JP4882874B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce output of an unnecessary sheet, wherein an image is inclined by bend of the sheet, and to prevent outbreak of the unnecessary stop time in an image forming device. <P>SOLUTION: When a bend detecting sensor 61 detects bend of a sheet S, supply of the sheet S by a feeding roller 21 is stopped, and while conveyance of sheets, which are already supplied from a sheet housing portion 20 and left in a conveyance path between the sheet housing portion 20 and the detecting sensor 61, is continued. Based on a result of the detection by the bend detecting sensor 61 relative to the left sheets, any one of the operation for re-starting supply of the sheets S with the feeding roller 20 and the operation for stopping the image forming device 1 is carried out. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a sheet.

  Image forming apparatuses such as copiers, printers, and facsimile machines are installed in many offices, and there is a demand from users for higher speed and higher image quality.

  In order to satisfy the user's request, it is important to properly convey the sheet in the image forming apparatus. For example, if the sheet is bent and conveyed in the image forming apparatus, an inclined image is formed on the sheet. This is disadvantageous for the user. In consideration of this point, various techniques for properly conveying the sheet have been proposed. However, the sheet may be bent and conveyed due to a sudden external factor, a defect in a conveying component, or the like. Therefore, conventionally, there has been proposed a technique in a case where bending occurs in the conveyed sheet.

In the technique described in Patent Document 1, paper bending is detected by a paper bending detection unit, and control for stopping the operation of the image forming apparatus is performed based on the detection signal, or the image forming operation is continued and the paper is bent. This is a technique for discharging the generated recording paper to different paper discharge trays.
JP 2002-36281 A

  However, when the cause of paper bending is a sudden external factor, it is unlikely that paper bending will occur continuously on the recording paper, so the image forming apparatus is stopped as in the technique described in Patent Document 1. If this happens, an unnecessary stop time is generated, which is not preferable from the viewpoint of productivity.

  On the other hand, when the cause of the paper bending is a mechanical factor in the image forming apparatus such as a defect in the conveying part, there is a high possibility that the paper is continuously bent. If the image forming operation is continued, unnecessary recording paper is output, which is not preferable.

  Accordingly, an object of the present invention is to provide an image forming apparatus that performs an appropriate operation according to the frequency of occurrence of bending in a sheet.

In order to achieve the above object, an image forming apparatus according to the present invention includes:
An image forming apparatus for forming an image on a sheet,
A sheet accommodating portion for accommodating the sheet;
A sheet feeding unit for feeding sheets from the sheet storage unit;
Receiving the sheets fed by the sheet feeding unit, and the resist conveyance unit for conveying the sheet to the images forming unit at a predetermined timing,
And the image forming unit for forming an image on a sheet conveyed by the registration conveyor section,
A bending detection sensor for detecting the bending of the sheet conveyed by the resist conveyance unit;
A control unit for controlling the operation in the image forming apparatus;
Have
The controller is
When the bending of the sheet is detected by the bending detection sensor, the feeding of the sheet by the sheet feeding unit is stopped, and the conveyance path between the sheet storage unit and the bending detection sensor after feeding from the sheet storage unit is stopped. The remaining sheet is continuously conveyed, and the sheet feeding unit resumes feeding or stops the operation of the image forming apparatus based on the detection result of the bending detection sensor for the remaining sheet. Or any one of the operations is executed by the image forming apparatus.

  According to the image forming apparatus of the present invention, since it is determined whether or not to continue the image forming operation on the sheet based on the occurrence frequency of the bending of the sheet, it is possible to reduce the output of unnecessary sheets and to generate unnecessary stop time. Can be prevented.

  FIG. 1 is a central sectional view showing the internal configuration of the image forming apparatus 1.

  The image processing apparatus 1 is a tandem color image forming apparatus having an intermediate transfer belt 50.

  The document set on the document feeder a of the double-sided document automatic feeder 10 is conveyed toward the image reading unit 30 by various rollers.

  The image forming apparatus 1 has a plurality of sheet storage portions 20 at the bottom. An image forming unit 40 and an intermediate transfer belt 50 are installed above the sheet storage unit 20, and an image reading unit 30 is installed in the upper part of the apparatus main body.

  The sheet storage unit 20 can be pulled out to the front side of the apparatus (the front side in FIG. 1). Sheets S such as white paper are accommodated in the plurality of sheet accommodating portions 20 according to size. The sheets S stored in the sheet storage unit 20 are fed one by one by a sheet feeding roller 21 that functions as a sheet feeding unit. Further, special paper such as an OHP sheet is set in the manual feed portion 22.

  The image forming unit 40 includes four sets of image forming engines 400Y, 400M, 400C, and 400K for forming toner images of Y, M, C, and K colors. The image forming engines 400Y, 400M, 400C, and 400K are arranged linearly from top to bottom in this order, and have the same configuration. The configuration of the image forming engine 400Y for yellow will be described as an example. The image forming engine 400Y includes a photoreceptor 410 that rotates counterclockwise, a scorotron charging unit 420, an exposure unit 430, and a developing unit 440.

  The cleaning unit 450 is disposed to include a region facing the lowermost part of the photoconductor 410.

  The intermediate transfer belt 50 located at the center of the apparatus main body is endless and has a predetermined volume resistivity. The primary transfer electrode 510 is installed at a position facing the photoconductor 410 with the intermediate transfer belt 50 interposed therebetween.

  Next, an image forming method for forming a color image will be described.

  The photoconductor 410 is driven to rotate by a main motor (not shown), and is negatively charged by the discharge of the scorotron charging unit 420 (for example, −800 V). Next, the exposure unit 430 performs optical writing according to image information on the photoconductor 410 to form an electrostatic latent image. When the formed electrostatic latent image passes through the developing unit 440, the negatively charged toner in the developing unit adheres to the portion of the latent image by application of the negative developing bias, and the toner image is formed on the photoreceptor 410. It is formed. The formed toner image is transferred to the intermediate transfer belt 50 that is pressure-bonded to the photoreceptor 410. The toner remaining on the photoreceptor 410 after the transfer is cleaned by the cleaning unit 450.

  A toner image formed by each of the image forming engines 400Y, 400M, 400C, and 400K is transferred onto the intermediate transfer belt 50 so that a color image is formed on the intermediate transfer belt 50. The sheets S are fed one by one by the sheet storage unit 20 and conveyed to the position of a registration roller 60 that functions as a registration conveyance unit. The sheet S is abutted against the registration roller 60 and stops once, and the bending of the sheet S is corrected. The sheet S is fed from the registration roller 60 at a timing when the toner image on the intermediate transfer belt 50 coincides with the image position.

  The sheet S fed by the registration roller 60 is guided by a guide plate and fed to a transfer nip position (image forming position) formed by the intermediate transfer belt 50 and the transfer unit 70. The transfer unit 70 constituted by rollers presses the sheet S toward the intermediate transfer belt 50. By applying a bias (for example, +500 V) having a polarity opposite to that of the toner to the transfer unit 70, the toner image on the intermediate transfer belt 50 is transferred to the sheet S by the action of electrostatic force. The sheet S is neutralized by a separation device (not shown) including a static elimination needle, separated from the intermediate transfer belt 50, and sent to a fixing unit 80 including a roller pair of a heating roller and a pressure roller. As a result, the toner image is fixed to the sheet S, and the image-formed sheet S is discharged out of the apparatus.

  Note that the image forming apparatus 1 in this embodiment forms a color image on a sheet by electrophotography, but the image forming apparatus according to the present invention is not limited to this embodiment, and forms a monochrome image. Of course, the image forming apparatus may be any image forming system other than the electrophotographic system, such as an ink jet system, a thermal transfer system, and a silver salt photographic system.

  FIG. 2 is a block diagram of a control system of the image forming apparatus 1, and only representative ones are shown here.

  A CPU (Central Processing Unit) 101 is connected to a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like via a system bus 107. The CPU 101 reads out various programs stored in the ROM 102, develops them in the RAM 103, and controls the operation of each unit. Further, the CPU 101 executes various processes according to the program expanded in the RAM 103, stores the processing results in the RAM 103 and displays them on the operation display unit 105. Then, the processing result stored in the RAM 103 is stored in a predetermined storage destination. In this embodiment, the CPU 101 constitutes a control unit by cooperating with the ROM 102 and the RAM 103.

  The ROM 102 stores programs, data, and the like in advance, and typically includes a semiconductor memory.

  The RAM 103 forms a work area for temporarily storing data processed by various programs executed by the CPU 101.

  The HDD 104 has a function of storing image data of a manuscript image obtained by reading by the image reading unit 30 and storing output image data and the like. It has a structure in which a plurality of metal disks coated or vapor-deposited with a magnetic material are stacked at regular intervals, and this is rotated at high speed by a motor to read and write data by bringing the magnetic head closer.

  The operation display unit 105 enables various settings. The operation display unit 105 has, for example, a touch panel format, and conditions relating to color printing and monochrome printing are set by the user inputting through the operation display unit 105. Various kinds of information such as network setting information are displayed on the operation display unit 105.

  The image reading unit 30 optically reads a document image and converts it into an electrical signal. When reading a color original, image data having luminance information of 10 bits for each of RGB per pixel is generated.

  Image data generated by the image reading unit 30 and image data transmitted from a PC connected to the image forming apparatus 1 are subjected to image processing by the image processing unit 106. When color printing is executed by the image forming apparatus 1, R (Red), G (Green), and B (Blue) image data generated by the image reading unit 106 or the like is input to a color conversion LUT in the image processing unit 106. , R, G, B data is color-converted into Y (Yellow), M (Magenta), C (Cyan), Bk (Black) image data. Then, tone reproduction characteristics are corrected for the color-converted image data, screen processing such as halftone dots is performed with reference to the density correction LUT, and edge processing for emphasizing fine lines is performed. .

  The image forming unit 40 receives the image data processed by the image processing unit 106 and forms an image on a sheet.

  The sheet feeding roller 21, the sheet feeding roller 60, and the bending detection sensor 61 related to the conveyance of the sheet S are connected to the CPU 101 and the like via the system bus 107. The CPU 101 reads a predetermined program stored in the ROM 102 and develops it in the RAM 103 to control the operation of the paper feed roller 21 and the like.

  FIG. 3 is an enlarged view showing a conveyance path from the sheet storage unit 20 to the transfer nip position.

  The sheet S stored in the sheet storage unit 20 is fed by a sheet feeding roller 21. The sheet S fed by the paper feed roller 21 is conveyed through the conveyance path 24 by a plurality of conveyance rollers (sheet conveyance units) 23 and stops at the registration roller 60 once.

  Since the sheet S stops once at the registration roller 60, the bending of the sheet S generated up to the registration roller 60 is eliminated at the registration roller 60.

  In order to form a toner image on the sheet S, the sheet S is conveyed from the registration roller 60 at a predetermined timing. A bending detection sensor 61 is installed on the downstream side of the registration roller 60 in the sheet conveyance direction. Whether or not the sheet S conveyed from the registration roller 60 is bent is detected based on the posture of the sheet S passing through the bending detection sensor 61. This point will be described in detail with reference to FIG.

  FIG. 4 is a plan view of the periphery of the registration roller 60 as viewed from above.

  The sheet S is conveyed in the X direction by the registration roller 60 and is conveyed to a transfer nip position T indicated by a broken line.

  The bending detection sensor 61 located on the downstream side of the registration roller 60 in the sheet conveyance direction is composed of two sensors, for example, an optical sensor including a light emitting element and a light receiving element. The two sensors constituting the bending detection sensor 61 are installed at an equal distance from the registration roller 60.

  As shown in FIG. 4A, when the sheet S conveyed from the registration roller 60 is not bent, the passage timing of the sheet S detected by the two sensors is almost the same. However, as shown in FIG. 4B, when the sheet S conveyed from the registration roller 60 is bent, the passage timing of the sheet S detected by the two sensors is different. Therefore, when the passage timing of the sheet S detected by the two sensors is detected and the passage timing is different for a predetermined time or more, it is determined that the sheet S conveyed by the registration roller 60 is bent.

  If the sheet S conveyed by the registration roller S is bent as shown in FIG. 4B, the sheet S is bent and enters the transfer nip position T, and the image formed on the sheet S is inclined. It becomes a problem.

  By the way, there are various causes of the bending occurring in the sheet S, and there are mechanical factors in the image forming apparatus 1 such as a sudden external factor and a defect in the registration roller 60. When the generation factor of the sheet S bend is a sudden external factor, the possibility of the sheet bend continuously is low. On the other hand, when the cause of the bending of the sheet S is a mechanical factor in the image forming apparatus 1 such as a defect of the registration roller 60, there is a high possibility that the sheet is continuously bent.

  Therefore, considering the factor of the bending that occurs in the sheet S, an appropriate operation is executed according to the frequency of the bending in the sheet S. Hereinafter, this operation will be described in detail with reference to FIGS.

  FIG. 5 is a flowchart showing an operation in the image forming apparatus 1 when the bending of the sheet S is detected.

  First, when execution of a print job is started in the image forming apparatus 1 (step S1), the bending detection sensor 61 detects whether or not the sheet conveyed from the registration roller 60 is bent (step S2).

  If the sheet is not bent (step S2; No), it is determined whether or not the print job is completed (step S3), and the operations of steps S2 and S3 are repeated unless the print job is completed.

  On the other hand, when the sheet is bent (step S2; Yes), the sheet feeding roller 21 is temporarily stopped (step S4) so that a new sheet is not fed from the sheet storage unit 20. This point will be described in detail with reference to FIG.

  FIG. 6 is an explanatory diagram that linearly shows a conveyance path from the sheet storage unit 20 to the bending detection sensor 61.

  Since there is a certain distance from the sheet storage unit 20 to the bending detection sensor 61, a plurality of sheets are present in the conveyance path when performing continuous printing. In the example shown in FIG. 6, there are three sheets S <b> 1 to S <b> 3 already fed from the sheet storage unit 20, and the sheets S <b> 1 to S <b> 3 are conveyed in the Y direction.

  The operation of step S4 in FIG. 5 will be described with reference to FIG. 6. When the bending detection sensor 61 detects the bending of the leading sheet S1, the sheet feeding roller 21 is temporarily stopped so that the subsequent sheet S4 is not fed. To. In this way, it is possible to prevent the continuously bent sheets from being fed.

  In the example shown in FIG. 6, even if the sheet feeding roller 21 is temporarily stopped, two sheets (S2; S2, S3) Since the sheet exists, the conveyance of these remaining sheets is continued and the image forming operation is executed. Therefore, the bending detection sensor 61 detects the bending of the remaining sheet, and based on the result, determines whether or not to resume the operation of the paper feed roller 21, that is, whether or not to continue the image forming operation in the image forming apparatus 1. To do. This point will be described in detail after step S5 in FIG.

  After the operation of the paper feed roller 21 is temporarily stopped in step S4, it is detected in step S5 whether or not the next sheet remaining in the conveyance path is bent by the bending detection sensor 61. In the example of FIG. 6, first, it is detected whether or not bending has occurred with respect to the remaining sheet S2.

  When the remaining sheet is not bent (step S5; No), the first detected sheet (sheet S1 in FIG. 6) is caused by a sudden external factor and is continuously detected. Therefore, it is determined that the sheet is not likely to be bent, and the operation of the sheet feeding roller 21 is resumed (step S6), and a new sheet is fed from the sheet storage unit 20. In this way, unnecessary stop time of the image forming apparatus 1 can be prevented and productivity can be ensured.

  On the other hand, if the remaining remaining sheet has been bent (step S5; Yes), it is detected that the sheet has been continuously bent, and the bending of the sheet is detected without restarting the operation of the sheet feeding roller 21. It is determined whether the finished sheet is the last sheet among the remaining sheets (step S7).

  If the sheet from which the bend is detected is not the final sheet (step S7; No), since there is still a remaining sheet, it is detected whether or not the bend has occurred with respect to another remaining sheet (step S5). In the example of FIG. 6, the remaining sheet includes the sheet S3 in addition to the sheet S2. Therefore, since the sheet S2 is not the final sheet among the remaining sheets, the bending detection sensor 61 detects whether or not the sheet S3 is bent.

  When it is determined that the sheet in which the bending is detected is the final sheet (step S7; Yes), since the sheet is continuously bent including the remaining sheet, the cause of the sheet bending is an image. It can be determined that this is a mechanical factor in the forming apparatus 1. Therefore, since there is a high possibility that the sheet will be bent continuously, the operation of the image forming apparatus is stopped (step S8), and a warning message such as “sheet bending has occurred” is displayed on the operation display unit 105. (Step S9). If the operation of the image forming apparatus is stopped in this way, unnecessary sheet output can be reduced.

  As described above with reference to FIGS. 5 and 6, the sheet bending is detected by the sheet feeding roller temporarily detected based on the detection result after detecting the sheet bending first after detecting the sheet bending. If it is determined whether or not to resume the paper, unnecessary sheet feeding can be reduced and unnecessary stop time can be prevented.

  In addition, this invention is not limited to the said embodiment, Even if there exists a change and addition in the range which does not deviate from the summary of this invention, it is contained in this invention.

FIG. 2 is a central sectional view showing an internal configuration of the image forming apparatus. 2 is a block diagram of a control system of the image forming apparatus. FIG. FIG. 4 is an enlarged view showing a conveyance path from a sheet storage unit 20 to a transfer nip position. It is the top view which looked at the registration roller 60 periphery from upper direction. FIG. 10 is a flowchart illustrating an operation in the image forming apparatus when sheet bending is detected. It is explanatory drawing which showed the conveyance path | route from a sheet | seat accommodating part to a bending | flexion detection sensor linearly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 20 Sheet accommodating part 21 Paper feed roller 23 Conveyance roller 24 Conveyance path 30 Image reading part 40 Image forming part 60 Registration roller 61 Bending detection sensor 101 CPU
102 ROM
103 RAM
104 HDD

Claims (2)

An image forming apparatus for forming an image on a sheet,
A sheet accommodating portion for accommodating the sheet;
A sheet feeding unit for feeding sheets from the sheet storage unit;
Receiving the sheets fed by the sheet feeding unit, and the resist conveyance unit for conveying the sheet to the images forming unit at a predetermined timing,
And the image forming unit for forming an image on a sheet conveyed by the registration conveyor section,
A bending detection sensor for detecting the bending of the sheet conveyed by the resist conveyance unit;
A control unit for controlling the operation in the image forming apparatus;
Have
The controller is
When the bending of the sheet is detected by the bending detection sensor, the feeding of the sheet by the sheet feeding unit is stopped, and the conveyance path between the sheet storage unit and the bending detection sensor after feeding from the sheet storage unit is stopped. The remaining sheet is continuously conveyed, and the sheet feeding unit resumes feeding or stops the operation of the image forming apparatus based on the detection result of the bending detection sensor for the remaining sheet. Or an image forming apparatus that causes the image forming apparatus to perform any one of the operations. The controller is
In the remaining sheet conveyed to the bend detection sensor next to the sheet in which the bend is detected, when the bend is not detected by the bend detection sensor, the sheet feeding unit resumes feeding the sheet,
2. The image forming apparatus according to claim 1, wherein in all the remaining sheets, when the bending is detected by the bending detection sensor, the operation of the entire image forming apparatus is stopped.

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