JPH10161387A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To alter printing time according to the size of a transfer sheet. SOLUTION: In multitransfer on a transfer sheet, the length of a transfer- sheet carrying path is switched by controlling a push roller 39 by means of a carrying-path control part so that a distance required for carrying is altered according to the size of the transfer sheet, thereby pushing in a transfer belt 31, stretched by roller members, by means of the push roller 39. The distance required for carrying the transfer sheet is shortened in such a manner that in the passing area of the root of the bypass part 40 of the transfer belt pushed in by the push roller 39, the transfer sheet gripped by a gripper situated at the rear is passed to a gripper attached to the transfer belt and situated at the front.

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 for forming an image by an electrophotographic recording method, and more particularly to a multi-transfer type multi-color image forming apparatus.

[0002]

2. Description of the Related Art In recent years, the formation of color images by the electrophotographic recording system has become widespread, and the use thereof has been expanded in presentations and the like because images of various color tones can be recorded. Further, there is an increasing demand for a simple and fast formation of a color image with high quality.

[0003] As a color image forming apparatus, an electrophotographic recording system is generally known. In this electrophotographic recording system, a drum-type electrophotographic photosensitive member (hereinafter, referred to as a “photosensitive drum”) as an uniformly charged image carrier is exposed to form an electrostatic latent image. A method of transferring a toner image obtained by visualizing an electrostatic latent image onto transfer paper as a transfer material is widely known.

As a color image forming apparatus using the above-mentioned electrophotographic recording system, a multi-developing / batch transfer system and a multi-transfer (sequential transfer) system are known. The former multiple development / batch transfer method is a method in which a photosensitive drum is charged and exposed to form an electrostatic latent image, which is then developed and developed into a visible image a plurality of times (four times or three times). This method includes a transfer step of repeatedly transferring a multicolor image from the photosensitive drum to transfer paper after the multiple development on the photosensitive drum. According to this multiple development / batch transfer method, an inexpensive and compact multicolor image forming apparatus with a simple configuration can be realized without reducing the printing speed.

However, this multiple development / batch transfer system is
At the time of multiple development, there was a case where a sufficient electrostatic latent image could not be formed due to the influence of the preceding toner image, the preceding toner image was disturbed, and color mixing with the preceding toner image occurred. Therefore, there is a problem in obtaining a high-definition and high-quality multicolor image.

In the latter multiple transfer system, a photosensitive drum is charged and exposed to form an electrostatic latent image, which is then developed,
This is a method in which an image forming step of developing a visible image and a transfer step of transferring a toner image visualized on a photosensitive drum onto transfer paper are alternately repeated a plurality of times (four or three times). According to the multiple transfer method, a high-definition and high-quality toner image can be obtained.

[0007]

However, in the above-described conventional multiple transfer system, a transfer drum having a longer peripheral length than the transfer paper of the maximum size is generally used as a transfer material conveying means for performing multiple transfer. This transfer drum has a fixed circumference, so when using small-size transfer paper,
There is a problem that the same printing time as that of a large-size transfer paper is required. Therefore, when an image is formed using transfer paper having a size equal to or less than half of the circumference of the transfer drum, two devices are attached to the transfer drum to reduce the printing time. It cannot handle transfer paper having a size equal to or more than half the circumference of the drum, and cannot support one image formation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an image forming apparatus in which the printing time is changed according to the size of a transfer material. I do.

[0009]

In order to achieve the above object, an image forming apparatus according to the first aspect of the present invention comprises an image carrier and a transfer material which moves relative to the image carrier. Transfer means for supporting and transporting the transfer material, and a transfer step of multiple transfer of a visible image formed on the image carrier to the transfer material, wherein the transfer material is It is characterized by having a multiple transfer conveyance path control means for controlling the distance moved to the transfer of the step.

According to a second aspect of the present invention, the transfer material transfer means for multiple transfer which supports and transfers the transfer material for multiple transfer is an endless belt, and the position of the transfer material on the transfer material transfer means for multiple transfer. And means for controlling the substantial transfer distance of the transfer material by changing

According to a third aspect of the present invention, there are provided a plurality of transfer material transfer means for multiple transfer, and a transfer switching control means for switching and controlling the plurality of transfer material transfer means for multiple transfer.

According to a fourth aspect of the present invention, there are provided a plurality of transfer material transporting means, and a plurality of transfer material transporting means are combined into one transfer material transporting means for multiplex transfer. A transport path length control unit for changing a length of at least one transfer material transport path of the unit.

According to a fifth aspect of the present invention, the endless belt adsorbs a transfer material and supports and transports the transfer material. The shape of the endless belt is changed so that the transfer material supported by the endless belt is skipped and transported. Thus, a means for controlling the moving distance of the transfer material is provided.

According to a sixth aspect of the present invention, the transfer material is moved relatively to the image carrier on which the toner image is formed, and the toner images of different colors formed on the image carrier are transferred to the transfer material. A transfer material endless transport band for holding and transporting the transfer material so as to move the transfer material relative to the image carrier; and a transfer material endless transport band. A plurality of roller members to which the transfer material is stretched, and the transfer material endless transporting belt in the stretched state is pushed inward from between two predetermined adjacent roller members of the roller members, whereby A pressing member that forms a detour portion of the transfer material endless transport zone between two roller members, and a transfer portion that transfers the transfer material at a root portion thereof; and the transfer material usually includes the plurality of roller members. Extension of endless transport belt On the other hand, the moving roller member which is pressed by the transfer material endless conveyance band forming the detour by the pressing operation of the pressing member and moves inward, and the pressing depth of the pressing member is set to the size of the transfer material. The transfer path length control means for controlling the transfer path length of the transfer material in accordance with the transfer path length.

According to a seventh aspect of the present invention, the transfer material endless transport band has a plurality of grippers for holding the transfer material, and the transport path length control means is located at a forward position in the transfer section. Is controlled so that the transfer material held by the gripper located behind the gripper to be separated is separated and delivered.

According to the invention described in claim 8, the gripper is attached to both side edges in the width direction of the transfer material endless transport band.

According to a ninth aspect of the present invention, a transfer material is moved relative to an image carrier on which a toner image is formed, and different color toner images formed on the image carrier are transferred to the transfer material. A transfer material endless transport band for holding and transporting the transfer material so as to move the transfer material relative to the image carrier, and the transfer material endless transport band A first transfer material conveying means for conveying a transfer material having a predetermined size or less, and a plurality of roller members for stretching the transfer material, the first transfer material conveying device being disposed adjacent to the first transfer material conveying means, Endless transfer belt for transfer material to be held and transported, a plurality of roller members for stretching the endless transport belt for transfer material, and transfer material in a stretched state between two predetermined adjacent roller members of the roller members By pushing the endless transport belt inward, the adjacent A pressing member that forms a pressing portion of the transfer material endless conveyance band between two roller members, and the transfer material endless conveyance band is usually stretched together with the plurality of roller members. A transfer roller member that moves inward by being pressed by the transfer material endless transfer band in which the pressing portion is formed, and transfers and transfers a transfer material having a predetermined size or more to and from the first transfer material transfer means. And a transfer path for transferring the transfer material from the first transfer material transfer means to the second transfer material transfer means, and the pressing depth of the pressing member is set to the size of the transfer material. And a conveyance path length control means for controlling the conveyance path length according to the control.

According to a tenth aspect of the present invention, the transfer material endless transport band has a plurality of grippers for holding the transfer material, and the transport path length control means includes a first transfer material transport means. At a portion adjacent to the first transfer material transporting means and the gripper of the second transfer material transporting means, and between the gripper of the second transfer material transporting means and the first The transfer material is controlled to be held again so as to deliver the transfer material to the gripper of the transfer material conveying means.

According to the eleventh aspect of the present invention, the gripper is attached to both side edges in the width direction of the transfer material endless transport band.

[Operation] According to the above arrangement, the present invention provides:
At the time of multiple transfer onto the transfer material, the pressing member is controlled by the transfer path length control means so as to change the distance required for the transfer according to the size of the transfer material, and the pressing member stretches the plurality of roller members. The transfer belt is pushed in while the transfer roller member is moved inward to change the transfer path length of the transfer material. In this case, at the transfer portion at the root portion of the detour of the transfer material endless conveyance band pushed by the pressing member, the transfer material is attached to the endless conveyance band, and the gripper located at the front is gripped by the gripper located at the rear. To transfer the transfer material and reduce the distance required for transporting the transfer material.

In another aspect of the present invention, when a transfer material having a size equal to or less than a predetermined size is transferred, the transfer material is transferred using a first transfer material transfer means having a transfer material endless transfer band stretched by a roller member. For multiple transcription. When transferring a transfer material having a predetermined size or more, the transfer path is controlled by a transfer path length control means so as to transfer the transfer material from the first transfer material transfer means to the second transfer material transfer means. Then, the transfer material is multiplex-transferred. In this case, at a portion adjacent to the first transfer material transporting device and the second transfer material transporting device, the transport path length control device controls the second or the second transfer material transporting device from the gripper of either the first or second transfer material transporting device. The transfer path is switched by re-holding the transfer material on the other gripper of the first transfer material transfer means.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. <First Embodiment> FIG. 1 is an overall configuration diagram showing an image forming apparatus according to a first embodiment of the present invention, and FIG. 2 is a view for explaining a transfer material transport path for multiple transfer. FIG. 4 is a cross-sectional view illustrating a transfer belt unit.

First, in FIG. 1, the image scanner unit 1 reads a document and performs digital image signal processing. The printer unit 2 is a part that prints an image corresponding to the document information obtained by reading the document by the image scanner unit 1 on transfer paper 53 as a transfer material. Both the image scanner unit 1 and the printer unit 2 have a resolution of 400 dpi.

First, a document G is placed on the document table 3 with the surface to be copied facing downward. Next, copying is started by pressing the copy button. The image scanner unit 1 scans a document while irradiating the document with a unit 4 in which a document irradiating lamp, a short focus lens array and a CCD sensor are integrated. The image is made incident on the CCD sensor. The CCD sensor includes a light receiving unit, a transfer unit, and an output unit. The light signal is converted into an electric signal in the light receiving portion of the CCD sensor, and is sequentially transferred to the output portion in synchronization with the clock pulse in the transfer portion. I do.
The analog signal thus obtained is converted into a digital signal by well-known image processing and sent to the printer unit 2.

The printer unit 2 includes an electrophotographic photosensitive drum 11 as an image carrier that is driven to rotate in the direction of arrow R11,
Charger 12 provided sequentially in the drum rotation direction around photosensitive drum 11 Rotary developing device 13 including developing devices 13M, 13C, 13Y, and 13K accommodating two-component developer, transfer charger 15, charge removal charging The photosensitive drum 11 includes a vessel 17, a cleaning device 16, and a laser beam scanner 10 provided above the photosensitive drum 11.

Developing devices 13M, 13C, 13Y, 13K
Uses a two-component magnetic brush developing device widely used in the past. An oscillating bias voltage obtained by superimposing a DC voltage on an AC voltage is applied to the developing sleeve. Each of the developing devices 13M, 13C, 13Y and 13K supplies a two-component developer containing a non-magnetic toner and magnetic particles (carrier) to the photosensitive drum 11. The developer of the developing device 13M contains magenta toner, the developer of the developing device 13C contains cyan toner, the developer of the developing device 13Y contains yellow toner, and the developer of the developing device 13K contains black toner. The laser beam scanner 10 includes a semiconductor laser, a polygon mirror, an fθ lens, and the like, receives an input of an electric digital pixel signal, and outputs a laser beam modulated in accordance with the digital pixel signal to the charger 12 and the rotary developing device 13. And the drum surface is exposed by scanning in the drum genera direction.

The sequence of the entire full-color printer will be briefly described by taking a full-color mode as an example. First, the photosensitive drum 11 is uniformly charged by the charger 12. Next, image exposure is performed by the laser beam E modulated by the magenta image signal of the document G, and an electrostatic latent image is formed on the photosensitive drum 11.
Magenta development is performed by a magenta developing unit 13M which is set in advance at a developing position, and a magenta image is formed on the photosensitive drum 11.

The printer main body 51 is provided with paper cassettes 52a and 52b accommodating transfer paper 53. One of the upper and lower sheet cassettes 52a, 52b,
When 52b is selected, the transfer paper 53 is fed by the paper feed rollers 54a and 54b with the rotation of the photosensitive drum
Send out from 2a, 52b. Paper feed rollers 54a, 54b
The transfer paper 53 sent from the printer reaches a registration roller pair 55 via a paper feed guide and a feed roller. The transfer paper 53 is synchronized with the toner image on the photosensitive drum 11 at a predetermined timing by a pair of registration rollers 55, and the attraction charger 41,
The transfer belt 42 electrostatically attracts and holds the transfer belt (transfer material endless transport belt) 31 constituting a transfer material transport unit described later.
The transfer belt 31 is synchronized with the photosensitive drum 11 by an arrow R shown in FIG.
The visible image rotating in the 31 direction and developed by the magenta developing device 13M is transferred to the transfer paper 53 by the transfer charger 15 in the transfer section. The transfer belt 31 keeps rotating as it is, and prepares for transfer of the next color (cyan in FIG. 1).

On the other hand, the photosensitive drum 11 is provided with a charge removing charger 17.
, Is cleaned by the cleaning device 16, is charged again by the charger 12, and receives the above-described exposure by the next cyan image signal. During this time, the rotary developing device 13 rotates and the cyan developing device 13C
Are fixed at a predetermined developing position to perform a predetermined cyan development. Then, the cyan image on the photosensitive drum 11 is transferred onto the transfer paper 53.

Similarly, the above steps are repeated to transfer the yellow image and the black image to the transfer paper 5 respectively.
3 is performed. When the transfer for four colors is completed,
The transfer paper 53 on which the visible images of four colors are formed is neutralized by the neutralization charger 43 to which an AC voltage is applied, and the transfer belt 3
Separated from 1. Then, the transfer paper 53 is sent to a fixing device 57 that applies heat and pressure to fix the toner by a transfer material transport unit 56. Thereafter, the transfer paper 53 on which the image formation has been completed is discharged by the discharge rollers 58 to the discharge stacker 5.
9 is discharged. Thus, a series of full-color print sequences is completed, and a required full-color print sequence image is formed.

In the case of single-color printing, the developing unit 13
Develop with any of C, 13M, 13Y, and 13K.

Next, control of the transfer path of the transfer material in the transfer material transfer means for performing the multiple transfer will be described with reference to FIG.

In FIG. 3, reference numeral 30 denotes a transfer belt unit as a transfer material transfer means for performing transfer, and suction transfer of the transfer paper 53 to multiplex-transfer the visible image on the photosensitive drum 11 onto the transfer paper 53. Things. The transfer belt unit 30 includes a transfer belt 31 which is a transfer material endless conveyance belt.
Are provided with a driving roller 33 as a roller member, an idle roller 35 as a moving roller member, idle rollers 34, 36 and 37 as roller members, and an adjusting roller 38 as a roller member. Rollers 38 adjust the tension of the transfer belt 31. Then, a pressing roller 39 as a pressing member is pressed between the adjacent idle rollers 36 and 37 to form a detour portion 40 on the transfer belt 31 so that the idle roller 35 moves to a position indicated by a dotted line in the drawing. ing.

The idle rollers 34, 35, 36,
When the transfer belt 31 and the pressing roller 39 are set at the positions indicated by the solid lines, the transfer belt 31 is disposed at the position indicated by the solid lines.
3 passes through a long transport path indicated by arrow A. Further, the transfer belt 31 is pressed by the pressing roller 39 to form the bypass part 40, so that the idle roller 34,
When the transfer rollers 31, 36, 37 and the pressing roller 39 are set at the positions indicated by the dotted lines, the transfer belt 31 is disposed at the position indicated by the dotted lines, and the transfer paper 53 is transferred at the transfer portion at the base portion of the detour portion 40, It passes through the short transport path shown in FIG.

The length Lmax of the transport path indicated by arrow A
Is longer than the length Wmax of the maximum size transfer paper 53 in the transport direction. In order to prevent the transfer paper 53 held on the transfer belt 31 from overlapping, the length (distance required for conveyance) L of the transfer path of the transfer paper 53 may be larger than the size W of the transfer paper 53. That is, L = W +
It should be X. X is a margin. Therefore,
The maximum size transfer paper 53 can be used without any trouble.

Further, the position of the pressing roller 39 pushed between the idle rollers 36 and 37 is set between the solid line and the dotted line in FIG. ), The length of the transfer path of the transfer paper 53 can be set steplessly. In this way, the pressing roller 39 is pushed into the arbitrary depth (position 39 'in FIG. 2) from the space between the idle rollers 36 and 37 or is separated from the idle rollers 36 and 37 (position 39 in FIG. 2). This makes it possible to change the transport path of the transfer paper 53 for performing multiple transfer by one transfer belt unit 30 and the distance required for transport, so that the length of the transport path can be reduced according to the size of the transfer paper 53. It can be set appropriately. Thus, the transfer path of the transfer paper 53 can be efficiently reduced, so that the printing time can be efficiently reduced for any transfer paper 53. Note that the transfer paper 53 having a size equal to or less than half the length Lmax of the longest transport path is used.
When printing a plurality of sheets, two sheets can be attached.

FIG. 3 is a block diagram illustrating a control configuration of an embodiment of a digital electrophotographic copying machine to which the present invention is applied. In the drawing, reference numeral 301 denotes a sheet cassette 52a,
A paper size detecting unit 302 for detecting the size of the transfer paper 53 stored in the paper cassette 52b;
a and 52b, a paper cassette selecting means 303; a paper size detecting means 301 and a paper cassette selecting means 302;
Paper size setting means for setting the size of the transfer paper 53 according to the above; 304, a main control unit for comprehensively controlling the print sequence; 305, a transfer path for the transfer paper 53; A conveyance path control unit 306 as a conveyance path length control unit for performing the re-control is a conveyance path of the transfer belt unit 30 controlled by the conveyance path control unit 305.

When the size W of the transfer paper 53 is set by the paper size setting means 303, the transport path control unit 3
05 and idle rollers 36 and 37 and pressing roller 3
9, the distance L required for the transfer of the transfer paper 53 is controlled to “W + X”. In this way, the printing time can be efficiently reduced corresponding to various sizes of the transfer paper 53.

Next, the numerical value sequence will be described. For example, the peripheral speed of the photosensitive drum 11 is V = 100 mm / sec, and the length of the maximum size transfer paper (A3-size vertical feed) in the transport direction is Wmax =
240 mm, the extra length X = 30 mm, and the maximum length of the transport path was Lmax = 450. In the case of performing multi-transfer of four colors, the transfer paper 53 needs to repeatedly move the multi-transfer conveyance path of the transfer belt unit 30 from the transfer position to the transfer position three times. The transport route at this time (repeated 3
Table 1 shows the length of transfer times, transfer papers of various sizes, and the reduction of printing time.

[0040]

[Table 1] As described above, according to the present embodiment, a clear and high-quality image can be obtained, and when a small-size transfer paper is used with a simple configuration, it is possible to cope with various transfer paper sizes. Printing time can be shortened. <Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 4 is an overall configuration diagram showing a second embodiment of a digital electrophotographic copying machine to which the present invention is applied.

This embodiment is different from the first embodiment only in the transfer material conveying means for performing the multiple transfer, and the other conditions are the same as those in the first embodiment. And a duplicate description is omitted.

That is, in the first embodiment, the multiple transfer conveyance path is created by one transfer belt, but in this embodiment, the first transfer material conveyance means 60 and the second transfer material conveyance Means 70 are provided independently of each other, and a multiple transfer conveyance path can be created only by the first transfer material conveyance means 60, and a multiple transfer conveyance path is created by cooperating the two transfer material conveyance means 60 and 70. It has a configuration that can be used.

In the first embodiment, the transfer paper 53
Is electrostatically held on the transfer belt by adsorption charging. In the present embodiment, the transfer paper 53 is held by a gripper provided on the transfer belt.

FIG. 5 is a sectional view of the transfer material conveying means for explaining the transfer material conveying path for the multiple transfer. In the figure, reference numeral 60 denotes a transfer belt unit as a first transfer material conveying means, and 70 denotes a transfer belt unit as a second transfer material conveying means.
The transport belt unit 70 is provided for performing multiple transfer, and holds and transports the transfer paper 53 to perform multiple transfer of the visible image on the photosensitive drum 11 to the transfer paper 53. Reference numerals 67 and 68 denote the transfer belt unit 60 to the transport belt unit 70 or the transport belt unit 70
Is a guide member for transferring the transfer paper 53 from the transfer belt unit 60 to the transfer belt unit 60. The transfer belt unit 60
The transfer belt 61, which is a transfer material endless conveyance belt, is
3, the idle rollers 64 and 65, and the tension adjusting roller 66.
Adjust the tension of 1. Further, the transfer belt 61 is provided with grippers 62a and 62b. Gripper 62a
The gripper 62b grips and holds the leading end of the transfer paper 53, and the gripper 62b grips and holds the side end of the transfer paper 53.

The transport belt unit 70 includes a transport belt 71, which is a transfer material endless transport belt, around which a drive roller 73, idle rollers 74 and 75, and a tension adjusting roller 76 are wound. The pressing roller 77 is pressed into the conveying belt 71 to form a pressing portion 79 in the conveying belt 71, thereby adjusting the tension. Further, the transport belt 71 is provided with grippers 72a and 72b. The gripper 72a holds and holds the leading end of the transfer paper 53, and the gripper 72b holds and holds the side end of the transfer paper 53. The circumference of the transfer belt unit 60 is L
1, the transfer paper 53 having a size smaller than L1 is transferred to the photosensitive drum 11 by the registration roller 55 at a predetermined timing.
The toner image is held by the gripper 62a in synchronization with the upper toner image, and passes through the transport path indicated by the arrow A only by the first transfer belt unit 60 as it is.

The transfer paper 53 having a size larger than L1 passes through a transport path created by the transfer belt unit 60 and the transport belt unit 70 in cooperation. That is, the transfer material 53
Is held by the gripper 62a at a predetermined timing in synchronization with the toner image on the photosensitive drum 11 by the registration roller 55, is conveyed on the transfer belt 61, and after the visible image is transferred by the transfer unit, the transfer paper 53 is When approaching the transport belt unit 70, the gripper 62b temporarily holds the gripper 62b and releases the gripper 62a. And
The transfer paper 53 is transferred from the transfer belt unit 60 to the transport belt unit 70 via a guide portion 67 between the transfer belt unit 60 and the transport belt unit 70,
The holding by the gripper 72a is released in synchronization with the predetermined timing, and the holding of the gripper 62b is released.

In this manner, the transfer paper 53 is transferred from the transfer belt 61 to the transport belt 71, and is transferred to the transport belt 71.
Conveyed above. When the transfer paper 53 on the conveyor belt 71 approaches the transfer belt unit 60, the transfer paper 53 is once held by the gripper 72b, and the gripper 72a is released, so that the transfer paper 53 is moved between the transfer belt unit 70 and the transfer belt unit 60. Is transferred from the conveyor belt unit 70 to the transfer belt unit 60 via the guide portion 68 of
The gripper 62a is held in synchronization with the predetermined timing, and the holding of the gripper 72b is released. Transfer belt 6
The transfer paper 53 transferred to 1 is further transported to the transfer unit. In this way, the transfer paper 53 is transported using the outer surface of the transfer belt unit 60 and the transport belt unit 70 that are not opposed to each other as the transport path.

When the idle rollers 74 and 75 and the pressing roller 77 are set at the positions indicated by the solid lines, the transfer belt 71 is disposed at the position indicated by the solid lines, and the transfer paper 53 passes through the long transfer path indicated by the arrow B. When the idle rollers 74 and 75 and the pressing roller 77 are set at the positions indicated by the dotted lines,
1 is arranged at a position indicated by a dotted line, and the transfer paper 53 passes through a slightly shorter transport path shown by an arrow C.

The length L of the long transport path shown by arrow B
max is the length Wmax of the maximum size transfer paper 53 in the transport direction.
Is bigger than. Furthermore, idle roller 7
It is also possible to set the positions of 4, 75 and the pressing roller 77 between the solid line and the dotted line in FIG. In this way, the length of the transfer path of the transfer paper 53 can be set steplessly.

As described above, in the present embodiment, the transfer path from the previous stage transfer to the main stage transfer for the multiple transfer is controlled to be switched, so that a small configuration can be realized with a simple configuration and simple operation. The printing time of the transfer paper 53 can be reduced.

Further, since the length of the conveyance path from the previous transfer to the main transfer can be changed, the transfer paper 5
By appropriately setting the length of the transport path corresponding to the size of No. 3, the length of the transport path of the transfer paper 53 can be efficiently changed. The printing time for the transfer paper 53 can be shortened efficiently.

Further, since the gripper is used, the transfer paper 53 can be transported more reliably. <Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is an overall configuration diagram showing a third embodiment of a digital electrophotographic copying machine to which the present invention is applied.

This embodiment is different from the first embodiment only in the transfer material conveying means for performing the multiple transfer, and the other conditions are the same as those of the first embodiment. And a duplicate description is omitted.

That is, in the first embodiment, the transfer paper 5
Although the transfer paper 53 is electrostatically held by suction charging, in the present embodiment, the transfer paper 53 is held by a grip.

FIG. 7 is a sectional view of a transfer belt unit for explaining a transfer material transport path for multiple transfer. In FIG. 1, reference numeral 30 denotes a transfer belt unit serving as a transfer material conveying means for performing multiple transfer, which holds and conveys the transfer paper 53 and multiply transfers the visible image on the photosensitive drum 11 to the transfer paper 53. . The transfer belt unit 30
The transfer paper 53 is composed of a driving roller 33 and idle rollers 34 and 3.
5, 36, 37 and the adjusting roller 38 are wound.
The adjusting roller 38 adjusts the tension of the transfer belt 31. The pressing roller 39 is used for the idle roller 3
The idle roller 35 is configured to move to a position indicated by a dotted line in the drawing by being pushed between the idle rollers 6 and 37.

Further, grippers 321, 322, and 322 are provided on the transfer belt 31 from the upstream side in the conveying direction of the transfer paper 53.
323, 324,... Are provided. When the idle rollers 34, 35, 36, and 37, the adjusting roller 38, and the pressing roller 39 are set to the positions indicated by the solid lines, the transfer belt 31
Are disposed at positions indicated by solid lines, and the transfer paper 53 passes through a long transport path indicated by an arrow A. Idle rollers 34, 35, 36,
When the 37, the adjusting roller 38, and the pressing roller 39 are set at the positions indicated by the dotted lines, the transfer belt 31 is disposed at the position indicated by the dotted lines, and the transfer paper 53 passes through a short conveyance path indicated by an arrow B.

The length Lmax of the long transport path indicated by arrow A is the length Wma of the maximum size transfer paper 53 in the transport direction.
greater than x.

The transfer paper 53 is held by, for example, a gripper 324 in synchronism with a predetermined timing by a registration roller 55, is conveyed on the transfer belt 31, and after a visible image is transferred by a transfer unit, the transfer paper 53 is transferred. Immediately before passing through the base portion (transfer portion) of the bypass portion 40 of the belt 31, the gripper 323 is temporarily held by the gripper 323 on the upstream side (rearward) in the transport direction of the transfer belt 31, and
24 is released. Then, the transfer belt 31 is held by, for example, a gripper 326 on the downstream side (front side) of the transfer belt 31,
The holding of the gripper 323 is released.

In this way, the transfer paper 53 jumps on the transfer belt 31 from the position of the gripper 324 to the position of the gripper 326 on the downstream side (front) and advances. In this way, the length of the transfer path of the transfer paper 53 can be reduced by at least one or more gripper intervals. In other words, the length of the transfer path of the transfer paper 53 can be set in multiple stages at the distance from the gripper to the gripper.

As described above, the length of the transfer path from the previous transfer to the main transfer for multiple transfer by one transfer material transfer means can be changed. Thus, the transport path can be set appropriately. Also,
Since the transport path of the transfer paper 53 can be efficiently changed, the print time can be efficiently reduced for any transfer paper 53.

Next, the numerical value sequence will be described.

For example, the length of the transfer belt is 448 mm, 16 grippers are provided with 28 mm, the peripheral speed of the photosensitive drum is V = 100 mm / sec, and the maximum size of the transfer paper (A3-size vertical feed) in the transport direction is set. Assuming that the length is Wmax = 420 mm and the margin length is X = 14 mm, the length of the maximum transport path is Lmax =
448. In the case of performing the multiple transfer in four colors, the transfer paper 53 needs to repeatedly move the multiple transfer transport path from the transfer position to the transfer position three times. Table 2 shows the length of the transport path (repeated three times), the transfer paper 53 of various sizes, and the reduction of the printing time at this time.

[0065]

[Table 2] As described above, according to the present embodiment, a clear and high-quality image can be obtained, and when a small-size transfer paper 53 is used with a simple configuration, various types of transfer paper 53 can be used. The printing time can be shortened according to the size. Further, since the gripper is used, the paper can be transported more reliably than the transfer paper 53.

[0066]

As described above, according to the present invention, the distance over which the transfer material moves from the previous transfer to the main transfer is controlled by the multiple transfer conveyance exposure control means. , The print time can be changed.

According to another aspect of the invention, when performing multiple transfer onto a transfer material, the pressing member is controlled by the transfer path length control means so as to change the distance required for transfer according to the size of the transfer material. Since the transfer member endless conveyance belt on which the roller member is stretched is pushed by the pressing member, and the transfer path of the transfer material is switched, the transfer material at the base portion of the detour portion of the transfer material endless conveyance band is transferred. Is transferred, the distance required for transporting the transfer material can be reduced, and the printing time can be changed according to the size of the transfer material.

In another aspect of the present invention, when a transfer material having a size equal to or smaller than a predetermined size is transferred, the transfer material is transferred using a first transfer material transfer means having a transfer material endless transfer band stretched by a roller member. When transferring a transfer material having a predetermined size or more, the transfer path length control means controls the transfer material from the first transfer material transfer means to the second transfer material transfer means. The transfer path is controlled and the transfer material is multiplex-transferred, so the printing time can be changed according to the size of the transfer material with a simple configuration, and the multi-transfer method enables high definition and high image quality. Can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a transfer belt unit for explaining a transfer material transport path for multiple transfer shown in FIG. 1;

FIG. 3 is a block diagram illustrating a control configuration of the image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is an overall configuration diagram illustrating an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a transfer material transport unit for explaining a transfer material transport path for multiple transfer in FIG. 4;

FIG. 6 is an overall configuration diagram illustrating an image forming apparatus according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a transfer material transport unit for explaining a transfer material transport path for multiple transfer shown in FIG. 6;

[Explanation of symbols]

REFERENCE SIGNS LIST 11 image carrier (photosensitive drum) 15 transfer charger 30 transfer material transfer means (transfer belt unit) 31 transfer material endless transfer band (transfer belt) 33 drive roller 34 idle roller 35 idle roller 36 idle roller 37 idle roller 38 adjustment Roller 39 Pressing member (pressing roller) 53 Transfer material (transfer paper) 60 First transfer material transport means (transfer belt unit) 61 Transfer material endless transport band (transfer belt) 62a Gripper 62b Gripper 70 Second transport material transport Means (Conveyor Belt Unit) 71 Transfer Material Endless Conveyor Belt (Conveyor Belt) 305 Conveyance Path Length Control Means (Conveyance Path Control Unit) 321 Gripper 322 Gripper 323 Gripper 324 Gripper 325 Gripper 326 Gripper 327 Gripper 328 Gripper

Claims (11)

[Claims] An image carrier; and a transfer material transporting unit that moves relative to the image carrier and supports and transports the transfer material, wherein a visible image formed on the image carrier is formed. An image forming apparatus having a transfer step of performing multiple transfer onto the transfer material, comprising: a conveyance path length control unit that controls a distance that the transfer material moves from a previous transfer to a main transfer. apparatus. 2. The transfer material transfer means for multiple transfer, which supports and transfers the transfer material for multiple transfer, is an endless belt, and by changing the position of the transfer material on the transfer material transfer means for multiple transfer, The image forming apparatus according to claim 1, further comprising a unit that controls a substantial movement distance of the transfer material. 3. The image forming apparatus according to claim 2, further comprising a plurality of transfer material transporting means for multiple transfer, and a transport switching control means for switching and controlling the plurality of transfer material transporting means for multiple transfer. apparatus. 4. A transfer material transporting means for multiple transfer, comprising a plurality of transfer material transporting means, and combining a plurality of transfer material transporting means, wherein at least one transfer material of said plurality of transfer material transporting means is provided. The image forming apparatus according to claim 2, further comprising a transport path control unit that changes a length of the material transport path. 5. The endless belt is for adsorbing and transferring a transfer material and supporting and transporting the transfer material. By changing the shape of the endless belt and skipping and transporting the transfer material supported by the endless belt, the transfer material is transferred. The image forming apparatus according to claim 2, further comprising a unit configured to control a moving distance of the image forming apparatus. 6. A transfer material is relatively moved with respect to an image carrier on which a toner image is formed, so that toner images of different colors formed on the image carrier are multiplex-transferred onto the transfer material. In the image forming apparatus, a transfer material endless conveyance band that holds and conveys the transfer material so as to move the transfer material relative to the image carrier, and a plurality of the transfer material endless conveyance bands that are stretched. A roller member, and by pressing the transfer material endless transport belt in the stretched state inward from between two predetermined adjacent roller members of the roller member, a gap between the adjacent two roller members is obtained. A pressing member forming a detour portion of the transfer material endless transport band, and forming a transfer portion for transferring the transfer material at a root portion thereof; and usually extending the transfer material endless transport band together with the plurality of roller members. While A moving roller member that is pressed by a transfer material endless transport band that forms the bypass portion by a pressing operation of the pressing member and moves inward, and a pressing depth of the pressing member is controlled according to a size of the transfer material. An image forming apparatus comprising: a conveyance path length control unit configured to switch a conveyance path length of the transfer material. 7. The transfer material endless transport band has a plurality of grippers for holding the transfer material, and the transport path length control means includes:
The image forming apparatus according to claim 6, wherein control is performed such that the transfer material sandwiched by the gripper located at the rear and the gripper located at the front is separated and delivered. 8. The image forming apparatus according to claim 7, wherein the grippers are attached to both side edges in a width direction of the transfer material endless conveyance band. 9. A transfer material is relatively moved with respect to an image carrier on which a toner image is formed, and toner images of different colors formed on the image carrier are multiplex-transferred onto the transfer material. In the image forming apparatus, a transfer material endless conveyance band that holds and conveys the transfer material, and a plurality of the transfer material endless conveyance bands that are stretched so as to move the transfer material relative to the image carrier. A first transfer material transporting unit having a roller member and transporting a transfer material of a predetermined size or less; a transfer material endless disposed adjacent to the first transfer material transporting unit and holding and transporting the transfer material A transfer belt, a plurality of roller members for extending the transfer material endless conveyance band, and the transfer material endless conveyance band in the stretched state inward from a predetermined adjacent two of the roller members. Into the two adjacent rows. Between the members, a pressing member that forms a pressing portion of the transfer material endless transport band, and the transfer material endless transport band is usually stretched together with the plurality of roller members, while the pressing portion is pressed by the pressing operation of the pressing member. A second transfer unit that has a moving roller member that moves inward by being pressed by the formed transfer material endless transfer belt, and that transfers and transfers a transfer material having a predetermined size or more to and from the first transfer material transfer unit. A material transfer unit, and a transfer path of the transfer material from the first transfer material transfer unit to a second transfer material transfer unit, and a pressing depth of the pressing member is controlled according to a size of the transfer material. An image forming apparatus, comprising: 10. The transfer material endless transfer belt has a plurality of grippers for holding the transfer material, and the transfer path length control unit includes a first transfer material transfer unit and a second transfer material transfer unit. At a portion adjacent to the first transfer material transport means from the gripper of the first transfer material transport means to the gripper of the second transfer material transport means, and from the gripper of the second transfer material transport means to the gripper of the first transfer material transport means. The image forming apparatus according to claim 9, wherein control is performed to re-hold the transfer material so as to deliver the transfer material. 11. The image forming apparatus according to claim 10, wherein the gripper is attached to both side edges in the width direction of the transfer material endless conveyance band.