JP6750521B2 - Stain prevention device and image forming apparatus - Google Patents

Description

The present invention relates to a stain prevention device and an image forming apparatus.

In general, an image forming apparatus (printer, copier, facsimile, etc.) that uses electrophotographic process technology forms an electrostatic latent image by irradiating (exposing) a charged photoreceptor with laser light based on image data. Form. Then, by supplying toner from the developing device to the photosensitive drum on which the electrostatic latent image is formed, the electrostatic latent image is visualized and a toner image is formed. Further, after the toner image is directly or indirectly transferred onto the sheet, the image is formed on the sheet by heating and pressing at the fixing nip to fix the sheet.

Further, a paper feeding device for feeding continuous paper (hereinafter referred to as “long paper”) such as continuous roll paper or folding paper to the front and rear of the image forming apparatus, and an image formed by the image forming apparatus. An image forming system has been put into practical use, which is connected to a sheet discharging device that stores a long sheet on which sheets are formed.

In the above-mentioned image forming system, label roll paper whose back side is a seal is often used as a long paper. In this label roll paper, a release sheet having a back surface (a surface corresponding to the release material) coated with glue is attached on a base material coated with the release material. The release sheet is used after being peeled off from the base material and attached to an object after the image is formed on the surface.

By the way, when the label roll paper passes through the fixing nip, the pressure applied by the fixing nip is large, and the glue of the label roll paper is softened by heating, so that the glue sticks out from the edge of the label roll paper. was there. In this case, there is a problem that the protruding glue adheres to a fixing member (for example, a fixing roller, a fixing belt, a pressure roller) forming a fixing nip and stains the fixing member.

In Patent Document 1, there is a technique in which an end pressing portion (hereinafter, simply referred to as a pressing portion) that presses the end portion of the label roll paper is provided on the upstream side of the fixing portion to prevent the glue of the label roll paper from protruding at the fixing portion. It is disclosed. Specifically, in Patent Document 1, the amount of adhesive on the end side of the label roll paper is reduced by reducing the pressing force from the end side of the pressing portion toward the center side and pushing the paste toward the center side. Then, there is disclosed a technique (hereinafter referred to as technique 1) in which the glue is less likely to stick out in the fixing portion. Further, in Patent Document 1, a removing portion is provided to increase the pressing force from the end portion side of the pressing portion toward the center side to discharge the glue from the end portion of the label roll paper and remove the discharged glue. There is disclosed a technique (hereinafter, referred to as technique 2) in which the amount of glue on the edge side of the label roll paper is reduced so that the glue is less likely to stick out at the downstream fixing section.

JP, 2016-090813, A

However, since the technique described in Patent Document 1 presses only the edge portion of the paper, the glue in the entire area of the paper may end up when the entire area of the paper is pressed by the fixing unit depending on the amount of glue in the entire area of the paper. In some cases, the sheet was pushed out to the side of the sheet and protruded from the edge of the sheet. Specifically, in the case of the above technique 1, the glue may be pushed back to the edge of the sheet at the fixing unit and protrude from the edge of the sheet, and in the case of the technique 2, the glue may be preliminarily removed at the fixing unit. In some cases, the paper was extruded from the edge of the paper beyond the removed amount and overflowed.

An object of the present invention is to prevent the fixing member from being soiled with the adhesive contained in the label paper, and to discharge a proper amount of the adhesive before the fixing process is performed on the label paper, and a stain prevention device and an image. It is to provide a forming device.

The stain prevention device according to the present invention,
In the paper conveyance direction of the label paper having a backing sheet coated with adhesive on the base material, it is provided on the upstream side of the fixing unit for fixing an unfixed toner image on the label paper, and the paper conveyance direction. A pressing portion that presses at least an end portion of the release sheet in the paper width direction orthogonal to
A removing unit that removes the glue protruding from the paper by the pressing of the pressing unit,
And a control unit that controls so as to change the mode of pressing the release sheet by the pressing unit according to the amount of glue on the release sheet.

The image forming apparatus according to the present invention is
The above-mentioned dirt prevention device,
An image forming unit that forms a toner image on paper,
And a fixing unit that fixes the toner image on the sheet.

According to the present invention, it is possible to prevent the fixing member from being soiled with the adhesive contained in the label paper, and to discharge an appropriate amount of the adhesive before the fixing process is performed on the label paper.

It is a figure which shows roughly the whole structure of the image forming system in this Embodiment. FIG. 3 is a diagram showing a main part of a control system of the image forming apparatus according to the present embodiment. It is a figure explaining arrangement|positioning etc. of the press part in this Embodiment. It is a figure which shows the structure of the edge part pressing part in this Embodiment, and a removal part, FIG. 4A is a figure shown from the front side, and FIG. 4B is a figure shown from a side surface side. It is a figure which shows the modification of a structure of the edge part pressing part in this Embodiment. It is a figure which shows the modification of a structure of the removal part in this Embodiment. It is a figure which shows the structure for moving the press roller in this Embodiment in an axial direction. It is a figure explaining the pressing mode of the edge part pressing part in this Embodiment, when FIG. 8A and FIG. 8B are the label roll papers which have 1st width and thickness, FIG. 8C and 8D show 2nd width. And label roll paper having a first thickness, FIG. 8E shows a label roll paper having a first width and a second thickness, respectively. 9A and 9B are diagrams illustrating a modified example of the configuration of the pressing unit and a pressing mode according to the present embodiment. FIGS. 9A and 9B are label papers having a first length and thickness, and FIGS. 9C and 9D are In the case of a label paper having a length of 2 and a first thickness, FIG. 9E shows the case of a label paper having a first length and a second thickness, respectively. FIGS. 10A and 10B are diagrams illustrating another modified example of the configuration of the pressing unit according to the present embodiment, FIG. 10A is a diagram illustrating a range in which the paste on the label paper is desired to be removed, and FIG. 10B is another modified example of the configuration of the pressing unit. It is a top view. It is a figure which shows the further another modified example of a structure of the press part in this Embodiment. In the present embodiment, it is a diagram illustrating a pressing mode by the pressing unit when the release sheet is present on a part of the label roll paper or the base material of the label paper.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an image forming system 100 according to this embodiment. FIG. 2 shows a main part of a control system of the image forming apparatus 2 included in the image forming system 100 according to this embodiment. The image forming system 100 uses a long paper P indicated by a thick line in FIG. 1 or a paper (also referred to as “cut paper”) S cut into a predetermined paper size as a recording medium. It is a system that forms an image on top. Here, the long paper P is a paper having a length exceeding the main body width of the image forming apparatus 2 in the conveyance direction, for example. In the present embodiment, as the long paper P, a label roll paper in which a release sheet having a back surface (a surface corresponding to the release material) coated with glue is attached on a base material coated with the release material is used. .. The release sheet is used after being peeled off from the base material and attached to an object after the image is formed on the surface. In the following description, the long paper P is referred to as label roll paper P. Further, in the present embodiment, as the paper S which is a cut paper, it is also possible to use a label paper in which a release sheet having a back surface coated with glue is attached on a base material coated with a label release material. In the following description, the paper S as such label paper is referred to as label paper PS.

As shown in FIG. 1, the image forming system 100 includes a paper feeding device 1, an image forming device 2, and a paper ejection device from the upstream side along the conveyance direction of the long paper P (hereinafter, also referred to as “paper conveyance direction”). The device 3 is connected and configured. The paper feeding device 1 and the paper discharging device 3 are used when forming an image on the label roll paper P.

The paper feeding device 1 is a device that feeds the label roll paper P to the image forming device 2. In the housing of the paper feeding device 1, as shown in FIG. 1, a roll-shaped label roll paper P is wound around a support shaft and rotatably held. The paper feeding device 1 conveys the label roll paper P wound around the support shaft to the image forming device 2 at a constant speed via a plurality of conveyance roller pairs (for example, a feeding roller, a paper feeding roller, etc.). To do. The paper feeding operation of the paper feeding device 1 is controlled by the control unit 101 included in the image forming apparatus 2.

In the sheet feeding device 1, the label roll paper P does not necessarily have to be held in a roll shape, and a plurality of label roll paper P having a predetermined size (for example, 210 mm×1200 mm) may be held.

The image forming apparatus 2 is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. That is, the image forming apparatus 2 primarily transfers the toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 to the intermediate transfer belt 421. After the toner images of four colors are superposed on the intermediate transfer belt 421, the label roll paper P fed from the paper feeding device 1 or the paper S or the label paper PS fed from the paper feed tray units 51a to 51c. An image is formed by secondary transfer to.

Further, in the image forming apparatus 2, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the toner images of respective colors are sequentially transferred to the intermediate transfer belt 421 in one procedure. The tandem system is adopted.

As shown in FIG. 2, the image forming apparatus 2 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a sheet conveying unit 50, a fixing unit 60, and a control unit 101.

The control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, and the like. The CPU 102 reads a program corresponding to the processing content from the ROM 103, expands it in the RAM 104, and centrally controls the operation of each block of the image forming apparatus 2 in cooperation with the expanded program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 is composed of, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 101 transmits/receives various data to/from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) and a WAN (Wide Area Network) via the communication unit 71. To do. The control unit 101 receives, for example, image data transmitted from an external device, and forms an image on the label roll paper P or the paper S or the label paper PS based on this image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card.

The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

The automatic document feeder 11 conveys the document D placed on the document tray by a conveyance mechanism and sends it to the document image scanning device 12. With the automatic document feeder 11, it is possible to continuously read the images (including both sides) of a large number of documents D placed on the document tray all at once.

The document image scanning device 12 optically scans a document conveyed from the automatic document feeding device 11 onto the contact glass or a document placed on the contact glass, and reflects light from the document on a CCD (Charge Coupled Device). ) A document image is read by forming an image on the light receiving surface of the sensor 12a. The image reading unit 10 generates input image data based on the reading result of the original image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

The operation display unit 20 is composed of, for example, a liquid crystal display (LCD: Liquid Crystal Display) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image states, operating states of each function, and the like according to a display control signal input from the control unit 101. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs operation signals to the control unit 101.

The image processing unit 30 includes a circuit that performs digital image processing on input image data in accordance with initial settings or user settings. For example, the image processing unit 30 performs the gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 101. Further, the image processing unit 30 performs various correction processing such as color correction and shading correction, compression processing, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data that has been subjected to these processes.

The image forming section 40 includes image forming units 41Y, 41M, 41C, 41K and an intermediate transfer unit 42 for forming an image with color toners of Y component, M component, C component, and K component based on the input image data. And so on.

The image forming units 41Y, 41M, 41C, and 41K for the Y component, the M component, the C component, and the K component have the same configuration. For convenience of illustration and description, common components are denoted by the same reference numeral, and when differentiating from each other, the reference numeral is appended with Y, M, C, or K. In FIG. 1, reference numerals are given only to the components of the image forming unit 41Y for the Y component, and reference numerals are omitted to the components of the other image forming units 41M, 41C, and 41K.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

The photoconductor drum 413 includes, for example, an undercoat layer (UCL: Under Coat Layer) and a charge generation layer (CGL: Charge Generation Layer) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 mm. , A negative charge type organic photoconductor (OPC) in which charge transport layers (CTL: Charge Transport Layer) are sequentially laminated. 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 a pair of positive charge and negative charge are generated by exposure by the exposure device 411. The charge transport layer consists of a material in which a hole transport material (electron donating nitrogen-containing compound) is 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 control unit 101 controls the drive current supplied to a drive motor (not shown) that rotates the photoconductor drum 413 to rotate the photoconductor drum 413 at a constant peripheral speed.

The charging device 414 uniformly charges the surface of the photoconductor drum 413 having photoconductivity to a negative polarity. The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photoconductor drum 413 with laser light corresponding to an image of each color component. Positive charges are generated in the charge generation layer of the photoconductor drum 413 and are transported to the surface of the charge transport layer, whereby the surface charges (negative charges) of the photoconductor drum 413 are neutralized. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to the potential difference from the surroundings.

The developing device 412 is a two-component developing type developing device, and makes toner of each color component adhere to the surface of the photosensitive drum 413 to visualize the electrostatic latent image to form a toner image.

The drum cleaning device 415 has a drum cleaning blade or the like that is in sliding contact with the surface of the photoconductor drum 413, and removes transfer residual toner remaining on the surface of the photoconductor drum 413 after the primary transfer.

The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

The intermediate transfer belt 421 is an endless belt and is stretched around a plurality of support rollers 423 in a loop. At least one of the plurality of support rollers 423 is a driving roller, and the others are driven rollers. For example, it is preferable that the roller 423A arranged downstream of the primary transfer roller 422 for the K component in the belt traveling direction is a drive roller. This makes it easy to keep the traveling speed of the belt at the primary transfer portion constant. The rotation of the driving roller 423A causes the intermediate transfer belt 421 to travel in the direction of arrow A at a constant speed.

The intermediate transfer belt 421 is a belt having conductivity and elasticity, and has a high resistance layer having a volume resistivity of 8 to 11 logΩ·cm on the surface. The intermediate transfer belt 421 is rotationally driven by a control signal from the control unit 101.

The primary transfer roller 422 is arranged on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photoconductor drums 413 of the respective color components. The primary transfer roller 422 is pressed against the photoconductor drum 413 with the intermediate transfer belt 421 interposed therebetween, whereby a primary transfer nip for transferring the toner image from the photoconductor drum 413 to the intermediate transfer belt 421 is formed.

The secondary transfer roller 424 is arranged on the outer peripheral surface side of the intermediate transfer belt 421, facing the backup roller 423B arranged on the downstream side of the driving roller 423A in the belt traveling direction. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, so that the label roll paper P or the paper S or the label paper PS (hereinafter, these are referred to as the label roll paper P, etc.) from the intermediate transfer belt 421. A secondary transfer nip for transferring the toner image is formed.

When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photoconductor drum 413 are sequentially primary-transferred on the intermediate transfer belt 421 in an overlapping manner. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and a charge having a polarity opposite to that of the toner is applied to the back surface side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422) to form a toner image. It is electrostatically transferred onto the intermediate transfer belt 421.

After that, when the label roll paper P or the like passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the label roll paper P or the like. Specifically, a secondary transfer bias is applied to the secondary transfer roller 424, and a charge having a polarity opposite to that of the toner is applied to the back surface side of the label roll paper P or the paper S (the side in contact with the secondary transfer roller 424). As a result, the toner image is electrostatically transferred to the label roll paper P or the like. The label roll paper P or the like on which the toner image is transferred is conveyed toward the fixing unit 60.

The belt cleaning device 426 removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer. Instead of the secondary transfer roller 424, a configuration in which the secondary transfer belt is stretched in a loop shape on a plurality of support rollers including the secondary transfer roller (so-called belt type secondary transfer unit) is adopted. Good.

The fixing unit 60 includes an upper fixing unit 60A having a fixing surface side member arranged on the side of the fixing surface (the surface on which the toner image is formed) of the label roll paper P, the back surface of the label roll paper P, etc. The lower fixing portion 60B and the like having a back surface side supporting member arranged on the opposite surface side are provided. By pressing the back surface side supporting member against the fixing surface side member, a fixing nip for holding and transporting the label roll paper P and the like is formed.

The fixing unit 60 fixes the toner image on the label roll paper P or the like by heating and pressing the label roll paper P or the like that has been secondarily transferred with the toner roll paper P or the like conveyed in the fixing nip. The fixing unit 60 is arranged in the fixing device F as a unit. Further, the fixing device F may be provided with an air separation unit that separates the label roll paper or the like from the fixing surface side member or the back surface side supporting member by blowing air.

The upper fixing unit 60A has an endless fixing belt 61 which is a fixing surface side member, a heating roller 62, and a fixing roller 63 (belt heating method). The fixing belt 61 is stretched around the heating roller 62 and the fixing roller 63 with a predetermined belt tension (for example, 40 N).

In the fixing belt 61, for example, PI (polyimide) having a thickness of 80 μm is used as a base, and the outer peripheral surface of the base is covered with a heat-resistant silicone rubber (hardness JIS-A30°) having a thickness of 250 μm as an elastic layer. The surface layer (release layer) is coated with PFA (perfluoroalkoxy) which is a heat-resistant resin having a thickness of 70 μm. The outer diameter of the fixing belt 61 is 100 mm, for example. The fixing belt 61 contacts the label roll paper P or the like on which the toner image is formed, and heats and fixes the toner image on the label roll paper P or the like at a fixing temperature (for example, 160 to 200° C.). Here, the fixing temperature is a temperature capable of supplying the amount of heat necessary for melting the toner on the label roll paper P or the paper S, and varies depending on the paper type such as the label roll paper P on which an image is formed.

The heating roller 62 has a built-in heating source (halogen heater) and heats the fixing belt 61. The heating roller 62 is heated by the heating source, and as a result, the fixing belt 61 is heated. The temperature of the heating source is controlled by the control unit 101 so that the temperature of the fixing belt 61 is set to 180° C. The outer diameter of the heating roller 62 is, for example, 50 mm.

The fixing roller 63 has, for example, a columnar cored bar made of aluminum or the like, and an elastic layer made of silicon rubber or the like (thickness: 10 mm) and a surface layer made of a fluororesin such as PTFE (eg, thickness: 70 μm) are sequentially laminated. The outer diameter of the fixing roller 63 is, for example, 40 mm. Drive control of the fixing roller 63 (for example, rotation on/off, peripheral speed, etc.) is performed by the control unit 101. The control unit 101 rotates the fixing roller 63 in the clockwise direction. As the fixing roller 63 rotates, the fixing belt 61 and the heating roller 62 are driven to rotate in the clockwise direction.

The lower fixing unit 60B has a pressure roller 64 that is a back side support member (roller pressure system). The pressure roller 64 has a structure in which an elastic layer made of silicon rubber and a surface layer made of a PFA tube are sequentially laminated on the outer peripheral surface of a cylindrical cored bar made of iron or the like. The outer diameter of the pressure roller 64 is, for example, 40 mm. For example, as shown in FIG. 3, the pressure roller 64 is applied with a predetermined fixing load (for example, 1000 N) on the fixing roller 63 via the fixing belt 61 by a pressure contact/separation unit 640 including a coil spring 641, a cam 642, and the like. Pressed. In the pressure contact/separation portion 640, one end of the coil spring 641 faces the shaft of the pressure roller 64, and the other end of the coil spring 641 faces the side surface of the cam 642. The press contact/separation unit 640 has a shaft of the cam 642 connected to a drive source such as a stepping motor, and the position of the cam 642 is controlled by the control unit 101. 61 and the pressure roller 64 are pressed against each other or separated from each other. In this way, a fixing nip for sandwiching and transporting the label roll paper P and the like is formed between the fixing belt 61 and the pressure roller 64. The control unit 101 performs drive control of the pressure roller 64 (for example, rotation on/off, peripheral speed, etc.) and drive control of the pressure contact/separation unit. The control unit 101 rotates the pressure roller 64 in the counterclockwise direction.

The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. Paper S (standard paper, special paper) and label paper PS identified based on basis weight, size, etc. and label paper PS are set in advance in each of the three paper feed tray units 51a to 51c constituting the paper feed unit 51. Housed in. The transport path portion 53 has a plurality of transport roller pairs including a registration roller pair 53a. The registration roller unit provided with the registration roller pair 53a corrects the inclination and deviation of the paper S or the label roll paper P.

The paper S or the label paper PS stored in the paper feed tray units 51a to 51c are sent out one by one from the uppermost part, and are conveyed to the image forming unit 40 by the conveyance path portion 53. In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred to one surface of the paper S or the label paper PS at once, and the fixing unit 60 performs a fixing process. On the other hand, the label roll paper P fed from the paper feeding device 1 to the image forming device 2 is conveyed to the image forming portion 40 by the conveyance path portion 53. Then, in the image forming unit 40, the toner images on the intermediate transfer belt 421 are secondarily transferred to one surface of the label roll paper P collectively, and the fixing unit 60 performs a fixing process.

The label roll paper P or the like on which an image is formed in this manner is conveyed to the paper ejection device 3 by the paper ejection unit 52 having a conveyance roller pair (paper ejection roller pair) 52a.

The paper discharge device 3 winds up and stores the label roll paper P conveyed from the image forming device 2. In the housing of the paper discharge device 3, for example, as shown in FIG. 1, the label roll paper P is wound around a support shaft and held in a roll shape. Therefore, the paper discharge device 3 supports the label roll paper P conveyed from the image forming device 2 at a constant speed via a plurality of conveyance roller pairs (for example, a feeding roller and a paper discharge roller). Roll it up. The winding operation of the paper discharge device 3 is controlled by the control unit 101 included in the image forming apparatus 2.

By the way, when the label roll paper P passes through the fixing nip, the pressure applied by the fixing nip is large and the glue of the label roll paper P is softened by the heating, so that the glue sticks out from the end portion of the label roll paper P. There were times when it ended up. In this case, there is a problem that the protruding glue adheres to the fixing member (the fixing belt 61 and the pressure roller 64 in the present embodiment) forming the fixing nip and stains the fixing member.

In order to deal with this problem, in the image forming apparatus 2, a pressing unit that presses at least a part (end side) in the width direction orthogonal to the transport direction of the label roll paper P is provided upstream of the fixing unit 60, and the pressing is performed. The glue on the edge side of the label roll paper P is made to squeeze out and collected at a portion. Hereinafter, the configuration of the pressing portion and the like will be described with reference to FIGS.

In the present embodiment, as shown in FIG. 1, FIG. 3, FIG. 4A, and FIG. 4B, in the paper transport direction of label roll paper P (direction of arrow B in FIG. 3), fixing unit 60 and image forming unit 40 On the upstream side, an end pressing portion 80 that presses the end of the label roll paper P in the paper width direction orthogonal to the paper transport direction is provided. The end pressing portions 80 are provided at both ends (left end and right end) of the label roll paper P in the paper width direction orthogonal to the paper transport direction (see FIG. 8). The end pressing unit 80 has a pair of upper and lower pressing rollers 82 and 84 that press the end of the label roll paper P from the vertical direction.

The pressing rollers 82 and 84 press the end portion of the label roll paper P so that the pressing force decreases from the central portion side to the end portion side of the label roll paper P in the paper width direction. As shown in FIG. 4A, the outer diameters of the pressing rollers 82 and 84 are larger on the central side (d2) than on the end side (d1) of the label roll paper P in the paper width direction. With this configuration, the glue P2 located between the base material P1 and the release sheet P3 is pushed from the central portion side to the end portion side of the label roll paper P in the paper width direction and protrudes from the end portion. The sticking out paste P2 adheres to the outer peripheral surfaces of the pressing rollers 82 and 84. The glue P2 adhering to the outer peripheral surfaces of the pressing rollers 82, 84 is scraped off by scrapers 92, 94 as a removing portion provided so as to contact the outer peripheral surfaces.

FIG. 4B is a vertical cross-sectional view of the pressure rollers 82 and 84 and the label roll paper P as viewed from the right side of FIG. 4A. As shown in FIG. 4B, the glue P2 protruding from the end of the label roll paper P adheres to the outer peripheral surfaces of the pressing rollers 82 and 84, and then contacts the scrapers 92 and 94 and the outer peripheral surfaces of the pressing rollers 82 and 84. It is carried to the contact position and scraped off. As described above, since the glue P2 is pushed out from the end portion side of the label roll paper P in the paper width direction, the amount of the glue P2 becomes smaller on the end portion side. As a result, when the label roll paper P passes through the fixing nip, it is possible to prevent the glue P2 from protruding from the end portion of the label roll paper P, and further, to prevent the fixing member from being soiled by the protruding glue. ..

From the viewpoint of more effectively preventing the glue P2 from protruding from the end of the label roll paper P, the label P is provided on the downstream side of the end pressing portion 80 in the paper transport direction of the label roll paper P. It is preferable that the pressing force of the nip (for example, the fixing nip) that nips and conveys P against the label roll paper P is lower than the pressing force of the end pressing portion 80 against the label roll paper P. In other words, it is preferable that the pressing force of the end pressing portion 80 against the label roll paper P is higher than the pressing force at the fixing nip and various nips provided on the downstream side.

On the other hand, when the sheet S containing no glue is conveyed, the edge pressing section 80 does not need to press the edge of the sheet. Therefore, as shown in FIG. 3, the pressing rollers 82 and 84 of the end pressing portion 80 pass a predetermined load on the label roll paper P through the pressure contact separation portion 800 including the coil spring 801 and the cam 802. The sheet S is pressed under a load (for example, a load exceeding 1000 N) and is controlled so as to be separated from the sheet S containing no glue.

The pressure contact/separation portion 800 has the same configuration as the pressure contact/separation portion 640 of the fixing unit 60 described above. That is, in the press contact/separation portion 800, one end of the coil spring 801 faces the shaft of the pressing roller 82 (84), and the other end of the coil spring 801 faces the side surface of the cam 802. The press contact/separation part 800 is opposed to the press contact/separation part 800 through the coil spring 801 which is pressed by the side surface of the cam 802 when the shaft of the cam 802 is connected to a drive source such as a stepping motor and the position of the cam 802 is controlled by the control part 101. The pressure roller 82 and the pressure roller 84 are pressed against each other or separated from each other. Although FIG. 3 illustrates the configuration in which the pressure contact/separation portion 800 is provided on both the upper pressure roller 82 and the lower pressure roller 84, the pressure contact/separation portion 800 is provided on one of the pressure roller 82 and the pressure roller 84. It may be configured.

FIG. 5 shows a modification of the configuration of the pressure rollers 82 and 84. As shown in FIG. 5, the pressure rollers 82 and 84 have a structure in which elastic layers 82B and 84B made of silicon rubber or the like are formed on the outer peripheral surfaces of core metals 82A and 84A made of aluminum or the like, respectively. The outer diameters of the cored bars 82A and 84A are larger on the central side (d4) than on the end side (d3) of the label roll paper P in the paper width direction. That is, the hardness of the pressing rollers 82 and 84 is higher on the central side of the label roll paper P in the paper width direction than on the end side. With this configuration, the glue P2 located between the base material P1 and the release sheet P3 is extruded from the end portion side of the label roll paper P in the paper width direction to the outside, and is reduced on the end portion side. As a result, when the label roll paper P passes through the fixing nip, it is possible to prevent the glue from sticking out from the end portion of the label roll paper P, and thus to prevent the fixing member from being soiled by the sticking glue.

As shown in FIG. 6, the cleaning webs 97 and 99 are brought into contact with the outer peripheral surfaces of the pressing rollers 82 and 84 as the removing portion for removing the glue P2 attached to the outer peripheral surfaces of the pressing rollers 82 and 84. The adhesive P2 may be wiped (removed) with the cleaning webs 97 and 99. Cleaning units 96 and 98 are provided near the pressing rollers 82 and 84, respectively. The cleaning unit 96 includes a main winding portion 96A in which a cleaning web 97 made of paper or cloth is wound in a roll shape, a pressing roller 96B that presses the cleaning web 97 fed from the original winding portion 96A against the pressing roller 82, and a cleaning unit. And a winding portion 96C for winding the subsequent cleaning web 97. The cleaning unit 98 includes an original winding portion 98A in which a cleaning web 99 made of paper or cloth is wound in a roll shape, a pressing roller 98B which presses the cleaning web 99 fed from the original winding portion 98A against the pressing roller 84, and a cleaning unit. And a winding portion 98C for winding the subsequent cleaning web 99.

By the way, as described above, in the configuration in which the widthwise end portion of the label roll paper P is pressed upstream of the fixing unit 60 to remove the glue on the end portion side in advance, the fixing unit 60 depends on the amount of glue in the entire area of the paper. When the entire area (full width) of the paper is pressed by, the adhesive in the entire area of the paper may be pushed out to the edge side and protrude from the edge of the paper. Specifically, as the paper width of the label roll paper P increases, the total amount of glue in the entire paper width increases, so that the glue is pushed toward the end portion at the fixing nip as compared with the case where the paper width of the label roll paper P is small. It is easy to get out of the edge of the paper. Further, as the thickness of the glue on the label roll paper P increases, the amount of the glue per unit area of the paper increases, so that the size of the glue on the label roll paper P is smaller than that on the edge side of the fixing nip as compared with the case where the thickness of the glue is small. It is pushed out to the edge of the paper and becomes easy to stick out.

In view of such a situation, in the image forming apparatus 2 of the present embodiment, a mode in which the release sheet P3 is pressed by the end pressing portion 80 according to the amount of the glue P2 of the release sheet P3 on the label roll paper P is described. The configuration is changed. Specifically, the pressing rollers 82 and 84 of the end pressing portion 80 are configured to be movable in the axial direction, and the pressing rollers 82 and 84 are used depending on the size (width or thickness) of the label roll paper P. The position of the label roll paper P to be pressed is controlled by the control unit 101. The contents of this configuration and control will be described with reference to FIGS. 7 and 8.

In the present embodiment, as shown in FIG. 7, a mechanism is provided that makes the axial distance between the pressing rollers 82, 84 variable. Referring to FIG. 7, a coil spring 85 is provided on the center side of the shaft 83 of the pressing roller 82 (84) facing the paper, and the coil spring 85 causes the pressing roller 82 (84) to move outward in the axial direction. I am biased.

On the other hand, a positioning member 86 for defining the axial position of the pressing roller 82 (84) is provided on the outer side (on the side not facing the paper) of the shaft 83 of the pressing roller 82 (84). Each positioning member 86 is slidably provided on the shaft 83 of the pressing roller 82 (84), and one end side of the positioning member 86 contacts the outer end of the pressing roller 82 (84). Further, a flange-shaped protrusion 86a is formed on the other end of the positioning member 86.

Further, the side surface of the cam 87 is provided so as to abut on the protruding portion 86a of the positioning member 86. In the present embodiment, a drive source such as a stepping motor is connected to the shaft 87a of the cam 87, and the drive source is controlled by the control unit 101. In such a configuration, when the axial position of the pressing roller 82 (84) is moved, the drive source of the cam 87 is controlled by the control unit 101 to rotate the cam 87 and stop it at a desired position. By such control, the pressing roller 82 (84) is pushed and moved toward the center side in the axial direction through the positioning member 86 or moved to the outside in the axial direction, from the sheet end portion to the center side end portion of the pressing rollers 82, 84. The distance X can be variable.

Next, with reference to FIGS. 8A to 8E, a description will be given of a pressing mode of the end pressing section 80 according to the amount of the glue P2 of the label roll paper P, that is, an example of controlling the axial positions of the pressing rollers 82 and 84. ..

8A and 8B show a label roll paper P having a first width and thickness, and FIGS. 8C and 8D show a label roll paper P having a second width and a first thickness smaller than the first width. The roll paper P is shown. That is, the label roll paper P shown in FIGS. 8A and 8B and the label roll paper P shown in FIGS. 8C and 8D have the same thickness and different paper widths orthogonal to the paper transport direction.

Comparing the label roll papers P shown in these drawings, it can be seen that the amount of the glue P2 in the width direction, that is, the axial direction of the pressure rollers 82 and 84 is larger in the paper shown in FIGS. 8A and 8B. Therefore, assuming that the label roll paper P is not pressed by the pressure rollers 82 and 84 and the glue P2 is not discharged, the fixing roller 60 passes through the fixing portion 60 on the downstream side, and the fixing nip of the fixing portion 60 is in the axial (width) direction. The amount of glue extruded from the edge is larger in the paper shown in FIGS. 8A and 8B.

Therefore, it is necessary to increase the amount of glue removed by the end pressing portion 80 located upstream of the fixing portion 60 for the label roll paper P having a large width shown in FIGS. 8A and 8B. In other words, it is desirable that the wider the width of the release sheet P3 of the label roll paper P is, the larger the pressing width (distance X shown in FIG. 7) of the width direction end portion of the release sheet P3 by the end pressing portion 80 is.

Therefore, the control unit 101 sets the distance X from the end of the paper to the end of the pressure rollers 82 and 84 on the center side according to the width of the label roll paper P so that X1>X2 (FIG. 8A and FIG. 8C). In the present embodiment, when the control unit 101 receives the paper information indicating the paper width of the label roll paper P, the control unit 101 calculates the amount of glue of the label roll paper P from the received paper information, and according to the calculated value, The distance X from the edge of the sheet to the central end of the pressing rollers 82, 84 is determined and the pressing rollers 82, 84 are controlled to move.

FIG. 8E illustrates a case where the label roll paper P has a first width and a second thickness that is larger than the first thickness. That is, the label roll paper P shown in FIGS. 8A and 8B and the label roll paper P shown in FIG. 8E show the case where the width of the paper orthogonal to the paper transport direction is the same and the thickness thereof is different.

Comparing the label roll papers P shown in these drawings, it can be seen that the amount of the glue P2 in the thickness direction is larger in the paper shown in FIG. 8E. Therefore, assuming that the label roll paper P is not pressed by the pressure rollers 82 and 84 and the glue P2 is not discharged, the fixing roller 60 passes through the fixing portion 60 on the downstream side, and the fixing nip of the fixing portion 60 is in the axial (width) direction. The amount of glue pushed out from the edge is larger in the paper shown in FIG. 8E.

Therefore, the control unit 101 sets the distance X from the edge of the sheet to the central end of the pressure rollers 82 and 84 in accordance with the thickness of the label roll paper P such that X3>X1. (See Figures 8A and 8E). In the present embodiment, when the control unit 101 receives the paper information indicating the thickness of the label roll paper P, the control unit 101 calculates the amount of glue of the label roll paper P from the received paper information, and according to the calculated value. Then, the distance X from the edge of the paper to the central end of the pressing rollers 82, 84 is determined, and the pressing rollers 82, 84 are controlled to move.

Table 1 shows an example of the distance X determined by the control unit 101 according to the width and thickness of the label roll paper P.

Paper information relating to the size (width or thickness) of such paper can be automatically detected by using a sensor or the like. Alternatively, the paper information may be configured to be input by the user via the operation display unit 20 or a display unit or an input unit (hereinafter, referred to as a display unit) of an external device such as a PC (not shown). When the user inputs the paper information, the input screen for inputting the paper size and the basis weight can be displayed on the display unit or the like. Alternatively, paper brand information and paper size information are registered in association with each other in a table (not shown), a list of paper brands is displayed on the display unit, etc., and the user can select the brand of paper to be used. It may be configured as.

Further, the value of the pressing width (distance X) determined by the control unit 101 may be finely adjusted by the user. In this case, for example, the value of the pressing width (distance X) determined by the control unit 101 is displayed on the display unit or the like, and the display unit is provided so that the user can input the pressing width adjustment instruction to increase or decrease the pressing width. Etc. Alternatively, for example, the user may be allowed to input a pressing width adjustment instruction to increase or decrease the pressing width (distance X) determined by the control unit 101 only on the left side or the right side in the paper width direction.

When the user inputs a pressing width adjustment instruction, the control unit 101 presses from the edge of the paper so as to increase or decrease the value of the determined pressing width (distance X) in consideration of the pressing width adjustment instruction. The distance X to the central end of the rollers 82, 84 is controlled. When the value of the determined pressing width (distance X) is reduced by the pressing width adjustment instruction, the control unit 101 reduces the adhesive P2 to the extent that the paste P2 does not stick out from the sheet at the downstream fixing nip.

On the other hand, it is desirable that the pressing force of the end pressing portion 80 is larger than the pressing force of the fixing nip as described above. However, if the pressing force becomes strong, the sheet may be deformed. In some cases, it may be better to set to be weak and to set the distance X to be relatively large. Therefore, when the value of the determined pressing width (distance X) is increased by the pressing width adjustment instruction, the control unit 101 presses the end pressing portion 80 to such an extent that the glue P2 does not stick out from the paper at the downstream fixing nip. The pressure may be set weakly.

As described above, according to the present embodiment, control is performed to change the position of the end portion pressing portion 80 depending on the type of paper, so that the label nip P is not affected by a large amount of glue P2, but by the fixing nip. It is possible to prevent the glue from protruding from the paper, and thus to prevent the fixing member from being soiled with the glue.

Next, another configuration example of the pressing portion will be described with reference to FIGS. 9 to 11.

In FIG. 7 and FIG. 8 and the like, the case where the image forming sheet is the label roll sheet P has been described. On the other hand, when the paper on which the image is formed is the label paper PS that is a cut paper, in the configuration in which the width direction end portion of the paper is pressed as described above, the paper is pressed when the fixing unit 60 presses the entire area of the paper. Even if it is possible to prevent the adhesive from squeezing out from the end portion in the width direction of the sheet, a problem may occur in which the adhesive is extruded and squeezes out from the rear end in the sheet conveying direction.

Specifically, in the configuration in which the glue of the label paper PS is pushed out (extended out) from the widthwise end portion by the end portion pressing portion 80, when the paste passes through the fixing nip, the glue is moved in the sheet conveying direction by the pressing force of the fixing nip. Since it is extended rearward, there is a problem that the glue is extruded from the trailing end of the label paper PS in the conveying direction and protrudes, and the fixing member is soiled by the protruded glue.

In order to deal with such a problem, in the paper conveyance direction of the label paper PS, in the paper width direction orthogonal to the paper conveyance direction, as shown in FIGS. 9A and 9B, on the upstream side of the fixing unit 60 and the image forming unit 40. The full width pressing portion 80A that presses the full width of the label paper PS in FIG. The full width pressing portion 80A has a pair of upper and lower pressing rollers 82C and 84C that press the entire width of the label paper PS from the vertical direction. In the present embodiment, the pressure rollers 82C and 84C are provided on the upstream side of the registration roller pair 53a in the sheet conveying direction, and are disposed, for example, in the vicinity of the pressure rollers 82 and 84 of the above-mentioned end portion pressing portion 80 (FIG. 10B).

As shown in FIG. 9A, the pressing rollers 82C and 84C of the full width pressing portion 80A have a width that is longer than the total width of the label paper PS in the transport direction. The full-width pressing portion 80A may be configured such that one of the pressing rollers 82C and 84C is rotationally driven by a drive source such as a motor.

Further, as shown in FIG. 9B, scraper 92A, 94A as a remover for removing the glue protruding from the label paper PS is provided on the press rollers 82C, 84C of the full-width press part 80A. It is provided so as to abut the surface. The scrapers 92A and 94A have substantially the same width as the corresponding pressing rollers 82C and 84C (see FIG. 10B).

In the image forming apparatus 2 having such a configuration, when an image is formed on the label paper PS, the label paper PS is pressed by the pressing rollers 82C and 84C from above and below on the upstream side of the image forming section 40 in the transport direction. While being conveyed, the paper is passed toward the image forming unit 40. At this time, the glue P2 between the base material P1 and the release sheet P3 is pushed out from the paper, and sticks out on the pressing rollers 82C and 84C from the end portions of the label paper PS, that is, the left and right ends and the rear end in the paper transport direction. Then, the glue P2 protruding from the left and right ends of the label paper PS in the paper transport direction is attached to the widthwise end portions of the pressure rollers 82C and 84C, and the glue P2 protruding from the rear end of the label paper PS in the paper transport direction is. , The pressure rollers 82C and 84C are adhered over substantially the entire width direction.

In this way, the paste P2 that sticks out from the label paper PS and adheres onto the pressure rollers 82C and 84C is scraped off by the scrapers 92A and 94A that are in contact with the surfaces of the pressure rollers 82C and 84C. By this operation, the surfaces of the pressure rollers 82C and 84C to which the glue P2 is attached are cleaned by the scrapers 92A and 94A.

Therefore, according to the image forming apparatus 2, the amount of the glue P2 at the left and right ends and the rear end of the label paper PS in the sheet conveying direction is reduced, and the entire label paper PS is pressed by the fixing nip so that the glue P2 ends (left and right). It is possible to prevent the adhesive P2 from squeezing out from the paper and contaminating the fixing member even when the fixing member is moved to both ends and the rear end.

The cleaning webs 97 and 99 as described above with reference to FIG. 6 may be used to remove the glue P2 attached to the outer peripheral surfaces of the pressing rollers 82C and 84C.

Next, the control for switching the pressing force by the full width pressing portion 80A will be described with reference to FIG.

As described above, in the configuration in which the pressing rollers 82C and 84C have a width larger than the entire width of the label paper PS in the transport direction and the entire width of the label paper PS in the transport direction is pressed, the glue P2 is spread over the entire width of the label paper PS. The glue P2 that has squeezed out and squeezed out can be attached and removed over substantially the entire width of the pressing rollers 82C and 84C.

On the other hand, in such a configuration, when the pressing mode (pressing force) of the pressing rollers 82C and 84C against the label paper PS is always constant, the size (length, width, thickness) of the label paper PS and the glue per unit area are set. Depending on the amount of P2 and the like, the amount of the glue P2 protruding by the full width pressing portion 80A may be excessive or insufficient. Specifically, as the length of the paper along the transport direction of the label paper PS is longer, the total amount of glue in the transport direction of the paper, that is, the total length of the paper is increased. The glue is pushed out to the edge side at the fixing nip and easily sticks out from the edge of the paper. Moreover, since the amount of glue per unit area of the paper increases as the thickness of the glue on the label paper PS increases, the glue is pushed out toward the end side at the fixing nip as compared with the case where the thickness of the glue on the label paper PS is small. It easily sticks out from the edge of the paper.

Here, if the amount of the glue P2 protruding by the full-width pressing portion 80A becomes excessively large, the function of the label paper PS as a label decreases, and the release sheet P3 may not stick to the target object. On the other hand, if the amount of the glue P2 that is pushed out by the full-width pressing portion 80A is too small, the glue P2 may be pushed out at the fixing nip and soil the fixing member as described above.

Therefore, in the present embodiment, a mechanism for varying the pressing force of the pressing rollers 82 and 84 against the label paper PS is provided, and the pressing force is controlled by the control unit 101. Specifically, the pressure contact/separation portion 800 described above with reference to FIG. 3 is provided on the pressing rollers 82C and 84C, and the control unit 101 controls the drive source (eg, stepping motor) that drives the cam 802 of the pressure contact/separation portion 800. The pressing force of the pressing rollers 82C and 84C is switched during the transportation of the label paper PS.

Here, the control unit 101 switches the pressing force of the pressure rollers 82C and 84C at the timing (see FIGS. 9A and 9B) at which the trailing end side of the label sheet PS in the transport direction passes through the pressure rollers 82C and 84C. To control. More specifically, the control unit 101 controls the pressing rollers 82C and 84C at a position where the amount of the glue P2 protruding on the trailing end side of the label paper PS is assumed while the label paper PS is being conveyed by the pressing rollers 82C and 84C. The stepping motor is controlled so that the pressing force is larger than that before switching.

By such control, the larger amount of the glue P2 sticks out on the trailing end side of the label paper PS in the transport direction, and the sticking glue P2 is attached to the pressing rollers 82C and 84C and removed by the removing section (not shown in FIG. 9). In this way, by performing control to switch the pressing forces of the pressure rollers 82C and 84C so that the paste P2 at the rear end of the paper is extruded in a focused manner, the paste P2 protrudes from the rear end of the label paper PS at the fixing nip. This can be prevented even better.

9A and 9B show a state immediately before switching the pressing force so as to increase the pressing force of the pressing rollers 82C and 84C at the rear end side in the transport direction of the label paper PS. Here, the pressing force of the pressing rollers 82C and 84C after switching the pressing force is preferably set to be larger than the pressing force of the fixing nip.

The pressing force of the pressing rollers 82C and 84C may be set to be larger than the pressing force of the fixing nip before the switching of the pressing force and further from the leading end in the transport direction of the label paper PS, but in this case, the adhesive P2 excessively protrudes. It may happen. Therefore, as described above, it is desirable to switch the pressing force of the pressure rollers 82C and 84C so that the pressing force of the pressure roller 82C is larger than the pressing force of the fixing nip on the trailing end side in the transport direction of the label paper PS. Further, until the pressing force is switched from the leading end in the transport direction of the label paper PS, the pressing force of the pressing rollers 82C and 84C is zero, that is, an arbitrary value out of the pressing force weaker than the fixing nip is used. can do.

In addition, in the present embodiment, control is performed to change the mode of pressing by the full width pressing portion 80A according to the amount of the glue P2 on the label paper PS. Specifically, the control unit 101 controls the switching position of the pressing force by the pressing rollers 82C and 84C according to the size (length or thickness) of the label paper PS. The contents of such control will be described with reference to FIGS. 9A to 9E.

9A and 9B show a label paper PS having a first length and thickness, and FIGS. 9C and 9D have a second length and a first thickness that are shorter than the first length. The label paper PS is shown. That is, the label paper PS shown in FIGS. 9A and 9B and the label paper PS shown in FIGS. 9C and 9D have the same thickness and different paper lengths along the paper transport direction.

Comparing the label sheets PS shown in these figures, the amount of the glue P2 in the sheet conveying direction, that is, in the sheet length direction orthogonal to the axial direction of the pressure rollers 82C and 84C, is larger in the sheet shown in FIGS. 9A and 9B. You can see that there are many. Therefore, if it is assumed that the label paper PS is not pressed by the pressure rollers 82C and 84C and the adhesive P2 is not discharged, the amount of the adhesive extruded in the fixing nip of the fixing portion 60 is assumed to pass through. 9A and 9B have more sheets.

Therefore, the amount of glue to be removed by the full-width pressing portion 80A upstream of the fixing portion 60 needs to be larger for the label paper PS having a longer length shown in FIGS. 9A and 9B. In other words, the longer the length of the label paper PS is, the larger the position (Y) from the rear end in the length direction of the paper, where the full width pressing portion 80A is switched to increase the pressing force on the label paper PS. It is desirable to do.

Therefore, the control unit 101 changes the distance Y from the rear end in the length direction of the paper, which is a position to switch to increase the pressing force of the full width pressing unit 80A according to the paper length of the label paper PS. It is set such that Y1>Y2 (see FIGS. 9B and 9D). In the present embodiment, when the control unit 101 receives the paper information indicating the paper length of the label paper PS, the control unit 101 calculates the amount of glue of the label paper PS from the received paper information and determines the paper amount according to the calculated value. The distance Y from the rear end in the length direction is determined, and when the rear end side in the transport direction of the label paper PS becomes the distance Y, the pressing force of the full width pressing portion 80A is controlled to be largely switched. Specifically, the controller controls the stepping motor that drives the cam 802 (see FIG. 3) of the above-described pressure contact/separation unit 800 at the timing when the portion of the label sheet PS on the rear end side in the transport direction comes to the distance Y from the rear end. By controlling with 101, it is switched so as to increase the pressing force of the pressing rollers 82C and 84C.

FIG. 9E shows a case where the label paper PS has a first length and a second thickness that is larger than the first thickness. That is, the label paper PS shown in FIGS. 9A and 9B and the label paper PS shown in FIG. 9E show a case where the lengths of the papers along the paper transport direction are equal and the thicknesses are different.

Comparing the label sheets PS shown in these figures, it can be seen that the amount of the glue P2 in the thickness direction is larger in the sheet shown in FIG. 9E. Therefore, if it is assumed that the label paper PS is not pressed by the pressure rollers 82C and 84C and the adhesive P2 is not discharged, the adhesive is pushed out by the fixing nip of the fixing unit 60, assuming that the adhesive passes through the fixing unit 60 on the downstream side. , The number of sheets shown in FIG. 9E is larger.

For this reason, the control unit 101 moves from the rear end in the length direction of the sheet at a position where the full-width pressing unit 80A switches to increase the pressing force on the label sheet PS in accordance with the thickness of the label sheet PS. The distance Y is set such that Y3>Y1 (see FIGS. 9B and 9E). In this embodiment, when the control unit 101 receives the paper information indicating the thickness of the label paper PS, the control unit 101 calculates the amount of glue of the label roll paper P from the received paper information, as described above. The distance Y from the rear end in the length direction of the paper is determined according to the calculated value, and when the rear end side in the transport direction of the label paper PS becomes the distance Y, the pressing force of the full width pressing portion 80A is controlled to be largely switched.

Table 2 shows an example of the distance Y determined by the control unit 101 according to the length and thickness of the label paper PS.

Similar to the above, such paper information regarding the size (length and thickness) of paper can be configured to be automatically detected using a sensor or the like, or can be input by the user via a display unit or the like. It may have any configuration.

Further, the value of the distance Y determined by the control unit 101 may be finely adjusted by the user. In this case, for example, the value of the distance Y determined by the control unit 101 is displayed on the display unit or the like, and the display unit or the like is displayed so that the user can input a pressing position adjustment instruction to increase or decrease the value of the distance Y. indicate. Here, when the pressing position adjusting instruction is input, the control unit 101 adds the pressing position adjusting instruction to increase or decrease the value of the determined distance Y so that the pressing force of the pressing rollers 82C and 84C is increased. Control the position to switch. When the value of the determined distance Y is reduced by the pressing position adjustment instruction, the control unit 101 reduces the adhesive P2 to the extent that the paste P2 does not stick out from the sheet at the downstream fixing nip.

On the other hand, it is desirable that the maximum value of the pressing force by the full-width pressing portion 80A is larger than the pressing force of the fixing nip as described above. In some cases, it may be better to set the pressing force weak and set the distance Y relatively large. Therefore, when the value of the determined distance Y is increased by the pressing position adjustment instruction, the control unit 101 sets the pressing force of the full-width pressing unit 80A to a weak level so that the glue P2 does not stick out from the paper in the downstream fixing nip. May be.

Next, another configuration example of the pressing portion will be described with reference to FIGS. 10A and 10B. The shaded portion in FIG. 10A indicates a range P2a in which the paste P2 on the label paper PS is desired to be removed. In this example, the area P2a where the paste P2 is desired to be removed is substantially U-shaped including the left and right end portions and the rear end portion in the paper transport direction of the label paper PS, as shown in FIG. 10A.

When removing the glue P2 in such a range P2a, as shown in FIG. 10B, the pressing portion has pressing rollers 82C and 84C (full width pressing portion 80A) and pressing rollers 82 and 84 (end pressing portion 80) as described above. Both should be provided. A removing unit (scraper or cleaning web) having the same configuration as described above is in contact with each of the pressing rollers 82 and 84 of the end pressing unit 80, and the removing unit is not shown for simplicity.

In FIG. 10B, the full-width pressing portion 80A is arranged on the downstream side of the end pressing portion 80 in the paper transport direction, but the reverse, that is, the full-width pressing portion 80A is arranged on the upstream side of the end pressing portion 80. Good. 10B, the full-width pressing portion 80A is provided near the end pressing portion 80, but the full-width pressing portion 80A and the end pressing portion 80 may be placed separately from each other.

In such a configuration, when the control unit 101 receives the paper information indicating the paper width, the paper length, and the paper thickness of the label paper PS, the control unit 101 calculates the amount of glue of the label paper PS from the received paper information, and performs the calculation. Depending on the value, the distance X (see FIG. 10A) from the edge of the paper to the central end of the pressing rollers 82, 84 is determined, and the pressing rollers 82, 84 are controlled to move. Further, the control unit 101 determines the distance Y (see FIG. 10A) from the rear end in the length direction of the paper according to the calculated value of the amount of glue on the label paper PS, and the rear end side in the transport direction of the label paper PS is determined. When the distance becomes Y, the pressing force of the full-width pressing portion 80A is controlled to be largely switched.

By performing such control, the glue P2 in the substantially U-shaped range P2a including the left and right ends and the rear end of the label paper PS in the paper transport direction is protruded from the label paper PS and removed. As a result, the glue P2 can be prevented from protruding from the left and right ends and the rear end of the label paper PS in the transport direction. Further, according to such a configuration, the glue P2 in the central region of the label paper PS can be left, and the paste P2 can be easily pushed out from the label paper PS without excess or deficiency.

11A and 11B show still another configuration example of the pressing portion. In the illustrated example, the above-described pressing roller 82C is arranged on the upper side of the sheet, and a plurality of pressing rollers 88 that independently move up and down are provided on the lower side of the sheet in the sheet width direction, whereby the label roll paper P or A configuration example in which the pressing force can be controlled at an arbitrary position of the label paper PS in the paper width direction is shown.

Referring to FIG. 11B, the rotation shaft of the pressing roller 88 is fixed to the pressing roller holder 89, and the pressing roller holder 89 is reciprocally movable only in the pressing direction by a rail (not shown) and moved in the pressing direction by the pressing spring 89a. Is configured to. Further, a cam 89b is provided on one end side of the pressing spring 89a, and the control unit 101 controls a drive source (for example, a stepping motor) for driving the cam 89b to switch the pressing force of the pressing roller 88. Further, a scraper 92B as a removing section for removing the glue is provided so as to contact the surface of the pressing roller 88.

With such a configuration, the adhesive P2 can be appropriately discharged on either the label roll paper P or the label paper PS. That is, when the area from the widthwise end of the label roll paper P or the label paper PS to the distance X (see FIG. 11A) is pressed to eject the glue P2, the control unit 101 positions the area at the distance X. The pressing force of the pressing roller 88 is controlled to be high. On the other hand, when switching to increase the pressing force at the position of the distance Y from the rear end of the label paper PS in the transport direction, the control unit 101 sets the timing at which the transport position of the label paper PS reaches the position corresponding to the distance Y. , Control is performed so that the pressing force of all the pressing rollers 88 is switched to high. Therefore, according to the pressing portion configured as shown in FIG. 11, it is possible to remove the glue in the substantially U-shaped range P2a as described above with reference to FIG. 10A.

FIG. 12 shows another configuration example of the label roll paper P or the label paper PS. In the above-described respective configuration examples, the label roll paper P or the label paper PS having the configuration in which the base material P1 and the release sheet P3 have the same shape, that is, the release sheet P3 is arranged on the entire surface of the base material P1 has been described.

On the other hand, as for the label roll paper P and the label paper PS, as shown in FIG. 12, the release sheet P3 has a shape smaller than the base material P1 and may be arranged on a part of the base material P1. In such a case, the control of the position where the pressing force of the full width pressing portion 80A is switched may be performed with reference to the rear end of each release sheet P3. In addition, the control of the end pressing width X of the end pressing portion 80 may be performed with reference to the center position or the end position of each release sheet P3 in the width direction. In this case, it is desirable to include the width and length of the release sheet P3 as the above-mentioned sheet information.

As described above, in the above-described embodiment, the pressing unit that is provided on the upstream side of the fixing unit 60 and presses at least the end of the release sheet P3 of the label roll paper P or the label paper PS, and the paper by the pressing of the pressing unit. A removal unit that removes the adhesive that protrudes from the substrate, and a control unit 101 that controls the pressing unit to change the mode of pressing the release sheet P3 according to the amount of the adhesive on the release sheet P3. With this configuration, the adhesive P2 contained in the label roll paper P or the label paper PS is prevented from soiling the fixing member, and an appropriate amount of the adhesive P2 is discharged before the fixing process is performed on the paper. be able to.

In addition, each of the above-described embodiments is merely an example of the embodiment for carrying out the present invention, and the technical scope of the present invention should not be limitedly interpreted by these. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

100 image forming system 2 image forming apparatus 40 image forming unit 50 paper transport unit 60 fixing unit 80 end pressing unit (pressing unit)
80A full width pressing part (pressing part)
82,82C,84,84C Pressing roller 82A,84A Core metal 82B,84B Elastic layer 92,92A,94,94A Scraper (removal part)
97,99 Cleaning web (removal part)
101 control unit (paper information receiving unit)
800 Pressure contact/separation part 801 Coil spring 802 Cam P Label roll paper PS Label paper P1 Base material P2 Adhesive P3 Release sheet

Claims (14)

In the paper conveyance direction of the label paper having a backing sheet coated with adhesive on the base material, it is provided on the upstream side of the fixing unit for fixing an unfixed toner image on the label paper, and the paper conveyance direction. A pressing portion that presses at least an end portion of the release sheet in the paper width direction orthogonal to,
A removing unit that removes the glue protruding from the paper by the pressing of the pressing unit,
A control unit that controls to change a mode of pressing the release sheet by the pressing unit according to the amount of glue of the release sheet,
Contamination prevention device. A paper information receiving unit for receiving paper information regarding the type of label paper,
The control unit controls the position of the pressing unit that presses the release sheet based on the received paper information,
The antifouling device according to claim 1. The control unit calculates the amount of glue of the release sheet from the paper information, and controls the position of the pressing unit that presses the release sheet based on the calculation result,
The antifouling device according to claim 2. The paper information includes paper width information,
The control unit controls to increase the pressing width of the width direction end portion of the release sheet by the pressing unit as the width of the sheet increases.
The antifouling device according to claim 2 or 3. The label paper is cut paper,
The paper information includes information on the length of the release sheet,
The control unit controls to increase the pressing force of the pressing unit at the timing when the trailing edge side of the label sheet in the transport direction passes through the pressing unit. Control to increase the pressing width on the rear end side to increase the pressure,
The antifouling device according to any one of claims 2 to 4. The paper information includes information on the thickness of the label paper,
The control unit controls so that the thicker the label paper is, the larger the pressing width of the width direction end portion of the release sheet by the pressing unit is,
The antifouling device according to any one of claims 2 to 5. The label paper is cut paper,
The paper information includes information on the thickness of the label paper,
The control unit controls to increase the pressing force of the pressing unit at the timing when the rear end side in the transport direction of the label paper passes the pressing unit, and the thicker the label paper is, the more the pressing force is increased. Control to increase the pressing width on the rear end side to increase the pressure,
The antifouling device according to any one of claims 2 to 5. The paper information receiving unit receives the paper information input via a display unit,
The antifouling device according to any one of claims 2 to 7. The control unit, when an instruction to adjust the pressing position is input via the display unit, in consideration of the instruction, the pressing unit controls the position pressed by the release sheet,
The antifouling device according to any one of claims 2 to 8. The pressing portion is configured such that the pressing force decreases from the central portion in the paper width direction toward the end portion in the paper width direction,
The stain prevention device according to any one of claims 1 to 9. The pressing portion includes a pair of end pressing rollers movable along the paper width direction,
The antifouling device according to claim 10. The pressing unit includes a pressing roller that presses the entire width of the label paper,
The antifouling device according to any one of claims 1 to 11. The pressing portion includes a plurality of pressing rollers arranged along the paper width direction,
The antifouling device according to any one of claims 1 to 12. A stain prevention device according to any one of claims 1 to 13,
An image forming unit that forms a toner image on paper,
A fixing unit configured to fix the toner image on the sheet,
Image forming apparatus.

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