JP2010117470A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of contributing to measures for preventing recurrence of winding of transfer paper on a transfer carrier caused by insufficient margin immediately after transfer. <P>SOLUTION: When a retrying mode is carried out, a control circuit 35 carries out at least one or more modes out of an edge margin extending mode for forming a toner image by extending the margin on an edge side in a conveying-direction of the transfer paper, a toner applied amount reducing mode for forming a toner image by reducing at least a toner amount on a side near to an edge in a conveying-direction of the toner image formed on the transfer paper, a control temperature changing mode for carrying out fixing by lowering fixing temperature of a fixing carrier, and a separation member interval changing mode for carrying out fixing by narrowing an opposed interval of a separation member 31 oppositely arranged in non-contact with the fixing carrier. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a fixing device that fixes a toner image formed on the surface of a transfer paper while conveying the transfer paper through a nip.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine equipped with these functions, a toner image is formed on the surface of a transfer paper by an image forming unit, and then the transfer paper is conveyed through a nip. A pair of fixing conveyance bodies that fix the toner image formed on the surface of the transfer paper, and the fixing conveyance bodies are arranged before and after the transfer paper conveyance direction to detect the wrapping around the fixing conveyance body. And a re-image forming process for the toner image formed on the wound transfer paper after removing the rolled paper by manual operation of the user when the winding detection sensor detects the winding of the transfer paper. An image forming apparatus that executes a retry mode is known (for example, see Patent Document 1).

  Generally, on the downstream side of the fixing conveyance body in the transfer paper conveyance direction, a spatula shape (nail shape) is used to prevent the transfer paper from being wrapped around the fixing conveyance body due to melting and fixing of the toner image. Or a plate-like) separating member.

  On the other hand, this separation member is particularly suitable for color machines that require high speed and high image quality. If the tip of the separation member is brought into contact with the fixing carrier, the surface smoothness of the fixing carrier due to wear or the like may occur. Etc. have changed, and there has been a problem that glossiness, streaks, and the like are generated in the image after fixing.

  Therefore, in order to prevent such a problem as an image fixing defect, the separating member is arranged in a non-contact manner separated from the surface of the fixing conveyance body.

  At this time, 0.2 mm or more is required between the tip of the separation member and the surface of the transfer transfer body while maintaining separation performance and considering conditions such as paper dust biting and toner fusion. .

  Further, when the leading edge of the separation member and the surface of the transfer conveyance body are separated by 0.2 mm, a leading edge margin of a predetermined amount or more is formed between the leading edge of the transfer sheet in the conveyance direction and the transfer start edge of the toner image. (For example, about 3 mm) is required.

  However, such a setting of the leading edge margin causes a deviation between the image reading timing (image data processing timing) and the image writing timing due to, for example, a paper feed slip or the like or a bug in the program. In this case, if the leading edge margin is not ensured, there is a possibility that winding around the fixing conveyance body cannot be avoided.

  In particular, when the leading margin is not ensured due to a bug in the program or the like, there is a possibility that wrapping will occur again even if the retry mode is executed.

Furthermore, there is a technique for automatically changing subsequent image forming conditions so that similar jams do not occur repeatedly when image formation is performed again after removing jammed transfer paper. (For example, refer to Patent Document 1).
JP 2007-010852 A

  However, in the image forming apparatus configured as described above, defects in the transfer paper itself (for example, moisture-absorbing transfer paper and curls) as a jam factor that can be assumed in the image forming process of the image forming apparatus, and the conveyance path When the cause is a design defect, the transfer current value or the separation current value is changed as an image forming condition to be changed in order to avoid the occurrence of another jam. There has been a problem in that it is insufficient to prevent the recurrence of the wrapping around the transfer conveyance body.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus that can contribute to measures for preventing recurrence of wrapping around a transfer conveyance body due to lack of blank space after transfer.

  An image forming apparatus according to the present invention includes a pair of fixing conveyance bodies that fix a toner image formed on the surface of a transfer paper while nip-conveying the transfer paper, and the transfer paper arranged before and after the fixing conveyance body in the transfer paper conveyance direction. A winding detection sensor that detects winding around the fixing conveyance body by detecting the passage of the fixing paper, and when the winding detection sensor detects winding of the transfer paper, it is formed on the transfer paper wound after removal of the winding transfer paper And a control circuit for driving a retry mode for executing a re-image forming process of the toner image, and the control circuit executes the same image forming process when the retry mode is executed. As a wrapping factor release mode to eliminate the factors that would cause wrapping in this case, a toner image is formed by widening the margin on the leading end side in the transfer paper conveyance direction. Tip margin enlargement mode, toner image reduction mode for forming a toner image by reducing the toner amount at least near the tip in the transport direction of the toner image formed on the transfer paper, and fixing by fixing the fixing transport body at a lower temperature. At least one of a control temperature change mode to be executed, and a separation member interval change mode in which fixing is performed by narrowing the interval between the separation members that are arranged to face the fixing conveyance member in a non-contact manner. To do.

  At this time, when the control circuit detects the winding of the transfer paper again in spite of executing one or more of the winding factor canceling modes in the retry mode, the control circuit uses the other winding factor canceling modes together or independently. It is preferable to carry out.

  In addition, the control circuit, the winding factor release mode that is automatically selected in a preset priority order, or the winding factor release mode that is manually selected every time the winding detection sensor detects winding of the transfer paper, Can be executed.

  Further, in the separation member interval change mode in which the control circuit executes fixing by narrowing the facing interval of the separation member arranged to face the fixing conveyance body in a non-contact manner, the separation member is moved to the fixing conveyance body. You may make it contact. At this time, the separation member is brought into contact with the fixing conveyance body without causing damage.

  The image forming apparatus of the present invention can contribute to measures for preventing the recurrence of wrapping around the transfer conveyance body due to lack of margin immediately after transfer.

  Next, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a main part of the image forming apparatus according to an embodiment of the present invention, and FIG. 3 is according to an embodiment of the present invention. FIG. 4 is a flowchart of an example of automatic winding factor release mode setting control in a control circuit applied to an image forming apparatus, and FIG. 4 is a manual winding factor release mode setting control in a control circuit applied to an image forming apparatus according to an embodiment of the present invention. It is an example flowchart.

(External configuration of image forming apparatus 1)
Referring to FIG. 1, an image forming apparatus 1 according to an embodiment of the present invention includes an automatic document feeder (ADF) that is disposed at the top of an apparatus body 2 and used when reading a document as various functions of a copying machine, a facsimile, and a scanner. 3) and an operation unit 5 for setting / selecting various functions and the like in combination with a display screen 4 such as a liquid crystal monitor disposed on the upper front side of the apparatus main body 2.

  Note that the shape, configuration, function, and the like of the image forming apparatus 1 are not limited to those illustrated. Further, for example, it does not hinder the installation of known optional devices such as ADF 3 and sorter (not shown).

(Internal configuration of image forming apparatus 1)
In addition, the image forming apparatus 1 is disposed below the inside of the apparatus main body 2 so that it can be pulled out from the front of the apparatus main body 2, and a paper feed cassette 6 on which transfer paper (not shown) before printing is stacked and accommodated. In addition to the paper feed cassette 7, the transfer paper loaded and stored in the paper feed cassette 6 is separated and transported one by one from the uppermost one, and provided separately from the paper feed cassette 6 from the side wall surface of the apparatus body 2. A manual feed tray 8 on which transfer paper (not shown) can be stacked and stored, and a manual paper feed transport unit 9 for separating and transporting the transfer paper stacked and stored in the manual feed tray 8 from the top one by one. A paper feed transport unit 10 for transporting transfer paper loaded and stored in an optional paper feed cassette (not shown) installed on the bottom surface of the apparatus main body 2, and each paper feed transport unit 7, 9, 10 An image forming unit 11 for forming an image to be transferred to transfer paper conveyed from A secondary transfer unit 12 that transfers an image formed by the image forming unit 11 to a transfer sheet, and a transfer sheet that is arranged upstream of the secondary transfer unit 12 in the transfer sheet conveyance direction and is conveyed to the secondary transfer unit 12 Registration roller pair 13 for controlling the abutting alignment and conveyance timing, a fixing unit 14 for fixing the toner image after transfer onto the transfer paper, a discharge unit 15 for discharging the transferred transfer paper, and discharging from the discharge unit 15 A stacking unit 16 for stacking the transferred transfer paper after fixing and a reverse path 17 for switching back the transfer paper to the secondary transfer unit 12 when an image is formed on the back surface of the transfer paper are provided.

(Configuration of the image forming unit 11)
The image forming unit 11 irradiates a laser beam L based on image data of a document image read using the ADF 3 or image data included in print data transmitted from an external computer (not shown) or the like. A belt-like intermediate transfer member 19 and a plurality of image forming devices 20 arranged in a tandem manner below the intermediate transfer member 19.

(Intermediate transfer member 19)
The intermediate transfer member 19 is supported by being wound around a plurality of rollers, and is rotated in a predetermined direction by a driving device (not shown) (see an arrow in FIG. 1). The intermediate transfer member 19 is configured by an elastic belt in which a rubber layer is laminated on the surface of a base layer made of synthetic resin or the like.

(Image forming device 20)
The image forming devices 20 are arranged in a row in a tandem manner from the upstream side to the downstream side in the rotational movement direction so as to follow the rotational movement direction of the intermediate transfer body 19. The four image forming devices 20 are arranged in order of magenta, cyan, yellow, and black, for example, in order from the upstream side. These image forming devices 20 include toner containers 21 corresponding to the respective colors. Developer (toner) is replenished. Note that well-known devices are used for the image forming device 20 and the toner container 21, and the present invention is not limited to the illustrated example.

  Each image forming device 20 includes a photosensitive drum 22 on which an electrostatic latent image of a document image is formed by the laser light L irradiated by the exposure device 18, and toner is transferred from the electrostatic latent image to the photosensitive drum 22. The image is developed. Further, the toner image is primarily transferred onto the surface of the intermediate transfer member 19 by a primary transfer unit 23 provided above each image forming device 20. Then, the toner image of each image forming device 20 is transferred to the intermediate transfer body 19 at a predetermined timing by the rotational movement of the intermediate transfer body 19, so that the surface of the intermediate transfer body 19 has magenta A color toner image is formed by superimposing four color toner images of cyan, yellow, and black.

  On the other hand, the secondary transfer unit 12 includes a secondary transfer roller 24, and the color toner image formed on the surface of the intermediate transfer member 19 is transferred to the nip of the transfer paper accompanying the press contact between the intermediate transfer member 19 and the secondary transfer roller 24. The image is transferred onto the surface of the transfer paper by applying a transfer bias during conveyance.

  At this time, deposits such as unfixed toner remaining on the surface of the intermediate transfer member 19 after the secondary transfer are cleaned by the cleaning device 25 disposed on the side opposite to the secondary transfer unit 12.

(Fixing unit 14)
The fixing unit 14 fixes the unfixed toner image formed on the transfer paper by heating and pressurizing while transferring the transfer paper on which the unfixed toner image is formed in the secondary transfer unit 12 by nip. As shown in FIG. 2, the pressure roller 26, the fixing roller 28 disposed so as to face the pressure roller 26 through the endless fixing belt 27, and the fixing belt 27 are rotated together with the fixing roller 28. A heating roller 29, a heater 30 disposed inside the heating roller 29, and a separation member 31 in a non-contact arrangement spaced apart (for example, 0.2 mm) from the fixing belt 27 are provided. The separation member 31 forms a downstream transfer paper conveyance path (upper direction in the drawing) of the fixing unit 14 together with the panel member 32. Further, the fixing unit 14 is a transfer sensor as a wrapping detection sensor disposed in each of an upstream transfer paper conveyance path (downward in the drawing) that is an inlet of the fixing unit 14 and a downstream transfer paper conveyance path that is an outlet of the fixing unit 14. A paper detection sensor (fixing unit inlet sensor) 33 and a transfer paper detection sensor (fixing unit outlet sensor) 34 are provided. As the sensor type and detection method of the transfer paper detection sensors 33 and 34, known ones are employed.

(Configuration of fixing belt 27)
The fixing belt 27 is wound around the fixing roller 28 and the heating roller 29, and is rotated by the pressure roller 26 in the direction indicated by the arrow in the drawing. The fixing belt 27 is an endless belt such as a nickel thin plate, for example, and an outer peripheral surface is coated with an offset preventing agent such as a silicon rubber film.

(Configuration of rollers 26, 28, 29)
The fixing roller 28 and the pressure roller 26 are rubber rollers arranged to face each other, and the pressure roller 26 is pressed toward the center of the fixing roller 28 via the fixing belt 27 to form a nip portion. . The heating roller 29 applies tension to the fixing belt 27 and is formed of a cylindrical aluminum tube having a constant thickness in the axial direction. In addition, the fixing belt 27 is heated to the fixing temperature via the heating roller 29 by the heat generated by the heater 30 disposed inside the heating roller 29.

(Functions of the transfer paper detection sensors 33 and 34)
The transfer paper detection sensors 33 and 34 detect, for example, the leading end of the transfer paper that has been transported in the transport direction, and the detection result is output to the control circuit 35.

(Function of control circuit 35)
The control circuit 35 stores a control program related to the winding factor release mode control according to the present invention stored in the ROM 36. The ROM 36 stores various control programs related to the entire image forming process, and the control circuit 35 and the ROM 36 constitute a microcomputer that executes the winding factor release mode control according to the present invention.

  For example, the control circuit 35 detects that the transfer paper detection sensor 34 detects the leading edge of the transfer paper even if a predetermined time (for example, 0.5 seconds or more) elapses after the transfer paper detection sensor 33 detects the leading edge of the transfer paper. When there is no detection stone, it is determined that a wrapping JAM around the fixing belt 27 has occurred, and a retry mode is executed.

  Here, since the predetermined time described above is set by the transfer paper conveyance speed setting value and the separation distance between the transfer paper detection sensor 33 and the transfer paper detection sensor 34, the numerical value is not limited. For example, if the transfer paper conveyance speed is 150 mm / second and the distance between the transfer paper detection sensor 33 and the transfer paper detection sensor 34 is 50 mm, the predetermined time is about 0.33 seconds.

  Hereinafter, an example of the winding factor release mode control when the control circuit 35 executes the retry mode of the present invention will be described with reference to the flowchart of FIG.

(Step S1)
In step S1, the control circuit 35 monitors whether or not a winding JAM has occurred by detecting the leading edge of the transfer paper by the transfer paper detection sensors 33 and 34. If a winding JAM has occurred, the control circuit 35 proceeds to step S2. If no winding JAM has occurred, this routine is monitored as it is.

(Step S2)
In step S2, the control circuit 35 displays a known JAM notification on the display screen 4 and prompts the user to remove the JAM transfer paper when a wrapping JAM has occurred where the transfer paper has been wound around the fixing belt 27. After the JAM transfer paper is removed, among the wrapping factor release modes stored in the ROM 36 and prioritized in advance, the leading edge margin enlargement mode is executed. At the same time as performing a retry in which the margin is enlarged (for example, the 3 mm margin is changed to the 5 mm margin) by delaying the drive timing of the transport drive unit 37 to be driven and delaying the image formation timing (transfer timing) on the transfer paper. Then, the winding JAM generation counter 38 is counted up and the process proceeds to step S3.

(Step S3)
In step S3, the control circuit 35 monitors whether or not the wrapping JAM has occurred again on the transfer paper after retrying the margin that has been enlarged, even though the margin has been enlarged. If this is the case, the process proceeds to step S4. If no winding JAM has occurred, the process proceeds to step S9.

(Step S4)
In step S4, the control circuit 35 displays a known JAM notification on the display screen 4 and transfers the JAM to the user because the transfer paper has been wound around the fixing belt 27 again despite the enlargement of the margin. After the removal of the JAM transfer paper is urged to remove the paper, the toner amount reduction transfer mode of the image forming unit 11 is executed in the wrapping factor release mode stored in the ROM 36 and prioritized in advance. Is saved (for example, reduced by 30%), and a retry is executed in which the applied toner amount is reduced. At the same time, the winding JAM generation counter 38 is counted up and the process proceeds to step S3.

  The leading edge margin enlargement mode executed in step S2 may be canceled or used together. Further, the above-described toner save amount (30%) is such that when the winding boundary application amount is about 1.0 mg / cm, the maximum toner application amount is about 1.3 mg / cm. The expected toner save amount is set to about 30%, but this 30% is not a limited value and can be appropriately selected depending on the setting.

(Step S5)
In step S5, the control circuit 35 monitors whether or not the wrapping JAM has occurred again on the transfer paper after retrying the toner application amount, even though the toner application amount has been reduced. If this occurs again, the process proceeds to step S6. If no winding JAM has occurred, the process proceeds to step S9.

(Step S6)
In step S6, the control circuit 35 displays a known JAM notification on the display screen 4 to the user because the transfer paper has been wound around the fixing belt 27 again despite the toner applied amount being reduced. In order to prompt the removal of the JAM transfer paper and execute the control temperature change mode among the winding factor release modes stored in the ROM 36 and prioritized after the removal of the JAM transfer paper, the amount of heat generated by the heater 30 is reduced. At the same time as retrying with the fixing temperature decreased by saving (for example, decreasing by 10 ° C.), the winding JAM generation counter 38 is counted up and the process proceeds to step S7. At this time, the leading edge margin enlargement mode and the toner application amount reduction mode executed in steps S2 and S4 may be canceled or used together.

(Step S7)
In step S7, the control circuit 35 monitors whether or not the wrapping JAM has occurred again, even though the transfer paper after retrying the control temperature changing process has been subjected to the control temperature changing process. If this is the case, the process proceeds to step S8. If no winding JAM has occurred, the process proceeds to step S9.

(Step S8)
In step S8, the control circuit 35 displays a known JAM notification on the display screen 4 and transfers the JAM to the user because the transfer paper has been wound around the fixing belt 27 again despite the control temperature changing process. After the removal of the JAM transfer paper, the paper is urged to be removed, and the separation distance between the separation member 31 and the fixing belt 27 is approached (or contacted) in the winding factor release mode stored in the ROM 36 and prioritized in advance. In order to execute the separation member interval changing mode for this purpose, the separation member drive device 39 that changes the separation distance of the separation member 31 is driven to perform a retry with a reduced separation distance, and at the same time, the winding JAM occurrence counter 38 is counted. Up to step S7. At this time, the leading edge margin enlargement mode, the toner application amount reduction mode, and the control temperature change mode executed in steps S2, S4, and S6 may be canceled or used together.

(Step S9)
In step S9, the control circuit 35 detects whether or not the transfer paper at the nip portion has passed by detecting the rear end of the transfer paper by the transfer paper detection sensors 33 and 34. If the leading edge of the transfer paper is detected and no wrapping JAM has occurred, but the trailing edge of the transfer paper has not been detected, it is determined that JAM has occurred in a state where the transfer paper has not completely passed through the nip portion. For example, the wrapping factor release mode is checked according to the count of the wrapping JAM occurrence counter 38, and the retry mode is executed in the wrapping factor release mode at the corresponding step, and the paper passing is completed. If detected, the process proceeds to step S10.

(Step S10)
In step S10, assuming that the fixing is completed by executing the winding factor cancel mode, the control circuit 35 cancels the winding factor cancel mode and resets the winding JAM generation counter 38, and ends this routine. An image forming process is executed (or waited).

  Note that the priority order of the above-described winding factor release mode is arbitrary, and the order can be set / changed according to the user (business type, etc.).

  Further, the separation member driving device 39 for approaching (or contacting) the separation distance of the separation member 31 from the fixing belt 27 may approach or contact the fixing belt 27 by rotating the lower end of the separation member 31 in the figure. The fixing belt 27 may be moved closer to or in contact with the lower end of the separating member 31 in the figure.

  Furthermore, in the above-described embodiment, the description has been given of the case where the winding factor release mode that is ranked in advance by the program stored in the ROM 36 is changed (or used together) according to the count number of the winding JAM occurrence counter 38. As shown in FIG. 4, along with the occurrence of winding JAM (step S1), the JAM transfer paper is urged to be removed on the display screen 4 by a known JAM notification technique, and the winding factor release mode is set by the panel switch function of the display screen 4. In the case where the wrapping JAM occurs again (step S3), the wrapping factor release mode is selected again by the panel switch function of the display screen 4 (steps S2, S4). , S6, S8), and thereafter, the selection operation may be repeated until the winding JAM is released.

  At this time, for example, when the leading edge margin enlargement mode is selected, the leading edge margin is enlarged (for example, 3 mm → 5 mm → 7 mm → 10 mm) and the toner application amount reduction mode is selected for each repeated selection. Alternatively, the transfer toner amount of the image forming unit 11 may be saved (for example, 30% reduction → 50% reduction).

  In the above embodiment, the image forming apparatus of the present invention is applied to a full-color multifunction peripheral. However, for example, the image forming apparatus can be applied to all image forming apparatuses such as a monochrome multifunction peripheral and a single-color printer. Of course you can.

  The configuration of the fixing unit 14 can be applied to all known fixing structures such as a roller-roller system and a roller belt system.

1 is an explanatory diagram of an image forming apparatus according to an embodiment of the present invention. 1 is an explanatory diagram of a main part of an image forming apparatus according to an embodiment of the present invention. It is a flowchart of the example of automatic winding factor cancellation | release mode setting control in the control circuit applied to the image forming apparatus which concerns on one Embodiment of this invention. It is a flowchart of the example of manual winding factor cancellation | release mode setting control in the control circuit applied to the image forming apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

35 ... Control circuit 31 ... Separating member 26 ... Pressure roller (fixing carrier)
27. Fixing belt (fixing carrier)
28. Fixing roller (fixing carrier)
29 ... Heating roller (fixing carrier)
30 ... Heater (fixing carrier)
33. Transfer paper detection sensor (wrapping detection sensor)
34. Transfer paper detection sensor (wrapping detection sensor)

Claims (4)

A pair of fixing conveyance bodies for fixing a toner image formed on the transfer paper surface while conveying the transfer paper in a nip, and the fixing conveyance body arranged before and after the transfer paper conveyance direction to detect the passage of the transfer paper, A winding detection sensor for detecting winding around the fixing conveyance body, and re-image formation of a toner image formed on the winding transfer paper after removal of the winding transfer paper when the winding detection sensor detects winding of the transfer paper In an image forming apparatus comprising: a control circuit that drives a retry mode that executes processing;
When executing the retry mode, the control circuit performs a wrapping factor release mode for eliminating a factor that may cause wrapping when the same image forming process is performed. A margin expansion mode for forming a toner image by widening the margin of the toner, a toner amount reduction mode for forming a toner image by reducing a toner amount at least near the front end in the transport direction of the toner image formed on the transfer paper, the fixing A control temperature change mode in which fixing is performed by lowering the fixing temperature of the transport body, and a separation member interval change mode in which fixing is performed by narrowing the facing interval of the separating members arranged in a non-contact manner in contact with the fixing transport body, An image forming apparatus that executes at least one or more.   When the control circuit detects the winding of the transfer sheet again in spite of executing one or more of the wrapping factor canceling modes in the retry mode, the control circuit executes the other wrapping factor canceling modes in combination or independently. The image forming apparatus according to claim 1.   The control circuit executes the winding factor cancellation mode automatically selected in a preset priority order, or the winding factor cancellation mode manually selected every time the winding detection sensor detects winding of the transfer paper. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   In the separation member interval change mode in which the control circuit executes fixing by narrowing the facing interval of the separating member arranged in a non-contact manner in contact with the fixing conveyance body, the control circuit contacts the fixing member with the fixing conveyance body. The image forming apparatus according to claim 1, wherein the image forming apparatus includes:

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