Image forming apparatus and image forming method

Abstract

To achieve a good visual effect. [Solution] An image forming apparatus 1 creates a decorative medium MC1 by sequentially superimposing and printing a lower color toner image PNL, a silver toner image PS having a background area AB and a decorative area AC, a transparent toner image PC, and an upper color toner image PNU on the surface of a blank medium M. As a result, the decorative medium MC1 can reduce the rate at which a portion of light transmits from the back side of the medium M compared to when the lower color toner image PNL is omitted, making the decorative area AC less visible. This allows the image forming apparatus 1 to create a good visual effect in which the decorative area AC appears and disappears on the surface of the decorative medium MC1 when the relative positions and angles of the observer's viewpoint VP, light source LS, and decorative medium MC1 are changed in various ways.

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and an image forming method, and is particularly suitable for applications such as forming images with special visual effects using bright colors on a medium. [Background technology]

[0002] Conventionally, electrophotographic printers, which use toner as an image-forming agent to form (i.e., print) images on a medium such as paper, have been widely used as image-forming devices. In these image-forming devices, when performing color printing, toners such as black, magenta, cyan, and yellow (hereinafter collectively referred to as normal colors) are combined (hereinafter referred to as normal color toners or normal color image-forming agents) to form color images in normal colors on a medium such as paper. In addition, some image-forming devices can form glossy images on paper by using glossy toners such as silver and gold (hereinafter also referred to as glossy colors) in addition to these normal colors (hereinafter referred to as glossy toners or glossy image-forming agents).

[0003] Furthermore, an image forming apparatus has been proposed that creates (i.e., prints) an image with a visual effect where the image appears and disappears by superimposing a normal-color image using a normal-color image agent onto a luminous image using a luminous image agent (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-82517 (Figures 2 and 3) Summary of the Invention [Problem to be solved by the invention]

[0005] However, in an image printed by the image forming apparatus described above, there are areas where the glitter developer is applied and areas where it is not. Therefore, in a medium that has undergone a printing process 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 developer that constitutes the normal color image. As a result, there is a difference in glossiness in each area on this medium, which can make the image visible against one's will, resulting in an insufficient visual effect.

[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 is provided with a color image forming unit capable of forming color images using a color developer, a glossy image forming unit capable of forming glossy images using a glossy developer, and a control unit that controls the glossy image forming unit and the color image forming unit according to print data, and the printed matter formed based on the control of the control unit has a first image, which is a color image, formed on a medium, a second image, which is a glossy image having a first region formed with a first formation amount per unit area and a second region formed with a second formation amount per unit area that is smaller than the first formation amount, formed on the first image, and a third image, which is a color image, formed on the second image.

[0008] Furthermore, the image forming apparatus of the present invention includes a colored image forming unit capable of forming a colored image using a colored imaging agent, a glossy image forming unit capable of forming a glossy image using a glossy imaging agent, and a control unit that controls the glossy image forming unit and the colored image forming unit according to the print data. The control unit controls the colored image forming unit to form a first image which is a colored image, the glossy image forming unit to form a second image which is a glossy image having a first region formed with a first forming amount per unit area and a second region formed with a second forming amount smaller than the first forming amount per unit area, on top of the first image, and the colored image forming unit to form a third image which is a colored image on top of the second image, thereby obtaining a printed product.

[0009] Furthermore, the image forming method of the present invention includes the steps of: forming a third image, which is a colored image, on an intermediate transfer member using a colored image forming unit capable of forming a colored image using a colored imaging agent; forming a second image, which is a luminous image, on the first image using a luminous image forming unit capable of forming a luminous image using a luminous imaging agent, having a first region formed with a first forming amount per unit area and a second region formed with a second forming amount smaller than the first forming amount per unit area; forming a first image, which is a colored image, on the second image using a colored image forming unit; and transferring the third image, the second image, and the first image superimposed from the intermediate transfer member onto a medium.

[0010] In this invention, since a first image, which is a colored image, is placed between a second image, which is a luminous image, and the medium, even if the medium has the property of transmitting visible light to some extent, the light that would reach the second image through the medium can be effectively blocked by the first image. As a result, in this invention, when an observer views the medium on which the first, second, and third images are formed from various angles, it is possible to avoid situations where the first and second regions are always distinguishable or always indistinguishable, and to switch between a state where the first and second regions are distinguishable and a state where they are not. [Effects of the Invention]

[0011] According to the present invention, an image forming apparatus and an image forming method capable of achieving good visual effects can be realized. [Brief explanation of the drawings]

[0012] [Figure 1] This is a schematic diagram showing the configuration of an image forming apparatus. [Figure 2] This is a schematic diagram showing the configuration of the image forming unit. [Figure 3] This is a schematic block diagram showing the circuit configuration of an image forming apparatus. [Figure 4] This is a schematic diagram showing the configuration of the decorative medium according to the first embodiment. [Figure 5] This is a simplified diagram illustrating how visual effects appear. [Figure 6] This is a simplified diagram illustrating the principle behind the appearance of visual effects. [Figure 7] This is a schematic diagram showing the configuration of the evaluation medium and the comparison medium. [Figure 8] This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the first embodiment. [Figure 9] This table shows the printing duty cycle, measurement results, and judgment results for each part in each comparative example according to the first embodiment. [Figure 10] This is a simplified diagram illustrating the process of visual recognition. [Figure 11] This graph shows the relationship between transmittance and color difference in the first embodiment. [Figure 12] This is a flowchart showing the printing process procedure for a decorative medium according to the first embodiment. [Figure 13] This is a schematic diagram showing the configuration of the decorative medium according to the second embodiment. [Figure 14] This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the second embodiment. [Figure 15] This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the second embodiment. [Figure 16]This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the second embodiment. [Figure 17] This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the second embodiment. [Figure 18] This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the second embodiment. [Figure 19] This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the second embodiment. [Figure 20] This table shows the printing duty cycle, measurement results, and judgment results for each part in each embodiment according to the second embodiment. [Figure 21] 10 is a graph showing the relationship between transmittance and color difference in the second embodiment. [Figure 22] 13 is a table showing the print duty, measurement results, and judgment results of each part in each comparative example and example according to the third embodiment. [Figure 23] 13 is a table showing the print duty, measurement results, and judgment results of each part in each example according to the third embodiment. [Figure 24] 13 is a table showing the print duty, measurement results, and judgment results of each part in each example according to the third embodiment. [Figure 25] 13 is a table showing the print duty, measurement results, and judgment results of each part in each example according to the third embodiment. [Figure 26] 10 is a graph showing the relationship between transmittance and color difference in the second and third embodiments. [Figure 27] 11 is a flowchart showing a procedure for a decorative medium printing process according to a third embodiment. [Figure 28] 10A and 10B are schematic diagrams illustrating the configuration of a decorating medium according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[0014] 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 a document or a communication function using a telephone line, and is a single-function SFP (Single Function Printer) that has only a printer function.

[0015] Various components are arranged inside a roughly box-shaped housing 2 of the image forming apparatus 1. In the following description, the right end portion in Fig. 1 is defined 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.

[0016] The image forming apparatus 1 is controlled overall by a control unit 3. As will be described later, this control unit 3 executes various processes by reading and executing predetermined programs. The control unit 3 is also connected wirelessly or by wire to a host device 100 (FIG. 3) such as a computer device, and when image data representing an image to be printed is provided from the host device and an instruction to print the image data is given, the control unit 3 executes a printing process to form a print image on the surface of a medium M.

[0017] The display operation unit 4 is a touch panel that combines a display device such as a liquid crystal panel with an operation device such as a touch sensor, and is disposed on the front side of the top surface of the housing 2. The display operation unit 4 displays various information under the control of the control unit 3, and also receives operation inputs from the user and notifies the control unit 3 of the inputs.

[0018] Five image forming units 10K, 10C, 10M, 10CL, and 10SL 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, 10CL, and 10SL correspond to the colors black (K), cyan (C), magenta (M), transparent (CL: clear), and silver (SL: silver), respectively, but are all configured similarly and only differ in color.

[0019] Black (K), cyan (C), and magenta (M) are all colors used in general color printers and are different from the brilliant colors and transparent colors described below. Hereinafter, these colors will also be referred to as normal colors. Note that in this embodiment, yellow (Y), which is used in general color printers, is not used.

[0020] Silver (SL) is a color that has a metallic luster, i.e., a brilliance, and is a special color that is different from normal colors. Hereinafter, such colors will also be referred to as brilliance colors. This silver (SL) can be used alone or layered on normal colors.

[0021] Transparent colors (CL) are transparent colors that have the property of transmitting at least a portion of visible light (i.e., transparency), and are special colors that differ from normal colors. Hereinafter, such colors will also be referred to as translucent colors. These transparent colors (CL) can be used alone or layered on normal colors or brilliant colors.

[0022] For convenience of explanation, image forming units 10K, 10C, 10M, 10CL, and 10SL will hereinafter be collectively referred to as image forming units 10 or image forming sections. Also, hereinafter, image forming unit 10SL corresponding to brilliant colors will be referred to as brilliant image forming sections, image forming unit 10CL corresponding to transparent colors (CL) will be referred to as transparent image forming sections, and image forming units 10K, 10C, and 10M corresponding to normal colors (i.e., colors that are neither brilliant colors nor transparent colors) will be referred to as color image forming sections.

[0023] 2, the image forming unit 10 is broadly 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 or a developer) therein, and is configured to be detachable from the image forming unit 10. When the toner container 12 is installed in 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.

[0024] As described below, silver toner T uses a toner containing a glitter pigment. For convenience of explanation, hereinafter, glitter silver (SL) toner T will be referred to as silver toner TSL, silver toner, glitter toner, or glitter developer. Transparent toner T uses a toner containing a specific resin material. For convenience of explanation, hereinafter, transparent (CL) toner T, which has transparency that allows at least a portion of visible light to pass through, will be referred to as transparent toner TCL, transparent toner, or transparent developer. Regarding transparent toner TCL, a transparent developer is defined as one that does not contain inorganic pigments such as aluminum pigments or organic pigments. Since some resin materials used as binder resins in this transparent developer are slightly yellow, a fluorescent brightener may be added to increase whiteness.

[0025] On the other hand, magenta, cyan, and black toners T are toners containing organic pigments, such as pigment cyan, pigment magenta, and carbon black. For convenience of explanation, hereinafter, toners T having normal colors, rather than brilliant colors or transparent colors, such as magenta, cyan, and black, will also be referred to as color toners TNL, color toners, color developers, or color image developers.

[0026] 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. Of 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.

[0027] 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 on their circumferential side, the elastic layer being made of a conductive urethane rubber foam or the like. The developing roller 24 has an elastic layer and a conductive surface layer formed on its circumferential side. The developing blade 25 is made of, for example, a stainless steel plate of a predetermined thickness, and a portion of it abuts against the circumferential side of the developing roller 24 in a state where it is slightly elastically deformed.

[0028] The photosensitive 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 circumferential surface, enabling it to be charged. The charging roller 27 has a conductive elastic body coated on its circumferential surface, which is in contact with the circumferential surface of the photosensitive drum 26. The cleaning blade 28 is made of, for example, a thin resin plate, and a portion of it is in contact with the circumferential surface of the photosensitive drum 26 while being slightly elastically deformed.

[0029] The LED head 14, which serves as an exposure unit, is located above the photosensitive 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).

[0030] The image forming main body 11 receives a driving force from a motor (not shown) to rotate the first supply roller 22, the second supply roller 23, the developing roller 24, and the charging roller 27 in the direction of arrow R1 (clockwise in the figure), and rotates the photosensitive drum 26 in the direction of arrow R2 (counterclockwise in the figure). 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.

[0031] 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 surfaces, and then rotate to cause the toner T to adhere to the circumferential surface of the developing roller 24. The developing roller 24 has excess toner T removed from the circumferential surface by the developing blade 25, and with the toner T adhering in the form of a thin film, the circumferential surface is brought into contact with the circumferential surface of the photosensitive drum 26.

[0032] Meanwhile, the charging roller 27, in a charged state, contacts the photosensitive drum 26, thereby uniformly charging the circumferential surface of the photosensitive drum 26. The LED head 14 sequentially exposes the photosensitive drum 26 by performing an exposure process in which it emits light at predetermined time intervals in an 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 surface of the photosensitive drum 26 near its upper end.

[0033] Next, the photosensitive drum 26 rotates in the direction of arrow R2, 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 circumferential surface of the photosensitive drum 26 based on the electrostatic latent image, and a toner image P based on the image data is developed. The photosensitive drum 26 further rotates in the direction of arrow R2, causing the toner image P to reach the vicinity of the bottom end of the photosensitive drum 26.

[0034] For convenience of explanation, hereinafter, a toner image P formed with a shiny silver toner TSL will be referred to as a silver toner image PS, a shiny toner image, or a shiny image, and a toner image P formed with a transparent toner TCL will be referred to as a transparent toner image PC, a transparent color toner image, or a transparent image. Also, hereinafter, a toner image P formed with a normal color (i.e., colored) color toner TNL will be referred to as a color toner image, a normal color image, or a color image.

[0035] 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 rollers 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.

[0036] The drive roller 31 is disposed below and rearward of the image forming unit 10SL, and rotates in the direction of 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 photosensitive 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.

[0037] The intermediate transfer belt 34, which serves as an intermediate transfer member, is constructed as an endless belt from a high-resistance plastic film and is stretched around the drive roller 31, the driven roller 32, and the backup roller 33. Furthermore, in the intermediate transfer section 30, five primary transfer rollers 35 are positioned below the portion of the intermediate transfer belt 34 stretched between the drive roller 31 and the driven roller 32, that is, directly below each of the five image forming units 10, and facing each photoreceptor drum 26 across the intermediate transfer belt 34. A predetermined bias voltage is applied to these primary transfer rollers 35 based on the control of the control unit 3.

[0038] The secondary transfer roller 36 is located directly below the backup roller 33 and is biased toward the backup roller 33. In other words, the intermediate transfer section 30 sandwiches the intermediate transfer belt 34 between the secondary transfer roller 36 and the backup roller 33. A predetermined bias voltage is also 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 section 39.

[0039] The reverse-bending roller 37 is positioned slightly below the front of the drive roller 31 and slightly behind the upper side of the backup roller 33, biasing the intermediate transfer belt 34 in the forward and upward direction. As a result, the intermediate transfer belt 34 maintains tension between each roller without any slack. In addition, a reverse-bending backup roller 38 is provided at a position above the front of the reverse-bending roller 37, sandwiching the intermediate transfer belt 34.

[0040] The intermediate transfer unit 30 rotates the drive roller 31 in the direction of arrow R1 using driving force supplied from a belt motor (not shown), thereby causing the intermediate transfer belt 34 to travel in the direction of arrow E1. Each primary transfer roller 35 also rotates in the direction of arrow R1 while a predetermined bias voltage is applied. As a result, each image forming unit 10 transfers the toner image P that had reached near the lower end of the peripheral surface of the photoreceptor drum 26 (Figure 2) to the intermediate transfer belt 34, and sequentially superimposes the toner images P of each color. At this time, the toner images P of each color are superimposed on the surface of the intermediate transfer belt 34 in order from the upstream silver (SL). By moving this intermediate transfer belt 34, the intermediate transfer unit 30 brings the toner images P transferred from each image forming unit 10 to the vicinity of the backup roller 33.

[0041] Incidentally, a transport path W is formed inside the housing 2 (Figure 1) for transporting the medium M. This transport path W starts from the lower front end of the housing 2, moves forward and upward, makes about a half-turn, and then proceeds backward along the underside of the intermediate transfer section 30. Subsequently, the transport path W moves upward, proceeds upward along the rearside of the intermediate transfer section 30 and the image forming unit 10SL, and then moves forward. In other words, the transport path W is formed to resemble the capital letter "S" in Figure 1. Various components are arranged inside the housing 2 along this transport path W.

[0042] A first paper feeding section 40 is located near the lower end inside the housing 2 (Figure 1). The first paper feeding section 40 is equipped with 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, feed roller 43, retard roller 44, and transport roller pairs 46, 47, and 48 are all formed in a cylindrical shape with their central axis aligned in the left-right direction.

[0043] The paper cassette 41 is configured in the shape of a hollow rectangular parallelepiped and is detachable from the housing 2. The paper cassette 41 stores the medium M in a stacked state, i.e., in a piled state, with the paper surface facing up and down. In this embodiment, the medium M is white high-quality paper.

[0044] The pickup roller 42 is in contact with the vicinity of the front end of the uppermost surface of the media M stored in the paper cassette 41. The feed roller 43 is positioned slightly in front of the pickup roller 42. The retard roller 44 is located below the feed roller 43, forming a gap between it and the feed roller 43 that corresponds to the thickness of one sheet of media M.

[0045] When the first paper feeding unit 40 receives driving force from a paper feeding motor (not shown), it rotates or stops the pickup roller 42, feed roller 43, and retard roller 44 as appropriate. As a result, the pickup roller 42 feeds forward one or more of the top sheets of media M stored in the paper cassette 41. The feed roller 43 and retard roller 44 feed the top sheet of media M further forward while blocking the second and subsequent sheets. In this way, the first paper feeding unit 40 feeds the media M forward, separating them one sheet at a time.

[0046] The transport guide 45 is positioned in the front lower part of the transport path W, and moves the medium M forward and upward along this transport path W, and then further backward and upward. The transport roller pairs 46 and 47 are positioned near the center and near the upper end of the transport guide 45, respectively, and are driven by a paper feed motor (not shown) to rotate in a predetermined direction. As a result, the transport roller pairs 46 and 47 move the medium M along the transport path W.

[0047] A second paper feed unit 50 is provided in front of the pair of transport rollers 47 in the housing 2. The second paper feed unit 50 is provided with a paper tray 51, a pickup roller 52, a feed roller 53, a retard roller 54, and the like. The paper tray 51 is formed in the shape of a thin plate extending vertically, and is designed to accommodate medium M2 on its upper side. Incidentally, medium M2, which may be different in size and paper quality from medium M stored in paper cassette 41, for example, is placed on the paper tray 51.

[0048] The pickup roller 52, feed roller 53, and retard roller 54 are configured similarly to the pickup roller 42, feed roller 43, and retard roller 44 of the first paper supply unit 40. When a driving force is supplied from a paper supply motor (not shown), the second paper supply unit 50 appropriately rotates or stops the pickup roller 52, feed roller 53, and retard roller 54 to feed the bottommost sheet of medium M2 on the paper tray 51 rearward while blocking the second and subsequent sheets. In this way, the second paper supply unit 50 separates the medium M2 sheet by sheet and feeds it rearward. The fed medium M2 is then transported along the transport path W by the transport roller pair 57 in the same manner as medium M. For convenience of explanation, medium M2 will hereinafter be referred to simply as medium M without distinguishing it from medium M.

[0049] The rotation of the conveying roller pair 47 is appropriately restricted, and by applying a frictional force to the medium M, it corrects the inclination of the sides of the medium M relative to the direction of travel, i.e., so-called skew, and sends the medium M rearward after aligning the leading and trailing edges. The conveying roller pair 48 is located a predetermined distance rearward from the conveying roller pair 47, and rotates in the same manner as the conveying roller pair 46, etc., to supply a driving force to the medium M being conveyed along the conveying path W, causing the medium M to move further rearward along the conveying path W.

[0050] The secondary transfer section 39 of the intermediate transfer unit 30, i.e., the backup roller 33 and the secondary transfer roller 36, is disposed behind the pair of conveying rollers 48. At this secondary transfer section 39, the toner image P 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 P from the intermediate transfer belt 34 onto the medium M conveyed along the conveying path W, and then causes the medium M to proceed further rearward.

[0051] 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, which are disposed opposite each other with the transport path W in between. The heating unit 61 has a heater that generates heat, multiple 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 its central axis aligned in the left-right direction, and presses its upper surface against the lower surface of the heating unit 61 to form a nip.

[0052] 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 cause the heating belt to run and rotate in the direction of arrow R1, and rotates the pressure unit 62 in the direction of arrow R2. Then, when the fixing unit 60 receives the medium M onto which the toner image P 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 P to the medium M, and then sends it out rearward.

[0053] A pair of conveying rollers 64 is disposed behind the fixing unit 60, and a switching unit 65 is disposed behind the pair of conveying rollers 64. The switching unit 65 switches the traveling direction of the medium M to either upward or downward in accordance with 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 conveying guide 71 that guides the medium M upward along the conveying path W, pairs of conveying rollers 72, 73, 74, and 75 that face each other across the conveying path W, and a discharge port 76.

[0054] Furthermore, a re-transport section 66 is positioned below the switching section 65, the fixing section 60, and the secondary transfer section 39. The re-transport section 66 has transport guides and transport roller pairs (not shown) that constitute the re-transport path Z. The re-transport path Z starts from below the switching section 65, moves downwards, then proceeds forward, and merges with the transport path W downstream of the transport roller pair 57.

[0055] When the control unit 3 discharges the medium M, the switching unit 65 switches the direction of travel of the medium M towards the upper paper discharge unit 70. The paper discharge unit 70 transports the medium M received from the switching unit 65 upward and discharges it from the discharge port 76 to the paper discharge tray 2T. When the control unit 3 returns the medium M with its front and back sides reversed, the switching unit 65 switches the direction of travel of the medium M towards the lower re-transport unit 66. The re-transport unit 66 transports the medium M received from the switching unit 65 to the re-transport path Z, and eventually reaches the downstream side of the transport roller pair 57, so that the medium M is 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 its paper surface reversed, and perform so-called double-sided printing.

[0056] In this way, the image forming apparatus 1 forms a toner image P using toner T in the image forming unit 10 and transfers it to the intermediate transfer belt 34, transfers the toner image P from the intermediate transfer belt 34 to the medium M in the secondary transfer unit 39, and then fixes it in the fixing unit 60, thereby printing an image on the medium M, that is, forming an image.

[0057] For example, in the image forming apparatus 1, when the image forming unit 10 transfers at least one toner image P from among the silver toner image PS, transparent toner image PC, and color toner image PN to the intermediate transfer belt 34, the toner image P is transferred to the medium M in the secondary transfer unit 39. As a result, the medium M is printed with one of the silver toner image PS, transparent toner image PC, and color toner image PN on its surface, or with them appropriately superimposed on each other.

[0058] Furthermore, the image forming apparatus 1 can transfer and fix a color toner image PN to the surface of the medium M, for example, and then return the medium M to the downstream side of the transport roller pair 57 without turning it over by the re-conveyance unit 66, and transfer and fix a silver toner image PS to the same surface of the medium M. At this time, the image forming apparatus 1 can further return the medium M to the downstream side of the transport roller pair 57 without turning it over by the re-conveyance unit 66, and transfer and fix a transparent toner image PC to the same surface of the medium M. Furthermore, the image forming apparatus 1 can further return the medium M to the downstream side of the transport roller pair 57 without turning it over by the re-conveyance unit 66, and transfer and fix a color toner image PN to the same surface of the medium M.

[0059] Furthermore, the image forming apparatus 1 can set the medium M in the first paper feed unit 40, transfer and fix a toner image P on its surface, eject the medium, and then set the medium M back in the first paper feed unit 40, whereby another toner image P can be transferred and fixed on top of the first toner image P. For example, the image forming apparatus 1 can first transfer and fix a lower color toner image PNL on the surface of the medium M, then transfer and fix a silver toner image PS on top of the first toner image PNL, then transfer and fix a transparent toner image PC on top of the first toner image PNL, and then transfer and fix an upper color toner image PNU on top of the first toner image PNL. In this case, the medium M has the lower color toner image PNL, silver toner image PS, transparent toner image PC, and upper color toner image PNU printed on top of the first toner image PNL on its surface.

[0060] In these cases, the image forming apparatus 1 can also adjust the temperature each time the fixing unit 60 fixes the toner image P to the medium M. For example, the image forming apparatus 1 can set the fixing temperature for the first fixing process, which fixes the silver toner image PS to the surface of the medium M, to a normal temperature (e.g., 150°C), and the fixing temperature for the second fixing process, which fixes the transparent toner image PC to the surface of the medium M, to a higher temperature (e.g., 190°C).

[0061] Incidentally, in the image forming apparatus 1, the absolute value of the bias voltage applied to each part can be increased by controlling the control unit 3, thereby increasing 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.

[0062] Next, the circuit configuration of the image forming apparatus 1 will be explained with reference to the block diagram in Figure 3. The control unit 3 of the image forming apparatus 1 is centered around the printing control unit 80, to which the storage unit 81, interface unit 82, display control unit 83, process control unit 84, development voltage control unit 85, supply voltage control unit 86, exposure control unit 87, transfer voltage control unit 88, and motor control unit 89 are connected.

[0063] 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, memory unit 81, etc. by the CPU 91.

[0064] The storage unit 81 is a non-volatile storage medium such as an HDD (Hard Disk Drive) or SSD (Solid State Drive), and stores various programs and information. This storage unit 81 is equipped with a data conversion table 95. This data conversion table 95 stores information for forming print patterns of each color based on print data acquired from the host device 100.

[0065] 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. The interface unit 82 can transmit and receive various information to and from the higher-level device 100, a predetermined server device (not shown), etc.

[0066] 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 operation unit 4, thereby causing the display screen to be displayed on the display operation unit 4.

[0067] 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 voltages 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 voltages applied to the first supply roller 22 and the second supply roller 23 (FIG. 2) based on instructions from the print control unit 80.

[0068] 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, 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 photosensitive drum 26 (FIG. 2) and each roller, etc. based on instructions from the print control unit 80.

[0069] The host 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 on the image forming device 1 is pre-installed on the host device 100. When the host device 100 receives a print instruction from the user in the application program for document data, image data, and the like, it 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.

[0070] [1-2. Toner manufacturing] Next, we will explain the toner T (also called developer) stored in the toner container 12 of the image forming unit 10 (FIG. 2). For the standard colors of black (K), cyan (C), and magenta (M), we used toner T of each color (black, cyan, and magenta) commercially available for the C941dn manufactured by Oki Electric Industry Co., Ltd.

[0071] The silver (SL) toner T (silver toner TSL), which is a bright color, and the transparent (CL) toner T (transparent toner TCL), which is a transparent color, were produced by the following methods.

[0072] First, the production of silver toner TSL will be described. In this embodiment, an aqueous medium containing an inorganic dispersant is first prepared. Specifically, 600 parts by weight of industrial-grade 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 is then added to adjust the pH (hydrogen ion index). A calcium chloride aqueous solution, prepared by dissolving 300 parts by weight of industrial-grade calcium chloride anhydrous in 2,600 parts by weight of pure water, is then added to this aqueous solution. While maintaining the liquid temperature at 60°C, the mixture is stirred at high speed for 34 minutes at a rotation speed of 3,566 rpm using a line mill (PRIMIX Corporation). This produces an aqueous phase, which is an aqueous medium containing a suspension stabilizer (inorganic dispersant) dispersed therein.

[0073] In this embodiment, a material dispersion oil medium is prepared by mixing 7,000 parts by weight of ethyl acetate, an organic solvent, with 470 parts by weight of a glittering pigment containing aluminum powder (volume median diameter 5.4 μm) and 23 parts by weight of a charge control agent (BONTRON E-84, manufactured by Orient Chemical Industries Co., Ltd.).

[0074] In this embodiment, the bright pigment used has a volume average particle size (also referred to as volume median diameter) of 5.4 μm, but this is not limited to this. Specifically, the volume average particle size of the bright 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.

[0075] In this embodiment, 175 parts by weight of ester wax (WE-4: manufactured by NOF Corporation) and 1670 parts by weight of polyester resin are then added while maintaining the temperature of the pigment dispersion at 60°C, and the mixture is stirred until no solid matter remains, thereby preparing an oil phase, which is an oil-based pigment dispersion medium.

[0076] Next, in this embodiment, the oil phase is added to the aqueous phase, the temperature of which has been lowered to 55°C, and the mixture is stirred for 5 minutes at a rotation speed of 1000 rpm to form a suspension, forming particles in the suspension. The suspension is then distilled under reduced pressure to remove ethyl acetate, forming a toner-containing slurry. Nitric acid is then added to this slurry, the pH of which is adjusted to 1.6 or less, and the mixture is stirred to dissolve the suspension stabilizer tricalcium phosphate. The toner is then dehydrated to form a toner. The dehydrated toner is then redispersed in pure water, stirred, and washed with water. In this embodiment, the toner base particles are then produced by a dehydration process, a drying process, and a classification process.

[0077] In this embodiment, to the toner matrix particles produced in this manner, 1.5 [weight] of small silica (RY200: manufactured by Nippon Aerosil Co., Ltd.), 2.29 [weight] of colloidal silica (X24-9163A: manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.37 [weight] of melamine particles (EPOSTAR S: manufactured by Nippon Shokubai Co., Ltd.) are added and mixed as an external addition step. Thus, in this embodiment, a silver toner TSL with lustrous properties can be obtained. The median volume diameter of the silver toner TSL produced in this manner was measured to be 15.01 [μm]. Note that the median volume diameter of the silver toner TSL is not limited to 15.01 [μm], but may be, for example, 10 to 20 [μm].

[0078] Next, the manufacturing process for transparent toner TCL will be described. In this embodiment, first, an aqueous medium in which an inorganic dispersant is dispersed is prepared. Specifically, 650 parts by weight of industrial trisodium phosphate dodecahydrate is mixed with 19540 parts by weight of pure water and dissolved at a liquid temperature of 60°C, after which dilute nitric acid for pH adjustment is added. To this aqueous solution, an aqueous calcium chloride solution prepared by dissolving 320 parts by weight of industrial anhydrous calcium chloride in 2560 parts by weight of pure water is added, and while maintaining the liquid temperature at 60°C, the mixture is rapidly stirred at a rotation speed of 3566 rpm for 34 minutes using a line mill (manufactured by Primix Corporation). This prepares the aqueous phase, which is an aqueous medium in which a suspension stabilizer (inorganic dispersant) is dispersed.

[0079] In this embodiment, a material-dispersed oily medium is produced. Specifically, 3120 parts by weight of ethyl acetate, an organic solvent, is heated and stirred at a liquid temperature of 50°C. Then, 17 parts by weight of paraffin wax (melting point: 62°C), 1.4 parts by weight of a fluorescent whitening agent, and 640 parts by weight of polyester resin are added sequentially, and the mixture is stirred until no solid matter remains. This prepares the oil phase.

[0080] Next, in this embodiment, the liquid temperature of the aqueous phase is lowered to 55°C, then the oil phase is added and the mixture is suspended by stirring at a rotation speed of 1000 rpm for 5 minutes to form particles in the suspension. Subsequently, the suspension is removed by vacuum distillation to form a slurry containing toner. Furthermore, nitric acid is added to this slurry to lower the pH to 1.5 or less and the mixture is stirred to dissolve the tricalcium phosphate, which is a suspension stabilizer, and the mixture is dehydrated to form toner. Subsequently, the dehydrated toner is redispersed in pure water and stirred to perform water washing. After that, in this embodiment, toner is produced by performing a dehydration process, a drying process and a classification process.

[0081] In this embodiment, to 100 parts by weight of the toner produced in this manner, 1.0 part by weight of hydrophobic silica RX50 (manufactured by Nippon Aerosil Co., Ltd., average primary particle size 40 [nm]) and 0.8 parts by weight of hydrophobic silica RX200 (manufactured by Nippon Aerosil Co., Ltd., average primary particle size 12 [nm]) are added as an external addition step and mixed. Thus, in this embodiment, a transparent toner TCL with permeability can be obtained.

[0082] [1-3. Visual effects by media] Next, the medium M on which the image has been printed by the image forming apparatus 1 will be described. As schematic diagrams are shown in Figures 4(A) and (B), the image forming apparatus 1 can sequentially superimpose and print the following on the surface of the medium M based on the control of the control unit 3: the first layer (bottom layer) lower color toner image PNL, the second layer silver toner image PS, the third layer transparent toner image PC, and the fourth layer (top layer) upper color toner image PNU.

[0083] Furthermore, the image forming apparatus 1, under the control of the control unit 3, forms multiple regions such as the background region AB and the decorative region AC in the second layer silver toner image PS, as shown in the schematic enlarged view in Figure 4(C). In this silver toner image PS, the amount of silver toner TSL deposited per unit area (hereinafter referred to as the amount deposited on the paper surface or the amount deposited on the medium) differs between the background region AB and the decorative region AC.

[0084] For the sake of explanation, the decorative area AC will also be referred to as the first area, and the background area AB will also be referred to as the second area. In this embodiment, the medium M on which four layers—a lower color toner image PNL, a silver toner image PS, a transparent toner image PC, and an upper color toner image PNU—are sequentially printed on the surface, and the background area AB and decorative area AC are formed in the second layer, the silver toner image PS, will be referred to as the decorative medium MC1.

[0085] Incidentally, the amount of toner T (silver toner TSL, transparent toner TCL, or color toner TNL) formed per unit area on the medium M can be expressed by the image density N[%]. This image density N corresponds to the ratio of the area of ​​the printed portion (the part where the image is formed) to the total area within the printable range of a predetermined region (for example, a region corresponding to one rotation of the photosensitive drum 26 or a region corresponding to one sheet of medium M). Furthermore, this image density N is set to 100[%] when printing an image with an area ratio of 100[%], similar to so-called full-surface solid printing. For example, when printing an image in a region corresponding to 1[%] of the printable range on medium M, the image density N is 1[%].

[0086] Incidentally, if the image density N is to be less than 100%, for example, in an image with an image density N of 100%, toner can be thinned out in the form of fine lines along a direction perpendicular to a predetermined direction at predetermined thinning intervals in that predetermined direction. In this case, the image density N can be adjusted by adjusting the thinning interval and the width (number of dots) of the fine lines.

[0087] Alternatively, if the image density N is to be less than 100%, this can be achieved, for example, by thinning out the toner in a halftone 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 halftone dots per unit area.

[0088] In this embodiment, for example, in a silver toner image PS using silver toner TSL, when the image density N is 100 [%], that is, in the case of a solid image, the amount of silver toner TSL adhering (forming) on ​​the surface of the medium M (i.e., the amount of adhering on the paper surface) is 0.45 [mg / cm 2 In this embodiment, for example, when the image density N of the silver toner image PS is 50%, the amount of adhesion on the paper surface is 0.225 mg / cm 2 ]

[0089] Here, the number of dots actually used for toner in the printing process when the photosensitive drum 26 rotates a predetermined number of rotations Cd, i.e., the number of exposed dots, is defined as the number of used dots Cm. Also, the number of dots per rotation of the photosensitive drum 26, i.e., the maximum number of dots potentially printable when the photosensitive drum 26 rotates once, regardless of whether it is exposed or not, and the number of dots when printing a so-called solid image, is defined as the total number of dots C0.

[0090] Therefore, the maximum number of dots that can potentially be printed when the photosensitive drum 26 rotates Cd times is (Cd x C0). Using this, the image density N can be expressed as the following equation (1).

[0091]

number

[0092] Furthermore, the amount of toner T (color toner TNL, clear toner TCL, or silver toner TSL) formed per unit area on medium M 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 the image-formable region of medium M is 100%. It is also the proportion of the area on medium M where the toner adheres and a toner image is formed. For this reason, hereinafter, print duty D is also referred to as the formation ratio. Note that a solid image here refers to a toner image on medium M formed by exposing the entire area in the printable range of photosensitive drum 26, and is an image in which toner T is used in all dots.

[0093] In other words, the print duty cycle D is the ratio of the number of dots used in the actual toner image P based on the print data to the total number of dots that make up the area on the medium M in which an image can be formed, and is sometimes called the print coverage ratio.

[0094] For example, when printing an image based on print data on a certain medium M, the control unit 3 calculates the print duty D using the following formula (2), where C1 is the dot count of the image data based on the print data and C0 is the dot count when the entire surface of the medium M is exposed to light. Note that formula (2) is just an example, and the control unit 3 can also calculate the print duty D using other formulas.

[0095]

number

[0096] In other words, in a silver toner image PS, the print duty cycle of the background area AB is different from that of the decorative area AC. For example, in a silver toner image PS of the decorative medium MC1, the print duty cycle of the background area AB can be set to 100%, and the print duty cycle of the decorative area AC can be set to 75%.

[0097] As shown in Figure 5(A), when an observer views the decorative medium MC1 from the surface at a predetermined angle, the uppermost color toner image PNU is visible, but the decorative area AC and background area AB of the silver toner image PS below it are not perceived.

[0098] On the other hand, as shown in Fig. 5(B), when a viewer views the decorative medium MC1 from the front side at an angle (posture) different from that shown in Fig. 5(A), the decorative area AC and the background area AB in the silver toner image PS of the second layer can be made to look different from each other by overlapping with the upper color toner image PNU of the top layer. In other words, in this case, the decorative medium MC1 allows the viewer to visually recognize an image in which the decorative area AC appears to stand out from the background area AB.

[0099] In this way, the decorative medium MC1 can be switched between a state in which the decorative area AC is hidden (FIG. 5(A)) and a state in which the decorative area AC is visible (FIG. 5(B)) by changing the angle relative to the observer's viewpoint, the light source, etc. In other words, the decorative medium MC1 has a visual effect (decorative effect) in which the decorative area AC is made visible or invisible to the observer by changing the position and posture of the decorative medium MC1 in various ways.

[0100] For example, the decorative medium MC1 can create a visual effect for the observer by initially showing only the uppermost color toner image PNU, and then, when the orientation of the decorative medium MC1 changes, it can give the impression that the decorative area AC stands out, overlapping with the upper color toner image PNU.

[0101] Next, we will explain the principle behind the visual effect of the decorative medium MC1. When the surface of the decorative medium MC1 is shown to an observer in a bright place, the upper color toner image PNU on the upper layer reflects light, allowing the observer to clearly see the upper color toner image PNU.

[0102] Furthermore, if the medium M is shown to an observer with only the silver toner image PS printed on it, the luminous pigment (aluminum flakes, etc.) contained in the silver toner image PS will reflect light well, allowing the observer to clearly see the silver toner image PS. In addition, as described above, the silver toner image PS has different printing duty cycles D in the background area AB and the decorative area AC. Therefore, the medium M will have different degrees of light reflection between the background area AB and the decorative area AC, allowing the boundary between the two and the shape of the decorative area AC to be clearly recognized.

[0103] Next, as shown in Fig. 6(A), it is assumed that the light source LS and the observer's viewpoint VP are both located on the front side of the decorative medium MC1. In this case, the colored lower color toner image PNL blocks light from the back side of the decorative medium MC1, so no light passes from the back side to the front side of the decorative medium MC1.

[0104] At this time, the decorative medium MC1 reflects light from the light source LS well with the uppermost color toner image PNU, and can deliver light of sufficient intensity from the upper color toner image PNU to the observer's eye. The decorative medium MC1 also allows a portion of the light from the light source LS to pass through the uppermost color toner image PNU and the third layer transparent toner image PC to reach the second layer silver toner image PS. The decorative medium MC1 reflects this light with a relatively high reflectivity with the silver toner image PS, and a portion of it passes through the transparent toner image PC and the upper color toner image PNU and travels towards the observer's viewpoint VP.

[0105] If we focus on the intensity of light reaching the observer's viewpoint VP, the intensity of light reflected by the upper color toner image PNU is significantly greater than the intensity of light reflected by the silver toner image PS. Therefore, when the observer looks at the front side of the decorative medium MC1, as shown in Figure 5(A), the upper color toner image PNU is clearly visible, while the silver toner image PS is almost invisible. In other words, in the state shown in Figure 6(A), the decorative medium MC1 can hide the image represented by the decorative region AC of the silver toner image PS from the observer.

[0106] 6(B), assume that the observer's viewpoint VP is located on the front side of the decorative medium MC1, while the light source LS is located on the back side of the decorative medium MC1. In this case, too, the light from the back side of the decorative medium MC1 is blocked by the colored lower color toner image PNL, so that no light passes from the back side to the front side of the decorative medium MC1.

[0107] At this time, due to the positional relationship between the decoration medium MC1 and the light source LS, the upper color toner image PNU on the top layer cannot sufficiently reflect the light from the light source LS, and relatively weak light from the upper color toner image PNU reaches the viewer's eyes. On the other hand, the decoration medium MC1 allows some of the light from the light source LS to pass through the upper color toner image PNU on the top layer and the transparent toner image PC on the third layer and then reach the silver toner image PS on the second layer. The decoration medium MC1 reflects this light with a relatively high reflectance from the silver toner image PS, and some of the light passes through the transparent toner image PC and the upper color toner image PNU and travels toward the viewer's viewpoint VP.

[0108] Here, when we focus on the intensity of light reaching the observer's viewpoint VP, the intensity of light reflected by the upper color toner image PNU is not significantly greater than the intensity of light reflected by the silver toner image PS. Therefore, when the observer looks at the front side of the decorative medium MC1, as shown in FIG. 5(B), the observer can see the upper color toner image PNU to some extent, while also seeing the silver toner image PS. In other words, in the state shown in FIG. 6(B), the decorative medium MC1 allows the observer to see an image formed as the decorative area AC of the silver toner image PS.

[0109] [1-4. Conditions for obtaining visual effects] Next, in this first embodiment, evaluation tests were conducted on the lower color toner image PNL and the silver toner image PS for the decorative medium MC1, which was decoratively printed on the medium M by the image forming device 1, in order to find the conditions for obtaining a good visual effect.

[0110] [1-4-1. Pre-preparation of image forming apparatus and media] In this evaluation test, a C941dn (manufactured by Oki Electric Industry Co., Ltd.) was used as the image forming apparatus 1. In addition, in this evaluation test, as a preliminary preparation process, various biases and the like were adjusted for silver (SL) and cyan (C) printed by the image forming apparatus 1.

[0111] For silver (SL), the luminous reflectance difference ΔY was used to adjust the silver toner TSL in the image forming apparatus 1. This luminous reflectance difference ΔY is calculated by subtracting the luminous reflectance Y2 on the medium M before printing from the luminous reflectance Y1 on the image after printing. A spectrophotometer CM-2600d (manufactured by Konica Minolta Japan, Inc.) was used to measure the luminous reflectance difference ΔY. The measurement conditions were a colorimetric auxiliary illuminant C (6774[K]) as the light source, an angle of 2[°], and SCE (Specular Reflectance Emission Control) was applied to specular reflection.

[0112] In this preliminary preparation, various bias voltages (development voltage, etc.) related to the silver (SL) image forming unit 10SL were appropriately adjusted so that the visual reflectance difference ΔY in the background area AB of the silver toner image PS printed on the surface of the medium M by the image forming device 1 would be a value of 26.

[0113] In this evaluation test, the lower color toner image PNL and the upper color toner image PNU were images with a cyan (C) monochrome print duty of 100% (solid images).

[0114] As a preliminary step, the image forming apparatus 1 printed only a cyan (C) image (solid image) with a printing duty cycle of 100% onto the surface of the medium M, and the optical density OD was measured using a spectrophotometer (X-Rite eXact: X-Rite Corporation). Then, in this evaluation test, the control unit 3 controlled various bias voltages (development voltage, etc.) related to the cyan (C) image forming unit 10C in the image forming apparatus 1 so that the optical density OD was 1.4.

[0115] [1-4-2. Creation of evaluation media and comparison media] In this evaluation test, "Color Copy 120" (manufactured by Mondi), a high-quality white paper, was used as the medium M. This medium M is JIS / ISO A4 size (297 x 210 [mm]) and has a basis weight of 120 [g / m²]. 2 This medium M has an ISO whiteness of 110%, and its smoothness is enhanced compared to general fine paper due to a predetermined surface treatment.

[0116] Furthermore, in the evaluation test in this embodiment, after the above-described preliminary preparations were carried out, the image forming apparatus 1 used medium M to create eight types of evaluation mediums ME1 as Example 1 (Examples 1-1, 1-2, ..., 1-8), and eight types of comparison mediums MQ1 as Comparative Example 1 (Comparative Example 1-1, 1-2, ..., 1-8).

[0117] Each evaluation medium ME1 in Example 1 has the same configuration as the decorative medium MC1 shown in Figure 4, as shown in the schematic cross-sectional view in Figure 7(A). The lower color toner image PNL, silver toner image PS, transparent toner image PC, and upper color toner image PNU are sequentially superimposed on the medium M.

[0118] On the other hand, each comparative medium MQ1 in Comparative Example 1 has a configuration in which the lower color toner image PNL is omitted from the decorative medium MC1, as shown in the schematic cross-sectional view in Figure 7(B). The silver toner image PS, transparent toner image PC, and upper color toner image PNU are sequentially superimposed on the medium M.

[0119] Thus, in the first embodiment, each evaluation medium ME1 of Example 1 is configured to have a lower color toner image PNL, while each comparison medium MQ1 of Comparative Example 1 is configured to omit the lower color toner image PNL.

[0120] In addition, in this evaluation test, for the silver toner image PS, the printing duty of the background area AB was fixed at 100% for each evaluation medium ME1 and each comparison medium MQ1, while the printing duty of the decorative area AC was set to eight different values ​​less than 100%.

[0121] In Example 1 (Examples 1-1, 1-2, ..., 1-8), the specific values ​​of the print duty in the decorative area AC were 94, 88, 81, 75, 69, 63, 56, and 50%, respectively, which were successively decreased by 6 to 7% from 94%. Similarly, in Comparative Example 1 (Comparative Examples 1-1, 1-2, ..., 1-8), the specific values ​​of the print duty in the background area AB were 94, 88, 81, 75, 69, 63, 56, and 50%, respectively. In other words, in this evaluation test, eight common values ​​were used for the print duty in the decorative area AC between Example 1 and Comparative Example 1.

[0122] Furthermore, in this evaluation test, in each of the evaluation media ME and each of the comparison media MQ, multiple "OK" characters (Figures 4(C) and 5(B)) were formed in the silver toner image PS using the decorative area AC.

[0123] In addition, in this evaluation test, images (solid images) with a printing duty of 100% were used for each image except for the silver toner image PS, i.e., the lower color toner image PNL on each evaluation medium ME1, and the transparent toner image PC and upper color toner image PNU on each evaluation medium ME1 and each comparison medium MQ1.

[0124] Fig. 8 shows in tabular form the print duty values ​​in the decorative area AC and background area AB of the silver toner image PS in each of Example 1 (Examples 1-1, 1-2, ..., 1-8). Fig. 9 shows in tabular form the print duty values ​​in the decorative area AC and background area AB of the silver toner image PS in each of Comparative Examples 1 (Comparative Examples 1-1, 1-2, ..., 1-8).

[0125] In Figure 8, for the sake of convenience in correspondence with the second embodiment described later, the printing duty in both the decorative area AC and the background area AB is set to 100%, thereby indicating that the lower color toner image PNL is a solid image.

[0126] [1-4-3. Measurement and calculation of transmittance and color difference] Next, in this evaluation test, the transmittance TM of the decorated area AC and the color difference ΔE between the decorated area AC and the background area AB were measured and calculated for each evaluation medium ME1 in Example 1 and each comparison medium MQ1 in Comparative Example 1.

[0127] Regarding the transmittance TM, a tabletop transmission densitometer (X-Rite 361, manufactured by X-Rite Inc.) was used to measure the transmission density TD of the decorative area AC in each evaluation medium ME and each comparison medium MQ. Next, the transmittance TM was calculated using the following equation (3):

[0128]

number

[0129] Regarding the color difference ΔE, first, a spectrophotometer (X-Rite eXact, manufactured by X-Rite) was used to measure the colors of the decorative area AC and the background area AB, and values ​​expressed in the L*a*b* color system were obtained. Then, the color value of the decorative area AC (L* C ,a* C ,b* C ) and the color value of the background area AB (L* B ,a* B ,b* B ) and calculated the color difference ΔE using the following formula (4).

[0130]

number

[0131] The transmittance TM and color difference ΔE calculated in this manner were the values ​​shown in Figure 8 for each evaluation medium ME1 in Example 1, and the values ​​shown in Figure 9 for each comparison medium MQ1 in Comparative Example 1.

[0132] [1-4-4. Visual assessment of evaluation media] Next, in this evaluation test, visual judgments were performed for both Example 1 and Comparative Example 1. This judgment determined whether it was possible to distinguish between the background area AB and the decorated area AC, that is, whether the word "OK" could be seen, under two different viewing conditions in which the angle of view to the image on the decorative medium MC1 was different under a fixed light source.

[0133] The two types of viewing conditions were the first viewing condition, schematically shown in Figure 10(A), and the second viewing condition, schematically shown in Figure 10(B). In the first viewing condition, the light source LS was positioned so that the angle of incidence to the surface of the decorative medium MC1 was 45 degrees, and the observer's (the person making the judgment) viewpoint VP was positioned in a direction that made a 90-degree angle to the surface, that is, the line of sight LVP from the viewpoint VP was positioned perpendicular to the surface.

[0134] In the second viewing condition, similar to the first viewing condition, the light source LS was positioned so that the angle of incidence with respect to the surface of the decorative medium MC1 was 45 degrees, while the observer's viewpoint VP 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.

[0135] In all viewing conditions, a fluorescent lamp was used as the light source LS, and the distance from the light source LS to the decorative medium MC1 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 evaluation was performed in a dark room to eliminate the influence of other lighting, etc.

[0136] First, in this evaluation test, it was determined whether or not the background area AB and the decorative area AC could be distinguished under each viewing condition. Hereinafter, this determination will also be referred to as a distinction determination, and the obtained determination result will be referred to as a distinction determination result. Next, in this evaluation test, it was determined whether or not the effect of the decorative area AC appearing or hiding (i.e., visual effect) was obtained based on the distinction determination results under both viewing conditions. Hereinafter, this determination will be referred to as a visual effect determination.

[0137] Specifically, in this evaluation test, if the background area AB and the decorative area AC could be distinguished under one viewing condition, but the background area AB and the decorative area AC could not be distinguished under the other viewing condition, it was determined that the visual effect of the decorative area AC appearing or disappearing was achieved, and this was represented by the symbol "○".

[0138] In addition, in this evaluation test, if the background area AB and the decorative area AC could be distinguished under both viewing conditions and the decorative area AC was visible in both cases, and if the background area AB and the decorative area AC could not be distinguished under both viewing conditions and the decorative area AC was not visible in both cases, it was determined that no visual effect was obtained, and this was indicated by the symbol "x".

[0139] As shown in Fig. 8, in Example 1, no visual effect was obtained when the print duty value in background area AB was 88% or higher, but a visual effect was obtained when the print duty value was 81% or lower. Also, as shown in Fig. 9, in Comparative Example 1, no visual effect was obtained regardless of the print duty value in background area AB.

[0140] Here, for each Example 1 and each Comparative Example 1, the transmittance TM of the decorated area AC was plotted on the horizontal axis and the color difference ΔE on the vertical axis, and the relationship between the two was plotted, resulting in the graph shown in Fig. 11. In Fig. 11, each plot of Example 1 is indicated by a circle, and further, those for which a visual effect was obtained are shown in white, and those for which no visual effect was obtained are shown in black.

[0141] From Figure 11, it was found that, for a blank medium M, in the configuration where the lower color toner image PNL was omitted as in Comparative Example 1, no visual effect was obtained regardless of the duty cycle of the decorative area AC. However, in the configuration where the lower color toner image PNL was provided as in Example 1, a visual effect could be obtained depending on the duty cycle of the decorative area AC. In other words, in order to obtain a visual effect on the decorative medium MC1, it is necessary to provide at least the lower color toner image PNL.

[0142] In addition, in this evaluation test, a comparison medium MQ2 (not shown) was created in which the lower color toner image PNL and the silver toner image PS in Example 1 were swapped, and it was evaluated whether a visual effect could be obtained. Specifically, in this comparison medium MQ2, the bottom layer (1st layer) is the silver toner image PS, the 2nd layer is the lower color toner image PNL, the 3rd layer is the transparent toner image PC, and the top layer (4th layer) is the upper color toner image PNU.

[0143] However, no visual effect was obtained with the comparison medium MQ2. This is presumed to be because, in the comparison medium MQ2, the reflection of light from the silver toner image PS blocked the lower color toner image PNL. Therefore, in order to obtain the visual effect, it is considered necessary to place the lower color toner image PNL below the silver toner image PS.

[0144] 11, it is possible that there exists a range for each of the transmittance TM and the color difference ΔE that can provide a good visual effect. However, each Example 1 and each Comparative Example 1 could not specifically identify that range.

[0145] [1-5. Decorative media printing process] Next, a decorative medium printing process will be described in which the image forming apparatus 1 prints an image on the medium M to provide a visual effect, thereby creating a decorative medium MC1.

[0146] Based on the results of the evaluation test described above, when creating the decorative medium MC1, the image forming device 1 is configured to first provide a lower color toner image PNL, and then overlay it with a silver toner image PS, a transparent toner image PC, and an upper color toner image PNU.

[0147] Specifically, when the control unit 3 (Figure 3) of the image forming device 1 receives print data from the higher-level device 100 via the interface unit 82, the print control unit 80 reads and executes the decorative medium printing program from the memory unit 81, starts the decorative medium printing processing procedure RT1 shown in Figure 12, and proceeds to the first step SP1.

[0148] In step SP1, the control unit 3 displays a predetermined message on the display operation unit 4 to prompt the user to set the medium M in the first paper feed unit 40, and then proceeds to the next step SP2.

[0149] In step SP2, 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 SP3. 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).

[0150] In step SP3, the control unit 3 controls the cyan image forming unit 10C based on the received print data to form the lower color toner image PNL to be printed on the surface of the medium M on the intermediate transfer belt 34 (FIGS. 1 and 2). Next, the control unit 3 causes the secondary transfer unit 39 to transfer the lower color toner image PNL from the intermediate transfer belt 34 to the surface of the medium M, and then causes the fixing unit 60 to fix the silver toner image PS to the surface of the medium M, and proceeds to the next step SP4. In step SP4, the control unit 3 causes the re-feed unit 66 to return the medium M to the downstream side of the feed roller pair 57 without turning it over, and proceeds to the next step SP5.

[0151] In step SP5, the control unit 3 controls the silver image forming unit 10SL based on the received print data to form a silver toner image PS on the intermediate transfer belt 34 (FIGS. 1 and 2) to be printed superimposed on the surface of the medium M on which the lower color toner image PNL has been printed. Next, the control unit 3 controls the secondary transfer unit 39 to transfer the silver toner image PS from the intermediate transfer belt 34 to the surface of the medium M so that it is superimposed on top of the lower color toner image PNL. Furthermore, the control unit 3 controls the fixing unit 60 to fix the silver toner image PS superimposed on top of the lower color toner image PNL on the surface of the medium M, and then proceeds to the next step SP6. In step SP6, as in step SP4, the control unit 3 returns the medium M to the downstream side of the conveyance roller pair 57 without turning it over by using the re-conveyance unit 66, and then proceeds to the next step SP7.

[0152] In step SP7, the control unit 3 controls the transparent-color image forming unit 10CL based on the received print data to form a transparent toner image PC on the intermediate transfer belt 34 (FIGS. 1 and 2) to be printed superimposed on the surface of the medium M on which the lower color toner image PNL and the silver toner image PS have been printed. Next, the control unit 3 controls the secondary transfer unit 39 to transfer the transparent toner image PC from the intermediate transfer belt 34 to the surface of the medium M so that it is superimposed on top of the lower color toner image PNL and the silver toner image PS. Furthermore, the control unit 3 controls the fixing unit 60 to fix the transparent toner image PC superimposed on top of the lower color toner image PNL and the silver toner image PS on the surface of the medium M, and then proceeds to the next step SP8. In step SP8, the control unit 3 returns the medium M to the downstream side of the conveying roller pair 57 without turning it over, as in step SP4, etc., using the re-conveyance unit 66, and then proceeds to the next step SP9.

[0153] In step SP9, based on the received print data, the control unit 3 controls the cyan image forming unit 10C to form on the intermediate transfer belt 34 (FIGS. 1 and 2) an upper color toner image PNU to be printed superimposed on the surface of the medium M on which the lower color toner image PNL, silver toner image PS, and clear toner image PC have been printed. Next, the control unit 3 controls the secondary transfer unit 39 to transfer the upper color toner image PNU from the intermediate transfer belt 34 so that it is superimposed on top of the lower color toner image PNL, silver toner image PS, and clear toner image PC on the surface of the medium M. Furthermore, the control unit 3 controls the fixing unit 60 to fix the upper color toner image PNU superimposed on top of the lower color toner image PNL, silver toner image PS, and clear toner image PC on the surface of the medium M, and then proceeds to the next step, SP10.

[0154] In step SP10, the control unit 3 transports the medium M along the transport path W using the paper discharge unit 70, discharges it from the discharge port 76 to the paper discharge tray 2T, and then moves to the next step SP11 to complete the decorative medium printing procedure RT1.

[0155] As a result, the image forming apparatus 1 can create a decorative medium MC1 on the surface of the medium M, in which a lower color toner image PNL, a silver toner image PS having a background area AB and a decorative area AC, a transparent toner image PC, and an upper color toner image PNU are sequentially printed on top of each other.

[0156] [1-6. Effects, etc.] In the above configuration, the image forming apparatus 1 according to the first embodiment creates a decorated medium MC1 by sequentially superimposing and printing a lower color toner image PNL, a silver toner image PS having a background area AB and a decorative area AC, a transparent toner image PC, and an upper color toner image PNU onto the surface of a blank medium M.

[0157] As a result, the image forming apparatus 1 can provide a good visual effect in which the decorated area AC appears and disappears on the surface side of the decorated medium MC1, when the position and orientation of the decorated medium MC1 are changed in various ways by the observer, and the relative position and angle relationship between the observer's viewpoint VP, the light source LS, and the decorated medium MC1 changes in various ways.

[0158] In particular, since the decorative medium MC1 uses white paper as the medium M, some light is more easily transmitted between the front and back sides of the medium M compared to when black paper or the like is used. Specifically, as shown in Comparative Example 1 (Figure 9), in the comparative medium MQ1 in which the lower color toner image PNL was omitted, the transmittance TM value in the decorative area AC was relatively high, ranging from 1.82% to 2.45% depending on the printing duty cycle. Therefore, in Comparative Example 1, in the comparative medium MQ1, the decorative area AC portion of the silver toner image PS was less likely to be hidden by the upper color toner image PNU, and a visual effect of it being visible or hidden was not obtained.

[0159] In contrast, as shown in Example 1 (Figure 8), in the evaluation medium ME1 provided with the lower color toner image PNL, the transmittance TM in the decorative area AC was a relatively low value, ranging from 0.47% to 0.62% depending on the print duty cycle. Therefore, in Example 1, in the evaluation medium ME1, the decorative area AC portion of the silver toner image PS was easily obscured by the upper color toner image PNU, and a visual effect of it being partially visible or partially hidden was obtained for some print duty cycles.

[0160] As described above, the silver toner image PS has a certain difference in printing duty between the background area AB and the decorative area AC. Therefore, when the silver toner image PS is printed on the medium M, there is a possibility that a step will be formed on the surface of the medium M at the boundary between the background area AB and the decorative area AC.

[0161] Therefore, if, for example, the color toner image PNU is printed on top of the silver toner image PS on the surface side of the medium M, that is, in the case of Patent Document 1, the step difference at the boundary between the background area AB and the decorative area AC formed in the silver toner image PS may appear on the surface of the color toner image PNU as well.

[0162] Consequently, if an observer were to view the medium M in a situation similar to that shown in Figure 6(A), they might be able to see the step formed in the upper color toner image PNU, and thus perceive the shape of the decorative area AC. In other words, even if the intention was to conceal the decorative area AC, there was a risk that it could be seen through the step.

[0163] Therefore, the image forming apparatus 1 prints a transparent toner image PC superimposed on a silver toner image PS on the decorative medium MC1, and then prints an upper color toner image PNU on top of it (Figure 4, etc.). In other words, although a step is formed between the background area AB and the decorative area AC in the silver toner image PS, the image forming apparatus 1 can effectively fill this step by superimposing the transparent toner image PC, making its upper surface significantly smoother than the upper surface of the silver toner image PS, bringing it closer to a flat state.

[0164] This allows the image forming apparatus 1 to form a sufficiently flat surface of the upper color toner image PNU on the decorative medium MC1, making it difficult for an observer to notice the step between the background area AB and the decorative area AC formed below it.

[0165] In other words, the image forming device 1 can adequately hide the decorative area AC in the printed decorative medium MC1, thereby preventing the decorative area AC from appearing more than necessary in a form different from its original appearance and providing a good visual effect to the observer.

[0166] With the above configuration, the image forming apparatus 1 according to the first embodiment creates a decorative medium MC1 by sequentially superimposing and printing a lower color toner image PNL, a silver toner image PS having a background area AB and a decorative area AC, a transparent toner image PC, and an upper color toner image PNU onto the surface of a blank medium M. As a result, the decorative medium MC1 can reduce the amount of light transmitted from the back side of the medium M compared to the case where the lower color toner image PNL is omitted, making the decorative area AC difficult to see. Thus, the image forming apparatus 1 can provide a good visual effect in which the decorative area AC appears and disappears on the surface side of the decorative medium MC1 when the relative position and angle relationship between the observer's viewpoint VP, the light source LS, and the decorative medium MC1 changes in various ways.

[0167] [2. Second Embodiment] Image forming apparatus 201 according to the second embodiment differs from image forming apparatus 1 according to the first embodiment in that it has control unit 203 instead of control unit 3, but is otherwise configured in the same manner.

[0168] The control unit 203 (Figure 3) differs from the control unit 3 in the first embodiment in that it has a storage unit 281 instead of the storage unit 81, but is otherwise configured similarly. The storage unit 281, like the storage unit 81 in the first embodiment, is a non-volatile storage medium such as an HDD or SSD, and stores various programs and information, although the programs and other information it stores differ in some respects from those in the first embodiment.

[0169] Furthermore, the storage unit 281 is provided with a data conversion table 295, which replaces the data conversion table 95. Similar to the data conversion table 95, this data conversion table 295 stores information for forming print patterns of each color based on print data acquired from the host device 100, but some of this information differs from that of the first embodiment.

[0170] [2-1. Composition of decorative media] Next, we will explain the medium M on which an image is printed by the image forming apparatus 201. As shown in the schematic diagrams of Figures 13(A) and 13(B) corresponding to Figures 4(A) and 4(B), the image forming apparatus 201 creates a decorative medium MC2 by printing multiple images on the surface of the medium M in an overlapping manner based on the control of the control unit 203.

[0171] This decorative medium MC2 differs from the decorative medium MC1 in the first embodiment in that it has a background area AB and a decorative area AC formed on the lower color toner image PNL, similar to the silver toner image PS. Furthermore, in the decorative medium MC2, the background area AB and the decorative area AC are formed so that their ranges coincide on a plane parallel to the surface of the medium M between the silver toner image PS and the lower color toner image PNL.

[0172] Furthermore, in the silver toner image PS of the MC2 decorative medium, the print duty cycle in the background area AB is 100%, while the print duty cycle in the decorative area AC is lower. On the other hand, in the lower color toner image PNL of the MC2 decorative medium, the print duty cycle in the background area AB is approximately 20-40%, while the print duty cycle in the decorative area AC is higher.

[0173] Furthermore, in the decorative medium MC2, the magnitude of the difference in print duty between the background area AB and the decorative area AC for the silver toner image PS is approximately equal to the magnitude of the difference in print duty between the background area AB and the decorative area AC for the lower color toner image PNL.

[0174] Therefore, in the decorative medium MC2, when the lower color toner image PNL is printed on the surface of the medium M, and then the silver toner image PS is printed on top of it, the surface becomes almost flat. Consequently, when the transparent toner image PC and the upper color toner image PNU are printed on top of the silver toner image PS in the decorative medium MC2, the smoothness of the surface can be improved compared to the decorative medium MC1 (Figure 4, etc.).

[0175] [2-2. Conditions for obtaining visual effects] Next, in this second embodiment, evaluation tests were conducted on the lower color toner image PNL and the silver toner image PS for the decorative medium MC2, which was decoratively printed on the medium M by the image forming device 201, in order to explore in more detail than in the first embodiment the conditions for achieving a good visual effect.

[0176] [2-2-1. Creation of evaluation and comparison media] In this evaluation test, as in the first embodiment, a C941dn (manufactured by Oki Electric Industry Co., Ltd.) was used as the image forming apparatus 201. In addition, in this evaluation test, as in the first embodiment, unless otherwise specified, a medium M having a basis weight (basis weight) of 120 [g / m 2 We used the "Color Copy 120" (manufactured by Mondi).

[0177] Furthermore, in the evaluation test of this embodiment, after carrying out the same preliminary preparations as in the first embodiment, seven groups of evaluation media ME2 were created as seven examples (Examples 21, 22, 23, 24, 25, 26 and 27) using the image forming device 201 and the medium M.

[0178] Each evaluation medium ME2 has the same configuration as the decorative medium MC2 shown in Fig. 13, with a lower color toner image PNL, a silver toner image PS, a transparent toner image PC, and an upper color toner image PNU superimposed in this order on the medium M. In addition, the lower color toner image PNL and the silver toner image PS each have a decorative area AC and a background area AB.

[0179] Of these, the print duty of the silver toner image PS in the background area AB was fixed at 100[%], while the print duty of the decorative area AC was set to a value that was successively reduced by 6 to 7[%] in each example from 94[%], as in Example 1 of the first embodiment. In detail, eight types were used in Example 21, four types in Example 22, 12 types in Example 23, 10 types in Example 24, eight types in Example 25, 12 types in Example 26, and 12 types in Example 27.

[0180] On the other hand, for the lower color toner image PNL, the printing duty cycles for the decorative area AC and background area AB were determined based on different policies for each example.

[0181] First, in Examples 21, 22, and 23, the printing duty of the background area AB was made different from one another, being 31[%] in Example 21, 44[%] in Example 22, and 19[%] in Example 23. The printing duty of the decorative area AC of the lower color toner image PNL was specifically set to 38[%] to 81[%] in Example 21, 50[%] to 69[%] in Example 22, and 25[%] to 94[%] in Example 23.

[0182] Next, in Examples 24 and 25, the print duty of the background area AB was set to 19%, the same as in Example 23, while the print duty of the decorative area AC was set to a slightly higher value. Specifically, the print duty of the decorative area AC was set to 38% to 94% in Example 24, and 50% to 94% in Example 25.

[0183] Furthermore, in Examples 26 and 27, the printing duties of the silver toner image PS and the lower color toner image PNL were the same as in Example 23, but different weights were used as the medium M. Specifically, in Example 26, the weight was 200 [g / m 2 Using "Color Copy 200" (manufactured by Mondi), in Example 27, the weighing capacity was 300 [g / m²]. 2I used "Color Copy 300" (manufactured by Mondi).

[0184] Figure 14 shows in table format the print duty cycle values ​​for the decorative area AC and background area AB of the lower color toner image PNL and silver toner image PS in each of the 21 examples (Examples 21-1, 21-2, ..., 21-8). Figure 15 shows in table format the print duty cycle values ​​for the decorative area AC and background area AB of the lower color toner image PNL and silver toner image PS in each of the 22 examples (Examples 22-1, 22-2, 22-3, 22-4). Figure 16 shows in table format the print duty cycle values ​​for the decorative area AC and background area AB of the lower color toner image PNL and silver toner image PS in each of the 23 examples (Examples 23-1, 23-2, ..., 23-12).

[0185] Figure 17 shows in table format the print duty cycle values ​​for the decorative area AC and background area AB of the lower color toner image PNL and silver toner image PS in each of the 24 examples (Examples 24-1, 24-2, ..., 24-10). Figure 18 shows in table format the print duty cycle values ​​for the decorative area AC and background area AB of the lower color toner image PNL and silver toner image PS in each of the 25 examples (Examples 25-1, 25-2, ..., 25-8).

[0186] Furthermore, Figure 19 shows in table format the print duty cycle values ​​for the decorative area AC and background area AB of the lower color toner image PNL and silver toner image PS in each of the 26 examples (Examples 26-1, 26-2, ..., 26-12). Figure 20 shows in table format the print duty cycle values ​​for the decorative area AC and background area AB of the lower color toner image PNL and silver toner image PS in each of the 27 examples (Examples 27-1, 27-2, ..., 27-12).

[0187] Furthermore, in the second embodiment, similarly to the first embodiment, the transmittance TM and color difference ΔE of the decorative area AC in each example were measured and calculated, resulting in the values ​​shown in the tables of Figures 14 to 20.

[0188] [2-2-2. Visual assessment of evaluation media] Next, in this evaluation test, visual judgment was performed on each of the seven groups of examples (Examples 21, 22, 23, 24, 25, 26, and 27). As in the first embodiment, this judgment consisted of a distinction judgment to determine whether or not it was possible to distinguish between the background region AB and the decorative region AC under each of the first viewing condition (FIG. 10(A)) and the second viewing condition (FIG. 10(B)), and then a visual effect judgment to determine whether or not a visual effect was obtained.

[0189] In Example 21, as shown in Figure 14, visual effects were obtained in eight types of Examples 21-1 to 21-8, i.e., in all evaluation tests. In Example 22, as shown in Figure 15, visual effects were obtained in Examples 22-3 and 22-4, but not in Examples 22-1 and 22-2. In Example 23, as shown in Figure 16, visual effects were obtained in Examples 23-9 and 23-10, but not in Examples 23-1 to 23-8, 23-11, and 23-12.

[0190] In Example 24, as shown in Figure 17, visual effects were obtained in Examples 24-9 to 24-12, but not in Examples 24-1 to 24-8. In Example 25, as shown in Figure 18, visual effects were obtained in Examples 25-2 to 25-8, but not in Example 25-1.

[0191] In Example 26, as shown in Figure 19, visual effects were obtained in Examples 26-1 to 26-8, but not in Examples 26-9 to 26-12. In Example 27, as shown in Figure 20, visual effects were obtained in Examples 27-3, 27-7, and 27-8, but not in Examples 27-1 and 27-2, Examples 27-4 to 27-6, and Examples 27-9 to 27-12.

[0192] Here, for Examples 21 to 27, the transmittance TM of the decorated area AC was plotted on the horizontal axis and the color difference ΔE on the vertical axis, and the relationship between the two was plotted, resulting in the graph shown in Figure 21, which corresponds to Figure 11. In Figure 21, circles indicate results that had a visual effect, and triangles indicate results that did not have a visual effect.

[0193] From the graph in Figure 21, it can be inferred that with decorative medium MC2, if the transmittance of decorative area AC is too low, the shapes of letters and images will not be easily hidden by the reflection of light, and therefore no visual effect will be obtained. Also, from the graph in Figure 21, it can be inferred that with decorative medium MC2, if the transmittance of decorative area AC is too high, more light will be transmitted than reflected depending on the angle, which will increase visibility, prevent the decorative area AC from being hidden, and therefore no visual effect will be obtained.

[0194] 21, it is inferred that, in the decorative medium MC2, if the color difference ΔE between the decorative area AC and the background area AB is too small, the decorative area AC and the background area AB will blend together, making the decorative area AC invisible. Also, it is inferred from the graph in FIG. 21 that, in the decorative medium MC2, if the color difference ΔE between the decorative area AC and the background area AB is too large, the shape of the decorative area AC (such as letters or figures) will stand out and be difficult to conceal, making it impossible to obtain a visual effect.

[0195] In Fig. 21, as shown by the dashed lines and shading in the same way as in Fig. 11, it is possible that there are ranges for the transmittance TM and the color difference ΔE in which a good visual effect can be obtained. Regarding the transmittance TM of the decorative area AC, it can be seen that the plotted area (circled) in which a good visual effect can be obtained is concentrated within a range of at least 0.22% and 0.98%. On the other hand, regarding the color difference ΔE, no clear range has been found.

[0196] Therefore, in the image forming device 201, the range in which the transmittance TM of the decorative area AC is 0.22[%] or more and 0.98[%] or less is defined as the range in which a visual effect is likely to be obtained (in this embodiment, this is called the visual effect range or visual effect condition).

[0197] Furthermore, when creating the decorative medium MC2 in the image forming device 201, the control unit 203 controls the printing duty of the decorative area AC and the background area AB in the lower color toner image PNL and the silver toner image PS so that the transmittance TM of the decorative area AC is 0.22 [%] or more and 0.98 [%] or less.

[0198] [2-3. Printing process for decorative media] Next, a decorative medium printing process will be described in which the image forming apparatus 201 prints an image on the medium M that provides a visual effect to create a decorative medium MC2.

[0199] Based on the results of the evaluation test described above, when creating the decorative medium MC2, the image forming apparatus 201 prints the lower color toner image PNL, the silver toner image PS, the transparent toner image PC, and the upper color toner image PNU in a sequentially overlapping manner, in the same manner as when creating the decorative medium MC1 in the first embodiment.

[0200] Furthermore, the image forming apparatus 201 forms a decorative area AC and a background area AB in the lower color toner image PNL and silver toner image PS, respectively, where the printing duty cycles differ from each other, and adjusts the respective printing duty cycles to satisfy the above-mentioned visual effect conditions.

[0201] Specifically, the image forming apparatus 201 stores in advance, in a data conversion table 295 (FIG. 3) of the storage unit 281, information for realizing the print duties of the decorative area AC and the background area AB in the lower color toner image PNL and the silver toner image PS that satisfy the visual effect conditions. That is, the data conversion table 295 stores information for forming print patterns that set the transmittance TM of the lower color toner image PNL and the silver toner image PS to 0.22% or more and 0.98% or less.

[0202] Then, the control unit 203 of the image forming apparatus 201 executes the decorative medium printing procedure RT1 (Figure 12), similar to the first embodiment, to sequentially transfer and fix the lower color toner image PNL, silver toner image PS, transparent toner image PC, and upper color toner image PNU onto the medium M, thereby creating the decorative medium MC2.

[0203] However, when forming the lower color toner image PNL in step SP3 and when forming the silver toner image PS in step SP5, the control unit 203 sets the printing duty of the decorative area AC and the background area AB to appropriate values ​​by referring to the data conversion table 295 (Figure 3) in the memory unit 281.

[0204] [2-4. Effects, etc.] In the above configuration, the image forming apparatus 201 according to the second embodiment creates a decorated medium MC2 by printing a lower color toner image PNL and a silver toner image PS having a background area AB and a decorated area AC, a transparent toner image PC and an upper color toner image PNU, in a sequentially superimposed manner, on the surface of a blank medium M.

[0205] This allows the image forming device 201 to provide a good visual effect in which the decorative area AC appears and disappears on the surface side of the decorative medium MC2 when the position and posture of the decorative medium MC2 are changed in various ways by the observer, and the relative positions and angles of the observer's viewpoint VP, light source LS, and the decorative medium MC2 change in various ways.

[0206] In particular, the image forming apparatus 201 appropriately adjusts the print duties of the background area AB and the decorative area AC of the lower color toner image PNL and the silver toner image PS so as to satisfy the visual effect conditions determined based on the results of visual effect judgments in multiple evaluation tests. That is, the image forming apparatus 201 satisfies the visual effect conditions that the transmittance TM of the decorative area AC of the lower color toner image PNL and the silver toner image PS is 0.22% or more and 0.98% or less.

[0207] Therefore, the image forming apparatus 201 can create a decorative medium MC2 that more reliably produces visual effects compared to the first embodiment.

[0208] In addition, the image forming device 201 makes the magnitude of the difference in print duty between the background area AB and the decorative area AC for the silver toner image PS approximately equal to the magnitude of the difference in print duty between the background area AB and the decorative area AC for the lower color toner image PNL (Figures 14 to 20).

[0209] Therefore, when creating the decorative medium MC2, the image forming apparatus 201 can make the surface of the decorative medium MC2 almost flat at the stage when it has finished printing the silver toner image PS over the lower color toner image PNL. As a result, when the image forming apparatus 201 completes the decorative medium MC2 by overlaying the transparent toner image PC and the upper color toner image PNU on top of it, there is almost no physical difference in level between the background area AB and the decorative area AC, and the possibility that the decorative area AC will be unnecessarily visible can be significantly reduced.

[0210] In other respects as well, the image forming apparatus 201 according to the second embodiment can achieve the same effects as the image forming apparatus 1 according to the first embodiment.

[0211] 3. Third Embodiment The image forming apparatus 301 according to the third embodiment differs from the image forming apparatus 1 according to the first embodiment in that it has a control unit 303 instead of the control unit 3, but is otherwise configured similarly.

[0212] The control unit 303 (Figure 3) differs from the control unit 3 in the first embodiment in that it has a storage unit 381 instead of the storage unit 81, but is otherwise configured similarly. The storage unit 381, like the storage unit 81 in the first embodiment, is a non-volatile storage medium such as an HDD or SSD, and stores various programs and information, although the programs and other information it stores differ in some respects from those in the first embodiment.

[0213] Furthermore, the storage unit 381 is provided with a data conversion table 395, which replaces the data conversion table 95. Similar to the data conversion table 95, this data conversion table 395 stores information for forming print patterns of each color based on print data acquired from the host device 100, but some of this information differs from that of the first embodiment.

[0214] [3-1. Composition of decorative media] Next, the medium M on which the image is printed by the image forming apparatus 301 will be described. Based on the control of the control unit 303, the image forming apparatus 301 creates a decorative medium MC3 with a configuration similar to the decorative medium MC2 (Figures 13(A) and (B)) in the second embodiment.

[0215] Similar to the decorative medium MC2, the decorative medium MC3 has a configuration in which a lower color toner image PNL and a silver toner image PS, with background areas AB and decorative areas AC respectively formed on the surface of medium M, are superimposed, and a transparent toner image PC and an upper color toner image PNU are then superimposed on top of this.

[0216] [3-2. Conditions for obtaining visual effects] Next, in this third embodiment, for the decorative medium MC3 on which decorative printing was performed by the image forming device 301, focusing on the surface roughness of the medium M, several preliminary evaluation tests were conducted, followed by several evaluation tests, in order to find the conditions for obtaining a good visual effect.

[0217] In these preliminary evaluation tests and evaluation tests, a C941dn (manufactured by Oki Electric Industry Co., Ltd.) was used as the image forming apparatus 301, as in the first and second embodiments. In the preliminary tests, unless otherwise specified, the medium M was a medium having a basis weight (basis weight) of 120 [g / m 2 The "Color Copy 120" (manufactured by Mondi) was used. The medium M used in the evaluation test will be described later.

[0218] [3-2-1. Preliminary Evaluation Test] Regarding the silver toner image PS that constitutes the second layer in the decorative medium MC3, for example, as disclosed in Japanese Patent Application Publication No. 2024-87647, in order to obtain a stable metallic luster, the dots on which the silver toner TSL is placed may be arranged in the shape of fine lines in an image pattern composed of a collection of multiple dots. Hereinafter, such an image pattern will be referred to as a fine line pattern.

[0219] However, if the surface roughness of the medium M is relatively large, this fine line pattern may break down in the silver toner image PS printed on the medium M. In such a case, in the decorative medium MC3 created using the medium M, it may become difficult to distinguish between the decorative area AC and the background area AB, and the color difference ΔE value will also decrease, which may result in a reduced visual effect.

[0220] To avoid the collapse of the fine line pattern in the silver toner image PS of the decorative medium MC3, it is possible to consider a method of increasing the amount of the lower color toner image PNL, which is the first layer, adhered to the paper surface. This aims to reduce the surface roughness as seen from the silver toner image PS by filling in the irregularities formed on the surface of the medium M with the color toners that make up the lower color toner image PNL.

[0221] Therefore, in the third embodiment, as a preliminary evaluation test, two types of comparison media MQ3 were created as two comparative examples (Comparative Example 31 and Comparative Example 32), and one type of evaluation media ME3 was created as Example 31.

[0222] In all of Comparative Examples 31 and 32 and Example 31, the medium M used was the same "Color Copy 120" (manufactured by Mondi) as in the first and second embodiments. This "Color Copy 120" had a surface roughness of 20.29 μm. In all of Comparative Examples 31 and 32 and Example 31, the print duties of the decorative area AC and background area AB in the lower color toner image PNL and silver toner image PS, respectively, were set to the same values ​​as in Example 21-1 (FIG. 14).

[0223] On the other hand, in Comparative Examples 31 and 32 and Example 31, the deposition amount of each color toner on the paper surface was adjusted for the lower color toner image PNL, which is the first layer, and the upper color toner image PNU, which is the fourth layer.

[0224] First, in Comparative Example 31, the amount of lower color toner PNL deposited on the paper surface was 0.11 [mg / cm²]. 2 The amount of color toner PNU deposited on the paper surface is set to 0.30 [mg / cm²]. 2 In this case, the transmittance TM of the decorated area AC was 0.79 [%], and the color difference ΔE between the decorated area AC and the background area AB was 1.8. No visual effect was obtained.

[0225] In Comparative Example 31, the color difference ΔE was 1.8, which is thought to be why the thin line pattern in the silver toner image PS collapsed and no visual effect was obtained. In other words, in Comparative Example 31, it is thought that the amount of the lower color toner image PNL attached to the paper surface was too small compared to the surface roughness of the medium M.

[0226] Next, in Comparative Example 32, the amount of lower color toner PNL deposited on the paper surface was 0.13 [mg / cm²]. 2 The amount of color toner PNU deposited on the paper surface was increased to 0.30 [mg / cm²]. 2 The setting was left as is. In this case, the transmittance TM increased to 0.93[%], and the color difference ΔE increased to 5.6. However, no visual effect was obtained.

[0227] In this comparative example 32, compared to comparative example 31, the amount of lower color toner image PNL deposited on the paper surface was increased, which is presumed to have resulted in a better formation of fine line patterns in the silver toner image PS, thus increasing the color difference ΔE to 5.6. However, in this case, the color difference ΔE is excessive, making the decorative area AC more visible than necessary, thus preventing the desired visual effect from being achieved.

[0228] Therefore, in the following example 31, the amount of lower color toner PNL deposited on the paper surface was set to 0.13 [mg / cm²]. 2 On the other hand, the amount of color toner PNU deposited on the paper surface is 0.24 [mg / cm²]. 2 The transmittance TM decreased to 0.69[%], and the color difference ΔE decreased to 2.4. As a result, a visual effect was obtained in this example 31.

[0229] These preliminary evaluation tests revealed a general direction for the decorative medium MC3: when the color difference ΔE is insufficient due to the surface roughness of medium M, increasing the amount of lower color toner image PNL on the paper surface and decreasing the amount of upper color toner image PNU on the paper surface can appropriately increase the color difference ΔE and achieve a visual effect.

[0230] [3-2-2. Evaluation Test] Based on the results of these preliminary evaluation tests, the evaluation tests focused on the relationship between the surface roughness of the medium M and the amount of adhesion on the paper surface of each of the lower color toner image PNL and the upper color toner image PNU.

[0231] In this evaluation test, the ratio of the adhesion amounts of the lower color toner image PNL and the upper color toner image PNU on the paper surface was changed while keeping the total value of both roughly constant, based on the results of Example 31. Therefore, for the adhesion amounts on the paper surface, the ratio of the adhesion amount of the lower color toner image PNL on the paper surface to the adhesion amount of the upper color toner image PNU on the paper surface (hereinafter referred to as the color toner adhesion ratio RN) was used as an index.

[0232] In this evaluation test, three types of media M with different surface roughness were prepared as three examples (Examples 32, 33, and 34), and multiple evaluation media ME3 were created.The color toner adhesion ratio RN of each evaluation medium ME3 was varied, and the transmittance TM and color difference ΔE of each were measured and calculated, and the presence or absence of a visual effect was also determined.

[0233] First, in Example 32, as in the first and second embodiments, "Color Copy 120" (manufactured by Mondi) was used as the medium M. As described above, the surface roughness Rz of this "Color Copy 120" was 20.29 μm. In Example 32, ten types of evaluation media ME3 with different color toner adhesion ratios RN were created by adjusting the adhesion amounts on the paper surface of the upper color toner image PNU and the lower color toner image PNL. Specifically, the color toner adhesion ratios RN of the evaluation media ME3 were 0.89, 0.87, 0.86, 0.82, 0.81, 0.63, 0.61, 0.51, 0.41, and 0.40, respectively.

[0234] Next, in Example 33, "Excellent Gloss A4" (manufactured by OKI Electric Industry Co., Ltd.) was used as the medium M. This "Excellent Gloss A4" has a weighing capacity of 128 g / m². 2The surface roughness Rz was 9.9 [μm]. In this Example 33, ten different evaluation media ME3 with varying color toner adhesion ratios RN were created by adjusting the amount of toner deposited on the paper surface in the upper color toner image PNU and the lower color toner image PNL. Specifically, the color toner adhesion ratios RN for each evaluation media ME3 were 0.77, 0.76, 0.69, 0.68, 0.62, 0.53, 0.47, 0.41, 0.39, and 0.38, respectively.

[0235] Next, in Example 34, "OS coated paper W" (manufactured by Fujifilm Business Innovation Co., Ltd.) was used as the medium M. This "OS coated paper W" has a basis weight of 127 [g / m 2 The surface roughness Rz was 2.93 [μm]. In this Example 34, ten different evaluation media ME3 with varying color toner adhesion ratios RN were created by adjusting the amount of toner deposited on the paper surface in the upper color toner image PNU and the lower color toner image PNL. Specifically, the color toner adhesion ratios RN for each evaluation media ME3 were 0.63, 0.59, 0.58, 0.48, 0.47, 0.44, 0.39, 0.38, 0.35, and 0.34, respectively.

[0236] In addition, for each evaluation medium ME3, the printing duties of the decorative area AC and the background area AB in the lower color toner image PNL were fixed to 50[%] and 31[%], respectively, and the printing duties of the decorative area AC and the background area AB in the silver toner image PS were fixed to 81[%] and 100[%], respectively.

[0237] The surface roughness Rz, color toner adhesion ratio RN, transmittance TM, and color difference ΔE values, as well as the visual effect evaluation results, for Examples 32, 33, and 34 are summarized in FIGS. 23, 24, and 25, respectively.

[0238] Furthermore, in addition to the plots of the relationship between the transmittance TM and the color difference ΔE of the decorated area AC in the second embodiment (FIG. 21), the relationships between the transmittance TM and the color difference ΔE in Examples 32, 33, and 34 were plotted, resulting in the graph shown in FIG. 26. In FIG. 26, as in FIG. 21, circles indicate results that had a visual effect, and triangles indicate results that did not have a visual effect.

[0239] 26, it can be seen that the plotted areas (circles) where the visual effect is obtained form rectangular ranges of different sizes in the portions where the transmittance TM of the decorative area AC is 0.72% or more and the portions where it is 0.72% or less. Therefore, in the image forming device 301, the range formed by combining two rectangles, the first visual effect range AR1 and the second visual effect range AR2 in FIG. 26, is defined as the range where the visual effect is obtained (in this embodiment, this is called the visual effect range or visual effect condition).

[0240] Of these, the first visual effect range AR1 is the range in which the transmittance TM of the decorative area AC is 0.22% or more and 0.72% or less, and the color difference ΔE is 1.97 or more and 11.36 or less. The second visual effect range AR2 is the range in which the transmittance TM of the decorative area AC is 0.72% or more and 0.98% or less, and the color difference ΔE is 1.97 or more and 5.36 or less.

[0241] Furthermore, when creating the decorative medium MC2 in the image forming device 301, the control unit 303 controls the printing duty of the decorative area AC and the background area AB in the lower color toner image PNL and the silver toner image PS to adjust the transmittance TM of the decorative area AC to be within the first visual effect range AR1 or the second visual effect range AR2, i.e., to be 0.22% or more and 0.98% or less.

[0242] Next, we focus on the surface roughness Rz of the medium M. As shown in Figure 23, in Example 32, visual effects were obtained in Examples 32-5 to 32-9, but not in Examples 32-1 to 32-4 and Example 32-10. That is, when the surface roughness Rz of the medium M was 20.29 [μm], visual effects were obtained in the range of color toner adhesion ratio RN from 0.81 to 0.41. From this, it can be concluded that when the surface roughness Rz of the medium M is 20.29 [μm], the probability of obtaining a visual effect with the medium M is highest when the color toner adhesion ratio RN is 0.61, which is the center of this range.

[0243] Furthermore, as shown in Figure 24, in Example 33, visual effects were obtained in Examples 33-4 to 33-9, but not in Examples 33-1 to 33-3 and Example 33-10. In other words, when the surface roughness Rz of the medium M was 9.90 [μm], visual effects were obtained in the range of color toner adhesion ratio RN from 0.68 to 0.39. From this, it can be concluded that when the surface roughness Rz of the medium M is 9.90 [μm], the probability of obtaining visual effects with the medium M is highest when the color toner adhesion ratio RN is 0.53, which is the center of this range.

[0244] Furthermore, as shown in Figure 25, in Example 34, visual effects were obtained in Examples 34-3 to 34-9, but not in Examples 34-1, 34-2, and 34-10. In other words, when the surface roughness Rz of the medium M was 2.93 [μm], visual effects were obtained in the range of color toner adhesion ratio RN from 0.58 to 0.35. From this, it can be concluded that when the surface roughness Rz of the medium M is 2.93 [μm], the probability of obtaining visual effects with the medium M is highest when the color toner adhesion ratio RN is 0.47, which is the center of this range.

[0245] Here, the relationship between the surface roughness Rz of the medium M obtained in Examples 32, 33, and 34 and the color toner adhesion ratio RN was approximated as a linear function, and the following equation (5) was obtained.

[0246]

number

[0247] In equation (5), the coefficient multiplied by the surface roughness Rz is a positive value. From this, we can see that for the decorative medium MC3, as the value of the surface roughness Rz increases, the value of the color toner adhesion ratio RN also increases, that is, the ratio of the lower color toner image PNL increases.

[0248] Therefore, in the image forming apparatus 301, when the surface roughness Rz of the medium M is known, the color toner adhesion ratio RN appropriate for the surface roughness Rz is calculated using this formula (5). Then, in the image forming apparatus 301, when creating a decorative medium MC3 using the medium M, the adhesion amounts of the upper color toner image PNU and the lower color toner image PNL on the medium are set to values ​​based on this color toner adhesion ratio RN.

[0249] Therefore, in the image forming apparatus 301, for example, the color toner adhesion ratio RN32 in a predetermined medium M32 with a relatively large surface roughness Rz value is larger than the color toner adhesion ratio RN31 in a predetermined medium M31 with a relatively small surface roughness Rz value.

[0250] [3-3. Decorative media printing process] Next, we will describe the printing process for a decorative medium MC3 when an image forming apparatus 301 prints an image on the medium M that produces a visual effect.

[0251] Based on the results of the evaluation tests described above, when creating decorative medium MC3, the image forming apparatus 301 prints a lower color toner image PNL, a silver toner image PS, a transparent toner image PC, and an upper color toner image PNU in a sequentially overlapping manner, in the same manner as when creating decorative medium MC1 and MC2 in the first and second embodiments.

[0252] Specifically, the image forming apparatus 301 stores in advance in a data conversion table 395 (FIG. 3) in the storage unit 381 information for realizing a bottom color toner image PNL, a silver toner image PS, a clear toner image PC, and a top color toner image PNU that satisfy the visual effect conditions. The image forming apparatus 301 also stores in advance in the storage unit 381 information for performing the calculation of the above-mentioned equation (5).

[0253] When the control unit 303 (Figure 3) of the image forming device 301 receives print data from the upper device 100 via the interface unit 82, the print control unit 80 reads and executes the decorative medium printing program from the memory unit 381, starts the decorative medium printing processing procedure RT3 shown in Figure 27, which corresponds to Figure 12, and proceeds to the first step SP31.

[0254] In step SP31, the control unit 303 causes the user to input the value of the surface roughness Rz of the medium M via the display operation unit 4 (FIG. 1), and then proceeds to the next step SP32.

[0255] In step SP32, the control section 303 reads out equation (5) from the storage section 381, and calculates the color toner adhesion ratio RN by substituting the input value of the surface roughness Rz, and then proceeds to the next step SP33.

[0256] In step SP33, the control unit 303 calculates the adhesion amounts on the medium of the lower color toner image PNL and the upper color toner image PNU based on the calculated color toner adhesion ratio RN, and further calculates the development biases corresponding to each adhesion amount on the medium and stores them in the memory unit 381, and then proceeds to the next step SP34.

[0257] Thereafter, the control unit 303 performs steps SP34 to SP43 similar to steps SP1 to SP10 of the decorative medium printing process procedure RT1 (FIG. 12). However, in step SP36, the lower color toner image PNL is formed with the developing bias set to the value calculated in step SP33. Also, in step SP42, the upper color toner image PNU is formed with the developing bias set to the value calculated in step SP33.

[0258] After completing the process of step SP43, the control section 303 proceeds to step SP44 and ends the decorative medium printing process procedure RT3.

[0259] [3-4. Effects, etc.] In the above configuration, the image forming apparatus 301 according to the third embodiment creates a decorated medium MC3 by printing a lower color toner image PNL and a silver toner image PS having a background area AB and a decorated area AC, a transparent toner image PC and an upper color toner image PNU, in a sequentially superimposed manner, on the surface of a blank medium M.

[0260] This allows the image forming device 301 to provide a good visual effect in which the decorative area AC appears and disappears on the surface of the decorative medium MC3 when the position and posture of the decorative medium MC3 are changed in various ways by the observer, and the relative positions and angles of the observer's viewpoint VP, light source LS, and the decorative medium MC3 change in various ways.

[0261] In particular, the image forming apparatus 301 calculates the color toner adhesion ratio RN according to the surface roughness Rz of the medium M used, and adjusts the development bias when forming the lower color toner image PNL and the development bias when forming the upper color toner image PNU based on this. As a result, the image forming apparatus 301 can maintain a roughly constant amount of adhesion on the medium, combined with the upper color toner image PNU, while appropriately filling in the unevenness formed on the surface of the medium M with the lower color toner image PNL to bring it closer to a flat state.

[0262] As a result, the decorative medium MC3 created by the image forming apparatus 301 can provide the observer with a visual effect in which the decorative area AC appears and disappears depending on changes in the viewing angle.

[0263] Furthermore, in the image forming apparatus 301, based on the results of preliminary evaluation tests, when creating the decorative medium MC3, if the surface roughness Rz of the medium M is relatively large, the amount of lower color toner image PNL deposited on the medium is increased, as well as the amount of upper color toner image PNU deposited on the medium is reduced. As a result, the image forming apparatus 301 can keep the transmittance TM and color difference ΔE within an appropriate range in the created decorative medium MC3, and as a result, a visual effect can be obtained.

[0264] In other respects as well, the image forming apparatus 301 according to the third embodiment can achieve the same effects as the image forming apparatus 1 according to the first embodiment and the image forming apparatus 201 according to the second embodiment.

[0265] [4. Other Embodiments] In the first embodiment described above, a transparent toner image PC was provided between the silver toner image PS and the upper color toner image PNU in the decorative medium MC1. However, the present invention is not limited to this, and the transparent toner image PC may be omitted from the decorative medium MC1, for example, when the difference in print duty cycle between the decorative area AC and the background area AB in the silver toner image PS is relatively small. The same applies to the second and third embodiments.

[0266] In the first embodiment described above, a transparent toner image PC is provided as a third layer between the silver toner image PS (second layer) and the upper color toner image PNU (fourth layer) in the decorative medium MC1. However, the present invention is not limited to this. For example, the transparent toner image PC may be provided as a first layer as in the decorative medium MC4 shown in FIG. 28(A), or as a second layer as in the decorative medium MC5 shown in FIG. 28(B), or as a fourth layer as in the decorative medium MC6 shown in FIG. 28(C). The same applies to the second and third embodiments.

[0267] Furthermore, in the first embodiment described above, in the silver toner image PS of the decorative medium MC1, the print duty of the background area AB is set to 100% and the print duty of the decorative area AC is set to a lower value. However, the present invention is not limited to this. For example, the print duty of the background area AB may be set to any value lower than 100%, and the print duty of the decorative area AC may be set to an even lower value. Alternatively, for example, the print duty of the decorative area AC may be set to 100% and the print duty of the background area AB may be set to an even lower value. In short, by varying the print duty between the decorative area AC and the background area AB to some extent, a visual effect in which the decorative area AC appears and disappears may be achieved. The same applies to the second and third embodiments.

[0268] Furthermore, in the third embodiment described above, the visual effect conditions are defined as the ranges of the transmittance TM and the color difference ΔE of the decorative area AC so as to correspond to the entire range formed by combining the first visual effect area AR1 and the second visual effect area AR2 in FIG. 26 . Specifically, the range corresponding to the first visual effect area AR1 is defined as the range in which the transmittance TM of the decorative area AC is 0.22% or more and 0.72% or less, and the color difference ΔE is 1.97% or more and 11.36 or less. Furthermore, the range corresponding to the second visual effect area AR2 is defined as the range in which the transmittance TM of the decorative area AC is 0.72% or more and 0.98% or less, and the color difference ΔE is 1.97% or more and 5.36 or less. However, the present invention is not limited to this, and a range corresponding to a portion of the range formed by combining the first visual effect area AR1 and the second visual effect area AR2 may be defined as the visual effect condition. Specifically, for example, the visual effect condition may be a range in which the transmittance TM of the decorative area AC is 0.22% or more and 0.72% or less and the color difference ΔE is 1.97 or more and 11.36 or less for the portion corresponding to only the first visual effect range AR1. Alternatively, for example, the visual effect condition may be a range in which the transmittance TM of the decorative area AC is 0.72% or more and 0.98% or less and the color difference ΔE is 1.97 or more and 5.36 or less for the portion corresponding to only the second visual effect range AR2. Alternatively, for example, the visual effect condition may be a range in which the transmittance TM of the decorative area AC is 0.22% or more and 0.98% or less and the color difference ΔE is 1.97 or more and 5.36 or less for the portion corresponding to only the second visual effect range AR2.

[0269] Furthermore, in the first embodiment described above, the lower color toner image PNL and the upper color toner image PNU are both images (solid images) in which the cyan (C) print duty is 100%. However, the present invention is not limited to this, and the lower color toner image PNL and the upper color toner image PNU may be various other colors. In this case, they may be a single color (e.g., magenta or black) composed of one toner color, or a mixed color (e.g., green or purple) composed of multiple toner colors. Furthermore, when black is used, it may be black using only black toner, or black composed of multiple mixed colors (so-called process black). However, in these cases, it is desirable to use a color with as low light transmittance as possible, i.e., a relatively dark color, so that the decorative area AC is not more visible than necessary. The same applies to the second and third embodiments.

[0270] Furthermore, in the first embodiment described above, the lower color toner image PNL and the upper color toner image PNU are described as having the same color. However, the present invention is not limited to this. For example, the lower color toner image PNL and the upper color toner image PNU may have colors that are considered to be substantially the same, even if there is a slight difference. Specifically, for example, if the color difference ΔE between the lower color toner image PNL and the upper color toner image PNU is 3.2 or less, the colors are generally recognized as the same color, and if it is 1.6 or less, the colors are so close that the difference is within the error range of a color measurement device. The same applies to the second and third embodiments.

[0271] Furthermore, in the third embodiment described above, the total amount of adhesion of the lower color toner image PNL and the upper color toner image PNU on the paper surface is set to be approximately constant. However, the present invention is not limited to this. For example, the amount of adhesion of the lower color toner image PNL on the paper surface may be increased or decreased depending on the surface roughness Rz of the medium M while maintaining the amount of adhesion of the upper color toner image PNU on the paper surface.

[0272] Furthermore, in the first embodiment described above, the lower layer of the decorative medium MC (FIG. 4) is formed of a silver (SL) toner image PS. However, the present invention is not limited to this, and the toner image P may be formed using a toner T of various colors having brilliance, such as gold or copper. For example, the gold toner T can be produced by partially modifying the manufacturing process of the silver toner TSL described in the first embodiment. Specifically, when adding aluminum powder as a brilliance pigment, the gold toner T can be produced by adding a yellow pigment (e.g., the organic pigment CI Pigment Yellow 180), a magenta pigment (e.g., the organic pigment CI Pigment Red 122), a reddish-orange fluorescent pigment (e.g., FM-34N_Orange (manufactured by Shin-Roi-Hi Co., Ltd.)), and a yellow fluorescent pigment (FM-35N_Yellow (manufactured by Shin-Roi-Hi Co., Ltd.)). Furthermore, the lustrous pigment is not limited to aluminum (Al); various other pigments with lustrous properties may be used, such as pearl pigments (natural mica) and inorganic pigments made from titanium dioxide. The same applies to the second and third embodiments.

[0273] Furthermore, in the first embodiment described above, the image forming apparatus 1 is provided with one image forming unit 10SL that forms a silver toner image, which is a brilliant color. The image forming unit 10SL is used to form a silver toner image PS by varying the print duty between the decorative area AC and the background area AB. However, the present invention is not limited to this. For example, the image forming apparatus 1 may be provided with two silver image forming units 10SL. In this case, for example, one image forming unit 10SL (hereinafter also referred to as the first brilliant image forming unit) may form an image of the background area AB (hereinafter also referred to as the first brilliant image), and the other image forming unit 10SL (hereinafter also referred to as the second brilliant image forming unit) may form an image of the decorative area AC (hereinafter also referred to as the second brilliant image). Alternatively, for example, one image forming unit 10SL may form an image of the entire range combining the background area AB and the decorative area AC, and the other image forming unit 10SL may form only the background area AB in an overlapping manner. This also applies to the second and third embodiments.

[0274] In these cases, it is sufficient that the amount of silver toner TSL deposited per unit area in the silver 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., the amount of exposure, such as brightness or light intensity) may be different between the two image forming units 10SL, or the bias voltages during development and transfer may be different, or these may be combined appropriately. Alternatively, the color or characteristics of the bright color toner may be different between the two image forming units 10SL. The same applies to the second and third embodiments.

[0275] Furthermore, in the first embodiment described above, the fixing temperature in the fixing unit 60 is kept constant (for example, 150°C), and the fixing temperatures for the lower color toner image PNL, silver toner image PS, transparent toner image PC, and upper color toner image PNU are set to be the same. However, the present invention is not limited to this, and various temperatures can be used to fix the lower color toner image PNL, silver toner image PS, transparent toner image PC, and upper color toner image PNU. Specifically, for example, the fixing temperature may be set in the range of 145 to 190°C. Also, for example, the fixing temperature for the transparent toner image PC may be set higher than the fixing temperatures for the silver toner image PS, upper color toner image PNU, and lower color toner image PNL. Specifically, for example, the fixing temperature for the lower color toner image PNL, silver toner image PS, and upper color toner image PNU may be set to 150°C, and the fixing temperature for the transparent toner image PC may be set to 190°C. This increases the degree to which the transparent toner TCL penetrates the decorative area AC in the silver toner image PS. The same applies to the second and third embodiments.

[0276] Furthermore, in the first embodiment described above, as shown in the decorative media printing process procedure RT1 (Figure 12), the lower color toner image PNL, silver toner image PS, transparent toner image PC, and upper color toner image PNU are printed by sequentially overlapping them while fixing each layer. However, the present invention is not limited to this, and for example, with respect to the silver toner image PS and transparent toner image PC, the silver toner image PS and the transparent toner image PC may be superimposed on the intermediate transfer belt 34 and then transferred and fixed together to the medium M by the secondary transfer unit 39. In short, the images should be formed by superimposing them appropriately according to the relationship between the alignment order of each color in the front-to-back direction of the image forming unit 10 and the order in which each color is superimposed on the medium M. The same applies to the second and third embodiments.

[0277] Furthermore, in the first embodiment described above, each time each layer of the lower color toner image PNL, the silver toner image PS, the clear toner image PC, and the upper color toner image PNU is printed on the medium M, the re-feeding unit 66 returns the medium M to the transport path W without turning it over, and the next layer is printed. However, the present invention is not limited to this. For example, each time each layer is printed, the medium M may be ejected and the user may be prompted to reset the medium M in the paper cassette 41. In this case, the configuration can be simplified by omitting the re-feeding unit 66 from the image forming apparatus 1. The same applies to the second and third embodiments.

[0278] Furthermore, in the first embodiment described above, a form in which white fine paper is used as the medium M has been described. However, the present invention is not limited to this, and various colored fine paper such as blue or red may be used as the medium M, or paper other than fine paper such as cardboard or coated paper may be used as the medium M. In short, any sheet-like object onto which a toner image can be transferred and fixed can be used as the medium M. The same applies to the second and third embodiments.

[0279] Furthermore, in the first embodiment described above, the image forming apparatus 1 (FIG. 1) is described as having 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 fewer or six or more image forming units 10. For example, when six image forming units 10 are provided, black (K), cyan (C), magenta (M), and yellow (Y) can be used as normal colors, silver (SL) can be used as a brilliant color, and a transparent color (CL) can also be used. The same applies to the second and third embodiments.

[0280] Furthermore, in the first embodiment described above, the yellow (Y) image forming unit 10 used in a typical color printer is omitted and replaced with a transparent (CL) image forming unit 10. However, the present invention is not limited to this. For example, the magenta (M) image forming unit 10 may be omitted and replaced with a transparent (CL) image forming unit 10. Alternatively, one of the normal colors (i.e., a color that is neither a brilliant color nor a transparent color) may be omitted and replaced with a transparent (CL) image forming unit 10. The same applies to the second and third embodiments.

[0281] Furthermore, in the first embodiment described above, the image forming apparatus (FIG. 1) is of a so-called intermediate transfer type, in which 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, in which a toner image formed in each image forming unit 10 is directly transferred to the medium M. The same applies to the second and third embodiments.

[0282] Furthermore, in the first embodiment described above, the present invention has been described as being applied to an image forming apparatus 1 that forms images using a developer used in a one-component development system. However, the present invention is not limited to this, and may also be applied to an image forming apparatus that forms images using a developer used in a two-component development system 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 system, particles containing a glitter pigment, a binder resin, and an external additive, or a powder formed by aggregation of these particles, are defined as glitter toner or glitter developer. The same applies to the second and third embodiments.

[0283] Furthermore, in the first embodiment described above, the decorative medium MC1 is created using an image forming apparatus 1 that prints an image on a medium M using an electrophotographic method that uses toner as a developer. However, the present invention is not limited to this. The decorative medium MC1 may also be created using various image forming apparatuses that form images on a medium using various well-known methods, such as an inkjet method or a thermal transfer method that uses ink as a developer. Furthermore, the developer is not limited to toner or ink. Various colorants may be used as the developer as long as they exhibit the colors described in the above-described embodiment. Note that the image forming unit in the inkjet method includes at least a storage unit that stores ink of each color and a discharge unit that discharges the ink stored in the storage unit. Furthermore, a transparent developer in the inkjet method refers to an ink that does not contain a colorant in the water, organic solvent, etc. that constitutes the ink. A glittering developer may be an ink that contains a pearl pigment such as silicon dioxide or titanium oxide, or a metal pigment such as aluminum, silver, gold, or nickel, as a colorant in the water, organic solvent, etc. that constitutes the ink. Furthermore, when measuring the amount of adhesion per unit area in the inkjet method, the difference in weight on the medium before and after ink is discharged may be measured. The same applies to the second and third embodiments.

[0284] Furthermore, in the first embodiment described above, information for creating a decorative medium MC1 with a visual effect is stored in advance in a data conversion table 95 (FIG. 3) provided in the storage unit 81 of the image forming apparatus 1, and the decorative medium printing process procedure RT1 (FIG. 12) executed by the control unit 3 forms and sequentially prints each layer based on that information. However, the present invention is not limited to this. For example, the information may be stored in advance in the host device 100, and the printer driver may reference that information to generate print data, which may then be transmitted to the image forming apparatus 1. In this case, the control unit 3 of the image forming apparatus 1 need not perform processing based on that information; it simply forms and sequentially prints the images for each layer. The same applies to the second and third embodiments.

[0285] Furthermore, in the first embodiment described above, the present invention has been described as being applied to an image forming apparatus 1 that is a single-function printer. However, the present invention is not limited to this, and may be applied to an image forming apparatus having various other functions, such as an MFP (Multi Function Peripheral) that has the functions of a copier or facsimile machine. The same applies to the second and third embodiments.

[0286] Furthermore, the present invention is not limited to the above-described embodiments and other embodiments. That is, the scope of application of the present invention also extends to embodiments in which the above-described embodiments are combined in part or in whole with any of the above-described other embodiments. The scope of application of the present invention also extends to embodiments in which part of the configuration described in any of the above-described embodiments and other embodiments is extracted and used as part of the configuration of any of the above-described embodiments and other embodiments, or in which part of the extracted configuration is added to any of the above-described embodiments.

[0287] Furthermore, in the first embodiment described above, the image forming apparatus 1 is configured as an image forming apparatus using an image forming unit 10C as a color image forming section, an image forming unit 10SL as a glossy image forming section, and a control unit 3 as a control section. However, the present invention is not limited to this, and the image forming apparatus may be configured by a color image forming section, a glitter image forming section, and a control section having various other configurations. [Industrial Applicability]

[0288] This invention can be used when forming an image on a medium using an electrophotographic method with a developer containing a metal pigment.

[0289] The various aspects of this disclosure are summarized below as an appendix. (Appendix 1) A color image forming unit capable of forming a color image using a colored imaging agent, A luminous image forming unit capable of forming a luminous image using a luminous imaging agent, a control unit that controls the glossy image forming unit and the color image forming unit in accordance with print data; Equipped with The control unit causing the color image forming unit to form a first image, which is the color image; forming a second image, which is a glossy image having a first region formed with a first formation amount per unit area and a second region formed with a second formation amount per unit area that is smaller than the first formation amount, on the first image in the glossy image forming unit; The color image forming unit is controlled so as to obtain a printed matter in which a third image, which is the color image, is formed on the second image. An image forming apparatus characterized by: (Appendix 2) A transparent image forming section capable of forming a transparent image using a transparent developer Further comprising: the control unit controls the transparent image forming unit in addition to the glossy image forming unit and the color image forming unit in accordance with the print data; The printed matter is The fourth image, which is the transparent image, is formed so as to be superimposed on any one of the first image, the second image, and the third image. 2. The image forming apparatus according to claim 1, (Appendix 3) The printed matter is The fourth image is formed between the second image and the third image. 3. The image forming apparatus according to claim 2, (Appendix 4) the first image has a third region formed at a third formation amount per unit area and a fourth region formed at a fourth formation amount per unit area that is smaller than the third formation amount, The first region of the second image is formed in a position overlapping the fourth region of the first image, and the second region of the second image is formed in a position overlapping the third region of the first image. An image forming apparatus as described in any of Appendix 1 to Appendix 3, characterized by the above. (Appendix 5) The second image is formed so that the color difference between the first region and the second region is 1.97 to 11.36, and the transmittance of the first region to white light is 0.22% to 0.72%. An image forming apparatus as described in any of Appendix 1 to Appendix 4, characterized by the above. (Appendix 6) The surface roughness of the printed material is between 2.93 [μm] and 20.29 [μm]. An image forming apparatus as described in any of Appendix 1 to Appendix 5, characterized by the above. (Appendix 7) The weight of the medium is 120 [g / m 2 ] or more 300[g / m 2 ] or less An image forming apparatus as described in any of Appendix 1 to Appendix 6, characterized by the above. (Appendix 8) The control unit The first image is formed on a first medium having a first surface roughness at a fifth formation amount per unit area, and the first image is formed on a second medium having a second surface roughness greater than the first surface roughness at a sixth formation amount greater than the fifth formation amount per unit area. An image forming apparatus as described in any of Appendix 1 to Appendix 7, characterized by the above. (Appendix 9) The control unit The third image is formed on the first medium at a seventh formation amount per unit area, and the third image is formed on the second medium at an eighth formation amount per unit area that is smaller than the seventh formation amount. An image forming apparatus as described in any of Appendix 1 to Appendix 8, characterized by the above. (Appendix 10) The color image forming unit includes: The colored image is formed using at least one of the following: black toner, yellow toner, magenta toner, and cyan toner. An image forming apparatus as described in any of Appendix 1 to Appendix 9, characterized by the above. (Appendix 11) The first and third images are the same color. 11. The image forming apparatus according to claim 1, wherein: (Appendix 12) The color image forming unit includes a toner container that contains color toner as the color developer, and a carrier container that contains a carrier. 12. The image forming apparatus according to claim 1, wherein: (Appendix 13) forming a first image, which is a color image, on a medium by a color image forming unit capable of forming a color image using a color developer; A step of forming a second image, which is a luminous image, on the first image using a luminous image forming unit capable of forming a luminous image with a luminous imaging agent, the second image having a first region formed with a first forming amount per unit area and a second region formed with a second forming amount smaller than the first forming amount per unit area. forming a third image, which is the color image, on the second image by the color image forming unit; An image forming method comprising the steps of: (Appendix 14) forming a third image, which is a color image, on an intermediate transfer member by a color image forming unit capable of forming a color image using a color developer; A step of forming a second image, which is a luminous image, on the third image using a luminous image forming unit capable of forming a luminous image with a luminous imaging agent, the second image having a first region formed with a first forming amount per unit area and a second region formed with a second forming amount smaller than the first forming amount per unit area. forming a first image, which is the color image, on the second image by the color image forming unit; transferring the third image, the second image, and the first image in a superimposed state from the intermediate transfer member to a medium; An image forming method comprising the steps of: (Appendix 15) The medium itself; a first image formed as a color image on the medium; a second image formed on the first image as a glossy image having a first region formed with a first formation amount per unit area and a second region formed with a second formation amount per unit area smaller than the first formation amount; On the second image, the third image formed as the colored image and An image-forming medium characterized by comprising the following: [Explanation of symbols]

[0290] 1, 201, 301...Image forming apparatus, 3, 203, 303...Control unit, 4...Display operation unit, 10, 10C, 10SL...Image forming unit, 34...Intermediate transfer belt, 39...Secondary transfer unit, 60...Fixing unit, 66...Re-transport unit, 70...Paper discharge unit, 80...Printing control unit, 81, 281, 381...Storage unit, 95, 295, 395...Data conversion table, 100...Host unit, AB...Background area, AC...Decoration area, D...Print duty cycle, M...Media, MC...Decoration media, ME...Evaluation media, MQ...Comparison media, P...Toner image, PC...Transparent toner image, PN...Color toner image, PNL...Lower color toner image, PNU...Upper color toner image, PS...Silver toner image, RN...Color toner adhesion ratio, T...Toner, TM...Transmittance, ΔE...Color difference.

Claims

1. a color image forming unit capable of forming a color image using a color developer; a glitter image forming unit capable of forming a glitter image using a glitter developer; a control unit that controls the glossy image forming unit and the color image forming unit in accordance with print data; Equipped with The printed matter formed under the control of the control unit is a first image, which is the color image, is formed on a medium; a second image, which is the glossy image, is formed on the first image, the second image having a first region formed with a first formation amount per unit area and a second region formed with a second formation amount per unit area that is smaller than the first formation amount; The third image, which is the color image, is formed on the second image. An image forming apparatus characterized by:

2. A transparent image forming section capable of forming a transparent image using a transparent developer Further comprising: the control unit controls the transparent image forming unit in addition to the glossy image forming unit and the color image forming unit in accordance with the print data; The printed matter is The fourth image, which is the transparent image, is formed so as to be superimposed on any one of the first image, the second image, and the third image.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. The printed matter is The fourth image is formed between the second image and the third image.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. the first image has a third region formed with a third formation amount per unit area and a fourth region formed with a fourth formation amount per unit area that is smaller than the third formation amount, The first region of the second image is formed at a location overlapping the fourth region of the first image, and the second region of the second image is formed at a location overlapping the third region of the first image.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. The second image is formed so that a color difference between the first region and the second region is 1.97 to 11.36, and a transmittance of white light in the first region is 0.22% to 0.72%.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

6. The control unit The first image is formed on a first medium having a first surface roughness at a fifth formation amount per unit area, and the first image is formed on a second medium having a second surface roughness greater than the first surface roughness at a sixth formation amount greater than the fifth formation amount per unit area.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

7. The control unit The third image is formed on the first medium at a seventh formation amount per unit area, and the third image is formed on the second medium at an eighth formation amount per unit area that is smaller than the seventh formation amount.

7. The image forming apparatus according to claim 6, wherein the image forming apparatus is a recording medium.

8. The color image forming unit includes: The color image is formed using at least one of black toner, yellow toner, magenta toner, and cyan toner.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. The first image and the third image are the same color.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

10. The color image forming unit includes a toner container that contains color toner as the color developer, and a carrier container that contains a carrier.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

11. a storage unit that stores a conversion table for changing the formation amount per unit area of ​​the print data; Further comprising: The control unit forms the printed matter based on the print data whose formation amount has been changed by the conversion table.

11. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

12. a color image forming unit capable of forming a color image using a color developer; a glitter image forming unit capable of forming a glitter image using a glitter developer; a control unit that controls the glossy image forming unit and the color image forming unit in accordance with print data; Equipped with The control unit forming a first image, which is the color image, in the color image forming unit; forming a second image, which is a glossy image having a first region formed with a first formation amount per unit area and a second region formed with a second formation amount per unit area that is smaller than the first formation amount, on the first image in the glossy image forming unit; The color image forming unit is controlled so as to obtain a printed matter in which a third image, which is the color image, is formed on the second image. An image forming apparatus characterized by:

13. forming a third image, which is a color image, on an intermediate transfer member by a color image forming section capable of forming a color image using a color developer; forming, on the third image by a glitter image forming unit capable of forming a glitter image using a glitter developer, a second image which is the glitter image having a first region formed with a first formation amount per unit area and a second region formed with a second formation amount per unit area which is smaller than the first formation amount; forming a first image, which is the color image, on the second image by the color image forming unit; transferring the third image, the second image, and the first image in a superimposed state from the intermediate transfer member to a medium; An image forming method comprising the steps of:

Images