JP2008083302A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming a good image at any time by preventing such apparatus-contamination that vapor generated from a previously formed image and composition forming the image stick to respective parts in the apparatus, in the case of additional-printing to form an image on a recording material on which the image is previously formed. <P>SOLUTION: In the additional printing mode, an air discharge means for discharging the air in the vicinity of the fixing device is operated under a control different from that in a normal mode, then, the vapor generated in the fixing device is sufficiently collected. Further, in the additional printing mode, the idle operation time of the fixing device is made longer, then, foreign substances sticking to a heating member and a pressurizing member are forcibly removed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including a fixing device that heats and fixes an image.

  In an electrophotographic image forming apparatus, a fixing device that fixes a toner image to a recording material by heating and melting is generally used. However, since the fixing temperature is high around 200 ° C., heat generated in the fixing device is used. As a result, various problems occur, and countermeasures are being taken.

  For example, in Patent Document 1, when the temperature of the paper discharge unit of the fixing device is lower than the fixing temperature, the curling of the recording material and the uneven gloss of the image may occur. It has been proposed to raise the temperature of the paper discharge unit before passing the recording material through the fixing device by stopping the exhaust or reducing the exhaust.

Japanese Patent Application Laid-Open No. 2004-228867 proposes preventing the fixing film from being damaged when the fixing film is driven at a high temperature by controlling the post-rotation time of the fixing device.
JP 2004-45611 A JP-A-7-248697

  An electrophotographic image forming apparatus has a feature that a selection range of a recording material on which an image is recorded is wide. In addition to plain paper, the image is recorded on thick paper such as coated paper, postcard, or OHP sheet. Can do.

  In recent years, along with the widespread use of color electrophotographic image forming apparatuses, images are additionally formed on recording materials on which images have been formed in advance, and new information is incorporated in the frame and background, or images on which one side has been printed in advance are recorded. Various information can be created by forming a double-sided image by forming an image on the other side of the material, or by changing part of the image depending on the layer, region, information provision time, etc. on the side where information is received The characteristics of an electrophotographic image forming apparatus with a wide selection range of recording materials are utilized to create a recording medium.

  In particular, it is used when address information is written on a preprinted sheet of information such as a sender, and such a method of using an electrophotographic image forming apparatus is called reprinting.

  In reprinting, an image is generally additionally formed by an electrophotographic image forming apparatus on a recording material on which an image has been formed in advance by plate-making printing using ink. In this case, the recording material is 200 ° C. in the fixing device. Due to the high-temperature processing before and after, volatile components contained in the printed image were evaporated, or the ink melted, causing problems.

  That is, the inside of the apparatus is contaminated by volatile components. Further, ink adheres to the fixing roller and the pressure roller.

  Due to contamination in the apparatus, the operation of the charging means becomes unstable, the charged potential of the photosensitive member rises, and white spots and carrier adhesion may occur.

  Further, vapor adheres to the conveying roller or the like and causes an image defect called oil stain. Further, the ink composition adheres and remains on the fixing roller and the pressure roller, and is transferred to a recording material and causes image smearing in later image formation.

  Conventionally, such problems have not been noticed, and these problems cannot be solved by conventional techniques including Patent Documents 1 and 2.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can prevent contamination in the apparatus during reprinting, solve problems such as image defects, and form high-quality images.

The object is achieved by the following invention.
1.
An image forming apparatus that forms an image on a recording material, a fixing device that fixes an image on the recording material, and an image forming apparatus that has an exhaust unit that discharges air around the fixing device to the outside of the apparatus.
An image forming apparatus comprising: a reprint information output unit that outputs reprint information; and an exhaust control unit that controls the exhaust unit based on an output of the reprint information output unit.
2.
2. The image forming apparatus according to 1, wherein the exhaust control unit controls the exhaust unit so as to increase an exhaust amount when the additional printing information output unit outputs additional printing information.
3.
The exhaust means has a first exhaust path for exhausting air around the fixing device and a second exhaust path for exhausting air around the fixing apparatus, and the exhaust control means is configured to perform the first exhaust in the normal mode. The exhaust unit is controlled so that air around the fixing device is discharged through a path, and air around the fixing device is discharged through the second exhaust path in the follow-up mode. The image forming apparatus described in 1.
4).
4. The image forming apparatus according to 3, wherein the second exhaust path includes a collecting unit that collects a substance evaporated in the fixing device.
5.
In an image forming apparatus for forming an image on a recording material and an image forming apparatus having a fixing device for fixing an image on the recording material,
An image forming apparatus comprising: a reprint information output unit that outputs reprint information; and a fixing control unit that controls an idle operation of the fixing device based on an output of the reprint information output unit.
6).
In the normal mode, the fixing control unit immediately stops the operation of the fixing device after discharging the last paper, and in the follow-up mode, controls the post-processing to stop the fixing device after operating for a predetermined time after discharging the last paper. 6. The image forming apparatus as described in 5 above, which is performed.
7).
The fixing control unit operates the fixing device for a predetermined time after discharging the last paper in the normal mode and the follow-up printing mode, and sets the operation time after discharging the last paper of the fixing device in the follow-up printing mode in the normal mode. 6. The image forming apparatus as described in 5 above, wherein post-processing is controlled to be longer than the operation time.
8).
The reprint information output means outputs reprint information when a reprint mode for forming an image on a recording material on which an image has been formed in advance by plate-making printing using ink is designated. The image forming apparatus according to claim 1.
9.
9. The image forming apparatus according to any one of 1 to 8, wherein the reprint information output unit includes an operation unit that accepts reprint designation by an operator.
10.
10. The image forming apparatus according to any one of 1 to 9, wherein the reprint information output unit includes a communication unit that receives a print command including designation of reprint from the outside.

  In the present invention, the steam generated around the fixing device is sucked stronger in the reprint mode than in the normal mode, or switched to the exhaust path having a higher ability to collect the steam, and is discharged in the reprint mode. Therefore, it is possible to satisfactorily prevent image quality defects and image stains caused by the generated steam, and to stably form high-quality images.

  Further, in the follow-up printing mode, it is possible to satisfactorily prevent image smear caused by the ink composition adhering to the fixing member or the pressure member.

  The present invention will be described below with reference to embodiments shown in the drawings, but the present invention is not limited to the embodiments.

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

  The image forming apparatus A is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-shaped intermediate transfer member 6, a sheet feeding device 20, and a fixing device 30. It is composed of

  Above the image forming apparatus A, an image reading device SC is installed. The document placed on the document table is scanned and exposed by the optical system of the document image scanning exposure device of the image reading device SC and read by the line image sensor. The analog signal photoelectrically converted by the line image sensor is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in the image processing unit, and then input to the optical writing means 3Y, 3M, 3C, 3K. Is done.

  An image forming apparatus 10 that forms an image on a recording material P includes image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer member 6, and a secondary transfer unit 9.

  An image forming unit 10Y that forms a yellow (Y) image includes a charging unit 2Y, an optical writing unit 3Y, a developing device 4Y, and a cleaning unit 5Y disposed around a photosensitive drum 1Y as an image carrier. . An image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a charging unit 2M, an optical writing unit 3M, a developing device 4M, and a cleaning unit 5M. An image forming unit 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image carrier, a charging unit 2C, an optical writing unit 3C, a developing device 4C, and a cleaning unit 5C. The image forming unit 10K that forms a black (K) image includes a photosensitive drum 1K as an image carrier, a charging unit 2K, an optical writing unit 3K, a developing device 4K, and a cleaning unit 5K.

  Reference numerals 4Y, 4M, 4C, and 4K denote developing devices that contain a two-component developer composed of a small particle size toner of yellow (Y), magenta (M), cyan (C), and black (K) and a carrier.

  The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred onto the rotating intermediate transfer body 6 by the primary transfer units 7Y, 7M, 7C, and 7K, and a combined color image is obtained. It is formed.

  The recording material P accommodated in the paper feeding cassette 21 of the paper feeding device 20 is fed by a paper feeding means (first paper feeding unit) 22, and is fed with paper feeding rollers 23, 24, 25, 26 and registration rollers (first rollers). (Second paper feed unit) 27 and the like, and conveyed to the secondary transfer means 9 to transfer the color image onto the recording material P.

  Note that the three-stage sheet feeding cassettes 21 arranged vertically in the vertical direction below the image forming apparatus A have substantially the same configuration. The three-stage sheet feeding means 22 has almost the same configuration. The sheet feeding cassette 21 and the sheet feeding means 22 are collectively referred to as a sheet feeding device 20.

  The recording material P to which the color image has been transferred is sandwiched by the fixing device 30 and the color toner image (or toner image) on the recording material P is fixed by applying heat and pressure to the recording material P. The sheet is fixed on the upper side, sandwiched between the sheet discharge rollers 28 and placed on a sheet discharge tray 29 outside the apparatus.

  On the other hand, after the color image is transferred to the recording material P by the secondary transfer means 9, the residual toner is removed by the cleaning means 8 from the intermediate transfer body 6 from which the recording material P is separated by curvature.

  In the description of the image forming apparatus A, the color image formation has been described. However, the present invention includes a case of forming a monochrome image.

  FIG. 2 is a diagram showing an exhaust control system according to Embodiment 1 of the present invention.

  Air around the fixing device 30 is exhausted outside the image forming apparatus by the exhaust means 40. The exhaust means includes a duct 41, a filter 43, and an exhaust fan 44. Air around the fixing device 30 is exhausted outside the apparatus by the fan motor exhaust fan 44 through the duct 41 and the filter 43. The air around the image forming apparatus 10 is exhausted outside the apparatus through the duct 42 and the filter 43 by the exhaust fan 44. In the image forming device 10, the scattered toner is removed particularly by exhausting air in the vicinity of the developing device.

  The control unit 100 as the exhaust control unit controls the image forming device 10 to form an image on the recording material, but receives information on a reprint mode for forming an image on the recording material on which an image is formed in advance, and exhausts the image. The rotational speed of the fan motor 45 that drives the fan 44 is controlled.

  Specifically, in the follow-up printing mode, control is performed so that the air flow rate of the exhaust fan 44 is several times that in the normal mode in which an image is formed on white paper.

  As a result, the vapor of the volatile component generated by heating the recording material carrying the printing ink in the fixing device 30 is almost completely sucked into the duct 41 and collected by the filter 43.

  Reprinting means forming an image on a recording material on which an image has been formed, and reprint information is output when a reprint mode is designated by the operator.

  In particular, it is preferable to designate a mode in which an image is formed on a recording material on which an image has been previously formed with ink by plate-making printing, as a reprint mode.

  The reprint information is output from the operation unit 101 or the communication unit 102 as a reprint information output unit. That is, the operation unit 101 is provided with a reprint button (not shown) for designating a reprint mode, and the operation unit 101 outputs reprint information when the operator operates the button.

  The communication unit 102 receives a print command including designation of a reprint mode from an external device such as a personal computer via the network, and outputs reprint information.

  In the normal mode, the control unit 100 rotates the fan motor 45 at a normal rotation speed, and exhausts air with a normal displacement.

  In the follow-up printing mode, the control means 100 increases the rotational speed of the fan motor 45 and exhausts with a larger exhaust amount than usual.

  FIG. 3 is a flowchart of such exhaust control.

  In STEP1, the control means 100 determines whether the normal mode or the follow-up printing mode. In the normal mode, the fan motor 45 is set to a normal rotation speed in STEP2A.

  In STEP 3, image formation is started, a set number of prints are performed (STEPs 4 and 5), and the end of image formation is executed (STEP 6). The start of image formation in STEP 3 includes exhaust for operating the fan motor 45, and the end of image formation in STEP 6 includes stop of the fan motor 45.

In the follow-up printing mode, the control unit 100 sets the fan motor 45 to a speed higher than that in the normal mode, exhausts air (STEP 2B), and executes from the start to the end of image formation in the same manner as in the normal mode (STEP 3 to STEP 6). ) After the end of image formation (STEP 6), the rotational speed of the fan motor 45 is returned to normal (STEP 7).
<Embodiment 2>
FIG. 4 is a diagram showing an exhaust control system according to Embodiment 2 of the present invention.

  In the present embodiment, the exhaust means 40 has a first exhaust path for exhausting air around the fixing device 30 in the normal mode and a second exhaust path for exhausting air around the fixing device 30 in the follow-up printing mode.

  The first exhaust path includes a duct 41A, a filter 43A, an exhaust fan 44A, and an exhaust fan motor 45A. A duct 42 that forms an exhaust path from the image forming apparatus 10 is connected to the duct 41A.

  The second exhaust path includes a duct 41B, a filter 43B, an exhaust fan 44B, and a fan motor 45B.

  The second exhaust path further has a collecting means including a trap 46 and a drain 47 formed in a labyrinth. The vapor evaporated from the print image of the recording material is separated from the exhaust in the trap 46, and the drain 47 To be collected.

  A valve 48 selects the first exhaust path or the second exhaust path.

  The control means 100 selects the first exhaust path in the normal mode, and selects the second exhaust path by operating the valve 48 in the follow-up printing mode.

  Reprint information is output from the operation unit 101 or the communication unit 102.

  FIG. 5 is a flowchart of exhaust control in the second embodiment.

  In STEP 1, it is determined whether the normal mode or the follow-up mode. If the normal mode is selected, the first exhaust path is selected in STEP 2 C.

  After STEP 2C, the process is the same as that of the first embodiment. In STEPs 3 to 6, the set number of sheets are printed, and the process ends.

  In the reprint mode, the second exhaust path is selected in STEP 2D, the number of prints set in STEP 3 to 6 are printed, and the exhaust path is returned from the second exhaust path to the first exhaust path in STEP 8. To do.

  Since the trap 46 and the drain 47 are provided in the second exhaust path, the vapor generated in the fixing device 3 is almost completely collected.

It is preferable that the output of the fan motor 45B is larger than the output of the fan motor 45A, so that the vapor evaporated from the image generated around the fixing device 30 is almost completely collected.
<Embodiment 3>
FIG. 6 shows a control system of control executed at the end of fixing in the third embodiment of the present invention, and FIG. 7 is a flowchart of fixing control in the third embodiment.

  The control means 100 as the fixing control means controls the motor 35 that rotationally drives the fixing roller 31 as follows.

  When the fixing of the set number of recording materials is completed, the control unit 100 stops the motor 35 and stops the rotation of the fixing roller 31.

  In the normal mode, the fixing of the set number of recording materials is completed, and the motor 35 is stopped when the recording material is discharged from the fixing device 30. However, in the reprint mode, the set number of recording materials is set. Even after the fixing to the motor is completed, the motor 35 is operated for a predetermined time.

  As a result, the fixing roller 31 and the pressure roller 32 rotate for a predetermined time. This rotation is an idling rotation that does not allow the recording material to pass through. By the idling rotation, the fixing roller 31 is cleaned by the cleaning device 34, and deposits on the peripheral surface of the fixing roller 31 are removed.

  Further, the deposit on the pressure roller 32 is also transferred to the fixing roller 31 and is removed by the cleaning 34 through the fixing roller 31, so that the surface of the pressure roller 32 is cleaned.

  In follow-up printing, a preprinted image is heated, so that a part of the composition such as ink forming the image adheres to the surface of the fixing roller 31, or from the fixing roller 31 to the pressure roller. 32 to adhere. Deposits on the fixing roller 31 and the pressure roller 32 adhere to the recording material and cause image smearing.

  Deposits on the fixing roller 31 and the pressure roller 32 are removed by the cleaning device 34 by the idling after the fixing process is completed, that is, the operation of rotating the fixing roller 31 and the pressure roller 32 without passing the recording material. The

  FIG. 7 is a flowchart of control in the present embodiment.

  In STEP 10, it is determined whether it is the normal mode or the overprinting mode. In the normal mode, in STEP 11A, image formation is started, and it is detected in STEP 13A that the set number of sheets have been printed.

  The detection in STEP 13A is performed by a signal that the paper discharge sensor 104 provided in the paper discharge unit of the fixing device 30 detects the passage of the trailing edge of the recording material.

  In STEP 14A, the fixing roller 31 is rotationally driven for 2 seconds after the completion of fixing and discharging to complete image formation (STEP 15A).

  When it is determined in STEP 1 that the reprint mode is selected, the same processing as STEP 11A, STEP 12A, STEP 13A, and STEP 15A is performed in STEP 11B, STEP 12B, STEP 13B, and STEP 15B, respectively.

  In STEP 14B, a process of idling the fixing roller 31 for 10 seconds longer than that in the normal mode is executed.

  As a result, as described above, the surfaces of the fixing roller 31 and the pressure roller 32 are sufficiently cleaned so that foreign matters such as ink can be removed.

  In the above-described example, the fixing roller 31 and the pressure roller 32 are idled in the normal mode and the idling time is extended in the follow-up printing mode. In the printing mode, it may be configured to idle.

  The embodiment is a fixing device using a fixing roller and a heating roller. However, the belt is used as a heating member or a pressure member, and after the fixing process is completed, post-processing is performed in which the belt is idled and reprinted. It is also possible to lengthen the post-processing time in the mode.

  In the example described above, the foreign matter adhering to the heating member or the pressure member is removed by the post-processing executed after the image formation is completed. However, the foreign matter may be removed in the pre-processing. .

  In other words, as a pre-processing for image formation, the fixing roller and the pressure roller can be idled to remove foreign matter adhering during reprinting. In a configuration in which foreign matter is removed by such preprocessing, information on the job immediately before the job to be executed is stored, and when the immediately preceding job is performed in the overprinting mode, before the next job is executed. Further, as a pretreatment, the fixing roller is heated to melt the deposits on the roller surface, and is rotated idly to remove foreign matters on the roller surface.

<Example 1>
The exhaust system shown in FIG. 2 was used to measure the exhaust capacity of the exhaust fan by the wind speed immediately downstream of the fan. As shown in Table 1, the wind speed was 1 m / sec in the normal mode and 3 m / sec in the reprint mode. did.
<Comparative Example 1>
In Comparative Example 1, the wind speed was 1 m / sec in both the normal mode and the follow-up printing mode.
<Comparative example 2>
In Comparative Example 2, the wind speed was 3 m / sec in both the normal mode and the follow-up printing mode.

  Using A3 size paper, 5 kp (5000 sheets) image formation was performed in a normal mode in which an image was formed on white paper, and then 5 kp reprinting using the paper carrying the image was repeated.

  In Example 1, a print with less power consumption and no oil stain was obtained through 200 kp, but in Comparative Example 1, oil stain was generated from 100 kp.

  The oil stain is a phenomenon in which oil adheres to the recording material to form a stain, and it is considered that the vapor adhering to the conveying roller or the like is transferred to and adhered to the recording material.

  In Comparative Example 2, there was no oil stain, but the power consumption was large.

  Table 2 shows the results of evaluation of white spots in the image.

  White spots are a phenomenon in which white spots appear in the form of vertical bands. As a result of the vapor adhering to the scorotron, which is a charging means, the controllability of the grid is lowered, charging becomes unstable, and the charging potential of the photosensitive member is increased. It is believed that there is.

  As shown in Table 2, in Comparative Example 1, white spots occurred from 50 kp. In Comparative Example 2, there was no white spot, but the power consumption was large.

  Note 1 in Tables 1 and 2 indicates that the filter was replaced.

In Example 1, prints were obtained with good power up to 200 kp with low power consumption.
<Example 2>
The exhaust system shown in FIG. 3 was used, the first exhaust path was used in the normal mode, and the second exhaust path was used in the follow-up mode.

The wind speed in the first exhaust path was 1 m / sec, and the wind speed in the second exhaust path was 3 m / sec.
<Comparative Example 3>
In both the normal mode and the follow-up printing mode, the first exhaust path was used, and the wind speed downstream of the fan was set to 1 m / sec.

  As shown in Table 3, in Example 2, there was no occurrence of oil stains and white spots up to 200 kp, and there was no clogging of the filter, but in Comparative Example 3, oil stains occurred after 100 kp, and at 50 kp. Occurrence of white spots and clogging of the filter occurred after 150 kp.

<Example 3>
Using A3 size paper, the 5 kp follow-up mode and the 5 kp normal mode were repeated, and at the end of each mode, the image forming process was terminated and post-rotation was performed.

The post-rotation time was 10 seconds after the follow-up mode and 2 seconds after the normal mode.
<Comparative Example 4>
In Comparative Example 4, post-rotation was performed for 2 seconds both at the end of the follow-up printing mode and at the end of the normal mode.

  As shown in Table 4, in the example, image smear did not occur and good prints were obtained, but in the comparative example, image smudge occurred.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the exhaust control system in Embodiment 1 of this invention. It is a flowchart of the exhaust control in Embodiment 1 of this invention. It is a figure which shows the exhaust control system in Embodiment 2 of this invention. 6 is a flowchart of exhaust control in the second embodiment. It is a figure which shows the control system of the control implemented at the time of completion | finish of fixing in this Embodiment 3 of this invention. 10 is a flowchart of fixing control in the third embodiment.

Explanation of symbols

30 Fixing device 40 Exhaust means 41, 41A, 41B, 42 Duct 43, 43A, 43B Filter 44, 44A, 44B Fan 45, 45A, 45B Fan motor 46 Trap 47 Drain 48 Valve

Claims (10)

An image forming apparatus that forms an image on a recording material, a fixing device that fixes an image on the recording material, and an image forming apparatus that has an exhaust unit that discharges air around the fixing device to the outside of the apparatus.
An image forming apparatus comprising: a reprint information output unit that outputs reprint information; and an exhaust control unit that controls the exhaust unit based on an output of the reprint information output unit. The image forming apparatus according to claim 1, wherein the exhaust control unit controls the exhaust unit to increase an exhaust amount when the reprint information output unit outputs reprint information. The exhaust means has a first exhaust path for exhausting air around the fixing device and a second exhaust path for exhausting air around the fixing apparatus, and the exhaust control means is configured to perform the first exhaust in the normal mode. The exhaust means is controlled so that air around the fixing device is exhausted via a path, and air around the fixing device is exhausted via the second exhaust path in a follow-up printing mode. The image forming apparatus according to 1. The image forming apparatus according to claim 3, wherein the second exhaust path includes a collecting unit that collects a substance evaporated in the fixing device. In an image forming apparatus for forming an image on a recording material and an image forming apparatus having a fixing device for fixing an image on the recording material,
An image forming apparatus comprising: a reprint information output unit that outputs reprint information; and a fixing control unit that controls an idle operation of the fixing device based on an output of the reprint information output unit. In the normal mode, the fixing control unit immediately stops the operation of the fixing device after discharging the last paper, and in the follow-up mode, controls the post-processing to stop the fixing device after operating for a predetermined time after discharging the last paper. The image forming apparatus according to claim 5, wherein the image forming apparatus is performed. The fixing control unit operates the fixing device for a predetermined time after discharging the last paper in the normal mode and the follow-up printing mode, and sets the operation time after discharging the last paper of the fixing device in the follow-up printing mode in the normal mode. 6. The image forming apparatus according to claim 5, wherein post-processing is controlled to be longer than the operation time. The reprint information output unit outputs reprint information when a reprint mode for forming an image on a recording material on which an image has been formed in advance by plate-making printing using ink is designated. The image forming apparatus according to any one of 1 to 7. The image forming apparatus according to claim 1, wherein the reprint information output unit includes an operation unit that accepts reprint designation by an operator. The image forming apparatus according to claim 1, wherein the reprint information output unit includes a communication unit that receives a print command including a reprint designation from the outside.

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