JP6200277B2 - Image forming apparatus and image forming system - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming system for detecting a multi-feed for each paper type in an image forming apparatus and an image forming system for discharging printed matter printed on a plurality of types of paper based on a print job.

  In an image forming apparatus that discharges printed matter printed on paper based on image data, a multifeed sensor comprising a light emitting sensor and a light receiving sensor is provided on the transport path, and when the paper is transported along the transport path, A multi-feed sensor detects the amount of light transmitted through the paper and the amount of reflected light, etc., and detects the overlap (double feed) of two or more sheets based on the change in the amount of light. Has been proposed (see, for example, Patent Document 1).

  In this image forming apparatus, a histogram of the amount of light detected when the first sheet is conveyed is created, and a value of a predetermined ratio with respect to the maximum amount of light in the frequency in the histogram is used as a reference value for double feed detection. The same reference value for the first sheet is stored, and a histogram is created in the same way when the second and subsequent sheets are transported. The value is calculated as a comparison value, and the calculated comparison value is compared with the stored reference value to detect double feeding of paper.

Japanese Patent No. 3341866

  In the image forming apparatus described in Patent Document 1 described above, the reference value calculated when the first sheet is transported is compared with the comparison value calculated when the second and subsequent sheets are transported, and the double feed is performed. Detection is performed.

  Here, in an image forming system in which an enclosing sealing device is connected to the downstream side of the image forming apparatus, when the enclosing sealing process is executed by the enclosing sealing device to create a printed material set (hereinafter also referred to as “sealed letter”), Different types of paper for envelopes and contents are supplied alternately to the image forming apparatus.

  Therefore, when executing the enclosing sealing process, the technique described in Japanese Patent Application Laid-Open No. 2004-151867 that determines double feeding by comparing the reference value of the first sheet and the comparison value of the subsequent sheets is simply applied to the image forming apparatus. There is a problem that double feed cannot be detected correctly only by doing.

  In addition, when a sealed letter is created by a sealed sealing device, one envelope sheet is used for each mail. Therefore, whether or not a double feed has occurred in the first sealed letter is determined by the second envelope. The judgment can be made only after the paper is supplied. That is, it takes a certain amount of time to determine whether or not double feed has occurred in the first sealed letter. Therefore, the created first letter may be discharged to the letter tray before it is determined whether or not double feeding has occurred in the first letter. When a multi-feed sealed letter is discharged into a sealed tray where other sealed letters are stored, it may be difficult or difficult to find a sealed letter that has been double-fed. is there.

  The present invention has been made in view of such a problem. First, it is possible to reliably detect the presence or absence of double feeding for each type of paper, and secondly, the first one. An object of the present invention is to provide an image forming apparatus and an image forming system that can easily identify the first sealed letter with the possibility of double feeding when the sealed letter has the possibility of double feeding.

  In order to achieve the above object, a first feature of an image forming apparatus according to the present invention is to receive a print job including instructions for creating a plurality of envelopes composed of envelopes and contents, and envelope data according to the order of instructions And an image forming apparatus that prints and discharges content data on different sheets of paper, and detects the amount of light that is transmitted or reflected by irradiating light to each of the sheets on which the envelope data and the content data are printed. A double feed for comparing the amount of light detected by the detection unit with respect to the first and second printed sheets for each paper type and determining the presence or absence of double feed for each sheet based on the comparison result And a determination means.

  In addition, a first feature of the image forming system according to the present invention is an image forming system in which an enclosing sealing device is connected to a downstream side of the image forming apparatus, and the enclosing sealing device is discharged from the image forming apparatus. An encapsulated sealing unit that receives a sheet to be processed and executes a sealed sealing process for each of a plurality of sheets based on the print job to create a sealed letter; and a sealed tray that discharges the sealed letter created by the sealed sealing part; A discharge path that conveys and discharges the sealed letter created by the encapsulated sealing part to the sealed letter tray, and is created in at least one of the image forming apparatus and the sealed encapsulating apparatus. It is further provided with a conveyance control means for controlling the sealed letter so as to be stopped on the discharge path.

  A second feature of the image forming system according to the present invention is that the conveyance control unit compares the light amounts of the sheets used in the first and second sealed letters by the multi-feed determining unit. Thus, the conveyance of the first sealed letter is stopped until the determination of the presence or absence of the occurrence of double feeding in the first sealed letter is completed, and the double feeding is generated in the first sealed letter by the multi-feed determining means. If it is determined that it is not, the control is such that the conveyance of the first sealed letter is resumed and discharged to the sealed letter tray.

  According to the first feature of the image forming apparatus according to the present invention, the double feed determination unit compares the light amount with respect to the first and second printed sheets for each sheet type, and for each sheet based on the comparison result. Therefore, even in an image forming apparatus in which different types of paper are supplied in a mixed manner, it is possible to reliably detect the presence of double feeding for each type of paper.

  Further, according to the first feature of the image forming system according to the present invention, since the first sealed letter after the sealing process is stopped on the discharge path before the sealed letter tray, there is one possibility of double feeding. The sealed letter will stay in a specific place without being ejected to the sealed tray. Therefore, if it is determined that double feed has occurred in the first sealed letter by comparison with the amount of light of the paper used in the second sealed letter, the first sealed letter that is being multi-fed Is easy to find and remove.

  Further, according to the second feature of the image forming system according to the present invention, the sheets used in the first and second sealed letters are compared, so that the double-feed occurrence in the first sealed letter occurs. Since the transport of the first sealed letter is stopped until the presence / absence determination is completed, if a double feed occurs within the first sealed letter, the detected and removed sealed letter is detected Becomes easier. In addition, when the multi-feed determining unit determines that the multi-feed does not occur in the first sealed letter, the transport control means resumes the first sealed letter and discharges it to the sealed tray. The print job process can be continued without bothering the user.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram schematically showing a configuration of an entire image forming system including an image forming apparatus according to a first embodiment of the present invention. 3 is a flowchart illustrating an operation of an image forming system including an image forming apparatus and an enclosing sealing apparatus according to the first exemplary embodiment. (A) is a diagram showing a case where the first sealed letter determined to be double-fed is discharged to the sealed letter tray, and (b) is a first letter judged to be double-fed by the image forming apparatus of the first embodiment. It is a figure which shows the case where a sealed letter is stopped on a discharge belt. It is a flowchart which shows operation | movement of the image forming system which consists of the image forming apparatus of Example 2 which concerns on this invention, and an enclosure sealing device. FIG. 6 is an enlarged view illustrating a connection portion between an image forming apparatus and an encapsulating sealing apparatus according to Embodiment 2. FIG. 10 is a diagram illustrating an overlapping relationship between a content sheet or an envelope sheet and an inkjet head at a connection portion between the image forming apparatus and the sealing apparatus according to the second embodiment.

  Hereinafter, an image forming system 1 including the image forming apparatus 3 and the enclosing sealing device 5 according to the first and second embodiments of the present invention will be described. In the description, “upstream” means upstream when viewed from the conveyance direction of the content paper P1, etc., and “downstream” means downstream when viewed from the conveyance direction of the content paper, etc. In the figure, “L” indicates the left direction, “R” indicates the right direction, “FF” indicates the front direction, and “FR” indicates the rear direction.

Example 1
FIG. 1 is an explanatory diagram schematically showing the overall configuration of an image forming system 1 including an image forming apparatus 3 and an enclosing sealing device 5 according to a first embodiment of the present invention.

  As shown in FIG. 1, the image forming system 1 including the image forming apparatus 3 according to the first embodiment of the present invention performs printing on a plurality of content sheets P1 and an envelope sheet P2, and the contents of a plurality of printed sheets. In this system, the contents and envelopes are formed from the paper sheet P1 and the envelope paper P2, respectively, and the envelope is sealed in a state in which the contents are sealed, thereby producing a sealed letter M which is a printed material set. That is, the image forming system 1 is provided on the downstream side (back stage) of the image forming apparatus 3 that performs printing on a plurality of content sheets P1 and envelope sheets P2, and the image forming apparatus 3 Encapsulation for producing envelope M, which is a set of printed matter, by receiving the contents and envelopes, which are printed content paper P1 and envelope paper P2, from the inside and executing the sealing process for sealing the envelope with the contents sealed It is comprised from the combination with the sealing device 5.

<Configuration of image forming apparatus 3>
The image forming apparatus 3 includes an image forming apparatus casing 7, and contents image data (a part of print data) and envelope image data (print data of the print data) of the print job are included in the image forming apparatus casing 7. Ink-jet printing unit 9 that performs printing on content paper P1 and envelope paper P2 based on (part) is provided, and this printing unit 9 ejects ink of each color of black, cyan, magenta, and yellow An inkjet head 11 is provided.

  Further, in the image forming apparatus casing 7, a loop-shaped print transport path 13 for transporting the content sheet P1 and the envelope sheet P2 is provided so as to surround the printing unit 9, and the image forming apparatus casing 7, a plurality of first transport roller pairs (not shown) that sandwich and transport the content paper P1 and the envelope paper P2 are provided at intervals along the print transport path 13. The plurality of first transport roller pairs are rotated by driving an appropriate first transport motor (not shown).

  Below the printing unit 9 in the image forming apparatus housing 7, a plurality of content sheet feeding units 15 that sequentially feed a plurality of content sheets P 1 to the printing unit 9 side (printing conveyance path 13 side). Are provided stepwise in the vertical direction. Each content paper feeding unit 15 sequentially feeds a plurality of content papers P1 stacked on the paper feeding tray 17 to the printing unit 9 side. A plurality of paper feed rollers 19 are provided, and the plurality of paper feed rollers 19 rotate by driving an appropriate content paper feed motor (not shown).

  The image forming apparatus housing 7 is provided with a paper feed transport path 21 for transporting the content paper P1 to the printing unit 9 side. Three branch portions 21a are provided on the end side. The end of each branch portion 21 a of the paper feed conveyance path 21 is connected to the corresponding content paper feed section 15, and the upstream end (tip) of the paper feed conveyance path 21 is connected to the print conveyance path 13. ing. A plurality of second transport roller pairs (not shown) that sandwich and transport the content sheet P1 are spaced at positions along the paper feed transport path 21 in the image forming apparatus casing 7. The plurality of second transport roller pairs are rotated by driving an appropriate second transport motor (not shown).

  On the left side of the image forming apparatus casing 7, an envelope paper feeding unit 23 for feeding the envelope paper P2 to the printing unit 9 side (printing conveyance path 13 side) is provided. The envelope paper feed unit 23 includes a paper feed tray 25 for stacking a plurality of envelope papers P2, and a plurality of paper feed rollers 27 for feeding the envelope paper P2 stacked on the paper feed tray 25 to the printing unit 9 side. The plurality of paper feed rollers 27 are rotated by driving an appropriate envelope paper feed motor (not shown).

  Further, in the image forming apparatus casing 7, a paper feed conveyance path 29 for conveying the envelope paper P <b> 2 to the printing unit 9 side is provided, and an upstream end (base end part) of the paper feed conveyance path 29 is provided. ) Is connected to the envelope paper feed section 23, and the downstream end (tip) of the paper feed transport path 29 is connected to the print transport path 13. A plurality of third transport roller pairs (not shown) that sandwich and transport the envelope paper P <b> 2 are provided at intervals along the paper feed transport path 29 in the image forming apparatus housing 7. The plurality of third transport roller pairs are rotated by driving an appropriate third transport motor (not shown).

  In front of the print conveyance path 13, a registration roller pair 13 a that adjusts the feeding timing of the recording medium such as the content paper P1 and the envelope paper P2 to the print conveyance path 13 and the upstream side of the registration roller pair 13 a are close to each other. A registration sensor 13b is provided that detects the arrival of the recording medium such as the content paper P1 and the envelope paper P2 to the registration roller pair 13a.

  Further, between the registration roller pair 13a and the belt platen roller (paper pressing roller) 13c, light is irradiated from the light emitting side to the recording medium such as the content paper P1 and the envelope paper P2 conveyed on the printing conveyance path 13. Then, a double feed sensor 13d for detecting the transmission amount on the light receiving side is provided. Note that the registration sensor 13b and the multifeed sensor 13d can use not only a transmissive sensor but also various other sensors such as a reflective sensor. The double feed sensor 13d also has a function as a so-called first top edge sensor that controls the start of ink ejection to an inkjet head 11 provided in a printing unit 9 described later.

  In the upper left portion of the print conveyance path 13, a cassette 31 is provided for temporarily storing the content paper P1 and the envelope paper P2. A switchback conveyance path 33 is provided for reversing the contents sheet P1 and the envelope sheet P2 from the left part in the image forming apparatus housing 7 to the cassette 31 and conveying them to the printing unit 9 side. The base end portion of the switchback conveyance path 33 can be connected to and disconnected from the print conveyance path 13 by the operation of a known switchback flapper (not shown).

  In the left part of the image forming apparatus casing 7, there is a communication for conveying the contents paper P1 and the envelope paper P2 printed and discharged from the printing conveyance path 13 to the enclosing and sealing apparatus 5 side (right direction). A paper discharge sensor 35a is provided for detecting whether or not the printed content paper P1 and the envelope paper P2 have been discharged to the conveyance path 35 and the sealed sealing device 5 side. The end portion (base end portion) can be connected to and disconnected from the print conveyance path 13 by the operation of a known communication flapper (not shown). Further, a plurality of fourth transport roller pairs (not shown) that sandwich and transport the content paper P1 and the envelope paper P2 are spaced at positions along the communication transport path 35 in the image forming apparatus casing 7. The plurality of fourth transport roller pairs are rotated by driving an appropriate fourth transport motor (not shown).

  An image forming controller 37 having a memory for storing a control program related to image formation and a CPU for executing a control program related to image formation is provided at an appropriate position in the image forming apparatus housing 7. The image forming controller 37 controls the overall operation of the image forming apparatus 3 such as the printing unit 9, the content paper feeding unit 15, and the envelope paper feeding unit 23 based on the print data of each job, and also relates to the present invention. It functions as a double feed determination means. Further, the image forming controller 37 may function as a conveyance control unit according to the present invention.

<Configuration of Encapsulation Sealing Device 5>
As shown in FIG. 1, the encapsulating / sealing device 5 includes an enclosing / sealing device housing 39, and the encapsulating / sealing device housing 39 is sent out from the communication conveyance path 35 (image forming device 3). An introduction conveyance path 41 for conveying the printed content sheet P1 and envelope sheet P2 to the right is provided, and an upstream end (base end) of the introduction conveyance path 41 is connected to the communication conveyance path 35. It is connected to the downstream end (tip). In addition, a plurality of fifth transport roller pairs (not shown) that sandwich and transport the printed content paper P1 and the envelope paper P2 at a position along the introduction transport path 41 in the enclosure sealing device housing 39. ) Are provided at intervals, and the plurality of fifth transport roller pairs are rotated by driving an appropriate fifth transport motor (not shown).

  A content paper transport path 43 for transporting the printed content paper P1 (hereinafter, abbreviated as “content paper P1” as appropriate) is provided in the enclosure sealing device housing 39. The upstream end portion (base end portion) of the sheet conveyance path 43 can be connected to and disconnected from the downstream end section (tip end portion) of the introduction conveyance path 41 by operation of a known sealing and sealing flapper. A plurality of sixth transport roller pairs (not shown) that sandwich and transport the printed matter or the like of the content paper P1 at a position along the content paper transport path 43 in the enclosing and sealing device housing 39 are spaced apart. The plurality of sixth transport roller pairs are provided in a space, and are rotated by driving an appropriate sixth transport motor (not shown).

  An envelope paper conveyance path 45 for conveying printed envelope paper P2 (hereinafter, abbreviated as envelope paper P2 as appropriate) is provided above the content paper conveyance path 43 in the enclosure sealing device housing 39. The upstream end portion (base end portion) of the envelope paper conveyance path 45 can be connected to and disconnected from the downstream end portion of the introduction conveyance path 41 by the operation of the above-described sealing flapper. A plurality of seventh transport roller pairs (not shown) that sandwich and transport the printed envelope paper P2 are spaced apart from each other at positions along the envelope paper transport path 45 in the enclosing and sealing device housing 39. The plurality of seventh transport roller pairs are rotated by driving an appropriate seventh transport motor (not shown).

  The downstream end side of the content paper transport path 43 and the downstream end side of the envelope paper transport path 45 are merged, and the downstream side of the junction between the content paper transport path 43 and the envelope paper transport path 45 in the apparatus housing 39. On the (exit side), an envelope conveyance path 47 for conveying an envelope or the like (including the sealed letter M) in a state where the contents are enclosed is provided. In addition, a plurality of eighth conveying roller pairs (not shown) that sandwich and convey the envelope or the like are provided at intervals along the envelope conveyance path 47 in the enclosure sealing device casing 39. Yes.

  An alignment unit (alignment unit) 49 is provided in the middle of the content sheet conveyance path 43, and the alignment unit 49 accumulates a plurality of printed content sheets P1 sent out from the introduction conveyance path 41. To be consistent. The alignment unit 49 includes an alignment gate (standby gate) 51 that waits for a plurality of printed content sheets P1. The alignment gate 51 opens and closes the content sheet conveyance path 43. Can be switched to.

  A content forming unit 53 is provided on the exit side (downstream side) of the alignment unit 49 in the content sheet conveyance path 43, and the content formation unit 53 includes a plurality of aligned units sent from the alignment unit 49. The content sheet P1 is folded to form the content. And the specific structure of the content formation part 53 is as follows, for example.

  A main folding roller 55 is rotatably provided on the outlet side (downstream side) of the aligning portion 49 in the enclosed sealing device casing 39, and a position adjacent to the main folding roller 55 in the enclosed sealing device casing 39. In addition, an introduction roller 57 for introducing the content paper P1 from the content paper transport path 43 in cooperation with the main folding roller 55 is rotatably provided. In addition, a guide plate 59 for guiding the content sheet P1 introduced by the main folding roller 55 and the introduction roller 57 is provided below the main folding roller 55 in the enclosure sealing device housing 39. Further, the guide plate 59 is provided with an abutting member 61 that abuts against (the front end of) the content paper P1 to give a slack near the folding line of the content paper P1, and this abutting member 61 is provided with an appropriate amount. The position can be adjusted along the guide plate 59 by driving a first position adjusting motor (not shown). An intermediate roller 63 is rotatably provided at a position adjacent to the main folding roller 55 and opposed to the introduction roller 57 in the enclosing / sealing device casing 39, and the intermediate roller 63 is a content sheet P1. The content sheet P1 is folded from the folding line in cooperation with the main folding roller 55 in a state where the vicinity of the folding line is slackened.

  A guide plate 65 is provided on the left side of the main folding roller 55 in the enclosing and sealing device housing 39 to guide the content sheet P1 folded by the main folding roller 55 and the intermediate roller 63. Further, the guide plate 65 is provided with an abutting member 67 that abuts against (the front end of) the content paper P1 and gives a slack in the vicinity of the folding line of the content paper P1. The position can be adjusted along the guide plate 65 by driving a second position adjusting motor (not shown). Further, a guide roller 69 is rotatably provided at a position adjacent to the main folding roller 55 and facing the intermediate roller 63 in the enclosing and sealing device housing 39, and the guide roller 69 is a content sheet P1. In the state where the vicinity of the fold line is slackened, the contents sheet P1 is led out to the contents sheet conveyance path 43 side while being folded from the fold line in cooperation with the main folding roller 55.

  Here, the main folding roller 55, the introduction roller 57, the intermediate roller 63, and the outlet roller 69 are each rotated by driving an appropriate first folding motor (not shown).

  A front folding part 71 is provided in the middle of the envelope paper conveyance path 45, and the front folding part 71 performs forward folding of the envelope paper P <b> 2 sent out from the introduction conveyance path 41. And the concrete structure of the front folding part 71 is as follows, for example.

  A main folding roller 73 is rotatably provided in the middle of the envelope paper conveyance path 45 in the enclosing and sealing apparatus housing 39, and at a position adjacent to the main folding roller 73 in the enclosing and sealing apparatus housing 39, An introduction roller 75 for introducing the envelope sheet P2 from the envelope sheet conveyance path 45 in cooperation with the main folding roller 73 is rotatably provided. A guide plate 77 for guiding the envelope paper P2 introduced by the main folding roller 73 and the introduction roller 75 is provided below the main folding roller 73 in the enclosure sealing device housing 39. Further, the guide plate 77 is provided with an abutting member 79 that abuts against (the leading end of) the envelope paper P2 and gives a slack in the vicinity of the folding line P2a of the envelope paper P2. The position can be adjusted along the guide plate 77 by driving a three-position adjusting motor (not shown). A lead-out roller 81 is rotatably provided at a position adjacent to the main folding roller 73 and facing the introduction roller 75 in the enclosing and sealing device housing 39. The lead-out roller 81 is provided on the envelope paper P2. In the state where the vicinity of the fold line P2a is slack, the envelope paper P2 is led to the envelope paper conveyance path 45 side while being folded from the fold line P2a in cooperation with the main fold roller 73.

  Here, the main folding roller 73, the introduction roller 75, and the outlet roller 81 are each rotated by driving an appropriate second folding motor (not shown).

  An envelope forming portion 83 is provided at the junction between the content paper transport path 43 and the envelope paper transport path 45, and the envelope forming section 83 bends the envelope paper P2 fed from the front folding portion 71 to provide an envelope. Is formed. And the concrete structure of the envelope formation part 83 is as follows, for example.

  A main folding roller 85 is rotatably provided on the outlet side (downstream side) of the front folding portion 71 in the enclosing and sealing apparatus housing 39 and is adjacent to the main folding roller 85 in the enclosing and sealing apparatus housing 39. In the position, an introduction roller 87 for introducing the envelope paper P2 from the envelope paper conveyance path 45 in cooperation with the main folding roller 85 is rotatably provided. A guide plate 89 for guiding the envelope paper P2 introduced by the main folding roller 85 and the introduction roller 87 is provided below the main folding roller 85 in the enclosure sealing device housing 39. Further, the guide plate 89 is provided with an abutting member 91 that abuts against (the leading end of) the envelope paper P2 and gives a slack in the vicinity of the folding line of the envelope paper P2. The position can be adjusted along the guide plate 89 by driving a position adjusting motor (not shown). An intermediate roller 93 is rotatably provided at a position adjacent to the main folding roller 85 and opposed to the introduction roller 87 in the enclosing and sealing device housing 39. The intermediate roller 93 is provided on the envelope paper P2. The envelope paper P2 is folded from the folding line in cooperation with the main folding roller 85 in a state where the folding line is slackened.

  A guide plate 95 is provided on the right side of the main folding roller 85 in the enclosing and sealing device casing 39 to guide the envelope paper P2 folded by the main folding roller 85 and the intermediate roller 93. Further, the guide plate 95 is provided with an abutting member 97 that abuts against (the front end of) the envelope paper P2 and gives a slack in the vicinity of the folding line of the envelope paper P2. The position can be adjusted along the guide plate 95 by driving a position adjusting motor (not shown). Further, a guide roller 99 is rotatably provided at a position adjacent to the main folding roller 85 and opposed to the intermediate roller 93 in the sealing device casing 39. The guide roller 99 is provided on the envelope paper P2. In a state where the vicinity of the fold line is slackened, the envelope paper P2 is led from the fold line to the envelope conveyance path 47 side in cooperation with the main fold roller 85.

  Here, the main folding roller 85, the introduction roller 87, the intermediate roller 93, and the outlet roller 99 are each rotated by driving an appropriate third folding motor (not shown).

  A sealing part 101 is provided in the middle of the envelope conveyance path 47, and in this sealing part 101, a part Ea to which a pressure-sensitive adhesive (crimping adhesive) is applied in advance in an envelope sent from the envelope forming part 83. Is pressed (pressed) to seal the envelope. In addition, the sealing unit 101 cooperates with a pair of pressure-lowering rollers 103 (only one is shown) that are separated in the front-rear direction and support both ends of the envelope, and in cooperation with the pair of pressure-lowering rollers 103 that are separated in the front-rear direction. And a pair of upper pressing rollers 105 for pressing both ends of the envelope. And a pair of pressurization lower roller 103 and a pair of pressurization upper roller 105 rotate by the drive of an appropriate sealing motor (not shown).

  A discharge conveyor 113 is provided on the downstream end side of the envelope conveyance path 47 in the enclosure sealing device casing 39 to convey the sealed letter M sent out from the sealing unit 101 to the downstream side and discharge it to the sealed letter tray 123. The discharge conveyor 113 includes a pair of pulleys 115 and 115 that are spaced apart from each other and can be rotated, and a discharge belt 117 that can circulate around the pair of pulleys 115 and 115 to convey the sealed letter M downstream. A conveyance motor 119 that circulates the discharge belt 117 is provided. In addition, all or part of the discharge conveyor 113 is provided in the opening on the upper surface of the encapsulating sealing device housing 39 so that it can be seen from the upper surface side of the enclosing sealing device housing 39, that is, can be visually confirmed by the user. Is provided. That is, the user can check the sealed letter M conveyed in the direction of the sealed letter tray 123 on the discharge belt 117. The discharge belt 117 is not limited to being visible from above the encapsulating sealing device casing 39, but may be a place where the door (not shown) of the enclosing sealing device casing 39 can be viewed.

  Further, a guide plate 121 for guiding the sealed letter M to the discharge conveyor 113 is provided on the inlet side (upstream end side) of the discharge conveyor 113 in the enclosure sealing device casing 39, while its carry-out side (downstream side). Is provided with a sealed tray 123 for storing the sealed letter M.

  An enclosure / sealing controller 125 is provided at an appropriate position in the enclosure / sealing device casing 39, and the enclosure / sealing controller 125 is used for enclosing / sealing processing data (a part of print data) of a job (print job). Based on this, the operations of the alignment unit 49, the content forming unit 53, the front folding unit 71, the envelope forming unit 83, the sealing unit 101, the discharge conveyor 113, and the like are controlled. The enclosing / sealing controller 125 functions as a conveyance control unit according to the present invention.

<Operation of Image Forming System 1>
Next, the operation of the image forming system 1 including the image forming apparatus 3 and the sealing device 5 configured as described above will be described with reference to flowcharts. In the following description, a case where there is one content sheet P1 and one envelope sheet P2 will be described.

  FIG. 2 is a flowchart showing the operation of the image forming system 1 including the image forming apparatus 3 and the enclosing / sealing apparatus 5.

  In the image forming system 1, when the sealed letter M is produced, first, the image forming apparatus 3 feeds the first content paper P 1 from the content paper feeding unit 15 under the control of the image forming controller 37. (Step S101), the multi-feed sensor 13d measures the transmission amount D1 of the first content sheet P1, and the transmission amount D1 of the first content sheet P1 measured by the multi-feed sensor 13d. And the first content sheet P1 is printed by the printing unit 9 (step S103). The printed first content sheet P1 is discharged to the sealing device 5 and the above-described predetermined sealing process is executed under the control of the sealing device 125.

  Next, the image forming controller 37 feeds the first envelope paper P2 from the envelope paper feed unit 23 (step S105), and causes the multi-feed sensor 13d to transmit the first envelope paper P2. The amount D2 is measured, and the transmission amount D2 of the first envelope paper P2 measured by the double feed sensor 13d is stored, and the first envelope paper P2 is printed by the printing unit 9 (step S107). . The printed first envelope paper P2 is discharged to the sealing device 5 as in the case of the first content paper P1, and the above-mentioned predetermined sealing processing is performed under the control of the sealing controller 125. Is executed.

  Here, the image forming controller 37 determines whether or not the second sheet of paper is being double fed, that is, until it is determined in step S113 described later that D1> D3 or D1 <D3, or step S113. In step S121, a command is sent to the sealed sealing controller 125 until the determination process in step S121 is completed, and a sealed letter M, which is a printed matter set including the first content paper P1 and envelope paper P2, is completed. Even when the paper can be discharged to the sealed letter tray 123, it is stopped on the discharge belt 117 of the discharge conveyor 113.

  When the feeding of the first content paper P1 and the envelope paper P2 is completed, the image forming controller 37 subsequently causes the content paper feeding unit 15 to feed the second content paper P1. (Step S109), the multi-feed sensor 13d measures the transmission amount D3 of the second content sheet P1, and the transmission amount D3 of the second content sheet P1 measured by the multi-feed sensor 13d. The second content sheet P1 is stored and printed by the printing unit 9 (step S111).

  Next, the image forming controller 37 determines the transmission amount D1 of the first content sheet P1 measured and stored in step S103, and the transmission amount D3 of the second content sheet P1 measured and stored in step S111. Are compared to determine which of the transmission amounts D1 and D3 of both is greater or whether the transmission amounts D1 and D3 are equal (step S113). When comparing the transmission amounts D1 and D3, it is considered that they are equal if they are within a predetermined range in the vicinity, and the range may be set and adjusted as appropriate by the user.

  Here, when it is determined that the transmission amount D1 of the first content sheet P1 is larger than the transmission amount D3 of the second content sheet P1 (step S113 “D1> D3”), the first transmission The second content sheet P1 is more likely not to transmit the irradiation light of the multi-feed sensor 13d than the second content sheet P1, and it is highly likely that the second content sheet P1 has been double-fed. The image forming controller 37 immediately stops a series of processes in the image forming apparatus 3 immediately as in the case of normal double feed detection (step S115).

  On the other hand, when the transmission amount D1 of the first content sheet P1 and the transmission amount D3 of the second content sheet P1 are equal (step S113 “D1 = D3”), the first content sheet Double feed does not occur at P1 and the second content sheet P1, and it is in a normal printing state. Therefore, the image forming controller 37 causes the second envelope paper P2 to be fed from the envelope paper feeder 23 (step S117), and causes the double feed sensor 13d to transmit the second envelope paper P2. D4 is measured, and the transmission amount D4 of the second envelope paper P2 measured by the double feed sensor 13d is stored, and the second envelope paper P2 is printed by the printing unit 9 (step S119).

  Next, the image forming controller 37 compares the transmission amount D2 of the first envelope paper P2 measured and stored in step S113 with the transmission amount D4 of the second envelope paper P2 measured and stored in step S119. Then, it is determined which of the transmission amounts D2 and D4 of the both is greater or whether the transmission amounts D2 and D4 are equal (step S121). As in the case of comparing the transmission amount D1 of the first content sheet P1 and the transmission amount D3 of the second content sheet P1 in step S113, the comparison of the transmission amounts D1 and D3 is also performed. It is considered that they are equal if they are within a predetermined range in the vicinity, and the range may be set and adjusted as appropriate by the user.

  If it is determined in step S121 that the transmission amount D2 of the first envelope paper P2 is larger than the transmission amount D4 of the second envelope paper P2 (“D2> D4”), the first envelope paper Since the second envelope paper P2 has a higher possibility that the second envelope paper P2 does not transmit the irradiation light of the double feed sensor 13d and the second envelope paper P2 has a double feed, the image forming controller 37 As in the case where D1> D3 is determined in step S113, the series of processing in the image forming apparatus 3 is immediately stopped immediately (step S115).

  On the other hand, in step S121, when the transmission amount D2 of the first envelope paper P2 and the transmission amount D4 of the second envelope paper P2 are equal (“D2 = D4”), the first envelope paper P2 and 2 Since the multi-feed is not generated at the second envelope paper P2 and the normal printing state is performed, the image forming controller 37 thereafter performs normal normal heavy printing after the third content paper P1 and the envelope paper P2. A sending determination process is executed (step S123). Note that the normal multi-feed determination process for the third and subsequent copies does not cause multi-feeds in the first content sheet P1 and the envelope paper P2, and therefore, for example, the transmission amount of the first content sheet P1 Based on the permeation amount D2 of D1 and the envelope paper P2, the permeation amount of the third and subsequent contents paper P1 and the permeation amount of the envelope paper P2 may be measured and the multifeed determination process may be similarly performed. The double feed determination process may be performed based on the transmission amount of the content sheet P1 and the transmission amount of the envelope paper P2 immediately before the occurrence of the occurrence of the paper.

  On the other hand, when it is determined in step S113 that the transmission amount D3 of the second content sheet P1 is larger than the transmission amount D1 of the first content sheet P1 ("D1 <D3"), two transmissions It is more likely that the first content sheet P1 does not transmit the irradiation light of the multi-feed sensor 13d than the first content sheet P1, and the multi-feed has occurred in the first content sheet P1.

  Similarly, when it is determined in step S121 that the transmission amount D4 of the second envelope paper P2 is larger than the transmission amount D2 of the first envelope paper P2 (step S121 “D2 <D4”), 2 It is more likely that the first envelope paper P2 does not transmit the irradiation light of the multifeed sensor 13d than the first envelope paper P2, and the double feed has occurred in the first envelope paper P2.

  Therefore, if the image forming controller 37 determines that D1 <D3 in the determination process in step S113 and determines that D2 <D4 in step S121, the image forming controller 37 overlaps the first content sheet P1 or envelope sheet P2. Assuming that the feeding has occurred, a command is sent to the sealed sealing controller 125 of the sealed sealing device 5, and as shown in FIG. 3B to be described later, the sealed letter consisting of the first content paper P1 and the envelope paper P2 The discharge belt 117 is stopped in a state where M is placed (step S125).

  That is, when the image forming controller 37 determines that the double feed has occurred on the first content sheet P1 or the envelope sheet P2, the sealed sealing controller 125 first discharges from the image forming apparatus 3. The content paper P1 and the envelope paper P2 are conveyed on the introduction conveyance path 41, and the content paper P1 is conveyed to the content formation unit 53 via the content paper conveyance path 43, while the envelope paper P2 is the envelope paper. It is conveyed to the front folding part 71 via the conveyance path 45.

  Next, the encapsulating controller 125 folds the envelope paper P2 sent out from the front folding portion 71 by the envelope forming portion 83 to form an envelope, and the contents folded by the content forming portion 53 in the envelope. The paper P1 is sealed and sealed by the sealing unit 101 on the envelope conveyance path 47 to produce a sealed letter M, which is sent onto the discharge belt 117 of the discharge conveyor 113.

  Then, the enclosing / sealing controller 125 includes the first content sheet P1 or the envelope sheet P2 that is regarded as being double-fed by the discharge belt 117 by rotating the transport motor 119 based on the control signal of the image forming controller 37. Although the sealed letter M is conveyed, it is determined to be double feeding, and therefore the rotation of the conveying motor 119 is stopped halfway, and the sealed letter M is stopped by the discharge belt 117 that can be visually confirmed by the user, and is not discharged to the sealed letter tray 123. At this time, the operation panel (not shown) or the like is used to inform the user that the conveyance of the first sealed letter M regarded as double feeding has been stopped on the discharge belt 117 that can be visually confirmed by the user. You may make it alert | report.

  FIG. 3A shows a case where the first sealed letter M determined to be double-fed is discharged to the sealed letter tray 123. FIG. 3B shows the case where the image forming apparatus 3 according to the first embodiment performs double-fed. The case where the determined first sealed letter M is not discharged to the sealed letter tray 123 and is stopped by the discharge belt 117 that can be visually confirmed by the user is shown.

  As shown in FIG. 3A, when the first sealed letter M determined to be double-fed is discharged to the sealed letter tray 123, if the sealed letter M is already loaded on the sealed letter tray 123, the double-fed 1 The sealed letter M including the continuous contents sheet P1 and the envelope sheet P2 may be unclear and difficult to find. Even when the sealed letter M is not already loaded on the sealed letter tray 123, if the second sealed letter M is loaded after the first fed letter M is discharged, the It is difficult to find the first sealed letter M.

  In contrast, in the image forming apparatus 3 according to the first embodiment of the present invention, the sealed letter M is stopped on the discharge belt 117 that can be visually confirmed by the user as shown in FIG. Even if the envelope M is loaded, the user can immediately find the envelope M including the first content sheet P1 and the envelope sheet P2 that are double-fed.

  Further, when double feed occurs on the first content sheet P1 or envelope sheet P2, the image forming apparatus 3 and the enclosing sealing apparatus 5 are not stopped instantaneously as in the process of step S115 in FIG. Since the first sealed letter M in which the double feed is generated by the process of step S125 is stopped on the discharge belt 117, it is easily confirmed visually by the user that double feed has occurred in the first sealed letter M. be able to.

  Therefore, when printing is resumed, it is understood that printing is resumed from the first one by clarifying the first sealed letter M sealed including the multi-feed content paper P1 or envelope paper P2. Therefore, it is possible to omit the trouble of performing the test printing and confirming it.

  As described above, in the image forming apparatus 3 and the sealing device 5 according to the first embodiment of the present invention, the transmission amount D1 of the first content sheet P1 and the transmission amount D3 of the second content sheet P1 Are compared with the permeation amount D2 of the first envelope paper P2 and the permeation amount D4 of the second envelope paper P2, and if D1 <D3 and D2 <D4, the first content It is determined that double feeding has occurred in the paper P1 or the envelope paper P2, and the sealed letter M composed of the first content paper P1 or the envelope paper P2 is stopped on the discharge belt 117 that the user can visually check. Therefore, it is possible to reliably detect the first multi-feed of the content paper P1 or the envelope paper P2 for each type of paper, that is, for each of the content paper P1 and the envelope paper P2. It is possible to easily find the sealed letter M composed of the continuous contents paper P1 or the envelope paper P2 on the discharge belt 117 that can be visually checked by the user, and to prevent it from becoming difficult to find in the sealed letter tray 123.

  In addition, according to the image forming apparatus 3 and the encapsulating and sealing apparatus 5 of Example 1 according to the present invention, one encapsulated and sealed process is performed until the determination of the presence or absence of occurrence of double feeding of at least the second printed set is completed. Since the sealed letter M, which is the first printed matter set, is stopped on the discharge belt 117, if there is a possibility of double feeding with the first printed matter set, the first sealed letter M to the sealed tray 123 is stored. The discharge can be stopped. That is, if it is determined that there is no double feed on the contents paper P1 and the envelope paper P2 of the first print set, and it is determined that there is a double feed on the second print set, the first print set is changed to the first print set. Since there is a possibility of a cause, it is difficult to find in the sealed tray 123 by discharging to the sealed tray 123 only when it is determined that there is no double feed in the first and second printed sets. Can be prevented.

  In the above description, the description has been made on the assumption that there is one content sheet P1 and one envelope sheet P2, but there are many cases where there are a plurality of content sheets P1. Therefore, for example, when there are a plurality of content sheets P1, it is possible to detect double feeding between the first and second content sheets P1 even in the first content sheet P1. That is, when there are a plurality of content sheets P1, the transmission amounts of the first and second content sheets P1 in the first content sheet P1 are measured in step S103 of FIG. Stored as amounts D1 and D3, omit the processing in steps S109 and S111, and in step S113, instead of comparing the transmission amount of the first and second contents paper P1, measure in step S103. One sheet of the first content sheet P1 is compared by comparing the transmission amounts D1 and D3 of the first and second content sheets P1 of the first content sheet P1 stored in advance. It is possible to detect double feeding of the first and second content sheets P1.

  In the image forming system 1, the envelope paper P2 is supplied and processed after the processing of the content paper P1 is completed. Therefore, when there are many contents, the first sealed letter M may be discharged to the sealed letter tray 123 before the envelope paper P2 of the second sealed letter M reaches the multi-feed sensor 13d. If it is determined that double feed has occurred in the first sealed letter M after the first sealed letter M is discharged, it becomes difficult for the user to find and remove the first sealed letter M. There is a case.

  Therefore, when it is not confirmed that the double feed in the first sealed letter M has not occurred, the sealed sealing controller 125 uses the discharge belt 117 to stop the first sealed letter M on the discharge belt 117. The conveyance may be controlled. Further, the enclosing / sealing controller 125 may control the conveyance by the conveyance belt 117 so that the conveyance of the first sealed letter M is always stopped on the discharge belt 117.

  In addition, the sealed sealing controller 125 detects that the double feed sensor 13d detects the amount of light received by the envelope paper P2 related to the second sealed letter M, and determines that no double feed has occurred in the first sealed letter M. The receipt of the first letter M by the conveying belt 117 may be resumed, and the letter M may be discharged to the letter tray 123 so that the print job can be continued as the entire system.

(Example 2)
In Embodiment 1 according to the present invention, even when one of the content paper P1 and the envelope paper P2 discharged from the image forming apparatus 3 is not regarded as a normal printed matter due to a trouble such as a so-called paper jam of other paper. The image forming apparatus 3 has been described by way of example as it is coasting and discharged to the sealing device 5 on the downstream (rear stage) side. For this reason, the encapsulating and sealing apparatus 5 may count and charge the paper as a normal printed matter, and the image forming apparatus 3 and the encapsulating and sealing apparatus 5 may not be able to match the accounting.

  Therefore, in the image forming system 1 according to the second embodiment of the present invention, even if a trouble such as a paper jam occurs in the image forming apparatus 3, the count value of the normal printed matter is obtained between the image forming apparatus 3 and the enclosing sealing device 5. It is characterized in that it is consistent and can be matched for billing. The configurations of the image forming apparatus 3 and the sealing device 5 according to the second embodiment of the present invention are the same as those of the image forming apparatus 3 and the sealing device 5 according to the second embodiment of the present invention shown in FIG. A description will be given with reference to the configuration of the first embodiment according to the present invention shown in FIG.

  FIG. 4 is a flowchart showing the operation of the image forming system including the image forming apparatus and the sealing device according to the second embodiment of the present invention.

  As shown in FIG. 4, when printing is started in the image forming apparatus 3 according to the second embodiment of the present invention, the image forming controller 37 controls the entire image forming apparatus 3, and the content sheet as shown in FIG. The content sheet P1 is fed from the sheet feeding unit 15 and printing is performed by the printing unit 9 via the sheet feeding conveyance path 21 and the printing conveyance path 13 (step S201). Similarly, the envelope paper P2 is fed from the envelope paper feed unit 23, and printing is executed by the printing unit 9 via the paper feed conveyance path 29 and the print conveyance path 13 (step S201).

  Then, the image forming controller 37 performs the contents sheet P1 or the envelope on any one of the paper feed transport path 21, the paper feed transport path 29, the print transport path 13, the switchback transport path 33, the communication transport path 35, and the like. It is detected whether a paper jam has occurred in the paper P2 (step S203).

  In step S203, if no paper jam has occurred in any of the transport paths during printing in the printing unit 9 (step S203 “NO”), the image forming controller 37 continues printing in the printing unit 9 as it is (step S203). Step S201).

  On the other hand, in step S203, when a paper jam of the content paper P1 or the envelope paper P2 occurs in any of the conveyance paths during printing by the printing unit 9 (“YES”), the image forming controller 37 continues to It is determined whether a paper jam has occurred during printing in the printing unit 9 (step S205). Whether or not a paper jam has occurred during printing in the printing unit 9 is determined based on the size of a paper jam occurrence time T1 and a paper detection time T2 in the paper discharge sensor 35a provided on the downstream side of the printing unit 9.

  As a result, when the paper jam occurrence time T1 is earlier than the paper detection time T2 in the paper discharge sensor 35a, that is, when T1 <T2, the image forming controller 37 easily determines that a paper jam has occurred during printing. it can.

  On the other hand, when the paper jam occurrence time T1 is the same as or later than the paper detection time T2 in the paper discharge sensor 35a, that is, when T1 ≧ T2, the image forming controller 37 generates the paper jam as shown in FIG. Time T1, detection time T2 of the content paper P1 or envelope paper P2 in the paper discharge sensor 35a, size of the content paper P1 or envelope paper P2, transport speed, and point B where the paper discharge sensor 35a is provided The determination is made based on the distance H to the point A that is the downstream end of the inkjet head 11.

  FIG. 5 is an enlarged view showing a connection portion between the image forming apparatus 3 and the sealing device 5. FIG. 6 is a diagram showing an overlapping relationship between the content paper P1 or the envelope paper P2 and the ink jet head 11 at the connection portion between the image forming apparatus 3 and the sealing device 5.

  As shown in FIG. 5, the image forming controller 37 turns on the discharge sensor 35a provided at the point B in the communication conveyance path 35 at the leading end of the contents sheet P1 or the envelope sheet P2, that is, at the discharge sensor 35a. Based on the difference (T1-T2) between the detection time T2 of the content paper P1 or the envelope paper P2 and the paper jam occurrence time T1 and the conveyance speed of the communication conveyance path 35, as shown in FIG. First, the distance h1 of how much the leading end of the content paper P1 or the envelope paper P2 is conveyed from the point B is calculated.

  Next, the image forming controller 37 determines the distance h1 from which the leading end of the content paper P1 or the envelope paper P2 is transported from the point B and the size in the transport direction of the content paper P1 or the envelope paper P2. As shown in FIG. 6, the distance h2 from the point B on the communication conveyance path 35 at the paper jam occurrence time T1 to the rear end portion of the content paper P1 or the envelope paper P2 is calculated.

  The image forming controller 37 then stores a distance H from a point A that is a downstream end of the inkjet head 11 stored in advance to a point B where the paper discharge sensor 35a is provided, and a point B at the paper jam occurrence time T1. By comparing the size of the distance h2 to the rear end of the content paper P1 or the envelope paper P2, if H <h2, the rear end of the content paper P1 or the envelope paper P2 is as shown in FIG. Since it is at the downstream end of the inkjet head 11, it can be determined that printing is in progress. On the other hand, if H ≧ h2, the rear end portion of the content paper P1 or the envelope paper P2 has passed the downstream end portion of the inkjet head 11, and therefore it can be determined that the printing is finished.

  As described above, when it is determined that the paper jam of the content paper P1 or the envelope paper P2 has occurred during the printing in the printing unit 9 (step S205 “YES”), the printing of the printed material is completed in the printing unit 9 Since it can be regarded as an unfinished printed matter, the image forming controller 37 sends a control signal to the enclosing / sealing controller 125 of the enclosing / sealing device 5 to immediately stop the enclosing / sealing device 5 (step S207).

  For this reason, if a paper jam occurs during printing (step S205 “YES”), even if the paper is sent from the image forming apparatus 3 to the encapsulating and sealing apparatus 5, the encapsulating and sealing apparatus 5 does not execute the enclosing and sealing process. Is also prevented.

  On the other hand, when it is determined that the paper jam has occurred when the printing unit 9 is not in the middle of printing (step S205 “NO”), the printed matter has been normally printed by the printing unit 9. Therefore, the image forming controller 37 sends a control signal to the enclosure / sealing controller 125 of the enclosure / sealing device 5 to execute a predetermined enclosure / sealing process in the enclosure / sealing device 5, and normally ejects it from the discharge conveyor 113 to the sealed letter tray 123. (Step S209).

  For this reason, even when a paper jam occurs (step S205 “YES”), if it can be considered that printing has been completed normally by the printing unit 9 (step S205 “NO”), the image forming apparatus 3 generates a completed printed product. It is sent to the sealing device 5 and sealed by the sealing device 5 and charged.

  Therefore, according to the image forming apparatus 3 of the second embodiment of the present invention, when a paper jam occurs during printing in the printing unit 9, the enclosing sealing device 5 is stopped urgently, and the image forming apparatus 3 starts the enclosing sealing device 5. Even if the paper is sent by inertia, the sealing process is not executed. Therefore, even if a paper jam occurs in the image forming apparatus 3 and a paper that is not counted as a normal printed matter is discharged to the sealing device 5, the sealing device 5 is stopped, and the paper is counted as a normal printed material and sealed. Thus, the image forming apparatus 3 and the enclosing / sealing apparatus 5 can be matched for billing.

DESCRIPTION OF SYMBOLS 1 ... Image forming system 3 ... Image forming apparatus 5 ... Enclosing sealing device 9 ... Printing part 11 ... Inkjet head 13 ... Printing conveyance path 13a ... Registration roller pair 13b ... Registration sensor 13c ... Belt platen roller 13d ... Multi feed sensor (detection means) )
DESCRIPTION OF SYMBOLS 15 ... Content paper feed part 21 ... Paper feed conveyance path 23 ... Envelope paper feed part 29 ... Paper feed conveyance path 35 ... Communication conveyance path 35a ... Paper discharge sensor 37 ... Image formation controller (multifeed determination means, conveyance control) means)
47 ... Envelope transport path 49 ... Alignment section 53 ... Contents forming section 83 ... Envelope forming section 101 ... Sealing section 113 ... Discharge conveyor 117 ... Discharge belt 119 ... Conveyance motor 123 ... Sealing tray 125 ... Enclosed seal controller P1 ... Content paper P2 ... envelope paper M ... envelope

Claims (2)

An image forming apparatus that receives a print job including instructions for creating a plurality of envelopes composed of envelopes and contents, prints the envelope data and contents data on different sheets according to the order in which they are instructed, and the image formation An image forming system having an enclosing sealing device connected to a downstream side of the device,
The image forming apparatus includes:
Detecting means for irradiating light to each sheet on which the envelope data and contents data are printed and detecting the amount of light transmitted or reflected;
A double feed determination that compares the amount of light detected by the detection unit for the first and second printed sheets for each paper type and determines whether or not a double feed has occurred for each sheet based on the comparison result. and means, the,
The enclosed sealing device is
An encapsulated sealing unit that receives a sheet discharged from the image forming apparatus and executes a sealed sealing process for each of a plurality of sheets based on the print job to create a sealed letter;
A sealed tray in which the sealed letter created by the sealed sealed part is discharged;
A discharge path for conveying and discharging the sealed letter created by the sealed sealing part to the sealed letter tray,
At least one of the image forming apparatus and the sealing device is further provided with a transport control unit that controls the transport of the sealed letter so as to stop the created first sealed letter on the discharge path. An image forming system. The transport control means includes
Until the determination of the presence or absence of occurrence of double feed in the first sealed letter is completed by comparing the light quantity of the sheets used in the first and second sealed letters by the double-feed determining means. Stop conveying the first letter,
When the multi-feed determining means determines that multi-feed has not occurred in the first sealed letter, control is performed to resume transport of the first sealed letter and discharge it to the sealed letter tray. The image forming system according to claim 1 .

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