Image forming apparatus and program

Abstract

To suitably fix coloring materials in yellow, magenta, cyan, black, and special color without reducing productivity and deteriorating color reproducibility.SOLUTION: An image forming apparatus 100 comprises: image forming units 1Y, 1M, 1C, 1K, 1W that form images on a sheet based on image data to be input by using at least coloring materials in yellow, magenta, cyan, black, and special color; a fixing unit 9 that fixes the images formed by the image forming units 1Y, 1M, 1C, 1K, 1W; a first acquisition unit (control unit 11) that acquires sheet information being information on the sheet; a density receiving unit (control unit 11) that receives selecting at least a first density and a second density being a density larger than the first density for the density of the special color; and a control unit (control unit 11) that controls the second density to be unselectable according to the sheet information.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and a program.

Background Art

[0002] In recent years, as image forming apparatuses, apparatuses that add a special toner (for example, white) to yellow, magenta, cyan, and black toners have been increasing. In such an image forming apparatus, when using a special toner on output paper such as thick paper with a large heat capacity, if fixing is performed under the same fixing conditions as ordinary paper, the toner may not melt sufficiently, resulting in fixing failure. Therefore, in such a case, although fixing performance can be maintained by reducing the fixing speed, there is a problem that productivity decreases. Regarding the density of the special white toner, in the case of an apparatus that can set a standard density and a density higher than the standard, setting a density higher than the standard makes it easier to cause more fixing failure.

[0003] In relation to this, for example, Patent Document 1 describes a technique in which, prior to performing image formation of a target image, a test pattern is output, and based on the output result, an output density that can ensure toner fixability is detected, and printing is not performed at an output density equal to or higher than this output density. Also, Patent Document 2 describes a technique for changing the maximum density setting of an image based on the elapsed time since the main power of the image forming apparatus was turned on, the basis weight, and the thickness, or based on the number of sheets continuously printed, the basis weight, and the thickness. Further, Patent Document 3 describes a technique for detecting the basis weight, smoothness, and whiteness of the back paper, and performing image correction, changing toner image formation conditions, and transfer / fixing conditions according to the detection results.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, Patent Documents 1 to 3 do not mention the characteristics such as white toner, and do not solve the problems when using the characteristics. Also, although it is described that the toner adhesion amounts of yellow, magenta, cyan, and black, which are color toners, are changed, there is a problem that the color reproducibility deteriorates when the adhesion amount of the color toner is reduced.

[0006] An object of the present invention is to provide an image forming apparatus and a program that can suitably fix color materials of yellow, magenta, cyan, black, and characteristics without reducing productivity and without deteriorating color reproducibility. [Means for Solving the Problems]

[0007] To solve the above problems, the image forming apparatus according to the invention described in claim 1 is an image forming unit that forms an image on a sheet with at least color materials of yellow, magenta, cyan, black, and characteristics based on input image data; a fixing unit that fixes the image formed by the image forming unit; a first acquisition unit that acquires sheet information, which is information about the sheet; a density reception unit that accepts selection of at least a first density and a second density that is denser than the first density for the density of the characteristics; a control unit that controls the second density to be unselectable according to the sheet information; and includes.

[0008] The invention described in claim 2 is the image forming apparatus according to claim 1, wherein The first acquisition unit acquires the sheet information specified by the user.

[0009] The invention according to claim 3 is the image forming apparatus according to claim 1, comprising a detection unit that detects physical property values of the sheet, wherein the first acquisition unit acquires the physical property values of the sheet detected by the detection unit as the sheet information.

[0010] The invention according to claim 4 is the image forming apparatus according to any one of claims 1 to 3, wherein the image formed by at least the yellow, magenta, cyan, black, and special color materials is an image formed by toner of each color.

[0011] The invention according to claim 5 is the image forming apparatus according to any one of claims 1 to 4, wherein the special color is white.

[0012] The invention according to claim 6 is the image forming apparatus according to any one of claims 1 to 5, wherein the sheet information includes the basis weight of the sheet.

[0013] The invention according to claim 7 is the image forming apparatus according to any one of claims 1 to 6, wherein the sheet information includes the paper type.

[0014] The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 7, comprising a second acquisition unit that acquires selection information of two modes, a first mode and a second mode, wherein when the first mode is selected, the control unit controls the second density to be unselectable based on the sheet information, and when the second mode is selected, the control unit reduces the system linear velocity based on the sheet information compared to when the first mode is selected.

[0015] The program of the invention according to claim 9 is an image forming unit that forms an image on a sheet with at least yellow, magenta, cyan, black, and special colorants based on input image data; a fixing unit that fixes the image formed by the image forming unit; and causes a computer of an image forming apparatus including a first acquisition unit that acquires sheet information which is information about the sheet, a density reception unit that receives a selection of at least a first density and a second density that is denser than the first density for the density of the special color, and a control unit that controls the second density to be unselectable according to the sheet information to function as.

Advantages of the Invention

[0016] According to the present invention, it is possible to suitably fix yellow, magenta, cyan, black, and special colorants without reducing productivity and without deteriorating color reproducibility.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8A

Figure 8B

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[0019] [Configuration of Image Forming Apparatus] First, with reference to FIGS. 1 to 3, the apparatus configuration of the present embodiment will be described. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 100 according to the present embodiment.

[0020] As shown in FIG. 1, the image forming apparatus 100 is a color image forming apparatus that forms a full-color image by an electrophotographic method. The image forming apparatus 100 includes a printer unit 10, a paper conveyance unit 20, an original reading unit 30, a control unit 11, etc., and these are housed in one housing.

[0021] The printer unit 10 forms an image on a sheet P (sheet) as a recording member based on image data. The printer unit 10 includes four sets of normal color (process color) image forming units 1Y, 1M, 1C, 1K, one set of special color image forming unit 1W, an intermediate transfer belt 7, a secondary transfer roller 8, a fixing unit 9, etc.

[0022] The image forming unit 1Y forms a yellow (Y) image. The image forming unit 1M forms a magenta (M) image. The image forming unit 1C forms a cyan (C) image. The image forming unit 1K forms a black (K) image. The image forming units 1Y, 1M, 1C, and 1K form a color image with process color toners of a plurality of colors (yellow, magenta, cyan, black). The image forming unit 1W forms a white (W) image. The image forming unit 1W forms a special image with a special toner of a color different from each of the colors of yellow, magenta, cyan, and black. Here, white is used as the special color, but other colors such as gold may be used, or a transparent (clear) toner for increasing glossiness may also be used.

[0023] The image forming unit 1Y includes a photosensitive drum 2Y, a charging unit 3Y, an exposure unit 4Y, a developing unit 5Y, and a primary transfer roller 6Y. The charging unit 3Y uniformly charges the surface of the photosensitive drum 2Y. The exposure unit 4Y performs scanning exposure on the photosensitive drum 2Y to form an electrostatic latent image. The developing unit 5Y supplies and develops yellow toner to the electrostatic latent image on the photosensitive drum 2Y. The primary transfer roller 6Y transfers (primary transfer) the yellow toner image formed on the photosensitive drum 2Y onto the intermediate transfer belt 7.

[0024] Similarly, the image forming units 1M, 1C, 1K, and 1W include photosensitive drums 2M, 2C, 2K, and 2W, charging units 3M, 3C, 3K, and 3W, exposure units 4M, 4C, 4K, and 4W, developing units 5M, 5C, 5K, and 5W, and primary transfer rollers 6M, 6C, 6K, and 6W. Regarding the configurations of the image forming units 1M, 1C, 1K, and 1W, they are the same as the image forming unit 1Y, except that the colors of the toners to be handled are different.

[0025] On the intermediate transfer belt 7, at least one toner image of yellow, magenta, cyan, black, and white is formed by the image forming units 1Y, 1M, 1C, 1K, and 1W. One image of each of yellow, magenta, cyan, black, and white may be placed on the intermediate transfer belt 7, or it is also possible to stack all five colors.

[0026] The secondary transfer roller 8 transfers the toner image composed of each color formed on the intermediate transfer belt 7 to the sheet P conveyed at a predetermined timing by the sheet conveyance unit 20. That is, the secondary transfer roller 8 is a transfer unit that transfers the color image formed by the image forming units 1Y, 1M, 1C, 1K and the special color image formed by the image forming unit 1W to the sheet P. The secondary transfer roller 8 forms a nip portion (transfer nip portion) by being disposed in pressure contact with the intermediate transfer belt 7.

[0027] The fixing unit 9 fixes the toner image transferred to the sheet P by heating and pressurizing. That is, the fixing unit 9 fixes the color image and the special color image transferred by the secondary transfer roller 8 to the sheet P. The configuration of the fixing unit 9 is shown in FIG. 2. The fixing unit 9 includes an upper pressure roller 91, a lower pressure roller 92, a fixing belt 93, a heating roller 94, and a belt tension 95. The upper pressure roller 91 is a roller having an outer diameter of 90 mm in which a solid core bar formed of a metal such as iron is coated with an elastic layer having a thickness of 20 mm, and the Asker C hardness is 35°. As the material of the elastic layer, for example, heat-resistant silicone rubber can be used. The upper pressure roller 91 forms a nip portion N between the fixing belt 93 and the lower pressure roller 92. The fixing load in the nip portion N is, for example, 2500 N. The lower pressure roller 92 is a roller having an outer diameter of 80 mm in which the outer peripheral surface of a hollow core bar formed of a metal such as iron is coated with an elastic layer having a thickness of 10 mm, and the Asker C hardness is 30°. As the material of the elastic layer, for example, heat-resistant silicone rubber can be used. Further, as the elastic layer, a configuration in which heat-resistant silicone rubber is coated with a resin layer of a PFA (perfluoroalkoxy) tube as a surface release layer is used. The fixing belt 93 is formed by coating the outer peripheral surface of a substrate made of PI (polyimide) with a thickness of, for example, 70 μm as an elastic layer with a heat-resistant silicon rubber with a thickness of 400 μm, and further coating or coating the surface layer with a PFA tube made of a heat-resistant resin. The fixing belt 93 is stretched between the heating roller 94 and the upper pressure roller 91. The heating roller 94 is a roller with an outer diameter of 80 mm, the outer peripheral surface of an aluminum core with a thickness of 2.5 mm containing a heating means such as a halogen heater (not shown) for heating the fixing belt 93, for example, is coated with a resin layer made of a 15-μm-thick PFA coat or the like. The belt tension 95 can adjust the tension of the fixing belt 93 by making the heating roller 94 movable. The tension of the belt tension 95 on the heating roller 94 is, for example, 100 N.

[0028] Returning to FIG. 1, the paper conveyance unit 20 conveys the paper P along the conveyance path of the paper P. The paper conveyance unit 20 includes an image formation path R1 for conveying the paper P to the printer unit 10, a switching gate G, a paper discharge path R2 for discharging the paper P after image formation to the outside, and a reversal path R3 for performing image formation on both sides of the paper P.

[0029] A plurality of roller pairs for conveying the paper P are provided in each conveyance path. The individual roller pairs have the rollers pressed against each other, and at least one roller is rotationally driven by a drive mechanism such as an electric motor to convey the paper P.

[0030] The image formation path R1 is a path for conveying the paper P from the paper feed tray 21 to the switching gate G. The paper P stored in the paper feed tray 21 is taken in by the paper feed unit 22 and sent out to the image formation path R1.

[0031] On the image formation path R1, the printer unit 10 (particularly, the transfer nip portion formed by the intermediate transfer belt 7 and the secondary transfer roller 8, and the fixing portion 9) is provided. The sheet P is sequentially conveyed and advances along the image forming path R1. The timing at which the sheet P is conveyed toward the transfer nip portion is adjusted at the position where the leading end of the sheet P abuts against the registration roller 23. When the registration roller 23 starts rotating at a predetermined timing so as to be synchronized with the toner image carried by the intermediate transfer belt 7, the sheet P is conveyed to the transfer nip portion of the printer unit 10, and further conveyed to the fixing unit 9. The sheet P on which the fixing process has been performed in the fixing unit 9 is conveyed to the switching gate G.

[0032] The switching gate G is provided on the downstream side of the fixing unit 9 in the sheet conveying direction and switches the conveyance destination of the sheet P conveyed along the image forming path R1. Specifically, when the switching gate G conveys the sheet P that has passed through the fixing unit 9 to the paper discharge path R2, the sheet P is made to go straight. Also, when the switching gate G conveys the sheet P that has passed through the fixing unit 9 to the reverse path R3, the sheet P is guided downward.

[0033] The paper discharge path R2 is a conveyance path for discharging the sheet P on which the fixing process has been performed by the fixing unit 9 to the paper discharge tray 24 attached to the outer side surface of the housing.

[0034] The reverse path R3 is a conveyance path for reversing the front and back of the sheet P on which the fixing process has been performed by the fixing unit 9 and returning it to the image forming path R1. The reverse path R3 branches from a position downstream (the position of the switching gate G) in the sheet conveying direction from the printer unit 10 of the image forming path R1, branches from a position upstream of the reversing roller 25 in the sheet conveying direction, and is provided so as to reach a merging point 26 provided in the middle of the image forming path R1. When forming an image on the back surface of the sheet P as well, the sheet P conveyed to the reverse path R3 is reverse-fed by the reversal of the reversing roller 25 at the timing when the reversing roller 25 sandwiches the trailing end of the sheet P, and then is conveyed to the reverse path R3 leading to the merging point 26 from its trailing end and reaches the merging point 26 of the image forming path R1. The sheet P that has reached the merging point 26 will be sent out to the image forming path R1 again.

[0035] The original document reading unit 30 scans and exposes the image of the original document, reads the reflected light with a line image sensor, and obtains an image signal. The original document reading unit 30 performs processes such as A / D conversion, shading correction, and compression on this image signal, and then outputs it to the control unit 11 as image data.

[0036] In the image forming apparatus 100, when forming a color image on a sheet P such as a color paper, in order to improve the color development of the color image, a white image layer is formed under the color image layer (between the sheet P). In the image forming apparatus 100, in the rotation direction of the intermediate transfer belt 7, since a special color image forming unit (image forming unit 1W) is provided downstream of the color image forming units (image forming units 1Y, 1M, 1C, 1K), images of each color are sequentially superimposed on the intermediate transfer belt 7 from the image forming units 1Y, 1M, 1C, 1K, 1W, and then the images are transferred to the sheet P from the intermediate transfer belt 7 all at once, and then fixed.

[0037] FIG. 3 is a block diagram schematically showing the configuration of the control system of the image forming apparatus 100. As shown in FIG. 3, the image forming apparatus 100 includes a control unit 11, a storage unit 12, a communication unit 13, an operation unit 14, a display unit 15, a printer unit 10, a sheet conveyance unit 20, an original document reading unit 30, a detection unit 40, and the like.

[0038] The control unit 11 is composed of a CPU (Central Processing Unit), a RAM (Random Access Memory), etc. The CPU of the control unit 11 reads out the system program and various processing programs stored in the storage unit 12 and expands them in the RAM, and centrally controls the operations of each part of the image forming apparatus 100 according to the expanded programs. For example, the control unit 11 performs control to form an image on the sheet P based on the image data received by the communication unit 13 or the image data obtained by the original document reading unit 30. Other functions of the control unit 11 will be described later.

[0039] The storage unit 12 is composed of a non-volatile semiconductor memory, an HDD (Hard Disk Drive), etc., and stores various programs executed by the control unit 11, as well as parameters, data, etc. required by each unit.

[0040] The communication unit 13 is equipped with various interfaces such as a NIC (Network Interface Card), a MODEM (Modulator-DEModulator), and a USB (Universal Serial Bus), connects to an external device such as a personal computer, and performs data transmission and reception with the external device. For example, the communication unit 13 receives job information describing the instruction content for forming an image from an external device. The job information includes various setting information in addition to the image data of the image formation target.

[0041] The operation unit 14 is equipped with a touch panel formed to cover the display screen of the display unit 15 and various operation buttons such as numeric buttons and a start button, and outputs an operation signal based on the user's operation to the control unit 11. Further, the operation unit 14 may be equipped with a dedicated button provided for the user to input the density selection of the white toner.

[0042] The display unit 15 is composed of an LCD (Liquid Crystal Display) and displays various screens according to the instruction of the display signal input from the control unit 11.

[0043] The detection unit 40 consists of a laser light receiving member and a laser irradiation member, and measures the laser light irradiated in the direction perpendicular to the paper from the front side of the paper at a position upstream of the printer unit 10 on the image formation path R1 in the paper conveyance direction with a light receiving unit installed on the back side of the paper. Since the light reception amount decreases as the basis weight of the paper increases, the basis weight, which is a physical property value of the sheet, can be measured. The detection unit 40 outputs the measurement result to the control unit 11.

[0044] Next, the functions of the control unit 11 will be described. The control unit 11 acquires sheet information, which is information regarding the sheet (paper P), from the detection unit 40, from the job information, or from the input of an operation signal from the operation unit 14 based on a user operation. Here, the control unit 11 functions as a first acquisition unit. Further, the control unit 11 accepts, based on the input of an operation signal from the operation unit 14 based on a user operation, the selection of at least a first density and a second density that is denser than the first density for the density of the special feature. Here, the control unit 11 functions as a density acceptance unit. Also, the control unit 11 controls the non-selectability of the second density according to the sheet information. Here, the control unit 11 functions as a control unit. Furthermore, the control unit 11 acquires selection information for two modes, namely a speed priority mode (first mode) and an image quality priority mode (second mode), based on the input of an operation signal from the operation unit 14 based on a user operation. Here, the control unit 11 functions as a second acquisition unit.

[0045] Here, FIG. 4 shows examples of the fixability when forming an image with toner of yellow, magenta, cyan, black, and white on four paper types: plain paper, high-quality paper, coated paper gloss, and coated paper matte. The density of the white toner was set at two levels, "standard" (first density) and "standard+" (second density), which is denser than "standard", for image formation. In the table of FIG. 4, "○" indicates a case where the density of the white toner can be fixed at both "standard" and "standard+". Also, "×" indicates a case where the density of the white toner can be fixed at "standard", but the fixability is insufficient at "standard+". That is, in plain paper and high-quality paper, when the basis weight of the paper P is 52 - 400 g / m 2 , the density of the white toner can be fixed at both "standard" and "standard+". Also, in coated paper gloss, when the basis weight of the paper P is 52 - 176 g / m 2 , the density of the white toner can be fixed at both "standard" and "standard+", and when the basis weight is 177 - 400 g / m 2 , the density of the white toner can be fixed at "standard", but the fixability is insufficient at "standard+". Also, in coated paper matte, when the basis weight of the paper P is 52 - 80 g / m2 In this case, the white toner density can be fixed at either "Standard" or "Standard+", and the basis weight is 81 to 400 g / m 2 In this case, the white toner is fixed at the "standard" density, but the fixability is insufficient at the "standard+" density.

[0046] As shown in FIG. 4, when poor fixing occurs, the control unit 11 controls the white toner density so that "standard+" cannot be selected. This feature of making "Standard+" unselectable is particularly effective for white toner. White toner is often used to cover the surface of the base paper, so it adheres in large quantities. The adhesion amounts of yellow, magenta, cyan, and black toner are each 4 g / m 2 The white toner deposition is about 8 g / m 2 Generally, it is common to set the standard to about "Standard+". The total amount of attached toner of the five colors (yellow, magenta, cyan, black, and special color) is particularly large when the special color is white toner, and there is little margin for fixing, so it is effective to make "Standard+" unselectable for white toner.

[0047] [Operation of Image Forming Apparatus 100] Next, the operation of the image forming process of this embodiment will be described. 5 shows a flowchart of the image forming process executed in the image forming apparatus 100. The image forming process is executed by the control unit 11 in cooperation with a program stored in the storage unit 12. The control unit 11 starts image forming processing when it receives a job via the communication unit 13 or a job input by a user via the operation unit 14 .

[0048] First, the control unit 11 refers to the job information of the received job and determines whether or not toner of white color is to be used (step S1). When using white toner (step S1; YES), the control unit 11 controls the detection unit 40 to obtain the basis weight of the sheet P, which is sheet information, and determines whether the basis weight is equal to or greater than a preset threshold value (for example, in the table of FIG. 4, in the case of coated paper matte "standard +", the fixing property is insufficient at 81 g / m 2 2 or more) (step S2). When the basis weight of the sheet P is equal to or greater than the threshold value (step S2; YES), the control unit 11 makes "standard +" non-selectable in the density setting of the white toner (step S3). The density of the white toner can be set by a button dedicated to the "standard +" setting of the operation unit 14 or by a density increase mechanism by density adjustment. Making "standard +" non-selectable means that a message indicating non-selectability is displayed on the display unit 15, and the above density setting function may be controlled to be unusable. At this time, the density of the white toner is set to "standard". Next, the control unit 11 forms an image with yellow, magenta, cyan, black, and white toners based on the image data included in the received job information (step S4), and ends the image forming process. The density of the white toner at this time is "standard" set in step S3.

[0049] Also, when not using white toner (step S1; NO), the control unit 11 forms an image with yellow, magenta, cyan, and black toners based on the image data included in the received job information (step S4), and ends the image forming process. Also, when the basis weight of the sheet P is less than the threshold value (step S2; NO), the control unit 11 accepts a selection between "standard" and "standard +" in the density setting of the white toner (step S5). When accepting the density setting input by the user via the above density setting function, the control unit 11 forms an image with yellow, magenta, cyan, black, and white toners (step S4), and ends the image forming process. The density of the white toner at this time is the density set in step S5.

[0050] Fig. 6 shows a table of examples of the density selection of white toner when forming an image with yellow, magenta, cyan, black, and white toners on four types of paper: plain paper, coated paper gloss, and coated paper matte in the above image forming process. As shown in Fig. 6, regardless of the paper type, when the basis weight of the paper P is in the range less than the threshold value (for example, 81 g / m 2 ), the density selection of white toner is possible. When the basis weight of the paper P is in the range equal to or greater than the threshold value (for example, 81 g / m 2 ), "Standard +" is set to be unselectable.

[0051] (Modification Example 1) Fig. 7 is a flowchart of the image forming process of this Modification Example 1. Hereinafter, the description will focus on the differences from the above embodiment. The configuration of the image forming apparatus 100 of this Modification Example 1 is the same as that of the image forming apparatus 100 of the above embodiment.

[0052] First, after the control unit 11 performs step S11 similar to step S1 of the image forming process of the above embodiment, it refers to the job information of the received job, acquires the paper type information which is the sheet information of the paper P, and determines whether the paper type is coated paper gloss or coated paper matte (step S12). When the paper type of the paper P is coated paper gloss or coated paper matte (step S12; YES), the control unit 11 controls the detection unit 40 to acquire the basis weight of the paper P, and determines whether the basis weight is equal to or greater than a preset threshold value (for example, in the table of Fig. 4, the threshold value at which the fixability becomes insufficient in "Standard +", 177 g / m for coated paper gloss 2 , 81 g / m for coated paper matte 2 ) (step S13). When the basis weight of the paper P is equal to or greater than the threshold value (step S13; YES), the control unit 11 performs steps S14 and S15 similar to steps S3 and S4 of the image forming process of the above embodiment, and ends the image forming process.

[0053] Also, when white toner is not used (step S11; NO), the control unit 11 forms an image with yellow, magenta, cyan, and black toners based on the image data included in the received job information (step S15), and ends the image forming process. Also, when the paper type of the paper P is not coated paper gloss or coated paper matte (step S12; NO), and when the basis weight of the paper P is less than the threshold value (step S13; NO), the control unit 11 accepts a selection of "standard" or "standard +" in the density setting of the white toner (step S16). When the density setting input by the user is accepted via the above density setting function, the control unit 11 forms an image with yellow, magenta, cyan, black, and white toners (step S15), and ends the image forming process. The density of the white toner at this time is the density set in step S16.

[0054] FIG. 8A shows a table of an example of density selection of the white toner when forming an image with yellow, magenta, cyan, black, and white toners on four types of paper, namely plain paper, high-quality paper, coated paper gloss, and coated paper matte, in the image forming process of the first modified example. As shown in FIG. 8A, when the paper type of the paper P is coated paper gloss or coated paper matte and the basis weight is in the range of the threshold value (for example, 177 g / m for coated paper gloss 2 , 81 g / m for coated paper matte 2 ) or more, "standard +" is set to be unselectable. In other ranges, the density selection of the white toner is set to be possible. Also, in the basis weight of the paper P, coated paper gloss and coated paper matte may be grouped together as coated paper, and one threshold value (for example, 81 g / m 2 ) may be provided. In the image forming process of the first modified example in this case, a table of an example of density selection of the white toner when forming an image with yellow, magenta, cyan, black, and white toners on four types of paper, namely plain paper, high-quality paper, coated paper gloss, and coated paper matte, is shown in FIG. 8B. As shown in FIG. 8B, when the paper type of the paper P is coated paper gloss or coated paper matte and the basis weight is in the range of the threshold value (for example, 81 g / m 2Within the above range, "Standard+" is set to be unselectable. In other ranges, the density selection of white toner is set to be possible.

[0055] (Modification Example 2) FIG. 9 is a flowchart of the image forming process of this Modification Example 2. Hereinafter, the description will focus on the differences from the above Modification Example 1. The configuration of the image forming apparatus 100 of this Modification Example 2 is the same as that of the image forming apparatus 100 of the above embodiment. In this Modification 2, the fixing process line speed (system line speed) in the fixing unit 9 can be selected from two modes: a speed priority mode which is the first mode and an image quality priority mode which is the second mode. In the speed priority mode, the fixing process line speed during normal image formation is maintained, and when fixing failure occurs, "Standard+" is controlled to be unselectable in the density setting of white toner. On the other hand, in the image quality priority mode, when fixing failure occurs, the fixing process line speed is made slower than that in the speed priority mode (for example, 15% slower). The selection of these two modes may be input by the user in advance from the operation unit 14, or may be set as job information received via the communication unit 13.

[0056] First, after the control unit 11 performs steps S21 to S23 similar to steps S11 to S13 of the image forming process of the above Modification Example 1, when the basis weight of the sheet P is equal to or greater than the threshold value (step S23; YES), the control unit 11 acquires selection information of two modes, namely the speed priority mode and the image quality priority mode, and determines whether it is set to the speed priority mode (step S24). When it is set to the speed priority mode (step S24; YES), the control unit 11 performs steps S25 and S26 similar to steps S14 and S15 of the image forming process of the above Modification Example 1, and ends the image forming process.

[0057] Also, when white toner is not used (step S21; NO), the control unit 11 forms an image with yellow, magenta, cyan, and black toners based on the image data included in the received job information (step S26), and ends the image forming process. Also, when the paper type of the paper P is not coated paper gloss or coated paper matte (step S22; NO), and when the basis weight of the paper P is less than the threshold value (step S23; NO), the control unit 11 accepts a selection of "standard" or "standard +" in the density setting of the white toner (step S27). When the control unit 11 accepts the density setting input by the user via the above density setting function, it forms an image with yellow, magenta, cyan, black, and white toners (step S26), and ends the image forming process. The density of the white toner at this time is the density set in step S27.

[0058] Also, when not set to the speed priority mode (step S24; NO), that is, when set to the image quality priority mode, the control unit 11 accepts a selection of "standard" or "standard +" in the density setting of the white toner (step S28). Next, the control unit 11 determines whether "standard +" is selected in step S28 (step S29). When "standard +" is selected (step S29; YES), the control unit 11 makes the fixing process line speed slower than that during normal image formation (step S30), and proceeds to step S26. Also, when "standard +" is not selected (step S29; NO), that is, when set to "standard", the control unit 11 proceeds to step S26.

[0059] Fig. 10 shows a table of examples of density selection of the white toner when forming an image with yellow, magenta, cyan, black, and white toners on four paper types of plain paper, fine paper, coated paper gloss, and coated paper matte in the image forming process of this second modified example. As shown in Fig. 10, when the paper type of the paper P is coated paper gloss or coated paper matte, and the basis weight is the threshold value (for example, 177 g / m for coated paper gloss 2 , 81 g / m for coated paper matte 2)Within the above range, "Standard+" is set to be unselectable (in speed priority mode), or the fixing process line speed is set to be slower (in image quality priority mode). In other ranges, the selection of the density of the white toner is set to be possible.

[0060] As described above, the image forming apparatus 100 includes an image forming unit 1Y, 1M, 1C, 1K, 1W that forms an image on a sheet with at least yellow, magenta, cyan, black, and special color materials based on input image data, a fixing unit 9 that fixes the image formed by the image forming unit 1Y, 1M, 1C, 1K, 1W, a first acquisition unit (control unit 11) that acquires sheet information which is information about the sheet, a density reception unit (control unit 11) that accepts the selection of at least a first density and a second density that is denser than the first density for the special color density, and a control unit (control unit 11) that controls the second density to be unselectable according to the sheet information. Thereby, in a situation where productivity, color reproducibility, and fixability cannot be satisfied when the second density is selected, by making the second density unselectable, it is possible to suitably fix the yellow, magenta, cyan, black, and special color materials without reducing productivity and without deteriorating color reproducibility.

[0061] Also, in the image forming apparatus 100, since the first acquisition unit (control unit 11) acquires the sheet information specified by the user, it is possible to suitably fix the yellow, magenta, cyan, black, and special color materials according to the sheet information instructed by the user without reducing productivity and without deteriorating color reproducibility.

[0062] Also, the image forming apparatus 100 includes a detection unit 40 that detects the physical property value of the sheet, and since the first acquisition unit (control unit 11) acquires the physical property value of the sheet detected by the detection unit 40 as the sheet information, the sheet information can be automatically acquired.

[0063] In the image forming apparatus 100, since the images formed by at least yellow, magenta, cyan, black, and special color materials are images formed by toners of respective colors, it is possible to suitably fix the yellow, magenta, cyan, black, and special toners without reducing productivity and without deteriorating color reproducibility.

[0064] In the image forming apparatus 100, since the special color is white, it is possible to ensure fixability even when using a white color material that is likely to cause poor fixing.

[0065] In the image forming apparatus 100, since the sheet information includes the basis weight of the sheet, it is possible to suitably fix the yellow, magenta, cyan, black, and special color materials according to the basis weight of the sheet without reducing productivity and without deteriorating color reproducibility.

[0066] In the image forming apparatus 100, since the sheet information includes the paper type, it is possible to suitably fix the yellow, magenta, cyan, black, and special color materials according to the paper type without reducing productivity and without deteriorating color reproducibility.

[0067] In the image forming apparatus 100, a second acquisition unit (control unit 11) that acquires selection information for two modes, i.e., a first mode (speed priority mode) and a second mode (image quality priority mode), is provided. When the first mode is selected, the control unit controls the second density to be unselectable based on the sheet information. When the second mode is selected, the control unit reduces the system linear speed based on the sheet information as compared with the case where the first mode is selected. Therefore, it is possible to suitably fix the yellow, magenta, cyan, black, and special color materials without causing poor fixing.

[0068] Note that the description in the above embodiment shows a preferred example of the image forming apparatus according to the present invention, and is not limited thereto.

[0069] In addition, in the above-described embodiments and modified examples, although the concentration of the white toner can be set to two levels of "standard" and "standard +", it is not limited thereto. Settings of three levels or more may be provided.

[0070] In addition, in the above-described embodiments and modified examples, although an image is formed using yellow, magenta, cyan, black, and white toners as color materials, it is not limited thereto. For example, yellow, magenta, cyan, black, and white inks may be used, and any color material that requires fixing may be used to form an image. In addition, as color materials, yellow, magenta, cyan, black, light cyan, light magenta, and special toners, or yellow, magenta, cyan, black, light cyan, light magenta, and special inks may be used.

[0071] In addition, in the above-described embodiments and modified examples, the sheet information is the basis weight of the paper P and the paper type of the paper P, but it is not limited thereto. The surface roughness of the paper P or the air permeability of the paper P may be used as the sheet information. Information on the surface roughness of the paper P or the air permeability of the paper P may be input by the user from the operation unit 14, or may be set as job information received via the communication unit 13. Further, the detection unit 40 may have a function of detecting the surface roughness of the paper P and the air permeability of the paper P, and the control unit 11 may acquire the detection result as information on the surface roughness of the paper P or the air permeability of the paper P. When the surface roughness of the paper P is used as the sheet information, for example, based on Bekk smoothness 100, for a range greater than 100, the selection of "standard +" (second concentration) may be uncontrollably restricted. When the air permeability of the paper P is used as the sheet information, for example, based on 500, for a range greater than 500, the selection of "standard +" (second concentration) may be uncontrollably restricted.

[0072] Further, in the above-described modification, it has been assumed that the paper type information of the sheet P is obtained from the job information of the job that has received the paper type information of the sheet P, but it is not limited to this. The detection unit 40 may be provided with a function of detecting the paper type of the sheet P, and the control unit 11 may obtain the detection result as the paper type information of the sheet P. Further, the user may input the paper type information of the sheet P from the operation unit 14. That is, the first acquisition unit acquires the paper type information of the sheet P, which is the sheet information specified by the user.

[0073] Also, in the above-described embodiment and modification, it has been assumed that the basis weight of the sheet P is detected by the detection unit 40, but it is not limited to this. The basis weight of the sheet P may be input by the user from the operation unit 14, or may be set as job information received via the communication unit 13. That is, the first acquisition unit acquires the basis weight of the sheet P, which is the sheet information specified by the user.

[0074] In addition, the detailed configuration and detailed operation of the image forming apparatus can be appropriately changed without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0075] 1Y, 1M, 1C, 1K, 1W Image Forming Unit 2Y, 2M, 2C, 2K, 2W Photoconductor Drum 3Y, 3M, 3C, 3K, 3W Charging Unit 4Y, 4M, 4C, 4K, 4W Exposure Unit 5Y, 5M, 5C, 5K, 5W Developing Unit 6Y, 6M, 6C, 6K, 6W Primary Transfer Roller 7 Intermediate Transfer Belt 8 Secondary Transfer Roller 9 Fixing Unit 91 Upper Pressing Roller 92 Lower Pressing Roller 93 Fixing Belt 94 Heating Roller 95 Belt Tension 10 Printer Unit 11 Control Unit (First Acquisition Unit, Density Reception Unit, Control Unit, Second Acquisition Unit) 12 Storage Unit 13 Communication Unit 14 Operation Unit 15 Display Unit 20 Paper Feeding Unit 21 Paper Cassette 22 Paper Feeding Section 23 Registration Roller 24 Output Tray 25 Reversing Roller 26 Confluence Point 30 Original Reading Unit 40 Detection Unit 100 Image Forming Apparatus G Switching Gate N Nip Section P Paper R1 Image Forming Path R2 Output Path R3 Reversing Path

Claims

1. An image forming unit that forms an image on a sheet with at least yellow, magenta, cyan, black, and special color materials based on input image data; A fixing unit that fixes the image formed by the image forming unit; A first acquisition unit that acquires sheet information which is information about the sheet; A density reception unit that accepts selection of at least a first density and a second density that is denser than the first density for the density of the special color; A control unit that controls to make the second density non-selectable according to the sheet information; An image forming apparatus comprising the above.

2. The image forming apparatus according to claim 1, wherein the first acquisition unit acquires the sheet information specified by a user.

3. Comprising a detection unit that detects physical property values of the sheet, The image forming apparatus according to claim 1, wherein the first acquisition unit acquires the physical property values of the sheet detected by the detection unit as the sheet information.

4. The image forming apparatus according to any one of claims 1 to 3, wherein the image formed by at least yellow, magenta, cyan, black, and special color materials is an image formed by toner of each color.

5. The image forming apparatus according to any one of claims 1 to 4, wherein the special color is white.

6. The image forming apparatus according to any one of claims 1 to 5, wherein the sheet information includes the basis weight of the sheet.

7. The image forming apparatus according to any one of claims 1 to 6, wherein the sheet information includes the paper type.

8. Comprising a second acquisition unit that acquires selection information of two modes, a first mode and a second mode, The control unit controls to make the second density non-selectable based on the sheet information when the first mode is selected, and lowers the system line speed based on the sheet information when the second mode is selected compared to when the first mode is selected. The image forming apparatus according to any one of claims 1 to 7.

9. An image forming unit that forms an image on a sheet with at least yellow, magenta, cyan, black, and special color materials based on input image data; A fixing unit that fixes the image formed by the image forming unit; The computer of the image forming apparatus comprising the above, A first acquisition unit that acquires sheet information which is information about the sheet, A density receiving unit that receives a selection of at least a first density and a second density that is denser than the first density with respect to the density of the feature, A control unit that controls the second density to be unselectable according to the sheet information, A program that functions as

Images