JPH0664782A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a jam from being caused of a transcription material so as to secure reuse thereof by selectively controlling carrying in to a both-side multi-device and a curl remover, so that also sequence control of an image forming mode can be performed. CONSTITUTION:A document is placed in a document feeder 1, to set mode of a number of sheets of transcription or the like. In the case of forming a double image in one or both sides, in the set mode, a transfer material P of forming an image in the first side, after passing through a fixer 12, is fed to a both-side multiplexing path, and the transfer material, correcting its curl by a curl remover 14, is discharged onto an intermediate tray 15. The curl remover 14 is selectively used so as to eliminate a bad influence to also stiffness, toner amount, etc., of the transcription material P. Image information of the document is detected by a document reader 3, and an order of the document is changed to perform copying work by such as selecting document with small image information in the first side. After the copying work, the transcription material P is rearranged in the initially set order of the document. These operations can be embodied by sequence control.

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 apparatus or an electrostatic recording apparatus, and more particularly to an image forming apparatus for forming a plurality of (multiple) images on the back surface (both sides) or one surface of a transfer material. Is.

[0002]

2. Description of the Related Art Conventionally, a toner image of plural colors is sequentially formed on the outer surface of an image carrier having a drum shape or an endless belt shape, and the toner images are formed on a transfer drum (rotary transfer material carrying means). 2. Description of the Related Art There is known an image forming apparatus that forms a multicolor image by sequentially transferring onto a transfer material that is positioned and held by.

In the apparatus, the method for positioning and holding the transfer material on the transfer drum is to hold the transfer material by gripping the tip of the transfer material with a gripper, or to hold the transfer material by electrostatic attraction (Coulomb force). There is a way to do it.

Among these, the one utilizing electrostatic attraction force can hold the transfer material at any position of the transfer drum, and when a plurality of small-sized transfer materials are held on the transfer drum, the transfer materials are separated from each other. Since it is possible to reduce the distance between the two and improve the efficiency of transfer, it is becoming more widely used than the one using a gripper.

Further, these image forming apparatuses are often equipped with a double-sided / multiplexing apparatus capable of forming images on the back surface (both sides) or one side of a transfer material a plurality of times (multiplexing). The equipment ratio of double-sided / multiplexing devices is increasing, as the back side is increasingly used to effectively use the transfer material. Since such an image forming apparatus can form not only a color image but also a monotone (black and white) image and the like, there is an advantage that various image information can be formed on a transfer material in combination with double-sided / multiplexing.

[0006]

However, in the above-mentioned conventional example, especially in the color image forming apparatus, the transfer material is held on the transfer material holding member by electrostatic attraction force (Coulomb force), or a plurality of colors are transferred. Since different toners are used and the amount of oil in the fixing portion is larger than that in a monotone (black and white) image forming apparatus, it is difficult to use the transfer material for the second time and thereafter.

For example, since toners of different colors are used, the curl amount of the transfer material after passing through the fixing portion is different depending on the amount of image information, so that the transfer material cannot be conveyed or re-supplied to the intermediate tray, or the transfer material is not supplied. However, the transfer material cannot be adsorbed to the transfer material supporting member, and the transfer material is clogged (jammed), resulting in extremely poor workability.

As a countermeasure against this, a curl removing means or the like is used. However, since the curl amount is variously changed depending on the image information amount and the type of transfer material, it is difficult to use it.

Further, in the conventional example, as described above, toners of different colors are used. That is, the amount of image information (toner amount) is larger than that of a monotone (black and white) image. Therefore, the curl amount of the transfer material after passing through the fixing portion becomes large, and it is difficult to reuse the transfer material.

That is, when the transfer material is reused, the discharge effect of the corona discharger is deteriorated, and the attraction force (Coulomb force) to the transfer material holding member (transfer drum) is reduced, so that the transfer material is formed in the image forming apparatus. Clogs (jams) may occur.

As a countermeasure, a gripper is used to hold the transfer material on the transfer drum. If you do this,
Even if a double-sided / multiple image is formed, a jam does not occur.
However, the advantage obtained by utilizing electrostatic attraction is lost. In other words, double-sided on multiple small-sized transfer materials
It takes a long time to form multiple images, resulting in poor efficiency.

The present invention has been made by paying attention to such a conventional problem, and has good workability without clogging (jam) of the transfer material. Therefore, the transfer material can be surely reused. An object is to provide an image forming apparatus (hereinafter referred to as a first image forming apparatus).

Further, the present invention provides an image forming apparatus (hereinafter referred to as a second image forming apparatus) which is efficient and does not take much time to form a double-sided / multiplexed image on a plurality of small-sized transfer materials. The purpose is to provide.

[0014]

A first image forming apparatus provided by the present invention is an image forming apparatus equipped with a double-sided / multiplexing device and a curl removing device, and has a means for detecting image information and an image forming mode. A means for detecting, a means for detecting the material type of the transfer material, and a control means for analyzing the detection output of each of these means are provided, and by the control means, the transfer material is carried into the screen / multiplexing device and the curl removing device. Is selectively controlled so that the sequence of the image forming mode can also be controlled.

Further, the second image forming apparatus provided by the present invention forms the image by holding the transfer material on the transfer material holding member by an electrostatic attraction force or a gripper in a predetermined process, and then the same transfer is performed again. In an image forming apparatus that forms an image on the back surface or the same surface of a material by the same process, a means for detecting the curl amount of the transfer material after fixing and a control means for analyzing the detection output are provided. When the transfer material is used again, the electrostatic attraction force or the use of the gripper is selectively controlled.

[0016]

According to the first image forming apparatus, it is possible to prevent the transfer material from jamming (jamming), so that the workability is improved and the transfer material can be surely used again.

Further, according to the second image forming apparatus, it is possible to efficiently form a double-sided / multiplex image on a plurality of small-sized transfer materials in a short time.

[0018]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic configuration of the embodiment, and the image forming process will be briefly described with reference to FIG.

First, a document is conveyed by the circulation type document feeder 1 onto the platen glass 2, and its image information is recorded by the optical system 3.
It is obtained by a document reading device 3 such as a CCD via a. Further, the photosensitive drum 4 as an image bearing member which rotates in the direction of the arrow is uniformly charged by the primary charger 5, and the optical image 6 irradiated by using the exposing means is a four-color movable developing device which is arranged close to the photosensitive drum 4. The image is visualized (tonerized) by the device 7.

The movable developing device 7 includes magenta, cyan,
Store four color developers, yellow and black, separately 4
With one developing device, hold these developing devices,
Further, it is rotated and moved to convey a desired developing device to a position facing the outer peripheral surface of the photosensitive drum 4, and develops an electrostatic latent image corresponding to each color.

On the other hand, the transfer material P is supplied from the cassette,
The registration roller 8 sends the toner image to the transfer material P by sending the toner image to the transfer drum D in timing with respect to the visible image. At this time, the transfer material P applies an electrostatic force (Coulomb force) to the suction corona charger 9 and the suction roller 10.
And is held by the transfer drum D. Further, when a sufficient electrostatic attraction force cannot be obtained due to the material and thickness of the transfer material P, the transfer material P is held by the gripper of the transfer drum D (see FIG. 10). After the completion of the transfer process, the transfer material P is sent to the fixing device 12 by the conveying unit 11, where the toner image is fixed. The fixing device 12 includes a device 13 that applies silicone oil or the like to enhance the peeling property between the fixing roller and the toner on the transfer material P and to protect the fixing roller.

After fixing the toner image, the transfer material P is ejected out of the image forming apparatus in the mode in which the image is formed only on one side thereof (the mode in which the image is formed only on the first side).

In the mode in which a double image is formed on both sides or one side of the transfer material P, the transfer material P having the image formed on the first surface is sent to the screen multiplexing path after passing through the fixing device 12. The curl of the transfer material P is corrected by the curl removing device 14 and is discharged onto the intermediate tray 15. After that, similarly, the second image formation is started. That is, the transfer material P on the intermediate tray 15 is sent in the same manner as in the case of the paper feed cassette, an image is formed on the second surface by the same process, and is discharged to the outside of the image forming apparatus.

A sensor S for detecting the curl amount of the transfer material P is installed in the transfer material guide on the downstream side of the fixing device 12. The structure around the sensor S is as shown in FIG. In the figure, 16 is a lever-shaped lever guide that is pushed outward by a curl portion of the transfer material P and moves, and a sensor S is attached to the upper surface thereof. Reference numeral 17 is a rotating shaft of the lever guide 16, 18 is a spring for pressing the lever guide 16 against the fixed conveyance guide 19, and 20 is a sensor S.
The transfer guide is a transfer guide whose inlet side is open outward so as not to hinder the transfer of the transfer material P even if the lever guide 16 moves.

The main cause of curling of the transfer material P is that the toner on the transfer material P is made of resin or the like, so that the contraction rate of the transfer material and the contraction rate of the toner differ after fixing, and the contraction rate is large. This is because the toner curls on the toner side (front side).

The curl amount of the transfer material P can be represented by the height C of the end portion when measured as shown in FIG. Then, as shown in FIG. 4, after the transfer material P has passed through the fixing device, the toner does not start shrinking in a short time and the curl amount C is small, but after a while, the toner is contracted by cooling and the curl amount C starts. It stabilizes at a certain amount. Curl amount C
5 and the toner amount a which is the image information amount are as shown in FIG. 5. In particular, in a color image forming apparatus, there are four types of toner, and the toner amount a is four times as large as the simple consideration. Therefore, the curl amount C increases. Further, as shown in FIG. 6, the curl amount C changes depending on the thickness b of the transfer material P which is the paper. That is, as the thickness increases, the transfer material P becomes stiffer and the curl amount C decreases.

FIG. 7 shows a state in which the image is stocked upward (for both sides) on the curled transfer material P and the intermediate tray 15 of the duplexer, and when the image is stocked downward. The state (for multiplexing) is shown in FIG. When the image is directed downward, the re-feeding side end of the transfer material P is sandwiched between the pickup roller 21 and the intermediate tray 15 as shown in FIG. 9, and it is easy to re-feed a little. . In addition,
22 is a re-supply roller.

The curl of the transfer material P can be prevented by a curl removing device 14 such as a curl removing roller whose roller nip width and pressure are adjusted while the curl is small after passing through the fixing device 12. However, in this case, the curl removing device 14 may give an excessive amount of reverse curl, or the curl may not be properly corrected when the image for the second side is formed. It may be necessary to adjust each time according to. In addition,
23 is a sorter.

As shown in FIG. 10, the transfer material carrying member 24
Is wound around a transfer drum D made of a transfer ring 25. The transfer material P is sandwiched by the grippers 26. The curl direction of the re-supplied transfer material P was set so that the image was directed to the transfer drum D (for both sides) and the image was not directed to the transfer drum D side with respect to the curvature of the circumference of the transfer drum D. When (for multiple) it is different. Therefore, the electrostatic attraction force when the transfer material P is again attracted to the transfer drum D changes, and the holding force of the transfer material P is different between the double-sided and the multiplex.

Next, the operation will be described with reference to the flowchart of FIG.

First, one or a plurality of originals are put into the original feeding apparatus 1 and a mode such as the number of sheets to be copied is set. When the set mode is only one side (step 1), normal copying is performed as it is (step 8). When the double-sided or multi-sided mode is set, when the transfer material P used is double-sided or multi-sided, curling becomes a problem, and whether or not a jam occurs will be remembered beforehand in advance. At that time, when the cassette etc. is opened and the transfer material P of a different kind is exchanged,
Reset each time and remember the above data for each cassette. If the transfer material P used here has no problem, it is used as it is (steps 2 and 3). If there is no data immediately after the transfer material P of the cassette is exchanged, the set number of sheets is first used as new data n (steps 4, 5, 11, 12, 17, 18).

Regarding the image information amount, as shown in FIG. 5, the curl amount increases as the toner amount increases. The curl amount also changes depending on which part of the transfer material P the image is formed on. For example, when an image with a large amount of toner is formed only on the leading end of the transfer material P in the transport direction, the intermediate tray 1
When the transfer material P is put on the sheet 5, it is difficult to re-supply the curled position at the leading end portion in the case of multiple use, but in the double-sided use, since the leading end portion and the trailing end portion of the transfer material P are reversed, re-feeding is performed. Will be easier.

When the transfer materials P are stocked on the intermediate tray 15, as shown in FIGS. 7 and 8, when the images on the transfer materials P face downward, the images tend to be stacked more easily than they face upward, and the re-feeding is also possible. It will be easy. Therefore, when images are formed on both surfaces of the transfer material P from two originals, it is preferable that the originals having a small amount of toner be first surface even if the order is selectively changed. Also, the number of sheets that can be stacked on the intermediate tray 15 varies depending on the toner amount, the double-sided / multiplexing mode, and the type of the transfer material P. Here, as a curl countermeasure, the curl removing device 14 is used as necessary when creating the second surface.

The decurling is selectively used so that there is no adverse effect on the stiffness of the transfer material P, the amount of toner, the preparation of the second surface, the completion of preparation, and the like. Therefore, the number n of sheets that can be reliably produced is determined, n sheets of transfer material are used in that mode, and finally the target number is obtained (step 11,
12, 17, 18). In the meantime, if the curl amount significantly changes and a jam occurs, the value of the number n of sheets that can be surely produced at one time is changed to continue the production. After the second surface has been created, the curl direction and amount further change, so the curl removing device 14 is selectively used accordingly (steps 6, 7, 13, 14).

The image information of the document is detected by the document reading device 3 and it is determined how the order of the document should be changed. For example, the order of the originals is changed by using the original feeding device 1, the image memory, or the like, such as selecting one having a small amount of image information on the first side. Then, the copying operation is performed as described above. When the order of the originals is changed and a copying operation is performed, the transfer materials are rearranged in the order initially set for the originals. As a method thereof, the transfer material P is discharged to the corresponding bin positions in order by the sorter 23, and when the order of the first surface and the second surface of the transfer material P is changed, the transfer material reversing section is used. Reverse discharge and correct the front and back. Finally, the order of the originals is also corrected to the order in which the originals were first set in the original feeding device 1 (steps 8, 9,
10, 15, 16).

Next, the operation for forming an image on a plurality of small-sized transfer materials will be described with reference to the flowchart of FIG.

In the double-sided mode or the multiplex mode and the mode other than the plural-sheet mode for small size sheets, the transfer material P is held on the transfer drum D for image formation on the first side, and at this time, as shown in FIG.
As shown in FIG. 5, the transfer material P is held by the gripper 26.
In this way, the conveyance and the predetermined process are performed without being affected by the curl amount C of the transfer material P (step 2).
1, 25).

In the double-sided mode or the multiplex mode and the plural-size mode for small-sized paper, an image is formed on one side of the transfer material P, and after passing through the fixing device 12, the curl amount is measured by the sensor S portion (step. 22, 23). When measuring, see Figure 4.
As explained in, the time when the curl amount can be measured correctly,
That is, the sensor S is provided at an appropriate position on the downstream side of the fixing device 12.

Further, as described with reference to FIGS. 7 and 8, the curl amount detection output is analyzed depending on whether double-sided copying or multiplex copying is performed, and the transfer material P is held on the transfer drum D during image formation on the second surface. If it is determined that there is a problem with the electrostatic attraction, the holding by gripping the gripper is selected (step 2).
2, 26). In cases other than these, the electrostatic adsorption method is used to hold the transfer material P on the transfer drum D during image formation on the second surface (step 24). That is, as shown in FIGS. 11 and 12, a plurality of small-sized transfer materials P ₁ , P
₂ can be held at any position on the transfer drum D, and the effect of electrostatic attraction can be fully utilized.

FIG. 15 shows a transfer material reversing portion for double-sided / multiplexing, that is, a reversing flapper 27 and a reversing roller 28 on the downstream side of the intermediate tray 15 in the image forming apparatus shown in FIG.
Is an example in which is provided. With this arrangement, when the transfer material P is stocked on the intermediate tray 15, the image can be directed downward as shown in FIGS. , More transfer material P
Can be stocked once.

[0042]

As described above, according to the present invention,
In an image forming apparatus equipped with a double-sided / multiplexing device and a curl removing device, a means for detecting image information, a means for detecting an image forming mode, a means for detecting a material type of a transfer material, and a detection output of each means. Since the control means for analyzing the transfer material is selectively controlled by the control means, the transfer of the transfer material to the double-sided / multiplexing device and the curl removing device can be controlled, and the sequence of the image forming mode can also be controlled. There is no occurrence of jams (jams), and therefore the transfer paper can be reliably used again.

Further, according to the present invention, an image is formed by holding the transfer material on the transfer material carrying member by an electrostatic attraction force or a gripper in a predetermined process, and then again on the back surface or the same surface of the same transfer material. An image forming apparatus that forms an image by the same process is provided with a unit for detecting the curl amount of the transfer material after fixing and a control unit for analyzing the detection output, and the control unit controls the electrostatic attraction force. Or, since the use of the gripper can be selectively controlled, it does not take time to form double-sided / multiple images on a plurality of small-sized transfer materials,
Work efficiency is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment.

FIG. 2 is a perspective view showing a configuration of a curl amount detection sensor portion in the embodiment.

FIG. 3 is a perspective view showing a procedure for measuring a curl amount of a transfer material.

FIG. 4 is a graph showing the relationship between the curl amount of the transfer material and the time after passing through the fixing device.

FIG. 5 is a graph showing the relationship between the curl amount of the transfer material and the toner amount.

FIG. 6 is a graph showing the relationship between the curl amount of the transfer material and the thickness of the transfer material.

FIG. 7 is a side view showing a state where the transfer material is placed on the intermediate tray with the image surface facing upward.

FIG. 8 is a side view showing a state in which the transfer material is placed on the intermediate tray with the image surface facing downward.

FIG. 9 is a side view showing a state where the transfer material is sandwiched between the intermediate tray and the pickup roller.

FIG. 10 is a perspective view showing a state where the gripper of the transfer drum is used.

FIG. 11 is a perspective view showing a state where electrostatic attraction of a transfer drum is used.

FIG. 12 is a perspective view showing a state where electrostatic attraction of a transfer drum is used.

FIG. 13 is a flowchart showing the operation of the embodiment.

FIG. 14 is a flowchart showing the operation of the embodiment.

FIG. 15 is a configuration diagram of an image forming apparatus according to an embodiment.

[Explanation of symbols]

 1 Document Feeding Device 3 Document Reading Device 4 Photosensitive Drum 7 Movable Developing Device P Transfer Material D Transfer Drum 11 Conveying Section 12 Fixing Device 14 Curl Removing Device 15 Intermediate Tray 23 Sorter 27 Reversing Flapper 28 Reversing Roller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03G 15/01 Y 114 B 15/16 H04N 1/29 G 9186-5C

Claims (6)

[Claims] 1. An image is formed by transferring a toner image formed on an image carrier by a predetermined process to a transfer material a plurality of times, and an image is again formed on the back surface or the same surface of the same transfer material by the same process. In an image forming apparatus having a double-sided / multiplexing device for forming and a curl removing device for curling the transfer material, a means for detecting image information, a means for detecting an image forming mode, and a material type for the transfer material are detected. Means and a control means for analyzing the detection output of each of these means, and the control means selectively controls the feeding of the transfer material to the double-sided / multiplexing device or the curl removing device, and the sequence of the image forming mode. An image forming apparatus characterized in that it is also controlled. 2. The image forming apparatus according to claim 1, wherein in the sequence of the image forming mode, the image information is reordered according to the amount of the image information. 3. The image forming apparatus according to claim 1, wherein in the sequence of the image forming mode, the number of transfer materials carried into the double-sided / multiplexing device and the curl removing device is changed. 4. The image forming apparatus according to claim 1, wherein, in the sequence of the image forming mode, the transfer material is rearranged by performing a correction control of the rearranged image information. 5. A transfer material carrying member is held in a predetermined process by an electrostatic attraction force or a gripper to form an image, and an image is formed again on the back surface or the same surface of the same transfer material by a similar process. In the image forming apparatus for forming, a means for detecting the curl amount of the transfer material after fixing and a control means for analyzing the detecting means are provided, and by the control means, when the transfer material is reused, the electrostatic An image forming apparatus characterized in that the suction force or the use of a gripper is selectively controlled. 6. The image forming apparatus according to claim 5, wherein the control by the control unit is changed again depending on whether the back side or the front side of the transfer material is used.