JP2006264962A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of easily performing jam processing. <P>SOLUTION: This image forming device is constituted so as to detect the occurrence of a jam by a jam detecting means, by detecting a position of paper carried in respective carrying passages 36, 37, 38, 51 and 52 by a paper detecting means, by forming an image on the paper carried in a main carrying passage 36 by an image forming system 31, by carrying the paper along the main carrying passage 36, the first reversing carrying passage 37, the second reversing carrying passage 38, the relay carrying passage 51 and the switchback carrying passage 52 of a paper carrying system 32 by a plurality of driving sources. When detecting the occurrence of the jam by the jam detecting means, control made different in the timing for stopping the respective driving sources for carrying the paper, is performed in response to a jam occurrence time paper position detected by the paper detecting means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for facilitating jam processing in an image forming apparatus.

  In recent years, image forming apparatuses have become more multifunctional, compact, and faster. In order to achieve this compactness, the paper conveyance path for conveying the paper is formed by curving and bending, shortening, the paper conveyance path and the printing unit, the paper discharge unit arranged along the paper conveyance path, etc. For example, the interval between the component members is reduced. As the speed increases, as described above, the paper transport path is shortened, the peripheral speed of the photoconductor called the process speed, the paper transport speed, etc. are increased, and the paper is fed continuously from the paper feed unit. When performing the above, the interval between the sheets conveyed along the sheet conveyance path is narrowed.

  In addition, with the increase in functionality, development of paper post-processing devices that perform post-processing on paper after printing, for example, stapling processing, punching processing, bookbinding processing, etc., and devices equipped with a multi-stage discharge tray as an option are being developed. ing. Such a sheet post-processing device and a multi-stage paper discharge tray are large, and in the case of an image forming apparatus having a compact configuration, the paper post-processing device and the multi-stage paper discharge tray cannot be arranged in the apparatus main body. For this reason, the sheet post-processing device and the multi-stage sheet discharge tray are installed outside (for example, the side portion) of the image forming apparatus.

  By the way, when a sheet post-processing device or a multi-stage sheet discharge tray is provided as an option, a relay conveyance unit may be mounted on the apparatus main body of the image forming apparatus. The relay conveyance unit is provided in a space formed in the apparatus main body of the image forming apparatus, for example, in a space formed by the document reading unit, the printing unit, and the paper feeding unit of the apparatus main body. It is provided instead, and conveys paper to an external paper post-processing device or a multi-stage paper discharge tray.

  On the other hand, when a jam occurs in the image forming apparatus, normally, the energization is immediately cut off, and operations such as print processing and paper conveyance are stopped until the jam processing is completed. Then, if the paper conveyance is immediately stopped after the jam occurs, there is a possibility that paper other than the jammed paper is stagnant in the paper conveyance path when continuous paper feeding is performed from the paper feeding unit. . The jam processing can be performed by the user opening the door or cover of the apparatus, and removing the stagnant paper by putting a hand in the space in the apparatus as necessary.

  However, as described above, in the image forming apparatus, if the paper conveyance path is curved or bent, or the distance between the paper conveyance path and the constituent members such as the printing unit and the paper discharge unit is narrow, the paper is stagnated. Depending on the location, there is no space for the user to handle, making it difficult to remove the paper, and jam handling becomes difficult. Further, if the paper stagnate while straddling the conveyance path of an adjacent unit among the units arranged in the image forming apparatus, the jam processing becomes extremely difficult. For example, as described above, when a relay transport unit is mounted on the apparatus main body and the paper is transported to a downstream paper post-processing device or a multistage paper discharge tray, most of the paper is transported into the relay transport unit. When stagnated in a state, such a sheet is extremely difficult to remove, and jam handling becomes extremely difficult.

  In addition, if continuous paper feeding is performed with the interval between papers narrowed, there is a high possibility that paper other than jammed paper is stagnant in the paper transport path, and the above-described jam processing is difficult. There is a problem that there is a high possibility that the vehicle is stagnating in a different place.

Patent Document 1 discloses a multiple sorter that can easily perform jam processing. Specifically, in a state where the discharge cover of the multiple sorter is closed, the push-up member is positioned below the conveyance path between the conveyance roller and the deflection guide, and if a jam occurs, the multiple sorter is discharged. When the cover is opened, the push-up member is lifted from the above-mentioned position via the link member connected to the discharge cover. A technique is shown in which the paper stagnating in a place where jamming is difficult can be easily removed by pushing up the paper jammed in the conveyance path by the movement of the push-up member. .
JP-A-4-182265

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can easily perform jam processing.

  In the present invention, means for solving the above-described problems are configured as follows. In other words, paper is transported along a paper transport path by a plurality of drive sources, an image is formed on a paper transported through the paper transport path by an image forming unit, and the paper being transported through the paper transport path by a paper detection unit In the image forming apparatus configured to detect the position of the jam and to detect the occurrence of the jam by the jam detection unit, when the occurrence of the jam is detected by the jam detection unit, the sheet detection unit detects the jam. The timing of stopping each drive source for carrying the paper is made different according to the position of the paper when the jam occurs.

  According to the image forming apparatus having such a configuration, each drive source that transports paper is not stopped immediately after a jam occurs, but is stopped according to the position of the paper when the jam occurs. Specifically, paper conveyance by each drive source can be performed as follows. When a jam occurs, if the paper being transported on the paper transport path is in a position where it can be jammed, stop the drive source immediately after the jam has occurred and do not transport any more paper. Can be. Conversely, if the paper is in a position where it is difficult to carry out jam processing, the drive source is not stopped immediately after the jam occurs, and the drive source is moved to a position where the paper can be removed. Can be stopped. As a result, the jam processing can be easily performed.

  In the image forming apparatus of the present invention, a plurality of the paper detection means are provided in the paper conveyance path, and the position of the paper being conveyed is detected based on the on / off timing of the paper detection means. Features. As such a sheet detection means, a contact sensor or an optical sensor that is turned on when the leading edge of the sheet passes and is turned off when the trailing edge passes can be used.

  According to the image forming apparatus having such a configuration, the drive sources for carrying the paper do not stop immediately after the jam occurs, and the on / off timings of a plurality of paper detection means arranged in the paper carrying path are set. The paper is stopped according to the position of the paper when the jam is detected based on the paper. Specifically, when the paper is transported by each drive source, when the jam occurs, if the paper being transported through the paper transport path is in a position where jam processing can be performed, immediately after the jam has occurred, It is possible to stop and prevent further paper conveyance. Conversely, if the paper is in a position where it is difficult to carry out jam processing, the drive source is not stopped immediately after the jam occurs, and the drive source is moved to a position where the paper can be removed. Can be stopped. As a result, the jam processing can be easily performed.

  Further, in the image forming apparatus of the present invention, the position of the sheet at the time of occurrence of the jam detected by the sheet detecting unit is an adjacent unit among the units disposed in the image forming apparatus in the sheet transport path. If the paper is straddling the transport path, the drive source for transporting the paper from the one adjacent unit to the other unit is not stopped immediately after the jam occurs, and the drive source is not stopped immediately, but to the transport path of any unit. It is characterized by stopping after the sheet is fed and conveyed to a position where the sheet can be removed.

  Here, the units provided in the image forming apparatus include a post-processing unit that performs paper post-processing on paper after printing, a post-processing apparatus installed outside the image forming apparatus, and a multi-stage paper discharge tray. There are relay transfer units and the like. Further, when the post-processing unit and the relay conveyance unit are mounted on the image forming apparatus, the apparatus main body other than the image processing apparatus post-processing unit and the relay conveyance unit can be regarded as one unit.

  When a jam occurs, if the paper stagnates while straddling the conveyance path of the adjacent unit, for example, if the paper stagnates across the conveyance path of the image forming apparatus main body and the conveyance path of the relay conveyance unit, Such paper is extremely difficult to remove and jamming may be extremely difficult. In the image forming apparatus configured as described above, when a jam occurs, if a sheet straddles the conveyance path of an adjacent unit, the sheet conveyance is not stopped immediately after the jam occurs, and the conveyance path of any unit The paper is fed to the position where it can be removed. As a result, the jam processing can be easily performed.

  Further, in the image forming apparatus according to the present invention, after the energization of the image forming apparatus is cut off due to the occurrence of a jam, a part of the driving source that transports the paper is reversely rotated for a predetermined time at the start of the next energization. It is characterized by.

  If the paper stagnates at a position where it is difficult to perform jam processing, it may be difficult to remove the paper unless the drive source for carrying the paper is rotated in the reverse direction. However, some drive sources that carry the paper are not supposed to switch the rotation direction frequently in normal times. Accordingly, it may be difficult to reversely rotate the drive source immediately when a jam occurs. Therefore, in such a case, when a jam occurs, such a drive source is not immediately reversely rotated, but after the energization of the image forming apparatus is cut off, it is reversed for a predetermined time at the start of the next energization. Try to rotate. By this reverse rotation, the paper can be forcibly fed back and sent to a position where the paper can be removed, and then the paper can be removed by opening the cover of the image forming apparatus.

  As described above, according to the present invention, each drive source that transports paper is not stopped immediately after a jam occurs, but is stopped according to the position of the paper when the jam occurs. Specifically, when the paper is transported by each drive source, when the jam occurs, if the paper being transported through the paper transport path is in a position where jam processing can be performed, immediately after the jam has occurred, It is possible to stop and prevent further paper conveyance. Conversely, if the paper is in a position where it is difficult to carry out jam processing, the drive source is not stopped immediately after the jam occurs, and the drive source is moved to a position where the paper can be removed. Can be stopped. As a result, the jam processing can be easily performed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

  In the present embodiment, a case where the image forming apparatus of the present invention is applied to a multifunction machine will be described. FIG. 1 shows an outline of the internal configuration of such a multifunction machine. As shown in FIG. 1, the multifunction machine 1 includes a scanner unit 2 as an original reading unit, an image forming unit 3, an automatic document feeder 4, and a relay conveyance unit 5. In the following, for the sake of convenience, in the configuration of the multifunction machine 1 shown in FIG. 1, a part other than the relay transport unit 5 is referred to as an “apparatus main body”.

  The multifunction device 1 has a copier mode (copy mode), a printer mode, and a FAX mode as image forming modes for forming an image on a sheet (including a recording medium such as OHP), and an operation unit (not shown). The control unit (not shown) selects a mode in accordance with an operation input from the printer or a print job received from an external host device such as a personal computer.

  Hereinafter, each part of the multifunction device 1 will be described.

  First, the scanner unit 2 will be described. The scanner unit 2 creates document image data by reading an image of a document placed on a document table 41 made of transparent glass or the like, or an image of a document fed by the automatic document feeder 4 one by one. It is a part to do. The scanner unit 2 includes an exposure light source 21, a plurality of reflecting mirrors 22, 23, 24, an imaging lens 25, and a photoelectric conversion element (CCD) 26.

  The exposure light source 21 emits light to a document placed on the document table 41 of the automatic document feeder 4 or a document conveyed through the automatic document feeder 4. Each reflecting mirror 22, 23, 24 reflects the reflected light from the document once in the left direction in FIG. 1 and then reflects downward as indicated by the alternate long and short dash line A in FIG. Thereafter, the light is reflected in the right direction in FIG.

  There are the following two types of document image reading operations. When a document placed on the document table 41 is read (when used as a “sheet fixing method”), the exposure light source 21 and the reflecting mirrors 22, 23, 24 are arranged horizontally along the document table 41. By scanning, the image of the entire original is read. On the other hand, when reading a document conveyed by the automatic document feeder 4 (when used as a “sheet moving method”), the exposure light source 21 and the reflecting mirrors 22, 23, 24 are positioned at the positions shown in FIG. When the document passes through a document reading unit 42 of the automatic document feeder 4 described later, the image is read.

  The light reflected by the reflecting mirrors 22, 23 and 24 and passed through the imaging lens 25 is guided to the photoelectric conversion element 26, and the reflected light is converted into an electric signal (original image data) by the photoelectric conversion element 26. It is like that.

  The automatic document feeder 4 is configured as a so-called automatic duplex document feeder. The automatic document feeder 4 can be used as a sheet moving type, and includes a document tray 43 as an original placement unit, an intermediate tray 44, a document discharge tray 45 as a document discharge unit, and trays 43 and 44. , 45 is provided with a document conveying system 46 for conveying the document.

  The document transport system 46 includes a main transport path 47 for transporting a document placed on the document tray 43 to the intermediate tray 44 or the document discharge tray 45 via the document reading unit 42, and the document on the intermediate tray 44. And a sub-transport path 48 for supplying to the main transport path 47.

  A document pick-up roller 47a and a separating roller 47b are disposed at the upstream end of the main conveyance path 47 (a portion facing the discharge side of the document tray 43). Further, a separating plate 47c is disposed below the separating roller 47b. With the rotation of the document pickup roller 47a, one of the documents on the document tray 43 passes between the separation roller 47b and the separation plate 47c and is fed to the main conveyance path 47. Yes. PS rollers 47e and 47e are disposed on the downstream side of the joining portion (B portion in FIG. 1) of the main transport path 47 and the sub transport path 48. The PS rollers 47 e and 47 e adjust the leading edge of the document and the image reading timing of the scanner unit 2 and supply the document to the document reading unit 42. In other words, the PS rollers 47e and 47e temporarily stop the conveyance of the document while the document is supplied, adjust the timing, and supply the document to the document reading unit 42.

  The document reading unit 42 includes a platen glass 42a and a document pressing plate 42b. When the document supplied from the PS rollers 47e and 47e passes between the platen glass 42a and the document pressing plate 42b, the document reading unit 42 receives from the exposure light source 21. The light passes through the platen glass 42a and is irradiated on the original. At this time, the document image data is acquired by the scanner unit 2. A biasing force by a coil spring (not shown) is applied to the back surface (upper surface) of the document pressing plate 42b. Thereby, the document pressing plate 42b comes into contact with the platen glass 42a with a predetermined pressing force, and prevents the document from floating from the platen glass 42a when passing through the document reading unit 42.

  On the downstream side of the platen glass 42a, a conveyance roller 47f and a document discharge roller 47g are provided. The document that has passed over the platen glass 42a is discharged to the intermediate tray 44 or the document discharge tray 45 via the conveyance roller 47f and the document discharge roller 47g.

  An intermediate tray swinging plate 44 a is disposed between the document discharge roller 47 g and the intermediate tray 44. The intermediate tray swinging plate 44a has an end on the side of the intermediate tray 44 as a swing center, and in FIG. 1, position 1 (position indicated by a solid line) and position 2 jumped upward from the position 1 are shown. Can swing between the two. When the intermediate tray swinging plate 44 a is at the position 2, the document discharged from the document discharge roller 47 g is collected to the document discharge tray 45. On the other hand, when the intermediate tray swinging plate 44a is at the position 1, the document discharged from the document discharge roller 47g is discharged to the intermediate tray 44. When the sheet is discharged to the intermediate tray 44, the edge of the document is sandwiched between the document discharge rollers 47g and 47g. From this state, the document discharge roller 47g rotates in the reverse direction, so that the document is It is supplied to the conveyance path 48 and is sent out again to the main conveyance path 47 through the sub-conveyance path 48. The reverse rotation operation of the document discharge roller 47g is performed by adjusting the document delivery to the main conveyance path 47 and the image reading timing. Thus, the image on the back side of the document is read by the document reading unit 42.

  Next, the image forming unit 3 will be described. The image forming unit 3 includes an image forming system 31 and a paper transport system 32.

  The image forming system 31 includes a laser scanning unit 31a and a photosensitive drum 31b as a drum type image carrier. The laser scanning unit 31a irradiates the surface of the photosensitive drum 31b with laser light based on document image data converted by the photoelectric conversion element 26 or image data from an external host device. The photosensitive drum 31b rotates in a direction indicated by an arrow in FIG. 1, and an electrostatic latent image is formed on the surface of the photosensitive drum 31b by being irradiated with laser light from the laser scanning unit 31a.

  In addition to the laser scanning unit 31a, a developing unit (developing mechanism) 31c, a transfer unit (transfer mechanism) having a transfer roller 31d, a cleaning unit (cleaning mechanism) 31e, not shown, are provided around the outer periphery of the photosensitive drum 31b. A charging unit (charging mechanism) having a static eliminator and a charging roller 31f is sequentially arranged in the circumferential direction.

  The developing unit 31c develops the electrostatic latent image formed on the surface of the photosensitive drum 31b into a visible image with toner (visualizing substance). The transfer roller 31d transfers a toner image formed on the surface of the photosensitive drum 31b onto a sheet as a recording medium. The cleaning unit 31e removes toner remaining on the surface of the photosensitive drum 31b after toner transfer. The static eliminator removes residual charges on the surface of the photosensitive drum 31b. The charging roller 31f charges the surface of the photosensitive drum 31b before the electrostatic latent image is formed to a predetermined potential.

  When an image is formed on a sheet, the surface of the photosensitive drum 31b is charged to a predetermined potential by the charging roller 31f, and the laser scanning unit 31a irradiates the surface of the photosensitive drum 31b with laser light based on the image data. . Thereafter, the developing unit 31c develops a visible image with toner on the surface of the photosensitive drum 31b, and the toner image is transferred onto the sheet by the transfer roller 31d. Further, after that, the toner remaining on the surface of the photosensitive drum 31b is removed by the cleaning unit 31e, and the residual charge on the surface of the photosensitive drum 31b is removed by the static eliminator. Thereby, one cycle of the image forming operation (printing operation) on the paper is completed. By repeating this cycle, it is possible to continuously form images on a plurality of sheets.

  The paper transport system 32 transports the paper stored in a paper cassette 33 as a paper feeding unit or the paper placed on the manual feed tray 34 one by one to cause the image forming system 31 to perform image formation. A sheet on which an image is formed is conveyed and discharged. As will be described later, the sheet on which the image has been formed is discharged to a sheet post-processing device (not shown) or a multistage sheet discharge tray (not shown) provided on the downstream side of the relay transfer unit 5 via the discharge tray 35 or the relay transfer unit 5. The

  The paper transport system 32 includes a main transport path 36, a first reverse transport path 37, and a second reverse transport path 38 in the apparatus main body, and a relay transport path 51 and a switchback transport path 52 in the relay transport unit 5. .

  One end side of the main conveyance path 36 of the apparatus main body is branched into two, one branch end faces the discharge side of the paper cassette 33 and the other branch end is the discharge side of the manual feed tray 34. Opposite to. Further, the other end side of the main transport path 36 faces the relay transport unit 5. One end side of the second reverse conveying path 38 is connected to the main conveying path 36 on the upstream side (lower side in FIG. 1) from the position where the transfer roller 31d is disposed, and the other end side is disposed where the transfer roller 31d is disposed. Further, it is connected to the main transport path 36 on the downstream side (upper side in FIG. 1). The first reverse conveyance path 37 has one end side downstream from the position where the transfer roller 31d is disposed, and further downstream from the position where the one end side of the second reverse conveyance path 38 is connected. , And the other end faces the paper discharge tray 35.

  A pickup roller 36 a having a semicircular cross section is disposed at one branch end of the main conveyance path 36 (a portion facing the discharge side of the paper cassette 33). By the rotation of the pickup roller 36a, the sheets stored in the sheet cassette 33 can be intermittently fed to the main transport path 36 one by one. Similarly, a pickup roller 36b having a semicircular cross section is disposed at the other branch end of the main conveyance path 36 (a portion facing the discharge side of the manual feed tray 34). Due to the rotation of the pickup roller 36b, the sheets placed on the manual feed tray 34 can be intermittently fed to the main transport path 36 one by one.

  A registration roller 36d is disposed upstream of the position where the transfer roller 31d is disposed in the main conveyance path 36. The registration roller 36d temporarily holds the paper transported along the main transport path 36, and at the same time aligns the leading edge of the paper with the leading edge of the toner image on the surface of the photosensitive drum 31b, to the photosensitive drum 31b. It is a roller which conveys toward.

  The toner image transferred to the paper is located downstream of the transfer position of the transfer roller 31d in the main transport path 36 and upstream of the position where one end of the second reverse transport path 38 is connected. A fixing unit 39 including a pair of heating rollers 39a and a pressure roller 39b for fixing by heating is provided. Further, a discharge roller 36 e for conveying the sheet to the relay conveyance unit 5 is disposed at the downstream end of the main conveyance path 36. The main transport path 36 is provided with a paper sensor (not shown) for detecting passage of paper.

  A branching claw 37 a is disposed at a connection position of the first reverse conveyance path 37 with respect to the main conveyance path 36. The branching claw 37a is rotated from the first position (indicated by a solid line) in FIG. 1 and the first position in the counterclockwise direction in FIG. 1 to open the first reverse conveyance path 37. It is rotatable around a horizontal axis between two positions. When the branching claw 37a is at the first position, the sheet is conveyed toward the relay conveyance unit 5, and when the branch claw 37a is at the second position, the sheet is conveyed toward the discharge tray 35.

  A discharge roller 37 b is disposed in the first reverse conveyance path 37, and when the paper switched back by the switchback conveyance path 52 in the relay conveyance unit 5 is supplied to the first reverse conveyance path 37. The paper is discharged to the paper discharge tray 35 by the discharge roller 37b. The first reverse conveyance path 37 is provided with a sheet sensor (not shown) for detecting the passage of the sheet.

  A branching claw 38 a is disposed at a connection position of the upstream end of the second reverse conveyance path 38 with respect to the main conveyance path 36. The branch claw 38a is rotated from the first position (indicated by the solid line) in FIG. 1 and the first position in the counterclockwise direction in FIG. It is rotatable around a horizontal axis between two positions. When the branch claw 38a is at the first position, the sheet is conveyed toward the relay conveyance unit 5, and when it is at the second position, the sheet can be supplied to the second reverse conveyance path 38.

  In the second reverse conveyance path 38, a conveyance roller 38 b is disposed, and when the paper switched back by the switchback conveyance path 52 in the relay conveyance unit 5 is supplied to the second reverse conveyance path 38. The paper is transported by the transport roller 38b, the paper is introduced into the main transport path 36 on the upstream side of the registration roller 36d, and is transported again through the main transport path 36 toward the transfer roller 31d. That is, an image can be formed on the back side of the paper. The second reverse conveyance path 38 is provided with a sheet sensor (not shown) for detecting the passage of the sheet.

  Next, the relay conveyance unit 5 will be described. The relay conveyance unit 5 is mounted on the main body of the multifunction machine 1 and is provided for conveying the paper after printing to a paper post-processing device or a multi-stage paper discharge tray attached to the side of the multifunction machine 1. Yes. Further, it is provided for discharging the paper after printing to the paper discharge tray 35, or for reversing the paper on which front side printing has been completed when performing double-sided printing with the multifunction device 1. The relay transport unit 5 is formed by a space formed in the main body of the multifunction device 1, specifically, a paper cassette 33, an image forming unit 3 (image forming system 31), and a scanner unit 2. It is provided in the space. In FIG. 1, the sheet post-processing device and the multistage paper discharge tray are not shown.

  The relay transport unit 5 includes a relay transport path 51 and a switchback transport path 52. The relay conveyance path 51 and the switchback conveyance path 52 are respectively connected to the main conveyance path 36 of the apparatus main body. And the branch nail | claw 53 is arrange | positioned in the connection position. The branch claw 53 rotates in the counterclockwise direction in FIG. 1 from the first position (position indicated by a solid line) where the relay conveyance path 51 is opened in FIG. 1 and the switchback conveyance. It is rotatable around a horizontal axis between the second position where the path 52 is opened. When the branching claw 53 is in the first position, paper can be supplied to the relay conveyance path 51, and when it is in the second position, paper can be supplied to the switchback conveyance path 52.

  The relay conveyance path 51 has an upstream end connected to the main conveyance path 36 of the apparatus main body, and a downstream end opposed to a sheet post-processing apparatus or a multi-stage sheet discharge tray attached to the side portion of the multifunction machine 1. A conveyance roller 54 and a discharge roller 55 are disposed in the relay conveyance path 51. In the relay conveyance path 51, the sheet conveyed from the main conveyance path 36 of the apparatus main body is conveyed by a conveyance roller 54, and discharged by a discharge roller 55 to a sheet post-processing apparatus or a multistage discharge tray. The relay conveyance path 51 is provided with a sheet sensor (not shown) for detecting the passage of the sheet.

  The switchback conveyance path 52 has an upstream end connected to the main conveyance path 36 of the apparatus main body, and is formed in the upper part of the relay conveyance unit 5. The switchback conveyance path 52 is used when paper after printing is discharged to the paper discharge tray 35, or when the front-side printed paper is reversed when double-sided printing is performed by the multifunction device 1. The paper reversal in the switchback conveyance path 52 is performed as follows. The sheet conveyed from the discharge roller 36e of the apparatus main body is guided to the switchback conveyance path 52, and the discharge roller 36e is rotated in the reverse direction with the trailing end of the sheet chucked by the discharge roller 36e. As a result, the sheet is reversed, and this time, the sheet is conveyed in the reverse direction on the main conveyance path 36, and then guided to the first reverse conveyance path 37 or the second reverse conveyance path 38. The switchback conveyance path 52 is provided with a paper sensor (not shown) for detecting the presence of paper.

  In the multi-function device 1 including the relay conveyance unit 5 as described above, when a jam occurs, the power of the multi-function device 1 is cut off, and printing processing and paper conveyance are stopped. When the sheet conveyance is stopped, the sheet being conveyed stagnates in the sheet conveyance system 32.

  In the MFP 1 of this example, as described below, the position of the sheet being conveyed through the sheet conveyance system 32 is detected, and the timing at which the sheet conveyance is stopped differs depending on the position of the sheet being conveyed when a jam occurs. By doing so, control is performed so that jam processing can be easily performed. Note that the control subject of this control is mainly a control unit (not shown) of the multifunction device 1, and this control unit specifically performs the processing shown in FIG.

  Here, the sheet conveyance in the sheet conveyance system 32 is performed by transmitting the power of a drive source (not shown) such as a motor to a roller or the like disposed in the sheet conveyance system 32. Here, the multifunction device 1 is provided with a plurality of drive sources so that the respective rollers and the like of the paper transport system 32 can be driven independently. For example, a discharge motor for driving the discharge roller 36e is provided, and a transport motor for driving the transport roller 38b is provided. Each drive source is connected to the control unit of the multifunction device 1, and the drive is controlled by a signal from the control unit of the multifunction device 1.

  Further, the position of the sheet being conveyed through the sheet conveyance system 32 is detected as follows. Paper sensors (paper detection means) for detecting the passage and presence of paper are disposed at a plurality of locations in the paper transport system 32. Specifically, as described above, the sheet sensors are arranged in the main transport path 36, the first reverse transport path 37, the second reverse transport path 38, the relay transport path 51, and the switchback transport path 52. As this paper sensor, for example, a contact sensor or an optical sensor that is turned on when the leading edge of the paper passes and is turned off when the trailing edge passes can be used. Each paper sensor is connected to the control unit of the multifunction device 1, and a paper detection signal is sent to the control unit of the multifunction device 1 when each paper sensor detects passage or presence of the paper. On the other hand, in the multi function device 1, the paper transport speed is determined according to the paper position of the paper transport system 32. Therefore, if the timer is started at a certain reference time (reference time) and the elapsed time from the reference time is measured, the position of the sheet being conveyed can be known from the time measured by the timer. In other words, after the reference time, the sheet being conveyed by the sheet conveyance system 32 is detected by the sheet sensor at a predetermined timing. The reference time includes, for example, the timing at which a sheet is detected by one of the sheet sensors, the timing at which feeding of the sheet stored in the sheet cassette 33 to the main transport path 36 by the pickup roller 36a, There is a timing at which the conveyance of the sheet is started so that the leading edge of the sheet temporarily held by 36d is aligned with the leading edge of the toner image on the surface of the photosensitive drum 31b. In addition, what was built in the control part as a timer can be used.

  Then, after the reference time, the sheet sensor being conveyed by the sheet conveyance system 32 should be detected at a predetermined timing, but if it is not detected at the predetermined timing, the upstream of the sheet sensor. It is determined that a jam has occurred on the side. That is, it is determined that a jam has occurred if the paper is not conveyed at the predetermined timing even though the paper should have been conveyed at the predetermined timing. In this way, the jam detection means can be configured by the paper sensor and the timer. At this time, if a sheet other than the jammed sheet is being conveyed through the sheet conveyance system 32, the position of the sheet being conveyed when the jam occurs can be known.

  In this example, the timing for stopping paper conveyance is made different depending on the paper position during conveyance when a jam occurs. Specifically, if the paper is in a position where it is difficult to remove the paper when a jam occurs, the paper is transported to a position where the paper can be removed without stopping the drive source for transporting the paper immediately after the jam occurs. After that, control is performed to stop the drive source. An example of such control will be described in detail with reference to the flowchart of FIG.

  FIG. 2 shows an example in which the paper is reversed by the switchback conveyance path 52. The drive source of the discharge roller 36e that performs paper reversal according to the position of the paper being conveyed at the time of jam occurrence (hereinafter referred to as “discharge motor”). ") Is a control for changing the stop timing. FIG. 3 is a timing chart showing the driving of the discharge motor that drives the discharge roller 36e.

  This control is performed for each sheet (each sheet other than the jammed sheet) reversed in the switchback conveyance path 52. Here, paying attention to one sheet of paper conveyed, the operation of the discharge motor before and after the reversal of the paper will be described in detail. As described above, in order to reverse the sheet in the switchback conveyance path 52, first, the sheet conveyed from the discharge roller 36e by the forward rotation of the discharge motor is guided to the switchback conveyance path 52, and the trailing edge of the sheet In this state, the discharge roller 36e is reversely rotated by the reverse rotation of the discharge motor.

  As shown in FIG. 2, when the control unit of the multifunction device 1 detects the paper being conveyed from the main conveyance path 36 toward the switchback conveyance path 52 by the reverse sensor, it sets a predetermined time Tf and starts the timer. (Steps S101, S102, S103). Here, the reversing sensor is for starting a timer for measuring the elapsed time from the reference time described above, and is referred to as “reversing sensor” for convenience. As the reversal sensor, a sensor that can set the reference time as described above, in this case, for example, a paper sensor disposed in the main transport path 36 can be used. In FIG. 3, at time t1, the sheet being conveyed from the main conveyance path 36 toward the switchback conveyance path 52 is detected by the reverse sensor, and the reverse sensor is turned on.

  The time Tf is the time required to transport the sheet from the position where the reversing sensor is disposed to the position where the sheet stops when the sheet is reversed (reversal stop position). The reversal stop position is a position where the sheet is temporarily stopped when the sheet is reversed, and is a position where the sheet is fed from the main conveyance path 36 to the switchback conveyance path 52 to the maximum extent.

  Next, it is determined whether or not a jam has occurred in the multifunction device 1 before the time measured by the timer tm1 has passed the time Tf (steps S104 and S105). As described above, in the paper transport system 32 of the multifunction machine 1, a jam occurs when the paper is not transported at the predetermined timing even though the paper should have been transported at the predetermined timing. It is determined that Here, it is determined whether or not a jam has occurred before the sheet is sent to the reversal stop position, that is, before the sheet is reversed. If it is determined that a jam has occurred, the process proceeds to step S111. If no jam has occurred, the process proceeds to step S106.

  In step S106, a predetermined time Tb is set and the time count of the timer is reset to zero. Next, reverse rotation of the discharge motor is started to rotate the discharge roller 36e in reverse, and a timer is started (steps S107 and S108). As a result, the sheet that has been transported to the reversal stop position is reversed, and is then transported from the switchback transport path 52 toward the main transport path 36. The time Tb is a time required for transporting the paper from the above-described reversal stop position to the position where the paper has been reversed at the time of paper reversal (reversal completion position). The inversion completion position is a position where the sheet is completely fed from the switchback conveyance path 52 to the main conveyance path 36 and the sheet conveyance is completed.

  Next, it is determined whether or not a jam has occurred in the multifunction device 1 before the time measured by the timer tm2 elapses the time Tb (steps S109 and S110). Here, it is determined whether or not a jam has occurred before the sheet is sent from the reversal stop position to the reversal completion position, that is, after the reversal of the sheet. As a result of this determination, if a jam has occurred, the process proceeds to step S121. Conversely, if a jam has not occurred, this control is terminated assuming that the reversal has been performed normally. As described above, when the sheet is normally reversed, the discharge motor is driven as indicated by “A. Normal reversal” in FIG. In FIG. 3, the reverse rotation of the discharge motor is started at time t3, and the time from time t1 to time t3 described above is time Tf.

  If a jam occurs before the paper is sent to the reverse stop position, that is, if a jam occurs before the paper is turned over, the discharge motor is stopped as follows. In step S111, the time Ts is set and the time count of the timer is reset to zero. The time Ts is obtained by subtracting the time required to reversely convey the sheet from the above-described time Tf to a position where the sheet can be removed from the reversal stop position (paper removable position). It is a value obtained by subtracting the time tm1. The paper removable position is a position where the paper can be removed by opening the cover of the multifunction device 1 when the paper is stagnated at that position. In other words, it is a position where jam processing can be easily performed.

  Next, it is determined whether or not the time Ts is greater than 0 (step S112). Here, based on the value of the time Ts calculated in step S111, it is determined whether or not the sheet is currently in a sheet removable position. More specifically, in this case, before the sheet is reversed, the sheet is being conveyed from the main conveyance path 36 toward the switchback conveyance path 52 by the forward rotation of the discharge roller 36e. For this reason, if the value of Ts is larger than 0, the portion of the paper that is being transported to the switchback transport path 52 is small (there are many portions that remain in the main transport path 36), and the paper is in a paper removable position. It is determined. On the other hand, if the value of Ts is not larger than 0, there are many portions of the paper that are transported to the switchback transport path 52 (there are few portions remaining in the main transport path 36), and the paper is not in the paper removable position. It is determined that there is no.

  If it is determined in step S112 that Ts is larger than 0 (Ts> 0), it is determined that the sheet is in a sheet removable position and the discharge motor is stopped (step S116). As a result, the paper conveyance is stopped and the paper is stagnated. At this time, since the paper is stagnating at the paper-removable position, it can be removed by opening the cover of the multifunction machine 1 or the like. In other words, since the sheet is in the position where the sheet can be removed, the jam processing can be easily performed even if the discharge motor is stopped immediately after the jam occurs.

  However, if Ts is not greater than 0 (Ts ≦ 0) in the determination in step S112, the sheet is not in the sheet removable position. For this reason, a timer is started, and until the time tm3 measured by this timer has passed the time | Ts | (−Ts), reverse rotation of the discharge motor is started to reversely rotate the discharge roller 36e (steps S113, S114, S115). Then, after the time measured by the timer tm3 has passed the time -Ts, the discharge motor is stopped (step S116). With such control, when a jam occurs, the paper that was not in the paper removal position is conveyed to the main conveyance path 36 side by rotating the discharge motor in reverse for the time −Ts, and reaches the paper removal position. I try to return it. Then, after transporting to the paper removable position, the discharge motor is stopped. At this time, since the sheet is returned to the sheet removable position and is stagnated, it can be removed by opening the cover of the multifunction machine 1 or the like. In this way, if the paper is not in the paper-removable position when a jam occurs, the paper discharge motor is not stopped immediately after the paper jam occurs, but the paper discharge is stopped after the paper is transported to the paper removable position, and the jam processing is performed. Can be done easily. As described above, when a jam occurs before paper reversal and the paper is not in a position where paper can be removed, the discharge motor is driven as shown by “B. Pre-reversal-stop jam detection” in FIG. To do. Here, the discharging motor that has rotated in the forward direction is rotated reversely after the jam detection, and is driven only for the time −Ts. In FIG. 3, occurrence of a jam is detected at time t2 before the paper is reversed, and reverse rotation of the discharge motor is started at time t2. At time t4, the reverse rotation of the discharge motor is stopped, and the time from time t2 to time t4 is time -Ts.

  On the other hand, if a jam occurs before the paper is sent from the reversal stop position to the reversal completion position, that is, if a jam occurs after the paper is reversed, the discharge motor is stopped as follows. Done. In step S121, the time Ts' is set and the time count of the timer is reset to zero. The time Ts ′ is a value obtained by subtracting the time tm2 measured by the timer until the occurrence of a jam from the time required to reversely convey the sheet from the reversal stop position to the position where the sheet can be removed.

  Next, it is determined whether or not the time Ts ′ is greater than 0 (step S122). Here, based on the value of the time Ts ′ calculated in the above step S121, it is determined whether or not the sheet is currently at the sheet removable position. More specifically, in this case, after the sheet is reversed, the sheet is being conveyed from the switchback conveyance path 52 toward the main conveyance path 36 by the reverse rotation of the discharge roller 36e. For this reason, if the value of Ts ′ is smaller than 0, the portion of the paper that is being transported to the main transport path 36 is large (the portion that remains in the switchback transport path 52 is small), and the paper reaches the position where the paper can be removed. Being transported. On the other hand, if the value of Ts ′ is not smaller than 0, the portion of the paper transported to the main transport path 36 is small (many portions remain in the switchback transport path 52), and the paper reaches the position where the paper can be removed. Not being transported.

  If it is determined in step S122 that Ts ′ is smaller than 0 (Ts ′ <0), the discharge motor is stopped assuming that the sheet is at the sheet removable position (step S125). As a result, the paper conveyance is stopped and the paper is stagnated. At this time, the sheet is transported to the sheet-removable position and stagnated, so that it can be removed by opening the cover of the multifunction machine 1 or the like. In other words, since the sheet is in the position where the sheet can be removed, the jam processing can be easily performed even if the discharge motor is stopped immediately after the jam occurs.

  However, if Ts ′ is not smaller than 0 (Ts ′ ≧ 0) in the determination in step S122, the sheet is not in the sheet removable position. For this reason, a timer is started and the discharge roller 36e is reversely rotated by continuing the reverse rotation of the discharge motor until the time tm4 measured by the timer has passed the time Ts' (steps S123 and S124). Then, after the time measured by the timer tm4 has passed the time Ts', the discharge motor is stopped (step S125). By such control, when a jam occurs, the paper that was not in the paper removal position is further conveyed to the main conveyance path 36 side by continuing the reverse rotation of the discharge motor for the time Ts ′, and the paper is removed. It transports to a possible position. Then, after transporting to the paper removable position, the discharge motor is stopped. At this time, the sheet is transported to the sheet-removable position and stagnated, so that it can be removed by opening the cover of the multifunction machine 1 or the like. Thus, if the paper is not in the paper removal position when a jam occurs, the discharge motor is not stopped immediately after the jam occurs, the stop timing is delayed, and the discharge motor is moved after the paper is conveyed to the paper removal position. It is stopped so that jam processing can be easily performed. As described above, when a jam occurs after paper reversal and the paper is not in a position where paper can be removed, the discharge motor is driven as shown in “C. After reversal-jam detection stop” in FIG. . Here, the driving of the discharge motor that has been rotating in the reverse direction is continued only for the time Ts ′ after the jam detection. In FIG. 3, occurrence of a jam is detected at time t5 after the paper is reversed. At time t5, the reverse rotation of the discharge motor is not stopped and continues until time t6. The time from time t5 to time t6 is time Ts ′.

  As described above, when performing sheet reversal in the multifunction machine 1 including the relay conveyance unit 5, the position of the sheet being conveyed through the sheet conveyance system 32 is detected, and according to the position of the sheet being conveyed when a jam occurs, The timing for stopping paper conveyance is different. In other words, if a paper being transported is in a paper removable position when a jam occurs, the paper discharge motor that drives the discharge roller 36e is immediately stopped to stop the paper transport, while the paper being transported is brought to a paper removable position. If not, the discharge motor is not stopped immediately, but after the paper is transported to the paper removable position, the discharge motor is stopped to stop the paper transport. Thus, in any case, the sheet can be removed by opening the cover of the multifunction device 1 or the like, and the jam processing can be easily performed.

  Although the case where the sheet is reversed using the switchback conveyance path 52 has been described above, the same applies to other cases. For example, when the paper is transported from the apparatus main body to the relay transport unit 5 by the discharge roller 36e without reversing the paper, the stop timing of the discharge motor is changed according to the paper position being transported when the jam occurs. Therefore, the jam processing can be facilitated.

  Further, for the rollers other than the discharge roller 36e, the jam processing can be facilitated by changing the timing of stopping the respective drive sources in accordance with the position of the paper being conveyed when the jam occurs. For example, in the case of the transport roller 54 and the discharge roller 55 in the relay transport path 51 of the relay transport unit 5, jam processing is performed when all parts of the paper (all parts from the front end to the rear end) stagnate in the relay transport unit 5. Is extremely difficult. For this reason, immediately after the jam occurs, the drive sources of the transport roller 54 and the discharge roller 55 are not stopped, but the stop timing is delayed so that the paper removal position (in this case, the leading edge of the paper protrudes from the discharge roller 55). Jam processing can be easily performed by stopping the drive source and stopping the sheet conveyance after the sheet is conveyed to the correct position).

  Note that, as described above, if the paper stagnates at a position where it is difficult to perform jam processing, it may be difficult to remove the paper unless the drive source for carrying the paper is reversely rotated. By the way, since the discharge roller 36e is a roller for reversing the paper, it is possible to easily perform control for switching the rotation direction even in a normal time when no jam occurs. That is, a discharge motor that can easily switch the rotation direction is used as the discharge motor that drives the discharge roller 36e. However, some drive sources that carry the paper are not supposed to switch the rotation direction frequently in normal times. Therefore, in the above-described control, it may be difficult to immediately reverse the drive source when a jam occurs. Therefore, in such a case, when a jam occurs, such a drive source is not immediately reversely rotated, but after the energization of the multifunction device 1 is cut off, it is reversed for a predetermined time at the start of the next energization. Try to rotate. By this reverse rotation, the paper can be forcibly fed back to a position where the paper can be removed. As a result, the cover of the multifunction device 1 can be removed by opening it or the like. Here, when the next energization is started, for example, when the multifunction device 1 is de-energized due to the occurrence of a jam, and then the cover opened for jam processing is closed.

1 is a diagram illustrating a schematic configuration of a multifunction machine to which the present invention is applied. 6 is a flowchart illustrating control for changing a stop timing of a driving source of a roller that performs paper reversal when reversing paper. 6 is a timing chart illustrating driving of a driving source of a roller that performs sheet reversal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunction machine 2 Scanner part 3 Image formation part 5 Relay conveyance unit 31 Image formation system 32 Paper conveyance system 33 Paper cassette 35 Discharge tray 36 Main conveyance path 36e Discharge roller 37 First reverse conveyance path 38 Second reverse conveyance path 51 Relay Transport path 52 Switchback transport path

Claims (4)

The position of the paper being conveyed along the paper conveyance path by a plurality of drive sources, the image forming means forming an image on the paper conveyed through the paper conveyance path, and the paper detection means conveying the paper conveyance path In an image forming apparatus configured to detect occurrence of a jam by a jam detection unit,
When the occurrence of a jam is detected by the jam detection unit, the timing of stopping each drive source for carrying the paper is varied according to the position of the paper when the jam is detected by the paper detection unit. An image forming apparatus.   2. The image according to claim 1, wherein a plurality of the paper detection means are provided in a paper conveyance path, and a paper position being conveyed is detected based on an on / off timing of the paper detection means. Forming equipment.   When the paper position at the time of occurrence of a jam detected by the paper detection unit straddles the transport path of an adjacent unit among the units disposed in the image forming apparatus in the paper transport path. The drive source that transports paper from one of the adjacent units to the other unit can be removed by feeding the paper to the transport path of any unit without stopping the drive source immediately after a jam occurs The image forming apparatus according to claim 1, wherein the image forming apparatus stops after being conveyed to a correct position.   2. The drive mechanism according to claim 1, wherein some of the driving sources that transport the paper are reversely rotated for a predetermined time at the start of the next energization after the energization of the image forming apparatus is cut off due to the occurrence of a jam. Image forming apparatus.

Images