Image formation apparatus and image formation method

Abstract

To realize satisfactory visual effects.SOLUTION: An image formation apparatus 1 prints a color toner image PL on a front surface of a medium M, and also prints a photoluminescent toner image PS on a rear surface to print a decorative medium MC. At this point in the image formation apparatus 1, a duty difference of a background print duty DB and a decorative print duty DC is 18.75[%] to 37.50[%], and further, a range of a ratio of the decorative print duty DC to the background print duty DB is 62.50[%] to 81.25[%], in the photoluminescent toner image PS. Accordingly, the image formation apparatus 1 is capable of imparting satisfactory visual effects such that a decorative area AC appears and disappears on a front surface side of the decorative medium MC, when a relationship of relative positions and angles of a user's viewpoint VP, a light source LS, and the decorative medium MC changes in various ways.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus and an image forming method, which are suitable for use in forming, on a medium, an image having a special visual effect using, for example, glittering colors. [Background technology]

[0002] Conventionally, when performing color printing, image forming apparatuses that combine toners (hereinafter referred to as normal color toners) such as black, magenta, cyan, and yellow (hereinafter referred to as normal colors) to form (i.e., print) color images in normal colors on a medium such as paper have been widely used. Some image forming apparatuses can form images with a glossy quality on paper by using toners (hereinafter referred to as glossy toners) that have a glossy quality such as silver or gold (hereinafter referred to as glossy colors) in addition to the normal colors.

[0003] Additionally, an image forming device has been proposed that forms (i.e. prints) an image having a visual effect of an image appearing to disappear by overlaying a glossy image made of glossy toner on a normal color image made of normal color toner (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-82517 A (Figs. 2 and 3) Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the image printed by the image forming device described above, there are areas where the glitter toner is placed and areas where it is not placed. Therefore, in a medium where a printing process is performed in which a normal color image is overlaid on the glitter image, a step is formed in each area in the layer of normal color toner that constitutes the normal color image. As a result, there is a difference in glossiness in each area of ​​this medium, and the image may be visible against one's will, resulting in a problem that the visual effect is insufficient.

[0006] The present invention has been made in consideration of the above points, and aims to propose an image forming apparatus and an image forming method that can achieve a good visual effect. [Means for solving the problem]

[0007] In order to solve this problem, the image forming apparatus of the present invention includes a non-glossy image forming unit capable of forming a non-glossy image using a non-glossy developer on a medium that transmits at least a portion of visible light, a glossy image forming unit capable of forming a glossy image using a glossy developer on the medium, and a control unit that controls the non-glossy image forming unit and the glossy image forming unit in accordance with print data, and the control unit causes the non-glossy image forming unit to form a non-glossy image on a first side of the medium, and causes the glossy image forming unit to form a glossy image having a first region and a second region on a second side that is the opposite side to the first side, and defines adhesion rates in the first and second regions, which are expressed as an area ratio of the amount of adhesion of the glossy developer per unit area on the medium, as a first adhesion rate and a second adhesion rate, respectively, and controls the difference between the first adhesion rate and the second adhesion rate to be 18.75% or more and 37.50% or less.

[0008] Furthermore, the image forming method of the present invention includes a non-glossy image forming step in which a non-glossy image is formed by a non-glossy developer on a first surface of a medium that transmits at least a portion of visible light by a non-glossy image forming unit, and a glossy image forming step in which, before or after the non-glossy image forming step, a glossy image having a first region and a second region is formed by a glossy developer on a second surface of the medium that is the opposite surface to the first surface by the glossy image forming unit, and in the glossy image forming step, when the adhesion rates of the amount of adhesion of the glossy developer per unit area on the medium in the first region and the second region are respectively defined as a first adhesion rate and a second adhesion rate, with the ratio of the adhesion rate to a predetermined reference amount, the difference of the second adhesion rate from the first adhesion rate is set to be 18.75% or more and 37.50% or less.

[0009] Furthermore, the image forming apparatus of the present invention includes a first image forming unit capable of forming a first image using a non-photoluminescent developer on a medium that transmits at least a portion of visible light, a second image forming unit capable of forming a second image using a photoluminescent developer on the medium, and a control unit that controls the first image forming unit and the second image forming unit in accordance with print data, and the control unit causes the first image forming unit to form a first image on a first side of the medium, and causes the second image forming unit to form a second image having a first region and a second region on a second side that is the opposite side to the first side, and defines adhesion rates in the first and second regions as a first adhesion rate and a second adhesion rate, respectively, which are expressed as a ratio of the adhesion amount of the photoluminescent developer per unit area on the medium to a predetermined reference amount, and controls the ratio of the second adhesion rate to the first adhesion rate to be 62.50[%] or more and 81.25[%] or less.

[0010] Furthermore, the image forming method of the present invention includes a non-glossy image forming step in which a non-glossy image is formed by a non-glossy developer on a first surface of a medium that transmits at least a portion of visible light by a non-glossy image forming unit, and a glossy image forming step in which, before or after the non-glossy image forming step, a glossy image having a first region and a second region is formed by a glossy developer on a second surface of the medium that is the opposite surface to the first surface by the glossy image forming unit, and in the glossy image forming step, when adhesion rates expressed as a ratio of the adhesion amount of glossy developer per unit area on the medium to a predetermined reference amount in the first region and the second region are defined as a first adhesion rate and a second adhesion rate, respectively, the ratio of the second adhesion rate to the first adhesion rate is set to be 62.50[%] or more and 81.25[%] or less.

[0011] Furthermore, the image forming apparatus of the present invention includes a non-glossy image forming unit capable of forming a non-glossy image and a correction image on a medium using a non-glossy developer, a glossy image forming unit capable of forming a glossy image on the medium using a glossy developer, and a control unit that controls the non-glossy image forming unit and the glossy image forming unit in accordance with print data, and the control unit causes the non-glossy image forming unit to form a correction image in a second area excluding the first area on the surface of the medium, and causes the glossy image forming unit to form a correction image in the first area and the second area on the medium by superimposing the correction image thereon. A glossy image having a glossy area is formed, and then a non-glossy image is formed by a non-glossy image forming section by overlaying the glossy image. In the first and second areas, adhesion rates expressed as a ratio of the amount of adhesion of glossy developer per unit area on the medium to a predetermined reference amount are designated as a first adhesion rate and a second adhesion rate, respectively, and the difference between the first adhesion rate and the second adhesion rate is controlled to be 18.75% or more and 37.50% or less, and the adhesion rate of the corrected image is controlled to be equal to the difference.

[0012] The present invention forms a non-glossy image on a first side of a medium, and controls the difference between a first adhesion rate in a first region and a second adhesion rate in a second region in a glossy image formed on a second side of the medium to be within a predetermined range. Therefore, the present invention allows a user viewing the first side of the medium to visually recognize the non-glossy image, and can provide a visual effect that transitions between a state in which the boundary between the first region and the second region is visually recognized and a state in which only the non-glossy image is visually recognized without the boundary being recognized, depending on the positional relationship with the light source and the angle of the medium, etc. Effect of the Invention

[0013] According to the present invention, it is possible to realize an image forming apparatus and an image forming method that can realize a good visual effect. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus. [Diagram 2] FIG. 2 is a schematic diagram illustrating a configuration of an image forming unit. [Diagram 3] FIG. 2 is a schematic block diagram illustrating a circuit configuration of the image forming apparatus. [Figure 4] 1 is a schematic diagram showing a configuration of a decoration medium according to a first embodiment. [Diagram 5] 11A and 11B are schematic diagrams illustrating how a visual effect appears. [Figure 6] 1 is a schematic diagram illustrating the principle by which a visual effect is produced. [Figure 7] 11 is a table showing the print duty and various measurement values ​​of an evaluation image, and the evaluation results. [Figure 8] FIG. 4 is a schematic diagram showing how reflectance is measured. [Figure 9] 11 is a schematic diagram showing how a luminous reflectance difference is measured; FIG. [Figure 10] 5 is a flowchart showing a procedure of a decorative medium printing process according to the first embodiment. [Figure 11] 13 is a schematic diagram showing a configuration of a decoration medium according to a second embodiment. FIG. [Figure 12]13 is a flowchart showing a procedure of a decorative medium printing process according to a second embodiment. [Figure 13] 13 is a schematic diagram showing a configuration of a decoration medium according to a third embodiment. FIG. [Figure 14] 13 is a flowchart showing a procedure of a decorative medium printing process according to a third embodiment. [Figure 15] 13 is a schematic diagram showing a configuration of a decoration medium according to another embodiment. FIG. [Figure 16] 13 is a schematic diagram showing a configuration of a decoration medium according to another embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[0016] 1. First embodiment [1-1. Configuration of image forming device] 1, the image forming apparatus 1 according to the first embodiment is an electrophotographic color printer that can form (i.e., print) a color image on a medium M such as paper. Incidentally, the image forming apparatus 1 does not have an image scanner function for reading an original document or a communication function using a telephone line, and is a single-function SFP (Single Function Printer) that has only a printer function.

[0017] Various parts are arranged inside a housing 2 formed in a substantially box shape in the image forming apparatus 1. In the following description, the right end portion in Fig. 1 is regarded as the front of the image forming apparatus 1, and the up-down direction, left-right direction, and front-rear direction are defined when viewed from the front.

[0018] The image forming apparatus 1 is controlled by the control unit 3. As described below, the control unit 3 executes various processes by reading and executing a predetermined program. The control unit 3 is also connected to a higher-level device 100 (FIG. 3) such as a computer device by wireless or wired connection, and when image data representing an image to be printed is provided from the higher-level device and printing of the image data is instructed, the control unit 3 executes a print process to form a print image on the surface of the medium M. The display unit 4 is a display device such as a liquid crystal panel, and is disposed on the front side of the upper surface of the housing 2. The display unit 4 displays various information under the control of the control unit 3.

[0019] Five image forming units 10K, 10C, 10M, 10Y, and 10S are arranged in this order from the front to the rear on the upper side inside the housing 2. The image forming units 10K, 10C, 10M, 10Y, and 10S correspond to the colors black (K), cyan (C), magenta (M), yellow (Y), and spot color (S), respectively, but only the colors differ and all are configured similarly.

[0020] Black (K), cyan (C), magenta (M) and yellow (Y) are all colors used in general color printers (hereinafter, these are referred to as normal colors or non-glossy colors). On the other hand, the special color (S) is a special color (hereinafter, these are also referred to as glittering colors) that exhibits metallic luster, i.e., has glittering properties, such as gold and silver. This special color may be used alone or may be used in combination with a normal color. In this embodiment, the case where silver is used as a special color will be described as an example. For convenience of explanation, the image forming units 10K, 10C, 10M, 10Y and 10S will be collectively referred to as the image forming units 10 below. In addition, the image forming units 10K, 10C, 10M and 10Y will be referred to as non-glossy image forming units or first image forming units, and the image forming unit 10S will be referred to as glittering image forming units or second image forming units.

[0021] 2, the image forming unit 10 is roughly composed of an image forming main body 11, a toner container 12, a toner supply unit 13, and an LED (Light Emitting Diode) head 14. The toner container 12 contains toner T (also called a developer) therein, and is configured to be detachable from the image forming unit 10. When the toner container 12 is mounted on the image forming unit 10, it is attached to the image forming main body 11 via the toner supply unit 13. Incidentally, the toner container 12 is sometimes called a toner cartridge.

[0022] As described later, for the silver toner T, a toner containing a glittering pigment is used. For convenience of explanation, hereinafter, the glittering silver toner T is referred to as silver toner TS, glittering toner, or glittering developer. On the other hand, for the yellow, magenta, cyan, and black toners T, a toner containing an organic pigment, such as pigment yellow, pigment cyan, pigment magenta, and carbon black, is used. For convenience of explanation, hereinafter, the yellow, magenta, cyan, and black (i.e., non-glittering) toners T are also referred to as color toner TL, non-glittering toner, or non-glittering developer.

[0023] The image forming main body 11 (FIG. 2) incorporates an image forming housing 20, a toner storage space 21, a first supply roller 22, a second supply roller 23, a developing roller 24, a developing blade 25, a photosensitive drum 26, a charging roller 27, and a cleaning blade 28. Among these, the first supply roller 22, the second supply roller 23, the developing roller 24, the photosensitive drum 26, and the charging roller 27 are each configured in a cylindrical shape with their central axes aligned in the left-right direction, and are each rotatably supported by the image forming housing 20.

[0024] The toner storage space 21 stores the toner T supplied from the toner storage container 12 via the toner supply unit 13. The first supply roller 22 and the second supply roller 23 each have an elastic layer formed of a conductive urethane rubber foam or the like on their circumferential side. The developing roller 24 has an elastic layer having elasticity and a surface layer having conductivity formed on their circumferential side. The developing blade 25 is made of, for example, a stainless steel plate of a predetermined thickness, and a part of it is in contact with the circumferential side of the developing roller 24 in a state where it is slightly elastically deformed.

[0025] The photoconductor drum 26, which serves as an image carrier, has a thin-film charge generating layer and a charge transport layer formed in that order on its peripheral surface so that it can be charged. The charging roller 27 has a conductive elastic body coated on its peripheral surface, which is brought into contact with the peripheral surface of the photoconductor drum 26. The cleaning blade 28 is made of, for example, a thin resin plate, and a part of it is brought into contact with the peripheral surface of the photoconductor drum 26 while being slightly elastically deformed.

[0026] The LED head 14 as an exposure unit is located above the photoconductor drum 26 in the image forming main body 11. This LED head 14 has multiple light-emitting element chips arranged linearly in the left-right direction, and causes each light-emitting element to emit light in a light emission pattern based on image data signals supplied from the control unit 3 (FIG. 1).

[0027] The image forming main body 11 rotates the first supply roller 22, the second supply roller 23, the developing roller 24, and the charging roller 27 in the direction of the arrow R1 (clockwise in the figure) and rotates the photosensitive drum 26 in the direction of the arrow R2 (counterclockwise in the figure) by receiving a driving force from a motor (not shown). Furthermore, under the control of the control unit 3, the image forming main body 11 applies a predetermined bias voltage to the first supply roller 22, the second supply roller 23, the developing roller 24, the developing blade 25, and the charging roller 27, thereby charging them.

[0028] The first supply roller 22 and the second supply roller 23 are charged to cause the toner T in the toner storage space 21 to adhere to their circumferential sides, and then rotate to cause the toner T to adhere to the circumferential side of the developing roller 24. The developing roller 24 has excess toner T removed from the circumferential side by the developing blade 25, and with the toner T adhered in a thin film form, the circumferential side is brought into contact with the circumferential side of the photosensitive drum 26.

[0029] Meanwhile, the charging roller 27, in a charged state, comes into contact with the photoconductor drum 26, thereby uniformly charging the circumferential side surface of the photoconductor drum 26. The LED head 14 sequentially exposes the photoconductor drum 26 by performing an exposure process in which it emits light at predetermined time intervals in a light emission pattern based on an image data signal supplied from the control unit 3 (FIG. 1). As a result, electrostatic latent images are sequentially formed on the circumferential side surface of the photoconductor drum 26 near its upper end.

[0030] Next, the photoconductor drum 26 rotates in the direction of arrow R2, thereby bringing the area where the electrostatic latent image is formed into contact with the developing roller 24. As a result, toner T adheres to the peripheral side surface of the photoconductor drum 26 based on the electrostatic latent image, and a toner image based on the image data is developed. The photoconductor drum 26 further rotates in the direction of arrow R2, thereby causing the toner image to reach the vicinity of the lower end of the photoconductor drum 26. For convenience of explanation, hereinafter, a toner image formed with silver toner TS having glitter properties is also referred to as a glitter toner image PS or a glitter image, and a toner image formed with color toner TL, which is a normal color, is also referred to as a color toner image PL or a non-glitter image.

[0031] An intermediate transfer section 30 is disposed below each image forming unit 10 within the housing 2 (FIG. 1). The intermediate transfer section 30 includes a drive roller 31, a driven roller 32, a backup roller 33, an intermediate transfer belt 34, five primary transfer rollers 35, a secondary transfer roller 36, and a reverse bending roller 37. Of these, the drive roller 31, the driven roller 32, the backup roller 33, the primary transfer rollers 35, the secondary transfer roller 36, and the reverse bending roller 37 are all formed in a cylindrical shape with their central axes aligned in the left-right direction, and are rotatably supported by the housing 2.

[0032] The drive roller 31 is disposed below and rearward of the image forming unit 10S, and rotates in the direction of the arrow R1 when a driving force is supplied from a belt motor (not shown). The driven roller 32 is disposed below and frontward of the image forming unit 10K. The upper ends of the drive roller 31 and the driven roller 32 are positioned at the same level as or slightly below the lower ends of the photoconductor drums 26 (FIG. 2) in the respective image forming units 10. The backup roller 33 is disposed below and frontward of the drive roller 31 and below and rearward of the driven roller 32.

[0033] The intermediate transfer belt 34 is configured as an endless belt made of a high-resistance plastic film, and is stretched so as to go around the driving roller 31, the driven roller 32, and the backup roller 33. Furthermore, in the intermediate transfer section 30, five primary transfer rollers 35 are disposed below the portion of the intermediate transfer belt 34 stretched between the driving roller 31 and the driven roller 32, i.e., directly below each of the five image forming units 10, at positions facing each of the photoconductor drums 26 with the intermediate transfer belt 34 in between. A predetermined bias voltage is applied to the primary transfer rollers 35 under the control of the control section 3.

[0034] The secondary transfer roller 36 is located directly below the backup roller 33 and is biased toward the backup roller 33. That is, the intermediate transfer unit 30 has the intermediate transfer belt 34 sandwiched between the secondary transfer roller 36 and the backup roller 33. A predetermined bias voltage is applied to the secondary transfer roller 36. Hereinafter, the secondary transfer roller 36 and the backup roller 33 will be collectively referred to as the secondary transfer unit 39.

[0035] The reverse bending roller 37 is located at a position lower on the front side of the drive roller 31 and rearward on the upper side of the backup roller 33, and biases the intermediate transfer belt 34 in a front-upward direction. This prevents the intermediate transfer belt 34 from becoming loose, and tension acts between each roller. In addition, a reverse bending backup roller 38 is provided at a position above and in front of the reverse bending roller 37, sandwiching the intermediate transfer belt 34 therebetween.

[0036] The intermediate transfer section 30 rotates the drive roller 31 in the direction of the arrow R1 by the driving force supplied from a belt motor (not shown), thereby moving the intermediate transfer belt 34 in the direction along the arrow E1. In addition, each primary transfer roller 35 rotates in the direction of the arrow R1 with a predetermined bias voltage applied thereto. As a result, each image forming unit 10 transfers the toner image that has reached the vicinity of the lower end of the circumferential side surface of the photosensitive drum 26 (FIG. 2) to the intermediate transfer belt 34, and the toner images of each color are sequentially superimposed. At this time, the toner images of each color are sequentially superimposed on the surface of the intermediate transfer belt 34, starting from silver (S) on the upstream side. The intermediate transfer section 30 moves the intermediate transfer belt 34, thereby causing the toner images transferred from each image forming unit 10 to reach the vicinity of the backup roller 33.

[0037] Incidentally, inside the housing 2 (FIG. 1), a transport path W is formed, which is a path for transporting the medium M. This transport path W heads from the front of the lower end inside the housing 2 toward the upper front direction, turns about half a turn, and then proceeds toward the rear below the intermediate transfer unit 30. The transport path W then heads upward, travels upward along the rear side of the intermediate transfer unit 30 and the image forming unit 10S, and then heads toward the front. That is, the transport path W is formed as if it were drawing the capital letter "S" in FIG. 1. Inside the housing 2, various parts are arranged along the transport path W.

[0038] A first paper supply section 40 is disposed near the bottom end inside the housing 2 (FIG. 1). The first paper supply section 40 includes a paper cassette 41, a pickup roller 42, a feed roller 43, a retard roller 44, a transport guide 45, and transport roller pairs 46, 47, and 48. Incidentally, the pickup roller 42, the feed roller 43, the retard roller 44, and the transport roller pairs 46, 47, and 48 are all formed in a cylindrical shape with their central axes aligned in the left-right direction.

[0039] The paper cassette 41 is configured in a hollow rectangular parallelepiped shape and is detachable from the housing 2. The paper cassette 41 stores the medium M in a stacked state with the paper surface facing up and down, i.e., in a stacked state. In this embodiment, the medium M is a so-called OHP (Overhead Projector) film, specifically, for example, CG3700 (manufactured by 3M Japan Ltd.). The medium M has a sufficiently high transmittance of visible light and is a so-called transparent film-like medium.

[0040] The pickup roller 42 is in contact with the vicinity of the front end of the top surface of the medium M stored in the paper cassette 41. The feed roller 43 is disposed slightly in front of the pickup roller 42. The retard roller 44 is located below the feed roller 43, and a gap equivalent to the thickness of one sheet of medium M is formed between the retard roller 44 and the feed roller 43.

[0041] When a driving force is supplied from a paper feed motor (not shown), the first paper feed section 40 appropriately rotates or stops the pickup roller 42, feed roller 43, and retard roller 44. As a result, the pickup roller 42 feeds forward the topmost sheet or sheets of media M stored in the paper cassette 41. The feed roller 43 and retard roller 44 feed the topmost sheet of media M further forward, while blocking the second and subsequent sheets. In this way, the first paper feed section 40 feeds forward the media M while separating them one by one.

[0042] The transport guide 45 is disposed in a front lower portion of the transport path W, and causes the medium M to travel in a front-upper direction and then in a rear-upper direction along the transport path W. The transport roller pairs 46 and 47 are disposed near the center and near the upper end of the transport guide 45, respectively, and rotate in a predetermined direction by a driving force supplied from a paper feed motor (not shown). The transport roller pairs 46 and 47 thereby cause the medium M to travel along the transport path W.

[0043] Further, a second paper feed section 50 is provided in front of the pair of transport rollers 47 in the housing 2. The second paper feed section 50 is provided with a paper tray 51, a pickup roller 52, a feed roller 53, a retard roller 54, etc. The paper tray 51 is formed in a thin plate shape in the vertical direction, and is configured to place the medium M2 on its upper side. Incidentally, the medium M2, which is different in size and paper quality from the medium M stored in the paper cassette 41, for example, is placed on the paper tray 51.

[0044] The pickup roller 52, the feed roller 53, and the retard roller 54 are configured in the same manner as the pickup roller 42, the feed roller 43, and the retard roller 44 of the first paper feed section 40. When the second paper feed section 50 receives a driving force from a paper feed motor (not shown), it appropriately rotates or stops the pickup roller 52, the feed roller 53, and the retard roller 54 to feed the bottommost sheet of the medium M2 on the paper tray 51 backward, while blocking the second and subsequent sheets. Thus, the second paper feed section 50 feeds the medium M2 backward while separating them one by one. The fed medium M2 is transported by the transport roller pair 57 along the transport path W in the same manner as the medium M. For convenience of explanation, the medium M2 will not be distinguished from the medium M and will simply be referred to as the medium M below.

[0045] The rotation of the transport roller pair 47 is appropriately restricted, and a frictional force is applied to the medium M to correct the inclination of the sides of the medium M with respect to the direction of travel, i.e., to align the leading and trailing edges to the left and right, before sending the medium backward. The transport roller pair 48 is located a predetermined distance rearward from the transport roller pair 47, and rotates in the same manner as the transport roller pair 46, etc., to supply a driving force to the medium M transported along the transport path W, causing the medium M to travel further rearward along the transport path W.

[0046] The secondary transfer section 39 of the intermediate transfer section 30 described above, that is, the backup roller 33 and the secondary transfer roller 36, are disposed behind the pair of transport rollers 48. In the secondary transfer section 39, the toner image formed in the image forming unit 10 and transferred to the intermediate transfer belt 34 approaches the intermediate transfer belt 34 as the intermediate transfer belt 34 travels, and a predetermined bias voltage is applied to the secondary transfer roller 36. Therefore, the secondary transfer section 39 transfers the toner image from the intermediate transfer belt 34 to the medium M transported along the transport path W, and causes the medium M to proceed further backward.

[0047] A fixing unit 60 is disposed behind the secondary transfer unit 39. The fixing unit 60 is composed of a heating unit 61 and a pressure unit 62 disposed to face each other across the transport path W. The heating unit 61 has a heater that generates heat, a plurality of rollers, and the like disposed inside a heating belt that is a hollow endless belt. The pressure unit 62 is formed as a cylindrical pressure roller with a central axis aligned in the left-right direction, and presses an upper surface against a lower surface of the heating unit 61 to form a nip portion.

[0048] Based on the control of the control unit 3, the fixing unit 60 heats the heater of the heating unit 61 to a predetermined temperature, rotates the roller appropriately to rotate the heating belt in the direction of the arrow R1, and rotates the pressure unit 62 in the direction of the arrow R2. After that, when the fixing unit 60 receives the medium M onto which the toner image has been transferred by the secondary transfer unit 39, it sandwiches (i.e. nips) it between the heating unit 61 and the pressure unit 62 and applies heat and pressure to fix the toner image to the medium M, and then sends it out backwards.

[0049] A pair of transport rollers 64 is disposed behind the fixing unit 60, and a switching unit 65 is disposed behind the pair of transport rollers 64. The switching unit 65 switches the traveling direction of the medium M to the upward or downward direction according to the control of the control unit 3. A paper discharge unit 70 is provided above the switching unit 65. The paper discharge unit 70 is composed of a transport guide 71 that guides the medium M upward along the transport path W, pairs of transport rollers 72, 73, 74, and 75 that face each other across the transport path W, and a discharge port 76.

[0050] Further, a re-conveying unit 66 is disposed below the switching unit 65, the fixing unit 60, the secondary transfer unit 39, etc. The re-conveying unit 66 has a conveying guide, a pair of conveying rollers (not shown), etc. that constitute a re-conveying path Z. The re-conveying path Z heads downward from below the switching unit 65, and then proceeds forward, and merges with the conveying path W downstream of the pair of conveying rollers 57.

[0051] When discharging the medium M, the control unit 3 switches the traveling direction of the medium M to the upper discharge unit 70 side by the switching unit 65. The discharge unit 70 transports the medium M received from the switching unit 65 upward and discharges it from the discharge port 76 to the discharge tray 2T. When returning the medium M upside down, the control unit 3 switches the traveling direction of the medium M to the lower re-conveyance unit 66 side by the switching unit 65. The re-conveyance unit 66 transports the medium M received from the switching unit 65 to the re-conveyance path Z, and eventually reaches the downstream side of the transport roller pair 57, causing the medium M to be transported again along the transport path W. In this way, the image forming apparatus 1 can return the medium M to the transport path W with the paper surface of the medium M turned upside down, thereby performing so-called double-sided printing.

[0052] In this manner, in the image forming device 1, a toner image is formed using toner T in the image forming unit 10 and transferred to the intermediate transfer belt 34, the toner image is transferred from the intermediate transfer belt 34 to the medium M in the secondary transfer section 39, and then fixed in the fixing section 60, thereby printing an image on the medium M, i.e., forming an image.

[0053] For example, in the image forming apparatus 1, when the image forming unit 10 sequentially transfers a glitter toner image PS made of silver toner TS and a color toner image PL made of color toner TL onto the intermediate transfer belt 34, these images are transferred onto the medium M at the secondary transfer section 39. As a result, the medium M has a state in which the color toner image PL and the glitter toner image PS are printed and superimposed on its surface.

[0054] Furthermore, the image forming apparatus 1 can transfer and fix a color toner image PL onto the front surface of the medium M, for example, and then return the medium M to the downstream side of the pair of transport rollers 57 by the re-transport unit 66 and turn the medium M over, so as to transfer and fix a glossy toner image PS onto the rear surface of the medium M. In this case, the medium M is in a state in which the color toner image PL is printed on the front surface and the glossy toner image PS is printed on the rear surface.

[0055] In this case, the image forming apparatus 1 may set the fixing temperatures for the first fixing process in which the color toner image PL is fixed to the front surface of the medium M by the fixing section 60, and the second fixing process in which the glossy toner image PS is fixed to the back surface of the medium M to be the same (e.g., 150°C) or different.

[0056] Furthermore, after transferring and fixing the glossy toner image PS onto the surface of the medium M, the image forming apparatus 1 can return the medium M to the downstream side of the pair of transport rollers 57 without turning it over by the re-transport unit 66, and transfer and fix the color toner image PL onto the same surface of the medium M. In this case, the medium M is in a state where the glossy toner image PS and the color toner image PL are printed and superimposed on its surface.

[0057] Incidentally, in the image forming apparatus 1, the absolute value of the bias voltage applied to each part under the control of the control unit 3 can be increased to increase the amount of toner T adhering to the toner image transferred to the medium M, and the absolute value of the bias voltage can be decreased to decrease the amount of toner T adhering to the medium M.

[0058] Next, the circuit configuration of the image forming apparatus 1 will be described with reference to the block diagram of Fig. 3. The control unit 3 of the image forming apparatus 1 is configured mainly around a print control unit 80, to which a storage unit 81, an interface unit 82, a display control unit 83, a process control unit 84, a development voltage control unit 85, a supply voltage control unit 86, an exposure control unit 87, a transfer voltage control unit 88, and a motor control unit 89 are connected.

[0059] The printing control unit 80 has a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, and a RAM (Random Access Memory) 93 inside, and performs various processes by using the RAM 93 as a work area and executing various programs read from the ROM 92, the memory unit 81, etc. by the CPU 91.

[0060] The storage unit 81 is a non-volatile storage medium such as a hard disk drive (HDD) or a solid state drive (SSD), and stores various programs and information. The storage unit 81 is provided with a normal color data conversion table 95 and a glitter color data conversion table 96. The normal color data conversion table 95 stores information for forming a print pattern of each color from a portion of the print data acquired from the higher-level device 100 that is represented by normal colors (black, cyan, magenta, and yellow). The glitter color data conversion table 96 stores information for forming a print pattern corresponding to a portion of the print data acquired from the higher-level device 100 that is represented by glitter color (silver).

[0061] The interface unit 82 functions as an interface for a wired LAN (Local Area Network) conforming to standards such as IEEE (Institute of Electrical and Electronics Engineers) 802.3u / ab / an / ae, or a wireless LAN conforming to standards such as IEEE 802.11a / b / g / n / ac / ax, etc. This interface unit 82 can transmit and receive various information to and from the higher-level device 100, a predetermined server device (not shown), etc.

[0062] Based on instructions from the print control unit 80, the display control unit 83 creates display screen data representing various display screens on which characters, figures, etc. are appropriately arranged, and sends the display screen data to the display unit 4, thereby causing the display screen to be displayed on the display unit 4.

[0063] The process control unit 84 controls the voltages of the various parts in the image forming units 10 for each color based on instructions from the print control unit 80. The development voltage control unit 85 controls the development voltage applied to the development roller 24 and the development blade 25 (FIG. 2) based on instructions from the print control unit 80. The supply voltage control unit 86 controls the supply voltage applied to the first supply roller 22 and the second supply roller 23 (FIG. 2) based on instructions from the print control unit 80.

[0064] The exposure control unit 87 controls the turning on and off of each light-emitting element chip provided in the LED head 14 based on instructions from the print control unit 80. The transfer voltage control unit 88 controls the transfer voltage applied to the primary transfer roller 35, the secondary transfer roller 36 (FIG. 2), etc. based on instructions from the print control unit 80. The motor control unit 89 controls the rotation of the photoconductor drum 26 (FIG. 2) and each roller, etc. based on instructions from the print control unit 80.

[0065] The higher-level device 100 is an information processing device such as a personal computer, and executes various application programs such as document creation, spreadsheets, and image editing based on user operations. A printer driver for printing documents, images, and the like in the image forming device 1 is pre-installed in the higher-level device 100. When the higher-level device 100 receives a print instruction for document data, image data, and the like from a user in an application program, the higher-level device 100 executes the printer driver to generate print data based on the document data, image data, and the like, and transmits the print data to the image forming device 1.

[0066] [1-2. Toner composition] Next, the toner (also called developer) stored in the toner container 12 of the image forming unit 10 (FIG. 2) will be described. For the standard colors of black (K), cyan (C), magenta (M) and yellow (Y), the toners of each color (black, cyan, magenta and yellow) commercially available for the C941dn manufactured by Oki Electric Industry Co., Ltd. were used.

[0067] For the bright special color (S) toner, a silver toner (hereinafter also referred to as silver toner) was manufactured as described above. This silver toner was manufactured by the following method.

[0068] When manufacturing silver toner, in this embodiment, an aqueous medium in which an inorganic dispersant is dispersed is first produced. Specifically, 600 parts by weight of industrial trisodium phosphate dodecahydrate is mixed with 18,400 parts by weight of pure water, and dissolved at a liquid temperature of 60°C. Dilute nitric acid for adjusting pH (hydrogen ion exponent) is then added. A calcium chloride aqueous solution in which 300 parts by weight of industrial calcium chloride anhydride is dissolved in 2,600 parts by weight of pure water is added to this aqueous solution, and while maintaining the liquid temperature at 60°C, the mixture is stirred at high speed for 50 minutes at a rotation speed of 3,566 rpm using a line mill (PRIMIX Corporation). This prepares the aqueous phase, which is an aqueous medium in which a suspension stabilizer (inorganic dispersant) is dispersed.

[0069] In this embodiment, a material dispersion oil medium is prepared. Specifically, 470 parts by weight of a glittering pigment (volume median diameter 5.4 [μm]) containing aluminum powder and 23 parts by weight of a charge control agent (BONTRON E-84: manufactured by Orient Chemical Industry Co., Ltd.) are mixed with 7000 parts by weight of ethyl acetate, which is an organic solvent, to prepare a pigment dispersion liquid.

[0070] In this embodiment, the luster pigment used has a volume average particle size (also called the volume median diameter) of 5.4 μm, but is not limited to this. Specifically, the volume average particle size of the luster pigment is preferably 5 μm or more and 20 μm or less, and more preferably within the range of 5.3 to 5.7 μm.

[0071] Then, in this embodiment, while maintaining the liquid temperature of the pigment dispersion at 60°C, 175 parts by weight of ester wax (WE-4: manufactured by NOF Corp.) and 1670 parts by weight of polyester resin are added and stirred until no solid matter remains. This prepares an oil phase, which is a pigment dispersion oil-based medium.

[0072] Next, in this embodiment, the oil phase is added to the aqueous phase whose liquid temperature has been lowered to 55° C., and the oil phase is suspended by stirring at a rotation speed of 1000 rpm for 5 minutes to form particles in the suspension. The suspension is then distilled under reduced pressure to remove ethyl acetate, forming a slurry containing a toner. Nitric acid is then added to the slurry to adjust the pH to 1.6 or less, and the slurry is stirred to dissolve tricalcium phosphate, which is a suspension stabilizer, and the toner is formed by dehydrating the slurry. The dehydrated toner is then redispersed in pure water, stirred, and washed with water. After that, in this embodiment, a dehydration process, a drying process, and a classification process are performed to generate toner base particles.

[0073] In this embodiment, 1.5% by weight of small silica (RY200: manufactured by Nippon Aerosil Co., Ltd.), 2.29% by weight of colloidal silica (X24-9163A: manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.37% by weight of melamine particles (EPOSTAR S: manufactured by Nippon Shokubai Co., Ltd.) are added to the toner base particles thus produced and mixed as an external addition process. Thus, in this embodiment, a silver toner having a lustrous property can be obtained. The volume median diameter of the silver toner thus produced was measured and found to be 15.01 μm. The volume median diameter of the silver toner is not limited to 15.01 μm, and may be, for example, 10 to 20 μm.

[0074] [1-3. Visual effects by medium] Next, a description will be given of a medium M on which an image is printed by the image forming apparatus 1. As shown in Fig. 4(A) and (B), for example, the image forming apparatus 1 can print a color toner image PL using normal color toner TL on the front side of the medium M, and can print a glittering toner image PS using silver toner TS having glittering properties on the back side of the medium M. Hereinafter, a medium M on which a color toner image PL (also referred to as a first image) is printed on one side (also referred to as one side or first side) and a glittering toner image PS (also referred to as a second image) is printed on the other side (also referred to as the other side, opposite side or second side) of the medium M will be referred to as a decorated medium MC.

[0075] Further, under the control of the control unit 3, the image forming apparatus 1 forms a plurality of regions such as a background region AB and a decorative region AC on the other side of the decorative medium MC on which the glossy toner image PS is formed, as shown in a schematic enlarged view in Fig. 4(C). In this glossy toner image PS, the amount of silver toner TS adhered per unit area differs between the background region AB and the decorative region AC. For convenience of explanation, hereinafter, the background region AB will also be referred to as the first region, and the decorative region AC will also be referred to as the second region.

[0076] The amount of toner (color toner TL or silver toner TS) adhered to the medium M per unit area can be expressed by image density N [%]. This image density N corresponds to the ratio of the area of ​​the printed portion (the portion where an image is formed) to the entire area in the printable range of a predetermined area (for example, an area equivalent to one revolution of the photoconductor drum 26 or an area equivalent to one sheet of the medium M). Furthermore, this image density N is set to 100 [%] when an image with an area ratio of 100 [%] is printed, as in so-called full-surface solid printing. For example, when an image is printed in an area equivalent to an area of ​​1 [%] of the printable range of the medium M, the image density N is 1 [%].

[0077] Incidentally, when the image density N is less than 100[%], for example, in an image with an image density N of 100[%], this can be achieved by thinning out the toner in a thin line shape along a direction perpendicular to a predetermined direction at a predetermined thinning interval in the predetermined direction. In this case, the image density N can be adjusted by adjusting the thinning interval or the width (number of dots) of the thin line.

[0078] Alternatively, when the image density N is to be less than 100[%], it can be realized by thinning out the toner in a halftone dot pattern in an image with an image density N of 100[%]. In this case, the image density N can be adjusted by adjusting the number and size of the halftone dots contained per unit area.

[0079] Here, the number of dots for which toner is actually used in the printing process when the photoconductor drum 26 rotates a predetermined number of rotations Cd, i.e., the number of exposed dots, is defined as the number of dots used Cm. Also, the number of dots per rotation of the photoconductor drum 26, i.e., the maximum number of dots that can potentially be printed when the photoconductor drum 26 rotates once, regardless of whether it is exposed to light or not, and the number of dots when printing a so-called solid image, is defined as the total number of dots C0.

[0080] Then, the maximum number of dots that can potentially be printed when the photoconductor drum 26 rotates Cd times is (Cd x C0) dots. Using this, the image density N can be expressed by the following equation (1).

[0081] N=[Cm / (Cd×C0)] / 100 [%] ……(1)

[0082] Furthermore, the amount of toner (color toner TL or silver toner TS) adhered to medium M per unit area can be expressed by print duty D in addition to the image density N described above. This print duty D is the ratio of the area in which toner is used in a printed image based on print data, assuming that the area in which a solid image is printed in an image-formable region of medium M is 100%. It is also the proportion of the area in which the toner adheres to medium M. For this reason, hereinafter, print duty D is also referred to as the adhesion ratio. Note that the solid image referred to here is a toner image on medium M formed by exposing the entire area in the printable range of photoconductor drum 26, and is an image in which toner is used in all dots.

[0083] In other words, printing duty D is the ratio of the number of dots used in the actual toner image based on the printing data to the total number of dots that make up the area of ​​medium M on which an image can be formed, and is sometimes called the printing rate.

[0084] For example, when the control unit 3 prints an image based on print data on a certain medium M, it calculates the print duty D by the following formula (2) by taking the dot count of the image data based on the print data as C1 and the dot count when the medium M is fully exposed to light as C0. Note that formula (2) is just an example, and the control unit 3 can also calculate the print duty D by other formulas.

[0085] D = (C1 / C0) × 100 [%] …… (2)

[0086] That is, in the glossy toner image PS, the print duty D of the background area AB (hereinafter referred to as background print duty DB) differs from the print duty D of the decorative area AC (hereinafter referred to as decorative print duty DC). As an example, in the glossy toner image PS of the decorative medium MC, the background print duty DB can be 100[%] and the decorative print duty DC can be 75[%]. For convenience of explanation, hereinafter the background print duty DB is also referred to as the first adhesion ratio, and the decorative print duty DC is also referred to as the second adhesion ratio.

[0087] As shown in Figure 5 (A), when a user views this decorative medium MC, which has black paper MK superimposed on the back side, from the front side at a predetermined angle, the color toner image PL on the front side is visible, but the decorative area AC and background area AB on the back side are not perceived.

[0088] On the other hand, as shown in Fig. 5(B), when the user views the decoration medium MC with the black paper MK superimposed on the back side from the front side at an angle (posture) different from that of Fig. 5(A), the decoration medium MC can make the decoration area AC on the back side and the background area AB look different from each other by superimposing it on the color toner image PL on the front side. That is, in this case, the decoration medium MC can make the user visually recognize an image in which the decoration area AC appears to stand out from the background area AB.

[0089] In this way, the decoration medium MC can switch between a state in which the decoration area AC is hidden (FIG. 5(A)) and a state in which the decoration area AC is visible (FIG. 5(B)) by changing the angle of the user's viewpoint or the light source, etc. In other words, the decoration medium MC has a visual effect in which the decoration area AC is made visible and invisible to the user by changing the position and posture of the decoration medium MC in various ways.

[0090] For example, as a visual effect for a user, the decoration medium MC can initially allow only the color toner image PL on the surface to be seen, and then, when the position of the decoration medium MC is changed, the user is given the impression that the decoration area AC has emerged, overlapping with the color toner image PL.

[0091] Next, the principle of how such a visual effect is produced in the decoration medium MC will be described. If the surface of the decoration medium MC is shown to a user in a bright place, the color toner image PL reflects light, allowing the user to clearly see the color toner image PL.

[0092] Furthermore, if the back side of the decorative medium MC is shown to a user in a bright place, the glossy pigment (aluminum flakes, etc.) contained in the glossy toner image PS reflects light well, allowing the user to clearly see the glossy toner image PS. Furthermore, as described above, the glossy toner image PS has different print duties D in the background area AB and the decorative area AC. Therefore, the decorative medium MC causes the degree of light reflection to differ between the background area AB and the decorative area AC, allowing the user to clearly recognize the boundary between the two and the shape of the decorative area AC.

[0093] Next, as shown in Fig. 6(A), assume that black paper MK is placed on the back side of the decoration medium MC, and the light source LS and the user's viewpoint VP are both located on the front side of the decoration medium MC. In this case, the black paper MK blocks light at the back side of the decoration medium MC, so light does not pass from the back side to the front side of the decoration medium MC.

[0094] At this time, the decoration medium MC reflects the light from the light source LS well with the color toner image PL on the front side, and the color toner image PL delivers light of sufficient intensity to the user's eyes. The decoration medium MC also allows a portion of the light from the light source LS to pass through the color toner image PL and the transparent medium M and reach the glossy toner image PS on the back side. The decoration medium MC reflects this light with a relatively high reflectance with the glossy toner image PS, and a portion of the light passes through the transparent medium M and the color toner image PL and travels toward the user's viewpoint VP.

[0095] Here, when focusing on the intensity of light reaching the user's viewpoint VP, the intensity of light reflected by the color toner image PL is much greater than the intensity of light reflected by the glossy toner image PS. Therefore, when the user looks at the front side of the decoration medium MC, as shown in Fig. 5(A), the user can clearly see the color toner image PL, but can barely see the glossy toner image PS. In other words, the decoration medium MC can hide the image represented by the decoration area AC of the glossy toner image PS from the user in the state shown in Fig. 6(A).

[0096] Next, as shown in Fig. 6(B), assume that black paper MK is placed on the back side of the decoration medium MC, the user's viewpoint VP is located on the front side of the decoration medium MC, and the light source LS is located on the back side of the decoration medium MC. In this case, too, the light is blocked by the black paper MK at the back side of the decoration medium MC, so that no light passes from the back side to the front side of the decoration medium MC.

[0097] At this time, due to the positional relationship between the decoration medium MC and the light source LS, the color toner image PL on the front side of the decoration medium MC cannot sufficiently reflect the light from the light source LS, and the color toner image PL delivers relatively weak light to the user's eyes. On the other hand, the decoration medium MC allows part of the light from the light source LS to pass through the color toner image PL and the transparent medium M and reach the glossy toner image PS on the back side. The decoration medium MC reflects this light with a relatively high reflectance by the glossy toner image PS, and part of the light passes through the transparent medium M and the color toner image PL and travels toward the user's viewpoint VP.

[0098] Here, when focusing on the intensity of light reaching the user's viewpoint VP, the intensity of light reflected by the color toner image PL is not so great as the intensity of light reflected by the glossy toner image PS. Therefore, when the user looks at the front side of the decoration medium MC, as shown in Fig. 5(B), the user can see the color toner image PL to some extent, while also seeing the glossy toner image PS. In other words, in the state shown in Fig. 6(B), the decoration medium MC can show the user an image formed as the decoration area AC of the glossy toner image PS.

[0099] [1-4. Conditions for obtaining visual effects] Next, in order to find the conditions for obtaining a good visual effect for the decorative medium MC on which decorative printing was performed on the medium M by the image forming device 1, several types of decorative medium MC were created with different printing duties of the silver toner TS in the glossy toner image PS, and evaluation tests were conducted.

[0100] [1-4-1. Creating evaluation media] In this evaluation test, an OHP film CG3700 (manufactured by 3M Japan Ltd.) was used as the medium M. In addition, in this evaluation test, an image with a printing duty of 100% for cyan (C) toner, a so-called solid image, was used as the color toner image PL. Hereinafter, this color toner image PL is also referred to as a cyan image.

[0101] Furthermore, in this evaluation test, the optical density OD of the medium M with a cyan image printed on the surface was measured using a spectrophotometer (X-Rite eXact: X-Rite Corporation). In this evaluation test, the optical density OD was set to a value of 1.4 and the amount of formation on the medium (amount of adhesion on the paper surface) was set to 0.45 [mg / cm 2 ] by the control of the control unit 3. 2 Various bias voltages (developing voltage, etc.) related to the cyan (C) image forming unit 10C in the image forming apparatus 1 were adjusted so that:

[0102] Next, in this evaluation test, a glossy toner image PS was printed using silver toner TS on the back surface of medium M. Specifically, in image forming apparatus 1, a color toner image PL (cyan image) was transferred and fixed on the front surface of medium M, and then medium M was turned over by re-conveyance unit 66 (FIG. 1), and a glossy toner image PS was transferred and fixed on the back surface of medium M.

[0103] In this evaluation test, the print duty D of the background area AB (ie, background print duty DB) was set to 100[%], and the print duty D of the decorative area AC (ie, decorative print duty DC) was set to a value less than 100[%].

[0104] In this evaluation test, the visual reflectance difference ΔY was used to adjust the silver toner TS in the image forming apparatus 1. This visual reflectance difference ΔY was calculated by subtracting the visual reflectance Y2 on the medium M before printing from the visual reflectance Y1 on the image after printing. A spectrophotometer CM-2600d (manufactured by Konica Minolta Japan, Inc.) was used to measure the visual reflectance difference ΔY. The measurement conditions were as follows: the light source was auxiliary illuminant C for color measurement (6774[K]), and SCE (specularly reflected light excluded) was used for the specular reflected light.

[0105] In this evaluation test, various bias voltages (developing voltage, etc.) related to the silver (S) image forming unit 10S were appropriately adjusted so that the luminous reflectance difference ΔY in the background area AB of the glitter toner image PS printed on the back side of the medium M by the image forming apparatus 1 was a value of 36. Furthermore, in the image forming apparatus 1, this adjustment resulted in the amount of glitter toner image PS formed on the medium (amount attached on the paper surface) being 0.65 [mg / cm] when the print duty D of the background area AB was 100 [%]. 2 ] became.

[0106] In addition, in this evaluation test, evaluation images PE (PE1, PE2, ..., PE8) were formed as the glittering toner images PS by varying the decorative printing duty DC (i.e., the printing duty D of the decorative area AC) in eight stages at intervals of 6.25% from 93.75% and printed on the back surface of the medium M. Hereinafter, the medium M having the color toner image PL printed on the front surface and the evaluation image PE printed on the back surface in this manner will also be referred to as the evaluation medium ME.

[0107] Specifically, the decorative print duties DC of the evaluation images PE were set to 93.75[%], 87.50[%], 81.25[%], 75.00[%], 68.75[%], 62.50[%], 56.25[%], and 50.00[%], as shown in Table TBL1 in Fig. 7(A). Accordingly, the formation amount on the medium in the decorative area AC of each evaluation image PE was 0.61[mg / cm 2 ], 0.57 [mg / cm 2 ], 0.53 [mg / cm 2 ], 0.49 [mg / cm 2 ], 0.45 [mg / cm 2 ], 0.41 [mg / cm 2 ], 0.37 [mg / cm 2 ] and 0.33 [mg / cm 2 Incidentally, in each evaluation image PE, multiple "OK" characters (FIGS. 4(C) and 5(B)) were formed by the decorative area AC.

[0108] In addition, for each evaluation image PE, the duty difference, which is the difference between the background print duty DB and the decorative print duty DC, was calculated and listed in table TBL1 in Fig. 7(A). This duty difference represents the difference in the adhesion amount per unit area of ​​the silver toner TS, and as mentioned above, the values ​​differ by 6.25[%].

[0109] Incidentally, in each evaluation image PE, the background print duty DB is 100[%], so the value of the decorative print duty DC represents the ratio of the decorative print duty DC to the background print duty DB, and the ratio of the on-medium formation amount of the decorative area AC to the on-medium formation amount of the background area AB. For example, in the evaluation image PE1, the value of the decorative print duty DC is 93.75[%], and the ratio of the decorative print duty DC to the background print duty DB is also 93.75[%]. Also, for example, in the evaluation image PE3, the value of the decorative print duty DC is 81.25[%], and the ratio of the on-medium formation amount of the decorative area AC to the on-medium formation amount of the background area AB is 0.82 when rounded off to the third decimal place.

[0110] [1-4-2. Reflectance measurement] Next, in this evaluation test, as shown in the schematic diagram of Figure 8, a medium M was prepared in which the color toner image PL was not printed on the front side, and each evaluation image PE was printed only on the back side of the medium M (hereinafter referred to as measurement medium MM), and the reflectance was measured using this measurement medium MM. Hereinafter, this measurement will be referred to as reflectance measurement.

[0111] In this reflectance measurement, as shown in Fig. 8, the light source LS was placed so that the incident angle with respect to the surface of the measurement medium MM was 45 degrees, and the viewpoint VP of the user (the person making the judgment) was positioned in a direction that forms 90 degrees with respect to the surface. In other words, the viewpoint VP was positioned so that the line of sight LVP from the viewpoint VP was perpendicular to the surface of the measurement medium MM, and the angle that the line of sight LVP makes with the normal line of the surface was 0°. Hereinafter, the reflectance obtained by this reflectance measurement will also be referred to as the 0° reflectance or Y value.

[0112] In this reflectance measurement, a goniophotometer GC500L (manufactured by Nippon Denshoku Industries Co., Ltd.) was used to measure the light reflectance in each of the decorative area AC and background area AB of each measurement medium MM on which each evaluation image PE was printed, and the measurement results shown in Table TBL2 shown in Figure 7(B) were obtained. Table TBL2 also lists the difference in reflectance between each of the evaluation images PE in the decorative area AC and the background area AB.

[0113] Comparing the various values ​​listed in Tables TBL1 and TBL2, it can be seen that as the decorative printing duty DC, which is the printing duty D in the decorative area AC, increases or decreases, the value of the 0° reflectance (Y value) in the decorative area AC also increases or decreases, that is, there is a correlation between the printing duty D and the 0° reflectance (Y value).

[0114] [1-4-3. Measurement of luminous reflectance difference] Next, in this evaluation test, the luminous reflectance difference ΔY was measured using the measurement medium MM under the same conditions as those described above for the adjustment of the silver toner TS in the image forming apparatus 1.

[0115] Specifically, when the luminous reflectance difference ΔY in the decorative area AC and the background area AB was measured using each measurement medium MM on which each evaluation image PE was printed, the measurement results shown in Table TBL2 (FIG. 7(B)) were obtained. Table TBL2 also lists the calculated values ​​of the difference between the value of the decorative area AC and the value of the background area AB and the rate of decrease (decrease rate) for each evaluation image PE.

[0116] Comparing the various values ​​listed in Tables TBL1 and TBL2, it can be seen that as the decorative printing duty DC, which is the printing duty D in the decorative area AC, increases or decreases, the value of the visual reflectance difference ΔY in the decorative area AC also increases or decreases, that is, there is a correlation between the printing duty D and the visual reflectance difference ΔY.

[0117] [1-4-4. Image recognition judgment] Next, in this evaluation test, a medium M (hereinafter referred to as evaluation medium ME) was used, in which a color toner image PL was printed on the front side and each evaluation image PE was printed on the back side in place of the glossy toner image PS, and a visual judgment was made on the image. This visual judgment was made under two different viewing conditions in which the angle of the line of sight to the image was different under a fixed light source, and it was judged whether or not the background area AB and the decorative area AC could be distinguished, that is, whether or not the word "OK" could be seen. Hereinafter, this judgment will be referred to as a visual judgment.

[0118] The two viewing conditions were the first viewing condition, which is shown in Fig. 9(A) and the second viewing condition, which is shown in Fig. 9(B). In the first viewing condition, the light source LS was placed so that the angle of incidence with respect to the surface of the evaluation medium ME was 45 degrees, and the viewpoint VP of the user (the person making the judgment) was positioned in a direction that forms an angle of 90 degrees with respect to the surface, i.e., the line of sight LVP from the viewpoint VP was positioned perpendicular to the surface.

[0119] In the second viewing condition, as in the first viewing condition, the light source LS was positioned so that the angle of incidence with respect to the surface of the evaluation medium was 45 degrees, while the viewpoint VP of the user (the person making the judgment) was positioned on the same straight line as the incident direction from the light source LS, i.e., the line of sight LVP from the viewpoint VP was positioned at 45 degrees with respect to the surface.

[0120] In all viewing conditions, a fluorescent lamp was used as the light source LS, and the distance from the light source LS to the evaluation medium ME was set to 200 [mm], so that the illuminance on the surface of the evaluation medium ME was about 800 [lx]. In addition, this viewing judgment was performed in a dark room to eliminate the influence of other lighting, etc.

[0121] In addition, in this visual recognition evaluation, a sufficiently thick piece of black paper MK was placed on the back side of the evaluation medium ME. This prevented the scenery on the back side from being seen through the medium M, which has a high visible light transmittance.

[0122] When these two types of visual judgments were performed, the judgment results shown in Table TBL3 shown in Fig. 7(C) were obtained. That is, under the first viewing condition, the background region AB and the decorative region AC could not be distinguished in the evaluation media ME1 to ME6, but could be distinguished between the two in the evaluation media ME7 and ME8. On the other hand, under the second viewing condition, the background region AB and the decorative region AC could not be distinguished in the evaluation media ME1 and ME2, but could be distinguished between the two in the evaluation media ME3 to ME8. In Table TBL3, the fact that the background region AB and the decorative region AC could be distinguished is represented by the symbol "○", and the fact that they could not be distinguished is represented by the symbol "×".

[0123] Here, the relationship between the results of the two types of visibility judgment and the visual effect of the decorated area AC appearing or disappearing depending on the angle of the medium M will be summarized.

[0124] For the evaluation media ME1 and ME2, the background area AB and the decorative area AC could not be distinguished under either the first viewing condition or the second viewing condition. In other words, for both, the decorative area AC remained invisible (hidden) regardless of the angle of the medium M. In other words, for the evaluation media ME1 and ME2, the visual effect of the decorative area AC appearing and disappearing could not be obtained.

[0125] Furthermore, for evaluation media ME7 and ME8, the background region AB and the decorative region AC could be distinguished under both the first viewing condition and the second viewing condition. In other words, for both, the decorative region AC remained visible regardless of the angle of the medium M. In other words, for evaluation media ME7 and ME8, the visual effect of the decorative region AC appearing and disappearing was not obtained.

[0126] On the other hand, for the evaluation media ME3 to ME6, the background area AB and the decorated area AC could not be distinguished under the first viewing condition, but the two could be distinguished under the second viewing condition. In other words, the decorated area AC changed between being visible and not being visible (hidden) depending on the angle of the medium M. That is, for the evaluation media ME3 to ME6, a visual effect was obtained in which the decorated area AC appeared and disappeared.

[0127] Furthermore, for evaluation media ME4 and ME5, the difference in appearance between the background region AB and the decorated region AC was larger under the second viewing condition than for evaluation media ME3 and ME6, and the decorated region AC was more clearly visible. In other words, for evaluation media ME4 and ME5, a noticeable visual effect of the decorated region AC appearing and disappearing was observed.

[0128] In this evaluation test, the overall evaluation of the visual effect was shown in Table TBL3 (Figure 7(C)), with the symbol "◎" indicating that the visual effect was significantly observed, the symbol "○" indicating that the visual effect was obtained, and the symbol "×" indicating that the visual effect was not obtained.

[0129] Here, the conditions for obtaining the visual effect are summarized based on Tables TBL1, TBL2, and TBL3 (FIG. 7). If the background print duty DB is 100%, the range of the decorative print duty DC for obtaining the visual effect is 62.50% or more and 81.25% or less, and the duty difference between the two for obtaining the visual effect is 18.75% or more and 37.50% or less. Furthermore, the range of the ratio of the decorative print duty DC to the background print duty DB for obtaining the visual effect is 62.50% or more and 81.25% or less, which is also the value of the decorative print duty DC.

[0130] The range of the difference in 0° reflectance between the background area AB and the decorative area AC to obtain a visual effect is from 1.53% to 5.79%. The range of the difference in luminous reflectance difference ΔY between the background area AB and the decorative area AC to obtain a visual effect is from 8 to 14, and the range of the reduction rate of the decorative area AC relative to the background area AB is from 22% to 39%.

[0131] These values ​​are the quantitative expressions of the results of the above-mentioned visibility judgment using different methods. For example, it means that the visual effect is obtained if the difference in 0° reflectance between the background area AB and the decorative area AC is within the range of 1.53% to 5.79%.

[0132] [1-5. Decorative media printing process] Next, a decorative medium printing process will be described in which a decorative medium MC is created by printing an image that provides a visual effect on a medium M using the image forming apparatus 1. When the control unit 3 (FIG. 3) of the image forming apparatus 1 receives print data from the higher-level device 100 via the interface unit 82, the control unit 3 reads and executes a decorative medium printing program from the storage unit 81 using the print control unit 80, starts a decorative medium printing process procedure RT1 shown in FIG. 10, and proceeds to the first step SP1.

[0133] In step SP1, the control unit 3 causes the first paper feed unit 40 to feed one sheet of medium M from the paper cassette 41 and transport it along the transport path W, and then proceeds to the next step SP2. As a result, the medium M is transported to the secondary transfer unit 39 with its front surface facing upward (the side facing the intermediate transfer belt 34).

[0134] In step SP2, the control unit 3 controls the normal color image forming units 10 (10K, 10C, 10M and 10Y) based on the received printing data to form the color toner image PL to be printed on the surface of the medium M on the intermediate transfer belt 34 (Figures 1 and 2), and then proceeds to the next step SP3.

[0135] In step SP3, the control unit 3 causes the secondary transfer unit 39 to transfer the color toner image PL from the intermediate transfer belt 34 to the surface of the medium M, and then proceeds to the next step SP4. In step SP4, the control unit 3 causes the fixing unit 60 to fix the color toner image PL on the surface of the medium M, and then proceeds to the next step SP5.

[0136] In step SP5, the control unit 3 causes the re-conveying unit 66 to turn the medium M over and return it to the conveying path W, and then causes it to be conveyed further along the conveying path W, and proceeds to the next step SP6. As a result, the medium M is conveyed to the secondary transfer unit 39 with the back side facing up (the side facing the intermediate transfer belt 34).

[0137] In step SP6, the control unit 3 controls the silver image forming unit 10S based on the received print data to form the glossy toner image PS to be printed on the back side of the medium M on the intermediate transfer belt 34, and then proceeds to the next step SP7. At this time, the control unit 3 forms the background area AB and the decorative area AC (FIG. 4) on the glossy toner image PS based on the received print data. The control unit 3 also controls the background print duty DB of the background area AB to be 100[%], and the decorative print duty DC of the decorative area AC to be in the range of 62.50[%] or more and 81.25[%] or less.

[0138] In step SP7, the control unit 3 causes the secondary transfer unit 39 to transfer the glossy toner image PS from the intermediate transfer belt 34 to the back surface of the medium M, and proceeds to the next step SP8. In step SP8, the control unit 3 causes the fixing unit 60 to fix the glossy toner image PS to the back surface of the medium M, and proceeds to the next step SP9. At this time, on the front surface of the medium M, heat and pressure are also applied to the color toner image PL by the fixing unit 60, so that the surface of the color toner image PL is further smoothed.

[0139] In step SP9, the control unit 3 causes the paper discharge unit 70 to transport the medium M along the transport path W and discharge it from the discharge port 76 to the paper discharge tray 2T, then proceeds to the next step SP10, where the decorative medium printing process procedure RT1 ends. As a result, the image forming apparatus 1 can print a color toner image PL on the front side of the medium M and print a glossy toner image PS on the back side thereof, i.e., create a decorative medium MC.

[0140] [1-6. Effects, etc.] In the above configuration, the image forming apparatus 1 according to the first embodiment prints a color toner image PL on the front surface of a medium M, and prints a glossy toner image PS having a background area AB and a decorative area AC on the back surface of the medium M, thereby printing a decorative medium MC.

[0141] In this case, when the image forming device 1 forms the glittering toner image PS by the silver image forming unit 10S, the background printing duty DB of the background area AB is set to 100[%], and the decorative printing duty DC of the decorative area AC is set to a range of 62.50[%] or more and 81.25[%] or less. From another perspective, the image forming device 1 sets the duty difference between the background printing duty DB and the decorative printing duty DC to be 18.75[%] or more and 37.50[%] or less, and also sets the range of the ratio of the decorative printing duty DC to the background printing duty DB to be 62.50[%] or more and 81.25[%] or less.

[0142] In other words, the image forming apparatus 1 sets the difference in the amount of toner formed on the medium (the amount of toner attached on the paper surface) between the background area AB and the decorative area AC to 0.12 [mg / cm 2 ] or more 0.24[mg / cm 2 In addition, the image forming apparatus 1 sets the range of the ratio of the amount of the decorative area AC formed on the medium to the amount of the background area AB formed on the medium to be 0.63 or more and 0.82 or less when rounded off to two decimal places.

[0143] As a result, the image forming device 1 can provide a good visual effect in which the decorative area AC appears and disappears on the surface of the decorative medium MC when the user changes the position and posture of the decorative medium MC in various ways, such as when the relative positions and angles of the user's viewpoint VP, light source LS, and the decorative medium MC change in various ways.

[0144] Incidentally, as described above, in the glossy toner image PS, there is a certain degree of difference in the print duty D (background print duty DB and decorative print duty DC) between the background area AB and the decorative area AC. Therefore, when the glossy toner image PS is printed on the medium M, there is a possibility that a step will be formed on the surface at the boundary between the background area AB and the decorative area AC.

[0145] For this reason, if a color toner image PL is printed on top of the glossy toner image PS on the front side of the medium M, as in the case of Patent Document 1, there is a possibility that the step at the boundary between the background area AB and the decorative area AC formed in the glossy toner image PS will appear as it is on the surface of the color toner image PL.

[0146] 6(A), the user may be able to see the step formed in the color toner image PL and may be able to perceive the shape of the decorative area AC. In other words, even if the user wishes to hide the decorative area AC, the user may be able to see the decorative area AC through the step.

[0147] In this regard, the image forming apparatus 1 is configured to print a color toner image PL on the front side of the medium M in the decorative medium MC, and to print a glossy toner image PS on the back side of the medium M (FIG. 4, etc.). That is, the image forming apparatus 1 prints the color toner image PL directly on the flat surface of the medium M, thereby making it possible to form the color toner image PL flat, regardless of the presence or absence of a step between the background area AB and the decorative area AC in the glossy toner image PS.

[0148] In other words, the image forming apparatus 1 can adequately hide the decorative area AC in the printed decorative medium MC, thereby preventing the decorative area AC from appearing more than necessary in a way that is different from its original appearance, and providing the user with a good visual effect.

[0149] Furthermore, the image forming apparatus 1 generates image data in which the print duty D is appropriately set for each of the portions that will become the background area AB and the portions that will become the decorative area AC, using the silver image forming unit 10S, based on the control of the control unit 3, and performs exposure processing, development processing, and the like based on the image data. In other words, the image forming apparatus 1 can easily create a decorative medium MC that provides a good visual effect while using a well-known mechanism that can form and print a toner image using silver toner, which is a brilliant color, without using any special parts, etc., for creating the decorative medium MC.

[0150] According to the above configuration, the image forming apparatus 1 according to the first embodiment prints a color toner image PL on the front side of the medium M, and prints a glittering toner image PS on the back side to print a decorative medium MC. In this case, the image forming apparatus 1 sets the duty difference between the background printing duty DB and the decorative printing duty DC in the glittering toner image PS to be 18.75[%] or more and 37.50[%] or less, and sets the range of the ratio of the decorative printing duty DC to the background printing duty DB to be 62.50[%] or more and 81.25[%] or less. As a result, the image forming apparatus 1 can provide a good visual effect in which the decorative area AC appears and disappears on the front side of the decorative medium MC when the relative positions and angles of the user's viewpoint VP, the light source LS, and the decorative medium MC are changed in various ways.

[0151] 2. Second embodiment An image forming apparatus 201 according to the second embodiment is different from the first embodiment in that it has a control unit 203 instead of the control unit 3, but is otherwise configured similarly. This control unit 203 creates (i.e. prints) the decoration medium MC by performing a process that is partially different from that of the control unit 3 according to the first embodiment.

[0152] Specifically, in the second embodiment, instead of the decoration medium MC according to the first embodiment (FIG. 4, etc.), a decoration medium MC2 shown in a schematic cross-sectional view in FIG. 11 is created. Compared to the decoration medium MC according to the first embodiment, this decoration medium MC2 has a medium M, a color toner image PL on the front side, and a glittering toner image PS on the back side that are configured similarly, and in addition, a coating toner image PV (hereinafter also referred to as a coating image) is superimposed on the back side.

[0153] The coated toner image PV is formed by the black image forming unit 10K (FIG. 1) using black toner TK. The coated toner image PV has a constant print duty in all parts, and a constant amount of black toner TK deposited per unit area (for example, the amount of deposition on the medium is 0.50 [mg / cm 2 ]).

[0154] In the second embodiment, the image forming apparatus 201 creates a decoration medium MC2 by performing a process that is partially different from that of the first embodiment, based on the control of the control unit 203. Specifically, when the control unit 203 receives print data from the higher-level device 100 (FIG. 3), it starts a decoration medium printing process procedure RT2 shown in FIG. 12, which corresponds to FIG. 10, and proceeds to the first step SP201.

[0155] In steps SP201 to SP208, the control unit 203 performs the same processes as steps SP1 to SP8 of the decorative medium printing processing procedure RT1 (FIG. 10), and proceeds to the next step SP209. As a result, the control unit 203 forms and fixes a color toner image PL on the front side of the medium M, and forms and fixes a glossy toner image PS on the back side of the medium M.

[0156] In step SP209, the control unit 203 causes the re-conveying unit 66 to return the medium M to the conveying path W without turning it over, and conveys it along the conveying path W, and proceeds to the next step SP210. As a result, the medium M is conveyed to the secondary transfer unit 39 with the back side still facing upward (the side facing the intermediate transfer belt 34).

[0157] In step SP210, the control unit 203 controls the black (K) image forming unit 10K to form, on the intermediate transfer belt 34, a coated toner image PV to be printed on the back surface of the medium M, and then proceeds to the next step SP211.

[0158] In step SP211, the control unit 203 causes the secondary transfer unit 39 to transfer the coated toner image PV from the intermediate transfer belt 34 to the back surface of the medium M, i.e., so as to be superimposed on the existing glossy toner image PS, and proceeds to the next step SP212. In step SP212, the control unit 203 causes the fixing unit 60 to fix the coated toner image PV to the back surface of the medium M, and proceeds to the next step SP213. At this time, on the front surface of the medium M, the fixing unit 60 also applies heat and pressure to the color toner image PL, so that the surface of the color toner image PL is further smoothed.

[0159] In step SP213, the control unit 203 causes the paper discharge unit 70 to transport the medium M along the transport path W and discharge it from the discharge port 76 to the paper discharge tray 2T, then proceeds to the next step SP214, where the decorative medium printing process procedure RT2 ends. As a result, the image forming apparatus 201 can print the color toner image PL on the front side of the medium M and print the glossy toner image PS and the coated toner image PV on the back side, that is, create the decorative medium MC2 (FIG. 11).

[0160] The decoration medium MC2 created in this manner does not require overlaying black paper MK as in the first embodiment, and can provide a visual effect of making the decoration area AC appear and disappear depending on the relative relationship between the user's viewpoint VP, the position of the light source LS, etc., and the position and angle of the decoration medium MC2.

[0161] Furthermore, the image forming apparatus 201 can print the coated toner image PV using black (K) toner by the existing black (K) image forming unit 10K, and can also utilize the re-conveyance unit 66. Therefore, compared to the first embodiment, the image forming apparatus 201 does not need to add parts or change the structure, and can create the decoration medium MC2 by changing the control by the control unit 203.

[0162] In other respects, image forming apparatus 201 according to the second embodiment can achieve the same effects as image forming apparatus 1 according to the first embodiment.

[0163] 3. Third embodiment An image forming apparatus 301 according to the third embodiment is different from the first embodiment in that it has a control unit 303 instead of the control unit 3, but is otherwise configured similarly. This control unit 303 creates (i.e. prints) a decoration medium MC by performing a process that is partially different from that of the control unit 3 according to the first embodiment.

[0164] Specifically, in the third embodiment, instead of the decoration medium MC according to the first embodiment (FIG. 4, etc.), a decoration medium MC3 shown in a schematic cross-sectional view in FIG. 13 is created. This decoration medium MC3 differs from the decoration medium MC according to the first embodiment in that a paper medium MP is used instead of the medium M, and that a correction toner image PR (hereinafter also referred to as a correction image) is printed on the front side of the paper medium MP, and further a glitter toner image PS and a color toner image PL are printed in succession on top of each other.

[0165] Of these, the paper medium MP is so-called high-quality paper, and unlike the medium M used in the first and second embodiments, it does not have the property of transmitting visible light. The corrected toner image PR is formed on the paper medium MP in the same portion as the decorative area AC in the glittering toner image PS using normal color (i.e., non-glittering color) toner. The print duty D of the corrected toner image PR is adjusted to a value equivalent to the difference between the background print duty DB and the decorative print duty DC in the glittering toner image PS (i.e., the duty difference in table TBL1 (FIG. 7)). Incidentally, the corrected toner image PR is composed of cyan (C) toner, just like the color toner image PL.

[0166] Therefore, in the decoration medium MC3, when the corrected toner image PR is printed on the front side of the paper medium MP and the glittering toner image PS is printed on top of it, the surface of the corrected toner image PR can be finished to be generally flat. As a result, in the decoration medium MC3, when the color toner image PL is printed on top of the corrected toner image PR, the surface of the color toner image PL can be finished to be generally flat without forming a step at the boundary between the decoration area AC and the background area AB in the glittering toner image PS.

[0167] In the third embodiment, the image forming apparatus 301 creates a decorative medium MC3 by performing a process that is partially different from that of the first embodiment, based on the control of the control unit 303. Specifically, when the control unit 303 receives print data from the higher-level device 100 (FIG. 3), it starts a decorative medium printing process procedure RT3 shown in FIG. 14, which corresponds to FIG. 10, and proceeds to the first step SP301.

[0168] In step SP301, the control unit 303 causes the first paper feed unit 40 to feed one sheet of paper medium MP from the paper cassette 41 and transport it along the transport path W, similar to step SP1 (FIG. 10) of the decorative medium printing process procedure RT1, and then proceeds to the next step SP302. As a result, the paper medium MP is transported to the secondary transfer unit 39 with its front side facing upward (the side facing the intermediate transfer belt 34).

[0169] In step SP302, the control unit 3 controls the normal color image forming units 10 (10K, 10C, 10M, and 10Y) based on the received print data to form a corrected toner image PR using normal color toners on the intermediate transfer belt 34 (FIGS. 1 and 2) in the same portion as the decorative area AC of the glitter toner image PS, and then proceeds to the next step SP303. At this time, the control unit 303 adjusts the print duty D of the corrected toner image PR to a value equivalent to the difference between the background print duty DB and the decorative print duty DC in the glitter toner image PS.

[0170] In step SP303, the control unit 303 causes the secondary transfer unit 39 to transfer the corrected toner image PR from the intermediate transfer belt 34 to the surface of the paper medium MP, and then proceeds to the next step SP304. In step SP304, the control unit 303 causes the fixing unit 60 to fix the corrected toner image PR on the surface of the paper medium MP, and then proceeds to the next step SP305.

[0171] In step SP305, the control unit 303 causes the re-conveying unit 66 to return the paper medium MP to the conveying path W without turning it over, and conveys it along the conveying path W, and then proceeds to the next step SP306. As a result, the paper medium MP continues to be conveyed to the secondary transfer unit 39 with the front side facing up (the side facing the intermediate transfer belt 34).

[0172] In step SP306, the control unit 303 controls the silver image forming unit 10S based on the received print data to form the glossy toner image PS on the intermediate transfer belt 34, and proceeds to the next step SP307. At this time, the control unit 303 forms the background area AB and the decorative area AC (FIG. 4) on the glossy toner image PS based on the received print data. The control unit 303 also controls the background print duty DB of the background area AB to be 100[%], and the decorative print duty DC of the decorative area AC to be in the range of 62.50[%] or more and 81.25[%] or less.

[0173] In step SP307, the control unit 203 causes the secondary transfer unit 39 to transfer the glossy toner image PS from the intermediate transfer belt 34 to the front side of the paper medium MP, i.e., to be superimposed on the top of the corrected toner image PR, and proceeds to the next step SP308. In step SP308, the control unit 303 causes the fixing unit 60 to fix the glossy toner image PS to the front side of the paper medium MP, and proceeds to the next step SP309. At this time, the surface of the corrected toner image PR becomes approximately flat.

[0174] In step SP309, similar to step SP305, the control unit 303 causes the re-conveying unit 66 to return the paper medium MP to the conveying path W without turning it over, and conveys it along the conveying path W, and then proceeds to the next step SP310. As a result, the paper medium MP continues to be conveyed to the secondary transfer unit 39 with the front side facing up (the side facing the intermediate transfer belt 34).

[0175] In step SP310, the control unit 303 controls the normal color image forming units 10 (10K, 10C, 10M, and 10Y) based on the received printing data to form the color toner image PL to be printed on the front side of the paper medium MP on the intermediate transfer belt 34 (Figures 1 and 2), and then proceeds to the next step SP311.

[0176] In step SP311, the control unit 303 causes the secondary transfer unit 39 to transfer the color toner image PL from the intermediate transfer belt 34 to the front side of the paper medium MP, i.e., to be superimposed on the upper side of the glossy toner image PS, and proceeds to the next step SP312. In step SP312, the control unit 303 causes the fixing unit 60 to fix the color toner image PL to the front side of the paper medium MP, and proceeds to the next step SP313.

[0177] In step SP313, the control unit 303 causes the paper discharge unit 70 to transport the medium M along the transport path W and discharge it from the discharge port 76 to the paper discharge tray 2T, then proceeds to the next step SP314, where the decorative medium printing process procedure RT3 ends. As a result, the image forming apparatus 301 can print the corrected toner image PR, the glitter toner image PS, and the color toner image PL in succession on top of each other on the surface of the paper medium MP, that is, create the decorative medium MC3 (FIG. 13).

[0178] The decorative medium MC3 created in this manner can achieve the same visual effect as the first embodiment while using a paper medium MP, which is general high-quality paper, without using a medium M that has the property of transmitting visible light as in the first embodiment.

[0179] Furthermore, the image forming apparatus 301 can form and print a corrected toner image PR using normal color toner by the normal color image forming unit 10, and can also utilize the re-conveying unit 66. Therefore, compared to the first embodiment, the image forming apparatus 301 does not need to add parts or change the structure, and can create the decoration medium MC3 by changing the control by the control unit 303.

[0180] In other respects, image forming apparatus 301 according to the third embodiment can achieve the same effects as image forming apparatus 1 according to the first embodiment.

[0181] [4. Other embodiments] In the above-mentioned first embodiment, the background print duty DB of the background area AB in the glittering toner image PS is set to 100[%], and the decorative print duty DC of the decorative area AC is set to 62.50[%] or more and 81.25[%] or less, that is, the decorative print duty DC is set lower than the background print duty DB. However, the present invention is not limited to this, and the decorative print duty DC of the decorative area AC may be set higher than the background print duty DB of the background area AB, for example, as in the decorative medium MC11 shown in FIG. 15(A) corresponding to FIG. 4(A). In addition, in the second embodiment, the decorative print duty DC of the decorative area AC may be set higher than the background print duty DB of the background area AB, for example, as in the decorative medium MC12 shown in FIG. 15(B) corresponding to FIG. 11. Furthermore, in the third embodiment, the decorative print duty DC of the decorative area AC may be set higher than the background print duty DB of the background area AB, for example, as in the decorative medium MC13 shown in FIG. 15(C) corresponding to FIG. 13. In this case, the corrected toner image PR may be formed in the same portion as the background area AB, which is an area with a lower print duty.

[0182] In the first embodiment described above, the amount of the glitter toner image PS formed on the medium (amount of adhesion on the paper surface) when the background print duty DB is 100% is set to 0.65 mg / cm 2 However, the present invention is not limited to this. For example, when the background print duty DB is 100%, the amount of the glitter toner image PS formed on the medium is 0.50 to 0.80 mg / cm 2 In this case, the difference in the amount of formation on the medium between the background area AB and the decorative area AC may be set to a value within the range of 0.12 [mg / cm 2 ] or more 0.24[mg / cm 2 ] or less, or the ratio of the amount of the decorative area AC formed on the medium to the amount of the background area AB formed on the medium is set to a range of 0.63 to 0.82. Furthermore, the amount of the color toner image PL (cyan image) printed on the surface of the medium M is also set to 0.45 [mg / cm 2], for example, 0.35 to 0.55 [mg / cm 2 In this case, the same effect can be obtained. The same applies to the second and third embodiments.

[0183] Furthermore, in the above-mentioned first embodiment, the duty difference between the background printing duty DB and the decorative printing duty DC is 18.75[%] or more and 37.50[%] or less, and the range of the ratio of the decorative printing duty DC to the background printing duty DB is 62.50[%] or more and 81.25[%] or less. However, the present invention is not limited to this, and for example, only one of the duty difference between the background printing duty DB and the decorative printing duty DC being 18.75[%] or more and 37.50[%] or less, and the range of the ratio of the decorative printing duty DC to the background printing duty DB being 62.50[%] or more and 81.25[%] or less may be satisfied. Alternatively, for example, a combination may be used in which the difference in 0° reflectance (Y value) between the background region AB and the decorative region AC is 1.53 to 5.79, a combination may be used in which the difference in luminous reflectance difference ΔY is 8 to 14, or a combination may be used in which the reduction rate of the luminous reflectance difference ΔY is 22% to 39%. The same applies to the second and third embodiments.

[0184] Furthermore, in the above-mentioned first embodiment, the print duty D of the glittering toner image PS is set to two levels, the background print duty DB and the decorative print duty DC. However, the present invention is not limited to this, and the print duty D of the glittering toner image PS may be set to three or more levels. The same applies to the second and third embodiments.

[0185] In the above-mentioned first embodiment, the glossy toner image PS of the decoration medium MC (FIG. 4) is formed of a silver toner (silver toner TS). However, the present invention is not limited to this, and the glossy toner image PS may be formed of various glossy toners, such as gold and copper. For example, a gold toner can be manufactured by partially modifying the manufacturing process of the silver toner TS described in the first embodiment. Specifically, when adding aluminum powder as a glossy pigment, a yellow pigment (e.g., CI Pigment Yellow 180, which is an organic pigment), a magenta pigment (e.g., CI Pigment Red 122, which is an organic pigment), a red-orange fluorescent pigment (e.g., FM-34N_Orange (manufactured by Shinroihi Co., Ltd.)), and a yellow fluorescent pigment (FM-35N_Yellow (manufactured by Shinroihi Co., Ltd.)) are added, respectively, to manufacture a gold toner. The luster pigment is not limited to aluminum (Al), and may be any other luster pigment such as pearl pigment (natural mica) and inorganic pigment made of titanium oxide. The same applies to the second and third embodiments.

[0186] Furthermore, in the above-mentioned first embodiment, the color toner image PL of the decoration medium MC (FIG. 4) is described as being formed using cyan (C) toner with a print duty of 100%. However, the present invention is not limited to this, and the color toner image PL may be formed using toner of various colors such as black (K), magenta (M), yellow (Y), white, or a combination of these. In short, it is sufficient that the image is formed using a non-glossy toner. The same applies to the second and third embodiments. The same also applies to the correction toner image PR in the third embodiment.

[0187] Furthermore, in the above-mentioned first embodiment, the image forming apparatus 1 is provided with one image forming unit 10S for forming an image of silver toner, which is a glitter color, and the image forming unit 10S is used to form a glitter toner image PS by making the background print duty DB of the background area AB and the decorative print duty DC of the decorative area AC different from each other. However, the present invention is not limited to this, and for example, the image forming apparatus 1 may be provided with two image forming units 10S for forming an image of silver toner, which is a glitter color. In this case, for example, one image forming unit 10S (hereinafter also referred to as the first glitter image forming unit) may form an image of the background area AB (hereinafter also referred to as the first glitter image), and the other image forming unit 10S (hereinafter also referred to as the second glitter image forming unit) may form an image of the decorative area AC (hereinafter also referred to as the second glitter image). Alternatively, for example, one image forming unit 10S may form an image of the entire range combining the background area AB and the decorative area AC, and the other image forming unit 10S may form only the background area AB by overlapping them.

[0188] In these cases, it is sufficient that the amount of silver toner TS attached per unit area in the glitter toner image PS formed on the medium M is appropriately different between the background region AB and the decorative region AC. Specifically, for example, the degree of exposure per unit area during exposure (i.e., brightness, light amount, etc.) may be different between the two image forming units 10S, the bias voltages during development and transfer may be different, or these may be combined appropriately. Alternatively, the color or characteristics of the glitter color toner may be different between the two image forming units 10S. In this case, for example, as shown in Table TBL1, it is possible to consider a combination in which the difference in 0° reflectance (Y value) between the background region AB and the decorative region AC is 1.53 or more and 5.79 or less, or a combination in which the difference in luminous reflectance difference ΔY is 8 or more and 14 or less. Alternatively, for example, a combination in which the reduction rate of the luminous reflectance difference ΔY is 22[%] or more and 39[%] or less may be used. The same applies to the second and third embodiments.

[0189] Further, in the above-mentioned first embodiment, the temperature during fixing in the fixing unit 60 is constant (for example, 150[°C]), and the temperature when fixing the color toner image PL is equal to the temperature when fixing the glossy toner image PS. However, the present invention is not limited to this, and various temperatures can be used so that the color toner image PL and the glossy toner image PS can be fixed to the medium M. Specifically, for example, the temperature during fixing may be within a range of 145 to 190[°C]. Also, for example, the temperature when fixing the color toner image PL may be set higher than the temperature when fixing the glossy toner image PS. Specifically, for example, the fixing temperature of the glossy toner image PS may be set to 150[°C], and the fixing temperature of the color toner image PL may be set to 190[°C]. This can increase the degree of gloss on the surface of the color toner image PL. The same applies to the second and third embodiments.

[0190] Furthermore, in the above-mentioned first embodiment, as shown in the decorative medium printing process procedure RT1 (FIG. 10), a form has been described in which a color toner image PL is printed on the front surface of the medium M, and then a glossy toner image PS is printed on the rear surface of the medium M. However, the present invention is not limited to this, and for example, a glossy toner image PS may be printed on the rear surface of the medium M, and then a color toner image PL may be printed on the front surface of the medium M. The same applies to the second embodiment.

[0191] Furthermore, in the above-mentioned first embodiment, a form in which a material made of a so-called transparent material with an extremely high visible light transmittance, such as an OHP film, is used as the medium M has been described. However, the present invention is not limited to this, and the medium M may be made of a material made of various colors or colored, such as a so-called color film, or may be made of a material that is slightly inferior in visible light transmittance to an OHP film and is described as "semi-transparent", such as tracing paper. In short, any paper-like material that has the property of transmitting at least a part of visible light can be used as the medium M. The same applies to the second embodiment. In the third embodiment, the paper medium MP may be made of various materials to which a toner image can be transferred and fixed.

[0192] Furthermore, in the second embodiment described above, a form has been described in which the printing duty D is constant for all portions of the coated toner image PV superimposed on the glossy toner image PS in the decorative medium MC2 (FIG. 11). However, the present invention is not limited to this, and for example, as in the decorative medium MC21 shown in FIG. 16(A) corresponding to FIG. 11, the printing duty D of the decorative area AC in the coated toner image PV may be made higher than the printing duty D of the background area AB. Furthermore, when the decorative printing duty DC of the decorative area AC is made higher than the background printing duty DB of the background area AB as in the decorative medium MC12 shown in FIG. 15(B), the printing duty D of the background area AB in the coated toner image PV may be made higher than the printing duty D of the decorative area AC as in the decorative medium MC22 shown in FIG. 16(B). In these cases, the back surface of the coated toner image PV can be made flat, and the formation of steps in the coated toner image PV at the boundary between the background area AB and the decorative area AC can be avoided, so that when a user visually inspects the back surface of the decorative medium MC21, etc., the shape of the decorative area AC can be prevented from being recognized.

[0193] Furthermore, in the above-mentioned second embodiment, the coated toner image PV is described as being composed of black toner TK. However, the present invention is not limited to this, and may be composed of process black, for example, a mixture (i.e., a mixture) of cyan (C), magenta (M) and yellow (Y) toners T. Also, the color is not limited to black, and may be other colors composed of mixed colors or other colors such as white, which are toners themselves. In this case, any color or amount of adhesion per unit area that has properties of blocking visible light as much as possible may be used. Furthermore, when the coated toner image PV is fixed by the fixing unit 60 (FIG. 1) of the image forming apparatus 1, the fixing temperature may be controlled to be lower than normal, thereby intentionally reducing the transmittance of visible light.

[0194] Furthermore, in the above-mentioned second embodiment, the fixing temperature in the fixing unit 60 is constant (for example, 150° C.) in all of the first fixing process for fixing the color toner image PL to the front surface of the medium M, the second fixing process for fixing the glitter toner image PS to the rear surface of the medium M, and the third fixing process for fixing the coated toner image PV to the rear surface of the medium M. However, the present invention is not limited to this, and the fixing temperature in the third fixing process may be lower than the fixing temperatures in the first and second fixing processes, for example, to 140° C. This can reduce the smoothness of the surface of the coated toner image PV and reduce its transparency, thereby improving the effect of the coating. In addition, in a state in which the color toner image PL and the glitter toner image PS are transferred to the front surface of the medium M in an overlapping manner, both images may be fixed together in one fixing process.

[0195] Furthermore, in the above-mentioned third embodiment, as shown in the decorative medium printing process procedure RT3 (FIG. 14), the correction toner image PR, the glitter toner image PS, and the color toner image PL are formed separately, and then transferred and fixed, respectively. However, the present invention is not limited to this. For example, the correction toner image PR and the glitter toner image PS may be formed together on the intermediate transfer belt 34 and then transferred and fixed together, or the glitter toner image PS and the color toner image PL may be formed together on the intermediate transfer belt 34 and then transferred and fixed together. In these cases, a combination that allows superposition may be adopted according to the order of arrangement of the image forming units 10 of each color in the front-rear direction in the image forming apparatus 1 (FIG. 1) and the running direction of the intermediate transfer belt 34. The same applies to the glitter toner image PS and the coated toner image PV in the second embodiment.

[0196] Furthermore, in the above-described first embodiment, a configuration has been described in which the image forming apparatus 1 (FIG. 1) is provided with a re-conveying unit 66, and after a color toner image PL is formed and fixed on the front surface of the medium M, the medium M is turned over by the re-conveying unit 66 and returned to the conveying path W, and a glossy toner image PS is formed and fixed on the rear surface of the medium M. However, the present invention is not limited to this. For example, the re-conveying unit 66 may be omitted from the image forming apparatus 1, and after a color toner image PL is formed and fixed on the front surface of the medium M, the medium M may be discharged from the discharge port 76 to the discharge tray 2T by the paper discharge unit 70. In this case, the glossy toner image PS can be printed on the rear surface of the medium M by having the user turn the medium M over and set it again in the paper cassette 41 or paper tray 51. In this case, for example, at the stage where the color toner image PL is printed on the front side of the medium M, a message such as "Please turn the medium over and set it in the paper cassette" may be displayed on the display unit 4 to prompt the user to turn the medium M over and set it in the paper cassette 41 etc. The same applies to the second and third embodiments.

[0197] Furthermore, in the above-mentioned first embodiment, the image forming apparatus 1 (FIG. 1) is described as being provided with five image forming units 10. However, the present invention is not limited to this, and the image forming apparatus 1 may be provided with four or less image forming units 10 or six or more image forming units 10. The same applies to the second and third embodiments.

[0198] Furthermore, in the above-described first embodiment, the image forming apparatus (FIG. 1) is of a so-called intermediate transfer type, and a toner image formed in each image forming unit 10 is primarily transferred to the intermediate transfer belt 34, and the toner image is secondarily transferred from the intermediate transfer belt 34 to the medium M. However, the present invention is not limited to this, and for example, the image forming apparatus may be of a so-called direct transfer type, and the toner image formed in each image forming unit 10 may be directly transferred to the medium M. The same applies to the second and third embodiments.

[0199] Furthermore, in the above-mentioned embodiment, the present invention has been described as being applied to an image forming apparatus 1 that forms an image using a developer used in a one-component development method. However, the present invention is not limited to this, and the present invention may also be applied to an image forming apparatus that forms an image using a developer used in a two-component development method in which a carrier and a toner are mixed and an appropriate amount of charge is imparted to the toner by utilizing friction between the carrier and the toner. When describing the two-component development method, particles containing a glittering pigment, a binder resin, and an external additive, or a powdery material in which these particles are aggregated, are defined as glittering toner or glittering developer. The same applies to the second and third embodiments.

[0200] Furthermore, in the above-mentioned first embodiment, the present invention has been described as being applied to the image forming apparatus 1 which is a single-function printer. However, the present invention is not limited to this, and may be applied to image forming apparatuses having various other functions, such as an MFP (Multi Function Peripheral) having the functions of a copier or facsimile machine. The same applies to the second and third embodiments.

[0201] Furthermore, the present invention is not limited to the above-mentioned embodiments and other embodiments. That is, the scope of application of the present invention extends to embodiments in which the above-mentioned embodiments and the other embodiments are combined in part or in whole in any manner. The scope of application of the present invention also extends to embodiments in which a part of the configuration described in any of the above-mentioned embodiments and other embodiments is extracted and replaced or diverted with a part of the configuration of any of the above-mentioned embodiments and other embodiments, or an embodiment in which a part of the extracted configuration is added to any of the embodiments.

[0202] Furthermore, in the above-mentioned first embodiment, the image forming apparatus 1 is configured as an image forming apparatus by the image forming unit 10C as a non-glossy image forming section, the image forming unit 10S as a glossy image forming section, and the control section 3 as a control section. However, the present invention is not limited to this, and the image forming apparatus may be configured by a non-glossy image forming section, a glossy image forming section, and a control section having various other configurations. [Industrial Applicability]

[0203] The present invention can be used in the case where an image is formed on a medium by electrophotography using a developer containing a metal pigment. [Explanation of symbols]

[0204] 1, 201, 301: image forming apparatus; 3, 203, 303: control unit; 4: display unit; 10: image forming unit; 14: LED head; 24: developing roller; 26: photoconductor drum; 35: primary transfer roller; 36: secondary transfer roller; 39: secondary transfer unit; 41: paper cassette; 51: paper tray; 60: fixing unit; 66: re-transport unit; 80: print control unit; 81: memory unit; 95: normal color data conversion table; 96: glitter color data conversion table; 100: host device; AB...background area, AC...decoration area, D...printing duty, DC...decoration printing duty, LS...light source, M...medium, MC...decoration medium, ME...evaluation medium, PE...evaluation image, PL...color toner image, PR...corrected toner image, PS...glossy toner image, PV...coated toner image, T...toner, TK...black toner, TL...color toner, TS...silver toner, VP...viewpoint, W...transport path, Y...visual reflectance, Z...re-transport path, ΔY...visual reflectance difference.

Claims

1. a non-glossy image forming unit capable of forming a non-glossy image using a non-glossy developer on a medium that transmits at least a part of visible light; a glitter image forming unit capable of forming a glitter image on the medium using a glitter developer; a control unit that controls the non-glossy image forming unit and the glossy image forming unit in accordance with print data; Equipped with The control unit is The non-glossy image is formed on a first surface of the medium by the non-glossy image forming unit, and the glossy image having a first region and a second region is formed on a second surface, which is an opposite surface of the first surface, by the glossy image forming unit; In the first region and the second region, adhesion rates of the amount of the glitter developer per unit area of ​​the medium expressed as a ratio of the area are defined as a first adhesion rate and a second adhesion rate, respectively; The difference between the first adhesion rate and the second adhesion rate is controlled to be equal to or greater than 18.75% and equal to or less than 37.50%.

1. An image forming apparatus comprising:

2. The control unit controls the first adhesion rate and the second adhesion rate so that a difference between the luminous reflectance of the first region and the luminous reflectance of the second region of the glossy image is 1.53% or more and 5.79% or less.

2. The image forming apparatus according to claim 1,

3. The control unit causes the non-glossy image forming unit to form a covering image using the non-glossy developer on the second surface of the medium, the covering image being superimposed on the non-glossy image.

2. The image forming apparatus according to claim 1,

4. The control unit forms the coating image using the non-glossy developer in black or white.

4. The image forming apparatus according to claim 3.

5. a fixing section for fixing the non-glossy image and the glossy image formed on the medium onto the medium at a fixing temperature based on the control of the control section; Further comprising: The control unit controls the fixing temperature to be lower when fixing the covering image than when fixing the non-glossy image or the glossy image.

5. The image forming apparatus according to claim 4.

6. A fixing section that fixes the non-glossy image and the glossy image formed on the medium on the basis of the control of the control section. Further comprising: The control unit controls the non-glossy image forming unit to form the non-glossy image on the first surface of the medium, the fixing unit to fix the non-glossy image on the medium, and then the glossy image forming unit to form the glossy image on the second surface of the medium, and the fixing unit to fix the glossy image on the medium.

2. The image forming apparatus according to claim 1,

7. the glossy image forming unit forms an electrostatic latent image by exposing an image carrier by an exposure unit, and develops the electrostatic latent image by the glossy developer to form the glossy image; The control unit causes the degree of exposure per unit area to differ between the first region and the second region when the glossy image forming unit forms the glossy image.

2. The image forming apparatus according to claim 1,

8. The glossy image forming unit is a first glossy image forming unit that forms a first glossy image on the second surface of the medium at a predetermined adhesion ratio; a second glossy image forming unit that forms a second glossy image on the second surface of the medium, the second glossy image having a different adhesion ratio from that of the first glossy image; having The control unit controls the first glossy image forming unit and the second glossy image forming unit to combine the first glossy image and the second glossy image to form the glossy image.

2. The image forming apparatus according to claim 1,

9. The control unit causes the first glossy image forming unit to form the first region of the glossy image, and causes the second glossy image forming unit to form the second region of the glossy image.

9. The image forming apparatus according to claim 8,

10. The control unit causes the first glossy image forming unit to form the first region and the second region of the glossy image, and causes the second glossy image forming unit to form the first region of the glossy image in an overlapping manner.

9. The image forming apparatus according to claim 8,

11. The control unit controls a bias voltage applied when the glittering developer is developed in the first glittering image forming unit and a bias voltage applied when the glittering developer is developed in the second glittering image forming unit to be different from each other.

9. The image forming apparatus according to claim 8,

12. The control unit controls the degree of exposure per unit area when the exposure process is performed in the first glossy image forming unit to be different from the degree of exposure per unit area when the exposure process is performed in the second glossy image forming unit.

9. The image forming apparatus according to claim 8,

13. a non-glossy image forming step of forming a non-glossy image using a non-glossy developer on a first surface of a medium that transmits at least a portion of visible light by a non-glossy image forming unit; a glitter image forming step of forming a glitter image having a first region and a second region by a glitter image forming unit on a second surface of the medium, the second surface being the opposite surface to the first surface, using a glitter developer, before or after the non-glitter image forming step; having In the glitter image forming step, when adhesion rates of the glitter developer per unit area of ​​the medium in the first region and the second region are expressed as a ratio of the area to a first adhesion rate and a second adhesion rate, respectively, a difference between the first adhesion rate and the second adhesion rate is set to 18.75% or more and 37.50% or less.

1. An image forming method comprising:

14. a first image forming unit capable of forming a first image using a non-glossy developer on a medium that transmits at least a portion of visible light; a second image forming section capable of forming a second image on the medium using a glitter developer; a control unit that controls the first image forming unit and the second image forming unit in response to print data; Equipped with The control unit is forming the first image on a first surface of the medium by the first image forming unit, and forming the second image having a first region and a second region on a second surface, which is an opposite surface of the first surface, by the second image forming unit; In the first region and the second region, adhesion rates of the amount of the glitter developer per unit area of ​​the medium expressed as a ratio of the area are defined as a first adhesion rate and a second adhesion rate, respectively; The ratio of the second adhesion rate to the first adhesion rate is controlled to be equal to or greater than 62.50% and equal to or less than 81.25%.

1. An image forming apparatus comprising:

15. a non-glossy image forming step of forming a non-glossy image using a non-glossy developer on a first surface of a medium that transmits at least a portion of visible light by a non-glossy image forming unit; a glitter image forming step of forming a glitter image having a first region and a second region by a glitter image forming unit on a second surface of the medium, the second surface being the opposite surface to the first surface, using a glitter developer, before or after the non-glitter image forming step; having In the glitter image forming step, when adhesion rates of the glitter developer per unit area of ​​the medium in the first region and the second region are expressed by an area ratio as a first adhesion rate and a second adhesion rate, respectively, a ratio of the second adhesion rate to the first adhesion rate is set to 62.50% or more and 81.25% or less.

1. An image forming method comprising:

16. a non-glossy image forming unit capable of forming a non-glossy image and a correction image on a medium using a non-glossy developer; a glitter image forming unit capable of forming a glitter image on the medium using a glitter developer; a control unit that controls the non-glossy image forming unit and the glossy image forming unit in accordance with print data; Equipped with The control unit is The non-glossy image forming unit forms the correction image in a second region excluding the first region on the surface of the medium, the glossy image forming unit forms the glossy image having the first region and the second region on the medium by superimposing the correction image, and the non-glossy image forming unit forms the non-glossy image by superimposing the glossy image on the medium, In the first region and the second region, adhesion rates of the amount of the glitter developer per unit area of ​​the medium expressed as a ratio of the area are defined as a first adhesion rate and a second adhesion rate, respectively; A difference between the first adhesion rate and the second adhesion rate is controlled to be equal to or greater than 18.75% and equal to or less than 37.50%; The adhesion ratio of the corrected image is controlled to be equal to the difference.

1. An image forming apparatus comprising:

Images