JP2019012157A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus capable of suppressing a stain of a recording medium by toner in performing margin-free printing.SOLUTION: The image forming apparatus includes: image formation means for forming a toner image without a margin to each side of a recording medium on the basis of image data converted into an output color space; and toner amount control means for reducing a toner amount of the toner image in a fixed area of each side in comparison with the time of printing with a magin. The toner amount control means reduces the toner amount of a toner image of a side going along a conveyance direction of the recording medium more than the toner amount of a toner image of each side crossing the conveyance direction of the recording medium, and reduces the toner amount of a toner image of a side on a front edge side of the conveyance direction of the recording medium more than the toner amount of a toner image of a side on a rear edge side of the conveyance direction of the recording medium.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an image forming apparatus.

  Predetermined toner image formation by holding four color toner images with four color image recording signals from an image processing device that converts the input three color signals into four color image recording signals including black A toner image forming means for forming a four-color toner image on a toner image holding member transported from a position to a predetermined toner image transfer position, and a four-color toner image transported to the toner image transfer position on a recording medium An image processing apparatus used for an image forming apparatus comprising: a transfer fixing unit that transfers and fixes while heating by a heating body in contact with a heated body that is at least one of the recording medium and the toner image holding body A lightness determination means for obtaining a lightness signal indicating the brightness of the input three color signals, and a black ink for determining the under color removal amount and the black ink amount according to the lightness signal obtained by the lightness determination means. amount Image processing apparatus comprising a constant section, a is known (Patent Document 1).

JP 2000-278539 A

  The present invention provides an image forming apparatus capable of suppressing smearing of a recording medium due to toner during marginless printing.

In order to solve the above problem, an image forming apparatus according to claim 1,
Image forming means for forming a toner image without margins on each side of the recording medium based on the image data converted into the output color space;
A toner amount control means for reducing the toner amount of the toner image in a fixed region on each side compared to when printing with margins,
It is characterized by that.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
The toner amount control means changes the amount by which the toner amount of the toner image is decreased for each side;
It is characterized by that.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect,
The toner amount control means reduces the toner amount of the toner image on the side along the conveyance direction of the recording medium from the toner amount of the toner image on each side intersecting the conveyance direction of the recording medium;
It is characterized by that.

The invention according to claim 4 is the image forming apparatus according to claim 2 or 3,
The toner amount control means reduces the toner amount of the toner image on the front side in the transport direction of the recording medium to be smaller than the toner amount of the toner image on the rear side in the transport direction of the recording medium;
It is characterized by that.

The invention according to claim 5 is the image forming apparatus according to any one of claims 1 to 4,
The toner amount control means controls the toner amount of the toner image on the side along the conveyance direction of the recording medium to 2.0 g / cm ² or less;
It is characterized by that.

The invention according to claim 6 is the image forming apparatus according to any one of claims 1 to 4,
The toner amount control means sets the toner amount of the toner image on the side on the leading end side in the transport direction of the recording medium to 4.2 g / cm ² or less;
It is characterized by that.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects,
The toner amount control means controls the toner amount of the toner image on the side on the rear end side in the conveyance direction of the recording medium to 5.4 g / cm ² or less;
It is characterized by that.

The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 4,
The toner amount control means converts a part of the YMC equivalent amount of black component into K color when the image data in the fixed region of each side includes YMC color components as the output color space.
It is characterized by that.

The invention according to claim 9 is the image forming apparatus according to claim 8,
The toner amount control means is a YMC equivalent amount of black component so that the K color density is 1.4 or more when the image data in the fixed region of each side includes YMC color components as the output color space. Convert a part of to K color,
It is characterized by that.

According to a tenth aspect of the present invention, in the image forming apparatus according to the eighth or ninth aspect,
The toner amount control unit is configured to reduce the toner amount of the toner image on the side along the conveyance direction of the recording medium to be smaller than the toner amount of the toner image on each side intersecting the conveyance direction of the recording medium. Convert a part of the amount of black ink component to K color,
It is characterized by that.

The invention according to claim 11 is the image forming apparatus according to claim 8 or 9, wherein
The toner amount control means is configured to reduce the toner amount of the toner image on the front side in the transport direction of the recording medium to be smaller than the toner amount of the toner image on the side on the rear end side in the transport direction of the recording medium. Convert a part of the equal amount of black ink component to K color,
It is characterized by that.

According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the eighth to eleventh aspects,
The toner amount control means converts a part of the YMC equivalent amount of black component into K color so that the total amount of YMC toner of the toner image on each side of the recording medium is uniformly 120% or less.
It is characterized by that.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the eighth to eleventh aspects,
The toner amount control means controls the YMC equal amount of black component so that the total amount of YMC toner of the toner image on each side of the recording medium gradually decreases toward the outside of each side to 120% or less. Part to K color,
It is characterized by that.

  According to the first aspect of the present invention, compared with the configuration without the toner amount control means for reducing the toner amount of the toner image in the fixed region on each side of the recording medium as compared with the printing with the margin, the printing is performed without the margin. The contamination of the recording medium due to the toner can be suppressed.

  According to the second aspect of the present invention, each of the recording media can be printed at the time of printing without margins as compared with a configuration in which there is no adhesion increasing means for changing the amount of toner of the toner image for each side of the recording medium. It is possible to suppress the contamination of the recording medium due to the toner while suppressing the deterioration of the color of the edge.

  According to a third aspect of the present invention, the toner amount control means for reducing the toner amount of the toner image on the side along the conveyance direction of the recording medium from the toner amount of the toner image on each side intersecting the conveyance direction of the recording medium. Compared with a configuration that does not have this, it is possible to suppress smearing due to toner on the side along the conveyance direction of the recording medium during marginless printing.

  According to the fourth aspect of the present invention, the toner amount control means for reducing the toner amount of the toner image at the front end side in the conveyance direction of the recording medium from the toner amount of the toner image at the rear end side in the conveyance direction of the recording medium. Compared to the configuration without the margin, it is possible to suppress the contamination by the toner on the front side and the rear side in the transport direction of the recording medium during printing without margins.

  According to the fifth aspect of the present invention, it is possible to suppress smearing due to toner on the side along the recording medium conveyance direction during marginless printing.

  According to the sixth aspect of the present invention, it is possible to suppress the stain due to the toner on the front side in the conveyance direction of the recording medium during marginless printing.

  According to the seventh aspect of the present invention, it is possible to suppress the contamination of the side on the rear end side in the conveyance direction of the recording medium due to toner during marginless printing.

  According to the invention of claim 81, when the image data in the constant region of each side includes each color component of YMC that is the output color space, the toner amount that converts a part of the YMC equivalent amount of black component to K color Compared to a configuration that does not have a control means, it is possible to suppress smearing of the recording medium due to toner during marginless printing while suppressing deterioration of the color of the image formed at the end of the recording medium with the same amount of YMC. .

  According to the ninth, tenth, and eleventh aspects of the present invention, when the image data in a certain area on each side includes each color component of YMC that is an output color space, the KMC has a Y color density of 1.4 or more. Compared to a configuration that does not have a toner amount control means for converting a part of an equal amount of black ink into K color, while suppressing the deterioration of the color of an image formed at the YMC equal amount at the end of the recording medium. It is possible to prevent the recording medium from being smeared with toner during printing without margins.

  According to the invention described in claims 12 and 13, it is possible to suppress the color deviation and the occurrence of discontinuity while suppressing the change in the color of the edge of the recording medium.

1 is a schematic cross-sectional view showing an internal configuration of an image forming apparatus. It is a cross-sectional schematic diagram of a paper conveying apparatus including a secondary transfer unit. 2 is a block diagram illustrating an example of a functional configuration of an image forming apparatus. FIG. (A) is a diagram illustrating printing without margins, and (b) is a diagram illustrating printing with margins. FIG. 5 is a diagram illustrating toner image formation during marginless printing. It is a flowchart which shows the flow of operation | movement at the time of marginless printing. FIG. 6 is a diagram illustrating a relationship between a toner amount of a toner image formed on an intermediate transfer belt and a degree of contamination on a sheet conveyance path. FIG. 6 is a diagram illustrating an example in which the toner amount of a toner image in a certain area on each side of a sheet is decreased. 12 is a flowchart illustrating a flow of operations during marginless printing of the image forming apparatus according to the second embodiment. FIG. 6 is a diagram illustrating a relationship between a toner amount and a K color density degree when image data includes YMC color components. FIG. 6 is a diagram illustrating an example in which inking is performed by reducing the toner amount of a toner image in a certain region on each side of a sheet. (A) is a schematic diagram showing an example of density control according to Modification 1 of the edge region when enlarging an image for marginless printing, and (b) is an image enlarging for marginless printing. It is a schematic diagram which shows the example of the density | concentration control which concerns on the modification 2 of an edge part area | region. (A) is a diagram showing the amount of toner adhering to each side of the paper during marginless printing, and (b) is a diagram showing the relative degree of toner transfer occurring in the paper conveyance path after marginless printing.

Next, the present invention will be described in more detail with reference to the drawings with reference to embodiments and specific examples. However, the present invention is not limited to these embodiments and specific examples.
Also, in the description using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension and the like are different from the actual ones, and are necessary for the description for easy understanding. Illustrations other than members are omitted as appropriate.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

“First Embodiment”
(1) Overall Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view showing the internal configuration of the image forming apparatus 1 according to this embodiment.
Hereinafter, the overall configuration and operation of the image forming apparatus 1 will be described with reference to the drawings.

(1.1) Overall Configuration of Image Forming Apparatus The image forming apparatus 1 includes an image forming unit 10, a paper feeding device 20 mounted on the bottom of the image forming unit 10, an operation display unit 30, and an image processing unit 40. , And is configured.

  The image forming unit 10 includes a system control device 11, an exposure device 12, a photosensitive unit 13, a developing device 14, a transfer device 15, a paper transport device 16, and a fixing device 17, and is received from the image processing unit 40. The image information is formed as a toner image on the paper P sent from the paper feeding device 20.

A paper feeding device 20 having paper trays 21 and 22 is provided at the bottom of the image forming unit 10. Further, below the paper feeding device 20, the paper feeding device 20 is arranged in multiple stages in the vertical direction (in this embodiment, two stages). The tray module TM including the paper trays T1 and T2 that store the paper P is connected to supply the paper to the image forming unit 10.
In other words, a plurality of trays for storing sheets of different types (for example, material, thickness, sheet size, and grain) are provided, and sheets fed out from any one of the plurality of trays are stored in the image forming unit 10. It is comprised so that it may supply.

  The operation display unit 30 corresponds to a so-called user interface, and is specifically configured by combining a liquid crystal display panel, various operation buttons, a touch panel, and the like, and is used for inputting various settings and instructions and displaying information.

  The image processing unit 40 generates image data from print information transmitted from an external device 82 (illustrated in FIG. 3; for example, a personal computer).

(1.2) Configuration and Operation of Image Forming Unit 10 In the image forming apparatus 1 having such a configuration, every sheet printed by a print job in the paper feeding device 20 or the tray module TM in accordance with the timing of image formation. The sheet P fed out from the tray specified in (2) is sent to the image forming unit 10.

  The photoconductor unit 13 includes a photoconductor drum 131 which is provided in parallel above the paper feeding device 20 (Z direction) and is driven to rotate. On the respective photosensitive drums 131 on which the electrostatic latent images are formed by the exposure device 12, yellow (Y), magenta (M), cyan (C), and black (K) toner images are respectively developed by the developing devices 14. Is formed.

  The transfer device 15 includes an intermediate transfer belt 151 as an image carrier on which each color toner image formed on the photoconductive drum 131 of each photoconductor unit 13 is transferred, and each color toner formed by each photoconductor unit 13. A primary transfer roller 152 that sequentially transfers (primary transfer) the image to the intermediate transfer belt 151 is provided.

  The paper transport device 16 corrects the posture of the paper P fed out from the paper feeding device 20 and sends the paper P to the secondary transfer portion TR in accordance with the secondary transfer timing, and a driven roller 24b of the registration roller pair 24, And a secondary transfer roller 162 that collectively transfers (secondary transfer) each color toner image transferred onto the intermediate transfer belt 151 onto a sheet P as a recording medium. Further, the sheet P on which the transferred toner image is held is guided to the fixing nip portion NF of the fixing device 17 through the conveyance guide 166.

  Each color toner image formed on the photosensitive drum 131 of each photosensitive unit 13 is transferred onto the intermediate transfer belt 151 by a primary transfer roller 152 to which a predetermined transfer voltage is applied from a power supply device controlled by the system controller 11. Sequential electrostatic transfer (primary transfer) is performed to form a superimposed toner image in which toner of each color is superimposed.

The superimposed toner image on the intermediate transfer belt 151 is conveyed to the secondary transfer unit TR as the intermediate transfer belt 151 moves. When the superimposed toner image is conveyed to the secondary transfer unit TR, the paper P is supplied from the registration roller pair 24 to the secondary transfer unit TR in accordance with the timing.
A predetermined transfer voltage is applied to the secondary transfer roller 162 from the power supply device controlled by the system control device 11, and the multiple toner image on the intermediate transfer belt 151 is transferred to the paper P sent out from the registration roller pair 24. Batch transfer.

  The fixing device 17 includes a heating module 171 and a pressure module 172, and a fixing nip portion NF (fixing area) is formed by a pressure contact area between the heating module 171 and the pressure module 172. The sheet P on which the toner image is transferred in the secondary transfer unit TR is conveyed to the fixing device 17 via the conveyance guide 166 in a state where the toner image is not fixed. The toner image is fixed on the sheet P conveyed to the fixing device 17 by a pair of heating module 171 and pressure module 172 by the action of heating and pressure bonding.

  The sheet P on which the fixing toner image is formed is guided by the switching gate G1, and is discharged and accommodated from the first discharge roller pair 173 to the discharge tray portion TR1 on the upper surface of the image forming apparatus 1. When the paper is reversed for double-sided printing or discharged with the image recording surface facing upward, the conveyance direction is switched toward the conveyance guide 166 by the switching gate G1.

(2) Functional Configuration and Operation of Image Forming Apparatus 1 FIG. 2 is a schematic cross-sectional view of a sheet conveying device 16 including a secondary transfer unit TR, FIG. 3 is a block diagram illustrating an example of a functional configuration of the image forming apparatus 1, and FIG. (A) is printing without margins, (b) is a diagram explaining printing with margins, FIG. 5 is a diagram explaining toner image formation during printing without margins, and FIG. 13 (a) is each side of the paper during printing without margins. FIG. 7B is a diagram illustrating a relative degree of toner transfer that occurs in the paper conveyance path after marginless printing.

(2.1) Configuration of Paper Transport Device The paper transport device 16 includes a driven roller 24b of the registration roller pair 24, a paper guide guide 161, a secondary transfer roller 162, a cleaning blade 163, a collection container 164, a charge removal device 165, a transport. And a guide 166.
The secondary transfer roller 162 is in pressure contact with the backup roller 154 with the intermediate transfer belt 151 interposed therebetween to form a secondary transfer portion TR.

The intermediate transfer belt 151 is made of a resin such as polyimide or polyamide containing a suitable amount of a conductive agent such as carbon black, and is formed so that its volume resistivity is 106 to 1014 Ω · cm. The thickness is, for example, a film-like endless belt of about 0.1 mm.
The intermediate transfer belt 151 includes a backup roller 154 that also serves as a drive roller for circulatingly driving the intermediate transfer belt 151, and a driven roller 153 that supports the intermediate transfer belt 151 that extends substantially linearly along the direction in which the photosensitive drums 131 are arranged. 1), a tension roller 155 (not shown) that applies a constant tension to the intermediate transfer belt 151 and prevents the intermediate transfer belt 151 from meandering, and is provided on the upstream side of the secondary transfer portion TR. It has a support roller 156 for supporting.

The backup roller 154 is a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and the inside is made of EPDM rubber so that the surface resistivity is 10 ⁷ to 10 ¹⁰ Ω / □ and the roller diameter is 28 mm. The hardness is set to 70 degrees (Asker C), for example.
The backup roller 154 is disposed on the back side of the intermediate transfer belt 151 and forms a counter electrode of the secondary transfer roller 162. The backup roller 154 is disposed in contact with a metal power supply roller 154A that applies a bias voltage for forming a secondary transfer electric field in the secondary transfer portion TR.

The secondary transfer roller 162 is made of, for example, a semiconductive rubber having a surface resistivity of 10 ⁶ to 10 ¹⁰ Ω · cm having a surface layer made of a urethane rubber tube coated with fluorine, and the roller diameter is 28 mm. The hardness is set to 30 degrees (Asker C), for example.
The secondary transfer roller 162 is disposed to face the backup roller 154 via the intermediate transfer belt 151, and the toner held by the intermediate transfer belt 151 together with the backup roller 154 for the paper P conveyed from the paper feeding device 20. A secondary transfer portion TR for secondary transfer of the image is formed.

A cleaning device 167 that removes residual toner, paper dust, and the like adhering to the surface of the secondary transfer roller 162 is disposed opposite to the secondary transfer roller 162.
The cleaning device 167 includes a cleaning blade 163 that removes residual toner, paper dust, and the like attached to the surface of the secondary transfer roller 162, and a collection container 164 that stores the removed toner.

  A neutralization device 165 including an electrode member 165a and a guide guide 165b is disposed on the downstream side of the secondary transfer unit TR in the sheet conveyance direction. The sheet P on which the toner image has been secondarily transferred is separated and peeled off from the intermediate transfer belt 151 while being gradually electrified from the back surface of the sheet P by the electrode member 165a, and is guided by the guide guide 165b while passing through the transport guide 166. To the fixing device 17.

(2.2) Functional Configuration of System Control Apparatus The image forming apparatus 1 includes an image output control unit 111, a margin determination unit 112, a toner amount control unit 113, a power control unit 115, an exposure control unit 116, and a fixing temperature control unit 117. The system control device 11 is included, and the control program stored in the memory is executed to control the operation of the entire image forming apparatus 1.

The image output control unit 111 controls the exchange of information with the paper feeding device 20, as well as the exposure device 12, the photosensitive unit 13, the developing device 14, the transfer device 15, and the fixing device 17 provided in the image forming unit 10. Is given an operation control instruction.
The image output control unit 111 gives operation control instructions to the power control unit 115, the exposure control unit 116, and the fixing temperature control unit 117 included in the system control device 11. That is, it is determined whether or not to supply power to and drive the exposure device LH, the photosensitive unit 13, the developing device 14, the transfer device 15, the paper transport device 16, the fixing device 17 and the like constituting the image forming unit 10. The determination result is instructed to each control unit.

  Further, the image output control unit 111 exchanges information with the margin determination unit 112 and the toner amount control unit 113, and performs a predetermined operation control when it is determined that no margin printing is performed.

The margin determination unit 112 detects the presence or absence of a margin in the received image data on the paper P, and determines whether printing is performed without margins or normal printing (printing with margins).
As schematically shown in FIG. 4A, during normal printing (printing with a margin), the toner image is entirely contained in the sheet P, and an upper margin (mh), a lower margin (mb), There are peripheral margins of left margin (ml) and right margin (mr).
On the other hand, in marginless printing, as shown in FIG. 4B, the toner image reaches the end of the paper P, and the peripheral margin is eliminated. FIG. 4B illustrates a state in which there are no upper margin, lower margin, left margin, and right margin, but if there is no margin at some end portions, it is determined that printing is not performed.

(2.2) Printing without margins The image forming apparatus 1 has a normal printing mode in which an image is printed by providing a margin portion over the entire circumference of the end portion of the paper P, and an end portion of the paper P without a margin portion. It has a marginless printing mode for printing images all the way.
The presence / absence of the marginless print mode is determined by the margin determination unit 112 of the system control device 11 that controls the operation of the image forming apparatus 1.

FIG. 5A shows the size of a toner image formed on the intermediate transfer belt 151, where Iv is vertical and Ih is horizontal. FIG. 5B shows the size of the paper P, where Pv is vertical and Ph is horizontal.
The size relationship between the toner image and the paper P is set such that Pv <Iv and Ph <Ih, as schematically shown in FIG. In other words, the size of the toner image is formed to be slightly larger than the selected paper size so that no margin is generated in the paper P even if the paper P is fed slightly off the front, back, left and right.

  On the intermediate transfer belt 151, an Iv × Ih size toner image indicated by halftone dots is formed. The Iv × Ih size toner image is conveyed toward the secondary transfer portion TR by the intermediate transfer belt 151. On the other hand, the timing of the sheet P is controlled by the registration roller pair 24, and the toner image is conveyed to the secondary transfer unit TR as the toner enters the secondary transfer unit TR. A marginless toner image is formed.

  The paper P on which the marginless toner image having no margin is formed is fixed on the paper P by heat and pressure at the fixing nip portion NF of the fixing device 17. The sheet P on which the toner image has been fixed is peeled from the heating module 171 side at the exit of the fixing nip NF and discharged from the first discharge roller pair 173 to the discharge tray TR1 on the upper surface of the image forming apparatus 1.

  FIG. 13A shows the amount of toner adhering on the four sides of the paper P during marginless printing. In marginless printing, since the size of the toner image is larger than the size of the paper P, the toner image protruding from the paper P is transferred onto the secondary transfer roller 162 and scraped off and collected by the cleaning blade 163. Housed in a container 164.

  On the other hand, the toner image that is not transferred onto the secondary transfer roller 162 of the protruding toner image adheres to each side of the paper P. As shown in FIG. 12A, the amount of toner adhering to each side of the paper P is the largest at the leading edge and is small at the other sides. As for the paper type, the toner adhesion amount is larger for thick paper (250 gsm) than for plain paper (70 gsm). When the paper P is guided by the paper guide 161 and enters the secondary transfer portion TR, it is assumed that the leading edge of the paper P comes into contact with the intermediate transfer belt 151 holding the toner image without margins. .

  The toner adhering to each side of the paper P moves and accumulates around the guide guide 165b and the transport guide 166 of the static eliminator 165, and the back surface of the paper P passing through the paper transport path downstream from the secondary transfer portion TR is stained. There was a risk of occurrence.

  FIG. 13B shows the rate (influence degree) at which the toner adhering to each side of the paper P moves to and accumulates around the guide guide 165b and the conveyance guide 166. According to this, the amount of toner adhering to each side of the paper P is shifted from each side of the paper P to the periphery of the guide guide 165b and the conveyance guide 166 even though the leading edge LE is the largest. There are a lot of sides (left end side OE, right end side IE) along the conveyance direction of P, and then in order of the front end side LE and the rear end side TE. It is presumed that the left end side OE and the right end side IE have a longer distance in contact with the guide guide 165b and the conveyance guide 166 than the front end side LE and the rear end side TE. In addition, the effect of the thick paper is greater than that of the plain paper.

(3) Operation during marginless printing FIG. 6 is a flowchart showing the flow of operation during marginless printing, and FIG. 7 shows the toner amount of the toner image formed on the intermediate transfer belt 151 and the degree of contamination on the sheet conveyance path (grade). FIG. 8 is a diagram illustrating an example in which the toner amount of the toner image in a certain region on each side of the paper P is decreased.
The operation control during marginless printing will be described below with reference to the drawings.

In the image forming apparatus 1 according to the present embodiment, when the received print job is determined to be in the marginless printing mode, the toner amount TMA (intermediate transfer) of the toner image in a certain area on each side of the paper P is compared to printing with margins. The toner weight per unit area (g / cm ² ) formed on the belt 151 is reduced to perform marginless printing, and toner adhesion to each side of the paper P is suppressed.

  When the system control apparatus 11 receives the print job, the system control apparatus 11 determines whether the print job received by the margin determination unit 112 is printing without margin or printing with margin (S101). Specifically, by detecting whether or not there are peripheral margins of the upper margin (mh), lower margin (mb), left margin (ml), and right margin (mr) around the paper P, a part of the margin is detected. If there is no margin at the end, it is determined that printing without margin (S101: Yes).

When it is determined in step 101 that there is no margin printing mode (S101: Yes), the toner amount control unit 113 determines the toner amount TMA of the toner image in a certain area on each side of the paper P for each side as compared with normal printing. (S102).
Specifically, the toner amount in the constant areas R1 and R2 of the left end side OE and the right end side IE along the transport direction of the paper P, the front end LE that intersects the transport direction of the paper P, the constant area R3 of the rear end TE, The amount of toner in the constant region R3 of the leading edge LE on the leading side in the transport direction of the paper P is decreased from the toner amount TMA in the transporting direction of the paper P by the toner amount TMA of the constant region R4 on the trailing edge TE in the trailing direction of the paper P Decrease.

  As shown in FIG. 13B, the amount of toner adhering to each side of the paper P that moves to and around the conveyance guide 166 varies depending on the side of the paper P. Then, as shown in FIG. 7, if the toner amount of the toner image is smaller than the predetermined toner amount TMA for each side, the degree of contamination (grade) due to the toner in the paper transport path is allowed (G0.5). ) It is experimentally known that

As shown in FIG. 8, the toner amount control unit 213 reduces the toner amount in the fixed regions R1 and R2 of the left end side OE and the right end side IE along the transport direction of the sheet P to 2.0 g / cm ² or less. The toner amount in the constant region R3 of the front end LE that intersects the transport direction is controlled to 4.2 g / cm ² or less, and the toner amount in the constant region R4 of the rear end TE is controlled to 5.4 g / cm ² or less (S102). Then, printing without margins is performed (S103). Thus, by suppressing the toner adhering to each side of the paper P from moving around the electrode member 165a and the guide guide 165b, the degree of contamination by the toner on the paper transport path is set to an allowable level of G0.5 or less. Occurrence of contamination of the paper P passing through the paper conveyance path downstream from the next transfer portion TR can be suppressed.

“Second Embodiment”
FIG. 9 is a flowchart showing the flow of operations during marginless printing of the image forming apparatus 1A according to the present embodiment. FIG. 10 shows the relationship between the toner amount TMA and the K color density degree when the image data includes YMC color components. FIG. 11 is a diagram illustrating an example in which inking is performed by reducing the toner amount of a toner image in a fixed region on each side of the paper P. FIG.
Hereinafter, the operation control during marginless printing in the image forming apparatus 1A will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same component as the image forming apparatus 1 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted.

  In the image forming apparatus 1A according to the present embodiment, when printing without margins, the toner amount of the toner image in a certain area on each side of the paper P is reduced, and the edge area of the paper P further includes YMC color components. Converts a portion of the YMC equivalent amount of the black component into K color to suppress the deterioration of the color of the image and suppress the smearing of the paper P due to the toner during printing without margins.

Upon receipt of the print job, the system control device 11 determines whether the print job received by the margin determination unit 112 is printing without margins or printing with margins (S201), and when it is determined that the printing mode has no margins (S201: Yes). ), The toner amount control unit 113 reduces the toner amount TMA of the toner image in a certain region on each side of the paper P so that the toner amount becomes a predetermined toner amount for each side as compared with normal printing (S202).
Specifically, the toner amount control unit 213 sets the toner amount in the constant regions R1 and R2 of the left end side OE and the right end side IE along the transport direction of the paper P to 2.0 g / cm ² or less, and the transport direction of the paper P. The toner amount in the constant region R3 of the front end LE intersecting with the toner is controlled to 4.2 g / cm ² or less, and the toner amount in the constant region R4 of the rear end TE is controlled to 5.4 g / cm ² or less (S202).

  Next, it is determined whether or not a certain area on each side of the sheet P includes YMC color components (S203). If the predetermined area on each side of the paper P includes YMC color components (S203: Yes), it is further determined whether the total of YMC color components is 240% or less (S204).

As shown in FIG. 10, when the total color components of YMC are 240% or less, the K color density degree is less than 1.4, and it is known that the image looks closer to brown than black and the color is poor. Yes. For example, in FIG. 12, if each YMC color component (hereinafter referred to as 3C) is 240% in total, the toner amount TMA is 6.5 g / cm ² and the K color density degree exceeds 1.4. When the total amount of 3C is 180%, the toner amount TMA is 4.2 g / cm ² , the K color density degree is less than 1, and the appearance is brown.

When the sum of the YMC color components is 240% or less (S204: Yes), the toner amount control unit 213 converts some of the YMC equivalent ink components to K color so that the K color density is 1.4 or more. Conversion (inking) is performed (S205).
Specifically, as shown in FIG. 11, the toner amount control unit 213 sets the toner amount in the fixed regions R1 and R2 of the left end side OE and the right end side IE along the transport direction of the paper P to 2.0 g / cm ² or less. In order to achieve this, 3C is reduced to 0.2 g / cm ² for each color (0.6 g / cm ^{2 in} total for 3C), and K is added to 1.4 g / cm ² (inking). Further, in order to reduce the toner amount in the constant region R3 of the leading edge LE intersecting with the conveyance direction of the paper P to 4.2 g / cm ² or less, 3C is reduced to 1.0 g / cm ² for each color (3C in total) 3.0 g / cm ² ), 1.2 g / cm ^{2 of} K is added (inked), and the amount of toner in the constant region R4 of the rear end TE is 5.4 g / cm ² or less, so that 3C is changed to each color. It is reduced to 1.5 g / cm ² (4.5 g / cm ^{2 in} total for 3C), and 0.9 g / cm ^{2 of} K is added (inking) (S205).

  In this way, the toner amount of the toner image in the fixed regions R1, R2, R3, and R4 on each side of the paper P is reduced, and when each color component of YMC is included, the K color density is set to 1.4 or more. A portion of the YMC equivalent amount of black component is converted to K color (S205), and marginless printing is performed (S206).

  As a result, even when a certain area on each side of the paper P includes YMC color components, it is possible to suppress the stain of the paper P due to toner during marginless printing while suppressing deterioration of the color of the image.

"Modification 1"
FIG. 12A is a schematic diagram illustrating an example of density control of the end region when enlarging an image for marginless printing.
In the image forming apparatus 1A according to the first modification, when a certain area on each side of the paper P includes YMC color components, the total amount of YMC toner (3C total amount) of the toner image on each side of the paper P is uniformly 120%. A part of the YMC equivalent amount of black component is converted to K color so as to be as follows.

  As illustrated in FIG. 12A, when enlarging an image of a certain region R on each side of the paper P in order to perform marginless printing, an area Ra that becomes a marginless image, a protruding image from the paper P, and In the region Rb, the density change between the portion that becomes the image without margin and the original image portion (3C is 240%) by reducing the amount of toner of each color so that the total amount of 3C becomes 120% or less. To ease.

"Modification 2"
FIG. 12B is a schematic diagram illustrating another example of density control of the end region when enlarging an image for marginless printing.
In the image forming apparatus 1A according to the first modification, when a certain area on each side of the paper P includes YMC color components, the total YMC toner amount (3C total amount) of the toner image on each side of the paper P is equal to each side of the paper P. A part of the YMC equivalent amount of black component is converted to K color so that it gradually decreases toward the outside of the ink and reaches 120% or less.

  As shown in FIG. 12B, when enlarging the image of the fixed region R on each side of the paper P in order to perform marginless printing, the region Ra that becomes a marginless image, the protruding image from the paper P, and In the region Rb, a portion that becomes an image without a margin by reducing the amount of toner of each color so that the total amount of 3C gradually decreases toward the outside of each side of the paper P and becomes 120% or less. And the density change between the original image part (3C is 240%).

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Image forming part 11 ... System control apparatus 111 ... Image output control part 112 ... Margin determination part 113 ... Toner amount control part 12 ... Exposure apparatus DESCRIPTION OF SYMBOLS 13 ... Photosensitive unit 14 ... Developing device 15 ... Transfer device 16 ... Paper conveyance device 162 ... Secondary transfer roller 165 ... Static elimination device 165a ... Electrode member 165b ... Guide guide 166... Transport guide 17... Fixing device 20... Paper feeder 30 .. Operation display unit 40... Image processing unit P. ..Fixing nip

Claims (13)

Image forming means for forming a toner image without margins on each side of the recording medium based on the image data converted into the output color space;
A toner amount control means for reducing the toner amount of the toner image in a fixed region on each side compared to when printing with margins,
An image forming apparatus. The toner amount control means changes the amount by which the toner amount of the toner image is decreased for each side;
The image forming apparatus according to claim 1. The toner amount control means reduces the toner amount of the toner image on the side along the conveyance direction of the recording medium from the toner amount of the toner image on each side intersecting the conveyance direction of the recording medium;
The image forming apparatus according to claim 2. The toner amount control means reduces the toner amount of the toner image on the front side in the transport direction of the recording medium to be smaller than the toner amount of the toner image on the rear side in the transport direction of the recording medium;
The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. The toner amount control means controls the toner amount of the toner image on the side along the conveyance direction of the recording medium to 2.0 g / cm ² or less;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The toner amount control means sets the toner amount of the toner image on the side on the leading end side in the transport direction of the recording medium to 4.2 g / cm ² or less;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The toner amount control means controls the toner amount of the toner image on the side on the rear end side in the conveyance direction of the recording medium to 5.4 g / cm ² or less;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The toner amount control means converts a part of the YMC equivalent amount of black component into K color when the image data in the fixed region of each side includes YMC color components as the output color space.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The toner amount control means is a YMC equivalent amount of black component so that the K color density is 1.4 or more when the image data in the fixed region of each side includes YMC color components as the output color space. Convert a part of to K color,
The image forming apparatus according to claim 8. The toner amount control unit is configured to reduce the toner amount of the toner image on the side along the conveyance direction of the recording medium to be smaller than the toner amount of the toner image on each side intersecting the conveyance direction of the recording medium. Convert a part of the amount of black ink component to K color,
The image forming apparatus according to claim 8, wherein the image forming apparatus is an image forming apparatus. The toner amount control means is configured to reduce the toner amount of the toner image on the front side in the transport direction of the recording medium to be smaller than the toner amount of the toner image on the side on the rear end side in the transport direction of the recording medium. Convert a part of the equal amount of black ink component to K color,
The image forming apparatus according to claim 8. The toner amount control means converts a part of the YMC equivalent amount of black component into K color so that the total amount of YMC toner of the toner image on each side of the recording medium is uniformly 120% or less.
The image forming apparatus according to claim 8, wherein the image forming apparatus is an image forming apparatus. The toner amount control means controls the YMC equal amount of black component so that the total amount of YMC toner of the toner image on each side of the recording medium gradually decreases toward the outside of each side to 120% or less. Part to K color,
The image forming apparatus according to claim 8, wherein the image forming apparatus is an image forming apparatus.

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