JP2015200781A - image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can correct deviation of a roll sheet without using a guide member, and ensure the accuracy of position of an image.SOLUTION: An image forming apparatus includes: a paper-feed path through which a roll sheet can be conveyed; an image forming unit that transfers a toner image onto the roll sheet fed along the paper-feed path; a deviation detection unit that detects deviation in the sheet-width direction of the roll sheet on the paper-feed path; a deviation correction unit that corrects deviation of the roll sheet on the paper-feed path; and a control unit that operates the deviation correction unit on the basis of a result of the detection by the deviation detection unit between toner images from the completion of the transfer of a first toner image onto the roll sheet to the start of the transfer of a second toner image that is subsequently transferred onto the roll sheet.

Description

  The present invention relates to an electrophotographic image forming apparatus that forms an image on roll paper.

  In general, in an image forming apparatus (printer, copying machine, facsimile, etc.) using an electrophotographic process technology, a laser beam based on image data is irradiated (exposed) to a uniformly charged photoconductor (for example, a photoconductive drum). ), An electrostatic latent image is formed on the surface of the photoreceptor. Then, toner is supplied to the photoconductor on which the electrostatic latent image is formed, so that the electrostatic latent image is visualized and a toner image is formed. The toner image is transferred directly or indirectly to the sheet via an intermediate transfer member, and then heated and pressed by a fixing device, whereby an image is formed on the sheet.

  In such an image forming apparatus, a piece in the width direction of the sheet is caused by a slight inclination of the conveying roller shaft or a difference in nip pressures (hereinafter referred to as “conveying nip pressure”) of a plurality of roller pairs constituting the sheet passing path portion. It is known that a shift occurs. In particular, when image formation is performed on roll paper, since the deviation in the paper width direction is accumulated, the positional accuracy of the image decreases with time. Conventionally, the roll paper is prevented from shifting by pressing the guide members from both sides in the paper width direction (direction orthogonal to the paper conveyance direction) with respect to the roll paper (for example, Patent Document 1).

JP 2006-188352 A

  However, in the method of preventing the roll paper from being offset by the guide member, the end of the roll paper in the paper width direction comes into sliding contact with the guide member, and thus the roll paper may be deformed or damaged. In addition, when image formation is performed on tack roll paper (roll paper with surface base material, adhesive, release paper), the adhesive leaks from the edge of the roll paper in the paper width direction, and the roll paper and guide members are soiled. There is a risk of being.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can correct the deviation of roll paper without using a guide member and can ensure the positional accuracy of an image.

An image forming apparatus according to the present invention includes a paper passing path capable of conveying roll paper,
An image forming unit that transfers a toner image to roll paper that is passed along the paper passing path;
A deviation detection unit that detects a deviation in the paper width direction of the roll paper on the paper passing path;
A deviation correction unit that corrects a deviation of the roll paper on the sheet passing path;
The deviation correction is performed based on the detection result of the deviation detection unit between the toner images from the completion of the transfer of the first toner image to the start of the transfer of the second toner image to be transferred next. And a control unit for operating the unit.

According to the present invention, since the deviation of the roll paper is corrected based on the actual detection result, the deviation of the roll paper can be corrected without using the guide member, and the positional accuracy of the image can be ensured. Since the guide member is unnecessary, problems due to the sliding contact between the roll paper and the guide member (for example, damage to the roll paper and adhesion of the adhesive) do not occur.
Further, since the deviation correction is performed between the toner images on which the toner image is not transferred to the roll paper, the image quality is not deteriorated by the deviation correction, and the productivity is not impaired.

1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating an overall configuration of an image forming apparatus main body. FIG. 3 is a diagram illustrating a main part of a control system of the image forming apparatus main body. It is a side view which shows an example of the arrangement | positioning aspect of a deviation detection sensor and an approach roller part. It is a top view which shows an example of the arrangement | positioning aspect of a deviation detection sensor and an approach roller part. It is the figure which looked at the approach roller part from the upper direction (Z direction base end side). It is the figure which looked at the approach roller part from the paper conveyance direction upstream (Y direction base end side). It is a flowchart which shows an example of a deviation correction process.

FIG. 1 is a diagram showing an image forming apparatus 1 according to an embodiment of the present invention.
An image forming apparatus 1 illustrated in FIG. 1 includes a paper feeding device 1A, an image forming device main body 1B, and a winding device 1C.
The paper feeding device 1A has a roll paper feeding unit 91 and feeds paper according to an instruction from the image forming apparatus main body 1B. Roll paper fed from the paper feeding device 1 </ b> A is conveyed along the paper passing path 93. The image forming apparatus main body 1B forms an image on roll paper fed from the paper feeding device 1A. The winding device 1 </ b> C has a roll winding unit 92, and an image is formed by the image forming apparatus main body 1 </ b> B, and the fed roll paper is wound.

FIG. 2 is a diagram illustrating an overall configuration of the image forming apparatus main body 1B. FIG. 3 is a diagram illustrating a main part of a control system of the image forming apparatus main body 1B.
An image forming apparatus main body 1B shown in FIGS. 2 and 3 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. In the image forming apparatus main body 1B, photosensitive drums 213 corresponding to four colors of CMYK are arranged in series in the running direction (vertical direction) of the intermediate transfer belt 221, and each color toner image is sequentially applied to the intermediate transfer belt 221 in one procedure. A vertical tandem system for transfer is used.
That is, the image forming apparatus main body 1B primarily transfers the Y (yellow), M (magenta), C (cyan), and K (black) toner images formed on the photosensitive drum 213 to the intermediate transfer belt 221. After the four color toner images are superimposed on the intermediate transfer belt 221, the image is formed by secondary transfer onto a sheet.

  As shown in FIGS. 2 and 3, the image forming apparatus main body 1 </ b> B includes an image reading unit 11, an operation display unit 12, an image processing unit 13, an image forming unit 20, a paper feed unit 14, a paper discharge unit 15, and a paper transport unit 16. And a control unit 18.

  The control unit 18 includes a CPU (Central Processing Unit) 181, a ROM (Read Only Memory) 182, a RAM (Random Access Memory) 183, and the like. The CPU 181 reads out a program corresponding to the processing content from the ROM 182 or the storage unit 192, expands the program in the RAM 183, and cooperates with the expanded program in each block of the image forming apparatus main body 1B, the sheet feeding device 1A, and the winding device. Centrally control the operation of 1C.

The communication unit 191 includes various interfaces such as a NIC (Network Interface Card), a MODEM (Modulator-DEModulator), and a USB (Universal Serial Bus).
The storage unit 192 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive. The storage unit 192 stores, for example, a look-up table that is referred to when controlling the operation of each block.

  The control unit 18 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 191. Do. For example, the control unit 18 receives image data (input image data) in a page description language (PDL) transmitted from an external device, and forms an image on a sheet based on the received image data.

The image reading unit 11 includes an automatic document feeder 111 called an ADF (Auto Document Feeder), a document image scanning device 112 (scanner), and the like.
The automatic document feeder 111 conveys the document placed on the document tray by the conveyance mechanism and sends it out to the document image scanning device 112. The automatic document feeder 111 can continuously read images (including both sides) of a large number of documents placed on the document tray.
The document image scanning device 112 optically scans a document conveyed on the contact glass from the automatic document feeder 111 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 112a, and a document image is read. The image reading unit 11 generates input image data based on the reading result by the document image scanning device 112. The input image data is subjected to predetermined image processing in the image processing unit 13.

The operation display unit 12 includes, for example, a liquid crystal display (LCD) with a touch panel, and functions as the display unit 121 and the operation unit 122. The display unit 121 displays various operation screens, image status display, operation status of each function, and the like according to a display control signal input from the control unit 18. The operation unit 122 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 18.
The user can operate the operation display unit 12 to perform settings relating to image formation such as document setting, image quality setting, magnification setting, application setting, output setting, single-sided / double-sided setting, and paper setting. Further, the operation display unit 12 issues an error notification when the roll paper misalignment correction cannot be executed.

  The image processing unit 13 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 13 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 18. Further, the image processing unit 13 performs various correction processes such as color correction and shading correction, compression process, and the like on the input image data. The image forming unit 20 is controlled based on the image data subjected to these processes.

  The image forming unit 20 is based on the input image data, and an image forming unit 21 for forming an image with each color toner of Y component, M component, C component, and K component, and a toner image formed by the image forming unit 21 Are provided with an intermediate transfer unit 22 for transferring the toner image onto a sheet, a fixing unit 23 for fixing the transferred toner image on the sheet, and the like.

  The image forming unit 21 includes four image forming units 21Y, 21M, 21C, and 21K for Y component, M component, C component, and K component. Since the image forming units 21Y, 21M, 21C, and 21K have the same configuration, for convenience of illustration and description, common constituent elements are denoted by the same reference numerals, and the Y, M, and C are denoted by the same reference numerals when distinguished from each other. Or K. In FIG. 2, only the components of the Y-component image forming unit 21Y are denoted by reference numerals, and the reference numerals of the other image forming units 21M, 21C, and 21K are omitted.

  The image forming unit 21 includes an exposure device 211, a developing device 212, a photosensitive drum 213, a charging device 214, a drum cleaning device 215, and the like.

The photosensitive drum 213 includes, for example, an undercoat layer (UCL), a charge generation layer (CGL), and a charge transport layer (CTL) on a peripheral surface of an aluminum conductive cylindrical body (aluminum tube). : A negatively charged organic photoconductor (OPC) in which Charge Transport Layers are sequentially stacked.
The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive charges and negative charges upon exposure by the exposure device 211. The charge transport layer consists of a hole transport material (electron donating nitrogen-containing compound) dispersed in a resin binder (for example, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. To do.

  The charging device 214 is constituted by a corona discharge generator such as a scorotron charging device or a corotron charging device. The charging device 214 uniformly charges the surface of the photosensitive drum 213 to a negative polarity by corona discharge.

  The exposure apparatus 211 includes, for example, an LED array in which a plurality of light emitting diodes (LEDs) are linearly arranged, an LPH driving unit (driver IC) for driving individual LEDs, and emitted light from the LED array Is formed by an LED print head having a lens array or the like that forms an image on the photosensitive drum 213. One LED of the LED array corresponds to one dot of the image. When the control unit 18 controls the LPH driving unit, a predetermined driving current is supplied to the LED array, and a specific LED emits light.

  The exposure device 211 irradiates the photosensitive drum 213 with light corresponding to the image of each color component. The positive charge generated in the charge generation layer of the photosensitive drum 213 is transported to the surface of the charge transport layer, so that the surface charge (negative charge) of the photosensitive drum 213 is neutralized. Thereby, an electrostatic latent image of each color component is formed on the surface of the photosensitive drum 213 due to a potential difference from the surroundings.

  The developing device 212 contains a developer for each color component (for example, a two-component developer composed of toner and a magnetic carrier). The developing device 212 visualizes the electrostatic latent image by forming toner of each color component on the surface of the photosensitive drum 213 to form a toner image. Specifically, a developing bias voltage is applied to the developer carrier (developing roller), and an electric field is formed between the photosensitive drum 213 and the developer carrier. Due to the potential difference between the photosensitive drum 213 and the developer carrying member, the charged toner on the developer carrying member moves to and adheres to the exposed portion of the surface of the photosensitive drum 213.

  The drum cleaning device 215 includes a drum cleaning blade that is slidably contacted with the surface of the photosensitive drum 213, and removes transfer residual toner remaining on the surface of the photosensitive drum 213 after primary transfer.

  The intermediate transfer unit 22 includes an intermediate transfer belt 221, a primary transfer roller 222, a plurality of support rollers 223, a secondary transfer roller 224, a belt cleaning device 225, and the like.

  The intermediate transfer belt 221 is an endless belt, and is stretched around a plurality of support rollers 223 in a loop shape. At least one of the plurality of support rollers 223 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the support roller 223 disposed downstream of the K component primary transfer roller 222 in the belt traveling direction is a drive roller. As the drive roller rotates, the intermediate transfer belt 221 travels in the direction of arrow A at a constant speed.

  The primary transfer roller 222 is disposed on the inner peripheral surface side of the intermediate transfer belt 221 so as to face the photosensitive drum 213 of each color component. The primary transfer roller 222 is pressed against the photosensitive drum 213 with the intermediate transfer belt 221 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 213 to the intermediate transfer belt 221.

  The secondary transfer roller 224 is disposed on the outer peripheral surface side of the intermediate transfer belt 221 so as to face one of the plurality of support rollers 223. The support roller 223 disposed to face the intermediate transfer belt 221 is called a backup roller. The secondary transfer roller 224 is pressed against the backup roller with the intermediate transfer belt 221 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 221 to the sheet.

  In the primary transfer nip, the toner image on the photosensitive drum 213 is primarily transferred to the intermediate transfer belt 221 in order. Specifically, a primary transfer bias is applied to the primary transfer roller 222, and a charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 221 (the side in contact with the primary transfer roller 222). It is electrostatically transferred to the intermediate transfer belt 221.

  Thereafter, when the sheet passes through the secondary transfer nip, the toner image on the intermediate transfer belt 221 is secondarily transferred to the sheet. Specifically, by applying a secondary transfer bias to the secondary transfer roller 224 and applying a charge having a polarity opposite to that of the toner to the back side of the paper (the side in contact with the secondary transfer roller 224), the toner image becomes It is electrostatically transferred to the paper. The sheet on which the toner image is transferred is conveyed toward the fixing unit 23.

  The belt cleaning device 225 includes a belt cleaning blade that is in sliding contact with the surface of the intermediate transfer belt 221 and removes transfer residual toner remaining on the surface of the intermediate transfer belt 221 after the secondary transfer.

  In the intermediate transfer unit 22, the secondary transfer belt is looped around a plurality of support rollers including the secondary transfer roller instead of the secondary transfer roller 224 (so-called belt-type secondary transfer). Unit) may be adopted.

  The fixing unit 23 is disposed on the upper fixing unit 231 having a fixing surface side member disposed on the fixing surface (surface on which the toner image is formed) side of the paper, and on the back surface (surface opposite to the fixing surface) side of the paper. A lower fixing unit 232 having a back-side support member, a heating source 233 for heating the fixing-side member, and a press-contacting / separating unit (not shown) for pressing the back-side support member against the fixing-side member.

For example, when the upper fixing unit 231 is a roller heating method, the fixing roller is a fixing surface side member, and when the upper fixing portion 231 is a belt heating method, the fixing belt is a fixing surface side member. Further, for example, when the lower fixing unit 232 is a roller pressurization method, the pressure roller is a backside support member, and when the lower fixing unit 232 is a belt pressurization method, the pressure belt is a backside support member. The fixing surface side member and the back surface side supporting member may be collectively referred to as a “fixing member”.
FIG. 2 shows a case where the upper fixing unit 231 is configured by a roller heating method and the lower fixing unit 232 is configured by a roller pressing method.

  The upper fixing unit 231 includes an upper fixing unit driving unit (not shown) for rotating the fixing surface side member. When the operation of the upper fixing unit driving unit is controlled by the control unit 18, the fixing surface side member rotates (runs) at a predetermined speed. The lower fixing unit 232 includes a lower fixing unit driving unit (not shown) for rotating the back side support member. When the operation of the lower fixing unit driving unit is controlled by the control unit 18, the back side support member rotates (runs) at a predetermined speed. When the fixing surface side member is driven by the rotation of the back surface side support member, the upper fixing portion driving unit is not necessary.

  The heat source 233 is disposed in or near the fixing surface side member. By controlling the output of the heating source 233 by the control unit 18, the fixing surface side member is heated and held at a predetermined temperature (for example, allowable fixing temperature, fixing idling temperature). The control unit 18 controls the output of the heating source 233 based on the detection result of a fixing temperature detection unit (not shown) arranged close to the fixing surface side member.

  Further, the operation of the press contact / separation portion (not shown) is controlled by the control unit 18 and the back surface side support member is pressed against the fixing surface side member, thereby forming a fixing nip for nipping and transporting the sheet. The sheet on which the toner image is secondarily transferred and conveyed along the sheet passing path is heated and pressurized when passing through the fixing nip. As a result, the toner image is fixed on the paper.

  The fixing unit 23 cools the fixing surface side member or the back surface side support member or separates the sheet from the fixing surface side member or the back surface side support member with respect to the fixing surface side member or the back surface side support member. You may provide the ventilation part which performs ventilation.

  The paper feed unit 14 includes a paper feed tray unit 141 and a manual paper feed unit 142. In the paper feed tray unit 141, sheets (standard paper, special paper) identified based on basis weight, size, and the like are stored for each preset paper type. The roll paper sent out from the paper feeding device 1A is fed via the manual paper feeding unit 142.

  The paper discharge unit 15 includes a paper discharge roller unit 151 and the like, and discharges the paper sent from the paper transport unit 16 to the outside of the apparatus.

  The sheet transport unit 16 includes a main sheet passing path unit 161, a switchback path unit 162, a back surface printing path unit 163, a sheet passing path switching unit (not shown), and the like. The paper transport unit 16 is incorporated in one unit together with the fixing unit 23, and is detachably attached to the image forming apparatus main body 1B as a paper transport unit (a so-called ADU (Auto-Duplex Unit)).

  The main sheet passing path section 161 includes a plurality of transport roller sections including an entrance roller section 165 disposed on the upstream side of the secondary transfer nip in the sheet transport direction. The main sheet passing path unit 161 conveys a sheet fed from the sheet feeding tray unit 141 or a roll sheet fed from the sheet feeding device 1A via the manual sheet feeding unit 142 to convey the image forming unit 20 ( The paper is passed through the secondary transfer nip (fixing nip) and the paper sent from the image forming unit 20 (fixing unit 23) is conveyed to the paper discharge unit 15.

  The switchback path unit 162 temporarily stops the paper sent from the fixing unit 23, reverses the transport direction, and transports it to the paper discharge unit 15 or the back surface printing path unit 163.

  The back surface printing path unit 163 is a circulation path that conveys the paper that is switched back and sent out by the switchback path unit 162 to the main sheet passing path unit 161. A sheet is passed through the main sheet passing path portion 161 with the second surface (back surface) being the upper surface.

  The sheet passing path switching unit (not shown) passes the sheet sent out from the fixing unit 23 as it is, whether it is discharged after being reversed, discharged, or conveyed to the back surface printing path unit 163. Switch the paper path. Specifically, the control unit 18 controls the operation of the sheet passing path switching unit based on the processing content of the image forming process (single-sided / double-sided printing, face-up discharge, face-down discharge, etc.).

  When image formation is performed on roll paper, the roll paper is fed from the paper feeding device 1 </ b> A via the manual paper feed unit 142. The fed roll paper is conveyed to the image forming unit 20 by the main paper passing path unit 161. Then, when the roll paper passes through the secondary transfer nip, the toner image on the intermediate transfer belt 221 is secondarily transferred to the roll paper at once and subjected to fixing processing in the fixing unit 23. The roll paper on which the image is formed is discharged from the paper discharge unit 15 to the outside of the apparatus, and is taken up by the roll take-up unit 92 of the take-up device 1C.

  As described above, the main sheet passing path portion 161 constitutes a part of the sheet passing path when image formation is performed on roll paper in the image forming apparatus 1. When image formation is performed on roll paper, the switchback path unit 162, the back surface printing path unit 163, and the sheet passing path switching unit (not shown) are not used.

Further, the image forming apparatus 1 detects a deviation of the sheet on the main sheet passage path 161, and a deviation of the sheet (in the sheet width direction) based on the detection result of the deviation detection sensor S1. And a deviation correction unit for correcting (position).
In the present embodiment, the entrance roller unit 165 functions as a deviation correction unit. By causing the entrance roller 165 disposed on the upstream side of the secondary transfer nip in the paper conveyance direction to function as a deviation correction unit, the toner image is transferred to the sheet on which the deviation correction has been performed. Position accuracy is improved.

  FIG. 4 is a side view showing an example of an arrangement mode of the deviation detection sensor S1 and the entrance roller portion 165. As shown in FIG. FIG. 5 is a plan view illustrating an example of an arrangement mode of the deviation detection sensor S <b> 1 and the entrance roller unit 165.

As shown in FIGS. 4 and 5, the deviation detection sensor S <b> 1 is located downstream of the entry roller unit 165 in the sheet conveyance direction (between the entry roller unit 165 and the secondary transfer nip _NT ) in the main sheet passing path unit 161. Be placed. By disposing the deviation detection sensor S1 (deviation detection unit) in the vicinity of the entry roller unit 165 (deviation correction unit), the deviation of the paper in the entry roller unit 165 can be appropriately determined, so that the accuracy is high. Misalignment correction can be realized.

The deviation detection sensor S1 is composed of, for example, a line sensor in which image receiving elements are arranged in a row (or a plurality of rows). The deviation detection sensor S1 is arranged in parallel to the paper width direction.
The deviation detection sensor S1 detects the position of the edge of the sheet in the width direction by turning on illumination (for example, an LED) when the sheet is passing through the detection area and photographing with the image receiving element. From the detected position of the edge in the width direction of the sheet, a deviation amount ΔX (deviation amount) of the sheet is calculated. By configuring the deviation detection sensor S1 with a line sensor, the deviation amount ΔX can be detected with high accuracy (for example, several tens of μm).

FIG. 6 is a view of the entrance roller portion 165 as viewed from above (the base end side in the Z direction). FIG. 7 is a diagram of the entrance roller unit 165 as viewed from the upstream side in the sheet conveyance direction (Y direction base end side).
As shown in FIGS. 6 and 7, the entrance roller unit 165 includes a pair of rollers including a driving roller 31 and a driven roller 32 disposed to face the driving roller 31. The driving roller 31 is composed of, for example, a rubber roller, and the driven roller 32 is composed of, for example, a metal roller. When the driven roller 32 is brought into pressure contact with the driving roller 31, a nip portion (entry nip) for nipping and conveying the sheet is formed.

  The driving roller 31 and the driven roller 32 are inserted into bearings formed on the frame 38 and are rotatably fixed. The roller shaft 31 b of the driving roller 31 and the roller shaft 32 b of the driven roller 32 are connected by a connecting member 37. As a result, when correcting the position of the paper in the paper width direction, the drive roller 31 and the driven roller 32 swing together in the paper width direction.

  The drive roller 31 is connected to the drive motor 36 via a power transmission unit including gears 31a and 36a. The gear 31a has a predetermined length so that the driving force is transmitted even when the driving roller 31 swings in the axial direction during swinging. The power of the drive motor 36 is transmitted to the drive roller 31 via the gears 36a and 31a, whereby the drive roller 31 and the driven roller 32 rotate. The sheet conveying operation (driving of the driving motor 36) in the entrance roller unit 165 is controlled by the control unit 18.

  The driving roller 31 is connected to the swing motor 33 via a power transmission unit 34 including a rack 34b and a pinion 34a. The rack 34b is a cylindrical member having a bearing on the inner surface, and is inserted through the roller shaft 31b. The rack 34b is fixed in the vicinity of the gear 31a by sandwiching both ends of the rack 34b with two washers (for example, an E ring) fixed to the roller shaft 31b. That is, the rack 34b allows the drive roller 31 to rotate, but is fixed so as not to swing in the axial direction. When the power of the swing motor 33 is transmitted to the drive roller 31 via the power transmission unit 34, the drive roller 31 and the driven roller 32 swing in the paper width direction.

Specifically, the control unit 18 drives the swinging motor 33 based on the detection result of the deviation detection sensor S1, and controls the swinging operation of the entrance roller unit 165. At this time, the control unit 18 refers to the swing control table stored in the storage unit 192, acquires the swing command value corresponding to the deviation amount ΔX, and uses the swing command value to control the swing motor 33. Drive.
The rotational motion of the swing motor 33 is converted into a linear motion by the pinion 34 a and the rack 34 b and transmitted to the drive roller 31. As a result, the drive roller 31 and the driven roller 32 swing by a predetermined amount (a swing amount corresponding to the swing command value) in the axial direction. The position in the width direction of the paper is adjusted by the drive roller 31 and the driven roller 32 being rotated, that is, swinging in the paper width direction while transporting the paper.

  The entrance roller 165 swings within a predetermined swing allowable range (for example, ± 5 mm) with reference to the home position. The home position is a position where the entrance roller portion 165 does not swing in the paper width direction (the swing amount is 0). In the initial state, the roll paper passes through the central portion of the entrance nip in the paper width direction. Is set.

In the image forming apparatus 1, when image formation is performed on roll paper, a plurality of images are continuously transferred onto the roll paper. In this case, if the deviation correction operation is performed during the transfer of the toner image onto the roll paper, the image quality may be deteriorated. In the present embodiment, as shown in FIG. 4, when the toner image area (the area where the toner image is not formed) on the secondary transfer belt 221 passes through the secondary transfer nip _NT , that is, to roll paper. When the toner image is not transferred, the approach roller 165 as the deviation correction unit operates based on the detection result (deviation amount ΔX) of the deviation detection sensor S1. Specifically, the control unit 18 performs a deviation correction process according to the flowchart shown in FIG.

  FIG. 8 is a flowchart illustrating an example of the deviation correction process. This process is realized, for example, by the CPU 181 executing a predetermined program stored in the ROM 182 when the image forming apparatus 1 starts an image forming process on roll paper.

  In step S101 in FIG. 8, the control unit 18 determines whether the paper used for image formation is roll paper based on the paper type information included in the print job. If the paper used for image formation is roll paper (“YES” in step S101), the process proceeds to step S102. If the paper used for image formation is not roll paper ("NO" in step S101, for example, a sheet), the misalignment correction processing is terminated.

  In step S102, the control unit 18 acquires the detection result (deviation amount ΔX) of the deviation detection sensor S1.

  In step S103, the control unit 18 determines the magnitude of the acquired deviation amount ΔX. Here, the first threshold A is a value for determining whether or not a certain image quality can be maintained, and is set to 0.2 mm, for example. The second threshold value B is a value for determining whether or not the deviation of the roll paper can be corrected between normal toner images, and is set to 0.5 mm, for example. The third threshold value C is a value for determining whether or not a roll paper passing defect has occurred, and is set to, for example, 1.0 mm.

  When the deviation amount ΔX is smaller than the first threshold A, a constant image quality is maintained. In this case, the swing operation of the entrance roller unit 165 is not performed, and the process proceeds to step S109. Even if a small amount of deviation is detected due to vibration of the roll paper or the like, the deviation correction is not performed.

When the deviation amount ΔX is equal to or larger than the first threshold value A and smaller than the second threshold value B, it affects the image quality, but can be corrected while the normal toner image passes through the secondary transfer nip _NT. This means that a degree of deviation has occurred. In this case, the process proceeds to step S104.

When the deviation amount ΔX is equal to or larger than the second threshold value B and smaller than the third threshold value C, it affects the image quality and cannot be corrected while the normal toner image passes through the secondary transfer nip _NT. This means that a degree of deviation has occurred. In this case, the process proceeds to step S105.

  When the deviation amount ΔX is equal to or greater than the third threshold value C, there is a high possibility that a roll paper passing defect has occurred. In this case, the process proceeds to step S107.

In step S104, the control unit 18 swings the entry roller unit 165 at the timing when the next toner image passes through the secondary transfer nip _NT , and corrects the deviation of the roll paper. At this time, the swing amount of the entrance roller portion 165 is determined based on the deviation amount ΔX.

  In this way, the control unit 18 operates the entrance roller unit 165 (deviation correction unit) when the detection result of the deviation detection sensor S1 (deviation detection unit) exceeds a predetermined threshold (A ≦ ΔX). Let As a result, since the deviation correction is not performed for the deviation that can maintain a constant image quality, the control of the entrance roller unit 165 for performing the deviation correction is simplified, and the deviation is frequently performed. It is possible to prevent the entrance roller portion 165 from being deteriorated due to the shift correction operation.

  In step S <b> 105, the control unit 18 controls the operation of the image forming unit 21 to expand the space between the toner images as compared with that during normal image formation to form a toner image. At this time, the expansion amount between the toner images is set based on the swinging time of the entrance roller portion 165 and the traveling speed of the intermediate transfer belt 221 that are necessary for deviation correction.

  In step S <b> 106, the control unit 18 swings the entry roller unit 165 when the expanded toner image passes through the secondary transfer nip, and corrects the deviation of the roll paper. At this time, the swing amount of the entrance roller portion 165 is determined based on the deviation amount ΔX.

  As described above, when the deviation of the roll paper cannot be corrected between the toner images (B ≦ ΔX), the control unit 18 extends the interval between the toner images formed by the image forming unit 20. Accordingly, since the time during which the deviation can be corrected by swinging the entrance roller 165 becomes longer, the deviation can be reliably corrected while the toner image is not transferred.

In step S107, the control unit 18 stops the image forming process.
In step S <b> 108, the control unit 18 causes the operation display unit 12 to display that a paper passing defect has occurred (error notification).

  As described above, the image forming apparatus 1 includes the operation display unit 12 (information presenting unit) that presents information to the user, and the control unit 18 detects a paper passing failure of the roll paper (ΔX> C). The operation display unit 12 is notified of an error without operating the entry roller unit 165 (deviation correction unit). As a result, the user can quickly know the paper passing failure of the roll paper and can perform appropriate error processing.

  In step S109, the control unit 18 determines whether or not a series of image forming processes has been completed. A series of image forming processes is a process for forming an image set by a signal (for example, a print job) instructing image formation. When the series of image forming processes is completed (“YES” in step S109), the deviation correction process is ended. If the series of image forming processes has not ended ("NO" in step S109), the processes in and after step S102 are repeated. In addition, when the deviation correction process ends, the approach roller unit 165 is returned to the home position.

  In addition, when the swinging amount (integrated amount) of the entrance roller unit 165 exceeds the swing allowable range (including the case where it is likely to exceed), the control unit 18 sets the entrance roller unit 165 (deviation correction unit) as a separated state. It is preferable to return to the position. Or you may make it the control part 18 return the approach roller part 165 to a home position regularly. Thereby, even when the deviation of the roller paper occurs with time, it is possible to appropriately cope with it.

  As described above, the image forming apparatus 1 transfers the toner image to the main sheet passing path unit 161 (sheet passing path) capable of transporting the roll sheet and the roll sheet passing along the main sheet passing path unit 161. The image forming unit 20 to perform, a deviation detection sensor S1 (deviation detection unit) for detecting a deviation of the roll paper on the main paper passage path unit 161 in the paper width direction, and a roll paper on the main paper passage unit 161. An entrance roller 165 (shift correction unit) that corrects the deviation of the toner, and a toner image from when the transfer of the first toner image is completed until the transfer of the second toner image to be transferred next is started. And a control unit 18 that operates the entrance roller unit 165 based on the detection result of the deviation detection sensor S1.

  According to the image forming apparatus 1, since the deviation of the roll paper is corrected based on the actual detection result (deviation amount ΔX), the deviation of the roll paper can be corrected without using a guide member. Accuracy can be ensured. Since the guide member is unnecessary, problems due to the sliding contact between the roll paper and the guide member (for example, damage to the roll paper and adhesion of the adhesive) do not occur. Further, since the deviation correction is performed between the toner images on which the toner image is not transferred to the roll paper, the image quality is not deteriorated by the deviation correction, and the productivity is not impaired.

As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be changed without departing from the gist thereof.
For example, the arrangement of the sheet detection sensor S1 may be on the main sheet passing path portion 161, and may be, for example, upstream of the deviation correction unit in the sheet conveyance direction. Moreover, a conveyance roller part other than the entrance roller part 165 can also be applied to the deviation correction part.
Furthermore, in addition to a method of swinging while pinching roll paper, a so-called steering control method of tilting the axis of the transport roller unit can be applied to the deviation correction unit.

  Further, when the deviation of the roll paper cannot be corrected between the normal toner images (“B ≦ ΔX <C” in step S103 in FIG. 8), the control unit 18 includes a plurality of entrance roller units 165 (deviation correction units). The operation may be performed between the toner images. Furthermore, after the space between the toner images is expanded, the entrance roller unit 165 (deviation correction unit) may be operated between a plurality of toner images.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1A Paper feeding apparatus 1B Image forming apparatus main body 1C Winding apparatus 11 Image reading part 12 Operation display part 13 Image processing part 14 Paper feeding part 15 Paper discharge part 16 Paper conveyance part 18 Control part 20 Image forming part 21 Image Forming unit 22 Intermediate transfer unit 23 Fixing unit 161 Main sheet passing path unit 162 Switchback path unit 163 Back side printing path unit 165 Entrance roller unit (deviation correction unit)
N _F fixing nip N _T secondary transfer nip S1 Misalignment detection sensor (deviation detection section)

Claims (9)

A paper feed path through which roll paper can be conveyed,
An image forming unit that transfers a toner image to roll paper that is passed along the paper passing path;
A deviation detection unit that detects a deviation in the paper width direction of the roll paper on the paper passing path;
A deviation correction unit that corrects a deviation of the roll paper on the sheet passing path;
The deviation correction unit based on the detection result of the deviation detection unit between the toner images after the transfer of the first toner image is completed and the transfer of the second toner image to be transferred next is started. An image forming apparatus comprising: a control unit that operates the apparatus.   The image forming apparatus according to claim 1, wherein the control unit operates the shift correction unit when a detection result of the shift detection unit exceeds a predetermined threshold.   3. The image formation according to claim 1, wherein when the deviation of the roll paper cannot be corrected between the toner images, the control unit extends the interval of the toner images formed by the image forming unit. apparatus.   4. The control unit according to claim 1, wherein, when the deviation of the roll paper cannot be corrected between the toner images, the control unit operates the deviation correction unit between the plurality of toner images. 5. The image forming apparatus described in 1. It has an information presentation unit that presents information to users,
5. The control unit according to claim 1, wherein the control unit causes the information presentation unit to perform error notification without operating the deviation correction unit when a roll paper passing defect is detected. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the shift detection unit is disposed in the vicinity of the shift correction unit.   The image forming apparatus according to claim 1, wherein the deviation correction unit is disposed upstream of the image forming unit in a sheet conveyance direction.   The image forming apparatus according to claim 1, wherein the deviation correction unit swings in a paper width direction while sandwiching a roll paper.   The image forming apparatus according to claim 8, wherein the control unit returns the deviation correction unit to a home position in a separated state when the amount of oscillation of the deviation correction unit exceeds an allowable swing range.

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