JP6137447B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a fixing device that fixes an image on a sheet.

In an image forming apparatus such as a copying machine, a printer, or a multifunction machine, a toner image is formed on a photoconductor provided in an image forming unit based on image data obtained by reading from a document reading device, and the toner Printing is performed by transferring an image onto a sheet fed from a tray and further fixing the image. Further, the sheet on which the image is formed on the front side can be reversed and conveyed by a reversing conveyance unit if desired, and can be recirculated to the sheet conveyance unit, whereby image formation and fixing can be performed on the back side.
The fixing device passes the paper through a fixing roller, a pressure belt, etc., and fixes the toner image on the paper by heating, pressing, etc., but the paper as it is formed is conveyed to the fixing device. Therefore, over time, the fixing member such as the fixing roller and the pressure belt may be soiled with toner, or the toner may adhere to the fixing member due to a paper jam. When a new sheet is passed through the fixing device, the toner on the fixing member adheres to the sheet and becomes dirty, thereby impairing product quality. For this reason, it has been proposed to clean the fixing device by passing blank paper through the fixing device (see Patent Documents 1 and 2).

In Patent Document 1, when performing blank paper cleaning after a jam, the degree of dirt on the fixing device is determined from the printing rate at the time of jam occurrence and the position of the jam paper, and the necessity of blank paper passage, the number of sheets to be passed, etc. are automatically determined. This makes it possible to perform appropriate blank sheet cleaning with the minimum number of sheets.
In Patent Document 2, the cleaning operation of the fixing device is performed by performing a blank sheet passing when a certain number of output sheets is reached and when designated in the serviceman mode.

JP 2007-65328 A Japanese Patent Laid-Open No. 2003-149979

  In both Patent Documents 1 and 2, the fouling of the fixing device is predicted, and cleaning is performed based on the prediction. However, in actual operation, toner adhesion to the fixing member varies and may not be as expected. For this reason, it is not guaranteed that the cleaning will be performed at the right time and in the right amount. In fact, the product will become dirty due to lack of cleaning, or the product will be excessively cleaned and the production efficiency will be reduced. There is a problem of doing.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide an image forming apparatus capable of accurately grasping stains due to toner adhesion on a fixing device.

That is, among the image forming apparatuses of the present invention, the first aspect of the present invention is:
An image forming unit for forming a toner image on paper;
A fixing device for fixing the toner image on the paper to be passed;
A detection unit for detecting toner adhesion on paper conveyed through the fixing unit;
A control unit for controlling the image forming apparatus,
The control unit is configured to receive a detection result of the detection unit and determine a stain state of the paper that has passed through the fixing device based on the detection result.
When the job includes a blank page, during the actual output operation of the job, a detection result obtained by detecting the toner adhesion by the detection unit in order to determine the contamination state only for the blank page after fixing is received, and based on the detection result. Judge the paper smudge status,
When the detected toner adhesion amount is equal to or greater than a predetermined value, it is determined that the cleaning process of the fixing device is necessary. When the detected toner adhesion amount is less than the predetermined value, it is determined that the cleaning process is not necessary. And
When it is determined that the fixing device needs to be cleaned, the main output operation of the job is interrupted and the fixing device cleaning process is started.
This output operation is continued when it is determined that the cleaning process is not necessary.

In the image forming apparatus according to the second aspect of the present invention, in the first aspect of the present invention , the control unit determines that the cleaning process of the fixing device is necessary by determining the contamination state of the paper during the cleaning process. If the cleaning process is continued and it is determined that the cleaning process is not necessary, the output operation is restarted .
Third image forming apparatus of the present invention, the first or second Oite the present invention, the control unit is provided with a function of notifying the detection result and / or the state of soiling of the toner adhering to the user It is characterized by.

The image forming apparatus according to a fourth aspect of the present invention is characterized in that, in the third aspect of the present invention, the control unit enables a user to perform the cleaning instruction operation together with the notification.

In the image forming apparatus according to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, the control unit performs the notification when the toner adhesion amount or the dirt state exceeds a predetermined reference. Features.

An image forming apparatus according to a sixth aspect of the present invention includes the paper reversing device capable of reversing the front and back of the paper that has passed through the fixing device in any one of the first to fifth aspects of the present invention,
The control unit reverses the paper on which toner adhesion has been detected by the detection unit using the paper reversing device, and enables detection of toner adhesion on the back side of the paper by the detection unit.

The image forming apparatus according to a seventh aspect of the present invention is the image forming apparatus according to any one of the first to sixth aspects, wherein the control unit cleans the fixing device with a predetermined amount and then the toner adhesion by the detection unit. The detection is performed.

An image forming apparatus according to an eighth aspect of the present invention is the image forming apparatus according to any one of the first to seventh aspects, wherein the cleaning process is performed by passing a blank sheet through the fixing device.

The image forming apparatus according to a ninth aspect of the present invention is the image forming apparatus according to the eighth aspect , wherein the controller cleans the fixing unit from the length of the sheet passing direction of the blank sheet in the cleaning process of the fixing unit with blank sheet. The number of times is calculated, and when the number of times of cleaning is a plurality of times, the toner adhesion is detected by the detection unit for the paper portion corresponding to the final cleaning.

  That is, according to the present invention, it is possible to accurately grasp the contamination of the paper due to the toner adhering to the paper that has passed through the fixing device. Further, it is possible to appropriately determine the start of cleaning and the end of cleaning based on the dirt.

1 is a diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention. Similarly, it is a figure which shows a control block. Similarly, it is a figure which shows the example of a screen at the time of Jam generation. Similarly, it is a flowchart showing a cleaning processing procedure when a jam occurs. Similarly, it is a figure which shows the example of a cleaning inquiry screen after Jam cancellation | release. Similarly, it is a figure which shows the example of a paper feed tray selection screen at the time of cleaning. Similarly, it is a figure which shows the example of an operation | movement screen at the time of cleaning. Similarly, it is a figure which shows the timing of the toner adhesion detection at the time of job execution. Similarly, it is a flowchart illustrating a procedure of toner adhesion detection and cleaning processing during job execution. Similarly, it is a diagram showing a cleaning state with blank paper and a position of toner adhesion detection on the paper. Similarly, it is a figure which shows the outline of the image forming apparatus in other embodiment. Similarly, it is a flowchart illustrating a procedure of toner adhesion detection and cleaning processing on the front and back sides of a sheet. Similarly, it is a flowchart showing a procedure for performing selection of execution of the cleaning process. Similarly, it is a figure which shows the implementation selection screen which performs selection of implementation of a cleaning process.

Hereinafter, an image forming apparatus 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings.
In the image forming apparatus 1, as shown in FIG. 1, an image forming apparatus main body 10 that performs image formation and fixing, a relay apparatus main body 20, and a post-processing apparatus main body 30 are connected in series.
In the present invention, the connection configuration of the image forming apparatus is not limited to this, and it may be configured only by the image forming apparatus main body. Further, a fixing device may be provided outside the image forming apparatus main body 10.

The image forming apparatus main body 10 is provided with an automatic document feeder (ADF) 14 on the upper side, and a document fed by the automatic document feeder (ADF) 14 is scanned by a scanner unit 130 shown in FIG. Image reading is possible. The document can be read on a platen glass (not shown).
In addition, an LCD 141 is installed on the upper side of the image forming apparatus main body 10 or the relay apparatus main body 20 where the platen glass is not located. The LCD 141 is configured by a touch panel, and can be operated by an operator and information can be displayed. The LCD 141 serves as both an operation unit and a display unit. The operation unit may be configured with a mouse, a tablet, or the like, and may be configured separately from the display unit. The LCD 141 may be movable.

A plurality of paper feed trays 12 (two stages in the drawing) are arranged on the lower side of the image forming apparatus main body 10.
In the image forming apparatus main body 10, a transport path 13 for transporting paper fed from any one of the paper feed trays 12 is provided, and the image forming unit 11 is disposed in the middle of the transport path in the image forming apparatus main body 10. Is provided. The image forming unit 11 includes a photoconductor 11a, a charger, an LD, a developing device, and a transfer unit (not shown) arranged around the photoconductor 11a. Further, a fixing device 15 is disposed in the conveyance path 13 on the downstream side of the photoconductor 11a.
On the downstream side of the fixing device 15, the conveyance path 13 extends and is connected to the conveyance path 23 of the relay apparatus main body 20, and the conveyance path 13 branches on the downstream side of the fixing device 15 to form an image. A reverse conveyance path 16 that joins the conveyance path 13 on the upstream side of the section 11 is provided. The reversing conveyance path 16 is provided with a reversing unit 17 for reversing the paper. The sheet reversed by the reversing unit 17 can be conveyed to the conveyance path 13 on the upstream side of the image forming unit 11 through the reversal conveyance path 16, and the sheet reversed by switching the path is arranged on the downstream side of the fixing unit 15. It can also be returned to the transport path 13 and transported to the relay device main body 20 as it is.

In the image forming unit 11, the charger uniformly charges the surface of the photoconductor 11a before image writing, and the LD irradiates the photoconductor 11a with the surface uniformly charged by irradiating a semiconductor laser. An electrostatic latent image is formed on the surface. The developing device develops the electrostatic latent image formed on the photoconductor 11a by the LD with the toner member. By this development processing, a toner image is formed on the photoreceptor 11a. The transfer unit transfers the toner image on the photoconductor 11 a onto the paper conveyed from the paper feed tray 12. The sheet onto which the toner image has been transferred is separated from the photoreceptor 11a and conveyed to the fixing device 15. The toner member remaining on the photoconductor 11a is removed by a cleaning unit (not shown).
The fixing device 15 fixes the toner image transferred to the front side of the sheet by heating the conveyed sheet. The sheet subjected to the fixing process is transported to the relay apparatus main body 20 by the transport path 13 or is reversed by the reversing unit 17 through the reverse transport path 16 and then transported on the upstream side of the image forming unit 11. The The paper that has been turned upside down can be image-formed on the back side. The reverse conveyance path 16 and the reverse unit 17 correspond to the paper reverse device of the present invention.

  The relay apparatus main body 20 has a transfer path 23 connected to the transfer path 13 and connected to the post-processing apparatus main body 30 of the subsequent stage. The transport path 23 includes a stack unit 21 that can stack a predetermined number of sheets transported along the transport path 23. The sheets stacked in the stack unit 21 can be transported to the post-processing apparatus main body 30 side at a predetermined timing, and the sheets are stacked on the post-processing apparatus main body 30 side through the transport path 23 without stacking the sheets on the stack unit 21. Paper can also be conveyed. In addition, an inline sensor 25 that detects a toner image on the surface of the paper transported through the transport path 23 is disposed on the transport path 23 on the upstream side of the stack unit 21. The in-line sensor 25 can detect a toner image with a length corresponding to the maximum width of the paper, and can use a CCD or CMOS array. The inline sensor 25 corresponds to the detection unit of the present invention.

  The post-processing main body 30 performs predetermined post-processing such as superposition / inversion, folding, saddle stitching, and the like. The post-processing main body 30 includes a post-processing unit (not shown) corresponding to the predetermined post-processing, and predetermined post-processing is performed by the post-processing unit on paper conveyed from the relay apparatus main body 20 according to the post-processing setting. Done. If post-processing execution is not set, the paper can be discharged to the paper discharge unit 31 without performing post-processing.

Next, the functional configuration of the image forming apparatus 1 will be described with reference to FIG.
The image forming apparatus main body 10 includes a control block 110, a scanner unit 130, an operation unit 140, and a printer unit 150, and further processes image data input from an external device 40 such as a terminal PC through the LAN 3, or a scanner. An image processing unit (print & scanner controller) 160 that enables image data obtained by the unit 130 to be transferred to the external device 40 through the LAN 3 is provided.

  The control block unit 110 has a PCI bus 112 connected to an image processing unit (print & scanner controller) 160, and a DRAM control IC 111 is connected to the PCI bus 112. An image memory (DRAM) 120 is connected to the DRAM control IC 111. The image memory (DRAM) 120 has a compression memory 121 for storing compressed image data and a page memory 122 for temporarily storing uncompressed image data to be printed before image formation. .

In addition, an HDD 119 (hard disk) is connected to the PCI bus 112 via a controller IC 118, and the HDD 119 is connected to image data acquired by the scanner unit 130 and an image processing unit (print & scanner controller) 160. The image data generated by the external device 40 is stored.
The image data acquired by the image processing unit (print & scanner controller) 160 and the image data stored in the HDD 119 are transmitted to the DRAM control IC 111 through the PCI bus 112 along with the printing operation.

The control block unit 110 includes a control CPU 113, and a DRAM control IC 111 is connected to the control CPU 113.
The control CPU 113 is connected to a non-volatile memory 115 composed of a flash memory or the like. In the nonvolatile memory 115, initial print setting information of the image forming apparatus main body 10, machine setting information such as process control parameters, initial data of output settings, a prescribed value of a toner image serving as a threshold value when cleaning the fixing device, A program and the like for operating the control CPU 113 are stored.

The control CPU 113 can read nonvolatile data in the nonvolatile memory 115 and can write desired data in the nonvolatile memory 115.
The control CPU 113 controls the operation of each unit of the image forming apparatus main body 10 in accordance with the machine setting information, print setting information, output settings, and the like.
The control CPU 113 constitutes a control unit of the present invention together with the nonvolatile memory 115 and the like, and controls the entire image forming apparatus 1.
The control CPU 113 can perform job output settings and operation instructions through the operation unit 140.

The scanner unit 130 includes a CCD 131 that performs optical reading and a scanner control unit 132 that controls the entire scanner unit 130. The scanner control unit 132 is connected to the control CPU 113 so that serial communication is possible. The CCD 131 is connected to a reading processing unit 116 that processes image data read by the CCD 131, and the reading processing unit 116 is connected to a DRAM control IC 111 via a compression / decompression IC 117 in a controllable manner.
The reading processing unit 116 performs various processing such as analog signal processing, A / D (Analog to Digital) conversion processing, shading processing, and the like on the analog image signal input from the CCD 131 to generate digital image data, and compress / Output to the decompression IC 117.
The scanner unit 130 reads an image of a document placed on the upper platen of the image forming apparatus main body 10 or a document automatically conveyed by the ADF 14 (document feeder).

The operation unit 140 includes an LCD 141 configured as a touch panel that serves as both a display unit and an operation unit, and an operation unit control unit 142 that controls the entire operation unit. The operation unit control unit 142 performs serial communication with the control CPU 113. Connected as possible.
In the operation unit 140, under the control of the control CPU 113, input of machine settings such as output condition setting and operation control condition in the image forming apparatus body 10 and setting of paper information (size, paper type) of each paper feed tray are performed by the LCD 141. Input, display of setting contents, display of desired information such as a message, etc., and further operation instructions, setting input, and display related to cleaning of the fixing device 15 can be performed.

The DRAM control IC 111 is connected to a compression / decompression IC 117 that compresses and decompresses image data. The DRAM control IC 111 controls the compression process of the image data and the decompression process of the compressed image data by the compression / decompression IC 117 in accordance with an instruction from the control CPU 113 and controls the input / output of the image data to the image memory (DRAM) 120. .
The write processing unit 123 is connected to the image forming unit 11 including the LD 152 of the printer unit 150 and the like, and generates write data used for the operation of the LD 152 based on the image data.

The printer unit 150 includes the image forming unit 11, a paper feed tray 12, a conveyance path 13, a reverse conveyance path 16, a fixing device 15, and the like.
In addition, the printer unit 150 includes a printer control unit 151 that controls the entire printer unit 150 (paper feeding, image formation, paper discharge, post-processing, and the like). The printer control unit 151 performs serial communication with the control CPU 113 described above. Connected as possible. The printer control unit 151 operates according to a control command from the control CPU 113 to control the printer unit 150 to perform paper conveyance, image formation, and the like.

  Further, the DRAM control IC 161 of the image processing unit (print & scanner controller) 160 is connected to the PCI bus 112 to which the DRAM control IC 111 is connected as described above. When the image forming apparatus main body 10 is used as a network printer or a network scanner, the image processing unit (print & scanner controller) 160 receives image data or the like from the external device 40 connected to the LAN 3 by the image forming apparatus main body 10. Or the image data acquired by the scanner unit 130 is transmitted to an external device 40 connected to the LAN 3 or the like.

  In the image processing unit (print & scanner controller) 160, an image memory 162 composed of a DRAM or the like is connected to the DRAM control IC 161. Further, in the image processing unit (print & scanner controller) 160, a DRAM control IC 161 and a controller control unit 163 for controlling the entire image processing unit (print & scanner controller) 160, a LAN control unit 164, and a LAN interface 165 are provided on a common bus. Is connected. The LAN interface 165 is connected to the LAN 3.

  Further, the control CPU 113 is connected to the inline sensor control unit 25a of the inline sensor 25 disposed in the relay apparatus main body 20 so as to be controllable, and the control CPU 113 can control the operation of the inline sensor 25. The control CPU 113 can receive the detection result in the inline sensor 25. The inline sensor 25 is controlled by the inline sensor 25a.

Next, the basic operation of the image forming apparatus 1 will be described.
First, a procedure for accumulating image data in the image forming apparatus main body 10 will be described. In the image forming apparatus main body 10, a case where the scanner unit 130 reads an image and generates image data will be described. The scanner unit 130 optically reads an image from a document by the CCD 131. At this time, the operation of the CCD 131 is controlled by the scanner control unit 132 that receives a command from the control CPU 113. The document reading may be performed while automatically feeding the document by the automatic document feeder (ADF) 14 or may be performed by placing the document on the platen glass.

  The control CPU 113 operates according to a program and issues a command to the scanner unit 130 based on an operation (reading instruction or copy instruction) by the operation unit 140. The image read by the CCD 131 is subjected to data processing by the reading processing unit 116, and the image data subjected to the data processing is sent to the compression / expansion IC 117 via the DRAM control IC 111 and compressed by a predetermined method. The compressed data is stored in the image memory (DRAM) 120 via the DRAM control IC 111. When storing the data in the HDD 119, the data once stored in the compression memory 121 is sent to the HDD 119 via the DRAM control IC 111 and the controller IC 118.

  In addition, the image data is input to the image forming apparatus main body 10 via the LAN 3. Examples of the image data include data generated by an application program such as the external device 40. The method for generating image data is not particularly limited. The data is received by the image processing unit (print & scanner controller) 160 via the LAN 3 and the LAN interface 165, and is temporarily stored in the image memory 162 by the DRAM control IC 161. Data stored in the image memory 162 is transferred to the DRAM control IC 111 via the PCI bus 112 and temporarily stored in the page memory 122. Data stored in the page memory 122 is sent to the compression / decompression IC 117 via the DRAM control IC 111, subjected to compression processing, and stored in the compression memory 121 via the DRAM control IC 111. When storing the data in the HDD 119, the data once stored in the compression memory 121 is sent to the HDD 119 via the DRAM control IC 111 and the controller IC 118.

  When the image data is stored, output settings are made before or after storing the image data. The output setting can be performed by an operation input by an operator by displaying a setting screen on which operation input is possible on the operation unit 140. Further, when the output setting item is selected in the initial setting and the setting input by the operator is not made, the output setting is made by the initial setting.

  When the image forming apparatus 1 outputs an image, that is, when used as a copying machine or a printer, the image data stored in the compression memory 121 is sent to the compression / decompression IC 117 via the DRAM control IC 111 to decompress the data. The expanded data is sent to the writing processing unit 123, and writing is performed by the LD 152 on the photosensitive member 11a charged by the charging unit. When image data stored in the HDD 119 is used, the image data stored in the HDD 119 is temporarily stored in the compression memory 121 via the DRAM control IC 111, and the image data stored in the compression memory 121 is DRAM-controlled. The data is decompressed by sending it to the compression / decompression IC 117 via the IC 111, and the decompressed data is sent to the write processing unit 123 in the same manner as described above.

In the printer unit 150, each unit is controlled by the printer control unit 151 that receives a command from the control CPU 113. In the image forming unit 11, the latent image written on the photoconductor 11 a is developed as a toner image by a developing unit (not shown), and the toner image is transferred to a sheet supplied by a conveyance path 13 by a transfer unit (not shown). Is fixed. In the photoreceptor 11a, after the toner image is transferred onto the paper, the residual toner is removed by a cleaning unit (not shown).
In this embodiment, the description has been given on the assumption of monochrome image formation. However, the image forming apparatus main body may be provided with a photoconductor for each color (for example, cyan, magenta, yellow, and black). .
The sheet on which the image has been formed is conveyed to the relay device 20 via the conveyance path 13, reversed by the reversing unit 17 of the reverse conveyance path 16, and conveyed to the relay apparatus main body 20 via the conveyance path 13, or reversed conveyance. It is transported along the path 16 and circulated to the transport path 13. The sheet circulated to the transport path 13 is subjected to image formation and fixing on the back side, and is transported to the relay apparatus main body 20 through the transport path 13.

  In the relay apparatus main body 20, the toner image on the surface of the sheet conveyed along the conveyance path 23 is detected by the inline sensor 25 as necessary, and the detection result is transmitted to the control CPU 113. The sheets are stacked on the stack unit 21 according to the setting, or are transported as they are along the transport path 23 to the post-processing apparatus main body 30. In the post-processing apparatus main body 30, predetermined post-processing is performed according to the setting, or the post-processing is performed without performing post-processing, and the paper is discharged to the paper discharge unit 31 or the like.

FIG. 3 shows an example of a jam generation screen 1400 displayed on the LCD 141 of the operation unit 140 when a jam occurs in the fixing device 15 for the paper conveyed in the conveyance path 23. The occurrence of jam, for example, when a sensor for detecting paper is arranged at an appropriate position on the conveyance path and the paper cannot be detected by the sensor even after a predetermined time, is not detected with the sensor that has detected the passage of the paper. It can be determined that a jam has occurred with the sensor. When it is determined that Jam has occurred, the control unit interrupts the main output operation of the image forming apparatus.
On the jam generation screen 1400, the apparatus configuration 1401 of the image forming apparatus is displayed as an illustration, and displayed in different colors and patterns so that the jam generation apparatus configuration 1402 stands out. Further, the jam generator configuration 1402 displays a code 1403 indicating a jam occurrence location. In the jam generation screen 1400, an information display 1404 indicating the occurrence of a jam and its location is displayed, prompting the user to cancel the jam.

When the user removes the jam paper and is reset and the apparatus operation is resumed, processing related to the blank paper cleaning operation is started. The reset is performed in accordance with an operation instruction from the user through the operation unit 140, an opening / closing operation of the door of the apparatus main body, or the like.
Below, the procedure of the said process is demonstrated based on the flowchart of FIG. The following processing is executed under the control of the control CPU 113.

The process is started when a jam occurs and jam cancellation is performed.
First, it is determined whether or not the jam is to be subjected to blank paper cleaning (step s1). When Jam occurs around the fixing device, it can be determined that Jam is the target of blank paper cleaning.
If it is not the blank paper cleaning target jam (step s1, NO), the blank paper cleaning is unnecessary and the process ends.
If it is a blank paper cleaning target jam (step s1, YES), it is determined whether or not blank paper cleaning is to be performed (step s2). In this determination, as shown in FIG. 5, a cleaning inquiry screen 1410 is displayed on the operation unit 140, and the user is made to select cleaning. On the cleaning inquiry screen 1410, an inquiry display 1411 is displayed, and a “Yes” button 1412 and a “No” button 1413 are displayed so that they can be pressed.

  If the “NO” button 1413 is pressed, it is determined that the blank paper cleaning is not performed (step s2, NO), and the process is ended. If the “Yes” button 1412 is pressed, it is determined that blank sheet cleaning is to be performed (step s2, YES), and blank sheet cleaning processing is performed (step s3). The blank paper cleaning process is a process of feeding paper from the paper feed tray, transporting only the paper without forming an image, and passing the fixing device 15 through the paper. By passing the blank paper through the fixing device 15, the toner adhering to the fixing member such as the fixing roller of the fixing device 15 is copied onto the white paper, and as a result, the fixing device 15 is cleaned. The blank sheet can be passed through a predetermined number of sheets, and the number of sheets passed may be set for each sheet size. The number of sheets to be passed can be stored in the nonvolatile memory 115 or the HDD 119.

It should be noted that a paper feed tray for feeding paper can be selected for blank paper cleaning.
FIG. 6 shows a paper feed tray selection screen 1420 at the time of cleaning for selecting a paper feed tray to be used for blank paper cleaning. In the paper feed tray selection screen 1420, a selectable paper feed tray button group 1421 is displayed so that it can be pushed. When any of the paper feed tray buttons is pushed, tray information set in the paper feed tray is displayed. Is displayed in the tray information column 1422.
In addition, a start button 1423 is displayed on the paper feed tray selection screen 1420 so that the push button can be pushed. When one of the paper feed tray buttons is pushed and the start button 1423 is pushed, a sheet is fed from the selected paper feed tray. The paper is fed and cleaning starts.
When cleaning is started, until the cleaning is completed, the information display column 1424 displays that the inline sensor is operating and cleaning is being performed as shown in FIG.

Next, a toner adhesion amount measurement process is performed (step s4). The toner adhesion amount measurement process may be performed after the cleaning process is completed, or may be performed each time a sheet of white paper is passed through the fixing device 15.
In the toner adhesion amount measurement process, the inline sensor 25 reads the toner on the paper that has passed through the fixing device 15, and the control CPU 113 determines the toner adhesion amount from the read result. The toner adhesion amount is analyzed by, for example, an image read by an inline sensor.

Next, it is determined whether the detected toner adhesion amount is equal to or greater than a specified value (step s5). The specified value is set in advance and stored in the nonvolatile memory 115 or the HDD 119. For example, the standard value is set using a standard such as whether there is a black spot in the 5 × 5 mm range. It is desirable that this can be set by the operator himself. The specified value of the toner adhesion amount corresponds to the predetermined value of the present invention.
If the measured toner adhesion amount is less than the prescribed value (step s5, NO), the process is terminated because cleaning is unnecessary. If cleaning is in progress, stop cleaning. Thereafter, the main output operation of the interrupted job can be started.
If the detected toner adhesion amount is greater than or equal to the specified value (step s5, YES), cleaning is necessary. Therefore, when cleaning is in progress, cleaning is continued, and when predetermined cleaning is being performed for a while, Assuming that the cleaning is resumed, the process returns to step s3 to continue the processing.

In the above description, the cleaning operation is performed when a jam occurs. However, it may be possible to determine whether blank paper cleaning is necessary during job execution.
For example, as shown in FIG. 8, when a sheet of P1... P5... Is used along a page in a certain job, and there is a white image page on which no image is formed, the sheet (this example) Then, it is possible to determine whether or not cleaning is necessary by detecting toner adhesion using P3). In this case, as shown in Table 1, a toner adhesion measurement flag can be set for each page, and the amount of toner adhesion can be measured when a flag-on page is conveyed.
When the control unit determines from the job data that the page is a white image page, Page. 3 is output, the image is read by the in-line sensor 25 and the toner adhesion amount is measured. If the specified value is exceeded, a blank paper cleaning process is performed.

FIG. 9 is a flowchart showing a procedure for determining whether or not cleaning is required when a reserved job is output.
When the reserved job is executed, it is determined whether the page is a blank page (step s10). For the determination, as shown in Table 1, a flag set for each page can be used.
If it is not a blank page (step s10, NO), a printing process (main output operation) is performed on the page (step s11), and it is determined whether all pages of the reserved job have been printed (step s12). If the previous page has been printed (step s12, YES), the process ends. If all the pages have not been printed (step s12, NO), the process returns to step s10 to repeat the process.

If it is determined in step s10 that the page is a blank page (step s10, YES), toner adhesion amount measurement processing is performed for the blank page (step s13). Next, it is determined whether the measured toner adhesion amount is equal to or greater than a specified value (step s14). The specified value is set in advance and stored in the nonvolatile memory 115 or the HDD 119.
If the toner adhesion amount has not reached the specified value (NO in step s14), the process proceeds to step s12 to perform this output operation, and it is determined whether all pages have been printed.
If the toner adhesion amount is equal to or larger than the specified value (step s14, YES), the reserved job is interrupted and a cleaning process using white paper is performed (step s15). The cleaning process may be performed using a predetermined number of blank sheets, or may be performed using a single sheet of blank paper. If the next sheet or later in the reserved job is fed and is in the transport path 13, the pages of the subsequent reserved job are not fed. After performing the printing process on these sheets, the reservation job may be interrupted and the cleaning process may be performed.
Note that an operation for cleaning processing such as selection of a paper feed tray may be performed during the printing processing.

In the above description, when the toner adhesion amount is detected, which part of the target paper is to be detected is not clearly described. In the present invention, there is no particular limitation on whether the process is performed for the entire target paper or a part of the target paper, and where the target paper is used. Moreover, when determining whether a measured value is beyond a regulation value, you may determine based on one of measured values, and you may determine based on the average value of a measurement area | region.
Note that when determining the effect of blank paper cleaning, it is also possible to detect toner adhesion after cleaning on the rear side of the paper using the paper to be cleaned.
FIG. 10A shows a state in which the fixing device 15 having the fixing roller 15a having a peripheral length l is cleaned with a paper having a paper length L. At this time, if 4 * l> L is established, cleaning is performed in the portions of length l of p1, p2, p3, and p4 corresponding to the length of l of the paper, and toner adheres to the remaining portion of p4. Can be detected, and determination can be made without preparing a separate paper for toner adhesion. When the fixing roller contacts the paper a plurality of times, only the last contacted portion needs to be viewed.

In the above-described embodiment, the detection unit is provided in the subsequent device of the image forming apparatus main body 10. However, the detection unit may be provided in the image forming apparatus main body.
FIG. 11 shows an image forming apparatus main body 10a provided with an inline sensor 18 corresponding to a detection unit. The inline sensor 18 can have the same configuration as the inline sensor 25, and the inline sensor 18 also corresponds to the detection unit of the present invention.
The image forming apparatus main body 10a may be further connected to another apparatus main body in the subsequent stage, or the image forming apparatus may be configured by only the image forming apparatus main body 10a. In addition, the same code | symbol is attached | subjected about the structure same as above-described embodiment, and the description is abbreviate | omitted or simplified.

In this embodiment, an in-line sensor 18 is arranged on the conveyance path 13 downstream of the fixing device 15 and upstream of the point where the reverse conveyance path 16 branches from the conveyance path 13.
In the fixing device 15, not only the fixing roller in contact with the surface of the paper but also a portion in contact with the back side of the paper such as a counter roller may be stained. In the above-described embodiment, the toner adhesion is measured only on the front side of the paper, and therefore, it is not possible to confirm the backside contamination of the paper for white paper cleaning.

In this embodiment, the paper that has passed through the fixing device 15 is introduced into the paper reversing path 16, the front and back sides are reversed by the reversing unit 17, and then circulated to the conveying path 13, so The toner adhesion on the side can be detected by the in-line sensor 18, and the contamination state of the member that contacts the back side of the sheet of the fixing device 15 can be grasped. It should be noted that when grasping the stain state on the back surface side, it is confirmed that the member in contact with the paper surface side of the fixing device 15 is not dirty, or the toner is applied to a portion other than the paper portion where the toner adhesion is detected first. It is desirable to detect adhesion.
As a result, the influence of dirt on the front surface side of the fixing device 15 can be eliminated and the dirt on the back surface side can be accurately grasped.

The front / back detection procedure will be described with reference to the flowchart of FIG. The following processing procedure is executed by the operation of the control unit.
First, a blank paper cleaning process is performed (step s20), and toner adhesion on the paper surface is measured (step s21). Next, it is determined whether the measured value is equal to or greater than a specified value (step s22). The specified value can be stored in the nonvolatile memory 115 or the HDD 119 as described above. When the measured value is not less than the specified value (step s22, YES), the process returns to step s20 and the cleaning is continued.

If the measured value does not reach the specified value (NO at step s22), the sheet is reversed and conveyed by the sheet reversing path 16 and the reversing unit 17, and toner adhesion on the back side of the sheet is detected by the inline sensor 18 (step s23). ). Next, it is determined whether the measured value is equal to or greater than a specified value (step s24). The specified value can be stored in the nonvolatile memory 115 or the HDD 119.
It should be noted that the same value may be used for the front side and the back side, and different rules may be set for the front side and the back side and stored separately.

  If the measured value is not less than the specified value (step s24, YES), blank paper cleaning is performed (step s25), and the process returns to step s23 to continue the measurement process of the toner adhesion amount on the back side. If the measured value does not reach the specified value, the process is terminated.

  In the above description, it has been described that toner adhesion is detected on a blank paper. However, it is possible to determine toner adhesion on a blank paper portion where no image is formed. Therefore, even when blank paper is not being used during job execution, toner is attached using a blank area outside the image formation area of the paper on which the image is formed or a range where no image is formed even within the image formation area. Can be detected. In addition, it is desirable to detect toner adhesion in the entire width direction of the fixing member, and the entire width of the sheet can be set as a detection region in a margin portion. When a range where no image is formed is to be detected, if the full width of the paper cannot be secured, detection is performed in a plurality of ranges at different positions in the sub-scanning direction, so that the widest possible width (preferably the full width of the paper) Thus, toner detection can be performed.

In the above description, the cleaning process is automatically performed when the toner adhesion amount is equal to or greater than the specified value. However, the user may be instructed.
FIG. 13 is a flowchart illustrating a procedure for performing blank paper cleaning according to a user's selection.
When the procedure of the blank paper cleaning process is started, the user is notified by a method of displaying the detected adhesion amount on the operation unit 140 (step s30). Next, it is determined whether or not cleaning is performed (step s31).

FIG. 14 shows a cleaning execution selection screen 1430 displayed on the operation unit 140. On the selection screen 1430, the detected toner adhesion amount is displayed in the adhesion amount display column 1431, and in the message column 1432, it is displayed that the adhesion amount exceeds a specified value and a request to perform cleaning is requested. Has been.
Further, a “YES” button 1433 for instructing execution of cleaning and a “NO” button 1434 for instructing non-execution of cleaning are displayed on the selection screen 1430 in a pushable manner.
When “YES” button 1433 is pressed, it is determined that cleaning is being performed (step s31, YES), cleaning is executed, and the process ends. When “NO” button 1434 is pressed, the process is terminated without performing cleaning.

  As described in the above embodiment, when the blank paper cleaning is started, the toner adhesion amount is measured by the in-line sensor, and the blank paper cleaning is performed until it becomes less than a certain threshold value. When the toner adhesion amount becomes less than the threshold value, the blank paper cleaning is completed and the normal output can be returned.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to the content of the said embodiment, A suitable change is possible unless it deviates from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image forming apparatus main body 10a Image forming apparatus main body 14 Automatic document feeder (ADF)
DESCRIPTION OF SYMBOLS 11 Image formation part 15 Fixing device 18 Inline sensor 20 Relay apparatus main body 25 Inline sensor 30 Post-processing apparatus main body 113 Control CPU
115 Non-volatile memory 130 Scanner unit 140 Operation unit 150 Printer unit 1400 Jam generation screen 1410 Cleaning inquiry screen 1420 Paper feed tray selection screen 1430 Cleaning execution selection screen

Claims (9)

An image forming unit for forming a toner image on paper;
A fixing device for fixing the toner image on the paper to be passed;
A detection unit for detecting toner adhesion on paper conveyed through the fixing unit;
A control unit for controlling the image forming apparatus,
The control unit is configured to receive a detection result of the detection unit and determine a stain state of the paper that has passed through the fixing device based on the detection result.
When the job includes a blank page, during the actual output operation of the job, a detection result obtained by detecting the toner adhesion by the detection unit in order to determine the contamination state only for the blank page after fixing is received, and based on the detection result. Judge the paper smudge status,
When the detected toner adhesion amount is equal to or greater than a predetermined value, it is determined that the cleaning process of the fixing device is necessary. When the detected toner adhesion amount is less than the predetermined value, it is determined that the cleaning process is not necessary. And
When it is determined that the fixing device needs to be cleaned, the main output operation of the job is interrupted and the fixing device cleaning process is started.
If it is determined that the cleaning process is not necessary, the output operation is continued. The control unit continues the cleaning process when determining that the fixing unit needs to be cleaned in the determination of the dirty state of the paper during the cleaning process, and determines that the cleaning process is not necessary. the image forming apparatus according to 請 Motomeko 1 you, characterized in that to resume the output operation. Wherein the control unit, the image forming apparatus according to claim 1 or 2, characterized in that it has a function of notifying the detection result and / or the state of soiling of the toner adhering to the user. The image forming apparatus according to claim 3 , wherein the control unit enables a user to perform the cleaning instruction operation together with the notification. Wherein the control unit, the image forming apparatus according to claim 3 or 4 adhesion amount or the contamination state of the toner and performing the notification when it exceeds a predetermined reference. A paper reversing device capable of reversing the paper that has passed through the fixing device;
The control unit reverses the paper on which toner adhesion has been detected by the detection unit using the paper reversing device, and enables detection of toner adhesion on the back side of the paper by the detection unit. Item 6. The image forming apparatus according to any one of Items 1 to 5 . Wherein, after said fixing device and cleaning process by a predetermined amount, the image forming apparatus according to any one of claims 1 to 6, characterized in that the detection of the toner adhesion by the detection unit. The image forming apparatus according to any one of claims 1 to 7, characterized in that the cleaning process is performed by passed the blank paper to the fixing device. In the cleaning process of the fixing device with blank paper, the control unit calculates the number of cleanings for the fixing device from the length of the paper passing direction of the blank paper, and when the cleaning is performed a plurality of times, The image forming apparatus according to claim 8 , wherein the toner adhesion is detected by the detection unit for a paper portion corresponding to cleaning.

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