JP4141470B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming method capable of reducing the burden on a user and continuing image formation even when double feeding occurs on a sheet on which an image is formed.

  In recent years, an image forming apparatus such as a digital copying machine having a scanner function, a printer function, a facsimile function, or the like, or a printer device is stored in image data transmitted from an external personal computer or a storage device such as an HDD in advance. A large amount of data has been processed at high speed by performing printing processing on recording paper based on the image data.

  However, when recording paper is transported from a paper feed cassette in order to perform printing processing on the recording paper, the recording paper is not separated and transported one by one due to the influence of humidity or static electricity. In some cases, multiple feeds that are transported in an overlapping manner occur. Conventionally, in the image forming apparatus, when double feeding occurs, the conveyance of the recording paper is stopped and the image forming process such as the exposure process, the developing process, the transfer process, and the fixing process is also stopped. There has been a problem that the job efficiency is reduced, or a recovery process performed by the user when a double feed occurs requires a lot of burden. In view of this, an image forming apparatus or the like that can take appropriate measures when double feeding occurs has been proposed.

  For example, if double feed is detected during conveyance of the recording paper, the image data that was planned to be formed on this recording paper is held without being formed on the recording paper for double feeding. In addition, by forming an image based on the image data held on the recording paper supplied from the recording paper supply unit, it is possible to ensure the continuity of the image forming process and reuse the recording paper related to the multi-feed. An image forming apparatus has been proposed (see Patent Document 1).

  Also, an image forming apparatus for creating a sheet bundle in which insertion sheets are inserted into recording sheets, and when a double feed of the insert sheets occurs, the sheet bundle that has been created normally and the sheet bundle that has not been created correctly due to the multiple feed An image forming apparatus that divides and discharges a bundle of sheets into separate discharge trays has been proposed (see Patent Document 2).

When double feeding is detected during transfer of transfer paper, the image forming conditions such as the fixing temperature or transfer conditions are changed according to the double feed detection value such as the thickness of the transfer paper or the length in the transport path direction. Thus, there has been proposed an image forming apparatus capable of forming an image without stopping the printing operation even when double feeding occurs (see Patent Document 3).
JP 2002-333797 A JP 2003-327361 A Japanese Patent Laid-Open No. 2005-15166

  However, in the image forming apparatus disclosed in Japanese Patent Laid-Open No. 2004-228688, although the recording paper for double feeding is discharged to another tray, the recording paper that is normally created before and after the occurrence of double feeding is discharged to the same tray. For this reason, the user searches for a regular part between the normally printed recording sheets of the recording sheet on which the image that is scheduled to be printed on the recording sheet related to the multi-feed is printed and discharged to a specific tray. There was a need to insert. In particular, when printing a large amount of recording paper, the work burden on the user is increased, and an image forming apparatus that can reduce the burden on the user has been desired.

  Further, in the image forming apparatus disclosed in Patent Document 2, when a double feed occurs in an insertion sheet to be inserted into a recording paper, a paper bundle that is normally created by discharging the paper bundle related to the double feed to another tray. However, there is no description about the processing when a multi-feed occurs on the conveyed recording paper when printing different images for each of the many recording papers. Therefore, there is a demand for an image forming apparatus that can reduce the burden on the user and continue image formation even when double feeding occurs on the recording paper when forming an image on a large amount of recording paper. It was.

  Further, in the image forming apparatus disclosed in Patent Document 3, when double feed is detected, the image forming operation is interrupted when the double feed detection value exceeds a set value. There is a risk of reducing the job efficiency of the entire apparatus. In particular, when a large amount of data needs to be processed at high speed, the job efficiency of the apparatus is significantly reduced, and an image forming apparatus that can continue image formation even when double feeding occurs is desired. It was rare.

The present invention has been made in view of such circumstances, and when a double feed of a sheet (for example, recording paper) is detected, the sheet on which an image is formed before the double feed is detected is the first. The sheet that has been discharged to the tray and conveyed after the double-feed sheet in which double-feed has been detected is discharged to the second tray, and whether or not the ongoing image formation can be interrupted is determined. Even if a feed is detected, the image formation process continues without wasting the ongoing image formation , preventing a reduction in job efficiency of the entire device, and the user taking corrective action when a double feed occurs. It is an object of the present invention to provide an image forming apparatus and an image forming method that can reduce the burden on the user without having to take the measures.

  Another object of the present invention is to discharge the multi-feed sheet to the third tray so that the multi-feed sheet can be easily distinguished from the sheet on which the image is normally formed. It is an object of the present invention to provide an image forming apparatus that can reduce the burden on the user without confirming all the sheets that have been used and removing unnecessary sheets such as removing unnecessary sheets.

  Another object of the present invention is to generate multiple feeds by switching the tray based on the determination result of whether or not there is a sheet on the tray when the detection unit detects the double feed. Even in this case, it is not necessary to stop the image forming process in order to discharge the sheet, and it is not necessary to check the order of the discharged sheets, and the image forming process can be continued without imposing a burden on the user. An object of the present invention is to provide an image forming apparatus capable of performing the above.

  Another object of the present invention is to interrupt image formation when it is determined that all trays have sheets, and when it is determined that there is no sheet in at least one of the trays, An image forming apparatus capable of continuing image forming processing without burdening the user without recognizing the order of discharged sheets even when multiple feeding occurs a plurality of times by resuming formation It is to provide.

  Another object of the present invention is to provide an output unit that outputs an instruction to remove a sheet on at least one of the trays when it is determined that all trays have sheets. When performing printing, even when multiple feeding occurs a plurality of times, an already formed sheet can be used for post-processing, and image forming processing can be continued without burdening the user Is to provide.

An image forming apparatus according to the present invention includes an image forming unit that forms an image on a sheet conveyed based on input image data, and a plurality of trays for discharging the sheet on which the image is formed. In the apparatus, an image processing unit that performs generation processing of image forming data used for image formation based on image data, a detection unit that detects double feeding of sheets, a control unit that controls switching of the tray , When double detection is detected by the detection means, there is a first determination means for determining the presence or absence of image formation data already generated by the image processing section, and image formation data already generated by the first determination means. If it is determined, depending on whether the image forming unit has completed the image formation on the sheet based on the data for the image forming, and a second determining means for determining an interruption possibility of image forming ongoing said system Means, when said detection means multifeed is detected, so as to discharge the sheet to form the images before the image forming unit is double feed on the basis of the data for image formation is detected in the first tray to Yes and, if it is determined that there is already generated image forming data by the first judging means, multifeed is conveyed after the double feed sheets detected, the image forming unit for image formation data seeded based on Yes in the so that to discharge the sheet having an image formed on the second tray, furthermore, waiting to determine the interrupt allowed by the second determination means, the double feeding is formed in the double feed sheet A sheet on which an image is formed based on image forming data corresponding to the image is configured to be discharged to the first tray .

  The image forming apparatus according to the present invention is characterized in that the control means is adapted to discharge the multi-feed sheet to a third tray.

The image forming apparatus according to the present invention includes a sheet determination unit that determines the presence / absence of a sheet on a tray, and the control unit determines the sheet as the second tray when the detection unit detects a double feed. The tray is determined to have no sheet by the means, and is switched.

The image forming apparatus according to the present invention, the image forming unit, when it is determined that there is a sheet on all the trays in said sheet determination means, to interrupt the image formation, further, at least one tray at said sheet determination means If it is determined that there is no sheet, the interrupted image formation is resumed, and the control means is adapted to discharge the sheet on which the image is formed by the resumed image formation to the tray. .

The image forming apparatus according to the present invention, when the double feed is detected by said detecting means, said when it is determined that there is a sheet on all the trays in the sheet determination means is at least one tray of the tray Output means for outputting an instruction to remove the sheet.

An image forming method according to the present invention includes an image forming unit that forms an image on a sheet conveyed based on input image data, and a plurality of trays for discharging the sheet on which the image is formed. In the image forming method of the apparatus, when image forming data is generated based on the image data by the image processing unit and double feeding of the sheet is detected by the detecting unit , the image forming unit overlaps based on the image forming data. feed is discharging the sheet on which the image is formed prior to being detected in the first tray, when it is determined that there is an image formation data seeded by the first determination means, overlap feed multifeed is detected A sheet conveyed after the sheet and on which an image is formed based on the image forming data generated by the image forming unit is discharged to the second tray, and is generated based on the image forming data generated by the second determination unit. Z Waiting for completion of image formation on the sheet to determine that the ongoing image formation can be interrupted, the image is formed based on the image forming data corresponding to the image related to the multi-feed formed on the multi-feed sheet. The sheet on which is formed is discharged to the first tray.

In the present invention, the detection means is transported in a state where two or more sheets are overlapped before an image is formed on the transported sheet (for example, recording paper). ) Is detected. The detection means uses, for example, an ultrasonic sensor, and includes a transmission unit that transmits ultrasonic waves and a reception unit that receives the transmitted ultrasonic waves on both sides of the conveyed sheet, and the magnitude of the energy of the received ultrasonic waves In response to this, double feeding of the sheet is detected . Control means, the image forming section based on the data for image formation, to discharge the sheet on which the image is formed before the double feed is detected in the first tray.

If double feed is detected by the detecting means, control means, when it is determined that the already generated image forming data by the first judging means is being transported after the double feed sheet double feed is detected, image forming unit to discharge the sheet on which the image is formed on the second tray on the basis of the imaging data seeded. When the second determination unit determines that there is image formation data generated by the first determination unit, the image forming unit determines whether image formation on the sheet has been completed based on the generated image formation data. Then, it is determined whether or not the ongoing image formation can be interrupted. For example, when double feeding is detected on the Nth (or page) sheet, processing for forming an image on the sheet precedes, and image formation for forming an image on the N + 3th sheets is already performed. If the image data has already been generated, the second determination unit can interrupt the image forming unit after the image forming unit forms an image on the (N + 3) th sheet (image formation) (interruption of ongoing image formation) Judged). The control unit waits for the second determination unit to determine that the interruption is possible, and first sets the sheet on which the image is formed based on the image forming data corresponding to the image related to the multi-feed formed on the multi-feed sheet. To the tray .

  In the present invention, the control means discharges the multi-feed sheet to the third tray. Thus, a multi-feed sheet, a sheet on which an image is normally formed before occurrence of multi-feed, and a sheet on which an image is normally formed after occurrence of multi-feed are distinguished.

In the present invention, when the double feed is detected, the control means switches the tray where it is determined that there is no sheet on the tray as a second tray.

  In the present invention, the image forming unit interrupts image formation when it is determined by the means that there are sheets on all trays. If it is determined that there is no sheet in at least one tray after all the sheets are present, the image forming unit resumes the interrupted image formation. The control unit discharges the sheet on which the image is formed by the restarted image formation to the tray.

  In the present invention, the output means outputs an instruction to remove a sheet on at least one of the trays when it is determined that there are sheets in all trays when double feeding is detected. (For example, an operation to specify a tray and remove a sheet is displayed).

  In the present invention, when the double feeding of the sheet is detected, the control unit discharges the sheet on which the image is formed after being conveyed after the double feeding sheet to a second tray different from the first tray. As a result, even when double feeding is detected, the image forming process on the sheet can be continued without stopping, and it is possible to prevent the job efficiency of the entire apparatus from being reduced due to double feeding. .

Further, by discharging the sheet on which the image is formed to a different tray before and after the detection of the double feed, the user can double-feed between the last page of the first tray and the first page of the second tray. Can be easily determined, and a sheet on which an image related to double feeding is formed is placed after the last page of the sheet discharged to the first tray, and then discharged to the second tray. By placing the sheets, the sheets can be easily arranged in the order of image formation, and the burden on the user can be reduced.
In addition, an image forming process is performed even when a multi-feed occurs by re-forming an image formed on or scheduled to be formed on the multi-feed sheet (an image related to the multi-feed) on a sheet conveyed after the multi-feed sheet. Can continue without stopping.
Further, when double feed is detected, it is determined whether or not the ongoing image formation can be interrupted, so that when the double feed occurs, the processing of the ongoing image formation is not wasted and the double feed is performed. The image which concerns on can be formed rapidly.
In addition, by discharging a sheet on which an image related to multi-feed is formed to the first tray, even when multi-feed occurs, the sheets on which images are formed can be arranged in the order of recording, and the user can perform multi-feed related. There is no need to distinguish the sheets on which the images are formed and rearrange them in the correct order, and the burden on the user can be reduced. In addition, especially when it is necessary to process a large amount of printing at high speed based on a large amount of image data, sheets already ejected in the order of recording can be quickly sent to post-printing post-processing, which reduces the burden on the user. It becomes possible to reduce significantly.

  In the present invention, by discharging the multi-feed sheet to the third tray, it is possible to prevent the multi-feed sheet from being mixed with the sheet on which the image is normally formed, and the multi-feed sheet which is no longer required by the user. Can be easily disposed of, and the burden on the user can be reduced.

  In the present invention, when double feeding is detected, the sheet is already detected even when multiple feeding occurs multiple times by switching the tray based on the determination result of whether or not there is a sheet on the tray. By switching to an empty tray without using the discharged tray, sheets can be distinguished and discharged, and the burden on the user can be reduced.

  In the present invention, when it is determined that there are sheets in all trays, image formation is interrupted, and after there is a sheet in all trays, there is no sheet in at least one of the trays. If determined, by restarting the interrupted image formation, the image formation can be resumed by waiting for the tray to be freed even if multiple feeding occurs, and the image formation is not burdened on the user. Processing can continue.

  In the present invention, when it is determined that there are sheets in all trays, a large amount of printing is performed by providing an output unit that outputs an instruction to remove a sheet on at least one of the trays. In this case, the image forming process can be continued without burdening the user even when multiple feeding occurs a plurality of times.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. FIG. 1 is a schematic front view of an image forming apparatus 100 according to the present invention. In the figure, reference numeral 1 denotes a placing table on which a document is placed. An automatic document feeder 2 having an image reading unit (not shown), a document placing tray 20 and the like is mounted on the upper side of the placing table 1. A scanner unit 3 having an image reading unit 30 is disposed below the mounting table 1.

  The image reading unit 30 includes a scanning unit that reciprocates in parallel along the lower surface of the mounting table 1, an imaging lens, a CCD line sensor (not shown) that is a photoelectric conversion element, and the like. The scanning unit includes a light source for irradiating a document placed on the placing table 1 or a document transported along a transport path with a laser beam, a mirror for guiding the laser light reflected by the document to a predetermined optical path, and the like. It has. The imaging lens images the laser beam guided from the scanning unit at a predetermined position on the CCD line sensor. The CCD line sensor photoelectrically converts the formed light image and outputs an electrical signal. The image reading unit 30 outputs, to the process control unit 43, data separated into R (red), G (green), and B (blue) color components based on the color image read from the document. The data output to the process control unit 43 is subjected to predetermined image data processing.

  On the lower side of the scanner unit 3, the image forming unit 4 is arranged with a conveyance path 7 for discharging the recording paper (sheet) on which the image is formed interposed therebetween. The image forming unit 4 includes an electrophotographic process unit 40, a fixing device 41, an optical writing unit 42, a process control unit 43, a recording paper storage unit 44 for storing recording paper, and the like.

  The electrophotographic process unit 40 is a photosensitive drum that is rotationally driven, a developing device that develops an electrostatic latent image formed on the surface of the photosensitive drum, and a transfer that transfers a toner image on the surface of the photosensitive drum to a recording sheet. Equipment.

  The fixing device 41 includes a fixing roller, and fixes the toner image on the recording paper by pressurizing the toner image transferred and formed on the recording paper at a high temperature.

  The optical writing unit 42 is a semiconductor laser that emits dot light modulated in accordance with image data read by the image reading unit 30 or image forming data generated based on image data acquired from an external personal computer or the like. Element, a polygon mirror for deflecting laser light emitted from the semiconductor laser element in the main scanning direction, and a lens and mirror for imaging the laser light deflected by the polygon mirror on the surface of the photosensitive drum (both (Not shown).

  The process control unit 43 includes a control unit 10 including a CPU that performs various arithmetic processes, a storage unit 12 including a ROM 13, a RAM 14, and an HDD, an image processing unit 15, and the like, and controls the entire image forming apparatus.

  Below the image forming unit 4, a multi-stage paper feeding unit 6 in which recording paper storage units 61,... When an output image is formed, a recording paper having a desired size is selected, and the selected recording paper is supplied to the electrophotographic process unit 40.

  The upstream side of the electrophotographic process unit 40 is provided with a registration roller 45 that transports the recording paper in accordance with the timing of image formation. The registration roller 45 is an upstream side of the registration roller 45 and contains recording paper. On the downstream side of the unit 44 and the multi-stage sheet feeding unit 6, there is provided a transmitter 8 a that transmits an ultrasonic wave and a receiver 8 b that receives the ultrasonic wave transmitted by the transmitter 8 a, which are opposed to each other with a conveyance path therebetween. A sonic sensor 8 is provided.

  A post-processing unit 5 that performs post-processing (for example, sorting processing, stapling processing, etc.) of recording paper is disposed between the scanner unit 3 and the multi-stage paper feeding unit 6 and on the side surface of the electrophotographic process unit 40. ing. The post-processing unit 5 outputs a discharge tray 51a (first tray), 51b (second tray), and 51c (third tray) for discharging recording paper on which an image is formed. Guides 52 and 53 for switching whether or not to discharge the recording paper, and a conveyance roller 50 for conveying the recording paper to be discharged are provided. Each of the trays 51a, 51b, 51c is provided with recording paper sensors 54a, 54b, 54c that detect the presence or absence of the recording paper discharged to the tray. The recording paper sensors 54a, 54b, 54c The presence or absence of the upper recording sheet is detected, and the detection result is output to the control unit 10.

  FIG. 2 is a block diagram showing an internal configuration of the image forming apparatus 100 according to the present invention. The image forming apparatus 100 includes a control unit 10 including a CPU that performs various arithmetic processes. The control unit 10 includes an image reading unit 30, a storage unit 11, a ROM 12, a RAM 13, an interface unit 14, an ultrasonic sensor 8, an image processing unit 15, a buffer memory 16, an image forming unit 4, and a guide driving unit via an internal bus. 17, the operation unit 18 and the like are connected, and the control unit 10 controls the operation of each of these hardware units.

  The ROM 12 stores a control program indicating a control procedure of the control unit 10 in advance. When the CPU of the control unit 10 loads the control program stored in the ROM 12 into the RAM 13, the control unit 10 controls the operation of the image forming apparatus 100 according to the control procedure indicated by the control program.

  The image reading unit 30 photoelectrically converts an image on a document with a CCD sensor, and converts the obtained analog signal into a digital signal with an A / D converter. The image reading unit 30 corrects the orientation characteristics of the light source at the time of reading the document, the sensitivity unevenness of the image sensor, and the like on the digital signal obtained by the conversion, and the image data obtained under the control of the control unit 10 Is stored in the storage unit 11.

  The image processing unit 15 records data (image forming data) for controlling semiconductor laser light for forming an electrostatic latent image on the surface of the photosensitive drum based on the image data stored in the storage unit 11. The data is generated for each sheet of paper, and the generated data is temporarily stored in the buffer memory 16. Each time the image forming data is generated, the image processing unit 15 outputs to the control unit 10 a count signal indicating how many recording sheets the data for forming is generated. As a result, the control unit 10 can determine how many sheets of image forming data have already been generated.

  The image forming unit 4 forms an image on the recording paper based on the image forming data stored in the buffer memory 16 under the control of the control unit 10. Each time an image is formed on a recording sheet, the image forming unit 4 outputs an output signal indicating the number of recording sheets on which the image is formed to the control unit 10. As a result, the control unit 10 can determine how many recording sheets of the already formed image forming data have been formed. The image forming unit 4 is not limited to the electrophotographic system, and may be any system such as an inkjet system or a thermal transfer system.

  The ultrasonic sensor 8 detects the double feeding of the recording paper in the conveyance path downstream of the joining point of the recording paper storage unit 44 and the multi-stage paper feeding unit 6 and upstream of the registration roller 45, and the detection result is a control unit. 10 is output. Double feeding of recording paper refers to a state in which two recording papers are transported in an overlapping manner where the recording papers are supposed to be separated and conveyed one by one. Details of double feeding will be described later with reference to FIG.

  FIG. 3 is a block diagram showing the configuration of the ultrasonic sensor 8. The ultrasonic sensor 8 includes, for example, an oscillation circuit 8c that generates a drive waveform having an oscillation frequency of about 220 kHz, an amplification circuit 8d that amplifies the drive waveform generated by the oscillation circuit 8c, a transmission unit 8a that transmits the drive waveform, and a transmission unit 8a. A receiving unit 8b that receives a signal transmitted from the receiver, a resonance circuit 8e that detects a signal received by the receiving unit 8b over a wide band (for example, 220 kHz ± 20 kHz), an amplification circuit 8f that amplifies the received signal, and an amplified signal An A / D conversion circuit 8g for converting to a digital signal is provided. The ultrasonic sensor 8 transmits a signal from the transmission unit 8a to the recording paper to be conveyed, and outputs a detection signal received by the reception unit 8b to the control unit 10, thereby generating a signal energy. Based on the size, the number of conveyed recording sheets, that is, double feed is detected. The means for detecting double feed is not limited to the ultrasonic sensor, and other sensors can also be used.

  The guide driving unit 17 switches the guides 52 and 53 under the control of the control unit 10. For example, when a required printing process is performed, the guides 52 and 53 are switched so that the recording paper on which the image is formed is discharged to the first tray 51a. When double feeding is detected, the guides 52 and 53 are switched so that the double fed recording paper is discharged to the third tray 51c. The guide sheets 52 and 53 are switched so that the recording paper that is conveyed after the double feed is detected and on which the image is formed is discharged to the first tray 51b.

  The operation unit 18 is a touch panel type operation panel, and includes various keys and switches that accept user operation instructions, and a liquid crystal display that displays information to be notified to the user. For example, when the double feed is detected and the empty tray is not available, the operation unit 18 displays an instruction to the user to remove the recording paper on the tray, and when printing is finished, the operation unit 18 is discharged to the tray. Displays the handling of recording paper such as the order of recording paper stacking.

  The interface unit 14 acquires image data from an information processing apparatus such as an external personal computer, and stores the acquired image data in the storage unit 11.

  FIG. 4 is an explanatory diagram showing an example of double feeding of recording paper. The arrows in the figure indicate the recording paper conveyance direction. FIG. 4A shows a case where recording sheets are normally conveyed one by one with a predetermined separation dimension. FIG. 4B shows a case where the leading edge of the first recording sheet overlaps with the leading edge of the second recording sheet. FIG. 4C shows a case where the leading edge of the first recording sheet overlaps with the leading edge of the second recording sheet.

  FIG. 5 is a time chart showing the level of the double feed detection signal when the leading ends of the recording sheets are displaced. The energy (for example, transmitted energy) of the signal received by the receiving unit 8b of the ultrasonic sensor 8 changes according to the number of recording sheets through which the signal passes. For example, when there is no recording paper, the energy of the received signal is E0, when there is one recording paper, the energy of the received signal is E1 (E0> E1), and when the two recording papers overlap, The energy of the signal is E2 (E1> E2). At time t1, it is detected that the next recording sheet has been conveyed because the signal energy has changed from E0 to E1. When double feeding of recording paper occurs, for example, at time t2, the signal energy changes from E1 to E2. It is possible to detect that the two recording sheets are double-fed while their leading ends are deviated from the difference in energy level of the received signals. At time t3, the signal energy changes from E2 to E1.

  Based on the conveyance speed of the recording paper and the time difference between the times t2 and t1, it is also possible to calculate how much the recording paper is shifted and double fed.

  FIG. 6 is a time chart showing the relationship of double feed detection signals when the leading ends of the recording sheets overlap. At time t4, the signal energy changes from E0 to E2. Based on the difference in energy level of the received signal, it can be detected that two recording sheets have been double-fed while the leading end of the next recording sheet is overlapped. At time t5, the signal energy changes from E2 to E0.

  The control unit 10 can determine how many sheets of recording paper have been multi-fed based on the detection result (detection signal level) output from the ultrasonic sensor 8. When the double feed is detected, the control unit 10 determines whether the image forming data has already been processed, that is, up to what number of recording sheets, based on the count signal output from the image processing unit 15. It is determined whether it has been generated. In addition, when the multi-feed is detected, the control unit 10 determines how many recording sheets the image has been formed based on the output signal output from the image forming unit 4.

  When the double feed is detected, the control unit 10 generates the image forming data based on the generated image forming data when the generation of the image forming data is already completed and there is a recording sheet in which the image forming is not completed. The image forming unit 4 continues the formation. The image forming unit 4 outputs a signal to the control unit 10 in order to notify the end of the process of forming an image on the recording paper based on the generated image forming data.

  When the control unit 10 receives a signal from the image forming unit 4, the control unit 10 determines that image formation can be interrupted by image formation, and an image that cannot be formed by double feeding (an image related to double feeding). The image processing unit 15 and the image forming unit 4 are controlled so that they are formed again on the recording paper. The control unit 10 again forms an image that could not be formed by double feeding on a recording sheet, and then controls the image processing unit 15 and the image forming unit 4 to continue forming the remaining images.

  FIG. 7 is a time chart showing the image forming process. The storage unit 11 stores in advance image data D1, D2,... For forming images on recording sheets 1, 2,. The image processing unit 15 acquires image data from the storage unit 11 and corresponds to the image forming data V1, V2,... For forming images on the recording sheets 1, 2,. ) Is generated. The image forming unit 4 forms an image on the recording paper 1, 2,... Based on the image forming data V1, V2,.

  Based on the image forming data V1 generated by the image processing unit 15, the image forming unit 4 forms an image on the recording paper 1, and the recording paper 1 on which the image is formed is discharged to the first tray 51a. . For example, when double feeding is detected at time t6 while the recording paper 2 is being transported, the control unit 10 switches the tray to the third tray 51c and discharges the double feeding recording paper to the tray 51c. Further, the control unit 10 outputs a holding signal to the image processing unit 15 so as to hold the image data D2 (or image forming data V2) used for forming an image on the recording paper 2.

  Note that the control unit 10 determines whether or not image formation (writing) on the double-fed recording paper can be stopped when double feeding is detected. The image formation is stopped in order to prevent an image formation. If the image formation cannot be stopped, an image is formed on the multi-feed recording paper, and the multi-feed recording paper is discharged to the tray 51c. When an image is formed on a multi-feed recording paper, for example, when an image is formed on two overlapping recording papers, conditions relating to the image formation (for example, transfer current, fixing temperature, etc.) are one recording paper. Therefore, the image cannot be formed under normal conditions, and the multi-feed recording paper is discharged to the tray 51c regardless of whether image formation is possible.

  When the control unit 10 determines that the image forming data V4 up to the recording sheet 4 has already been generated by the image processing unit 15 at the time t6 when the double feed is detected, the control unit 10 An instruction is given to continue image formation on recording sheets 3 and 4. The control unit 10 switches the tray for discharging the recording sheets 3 and 4 to the second tray 51b. Thereby, the recording paper after double feeding is discharged to a second tray different from the first tray from which the recording paper before double feeding is discharged, and the double feeding recording paper is different from the first and second trays. It is discharged to the third tray.

  When the image forming unit 4 finishes image formation on the recording paper 4, the image forming unit 4 outputs a signal indicating that continuous image formation has been completed to the control unit 10. As a result, the control unit 10 determines that the ongoing image formation can be interrupted, and the image processing unit 15 and the image forming unit 4 are for image formation of an image that could not be formed by double feeding. Based on the data V2, control is performed to form an image on the recording paper again, and the tray is switched to the first tray 51a. As a result, the image scheduled to be formed on the multi-feed recording paper is formed again on the recording paper 2 and is discharged to the first tray 51a.

  The controller 10 switches the tray to the second tray, forms an image on the recording paper 5,..., And discharges the recording paper 5, on which the image is formed, to the tray 51b.

  Next, the operation of the image forming apparatus 100 according to the present invention will be described. FIGS. 8 and 9 are flowcharts showing a procedure of processing executed by the image forming apparatus 100 when double feeding of recording sheets is detected. The control unit 10 determines whether there is a print instruction based on information input from the operation unit 18 (S11). When there is no print instruction (NO in S11), the control unit 10 continues the process of step S11 and waits for a print instruction.

  When there is a print instruction (YES in S11), the control unit 10 conveys the recording paper (S12). The control unit 10 determines whether or not double feeding of recording paper is detected (S13). When the double feeding of the recording paper is not detected (NO in S13), the control unit 10 performs printing on the recording paper (S14), and discharges the printed recording paper to the tray (for example, the first tray 51a). (S15).

  The control unit 10 determines whether or not the page is the last page (S16). If the page is not the last page (NO in S16), the process from step S12 is continued. If it is the last page (YES in S16), the control unit 10 determines whether or not there is a record of double-feed pages (S17). If there is a record of double-feed pages (YES in S17), the control unit 10 discharges it to the tray. The double feed notification for indicating the handling of the recorded paper is performed (S18), and the process is terminated. If there is no double-feed page recording (NO in S17), the control unit 10 ends the process.

  On the other hand, when double feed is detected (YES in S13), the control unit 10 records a double feed page that is a page of the double-fed recording paper (S19), and controls the image processing unit 15 to perform double feed. Image data for an image to be formed on the recording paper is held (S20). The control unit 10 determines whether writing on the multi-feed recording paper (for example, image formation on the recording paper or image formation on the photosensitive drum) can be stopped (S21).

  When the writing can be stopped (YES in S21), the control unit 10 stops writing the image (S22), and switches the tray (for example, from the first tray 51a to the third tray 51c) (S24). Then, the multi-feed recording paper is discharged to the third tray (S25). When the writing stop is not possible (NO in S21), the control unit 10 writes the image (S23), and continues the processing from step S24.

  The control unit 10 determines whether the image forming data has already been generated by the image processing unit 15 (S26). If the image forming data has already been generated (YES in S26), the recording paper is It is determined whether there is an empty tray that has not been ejected (S27). If there is no empty tray (NO in S27), the control unit 10 displays a tray operation so as to remove the recording paper from the tray and create an empty tray (S28), and the process from step S27 is continued to create an empty tray. Wait until.

  When there is an empty tray (YES in S27), the control unit 10 switches the tray (for example, from the third tray 51c to the second tray 51b) (S29) and prints on the recording paper (S30). The control unit 10 discharges the printed recording paper to a tray (for example, the second tray 51b) (S31), and switches the tray again (for example, from the second tray 51b to the first tray 51a) (S32). ).

  On the other hand, if the image forming data has not been generated (NO in S26), the control unit 10 continues the processing from step S32. The control unit 10 reprints the contents to be printed on the multi-feed recording paper (S33), discharges the printed recording paper (S34), and moves the tray (for example, from the first tray 51a to the second tray 51b). ) Switching (S35), the processing after step S16 is continued.

  FIG. 10 is a schematic diagram showing an example of a screen displaying a tray operation when there is no empty tray. As shown in the drawing, when double feeding of recording paper is detected and there is no empty tray, a screen showing an operation for removing the recording paper from the tray is displayed on the liquid crystal display of the operation unit 18. On the display screen, for example, sentences such as “Multiple feed occurred during recording” and “Please remove all recording paper in the xx tray” are displayed. When the user removes the recording paper from the instructed tray, the image forming apparatus 100 continues the image formation and discharges the recording paper to the tray.

  FIG. 11 is a schematic diagram showing an example of a screen displayed on the display screen when notifying the double feed. As shown in the figure, when double feeding of recording paper is detected, a screen for notifying double feeding of recording paper is displayed on the liquid crystal display of the operation unit 18. On the display screen, for example, “Multiple feeding occurred during recording”, “Please stack the recording paper in the second tray on the recording paper in the first tray”, “Discard the recording paper in the third tray "Please" is displayed. By operating according to the instructions on the display screen, the user can easily distinguish the multi-feed recording paper from the normally printed recording paper even when double feeding occurs, and the printed recording paper It can be easily arranged in a regular order.

  FIG. 12 is a schematic diagram showing an example of recording paper discharge when double feeding occurs. The post-processing unit 5 is provided with three trays (a first tray, a second tray, and a third tray). The number of pages (number of sheets) of the recording paper discharged to each tray is represented by 1, 2,..., N (N is the last page). In the figure, a case where double feeding occurs on the 11th and 12th sheets of recording paper is shown. The numbers enclosed in the squares indicate the number of pages (number of sheets) of the recording paper on which double feeding has occurred. The numbers enclosed in a circle indicate the number of pages of the recording paper on which an image formed on the double-feed recording paper is printed again when double feeding occurs.

  The recording sheets (1, 2,..., 10) printed before the double feed occurs are discharged to the first tray. The recording paper (13, 14,... N) conveyed after the multi-feed recording paper is discharged to the second tray. The multi-feed recording sheets (11, 12) are discharged to the third tray. The recording paper (11, 12) printed again is discharged to the first tray.

  FIG. 13 is a schematic diagram illustrating an example of recording paper discharge when double feeding occurs twice. The post-processing unit 5 is provided with three trays (a first tray, a second tray, and a third tray). The number of pages (number of sheets) of the recording paper discharged to each tray is represented by 1, 2,..., N (N is the last page). In the figure, a case where the first double feed occurs in the 11th and 12th sheets of recording paper and the second double feed occurs in the 20th and 21st sheets is shown. The numbers enclosed in the squares indicate the number of pages of the recording paper on which double feeding has occurred. The numbers enclosed in a circle indicate the number of pages of the recording paper on which an image formed on the double-feed recording paper is printed again when double feeding occurs.

  The recording sheets (1, 2,..., 10) printed before the double feed occurs are discharged to the first tray. After the first double feed, the recording paper (13, 14,... 19) printed before the second double feed is discharged to the second tray. The multi-feed recording sheets (11, 12) are discharged to the third tray. The recording paper (11, 12) printed again is discharged to the first tray.

  When the second double feed occurs, the recording paper has already been discharged from the first, second, and third trays, and there is no empty tray. For example, the recording paper on the first tray ( The tray operation is displayed to the user so as to remove 1, 2,. After the user removes the recording paper (1, 2,..., 12) in the first tray, the recording paper (22, 23,... N) conveyed after the multi-feed recording paper is transferred to the first tray. Discharged. The double feed recording paper (20, 21) is discharged to the third tray. The recording paper (20, 21) printed again is discharged to the second tray.

  As a result, even when multiple feeds occur multiple times, the multi-feed recording paper can be easily distinguished from the normally printed recording paper by operating according to the instructions on the display screen. The recorded sheets can be easily arranged in a regular order.

  As described above, according to the present invention, even when double feeding is detected, the image forming process on the recording paper can be continued without being stopped. It is possible to prevent the efficiency from decreasing. In addition, it is possible to easily distinguish between the recording paper that has been double-fed and the recording paper that has been normally printed, and the recording paper can be easily arranged in the printing order, thereby reducing the burden on the user. it can. In addition, when double feeding occurs, an image formed on the multi-feed recording paper can be quickly formed again without wasting the ongoing image forming process. In addition, especially when it is necessary to process a large amount of printing at a high speed based on a large amount of image data, the recording paper that has already been ejected in the order of recording can be removed from the tray and can be quickly sent to post-processing after printing. The burden on the user can be significantly reduced.

  In the above-described embodiment, the ultrasonic sensor is used as the means for detecting the double feeding of the recording paper. However, the present invention is not limited to this. For example, the optical sensor may be used. Also good. However, when the optical sensor is used, the length of the recording paper in the conveyance direction is detected, and when the distance between the leading edge and the trailing edge of the recording paper is larger than the size of the document, it is detected that the paper is double fed. For this reason, when two recording sheets are completely overlapped, there is a possibility that they cannot be detected, and the ultrasonic sensor is excellent in terms of detection accuracy.

  In the above-described embodiment, the case where three trays are provided has been described. However, the number of trays is not limited to this, and a configuration including four or more trays may be used. By increasing the number of trays, if multiple feeds occur multiple times, when there are no more empty trays, an instruction is given to remove the recording paper from the trays. The recording paper can be discharged quickly.

  In the above-described embodiment, the tray for discharging the recording paper is switched by the guide. However, the switching of the tray is not limited to this, and recording is performed on a predetermined tray by moving the conveyance path itself. A configuration may be adopted in which the paper is discharged, or a configuration in which the discharge destination of the recording paper is switched by moving the discharge tray.

1 is a schematic front view of an image forming apparatus according to the present invention. 1 is a block diagram showing an internal configuration of an image forming apparatus according to the present invention. It is a block diagram which shows the structure of an ultrasonic sensor. FIG. 6 is an explanatory diagram illustrating an example of double feeding of recording paper. 6 is a time chart showing the level of a double feed detection signal when the leading ends of the recording paper are displaced from each other. 6 is a time chart showing the relationship of double feed detection signals when the leading ends of recording paper overlap each other. It is a time chart which shows the process of image formation. 6 is a flowchart illustrating a procedure of processing executed by the image forming apparatus when double feeding of recording paper is detected. 6 is a flowchart illustrating a procedure of processing executed by the image forming apparatus when double feeding of recording paper is detected. It is a schematic diagram which shows an example of the screen which displays tray operation when there is no empty tray. It is a schematic diagram which shows an example of the screen displayed on a display screen when alerting | reporting double feeding. FIG. 10 is a schematic diagram illustrating an example of recording paper discharge when double feeding occurs. FIG. 6 is a schematic diagram illustrating an example of recording paper discharge when double feeding occurs twice.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Document conveyance part 3 Scanner part 4 Image formation part 5 Post-processing part 6 Multi-stage paper feeding unit 8 Ultrasonic sensor 10 Control part 11 Storage part 14 Interface part 15 Image processing part 16 Buffer memory 17 Guide drive part 18 Operation part 30 Image reading Section 52, 53 Guide 51a, 51b, 51c Tray 54a, 54b, 54c Recording paper sensor

Claims (6)

In an image forming apparatus including an image forming unit that forms an image on a sheet conveyed based on input image data, and a plurality of trays for discharging the sheet on which the image is formed.
An image processing unit for generating image forming data used for image formation based on the image data;
Detection means for detecting double feeding of sheets;
Control means for controlling switching of the tray ;
A first determination unit that determines the presence or absence of image forming data generated by the image processing unit when double detection is detected by the detection unit;
When it is determined by the first determination means that there is already generated image forming data, the image forming unit continues image formation depending on whether the image forming unit has completed image formation on the sheet based on the image forming data. And a second determination means for determining whether or not the interruption is possible ,
The control means includes
If double feed is detected by said detecting means, there the image forming unit so as to discharge the sheet to form the images before double feeding based on data for image formation is detected in the first tray ,
If it is determined that there is already generated image forming data by the first judging means, multifeed is conveyed after the double feed sheets detected, the image based on the image formation data of the image forming unit is Generated the formed sheet Yes in the so that to discharge the second tray,
Further, after waiting for the second determination means to determine that the interruption is possible, the sheet on which the image is formed based on the image forming data corresponding to the image related to the multi-feed formed on the multi-feed sheet is changed to the first An image forming apparatus configured to be discharged to a tray . The control means includes
The image forming apparatus according to claim 1, wherein the multi-feed sheet is discharged to a third tray. A sheet determining means for determining the presence or absence of a sheet on the tray;
The control means includes
If double feed is detected by the detection means, the image forming apparatus according to claim 1 or claim 2, characterized in that switching to the tray it is determined that there is no sheet in the sheet determination means as said second tray . The image forming unit includes:
When it is determined by the sheet determination means that there are sheets in all trays, image formation is interrupted,
Further, when it is determined by the sheet determining means that there is no sheet in at least one tray, the interrupted image formation is resumed,
The control means includes
4. The image forming apparatus according to claim 3 , wherein a sheet on which an image is formed by restarted image formation is discharged to the tray. An output that outputs an instruction to remove a sheet on at least one of the trays when the sheet determination unit determines that all trays have sheets when the detection unit detects double feeding. The image forming apparatus according to claim 4 , further comprising a unit. In an image forming method of an image forming apparatus comprising: an image forming unit that forms an image on a sheet conveyed based on input image data ; and a plurality of trays for discharging the sheet on which the image is formed.
The image processing unit generates image formation data based on the image data ,
When the detection unit detects the double feeding of the sheet, the image forming unit discharges the sheet on which the image is formed before the double feeding is detected based on the image forming data to the first tray,
If it is determined that there is the image formation data Seeded by the first determining means, is conveyed after the double feed sheet double feed is detected, the image forming section based on the image formation data of the Generated image Is discharged to the second tray,
The multi-feed formed on the multi-feed sheet waits until it is determined that the image formation on the sheet based on the image forming data already generated by the second determination means has been completed, so that the ongoing image formation can be interrupted. An image forming method comprising discharging a sheet on which an image has been formed based on image forming data corresponding to the image to the first tray.

Images