are provided, and provided on both sides of the paper transport path. At least one of the plate-like guide members is made of an elastic film, and a slit-like gap elastically closely adhered is formed between the two guide members, and the sheet is guided to the suction position through the gap. It is characterized by the following.

The third paper guide device for a transfer material carrier of the present invention is a device for transferring a toner image, which is formed of a thin insulating sheet, onto which a toner image is to be electrostatically transferred by electrostatic attraction. In order to guide the paper to the suction position, plate-like guide members are provided on both sides of the paper conveyance path near the suction position, and a suction opposing roll for pressing the paper at the suction position of the transfer material support is provided. The plate-like guide member provided on the side closer to is made of an elastic film, and the paper guide direction thereof is set to a direction away from the suction position with respect to the transfer material carrier, and the elastic film Is characterized in that both sides of the sheet are sent to the suction position of the transfer material carrier earlier than in the center. In this case, the elastic film may be provided only in a region corresponding to a central portion excluding both end portions of the sheet width. In that case, the front end of a region corresponding to the central portion excluding both end portions of the sheet width of the plate-shaped guide member provided on the side further away from the transfer material carrier is cut out,
In addition, it is desirable that the sheet guide direction of the area corresponding to both ends of the sheet width is set to a direction substantially toward the suction position. Further, the elastic film may be configured so that the flexural rigidity in the paper advancing direction decreases from the central portion to the peripheral portion in the paper width direction.

[0009]

In the present invention, in order to guide a sheet made of a thin insulating sheet to a suction position of a transfer material carrier for electrostatically adsorbing and conveying a sheet for electrostatically transferring a toner image,
Since the plate-shaped guide members are provided on both sides of the paper conveyance path near the suction position, even if the paper is wavy due to water content in the paper conveyance direction or a direction perpendicular to the paper conveyance direction, the paper is suctioned by the wave in the paper conveyance direction. The paper is uniformly attracted to the transfer material carrier because the paper does not hit the transfer material carrier earlier and the waving in the direction perpendicular to the paper transport direction is removed before or at the suction position. In addition, transfer defects such as transfer unevenness of the toner image do not occur.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a sheet guide device for a transfer material carrier according to an embodiment of the present invention;
In the present invention, first, according to any of the three different principles, the waving perpendicular to the traveling direction of the sheet at the suction position or at the suction position is removed, and the transfer material such as the transfer drum 2 as shown in FIG. This is to eliminate the non-adsorption area b on the carrier.

The first one is to bend the paper slightly in the traveling direction and remove the wavy existing in the direction perpendicular to the traveling direction. One example is shown in FIG. FIG. 1 is a side view of the vicinity of a suction portion of the transfer drum 2 and a registration roll 10.
A guide plate 12 for guiding a sheet, and a PE having a rear end fixed to a mounting bracket 14
An elastic guide film 13 made of a T film or the like is provided.
The paper guide shape is, as shown in FIG.
0 is first guided in the direction approaching the transfer drum 2 by the protrusion A of the guide plate 12, and then,
The elastic guide film 13 is guided by the front end B of the elastic guide film 13 in a direction away from the transfer drum 2 and is pressed by the suction opposing roll 3 to the transfer drum 2 at the nip position (suction position) C thereof. The shape is such that it once suddenly meanders in the direction away from the transfer drum 2 from the transport route when no guide is provided as shown, and then reaches the suction position C. As described above, when the paper P is suddenly meandered in the paper path from the registration roll 10 to the suction opposing roll 3, the traveling direction of the paper P is bent at the meandering position, and the wavy existing in a direction perpendicular to the meandering position is removed. On the downstream side of the adsorption position C, the sheet P is electrostatically and uniformly adsorbed to the transfer drum 2, and the toner image is transferred at the transfer position without transfer failure.

It should be noted that the abrupt meandering path as described above can also be formed by two continuous guide plates that form the meandering path in cross section. However, in that case,
The running resistance increases, which is not always preferable.

The second principle of the present invention for removing the ripples in the direction perpendicular to the traveling direction of the sheet is achieved by advancing the sheet through a slit-like gap elastically closely contacting the sheet. One example is shown in FIG. As in the case of FIG. 1, a guide plate 12 for guiding a sheet and an elastic guide film 13 made of a polyester film or the like having a rear end fixed to a mounting bracket 14 are provided between the registration roll 10 and the suction opposing roll 3. Have been. In this case, the protruding portion A of the guide plate 12 and the side surface D near the tip of the elastic guide film 13 are in elastic contact, and the paper P passes through the closely-spaced slit-shaped gap therebetween and is squeezed. Thus, the waving existing in the direction perpendicular to the traveling direction of the sheet P is removed. In addition, the case of FIG. 2 has not only this ironing but also the effect of removing the wavy by the meandering of FIG.

As a modification of FIG. 2, as shown in FIG. 3, an elastic guide film extending in a slit-like space through which a sheet passes so as to narrow the conveyance path in the advancing direction with the side surface E of the guide plate 12. 13 and between them. This makes it easy for the elastic force of the elastic guide film 13 to concentrate on the slit-shaped gap for ironing,
While the ironing effect is improved, paper dust, dust and the like are more likely to be generated. Further, as shown in FIG. 4, the arrangement of the guide plate 12 and the elastic guide film 13 with respect to the transfer drum 2 may be reversed from the arrangement of FIG. In this case, the paper P whose tip is bent toward the transfer drum 2 in the traveling direction pushes down the relatively flexible elastic guide film 13 by the hard guide plate 12, and the paper P directly hits the transfer drum 2, and The thin insulating film is deformed, or the paper P feed speed is higher than the peripheral speed of the transfer drum 2, and a paper loop is formed between the registration roll 10 and the suction opposing roll 3, and the paper loop pushes down the elastic guide film 13 to transfer the paper. By deforming the drum 2, it is possible to prevent the paper P from being unevenly attracted based on the deformation.

Next, a third aspect of the present invention is to send a wavy existing in a direction perpendicular to the paper advancing direction to the nip of the suction opposing roll 3 on both sides of the leading end of the paper in the paper feeding direction before the center. This is to remove the sheet by generating a force to relatively delay the progress of the set and open the rear end of the sheet to both sides. In particular, if the leading edge of the paper is wavy due to the water content, the vicinity of the center in the direction perpendicular to the traveling direction will be transported before and after the suction to the transfer drum, and in this state, large waving occurs near the center Then, as the paper is fed backward, both sides of the trailing edge of the sheet are moved toward the center, the waving becomes larger, and a large transfer drop occurs. However, the arrangement based on this principle is particularly effective for transfer failure due to such a cause. One specific example is shown in FIGS. FIG. 5 is a side view of the vicinity of the attracting portion of the transfer drum 2 as in FIG. 1 and the like. FIG. In this case, the elastic guide film 13 whose rear end is fixed to the mounting bracket 14 only at the central portion in the direction perpendicular to the paper P feed direction and guides the paper P in the direction retracted from the suction position C with respect to the transfer drum 2 is provided. The elastic guide film 13 is not provided on portions corresponding to both sides of the sheet P. Therefore, as shown by the solid line in FIG.
2 and the elastic guide film 13, and reaches the nip position C along the suction opposing roll 3. On the other hand, on both sides of the paper P, since there is no elastic guide film 13, FIG.
Directly reaches the nip position C as indicated by the dotted line in FIG. Therefore, since both sides of the sheet P are sent earlier than the center portion, the sheet P acts to open the rear end to both sides, and the wavy existing in the direction perpendicular to the traveling direction of the sheet P is removed. .

In FIGS. 5 and 6, instead of providing the elastic guide film 13 only at the center in the direction perpendicular to the paper P feed direction, the elastic guide film 13 is provided over the entire width of the paper P in the transverse direction. Elastic guide film 1
It is also conceivable to make 3 more flexible. One example is shown in FIG. FIG. 7 is a view similar to FIG. 6, except that a slit 15 is cut in the elastic guide film 13 in the paper advancing direction. The density of the slits 15 is coarse at the center and dense at both sides. Therefore, almost as in the case of FIG.
Since the elastic guide film 13 in the central area of the paper P is unlikely to be bent, the elastic guide film 13 detours and reaches the nip position C as shown by a solid line in FIG. On the other hand, on both sides of the sheet P, the elastic guide film 13 is more easily bent, so that the sheet reaches the nip position C more directly as shown by the dotted line in FIG. Will be sent earlier than
By acting to open the trailing end of the sheet to both sides, the wavy existing in the direction perpendicular to the traveling direction of the sheet P is removed.
This example is equivalent to the elastic guide film 13 in which the slits 15 are coarsely cut at the center and densely formed at both sides in the configuration for removing the waving in FIG. ing. The configuration of FIG. 7 is different from that of FIG.
Since the stiffness of the sheet P continuously changes toward the periphery, the arrival time of the leading end of the sheet P to the nip position C changes continuously. Similar effects can be obtained by using a film that gradually becomes thinner from the center to the periphery instead of providing the slits 15 with a density difference as the elastic guide film 13.

Another example of the third principle is shown in FIGS. 8 is a side view of the vicinity of the suction portion of the transfer drum 2 as in FIG. 1 and the like, and FIG. 9 is a view as seen from the double arrow direction in FIG. In this case, as in the case of FIG. 6, the elastic guide film 13 is provided only at the center in the direction perpendicular to the paper P feed direction, the guide plate 12 is provided over the entire width of the paper P in the transverse direction, and the elastic guide at the tip of the guide plate 12 is provided. A central portion corresponding to the film 13 is cut out, and the elastic guide film 13 is inserted into the notch, and they are arranged so as to intersect when viewed in a side view. With this arrangement, the central region of the sheet P on which the elastic guide film 13 is provided reaches the nip position C by detouring around the distal end of the elastic guide film 13 as shown by the dashed line in FIG. On the other hand, on both sides of the sheet P, the sheet is guided by the guide plate 12 and is directly guided to the nip position C as shown by a dotted line in FIG. Similarly, both sides of the sheet P are sent earlier than the center, and the sheet P acts to open the trailing edge to both sides, so that the wavy existing in the direction perpendicular to the traveling direction of the sheet P is removed. It is. In this case, the central portion of the sheet P has an effect of further removing the waving due to the S-shaped path formed while being squeezed between the elastic guide film 13 and the notch end of the guide plate 12. .

By the way, in any of FIGS. 1 to 9 described above, since the elastic guide film 13 or the guide plate 12 is disposed between the sheet P and the transfer drum 2,
The paper P traveling in a meandering direction in the paper traveling direction or the leading edge PS of the paper traveling in a curved direction abuts against the transfer drum 2, thereby preventing the thin insulating film of the transfer drum 2 from deforming and preventing the paper P from being attracted unevenly. That is, in these embodiments, the transfer failure due to the waving in the paper traveling direction is
This is prevented by a guide member disposed between the sheet P and the transfer drum 2. In a case where such a guide member is not provided, or in a case where the guide member is easily pushed down even if provided, for example, as shown in FIG. A backing member (baffle) 16 that elastically presses the film from the back side to hold the drum shape is provided to prevent the transfer drum 2 from being deformed even when the paper P collides, thereby preventing the occurrence of uneven suction of the paper P. can do.

Although the above description has been made on the premise that a transfer drum is used as a transfer material carrier that adsorbs and transports a sheet to a transfer position, the same applies to a transfer belt using an insulating sheet that is thin and easily deformed. When the paper guide device having the above configuration is used, transfer failure due to paper waving can be prevented.

Although the apparatus for guiding a sheet to a transfer material carrier according to the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments, and various other modifications are possible. .

[0021]

As described above, according to the paper guide device for the transfer material carrier of the present invention, a paper made of a thin insulating sheet for electrostatically transferring a toner image is electrostatically attracted and conveyed. In order to guide the paper to the suction position of the transfer material carrier to be transferred, plate-shaped guide members are provided on both sides of the paper conveyance path near the suction position, so that the paper is wetted in the paper conveyance direction or in a direction orthogonal thereto by water etc. Even if there is undulation, the undulation in the sheet conveyance direction prevents the sheet from hitting the transfer material carrier before the suction position, and before the undulation in the direction perpendicular to the sheet conveyance direction reaches the adsorption position or at that position. As a result, the sheet is uniformly attracted to the transfer material carrier, and transfer defects such as uneven transfer of the toner image do not occur.

[Brief description of the drawings]

FIG. 1 is a side view of the vicinity of a suction unit of a transfer drum provided with a paper guide device according to an embodiment of the present invention.

FIG. 2 is a view similar to FIG. 1 of another embodiment.

FIG. 3 is a view similar to FIG. 1 of yet another embodiment.

FIG. 4 is a view similar to FIG. 1 of yet another embodiment.

FIG. 5 is a view similar to FIG. 1 of yet another embodiment.

FIG. 6 is a view as seen from a double arrow direction in FIG. 5;

FIG. 7 is a view similar to FIG. 6 of another embodiment.

FIG. 8 is a view similar to FIG. 1 of yet another embodiment.

FIG. 9 is a view as seen from a double arrow direction in FIG. 8;

FIG. 10 is a view similar to FIG. 1 of another embodiment.

FIG. 11 is a diagram for explaining the operation of the transfer drum.

FIG. 12 is a schematic perspective view for explaining a wavy state and non-uniformity of suction of a sheet sent from a registration roll to a suction position.

[Explanation of symbols]

P: copy paper, 1: photosensitive drum, 2: transfer drum, 3 ...
Suction opposing roll, 4 ... Suction corotron, 5 ... Transfer corotron, 6 ... Electrostatic corotron, 7 ... Exfoliation corotron, 8 ...
Cleaning device, 9 ... Corotron for transfer drum static elimination,
DESCRIPTION OF SYMBOLS 10 ... Register roll, 11 ... Discharge control baffle, 12 ... Guide plate, 13 ... Elastic guide film, 14 ... Mounting fitting, 15 ... Slit, 16 ... Backing member (baffle), A ... Protrusion of guide plate, B ... Elasticity Tip of guide film, C: Nip position (suction position) of suction opposing roll, D: Side surface of elastic guide film, E: Side surface of guide plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-87883 (JP, A) JP-A-59-5252 (JP, A) JP-A-3-55570 (JP, A) 3861 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 15/00 510

Claims (6)

(57) [Claims] 1. A sheet in the vicinity of a suction position for guiding a sheet made of a thin insulating sheet to a suction position of a transfer material carrier for electrostatically sucking and conveying a sheet for electrostatically transferring a toner image. the plate-like guide member in the conveying path on both sides provided, attraction counter row for pressing the sheet to the suction position of the transfer material carrying member
The guide member is provided with a suction facing roller.
Paper guide path to the nip position between the roller and the transfer material carrier
Is meandering in the direction away from the transfer material
A paper guide device for a transfer material carrier, wherein the paper guide device has a shape reaching the nip position . 2. A toner image, comprising a thin insulating sheet,
Transfer material that electrostatically attracts and transports the paper to be transferred
In order to guide the paper to the holding position of the holding body, near the suction position
Attraction counter rows of the sheet conveying path on both sides provided with a plate-shaped guide member, pressing the sheet to the suction position of the transfer material carrying member
Are provided on both sides of the paper transport path.
At least one of the plate-like guide members is made of an elastic film.
And the elastically tight contact between the two guide members
Is formed, and the adsorption position
A sheet guide device for guiding a transfer material to a transfer material carrier, wherein the sheet guide device guides the sheet to a transfer member. 3. A toner image formed of a thin insulating sheet,
Transfer material that electrostatically attracts and transports the paper to be transferred
In order to guide the paper to the holding position of the holding body, near the suction position
Attraction counter rows of the sheet conveying path on both sides provided with a plate-shaped guide member, pressing the sheet to the suction position of the transfer material carrying member
Is provided on the side closer to the transfer material carrier.
The provided plate-like guide member is made of an elastic film,
Paper guide direction from the suction position with respect to the transfer material carrier
Set in a direction toward a distant position, and
The elastic film covers both sides of the paper at the adsorption position of the transfer material carrier.
It is characterized in that it is sent earlier than in the center
Sheet guide device to the transfer material bearing member that. 4. An elastic film according to claim 1, wherein both end portions of the sheet width are provided.
Except that it is provided only in the area corresponding to the central part
4. The paper guide device for a transfer material carrier according to claim 3, wherein: 5. A sheet guide member provided on a side farther from the transfer material carrier has a cutout at a front end corresponding to a central portion excluding both end portions of the sheet width, and the sheet width of the sheet guide member is smaller than that of the sheet width. 5. The paper guide device for a transfer material carrier according to claim 4, wherein the paper guide direction of the area corresponding to both ends is set to a direction substantially toward the suction position. 6. An elastic film according to claim 1, wherein said elastic film has a width in a sheet width direction.
The flexural rigidity in the paper advancing direction decreases from the center to the periphery.
4. The apparatus according to claim 3, wherein the apparatus is configured so as to reduce the number thereof.
A paper guide device for the transfer material carrier described in the above.