JP2007022806A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of being simply controlled, correcting bending of a transfer paper repeatedly, and forming an image having high quality. <P>SOLUTION: This image forming device has a transfer attitude correction part for correcting transfer attitude of the transfer paper for receiving a toner image and conveying the corrected transfer paper into a transfer part by setting timing to travel of the toner image rotating together with an image holding body. The transfer attitude correction part has a register roller for conveying the transfer paper, a rotatable roller unit holding the register roller, a detection part for detecting a position of the transfer paper conveyed by the register roller, and a control part for rotating the roller unit based on the data detected by the detection part to correct bending of the transfer paper and moving the register roller on the roller unit to correct a transfer position of the transfer paper. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus that forms and outputs a toner image on a transfer paper as a copying machine, a printer, a facsimile machine, and a complex machine thereof, and in particular, transfer paper conveyed to a transfer position for transferring a toner image. The present invention relates to control for correcting a transfer posture for receiving a toner image.

  A recent image forming apparatus is connected to a personal computer (also referred to as a personal computer) or the like, and inputs information (also referred to as character information) composed of characters, numbers, symbols, or the like to form an image (printing or printing). , Or information that is composed of images and text and text information (also referred to as image information), and prints and outputs more. Yes.

  For example, when outputting image information such as a color photograph, an image cut into a square shape is often inserted into a printable area per page of transfer paper. Therefore, when the transfer sheet is conveyed and printed in a skewed state (hereinafter referred to as “bend”) with respect to the conveyance direction, the boundary portion of the rectangular image is linear. Further, the margin portion provided between the end portions of the transfer paper is inclined, and the “curvature of the transfer paper” is further emphasized, and depending on the viewpoint, there is a problem that the “curvature of the image” can be taken.

  Therefore, when outputting image information, the transfer paper bends more conspicuously than when outputting character information, and in order to enable high-quality image formation, it is as small as previously allowed. It has become desirable to be able to correct even the bending of transfer paper.

  In particular, for example, toner images of each color formed by color toners such as Y (yellow), M (magenta), C (cyan), and K (black) are repeatedly transferred onto transfer paper and superimposed to form a color image. In the image forming apparatus of this type, when the transfer paper is bent as described above, a phenomenon called “color misregistration” occurs, and an image with inferior quality is formed.

  Further, when the transfer sheet is shifted laterally from the transfer reference position, there is a problem that the transfer position of the image is different for each transfer sheet and the appearance is deteriorated.

  Therefore, in order to correct the above-described bending of the transfer paper, the transfer paper with higher accuracy than the conventionally well-known registration apparatus of the method of correcting the bending of the transfer paper by abutting the transfer paper against the pair of rollers. A technology that can correct bending is disclosed.

  For example, by disposing the tilt detection unit and the position detection unit on the downstream side of the conveyance roll pair of the registration device, the inclination or side of the transfer paper can be obtained when the recording sheet (transfer paper) is sandwiched between the conveyance roll pair. Since the detection of the position of the edge is performed, if the conveyance roll pair is rotated in accordance with the bending angle indicating the inclination of the transfer paper calculated based on the detection result, the correction of the transfer paper can be accurately corrected. A technique that can be used is disclosed (for example, see Patent Document 1).

  In addition, a detection unit that detects the inclination with respect to the transfer sheet conveyance direction with the sheet S (transfer sheet) being sandwiched is provided. When the transfer sheet is skewed, the inclination correction is performed based on the detection signal from the detection unit. The leading edge position t seconds after the inclination is corrected by the rotation of the means is calculated and predicted, and the conveyance speed of the registration roller pair is calculated according to the obtained deviation amount of the leading edge of the transfer paper after t seconds.

  Then, based on the calculation result, the bending correction means is rotated to correct the transfer paper so that the front end of the transfer paper and the front end of the image on the photosensitive drum coincide with each other at the transfer unit. The transfer paper is conveyed by adjusting the transfer paper conveyance speed by the registration roller pair to the obtained conveyance speed before reaching the section.

  After the leading edge of the transfer paper reaches the transfer section, the transfer paper is transported to the transfer section at the same speed as the peripheral speed of the photosensitive drum, so that the transfer paper is extremely accurate without temporarily stopping the transfer paper. A technique is disclosed that corrects the bending of (see, for example, Patent Document 2).

In addition, a technique has been disclosed in which a position detection sensor is provided in a direction orthogonal to the transfer paper transport direction to detect the position of the side edge of the transfer paper along the transfer paper transport direction to detect the inclination of the transfer paper. (For example, refer to Patent Document 3).
Japanese Patent Laid-Open No. 10-67448 JP 2005-53646 A JP 2005-35709 A

  However, Patent Document 1 corrects the bending in the direction orthogonal to the conveyance direction by the rotation of the conveyance roll pair, but depending on the rotation center position of the conveyance roll pair, the left end of the leading edge of the transfer paper in the direction orthogonal to the conveyance direction. Or, the right end position is not always corrected to the normal position. Next, move the transfer paper in the direction perpendicular to the transport direction to correct the left end or right end position of the transfer paper to the normal position. There is a need to. Therefore, there is a problem that when performing the correction by the parallel movement, the transfer paper may be bent again in some cases.

  Further, since Patent Document 2 predicts and corrects the leading edge position of the transfer paper after t seconds after the bending correction is made by turning the bending correction means based on the detection signal from the detection means. Although there is an advantage that correction can be performed without stopping, in some cases, the timing of the prediction and the actual, for example, the transfer speed of the transfer paper, etc., do not accurately match, and as a result, the bending is sufficient. There was a problem that sometimes it could not be corrected.

  In other words, since both Patent Document 1 and Patent Document 2 perform the curve correction based on the signal once detected, for example, the curve generated after the curve correction or the slight curve that cannot be corrected is corrected. There was a problem that I could not.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a correction unit that clamps transfer paper and corrects the inclination of the transfer paper. While the inclination is corrected, the holding roller that transports the transfer paper is released. Therefore, there is a complicated problem that the clamping operation of the correction unit and the clamping operation of the transport roller must be controlled with good timing.

  In view of the above problems, an object of the present invention is to provide an image forming apparatus that is easy to control, can repeatedly perform bending correction of transfer paper, and can form a high-quality image.

This invention can achieve the said objective by taking the following structure.
1.
An image carrier that carries and rotates a toner image;
A transfer portion for transferring a toner image from the image carrier to transfer paper;
A transfer posture correcting unit that corrects the transfer posture of the transfer paper for receiving the toner image, and matches the timing and movement of the toner image that rotates together with the image carrier, and conveys the corrected transfer paper to the transfer unit; Have
The transfer posture correction unit includes a registration roller that conveys the transfer paper, a roller unit that holds and rotates the registration roller, a detection unit that detects a position of the transfer paper conveyed by the registration roller, and the detection And a controller that rotates the roller unit based on the detection data to correct the bending of the transfer paper, and further moves the registration roller on the roller unit to correct the transfer position of the transfer paper. An image forming apparatus.
2.
The roller unit has a substrate configured to be rotatable and a substrate rotating unit that rotates the substrate in contact with one end of the substrate, and rotates the registration roller and the roller that rotates the registration roller on the substrate. 2. An image forming apparatus according to 1, further comprising a moving unit that moves the registration roller in a rotation axis direction.
3.
2. The image forming apparatus according to 1, wherein the detection unit is a line sensor that can detect the position of the transfer paper in a direction orthogonal to the transfer direction of the transfer paper.
4).
4. The image forming apparatus according to 3, wherein the line sensor is provided on an exit side of the registration roller.
5.
The detection unit measures the first position and the second position on the side end along the transfer paper conveyance direction at a predetermined time interval Δt, and the control unit bends the transfer paper from the two measured values. The image forming apparatus according to 1, wherein an amount is calculated, and the roller unit is rotated based on the calculated amount of bending.
6).
In the case where a plurality of transfer paper conveyance speeds are provided, the control unit detects the first and second positions when the detection unit measures the first position and the second position of the transfer paper at a predetermined time interval Δt. 6. The predetermined time interval Δt is changed according to a transfer paper transport speed so that a measurement distance interval between the position and the second position is constant regardless of the transfer paper transport speed. Image forming apparatus.
7).
7. The image forming apparatus according to claim 6, wherein the control unit changes a transfer paper conveyance speed according to the transfer paper size, and changes the predetermined time interval Δt according to the transfer paper size.
8).
The control unit includes a plurality of data of the predetermined time intervals Δt corresponding to a plurality of transfer paper transport speeds and a plurality of transfer paper transport speeds, or a plurality of transfer paper sizes and a plurality of transfer paper sizes. The image forming apparatus according to claim 7, further comprising a memory that stores at least one of the plurality of data of the predetermined time interval Δt corresponding to each of the plurality of data.
9.
6. The image forming apparatus according to 5, wherein the control unit controls the detection unit to detect a first position of the transfer paper after a predetermined time t0 after the detection unit detects the leading edge of the transfer paper. .
10.
9. The image forming apparatus according to 8, wherein the control unit changes a transfer paper conveyance speed according to a transfer paper size, and changes the predetermined time t0 according to the transfer paper size.
11.
The control unit calculates the amount of bending of the transfer paper a plurality of times until the leading edge of the transfer paper conveyed by the registration roller reaches the transfer position of the transfer unit, and performs the bending of the transfer paper a plurality of times. 2. The image forming apparatus according to 1, wherein correction is performed.
12
The control unit calculates a deviation between the transfer paper position and the transfer reference position based on the detection data of the detection unit, and moves the registration roller on the roller unit based on the calculated deviation to transfer the transfer paper. 2. The image forming apparatus according to 1, wherein the transfer position is corrected.
13.
The control unit has a paper feed roller that transports the transfer paper to the registration roller of the transfer posture correction unit, and the control unit stops the registration roller while the paper feed roller is transporting the transfer paper, and transfers to the stopped registration roller. 2. The image forming apparatus according to 1, wherein the correction of the transfer paper is preliminarily performed by abutting the leading end of the paper.

  In the present invention, the transfer posture correction unit corrects the bending of the transfer paper by rotating the roller unit based on the detection data by the detection unit, and further corrects the transfer position of the transfer paper by moving the registration roller on the roller unit. By doing so, it is possible to provide an image forming apparatus that is easy to control, can repeatedly correct the bending of the transfer paper, and can form a high-quality image.

  Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. In addition, in each drawing, the thing of the same code | symbol shall show the same thing, and shall be demonstrated in detail suitably with reference to other related drawings.

  The configuration of the image forming apparatus according to the present invention will be described with reference to FIG.

  The image forming apparatus 20 in the embodiment of the present invention is an electrophotographic copying machine.

  Reference numeral 20 denotes an image forming apparatus, and 30 denotes an automatic document feeder (ADF) mounted on the image forming apparatus 20.

  In the image forming apparatus 20, a manual feed tray 2 for supplying a relatively small amount of transfer paper P is provided on the right side surface portion of the housing 1, and a paper discharge tray 3 is provided on the left side surface portion.

  On the paper discharge tray 3, a transfer paper P supplied from a paper feed cassette 12 or a manual tray 2 described later and having an image formed thereon is discharged and stacked.

  The transfer paper P includes normal transfer paper made of plain paper and special transfer paper made of OHP sheet or the like, but in this embodiment, normal transfer made of plain paper is used unless otherwise specified. Paper (also simply referred to as transfer paper P) is used.

  A plurality of rollers (also referred to as casters) 4 for enabling the image forming apparatus 20 to move are provided on the bottom surface of the housing 1.

  A control panel CP as a display unit and an operation input unit for operating the image forming apparatus 20 is provided in the upper part of the front surface of the housing 1.

  The control panel CP includes a liquid crystal display device as the display means DP, or a touch panel type liquid crystal display device in which a touch panel or the like is incorporated in the liquid crystal display device.

  In addition, a numerical value or the like is input for inputting various image forming conditions such as whether the copy (printing, printing, or printing) is color or black and white, and control-related information such as the number of copies and the number of copies. An operation input means including a keyboard KB and a start button (also referred to as a copy button) SK for executing a series of image forming operations such as copying is provided as an input device.

  In particular, the touch panel type display means DP allows the user to input information such as selection and setting of information displayed on the display unit when the user touches a pattern such as a button on which a number, character, symbol, or the like is displayed on the display unit. It can be done.

  For example, regarding various operation modes related to image formation such as single-sided mode and double-sided mode, it also serves as input means for items that require selection setting.

  The single-side mode refers to a single-sided copy mode in which an image is formed by transferring a toner image formed by the image forming unit 11 to only one side of the transfer paper P based on image data. Incidentally, the duplex mode refers to a duplex copy mode in which images are formed on both sides of a transfer sheet.

  Inside the housing 1 are provided a control means EC, a transfer separating means 8, a fixing device 10, an image forming means 11, an image reading means 13, a paper supply / discharge means 14, an intermediate transfer member 16, and the like.

  The control means EC, also called a control circuit, is a means for controlling all operations of the image forming apparatus 20, and is composed of an electric circuit composed of a CPU (Central Processing Unit) or the like. Based on a control program or control data stored in advance in the CPU, all means constituting the image forming apparatus 20 are driven and controlled.

  Further, when an accessory device such as the ADF 30 is connected to the image forming apparatus 20, similarly, the control unit EC operates smoothly as a system of the image forming apparatus 20 in cooperation with these accessory devices. The drive is controlled to

  Further, even when connected to a personal computer or other information equipment via a LAN (local area network), etc., the control means EC cooperates with these equipment to provide information necessary for operation. It shall be possible to smoothly control drive without any problems including memory and transfer.

  The image forming unit 11 is a unit for forming an image based on image information. This embodiment is called a tandem system, and an image forming unit 11Y that forms a yellow (Y) image, an image forming unit 11M that forms a magenta (M) image, and an image forming unit that forms a cyan (C) image. 11C, image forming units 11K that form black (K) images are arranged in the image forming apparatus 20 in order from the top to the bottom in the vertical direction.

  Since the image forming units 11Y, 11M, 11C, and 11K constituting the image forming unit 11 perform the same operation except for the color of the toner used, the image forming unit 11Y that forms a yellow (Y) image is used here. Detailed description will be made with only the symbols attached.

  For example, the image forming unit 11Y uniformly includes a photosensitive drum (also referred to as a photosensitive member) 5Y and a photosensitive drum 5Y that rotate in an image forming direction (for example, counterclockwise) set in advance by a driving source such as a motor. The charging means 6Y for charging the exposure light EY, which is converted into a signal based on image information (also referred to as image data) and forms an electrostatic latent image on the photosensitive drum 5Y, and the electrostatic latent image formed on the photosensitive drum 5Y Developing means 7Y that visualizes the toner image, transfer separation means 8Y (also referred to as primary transfer means) that transfers the toner image formed on the photosensitive drum 5Y to the intermediate transfer body 16, and the toner image that is the intermediate transfer body 16. After the transfer, the cleaning means 9Y and the like for scraping off the toner and paper dust remaining on the photosensitive drum 5Y.

  The toner images formed by the respective image forming units are sequentially transferred and superimposed on, for example, a belt-like intermediate transfer body 16 (also referred to as a transfer belt) that rotates clockwise.

  The toner images of the respective colors transferred to the intermediate transfer body 16 are opposite in polarity to the polarity of the toner image by the transfer roller 8 as a transfer unit 8 (also referred to as a transfer unit, transfer separation unit, or simply transfer unit). Is applied to the transfer paper P, and is transferred from the intermediate transfer body 16 to the transfer paper P by electrostatic force.

  The transfer paper P onto which the toner image has been transferred is melt-fixed (fixed) in the process of passing through the fixing device 10, and the transfer paper P on which the color image with Y, M, C, and K toners is formed Thereafter, the paper is discharged to the paper discharge tray 3.

  As in the present embodiment, an image forming apparatus using an intermediate transfer member can superimpose toner images formed by the respective image forming units on the intermediate transfer member. Widely used. The intermediate transfer member is not limited to the transfer belt as long as it can transfer the toner image formed by the image forming unit, and may be a photosensitive drum. These transfer belts and photosensitive drums are defined as image carriers.

  In this embodiment, the transfer separating unit 8 is configured as a transfer roller 8 by a contact transfer method, and is disposed at a transfer position facing the intermediate transfer member 16, and a toner image formed on the intermediate transfer member 16. Is a means for applying a charge having a polarity opposite to the polarity of the toner image to the transfer paper P and transferring it with electrostatic force.

  Note that 8Y, 8M, 8C, and 8K (only 8Y is given a symbol) have the same configuration, and transfer the toner images formed by the image forming units 11Y, 11M, 11C, and 11K to the intermediate transfer member 16. It is a transfer separation means used.

  The cleaning unit 9 removes toner, paper dust, and the like remaining on the intermediate transfer member 16, and is configured by a blade, a brush roller, or the like. 9Y, 9M, 9C, and 9K (symbols are attached only to 9Y) are cleaning units that are used to clean the photosensitive drums of the image forming units 11Y, 11M, 11C, and 11K with the same configuration.

  Although not shown, the fixing device 10 includes, for example, a heating roller including a heater, a pressure roller, and the like. The toner image transferred to the transfer paper P is heated (for example, about 200 ° C.), pressure, and the like. It is a means for melting and fixing (fixing).

  The image reading unit 13 includes a reading optical system including a light source LT, a mirror group MR, an imaging lens LZ, and the like, and a reading device ES including an electric circuit including a CCD (solid-state imaging device).

  The reading device ES reads image information of a document placed on a platen glass (not shown) provided on the upper portion of the housing 1 or a document conveyed to a reading position by the automatic document feeder 30 and digitally reads the image information. The image data is stored in a storage means provided in the control means EC.

  Further, when the document conveyed by the ADF 30 is read by the image reading unit 13, the light source LT irradiates the document conveyed to the reading position, and the reflected light from the document is reflected by the imaging lens LZ via the mirror group MR. An image is formed on the CCD surface of the reading device ES, and image information output from the CCD is stored as image data.

  The paper supply / discharge means 14 is configured as a paper supply cassette 12 and a paper supply / discharge conveyance device (transfer paper conveyance means) comprising a motor as a drive source and a plurality of rollers.

  The paper feed cassette 12 includes, for example, a cassette 12a that stores special transfer paper, a cassette 12b that stores plain paper, and the like.

  The paper supply / discharge conveyance device as the paper supply / discharge means 14 selects a special transfer paper or plain paper according to an instruction from the control means EC, and then rotates a motor as a drive source to thereby provide a plurality of roller groups, etc. , The transfer sheet selected from the sheet cassette 12 is fed toward the intermediate transfer body 16 and the toner image is melted and fixed (fixed) by the fixing device 10 to form an image. The paper is conveyed to the paper tray 3. The paper supply / discharge conveyance device has a roller R2 (registration roller) for conveying the transfer paper to the transfer roller 8 in synchronization with the movement and timing of the toner image carried on the intermediate transfer body 16, and this roller R2 The transfer posture correction unit of the present invention is configured.

  The intermediate transfer member 16 is also called a transfer belt, and is composed of a belt-like object stretched around a plurality of rollers. In the present embodiment, the intermediate transfer member 16 is rotated clockwise by a drive source such as a motor (not shown). It is designed to rotate.

  When using an intermediate transfer member, the electrical characteristics (volume resistivity, surface resistivity, etc.), thickness, structure (for example, the number of layers such as single layer, two layers, three layers, etc.), material, material, etc. It is desirable to select and use various appropriate ones according to image forming conditions.

  The entire ADF 30 is covered with an ADF casing 31, and the ADF 30 is provided with a document table 32 and a paper discharge unit 33 outside the ADF casing 31.

  On the document placement table 32, a plurality of documents WP with the document surface (front surface) of the first page at the top is placed. The placed document WP is conveyed to a reading position by a document conveying device including a plurality of rollers and the like, read by a reading device ES, and discharged to a paper discharge unit 33.

  The document conveying device is operated in conjunction with the control means EC of the image forming apparatus 20 by a drive control circuit (not shown).

  Here, the image forming operation in the present embodiment will be briefly described.

  In the single-side mode in which an image is formed on one side of the transfer paper P, the image data read by the image reading means 13 shown in FIG. 1 or stored in the storage means of the control circuit EC described later by a communication network such as a LAN. Based on the image data, a yellow (Y) toner image is formed and transferred to the intermediate transfer member 16 by the operation of the well-known electrophotographic image forming unit 11Y.

  Similarly, magenta (M), cyan (C), and black (K) toner images are formed by the image forming units 11M, 11C, and 11K, and transferred to the intermediate transfer member 16.

  On the other hand, one sheet of transfer paper P taken out from the paper feed cassette 12 is transferred onto the transfer paper P at the position of the roller R2 provided in the transport path near the intermediate transfer body 16 from the X1 direction by the paper supply / discharge means 14. The leading edge of the transfer paper abuts against the roller R2 to form a loop and temporarily stop, whereby the bending of the transfer paper is preliminarily corrected, and further, the transfer paper bend and transfer position are corrected by a transfer posture correction unit described later. Is finally corrected with high accuracy, the transfer paper P is conveyed toward the intermediate transfer body 16 by the roller R2 at an appropriate timing.

  When the transfer sheet P approaches the intermediate transfer body 16, the transfer roller 8 operates in a direction in contact with the intermediate transfer body 16, and thereafter, at the transfer position where the intermediate transfer body 16 and the transfer roller 8 face each other, the intermediate transfer body 16. When the transfer paper P passes between the transfer roller 8 and the transfer roller 8, a charge having a polarity opposite to the polarity of the toner image is applied, and the electrostatic force causes the toner image on the intermediate transfer member 16 to be transferred to the transfer paper P. Is transferred to the second surface (surface).

  The transfer paper P onto which the toner image has been transferred passes through the fixing device 10 and is fixed by melting and fixing the toner image, conveyed in the X4 direction, and discharged onto the paper discharge tray 3 shown in FIG. When an image is formed on one side of a plurality of transfer sheets P, this operation is repeated.

  When performing double-sided copying (double-sided mode), first, the control unit EC performs an operation of forming an image on one side of the transfer paper P described above.

  Then, the transfer paper P on which an image is formed on one side passes through the fixing device 10 and is then conveyed in the direction of the paper discharge tray 3 (arrow X4 direction), and the rear end of the transfer paper P passes through a pair of rollers HR. The control means EC stops the rotation of the roller HR just before the operation.

  Subsequently, the roller HR is rotated in the reverse direction to be conveyed in the X3 direction, the front and back of the transfer paper are reversed, and conveyed to the conveyance path WA through the conveyance paths C and D.

  The transfer paper P that has entered the transport path WA again stops at the position of the roller R2 and is transported toward the intermediate transfer body 16 at an appropriate timing, as in the single-side mode in which an image is formed on one side.

  The transfer paper conveyed in the direction of the intermediate transfer body 16 has the toner image formed by the image forming means 11 on the first surface (back surface) transferred from the intermediate transfer body 16 to the transfer paper P by the transfer roller 8 in the same manner as single-sided copying. Is transcribed.

  Then, after passing through the fixing device 10, the transfer sheet P is conveyed in the X4 direction toward the sheet discharge tray 3 and discharged without causing the roller HR to stop. Finish copying. Therefore, this process is repeated when a plurality of double-sided copies are made.

  There are two methods for discharging transfer paper in single-sided mode: face-up discharge that discharges the print surface upward (front side) and face-down discharge that discharges the print surface downward (back side). The conveyance path WB is a conveyance path when performing face-down paper discharge.

  In general, the transfer paper transport path is often provided with a guide member for appropriately transporting the transfer paper, a switching means for switching the transport path, etc., but in the embodiment of the present invention, In order to simplify the explanation, illustration and explanation of these members are omitted.

  Next, the transfer posture correcting unit for transfer paper according to the present invention will be described with reference to FIG.

  2A is a partially enlarged view of the periphery of the conveyance path from the roller R2 to the transfer roller 8 in FIG. FIG. 2B is a schematic view of the transfer posture correcting portion of the transfer paper viewed from the arrow Z direction in FIG. In addition, the thing with the same code | symbol as FIG. 1 shall show the same member.

  In FIG. 2B, BP is a substrate for constituting the roller unit of the transfer posture correction unit. The substrate BP is provided with bearings BP1 and BP2, and the bearings BP1 and BP2 have a slightly longer shaft R21 in which the amount of movement is considered so that the roller R2 can be moved in a direction perpendicular to the transfer sheet conveyance direction. The gear G3 is fixed and a slightly longer shaft R22 in consideration of the moving amount is fitted.

  In addition, the substrate BP is provided with a motor M1 that applies a driving force to sandwich the transfer paper and transport it in the transport direction. The gear G1 fixed to the motor M1 meshes with the gear G3 via the intermediate gear G2, and rotates the roller R2.

  The roller R2 is configured as a pair of rollers as shown in FIG. 2A, but a mechanism for rotating the pair of rollers to convey the transfer paper is a known gear mechanism, belt mechanism, or the like. However, in order to simplify the description, the illustration of the configuration as a roller pair is omitted.

  M2 is a motor for moving the roller R2 in a direction orthogonal to the transfer paper conveyance direction, and is provided with a screw gear GS. The screw gear GS and the gear G3 provided on the shaft R22 of the roller R2 are connected to a connecting plate BR. It is connected.

  The connecting plate BR is configured so that one end thereof is engaged with a groove G3V provided in the gear G3 and the other end is engaged with the screw gear GS. When the motor M2 rotates, the roller R2 is moved leftward or rightward depending on the rotation direction. It can be moved linearly in the direction.

  Further, a gear GBP is partially provided at the left end portion of the substrate BP, and the gear GBP is meshed with a gear G4 rotated by the motor M3, so that the roller unit is rotated together with the substrate BP by the rotation direction of the motor M3. By turning clockwise or counterclockwise around the center BPC, the bending of the transfer paper can be corrected.

  Similarly, in the following description, it is particularly assumed that the substrate BP is rotated in a clockwise or counterclockwise direction in a plane around the rotation center BPC for bending correction.

  S is a position measuring means, for example, a sensor (line sensor) in which a plurality of fine image sensors are linearly provided in a direction perpendicular to the transfer sheet conveyance direction.

  Here, the bending correction operation of the transfer paper will be briefly described. The transfer paper is transported from the paper feed cassette 12 to the stopped roller R2 by the paper supply / discharge means 14. The leading edge of the transfer paper that has reached the roller R2 is once abutted against the roller R2 to form a loop, so that a large bend is first corrected.

  Subsequently, when the roller R2 is rotated and the transfer sheet is conveyed toward the transfer roller 8 at an appropriate timing, the sensor S is either one of the transfer sheets along the transfer direction of the transfer sheet that has passed through the roller R2. In FIG. 2B, the first position A point on the left end side of the transfer paper and the second position B point after a predetermined time interval t (seconds) are measured. The position information of the points A and B is acquired in consideration of the conveyance speed V, and the bending angle θ and the like are calculated.

  Then, as shown in FIG. 2B, when the transfer sheet is a quadrangle indicated by a two-dot chain line connecting four points C, D, E, and F, it is skewed (bent) at an angle θ. When calculated, the motor M3 is operated so that the roller unit rotates counterclockwise about the rotation center BPC by θ degrees with the transfer paper sandwiched, and the transfer paper is C1, D1, E1, Correction is made so as to form a square indicated by a broken line connecting the four points of F1.

  At this time, when the bending is corrected by rotating the roller unit by θ degrees around the rotation center BPC from the position information obtained by measuring the two points A and B by the sensor S, for example, the preset transfer reference position BL and , The amount of deviation ΔX in which the straight line connecting F1 and E1 deviates in the direction perpendicular to the transport direction is calculated, and when the transfer position of the transfer paper is shifted, the motor N2 is rotated in accordance with the amount of deviation, The transfer position of the transfer paper can be corrected on the roller unit.

  Next, a method for calculating the amount of bending of the transfer paper will be described with reference to FIG.

  3A shows a method for calculating the amount of bending ΔY of the transfer paper by the sensor S, and FIG. 3B shows measurement points at the sensor S and the left end (solid line) of the transfer paper. The first position A point and the second position B point which is a measurement point at the left end (broken line) after a predetermined time interval t (seconds) are shown.

  That is, FIG. 3B shows that the point A measured by the sensor S advances to the A1 position after Δt seconds from the start of the measurement by the transfer paper being conveyed, and is located behind the sensor S. It shows that the point B reaches the B1 position after Δt seconds and is measured by the sensor S. In addition, SL shown with a dashed-dotted line is a line which shows the measurement reference position assumed to show the measurement reference position when measuring two points, A point and B point, by the sensor S.

  In FIG. 3A, the square transfer paper indicated by the solid line connecting points C, D, E, and F is the position of the square transfer paper indicated by the broken line connecting points C1, D1, E1, and F1 after Δt seconds. Shall be transported to Then, assuming that the straight line DE and the straight line CF are set equal to the dimension X, and the straight line CD and the straight line EF are set equal to the dimension Y, it is assumed that the transfer paper of vertical and horizontal Y × X dimensions is conveyed.

  When the transfer sheet is conveyed at the conveyance speed V, as described with reference to FIG. 3B, for example, the point A is measured on the measurement position reference line SL of the sensor S, and the point B is measured after Δt seconds. If so, the distance T from which the point A is moved to the point A1 and the point B is moved to the point B1 is obtained by T = V × Δt.

  Moreover, the distance on the measurement position reference line SL of the sensor S between the point A and the point B (point B1) is, for example, the distance between the detection positions of the points A and B in a plurality of image sensors constituting the sensor S. As | A−B |.

  Therefore, the bending angle θ of the transfer paper can be obtained by θ = tan −1 (| A−B | / (V × Δt)).

  Further, at this time, when the length in the transport direction when the transfer paper of vertical and horizontal Y × X dimensions is bent at the bending angle θ is Ly, and the length in the direction orthogonal to the transport direction is Lx, the amount of bending in the transport direction ΔY is ΔY = Lx × tan θ.

  Further, since Lx = X × cos θ, ΔY = X × sin θ is also obtained.

  Further, by determining from the position of the image sensor that has detected the point B in the plurality of image sensors whether the point B is on the left side or the right side of the point A with respect to the point A, the turning direction is to the right. It is further determined whether the turn is left.

  Therefore, in the present embodiment, the transfer posture correcting unit shown in FIG. 2B performs the motor in the direction of correcting the determined bending angle θ or the bending amount ΔY and the determined bending direction. M3 is rotated, and the substrate BP is rotated counterclockwise with respect to the bending of the transfer paper shown in FIG. 3, and the bending correction is performed with the transfer paper held between the rollers R2 on the roller unit.

  In the present embodiment, when the substrate BP is turned counterclockwise, as shown in FIG. 2B, the transfer reference position BL and the right edge EF of the transfer paper are shifted by ΔX. In the same manner, the amount of deviation ΔX from the transfer reference position BL is calculated by calculating the corrected position of the corners (C, D, E, F) of the transfer paper with respect to the rotation center. By rotating the motor M2 in accordance with the amount of deviation ΔX and moving the roller R2 in the axial direction (direction perpendicular to the transport direction), the transfer paper is held between the roller R2 and the roller unit on the roller unit. The amount of deviation ΔX from the reference position BL can be corrected.

  The sensor S detects, for example, whether or not the leading edge of the transfer paper has passed the measurement reference position SL of the sensor S, and when detecting that it has passed, the timer (not shown) of the control circuit EC. In order to correct the bending of the transfer paper, the timer counter uses the measurement start timing t0 for measuring two points at the end of the transfer paper and the elapsed time with respect to the two measurement time intervals Δt as the count value. Ta is actuated, or for a preset time t2 until the leading edge of the transfer paper passes the measurement reference position SL of the sensor S and the leading edge of the transfer paper reaches the transfer position of the transfer roller. A timer counter Tb having the elapsed time as a count value is operated.

  Therefore, the control circuit EC in the present embodiment operates the timer when the leading edge of the transfer paper passes the measurement reference position SL of the sensor S, and the first point of the transfer paper after the elapsed time ta by the timer counter Ta is t0 hours. Is measured, and the second point is measured after time t0 from time t0, and the skew correction of the transfer paper is performed based on the measurement result.

  On the other hand, the elapsed time tb until the transfer paper reaches the transfer position of the transfer roller 8 is counted by the timer counter Tb, and the leading edge of the transfer paper is transferred while the elapsed time tb does not exceed the preset time t2. It is determined that the transfer position of the roller has not been reached, and it is possible to repeatedly correct the skew of the transfer paper.

  In this embodiment, as shown in FIG. 3B, the point A measured by the sensor S advances to the A1 position after Δt seconds as the transfer paper is conveyed, and the sensor S This shows that the point B located rearward reaches the B1 position after Δt seconds and is measured by the sensor S. In the image forming apparatus, for example, the transfer paper corresponds to the size of the transfer paper. In some cases, a plurality of transport speeds are provided.

  In the present embodiment, when the position is measured, the time interval between the points A and B is set to Δt seconds. However, when the conveyance speed changes according to the transfer paper size, The distance from point B varies for each transfer paper size. Thus, when the distance interval changes for each transfer paper size, the detection accuracy may change depending on, for example, the arrangement of a plurality of minute image sensors in a direction orthogonal to the transfer paper transport direction of the sensor S. Therefore, when the conveyance speed changes depending on the transfer paper size, it is desirable that the distance between the points A and B is constant so that the detection accuracy does not change.

  Therefore, in the present embodiment, the control circuit EC stores data of time intervals Δt for a plurality of transport speeds so that the distance between the points A and B is constant even if the transport speed changes. When the conveyance speed is stored in the means and the conveyance speed is changed, the measurement timing is controlled by reading the time interval Δt corresponding to the conveyance speed to be changed.

  Further, when the size of the transfer paper changes, the positions of the points A and B on the side edge of the transfer paper to be detected by the sensor S at the edge of the transfer paper shown in FIG. 3B change. Therefore, it is necessary to lengthen the length of the image sensor in the direction orthogonal to the transfer sheet conveyance direction of the sensor S for measuring the points A and B so as to correspond from the small transfer sheet to the large transfer sheet. There is. In particular, when the conveyance speed is low, it is necessary to further increase the time t0 for starting the measurement of the point A after the leading edge of the transfer paper has passed the measurement reference position SL of the sensor S. Since the sensor S is composed of a plurality of minute image sensors, the longer the sensor S is, the more image sensors are required, which generally increases the cost.

  Therefore, even when the size of the transfer paper changes, the time t0 for starting the measurement of the point A is changed so that the detection portion (position measurement unit) constituted by the image sensor of the sensor S has the shortest possible length. I am doing so. In other words, when data of time t0 corresponding to a plurality of transfer paper sizes is stored in the storage means and the transfer paper size is changed, the measurement timing is controlled by reading the time t0 corresponding to the transfer size to be changed. Measurement is possible with a position measuring unit of a predetermined length.

  In the present embodiment, two measurement points, point A and point B, have been described. For example, two or more measurement positions are measured in order to improve measurement accuracy in consideration of deformation of the transfer paper. You may make it do.

  Here, the circuit configuration of the image forming apparatus according to the present invention will be described with reference to FIG. In the present embodiment, the case where the image forming apparatus is a copying machine as described above will be described.

  Reference numeral 100 denotes a configuration of various means and circuits of the entire image forming apparatus 20. Reference numeral 110 denotes a CPU that controls the entire image forming apparatus, and stores various mode programs for controlling the image forming apparatus 20, data necessary for executing the programs, and the like.

  An information control circuit 120, an image processing circuit 140, a drive control circuit 150, a power supply circuit 400, and the like are connected to the CPU 110. These circuits constitute the control means EC shown in FIG. 1 so that the entire image forming apparatus 20 can be controlled.

  The information control circuit 120 is connected to the external information device 500 via an interface (I / F) 130 according to an instruction from the CPU 110 to set image information such as characters and images, density and magnification necessary for image formation, and the like. Information is input and stored in the storage means 160. The setting information stored in the storage unit 160 is output to the image processing circuit 140, the drive control circuit 150, the display unit 300, or the like.

  Further, the information control circuit 120 includes circuits and various means including the image processing circuit 140, the drive control circuit 150, and the like in addition to JOB information including image information and setting information input from the external information device 500 via the information network. For example, various information input by the operation input unit 200, information indicating an operation state output during operation of the various units of the apparatus, and the like related to instruction information necessary for the operation of the image forming apparatus are determined. It has a function of smoothly and appropriately transmitting information to each circuit and various means of the image forming apparatus so as not to hinder.

  The external information device 500 is mainly a computer or an Internet server connected by an information network, but in some cases, other image forming apparatuses on a local area network (LAN), a digital camera, An information device such as a measurement device capable of outputting the measured information is assumed.

  In the present embodiment, the information control circuit 120 corrects the bending of the transfer paper from the position information of the two points of the transfer paper measured by the sensor S, which is a sensor means, in order to correct the bending of the transfer paper. A bending amount ΔY and the like are calculated, and it is determined whether or not the transfer sheet is bent based on the calculated result. Further, a deviation amount ΔX from the transfer reference position of the transfer paper is calculated from the position information of the two points on the transfer paper. Then, based on the bending angle θ calculated by the information control circuit 120, the bending amount ΔY, the deviation amount ΔX, and the like, the drive control circuit 150 (to be described later) operates the transfer posture correction unit having the roller R2, thereby correcting the bending of the transfer paper. Deviation correction is executed.

  Also, for example, when the sensor S detects the leading edge of the transfer paper, a timer (not shown) is activated, and timer counters Ta and Tb are activated. Then, the first measurement time t0 for measuring two points on the transfer paper by the timer counter Ta and the elapsed time ta for matching the measurement timing of the sensor means S with the time interval t from the first measurement time t0. Count.

  Further, in order to repeatedly execute the transfer posture correction of the transfer paper until the transfer paper reaches the transfer position of the transfer roller 8, the transfer paper front end is taken into consideration in consideration of the operation such as the transfer posture correction of the transfer paper. The time t2 that is predicted to reach the transfer position of the transfer roller 8 is calculated, and the timer counter Tb counts the elapsed time tb with respect to the preset time t2 to execute the transfer paper transfer posture correction operation. It has a function to determine whether or not to make it.

  In addition, when the transfer speed of the image forming apparatus and the transfer paper size of the transfer paper to be used are changed, the information is stored in the storage unit 160 based on information on the changed transfer speed and transfer paper size of the transfer paper. It has a function of controlling the measurement timing by reading the time interval Δt, that is, the time interval Δt between the points A and B when the sensor S measures the position.

  The interface (I / F) 130 is information exchange means, and is configured to be connected to the above-described computer, other image forming apparatuses, and external information equipment 500 such as an Internet server via various networks.

  The operation input unit 200 is an input device provided on the control panel CP of the image forming apparatus 20. The above-described liquid crystal display device DP, keyboard KB, start button SK, etc., which are touch panel type display means, are assumed.

  For example, by operating the keyboard KB, the number and type of transfer paper output (for example, index paper, thick paper, plain paper, thin paper, recycled paper, OHP sheet, etc.), enlargement / reduction magnification, output image density, etc. Setting information can be entered.

  In some cases, the operation input unit 200 sets various operation modes of the image forming apparatus 20, such as a color mode, a monochrome mode, a single-side mode, and a double-side mode, which are selected and set when performing a copy operation. It becomes an input means for doing.

  In particular, in this embodiment, the transfer posture correction mode of the transfer paper can be selected and set by operating the touch panel type liquid crystal display device DP on the control panel CP of the operation input means 200. .

  For example, when the mode change is selected on the initial menu screen and the transfer paper transfer posture correction mode is selected, the correction condition setting button is displayed on the liquid crystal display device DP, and the correction condition setting button is touched with a finger. Press to display the correction menu screen that displays the correction conditions. If you want to repeat corrections, press the Repeat Correction button displayed on the Correction Menu screen to select the Repeat Correction mode, and press the Finish button after completing the selection settings. Return to the menu screen. If the correction condition is not newly selected and set even if the correction menu screen is displayed, the initial menu screen is similarly returned by pressing the completion button.

  The display means 300 is configured by the above-described liquid crystal display device, or a display device DP in which a touch panel or the like is incorporated in a liquid crystal display unit.

  The display unit 300 includes an operation procedure when inputting information with the operation input unit 200, a list display of various information (also referred to as a menu), a display of information stored in the storage unit 160, and an operation of the image forming apparatus 20. An internal status display, warning display, etc. are displayed.

  In response to an instruction from the CPU 110, the image processing circuit 140 cooperates with the information control circuit 120 to receive the image information of the original read by the image reading unit 13 and the image information input to the image forming apparatus via the information network described above. For example, when the image forming unit 11 forms an image based on the image data stored in the storage unit 160, the image forming unit 11 stores the image data in the storage unit 160 by compressing or expanding the image data. This is a circuit for converting data, signals, etc. suitable for the image forming method of the means 11.

  The drive control circuit 150 cooperates with the image processing circuit 140 in response to an instruction from the CPU 110 to move the transfer unit 8, the fixing unit 10, the image forming unit 11, the image reading unit 13, the paper supply / discharge unit 14, the ADF 30, and the like. This is a circuit for operating at an appropriate timing to perform an image forming operation based on a preset operation mode.

  In particular, in the present embodiment, the motors M1, M2, and the like that constitute the transfer posture correction unit based on the bending angle θ of the transfer paper, the bending amount ΔY, the deviation amount ΔX, and the like calculated by the information control circuit 120 according to an instruction from the CPU 110. By appropriately operating M3 according to a preset correction operation program and rotating the roller R2 about the rotation center BPC, the bending of the transfer paper and the transfer position deviation are corrected.

  As described above, the sensor S is configured by linearly providing a plurality of fine image sensors in the axial direction of the roller R2, which is orthogonal to the transfer paper conveyance direction, and corrects the bending of the transfer paper according to the present invention. In order to perform the above, the first position (point A) and the second of the side edge of one of the transfer sheets parallel to the transport direction of the transferred transfer sheet on the measurement position reference line SL of the sensor S Is measured at a predetermined time interval Δt. Note that the position information of the two points measured by the sensor S is stored in the storage unit 160 according to an instruction from the information control circuit 120.

  The storage unit 160 stores JOB information including image data necessary for forming an image, setting conditions for controlling the image forming apparatus 20, JOB data related to the jOB information, programs for various setting modes, and the like. Information is memorized.

  Further, in the present embodiment, the storage unit 160 stores information such as position information of two points measured by the sensor S and information such as the bending angle θ of the transfer sheet, the bending amount ΔY, and the deviation amount ΔX calculated by the information control circuit 120. Alternatively, the motor driving time and driving for appropriately operating the motors M1, M2, and M3 constituting the transfer posture correcting unit shown in FIG. 2 in accordance with the bending angle θ of the transfer paper, the bending amount ΔY, the deviation amount ΔX, and the like. Calculation formulas and data such as timing are also stored.

  The storage unit 160 also stores time intervals Δt and A points between the points A and B when the sensor S measures the position based on a plurality of conveyance speeds of the image forming apparatus and a plurality of transfer paper sizes used. The time t0 for starting the measurement is stored.

  Therefore, the information control circuit 120 measures two points by the sensor S shown in FIG. 2 provided in the paper supply / discharge means 14 based on these calculation formulas and data, and based on the measurement result, the amount of bending of the transfer paper And a deviation amount ΔX is calculated. On the other hand, the drive control circuit 150 rotates the roller unit of the transfer posture correction unit around the rotation center BPC based on the bending amount and deviation amount ΔX of the transfer paper calculated by the information control circuit 120 to transfer the transfer paper. Is corrected, and the roller R2 on the roller unit is shifted in the axial direction to correct the shift amount, thereby correcting the transfer posture of the transfer paper.

  In the present embodiment, in order to repeatedly correct the transfer posture of the transfer paper, when the sensor S repeatedly performs measurement, information based on the position information of the two points repeatedly measured and information based on the measurement result. Information such as the bending angle θ of the transfer sheet and the bending amount ΔY deviation amount ΔX calculated by the control circuit 120 is stored in the storage unit 160 until a series of JOBs is completed.

  When a power switch (not shown) is turned on by a user's operation, the power supply circuit 400 is appropriately energized from the power source to the entire image forming apparatus. When the power switch is shut off, the power supply is shut off. It has become so.

  Even if the power switch is turned on (ON), for example, in the power saving mode in which the image forming apparatus is in a standby state, the power supply circuit 400 temporarily instructs the image forming apparatus according to an instruction from the CPU 110. It is possible to continue energization only necessary for storing the stored contents of a typical memory and to shut off other energization such as a heater of a fixing device.

  Further, even when the power is turned off (OFF) by the power switch, the power supply circuit 400 does not cut off all the power as in the power saving mode or the like for setting the image forming apparatus in the standby state. Energization necessary for the operation of the CPU 110 and the like is performed, and a power switch is turned on (ON) or image information is input via a LAN so that an image forming operation can be started quickly. Anyway.

  Next, the procedure for correcting the transfer posture of the transfer paper will be described with reference to the flowchart of FIG. In order to simplify the explanation, the image forming apparatus is assumed to be a copying machine as a precondition. Further, the conveyance speed and the transfer paper are not changed, and the time interval Δt when the sensor S measures two points is constant.

  Note that this control procedure is an example of control based on the present embodiment, and is not limited to this procedure.

(ST1)
This is a step of determining whether or not the roller R2 is rotating. That is, since the transfer posture correction of the transfer paper in the present embodiment is performed on the transfer paper in the transport path from the roller R2 to the transfer roller 8, when the roller R2 is not rotating, the roller Since the transfer paper is not conveyed by R2, the transfer paper posture correction operation is not performed in this case.

  Accordingly, when it is determined that the roller R2 is rotating, the process proceeds to ST2, and when it is determined that the roller R2 is not rotating, the process proceeds to ST15.

  Whether or not the roller R2 is rotating is determined by, for example, a signal for controlling the operation of the motor M1 shown in FIG. 2B from the drive control circuit 150 to the transfer posture correction unit of the paper feeding unit 14. Can be determined by the information control circuit 120 detecting whether or not the state is being output.

(ST2)
This is a step of starting a timer of the control circuit EC. That is, the transfer paper is conveyed in the direction of the transfer roller 8 by the rotating roller R2, and for example, when the sensor S detects the leading edge of the transfer paper, the information control circuit 120 activates the timer and proceeds to ST3.

  In the present embodiment, when the timer is activated, whether the timer counter Ta that counts the time for controlling the measurement timing by the sensor S and the leading edge of the transfer paper have reached the transfer position of the transfer roller 8 or not. A timer counter Tb for counting the time for determining whether or not is activated.

(ST3)
In this step, it is determined whether tb is smaller than t2. That is, it is a step of determining whether or not the leading edge of the transfer paper has reached the transfer position of the transfer roller.

  t2 is the time from when the sensor S detects the leading edge of the transfer paper until the leading edge of the transfer paper advances to the transfer position of the transfer roller 8, taking into consideration the transfer paper conveyance speed and the correction operation time in advance. It is the set time.

  tb is an elapsed time as a count value by the timer counter Tb that starts operating when the sensor S detects the leading edge of the transfer paper.

  In order to detect whether or not the leading edge of the transfer paper has reached the transfer position of the transfer roller 8, the information control circuit 120 compares tb and t2.

  Therefore, if tb <t2, it is determined that the leading edge of the transfer paper has not reached the transfer position of the transfer roller 8, and the process proceeds to ST4 to correct the skew of the transfer paper. If tb ≧ t2, Then, it is determined that the leading edge of the transfer paper has reached the transfer position of the transfer roller 8, and the process proceeds to ST14 without correcting the bending of the transfer paper.

(ST4)
In this step, it is determined whether ta = t0. That is, in order to control the measurement timing by the sensor S, the information control circuit 120 measures the first measurement point (point A) by the sensor S when the elapsed time ta, which is the count value by the timer counter Ta, is ta = t0. Like to do.

  Therefore, when ta = t0, that is, when ta is less than t0 or when ta exceeds t0, the process proceeds to ST6, and only when ta = t0, the first measurement point (point A) is measured by the sensor S. In order to do so, the process proceeds to ST5.

(ST5)
This is a step of measuring point A (first measurement point). When the sensor S measures the first measurement point (point A) of the transfer paper shown in FIG. 3, the measurement value is stored in the storage means 160 and the process proceeds to ST6.

(ST6)
In this step, it is determined whether ta = Δt. Accordingly, when ta = Δt is not satisfied, that is, when ta is less than Δt or when ta exceeds Δt, the process proceeds to ST3, and the second measurement point (point B) is measured by the sensor S only when ta = Δt. In order to do so, the process proceeds to ST7.

  However, when the process proceeds to ST7 in order to measure the second measurement point (point B) when ta = Δt, the count value of ta is reset at, for example, ST13. It does not exceed Δt.

(ST7)
This is a step of measuring point B (second measurement point). When the sensor S measures the second measurement point (point B) of the transfer paper shown in FIG. 3, the measurement value is stored in the storage means 160 and the process proceeds to ST8.

(ST8)
This is a step of calculating | A−B |. When position information (also referred to as position data) between point A (first measurement point) and point B (second measurement point) stored in the storage unit 160 is read out and the difference between the position data of the two points is obtained, ST9. Proceed to

(ST9)
This is a step of determining whether or not | A−B | ≠ 0. In other words, when | A−B | = 0, the two points coincide with each other, indicating that there is no bending of the transfer sheet. The process proceeds to ST14 without correcting the bending of the transfer sheet, and when | A−B | ≠ 0. Indicates that there is a bending of the transfer paper, so the process proceeds to ST10 in order to correct the bending of the transfer paper.

(ST10)
This is a step of calculating a bend / deviation correction amount. In other words, as shown in FIG. 3, the bending angle θ of the transfer paper, the bending amount ΔY, the deviation amount ΔX, and the like are calculated from the position data of the two points, and the process proceeds to ST11. Further, it is determined whether the point B is on the left side or the right side of the point A, and the turning direction is also determined in this step.

(ST11)
In this step, it is determined whether tb is smaller than t2. That is, as in ST3, it is a step of determining whether or not the leading edge of the transfer paper has reached the transfer position of the transfer roller.

  That is, when tb ≧ t2, it is determined that the leading edge of the transfer paper has reached the transfer position of the transfer roller 8, and the transfer posture of the transfer paper is not corrected, and the process proceeds to ST14, where tb <t2. Determines that the leading edge of the transfer paper has not reached the transfer position of the transfer roller 8, and proceeds to ST12 to correct the transfer posture of the transfer paper.

(ST12)
This is a step of executing transfer posture correction of the transfer paper. The transfer posture correction shown in FIG. 2 is provided as a part of the paper supply / discharge unit 14 based on the bend angle θ of the transfer sheet, the bend amount ΔY, the shift amount ΔX, and the like calculated by the information control circuit 120 according to an instruction from the CPU 110. The motors M1, M2, and M3 constituting the motor are appropriately operated by, for example, a preset correction operation program, and the roller unit is rotated around the rotation center BPC to correct the bending of the transfer paper. The upper roller R2 is moved in the axial direction to correct ΔX, and the process proceeds to ST13.

(ST13)
This is a step of determining whether or not to end the transfer posture correction operation. In this embodiment, since it is possible to select whether or not to perform the transfer posture correction, for example, when the transfer posture correction is repeatedly set by the operation input unit 200 in advance, tb is set to t2. In order not to exceed, that is, while it is determined that the leading edge of the transfer paper has not reached the transfer position of the transfer roller 8, in order to repeat the transfer posture correction operation of the transfer paper by measuring two points, The count value ta of the timer counter Ta is reset, and the process proceeds to ST3. When the correction operation is not repeatedly performed, that is, when the transfer posture correction operation is completed only by one transfer posture correction operation, the process proceeds to ST14.

(ST14)
This is a step of stopping the operation of the timer. In order to end the transfer posture correction operation, the timer operated to correct the transfer posture of the transfer paper is stopped, or the timer counters Ta and Tb that are operated in relation to the timer are stopped. At the same time, when the process of resetting the counted elapsed times ta and tb is finished, the transfer posture correcting operation is finished.

(ST15)
This is a step of setting the roller R2 to the initial position. When the roller R2 is not rotating, the position of the roller R2 is set to the initial position in advance so that the transfer posture correction operation of the transfer paper can be performed at any time, and the operation of setting the roller R2 to the initial position is finished.

  As described above, the transfer posture correction of the transfer paper according to the present invention has been described based on the present embodiment. As described above, the conveyance path from the roller R2 to the transfer paper reaching the transfer position of the transfer roller. The present invention has an object to provide an image forming apparatus that is easy to control, can repeatedly perform transfer posture correction of transfer paper, and can form a high-quality image. The configuration of the sensor, the configuration of the sensor means, the configuration of the control circuit, and the like are not limited to the present embodiment.

  In particular, in order to determine whether or not the leading edge of the transfer paper has reached the transfer position of the transfer roller, in the present embodiment, when the sensor S detects the leading edge of the transfer paper, the information The control circuit 120 calculates the time t2 until the leading edge of the transfer paper reaches the transfer position of the transfer roller, and determines whether or not the elapsed time tb by the timer counter Tb satisfies the condition of tb <t2. However, without using a timer counter or the like, a leading edge detection sensor for detecting the leading edge of the transfer paper is provided separately, and the leading edge of the transfer paper is detected by the leading edge detection sensor. good.

  Also, when repeatedly correcting the bending of the transfer paper, tb <t2 is determined and the correction can be made repeatedly while this condition is satisfied. However, the correction is repeatedly performed to correct the transfer posture of the transfer paper repeatedly. When selecting a mode, the number of measurement positions to be measured repeatedly, the number of times of measurement, or the number of corrections that can be corrected may be set in advance. The operation of correcting the transfer posture of the transfer paper may be performed after the accuracy of the amount ΔY deviation amount ΔX is increased.

  In the present invention, in order to correct the transfer posture of the transfer paper, the position measured by the position measuring means is set to a plurality of points on one side edge portion of the transfer paper along the transfer paper transport direction. Compared to the method of measuring the leading edge of the transfer paper being transported, the measurement position is not limited and can be measured repeatedly as necessary, so the transfer paper can be bent and the transfer position shifted with high accuracy. Therefore, it is possible to provide an image forming apparatus capable of forming a high-quality image without bending the transfer paper or transferring the transfer position.

  In addition, since the position measuring means is disposed in the transfer paper conveyance path between the roller unit and the transfer position for transferring the toner image to the transfer paper, the transfer paper can be used as needed until the transfer paper reaches the transfer position. Since the measurement and correction regarding the bending of the transfer paper and the transfer position deviation can be repeated, the bending and the transfer position deviation of the transfer paper can be obtained and corrected with high accuracy. As a result, it has become possible to provide an image forming apparatus capable of forming a high-quality image with no bending of the transfer paper and no transfer position deviation.

  In addition, since the time interval for measuring the first position and the second position by the position measuring means can be changed according to the transfer paper transfer speed, transfer paper size, etc., the transfer paper transfer speed and transfer paper size It is possible to determine and correct the bending and transfer position deviation of the transfer paper with high accuracy based on the measurement data from the position measurement means, and the transfer speed and transfer paper size of the transfer paper. Since the time interval corresponding to the time interval is stored in the storage means, the time interval to be measured can be easily changed, the control is simple, and the image formation that enables high-quality image formation without bending of the transfer paper and transfer position deviation The device can now be provided.

  Further, the transfer paper P is abutted against the roller R2, and the transfer paper forms a loop and temporarily stops, so that the first transfer paper bend correction unit is preliminarily corrected so that the transfer paper is corrected. In addition, the transfer posture correction unit may not be able to correct the transfer sheet slightly by the first transfer sheet bending correction unit, or the transfer sheet generated during the conveyance after the first transfer sheet bending correction unit. Since the second transfer paper bending correction unit is configured so that the bending can also be corrected, it is possible to provide an image forming apparatus capable of correcting the bending of the transfer paper with high accuracy and forming a high-quality image. .

  Although the image forming apparatus has been described by way of an example of a copying machine using recording material as transfer paper, it goes without saying that the image forming apparatus is not limited to a copying machine but may be a facsimile or a printer.

1 is a schematic view of an image forming apparatus according to the present invention. The schematic diagram of the transfer posture correction part which concerns on this invention. Explanatory drawing for demonstrating the curvature correction of the transfer paper which concerns on this invention. 1 is a block diagram showing a circuit configuration of an image forming apparatus according to the present invention. 6 is a flowchart showing a control procedure for correcting the transfer posture of the transfer paper according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Manual feed tray 3 Paper discharge tray 4 Caster 5 Photoconductor drum 6 Charging means 7 Developing means 8 Transfer separation means 9 Cleaning means 10 Fixing device 11 Image forming means 12 Paper feed cassette 13 Image reading means 14 Feed / discharge means 16 Intermediate transfer member 20 Image forming device 30 Automatic document feeder

Claims (13)

An image carrier that carries and rotates a toner image;
A transfer portion for transferring a toner image from the image carrier to transfer paper;
A transfer posture correcting unit that corrects the transfer posture of the transfer paper for receiving the toner image, and matches the timing and movement of the toner image that rotates together with the image carrier, and conveys the corrected transfer paper to the transfer unit; Have
The transfer posture correction unit includes a registration roller that conveys the transfer paper, a roller unit that holds and rotates the registration roller, a detection unit that detects a position of the transfer paper conveyed by the registration roller, and the detection And a controller that rotates the roller unit based on the detection data to correct the bending of the transfer paper, and further moves the registration roller on the roller unit to correct the transfer position of the transfer paper. An image forming apparatus. The roller unit has a substrate configured to be rotatable and a substrate rotating unit that rotates the substrate in contact with one end of the substrate, and rotates the registration roller and the roller that rotates the registration roller on the substrate. The image forming apparatus according to claim 1, further comprising: a moving unit configured to move the registration roller in a rotation axis direction. The image forming apparatus according to claim 1, wherein the detection unit is a line sensor that can detect a position of the transfer paper in a direction orthogonal to a transfer direction of the transfer paper. The image forming apparatus according to claim 3, wherein the line sensor is provided on an exit side of the registration roller. The detection unit measures the first position and the second position on the side end along the transfer paper conveyance direction at a predetermined time interval Δt, and the control unit bends the transfer paper from the two measured values. The image forming apparatus according to claim 1, wherein an amount is calculated, and the roller unit is rotated based on the calculated amount of bending. In the case where a plurality of transfer paper conveyance speeds are provided, the control unit detects the first and second positions when the detection unit measures the first position and the second position of the transfer paper at a predetermined time interval Δt. 6. The predetermined time interval Δt is changed in accordance with a transfer paper conveyance speed so that a measurement distance interval between the position and the second position is constant regardless of the transfer paper conveyance speed. The image forming apparatus described in 1. The image forming apparatus according to claim 6, wherein the control unit changes a transfer paper conveyance speed according to a transfer paper size, and changes the predetermined time interval Δt according to the transfer paper size. The control unit includes a plurality of data of the predetermined time intervals Δt corresponding to a plurality of transfer paper transport speeds and a plurality of transfer paper transport speeds, or a plurality of transfer paper sizes and a plurality of transfer paper sizes. The image forming apparatus according to claim 7, further comprising a memory that stores at least one of the plurality of data of the predetermined time interval Δt corresponding to each of the plurality of data. 6. The image according to claim 5, wherein the control unit controls the detection unit to detect a first position of the transfer paper after a predetermined time t0 after the detection unit detects the leading edge of the transfer paper. Forming equipment. The image forming apparatus according to claim 8, wherein the control unit changes a transfer paper conveyance speed according to a transfer paper size, and changes the predetermined time t0 according to the transfer paper size. The control unit calculates the amount of bending of the transfer paper a plurality of times until the leading edge of the transfer paper conveyed by the registration roller reaches the transfer position of the transfer unit, and performs the bending of the transfer paper a plurality of times. The image forming apparatus according to claim 1, wherein correction is performed. The control unit calculates a deviation between the transfer paper position and the transfer reference position based on the detection data of the detection unit, and moves the registration roller on the roller unit based on the calculated deviation to transfer the transfer paper. The image forming apparatus according to claim 1, wherein the transfer position is corrected. The control unit has a paper feed roller that transports the transfer paper to the registration roller of the transfer posture correction unit, and the control unit stops the registration roller while the paper feed roller is transporting the transfer paper, and transfers to the stopped registration roller. The image forming apparatus according to claim 1, wherein the leading edge of the paper is abutted to preliminarily correct the bending of the transfer paper.

Images