JP2011186215A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus suppressing generation of toner or ink for a needless image by reducing an area the image has in the width direction of transfer material when carrying out a borderless printing of the image to transfer material. <P>SOLUTION: The image forming apparatus 100 which carries out the borderless printing by printing a magnified toner image G which is magnified to be larger than the size of sheet P in the conveying direction of the sheet L and in the width direction of the sheet M to the sheet P, includes: a controller 50 to control so that a first extrusion amount is set to be smaller than a second extrusion amount when the first extrusion amount is defined as the amount in which a left edge section N1 and a right edge section N2 in the magnified toner image G extrudes more than a left edge section P11 and a right edge section P12 of the sheet P in the width direction of the sheet M on the downstream side of the conveying direction of the sheet L and the second extrusion amount is defined as the amount in which a left edge section N1 and the right edge section N2 of the magnified toner image G extrudes more than the left edge section P11 and the right edge section P12 of the sheet P in the width direction of the sheet M in the upstream side of the conveying direction of the sheet L. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus capable of executing borderless printing for forming an image at least at one end of a sheet.

  Conventionally, in an image forming apparatus such as a copying machine, a printer, and a fax machine using an electrophotographic process, an image is printed with a certain margin from the peripheral edge of the sheet. On the other hand, in an inkjet image forming apparatus, so-called “marginless printing” in which an image is formed on the entire surface of a sheet with no margin at the peripheral edge of the sheet is widespread. Realization of “borderless printing” is also strongly desired in an electrophotographic image forming apparatus.

  For example, Patent Document 1 proposes an image forming apparatus capable of borderless printing. In this patent document 1, borderless printing is achieved by forming a toner image larger than the sheet on the image carrier and transferring a part of the toner image onto the sheet. By forming a toner image larger than the size of the sheet, for example, the toner image can be transferred to the edge of the sheet even when the conveyance of the sheet varies.

JP 2004-45457 A

  However, since a toner image larger than the transfer material is formed on the image carrier when performing borderless printing, there is a problem that the amount of toner consumption increases compared to normal bordered printing.

  In order to solve the above problems, the image forming apparatus according to the present invention is configured to transfer a transfer material in a transfer material conveyance direction and a transfer material width direction orthogonal to the transfer material conveyance direction with respect to a transfer material conveyed in the transfer material conveyance direction. In an image forming apparatus that performs borderless printing by printing an enlarged image larger than the size, the side edge of the enlarged image is downstream of the transfer material conveyance direction, and the side edge of the transfer material is in the transfer material width direction. A controller that sets the first protrusion amount that protrudes in the upstream side in the transfer material conveyance direction to be smaller than the second protrusion amount in which the side edge portion of the enlarged image protrudes in the transfer material width direction from the side edge portion of the transfer material; It is characterized by.

  Another image forming apparatus of the present invention is larger than the size of the transfer material in the transfer material conveyance direction and the transfer material width direction orthogonal to the transfer material conveyance direction with respect to the transfer material conveyed in the transfer material conveyance direction. In the image forming apparatus that performs borderless printing by printing the enlarged image, the center side of the rear end portion of the enlarged image is located upstream of the rear end portion of the transfer material in the upstream direction in the transfer material conveyance direction. The fourth amount of protrusion that protrudes toward the upstream side in the transfer material conveyance direction is the maximum at the corner portion side of the rear end portion of the enlarged image in the upstream direction in the transfer material conveyance direction from the rear end portion of the transfer material. A controller is provided that is set to be smaller than the amount of protrusion.

  Another image forming apparatus of the present invention is larger than the size of the transfer material in the transfer material conveyance direction and the transfer material width direction orthogonal to the transfer material conveyance direction with respect to the transfer material conveyed in the transfer material conveyance direction. In an image forming apparatus that performs borderless printing by printing a magnified image, the center side of the leading edge of the magnified image is downstream in the transfer material conveyance direction downstream from the leading edge of the transfer material on the downstream side in the transfer material conveyance direction. The fifth protrusion amount that protrudes is set to be smaller than the sixth protrusion amount that protrudes toward the downstream side in the transfer material conveyance direction at the corner portion of the front end portion of the enlarged image on the downstream side in the transfer material conveyance direction. It is characterized by having a controller which performs.

  As described above, according to the present invention, when printing an image without a border on a transfer material, the area of the image in the width direction of the transfer material is reduced, and generation of toner on a useless image is suppressed. .

1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 5 is a plan view illustrating a relationship between a sheet and a toner image when printing is performed with a border. It is a flowchart which shows the control process of a controller. FIG. 6 is a plan view showing an enlarged image size formed on an intermediate transfer belt in borderless printing. It is a conceptual diagram which shows the image formation area with respect to a sheet | seat. FIG. 6 is a conceptual diagram showing a sheet outer side region. FIG. 6 is a cross-sectional view illustrating a configuration of a main part of an image forming apparatus according to a second embodiment. It is a conceptual diagram which shows the image formation area with respect to a sheet | seat. FIG. 6 is a conceptual diagram showing a sheet outer side region.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, since the dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions, particularly specific descriptions are provided. Unless otherwise, the scope of the present invention is not limited to these.

  FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus 100 according to Embodiment 1 of the present invention. The image forming apparatus 100 is an image forming apparatus using an electrophotographic image forming process. As shown in FIG. 1, the image forming apparatus 100 includes an image forming apparatus main body (hereinafter referred to as an apparatus main body) 100A. Inside the apparatus main body 100A, image forming units 3Y, 3M, and 3C that form images. 3K is provided. The image forming units 3Y, 3M, 3C, and 3K include photosensitive drums 1Y, 1M, 1C, and 1K that are image carriers.

  Inside the apparatus main body 100A, there are a laser scanner 25 as an exposure device, photosensitive drums 1Y, 1M, 1C, and 1K as image carriers, and developing rollers 2Y, 2M, 2C, and 2K as developer carriers. Has been placed. A laser scanner 25 serving as an exposure device writes an electrostatic image by irradiating each of the photosensitive drums 1Y, 1M, 1C, and 1K with laser beams 4Y, 4M, 4C, and 4K. The developing rollers 2Y, 2M, 2C, and 2K, which are developer carriers, develop the electrostatic images of the photosensitive drums 1Y, 1M, 1C, and 1K with the toner in the developer to develop the photosensitive drums 1Y, 1M, 1C, and A toner image is formed on 1K. The intermediate transfer belt 18 is suspended from the belt driving roller 16, the roller 19, and the roller 14, and rotates in the direction of arrow C.

  A sheet P, which is a transfer material stacked and accommodated in the feeding tray 8, is fed by a feeding roller 15 that rotates in an arrow B (clockwise direction) and has a registration sensor 12 that detects the leading edge of the sheet P. Passes through the roller pair 13. Then, the sheet P is sent to the nip portion of the secondary transfer portion 9 formed by the belt driving roller 16 and the transfer roller 17 via the intermediate transfer belt 18.

  The photosensitive drums 1Y, 1M, 1C, and 1K rotate in the direction of an arrow D (counterclockwise). Electrostatic images are sequentially formed on the outer peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K by the laser beams 4Y, 4M, 4C, and 4K from the laser scanner 25. Then, the electrostatic images on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K are developed by the developing rollers 2Y, 2M, 2C, and 2K to form toner images.

  The toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K are transferred to the intermediate transfer belt 18. When forming a color image, yellow, magenta, cyan, and black colors are developed on the photosensitive drums 1Y, 1M, 1C, and 1K, and the toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K are transferred to the intermediate transfer belt 18. The toner image formed on the intermediate transfer belt 18 is transferred to the sheet P sent to the secondary transfer unit 9.

  Then, the sheet P to which the toner image has been transferred is sent to the nip portion between the fixing film 20 and the pressure roller 21, where it is heated and pressed to fix the toner image on the sheet P and become a permanent image. The sheet P on which the toner image is fixed is discharged to the outside by a discharge roller 22 and a discharge roller 23.

  FIG. 2A is a plan view showing the relationship between the sheet P and the toner image g when printing with margins is executed. As shown in FIG. 2A, during “with border” printing, the toner image g is entirely contained while leaving a margin in the surface of the sheet P. In the periphery of the sheet P, an upper margin mh, a lower margin mb, a left margin ml, and a right margin mr are secured.

  FIG. 2B is a plan view showing the relationship between the sheet P and the enlarged toner image G when borderless printing is executed. As shown in FIG. 2B, at the time of “no border” printing, the enlarged toner image G reaches the edge of the sheet P, and no margin is secured. FIG. 2B shows a state in which there is no upper margin mh, lower margin mb, left margin ml, and right margin mr, but by definition, one or more margins are zero in the top, bottom, left, and right. If so, “no border” printing is performed.

  FIG. 3 is a flowchart showing the control process of the controller 50. As shown in FIG. 3, the controller 50 starts (starts) the control (step 1, hereinafter “step” is simply referred to as “S”, S1). Then, the controller 50 determines whether borderless printing (marginless printing) is set by an operation panel (not shown) (for example, an image file on the host computer) (S2). This setting is performed, for example, when the user selects borderless printing or borderless printing for an image file on the host computer. As an example, assume that a photo is printed without borders.

  If the result of determination in S2 is YES, the controller 50 acquires data relating to the sheet position deviation amount and the sheet tilt amount (S3). Data relating to the sheet position deviation amount and the sheet tilt amount will be described later. The controller 50 acquires sheet size information to be printed (S4). The controller 50 calculates the print area from the acquired information (S5). In calculating the print area, the sheet size and the sheet position deviation amount are calculated at the leading end of the sheet P. Further, at the rear end portion of the sheet P, the sheet size, the sheet position deviation amount, and the rear end deviation amount due to the inclination of the sheet side edge portion are calculated. In FIG. 3, there is a description of × 2 regarding the sheet position deviation amount. This means that “the amount of misalignment between both side edges of the sheet P in the sheet width direction M” or “the amount of misalignment between the leading end portion and the trailing end portion in the sheet conveying direction L” is considered. Further, in FIG. 3, there is a description of × 2 regarding the trailing edge shift amount due to the inclination of the sheet side edge. This means that “the amount of deviation regarding the inclination of the side edge portions of the sheet P” is taken into consideration. The controller 50 performs printing processing with the enlarged toner image G obtained by enlarging the toner image so that the selected image size is larger than the calculated print area range (S6). The controller 50 ends the control (S7).

  If the result of determination in S2 is NO, the controller 50 immediately acquires sheet size information (S8). Then, the controller 50 calculates the print area (S9). The controller 50 ends the control (S7).

  FIG. 4A is a plan view showing an image size of the enlarged enlarged toner image G formed on the intermediate transfer belt 18 in borderless printing. As shown in FIG. 4A, the enlarged toner image G is represented as Ih in the vertical direction and Iw in the horizontal direction.

  FIG. 4B is a plan view showing the size of the sheet P. As shown in FIG. 4B, the sheet P is represented by Ph in the vertical direction and Pw in the horizontal direction. The size relationship between the enlarged toner image G formed at the time of borderless printing in FIG. 4A and the sheet P in FIG. 4B is set to satisfy Pw <Iw and Ph <Ih. In order to stably perform borderless printing on the sheet P, the size of the enlarged toner image G is the amount of misalignment of the sheet, variation in detection accuracy of the leading edge of the sheet, variation in sheet size, and sheet during conveyance. It is necessary to consider the inclination of P.

  FIG. 4C is a plan view showing a process in which the inclination of the sheet P is corrected by the registration roller pair 13. As shown in FIG. 4C, the inclination of the leading end portion of the sheet P fed by the feeding roller 15 (see FIG. 1) is corrected by the registration roller pair 13. The sheet P fed while being inclined to the left moves in the sheet conveyance direction L from the sheet position P51 and abuts against the registration roller pair 13. The leading end portion of the sheet P pushed by the feeding roller 15 moves to the sheet position P52 while being aligned with the registration roller pair 13. When the inclination is not completely corrected, the sheet is conveyed to the registration roller pair 13 and moved to the sheet position P53, and is stopped by the registration sensor 12 that detects the leading end position of the sheet P. At this time, the sheet P is inclined to the left with the sheet leading edge detection position 121 where the leading edge is detected by the registration roller pair 13 as a center.

  Similarly, the sheet P fed while being tilted to the right is corrected by the registration roller pair 13, and when the skew feeding is not completely corrected, the sheet P is stopped by the registration sensor 12. At this time, the sheet P is tilted to the right with the sheet leading edge detection position 121 where the leading edge is detected by the registration roller pair 13 as a center.

  As described above, the posture of the sheet P after passing through the registration roller pair 13 is rotated by the inclination of the sheet P left and right with the sheet leading edge detection position 121 detected by the registration sensor 12 as the rotation center.

  FIG. 5 is a conceptual diagram showing an image forming area A1 of the enlarged toner image G on the sheet P. The state when the sheet sensor 1 is tilted from the sheet P1 tilted to the right to the sheet P2 tilted to the left around the sheet leading edge detection position 121 by the registration sensor 12 is shown. In addition to the locus of the four corners of the sheet P, there is a range that is expanded vertically and horizontally, including variations in the vertical position of the sheet P including sensor detection accuracy, variations in the left and right conveyance amounts, and variations in the horizontal position of the sheet P installation. This is the image forming area A1. This image forming area A1 is an unnecessary part (a part other than the hatched part from the image forming area A0 of the comparative example) from the enlarged toner image G enlarged larger than the area of the sheet P in consideration of the skew feeding of the sheet P. ) Can also be said to have been deleted.

For example, when the variation in the leading edge detection position of the sheet P is ± 2 mm, the variation in the left and right position of the sheet P is ± 2 mm, and the variation in the inclination of the sheet P is ± 1 °, the A4 size sheet P is printed without four edges. Sometimes we can say: That is, the value obtained by subtracting the area 210 × 297 mm ² of the sheet P from the image forming area A0 of the comparative example is 3019 mm ² . On the other hand, the value obtained by subtracting the area 210 × 297 mm ² of the sheet P from the image forming area A1 of Example 1 is 2018 mm ² . The area of the protruding area of the image forming area A1 of Example 1 is reduced by about 33% compared to the area of the protruding area of the image forming area A0 of the comparative example (conventional example). Here, the variation in the leading edge detection position of the sheet P refers to an error in the amount of protrusion that may occur at the leading edge of the sheet P. Further, the variation in the left and right positions of the sheet P refers to an error in the amount of protrusion that may occur on the left and right sides of the sheet P. Further, the variation in the inclination of the sheet P refers to an error in the amount of protrusion that may occur due to the inclination of the sheet P.

  As shown in FIG. 5, the sheet P that is a transfer material is conveyed in the sheet conveyance direction L. The enlarged toner image G, which is an enlarged image, is an image enlarged larger than the size of the sheet P in the sheet conveyance direction L, which is the transfer material conveyance direction, and in the sheet width direction M, which is the transfer material width direction orthogonal to the sheet conveyance direction L. It is. The image forming apparatus 100 performs borderless printing by printing the enlarged toner image G on the sheet P.

  Here, the left edge front end protrusion amount H11 (see FIG. 6A) and the right edge front end protrusion amount H12 (see FIG. 6A), which are the first protrusion amounts, are defined as follows. . That is, the first protrusion amount is such that the left edge N1 and the right edge N2 of the enlarged toner image G on the downstream side in the sheet conveying direction L are the left edge P11 (see FIG. 6A) and the right edge of the sheet P. It is defined as an amount that protrudes in the sheet width direction M from P12 (see FIG. 6A).

  The left edge rear end protrusion amount H21 (see FIG. 6A) and the right edge rear end protrusion amount H22 (see FIG. 6A), which are the second protrusion amounts, are defined as follows. That is, the second protrusion amount is such that the left edge N1 and the right edge N2 of the enlarged toner image G on the upstream side in the sheet conveying direction L are the left edge P11 (see FIG. 6A) and the right edge of the sheet P. It is defined as an amount that protrudes in the sheet width direction M from P12 (see FIG. 6A).

  The controller 50 sets the left edge front end protrusion amount H11 and the right edge front end protrusion amount H12 as the first protrusion amount, the left edge rear end protrusion amount H21 and the right edge rear end as the second protrusion amount. It is set smaller than the side protrusion H22 (see FIG. 6A).

  In other words, when the controller 50 performs borderless printing on the sheet P with the enlarged toner image G, it can be said that the following control is performed. The controller 50 controls the drive of the laser scanner 25 to enlarge the electrostatic image from the outer shape of the sheet P and write it on the photosensitive drum 1. In this case, the amount that the enlarged toner image G on the rear end side in the sheet conveyance direction L protrudes in the sheet width direction M perpendicular to the sheet conveyance direction L with respect to the width dimension Pw of the sheet P is defined as a second protrusion amount. The amount of the enlarged toner image G on the leading end side in the sheet conveyance direction L that protrudes in the sheet width direction M perpendicular to the sheet conveyance direction L with respect to the width dimension Pw of the sheet P is defined as a first protrusion amount. The controller 50 sets the second protrusion amount to be larger than the first protrusion amount.

  According to this configuration, when the enlarged toner image G is printed on the sheet P without borders, the area of the enlarged toner image G in the sheet width direction M is reduced, and generation of unnecessary toner on the enlarged toner image G is generated. Is suppressed.

  Here, the rear end center protrusion amount H31 (see FIG. 6A), which is the third protrusion amount, is defined as follows. That is, the third protrusion amount is such that the central side N30 of the rear end portion N3 of the enlarged toner image G on the upstream side in the sheet transport direction L is more in the sheet transport direction than the rear end portion P13 of the sheet P (see FIG. 6A). It is defined as the amount that protrudes in the upstream direction of L.

  The rear end left corner maximum protrusion amount H32 (see FIG. 6A) and the rear end right corner maximum protrusion amount H33 (see FIG. 6A), which are the fourth protrusion amounts, are defined as follows. . That is, the fourth protrusion amount is such that the top side N31 and N32 of the rear end portion N3 of the enlarged toner image G on the upstream side in the sheet conveyance direction L is greater than the rear end portion P13 of the sheet P (see FIG. 6A). It is defined as the maximum amount of protrusion in the upstream direction of the conveyance direction L.

  The controller 50 sets the rear end center protrusion amount H31, which is the third protrusion amount, to be larger than the rear end left corner maximum protrusion amount H32 and the rear end right corner maximum protrusion amount H33, which is the fourth protrusion amount. The length is set small (see FIG. 6A).

  According to this configuration, when the enlarged toner image G is borderless printed on the sheet P, the area that the enlarged toner image G has on the upstream side in the sheet conveyance direction L is reduced, and the wasteful enlarged toner image G is applied. Generation of toner is suppressed.

  Further, the tip end center protrusion amount H41 (see FIG. 6A), which is the fifth protrusion amount, is defined as follows. That is, the fifth protrusion amount is such that the central side N40 of the leading end portion N4 of the enlarged toner image G on the downstream side in the sheet conveying direction L is more in the sheet conveying direction L than the leading end portion P14 of the sheet P (see FIG. 6A). It is defined as the amount that protrudes in the downstream direction.

  The leading edge left corner protrusion amount H42 (see FIG. 6A) and the leading edge right corner protrusion amount H43 (see FIG. 6A), which are sixth protrusion amounts, are defined as follows. That is, the sixth protrusion amount is such that, on the downstream side in the sheet conveying direction L, the corner portions N41 and N42 of the leading end N4 of the enlarged toner image G are conveyed more than the leading end P14 of the sheet P (see FIG. 6A). It is defined as the amount that protrudes in the downstream direction of the direction L.

  The controller 50 sets the tip center protrusion amount H41, which is the fifth protrusion amount, smaller than the tip left corner side protrusion amount H42 and the tip right corner portion protrusion amount H43, which is the sixth protrusion amount (FIG. 6). (See (a)).

  According to this configuration, when the enlarged toner image G is borderless printed on the sheet P, the area that the enlarged toner image G has on the downstream side in the sheet conveyance direction L is reduced, and the wasteful enlarged toner image G is applied. Generation of toner is suppressed.

  Next, the left edge portion N1 and the right edge portion N2 of the enlarged toner image G are on a virtual plane in which the sheet P is formed in the sheet conveyance direction L and the sheet width direction M around the center P140 of the leading end portion P14 of the sheet P. Suppose that it is rotated by. In this case, the left edge N1 and the right edge N2 of the enlarged toner image G correspond to each other based on the left edge P11 and the right edge P12 that the sheet P has.

  According to this configuration, the enlarged toner image G is formed along the left edge P11 and the right edge P12 of the sheet P, so that it is not formed along the left edge P11 and the right edge P12. Generation of toner is suppressed.

  Here, referring back to FIG. 1, the steps after image formation will be described. A toner image to be A1 is formed on the intermediate transfer belt 18 and transferred to the sheet P by the secondary transfer unit 9. The toner remaining on the intermediate transfer belt 18 is collected by a cleaning device 11 provided downstream of the secondary transfer unit 9. The toner in the sheet outer area A11 (see FIG. 6A) is transferred to the transfer roller 17 and collected by the cleaning device 10.

  FIG. 6A is a conceptual diagram showing the sheet outer side area A11. As shown in FIG. 6A, the area (hatched area) obtained by subtracting the sheet area J from the image forming area A1 (see FIG. 5) of Embodiment 1 corresponds to the sheet outer area A11. This sheet outer area A11 corresponds to an area where toner remains. The sheet outside area A11 includes areas of a toner image side end portion 101, a toner image side end portion 102, and a toner image center portion 111. The toner image center portion 111 includes a toner image rear end portion 103 and a toner image front end portion 104. The cleaning device 10 collects the toner in the sheet outer area A11. In particular, it is necessary to continuously collect toner at the toner image side end portion 101 and the toner image side end portion 102 of the cleaning device 10. Note that the above-described leading edge protrusion amount H41, the left edge leading edge protrusion amount H11, and the right edge leading edge protrusion amount H12 correspond to the amount of variation in the position of the sheet P.

  FIG. 6B is a graph showing the relationship between the collected toner amount T11 and the width direction position when the vertical axis is the toner amount collected by the cleaning device 10 and the horizontal axis is the width direction position of the cleaning device 10. is there. The amount of toner recovered in the image forming area A0 of the comparative example (conventional example) indicated by the alternate long and short dash line in FIG. 6A is the recovered toner of the comparative example (conventional example) indicated by the dashed line in FIG. It corresponds to the quantity T0. The toner amount collected in the sheet outer area A11 indicated by the solid line in FIG. 6A corresponds to the collected toner amount T11 of the comparative example (conventional example) indicated by the solid line in FIG. 6B. As can be seen, in Example 1, the areas of the toner image side end portion 101 and the toner image side end portion 102 that are continuously collected in the sheet conveyance direction L are reduced. Therefore, the toner amount at the toner image side end portion 101 and the toner image side end portion 102 is reduced. As a result, the load for collecting the toner is reduced, and wear and deterioration of the portions corresponding to the toner image side ends 101 and 102 of the cleaning devices 10 and 11 are reduced.

  Further, in the first exemplary embodiment, the area of the image forming area of the toner image leading end portion 104 and the toner image trailing end portion 103 collected in the sheet width direction M is reduced. Therefore, the toner amount at the toner image leading end 104 and the toner image trailing end 103 is reduced. As a result, a load for collecting the toner is reduced, and wear and deterioration of a portion corresponding to the toner image central portion 111 of the cleaning devices 10 and 11 are reduced.

  Further, since the total amount of toner described above is reduced, the size of the container for storing waste toner is reduced, so that the size of the apparatus main body 100A is reduced.

  In the first embodiment, the configuration in which the registration sensor 12 is arranged in the center has been described. However, the registration sensor 12 may be arranged in any position in the sheet width direction M.

  FIG. 7A is a cross-sectional view illustrating a configuration of a main part of the image forming apparatus 200 according to the second embodiment. Of the configuration of the image forming apparatus 200 according to the second embodiment, the same configurations and effects as those of the image forming apparatus 100 according to the first embodiment are denoted by the same reference numerals and description thereof is omitted as appropriate. The image forming apparatus 200 according to the second embodiment is different from the image forming apparatus 100 according to the first embodiment in that in the image forming apparatus 200 according to the second embodiment, the sheet leading edge detection unit 301 or the sheet leading edge detection unit 302 is end in the sheet width direction M. It is the point arrange | positioned at a part (refer FIG. 8).

  As will be described later, the following cases are assumed from FIGS. 8 and 9A. That is, the left edge portion N1 and the right edge portion N2 of the enlarged toner image G are formed with the sheet P in the sheet conveyance direction L and the sheet width direction M around the left corner portion P141 or the right corner portion P142 of the leading end portion P14 of the sheet P. Suppose that it is rotated in a virtual plane. In this case, the left edge portion N1 and the right edge portion N2 of the enlarged toner image G are on the left edge portion P11 (see FIG. 9A) and the right edge portion P12 (see FIG. 9A) of the sheet P. Respond based.

  According to this configuration, the enlarged toner image G is formed along the left edge P11 and the right edge P12 of the sheet P, so that it is not formed along the left edge P11 and the right edge P12. Generation of toner is suppressed.

  As shown in FIG. 7A, the sheet P is fed in the sheet conveyance direction L by the feeding roller 15. When the leading edge of the sheet P enters the registration roller pair 30, the registration roller pair 30 is stopped. Since the leading edge of the sheet P fed by the feeding roller 15 tries to hit the registration roller pair 30, the inclination of the leading edge of the sheet P is corrected.

  Then, when the registration roller pair 30 is driven, the sheet P whose inclination is corrected is conveyed by the registration roller pair 30. The position of the leading edge of the sheet P is detected by the timing at which the registration roller pair 30 is driven.

  FIG. 7B is a process diagram illustrating a process in which the leading edge of the sheet P enters the registration roller pair 30 while being inclined and the inclination of the leading edge of the sheet P is corrected. As shown in FIG. 7B, the sheet P is conveyed while being inclined to the left like the sheet position P <b> 61, and the right end of the leading end portion of the sheet P hits the registration roller pair 30. The position of the leading edge of the sheet P is rotated around the sheet leading edge detector 301 and corrected so as to be aligned with the registration roller pair 30, and sequentially moves to the sheet position P62 and the sheet position P63. When the inclination of the sheet P is not completely corrected, the registration roller pair 30 is driven and is sandwiched between the registration roller pair 30. At this time, the driving start timing of the registration roller pair 30 is set to the sheet leading end position.

  Similarly, when the sheet P is conveyed to the right, the inclination of the sheet P is corrected by the registration roller pair 30 and the conveyance of the sheet P is stopped by the registration roller pair 30. In this case, the sheet P is corrected while rotating around the left end of the leading end of the sheet P.

  As described above, with the sheet P entering the registration roller pair 30 and stopping, the leading end of the sheet P rotates around the left and right ends of the leading end of the sheet P that abuts against the registration roller pair 30. It will be.

  FIG. 8 is a conceptual diagram showing an image forming area A2 (image forming area) for the sheet P. As shown in FIG. 8, the image forming area A2 is inclined to the right when the sheet P hits the registration roller pair 30 and the left end of the leading end of the sheet P rotates around the sheet leading end detection unit 302. The locus of the sheet position P3 is included. Further, the image forming area A2 has a locus of the sheet position P4 inclined to the left when the sheet P hits the registration roller pair 30 and the right end of the leading end of the sheet P rotates around the sheet leading end detecting unit 301. Including. In addition, the image forming area A2 includes variations in the leading and trailing ends of the sheet P, variations in the left and right conveyance amounts of the sheet P, and variations in the left and right positions of the sheet P, including sensor detection accuracy. It is a hatching range that spreads vertically and horizontally.

For example, when the variation in the leading edge detection position of the sheet P is ± 2 mm, the variation in the left and right position of the sheet P is ± 2 mm, and the variation in the inclination of the sheet P is ± 1 °, the A4 size sheet P is printed without four edges. Sometimes we can say: That is, a value obtained by subtracting the area 210 × 297 mm ² of the sheet P from the area of the image forming region A00 of the comparative example (conventional example) is 3004 mm ² . On the other hand, the value obtained by subtracting the area 210 × 297 mm ² of the sheet P from the area of the image forming area A 2 of Example 2 is 2097 mm ² . The area of the protruding area of the image forming area A2 of Example 2 is reduced by about 30% compared to the area of the protruding area of the image forming area A00 of the comparative example (conventional example). Here, the variation in the leading edge detection position of the sheet P refers to an error in the amount of protrusion that may occur at the leading edge of the sheet P. Further, the variation in the left and right positions of the sheet P refers to an error in the amount of protrusion that may occur on the left and right sides of the sheet P. Further, the variation in the inclination of the sheet P refers to an error in the amount of protrusion that may occur due to the inclination of the sheet P.

  Here, referring back to FIG. 7A, the steps after image formation will be described. A toner image to be A2 is formed on the intermediate transfer belt 18 and transferred to the sheet P by the secondary transfer unit 9. The toner remaining on the intermediate transfer belt 18 is collected by a cleaning device 11 provided downstream of the secondary transfer unit 9. The toner in the sheet outer area A <b> 21 (see FIG. 9A) is transferred to the transfer roller 17 and collected by the cleaning device 10.

  FIG. 9A is a conceptual diagram showing the seat outer area A21. As shown in FIG. 9A, the area obtained by subtracting the sheet area J from the image forming area A2 in Example 2 (the area of the hatched portion) corresponds to the sheet outer area A21. This sheet outer area A21 corresponds to an area where toner remains. The cleaning device 10 collects the toner in the sheet outer area A21. In particular, it is necessary to continuously collect toner at the toner image side end portion 105 and the toner image side end portion 106 of the cleaning device 10.

  FIG. 9B is a graph showing the relationship between the toner amount and the width direction position when the vertical axis is the collected toner amount collected by the cleaning device 10 and the horizontal axis is the width direction position of the cleaning device 10. . The amount of toner recovered in the image forming area A00 of the comparative example (conventional example) indicated by the alternate long and short dash line in FIG. 9A is the recovered toner of the comparative example (conventional example) indicated by the dashed line in FIG. This corresponds to the amount T00. The toner amount collected in the sheet outer side area A21 of Example 2 indicated by a solid line in FIG. 9A corresponds to the recovered toner amount T21 of Example 2 indicated by a solid line in FIG. 9B.

  In the second exemplary embodiment, the areas of the image forming regions of the toner image side end portion 105 and the toner image side end portion 106 that are continuously collected in the sheet conveyance direction L are reduced. Therefore, the toner amount at the toner image side end portion 105 and the toner image side end portion 106 is reduced. As a result, the load for collecting the toner is reduced, and wear and deterioration of the portions corresponding to the toner image side ends 105 and 106 of the cleaning device 10 are reduced.

  Further, in the second exemplary embodiment, only the area of the toner image rear end portion 107 is reduced with respect to the areas of the toner image rear end portion 107 and the toner image front end portion 108 that are collected in the sheet width direction M. . Therefore, the toner amount at the toner image rear end portion 107 is reduced. As a result, a load for collecting the toner is reduced, and wear and deterioration of a portion corresponding to the toner image central portion 112 of the cleaning device 10 are reduced.

  Further, since the total amount of toner described above is reduced, the size of the container for storing waste toner is reduced, so that the size of the apparatus main body 100A is reduced.

  Although the laser beam printer has been described in the first and second embodiments, the technical idea of forming the image forming areas A1 and A2 in the first and second embodiments can be applied to an ink jet printer that is an image forming apparatus. In this case, ink is used instead of toner, and an enlarged ink image is used instead of the enlarged toner image. In any case, the excess ink absorbing member can be reduced in size by the technical ideas of the first and second embodiments.

  The laser beam printer or the ink jet printer to which the techniques of the first and second embodiments are applied is a cleaning device 10 that is a cleaning unit that cleans the toner or ink that forms the enlarged toner image G or the enlarged ink image that protrudes from the sheet P. , 11. Then, when the enlarged toner image G or the enlarged ink image is printed on the sheet P without a border, the enlarged toner image G or the enlarged ink image protruding from the width dimension Pw of the sheet P on the rear end side in the sheet conveying direction L is formed. Toner is present. Further, there is toner that forms an enlarged toner image G or an enlarged ink image that protrudes beyond the width dimension Pw of the sheet P on the leading end side in the sheet conveying direction L. Similarly, when the enlarged toner image G or the enlarged ink image is printed on the sheet P without borders, the enlarged toner image G or the enlarged ink image that protrudes from the leading end in the sheet conveying direction L on the leading end side in the sheet conveying direction L. There is toner or ink that has formed. Further, there is toner that forms an enlarged toner image G or an enlarged ink image that protrudes from the rear end portion of the sheet P on the rear end side in the sheet conveying direction L. Cleaning devices 10 and 11 serving as cleaning means clean such toner.

  According to the configuration of the laser beam printer or the ink jet printer according to the first and second embodiments described above, the consumption amount of toner or ink is reduced while the borderless printing is executed satisfactorily. Therefore, the amount of toner or ink collected that forms the enlarged toner image G or enlarged ink image in which the enlarged toner image G or enlarged ink image protrudes from the sheet P is reduced. Specifically, the collected amount of toner or ink remaining at both ends of the enlarged toner image G or the enlarged ink image in the sheet width direction M, and the front and rear ends of the enlarged toner image G or the enlarged ink image in the sheet conveyance direction L The amount of collected toner or ink remaining at the end is reduced. As a result, the load on the cleaning devices 10 and 11 is reduced, and the size of the toner or ink collection space or the collection container is reduced.

  Finally, a description will be given of variation factors that cause margins when performing borderless printing. There are the following factors, which will be explained in turn. First, there is a variation in the size of the sheet P. Although the variation factor is a relatively small category, it is not strictly constant, and varies depending on the sheet manufacturer and the rod, and there is a sheet larger than the prescribed size. For this reason, in order to perform borderless printing on these sheets, it is necessary to make an image larger than the maximum size of the sheet.

  Second, there is variation due to the sheet not reaching the transfer position at the same timing. Since the stiffness of the sheet changes depending on the type of sheet, the atmosphere environment, the standing condition, etc., the slack shape of the sheet until reaching the transfer position is different, so the sheet may not reach the transfer position at the same timing. Since the arrival timing is different, it is necessary to start writing the leading edge image earlier by the variation.

  Third, there is variation in the sheet setting position. The feed width regulation takes into account variations in the sheet size, so there is a gap on the left and right when the sheet is set. The image forming area must be wider than the width and length of the sheet in consideration of variation in the set position.

  Fourth, there is variation due to the skew of the leading edge of the sheet not being completely corrected by the registration rollers. Since the leading edge of the sheet is conveyed to the registration rollers while being tilted, a deviation from the ideal position is more likely to occur at the trailing edge than at the leading edge in the sheet conveying direction. The rear end portion needs to form an image wider than the front end portion.

  Fifth, there is variation due to the difference between the left and right roller diameters. If there is a difference between the left and right roller diameters, even if the leading edge of the sheet is not inclined at all, the sheet is conveyed while being inclined little by little. More deviation from the ideal position occurs at the rear end than at the front end in the sheet conveyance direction. The rear end portion needs to form an image wider than the front end portion.

  It is difficult to detect and calibrate all the above-described variations, and a complicated configuration and control are required. In consideration of variations, by forming an image in an area larger than the sheet as in the image forming apparatuses of Embodiments 1 and 2, it is possible to perform borderless printing with a simple configuration and without generating a blank portion. It becomes.

50 controller 100 image forming apparatus P sheet (transfer material)
L Sheet conveyance direction (transfer material conveyance direction)
M Sheet width direction (transfer material width direction)
G Enlarged toner image (image)
H11 The amount of protrusion of the left edge tip side (first protrusion amount)
H12 Protruding amount on the right edge tip side (first protruding amount)
H21 Left edge rear end protrusion amount (second protrusion amount)
H22 The amount of protrusion on the right edge rear end side (second protrusion amount)
N1 Left edge (side edge of enlarged image)
N2 Right edge (side edge of enlarged image)
P11 Left side edge (side edge of transfer material)
P12 Right edge (side edge of transfer material)

Claims (6)

There is no border on the transfer material conveyed in the transfer material conveyance direction by printing an enlarged image that is larger than the size of the transfer material in the transfer material conveyance direction and the transfer material width direction orthogonal to the transfer material conveyance direction. In an image forming apparatus for printing,
The first protruding amount that the side edge portion of the enlarged image protrudes in the transfer material width direction from the side edge portion of the transfer material on the downstream side in the transfer material conveyance direction, and the side edge portion of the enlarged image on the upstream side in the transfer material conveyance direction. An image forming apparatus comprising: a controller that is set to be smaller than a second protrusion amount that protrudes in a transfer material width direction from a side edge portion of the transfer material. There is no border on the transfer material conveyed in the transfer material conveyance direction by printing an enlarged image that is larger than the size of the transfer material in the transfer material conveyance direction and the transfer material width direction orthogonal to the transfer material conveyance direction. In an image forming apparatus for printing,
A third amount of protrusion of the center side of the rear end portion of the enlarged image on the upstream side in the transfer material conveyance direction from the rear end portion of the transfer material toward the upstream direction in the transfer material conveyance direction is defined on the upstream side in the transfer material conveyance direction. An image forming apparatus comprising: a controller that sets a corner portion of a rear end portion of the enlarged image to be smaller than a fourth protrusion amount that protrudes in the upstream direction in the transfer material conveyance direction from the rear end portion of the transfer material. apparatus. There is no border on the transfer material conveyed in the transfer material conveyance direction by printing an enlarged image that is larger than the size of the transfer material in the transfer material conveyance direction and the transfer material width direction orthogonal to the transfer material conveyance direction. In an image forming apparatus for printing,
The fifth protrusion amount in which the center side of the front end portion of the enlarged image protrudes toward the downstream side in the transfer material transport direction from the front end portion of the transfer material on the downstream side in the transfer material transport direction, and the enlarged image on the downstream side in the transfer material transport direction. An image forming apparatus, comprising: a controller that sets a corner portion side of the leading end portion to be smaller than a sixth protruding amount that protrudes toward the downstream side in the transfer material transport direction from the leading end portion of the transfer material.   The side edge portion of the enlarged image has the transfer material when the transfer material is rotated on a virtual plane formed in the transfer material conveyance direction and the transfer material width direction around the center of the front end portion of the transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus is based on a side edge.   When the transfer material is rotated in a virtual plane formed in the transfer material transport direction and the transfer material width direction around the corner of the tip of the transfer material, the side edge of the enlarged image is The image forming apparatus according to claim 1, wherein the image forming apparatus is based on a side edge portion.   6. The image forming apparatus according to claim 1, further comprising a cleaning unit that cleans toner or ink that forms an image in which the enlarged image protrudes from the transfer material.

Images