JP2007010860A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a point where the toner quantity drastically changes in a sub-scanning direction in a border added part of a borderless image. <P>SOLUTION: The image forming apparatus has a density in a part corresponding to image information converted so that printing ratio in a leading tip part of a toner image is mildly varied when the toner image on the photoreceptor drum 1 is proceeded into a primary transfer part T1. Thus, blurring in a latent image due to proceeding into the primary transfer part T1 or proceeding directly into a transfer part and transfer blurring due to proceeding into a secondary transfer part composed of a secondary transfer roller 9 and a secondary transfer facing roller 6b are suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer.

  FIG. 1 shows an example of a conventional color image forming apparatus of an intermediate transfer belt type. A photosensitive drum 1 as an image carrier is configured by applying an organic photoreceptor (OPC) or a photoconductor made of A-Si, CdS, Se or the like to the outer peripheral surface of a cored bar made of aluminum or the like. It rotates in the direction of arrow C1 at a speed V1 (hereinafter referred to as a process speed). A surface 3 a of the surface of the photosensitive drum 1 is an exposure position by the exposure device 3 and is exposed by the exposure device 3 to form a latent image on the surface of the photosensitive drum 1. The intermediate transfer belt 60 as an intermediate transfer member is made of rubber such as EPDM, NBR, urethane, silicone rubber, or resin such as PI, PA, PC, PVDF, ETFE, PET, PC / PET, ETFE / PC. Further, the roller is stretched on two rollers, that is, a driving roller 6b and a stretching roller 6c which are also secondary transfer opposing rollers. The intermediate transfer belt 60 is driven at the process speed V <b> 1 in the direction of the arrow C <b> 3 when the driving roller 6 b is rotated by driving means (not shown). The intermediate transfer belt 60 is provided with a position detection member 5a that can be distinguished from the surface of the intermediate transfer belt 60 by the optical sensor 5 at one end in the circumferential direction and in the direction perpendicular to the circumferential direction. After detecting that the position detection member 5a passes the detection unit 5b by the optical sensor 5 (hereinafter referred to as TOP detection), the rotation phase can be recognized by counting the time inside the main body based on the detection. T1 is a contact portion between the photosensitive drum 1 and the intermediate transfer belt 60, that is, a primary transfer portion. The primary transfer roller 7 b provided with a conductive sponge layer on the shaft is in contact with the photosensitive drum 1 through the intermediate transfer belt 60. Reference numerals 100 and 101 denote means for charging the toner on the intermediate transfer belt 60. The charging rollers 100b and 101b that follow the intermediate transfer belt 60 and rotate at the same peripheral speed have a mechanism (not shown) that contacts and separates from the intermediate transfer belt 60, and can contact at a desired time. The DC voltage power supply 100a and the alternating voltage power supply 101a apply voltages to the charging rollers 100b and 101b, respectively. In addition, by using the driving roller 6b as a counter electrode, charging efficiency when charging is performed by the charging rollers 100b and 101b is increased.

  The full color image forming process will be described below with reference to FIG.

  The photosensitive drum 1 is driven in the direction of arrow C1 by a driving means (not shown), and is uniformly charged to a predetermined potential by the charging roller 2. At the timing when the TOP of the intermediate transfer belt 60 is detected, exposure is started by the exposure device 3, and light by a signal according to a yellow image pattern is scanned onto the photosensitive drum 1 whose surface is uniformly charged, and a latent image is formed. It is formed.

  When the photosensitive drum 1 further rotates in the direction of the arrow C1 after the latent image formation is started, the developing device 4a containing yellow toner among the developing devices 4a, 4b, 4c, and 4d supported by the support 4 becomes the photosensitive drum 1. The support 4 rotates in the direction of the arrow C2 so as to face each other. The selected developing device 4a has a developing roller (not shown) that rotates at a predetermined rotational speed at a portion facing the photosensitive drum 1, and is constantly carried in the developing device and carried on the surface of the developing roller. The latent image is visualized by the negative polarity toner. At this time, the reason that only the latent image forming portion on the surface of the photosensitive drum 1 is visualized by the toner is that the negative toner is developed in the non-latent image forming portion by the potential difference between the developing device and the photosensitive drum 1 (hereinafter, developing bias). This is because the potential difference is changed only in the portion where the latent image is formed, and the toner is transferred to the photosensitive drum 1. Normally, the developing bias is applied by a high voltage power source.

  When the photosensitive drum 1 further rotates in the direction of arrow C1 and reaches the primary transfer portion T1, the developed toner image is positively fed from the high-voltage power source 7a to the primary transfer roller 7b using the core of the photosensitive drum 1 as a counter electrode. By being applied with a positive bias, primary transfer is performed on the intermediate transfer belt 60. The untransferred toner on the photosensitive drum 1 is cleaned by a cleaner (hereinafter referred to as a blade cleaner) 13 that scrapes off by bringing the blade into contact therewith.

  When the development of the yellow toner image is completed, the developing device is switched. The support 4 rotates counterclockwise, and the developing device 4b containing the next magenta toner is positioned at a position facing the photosensitive drum 1. When the next TOP detection is performed, the same operation is repeated to develop and transfer magenta, cyan, and black colors, and a plurality of color toner images are formed on the intermediate transfer belt 60. At this time, since all the four color images are transferred to the same position on the intermediate transfer belt 60, the positions of the four color toner images coincide with each other.

  When the four color toner images are transferred onto the intermediate transfer belt 60, the transfer material P is conveyed from the registration roller R in synchronization with the movement of the intermediate transfer belt 60, and has the same configuration as the primary transfer roller 7b. The secondary transfer roller 9 contacts the intermediate transfer belt 60 via the transfer material P, and a positive polarity bias is applied from a high voltage power source (not shown) using the driving roller 6b as a counter electrode, so that the four colors on the intermediate transfer belt 60 are displayed. The toner images are secondarily transferred onto the transfer material P all at once.

  The transfer material P onto which the four color toner images have been transferred is fused and fixed by a conventionally known fixing device 11 that rotates a heating roller and a pressure roller using a driving means (not shown), and a paper discharge device (not shown). A color image is obtained by discharging the sheet.

  Next, FIG. 1 shows a cleaning process for toner remaining on the intermediate transfer belt 60 without being transferred during the secondary transfer (hereinafter referred to as secondary transfer residual toner).

  The secondary transfer residual toner is given a positive charge by a charging roller 100b to which a positive DC voltage is applied from a DC voltage power supply 100a. Note that the charge amount of each toner particle after the charging is not uniform, but charging can be performed while suppressing toner scattering.

  Subsequently, the secondary transfer residual toner is again given positive charge by the charging roller 101b to which an alternating voltage obtained by superimposing an alternating voltage of a predetermined frequency on a positive DC voltage having a predetermined value is applied from the alternating voltage power supply 101a. Is done. By this charging, the electric polarity of the toner particles maintains the positive polarity, and the charge amount of each particle is made uniform.

  Subsequently, the secondary transfer residual toner proceeds to the primary transfer portion T1, and is electrostatically transferred to the photosensitive drum simultaneously with the primary transfer of the first color of the next page by the primary transfer roller 7b to which a positive polarity bias is applied. It is removed from the transfer belt 60. Then, the secondary transfer residual toner transferred to the photosensitive drum 1 is collected by the photosensitive drum cleaner 13, and the removal of the secondary transfer residual toner on the intermediate transfer belt 60 is completed.

  For mono-color printing, in the case of full-color printing, four color images are sequentially primary transferred and superimposed, and then the process after secondary transfer is performed. Process after secondary transfer.

  Next, a borderless image forming process in the image forming apparatus to which the present invention is applied will be described.

  In order to form a borderless image, an image (hereinafter referred to as a border-added portion Cz) that complements a margin is determined with respect to the image information before the printing process. For example, as shown in FIG. 2, interpolation is performed by enlarging the image in the normal image area Iz in the transfer material area Pz. The border-added portion Cz takes into account variations in paper feed timing and the like so that toner is printed in the margin portion to ensure a final borderless image. To do.

  In the printing process, new image information obtained by complementing the marginal portion Cz to the original image information is formed by performing the above-described exposure and development processes.

  A borderless image is obtained by the above electrophotographic process.

JP 2004-117601 A

  In the above conventional example, the amount of toner per predetermined length in the sub-scanning direction (hereinafter referred to as a predetermined length longitudinal toner amount) from the front end to the rear end of the edge added portion (hereinafter referred to as the front edge added portion) on the front end side of the image. The relationship is not specified. Therefore, there may be a point where the toner amount changes abruptly in the sub-scanning direction at the front edge portion. When such a point exists, the frictional force applied from the intermediate transfer belt to the photosensitive drum is rapidly changed when the point is primarily transferred in the printing process. When this happens, sudden rotation fluctuations occur in the photosensitive drum, writing unevenness (hereinafter, latent image blur) occurs in laser exposure, and an image defect appears on the final image.

  This problem also occurs in the transfer process in the transfer belt type image forming apparatus. Some intermediate transfer belt type image forming apparatuses have a process of simultaneously performing a secondary transfer process and a primary transfer process on and after the next page. Similar defects occur in this process. That is, if there is a point where the toner amount changes abruptly in the sub-scanning direction at the front edge, the point enters the secondary transfer part before entering the paper during the secondary transfer, and the intermediate transfer from the secondary transfer roller. The frictional force applied to the belt changes rapidly. In this case, sudden rotation fluctuations occur in the intermediate transfer belt, and primary transfer unevenness (hereinafter referred to as transfer blur) occurs in the image during the primary transfer.

  In full-color printing, at the time of transferring the second and subsequent colors, the front edge of both the front edge of the color already transferred onto the belt and the color transferred from the photosensitive drum enters the transfer portion at the same time. Therefore, a plurality of colors of toner having a larger amount than that of a single color enter the transfer portion at the same time, and the frictional force applied from the intermediate transfer belt to the photosensitive drum may change abruptly. In this case, the same problem as described above occurs.

  Note that the method of adding a dot toner image disclosed in Patent Document 1 cannot eliminate the point at which the toner amount suddenly changes as described above, and is not sufficient to solve the above problem. There wasn't.

  Therefore, it has been a problem of the prior art to prevent the occurrence of latent image blur and transfer blur due to toner at the edge of the edge.

  An object of the present invention is to provide an image forming apparatus that solves the above problems.

  In order to solve the above-described problems, according to one embodiment of the present invention, an image forming unit that forms a latent image on an image carrier according to image information, and a toner image corresponding to the latent image is formed on the image carrier. An image forming apparatus using a developing unit and a transfer unit that transfers the toner image to a transfer material, wherein the transfer material has no margin according to the image information corresponding to an area larger than the entire area of the transfer material. In an image forming apparatus for forming an image, a printing rate at a leading end portion of the toner image when the toner image on the image carrier enters the transfer unit is gradually changed in a conveyance direction which is the entering direction. Means for converting the density of the portion corresponding to the tip of the image information.

  Here, the printing rate can be increased linearly over a predetermined range from the image start position on the leading end side in the toner image entrance direction in the transport direction. Alternatively, when the printing rate of the image information differs by a predetermined rate or more before and after a predetermined position on the leading end side of the toner image in the transport direction, a printing rate of a predetermined rate with respect to the printing rate behind the predetermined position By adding the additional image information before the predetermined position, a rapid change in the printing rate of the image information before and after the predetermined position can be suppressed. Alternatively, the developing unit forms a toner image of a plurality of colors corresponding to the latent image on the image carrier, and the printing rate is determined based on the start position of each color image at the leading end side of each color toner image in the transport direction. Each position shifted so as not to overlap can be increased linearly over a predetermined range.

  Another aspect of the present invention is an image forming unit that forms a latent image according to image information on an image carrier, a developing unit that forms a toner image corresponding to the latent image on the image carrier, and the toner image. Is a device that forms an image by a primary transfer unit that transfers a toner image to an intermediate transfer member and a secondary transfer unit that transfers a transfer image on the intermediate transfer unit to a transfer material, which is wider than the entire area of the transfer material. In the image forming apparatus for forming an image having no margin on the transfer material according to the image information corresponding to a region, the leading end portion of the transfer image when the transfer image on the intermediate transfer unit enters the secondary transfer unit Means for converting the density of the portion of the image information corresponding to the tip portion so that the printing rate in the image is gently changed in the transport direction, which is the entering direction.

  Here, the printing rate can be increased linearly over a predetermined range from the image start position on the leading end side in the entering direction of the transfer image in the transport direction. Alternatively, when the printing rate of the image information differs by a predetermined rate or more before and after a predetermined position on the leading end side of the transfer image in the transport direction, a printing rate of a predetermined rate with respect to the printing rate behind the predetermined position By adding the additional image information before the predetermined position, a rapid change in the printing rate of the image information before and after the predetermined position can be suppressed. Alternatively, the developing unit forms a toner image of a plurality of colors corresponding to the latent image on the image carrier, and the printing rate is determined based on the start position of each color image on the leading side of each color transfer image in the transport direction. Each position shifted so as not to overlap can be increased linearly over a predetermined range.

(Embodiment 1)
In this embodiment, the image forming apparatus shown in FIG. 1 can be used as in the conventional example.

  In the present invention, the printing process is the same as that of the conventional example, and the amount of toner per unit length in the sub-scanning direction position and the sub-scanning direction (hereinafter referred to as unit longitudinal toner amount) from the front edge to the rear edge of the front edge addition portion. Characterized by relationships.

  FIG. 3A shows an example of the relationship between the unit longitudinal toner amount after the edge addition and the sub-scanning direction position. PT indicates the position of the front edge of the front edge. Tsp indicates the margin start position at the leading edge of the paper, and Bsp indicates the margin start position at the trailing edge of the paper. The method for complementing the edge-added portion may be any method such as enlarging the image in the normal image area as in the conventional example. FIG. 3B shows the relationship between the unit longitudinal toner amount (vertical axis) and the sub-scanning direction position (horizontal axis) of the enlarged margin portion separately for each color component Y, M, C, K. .

  As a method of complementing the edge-added portion, a method such as enlargement is used, and when the relationship between the unit longitudinal toner amount of the edge-added portion and the position in the sub-scanning direction is not regular, each color component is similarly not regular. Therefore, there may be a point where the unit longitudinal toner amount changes abruptly in the sub-scanning direction. As for FIG. 3B, D1, D2 and D3 are such points. When these points enter the primary transfer portion in the printing process, the frictional force applied from the intermediate transfer belt to the photosensitive drum changes abruptly, resulting in latent image blurring.

  Therefore, in the present embodiment, the relationship between the position in the sub-scanning direction of the edge-added portion and the unit longitudinal toner amount in each color is converted so as to gradually increase from the front end to the rear end by performing a predetermined calculation. . By this operation, the point at which the unit longitudinal toner amount changes rapidly is eliminated, and latent image blurring is prevented.

  Specifically, for example, as shown in FIG. 4, the conversion rate is such that the printing rate increases linearly from the front edge PT at the front end CH to a position CH that is a predetermined distance before the margin, and does not change thereafter. Are uniformly applied in the longitudinal direction in each color. In this way, the printing rate gradually changes for each color in the sub-scanning direction, which is the transport direction, and an image that fades in is realized, and a relationship in which the unit longitudinal toner amount gradually increases is realized.

  When transferring the image after the calculation in this way, there is no point at which the unit longitudinal toner amount changes abruptly, and therefore no latent image blur occurs.

  For the above-described method, the change in the unit longitudinal toner amount can be reduced by adjusting the position of PT or CH, or by devising the relational expression between PT and CH, and the same effect can be obtained. It is done. Further, it is not necessary to apply the conversion formula uniformly in the longitudinal direction, and as a result, the amount of toner used in the entire longitudinal length only needs to satisfy the above relationship.

  Furthermore, since the present embodiment can be applied when the front edge of the front edge portion enters the transfer portion as long as the paper does not enter the transfer portion, the same applies to the transfer process of the image forming apparatus of the transfer belt system. Can be implemented.

  The present invention can also be applied to a secondary transfer process in a process in which secondary transfer and primary transfer after the next page are performed simultaneously. However, in the above specific example, sudden rotation fluctuations of the photosensitive drum are prevented and latent image blurring is prevented. In this case, sudden rotation fluctuations are prevented from occurring in the intermediate transfer member. What can be suppressed is primary transfer unevenness (hereinafter referred to as transfer blur).

  As described above, according to this embodiment, it is possible to prevent the latent image blur in the transfer belt method, and in the borderless image forming process of the intermediate transfer belt method, a predetermined length in the sub-scanning direction of the front edge addition portion. Further, it is possible to prevent a latent image blur due to a point where the longitudinal toner amount changes rapidly entering the primary transfer portion.

  Note that the density of the edge-added portion usually varies depending on the image signal in the direction perpendicular to the sub-scanning direction, which is the longitudinal direction of the edge-added portion. The slope of the linear part of the conversion formula shown in FIG. 4 can be made different according to the density in the longitudinal direction of the edge-added part so that the change in the printing rate in the sub-scanning direction is larger than the lower part. . This is because the longitudinal density of the edge-added part is compared on the left and right sides, and may vary depending on the result, or the longitudinal density of the edge-added part is compared in detail for each position in the longitudinal direction, and differs depending on the result. It may be allowed.

  Thereby, it is possible to prevent the intermediate transfer belt or the transfer belt from being deteriorated by the toner at the front edge added portion.

(Embodiment 2)
In this embodiment, the image forming apparatus shown in FIG. 1 can be used as in the conventional example.

  In the present embodiment, similarly to the first embodiment, the printing process is the same as that in the conventional example, and is characterized by the relationship between the position in the sub-scanning direction and the unit longitudinal toner amount from the front edge to the rear edge of the front edge addition portion.

  In the present embodiment, a point at which the unit longitudinal toner amount changes abruptly at the edge addition portion is specified in advance from the image information, and a toner image is added to the point. In this way, the relationship between the unit longitudinal toner amount of each color and the distance in the sub-scanning direction is converted to a gradually increasing relationship. By this operation, the point at which the unit longitudinal toner amount changes rapidly is eliminated, and latent image blurring is prevented.

  Specifically, a state in which the present method is applied using the edge-added portion image shown in FIG.

  First, a method for specifying the position where the unit longitudinal toner amount changes rapidly will be described with reference to FIG.

  For each color, for a predetermined position SCA in the sub-scanning direction, the entire longitudinal area up to 1 mm in the sub-scanning direction is designated as SCA- and SCA +, respectively, the print ratio of the two areas in the front and rear, and the image information of the edge portion Compare by analyzing. Similar to the SCA, the print ratios of the two areas before and after the plurality of positions SCB to SCD at regular intervals are compared, and the unit longitudinal toner amount changes abruptly at the position where the increase of the print ratio is 25% or more. Specify as location. In the example of FIG. 5, it can be specified that Y-color SCB, M-color SCB, and K-color SCC are corresponding positions.

  Next, a method of adding a toner image at a position where the unit longitudinal toner amount changes rapidly will be described with reference to FIG.

  As shown in FIG. 6A, an image was added to the Y-color SCB, the M-color SCB, and the K-color SCC at a printing rate that is half of the increased amount derived as described above. In this way, there is no point at which the unit longitudinal toner amount changes abruptly, and latent image blurring is prevented.

  Here, the additional image is set to a printing rate that is half of the increase in the printing rate. However, as shown in FIG. 6B, for example, it is divided into a plurality of stages such as 25%, 50%, and 75% of the increasing amount. The change in the unit longitudinal toner amount becomes more gradual, and a great effect can be obtained.

  As described above, according to the present embodiment, a point at which the unit longitudinal toner amount rapidly changes in the edge-added portion is specified in advance from the image information, and a toner image is added to the point so that the toner amount gradually increases. Thus, the latent image blur in the transfer belt method can be prevented, and in the intermediate transfer belt method of the borderless image forming step, the longitudinal toner amount of a predetermined length in the sub-scanning direction of the front margin is suddenly increased. It is possible to prevent latent image blur due to the point that changes to the primary transfer portion entering.

  If the left and right images are biased with respect to the center position in the direction perpendicular to the transport direction (longitudinal direction), the frictional force applied between the intermediate transfer belt and the photosensitive drum also varies, and the belt is transported. May deteriorate and image quality may deteriorate. Therefore, when the printing rate after the predetermined position on one side with respect to the center position is higher than the printing rate after the predetermined position on the opposite side with respect to the center position so that the left and right images are balanced as a whole, By making the ratio of the additional image on the second side lower than the ratio of the additional image on the opposite side, the left and right imbalance of the entire edge-added portion image can be suppressed.

  Thereby, it is possible to prevent the transferability of the intermediate transfer belt or the transfer belt from being deteriorated and the image quality from being deteriorated due to the left and right imbalance of the toner amount at the front edge added portion.

(Embodiment 3)
In this embodiment, the image forming apparatus shown in FIG. 1 can be used as in the conventional example.

  The present invention is characterized in that the printing process is the same as that of the conventional example, and the front edge of the front edge of each color at the time of full color printing is related.

  In the present invention, the front edge of the front edge of each color is offset during full color printing. In this way, even when the front edge of the front edge is primarily transferred after the second color, toners of a plurality of colors do not enter the primary transfer portion at the same time. Accordingly, there is no sudden change in the frictional force applied from the intermediate transfer belt to the photosensitive drum, so that no latent image blur occurs.

  Note that, as shown in the first embodiment, it is also desirable that the image has no sudden change in the frictional force for the edge portions of the respective colors.

  Specifically, for example, the image after the edge addition portion complementation shown in FIG. 3 is performed as shown in FIG. For the Y color, linearly increases from the front edge PT at the front end CH to a position CH that is a predetermined distance ahead of the margin, and thereafter, Ey equal to 1 is uniformly multiplied in the longitudinal direction. For the MCK color, the formulas Em, Ec, and Ek that are linearly increased from PT2, PT3, and PT4 that are equally spaced from the PT and thereafter 1 are uniformly multiplied in the longitudinal direction.

  In this way, in the intermediate transfer belt type full-color borderless image forming process, the leading ends of the colors do not overlap, and the toner of multiple colors does not enter the primary transfer portion at the time of primary transfer. Since the frictional force applied to the photosensitive drum does not change abruptly, the latent image blur due to simultaneous entry of a plurality of color toners in the front border portion into the primary transfer portion and further into the secondary transfer portion Transfer blur can be prevented. Also, it is possible to prevent latent image blurring in the transfer belt system.

1 is a diagram illustrating an example of a color image forming apparatus to which the present invention is applied. It is a figure which shows an example of the method of complementing a border addition part in a borderless image formation process. FIG. 6 is a diagram illustrating an example of a relationship between a unit longitudinal toner amount after complementing a marginal portion and a position in a sub-scanning direction. It is a figure which shows an example of the specific method of Embodiment 1 of this invention. FIG. 10 is a diagram illustrating an example of a specific method for specifying a position where a unit longitudinal toner amount changes suddenly according to the second exemplary embodiment of the present invention. FIG. 10 is a diagram illustrating an example of a specific method for adding a toner image in Embodiment 2 of the present invention. It is a figure which shows an example of the specific method of Embodiment 3 of this invention.

Explanation of symbols

1 Photosensitive drum 6b Secondary transfer counter roller (drive roller)
7b Primary transfer roller 9 Secondary transfer roller Bsp Margin start position Cz edge area Iz Normal image area Pz Transfer material area PT Front edge position Tsp Front edge margin start position T1 Primary transfer area

Claims (14)

Image forming means for forming a latent image according to image information on an image carrier, developing means for forming a toner image corresponding to the latent image on the image carrier, and transferring the toner image to a transfer material In an image forming apparatus that performs image formation by a transfer unit, and forms an image having no margin on the transfer material according to the image information corresponding to a region wider than the entire region of the transfer material,
The print rate of the toner image on the image carrier when the toner image enters the transfer means is gradually changed in the transport direction, which is the entering direction, of the image information. An image forming apparatus comprising: means for converting a density of a portion corresponding to the tip portion.   The image forming apparatus according to claim 1, wherein the printing rate is linearly increased over a predetermined range from an image start position on the leading end side of the toner image in the conveyance direction.   When the density of the portion corresponding to the leading edge of the image information is different in the direction perpendicular to the transport direction, the high density portion changes the printing rate in the transport direction more than the low density portion. The image forming apparatus according to claim 1, wherein the image forming apparatus is large.   When the print rate of the image information differs by a predetermined rate or more before and after a predetermined position on the leading end side of the toner image in the transport direction, an additional image having a predetermined print rate with respect to the print rate behind the predetermined position The image forming apparatus according to claim 1, wherein the information is added before the predetermined position to suppress a rapid change in the printing rate of the image information before and after the predetermined position.   Printing of the portion corresponding to the tip portion of the image information with respect to the center position in the direction perpendicular to the transport direction, the printing rate behind the predetermined position on one side is behind the predetermined position on the opposite side 5. The image forming apparatus according to claim 4, wherein the predetermined ratio for the additional image on the one side is lower than the predetermined ratio for the additional image on the opposite side when the ratio is higher. The developing unit forms a toner image of a plurality of colors corresponding to the latent image on the image carrier,
2. The image forming apparatus according to claim 1, wherein the printing rate linearly increases over a predetermined range from each position shifted so as not to overlap each color image start position on the leading direction side of each color toner image in the transport direction. .   The image forming apparatus according to claim 6, wherein the start position of each color image is shifted by deleting a portion of the image information corresponding to the leading end of the toner image of each color in the transport direction by a different length for each color. Image forming means for forming a latent image according to the image information on the image carrier, developing means for forming a toner image corresponding to the latent image on the image carrier, and primary for transferring the toner image to the intermediate transfer member An apparatus for forming an image by a transfer means and a secondary transfer means for transferring a transfer image on the intermediate transfer means to a transfer material, according to the image information corresponding to an area wider than the entire area of the transfer material. In an image forming apparatus for forming an image having no margin on the transfer material,
The image information so that the printing rate at the leading end of the transferred image when the transferred image on the intermediate transfer unit enters the secondary transfer unit is gradually changed in the transport direction that is the entering direction. An image forming apparatus comprising: means for converting a density of a portion corresponding to the tip portion of the image forming apparatus.   The image forming apparatus according to claim 8, wherein the printing rate is linearly increased over a predetermined range from an image start position on the leading end side of the transfer image in the transport direction.   When the density of the portion corresponding to the leading edge of the image information is different in the direction perpendicular to the transport direction, the high density portion changes the printing rate in the transport direction more than the low density portion. The image forming apparatus according to claim 8, wherein the image forming apparatus is large.   When the print rate of the image information differs by a predetermined rate or more before and after a predetermined position on the leading end side of the transfer image in the transport direction, an additional image having a print rate of a predetermined rate with respect to the print rate behind the predetermined position The image forming apparatus according to claim 8, wherein the information is added before the predetermined position to suppress a rapid change in the print rate of the image information before and after the predetermined position.   Printing of the portion corresponding to the tip portion of the image information with respect to the center position in the direction perpendicular to the transport direction, the printing rate behind the predetermined position on one side is behind the predetermined position on the opposite side 12. The image forming apparatus according to claim 11, wherein when the rate is higher than the rate, the predetermined ratio for the additional image on the one side is lower than the predetermined ratio for the additional image on the opposite side. The developing unit forms a toner image of a plurality of colors corresponding to the latent image on the image carrier,
9. The image forming apparatus according to claim 8, wherein the printing rate increases linearly over a predetermined range from each position shifted so that the respective color image start positions on the leading side in the entering direction of each color transfer image do not overlap in the transport direction. . The image forming apparatus according to claim 13, wherein the color image start position is shifted by deleting a portion of the image information corresponding to the leading end of the color transfer image in the entering direction by a different length for each color in the transport direction.

Images