JP6007693B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a plotter, a facsimile, or a complex machine thereof.

  As a form of paper feeding in a paper feeding unit of this type of image forming apparatus (hereinafter simply referred to as “machine”), a form using a paper feeding cassette, a paper feeding tray, or a manual feed tray is known. Yes. When the paper is set in the paper feeding mode, the paper is set by “horizontal feed” or “vertical feed”. The “lateral feed” is a set state in which the long side of the paper is positioned perpendicular to the paper transport direction, and is also expressed as “LEF (abbreviation of Long Edge Feed)”. “Vertical feed” is a set state in which the short side of the sheet is positioned perpendicular to the sheet conveyance direction, and is also referred to as “SEF (Short Edge Feed)”.

  There are various types of paper such as standard size paper (A3, A4, B4, B5, etc.), inch paper (DLT, LT, HLT, etc.), and other irregular size paper. Including paper type and paper thickness, the number of types increases. On the other hand, the feeding start timing of the machine is precisely set without waste according to the sheet length in the transport direction in order to increase productivity. In addition, in an image forming unit including a photoconductor, a secondary transfer belt, and the like, temperature control of the fixing device is performed according to the length of a sheet on which an image is formed.

  For this reason, if the paper size and the vertical / horizontal setting direction recognized on the machine side are different from the actual paper size and setting direction (hereinafter referred to as “paper size mismatch”), The paper is not fed correctly due to timing. Then, there is a high possibility that a plurality of sensors provided in the paper conveyance path in the machine will judge that the paper conveyance timing is abnormal and cause a jam.

  Further, since the image forming conditions are deviated, a normal image cannot be obtained. In this case, in order not to waste ink, toner, and processing time due to an abnormal image, when the machine detects that the image forming conditions have deviated, it recognizes the subsequent paper feed as a jam, Printing may stop. In addition, an error message may be displayed after the paper recognized as having a different size is discharged out of the machine, and the subsequent copying / printing may be stopped.

  When the paper size mismatch occurs in this manner, an area larger than the paper area may be formed in the image forming unit even when a jam occurs or a jam does not occur. As a result, it is necessary to clean the untransferred toner and the like, and the process unit is frequently replaced, and the life of the process unit is shortened.

  Conventionally, various countermeasures have been proposed to solve the problem of paper size mismatch. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 11-292349) informs the user of the fact by a message on the display when a paper feed jam is detected at the time of paper feeding after the image forming operation is started. And take measures to recover from jams.

  Japanese Patent Laid-Open No. 2003-095482 discloses a size error notification when the paper size detected before paper passing does not match the paper size of the print command, and prints the paper as it is. It is made to judge whether or not.

  Patent Document 3 (Japanese Patent Laid-Open No. 10-194529) detects the paper length with a timing sensor and stops the machine when the paper sizes do not match.

  Patent Document 4 (Japanese Patent Application Laid-Open No. 07-092959) informs the user of the fact that the paper sizes do not match.

  In Patent Document 5 (Japanese Patent No. 4065497), when the paper size (paper width) detected before passing the paper does not match the specified paper size, the user is notified of the fact, and the printing is performed with the size as it is. The user is allowed to select whether or not to do so.

  As described above, the length of the paper in the conveyance direction is an important parameter for the machine, but it is not easy for the machine to recognize the exact size and vertical / horizontal feeding direction for each paper. In addition, as a factor that makes it difficult to detect the paper size, there is a problem of paper feed and double feed. There are various types of paper set in the machine, and some types of paper (e.g., coated paper or water-resistant paper with a smooth surface) are easy to carry / double feed. Such a specific paper type is hereinafter referred to as “specific paper”.

  These specific sheets are difficult to separate between sheets due to electrostatic force or entanglement of paper fibers. Also, with special brand paper, cutting burrs at the paper edge may cause carry / double feed. When these specific sheets are set in the sheet feeding unit and the job is executed, the length detected by the sheet length detection unit is erroneously detected longer than the original sheet length due to carry / multifeed. . If such a misdetection occurs, the machine issues a “mismatch” notification even if the paper size does not match, resulting in a jam or an error, so the user is forced to check the paper settings and recover the machine each time. As a result, the productivity of the machine is greatly reduced.

  An object of the present invention is to prevent a sheet length detection unit from erroneously detecting a sheet length by feeding / multiple feeding of sheets in a machine that notifies a user of a sheet size mismatch. In other words, the paper conveyance direction length is correctly detected in a conveyance state without single feed / multi-feed (single-feed state), and whether the paper size matches or does not match is correctly determined based on the detection result. To the user, and the user can quickly resolve the cause of the paper size mismatch based on the notification.

  In order to solve the above-described problem, the present invention provides a paper feeding direction of the set paper set in the image forming apparatus at the time of image formation based on the length of the set paper manually or automatically input to the image forming apparatus. Is A, and B is the length detected by the paper length detection means for detecting the length of the paper actually conveyed in the image forming apparatus for image formation. The control unit of the image forming apparatus compares both lengths, and when | A−B | is smaller than a predetermined value, it is determined that the size of the set sheet is appropriate, and a predetermined image forming process is executed. When | A−B | is larger than a predetermined value and A> B, it is determined that the size of the set sheet is inappropriate, and the user is notified of the inappropriateness, and | A−B | If A <B, the A <B is continuously detected more than a predetermined number of times. When the size of the set paper is an image forming apparatus is characterized in that so as to notify the user the improper it is determined that the improper. The “predetermined value” can be based on the tolerance of the paper, and can be set to any of 20 mm, 15 mm, 10 mm, and 5 mm, for example.

  According to the present invention, it is possible to prevent erroneous detection of the paper conveyance direction length due to paper feed / double feed, and the user is limited to a paper size mismatch that requires confirmation of the paper setting or paper setting state of the machine. The user can quickly resolve the cause of the paper size mismatch.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is the schematic of an operation panel. It is a perspective view of a paper feed cassette. It is a perspective view of a manual feed tray. 2 is a schematic diagram of a control unit as a control unit of the image forming apparatus. FIG. FIG. 10 is a diagram illustrating display contents of a sheet tray selection screen displayed on the operation panel. It is a figure which shows the paper setting menu of a 2nd tray. It is a flowchart which shows the example of control of a control part. It is a flowchart which shows the example of control of a control part. It is a flowchart which shows the example of control of a control part. It is a flowchart which shows the example of control of a control part. It is a flowchart which shows the example of control of a control part. It is a flowchart which shows the example of control of a control part.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description will be given. Omitted.

(Image forming device)
FIG. 1 schematically shows an embodiment of an image forming apparatus to which the present invention is applied. This image forming apparatus is a multifunction peripheral (MFP) that combines two or more functions of a copying machine, a printer, a plotter, and a facsimile machine. The image forming apparatus is connected to the operation panel P of FIG. 2 or a network such as a wired or wireless LAN (not shown) It can be operated through a personal computer.

  The operation panel P includes a display device 3 such as an LCD for indicating the state of the image forming apparatus, and an operation input device 4 provided with various switch units for switching the mode and font of the image forming apparatus. The operation input device 4 includes an ultrasonic acoustic wave type touch panel 4a laminated on the surface of the display device 3, and a keyboard 4b having a plurality of keys. The keyboard 4b is provided with a start key for declaring the start of image reading, a numeric keypad for inputting numerical values, a reading condition setting key for setting the transmission destination of the read image data, a clear key, and the like.

  An image forming unit 100 is provided in the image forming apparatus main body 10. The image forming unit 100 is provided with an image carrier (photosensitive member) 11 on a drum, and a charging device 12, a developing device 13, a transfer / conveying device 14, a cleaning device 15 and the like are disposed around the image bearing member (photosensitive member) 11.

  A laser writing device 16 is provided on the image forming unit 100. Although not shown, the laser writing device 16 includes a light source such as a laser diode, a scanning rotary polygon mirror that is a polygon mirror, a polygon motor, a scanning optical system such as an fθ lens and a mirror, and the like.

  A fixing device 17 is provided on the left side of the cleaning device 15 in the drawing. The fixing device 17 is provided with a fixing roller 18 incorporating a heater and a pressure roller 19 pressed against the fixing roller 18 from below.

  In the lower part of the apparatus main body 10, a duplex unit 22 and a four-stage sheet cassette 23 are provided at the top and bottom. In addition, a large-volume sheet feeding device 30 is disposed externally to the apparatus main body 10, and a large amount of sheets are stacked in the apparatus main body 10 so as to be movable up and down.

  The duplex unit 22 passes through a refeed path A, and the feed cassette 23 passes through a supply path B to a common sheet feed path C extending below the image carrier 11. The duplex unit 22 branches off from the middle of the sheet discharge path D extending from the exit of the fixing device 17 to form a reverse path E.

  FIG. 3 shows the paper feed cassette 23. At the bottom of the paper feed cassette 23, a bottom plate is disposed that raises to an arbitrary position in a state where papers for image formation are stacked. The stacked sheet bundle 53 is regulated by a pair of side fences 54 and 54 that can slide in a width direction orthogonal to the feeding direction, and is regulated by an end fence 52 that can slide the feeding direction.

  The side fence 54 constitutes side detection means for detecting the lateral size of the paper, and the end fence 52 constitutes end detection means for detecting the length of the paper in the length direction. The positions of the fences 52 and 54 are detected by a sensor (not shown) so that each length in the width direction and the length direction of the set paper is detected.

  A detection sensor 51 including a plurality of push switches is provided on the image forming apparatus main body 10 side independently of the paper feed cassette 23. In addition, it is also possible to form an extension tray part by disposing the end fence 52 so as to be movable further beyond the predetermined moving range. Such an extension tray portion is convenient when setting a longitudinal sheet.

  A contact glass 26 is installed in the image reading unit 24 on the upper surface of the apparatus main body 10. An automatic document feeder 27 is provided on the apparatus body 10 so as to cover the contact glass 26 so as to be freely opened and closed. The automatic document feeder 27 and the optical reading device 20 constitute an image reading device 200.

  On the right side surface of the apparatus main body 10, a manual feed tray 28 for guiding manual feed paper to the paper feed path C is provided so as to be freely opened and closed. As shown in FIG. 4, the manual feed tray 28 is also supported by a manual feed subunit 28 a fixed to the image forming apparatus, and rotatably supported by the image forming apparatus by a support shaft 29, and also serves as an exterior cover, and is a transfer sheet. Are provided with a main tray portion 28b, an extension tray portion 28c, and a side fence 28d. The side fence 28d can also serve as side detection means for detecting the length of the paper in the width direction. Here, the “width direction” of the sheet is a direction orthogonal to the transport direction. The “length direction” of the paper is the same direction as the transport direction.

  The extension tray portion 28c is used by being pulled out from the main tray portion 28b when the longitudinal sheets are stacked. The extension tray portion 28c can be slid and stored in the main tray portion 28b when not in use or when the manual feed cover 5 is closed.

  A sheet post-processing device 31 is installed on the left side surface of the apparatus main body 10 so as to be attached to the apparatus main body 10, accepts the sheet discharged through the sheet discharge path D, and discharges the sheet as it is onto the upper tray 32, or staples After post-processing such as drilling, the sheet is discharged onto the upper tray 32 or the lower tray 33.

  When making a copy using this image forming apparatus, the original is set on the automatic document feeder 27 or the automatic document feeder 27 is opened and the original is directly set on the contact glass 26. When the start key on the operation panel P is pressed, the optical reading device 20 starts reading the document.

  When the paper feed cassette 23 is attached to the image forming apparatus main body 10, the concave / convex pattern on the cassette side and the paper size detection sensor 51 of the image forming apparatus main body 10 are pressed against each other. At the same time, an appropriate paper feed roller 34 rotates, and paper is sent out from the corresponding paper feed cassette 23 among the plurality of paper feed cassettes 23 provided in the apparatus main body 10 in multiple stages. The fed paper enters the paper feed path C through the supply path B, is transported by the transport roller 35, and is abutted against the timing roller pair 36 and stopped.

  In the vicinity of the paper feed roller 34 or the timing roller pair 36, the paper length for detecting the length of the paper from the rotation time of the timing roller pair 36 required for one sheet to pass and the outer peripheral length of the roller pair. A thickness detecting means is provided. Furthermore, although not shown, the control unit 102 in FIG. 5 of the machine to be described later is provided with a paper size estimation unit and a paper size determination unit.

  The paper size estimation means determines the size of the paper set on the manual feed tray 28 from the paper width detected by the side fence 28d and the paper size table stored in the control unit 102, for example, A4 or A3. To be estimated. The paper size determination means determines the set paper size from the estimation result and the paper length detected by the paper length detection means.

  The timing roller pair 36 rotates in synchronism with the rotation of the image carrier 11, and the sheet is fed below the image carrier 11 of the image forming unit 100. Alternatively, the paper feed roller 37 rotates and the paper is fed out from the mass paper feeder 30, enters the paper feed path C through the transport path F, is transported by the transport roller 35, and abuts against the timing roller pair 36. It can be stopped.

  Alternatively, the paper feed roller 38 in the manual paper feed unit rotates, and the manual paper set on the open manual feed tray 28 enters the paper feed path C and is also abutted against the timing roller pair 36 and stopped. The timing roller pair 36 rotates in synchronization with the rotation of the image carrier 11 and is fed below the image carrier 11 of the image forming unit 100.

  When the start key on the operation panel P is pressed, the carrier 11 is simultaneously rotated clockwise in the figure on the image of the image forming unit 100. Along with the rotation of the image carrier 11, the surface is first uniformly charged by the charging device 12, and then writing is performed by the laser writing device 16 by irradiating a laser beam according to the read content read by the optical reading device 20. An electrostatic latent image is formed on the surface of the image carrier 11, and then the toner is attached by the developing device 13 so that the electrostatic latent image is visualized.

  As described above, the visible image is transferred by the transfer / conveyance device 14 to the sheet fed below the image carrier 11. After the image transfer, the image carrier 11 is cleaned by removing the residual toner by the cleaning device 15 and prepared for the next similar image formation. The image carrier 11, the transfer / conveyance device 14, and the cleaning device 15 form one unit (process unit).

  The sheet after image transfer is conveyed by the transfer / conveyance device 14 and enters the fixing device 17, and heat and pressure are applied by the fixing roller 18 and the pressure roller 19 to fix the transferred image. Thereafter, the paper is discharged to the paper post-processing device 31 through the paper discharge path D.

  When forming images on both sides of the paper, the image is put in the reverse path E from the middle of the paper discharge path D, reversed by the duplex unit 22, re-fed, and separately formed on the back side of the paper by the transfer / conveyance device 14. After the image on the carrier 11 is transferred, the transferred image is fixed by the fixing device 17 and discharged to the paper post-processing device 31.

  The image forming apparatus main body 10 includes a control unit 102 as a control unit as shown in FIG. The control unit 102 converts print data from the host 103 into video data according to the control mode set therein and the control code from the host 103 or the network 115, and outputs the video data to the printer engine 113. It consists of the following modules.

  Panel I / F 108 is an interface between control unit 102 and operation panel P. The host I / F 105 is an interface for control signals and data from the host 103 to the image forming apparatus, and status signals from the image forming apparatus main body 10 to the host 103. The network I / F 116 is an interface for control signals and data from the network 115 to the image forming apparatus and status signals from the image forming apparatus main body 10 to the network 115.

The CPU 109 processes data (print data, control data, etc.) from the host 103 according to the program ROM 106. The RAM 110 and the option RAM 114 manage work data when the CPU 109 processes, a buffer for managing data from the host 103 in units of pages, and temporarily storing the data, and converting the data stored in the buffer into an actual print pattern. Used for bitmap memory that stores data.
An HDD (mass storage device) 117 stores a large amount of data. It is also used as a place to store a document of a stored document print function for storing a print document received from the host 103 and printing it later.

  The NV-RAM 111 (Nonvolatile RAM) is a non-volatile RAM for storing data to be retained even when the power is turned off. The font ROM 107 has various types of fonts used for printing. The engine I / F 112 is an interface for control signals and video data from the control unit 102 to the printer engine 113 and status signals from the image forming apparatus main body 10 to the control unit 102. The printer engine 113 creates and develops an electrostatic latent image on the photosensitive member based on the video signal and the control signal from the control unit 102, feeds the transfer paper from the paper feed unit, and transfers and fixes it to form an image. To do.

  The above is the outline of the control unit 102. Next, a series of flow of how data sent from the host 103 or the network 115 is processed will be described taking an example when print data is sent from the host 103.

(Reception processing)
The print data sent from the host 103 through the host I / F 105 is analyzed by the CPU 109 according to the data analysis program on the program ROM 106, and the print data and print control data (SP, CR, LF, HT, VT, etc.) and others. It is divided into. The print data and print control data are temporarily stored in the reception buffer on the RAM 110.

(Drawing process)
The received data once stored is taken out one by one by the control program on the program ROM 106 and processed. For example, if the extracted data is a character code, an intermediate code including a print position, a print size, a character code, font information, and the like is created and stored in an intermediate buffer provided on the RAM 110. If the extracted data is a command such as a control code or an escape sequence, a process defined in advance is performed on them.

  An example of a predefined process is shown. For example, if the extracted data is a control code for designating the print position, the position of the next character code is set to the designated position. Alternatively, if the font is changed, the font information of the next character code is set to the designated font. In this way, when the print command processing is performed according to the print data sent from the host 103 or the processed data exceeds one page, the intermediate code stored in the intermediate buffer is then stored in the control program. According to the above, processing for conversion to video data is performed.

(Output processing)
When the conversion is completed, the control unit 102 issues a print start command to the printer engine 113 through the engine I / F 112, and transfers video data in synchronization therewith. The print data from the host 103 is printed via the printer engine 113 in the series of flows as described above.

  The image forming apparatus can take a paper feed form using a paper feed cassette, a paper feed tray, or a manual feed tray that can selectively use the extension tray portion as a paper feed form. For example, as a paper feed tray, a plurality of paper feed trays such as a normal tray that supports a normal paper size (for example, A4 to A3) and a small size tray that supports a small paper size (for example, a postcard to B5) are used. Is possible. These types of paper feed modes can be detected by the printer engine 113.

  FIG. 6 shows an operation example when the user selects a tray on the operation panel for paper selection. In this example, the image forming apparatus has four trays from “second tray” to “fifth tray”, and the types of paper feed trays that can be exchanged are “normal” and “small size”.

  According to the menu displayed after the user presses the “Menu” key on the operation panel P, “Adjustment / Management”, “General Management”, “Small Size Tray”, “Tray 2-5”, “Not Use / Use” ”Is selected to set or save which tray uses the small size tray.

  This menu is read from what is stored in the program ROM 106. The program ROM 106 stores the entire range of the size of the irregular paper size that can be handled by the paper feed tray that can be exchanged and installed in the image forming apparatus. In this embodiment, two types of ranges “normal” and “small size” are stored.

  The selection result is stored in the NV-RAM 111 and is retained after the power is turned off / on. When the paper size is set after the type of the paper feed tray is determined, the paper size that can be selected changes according to the type of the selected paper feed tray.

  A specific example is given. The example shown in FIG. 7 is an example of a paper setting menu in the second tray (tray 2). If “paper setting” and “tray paper size: trays 2 to 5” are selected in accordance with the menu displayed after the “menu” key is pressed, and the type of the paper feeding tray is a normal tray, < When the A> menu is selected, a normal paper size option is displayed. When the type of the paper feed tray is a small size tray, a small paper size option is displayed as in the <B> menu of FIG. The When an irregular size is selected in this paper size option (third layer), the irregular size paper size setting is displayed (fourth and fifth layers), and the range of usable sizes for each type of paper feed tray is displayed. The size can be set.

(Control contents of the control unit)
The control unit 102 of the image forming apparatus notifies the user so that the mismatch can be quickly resolved when a paper size mismatch is detected other than the accompanying / multiple feed. 8 to 13 are flowcharts showing the control contents for that purpose.

  An example of control executed by the control unit 102 of the image forming apparatus will be described with reference to the flowcharts of FIGS.

(Control example)
FIG. 8 shows a control example 1. First, the length of the paper set in the machine is input manually or automatically (S1). This input is performed manually, for example, through the operation input device 4 on the operation panel P or a printer driver screen displayed on a monitor of a personal computer. The automatic input is performed by the sensor detecting the combination of the sheet feeding cassette detection plate and the push switch, the position of the end fence 52 and the side fence 54 of the sheet feeding cassette 23, or the side fence 28d of the manual feed tray 28. From the input paper length, the paper size estimation means of the control unit 102 estimates the size of the set paper (A3, A4, B4, B5, etc.), and the length A of the set paper in the paper feeding direction is determined. The machine is set (S2).

  When the length A is set in the machine, a copy / print command is issued from the machine controller 102 (S3), and copy / print is started (S4). When the first sheet fed from the sheet feeding cassette 23 is transported inside the machine, the length B in the sheet transport direction is detected by the above-described sheet length detecting means (S5).

  In S6, the lengths A and B are compared, and when the absolute value | A−B | is smaller than the predetermined value (A≈B), it is determined that the size of the set sheet is appropriate and the predetermined image forming process is performed. Copy / print is executed (S7). The predetermined value determined to be “smaller than the predetermined value” can be set to any of 20 mm, 15 mm, 10 mm, and 5 mm, for example.

  When | A−B | is larger than the predetermined value, it is determined that the size of the set sheet is inappropriate, and a jam or error is displayed (S8). In S9, the magnitude relationship between A and B is determined. If it is determined by this determination that A> B is so-called too short detection, the user is notified of the inappropriateness (S10). In the case of too short detection, there is a high possibility that the actual paper length is shorter than the paper setting of the machine. This notification includes a notification requesting that the paper size of the machine be re-set, and a notification requesting confirmation of the loaded paper.

  The notification can be displayed on the operation panel P or a personal computer monitor. A screen for setting the paper size may be displayed together with or subsequent to the notification. When it is necessary to reset the paper, such a screen is automatically opened on the operation panel P or the monitor of the personal computer, thereby improving the convenience for the user.

  When the user performs a jam or error recovery operation according to the notification in S10 (S11), the second copy / print is started (S4). Here, the first and second sheets have nothing to do with the first and second sheets of the job. That is, it means the first sheet and the second sheet in which the lengths A and B are compared in S6.

  If so-called too long detection of A <B is determined in S9, the process proceeds to S12. Here, too long sheet detection (A <B) continues for a predetermined number of times or more in a job that feeds paper from the same paper feed tray. It is then determined whether it has been detected. Here, the “predetermined number of times” is an integer n fixed to 1 or 2 or more.

  Paper that is easy to carry / double feed (specific paper) has a property of repeating repeat feed / double feed twice and three times with almost no single feed. On the other hand, with plain papers other than specific papers, it is rare that continuous or double feeding occurs continuously even if double feeding or double feeding occurs due to poor paper separation. Therefore, the size of n is set in advance in advance in consideration of the degree to which the paper used in the machine is easily fed / double fed.

  If too long is detected or less than the predetermined number of times, the process proceeds to S11, where a recovery operation for jam or error due to conventional erroneous detection is performed, and then the process returns to S4 described above to return to the second copy / Start printing. That is, when the detection is too long and less than the predetermined number, it is determined that the detection is an erroneous detection due to carry / double feed.

  If too long is detected a predetermined number of times or more, it is determined that the paper length is not the result of correctly detecting the paper length, not the carry / double feed, and the process proceeds to S10 and the paper size for the user as described above. Notify mismatch. Accordingly, the user can quickly eliminate the cause of the paper size mismatch based on the notification.

  FIG. 9 is obtained by adding a control example 2 different from the control example described above. This control example 2 is the same as in FIG. 8 until a jam or error display is made in S8 when it is determined in S6 that the paper size does not match, but the subsequent control is changed depending on whether or not paper is supplied. is there.

  That is, in S13, whether or not there is paper replenishment between the paper that is currently (currently) passed and the paper that was passed one time before the paper tray used in the current job. To be judged. Since papers of different sizes are rarely set in the same paper feed tray in a mixed state, there is no paper replenishment, and this is the first time that the paper size has been mismatched, immediately before (one time before) If it is not determined that the paper size does not match, it is highly likely that the length B of the paper transport direction obtained in S5 is erroneously detected. Therefore, a jam or error recovery operation is performed in S11, and the process returns to S4 described above.

  If it is determined in S14 that the paper size of the previous paper also does not match, and if it is determined in S13 in the previous stage that the paper has been replenished, the same control as in FIG. 8 is performed after S9. As a result, it is possible to more accurately eliminate erroneous detection of the paper length being too long due to carry / double feeding and notification of paper size mismatch based on the erroneous detection. That is, only when the paper size actually does not match, it is possible to notify the user of the paper size mismatch, and based on the notification, the user can quickly resolve the cause of the paper size mismatch.

The presence / absence of paper replenishment can be determined as “paper replenishment” if any one of various operations applied to the image forming apparatus in relation to paper replenishment. Specifically, if any one of the following criteria is applicable, it can be determined that “paper supply is present”. That is, between the current and previous two paper transports,
-When the paper tray used in the job is pulled out-When paper is detected after paper out of the paper tray used in the job is detected-Paper size set for the job If the machine size setting does not change,
・ When automatic size detection, a new automatic size detection is performed after resetting size information, etc. ・ When manual size setting, a new manual size setting is performed after resetting size information, etc. ・ Manual At the time of size setting, if the default size setting value is reached after resetting the size information, it can be determined that “paper supply is present”.

In addition to the above criteria, the following two criteria may be added.
-When the power is turned off-When the power saving mode, sleep mode, and standby mode are entered These two criteria are based on the power supply, and the information about whether the tray is pulled out between two paper transports and whether there is paper This is because I don't know.
By following the above criteria, it is possible to more reliably detect the possibility that the paper has been replenished, thereby detecting the “paper size mismatch” more reliably without erroneous detection and notifying the user. Based on this, the user can quickly resolve the cause of the paper size mismatch.

  FIG. 10 is obtained by adding a control example 3 different from the above-described control example. In this control example 3, if it is determined in S9 that it is too long, the paper length B detected in S5 indicates the maximum length of paper that can be set in the paper feed tray that has supplied the paper. It is judged whether or not it exceeds. In other words, if the paper length B is detected as a length that cannot be physically set in the paper feed tray, it is obvious that the paper length B is erroneously detected, so that a jam or error recovery operation is performed in S11. It returns to S4 mentioned above.

  If it is determined in S15 that the length is physically settable in the paper feed tray, the control from S12 is performed as in FIG. As a result, it is possible to more accurately eliminate erroneous detection of the paper length being too long due to carry / double feeding and notification of paper size mismatch based on the erroneous detection. That is, only when the paper size actually does not match, it is possible to notify the user of the paper size mismatch, and based on the notification, the user can quickly resolve the cause of the paper size mismatch.

  FIG. 11 is obtained by adding a control example 4 different from the above-described control example. In this control example 4, it is determined in S16 whether the paper is easy to carry / double feed. In the paper setting of the machine, it is possible to set the paper type. That is, paper types such as plain paper, thick paper, coated paper, water-resistant paper, paper brands, and the like can be set in the machine as image forming conditions.

  On the machine side, conditions such as transfer and fixing are changed according to the input information. In this way, from the paper type information set in the machine, the control unit of the machine determines whether the paper is easy to carry / double feed (specific paper) (S16). If it is determined that the specific sheet is easy to carry / multiple feed, the jam or error recovery operation is performed in S11 without performing the notification in S10 and without determining whether the continuous length is too long in S12. Return to S4.

  If it is determined that the sheet is not a specific sheet that is easy to carry / double-feed, it is determined in S12 whether or not the detection of too long a sheet has been continuously detected a predetermined number of times or more in a job that feeds paper from the same paper feed tray. The subsequent control is the same as in FIG. As a result, it is possible to more accurately eliminate erroneous detection of the paper length being too long due to carry / double feeding and notification of paper size mismatch based on the erroneous detection. That is, only when the paper size actually does not match, it is possible to notify the user of the paper size mismatch, and based on the notification, the user can quickly resolve the cause of the paper size mismatch.

  FIG. 12 is obtained by adding a control example 5 different from the above-described control example. In this control example 5, the degree of ease of follow-up / multiple feeding described above is distinguished by the magnitude of the continuous detection number n of detection of too long. The larger the number n, the easier it is to carry / double feed. The smaller the number n, the more difficult it is to carry / double feed. The control unit of the machine determines the ease of carrying / multiple feeding of the set paper from the paper type information set in the machine (S16a), and automatically determines the size of n based on the determination. (S16b).

  As described above, by changing the setting of the “predetermined number of times” according to the ease of carrying / double feeding of the paper, it is possible to more accurately detect the paper too long due to the carrying / double feeding and based on the erroneous detection. It is possible to eliminate notification of paper size mismatch. That is, only when the paper size actually does not match, it is possible to notify the user of the paper size mismatch, and based on the notification, the user can quickly resolve the cause of the paper size mismatch.

  In this control example 5, in the case of erroneous detection due to carry / double feed, the user is not notified of paper size mismatch. That is, the length of the paper in the conveyance direction is correctly detected in a conveyance state without single feed / multi-feed (single-feed state), and when the detection result does not match the paper size, the user is promptly notified. Based on this, the cause of the paper size mismatch can be quickly resolved and the job can be resumed.

  FIG. 13 is obtained by adding a control example 6 different from the above-described control example. In this control example 6, the setting value of the number of times of continuous overlength detection (predetermined number = n times) indicating the degree of ease of the above-mentioned carry / double feed is set by the machine user or the service person. According to the usage environment, the notification can be changed so that the notification of S10 does not occur as a result of erroneous detection of the length in the sheet conveyance direction (S16c).

The set value of the predetermined number of times (n times) can be set as follows, for example, according to the ease of carrying / double feeding.
n = 5 times: Paper that is most easily “taken / double-fed” (such as coated paper, water-resistant paper, etc.)
n = 3 times: Paper that is slightly easier to “feed / double-feed” (paper brands with large cutting burrs that often cause the paper to be mechanically in close contact)
n = 2 times: normal paper n = 1 time: paper of good quality and most difficult to “feed / double feed” n = 1 time when paper is too long (A <B) As a condition for notifying the size mismatch, it is not a condition that the detection of too long is continued a predetermined number of times or more. That is, when the paper is too long, the user is immediately notified of the paper size mismatch as in the case where the paper is too short.

  As described above, by changing the setting of the “predetermined number of times” according to the ease of carrying / double feeding, it is possible to more accurately detect the paper length too long due to the carrying / double feeding and the paper size based on the erroneous detection. It is possible to eliminate discrepancy notifications. That is, only when the paper size actually does not match, it is possible to notify the user of the paper size mismatch, and based on the notification, the user can quickly resolve the cause of the paper size mismatch.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the technical idea described in the claims.

4 Operation Input Device 4a Touch Panel 4b Keyboard 10 Image Forming Device Main Body 12 Charging Device 12 Control Example 13 Developing Device 13 Rear Developing Device 14 Transfer / Conveying Device 15 Cleaning Device 17 Fixing Device 23 Paper Feed Cassette 28 Manual Tray 28a Paper Feed Subunit 28b Main tray section 28c Extension tray section 28d Side fence 34 Paper feed roller 35 Transport roller 36 Timing roller pair 37 Paper feed roller 38 Paper feed roller 52 End fence 53 Paper bundle 54 Side fence 100 Image forming section 102 Control section 103 Host 115 Network 200 Image reading device P Operation panel

Japanese Patent Laid-Open No. 11-292349 JP 2003-095482 A Japanese Patent Laid-Open No. 10-194529 Japanese Patent Application Laid-Open No. 07-092959 Japanese Patent No. 40654497

Claims (8)

Based on the length of the set paper manually or automatically input to the image forming apparatus, the length in the paper feeding direction of the set paper set in the image forming apparatus at the time of image formation is A. When the length detected by the paper length detecting means for detecting the length of the paper actually conveyed in the image forming apparatus is B, the control means of the image forming apparatus has both lengths. When | A−B | is smaller than a predetermined value, it is determined that the size of the set sheet is appropriate, a predetermined image forming process is executed, and | A−B | is larger than the predetermined value. When A> B, it is determined that the size of the set paper is inappropriate and the user is notified of the inappropriateness. When | A−B | is larger than a predetermined value and A <B, the A <When B is continuously detected a predetermined number of times or more, the size of the set paper is invalid. With it is determined to be positive to notify the inappropriate user, without notifying the user when not detected a predetermined number of times or more in succession the A <B,
When a plurality of sheets are conveyed in one job, it is detected that | A−B | is greater than a predetermined value for a predetermined sheet to be conveyed, and | A− for another sheet conveyed immediately before the sheet. When it is detected that B | is greater than a predetermined value, it is determined whether or not the paper is supplied between the two paper transports. If it is determined that the paper is supplied, the notification is executed. When it is detected that −B | is smaller than a predetermined value, and it is detected that | A−B | is larger than a predetermined value for another sheet conveyed immediately before the sheet, it is determined that the sheet has not been replenished. In such a case , the image forming apparatus is configured to cancel the notification . 2. The image forming apparatus according to claim 1 , wherein the presence / absence of replenishment between the two paper transports is determined by the presence / absence of an operation applied to the image forming apparatus in relation to the replenishment of the paper.   When | A−B | is greater than a predetermined value and A <B, and the length of B exceeds the maximum length of paper that can be set in the paper feeding unit of the image forming apparatus, A <B is set to the predetermined value. The image forming apparatus according to claim 1, wherein the notification is not performed even if the detection is continuously performed more than the number of times.   The set sheets are classified into a plurality of categories in an order that facilitates carrying or double feeding, and the number of times that A <B as the notification condition is continuously detected for the predetermined number of times or more is changed according to the category. The image forming apparatus according to claim 1.   When it is determined that the set paper is a paper of a specific paper type that can be easily fed or double-fed, a notification when A <B is given to a set paper other than the paper of the specific paper type The image forming apparatus according to claim 1, wherein: 6. The image forming apparatus according to claim 5 , wherein the predetermined number of times can be set variably. The notification to the user, any one of the image forming apparatus 6 according to claim 1, characterized in that to perform on the operation panel of the image forming apparatus. The notification to the user, any one of the image forming apparatus 6 according to claim 1, characterized in that it has to perform on a computer monitor screen for commanding image formation on the image forming apparatus.