JP2005206338A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of forming at high speed a high quality image always placed at a given position relative to an end of a paper. <P>SOLUTION: An oscillation volume of an oscillation means for oscillating a transfer means in a direction orthogonal to a transfer direction of a recording material to be transferred by the transfer means is controlled on the basis of an amount of deviation of the recording material detected by a recording material deviation detecting means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus. More specifically, the present invention relates to an image forming apparatus that transfers an image formed by an image forming unit to a sheet conveyed by a conveying unit by a transfer unit.

  In recent years, a post-processing device that automatically performs sheet folding processing, binding processing, cutting processing, punching processing, and the like on a sheet on which an image is formed by an image forming apparatus such as an electrophotographic copying machine, a printer, or a printing machine. An image forming apparatus is provided. As a result, it is possible to save the labor of bookbinding and punching the output paper as before, and the office work is very efficient.

  Such an image forming apparatus requires high-precision paper conveyance. For example, the edge of the paper does not maintain a positional relationship that is parallel or perpendicular to the paper conveyance direction or the main scanning direction of the image forming unit. When the paper is conveyed (hereinafter referred to as “paper bending”) or the paper is not bent, the side edge position in the paper conveyance direction and the side edge position of the image formed by the image forming unit are constant. When the paper is transported without maintaining the positional relationship (hereinafter referred to as “paper misalignment”), the paper folding position, binding position, cutting position, or perforated holes are also offset, and as a result, There is a problem that the paper is offset and bound and filed.

  In order to solve such a problem, a paper misalignment sensor that detects the misalignment of the paper is provided on the paper conveyance path between the registration roller that corrects the bending of the paper conveyed through the refeed unit and the transfer unit. Provided, the position of the image data on the memory is corrected based on the information on the deviation of the paper detected by the sensor after the paper is corrected by the registration roller, and the image formed by the image forming means on the edge of the paper It is known that the formation position is always kept constant (for example, Patent Document 1).

On the other hand, there is an increasing demand for high-speed and high-quality color images. To meet this demand, yellow (Y), magenta (M), cyan (C) and black are provided on a plurality of photosensitive drums (image carriers). (K) toner images are formed, and these toner images are sequentially transferred onto an intermediate transfer belt (intermediate transfer member) to superimpose the toner images, and then the superimposed toner images (superposed color toner images). In general, a tandem-type image forming apparatus that collectively transfers a toner image onto a recording sheet is used as a useful device for forming a color image (for example, Patent Document 2).
JP 2002-248804 A JP 2001-222129 A

  FIG. 8 is a schematic sectional view of a conventional tandem color image forming apparatus.

  In the tandem type color image forming apparatus, images of respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the rotating intermediate transfer member 170 by the primary transfer rollers 15Y, 15M, 15C, and 15K. As a result, a combined color toner image is formed, and the color toner image is collectively transferred to the sheet S as the recording material by the secondary transfer roller 301 at the point P3. A color electrophotographic image is obtained by fixing processing by the fixing means shown in the figure.

  In the first yellow image formation, the photosensitive drum 11Y is exposed by the exposure unit 13Y at the position P1 to form an electrostatic latent image, and then the latent image is developed by the developing unit 14Y, and the point P2 is developed. Thus, the transfer to the intermediate transfer belt 170 is performed by the primary transfer roller 15Y.

  However, in the tandem type color image forming apparatus, when the image forming method described in Patent Document 1 is employed in order to always maintain the image forming position of the image forming unit with respect to the paper edge, the following problems are caused. Occurred.

  In other words, the image data stored in the memory is shifted based on the paper misalignment information detected by the paper misalignment sensor 60 installed at the point P4 between the registration roller 25 and the secondary transfer roller 301. Thus, after correcting the image forming position by the image forming unit, the point P1 is compared with the sheet conveyance distance between the points P3 to P4, although the photosensitive drum 11Y starts to be exposed by the exposure unit 13Y at the position P1. Since the image conveyance distance between .about.P2 and P3 is significantly large, before reaching the point P3 where the color toner image on the intermediate transfer body 170 is transferred to the sheet S, the sheet deviation sensor 60 at the point P4 is moved. The sheet S that has passed through reaches the point P3 and image formation on the sheet S cannot be performed.

  On the other hand, the conveyance of the sheet S that has passed through the sheet deviation sensor 60 at the point P4 is temporarily stopped, and the conveyance of the sheet S is resumed at the timing when the color toner image on the intermediate transfer body 170 reaches the point P3. Although it is conceivable to control the registration rollers 25, the time for temporarily stopping the conveyance of the paper S becomes very long, and high-speed color image formation cannot be achieved.

  Further, such a problem is not limited to a tandem color image forming apparatus, but also in a monochrome image forming apparatus, by using a photosensitive drum having a large diameter or a long photosensitive belt, the exposure means for the photosensitive member can be used. This may occur when the distance between the exposure position and the transfer position of the toner image onto the paper becomes long.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus that solves the above-described problems and can form a high-quality image that is always in a fixed position with respect to the end of the sheet at high speed.

  The object of the present invention can be achieved by the following constitution.

The invention according to claim 1 is an image forming apparatus for transferring an image formed by an image forming unit to a recording material conveyed by a conveying unit by a transfer unit.
A swinging means that supports the transporting means and is swingable in a direction perpendicular to the transporting direction of the recording material transported by the transporting means;
A recording material deviation detection means for detecting the deviation amount of the recording material conveyed by the conveying means;
An image forming apparatus comprising: a control unit that controls a swing amount of the swing unit based on a shift amount of the recording material detected by the recording material shift detection unit.

According to a second aspect of the present invention, the conveying unit includes a first conveying roller that sandwiches the recording material and sends the recording material to the transfer unit;
A second conveying roller that sandwiches the recording material and sends the recording material to the first conveying roller,
2. The image according to claim 1, wherein the recording material deviation detection unit detects an amount of deviation of the recording material conveyed between the first conveyance roller and the second conveyance roller. Forming device.

The invention according to claim 3 has a third conveying roller for sandwiching the recording material and feeding the recording material to the conveying means,
The third conveying roller can release the recording material,
3. The image forming apparatus according to claim 1, wherein the control unit releases nipping of the recording material by the third transport roller while the swinging unit is swinging. .

  According to a fourth aspect of the present invention, the control unit prohibits the conveyance of the recording material to the transfer unit by the conveying unit while the oscillating unit is oscillating. The image forming apparatus according to any one of items 1 to 3.

The invention according to claim 5 includes a recording material posture correcting unit that corrects a relative posture of the recording material conveyed by the conveying unit with the recording material deviation detection unit,
5. The image formation according to claim 1, wherein the recording material deviation detection unit detects an amount of deviation of the recording material whose posture is corrected by the recording material posture correction unit. Device.

  The invention according to claim 6 is characterized in that after the image formation on the image carrier by the image forming unit is started, the recording material shift amount detection is performed by the recording material shift detection unit. 6. The image forming apparatus according to any one of 5 above.

  According to a seventh aspect of the invention, the image forming unit forms a color image by sequentially transferring images formed by a plurality of sets of image forming units onto an intermediate transfer member, and the transfer unit includes the intermediate transfer unit. 7. The image forming apparatus according to claim 1, wherein a color image on the body is transferred to a recording material.

  According to the first aspect of the present invention, based on the amount of deviation of the recording material detected by the recording material deviation detection means, the conveyance in the direction orthogonal to the conveyance direction of the recording material conveyed by the conveyance means. By controlling the swinging amount of the swinging means that swings the means, the transport position of the recording material to which the image is transferred is corrected according to the position of the image formed by the image forming means. It is possible to form a high-quality image that is always at a fixed position with respect to the portion at high speed.

  According to the second aspect of the present invention, the recording material deviation detection means is between the first conveyance roller that sends the recording material to the transfer means and the second conveyance roller that sends the recording material to the first conveyance roller. By detecting the amount of deviation of the recording material being conveyed, it is possible to accurately detect the amount of deviation of the recording material being conveyed immediately before the image is transferred by the transfer means and with the inclination being corrected. In addition, since there is almost no deviation of the recording material thereafter, the recording material conveyance position can be corrected with higher accuracy, and a high-quality image can be formed.

  According to the third aspect of the invention, while the swinging means is swinging, the holding of the recording material by the third transporting roller that feeds the recording material to the transporting means is released, so that the transporting means alone Even for a large recording material that cannot be transported, the transport position of the recording material can be corrected by the swinging means, and a high-quality image can be formed at high speed regardless of the type of recording material.

  According to the fourth aspect of the present invention, the conveyance position correction of the recording material by the oscillating means is prohibited by prohibiting the conveyance means from conveying the recording material to the transfer means while the oscillating means is oscillating. Since the recording material is conveyed to the transfer means after the image forming process is completed, it is possible to reliably form a high-quality image.

  According to the fifth aspect of the present invention, by detecting the amount of deviation of the recording material whose posture is corrected by the recording material posture correcting means, the amount of deviation of the recording material being conveyed while the inclination is corrected is detected. Since it can be detected, it is possible to correct the transport position of the recording material with higher accuracy and to form a high-quality image.

  According to the sixth aspect of the present invention, after the image is formed on the image carrier by the image forming unit, the recording material shift detection unit detects the amount of shift of the recording material, thereby forming the image forming unit. Until the transferred image reaches the transfer means, it is not necessary to stop the conveyance of the recording material, and a high-quality image can be formed at high speed.

  According to the seventh aspect of the present invention, the images formed by the plurality of sets of image forming units are sequentially transferred onto the intermediate transfer member to form a color image. Even in the so-called tandem type color image forming apparatus in which the distance between the toner image and the transfer position of the toner image onto the recording material becomes long, high-speed and high-quality image formation is possible.

  An example of an embodiment of the present invention will be described with reference to the drawings. The description in this column does not limit the technical scope of the claims or the meaning of terms.

  Note that the X, Y, and Z directions shown in each drawing are the left direction as the X direction and the right direction as the reverse X direction when the image forming apparatus of the present embodiment is viewed from the front. Further, when viewed from the front, the upward direction is the Y direction, and the downward direction is the reverse Y direction. The front direction when viewed from the front is the Z direction, and the rear direction is the reverse Z direction.

  FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus showing an example of an embodiment of the present invention. This image forming apparatus is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K that are image forming units and an intermediate transfer unit 17, and a transfer unit 30 that is a transfer unit. And a sheet conveying unit 20 and a fixing unit 40. A scanner 2 is disposed on the upper part of the image forming apparatus main body 1.

  A yellow image forming unit 10Y that forms a yellow image has a charging unit 12Y, an exposure unit 13Y, a developing unit 14Y, and a primary transfer unit arranged around a photosensitive drum 11Y as a first image carrier. It has a transfer roller 15Y and a cleaning means 16Y. Similarly to the yellow image forming unit 10Y, a magenta image forming unit 10M that forms a magenta image, a cyan image forming unit 10C that forms a cyan image, and a black image forming unit 10K that forms a black image are respectively photoreceptors. It has a drum, charging means, exposure means, developing means, primary transfer roller, and cleaning means.

  The intermediate transfer unit 17 includes an intermediate transfer body 170 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported. The transfer unit 30 includes a secondary transfer roller 301 and the like.

  The paper transport unit 20 is a paper feed cassette 21A, 21B, 21C, a manual paper feed tray 21D, a paper feed unit 211, a plurality of transport rollers 22A, 22B, and a third transport roller according to the present invention. Recording including a third conveyance roller 23, a loop roller 24 as a second conveyance roller according to the present invention, a registration roller 23 as a first conveyance roller, a paper discharge roller 26, a paper discharge tray 27, and a paper reversing mechanism 28 It is a mechanism for conveying materials. The loop roller 24 and the registration roller 23 constitute a conveying unit according to the present invention.

  The color images formed by the color image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the rotating intermediate transfer body 170 by the primary transfer roller 15Y and the like of the color image forming units, and the combined color. An image is formed. The paper S, which is a recording material according to the present invention, loaded on any of the paper feed cassettes 21A, 21B, 21C and the manual paper feed tray 21D, which are paper placement means, is fed one by one by the paper delivery means 211. Then, the leading edge of the sheet S is abutted against the registration roller 25 through the plurality of conveyance rollers 22A and 22B, the third conveyance roller 23, and the loop roller 24.

  The registration roller 25 with which the leading edge of the paper S is abutted stops rotating when it is abutted. When the registration roller 25 is stopped, the sheet S is fed by the loop roller 24, whereby the sheet S is bent (loop) between the loop roller 24 and the registration roller 24, and the bending of the sheet is corrected. Subsequently, a deviation amount of the sheet S from the reference position is detected by a sheet deviation sensor 60 provided between the loop roller 24 and the registration roller 25, and the present invention is determined according to the detected deviation amount. The swinging part 50 which is the swinging means related to swings a predetermined amount.

  Thereafter, rotation of the registration roller 25 is started in synchronization with image formation in the image forming units 10Y, 10M, 10C, and 10K and the intermediate transfer unit 17, and the sheet S is brought into contact with the secondary transfer roller 301 and the intermediate transfer belt 170. The color image is transferred onto the sheet S at a time. The sheet S on which the color image has been transferred is fixed by the fixing unit 40, is sandwiched between the sheet discharge rollers 26, and is stacked on the sheet discharge tray 27 outside the apparatus.

  On the other hand, after the color image is transferred onto the paper S by the secondary transfer roller 301, the residual toner is removed by the cleaning unit 171 from the intermediate transfer body 170 that has separated the curvature of the paper S. Residual toner is collected by an apparatus (not shown).

  During the image forming process, the primary transfer roller 15K is always in pressure contact with the photosensitive drum 11K. The primary transfer rollers of the other image forming units are pressed against the corresponding photosensitive drums only during color image formation. The secondary transfer roller 301 is pressed against the intermediate transfer body 170 only when the sheet S passes through the secondary transfer roller 301 and the secondary transfer is performed.

  The details of the loop roller 24 and the registration roller 25 as the conveying means according to the present invention, the sheet deviation sensor 60 as the recording material deviation detection means, and the swinging portion 50 as the swinging means will be described with reference to FIG. To do. 2A is a schematic perspective view of the swinging portion 50 in the image forming apparatus of FIG. 1, and FIG. 2B is a schematic plan view of the swinging portion 50 as viewed from the Y direction.

  The oscillating portion 50 includes a unit base 51, unit support portions 52a and 52b, a drive motor 53, a drive pulley mechanism 54, and support springs 55a and 55b. In FIG. 2A, a part of the bottom surface of the unit base 51 is cut out so that the lower part can be seen.

  The unit base 51 is a housing formed of a rigid metal or resin, and supports the loop roller 24 and the registration roller 25. The unit support portions 52a and 52b support the main body frame of the image forming apparatus (not shown). Are supported so as to be movable in the Z direction and the reverse Z direction. That is, the unit support portions 52a and 52b support the unit base 51 and also function as guides for moving the unit base 51 in the Z direction and the reverse Z direction in the drawing.

  The drive pulley mechanism 54 includes a first pulley 54a that is driven to rotate by a stepping motor 53 that performs a predetermined amount of rotation driving based on a signal from a control unit, which will be described later, via a wire 54b fixed by a wire fixing unit 54d. The two pulleys 54c are rotationally driven, and the unit base 51 is moved in the direction in which the unit support portions 52a and 52b are guided by the principle of the pulley.

  The support springs 55a and 55b couple the main body panel 100 of the image forming apparatus and the side surface of the unit base 51, and urge the entire unit base 51 in the reverse Z direction. By the cooperation of the support springs 55a and 55b and the drive pulley mechanism 54, the swinging portion 50 can freely move in the Z direction and the reverse Z direction.

  The loop roller 24 which is also a second conveying roller constituting the conveying means according to the present invention includes an upper roller 241 and a lower roller 242 supported by the unit base 51, a drive transmission mechanism 244, and a main body of an image forming apparatus (not shown). The drive motor 243 is supported by a frame. The sheet is sandwiched between the upper roller 241 and the lower roller 242, and is transmitted via the drive transmission mechanism 244 from the drive motor 243 that is driven and rotated based on a signal from a control unit described later. The lower roller 242 is rotationally driven by the rotational driving force, and the paper is conveyed in the X direction in cooperation with the upper roller 241 that is driven to contact. Note that. The drive transmission mechanism 244 can transmit rotational driving force to and from the drive motor 243 supported by the main body frame even when the lower roller 242 supported by the unit base 51 moves in the Z direction and the reverse Z direction. It has become.

  In the present embodiment, the drive of the loop roller 24 is controlled by the drive motor 243. However, the drive transmission mechanism 244 is provided with a clutch mechanism for switching the drive, and is also realized by controlling the clutch mechanism. Is possible.

  The registration roller 25 which is also a first conveyance roller constituting the conveyance unit according to the present invention includes an upper roller 251 and a lower roller 252 supported by the unit base 51, a drive transmission mechanism 254, and a main body of an image forming apparatus (not shown). It comprises a drive motor 253 supported by a frame. Since the configuration is the same as that of the loop roller 24 described above, description thereof is omitted.

  The paper misalignment sensor 60 which is a recording material misalignment detection means of the present invention is a position detection sensor constituted by a contact type line sensor, and an illumination LED (not shown) serving as a light emitting unit and the transport direction of the paper S And a light receiving unit composed of a line sensor (not shown) in which sensor groups are arranged in a direction perpendicular to the Z direction (Z direction in the figure). The sheet deviation sensor 60 is attached to the main body panel 100 of the image forming apparatus, detects the passage position of the sheet S as an absolute position or a relative position with respect to a predetermined reference position, and counts the position of the sheet deviation amount. Output as a value. A well-known detection method (for example, described in Japanese Patent Application Laid-Open No. 2001-166663) can be used for detecting the deviation of the sheet and outputting the position count value.

  Details of the third transport roller 23, which is the third transport roller according to the present invention, will be described with reference to FIG. FIG. 3 is a schematic perspective view of the third conveyance roller 23 in the image forming apparatus of FIG.

  The third transport roller 23 is arranged such that a pinch roller 235 comes into contact with a driving roller 233 in which a plurality of roller members are arranged in a skewered manner on a support shaft 232 driven by a motor (not shown).

  The pinch roller 235 is held by the support shaft 237 via the support arm 236, and a link 239 is connected to the support shaft 237. In addition, a solenoid 238 is connected to one end of the link 239, and a spring 230 is connected to the other end to constitute a mechanism for swinging the shaft 237. In the state of transporting the paper, the pinch roller 235 is pressed by the support arm 236, and a predetermined pressing force by the spring 230 is set between both rollers so as to exert the transporting action on the paper. The support arm 236 may be a thin plate member, but when a spring plate is used, the pressing force can be easily set.

  On the other hand, when the sheet is stopped and held, a solenoid 238 is urged in the reverse X direction by a signal from a control unit described later, and the link 239 is rotated against the force of the spring 230 to support the shaft. The pinch roller 235 is separated from the driving roller 233 via 237 to release the nip between both rollers.

  The main part of the control system of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 4 is a block diagram conceptually showing the functional structure of the image forming apparatus shown in FIG.

  The image forming apparatus 1 includes a control unit 101, a memory 102, a scanner 2, an image forming unit 10, a sheet transport unit 20, a transfer unit 30, a fixing unit 40, a swing unit 50, a sheet offset sensor 60, and an operation unit 103. Therefore, the description of the members having the same reference numerals as those shown in FIGS.

  The control unit 101 includes a CPU (Central Processing Unit) (not shown) and the like, reads a program stored in a storage unit (not shown) into the memory 102, and centrally controls each unit of the image forming apparatus 1 according to the program.

  The memory 102 forms a temporary storage area for image data or control parameters.

  The operation unit 103 controls display on the operation panel and operation input. In the operation unit 103, switching between a high image quality mode and a normal image quality mode can be input. The operation unit 103 is configured by a pressure-sensitive (resistive film pressure type) touch panel in which transparent electrodes are arranged in a lattice shape, and can also function as a display unit (not shown). The XY coordinate of the force point pressed with the touch pen or the like is detected by a voltage value, and the detected position signal is output to the control unit 101 as an operation signal.

  An operation example of the image forming apparatus of the present invention will be described with reference to FIGS. FIG. 5 is an operation timing chart of each part of the image forming apparatus when the high image quality mode is selected in the operation unit 103 in FIG. 4 or a host computer (not shown). The abscissa indicates the passage of time, and the ordinate indicates the image formation start reference signal, each color image forming unit 10Y to 10K, the transfer unit 30, the registration roller 25, the loop roller 24, the paper misalignment detection sensor 60, and the swing unit. 50, the on / off operation of the conveyance cancellation of the third conveyance roller 23 is shown. FIG. 6A to FIG. 6D are schematic views showing the transport state of the paper transported by the transport unit according to the present invention.

When an image formation start instruction is input from the operation unit 103 or a host computer (not shown), the image formation start reference signal is turned on, and the loop roller 24 starts to be rotated by the drive motor 243 (t ₀ ). .

Subsequently, the image forming unit 10Y starts an image forming operation (t _11Y ), and then the image forming unit 10M (t _11M ), the image forming unit 10C (t _11C ), and the image forming unit 10K (t _11K ) are also sequentially imaged. The forming operation is started, and the sheet S1 is conveyed by the conveyance roller 22B and the third conveyance roller 23. At this time, the registration roller 25 is still stopped (FIG. 6A).

The leading edge of the sheet S1 hits the nip portion of the registration roller 25 (t ₂ ), and the sheet S1 is still fed by the loop roller 24, so that the sheet S1 is bent between the loop roller 24 and the registration roller 25 (loop). ) R is formed (FIG. 6B). A restoring force is generated on the sheet S1 with respect to the loop R, and the entire leading edge of the sheet S1 comes into contact with the nip portion of the registration roller 25 by this restoring force, and the bending of the sheet S1, that is, the posture of the recording material is corrected. . At this time, the loop roller 24 and the registration roller 25 function as a recording material posture correcting unit that corrects the relative posture of the paper displacement sensor 60.

After the curvature of the sheet S1 is corrected by the loop roller 24 and the registration roller 25, the deviation amount of the sheet S1 from the reference position is detected by the sheet deviation sensor 60 provided between the loop roller 24 and the registration roller 25. Is detected (t ₃ ), and the control unit 101 immediately determines the swing amount of the swing unit 50.

When the loop roller 24 stops rotating and the conveyance of the third conveyance roller 23 is released, the drive motor 53 of the oscillating unit 50 rotates by a predetermined step by a control signal corresponding to the oscillating amount determined by the control unit 101. The loop roller 24 and the registration roller 25 move in the Z direction or the reverse Z direction while sandwiching the sheet S1 (t ₄ , FIG. 6C).

After the movement of the swinging unit 50 is completed, the nipping of the sheet S1 by the third transport roller is resumed and the rotation of the registration roller 25 is started in synchronization with the transport of the color image formed on the intermediate transfer belt 170 ( t ₆ ) After a predetermined time, the rotation of the loop roller 24 is started at the same conveyance speed as that of the registration roller 25. There is no loop R of sheets S1 which is formed by time t _2, the sheet S is fed to the image transfer position while maintaining a state there is no loop, the intermediate transfer belt 170 on which the image forming is started at time t _11Y Color The image is transferred to the sheet S1 (t ₈ ).

When the conveyance of the sheet S1 by the loop roller 24 and the registration roller 25 is completed, the swinging unit 50 is returned to the initial position (t ₉ ) to prepare for the next image formation on the sheet S2 already started at time t ′ ₀ .

  As described above, in the high image quality mode, by adjusting the transport position of the paper S in accordance with the color image formed on the intermediate transfer body 170, the end portion of the paper S is set at a certain position at the image transfer position. It is transferred in a maintained state.

The control of the swinging amount of the swinging unit based on the recording material shift amount detected by the recording material shift detection unit will be described with reference to FIG. 7, at time t ₃ in FIG. 5 is a flowchart showing the processing of the swing amount determination of the oscillation unit 50 is a swing unit that is executed by the control unit 101 is a control means.

  In step S101, the size of the sheet S onto which the image formed by the image forming unit 10 is transferred, in particular, the length in the Z direction orthogonal to the transport direction of the sheet S is detected. The detection of the sheet S1 is performed by selecting and inputting the sheet size (for example, A4, B5, etc.) using the operation unit 103 or a host computer (not shown) or by a sheet size sensor (not shown).

  In step S102, the position of the image formed by the image forming unit 10 is determined based on the size of the sheet S1 detected in step S101, and the photosensitive member longitudinal direction by the exposure unit based on the image data stored in the memory 102 is determined. The exposure position is corrected. Note that steps S101 and S102 have been completed before image formation by the image forming unit 10 is started.

  In step S103, based on the size of the sheet S1 detected in step S101 and the image forming position determined in step S102, the sheet offset amount detected by the sheet offset sensor 60 and the swing amount of the swing unit 50 are detected. A reference position for determining is determined. Specifically, the position is determined in step S102 at a position displaced by a half of the width of the sheet S1 detected in step S101 with reference to the center line Q of the sheet conveyance path through which the sheet S1 is conveyed. A value obtained by adding and subtracting the displacement amount of the image forming position is set as a reference position value.

  In step S104, the sheet deviation sensor 60 detects the deviation amount from the reference position of the sheet S1 whose curvature is corrected by the loop roller 24 and the registration roller 25, and outputs it as a position count value.

  In step S105, it is determined whether or not the amount of deviation detected in step S104 is within a predetermined amount set in advance. If it is determined that the amount is within the predetermined amount (step S104; YES), the process of step S106 is executed. If it is determined that the amount is not within the predetermined amount (step S104; NO), the image is transferred to the correct position on the sheet S1. If not, the process of step S107 is executed. The predetermined amount is determined in advance by the movable range of the swinging unit 50 while the loop roller 24 stops conveying the paper S.

  In step S106, the swinging amount of the swinging unit 50 is determined based on the deviation amount detected in step S104. Specifically, the number of steps by which the drive motor 53 of the swinging unit 50 rotates is determined using a predetermined calculation formula or processing table, and the process ends.

  In step S107, image formation by the image forming unit 10 is temporarily stopped, the position for image formation is changed, and the process returns to step S103.

  In this embodiment, the tandem color image forming apparatus is described as an example of the image forming apparatus. However, the image forming apparatus such as a copier, a composite apparatus, a printer, and a printer information providing terminal (for example, a kiosk terminal) is used. Is also applicable.

  Further, the object of the present invention is to supply a storage medium storing a software program for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (CPU or MPU) of the system or apparatus is stored in the storage medium. Needless to say, this can also be achieved by reading and executing the program.

  In addition, the detailed configuration and detailed operation of each component constituting the image forming apparatus can be changed as appropriate without departing from the spirit of the present invention.

1 is a cross-sectional configuration diagram of an image forming apparatus showing an example of an embodiment of the present invention. 2A is a schematic perspective view of the swinging portion in the image forming apparatus of FIG. 1, and FIG. 2B is a schematic plan view of the swinging portion as viewed from the Y direction. FIG. 4 is a schematic perspective view of a third transport roller in the image forming apparatus of FIG. 1. FIG. 2 is a block diagram conceptually showing a functional configuration of the image forming apparatus in FIG. 1. 6 is an operation timing chart of each part of the image forming apparatus when a high image quality mode is selected. It is the model which showed the conveyance state of the paper conveyed by the conveyance means which concerns on this invention. It is a flowchart which shows the process of the rocking | swiveling amount determination of the rocking | swiveling part performed by a control part. It is a schematic sectional drawing of the conventional tandem type color image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 2 Scanner 10Y, 10M, 10C, 10K Image formation part 17 Intermediate transfer unit 20 Paper conveyance part 23 3rd conveyance roller 24 Loop roller 25 Registration roller 30 Transfer part 40 Fixing part 50 Swing part 60 Paper side deviation Sensor 101 Control unit 102 Memory 103 Operation unit

Claims (7)

In an image forming apparatus for transferring an image formed by an image forming unit to a recording material conveyed by a conveying unit by a transfer unit,
A swinging means that supports the transporting means and is swingable in a direction perpendicular to the transporting direction of the recording material transported by the transporting means;
A recording material deviation detection means for detecting the deviation amount of the recording material conveyed by the conveying means;
An image forming apparatus comprising: a control unit configured to control a swing amount of the swing unit based on a shift amount of the recording material detected by the recording material shift detection unit. The conveying unit includes a first conveying roller that sandwiches the recording material and sends the recording material to the transfer unit;
A second conveying roller that sandwiches the recording material and sends the recording material to the first conveying roller;
2. The image according to claim 1, wherein the recording material deviation detection unit detects an amount of deviation of the recording material conveyed between the first conveyance roller and the second conveyance roller. Forming equipment. A third conveying roller for sandwiching the recording material and feeding the recording material to the conveying means;
The third conveying roller can release the recording material,
The image forming apparatus according to claim 1, wherein the control unit releases nipping of the recording material by the third conveying roller while the swinging unit is swinging. 4. The control device according to claim 1, wherein the control unit prohibits the conveyance of the recording material to the transfer unit by the conveyance unit while the oscillation unit is oscillating. 5. The image forming apparatus described. A recording material posture correcting unit that corrects a relative posture of the recording material conveyed by the conveying unit with the recording material deviation detection unit;
5. The image formation according to claim 1, wherein the recording material deviation detection unit detects an amount of deviation of the recording material whose posture is corrected by the recording material posture correction unit. apparatus. 6. The recording material misalignment detection by the recording material misalignment detection means is performed after the image formation on the image carrier by the image forming means is started. Image forming apparatus. The image forming unit sequentially transfers images formed by a plurality of sets of image forming units onto an intermediate transfer member to form a color image, and the transfer unit transfers the color image on the intermediate transfer member to a recording material. The image forming apparatus according to claim 1, wherein the image forming apparatus transfers the image to the image forming apparatus.

Images