JP7351229B2 - Image forming device, print control device, image forming method, print control method, and image forming system - Google Patents

Description

The present invention relates to an image forming apparatus that performs printing using developers of multiple colors.

In recent years, in image forming devices such as color electrophotographic printers, in addition to process color toners such as cyan (C), magenta (M), yellow (Y), and black (K), toners such as white (W) or clear are used as developers. Image forming apparatuses that use special color toner have been proposed.
In this image forming apparatus, a W layer is formed using special color toner to increase whiteness, and process color toner is transferred by superimposing it on the W layer to improve color reproducibility. In this case, the amount of toner in the W layer is limited to a certain amount because if the amount of toner in the W layer using the special color toner is too large, the excessive amount of toner will cause transfer and fixing defects and deterioration of print quality. .

Therefore, there are two cases: printing in one-time fixing mode, in which the CMYK layer and W layer are transferred and fixed at once, and printing in two-time fixing mode, in which CMYK layer and W layer are transferred and fixed in two steps. A technique is adopted to adjust the amount of toner in the W layer. That is, in the case of the one-time fixing mode, the amount of toner in the W layer is decreased, and in the case of the two-time fixing mode, the amount of toner in the W layer is increased. In this way, by adjusting the amount of toner in the W layer, the image forming apparatus suppresses the deterioration of print quality due to poor transfer and fixing caused by an excessive amount of toner, and improves color reproduction by increasing the whiteness of the W layer. (For example, see Japanese Patent Laid-Open No. 2015-18120 (Patent Document 1)).

Japanese Patent Application Publication No. 2015-18120

However, in the conventional image forming apparatus described above, when printing in the double fixing mode, the second transfer image is formed on top of the first transfer image, so the position of the second transfer image is If the transfer image is shifted from the first transfer image, a part of the first transfer image appears in a gap or the like, causing a problem such as streaks or the like as a result of printing.
The present invention aims to solve such problems, and when printing in the double fixing mode, even if the position of the transferred image formed in the second time is shifted from the transferred image formed in the first time, the printing result will not change. It is an object of the present invention to provide an image forming apparatus that makes streaks and the like less noticeable and improves print quality.

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention performs printing by transferring and fixing a plurality of color developers onto a print medium by one transfer number or multiple transfer times based on print data. an image forming apparatus, comprising: a print data receiving means for receiving the print data including print medium color information specifying a color of the print medium; and the print medium color of the print data received by the print data receiving means. and a transfer number transfer color determining means for determining the number of transfers and the color of the developer to be used based on the information, and the transfer number transfer color determining means determines whether the color of the printing medium in the printing medium color information is a dark color. In this case, the number of times the transfer is performed is multiple times, and the color of the developer in the last transfer is determined to be a color close to the color of the print medium in the print medium color information.

According to the present invention, with the above configuration, the last transfer color of the plurality of transfers is a transfer color close to the color of the printing medium, so that when printing is performed by transferring and fixing in a plurality of times, the transferred image Even if the position of the transferred image deviates from the desired position, it is possible to provide an image forming apparatus that makes streaks and the like caused by the positional deviation of the transferred image less noticeable and improves print quality.

1 is an internal explanatory diagram of an image forming apparatus according to a first embodiment; FIG. FIG. 3 is an explanatory diagram of an image forming unit and a transfer section according to the first embodiment. FIG. 1 is a block diagram of an image forming system according to a first embodiment. 1 is a diagram illustrating main functional blocks of an image forming apparatus and a general-purpose terminal according to a first embodiment. 1 is a flowchart diagram of an image forming system according to a first embodiment; FIG. FIG. 3 is a screen diagram of application settings according to the first embodiment. FIG. 7 is a screen diagram for setting printing paper color information Cp according to the first embodiment. FIG. 7 is a screen diagram for setting white toner usage range information Rwt according to the first embodiment. FIG. 3 is an explanatory diagram of a transfer number transfer color determination table according to the first embodiment; FIG. 7 is a flowchart for determining the number of transfers and transfer colors in the first embodiment. FIG. 3 is an explanatory diagram of a transferred image formed by the image forming apparatus according to the first embodiment. FIG. 3 is a top view of a transferred image formed by the image forming apparatus according to the first embodiment.

(First embodiment)
The configuration of the first embodiment, which is the best mode for carrying out the present invention, will be described below. In the drawings, elements common to each figure are given the same reference numerals. FIG. 1 is an internal explanatory diagram of an image forming apparatus according to the first embodiment. The image forming apparatus 1 transfers and transfers toner Tn (see FIG. 2) as a developer of multiple colors onto a printing paper P as a printing medium by one transfer number or two divided transfer numbers based on print data. It is fixed and printed.
As shown in FIG. 1, the image forming apparatus 1 includes a paper feed section 7, an image forming section 8, and a discharge section 12, which are surrounded by broken lines. The image forming apparatus 1 also includes a paper feed tray 6 , a transfer unit 9 having a transfer section 10 , a fixing device 11 , and an operation display section 14 . Hereinafter, in FIG. 1, the right side of the paper will be referred to as the "apparatus front side," and the left side of the paper will be referred to as the "apparatus rear side."

A paper feed tray 6 disposed at the bottom of the apparatus is a tray that stores printing paper P in a stacked manner. When starting printing, the printing paper P stacked on the paper feed tray 6 is fed one by one from the top in the direction shown by the arrow A by the paper feed roller 15 of the paper feed unit 7, and then in the direction shown by the arrow D. The image is then transported to the transfer section 10.
In order to control the conveyance of the printing paper P after being fed, the paper feed unit 7 includes a pair of paper feed conveyance rollers 16 and 17 and a paper feed detection sensor on the conveyance path from the paper feed roller 15 to the image forming unit 8. 19 and a timing detection sensor 20 are provided. The paper feed detection sensor 19 is a sensor that detects the conveyance state of the printing paper P, and the timing detection sensor 20 is a sensor that adjusts printing timing.

The image forming section 8 includes five image forming units 18W, 18C, 18M, 18Y, and 18K arranged in order from the front side of the apparatus toward the rear side of the apparatus. The plurality of image forming units 18W, 18C, 18M, 18Y and 18K each produce toner using toner Tn as a developer of white (W), cyan (C), magenta (M), yellow (Y) and black (K). form an image. Hereinafter, the image forming units 18W, 18C, 18M, 18Y, and 18K will be collectively referred to as the "image forming unit 18."
The image forming apparatus 1 has a transfer unit 9 disposed below the image forming section 8, facing the image forming section 8. The transfer unit 9 includes a transfer section 10, a primary transfer roller 37 for each image forming unit 18, an intermediate transfer belt 38, a belt drive roller 22, and driven rollers 23 and 24. The transfer unit 10 includes a driven roller 25 and a transfer roller 26 that performs secondary transfer. The intermediate transfer belt 38 is stretched by the belt drive roller 22 and the driven rollers 23 to 25, and rotates in the direction shown by arrow E (clockwise in the drawing) by the drive of the belt drive roller 22.

The toner image formed by the image forming section 8 is primarily transferred onto a rotating intermediate transfer belt 38 by a primary transfer roller 37, and later a primary transfer image Ts shown in FIG. 2 is formed. The primary transfer image Ts formed on the intermediate transfer belt 38 is secondarily transferred by the transfer unit 10 onto the printing paper P conveyed in the direction shown by the arrow D, and later forms the transfer image Tz shown in FIG. do.
The fixing device 11 includes a pressure roller 11a and a heating roller 11b having a heating section inside. The fixing device 11 presses the printing paper P on which the transferred image Tz is formed using a pressure roller 11a, and heats the printing paper P using a heating roller 11b to fix the transferred image Tz on the printing paper P.
The image forming apparatus 1 includes a return conveyance mechanism 28 and a front-back reversing mechanism 29 below the fixing device 11 . The return conveyance mechanism 28 includes a pair of return conveyance rollers 27, 71, and 72, and conveys the printing paper P when performing the second transfer and fixing subsequent to the first transfer and fixing. The front-back reversing mechanism 29 includes a pair of front-back reversing transport rollers 73, and transports the printing paper P when performing printing on the front side and then printing on the back side when performing double-sided printing.

The discharge section 12 transports the printing paper P on which the transfer and fixation has been performed in the direction shown by the arrow F, discharges it to the discharge stacker 13 at the top of the apparatus, and stacks the printing paper P in order. For this purpose, the discharge section 12 disposes pairs of discharge conveyance rollers 75 to 77 on the conveyance path from the fixing device 11 to the discharge stacker 13. The discharge section 12 further includes a discharge detection sensor 21 that detects the discharge state of the printing paper P and the like.
The operation display section 14 is provided at the upper part of the front side of the device for easy operation by the user. The operation display section 14 is configured, for example, by stacking a transparent touch panel that functions as an operation section on an LCD (Liquid Crystal Display) that functions as a display section. The user can use the operation display unit 14 to check the operation guidance and issue printing instructions such as starting printing.

(Configuration of image forming unit)
Next, the configurations of the image forming unit 18 and the transfer section 10 according to the first embodiment will be explained. FIG. 2 is an explanatory diagram of an image forming unit and a transfer section according to the first embodiment. Note that FIG. 2A shows the internal configuration of the image forming unit 18, and FIG. 2B shows the configuration of the transfer section 10. The image forming units 18W, 18C, 18M, 18Y, and 18K have the same configuration as that shown in FIG. 2(a).

As shown in FIG. 2A, the image forming unit 18 is provided with an LED head 31 facing the photoreceptor drum 30, and causes the LED head 31 to form an electrostatic latent image on the photoreceptor drum 30. Further, the image forming unit 18 includes toner cartridges 39 that are removably attached to the image forming unit 18, and each toner cartridge 39 stores toner Tn of each color.
Further, the image forming unit 18 includes a developing roller 34, a supply roller 35, and a developing blade 36. The developing roller 34 is disposed adjacent to the photoreceptor drum 30 and forms a toner image on the photoreceptor drum 30.

That is, the developing roller 34 rotates together with the photoreceptor drum 30 in the direction shown by arrow U, and develops the electrostatic latent image formed on the photoreceptor drum 30 by attaching toner Tn to it. The photosensitive drum 30 is made of a charging member, and is rotated in the direction shown by an arrow V by a driving force transmitted from a motor driving section 54 shown in FIG. 3 later.
The supply roller 35 supplies toner Tn to the developing roller 34. The supply roller 35 is disposed in contact with the developing roller 34 and rotates in the same direction as the developing roller 34 but at a circumferential speed that is different by a predetermined speed. The supply roller 35 rotates in the direction shown by an arrow T by a driving force transmitted from a motor drive section 54 shown in FIG. 3 later. The developing blade 36 is disposed with its tip in contact with the developing roller 34, and regulates the amount of toner on the developing roller 34.

Further, the image forming unit 18 includes a charging roller 32 and a cleaning blade 33. The charging roller 32 is a roller that uniformly charges the surface of the photoreceptor drum 30 to a predetermined charging voltage. The charging roller 32 is rotatably supported so as to rotate together with the photosensitive drum 30 in the direction shown by the arrow W. Further, the cleaning blade 33 is disposed with its tip in contact with the photoreceptor drum 30 with a predetermined pressure, and scrapes off the toner Tn remaining on the surface of the photoreceptor drum 30 after the primary transfer to the intermediate transfer belt 38. .
The image forming section 8 shown in FIG. 1 is composed of the image forming units 18W, 18C, 18M, 18Y, and 18K configured as described above. The image forming section 8 performs primary transfer of the toner images formed by each image forming unit 18 by sequentially superimposing the toner images formed by each image forming unit 18 onto an intermediate transfer belt 38 rotating in the direction shown by arrow E (clockwise in the drawing) using each primary transfer roller 37. , to form a primary transfer image Ts.

On the other hand, as shown in FIG. 2(b), the transfer unit 10 includes a driven roller 25 that rotates in the direction shown by arrow N and a transfer roller 26 that rotates in the direction shown by arrow Q.
The transfer unit 10 holds the printing paper P conveyed in the direction shown by the arrow D by the transfer roller 26 and the driven roller 25 to which a predetermined transfer voltage is applied by the power supply unit 55 shown in FIG. The image is transported to the fixing device 11 on the back side of the apparatus.
In this way, the transfer section 10 secondarily transfers the primary transfer image Ts formed on the intermediate transfer belt 38 by the image forming unit 18 onto the printing paper P, thereby forming a transfer image Tz.

(Configuration of image forming system)
Next, the configuration of the image forming system 2 will be explained. FIG. 3 is a block diagram of an image forming system according to the first embodiment. The image forming system 2 includes an image forming apparatus 1 and a general-purpose terminal 3 as a host device, and the image forming apparatus 1 prints based on print data transmitted from the general-purpose terminal 3.
As shown in FIG. 3, the image forming system 2 is configured to connect a general-purpose terminal 3 and an image forming apparatus 1 via a network 4. The network 4 is composed of a wired interface based on a LAN (Local Area Network). The network 4 may be a wireless interface using a wireless LAN, or may be a wired interface using a USB (Universal Serial Bus).

The general-purpose terminal 3 is configured of, for example, a PC (Personal Computer), and generates print data of image data displayed, created, or edited by a user, and transmits it to the image forming apparatus 1 . For this purpose, the general-purpose terminal 3 includes a terminal control section 40, a display device 41, an input device 42, a terminal communication section 43, and a terminal storage section 44. The terminal control section 40 is composed of a microprocessor or the like, and controls each of the above sections. The display device 41 is composed of an LCD (Liquid Crystal Display) or the like. The input device 42 is configured by mounting a transparent touch panel that functions as an operation section on an LCD. The input device 42 may have a configuration in which a keyboard, a mouse, etc. can be used together. The terminal communication section 43 controls an interface that connects to the communication section 53 of the image forming apparatus 1 via the network 4 . The terminal storage unit 44 stores image data and the like created by the user.

The image forming apparatus 1 prints on printing paper P based on print data transmitted from the general-purpose terminal 3. For this purpose, the image forming apparatus 1 includes a control section 50, an operation display section 14, a storage section 51, a print control section 52, a communication section 53, a motor drive section 54, and a power supply section 55. The control section 50 is composed of a microprocessor or the like, and controls each section. The operation display section 14 is configured by the operation display section 14 disposed at the upper part of the front side of the image forming apparatus 1 shown in FIG. 1 . The storage unit 51 stores a transfer number/transfer color determination table 68 shown later in FIG. 9, and the like.

The print control unit 52 controls the drive of a motor (not shown) by the motor drive unit 54, and controls the rotational drive of the supply roller 35, the photosensitive drum 30, and the like. Further, the print control section 52 controls the rotational drive of the paper feed roller 15, the paper feed conveyance roller pair 16 and 17, the belt drive roller 22, etc. by the motor drive section 54. In addition, the print control unit 52 controls the charging voltage of the charging roller 32 , the developing voltage of the developing roller 34 , the primary transfer voltage of the primary transfer roller 37 , and the transfer voltage of the transfer roller 26 using the power supply unit 55 . The communication unit 53 controls an interface that connects to the general-purpose terminal 3 via the network 4 .

Next, main functional blocks of the image forming apparatus 1 and the general-purpose terminal 3 will be explained. FIG. 4 shows main functional blocks of an image forming apparatus and a general-purpose terminal according to the first embodiment. First, the main functional blocks of the general-purpose terminal 3 will be explained. As shown in FIG. 4, the main parts of the general-purpose terminal 3 include an application 46 and a printer driver 47 as a print control device. Each of these units may be configured to function by the terminal control unit 40 as shown in FIG. 4, or may be configured to function separately from the terminal control unit 40.
The application 46 creates, displays, or edits image data to be printed by the user. Further, in the application 46, the user selects the printer driver 47 of the image forming apparatus 1 for printing. In addition, the application 46 outputs image data displayed by the user to the printer driver 47.

The printer driver 47 adds to the image data input from the application 46, print paper color information Cp as print medium color information that specifies the color of the print medium, which will be described later in FIG. Print data is generated by adding white toner usage range information Rwt as special color developer usage range information that specifies the range. For this purpose, the printer driver 47 includes a printing paper color setting unit 48 as a printing medium color setting unit for setting each of the above information, and a white toner usage range setting unit 49 as a special color developer usage range setting unit. Note that the image data input from the application 46 may be converted to image data in a printer description language format.
Furthermore, the printer driver 47 transmits the generated print data to the image forming apparatus 1 selected by the user via the network 4.

The printing paper color setting section 48 sets printing paper color information Cp that specifies the printing paper color. The printing paper color setting section 48 sets the printing paper color based on the user's selection later on the printing paper color setting screen G10 shown in FIG.
The white toner usage range setting unit 49 sets white toner usage range information Rwt that specifies the range on the printing paper in which white toner as a special color developer is used. The white toner usage range setting unit 49 sets the range in which white toner is used based on the user's selection on the white toner usage range setting screen G20 shown in FIG. 8 later.

Next, main functional blocks of the image forming apparatus 1 will be explained. As shown in FIG. 4, the main parts of the image forming apparatus 1 include a print data receiving section 61, a color converting section 62, a transfer number transfer color determining section 63, a white amount adjustment processing section 64, an image area enlarging section 65, a halftone It is composed of a processing section 66 and a printing section 67. Each of these units may be configured to function by the control unit 50 as shown in FIG. 4, or may be configured to function separately from the control unit 50.
The print data receiving unit 61 as a print data receiving unit receives print data including print paper color information Cp that specifies the print paper color and white toner usage range information Rwt that specifies the range in which white toner is used. It is something.

That is, the print data reception unit 61 receives print data from the printer driver 47 of the general-purpose terminal 3 and outputs image data and white toner usage range information Rwt to the color conversion unit 62. The image data is, for example, image data of 256 gradations for each color of RGB. Further, the print data receiving section 61 outputs the printing paper color information Cp and the white toner usage range information Rwt to the transfer number transfer color determining section 63 .

The color converter 62 converts the image data input from the print data receiver 61 into WCMYK image data of 256 gradations for each WCMYK color, which is the color space of the image forming apparatus 1 . In this color conversion, for example, image data of 256 gradations for each color of RGB is converted into WCMYK image data of 256 gradations for each color of WCMYK by a conversion method using a color conversion table, which is a known technique. The color conversion table is, for example, a three-dimensional lookup table that describes the relationship between the RGB color space and the WCMYK color space in consideration of the color reproduction characteristics of the image forming apparatus 1. The color conversion unit 62 outputs the WCMYK image data converted using the color conversion table to the white amount adjustment processing unit 64.

The transfer number transfer color determining unit 63 as a transfer number transfer color determining unit determines the number of transfers and the transfer color based on the printing paper color information Cp and the white toner usage range information Rwt input from the print data receiving unit 61. .
That is, the transfer number transfer color determining unit 63 determines the number of times of transfer and fixing (hereinafter referred to as the "transfer number") indicating whether printing is performed in the one-time fixing mode or the two-time fixing mode. Here, the one-time fixing mode when the number of transfers is one is the W layer of special color developer such as white (W) and the W layer of special color developer such as white (W) and This is a mode in which CMYK layers of process color toner are transferred and fixed at one time. Further, the two-time fixing mode when the number of transfers is two is a mode in which the W layer and the CMYK layer are transferred and fixed in two separate times.

Furthermore, when the number of transfers is two, the transfer number transfer color determining unit 63 determines the toner color used in the first transfer and fixing of the plurality of toners and the toner color used in the second and final transfer and fixing. Determine the toner color as the transfer color to be used during fixing. On the other hand, when the number of transfers is one, the transfer colors are all WCMYK colors.
Specifically, for example, as shown in step S37 later shown in FIG. 10, the transfer number transfer color determining unit 63 determines whether the white toner usage range information Rwt is such that white toner is used only in the area where an image is formed. When the printing paper color information Cp is not a light color (Light), that is, when it is a dark color, the number of transfers is set to two. Further, the transfer number transfer color determination unit 63 sets the transfer color in the first transfer as the first transfer to a color other than the second transfer color, and sets the transfer color in the second transfer as the last transfer as the printing paper color. The color should be close to .
The transfer number and transfer color determination section 63 outputs the determined number of transfers and transfer color to the white amount adjustment processing section 64 , image area enlarging section 65 , and printing section 67 .

The white amount adjustment processing unit 64 determines the total thickness of WCMYK toner based on the WCMYK image data input from the color conversion unit 62 and the number of transfers input from the transfer number and transfer color determination unit 63. Here, the total toner thickness is the total thickness necessary to reproduce colors using WCMYK toner, and refers to the total toner thickness that can be fixed at one time by electrophotographic printing. The total toner thickness is expressed as a percentage based on the amount of white toner required to mask the printing paper color, that is, the W layer thickness (100%).
The white amount adjustment processing unit 64 generates white amount adjusted WCMYK image data in which the amount of white toner is adjusted based on the determined WCMYK total thickness. The total thickness of WCMYK toner is set to be larger in the two-time fixing mode than in the one-time fixing mode. For example, in the case of the one-time fixing mode, the total thickness of WCMYK toner is 300%, and in the case of the two-time fixing mode, it is 340%.

The total thickness of the WCMYK toner is determined as follows. That is, the first condition is that the total thickness that can be transferred and fixed at one time is 300%. The second condition is that the total CMYK thickness required to reproduce colors using CMYK toner is 240%. Furthermore, the third condition is that the amount of white toner required to block the color of the printing paper P is 100%. Then, the order of dominance is first condition>second condition>third condition.
Under the above conditions, in the one-time fixing mode, the total thickness of WCMYK toner is 300% from the first condition. Furthermore, since the second condition requires that the CMYK total thickness be 240%, the third condition is not satisfied, but the white toner amount is set to 300%-240%=60%.
On the other hand, in the case of double fixing mode, even if the total CMYK thickness is 240% from the second condition and the white toner amount is 100% from the third condition, the first condition is satisfied, so the total WCMYK toner thickness is 240%+100%=340%.

The white amount adjustment processing section 64 adjusts the amount of white toner so that the total WCMYK toner thickness of the WCMYK image data input from the color conversion section 62 is equal to or less than the total WCMYK toner thickness determined based on the number of transfers. That is, when the total WCMYK toner thickness exceeds the total WCMYK toner thickness determined based on the number of transfers, the white amount adjustment processing unit 64 reduces the white toner amount by the amount that exceeds the total thickness of WCMYK toner, so that the total thickness of WCMYK toner becomes less than the total thickness of WCMYK toner. Adjust the white toner amount as shown.
The white amount adjustment processing section 64 adjusts the amount of white toner based on the WCMYK total thickness determined based on the number of transfers as described above, and outputs the generated white amount adjusted WCMYK image data to the image area enlarging section 65. . Note that the amount of toner is controlled by thinning out dots in the halftone processing section 66.

The image area enlarging unit 65 as an image area enlarging unit expands the image area of the second transferred color, which is the last transfer among the plurality of transfers, by a predetermined length (later shown in FIGS. 11(b) and 12(c). ΔLα) shown in ) is enlarged. That is, the image area enlarging unit 65 enlarges the image area of the second transfer color input from the transfer number transfer color determining unit 63 in the white amount adjustment WCMYK image data input from the white amount adjustment processing unit 64. Generate WCMYK image data. To enlarge the image area, edges of the image area of the transferred color are detected for the second time using a known image edge detection technique, and the detected edge portion is enlarged by a predetermined length (ΔLα).
The image area enlarging unit 65 uses the enlarged WCMYK image data generated as described above as WCMYK image data when the number of transfers is two, and sends the WCMYK image data as it is to the halftone processing unit 66 when the number of transfers is one. Output.

The halftone processing unit 66 binarizes the WCMYK image data input from the image area enlarging unit 65 by halftone processing, and generates WCMYK binary image data with two gradations for each WCMYK color. The halftone processing unit 66 outputs the generated WCMYK binary image data to the printing unit 67. The binarization process is performed using, for example, a dither method, which is a known technique.
The printing unit 67 as a printing unit prints the WCMYK binary image data input from the halftone processing unit 66 on the printing paper P based on the number of transfers and the transfer color input from the transfer number transfer color determination unit 63. .

(Operation of image forming system)
With the above configuration, the image forming system 2 according to the first embodiment operates as follows. FIG. 5 is a flowchart of the image forming system according to the first embodiment.
First, the user starts the general-purpose terminal 3 and starts the application 46 of the general-purpose terminal 3 shown in FIG. Thereafter, the user selects image data to be printed using the activated application 46 and starts printing. Note that the following display on the general-purpose terminal 3 is performed by the display device 41 shown in FIG. 3, and the setting operation by the user on the general-purpose terminal 3 is performed by the input device 42 shown in FIG.

Step S11: When printing is started by the user, the terminal control unit 40 (see FIG. 3) of the general-purpose terminal 3 uses the application 46 to display the application setting screen G01 shown in FIG. 6 below, and accepts application settings related to printing. . For example, the terminal control unit 40 of the general-purpose terminal 3 receives, as application settings, the selection of the printer driver 47 of the image forming apparatus 1 used for printing, print settings related to printing, such as the print range and the number of copies to be printed, etc., from the application 46. The application settings consist of setting contents common to each printer driver 47.

FIG. 6 is a screen diagram of application settings related to the first embodiment. As shown in FIG. 6, the terminal control unit 40 of the general-purpose terminal 3 displays a printer name setting field 102, a print range setting field 103, and a print number setting field 104 as an application setting screen G01. In addition, the terminal control unit 40 of the general-purpose terminal 3 displays operation guidance 101 that prompts the user to specify a printing method, an OK button 105, and a cancel button 106.
The printer name setting field 102 is a field for selecting the printer driver 47 of the image forming apparatus 1 used for printing, and displays selectable printer drivers 47 by printer name etc. using a pull-down menu. The print range setting field 103 is a field for setting which page of image data of a plurality of pages of image data is to be printed. The print copy number setting field 104 is a field for setting the number of copies to be printed.

The OK button 105 is a button that is pressed to maintain the settings and proceed to the next printer driver setting. The cancel button 106 is a button that is pressed to discard the settings and end printing. The user selects the printer driver 47, sets the print range, etc. on the application setting screen G01, and presses the OK button 105.
Returning to FIG. 5, when the user presses the OK button 105, the terminal control unit 40 of the general-purpose terminal 3 stores the content accepted as the application settings in the terminal storage unit 44 (see FIG. 3), and selects the next printer. Proceed to driver settings. The next printer driver settings are made up of unique settings for each printer driver 47.

Step S12 (printing media color setting step): The terminal control unit 40 of the general-purpose terminal 3 uses the printing paper color setting unit 48 (see FIG. 4) of the printer driver 47 to select the printing paper color specified by the user as one of the printer driver settings. The printing paper color information Cp that specifies the color information is set.
FIG. 7 is a screen diagram for setting printing paper color information Cp according to the first embodiment. As shown in FIG. 7, the terminal control unit 40 of the general-purpose terminal 3 displays six hues of red (R), yellow (Y), green (G), cyan (C), and blue ( B) and magenta (M) selection buttons are displayed for each of three brightness levels, for example. That is, the selection buttons are displayed as a dark color selection button row 112, a middle color selection button row 113, and a light color selection button row 114.

Further, the terminal control unit 40 of the general-purpose terminal 3 displays a white button 115 and a black button 116. These selection buttons are displayed in color. In this way, the printing paper color setting screen G10 displays the colors so that they can be selected and set separately into dark colors such as dark/middle colors and black, and light colors such as light colors and white.
In addition, the terminal control unit 40 of the general-purpose terminal 3 provides operation guidance 111 that prompts the user to select the color closest to the color of the printing paper P, and an OK button that is pressed to maintain the settings and proceed to the next setting. 117 and a return button 118 to be pressed to discard the settings and return to the application setting screen G01.

Returning to step S12 in FIG. 5, when the user presses the selection button for the color closest to the color of the printing paper P on the printing paper color setting screen G10 and presses the OK button 117, the terminal control of the general-purpose terminal 3 The unit 40 sets the color of the pressed selection button as the printing paper color. The terminal control unit 40 of the general-purpose terminal 3 uses the printer driver 47 to set the printing paper color as printing paper color information Cp and stores it in the terminal storage unit 44 (see FIG. 3).
The printing paper colors are 6 hues of red (R), yellow (Y), green (G), cyan (C), blue (B), and magenta (M), and 3 levels of dark color (Dark). This is represented by middle color and light color, and is referred to as printing paper color information Cp. Alternatively, the printing paper color may be represented by a button number for identifying each selection button, and may be used as the printing paper color information Cp.

Step S13 (special color developer usage range setting step): Next, the terminal control unit 40 of the general-purpose terminal 3 sets the white toner usage range setting unit 49 (see FIG. 4) of the printer driver 47 as another printer driver setting. , the white toner usage range information Rwt is set, which specifies the range in which white toner is used by the user.
FIG. 8 is a screen diagram for setting white toner usage range information Rwt according to the first embodiment. As shown in FIG. 8, the terminal control unit 40 of the general-purpose terminal 3 displays operation guidance 121 and radio buttons 122 to 124 to prompt the user to set the white toner usage range as the white toner usage range setting screen G20. indicate.

The radio button 122 is a button selected by the user when white toner is not used. When printing on white printing paper P such as plain paper, the user selects this radio button 122 because white toner is usually not used.
The radio button 123 is a button that the user selects when using white toner for the entire printing paper. The radio button 124 is a button selected when white toner is to be used only in the area where an image is formed (hereinafter referred to as "image area only"). When printing on dark/middle color or black printing paper P, white toner is normally used to mask the color of the printing paper, so the user selects the radio button 123 or the radio button Select 124. Note that the radio buttons 122 to 124 are displayed so that one of them can be selected.

The terminal control unit 40 of the general-purpose terminal 3 also controls the OK button 125, which is pressed to maintain the settings and continue printing, and the return button 126, which is pressed to discard the settings and return to the application setting screen G01. indicate. On the white toner usage range setting screen G20, the user selects one of the radio buttons 122 to 124 and presses the OK button 125 to input the white toner usage range.

Returning to step S13 in FIG. 5, when the user presses the OK button 125, the terminal control unit 40 of the general-purpose terminal 3 uses the printer driver 47 to convert the white toner usage range input by the user into white toner usage range information. Rwt and stored in the terminal storage unit 44 (see FIG. 3).
Note that the printing paper color setting screen G10 and the white toner usage range setting screen G20 may be displayed in order by displaying a property button (not shown) on the application setting screen G01 when the property button is pressed by the user. .

Step S14 (print data generation step): The terminal control unit 40 of the general-purpose terminal 3 converts, by the printer driver 47, the image data selected by the user in the application 46 into a printer description language format that can be interpreted by the image forming apparatus 1. and generate print data. At this time, the terminal control unit 40 of the general-purpose terminal 3 uses the printer driver 47 to read the printing paper color information Cp and the white toner usage range information Rwt that were set in steps S12 and S13 and stored in the terminal storage unit 44, and reads out the print paper color information Cp and the white toner usage range information Rwt, which are set in steps S12 and S13 and stored in the terminal storage unit 44. Add to.
Step S15 (print data transmission step): Under the control of the terminal control section 40 of the general-purpose terminal 3, the printer driver 47 transmits the print data generated in step S14 to the network using the terminal communication section 43 (see FIG. 3). The image is transmitted to the image forming apparatus 1 via the .

Step S21 (print data reception step): The control unit 50 (see FIG. 3) of the image forming apparatus 1 receives data from the printer driver 47 of the general-purpose terminal 3 via the network 4 by the print data reception unit 61 (see FIG. 4). Receive print data. That is, the control unit 50 of the image forming apparatus 1 receives print data including printing paper color information Cp that specifies the printing paper color and white toner usage range information Rwt that specifies the range in which white toner is used.
The control unit 50 of the image forming apparatus 1 causes the print data receiving unit 61 to output the image data and white toner usage range information Rwt included in the received print data to the color conversion unit 62. At the same time, the control unit 50 of the image forming apparatus 1 outputs the printing paper color information Cp and the white toner usage range information Rwt included in the received print data to the transfer number transfer color determination unit 63.

Step S22: The control unit 50 of the image forming apparatus 1 converts the image data input from the print data receiving unit 61 into WCMYK image data using the color conversion unit 62 (see FIG. 4). At this time, the control unit 50 of the image forming apparatus 1 determines the WCMYK toner total thickness based on the white toner usage range information Rwt. That is, the control unit 50 of the image forming apparatus 1 uses the color conversion unit 62 to set the total thickness of CMYK toner to 240% at maximum. Further, the control unit 50 of the image forming apparatus 1 causes the color conversion unit 62 to determine the amount of white toner based on the white toner usage range information Rwt. That is, the control unit 50 of the image forming apparatus 1 sets the white toner amount to 100% in areas where white toner is used, and sets the white toner amount to 0% in areas where white toner is not used.

Step S23 (transfer count transfer color determination step): The control unit 50 of the image forming apparatus 1 uses the transfer count transfer color determination unit 63 (see FIG. 4) to determine the white toner usage range information Rwt input from the print data reception unit 61. The number of transfers is determined based on the print paper color information Cp. Furthermore, the control unit 50 of the image forming apparatus 1 determines the transfer color based on the white toner usage range information Rwt and the printing paper color information Cp by the transfer number transfer color determination unit 63. Note that the number of transfers and the transfer color are determined using the number of transfers and transfer color determination table 68 shown later in FIG. 9, and by the number of transfers and transfer color determining operation shown later in FIG.

Step S24: Next, the control unit 50 of the image forming apparatus 1 determines the WCMYK total thickness by the white amount adjustment processing unit 64 (see FIG. 4) based on the number of transfers input from the transfer number transfer color determination unit 63. do. Further, the control section 50 of the image forming apparatus 1 causes the white amount adjustment processing section 64 to generate white amount adjusted WCMYK image data in which the amount of white toner is adjusted based on the determined total WCMYK thickness.

For example, the control unit 50 of the image forming apparatus 1 uses the white amount adjustment processing unit 64 to set the WCMYK total thickness to 340% when the number of transfers is 2, and adjusts the white toner amount so that the WCMYK total thickness is less than or equal to the WCMYK total thickness. A white amount adjusted WCMYK image is generated.
On the other hand, when the number of transfers is one, the control section 50 of the image forming apparatus 1 causes the white amount adjustment processing section 64 to set the WCMYK total thickness to 300% and adjust the white toner amount so that the WCMYK total thickness becomes the same. Generate a white amount adjusted WCMYK image.
Thereafter, the control section 50 of the image forming apparatus 1 causes the white amount adjustment processing section 64 to output the generated white amount adjustment WCMYK image data to the image area enlarging section 65 .

Step S25 (image area enlarging step): When the number of transfers is two, the control unit 50 of the image forming apparatus 1 causes the image area enlarging unit 65 (see FIG. 4) to set the image area of the second transfer color to a predetermined value. The enlarged WCMYK image data is generated by enlarging the length ΔLα (see FIG. 11(b)). On the other hand, when the number of transfers is one, the control unit 50 of the image forming apparatus 1 does not enlarge the image area by the image area enlarging unit 65 because a large positional shift does not occur.
In this way, the enlarged WCMYK image data is generated based on the white amount adjustment WCMYK image data input from the white amount adjustment processing section 64 and the number of transfers and the transfer color input from the transfer number transfer color determining section 63.

For example, if the number of transfers is two and the second transfer color is black (K), the control unit 50 of the image forming apparatus 1 causes the image area enlarging unit 65 to change the white amount adjustment WCMYK image data to black (K). Enlarged WCMYK image data is generated by enlarging the image area by ΔLα by a predetermined length. On the other hand, when the number of transfers is one, the control unit 50 of the image forming apparatus 1 does not cause the image area enlarging unit 65 to enlarge the black (K) image area.
The control unit 50 of the image forming apparatus 1 causes the image area enlarging unit 65 to output the enlarged WCMYK image data generated as described above to the halftone processing unit 66 when the number of transfers is 2, and when the number of transfers is 1. In this case, WCMYK image data is output to the halftone processing section 66. The enlarged WCMYK image data and WCMYK image data output to the halftone processing section 66 are, for example, 256 gradations for each WCMYK color.

Step S26: The control unit 50 of the image forming apparatus 1 binarizes the enlarged WCMYK image data or WCMYK image data inputted from the image area enlarging unit 65 using the halftone processing unit 66 (see FIG. 4), and binarizes each WCMYK color Generate gradation WCMYK binary image data. The control section 50 of the image forming apparatus 1 causes the halftone processing section 66 to output the generated WCMYK binary image data to the printing section 67 .

Step S27 (Printing process): The control unit 50 of the image forming apparatus 1 receives the information input from the halftone processing unit 66 based on the number of transfers and the transfer color input from the number of transfers transfer color determination unit 63 by the printing unit 67. The generated WCMYK binary image data is printed on printing paper P.
For example, if the number of transfers is "2" and the second transfer color is "black (K)", the control unit 50 of the image forming apparatus 1 causes the printing unit 67 to transfer the WCMY layer in the first transfer. Then, black (K) is transferred and fixed a second time, and printed on the printing paper P. On the other hand, when the number of transfers is "1 time", the control unit 50 of the image forming apparatus 1 causes the printing unit 67 to transfer and fix the WCMYK layer at one time and print it on the printing paper P.

Next, the operation of determining the number of transfers and the transfer color regarding the first embodiment in step S23 shown in FIG. 5 will be described. First, the transfer number transfer color determination table 68, which is referred to when the control unit 50 of the image forming apparatus 1 determines the number of transfers and the transfer color, will be described.
FIG. 9 is an explanatory diagram of a transfer number transfer color determination table according to the first embodiment. The transfer number transfer color determination table 68 is a table to be referred to when determining the transfer number and transfer color from the white toner usage range information Rwt and the printing paper color information Cp, and is stored in advance in the storage unit 51 shown in FIG. do. In FIG. 9, the transferred colors are represented by "W" for white, "C" for cyan, "M" for magenta, "Y" for yellow, and "K" for black.

As shown in FIG. 9, the transfer number transfer color determination table 68 is divided into a "not used" column 131, an "entire printing paper" column 132, and an "image part only" column 133 according to the white toner usage range information Rwt. be done. These correspond to the radio buttons 122, 123, and 124 used by the user to set the white toner usage range on the white toner usage range setting screen G20 shown in FIG.

The "not used" column 131 describes the number of transfers and the transferred color to be referred to when the white toner usage range information Rwt is "not used", that is, when the user sets white toner not to be used. In the "not used" column 131, the number of times of transfer is one and the transfer color is described as "CMYK", regardless of the printing paper color specified by the printing paper color information Cp.
The "Entire printing paper" column 132 describes the number of transfers and the transfer color to be referenced when the white toner usage range information Rwt is "Entire printing paper", that is, when the user sets white toner to be used on the entire printing paper. be done. The "Whole printing paper" column 132 indicates that regardless of the printing paper color specified by the printing paper color information Cp, the number of transfers is two, the first transfer color is "W", and the second transfer color is "CMYK".

The “Image portion only” column 133 contains the number of transfers and the number of transfers to be referred to when the white toner usage range information Rwt is “image portion only”, that is, when the user sets white toner to be used only in the portion where an image is formed. Transfer color is described.
In the "image part only" column 133, the color is described in correspondence with the color of the selection button displayed on the printing paper color setting screen G10 shown in FIG. 7, which is set by the user. That is, in the "image part only" column 133, the transfer color is divided into a dark/middle color (Dark/Middle) column 141, a black (K) column 142, a light color (Light) column 143, and a white (W) column 144. be done. In other words, the "Image part only" column 133 is divided into dark colors such as Dark/Middle and black (K), and light colors such as Light and white (W). .

The dark/middle color (Dark/Middle) column 141 has specific colors such as red (R), yellow (Y), green (G), cyan (C), blue (B), or magenta (M). Transfer colors are described separately. That is, in the Dark/Middle color column 141, the number of times of transfer is two, the first transfer color is other than the second transfer color, and the second transfer color is a color close to the printing paper color.

For example, if the printing paper color is red (R), the first transfer color is described as "WCK" other than the second transfer color "MY", and the second transfer color is superimposed to change the printing paper color. It is written as "MY", which has a color close to that of . In addition, if the printing paper color is yellow (Y), the first transfer color is described as "WCMK" other than the second transfer color "Y", and the second transfer color is a color close to the printing paper color. It is written as "Y". Similarly, when the printing paper color is green (G), cyan (C), blue (B), or magenta (M), the color that should be the first transfer color (other than the second transfer color) and the second The color that should be the first transfer color (a color close to the printing paper color) is described.

In the dark black (K) column 142, the number of times of transfer is 2, the first transfer color is described as "WCMY", and the second transfer color is described as "K". That is, in the black (K) column 142, the number of transfers is set to two, similar to the dark/middle color (Dark/Middle) column 141, the first transfer color is other than the second transfer color, and the second transfer color is printed. It is described as a color close to the paper color. Note that the black (K) column 142 may be included in the dark/middle color (Dark/Middle) column 141.

On the other hand, the light color column 143 indicates whether the printing paper color is red (R), yellow (Y), green (G), cyan (C), blue (B), or magenta (M). In the case of , the number of transfers is also one, and the transferred colors are described as all the colors of "WCMYK".
Further, in the light color white (W) field 144, the number of times of transfer is one, as in the case of the light color (Light) field 143, and the transferred colors are described as all the colors of "WCMYK". Note that the white (W) column 144 may be included in the light color (Light) column 143.

Next, the operation of determining the number of transfers and the transfer color in step S23 shown in FIG. 5 will be explained. FIG. 10 is a flowchart for determining the number of transfers and transfer color in the first embodiment.
Step S31: First, the control unit 50 of the image forming apparatus 1 determines whether the white toner usage range information Rwt input from the print data receiving unit 61 indicates “not used”. When the control unit 50 of the image forming apparatus 1 determines that the white toner usage range information Rwt is "not used", the process proceeds to step S32. On the other hand, when the control unit 50 of the image forming apparatus 1 determines that the white toner usage range information Rwt is not "not used", the process proceeds to step S33.

Step S32: The control unit 50 of the image forming apparatus 1 refers to the transfer number transfer color determination table 68, and determines the number of transfers according to the description in the "not used" column 131, regardless of which color the printing paper color information Cp is. Once, the transfer color is set to "CMYK" and the process is completed. That is, the control unit 50 of the image forming apparatus 1 returns to step S23 shown in FIG. 5, and prints on the printing paper P by the operations from step S24 onwards based on the determined number of transfers and transfer color.

Step S33: On the other hand, when the control unit 50 of the image forming apparatus 1 determines that the white toner usage range information Rwt input from the print data receiving unit 61 is not “not used”, the printing paper color information Cp It is determined whether the color is "light". Note that this determination may be made by determining whether any button in the selection button row 114 shown in FIG. 7 has been pressed, based on the button number or the like.
When the control unit 50 of the image forming apparatus 1 determines that the printing paper color information Cp is "Light", the process proceeds to step S34 in which the transfer color for the one-time fixing mode is determined.
Further, the control unit 50 of the image forming apparatus 1 determines that the printing paper color information Cp is not "light" but "dark/middle" or "black". If so, the process advances to step S35 in which the transfer color for the two-time fixing mode is determined.

Step S34: The control unit 50 of the image forming apparatus 1 refers to the transfer number transfer color determination table 68 shown in FIG. The number of times of transfer is set to 1, and the transferred color is set to "WCMYK".
Step S35: The control unit 50 of the image forming apparatus 1 determines if the printing paper color information Cp is not "Light", that is, if it is a dark "Dark/Middle color" or "Black". determines whether the white toner usage range information Rwt is "the entire printing paper".

When the control unit 50 of the image forming apparatus 1 determines that the white toner usage range information Rwt is "the entire printing paper", the process proceeds to step S36. On the other hand, when the control unit 50 of the image forming apparatus 1 determines that the white toner usage range information Rwt is "image portion only", the process proceeds to step S37.
Step S36: When the control unit 50 of the image forming apparatus 1 determines that the white toner usage range information Rwt is "the entire printing paper," it refers to the transfer number transfer color determination table 68 shown in FIG. According to the description in the "Whole paper" column 132, the number of transfers is set to two. Furthermore, the control unit 50 of the image forming apparatus 1 sets the first transfer color to "W" and the second transfer color to "CMYK."

Step S37: On the other hand, when the control unit 50 of the image forming apparatus 1 determines that the white toner usage range information Rwt is "image portion only", the control unit 50 of the image forming apparatus 1 selects the dark/middle color (Dark/Middle) column 141 shown in FIG. According to the black (K) column 142, the number of transfers is set to two. Further, the control unit 50 of the image forming apparatus 1 sets the first transfer color to a color other than the second transfer color, and sets the second transfer color to a color close to the printing paper color.

For example, when the printing paper color information Cp is "black", the control unit 50 of the image forming apparatus 1 sets the number of transfers to two. Further, the control unit 50 of the image forming apparatus 1 sets the first transfer color to "WCMY" other than the second transfer color, black (K), and sets the second transfer color to "black (K)", which is close to the printing paper color. )”.
In this way, the control unit 50 of the image forming apparatus 1 determines the number of transfers and the transfer color based on the printing paper color information Cp and the white toner usage range information Rwt by the transfer number transfer color determination unit 63. Thereafter, the control unit 50 of the image forming apparatus 1 returns to step S23 shown in FIG. 5, and prints on the printing paper P by the operations from step S24 onwards based on the determined number of transfers and transfer color.

(Printing operation)
Next, a printing operation executed by the image forming apparatus 1 according to the first embodiment in step S27 shown in FIG. 5 will be described. This printing operation will be explained using FIGS. 1 to 4.
The image forming apparatus 1 shown in FIG. 1 receives the WCMYK binary image data from the halftone processing section 66 by the printing section 67 (see FIG. 4), and receives the transfer number and transfer color from the transfer number and transfer color determination section 63. When received, the printing operation starts as follows.

First, the print control section 52 (see FIG. 3) drives the paper feed roller 15 and paper feed conveyance roller pair 16 and 17 of the paper feed section 7 shown in FIG. Print paper P is fed from the paper feed tray 6. Furthermore, the print control section 52 adjusts the printing timing using the timing detection sensor 20 and transports the printing paper P to the transfer section 10 . At this time, the print control unit 52 confirms that the conveyance state of the print paper P is normal using the paper feed detection sensor 19.

On the other hand, the print control section 52 transmits the driving force of the motor drive section 54 to the rotating shaft of the photoreceptor drum 30 of the image forming unit 18 through a connection gear (not shown), etc., in the direction shown by arrow V in FIG. 2(a). The photosensitive drum 30 is rotated. Similarly, the print control section 52 transmits the drive of the motor drive section 54 to the rotating shaft of the supply roller 35, and rotates the supply roller 35 in the direction shown by arrow T in FIG. 2(a). The toner Tn is supplied from the supply roller 35 to the developing roller 34 by the rotation of the supply roller 35 . The thickness of the toner Tn supplied to the developing roller 34 is regulated by the developing blade 36, and the toner Tn of a constant thickness is formed on the developing roller 34. At this time, the developing roller 34 and the charging roller 32 rotate together with the rotation of the photoreceptor drum 30, and rotate in the directions shown by arrows U and W in FIG. 2(a).

Further, the print control unit 52 causes the power supply unit 55 (see FIG. 3) to apply a predetermined charging voltage to the charging roller 32 to uniformly charge the surface of the photoreceptor drum 30. Thereafter, the print control unit 52 causes the LED head 31 to emit light to form an electrostatic latent image pattern on the surface of the photoreceptor drum 30 based on the print data.
Further, the print control section 52 applies a predetermined supply voltage to the supply roller 35 and a predetermined development voltage to the development roller 34 using the power supply section 55 . The toner Tn on the developing roller 34 is charged to a predetermined amount of charge by this supply voltage and the developing voltage. Thereafter, the toner Tn on the developing roller 34 adheres to the electrostatic latent image pattern formed on the photoreceptor drum 30 to form a toner image on the photoreceptor drum 30.

On the other hand, the print control section 52 causes the motor drive section 54 to drive the belt drive roller 22 (see FIG. 1) and at the same time drive the driven rollers 23 to 25, so that the intermediate transfer belt 38 moves in the direction shown by arrow E in FIG. (clockwise). Through this rotation, the toner image formed on the photosensitive drum 30 is primarily transferred onto the intermediate transfer belt 38 by the primary transfer roller 37 rotating in the direction shown by arrow Y in FIG. 2(a).
In this way, the toner images formed on the photoreceptor drums 30 of the image forming units 18 for each color of WCMYK are primary transferred onto the intermediate transfer belt 38 in order of being superimposed, and the primary transfer image Ts shown in FIG. 2(a) is obtained. It is formed.

Furthermore, the print control unit 52 moves the intermediate transfer belt 38 in the direction shown by arrow E in FIG. The image is secondarily transferred onto the printing paper P being conveyed to form a transfer image Tz. At this time, the print control section 52 applies a predetermined transfer voltage to the transfer roller 26 using the power supply section 55 to control the secondary transfer. Thereafter, the print control section 52 causes the motor drive section 54 to transport the printing paper P onto which the transfer image Tz has been transferred to the fixing device 11, and fixes the transfer image Tz on the printing paper P. That is, the print control unit 52 heats the heating roller 11b of the fixing device 11 using the power supply unit 55, presses the printing paper P on which the transferred image Tz is formed using the pressure roller 11a, and transfers the transferred image Tz to the printing paper P. Let it settle in.

Thereafter, in the one-time fixing mode in which the number of transfers is “1 time”, the print control unit 52 transports the printing paper P by the pair of ejection transport rollers 75 to 77 shown in FIG. . At this time, the print control unit 52 uses the discharge detection sensor 21 to confirm that the conveyance state of the printing paper P to the discharge stacker 13 is normal.
On the other hand, in the two-time fixing mode in which the number of transfers is "2 times", the print control unit 52 does not eject the printing paper P onto which the first transfer image Tz has been transferred and fixed, and instead uses the return conveyance mechanism 28 transport to. That is, the print control unit 52 switches the conveyance path using a conveyance path switching guide (not shown), conveys the printing paper P in the direction shown by the arrow H in FIG. 72 to convey in the directions shown by arrows J and L in FIG.

The print control unit 52 adjusts the printing timing of the returned printing paper P using the timing detection sensor 20 in the same way as the first time, and causes the primary transfer image Ts of the remaining colors to be primarily transferred onto the intermediate transfer belt 38 . That is, the print control unit 52 causes the image forming units 18 of the remaining colors to form toner images, and transfers the toner images to the intermediate transfer belt 38 to form the primary transfer image Ts. Thereafter, the print control unit 52 transfers the primary transfer image of the remaining color to the transfer image Tz on the printing paper P which has been fixed for the first time and is being conveyed in the direction shown by the arrow D in FIG. 1 by the transfer unit 10. Ts is superimposed and secondary transfer is performed. Furthermore, the print control section 52 causes the fixing device 11 to fix the transfer image Tz of the remaining colors, and the discharge section 12 discharges the printing paper P to the discharge stacker 13 . In addition, when performing double-sided printing, printing is similarly performed on both sides of the printing paper P using the front-back reversing mechanism 29.
In this way, the printing unit 67 (see FIG. 4) controls printing by the print control unit 52 and prints on the printing paper P.

(Explanation of transferred image)
Next, a transfer image Tz formed by the image forming apparatus 1 according to the first embodiment will be described. FIG. 11 is an explanatory diagram of a transferred image formed by the image forming apparatus according to the first embodiment. FIG. 11 shows a transferred image Tz when the white toner usage range information Rwt is "image portion only", and is a diagram of the printing paper P viewed from the side with respect to the transport direction. In addition, FIG. 11(a) shows that a W layer 81, a C layer 82, an M layer 83, and a Y layer 84 (hereinafter referred to as "W layer 81, etc.") are formed on black printing paper P by the first transfer. , is a schematic diagram of a transferred image Tz in which a K layer 85 is formed by the second transfer. FIG. 11B shows a transferred image Tz in which the W layer 81 and the like are formed on the black printing paper P by the first transfer, and the image area of the K layer 85 is enlarged by the image area enlarger 65 in the second transfer. FIG.

As shown in FIG. 11, when the printing paper color information Cp is black, the image forming apparatus 1 forms a W layer 81 made of white toner as a base in the first transfer to improve color reproducibility. The image forming apparatus 1 sequentially forms a C layer 82, an M layer 83, and a Y layer 84 made of cyan (C), magenta (M), and yellow (Y) toners Tn, superimposed thereon. Thereafter, in the second transfer, the image forming apparatus 1 further forms a black (K) layer 85 in a superimposed manner.

In this way, when the transfer is performed in two steps, as shown in FIG. It shifts. This positional shift occurs due to detection errors of the timing detection sensor 20 shown in FIG. 1 between the first transfer and the second transfer, and variations in the skew amount of the printing paper P. As a result, a positional shift occurs between the W layer 81 etc. by the first transfer and the K layer 85 by the second transfer, resulting in a gap between the overhang area 88 that covers the W layer 81 etc. A crevice region 89 appears as a streak. Misalignment can occur in any direction, front, back, left, or right with respect to the conveyance direction of the printing paper P, and the direction in which it occurs varies depending on the cause.

In the image forming apparatus 1 according to the first embodiment, the transfer number transfer color determining unit 63 sets the second transfer color to a color close to black of the printing paper color, that is, black (K), and forms the K layer 85. Therefore, even if such a positional shift occurs, the streaks or the like caused by the eaves area 88 are not noticeable when viewed from the top surface of the printing paper P.

Furthermore, the image forming apparatus 1 according to the first embodiment expands the image area of the K layer 85 into a predetermined area by the image area enlarging unit 65, as shown in the left and right hatched areas of the K layer 85 shown in FIG. It is expanded by the length ΔLα. As a result, in the K layer 85, a first enlarged region 91 having a black (K) length ΔLα is added to the gap region 89. Therefore, the image forming apparatus 1 can make streaks and the like generated by the gap area 89 less noticeable. Note that the predetermined length of enlargement ΔLα may be determined by measuring the length of the above-mentioned positional deviation through experiments or the like, and may be, for example, about 0.2 mm to 0.3 mm.
In this case, in the K layer 85 shown in FIG. 11(b), a second enlarged area 92 having a length ΔLα is added to the eaves area 88 at the same time, but the second enlarged area 92 is also black, which is the printing paper color. The second enlarged area 92 is also inconspicuous because it is formed using black (K), which is a color close to that of the second enlarged area 92.

Further, a transfer image Tz formed by the image forming apparatus 1 according to the first embodiment will be explained using a top view. FIG. 12 is a top view of a transferred image formed by the image forming apparatus according to the first embodiment. Similar to FIG. 11, FIG. 12 shows the transferred image Tz when the white toner usage range information Rwt is "image portion only". In FIG. 12, a black printing paper P has a circular base of a W layer 81, and the top layer has a black K layer 85 in a ring shape, and the outer diameter of the ring shape of the K layer 85 is This indicates that it is slightly shorter than the circular diameter of the W layer 81. Furthermore, between the base W layer 81 and the top K layer 85, circular CMY layers 82 to 84 with the same diameter as the outer diameter of the annular figure are printed in pale gray. is a schematic diagram of the transferred image Tz in which the CMY layers 82 to 84 appear on the inner diameter of the annular figure.

FIG. 12A shows an ideal transferred image Tz formed in the two-time fixing mode, with no deviation in the K layer 85 of the second time. FIG. 12B shows a transferred image Tz that was formed in the two-time fixing mode and in which a shift occurred in the K layer 85 at the second time. In addition, in the figure, the gap region 89 is shown in an exaggerated manner. FIG. 12(c) is a transfer image Tz in which the image area of the K layer 85 is formed for the second time by the image area enlarging unit 65 according to the present embodiment, and a portion X surrounded by a broken line is the first enlarged area. 91 and an enlarged view of the periphery of a second enlarged region 92. FIG. In addition, in the figure, the first enlarged area 91 and the second enlarged area 92 are shown in an exaggerated manner.

In the two-time fixing mode, as shown in FIG. 12(b), the second K layer 85 is displaced relative to the first W layer, etc., for example, in the direction of arrow Z, resulting in a positional shift. As a result, a gap region 89 is generated, and streaks and the like are generated on the opposite side of the annular shape of the K layer 85 in the direction of arrow Z. On the other hand, in the direction of the arrow Z of the annular figure of the K layer 85, an eaves area 88 is generated in the K layer 85 so as to cover the W layer 81 and the like, but since the printing paper P is black, it is not noticeable.
In the image forming apparatus 1 according to the first embodiment, the image area enlarging section 65 enlarges the image area of the K layer 85 by a predetermined length ΔLα, as shown in FIG. 12(c). Therefore, the gap region 89 that occurs on the opposite side of the annular shape of the K layer 85 in the direction of the arrow Z disappears due to the first enlarged region 91, and streaks and the like become less noticeable.

On the other hand, in the direction of the arrow Z of the annular figure of the K layer 85, the image area of the K layer 85 has a second enlarged area 92 added to expand the eaves area 88, but since the printing paper P is black, it is not noticeable.
In addition, the image area of the K layer 85 is expanded by a second expansion of the length ΔLα in the outer area R2 of the image area of the K layer 85, as shown in the part X surrounded by the broken line in FIG. 12(c). In addition to adding the region 92, a first enlarged region 91 is also added to the inner region R1 of the image region of the K layer 85. Therefore, even if streaks or the like occur due to positional deviation in the inner region R1 of the image area of the K layer 85, the streaks or the like can be made less noticeable by the second enlarged region 92.
In the above description, the direction of displacement of the K layer 85 has been explained as being in the direction of arrow Z. However, the direction of displacement may be opposite to the direction of arrow Z or left and right in the direction of arrow Z as the up and down direction in the paper. Even if there is a shift in the direction, it is possible to make streaks or the like caused by the position shift less noticeable.

As described above, according to the image forming apparatus 1 according to the first embodiment, since the second transfer color is a color close to the printing paper color, the image forming apparatus 1 that is used for the second transfer is a color that is close to the printing paper color. The eaves area 88 can be made less noticeable. Further, according to the image forming apparatus 1 according to the first embodiment, since the image area of the second transferred color is expanded by a predetermined length ΔLα in all directions around it, the image area of the second transferred color is It is also possible to make the gap area 89 caused by the positional deviation of the transferred image Tz less noticeable.

(Modification 1)
The present invention is not limited to the above-described embodiments, but can be modified based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention. For example, in the above embodiment, a printer is used as an example of the image forming apparatus 1, but the image forming apparatus 1 may be a copying machine, a facsimile machine, or a multifunction peripheral. In addition, in the above embodiment, the image forming apparatus 1 using an electrophotographic method is described as an example, but the printing method may be an electrostatic recording method, an electrostatic printing method, a toner jet method, or the like. Further, in the description of the embodiments above, the printing method has been described as an intermediate transfer method, but the printing method may be a direct transfer method.

(Modification 2)
Furthermore, in the above embodiments, toner is used as an example of the developer, but the developer may be other types of developer such as ink. In addition, in the above embodiments, the printing paper P was used as an example of the printing medium, but the printing medium may be a card-shaped printing medium or a booklet-shaped printing medium. . Further, in the above embodiments, the special color developer that improves color reproducibility is described as a white toner, but the special color developer may be other toners.

(Modification 3)
Further, in the above description of the embodiment, an example was described in which the image forming apparatus 1 performs printing using the image forming unit 18 of five colors, including CMYK colors and W color, but the following method may be used. That is, the image forming apparatus 1 may be configured with image forming units 18 of colors other than WCMYK, or may be configured with image forming units 18 of six or more colors.

(Modification 4)
Furthermore, in the above description of the embodiment, an example of the image forming apparatus 1 that transfers and fixes in two steps has been described, but the image forming apparatus 1 transfers and fixes in three or more steps. The present invention can also be applied to such cases. In this case, the second transfer color in the description of the embodiment above is the transfer color that is transferred and fixed last among the plurality of transfers, the last transfer color is a color close to the printing paper color, and The image area of the last transferred color is expanded by a predetermined length ΔLα.

(Modification 5)
Further, in the above embodiment, the printing paper color is set by the user on the general-purpose terminal 3, but it may be set as follows. That is, the image forming apparatus 1 may provide an optical sensor or the like near the conveyance path for conveying the printing paper P to optically detect the printing paper color and set it as the printing paper color. In this case, the printer driver 47 of the general-purpose terminal 3 shown in FIG. 4 does not need to include the printing paper color setting section 48 as a printing paper color setting means.

(Modification 6)
Furthermore, in the above embodiment, it has been explained that the user sets the printing paper color and the white toner usage range on the general-purpose terminal 3. You can also do this. In this case, the image forming apparatus 1 is provided with a printing paper color setting section 48 and a white toner usage range setting section 49, and the user uses the operation display section 14 of the image forming apparatus 1 to set the printing paper color and the white toner usage range. settings.

(Modification 7)
Furthermore, in the above embodiment, the image forming apparatus 1 was described as enlarging the image area of the second transfer color by a predetermined length using the image area enlarging section 65. You can do it like this. That is, the printer driver 47 of the image forming apparatus 1 or the general-purpose terminal 3 displays a setting screen on the operation display unit 14 or the display device 41 on which the enlargement length can be arbitrarily set, and the user can arbitrarily set the enlargement length ΔLα. It may also be possible to set it.

1 Image forming device 2 Image forming system 3 General purpose terminal 4 Network 8 Image forming section 9 Transfer unit 10 Transfer section 11 Fixing device 18 Image forming unit 37 Primary transfer roller 38 Intermediate transfer belt 40 Terminal control section 46 Application 47 Printer driver 48 Print paper Color setting section 49 White toner usage range setting section 50 Control section 52 Print control section 61 Print data receiving section 63 Transfer count transfer color determination section 64 White amount adjustment processing section 65 Image area enlargement section 67 Print section 68 Transfer count transfer color determination table P Printing paper Tz Transfer image Cp Printing paper color information Rwt White toner usage range information

Claims (15)

An image forming apparatus that prints by transferring and fixing a plurality of color developers onto a print medium based on print data, using a single transfer number or a plurality of transfer times, the image forming apparatus comprising:
print data receiving means for receiving the print data including print medium color information that specifies the color of the print medium;
a transfer number transfer color determining means for determining the number of transfers and the color of the developer to be used based on the print medium color information of the print data received by the print data receiving means;
When the color of the printing medium in the printing medium color information is a dark color, the transfer number transfer color determining means sets the number of transfers to the plurality of times, and sets the color of the developer of the last transfer to the An image forming apparatus characterized by determining a color close to a color of the print medium in the print medium color information. The print data further includes special color developer use range information that specifies a range on the print medium in which the special color developer is used,
The transfer number transfer color determining means determines the number of transfers and the color of the developer to be used based on the printing medium color information and the special color developer usage range information, and the special color developer usage range information is determined based on the special color developer usage range information. When the developer is used only in the area where an image is formed and the color of the printing medium is the dark color, the number of transfers is the plurality of times, and the development of the last transfer is 2. The image forming apparatus according to claim 1, wherein the color of the agent is determined to be a color close to the color of the print medium according to the print medium color information. 3. The image forming apparatus according to claim 2, further comprising image area enlarging means for enlarging an image area on the print medium of the color of the developer in the last transfer by a predetermined length. 3. The image forming apparatus according to claim 2, wherein the special color developer is white toner. Claim: further comprising a storage unit that stores a transfer number transfer color determination table that is referred to when determining the number of transfers and the color of the developer from the special color developer use range information and the printing medium color information. 4. The image forming apparatus according to 4. Printing control that transmits the print data to the image forming apparatus for transferring and fixing the developer of a plurality of colors onto the print medium and printing it by the number of times of transfer once or the number of times divided into multiple times based on the print data. A device,
Print media color setting means for setting print media color information that specifies the color of the print media;
and a special color developer usage range setting means for setting special color developer usage range information that specifies the range on the printing medium in which the special color developer is used,
In order to cause the image forming apparatus to determine the number of transfers and the color of the developer based on the printing medium color information and the special color developer usage range information, the printing medium color information and the special color developer usage range information are used. A print control device that generates the added print data. 7. The printing control device according to claim 6, further comprising an operation display section that selectably displays the color of the printing medium in the printing medium color information as either a dark color or a light color. Further, the operation display unit may provide the special color developer usage range information indicating whether the special color developer is used for the entire print medium or the special color developer is used for a portion of the print medium where an image is formed. 8. The printing control device according to claim 7, wherein either one of the following is selectably displayed: or not using the special color developer. a printing step of transferring and fixing a plurality of color developers onto a print medium based on print data in a single transfer number or a plurality of transfer times;
a print data receiving step of receiving the print data including print medium color information that specifies the color of the print medium and special color developer use range information that specifies the range on the print medium in which the special color developer is used;
An image forming method comprising: a transfer number/transfer color determining step of determining the number of transfers and the color of the developer based on the printing medium color information and the special color developer use range information. In the transfer number transfer color determination step, when the special color developer use range information indicates that the special color developer is used only in the area where an image is formed and the printing medium color information is a dark color, Image formation according to claim 9, wherein the number of times of transfer is the plurality of times, and the color of the developer in the last transfer is a color close to the color of the printing medium in the printing medium color information. Method. 11. The image forming method according to claim 10, further comprising an image area enlarging step of enlarging an image area on the printing medium of the color of the developer in the last transfer by a predetermined length. Print data transmission for transmitting print data to the image forming apparatus for transferring and fixing the developer of a plurality of colors onto a print medium for printing by one transfer number or a plurality of transfer times based on the print data; process and
a printing medium color setting step of accepting settings of printing medium color information that specifies the color of the printing medium;
a special color developer usage range setting step of receiving setting of special color developer usage range information that specifies a range on the printing medium in which the special color developer is used;
In order to cause the image forming apparatus to determine the number of transfers and the color of the developer based on the printing medium color information and the special color developer usage range information, the printing medium color information and the special color developer usage range information are used. A print control method comprising: a print data generation step of generating added print data. The printing medium color setting step includes:
13. The print control method according to claim 12, wherein the print medium color information is divided into dark colors and light colors and settings are accepted. The special color developer usage range setting step includes determining whether the special color developer is used for the entire printing medium, the special color developer is used for a portion where an image is formed, or the special color developer is not used. 13. The print control method according to claim 12, wherein any one of the settings is accepted. an image forming apparatus that transfers and fixes a plurality of color developers onto a printing medium and prints based on print data; An image forming system comprising a print control device that transmits
The image forming apparatus includes:
print data receiving means for receiving the print data including print medium color information specifying the color of the print medium and special color developer use range information specifying a range on the print medium in which the special color developer is used; ,
transfer number transfer color determining means for determining the number of transfers and the color of the developer to be used based on the print medium color information and the special color developer use range information of the print data received by the print data receiving means; Prepare,
The print control device includes:
printing medium color setting means for setting the printing medium color information;
and a special color developer usage range setting means for setting the special color developer usage range information,
In order to cause the image forming apparatus to determine the number of transfers and the color of the developer based on the printing medium color information and the special color developer usage range information, the printing medium color information and the special color developer usage range information are used. By generating the added print data,
An image forming system characterized in that the image forming apparatus performs printing based on the print data.

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