JP2007025481A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of banding, in an image forming apparatus having a transfer process and a fixing process. <P>SOLUTION: The distance between a transfer position and a primary fixing section is made slightly shorter than the shortest image-receiving medium. The distance between the transfer position and a secondary fixing section is made slightly shorter than the longest image-receiving medium. When an image is formed on the shortest image-receiving medium, the image is fixed in the primary fixing section and the secondary fixing section. When the image is formed on the longest image-receiving medium, the image is fixed only in the secondary fixing section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a transfer process for transferring an image to an image receiving medium and a fixing process after transfer, and more specifically, image formation capable of preventing image unevenness in image transfer and miniaturizing the apparatus. Relates to the device.

As in electrophotographic image recording, after an image is formed on an image forming medium, or after an image is further transferred from the image forming medium to an intermediate transfer member, the image receiving medium (recording sheet) is transferred from the image forming medium or intermediate transfer member. An image forming method is known in which an image is transferred to the image and then the transferred image is fixed by pressurization or the like.
In image formation in which transfer is performed in this manner, if load fluctuations of the image receiving medium occur during image transfer, image unevenness (so-called banding) occurs, and image quality deteriorates. Examples of load fluctuation factors that cause banding include an impact when the image receiving medium enters the downstream process during transfer (tip entry load), a speed difference between the downstream conveyance speed and the transfer speed, and the like.

Particularly in recent years, as disclosed in Patent Document 1 and the like, high-quality prints close to silver halide photographic prints can be created even in electrophotographic image formation by means such as giving gloss to the surface of an image receiving medium. Has been done.
In such a high-quality print, image unevenness becomes a big problem, and it is extremely important to eliminate the occurrence of banding. In addition, in such a high-quality print, a thick image receiving medium is preferred, so that the tip inrush load is large and banding is likely to occur.

In order to suppress such banding, various methods have been proposed for reducing or eliminating load fluctuations that occur during image transfer to an image receiving medium.
For example, in Patent Document 2, in an image forming apparatus that performs transfer and fixing by press contact such as electrophotography, the distance between the transfer position and the fixing position is made longer than the corresponding longest image receiving medium, thereby causing banding or the like. An image forming apparatus with reduced image quality degradation is disclosed.
Japanese Patent Application Laid-Open No. 2004-228561 discloses an apparatus in which an applied pressure is variable by using an electromagnetic force in addition to a spring in an image fixing apparatus using pressure. Using this, it is conceivable to reduce the banding by initially reducing the applied pressure and increasing the applied pressure after the image receiving medium has entered the fixing device.

JP 2004-109860 A JP-A-3-253882 JP 58-126561 A

  However, as disclosed in Patent Document 2, if the distance (conveyance length) between the transfer position and the fixing position is longer than the longest image receiving medium, it is not only necessary to increase this distance, but also between the two. Therefore, it is necessary to provide a conveying means such as a conveying belt for conveying an image receiving medium smaller than the longest size, which causes an increase in size and cost of the apparatus.

  In fixing an electrophotographic image formation, it is necessary to maintain a certain level of pressure. For this reason, when the method disclosed in Patent Document 3 in which the pressure is changed during fixing, the load relationship between the respective processes (units) fluctuates due to load fluctuations in the fixing unit that occur during fixing conveyance. The banding caused by will occur.

  An object of the present invention is to solve the above-described problems of the prior art, and an image for transferring an image to an image receiving medium and then fixing the image transferred to the image receiving medium as in electrophotographic image formation. In the formation, it is possible to prevent the deterioration of image quality due to banding, and it can be suitably applied even for applications requiring high-quality images corresponding to the photographic image quality, and also the size of the apparatus is increased. An object of the present invention is to provide an image forming apparatus which can be configured in a compact manner.

  In order to achieve the above object, an image forming apparatus of the present invention includes a transfer unit that transfers an image to an image receiving medium at a predetermined transfer position, and a transfer unit that is disposed downstream of the transfer unit and pressurizes the image receiving medium. A primary fixing unit capable of fixing the image to be fixed and capable of being in a fixing state and a non-low fixing state; and a second fixing unit disposed downstream of the primary fixing unit and fixing the transferred image by pressurizing the image receiving medium. And a transfer length of the image receiving medium from the transfer position to the image fixing position in the secondary fixing section is shorter than the length of the longest image receiving medium in the transfer direction. When the image receiving medium is transported from the position to the fixing position in the primary fixing unit is shorter than the length in the transport direction of the image receiving medium that is the shortest in the transport direction, and when the image is formed on the longest image receiving medium The primary fixing unit is in a non-fixed state, and the transfer unit transfers the image to a position where transfer is completed when the leading edge of the image receiving medium reaches the secondary fixing unit, and When an image is formed on the shortest image receiving medium, the primary fixing unit is in a fixed state, and the transfer unit is a position where the transfer is completed when the leading edge of the image receiving medium reaches the primary fixing unit. An image forming apparatus is characterized in that the image is transferred.

In such an image forming apparatus, it is preferable that an intermediate transport unit capable of sandwiching and transporting the image receiving medium in which the image receiving medium is sandwiched and opened can be provided between the primary fixing unit and the secondary fixing unit.
At this time, when an image is recorded on the longest image receiving medium, it is preferable that the intermediate conveyance unit is opened at least until the transfer is completed. Further, when an image is formed on an image receiving medium having a length in the transport direction shorter than the longest image receiving medium and longer than the shortest image receiving medium, the transfer unit has a blank at the rear end in the transport direction. And transferring the image onto the image receiving medium, and setting the primary fixing unit in a non-fixed state, and the intermediate transport unit is initially in an open state and is in a sandwiched state after the transfer in the transfer unit is completed. Preferably, when forming an image on an image receiving medium whose length in the conveying direction is shorter than the longest image receiving medium and longer than the shortest image receiving medium, the intermediate conveying unit is initially Is in an open state, preferably after the leading edge of the image receiving medium reaches the intermediate conveying means, gradually enters a clamping state, or the length in the conveying direction is shorter than the longest image receiving medium, and Image receiving medium longer than the shortest image receiving medium When recording a plurality of images at intervals in the transport direction, the intermediate transport unit is initially open, the image receiving medium reaches the intermediate transport unit, and the transfer position is between the images in the transport direction. At this point, it is preferable to be in a sandwiched state.

  According to the present invention having the above configuration, after an image is formed on an image forming medium or an intermediate transfer body, as in electrophotographic image formation, the image is transferred to an image receiving medium (recording sheet), and then transferred. In an image forming apparatus that fixes a printed image by pressurization (or further heating), banding (image unevenness) due to load fluctuation of the image receiving medium during transfer can be prevented, and the apparatus can be used in accordance with the corresponding image receiving medium. It can be made compact.

  Hereinafter, an image forming apparatus of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIG. 1 is a conceptual diagram illustrating an example of a printer that uses the image forming apparatus of the present invention.
The printer 10 shown in FIG. 1 records an image on a recording sheet A (image receiving medium) by an electrophotographic method to create a print. Basically, the printer 10 includes a recording sheet supply unit 12 and an image forming unit 14. And a cutting / arranging portion 16. Further, even if there is no particular illustration or reference between these parts and each part, a conveying means for the recording sheet A such as a pair of conveying rollers and a guide member, or a recording sheet A can be provided as necessary. It has various members such as a sensor for detection that are arranged in a known printer. Further, although not shown, the printer 10 includes a control unit that controls driving and operation of each part.

The printer 10 records an image corresponding to the print size on the recording sheet A, and then cuts the recording sheet A into a print size, thereby obtaining a (finished) print. In the illustrated example, as a preferable mode, as necessary, a plurality of images such as two images and four images are recorded on one recording sheet A, so-called multi-sided printing is performed. Create multiple prints.
Further, in the printer 10, in order to prevent the contamination of the apparatus due to unfixed toner and the adverse effect between the images when a plurality of images are recorded, the image is formed on the recording sheet A with a blank in the periphery. To do. Accordingly, the peripheral portion of the recording sheet A, that is, the leading and trailing ends in the transport direction, and both end portions in the direction orthogonal to the transport direction are blank.
In the following description, for the sake of convenience, the direction perpendicular to the transport direction is defined as the width direction, and the size of the recording sheet A in this direction is defined as the width. Further, the conveyance direction of the recording sheet A is defined as the conveyance direction, and the size of the recording sheet A in the conveyance direction is defined as the length. Furthermore, the front end and the rear end correspond to the transport direction.

The recording sheet supply unit 12 (hereinafter referred to as the supply unit 12) is a part that supplies the cut sheet-like recording sheet A to the image forming unit 14.
In the illustrated example, the supply unit 12 includes two loading portions of a magazine 20 that accommodates a recording sheet roll 20 a formed by winding a long recording sheet A, and a cassette 24 that accommodates a cut sheet-like recording sheet A. And a loading unit.
In the loading section of each magazine 20, recording sheet rolls 20a having different widths (different sizes) are usually accommodated. On the other hand, the cassette 52 is a case for storing the recording sheet A and loading it into the printer, similar to those used in various printers.

The recording sheet A is not particularly limited, and any of various recording sheets (image receiving media) used in an electrophotographic printer can be used.
In particular, a recording sheet (for photographic image quality printing) that can produce a photo-quality print with excellent gloss, such as a recording sheet in which a transparent resin layer made of a thermoplastic resin is formed on the surface of a substrate made of paper or the like. Sheet) is preferred. As an example, this recording sheet is formed by forming a toner image on a transparent resin layer, and then subjecting the toner to a transparent resin by heating and pressing with a belt having excellent surface smoothness (which may also be used for fixing a toner image). By being melted in the layer and then cooled and fixed, a print having excellent gloss like a silver salt photographic print can be produced (see JP-A-5-216322, etc.).

  Although not shown in the drawings, the size of the recording sheet roll 20a (that is, the width (width dimension)) accommodated in the magazine 20 and the cassette 24 are accommodated in each loading unit by a dip switch, a barcode, or the like. Detection means for detecting the size of the recording sheet A and the type of the recording sheet A such as plain paper or the photographic image quality printing sheet is arranged.

A drawer roller pair 22 and a cutter 28 are arranged downstream of each magazine 20 loaded in the loading unit (downstream in the conveyance direction of the recording sheet A).
The drawing roller pair 22 is a roller pair that pulls out a recording sheet from the recording sheet roll 20 a accommodated in the magazine 20. The cutter 28 is a known sheet-like material cutting means such as a guillotine cutter.

The drawing of the recording sheet from the recording sheet roll 20a by the drawing roller pair 22 is stopped when the length of the recording sheet downstream from the cutter 28 reaches a predetermined length. Next, the cutter 28 cuts the recording sheet into a recording sheet A having a predetermined size cut sheet, and supplies the recording sheet A to a predetermined conveying means.
Here, as described above, in the printer 10, an image is formed on the recording sheet A so that the periphery is blank. In the present invention, the image is formed according to the print size (image size) or the like. By adjusting the cut-out length of the recording sheet A, blanks at the leading end and the trailing end (particularly the trailing end) of the recording sheet A may be formed and / or the length of the blank may be adjusted.

  Further, the recording sheet A accommodated in the cassette 24 is pulled out by a known means used in various printers and supplied to a predetermined conveying means.

Both the recording sheet A cut to a predetermined size by the cutter 28 and the recording sheet A drawn from the cassette 24 are conveyed to the image forming unit 14 by a pair of conveying rollers.
A print head 26 that records a back print on the back surface (non-image recording surface) of the print is disposed between the two transport roller pairs immediately upstream of the image forming unit 14.
The print head 26 is not particularly limited, and various known printing means such as an impact printer using an ink ribbon and an ink jet printer can be used.

The image forming unit 14 forms an image on the recording sheet A by electrophotography, and includes an exposure unit 30, a toner image forming unit 32, a transfer unit 34, a primary fixing roller pair 36, and an intermediate conveyance roller pair. 37, a secondary fixing unit 38, and a reversing unit 40.
The image forming unit 14 is related to the image forming apparatus of the present invention, and the transfer position of the image onto the recording sheet A in the transfer unit 34 and the interval (conveyance distance) between the primary fixing roller pair 36 correspond to each other. It is slightly shorter than the recording sheet A having the shortest length, and the interval between the transfer position and the secondary fixing unit 38 is slightly shorter than the corresponding recording sheet A having the longest length. This will be described in detail later.

The exposure unit 30 includes an exposure control unit 42 and an exposure unit 44.
The exposure control unit 42 acquires an image (image data) to be reproduced from an image supply source and performs predetermined image processing, and then the number of images to be recorded on one recording sheet A (number of recording surfaces). Accordingly, an image is assigned to form an image to be recorded on one recording sheet A. As described above, in the printer 10, one or more images are formed on the recording sheet A so that the periphery of each image is blank. Therefore, the exposure control unit 42 satisfies a predetermined interval between the images so as to satisfy this. The image is assigned so that there is a blank space at the leading edge and the trailing edge of the recording sheet A, and both ends in the width direction (hereinafter referred to as side edges).

On the other hand, the exposure unit 44 is a light beam (recording light) light source, an optical deflector, an fθ lens, an optical path changing mirror, and a light beam adjusting light for exposing an electrophotographic photosensitive drum 46 of the toner image forming unit 32 described later. This is a known light beam scanning optical system having the above-described lens.
That is, the exposure unit 44 applies the light beam E modulated according to the image data (that is, the image to be recorded) supplied from the exposure control unit 42 in the width direction (conveyance direction of the recording sheet A (= electrophotographic photosensitive member). The beam is deflected and emitted in the main scanning direction that coincides with the direction orthogonal to the rotation direction of the drum 46), reflected by the mirror 44a and incident on a predetermined exposure position, and a latent image is recorded on the electrophotographic photosensitive drum 46. To do.

The toner image forming unit 32 is a known toner image forming unit by electrophotography, and is an electrophotographic photosensitive drum 46 (hereinafter referred to as a photosensitive drum 46), a charging unit 48, a cleaning unit 50, and a toner supply unit 52. Have
The photosensitive drum 46 is a known electrophotographic photosensitive drum, and rotates in the direction of arrow a (the direction opposite to the conveyance direction of the recording sheet A) with the central axis coinciding with the width direction. As described above, since the light beam E from the exposure unit 44 is deflected in the width direction, the photosensitive drum 46 is two-dimensionally scanned and exposed by the light beam E modulated according to the recorded image.
The toner supply unit 52 supplies a C (cyan) toner supply unit 54C, an M (magenta) toner supply unit 54M, a Y (yellow) toner supply unit 54Y, and a K (black) toner supply to a rotatable drum-shaped main body 52a. The four toner supply portions of the portion 54K are provided at intervals of a rotation angle of 90 °.

  The transfer unit 34 presses the transfer belt 60 against the photosensitive drum 46 from the inside, a transfer belt 60 that is an endless belt partly contacting the photosensitive drum 46, three rollers 62 that stretch the transfer belt 60, and the inside. A pressing roller 64, a transfer roller 66, and a conveyance guide 68 are included. The transfer belt 60 is an intermediate transfer member for a toner image, and rotates in the direction of arrow b (the same direction as the conveyance direction of the recording sheet A). Further, the transfer roller 66 is movable together with one of the rollers 62 to a position where the transfer belt 60 (recording sheet A) is sandwiched and a position where the transfer roller 60 is separated from the transfer belt 60.

The photosensitive drum 46 is uniformly charged in the width direction by the charging means 48 while rotating in the direction of arrow a in the figure, and is scanned two-dimensionally by the light beam E modulated according to the image data as described above. Exposure is performed to form an electrostatic latent image. Next, the electrostatic latent image is developed by a toner supply unit, for example, a Y toner supply unit 54Y, located at the development position of the toner supply unit 52 (a position facing the photoconductive drum 46), and the surface of the photoconductive drum 46 is developed. A Y toner image is formed.
Further, the transfer belt 60 that is partly in contact with the photosensitive drum 46 and pressed by the pressing roller 64 rotates in the direction of arrow b in synchronization with the rotation of the photosensitive drum 46. Accordingly, the toner image of the photosensitive drum 46 developed by the toner supply means 52 is transferred to the transfer belt 60 at this contact portion (pressing portion by the pressing roller 64). In the region where the transfer of the toner image onto the transfer belt 60 of the photoconductive drum 46 is completed, the remaining toner is removed by the cleaning unit 50.

In the illustrated example, such toner image formation and transfer to the transfer belt 60 are performed by supplying four toners including a Y toner supply unit 54Y, an M toner supply unit 54M, a C toner supply unit 54C, and a K toner supply unit 54K. The parts are operated sequentially.
For example, after the Y toner image is transferred to the transfer belt 60 as described above, the toner supply means 52 (main body 56a) is then rotated by 90 ° in the direction of the arrow c, so that the M toner supply unit 54M is positioned at the development position. Then, the toner image is aligned with the Y toner image on the transfer belt 60, and similarly, a latent image is formed on the photosensitive drum 46 to form an M toner image and transferred to the transfer belt 60. Thereafter, similarly, the C toner image is transferred to the transfer belt, and the K toner image is transferred to the transfer belt. During this time, the transfer roller 66 is separated from the transfer belt 60.
Therefore, in the illustrated example, toner images of Y, M, C, and K are formed in alignment on the surface of the transfer belt 60, that is, four (full) color images are formed.

On the other hand, a cut sheet-like recording sheet A having a predetermined size is supplied from the supply unit 12 and waits at a registration roller pair 70 immediately upstream of the transfer roller 66, for example.
When a color image is formed on the transfer belt 60, the recording sheet by the registration roller pair 70 is synchronized with the rotation of the transfer belt 60 so that the recording sheet A and the color image formed on the transfer belt 60 are aligned. The conveyance of A is started, the transfer roller 66 is pressed against the transfer belt 60 (roller 62), and the recording sheet A is nipped and conveyed between the transfer belt 60 and the transfer roller 66. By this nipping and conveying, the four color toner images formed on the surface of the transfer belt 60 are transferred to the recording sheet A, and an image is formed on the surface of the recording sheet A.

  As described above, this image is impositioned according to the number of images to be recorded, and since the periphery of each image is imprinted so that no image is recorded, the recording sheet A A predetermined blank is formed around each image formed (transferred), and the front and rear ends and both side ends of the recording sheet A are blank.

The recording sheet A on which an image has been formed is guided by the conveyance guide 68 and conveyed to the primary fixing roller pair 36.
The primary fixing roller pair 36 is a pair of conveyance rollers, at least one of which is a heating roller, and moves away from the roller 36a on the image recording surface side (upper side in the illustrated example) of the recording sheet A, thereby separating the rollers. Thus, the pressure state (fixed state) can be released.
The recording sheet A on which the toner image is formed is heated / pressurized while being nipped and conveyed by the primary fixing roller pair 36, and the toner image is fixed to the recording sheet A. In the printer 10 according to the present invention, the primary fixing roller pair 36 uses the shortest length photographic quality print sheet as the recording sheet A, and uses plain paper as an image. The recording sheet A is heated / pressurized and fixed only when recording.
This will be described in detail later.

The reversing unit 40 is a part for reversing the recording sheet A on which an image is recorded on one side in order to create a so-called double-sided print, and includes a first switching unit 72 disposed downstream of the primary fixing roller pair 36 and a primary switching unit 72. A branch path 74 branched from the conveying path from the fixing roller pair 36, a kickback section 76 provided downstream of the branch path 74, and branched from the branch path 74 and the kickback section 76, and upstream of the transfer section 34. And a second transfer means 80 provided at a branch point between the kickback portion 76 and the return transfer path 78.
Both the first switching means 72 and the second switching means 80 act on (insert into) the conveyance path, and transport a known sheet-like material such as a flapper that guides the recording sheet A to the predetermined conveyance path. Switching means.

In the printer 10, when creating double-sided printing, the first switching unit 72 acts on the conveyance path from the primary fixing roller pair 36 to send the recording sheet A to the branch path 74, and the kickback section 76 from the branch path 74. When the upstream end of the recording sheet A reaches the downstream side of the second switching means 80, the conveyance is stopped.
Next, the second switching unit 80 is applied to the kickback unit 76, and the recording sheet A is conveyed in the reverse direction in the kickback unit 76, and is guided by the second switching unit 80 to return and convey the recording sheet A. The recording sheet is turned upside down by being sent to the path 78 and conveyed from the return conveying path 78 to the registration roller pair 70.

  Such a reversing unit 40 may be provided not from the downstream of the primary fixing roller pair 36 (primary fixing unit) but from the downstream of the secondary fixing unit 38.

An intermediate conveyance roller pair 37 is disposed downstream of the primary fixing roller pair 36 (a branch point to the reversing unit 40). The intermediate conveyance roller pair 37 conveys the recording sheet A conveyed by the transfer unit 34 and the primary fixing roller pair 36 to the downstream secondary fixing unit 38.
In the illustrated example, the number of intermediate conveyance roller pairs 37 is one. However, the intermediate conveyance roller pair 37 applies to all corresponding lengths of the recording sheet A according to the distance between the primary fixing roller pair 36 and the secondary fixing unit 38 and the length of the corresponding recording sheet A. Of course, a plurality of primary fixing roller pairs 36 and secondary fixing portions 38 may be provided so that the conveyance described later can be performed properly.

As shown in FIG. 2, in the printer 10, the intermediate conveyance roller pair 37 includes a long roller 82 having an axial length larger than the maximum width recording sheet A, and the recording sheet A together with the long roller 82. It has two short rollers 84 for nipping and conveying.
In the intermediate conveyance roller pair 37, the long roller 82 is a driving roller, and the short roller 84 is a driven roller. Further, the long roller 82 is disposed on the lower side (non-image forming surface side), and the short roller 84 is disposed on the upper side.

In the illustrated example, the recording sheet A is positioned in the width direction of the recording sheet A by a so-called center resist in which the center in the width direction coincides with the center in the width direction of the conveyance path.
The distance between the two short rollers 84 can be changed by separating the two short rollers 84 in the width direction (the arrow y direction in FIG. 2 and the arrow x in the transport direction) by the same distance from the center in the width direction indicated by a one-dot chain line in FIG. It has become. In the illustrated example, the intermediate conveyance roller pair 37 thereby corresponds to the recording sheets A having various widths.
Here, as described above, in the printer 10, the recording sheet A before being cut (transferred) on which the image is recorded is blank on both side edges. The intermediate conveying roller pair 37 adjusts the interval of the short rollers 84 according to the position information of the image on the recording sheet A (image recording position information by the exposure unit 44) in addition to the width information of the recording sheet A, and will be described later. As shown in FIG. 3, the short roller 84 sandwiches the blank portion at the side end of the recording sheet A. This prevents adverse effects on the image transferred to the recording sheet A and contamination with unfixed toner.

Further, the short roller 84 moves up and down as indicated by an arrow z in FIG. 2 so as to be able to contact / separate from the long roller 82, that is, it can be in a sandwiched state and a released state.
Here, in the printer 10 of the illustrated example, as a preferable aspect, the intermediate conveyance roller pair 37 moves the short roller 84 downward from the released state at a stroke and enters the clamping state, and gradually moves the short roller 84 from the released state. Thus, both operations are possible, that is, moving downward from the released state to the sandwiched state. This will be described in detail later.

The method for bringing the two short rollers 84 close to and away from each other with respect to the center in the width direction is not particularly limited, and various known methods can be used. For example, a method of screwing a frame supporting the short roller 84 to a shaft forming a reverse screw, and supporting the short roller 84 in a portion where the moving directions of the timing belt stretched around two pulleys are opposite to each other. Various known methods such as a method of fixing the frame to be performed can be used.
Further, the method for bringing the short roller 84 into the released state and the sandwiched state is not particularly limited. For example, two short rollers 84 (frames that pivotally support the short roller 84) that can be brought into contact with and separated from each other as described above are used. Various methods known in the art such as a method of holding the unit and urging the unit to the long roller 82 side with a spring or the like and swinging the unit up and down using a cam or the like can be used. is there.

  In the present invention, the intermediate conveyance unit may use a belt conveyor instead of the long roller 82, and the belt conveyor and the short roller 84 may sandwich and convey the recording medium A.

A secondary fixing unit 38 is disposed downstream of the intermediate conveyance roller pair 37.
The secondary fixing unit 38 includes a heating roller 85, a roller 86, a secondary fixing belt 88 that is an endless belt stretched around the heating roller 85 and the roller 86, a cooling unit 90 that is included in and in contact with the secondary fixing belt 88, The heating roller 85 includes a nip roller 92 that sandwiches the secondary fixing belt 88.
The heating roller 85 is a known heating roller that includes a heat source having a calorific value corresponding to a recording sheet heating process described later. The secondary fixing belt 88 is a belt having a very high surface (outer surface) smoothness.

  The secondary fixing unit 38 heats the recording sheet A when creating a high-quality print having glossiness corresponding to a silver salt photograph using the above-described photographic quality printing sheet as the recording sheet A. / Surface treatment by pressing and image fixing treatment are performed.

More specifically, the recording sheet A (the photographic quality print recording sheet) onto which the image (toner image) has been transferred in the transfer unit 34 is nipped and conveyed by the secondary fixing belt 88 (heating roller 88) and the nip roller 92. Thus, the recording sheet A is heated / pressurized, and then cooled by the cooling unit 90. Thereby, the thermoplastic resin or further toner on the surface of the recording sheet A is first melted, and then the melted thermoplastic resin or further toner is cooled / solidified to be fixed.
At this time, the surface properties of the secondary fixing belt 88 are transferred by melting / cooling / solidifying the thermoplastic resin on the surface of the recording sheet A while being conveyed under pressure. Here, as described above, the secondary fixing belt 88 has very high surface smoothness. Therefore, the recording sheet A has a high surface smoothness and good glossiness, and from this recording sheet A, a print having the same quality as a silver salt photographic print can be obtained.

In the illustrated printer 10, the heating condition and / or the cooling condition in the secondary fixing unit 38 can be adjusted, thereby making it possible to adjust the glossiness applied to the surface of the recording sheet A (print). May be.
Further, by selecting the surface property of the secondary fixing belt 88, so-called mat processing may be performed instead of gloss processing.

  As described above, in the printer 10, the primary fixing roller pair 36 (primary fixing unit) is disposed downstream of the transfer unit 34 that transfers the image to the recording sheet A, and the secondary fixing unit is downstream of the primary fixing roller pair 36. 38 is disposed, and an intermediate conveyance roller pair 37 is disposed between the primary fixing roller pair 36 and the secondary fixing unit 38.

Here, the image transfer position to the recording sheet A in the transfer section 34 (that is, the contact position (end position of the recording sheet A) between the endless belt 60 (roller 62) and the transfer roller 66), and the primary fixing roller pair 36. The distance from (the sandwiching position of the recording sheet A) is slightly shorter than the length of the corresponding recording sheet A having the shortest length. That is, the conveyance distance of the recording sheet A from the image transfer position to the recording sheet A to the primary fixing roller pair 36 is slightly shorter than the length of the recording sheet A having the shortest length.
The interval between the image transfer position and the secondary fixing portion (the contact position between the nip roller 92 and the endless belt 88 (heating roller 85) (the holding position of the recording sheet A)) is the corresponding maximum length size. It is slightly shorter than the length of the recording sheet A. That is, the conveyance distance of the recording sheet A from the image transfer position to the recording sheet A to the secondary fixing unit 38 is slightly shorter than the length of the longest recording sheet A.
Further, as described above, the recording sheet A to which the image has been transferred in the transfer unit 34 has blanks at the leading end and the trailing end, and at both side ends.

  The image forming apparatus according to the present invention has such a configuration in image formation including an image transfer process and a fixing process, so that a photographic quality print using the above-described recording sheet for photographic quality prints can be obtained. Corresponding to applications that require creation of high-quality prints, image quality deterioration due to banding can be prevented, and high-quality prints can be stably produced. Further, since the conveyance distance between the image transfer position and the secondary fixing unit is set according to the recording sheet A having the longest length, the size of the apparatus is not increased.

  The operation of fixing the image transferred to the recording sheet A in the printer 10 will be described below in detail with reference to the conceptual diagram shown in FIG. 3 to describe the above configuration and the image forming apparatus of the present invention in detail. .

First, when recording an image on a recording sheet A _min that is a photographic image quality printing sheet and has the shortest length, both the primary fixing roller pair 36 and the intermediate conveying roller pair 37 are held in a sandwiched state. _Amin image fixing and conveyance are performed.
The recording sheet A _min is transferred with an image by the transfer unit 34, and then the leading end reaches the primary fixing roller 36.

Here, as described above, the conveyance distance L1 of the recording sheet A from the image transfer position to the recording sheet A to the primary fixing roller pair 36 is slightly shorter than the length of the shortest recording sheet _Amin . Further, the trailing edge (also the leading edge in the illustrated example) of the recording sheet A to which the image has been transferred is blank. Therefore, as schematically shown in FIG. 3, when the leading end of the recording sheet A _min having the shortest length is sandwiched between the primary fixing roller pair 36, the transfer unit 34 displays an image (hatched area) on the recording sheet A _min . Is completed, and the transfer roller 66 and the transfer belt 60 (roller 62) sandwich the blank portion at the rear end of the recording sheet _Amin (in other words, a position where this is realized). To transfer the image).
Accordingly, the recording sheet A _min can be properly conveyed to the primary fixing roller pair 36, and even if the leading edge of the recording sheet A _min enters / nips between the primary fixing roller pair 36 and a load fluctuates, the transfer is not performed at this time. Since it has been completed, image unevenness due to banding does not occur.

The recording sheet A _min on which the image is fixed by the primary fixing roller pair 36 is then nipped and conveyed by the intermediate conveyance roller pair 37 and conveyed to the secondary fixing unit 38. The recording sheet A _min conveyed to the secondary fixing unit 38 is heated / pressurized and cooled by being nipped and conveyed between the secondary fixing belt 88 (heating roller 88) and the nip roller 92 as described above. Surface treatment and secondary fixing are performed and conveyed downstream.
In this case, it is preferable that the position in the width direction of the short roller 84 of the intermediate conveyance roller pair 37 sandwich the blank portion at the side edge according to the width information of the recording sheet A and the position information of the image. This is not limited.

On the other hand, when an image is recorded on the longest length recording sheet A _max with a photographic image quality print sheet, the primary fixing roller pair 36 and the intermediate conveyance roller pair 37 are separated from each other as shown by a dotted line in FIG. In the nipping and releasing state, the image is transferred.
Accordingly, the recording sheet A _max on which the image is transferred by the transfer unit 34 passes through the primary fixing roller 36 and the intermediate conveyance roller pair 37, and the leading end reaches the secondary fixing unit 38.

Here, as described above, the conveyance distance L2 of the recording sheet A from the image transfer position to the recording sheet A to the secondary fixing unit 38 is slightly shorter than the length of the longest recording sheet _Amax . Further, the trailing edge (also the leading edge in the illustrated example) of the recording sheet A to which the image has been transferred is blank. Therefore, as schematically shown in FIG. 3, the leading end of the longest recording sheet _Amax is sandwiched between the nip roller 92 and the secondary fixing belt 88 (heating roller 85) of the secondary fixing unit 38, as in the previous example. At this point, the transfer unit 34 has finished transferring the image to the recording sheet _Amax , and the transfer roller 66 and the transfer belt 60 (roller 62) sandwich the blank portion at the rear end of the recording sheet _Amax. (In other words, the image is transferred to a position where this is realized).
Accordingly, the recording sheet _Amax can be properly conveyed to the secondary fixing unit 38, and even if the leading end of the recording sheet _Amax enters / clamps the secondary fixing unit 38 and a load fluctuation occurs, the transfer is not performed at this time. Since it has been completed, image unevenness due to banding does not occur.

That is, in the present invention, the transport distance from the image transfer position to the primary fixing roller 36 is slightly shorter than the length of the shortest recording sheet A _min , and the transport distance from the image transfer position to the secondary fixing unit 38 is “Slightly shorter than the length of the longest recording sheet A _max ” means that the conveying distance is shorter than the length of the blank portion at the rear end of the recording sheet A (to realize this, the recording sheet A Control the transfer position of the image.

The recording sheet A _max conveyed to the secondary fixing unit 38 is nipped and conveyed between the secondary fixing belt 88 (heating roller 88) and the nip roller 92 in the secondary fixing unit 38 as described above, so that After being pressurized and cooled, surface treatment and fixing are performed, and the sheet is conveyed downstream.
When an image is recorded on the longest recording sheet A _max , the position in the width direction of the short roller 84 of the intermediate conveyance roller pair 37 is recorded according to the width information of the recording sheet A and the position information of the image. The sheet A _max is positioned in the blank portion at the side edge of the sheet A _max , and when the transfer in the transfer unit 34 is completed, the short roller 84 is lowered, and the recording sheet A _max is nipped and conveyed by the intermediate conveyance roller pair 37. May be.

Further, the recording sheet A is a photographic image printing sheet having a length that is longer than the shortest length recording sheet A _min and shorter than the longest length recording sheet A _max (hereinafter referred to as an intermediate length). When recording an image in _mid , similarly, as indicated by a dotted line in FIG. 3, the primary fixing roller pair 36 and the intermediate transport roller pair 37 are both set in a separated (clamping released) state. Further, according to the width information of the recording sheet A and the position information of the image, the position in the width direction of the short roller 84 of the intermediate conveyance roller pair 37 is positioned in the blank portion at the side end of the recording sheet _Amax .

In this state, the recording sheet A _mid on which the image is transferred by the transfer unit 34 passes through the primary fixing roller 36 and the leading end reaches the intermediate conveyance roller pair 37.
Here, when an image is recorded on the intermediate-length recording sheet A _mid , three types of operations (modes) are exemplified as the operation of the intermediate conveyance roller pair 37.

First, in the first mode, even if the leading end of the recording sheet A _mid reaches the intermediate conveying roller pair 37, the intermediate conveying roller 37 is not sandwiched, and the transfer is performed in the same manner as the recording sheet A _min and the recording sheet A _max. When the image transfer in the portion 34 is completed and the blank portion at the rear end of the recording sheet _Amax is sandwiched between the transfer roller 66 and the transfer belt 60 (roller 62), the lowermost part of FIG. As shown in FIG. 6, the short roller 84 is lowered to place the intermediate conveyance roller pair 37 in a sandwiched state, and the recording sheet A _mid is conveyed by the intermediate conveyance roller pair 37.
Also in this method, since the clamping by the intermediate conveyance roller pair 37 is after the image transfer is completed, the occurrence of image unevenness due to banding can be prevented.

In the second mode, after the leading edge of the recording sheet A _mid having an intermediate length passes through the intermediate conveyance roller pair 37 due to the end of the transfer in the transfer unit 34, the intermediate conveyance roller pair 37 is moved at a predetermined timing. The short roller 84 is gradually lowered to be nipped, and the recording sheet A _mid is conveyed by the intermediate conveying roller pair 37.
Even in this method, since the recording sheet A _mid is clamped after the leading edge has passed, and the short roller 84 is gradually lowered and clamped, image unevenness due to banding can be prevented.

As shown in FIG. 4, the third mode corresponds to a case where a plurality of images are allocated and recorded in the transport direction (length direction).
In this mode, after the leading edge of the intermediate-length recording sheet A _mid reaches the intermediate conveyance roller pair 37, as indicated by a dotted line in FIG. 4, when the space between the images in the conveyance direction reaches the image transfer position, The short roller 84 is lowered to place the intermediate conveyance roller pair 37 in a sandwiched state, and the recording sheet A _mid is conveyed by the intermediate conveyance roller pair 37.
Also in this method, since the intermediate conveyance roller pair 37 is nipped other than during transfer, the occurrence of image unevenness due to banding can be prevented. In addition, since these images are finally cut and removed by the cutting / arranging section 16, even if there is any inconvenience between these images, there is no influence on the product quality of the print. .

In the present invention, when an image is recorded on the recording sheet A _mid having an intermediate length, only one of the first mode and the second mode may be performed. Any of the second modes may be selectable.
Further, the third mode may not be set, and the third mode may be set and selectable when it can be implemented.

When an image is recorded on the recording sheet A _mid having an intermediate length, in the second mode and the third mode, the recording sheet A _mid is nipped and conveyed by the intermediate conveying roller pair 37 during image transfer in the transfer unit 34. Result. Therefore, the nipping and conveying by the intermediate conveying roller pair 37 may cause a load fluctuation on the nipping and conveying by the transfer belt 60 and the transfer roller 66 in the transfer unit 34, and banding may occur.
In order to prevent such inconvenience, a method in which the clamping force of the intermediate conveyance roller pair 37 is sufficiently weaker than the clamping force in the transfer unit 34 (the intermediate conveyance roller pair 37 merely conveys the recording sheet A). Therefore, a strong clamping force is not required.) The intermediate conveyance roller pair 37 during transfer can be obtained by providing a long-way roller 82 that is a driving roller of the intermediate conveyance roller pair 37 with a one-way clutch that can idle in the conveyance direction. It is preferable to prevent the transfer portion 34 from being subjected to load fluctuations and more reliably prevent banding. Further, by adopting such a configuration, the burden on the secondary fixing unit 38 that performs the surface treatment of the recording sheet A is reduced, and the recording caused by the slip between the recording sheet A and the secondary fixing belt 88 is performed. It is possible to prevent deterioration in the quality of the surface of the sheet A.

When an image is recorded on the recording sheet A _mid having an intermediate length as described above, the transfer unit 34 moves the recording sheet A when the leading edge of the recording sheet A reaches the intermediate conveyance roller pair 37 as necessary. The cutting length of the recording sheet A in the supply unit 12 may be adjusted, or the image forming position on the recording sheet A may be adjusted so that A is sandwiched.

When an image is formed by using plain paper that is not a photographic quality print sheet as the recording sheet A, in many cases, such high image quality is not required.
Therefore, in this case, regardless of the length of the recording sheet A, the primary fixing roller pair 36 and the intermediate conveyance roller pair 37 are both held, and after the image is transferred in the transfer unit 34, the primary fixing roller pair The primary fixing by 36 and the conveyance by the intermediate conveyance roller pair 37 are performed. In addition, since the surface treatment and the fixing process in the secondary fixing unit 38 are not necessary for print production using plain paper, the secondary fixing unit 38 does not heat the heating roller 85 and performs cooling by the cooling unit 90, for example. The recording sheet A is allowed to pass through without any processing such as not performing. Alternatively, if the cutting process in the subsequent cutting / arranging unit 16 is not necessary, it may be output as a print on a predetermined tray immediately after the fixing by the primary fixing roller pair 36 is completed.

When a high-quality image is required for image formation on plain paper, the longest recording sheet A _max , the shortest recording sheet A _min , and the intermediate length recording sheet A _mid are both _displayed in the photograph. Fixing may be performed in the same manner as the image quality printing sheet.

As is apparent from the above description, in the image forming apparatus of the present invention, the primary fixing roller pair 36 is not necessarily required for creating a print using a photographic quality print sheet. Further, fixing on plain paper can also be performed by the secondary fixing unit 38.
However, in consideration of peripheral contamination with toner, ease of conveyance and handling of the recording sheet A, stabilization of image quality, etc., it is preferable to fix the image as soon as possible after the image is transferred to the recording sheet A. That is, in the present invention, the provision of the primary fixing roller pair 36 (primary fixing unit) makes it possible to create a print on the shortest recording sheet A or plain paper (recording sheet that does not require secondary fixing). And improved stability.

In a normal printer 10, the longest length and the shortest length of the recording sheet A are not different depending on the type of the recording sheet A. That is, normally, the longest length and the shortest length are the same for both plain paper and photographic quality print sheets.
However, in the image forming apparatus of the present invention, when the longest length and / or the shortest length differs depending on the type of recording sheet A, the highest quality is required in the printer 10 such as a photographic quality print sheet. It is preferable to set the transport distance between the image transfer position and the primary fixing unit and / or the secondary fixing unit according to the shortest length and the longest length of the recording sheet A of the type.

In the illustrated example, for the purpose of preventing contamination with toner and the like, as a preferred mode, there are blank portions at all of the four periphery of the front end, rear end, and both side ends of the recording sheet A.
However, the present invention is not limited to this, and when an image is recorded on the recording sheet A having the longest length and the shortest length, the leading edge and the blank on the both ends may be eliminated (that is, the blank is a trailing edge). Only the edge is acceptable). Further, when an image is recorded on the recording sheet A having an intermediate length, the leading end blank may be eliminated (the rear end and the side end only may be used).
Depending on the clamping method and timing by the intermediate conveyance roller pair 37, the space between the images when performing the multiple imposition is not necessarily required.

  Further, in the image forming apparatus of the present invention, the image recording method is not limited to the electrophotography as shown in the example, and a latent image is recorded on a transfer sheet having a color material layer by means of heating or exposure, and this latent image is recorded. Various image recording methods having an image transfer process to a recording sheet (image receiving medium) and a fixing process after transfer, such as image recording by peeling transfer for fixing after transferring an image to a recording sheet, can be used. is there.

The recording sheet A that has been processed by the secondary fixing unit 38 is then conveyed to the cutting / arranging unit 16.
The cutting / arranging unit 16 includes a position adjusting unit 100, a cutting unit 102, an arranging unit 104, and a discharge unit 106.

The recording sheet A conveyed to the cutting / arranging unit 16 is first set to a predetermined position in the width direction in the position adjusting unit 100.
As described above, in the printer 10, one or more images are impositioned on the recording sheet A in a state having a blank around the recording sheet A. In response to this, the printer 10 cuts the recording sheet A in the width direction and the conveyance direction according to the print size of the print to be created in the cutting unit 102 described later, and forms individual prints. The position adjustment unit 100 is a part that adjusts the position in the width direction of the recording sheet A on which an image is formed to a predetermined position in order to perform this cutting appropriately.

There are no particular limitations on the position adjustment means in the width direction of the recording sheet A in the position adjustment unit 100, and various known position adjustment means for sheet-like materials can be used.
As an example, there is a method of using a guide plate that abuts the side edge of the recording sheet A and regulates the position in the width direction, and has an axial position adjustment function that moves in the width direction with the recording sheet A being sandwiched. Examples include a method using a pair of transport rollers.

The recording sheet A whose position in the width direction has been adjusted by the position adjusting unit 100 is then cut by the cutting unit 102 in accordance with the print size, and is set as a print P (hard copy) output as a product.
The cutting unit 102 includes a first slitter 110 and a second slitter 112, a guillotine cutter 114, and a registration roller pair 116.

Each of the first slitter 110 and the second slitter 112 cuts the recording sheet A in the transport direction, and is a known slitter using, for example, a rotary cutter or a circular cutter.
Both the first slitter 100 and the second slitter 112 are composed of two cutters arranged in the width direction at the same position in the transport direction and capable of adjusting the position in the width direction. Further, the second slitter 112 is disposed downstream of the first slitter 100.
Both the first slitter 100 and the second slitter 102 are transported by moving each cutter in the width direction according to the width information of the recording sheet A and the position information of the image (position information in the width direction). The recording sheet A is cut in the conveyance direction, and is cut out to the size in the width direction of the print for creating the recording sheet A.

In the illustrated example, the printer 10 records a maximum of two images in the width direction (performs a maximum of two faces).
As shown in FIG. 5A, when two images are recorded in the width direction (arrow y direction), each cutter of the first slitter 110 is converted into one image in the width direction, for example, the conveyance direction (arrow x direction). the corresponding place on the left side of the image, and taken along line Cx ₁ while conveying the recording sheet a, is cut corresponding to the size of the corresponding image printed in the width direction. The second slitter 112 of the downstream, the other images of the respective cutter width direction, that is, arranged corresponding to the right side of the image in the conveying direction, along line Cx ₂ while conveying the recording sheet A Then, the corresponding image is cut corresponding to the size in the width direction of the print.
That is, first, the first slitter 110 cuts out an image on the left side in the conveyance direction, and then the second slitter 112 cuts out the image on the right side.

On the other hand, as shown in FIG. 5B, when one image is recorded in the width direction, the second slitter 112 is retracted from the conveyance path of the recording sheet A, and each cutter of the first slitter 110 is moved to the recording sheet A. and arranged corresponding to the image recorded in the recording sheet while conveying the a, and taken along line Cx _1, to cut in response to the size of the corresponding image printed in the width direction.

The guillotine cutter 114 is a known guillotine cutter that cuts the recording sheet A in the width direction.
The registration roller pair 116 stops the conveyance of the recording sheet A at the cutting position by the guillotine cutter 114 according to the position information (position information in the conveyance direction) of the image of the recording sheet A. A pair of conveying rollers that perform cutting positioning.

For example, as shown in FIG. 5A, when two images are recorded in the conveying direction, the registration roller pair 116 _first uses the guillotine cutter 114 so that the cutting line Cy ₁ on the leading end side of the leading end side image is When the cutting position is reached, the conveyance of the recording sheet A is stopped. Next, the guillotine cutter 114 is operated to cut the recording sheet A at the cutting line Cy ₁ .
After cutting, the registration roller pair 116 resumes the conveyance of the recording sheet A, at the time when the cutting line Cy ₂ on the rear end side of the image becomes cutting position by the guillotine cutter 114, to stop the conveyance of the recording sheet A . Next, similarly, the guillotine cutter 114 is operated to cut the recording sheet A at the cutting line Cy ₁ . Here, the cutting portion 102, since the cut recording sheet A along the line Cx ₁ and the cutting line Cx ₂ by the first slitter 110 and the second slitter 112 first, by cutting with the guillotine cutter 114, the distal end Cut out two prints P on the side.

In the same manner, after cutting, the registration roller pair resumes conveyance of the recording sheet A, conveying at the time when the cutting line Cy ₃ of the distal end side of the second image in the conveyance direction reaches the cutting position by the guillotine cutter 114 Then, the guillotine cutter 114 cuts the recording sheet A at the cutting line Cy ₃ , and then the transport is resumed and the transport is stopped when the rear end side cutting line Cy ₄ reaches the cutting position. guillotine cutter 114 cuts the recording sheet a along the cutting line Cy _4.
As a result, similarly to the above, cutting along the cutting line Cx ₁ and cutting line Cx ₂ and cutting out the two prints P on the rear end side, from the four images recorded on the recording sheet A, four sheets corresponding to the print size Cut out the print P.

On the other hand, as shown in FIG. 5B, when one image is recorded in the conveyance direction, the registration roller pair 116 has the cutting line Cy ₁ on the leading end side of the image at the cutting position by the guillotine cutter 114. At that time, the conveyance of the recording sheet A is stopped, and then the guillotine cutter 114 is operated to cut the recording sheet A at the cutting line Cy ₁ .
After cutting, the registration roller pair 116 resumes the conveyance of the recording sheet A, at the time when the cutting line Cy ₂ in the rear end side of the image becomes cutting position by the guillotine cutter 114, to stop the conveyance of the recording sheet A, Similarly, the guillotine cutter 114 is actuated to cut the recording sheet a along the cutting line Cy _2. As described above, the cutting portion 102, since the cut recording sheet A by the first slitter 110 ahead along line Cx _1, by cutting with the guillotine cutter 114, from one image recorded on the recording sheet A Cut out one print according to the print size.

  The print P cut (cut out from the recording sheet A) by the cutting unit 102 is then conveyed to the arrangement unit 104 and is conveyed from the arrangement unit 104 to the discharge unit 106.

The arrangement unit 104 discharges the print P cut by the cutting unit 102 to the discharge unit 106. Here, when two images are recorded in the width direction on the recording sheet A, the arrangement unit 104 arranges two rows of prints P in the width direction into one row (single row), and outputs the discharge unit 106. To discharge. In the illustrated example, the arrangement unit 104 includes a carry-in roller pair 120, conveyance roller pairs 122, 124 and 132, a discharge roller pair 126, and a single-row roller pair 130.
The discharge unit 106 is a belt conveyor including two rollers 140 and an endless belt 142 stretched around the rollers 140.

The carry-in roller pair 120 of the arrangement unit 104 includes two roller pairs 120 a and 120 b that are arranged in the width direction and can be driven independently of each other.
The one roller pair 120a of the carry roller pair 120 corresponds to the first slitter 110 of the cutting line Cx ₁ cut by the print P (the width direction position) at the time of recording the 2 images in the width direction. The other roller pair 120b corresponds to the second slitter cutting lines Cx ₂ cut by 112 printing P (same as above).

The arrangement unit 104 branches downstream of the carry-in roller pair 120, and includes a lower first conveyance path 134 configured by the conveyance roller pairs 122 and 124, a single-row roller pair 130, and a conveyance roller pair 132. And an upper second transport path 136. The single-row roller pair 130 in the second transport path 136 is a transport roller pair movable in the width direction.
The first conveyance path 134 corresponds to the conveyance path of the roller pair 120a and the roller pair 120b of the carry-in roller pair 120, and the second conveyance path 136 corresponds to the conveyance path of the roller pair 120b. In addition, a guide member (not shown) that guides the print P to the first transport path 134 by acting on the transport path from the roller pair 120a or the roller pair 120b is disposed at the branch position of both transport paths.
Further, the two conveyance paths are joined by a guide member or the like (not shown) downstream of the conveyance roller pair 124 and the conveyance roller pair 132 to reach the discharge roller pair 126.

As shown in FIG. 5A, when two images are recorded in the width direction, the guide member is applied only to the conveyance path from the roller pair 120a of the carry-in roller pair 120.
When the two rows of prints P are conveyed in the cut width direction, the arrangement unit 104 conveys the prints P cut by the first slitter 110 to the first conveyance path 134 by the roller pair 120a and the guide member. On the other hand, the print P cut by the second slitter 112 is conveyed to the second conveyance path 136 by the roller pair 120b.

  In the first transport path 134, the transported print P is transported by transport roller pairs 122 and 124 and sent to the discharge roller pair 126, and the discharge roller pair 126 discharges the print P to the discharge unit 106.

  On the other hand, in the second transport path 136, transport of the transported print P is stopped when the single row roller pair 130 pinches and is separated from the roller pair 120b (the roller pair 120b is also stopped). Next, the single row roller pair 130 is moved in the width direction, and the print P is moved to the position in the width direction corresponding to the roller pair 120a. After the movement in the width direction, the single-row roller pair 130 and the conveyance roller pair 132 are placed so that the print P supplied to the first conveyance path 134 is fed to the conveyance roller pair 126 at the same timing and enters behind it. Then, the conveyance of the print P is started and sent to the discharge roller pair 126. Next, the discharge roller pair 126 discharges the print P to the discharge unit 106.

In the example shown in FIG. 5A, two prints P are also formed in the transport direction.
In this case, the single-row roller pair 130 moves in the opposite direction to the front in the width direction when the previous print P leaves, returns to the original position, and then resumes conveyance by the roller pair 120b. And sent to the second transport path 136. The second transport path 136 transported the print P stops the transport of the print P when the single-row roller pair 130 sandwiches the print P and leaves the roller pair 120b. The printing roller pair 130 is moved in the width direction to move the print P to the position in the width direction corresponding to the roller pair 120a, and then the print P is conveyed by the single-row roller pair 130 and the conveying roller pair 132. The paper is discharged to the discharge unit 106 by the conveyance roller pair 126.
As a result, a plurality of rows of prints P are made into a single row in the width direction and discharged to the discharge unit 106.

On the other hand, as shown in FIG. 5B, when one image is recorded in the width direction, the above-described guide member is applied to the conveyance path from both the roller pairs 120a and 120b.
When the cut print P is conveyed, in the arrangement unit 104, the carry-in roller pair 120 (driven in synchronization with the roller pairs 120a and 120b) and the guide member convey the print P to the first conveyance path 134. In the first conveyance path 134, the print P is conveyed by the conveyance roller pairs 122 and 124 and sent to the discharge roller pair 126, and the discharge roller pair 126 discharges the print P to the discharge unit 106.

  When the discharge unit 106 receives and stacks the prints P that have been transported / discharged by the discharge roller pair 126 on the belt conveyor and stacks the prints by sorting information or the like, A predetermined number of times set according to (maximum length of a matter) is conveyed to the stack of prints P and stopped, and then the next matter of prints P is received.

  The image forming apparatus of the present invention has been described in detail above. However, the present invention is not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the gist of the present invention. Of course.

1 is a conceptual diagram of an example of a printer that uses an image forming apparatus of the present invention. FIG. 2 is a schematic perspective view of an intermediate conveyance roller pair of the printer shown in FIG. 1. FIG. 2 is a conceptual diagram for explaining a fixing operation in the printer shown in FIG. 1. It is a conceptual diagram for demonstrating another example of the effect | action of the fixing in the printer shown in FIG. (A) And (B) is a conceptual diagram which shows an example of the image recording in the printer shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printer 12 (Recording sheet) supply part 14 Image formation part 16 Cutting / arrangement part 20 Magazine 22 Pull-out roller pair 24 Cassette 26 Print head 28 Cutter 30 Exposure part 32 Toner image formation part 34 Transfer part 36 Primary fixing roller pair 37 Intermediate conveyance Roller pair 38 Secondary fixing unit 40 Reversing unit 42 Exposure control unit 44 Exposure unit 46 (Electrophotography) Photosensitive drum 48 Charging unit 50 Cleaning unit 52 Toner supply unit 60 Transfer belt 62, 86, 140 Roller 64 Press roller 66 Transfer roller 68 Conveying guides 70 and 116 Registration rollers 72 First switching means 74 Branching path 76 Kickback portion 78 Return conveying path 80 Second switching means 82 Long roller 84 Short roller 85 Heating roller 88 Secondary fixing belt 90 Cooling unit 92 Nip roller 100 Placement adjustment unit 102 Cutting unit 104 Arrangement unit 106 Discharge unit 110 First slitter 112 Second slitter 114 Guillotine cutter 120 Carrying roller pair 122, 124, 132 Conveying roller pair 126 Discharging roller pair 130 Single row roller pair 134 First conveying path 136 Second transport path 142 Endless belt

Claims (6)

A transfer section for transferring an image to an image receiving medium at a predetermined transfer position;
A primary fixing unit that is disposed downstream of the transfer unit and fixes the transferred image by pressurizing the image receiving medium, and can be in a fixing state and a non-low fixing state;
A secondary fixing unit disposed downstream of the primary fixing unit and fixing the transferred image by pressurizing the image receiving medium;
The conveyance length of the image receiving medium from the transfer position to the image fixing position in the secondary fixing unit is shorter than the length in the conveyance direction of the longest image receiving medium in the conveyance direction, and the fixing in the primary fixing unit from the transfer position. The conveyance length of the image receiving medium up to the position is shorter than the length of the image receiving medium shortest in the conveyance direction,
Further, when forming an image on the longest image receiving medium, the primary fixing unit is set in a non-fixed state, and the transfer unit is transferred when the leading end of the image receiving medium reaches the secondary fixing unit. When the image is transferred to the finished position and the image is formed on the shortest image receiving medium, the primary fixing unit is set in a fixing state, and the transfer unit receives the image on the primary fixing unit. An image forming apparatus, wherein an image is transferred to a position where transfer is completed when a leading edge of a medium reaches.   2. The image forming apparatus according to claim 1, further comprising an intermediate conveyance unit configured to nipping and conveying the image receiving medium between the primary fixing unit and the secondary fixing unit, wherein the intermediate conveyance unit can be in a nipped state and an open state.   The image forming apparatus according to claim 2, wherein when the image is recorded on the longest image receiving medium, the intermediate conveyance unit is opened at least until the transfer is completed. When forming an image on an image receiving medium having a length in the conveying direction shorter than the longest image receiving medium and longer than the shortest image receiving medium,
The transfer unit is provided with a blank at the rear end in the transport direction to perform transfer to the image receiving medium, and the primary fixing unit is set in a non-fixed state, and the intermediate transport unit is initially in an open state, The image forming apparatus according to claim 2, wherein the image forming apparatus is in a clamping state after the transfer at the transfer unit is completed. When forming an image on an image receiving medium having a length in the conveying direction shorter than the longest image receiving medium and longer than the shortest image receiving medium,
4. The image forming apparatus according to claim 2, wherein the intermediate conveyance unit is initially in an open state, and gradually enters a clamping state after the leading edge of the image receiving medium reaches the intermediate conveyance unit. 5. When recording a plurality of images at intervals in the transport direction on an image receiving medium having a length in the transport direction shorter than the longest image receiving medium and longer than the shortest image receiving medium,
4. The intermediate conveyance unit according to claim 2, wherein the intermediate conveyance unit is initially in an open state, and is nipped when the image receiving medium reaches the intermediate conveyance unit and the transfer position is between images in the conveyance direction. Image forming apparatus.

Images