JP3466835B2 - Image forming device - 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 provided with curl correction means, and more particularly to control of a sheet material conveying speed of the curl correction means.

[0002]

2. Description of the Related Art Conventionally, electrophotographic recording systems have been widely used in image forming apparatuses such as copying machines and printers. Here, in this electrophotographic recording method, a latent image formed on an image carrier is developed to form a visible image, and this visible image (toner image) is transferred to a sheet material by electrostatic force, and then, An image is formed on the sheet material by fixing the transferred image by heat. Also, a double-sided image forming apparatus that forms an image on the other side (back side) of the sheet material on one side of which image formation is performed by the same operation as described above, and further, a color image is formed by mixing toners such as magenta, cyan, and yellow. A color image forming apparatus for forming is also proposed and implemented.

By the way, in such an image forming apparatus, when an image transferred onto a sheet material is fixed by a fixing device, the sheet material is warped (hereinafter referred to as curl) after being discharged. That is, when the unfixed toner image on the sheet material is heat-fixed by the fixing device including a pair of heat rollers,
When the sheet material is discharged and cooled, a difference occurs between the contraction rate of the sheet material and the contraction rate of the toner, so that the curl of the sheet material appears (generally, the image surface side is curled so as to be concave).

On the other hand, as a means for correcting such curl, as shown in FIG. 9, a pair of fixing rollers 101, 102.
Curling roller pair 10 on the downstream side of the sheet conveying direction
3, 104 are provided, and this curling roller pair 103, 1
No. 04, there is proposed a sheet material P configured to impart a reverse curl to correct the curl.

Here, the curling roller pair 103,
The upper curl roller 103 is made of a soft material such as sponge, and the lower curl roller 104 is used to impart a convex reverse curl to the sheet material P curled concavely on the image surface side. It is made of high hardness material. Then, by making the hard roller 104 bite into the soft roller 103, both rollers 103, 1
The curl of the sheet material P is corrected by passing the sheet material P through the nip formed by 04 and winding the sheet material P around the hard roller 104.

[0006]

However, in the image forming apparatus having such a configuration, since the upper curl roller 103 is made of silicon rubber, the silicone oil contained in the sheet material P is increased as the durability is improved. The upper curling roller 10 swells with toner or toner
The outer diameter of 3 changes to be thick.

As a result, the conveying speed of the sheet material P conveyed by the curling roller pair 103, 104 increases, and when the sheet material P is conveyed to the sorting apparatus for stacking it, the inlet roller pair and the curling roller pair of the sorting apparatus. 10
Between 3 and 104, a loop is formed by the outer diameter of the upper curl roller being thicker.

Due to this loop formation, the sheet material P has a habit or the entrance guide is brought into contact with the image surface,
Since scratches may occur, in the worst case, there is a problem that a jam occurs between the inlet roller pair and the curl roller pair 103 and 104, or conveyance failure occurs.

Therefore, the present invention has been made in order to solve such a conventional problem, and it is possible to convey the sheet material to the stacking and storing means without causing damages, scratches, conveyance defects, and the like. An object is to provide an image forming apparatus.

[0010]

SUMMARY OF THE INVENTION According to the present invention, an image is fixed between a fixing means for fixing an image transferred on a sheet material and a stack storing means for stacking and storing the sheet material on which the image is fixed. In an image forming apparatus provided with curl correction means for conveying the sheet material while correcting curl generated in the sheet material, the curl correction means is a soft roller body, and the image is fixed together with the soft roller body. And a hard roller body having a diameter smaller than that of the soft roller body for sandwiching and transporting the sheet material, and a control means for controlling the sheet material transport speed of the curl correction means according to the swelling of the soft roller body. It is characterized by that.

Further, according to the present invention, the deflection amount detecting means for detecting the deflection amount of the sheet material is provided between the curl correction means and the stacking and accommodating means, and the control means bends from the deflection amount detecting means. Based on the quantity signal, the sheet material conveying speed of the curl correction means is controlled to a speed at which the bending does not occur.

Further, according to the present invention, the control means determines the swelling amount of the soft roller body based on the table showing the relationship between the flexure amount and the diameter of the soft roller body and the flexure amount signal. Controlling the sheet material conveying speed of the curl correction means to a speed that does not cause the bending based on a table showing the relationship between the swelling amount of the soft roller body and the sheet material conveyance speed of the curl correction means. It is characterized by.

Further, according to the present invention, a counting means for counting the number of sheets of the sheet material corrected by the curl correction means is provided, and the control means and the curl correction means are stacked on the basis of a count signal from the counting means. It is characterized in that the sheet material conveying speed of the curl curl correction means is controlled to a speed at which the sheet material does not bend with the storage means.

According to the present invention, the control means determines the swelling amount of the soft roller body based on the count signal and a table showing the relationship between the number of straightened sheets and the diameter of the soft roller body, and Based on a table showing the relationship between the swelling amount of the soft roller body and the sheet material conveying speed of the curl correction means, it is possible to control the sheet material conveying speed of the curl correction means to a speed at which the bending does not occur. It is a feature.

Further, as in the present invention, between the fixing means and the loading / storing means, a soft roller body and a hard roller body having a diameter smaller than that of the soft roller body for sandwiching and carrying the sheet material on which the image is fixed together with the soft roller body. The curl correction means configured by and is arranged, and the sheet material is conveyed while correcting curl generated in the sheet material on which the image is fixed by the curl correction means. Further, while the bending amount detecting means for detecting the bending amount of the sheet material is provided between the curling correction means and the stacking and storing means, the control means controls the bending amount signal from the bending amount detecting means and the swelling amount of the soft roller body. Accordingly, the sheet material conveyance speed of the curl correction means is controlled to a speed that does not cause bending.

As in the present invention, the control means bends the sheet material conveying speed of the curl correction means in accordance with the count signal from the counting means for counting the number of corrections of the curl correction means and the swelling amount of the soft roller body. The speed is controlled so as not to cause.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an internal configuration of an image forming apparatus according to an embodiment of the present invention. In this embodiment, an electrophotographic copying machine is exemplified as the surface image forming device.

In the figure, A is an electrophotographic copying machine as an image forming apparatus. The electrophotographic copying machine A is provided with a color copying machine main body 1 capable of double-sided recording and an upper portion of the color copying machine main body 1. The automatic document feeder 2 is provided, and the sorting device 3, which is a stacking and storing means disposed on the sheet discharge side of the color copying machine main body 1 via a curl correction means described later, is provided.

Here, in the automatic document feeder 2, the sheet material such as the original document placed on the original document placing table 4 is sequentially separated from the lower side, and passes through the platen glass 5 of the copying machine body 1 through the path 6. The image is fed and the image is read by an optical reading system 7 composed of a CCD or the like of the copying machine main body 1, and after the reading is completed, the platen glass 5 is passed through a path 8 and the document placing table 4 is passed.
It is designed to be discharged to the top surface.

On the other hand, the copying machine main body 1 is provided with an image forming section 9 in which image forming stations 9M, 9Y, 9C and 9B corresponding to respective colors of magenta, yellow, cyan and black are arranged in a line. . The image forming stations 9M, 9Y, 9C and 9B are provided with the photosensitive drums 10a to 10d as the image bearing member and the photosensitive drum 10a for each color.
To 1Od as a process means that acts on the charger 1la
˜1 ld, developing devices 12 a to 12 d, cleaning device 13
It is configured by combining a to 13d and the like.

On the lower side of the image forming section 9, a belt conveying section 14 having transfer devices 14a to 14d for transferring an image (toner image) formed on each drum onto the sheet material P is arranged. It is set up. Further, on the upper side of the image forming section 9, there is provided a laser unit L as an image writing device that decomposes the image information read by the optical reading system 7 into each color component and exposes the photosensitive drums 10a to 10d respectively. ing.

A sheet material P is provided on the lower portion of the copying machine body 1.
The cassettes 15a and 15b in which are loaded and stored are mounted on the front side of the main body so as to be drawn out. This cassette 15a,
The sheet material P stored in 15b is appropriately picked up by the pickup rollers 16a and 16b and the separation roller pair 17a and 17b.
By the above, the sheets are separated and fed one by one from the uppermost one, fed to the registration roller pair 19 through a sheet feeding path composed of a plurality of conveyance roller pairs 18, etc., and fed to the image forming section 9 at a timing.

The sheet material P sent to the image forming section 9 is conveyed by the belt conveying section 14 in the direction of arrow a, and is conveyed by the known image forming process in each of the image forming stations 9M, 9Y, 9C and 9B. Photoconductor drum 10a
The images formed in 10d to 10d are sequentially transferred in an overlapping manner to form a multicolor image. The sheet material P on which the multicolor image is formed is sent to the fixing device 20 which is a fixing unit by the belt conveying unit 14, and the transferred image is thermally fixed.

On the other hand, 22 is a curl removing roller pair which is a curl correction means.
As shown in FIG. 2, the fixing device 20 and the sheet material P are arranged on the downstream side in the sheet conveying direction with respect to the branch path SR that guides the sheet material P to the discharge side or the re-feeding side. The branch path SR is provided with a switchable flapper 23 for restricting the traveling direction of the sheet material P to the discharge side or the re-feed side, and the discharge side of the flapper 23 further has a copying machine main body. A pair of transport rollers 24 that discharges and transports the sheet material P to the outside of the sheet 1 is disposed. As shown in FIG. 1, a pair of conveying rollers 25 and 26 and a pair of reversing conveying rollers 27 for inverting the front and back surfaces of the sheet material P and feeding the sheet material P to the intermediate tray 34 are disposed on the re-feeding side.

By the way, this curling roller pair 22
2, includes a soft roller 22a which is a soft roller body made of sponge and the like, and a hard roller 22b which is a hard roller body having a diameter smaller than that of the soft roller 22a. When the sheet material P is nipped and conveyed by the sheet 22b, the curl of the sheet material P is corrected.

Here, in the present embodiment, the soft roller 22a is arranged on the upper surface side of the sheet conveying path, and the hard roller 22b is arranged on the lower surface side thereof, so that a convex curl is applied to the sheet material P. Is configured. The smaller the diameter of the hard roller 22b, the higher the curl correction ability. For example, the soft roller 22a has an outer diameter of about 24 and a rubber hardness of 2
When the sponge roller is 5 ° (ASKARC), the hard roller 22b preferably has an outer diameter of φ12 or less, and more preferably an outer diameter of φ8 or φ6 enables proper curl correction.

In FIG. 2, reference numeral 50 denotes a curl removing and conveying roller pair, and the curl removing and conveying roller pair 50 is arranged between the curl removing roller pair 22 and the fixing roller 20 to remove the sheet material P from the curl removing roller. It is designed to be conveyed to the pair 22. In addition, the pair of curling and conveying rollers 5
0 is set to the same speed as the curl removing roller pair 22, and when the conveying speed of the curl removing roller 22 changes according to a signal on the main body side as described later, the conveying speed of the curl removing roller pair 50 is changed. Is changing as well.

Reference numeral 21 denotes an inlet roller of the sorting device 3, and the sheet material P decurled by the curl removing roller pair 22 is carried into the sorting device 3 by the inlet roller 21. .

By the way, in FIG. 2, the fixing device 20 and the curl removing roller pair 22 (the curl removing conveyance roller pair 50)
And the transport speed of the entrance roller 21 of the sorting apparatus 3 is as follows: V1, V2, V3
The setting is such that V1 = V2 = V3, which prevents the occurrence of a loop.

However, when the soft roller 22a of the pair of decurling rollers 22 swells due to durability, the outer diameter of the soft roller 22a becomes thicker as shown in FIG. 3, and as a result, the conveying speed becomes V2> V1 = V3. Become. Then, when the conveyance speeds become different as described above, between the curl removing roller pair 22 and the inlet roller 21 of the sorting device,
A loop L, which is a bend, is formed in the sheet material P.

Here, when the relationship between the loop amount of the sheet material P and the outer diameter of the curl removing roller pair 22 (soft roller 22a) is obtained by an experiment, the relationship is as shown in FIG. That is, the larger the roller diameter of the soft roller pair 22a, the larger the loop amount. Further, when the relationship between the roller diameter and the conveying speed V2 of the curl removing roller pair 22 is experimentally obtained, the relationship shown in FIG. 5 is obtained. That is, the larger the roller diameter of the roller pair 22a, the faster the conveyance speed. Further, when the relationship between the roller diameter and the optimum conveying speed of the curl removing roller pair 22 that does not cause a loop is obtained by an experiment, the relationship shown in FIG. 6 is obtained.

By the way, the loop amount is detected by the loop amount detecting sensor M provided in the vicinity of the sorting device inlet guide n (see FIG. 2). The loop amount detecting sensor M detects the loop amount. As shown in FIG. 1, a signal regarding the loop amount is input to a control device 51 which is a control means provided in the copying machine main body 1.

Here, the control device 51 has a table (see FIG. 4) showing the relationship between the loop amount and the outer diameter of the soft roller 22a in a memory part (not shown), the roller diameter and the conveying speed V2 of the curl removing roller pair 22. And a table (see FIG. 6) showing the relationship between the roller diameter and the optimum conveying speed of the curl removing roller pair 22 that does not cause a loop. Based on the table and the loop amount signal from the loop amount detecting sensor M, the optimum conveying speed of the curl removing roller pair 22 is obtained.

The optimum conveying speed thus obtained is fed back to the main body to set the speeds of the curl removing roller pair 22 and the curl removing conveying roller pair 50, so that the soft roller pair 22a does not swell. Therefore, it becomes possible to always control the optimum transport speed.

Next, the control device 51 having the above-mentioned configuration.
The transport speed control operation of will be described.

The sheet material P passing through the fixing device 20 is
The curl is corrected when passing through the pair of decurling rollers 22, and then is conveyed to the sorting device 3 through the inlet roller 21 of the sorting device. Here, the fixing device 2
0, conveyance speed V1, V2, V3 of the curl removing roller pair 22 (curl removing conveyance roller pair 50) and the entrance roller 21
2 is V1 = V2 = V3 as shown in FIG. 2, no loop occurs in the sheet material P. In addition,
When the loop does not occur in this way, the control device 51
Holds the conveying speed V2 of the curl removing roller pair 22 (curl removing conveying roller pair 50) in this state.

On the other hand, when the soft roller 22a of the curl removing roller pair 22 swells due to the durability, the outer diameter of the soft roller 22a becomes thicker as shown in FIG. 3, and as a result, the conveying speed becomes V2> V1 = V3. Become. Then, when the conveying speeds are different as described above, a loop L is formed between the curl removing roller pair 22 and the inlet roller 21.

When the loop amount detection sensor M detects the formation of the loop L and the loop amount signal is input, the control device 51 detects the loop amount signal and the loop amount stored in the memory section. A table showing the relationship between the outer diameter of the soft roller 22a, a table showing the relationship between the roller diameter and the carrying speed V2 of the curl removing roller pair 22, and an optimum carrying speed of the curl removing roller pair 22 that does not cause a loop with the roller diameter. Of the curl removing roller pair 2 based on the table showing the relationship between
The optimum transport speed of 2 is obtained.

Here, for example, when the loop amount L is determined to be 15 mm by the loop amount signal from the loop amount detecting means M, the control device 51 determines from FIG. 4 that the outer diameter of the soft roller 22a is 25 mm due to swelling. To do. further,
From FIG. 5, it is determined that the transport speed when the outer diameter of the soft roller 22a is 25 mm is increased to 1.04V2.

Further, from FIG. 6, when the outer diameter of the soft roller 22a is 25 mm, the optimum conveying speed is V2 = 0.96V2.
By feeding back this value to the main body 1 side and setting the conveyance speed of the curl removing roller pair 22 to 0.96 V2, stable conveyance without the loop amount L becomes possible.

As described above, the occurrence of the loop is suppressed by determining the swelling amount of the soft roller 22a based on the loop amount L and further determining the optimum conveying speed of the curl removing roller pair 22 based on the swelling amount. In the above, the configuration for obtaining the optimum transport speed from the relationship between the outer diameter of the soft roller 22a and the loop amount L has been described above, but the present invention is not limited to this, and for example, FIG. As shown, the optimum conveyance speed can be obtained based on a table showing the relationship between the number of durable sheets that is the number of corrections of the curl removing roller pair 22 and the outer diameter of the soft roller 22a.

That is, as shown in FIG. 8, a counter 52, which is a counting means, is provided on the main body 1 side to count the number of durable sheets, while the control device 51 shows the count information from the counter 52 and FIG. First, the outer diameter of the soft roller 22a is determined for each specific number of durable sheets based on the table showing the relationship between the number of durable sheets and the outer diameter of the soft roller 22a. Next, the outer diameter of the soft roller 22 thus obtained and the optimum conveyance speed at which the loop L is not formed are obtained from FIG.

Here, for example, when it is determined that the number of durable sheets to be passed is 75,000 based on the count information from the counter 52, the control device 51 determines that the outer diameter of the soft roller 22a is 25 mm.
Then, the optimum transport speed at this time is determined to be 0.96V2 from FIG. 6, and this value is fed back to the main body 1 side to set the transport speed of the curl removing roller pair 22 to 0.96V2. It enables stable transportation.

In the present embodiment, an electrophotographic copying machine is illustrated as an example of an image forming apparatus, but the present invention is not limited to this, and an image forming apparatus of another form, for example, a copying machine. And / or sheet feeding for feeding sheets such as manuscripts and recording sheets to printers, printers, facsimiles, etc.
Alternatively, it can be applied to a carrier device.

[0046]

As described above, according to the present invention, the amount of swelling of the soft roller body is obtained according to the amount of bending of the sheet material or the number of sheets to be corrected, and the curl correction means is provided based on the amount of swelling of the soft roller body. Since the sheet material conveying speed can be controlled to a speed that does not cause bending, it is possible to stably convey the sheet material. By carrying out the stable conveyance of the sheet material in this manner, the sheet material can be conveyed to the stacking and storing means without causing damage, scratches, conveyance failure, or the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an internal configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conveyance state of a sheet material when the conveyance speeds of a fixing device of the image forming apparatus, a curl removing roller pair, and an entrance roller of a sorting device are the same.

FIG. 3 is a diagram showing a state in which a loop is formed on a sheet material when the above-mentioned conveyance speeds are different.

FIG. 4 is a chart showing the relationship between the loop amount of the sheet material and the outer diameter of the soft roller.

FIG. 5 is a chart showing the relationship between the roller diameter and the conveyance speed of a curl removing roller pair.

FIG. 6 is a chart showing the relationship between the roller diameter and the optimum conveying speed of a curl removing roller pair that does not cause a loop.

FIG. 7 is a chart showing the relationship between the number of durable sheets and the outer diameter of a soft roller.

FIG. 8 is a diagram showing an internal configuration of an image forming apparatus according to another embodiment of the present invention.

FIG. 9 is a diagram showing a conventional fixing device and a curl removing roller pair.

[Explanation of symbols]

A Electrophotographic copying machine 3 Sorting device 20 Fixer 22 Curling roller pair 22a Soft roller 22a 22b hard roller 22b 21 Inlet roller of sorting device 51 control device 52 counter L loop M loop amount detection sensor P sheet material

Claims (5)

(57) [Claims] 1. A curling that occurs on the image-fixed sheet material between a fixing means for fixing the image transferred to the sheet material and a stacking storage means for stacking and storing the sheet material on which the image is fixed. An image forming apparatus provided with curl correction means for conveying the sheet material while correcting the sheet material, wherein the curl correction means sandwiches and conveys the soft roller body and the image-fixed sheet material together with the soft roller body. An image forming apparatus comprising a hard roller body having a diameter smaller than that of the soft roller body, and a control means for controlling the sheet material conveying speed of the curl correction means according to the swelling of the soft roller body. apparatus. 2. A flexure amount detecting means for detecting the flexure amount of the sheet material is provided between the curl correction means and the stacking and storing means, and the control means receives the flexure amount signal from the flexure amount detecting means. 3. The image forming apparatus according to claim 1, wherein the sheet material conveying speed of the curl correction means is controlled based on the speed so as not to cause the bending. 3. The control means determines a swelling amount of the soft roller body based on a table showing a relationship between the flexure amount and a diameter of the soft roller body and the flexure amount signal, and at the same time, the soft roller. The sheet material conveying speed of the curl correction means is controlled to a speed at which the bending does not occur based on a table showing the relationship between the swelling amount of the body and the sheet material conveyance speed of the curl correction means. Claim 2
The image forming apparatus described. 4. The counting means for counting the number of sheets of the sheet material corrected by the curl correction means is provided, and the control means, based on the count signal from the counting means, the curl correction means and the stacking and storing means. 2. The image forming apparatus according to claim 1, wherein the sheet material conveying speed of the curl curl correction unit is controlled to a speed that does not cause the sheet material to bend between them. 5. The control means determines the swelling amount of the soft roller body based on a table showing the relationship between the number of straightened sheets and the diameter of the soft roller body and the count signal, and the soft roller body. The sheet material conveying speed of the curl correction means is controlled to a speed at which the bending does not occur based on a table showing the relationship between the amount of swelling and the sheet material conveyance speed of the curl correction means. The image forming apparatus according to claim 4.