WO2004092847A1 - 画像形成装置 - Google Patents
画像形成装置 Download PDFInfo
- Publication number
- WO2004092847A1 WO2004092847A1 PCT/JP2004/005184 JP2004005184W WO2004092847A1 WO 2004092847 A1 WO2004092847 A1 WO 2004092847A1 JP 2004005184 W JP2004005184 W JP 2004005184W WO 2004092847 A1 WO2004092847 A1 WO 2004092847A1
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- WO
- WIPO (PCT)
- Prior art keywords
- image
- recording medium
- image forming
- forming apparatus
- paper
- Prior art date
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Classifications
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
- G03G15/23—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 specially adapted for copying both sides of an original or for copying on both sides of a recording or image-receiving material
- G03G15/231—Arrangements for copying on both sides of a recording or image-receiving material
- G03G15/232—Arrangements for copying on both sides of a recording or image-receiving material using a single reusable electrographic recording member
- G03G15/234—Arrangements for copying on both sides of a recording or image-receiving material using a single reusable electrographic recording member by inverting and refeeding the image receiving material with an image on one face to the recording member to transfer a second image on its second face, e.g. by using a duplex tray; Details of duplex trays or inverters
Definitions
- the present invention relates to an image forming apparatus.
- the present invention relates to measures for improving image quality in an image forming apparatus having a double-sided printing function.
- an image forming (printing) operation in an electrophotographic image forming apparatus such as a laser printer
- a host device such as a personal computer (hereinafter simply referred to as a personal computer).
- An electrostatic latent image is formed on the body drum, and toner is attached to the electrostatic latent image to visualize the image data on the photosensitive drum.
- the recording paper conveyed through the paper conveyance path is passed between the photosensitive drum and the transfer roller, and the toner image on the photosensitive drum is transferred onto the surface of the recording paper.
- the recording paper is passed through a fixing roller, and the toner image is fixed on the recording paper by heating and pressing by the fixing roller.
- first method when a plurality of double-sided printing is requested, first of all the front and back print data requested for printing, only the front side printing (single-sided printing) based on the front side printing data is recorded on a plurality of sheets.
- the recording is performed continuously over the sheets, and a plurality of recording sheets for which the front side printing has been completed are stored in the intermediate tray.
- the back side printing using the back side printing data is performed on each recording sheet while taking out the recording sheets stored in the intermediate tray one by one. Both sides A plurality of side-printed recording sheets are sequentially discharged to a discharge tray.
- the second method when double-sided printing is requested, printing is performed one by one using the front and back print data.
- a main transport path and a sub transport path are arranged as transport paths for transporting the recording paper, and a switchback mechanism for the recording paper is required. That is, after the recording paper is conveyed to the main conveyance path and front side printing is performed, the recording paper is conveyed to the sub conveyance path via a switchback mechanism, whereby the recording paper is turned over and the main conveyance is performed again. The paper is transported to a road and printed on the back side of the recording paper.
- the first method requires an intermediate tray large enough to hold a plurality of recording sheets in order to cope with a case where a plurality of double-sided printing is requested.
- a large intermediate tray is required, which makes it difficult to design a compact image forming apparatus.
- the back side printing is started after all the front side printing on the plurality of recording sheets is completed.
- the printing state of the first printed matter can be confirmed.
- a toner image is transferred to one side of one recording sheet, and then a toner image is fixed on the recording sheet.
- the fixing process is performed, and then the backside printing is started.
- heat fixing is performed in the fixing process, so that the recording paper subjected to the fixing process loses moisture from the surface due to heat of fixing.
- the surface resistance value of the recording paper when performing the back side printing is higher than the surface resistance value of the recording paper before performing the front side printing.
- the sheet resistance changes as shown in Fig.5. That is, in the transfer step in the surface printing of the first sheet (1), the surface resistivity of the paper is in the 1 X 1 0 8 ⁇ ⁇ cm . In the fixing step (1), which is performed immediately after that, moisture on the paper surface is lost due to the fixing heat, and the surface resistance value of the paper becomes 0.5 X 101. It rises to about ⁇ ⁇ cm.
- constant current control for controlling the transfer operation with a constant current is performed.
- constant current control is performed on the same paper having different surface resistance values.
- the surface resistance value of the paper (usually about 1 X 106 to ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ m) depends on the type and size of the paper, the amount of water in the paper, the surrounding environment, etc.
- the transfer voltage for back side printing is about twice the transfer voltage for front side printing due to the large fluctuation of the surface resistance of the paper during the fixing process as described above.
- the applied voltage may be close.
- Such a difference in the transfer voltage has a great effect on the transfer characteristics between the front side printing and the back side printing, and causes a problem that the image quality of the front and back sides does not match.
- two-sided printing is performed on a plurality of sheets, a printing failure due to “force filing” described later occurs during the front side printing of the second and subsequent sheets, which is a problem.
- the state of occurrence of the “capri” will be described.
- the photosensitive member b after the transfer process on the back side of the first sheet is indicated by a broken line in FIG. 6 (c).
- the surface potential at both ends outside the paper placement area decreases.
- the toner is unintentionally adhered to the photoconductor b due to the small potential difference, even though it is in the non-image area where toner adhesion is prevented by the potential difference between the toner and the photoconductor b.
- a phenomenon occurs (this phenomenon is called Capri).
- the state in which fogging has occurred on the photoconductor b continues until the charging process is performed again, that is, at least until the photoconductor makes one revolution. Will be.
- the fog image is transferred to the tip position corresponding to within one round of the photoconductor, but this is due to sheet conveyance variations (positional deviation in the sheet width direction). This occurs when the first sheet is displaced in the axial direction of the photoconductor with respect to the sheet passage position during the transfer of the back side of the first sheet.
- the resistance value of the printing paper changes due to a change in the environment of the apparatus due to the constant voltage control, and the appropriate voltage changes. This results in a change in the voltage to the photoreceptor, causing damage to the photoreceptor, and in this case, the life characteristics of the photoreceptor are also reduced.
- the present invention has been made in view of such a point, and an object of the present invention is to reduce the life characteristics of a photoconductor with respect to an image forming apparatus having a double-sided printing function. In addition, it is also possible to reduce printing defects due to “capri”. Disclosure of the invention
- the present invention changes the paper passing position at the time of front side printing and the paper passing position at the time of back side printing by a shifter function, without causing a reduction in life characteristics of the photoconductor. In this way, it is possible to reduce printing defects due to capri.
- the recording medium is transported again toward the image carrier, and It is assumed that the image forming apparatus has a double-sided printing function for recording an image formed on the image carrier on a second surface of the recording medium different from the first surface.
- the transport position of the recording medium when recording the image on the recording medium is determined by the case where the image is recorded on the first surface and the case where the image is recorded on the second surface. Switching means for switching differently in a direction orthogonal to the recording medium transport direction is provided.
- the surface potential of the image carrier at a position not in contact with the recording medium decreases due to the change in the surface resistance of the recording medium (for example, recording paper) passing through the image carrier. .
- Such a decrease in surface potential causes capri on the image carrier, and conventionally, if the transport position is slightly deviated when performing recording on the second and subsequent recording media. Printing failure due to capri had occurred.
- the transport position when performing double-sided printing on one recording medium, by changing the transport position as described above, the area where the surface potential of the image carrier is low is narrowed, and the area where capri is generated is reduced. Coming up.
- the transport position of the recording medium is approximately 10 to 30 O when recording image information on the first surface (front surface) and when recording image information on the second surface (back surface). It may be set so as to differ by about mm.
- the transport position of the recording medium is set to a reference position for passing the recording medium on the image carrier. are doing.
- the transport position of the recording medium is set such that the recording medium is transported by single-sided printing or the like.
- the transport position (the reference position for passing the image carrier). Therefore, even when the image forming apparatus performs double-sided printing and changes the transport position of the recording medium, the life (life) characteristics of the image carrier can be kept substantially constant. That is, in the image forming apparatus, not only double-sided printing but also single-sided printing is performed. Therefore, in order to exchange the image bearing member at a suitable timing in response to the deterioration of the image bearing member, the single-sided printing is performed even in the double-sided printing.
- the recording medium is transported in the same way as printing.
- the recording medium sets the paper passing reference position of the recording medium on the image carrier when recording on at least one surface.
- the state of deterioration of the image carrier can be kept almost constant. This makes it possible for a user or a maker to grasp the state of deterioration of the image carrier, so that it is possible to appropriately manage the replacement of the image carrier.
- a paper discharge unit for discharging a recording medium on which an image is recorded is provided, and the switching unit is provided in the paper discharge unit. Further, the switching means has an offset function for making the discharge position of the recording medium to be discharged different. Then, the transport position of the recording medium when an image is recorded on the recording medium is switched by an offset function of the switching means.
- the offset function shift The transfer position of the recording medium is switched by the data transfer function, so that the apparatus is not enlarged.
- an optical cut for writing image information on the image carrier is provided, and the optical unit writes the first information on the recording medium when writing the image information on the image carrier.
- An image information writing point for recording an image on a surface and an image information writing point for recording an image on the second surface of the recording medium are individually set. According to the above configuration, at the time of double-sided printing in the image forming apparatus, even if the transport position of the recording medium is changed, the image information writing point is appropriately set according to the transport position of the recording medium. Therefore, an image can be recorded at a predetermined position on the recording medium. Thus, even when double-sided printing is performed, the image recording position does not differ between the first surface and the second surface.
- the optical unit is provided with a write timing detection sensor for setting a timing for writing image information on the image carrier, and the write point is changed by changing the write timing from the write timing detection sensor. It is set.
- the timing of recording image information on the first surface or the second surface is controlled by the write timing detection sensor.
- the writing point is appropriately set according to the transport position of the recording medium.
- image information can be recorded at a predetermined position on the recording medium even when the transport position of the recording medium is changed during duplex printing in the image forming apparatus.
- the transport position of the recording medium is determined by a plurality of transport rollers disposed in a transport path of the recording medium, the image carrier, the fixing mechanism, the transfer mechanism, and a developing mechanism disposed around the image carrier. It is an operable area for various charging mechanisms and cleaning mechanisms. According to the above configuration, the transport position of the recording medium is determined by the transport roller, the image carrier, the fixing mechanism, the transfer mechanism, and the developing mechanism arranged around the image carrier, and the various types of charging. Mechanism, set in an area where the above-mentioned cleaning mechanism can operate. Have been.
- the transport position of the recording medium is determined by the following relational expression when recording an image on the first surface and when recording an image on the second surface.
- the image information formed on the image carrier can be preferably transferred onto the recording medium. It can. That is, by changing the transport position of the recording medium so as to satisfy the above relational expression, the image information formed on the image carrier can be recorded so as not to protrude from the recording medium.
- FIG. 1 is a diagram schematically illustrating an internal configuration of a multifunction peripheral according to the embodiment.
- FIG. 2 is a cross-sectional view of the shifter mechanism.
- FIG. 3 is a perspective view showing a schematic configuration of the laser scanning unit.
- FIG. 4 is a diagram for explaining changes in the current of the transfer roller and the surface potential of the photosensitive drum in the transfer process according to the embodiment.
- FIG. 5 is a diagram for explaining a change in the surface resistance value of a sheet.
- FIG. 6 is a diagram for explaining changes in the current of the transfer roller and the surface potential of the photosensitive drum in the transfer step of the conventional example.
- the present invention is applied to a multifunction peripheral having a print function and a facsimile function.
- the recording medium an arbitrary sheet such as an image forming sheet or a recording sheet is used.However, the present invention is not limited to this.
- a recording medium of another form such as an OHP sheet may be used. You may.
- FIG. 1 schematically shows an internal configuration of a multifunction peripheral 1 as an image forming apparatus according to the present embodiment.
- the multifunction peripheral 1 includes a scanner unit 2, a printing unit 3 as an image forming unit, and an automatic document feeding unit 4.
- a scanner unit 2 As shown in FIG. 1, the multifunction peripheral 1 includes a scanner unit 2, a printing unit 3 as an image forming unit, and an automatic document feeding unit 4.
- each unit will be described.
- the scanner unit 2 reads the image of the original placed on the original platen 4 1 made of transparent glass or the like and the image of the original fed one by one by the automatic original feeding unit 4 to create image data.
- 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: Charge Coupled Device) 26.
- CCD Charge Coupled Device
- the exposure light source 21 irradiates light on a document placed on the document table 4 1 of the automatic document feeder 4 and a document conveyed through the automatic document feeder 4.
- Each of the reflecting mirrors 22, 23, and 24 reflects the reflected light from the original once to the left in the figure, then downward, as shown by the dashed line A in FIG. The light is reflected rightward in the figure so as to be directed toward the imaging lens 25.
- the exposure light source 21 and the reflecting mirrors 2 2, 2 3 , 24 scan in the horizontal direction along the document table 41 to read the image of the entire document.
- the exposure light source 21 and the reflecting mirror 22 are fixed at the positions shown in FIG.
- the original reading section 42 is a platen glass described later. 4 2 a, an original presser plate 4 2 b, an exposure light source 21, reflecting mirrors 22, 23, 24, an imaging lens 25, and a photoelectric conversion element 26.
- the light reflected by each of the reflecting mirrors 22, 23 and 24 and passing through the imaging lens 25 is guided to a photoelectric conversion element 26, where the reflected light is converted into an electric signal (original image). Image data).
- the print 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 as an optical unit according to the present invention 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 the original image data converted by the photoelectric conversion element 26.
- the photoreceptor drum 31b rotates in the direction indicated by the arrow in FIG. 1, and is irradiated with laser light from the laser scanning unit 31a so that an electrostatic latent image is formed on its surface. ing.
- a developing device (developing mechanism) 31c, a transfer roller 31d constituting a transfer mechanism, and a cleaning device ( (Cleaning mechanism) 31 e, a static eliminator (not shown), and a charging butt 31 f are arranged in this order in the circumferential direction.
- the developing device 31c develops the electrostatic latent image formed on the surface of the photosensitive drum 31b into a visible image with toner.
- the transfer roller 31d transfers the toner image formed on the surface of the photosensitive drum 31b to image forming paper as a recording medium.
- the cleaning device 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 unit 31f charges the surface of the photosensitive drum 31b before the electrostatic latent image is formed to a predetermined potential.
- the charging unit 31 f The surface of the photosensitive drum 31b is charged to a predetermined potential, and the laser scanning unit 31a irradiates the surface of the photosensitive drum 31b with a laser beam based on the document surface image data. Thereafter, the developing device 31c develops a visible image with toner on the surface of the photosensitive drum 31b, and the toner image is transferred to the image forming paper by the transfer roller 31d. Further, thereafter, the toner remaining on the surface of the photosensitive drum 31b is removed by the cleaning device 31e, and the residual charge on the surface of the photosensitive drum 31b is removed by the neutralizer. This completes one cycle of the image forming operation (printing operation) on the image forming paper. By repeating this cycle, it is possible to continuously form an image on a plurality of sheets of image forming paper.
- the paper transport system 32 transports the image forming papers stored in a paper cassette 33 as a paper storage unit one by one to cause the image forming system 31 to perform image formation, and to perform image formation.
- the discharged image forming paper is discharged to a paper discharge tray 35 as a paper discharge unit.
- the paper transport system 32 includes a main transport path 36 and a reverse transport path 37.
- the main transport path 36 faces the discharge side of the paper cassette 33, and the other end faces the paper discharge tray 35.
- One end of the reversing conveyance path 37 is connected to the main conveyance path 36 on the upstream side (lower side in the drawing) of the arrangement of the transfer roller 31d, and the other end is connected to the transfer roller 31. It is connected to the main transport path 36 downstream (upper side in the figure) from the location of d.
- a pickup roller 36a having a semicircular cross section is disposed at an upstream end of the main transport path 36 (a portion facing the discharge side of the paper cassette 33). By the rotation of the pickup roller 36a, the image forming sheets stored in the sheet cassette 33 can be intermittently fed to the main transport path 36 one by one.
- registration rollers 36 d, 36 d On the upstream side of the transfer roller 31 d in the main transport path 36, there are provided registration rollers 36 d, 36 d.
- the registration rollers 36 d and 36 d transport the image forming paper while aligning the toner image on the surface of the photosensitive drum 31 b with the image forming paper.
- Transfer port in main transport path 36 Downstream from the disposition position, a pair of fixing rollers 36 e and 36 e for fixing the toner image transferred to the image forming paper by heating are disposed e.
- a discharge unit 7A as a discharge unit for discharging the image forming paper to the discharge tray 35 is provided at the downstream end of the main transport path 36. Inside A is housed a shifter mechanism 7 (see FIG. 2) as switching means described later.
- a branch claw 38 is provided at a connection position of the upstream end of the reverse conveyance path 37 with respect to the main conveyance path 36.
- the bifurcated claw 38 is moved horizontally between a first position indicated by a solid line in FIG. 1 and a second position in which the first position is rotated counterclockwise in the figure to open the reverse conveyance path 37. It is rotatable around.
- the branching pawl 38 is at the first position, the image forming paper is conveyed toward the discharge tray 35, and when at the second position, the image forming paper can be supplied to the reverse conveyance path 37. .
- a transport roller 37a is provided in the reverse transport path 37, and when the image forming paper is supplied to the reverse transport path 37 (the image forming paper is supplied to the reverse transport path 37 by so-called switchback transport).
- the image forming sheet is conveyed by the conveying roller 37a, and the image forming sheet is inverted upstream of the registration roller 36d, and the main conveying path is moved toward the re-transfer roller 31d. 36 is to be transported. That is, the image can be formed on the back surface of the image forming paper.
- the automatic document feeder 4 is configured as a so-called automatic double-sided document feeder.
- the automatic document feeder 4 can be used as a sheet movable type, and includes a document tray 43 as an original placing portion, an intermediate tray 44, a document output tray 45 as a document output portion, and each tray.
- An original transport system 46 for transporting the original between 43, 44, and 45 is provided.
- the document transport system 46 includes a main transport path 47 for transporting the document placed on the document tray 43 through the document reading unit 42 to the intermediate tray 44 or the document discharge tray 45. And a sub-transport path 48 for supplying the original on the intermediate tray 44 to the main transport path 47. ing.
- An original pick-up roller 47a and a separating roller 47b are disposed at an upstream end of the main transport path 47 (a portion facing the discharge side of the original tray 43).
- a separating plate 47c is provided below the separating roller 47b, and one of the documents on the document tray 43 is rotated by the rotating of the document pickup roller 47a.
- the paper is fed to the main transport path 47 after passing between 7b and the separating plate 47c.
- the PS rollers 47 e and 47 e are disposed downstream of the junction (the portion B in the drawing) 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 to supply the document to the document reading unit 42. In other words, the PS rollers 47e and 47e temporarily stop transporting the original while the original is being supplied, and adjust the timing to supply the original to the original reading unit 42. .
- the document reading section 42 includes a platen glass 42 a and a document holding plate 42 b, and the documents supplied from the PS rollers 47 e and 47 e receive the platen glass 42 a and the document holding plate 4 e. 2b, the light from the exposure light source 21 passes through the platen glass 42a and irradiates 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 holding plate 42b. As a result, the document holding plate 4 2b is in contact with the platen glass 4 2a with a predetermined pressing force, so that the document rises from the platen glass 4 2a when passing through the document reading section 42. Blocking.
- a transport roller 47f and a document / paper roller 47g are provided on the downstream side of the platen glass 42a.
- 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 transport roller 47f and the document discharge roller 47g.
- An intermediate tray plate 4 4a is located between the original discharge roller 47g and the intermediate tray 44. It is arranged.
- the intermediate tray rocking plate 44a has an end on the side of the intermediate tray 44 as a pivot center, and has a position 1 indicated by a solid line in the figure and a position 2 jumped upward from the position 1. It can swing between.
- the intermediate tray rocking plate 44a is in the position 2
- the document discharged from the document discharge roller 47g is collected to the document discharge tray 45.
- the intermediate tray rocking plate 44 a is in the position 1
- the document discharged from the document discharge roller 47 g is discharged to the intermediate tray 44.
- the edge of the document is held between the document discharge rollers 47g and 47g.
- the document discharge port 47g is set.
- the document is supplied to the sub-conveying path 48 by the reverse rotation of, and is sent to the reproduction main conveying path 47 via the sub-conveying path 48.
- the reverse rotation of the original discharge roller 47 g is performed by adjusting the sending of the original to the main transport path 47 and the image reading timing. As a result, the image on the back side of the document is read by the document reading unit 42.
- print data image data or text data transmitted from a host device such as a personal computer is used.
- the received print data print data
- a buffer memory
- the storage of the print data in the buffer and the reading of the print data from the buffer are sequentially performed, and based on the read print data, the image forming operation of the printing unit 3 described above forms the image on the image forming paper. Done.
- the scanned image data of the document read by the scanner unit 2 is temporarily stored in a buffer.
- the scan image data is stored in the buffer, and the scanned image data is sequentially transmitted to the host device, and the image is displayed on the display of the host device.
- the MFP 1 functions as a copier, an image is formed on image forming paper by the image forming operation of the printing unit 3 based on the document image data read by the scanner function. .
- the above-mentioned shifter mechanism (offset mechanism) 7 for discharging the image forming paper while shifting the paper discharge position is provided, and this is effectively used at the time of double-sided printing. .
- the shifter mechanism 7 will be described.
- the shifter mechanism 7 is provided inside the discharge unit 7A disposed at the downstream end of the main transport path 36 of the printing unit 3.
- the original function of this shifter mechanism 7 is to shift the discharge position by one copy so that the printed matter can be distinguished one copy at a time when printing multiple copies (in the direction perpendicular to the paper discharge direction). Shift to
- FIG. 2 is a cross-sectional view of the shifter mechanism 7 (a cross-sectional view taken along a plane perpendicular to the sheet discharging direction).
- the shifter mechanism 7 rotates the shaft 72 by a driving gear 71 that receives a driving force from a driving source (not shown) of the multifunction peripheral 1.
- the shaft 72 is rotatably and integrally connected to a connecting gear 73 via a connecting member 72a.
- offset rollers 74 a and 74 rotating by receiving the driving force from the connecting gear 73 are provided inside the box-shaped offset member 74 arranged below the connecting gear 73 in the drawing. a is provided.
- the drive gear 71 is driven by the driving force from the apparatus driving source, so that the shaft 72 is driven, and the offset roller 74 a provided in the offset member 74 is driven to rotate, and Is transported.
- the offset roller 74a is capable of reversible rotation in accordance with the rotation direction of the horse gear 71, so that the paper is discharged or the paper is reversely fed toward the reverse conveyance path 37. Rotation is possible.
- the shifter mechanism 7 can move the position of the offset member 74 in the horizontal direction by the offset driving source 75 and the offset gear group 76.
- the connection member 72 a is provided for the connection gear slide so that the connection gear 73 connected to the shaft 72 can slide within a predetermined range ⁇ ⁇ along the shaft 72. It has a slot 72b.
- a boss 72c protruding from the shaft 72 is disposed inside the connecting gear slide slot 72b. Therefore, when the connecting member 72 a is shifted by the offset gear group 76 so that the relative position of the boss 72 c in the elongated hole 72 b for the connecting gear slide moves, the connecting gear 73 also shifts. As a result, the position of the offset member 74 shifts. With the shift of the offset ⁇ ⁇ material 74, the positions of the offset rollers 74a and 74a are also shifted.
- the position of the offset opening rollers 74a, 74a is shifted together with the offset member 74, thereby shifting the recording paper discharge position (perpendicular to the paper transport direction). In the direction in which you do).
- the transfer position of the recording paper in the printing on the front surface and the back surface is shifted in the duplex printing.
- the multifunction peripheral (image forming apparatus) 1 having the above configuration functions as a copy machine (copier mode) will be described.
- the original to be printed is placed on the platen 4 1, and the user places the recording paper in the paper cassette 3 3, and the condition input keys on the operation panel (not shown) arranged on the exterior front of the MFP 1 After inputting (number of prints, print magnification, etc.), press the start key to start copying.
- the main drive motor starts at almost the same time as the start key is pressed, and each drive gear rotates. Thereafter, the pickup roller 36a rotates and the recording paper is fed, and the recording paper reaches the registration roller 36d.
- the recording paper is temporarily stopped to synchronize with the leading edge of the image formed on the photosensitive drum 31b, and the leading edge of the recording paper is uniformly pressed against the register roller 36d. Thus, the position of the leading end of the recording paper is corrected.
- the image information while the original is being read by the scanner section 2 is such that the exposure light source 21 is turned on, and the copy lamp unit composed of the exposure light source 21 and each of the reflecting mirrors 22, 23, 24 is attached to the original table. 4 Exposure is started by moving in the direction parallel to 1. Irradiation light including image information illuminating the original by the exposure light source 21 is input to the CCD 26 through the first mirror 22, the second mirror 23, the third mirror 24, and the optical lens 25. Is read.
- the image information read in this way is converted by a CCD circuit of a control unit (not shown) into image information of incident light into an electric signal, and the image information signal is subjected to image processing under set conditions. Transmitted as print data to Laser Scanning Unit (LSU) 3 la.
- LSU Laser Scanning Unit
- the photosensitive drum (image carrier) 31b is charged to a predetermined charging potential by the charging unit 31f.
- the laser beam from the laser scanning unit 31a is radiated to the photosensitive drum 31b through the polygon mirror 81 and various lenses as shown in Fig. 3, and is statically placed on the photosensitive drum 31b.
- An electrostatic latent image is formed.
- the toner on the MG roller in the developing tank of the developing device 31c is attracted to the surface of the photoconductor drum 31b, and the electrostatic latent image is formed on the photoconductor drum 31b by the toner.
- the image is visualized according to the potential gap, and a toner image is obtained.
- the recording paper to be imaged is moved in the direction of the photoconductor drum 3 1b (main transport path 3 6), and the toner on the photosensitive drum 31b is transferred to the recording paper by the transfer roller 31d.
- the toner remaining on the photosensitive drum 31b is removed and collected by the cleaning blade of the cleaning device 31e.
- the recording paper on which one transfer has been completed passes through the upper heat roller and the lower heat roller (fixing roller 36e, 36e) of the fixing device (fixing mechanism), and heat and pressure are reduced.
- the unfixed toner on the recording paper is melted and fixed on the paper, and discharged through the discharge unit 7A. Dispensed to paper tray 35.
- the recording paper that has passed through the fixing rollers 36 e and 36 e is reversed by the switchback mechanism so that the front end and the rear end of the recording paper are reversed. It is transported to the reverse transport path 37. Then, as described above, the resist roller 36d is conveyed in the direction of the photoconductor drum 31b (main conveyance path 36) at a timing synchronized with the photoconductor drum 31b. Then, printing is performed on the back side of the recording paper, and the recording paper is discharged to the paper discharge tray 35.
- the transfer position of the recording paper is shifted by using the shifter mechanism 7 provided in the discharge unit 7A during the switchback. That is, the recording paper on which the front side (the first side) is printed is first shifted by the shifter mechanism 7, and then the recording paper is conveyed to the reverse conveyance path 37 by performing switchback. Printing on the back side (second side). Therefore, when performing double-sided printing, the transport position of the recording paper in the photosensitive drum 31b, the transfer roller 31d, the fixing device, and the like is different between the front side printing and the back side printing.
- the transport position of the recording paper (paper transport position) is set so that the printing time on the front side of the recording paper is the reference position preset in the MFP 1.
- the paper transport position at the time of printing on the back side of the recording paper is the paper transport reference position set in the multifunction device 1 (in the present embodiment, the paper transport reference position on the photosensitive drum 31b).
- the shifter mechanism 7 is driven so as to deviate from the above.
- the reason for this is that the MFP 1 performs not only double-sided printing but also single-sided printing. Therefore, in order to keep the life (life) characteristics of the photosensitive drum 31b almost constant, the paper transport position for printing on either the front surface or the back surface is set to the paper transport reference position set in the multifunction device 1. It is preferable to set. This makes it easier to manage replacement of the photosensitive drum 31b due to deterioration or the like.
- the paper transport position of the recording paper in the multifunction machine 1 is determined by the registration rollers 36 d, the photosensitive drums 31 b, and the fixing rollers 3 arranged along the paper transport path on which the recording paper is transported. 6 e, transfer roller 31 d, developing device 31 c, charging unit 31 f disposed around photosensitive drum 31 b, cleaning unit 31 e, etc. Is preferred. Thereby, even when the conveyance position of the recording paper is changed in the duplex printing, the conveyance of the recording paper and the printing on the recording paper can be suitably performed. Further, it is preferable that the paper transport position (the change distance of the paper transport position) to be changed between the printing on the front surface and the printing on the back surface is represented by the following relational expression.
- the maximum recording paper used for printing is the recording paper that can be printed by the MFP 1. Among them, it refers to the recording paper with the largest size.
- the recording paper can transfer the toner image formed on the photosensitive drum 31 b to the recording paper at the time of printing.
- the timing of writing from the optical unit such as the laser scanning unit 31a to the photosensitive drum 31b is changed by changing the paper transport position between the front side printing and the backside printing. It needs to be changed.
- This timing is controlled by a write timing detection sensor provided in the optical unit. That is, as shown in FIG. 3, the writing timing detection sensor 80 writes a part of the light that has entered the polygon mirror 81 from the laser light source 82 to the photosensitive drum 31b. The light is emitted to a position different from the writing area where the light enters, and is reflected by the reflection mirror 83. When this reflected light is received by the sensor 80, writing on the surface of the photosensitive drum 31b is started after a predetermined time has elapsed.
- the writing points for the front side printing and the writing points for the back side printing are set as the writing points on the surface of the photosensitive drum 31b. Need to have As described above, writing on the photosensitive drum 31b starts after a predetermined time has elapsed after the reflected light is received by the sensor 80. , write Only the timing can be different. That is, the change of the writing point for the front side printing and the back side printing can be changed by the change of the writing timing.
- the multifunction peripheral 1 of the present embodiment has the switchback mechanism, and applies the transfer voltage of the transfer process by the constant current control.
- the change in the current of the transfer roller 31 d and the change in the surface potential of the photosensitive drum 31 b in the transfer process performed by the multifunction machine 1 will be described with reference to FIG.
- a recording sheet is sandwiched between the transfer roller 31d and the photosensitive drum 31b (hereinafter referred to as a photosensitive body), and the recording paper is placed on the photosensitive body 31b. Transfer the toner image to recording paper.
- the recording sheet is transported so as to pass through the maximum sheet passing position (A) shown in FIG.
- the transfer current flowing toward the photoconductor in the transfer process on the surface of the first sheet is almost constant as shown by the solid line in FIG. 4 (b). Therefore, the surface potential of the photoconductor 31b after the transfer process of the front side of the first sheet (immediately before printing on the back side of the first sheet) is represented by a solid line in FIG. 4 (c). As shown in the figure, the entire photoconductor 31b is almost constant.
- the recording paper printed on the front surface is switched back, and printing is performed on the back surface of the recording paper (the back surface of the first recording paper).
- the transfer process performed during the printing so as to pass through the maximum paper sheet passing position (B) shown in FIG. 4 (a), it moves the conveyance position of the recording paper.
- the movement of the transfer position is performed by using a shifter mechanism 7 provided in the discharge unit 7A of the multifunction device 1.
- the surface potential of the photoconductor 31b after the transfer process on the back side of the first sheet (immediately before the transfer to the front side of the second sheet) is obtained by the broken line in FIG. 4 (c).
- the potential decreases in the end region of the photoconductor 31b (yl, y2). This decrease in the potential value is greater in the first end region (voltage y 1) than in the second end region (voltage y 2).
- a decrease in the potential value in the first end region results in damage to the photoconductor, causing fog on the photoconductor 31b.
- fog on the photoreceptor 31b generated in the second end region where the decrease in the potential value is relatively small is small, and printing failure due to capri hardly causes a problem, so that the photoreceptor is not damaged.
- the first recording sheet on which double-sided printing has been performed is discharged, and printing is performed on the surface of the second recording sheet.
- the recording paper is conveyed so as to pass through the maximum paper passing position (A) shown in Fig. 4 (a), as in the transfer process on the front surface of the first recording paper. I do.
- the capri on the photoreceptor 31b generated in the second end area is small, a part of the recording paper is in contact with the second end area of the photoreceptor 31b and the transfer roller 31d. Even if they come into contact, adhesion of the toner to the recording paper by the above capri has little problem.
- the recording paper is passed between the photosensitive member 31b and the transfer roller 31d, so that the transfer of the surface of the second recording paper is performed.
- the photoreceptor 31 b and the transfer roller 31 d after the process are removed.
- the surface potential of the photoreceptor 31b is substantially constant over the entire photoreceptor as shown by the solid line in FIG. 4 (c). Therefore, in the transfer process of the back surface of the second recording paper, printing failure due to capri does not occur. Further, when printing on the third and subsequent recording sheets, by changing the transport position of the recording sheet as described above, printing defects due to capri can be reduced.
- the present invention is applied to a multifunction peripheral having a scanner function, a printer function, and a copy function.
- the present invention is not limited to this, and can also be applied to an image forming machine having at least one of the functions and other image forming machines.
- the present invention by changing the sheet passing position for front side printing and the sheet passing position for back side printing with an image forming apparatus having a double-sided printing function by the switching means (shifter function),
- the area where the surface potential of the image carrier is high is narrowed, and the area where capri is generated is small. For this reason, even when a slight shift occurs in the transport position of the recording medium during recording on the second and subsequent recording media, the recording medium contacts the area where the capri has occurred on the image carrier. It is possible to prevent the occurrence of printing defects due to capri on the recording medium, and to improve the image quality.
- the present invention is not limited to other spirits and main features. It can be implemented in various forms.
- the present invention is applicable to an image forming apparatus capable of forming an image without being limited to a copying machine, a printer, a facsimile machine, and the like.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Control Or Security For Electrophotography (AREA)
- Counters In Electrophotography And Two-Sided Copying (AREA)
- Delivering By Means Of Belts And Rollers (AREA)
- Paper Feeding For Electrophotography (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US10/550,543 US7418234B2 (en) | 2003-04-11 | 2004-04-09 | Image forming apparatus |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2003-107940 | 2003-04-11 | ||
JP2003107940A JP4245960B2 (ja) | 2003-04-11 | 2003-04-11 | 画像形成装置 |
Publications (1)
Publication Number | Publication Date |
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WO2004092847A1 true WO2004092847A1 (ja) | 2004-10-28 |
Family
ID=33295873
Family Applications (1)
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PCT/JP2004/005184 WO2004092847A1 (ja) | 2003-04-11 | 2004-04-09 | 画像形成装置 |
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US (1) | US7418234B2 (ja) |
JP (1) | JP4245960B2 (ja) |
CN (1) | CN100447677C (ja) |
WO (1) | WO2004092847A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN102741171A (zh) * | 2010-01-06 | 2012-10-17 | 哈利伯顿能源服务公司 | 紫外光处理方法和系统 |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005295113A (ja) * | 2004-03-31 | 2005-10-20 | Canon Inc | 画像読取ユニット及び画像読取装置 |
JP4863840B2 (ja) * | 2006-10-27 | 2012-01-25 | 株式会社リコー | 画素形成装置、光走査装置、光走査方法、画像形成装置、カラー画像形成装置 |
JP5187392B2 (ja) * | 2008-08-18 | 2013-04-24 | コニカミノルタビジネステクノロジーズ株式会社 | 画像形成装置 |
US8181955B2 (en) * | 2010-02-03 | 2012-05-22 | Goss International Americas, Inc. | Feeder device and method for moving printed products by planar motion |
CN103471636B (zh) * | 2012-06-06 | 2016-01-27 | 维嘉数控科技(苏州)有限公司 | 一种光学检测设备的玻璃压板装置 |
JP6025453B2 (ja) * | 2012-08-27 | 2016-11-16 | キヤノン株式会社 | 画像形成装置 |
JP6587474B2 (ja) | 2015-09-15 | 2019-10-09 | キヤノン株式会社 | 画像形成装置 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0218242A (ja) * | 1988-07-04 | 1990-01-22 | Canon Inc | 画像形成装置 |
JPH04208949A (ja) * | 1990-11-30 | 1992-07-30 | Ricoh Co Ltd | 画像形成装置の排紙装置 |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5162857A (en) * | 1987-07-14 | 1992-11-10 | Canon Kabushiki Kaisha | Sheet conveyer having a sheet aligner |
JP2002023576A (ja) | 2000-07-12 | 2002-01-23 | Sharp Corp | 画像形成装置 |
US6424365B1 (en) * | 2001-03-20 | 2002-07-23 | Toshiba Tec Kabushiki Kaisha | Image forming apparatus and method of controlling apparatus |
JP4579444B2 (ja) | 2001-05-08 | 2010-11-10 | キヤノン株式会社 | 画像形成装置 |
-
2003
- 2003-04-11 JP JP2003107940A patent/JP4245960B2/ja not_active Expired - Fee Related
-
2004
- 2004-04-09 US US10/550,543 patent/US7418234B2/en active Active
- 2004-04-09 CN CNB200480009694XA patent/CN100447677C/zh not_active Expired - Fee Related
- 2004-04-09 WO PCT/JP2004/005184 patent/WO2004092847A1/ja active Application Filing
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0218242A (ja) * | 1988-07-04 | 1990-01-22 | Canon Inc | 画像形成装置 |
JPH04208949A (ja) * | 1990-11-30 | 1992-07-30 | Ricoh Co Ltd | 画像形成装置の排紙装置 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102741171A (zh) * | 2010-01-06 | 2012-10-17 | 哈利伯顿能源服务公司 | 紫外光处理方法和系统 |
Also Published As
Publication number | Publication date |
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US20060216090A1 (en) | 2006-09-28 |
JP4245960B2 (ja) | 2009-04-02 |
US7418234B2 (en) | 2008-08-26 |
CN1771468A (zh) | 2006-05-10 |
CN100447677C (zh) | 2008-12-31 |
JP2004317577A (ja) | 2004-11-11 |
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