JP2006030407A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein paper jamming is prevented, and an ejected recording paper is also prevented from being wavy. <P>SOLUTION: A multi-functioned machine 1 is provided with: a paper size prescribing part 111 for prescribing at least a paper size of a recording paper; a transporting speed setting part 112 for setting a transporting speed of a fixing roller in the transfer device side and that of an eject roller in the discharge port side; a fixing roller driving part 1311 for driving the fixing roller at the transporting speed of the fixing roller which is set by the transporting speed setting part 112; and an eject roller driving part 1312 for driving the eject roller at the transporting speed of the eject roller which is set by the transporting speed setting part 112. The transporting speed setting part 112 makes the transporting speed of the fixing roller higher than that of the eject roller and sets a speed difference between the transporting speed of the fixing roller and that of the eject roller in accordance with the paper size of the recording paper which is prescribed by the paper size prescribing part 111. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus including at least two rollers between a transfer device that fixes a toner image on a recording sheet and a discharge port that discharges the recording sheet conveyed from the transfer device to the outside of the apparatus. .

  In general, in an image forming apparatus such as a printer or a copying machine, an image forming unit using a photosensitive drum is widely used. In such an image forming apparatus, an electrostatic region is formed on the surface of the photosensitive drum by the charging unit, and an electrostatic latent image based on image data is formed in the electrostatic region by laser light or the like irradiated from the exposure unit. The electrostatic latent image is developed into a toner image by the developing unit. Then, the toner image is transferred to the recording paper in the transfer unit, and the toner remaining on the surface of the photosensitive drum is removed in the cleaning unit. On the other hand, the recording paper on which the toner image has been transferred is heated by a fixing roller provided in the fixing unit, whereby the toner image is fixed, and is discharged to the outside by a discharge roller.

  When the toner image is heat-fixed in this way, moisture contained in the paper may evaporate and the paper may be bent into a waveform. In order to solve such a problem, for example, in Patent Document 1, the shape of a recording sheet that is curved after fixing is flattened by increasing the conveyance speed of the discharge roller more than the conveyance speed of the fixing roller and tensioning the recording sheet. The technology to make is disclosed.

In recent years, there has been known an image forming apparatus that employs a so-called short path mechanism in which a paper conveyance path length is shortened in order to improve a printing speed. In the image forming apparatus of this short path mechanism, there are only discharge rollers after the fixing roller, and the conveyance path between the fixing roller and the discharge roller may be curved.
JP 2004-35177 A

  When the technique of Patent Document 1 is used for the image forming apparatus employing the above-described short path mechanism, the fixing roller is used because the recording sheet is tensioned by making the conveyance speed of the discharge roller faster than the conveyance speed of the fixing roller. The recording surface of the recording paper comes into sliding contact with the inner portion of the curved conveyance path between the paper and the discharge roller. When the recording surface of the recording paper is brought into sliding contact, the melted toner just fixed may adhere to the inner portion of the conveyance path, and the toner may adhere in an icicle shape every time the number of printing is repeated. In some cases, the toner adhering in the shape of an icicle blocks the conveyance path, and a paper jam occurs.

  In addition, the recording paper can be bent in the conveyance path between the fixing roller and the discharge roller by making the conveyance speed of the discharge roller slower than the conveyance speed of the fixing roller. However, conventionally, the fixing roller and the discharge roller are always driven at the same speed once the conveyance speed is set. Therefore, for example, when A3 size recording paper is transported in accordance with the transport speed of A4 size recording paper, A3 size recording paper is longer than A4 size recording paper, so the recording paper is too bent. As a result, the recording paper is curved in a waveform between the fixing roller and the discharge roller and may be discharged as it is.

  The present invention has been made to solve the above-described problems, and provides an image forming apparatus that can prevent a paper jam and can prevent a discharged recording sheet from having a waveform. It is the purpose.

  An image forming apparatus according to the present invention includes at least two rollers between a transfer device that transfers a toner image onto a recording sheet and a discharge port that discharges the recording sheet conveyed from the transfer device to the outside of the apparatus. A sheet length specifying means for specifying at least the sheet length of the recording sheet, and a conveying speed setting means for setting the conveying speed of the first roller on the transfer device side and the conveying speed of the second roller on the discharge port side. The first roller driving means for driving the first roller at the conveying speed of the first roller set by the conveying speed setting means, and the conveying speed of the second roller set by the conveying speed setting means. Second roller driving means for driving the second roller, and the conveying speed setting means makes the conveying speed of the first roller faster than the conveying speed of the second roller. It is set according to the speed difference between the conveying speed of the conveying speed and the second roller of the first roller to the sheet length of the recording paper to be identified by said sheet length specifying means.

  According to this configuration, at least the sheet length of the recording sheet is specified, and the conveyance speed of the first roller on the transfer device side and the conveyance speed of the second roller on the discharge port side are set. Here, the transport speed of the first roller is made faster than the transport speed of the second roller, and the speed difference between the transport speed of the first roller and the transport speed of the second roller depends on the length of the specified recording paper. Is set. The first roller is driven by the set transport speed of the first roller, and the second roller is driven by the set transport speed of the second roller.

  Therefore, it is possible to prevent paper jam by making the conveyance speed of the first roller faster than the conveyance speed of the second roller and bending the recording paper in the conveyance path between the first roller and the second roller, In addition, by setting the speed difference between the conveyance speed of the first roller and the conveyance speed of the second roller according to the sheet length of the recording sheet, the discharged recording sheet can be prevented from having a waveform.

  In the above image forming apparatus, the first roller is a fixing roller for fixing the toner image on the recording paper, and the second roller is configured to feed the recording paper on which the toner image is fixed by the fixing roller to the outside of the apparatus. A discharge roller that discharges from a discharge port; a conveyance path between the fixing roller and the discharge roller is curved; and the conveyance speed setting unit is configured such that the recording surface of the recording sheet does not slide on the conveyance path It is preferable to set the conveying speed of the fixing roller and the discharge roller.

  According to this configuration, the conveyance path between the fixing roller for fixing the toner image on the recording sheet and the discharge roller for discharging the recording sheet on which the toner image is fixed by the fixing roller to the outside of the apparatus from the discharge port is curved. In addition, the conveyance speeds of the fixing roller and the discharge roller are set so that the recording surface of the recording sheet does not slide on the conveyance path. Accordingly, since the conveyance speed of the fixing roller and the discharge roller is set so that the recording surface of the recording sheet does not slide on the curved conveyance path between the fixing roller and the discharge roller, the melted toner just fixed is conveyed. Adhesion to the inner part of the path can be prevented, and paper jams can be prevented.

  In the image forming apparatus, the conveyance speed setting unit may increase the conveyance speed of the fixing roller as the sheet length in a direction parallel to the conveyance direction of the recording sheet specified by the sheet length specifying unit increases. It is preferable to set the speed difference with the transport speed of the discharge roller to be small.

  According to this configuration, the difference between the conveyance speed of the fixing roller and the conveyance speed of the discharge roller is set to be smaller as the sheet length in the direction parallel to the conveyance direction of the specified recording sheet becomes longer. Therefore, the longer the paper length in the direction parallel to the conveyance direction of the recording paper, the smaller the deflection of the recording paper, and it is possible to prevent the discharged recording paper from having a waveform.

  In the image forming apparatus, the conveyance speed setting unit may maintain the conveyance speed of the fixing roller constant regardless of the sheet length of the recording sheet specified by the sheet length specifying unit, and the conveyance speed of the discharge roller. It is preferable to set according to the paper length of the recording paper specified by the paper length specifying means.

  According to this configuration, the conveyance speed of the fixing roller is set to be constant regardless of the sheet length of the recording sheet specified by the sheet length specifying unit, and the conveyance speed of the discharge roller is set for the recording sheet specified by the sheet length specifying unit. It is set according to the paper length. Therefore, by changing the conveyance speed of the discharge roller according to the paper length without changing the conveyance speed of the fixing roller according to the paper length, it is not necessary to set the conveyance speed of the fixing roller. It is possible to make the conveyance speed of the fixing roller faster than the conveyance speed of the discharge roller only by setting only.

  In the image forming apparatus, it is preferable that the second roller driving unit increases the conveyance speed of the discharge roller after the recording sheet has passed through the nip portion of the fixing roller than before the passage.

  According to this configuration, after the recording sheet passes through the nip portion of the fixing roller, the conveyance speed of the discharge roller is made faster than before the passage, so that the speed of discharging the recording sheet can be improved.

  According to the first aspect of the present invention, the conveyance speed of the first roller is made faster than the conveyance speed of the second roller, and the recording paper is bent along the conveyance path between the first roller and the second roller. A paper jam can be prevented, and the discharged recording paper has a waveform by setting the speed difference between the transport speed of the first roller and the transport speed of the second roller according to the paper length of the recording paper. Can be prevented.

  According to the second aspect of the present invention, the curve between the fixing roller for fixing the toner image on the recording paper and the discharge roller for discharging the recording paper on which the toner image is fixed by the fixing roller to the outside of the apparatus from the discharge port. Since the conveyance speed of the fixing roller and the discharge roller is set so that the recording surface of the recording sheet does not slide on the conveyance path, it is possible to prevent the melted toner just fixed from adhering to the inner part of the conveyance path. Paper jam can be prevented.

  According to the third aspect of the invention, the longer the paper length in the direction parallel to the conveyance direction of the recording paper, the smaller the deflection of the recording paper, and the discharged recording paper has a waveform. Can be prevented.

  According to the fourth aspect of the present invention, the setting of the conveyance speed of the fixing roller is performed by changing the conveyance speed of the discharge roller according to the paper length without changing the conveyance speed of the fixing roller according to the paper length. This eliminates the need to set the transport speed of the fixing roller, and the transport speed of the fixing roller can be made faster than the transport speed of the discharge roller.

  According to the fifth aspect of the present invention, the speed at which the recording paper is discharged can be improved.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view schematically showing an internal configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is configured as a multifunction machine 1 having multiple functions such as a copy function, a printer function, a facsimile function, and a scanner function. The multi-function device 1 is disposed above the main body unit 2, the stack tray 3 disposed on the left side of the main body unit 2, the document reading unit 5 disposed on the top of the main body unit 2, and the document reading unit 5. And a document feeding unit 6 provided.

  An operation unit 47 is provided at the front part of the multifunction machine 1. The operation unit 47 displays a start key 471 for a user to input a print execution instruction, a ten key 472 for inputting the number of copies to be printed, operation guide information for various copying operations, and the like. A display unit 473 formed of a liquid crystal display or the like having a touch panel function, a reset key 474 for resetting setting contents set in the display unit 473, and a stop key for stopping a printing (image forming) operation being executed 475 and a function switching key 477 for switching between a copy function, a printer function, a scanner function, and a facsimile function.

  The document reading unit 5 includes a scanner unit 51 including a CCD (Charge Coupled Device) sensor and an exposure lamp, and a document table 52 and a document reading slit 53 made of a transparent member such as glass. The scanner unit 51 is configured to be movable by a drive unit (not shown). When reading a document placed on the document table 52, the scanner unit 51 is moved along the document surface at a position facing the document table 52, and the document image is scanned. The image data acquired while scanning is output to the control unit 100 (FIG. 3). Further, when reading a document fed by the document feeding unit 6, the document is moved to a position facing the document reading slit 53 and synchronized with the document feeding operation by the document feeding unit 6 via the document reading slit 53. The image of the original is acquired and the image data is output to the control unit 100.

  The document feeding unit 6 includes a document placing unit 61 for placing a document, a document discharge unit 62 for discharging a document whose image has been read, and a document placed on the document placing unit 61. A document transport mechanism 63 including a paper feed roller (not shown), a transport roller (not shown) and the like for feeding the paper one by one to a position facing the document reading slit 53 and discharging it to the document discharge section 62 is provided. The document conveyance mechanism 63 further includes a sheet reversing mechanism (not shown) that reverses the document and reversely conveys the document to a position facing the document reading slit 53, and scans both sides of the document through the document reading slit 53. 51 can be read.

  The document feeding unit 6 is provided so as to be rotatable with respect to the main body unit 2 so that the front side thereof can move upward. By moving the front side of the document feeder 6 upward to open the upper surface of the document table 52, the operator can place a read document, for example, a book in a spread state, on the upper surface of the document table 52. It has become.

  The main unit 2 includes a plurality of paper feed cassettes 461, a paper feed roller 462 that feeds recording paper from the paper feed cassette 461 one by one and transports it to the recording unit 40, and a recording paper transported from the paper feed cassette 461. And a recording unit 40 for forming an image.

  The recording unit 40 outputs an optical beam or the like based on the image data acquired by the scanner unit 51 to expose the photosensitive drum 43, and a developing unit 44 that forms a toner image on the photosensitive drum 43. A transfer unit 41 that transfers the toner image on the photosensitive drum 43 to a recording sheet; a fixing unit 45 that heats the recording sheet to which the toner image is transferred and fixes the toner image on the recording sheet; Discharge rollers 463 and 464 that are provided in the sheet conveyance path and convey the recording sheet to the stack tray 3 or the discharge tray 48 are provided. The fixing unit 45 includes a fixing roller 451 and heats and pressurizes the printing paper on which the toner image is transferred to fix the toner image on the printing paper.

  When forming images on both sides of the recording paper, the recording unit 40 forms an image on one side of the recording paper, and then the recording paper is nipped by the discharge roller 463 on the discharge tray 48 side. . In this state, the discharge roller 463 is reversed to switch back the recording paper, and the recording paper is sent to the paper transport path L and transported again to the upstream area of the recording unit 40, and an image is formed on the other surface by the recording unit 40. Thereafter, the recording paper is discharged to the stack tray 3 or the discharge tray 48.

  FIG. 2 is a cross-sectional view schematically showing the vicinity of the fixing roller and the discharge roller of the multifunction machine 1 shown in FIG. In FIG. 2, only the path through which the recording sheet conveyed from the fixing roller 451 is discharged from the discharge port 465 to the discharge tray 48 is shown. As shown in FIG. 2, in the short path mechanism, the conveyance path 49 between the fixing roller 451 and the discharge roller 463 is curved toward the discharge tray 48, and between the fixing roller 451 and the discharge roller 463, No other rollers are provided. The recording paper P on which the toner image is transferred by the photosensitive drum 43 is heated and pressed by the fixing roller 451 to fix the toner image, and is discharged from the discharge port 465 to the discharge tray 48 by the discharge roller 463.

  In the present exemplary embodiment, the conveyance speed control of the fixing roller 451 and the discharge roller 463 of the fixing unit 45 will be described. However, the present invention is not particularly limited to this, and a transfer unit (transfer device) that transfers a toner image onto a recording sheet. ) 41 and the conveyance speed control of the two rollers provided between the discharge port 465 for discharging the recording sheet conveyed from the transfer unit 41 to the discharge tray 48 outside the apparatus.

  FIG. 3 is a functional block diagram illustrating a schematic configuration of the multifunction machine 1. The multifunction machine 1 includes a control unit 100 that controls the operation of the entire apparatus. The control unit 100 includes a scanner unit 120 that can read a document image including an exposure lamp 121 and a CCD 122, and a recording unit 130 that includes a paper transport unit 131, an image forming unit 132, a transfer unit 133, a fixing unit 134, and the like. Is connected. The control unit 100 also includes an image memory 140 in which document data read by the scanner unit 51 is temporarily stored, and a large capacity HDD (storage device) having a storage capacity capable of storing a large amount of document data. 150 is connected.

  When the scanner unit 120 reads an original, the image processing unit 160 converts an analog image output from the scanner unit 120 into a digital image, performs image processing for improving image quality, and then converts the image into a compressed image. Note that in this specification, image data is also appropriately expressed as an image in order to simplify the description. The converted compressed image is written in the image memory 140. The control unit 100 stores the compressed image written in the image memory 140 in the HDD 150 as file data to be document managed. When printing out a registered document, file data (compressed image) to be printed out is written to the image memory 140 from the HDD 150 or each computer on the network, and the image processing unit 160 decompresses the compressed file data. In the case of laser exposure, for example, it is converted into a laser signal that is an analog modulation signal. The recording unit 130 (image forming unit 132) executes printout based on, for example, an analog-modulated laser signal.

  The operation panel unit 190 is for an operator (user) to input various instructions necessary for the operation of the multifunction device 1. The operation panel unit 190 is composed of an LCD (liquid crystal display) or the like. And an operation key unit 192 including a numeric keypad for inputting the number of out copies and the like. Note that the display unit 191 preferably includes a touch panel function and has a configuration in which an operator can input necessary instructions by touching the touch panel.

  The operation panel unit 190 receives an input of an instruction from the user related to copying, and transmits the input to the control unit 100. The operation panel unit 190 receives a message from the multifunction device 1 to the user and the like from the control unit 100 and displays the message. In this embodiment, input of an instruction from the user according to the present invention is mainly an instruction to start copying by pressing a start key. In response to this, the operation panel unit 190 transmits a copy start signal to the control unit 100.

  The scanner unit 120 takes in a copy document placed on the document placement unit 61 shown in FIG. 1 by the instruction of the control unit 100 by the document feeding unit 6 and reads an image of the document (copy document) into the image memory 140 as read image data. Store. When the document feeder 6 pulls in the document, it reads the size of the document by the position of the width detection cursor (not shown) and the length detection sensor (not shown), and reads the size information of the read document in the image memory 140. Store as part of the data. Here, the image width is a document size in a direction perpendicular to the document feeding direction (main scanning direction) and the length is a document size in the document feeding direction (sub-scanning direction). The multifunction device 1 according to the present invention can read originals having the same width and different lengths, and automatically select and copy a sheet that matches the size of the original. When the reading of all the originals placed on the original placement unit 61 is completed, the scanner unit 120 indicates that the original sizes are mixed and the size (for example, A3) when the number of originals and the original sizes are mixed. And A4) to the control unit 100.

  The control unit 100 includes a CPU (Central Processing Unit) (not shown) and a storage unit such as a RAM (Random Access Memory) or a ROM (Read Only Memory) that stores a program that defines the operation of the CPU. is doing. That is, the control unit 100 includes a computer. Accordingly, the control unit 100 functions as a paper size specifying unit 111, a conveyance speed setting unit 112, a fixing roller conveyance speed control unit 113, and a discharge roller conveyance speed control unit 114. The paper transport unit 131 includes a fixing roller driving unit 1311 and a discharge roller driving unit 1312. The HDD 150 includes a conveyance speed storage unit 151.

  The above-described program for realizing these functions by being read by a computer as the control unit 100 is stored in a non-volatile and large-capacity external storage device such as an HDD (Hard Disk Drive) 150, and the above-described RAM or the like. By appropriately transferring to the main storage device, it can be used for execution by the CPU. The program can be supplied through a computer-readable recording medium such as a ROM or a CD-ROM, or can be supplied through a transmission medium such as a network connected to a network interface (not shown) described later. When the program is supplied through the ROM, it can be used for execution by the CPU by mounting the ROM in which the program is recorded on the control unit 100.

  The paper size specifying unit 111 specifies at least the paper length of the recording paper from the document size read by the scanner unit 120. The paper length is a length in a direction parallel to the recording paper conveyance direction. That is, the dimensions of the standard size recording sheets such as the A and B rows are determined in advance. Therefore, the paper size specifying unit 111 specifies the paper size of the recording paper and specifies the orientation of the recording paper with respect to the transport direction (whether the long side of the recording paper is perpendicular or parallel to the transport direction). Thus, the sheet length can be specified.

  Note that the paper size specifying unit 111 in this embodiment specifies the paper length of the recording paper based on the document size read by the scanner unit 120 of the multifunction device 1, but the present invention is not particularly limited to this. When the paper size (paper length) of the recording paper is designated by the operation panel unit 190, the paper length of the recording paper may be specified based on the paper size designated by the operation panel unit 190. When the image forming apparatus is a printer apparatus, the sheet length of the recording sheet may be specified based on a sheet size (sheet length) designated by a terminal device such as a personal computer connected to the printer apparatus.

  In the conveyance speed storage unit 151, the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 are stored in advance in association with the sheet length of the recording sheet. The conveyance speed of the fixing roller 451 is set faster than the conveyance speed of the discharge roller 463. Further, the speed difference between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 is set according to the sheet length of the recording sheet, and the sheet length in the direction parallel to the recording sheet conveyance direction is long. The speed difference is set to be smaller.

  For example, when the paper size is A4 size and the long side of the recording paper is conveyed in a state parallel to the conveyance direction, the conveyance speed of the fixing roller 451 is 230 mm / s, and the conveyance speed of the discharge roller 463 is In this case, the speed difference between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 is 4 mm / s. On the other hand, when the paper size is A3 and the long side of the recording paper is conveyed in a state parallel to the conveyance direction, the conveyance speed of the fixing roller 451 is 230 mm / s, and the conveyance speed of the discharge roller 463 is In this case, the speed difference between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 is 2 mm / s.

  Note that the speed difference between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 is such that the recording surface of the recording paper passing through the conveyance path between the fixing roller 451 and the discharge roller 463 does not slide on the conveyance path. It is preferable that the non-recording surface of the recording paper (the back surface of the recording surface) is set so as not to be in sliding contact with the conveyance path.

  In addition, the conveyance speed of the fixing roller 451 in this embodiment is set to be constant regardless of the paper length, and the conveyance speed of the conveyance roller 463 is set to a different speed for each paper length. Therefore, by changing the conveyance speed of the discharge roller 463 according to the paper length without changing the conveyance speed of the fixing roller 451 according to the paper length, setting of the conveyance speed of the fixing roller 451 becomes unnecessary, and the discharge roller Only by setting the conveyance speed of 463, the conveyance speed of the fixing roller 451 can be made faster than the conveyance speed of the discharge roller 463.

  The conveyance speed setting unit 112 reads the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 corresponding to the sheet length of the recording sheet specified by the sheet size identification unit 111 from the conveyance speed storage unit 151, and By setting the conveyance speed and the conveyance speed of the discharge roller 463, the conveyance speed of the fixing roller 451 is made faster than the conveyance speed of the discharge roller 463, and the speed difference between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463. Is set according to the paper length of the recording paper specified by the paper size specifying unit 111.

  The fixing roller conveyance speed control unit 113 outputs a driving signal for rotating the fixing roller 451 at the conveyance speed of the fixing roller 451 set by the conveyance speed setting unit 112 to the fixing roller driving unit 1311.

  The discharge roller conveyance speed control unit 114 outputs a drive signal for rotating the discharge roller 463 at the conveyance speed of the discharge roller 463 set by the conveyance speed setting unit 112 to the discharge roller driving unit 1312. In this embodiment, the discharge roller conveyance speed control unit 114 detects whether or not the recording paper has passed through the nip portion of the fixing roller 451, and detects that the recording paper has passed through the nip portion of the fixing roller 451. In this case, the conveyance speed of the discharge roller 463 may be faster than before the passage. In this case, after the recording paper passes through the nip portion of the fixing roller 451, the conveyance speed of the discharge roller 463 is made faster than before the passage, so that the speed of discharging the recording paper can be improved.

  The fixing roller driving unit 1311 rotates the fixing roller 451 based on the drive signal output from the fixing roller conveyance speed control unit 113 and conveys the recording paper at the conveyance speed set by the conveyance speed setting unit 112.

  The discharge roller driving unit 1312 rotates the discharge roller 463 based on the drive signal output from the discharge roller conveyance speed control unit 114 and conveys the recording paper at the conveyance speed set by the conveyance speed setting unit 112.

  In the present exemplary embodiment, the fixing roller 451 corresponds to an example of a first roller, the discharge roller 463 corresponds to an example of a second roller, and the paper size specifying unit 111 corresponds to an example of a paper length specifying unit. The speed setting unit 112 corresponds to an example of a conveyance speed setting unit, the fixing roller conveyance speed control unit 113 and the fixing roller driving unit 1311 correspond to an example of a first roller driving unit, and the discharge roller conveyance speed control unit 114 and the discharge roller. The driving unit 1312 corresponds to an example of a second roller driving unit.

  Next, the operation of the multifunction machine 1 according to the present invention will be described. FIG. 4 is a flowchart for explaining the operation of the multifunction machine 1 according to the present invention.

  First, in step S1, the paper size specifying unit 111 specifies the paper length of the recording paper according to the document size.

  Next, in step S2, the conveyance speed setting unit 112 determines the conveyance speed V1 of the fixing roller 451 and the conveyance speed V2 of the discharge roller 463 (V1> V2) according to the sheet length of the recording sheet specified by the sheet size specifying unit 111. ) And set. Specifically, the transport speed setting unit 112 determines the transport speed V1 of the fixing roller 451 and the transport speed V2 of the discharge roller 463 corresponding to the paper length of the recording paper specified by the paper size specifying unit 111 from the transport speed storage unit 151. The conveyance speed V1 of the fixing roller 451 read out and the conveyance speed V2 of the discharge roller 463 are set.

  Next, in step S <b> 3, the fixing roller conveyance speed control unit 113 outputs a driving signal for driving the fixing roller 451 to rotate at the conveyance speed V <b> 1 of the fixing roller 451 set by the conveyance speed setting unit 112 to the fixing roller driving unit 1311. To do. The fixing roller driving unit 1311 rotates and drives the fixing roller 451 based on the drive signal output from the fixing roller conveyance speed control unit 113, and discharges the recording paper at the conveyance speed V1 set by the conveyance speed setting unit 112. Transport to roller 463.

  Next, in step S <b> 4, the discharge roller conveyance speed control unit 114 outputs a drive signal for rotating the discharge roller 463 at the conveyance speed V <b> 2 of the discharge roller 463 set by the conveyance speed setting unit 112 to the discharge roller driving unit 1312. To do. The discharge roller driving unit 1312 rotates the discharge roller 463 based on the drive signal output from the discharge roller conveyance speed control unit 114, and records the recording paper at the conveyance speed V 2 set by the conveyance speed setting unit 112. It is conveyed to an external discharge tray 48.

  Next, in step S5, the control unit 100 determines whether or not to discharge all the recording sheets and end printing. If it is determined that printing is to be terminated (YES in step S5), the process is terminated because all recording sheets have been discharged. If it is determined that printing is not to be terminated (NO in step S5), all recording is performed. Since the sheet is not discharged, the process returns to step S1.

  As described above, the multifunction device 1 (image) including at least two rollers between the fixing unit 45 that fixes the toner image on the recording sheet and the discharge port 465 that discharges the recording sheet conveyed from the fixing unit 45 to the outside of the apparatus. Forming apparatus) specifies at least the sheet length of the recording sheet, and sets the conveyance speed of the fixing roller 451 on the fixing unit 45 side and the conveyance speed of the discharge roller 463 on the discharge port 465 side. Here, the conveyance speed of the fixing roller 451 is made faster than the conveyance speed of the discharge roller 463, and the difference in speed between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 depends on the sheet length of the specified recording paper. Is set. Then, the fixing roller 451 is driven by the set conveyance speed of the fixing roller 451, and the discharge roller 463 is driven by the set conveyance speed of the discharge roller 463.

  Accordingly, it is possible to prevent a paper jam by making the conveyance speed of the fixing roller 451 faster than the conveyance speed of the discharge roller 463 and bending the recording paper in the conveyance path 49 between the fixing roller 451 and the discharge roller 463. In addition, by setting the speed difference between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463 according to the sheet length of the recording sheet, it is possible to prevent the discharged recording sheet from having a waveform.

  Further, the longer the paper length in the direction parallel to the recording paper conveyance direction specified by the paper size identification unit 111, the smaller the speed difference between the conveyance speed of the fixing roller 451 and the conveyance speed of the discharge roller 463. Therefore, as the sheet length in the direction parallel to the recording sheet conveyance direction becomes longer, the deflection of the recording sheet can be reduced, and the discharged recording sheet can be prevented from having a waveform. it can.

  Further, the conveyance path 49 between the fixing roller 451 and the discharge roller 463 is curved, and the conveyance speeds of the fixing roller 451 and the discharge roller 463 are set so that the recording surface of the recording paper does not slide on the conveyance path 49. The Accordingly, the conveyance speeds of the fixing roller 451 and the discharge roller 463 are set so that the recording surface of the recording sheet does not slide on the curved conveyance path 49 between the fixing roller 451 and the discharge roller 463. It is possible to prevent the melted toner from adhering to the inner portion of the conveyance path 49, and it is possible to prevent a paper jam.

  In this embodiment, thermal fixing is used in which the toner image is fixed on the recording paper by the fixing roller 451. However, the present invention is not particularly limited to this, and the toner absorbs the light energy at the time of flashing instantaneously. Alternatively, flash fixing may be used in which the toner is melted to fix the toner image on the recording paper.

  Further, the image forming apparatus in the present embodiment is described as a printer apparatus, a facsimile apparatus, and a multifunction machine having these functions. However, the present invention is not particularly limited to this, and a copier, a printer apparatus, and a facsimile apparatus. Etc.

1 is a side view schematically showing an internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the vicinity of a fixing roller and a discharge roller of the multifunction machine shown in FIG. 1. FIG. 2 is a functional block diagram illustrating a schematic configuration of a multifunction machine. 5 is a flowchart for explaining the operation of the multifunction machine according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunction device 100 Control part 111 Paper size specific part 112 Conveyance speed setting part 113 Fixing roller conveyance speed control part 114 Discharge roller conveyance speed control part 120 Scanner part 121 Exposure lamp 122 CCD
DESCRIPTION OF SYMBOLS 130 Recording part 131 Paper conveyance part 132 Image formation part 133 Transfer part 134 Fixing part 140 Image memory 150 HDD
151 Transport Speed Storage Unit 160 Image Processing Unit 190 Operation Panel Unit 191 Display Unit 192 Operation Key Unit 451 Fixing Roller 463, 464 Discharge Roller 1311 Fixing Roller Driving Unit 1312 Discharge Roller Driving Unit

Claims (5)

An image forming apparatus comprising at least two rollers between a transfer device for transferring a toner image onto a recording paper and a discharge port for discharging the recording paper conveyed from the transfer device to the outside of the device,
Paper length specifying means for specifying at least the paper length of the recording paper;
A conveyance speed setting means for setting a conveyance speed of the first roller on the transfer device side and a conveyance speed of the second roller on the discharge port side;
First roller driving means for driving the first roller according to the conveying speed of the first roller set by the conveying speed setting means;
Second roller driving means for driving the second roller according to the conveying speed of the second roller set by the conveying speed setting means,
The transport speed setting means makes the transport speed of the first roller faster than the transport speed of the second roller, and sets the speed difference between the transport speed of the first roller and the transport speed of the second roller as the sheet length. An image forming apparatus, wherein the image forming apparatus is set according to a sheet length of a recording sheet specified by an specifying unit. The first roller is a fixing roller that fixes a toner image onto a recording sheet, and the second roller is a discharge roller that discharges the recording sheet on which the toner image is fixed by the fixing roller to an outside of the apparatus from a discharge port. ,
The conveyance path between the fixing roller and the discharge roller is curved,
The image forming apparatus according to claim 1, wherein the conveyance speed setting unit sets a conveyance speed of the fixing roller and the discharge roller so that a recording surface of the recording sheet does not slide on the conveyance path.   The conveyance speed setting means is configured to increase the speed between the conveyance speed of the fixing roller and the conveyance speed of the discharge roller as the paper length in a direction parallel to the conveyance direction of the recording paper specified by the paper length specification means increases. The image forming apparatus according to claim 1, wherein the difference is set to be small.   The conveyance speed setting means makes the conveyance speed of the fixing roller constant regardless of the paper length of the recording paper specified by the paper length specification means, and specifies the conveyance speed of the discharge roller by the paper length specification means. The image forming apparatus according to claim 1, wherein the image forming apparatus is set according to a sheet length of the recording sheet.   The said 2nd roller drive means makes the conveyance speed of the said discharge roller faster than before passing after the said recording paper passes the nip part of the said fixing roller, The one in any one of Claims 1-4 characterized by the above-mentioned. Image forming apparatus.

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