Image forming apparatus

Abstract

To achieve both metallic glossiness and the hue of an image.SOLUTION: An image forming apparatus 1 is provided with: a first image forming section 90 that can form a silver developer image IS with sliver developer; a second image forming section 91 including at least one image forming unit 10 that can form a black developer image IB with color developer; and a print control section 3 that controls the operation of the first image forming section 90 and second image forming section 91 according to received print data. In causing the first image forming section 90 to form the silver developer image IS on a sheet P based on the print data, the print control section 3 causes the second image forming section 91 to form the black developer image IB outside a formation area of the silver developer image IS.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, and is particularly suitable for application to, for example, an electrophotographic printer. [Background technology]

[0002] Conventionally, image forming devices (also called printers) that are widely used perform printing by forming a developer image (also called a toner image) using an image forming unit based on an image supplied from a computer device or the like, transferring it to a medium such as paper, and fixing it by applying heat and pressure.

[0003] Furthermore, some developers contain luminous pigments such as aluminum, as seen in silver developers, for purposes such as providing luminosity. In addition, some image forming apparatuses can produce printed materials with high luminosity (FI value) by specifying the weight-average molecular weight of the silver developer, the size of the luminous pigment, and the content of the luminous pigment in the silver developer (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-113783 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In such image forming apparatuses, it is desirable to improve print quality by achieving a balance between metallic luster and color accuracy in the printed image.

[0006] This invention was made with the above points in mind, and aims to propose an image forming apparatus that can achieve both metallic luster and image color. [Means for solving the problem]

[0007] To solve these problems, the present invention provides an image forming apparatus comprising: a first image forming unit capable of forming a lustrous developer image using a lustrous developer; a second image forming unit including at least one image forming unit capable of forming a developer image using a non-lustrous developer; and a control unit that controls the operation of the first image forming unit and the second image forming unit according to received print data. A table that converts print data, which includes print data specified to be printed with a glossy developer having a print image density of 100%, into a first print data of a glossy developer image that can be formed by a first image forming unit, and a second print data of a black developer image that can be formed by a second image forming unit. The control unit is equipped with, First When the first image forming unit forms a glossy developer image on the medium based on the print data, outside the area where the glossy developer image is formed Based on the second print data The second image forming unit forms a black developer image. The region of the luminous developer image is made larger than the region of the black developer image in a predetermined area on the medium. I did that.

[0008] This invention suppresses the amount of luminous developer formed on the medium, thereby preventing a decrease in metallic luster (FI value), while also compensating for the image's color (visual reflectance) with a black developer image. [Effects of the Invention]

[0009] According to the present invention, an image forming apparatus that can achieve both metallic luster and image color can be realized. [Brief explanation of the drawing]

[0010] [Figure 1] This is a left side view showing the configuration of an image forming apparatus. [Figure 2] This is a left side view showing the configuration of the image forming unit. [Figure 3] This is a block diagram showing the control configuration of an image forming apparatus. [Figure 4] This figure shows the print pattern of Example 1. [Figure 5] This is an enlarged view showing the print pattern of Example 1. [Figure 6] This is an enlarged view showing the print pattern of Comparative Example 1. [Figure 7] This is an enlarged view showing the print pattern of Comparative Example 2. [Figure 8] It is an enlarged view showing the printing pattern of Comparative Example 3. [Figure 9] It is an enlarged view showing the printing pattern of Comparative Example 4. [Figure 10] It is an enlarged view showing the printing pattern of Comparative Example 5. [Figure 11] It is a diagram showing the measurement area of the developer in the image pattern. [Figure 12] It is a diagram showing the measurement location. [Figure 13] It is a diagram showing the irradiation and reception of light by a variable-angle photometer. [Figure 14] It is a diagram showing streaks. [Figure 15] It is a diagram showing vertical streaks. [Figure 16] It is a diagram showing horizontal bands. [Figure 17] It is a table showing the evaluation results of color unevenness. [Figure 18] It is a table showing the evaluation results of glossiness. [Figure 19] It is a table showing the evaluation results of streaks. [Figure 20] It is a table showing the evaluation results of vertical streaks and horizontal bands. [Figure 21] It is a block diagram showing the functional configuration of the image forming apparatus. [Figure 22] It is an enlarged view showing the printing pattern (1) according to another embodiment. [Figure 23] It is an enlarged view showing the printing pattern (2) according to another embodiment. [Figure 24] It is an enlarged view showing the printing pattern (3) according to another embodiment.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[0012] [[1. Configuration of Image Forming Apparatus]] As shown in Figure 1, the image forming apparatus 1 according to this embodiment is an electrophotographic color printer that forms (i.e., prints) a color image on paper P. Incidentally, the image forming apparatus 1 does not have an image scanner function for reading original documents or a communication function using a telephone line, and is a single-function SFP (Single Function Printer) that only has a printer function.

[0013] The image forming apparatus 1 has various components arranged inside a roughly box-shaped housing 2. For the purposes of this explanation, the rightmost part of Figure 1 will be considered the front of the image forming apparatus 1, and the vertical, horizontal, and front-to-back directions will be defined and explained based on the perspective of viewing this front.

[0014] The image forming apparatus 1 is centrally controlled by the print control unit 3. This print control unit 3 has a CPU (Central Processing Unit) 23 (Figure 3), ROM (Read Only Memory), RAM (Random Access Memory), etc., and performs various processes by reading and executing a predetermined program. The print control unit 3 is also connected wirelessly or by wire to a higher-level device 20 (Figure 3), such as a computer device. When image data representing the image to be printed is provided from this higher-level device 20 and printing of the image data is instructed, the print control unit 3 performs a printing process to form the printed image on the surface of the paper P.

[0015] Inside the housing 2, five image forming units 10K, 10C, 10M, 10Y, and 10S are arranged in order from front to rear on the upper side. Although the image forming units 10K, 10C, 10M, 10Y, and 10S correspond to the respective colors of black (K), cyan (C), magenta (M), yellow (Y), and spot color (S), they are all configured similarly, differing only in color. Also, on the upper side inside the housing 2, an LED (Light Emitting Diode) head 14 (Figure 2) is configured to face the image forming units 10K, 10C, 10M, 10Y, and 10S.

[0016] Black (K), cyan (C), magenta (M), and yellow (Y) are all colors commonly used in color printers (hereinafter referred to as standard colors). Spot colors (S), on the other hand, are special colors such as white, clear (transparent or colorless), and silver. For the sake of explanation, the image forming units 10K, 10C, 10M, 10Y, and 10S will be collectively referred to as image forming unit 10 below.

[0017] As shown in Figure 2, the image forming unit 10 is broadly composed of an image forming main body 11, a developer container 12, and a developer supply unit 13. Incidentally, the image forming unit 10 and each of its constituent parts have sufficient length in the left-right direction, corresponding to the left-right length of the paper P. For this reason, many of the parts have a relatively longer left-right length compared to their front-to-back and up-to-down lengths, and are formed in an elongated shape along the left-right direction.

[0018] The developer container 12 contains developer and is configured to be detachable from the image forming unit 10. When the developer container 12 is attached to the image forming unit 10, it is attached to the image forming body 11 via the developer supply unit 13. Incidentally, the developer container 12 is sometimes called a toner cartridge.

[0019] Incidentally, silver-colored developers use developers containing luminous pigments. For the sake of explanation, silver-colored developers will also be referred to as silver developers below. Yellow, magenta, cyan, and black developers use developers containing organic pigments, such as pigment yellow, pigment cyan, pigment magenta, and carbon black. For the sake of explanation, yellow, magenta, cyan, and black developers will also be referred to collectively as color developers below. Furthermore, below, each of the yellow, magenta, cyan, and black color developers will also be referred to as yellow developer, magenta developer, cyan developer, and black developer, respectively.

[0020] The image forming main unit 11 (Figure 2) incorporates an image forming housing 30, a developer storage space 31, a first supply roller 32, a second supply roller 33, a developing roller 34, a developing blade 35, a photoreceptor drum 36, a charging roller 37, and a cleaning blade 38. Of these, the first supply roller 32, the second supply roller 33, the developing roller 34, the photoreceptor drum 36, and the charging roller 37 are each cylindrical in shape with their central axis aligned in the left-right direction, and are each rotatably supported by the image forming housing 30.

[0021] Incidentally, in the special color (S) image forming unit 10S, a developer container 12 containing a developer of a color previously selected by the user (such as clear, gold, or silver) is attached to the image forming main unit 11 via a developer supply unit 13.

[0022] The developer storage space 31 contains the developer supplied from the developer container 12 via the developer supply unit 13. The first supply roller 32 and the second supply roller 33 each have an elastic layer made of conductive urethane rubber foam or the like formed on their circumferential surfaces. The developing roller 34 has an elastic layer or a conductive surface layer formed on its circumferential surface. The developing blade 35 is made of, for example, a stainless steel plate of a predetermined thickness, and in a slightly elastically deformed state, a portion of it is in contact with the circumferential surface of the developing roller 34.

[0023] The photoreceptor drum 36 has thin-film charge generation layers and charge transport layers sequentially formed on its circumferential surface, allowing it to be charged. The charging roller 37 has a conductive elastic material coated on its circumferential surface, and this surface is in contact with the circumferential surface of the photoreceptor drum 36. The cleaning blade 38 is made of, for example, a thin plate-shaped resin, and in a slightly elastically deformed state, a portion of it is in contact with the circumferential surface of the photoreceptor drum 36.

[0024] The LED head 14 is located above the photoreceptor drum 36 in the image forming body 11. This LED head 14 has multiple light-emitting chips arranged linearly along the left-right direction, and each light-emitting chip is made to emit light according to a light emission pattern based on the image data signal supplied from the print control unit 3 (Figure 1).

[0025] The image forming unit 11 is driven by a motor (not shown) to rotate the second supply roller 33, the developing roller 34, and the charging roller 37 in the direction of arrow R1 (clockwise in the figure), while rotating the first supply roller 32 and the photoreceptor drum 36 in the direction of arrow R2 (counterclockwise in the figure). Furthermore, based on the control of the printing control unit 3, the image forming unit 11 charges the first supply roller 32, the second supply roller 33, the developing roller 34, the developing blade 35, and the charging roller 37 by applying a predetermined bias voltage to each.

[0026] The first supply roller 32 and the second supply roller 33, by being charged, cause the developer in the developer storage space 31 to adhere to their circumferential surfaces, and by rotating, this developer adheres to the circumferential surface of the developing roller 34. The developing blade 35 removes excess developer from the circumferential surface of the developing roller 34, and the developer adheres in a thin film state, and this circumferential surface comes into contact with the circumferential surface of the photoreceptor drum 36.

[0027] Meanwhile, the charging roller 37, while charged, comes into contact with the photoreceptor drum 36, thereby uniformly charging the peripheral surface of the photoreceptor drum 36. The LED head 14 emits light at predetermined time intervals in a light emission pattern based on the image data signal supplied from the print control unit 3 (Figure 1), thereby sequentially exposing the photoreceptor drum 36. As a result, electrostatic latent images are sequentially formed on the peripheral surface of the photoreceptor drum 36 near its upper end.

[0028] Next, the photoreceptor drum 36 rotates in the direction of arrow R2, bringing the area where the electrostatic latent image is formed into contact with the developing roller 34. As a result, developer adheres to the peripheral surface of the photoreceptor drum 36 based on the electrostatic latent image, and a developer image based on the image data is developed. The photoreceptor drum 36 rotates further in the direction of arrow R2, bringing the developer image to the vicinity of the lower end of the photoreceptor drum 36.

[0029] An intermediate transfer section 40 is positioned below each image forming unit 10 within the housing 2 (Figure 1). The intermediate transfer section 40 is equipped with a drive roller 41, a driven roller 42, a backup roller 43, an intermediate transfer belt 44, five primary transfer rollers 45, a secondary transfer roller 46, and a reverse bending roller 47. Of these, the drive roller 41, driven roller 42, backup roller 43, each of the primary transfer rollers 45, secondary transfer rollers 46, and reverse bending roller 47 are all formed in a cylindrical shape with their central axis aligned in the left-right direction, and are rotatably supported by the housing 2.

[0030] The drive roller 41 is located on the rear lower side of the image forming unit 10S and rotates in the direction of arrow R1 when driven by a belt motor (not shown). The driven roller 42 is located on the front lower side of the image forming unit 10K. The upper ends of the drive roller 41 and the driven roller 42 are located at or slightly below the lower end of the photoreceptor drum 36 (Figure 2) in each image forming unit 10. The backup roller 43 is located on the front lower side of the drive roller 41 and on the rear lower side of the driven roller 42.

[0031] The intermediate transfer belt 44 is constructed as an endless belt using a high-resistance plastic film and is stretched to circumfer the drive roller 41, the driven roller 42, and the backup roller 43. Furthermore, in the intermediate transfer section 40, five primary transfer rollers 45 are positioned below the portion of the intermediate transfer belt 44 stretched between the drive roller 41 and the driven roller 42, that is, directly below each of the five image forming units 10, and facing each photoreceptor drum 36 across the intermediate transfer belt 44. A predetermined bias voltage is applied to these primary transfer rollers 45 based on the control of the printing control unit 3.

[0032] The secondary transfer roller 46 is located directly below the backup roller 43 and is biased toward the backup roller 43. In other words, the intermediate transfer section 40 sandwiches the intermediate transfer belt 44 between the secondary transfer roller 46 and the backup roller 43. A predetermined bias voltage is also applied to the secondary transfer roller 46. Hereinafter, the secondary transfer roller 46 and the backup roller 43 will be collectively referred to as the secondary transfer section 49.

[0033] The reverse-bending roller 47 is positioned slightly below the front of the drive roller 41 and slightly behind the upper side of the backup roller 43, biasing the intermediate transfer belt 44 in an upward and forward direction. As a result, the intermediate transfer belt 44 maintains tension between each roller without any slack. In addition, a reverse-bending backup roller 48 is provided at a position above the front of the reverse-bending roller 47, sandwiching the intermediate transfer belt 44.

[0034] The intermediate transfer unit 40 rotates the drive roller 41 in the direction of arrow R1 using driving force supplied from a belt motor (not shown), thereby causing the intermediate transfer belt 44 to travel in the direction of arrow E1. Each primary transfer roller 45 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 developer image that had reached near the lower end on the peripheral surface of the photoreceptor drum 36 (Figure 2) to the intermediate transfer belt 44, and sequentially superimposes the developer images of each color. At this time, the developer images of each color are superimposed on the surface of the intermediate transfer belt 44, starting with the upstream silver (S). By moving this intermediate transfer belt 44, the intermediate transfer unit 40 brings the developer images transferred from each image forming unit 10 to the vicinity of the backup roller 43.

[0035] Incidentally, a transport path W is formed inside the housing 2 (Figure 1) for transporting the paper P. 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 40. Subsequently, the transport path W moves upward, proceeds upward along the rearside of the intermediate transfer section 40 and the image forming unit 10S, 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.

[0036] A first paper feeding section 50 is located near the lower end inside the housing 2 (Figure 1). The first paper feeding section 50 is equipped with a paper cassette 51, a pickup roller 52, a feed roller 53, a retard roller 54, a transport guide 55, and transport roller pairs 56, 57, and 58. Incidentally, the pickup roller 52, feed roller 53, retard roller 54, and transport roller pairs 56, 57, and 58 are all formed in a cylindrical shape with their central axis aligned in the left-right direction.

[0037] The paper cassette 51 is constructed as a hollow rectangular parallelepiped, and stores the paper sheets P inside with their surfaces facing vertically, i.e., stacked. The paper cassette 51 is also detachable from the housing 2.

[0038] The pickup roller 52 is in contact with the vicinity of the front edge of the uppermost surface of the paper P stored in the paper cassette 51. The feed roller 53 is positioned slightly in front of the pickup roller 52. The retard roller 54 is located below the feed roller 53, forming a gap between it and the feed roller 53 that corresponds to the thickness of one sheet of paper P.

[0039] When the first paper feeding unit 50 receives driving force from a paper feeding motor (not shown), it rotates or stops the pickup roller 52, feed roller 53, and retard roller 54 as appropriate. As a result, the pickup roller 52 feeds forward one or more of the top sheets of paper P stored in the paper cassette 51. The feed roller 53 and retard roller 54 feed the top sheet of paper P further forward while blocking the second and subsequent sheets. In this way, the first paper feeding unit 50 feeds the paper P forward one sheet at a time, separating them as it goes.

[0040] The transport guide 55 is positioned in the front lower part of the transport path W, and moves the paper P forward and upward along this transport path W, and then further backward and upward. The transport roller pairs 56 and 57 are positioned near the center and near the upper end of the transport guide 55, respectively, and are driven by a paper feed motor (not shown) to rotate in a predetermined direction. As a result, the transport roller pairs 56 and 57 move the paper P along the transport path W.

[0041] Furthermore, a second paper feeding section 60 is provided in front of the transport roller pair 57 in the housing 2. The second paper feeding section 60 is equipped with a paper tray 61, a pickup roller 62, a feed roller 63, and a retard roller 64, etc. The paper tray 61 is formed in a thin plate shape in the vertical direction, and paper P2 is placed on top of it. Incidentally, the paper tray 61 is equipped with paper P2 that differs in size and paper quality from, for example, the paper P stored in the paper cassette 51.

[0042] The pickup roller 62, feed roller 63, and retard roller 64 are configured similarly to the pickup roller 52, feed roller 53, and retard roller 54 of the first paper feeding unit 50. When the second paper feeding unit 60 receives driving force from a paper feeding motor (not shown), it rotates or stops the pickup roller 62, feed roller 63, and retard roller 64 as appropriate, thereby feeding out the top sheet of paper P2 on the paper tray 61 to the rear while blocking the second sheet and subsequent sheets. Thus, the second paper feeding unit 60 feeds out the paper P2 one sheet at a time to the rear. The fed-out paper P2 is then transported along the transport path W by the transport roller pair 57 in the same way as paper P. For the sake of explanation, paper P2 will not be distinguished from paper P below and will simply be referred to as paper P.

[0043] Incidentally, the rotation of the transport roller pair 57 is appropriately suppressed, and by applying frictional force to the paper P, it corrects the so-called skew, where the side edges of the paper P are inclined relative to the direction of travel, and after the leading and trailing edges are aligned to the left and right, it is fed backward. The transport roller pair 58 is located at a predetermined distance behind the transport roller pair 57, and rotates in the same way as the transport roller pair 56, etc., supplying driving force to the paper P being transported along the transport path W, and causing the paper P to move further backward along the transport path W.

[0044] Behind the transport roller pair 58, the secondary transfer section 49 of the aforementioned intermediate transfer section 40, namely the backup roller 43 and the secondary transfer roller 46, are positioned. In this secondary transfer section 49, the developer image formed in the image forming unit 10 and transferred to the intermediate transfer belt 44 is brought into close proximity as the intermediate transfer belt 44 moves, and a predetermined bias voltage is applied to the secondary transfer roller 46. Therefore, the secondary transfer section 49 transfers the developer image from the intermediate transfer belt 44 to the paper P that has been transported along the transport path W, and then moves it further backward.

[0045] A fixing unit 65 is located behind the secondary transfer unit 49. The fixing unit 65 consists of a heating unit 66 and a pressurizing unit 67, which are arranged opposite each other across the transport path W. The heating unit 66 has a heating belt made of a hollow endless belt, inside which a heat-generating heater and multiple rollers are arranged. The pressurizing unit 67 is formed as a cylindrical pressurizing roller with its central axis aligned in the left-right direction, and its upper surface is pressed against the lower surface of the heating unit 66 to form a nip.

[0046] Based on the control of the print control unit 3, the fixing unit 65 heats the heater of the heating unit 66 to a predetermined temperature and rotates the roller as appropriate to move the heating belt in the direction of arrow R1, and also rotates the pressurizing unit 67 in the direction of arrow R2. Then, when the fixing unit 65 receives the paper P on which the developer image has been transferred by the secondary transfer unit 49, it grips (i.e., nips) it with the heating unit 66 and the pressurizing unit 67, applies heat and pressure to fix the developer image to the paper P, and then feeds it backward.

[0047] A pair of transport rollers 68 is positioned behind the fixing unit 65, and a switching unit 69 is positioned behind that. The switching unit 69 switches the direction of travel of the paper P upwards or downwards according to the control of the print control unit 3. A paper discharge unit 70 is provided above the switching unit 69. The paper discharge unit 70 consists of a transport guide 71 that guides the paper P upwards along the transport path W, and pairs of transport rollers 72, 73, 74, and 75 that face each other across the transport path W.

[0048] Furthermore, a re-transport section 77 is positioned below the switching section 69, the fixing section 65, and the secondary transfer section 49. The re-transport section 77 has transport guides and transport roller pairs (not shown) that constitute the re-transport path U. The re-transport path U starts below the switching section 69, moves downwards, then proceeds forward, and merges with the transport path W downstream of the transport roller pair 57.

[0049] When the print control unit 3 discharges paper P, the switching unit 69 switches the direction of travel of paper P toward the upper paper discharge unit 70. The paper discharge unit 70 transports the paper P received from the switching unit 69 upward and discharges it from the discharge port 76 to the paper discharge tray 2T. When the print control unit 3 returns paper P, the switching unit 69 switches the direction of travel of paper P toward the lower re-transport unit 77. The re-transport unit 77 transports the paper P received from the switching unit 69 to the re-transport path U, and eventually reaches the downstream side of the transport roller pair 57, causing the paper P to be transported again along the transport path W. As a result, the image forming apparatus 1 returns the paper P to the transport path W with the paper surface inverted, enabling so-called double-sided printing.

[0050] In this way, the image forming apparatus 1 forms a developer image using a developer in the image forming unit 10 and transfers it to the intermediate transfer belt 44, transfers the developer image from the intermediate transfer belt 44 to the paper P in the secondary transfer unit 49, and then fixes it in the fixing unit 65, thereby printing an image on the paper P (i.e., forming an image). For the sake of explanation, below, the developer image formed with silver developer will also be called a silver developer image, and the developer image formed with color developer will also be called a color developer image.

[0051] For example, in the image forming apparatus 1, when the image forming unit 10 sequentially transfers a silver developer image using a silver developer and a color developer image using a color developer to the intermediate transfer belt 44, these developer images are transferred to the paper P in the secondary transfer section 49. As a result, the color developer image adheres to the surface of the paper P, and the silver developer image is further superimposed on the surface of the color developer image. In other words, the color developer image is positioned between the paper P and the silver developer image so as to superimpose it on the silver developer image.

[0052] In the following, a color developer image formed with a black developer will also be referred to as a black developer image, a color developer image formed with a yellow developer will also be referred to as a yellow developer image, a color developer image formed with a magenta developer will also be referred to as a magenta developer image, and a color developer image formed with a cyan developer will also be referred to as a cyan developer image. Furthermore, below, the printing process in which a silver developer image is superimposed on a black developer image will be called a bright superimposed printing process, and the printed material obtained by the bright superimposed printing process will also be called a silver-black superimposed printed material. Further below, the printing process in which a black developer image and a silver developer image are formed without superimposing a silver developer image on the black developer image will be called a bright non-superimposed printing process, and the printed material obtained by the bright non-superimposed printing process will also be called a silver-black non-superimposed printed material. Furthermore, below, the printing process of a silver developer image alone will be called a silver developer printing process, and the printed material obtained by the silver developer printing process will also be called a silver printed material.

[0053] Incidentally, in the image forming apparatus 1, the amount of developer formed (i.e., the amount attached) in the developer image transferred to the paper P (hereinafter referred to as the amount formed on the medium; details will be described later) can be increased by increasing the absolute value of the bias voltage applied to each part by the control of the print control unit 3, while the amount formed on the medium can be decreased by decreasing the absolute value of the bias voltage. Furthermore, in the image forming apparatus 1, the amount of developer formed on the medium in the developer image transferred to the paper P can be increased by increasing the print image density of the developer (details will be described later) by the control of the print control unit 3, while the amount formed on the medium can be decreased by decreasing the print image density.

[0054] [2. Control Configuration of Image Forming Apparatus] As shown in Figure 3, the image forming apparatus 1 has a CPU 23, a memory 19, and a sensor 22. The CPU 23 has a print control unit 3, an interface unit 17, a display control unit 18, a process control unit 80, a development voltage control unit 81, a supply voltage control unit 82, an exposure control unit 83, a transfer voltage control unit 84, a motor control unit 85, and a data presence / absence determination unit 86.

[0055] The print control unit 3 controls the operation of the entire image forming apparatus 1. The interface unit 17 receives print data transmitted from a higher-level device 20, such as a computer, and provides the print data to the print control unit 3. The display control unit 18 controls the display state of the display unit 21 based on instruction signals from the print control unit 3.

[0056] The process control unit 80 controls the voltage of each part of the image forming unit 10, etc. The development voltage control unit 81 controls the bias voltage of the development roller 34. The supply voltage control unit 82 controls the bias voltage between the first supply roller 32 and the second supply roller 33 and the development blade 35. The exposure control unit 83 controls the on and off of the LEDs of the LED head 14. The transfer voltage control unit 84 controls the bias voltage of the primary transfer roller 45. The motor control unit 85 rotates the photoreceptor drum 36, etc., in a predetermined direction.

[0057] The data presence / absence determination unit 86 analyzes the print data transmitted from the host device 20 and received by the interface unit 17, and determines whether or not there is image data that should be printed by the image forming unit 10.

[0058] The data presence / absence determination unit 86 has a data conversion table 87. The data conversion table 87 converts the received print data into print patterns for the image forming units 10K, 10C, 10M, 10Y, and 10S. For example, when the data presence / absence determination unit 86 receives print data with a color of 100% red in RGB output from commercially available image creation software, it determines that the image data should be printed with 100% magenta (M) and 100% yellow (Y) according to the conversion formula contained in the data conversion table 87.

[0059] Furthermore, the data presence / absence determination unit 86 has a special silver data conversion table 88. The special silver data conversion table 88 is used when printing silver print data and converts the received print data into a print pattern for the image forming units 10K and 10S. For example, when the data presence / absence determination unit 86 receives print data of the color silver 100[%], it determines, according to the conversion formula contained in the special silver data conversion table 88, that the image data should be printed using the print pattern PT1 shown in Figure 5, which uses black (K) and silver (S).

[0060] Memory 19 is the ROM and RAM mentioned above, and stores various information such as information indicating the printing procedure and calculation formulas for various corrections (for example, software programs). Sensor 22 detects the position of the paper P, temperature and humidity, etc.

[0061] [3. Manufacturing of Developers] Next, the manufacturing of the developer contained in the developer container 12 of the image forming unit 10 (Figure 2) will be described. For the black, yellow, magenta, and cyan developers, commercially available developers for the image forming apparatus 1 (C941dn: manufactured by OKI Data Corporation) were used. In this embodiment, a silver developer was used for the special color developer. The manufacturing of the silver (silver-colored) developer will be described below.

[0062] Generally, a developer contains pigments to produce the desired color, as well as a binding resin to adhere the pigment to a medium such as paper P, and external additives to improve electrostatic properties. For the sake of explanation, below, particles containing pigment and binding resin, or powdery aggregates of these particles, will be referred to as toner or toner particles, and powdery materials containing toner and external additives will be referred to as a developer. In this embodiment, since a one-component development method is described, particles containing luminous pigment and binding resin, or powdery aggregates of these particles, will be referred to as luminous toner or luminous toner particles, and powdery materials containing luminous toner and external additives will be defined as a luminous developer. However, when describing a two-component development method, particles containing luminous pigment and binding resin, or powdery aggregates of these particles, will be referred to as luminous toner or luminous toner particles, and powdery materials containing luminous toner, external additives, and carriers will be defined as a luminous developer.

[0063] [3-1. Example 1] In Example 1, an aqueous medium containing a dispersed inorganic dispersant is first prepared. Specifically, 600 parts by weight of industrial trisodium phosphate dodecahydrate is mixed with 18,400 parts by weight of pure water and dissolved at a liquid temperature of 60°C. Dilute nitric acid is then added to adjust the pH. To this aqueous solution, an aqueous calcium chloride solution is added, prepared by dissolving 300 parts by weight of industrial anhydrous calcium chloride in 2,600 parts by weight of pure water. The mixture is then rapidly stirred at a rotation speed of 3,566 rpm for 50 minutes using a line mill (manufactured by Primix Corporation) while maintaining the liquid temperature at 60°C. This prepares the aqueous phase, which is an aqueous medium containing a dispersed suspension stabilizer (inorganic dispersant).

[0064] In Example 1, a material dispersion oily medium is prepared. Specifically, 7000 parts by weight of ethyl acetate is mixed with 470 parts by weight of a lustrous pigment (volume average particle size 5.4 [μm]) and 23 parts by weight of a charge control agent (BONTRON E-84: manufactured by Orient Chemical Industry Co., Ltd.) to create a pigment dispersion. The lustrous pigment contains minute flakes of aluminum (Al), i.e., small pieces formed in the form of flat, oblate, or flaky shapes, having planar portions. Hereafter, this lustrous pigment will also be referred to as aluminum pigment or metal pigment. The volume average particle size is also called the volume particle size, volume median diameter, or average median diameter. In this example, a lustrous pigment with a volume average particle size of 5.4 [μm] was used, but the volume average particle size of the lustrous pigment can be in the range of 5.3 to 5.7 [μm].

[0065] Subsequently, the pigment dispersion is stirred while maintaining the liquid temperature at 60°C, and 175 parts by weight of ester wax (WE-4: manufactured by NOF Corporation) as a release agent and 1670 parts by weight of polyester resin as a binder resin are added, and the mixture is stirred until no solid matter remains. This prepares the oil phase, which is the oily medium for pigment dispersion.

[0066] Next, the oil phase is added to the aqueous phase, whose liquid temperature has been lowered to 55°C, and suspended by stirring at a rotation speed of 1000 rpm for 5 minutes as granulation conditions, forming particles in the suspension. Next, the ethyl acetate is removed from the suspension by vacuum distillation to form a slurry containing the developer. Next, nitric acid is added to this slurry to lower the pH to 1.6 or less, and the mixture is stirred to dissolve the tricalcium phosphate, which is a suspension stabilizer, and then dehydrated to form the developer. Subsequently, the dehydrated developer is redispersed in pure water and stirred to perform a water wash. After that, toner matrix particles are produced by performing a dehydration process, a drying process and a classification process.

[0067] To the toner matrix particles thus produced, 1.5% by weight of small silica (RY200: manufactured by Nippon Aerosil Co., Ltd.), 2.29% by weight of colloidal silica (X24-9163A: manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.37% by weight of melamine particles (Epostor S: manufactured by Nippon Shokubai Co., Ltd.) are added and mixed to obtain a silver developer with a volume-average particle size of 15.01 μm. In this example, a silver developer with a volume-average particle size of 15.01 μm was used, but the volume-average particle size of the silver developer can be within the range of 15.01 ± 3.00 μm.

[0068] In this embodiment, the volume-average particle size of the developer was measured using a Multisizer3 precision particle size distribution analyzer (manufactured by Beckman Coulter, Inc.). The measurement conditions were as follows: • Aperture diameter: 100 [μm] • Electrolyte: Isoton II (manufactured by Beckman Coulter, Inc.) • Dispersion: Dissolve Neogen S-20F (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in the aforementioned electrolyte solution and adjust to a concentration of 5%. In this embodiment, 10-20 mg of the sample was added to 5 mL of the aforementioned dispersion and dispersed in an ultrasonic disperser for 1 minute. Then, 25 mL of electrolyte was added and dispersed in an ultrasonic disperser for 5 minutes. Aggregates were removed by passing the mixture through a mesh with a mesh opening of 75 μm to prepare the sample dispersion. Furthermore, in this embodiment, the sample dispersion was added to 100 mL of the aforementioned electrolyte, and 30,000 particles were measured using the aforementioned precision particle size distribution analyzer to determine the distribution (i.e., volume particle size distribution). Based on this volume particle size distribution, the volume-average particle size (Dv50) was determined. The volume-average particle size (Dv50) refers to the particle size at which the number or mass of particles larger than a certain size account for 50% of the total number or mass of particles in the powder's particle size distribution. The aforementioned precision particle size distribution analyzer measures particle size distribution using the Coulter principle. This Coulter principle, also known as the pore electrical resistance method, is a method of measuring particle volume by passing a constant electric current through pores (apertures) in an electrolyte solution and measuring the change in the electrical resistance of the pores as particles pass through them.

[0069] [4. About Print Patterns] Next, the printing patterns in the examples and comparative examples will be described.

[0070] [4-1. Regarding Example 1] In Example 1, the print pattern PT1 was created when print data specifying an image pattern (a so-called solid image) with a print image density of 100% for the entire area of ​​an A4 sheet of paper P was sent from the host device 20 to the image forming apparatus 1. The image forming apparatus 1 then performed a glossy non-overlay printing process using the special silver data conversion table 88, and created the print pattern on the paper P as shown in Figure 4.

[0071] At this time, the image forming apparatus 1 refers to a pre-stored special silver data conversion table 88 and converts the print data of 100% special color (silver) into an instruction to print a 16x16 dot area, which is a part of the print pattern PT1 in Figure 4, on the paper P in black and special color, as shown in Figure 5. Here, 1 dot (also called 1 pixel unit) is the state when the print pattern PT1 is enlarged to the smallest unit of the print instruction. The print pattern PT1 is formed of 600 dots, and the smallest square in Figure 5 corresponds to 1 dot. Since the print pattern PT1 is 600 dpi, the width and height of 1 dot are 0.042 mm. In this way, in the case of Example 1, a silver-black non-overlay print is obtained, which is a printed material created by laying out the print pattern PT1, shown in the enlarged view in Figure 5, across the entire area of ​​the A4 paper P as shown in Figure 4.

[0072] The print pattern PT1 consists of a silver developer image IS formed by a silver developer and a black developer image IB formed by a black developer. In the following, the region of the silver developer image IS on the paper surface will be referred to as the silver developer image region ARIS, and the region of the black developer image IB will be referred to as the black developer image region ARIB.

[0073] The silver developer image IS consists of 4x4 square silver developer image squares ISS arranged in a grid pattern with 4 dots spacing between them vertically and horizontally. The black developer image IB consists of 2x2 square black developer image squares IBS arranged between the silver developer image squares ISS. Between the black developer image squares IBS and the silver developer image squares ISS, a white area WH is formed, where no developer image is formed, surrounding the black developer image squares IBS by one dot at a time. In other words, the black developer image squares IBS are positioned with a white area WH, which is a blank space, between them and the silver developer image squares ISS. Note that when the black developer image squares IBS are printed on paper P, they do not actually form a perfect 2x2 square, but rather the 4 dots overlap to some extent and the corners are rounded.

[0074] Thus, in the printed pattern PT1, the black developer image area ARIB is positioned in the area excluding the silver developer image area ARIS, with a white area WH formed between it and the silver developer image area ARIS. Furthermore, when viewed in a 16x16 dot area, for example, the silver developer image IS is formed in 128 dots, which is half of the total area of ​​the 16x16 dots, while the remaining area is filled with the black developer image IB and the white area WH. Moreover, when viewed in a 16x16 dot area, for example, the silver developer image IS is formed in 128 dots and the black developer image IB is formed in 32 dots. Therefore, in the printed pattern PT1, the silver developer image area ARIS is formed to be larger than the black developer image area ARIB. In other words, within the 16x16 dot area of ​​the printed pattern PT1, the silver developer image area ARIS occupies a larger proportion of the area than the black developer image area ARIB.

[0075] [4-2. Regarding Comparative Example 1] In Comparative Example 1, the print pattern PT101 is created on the paper P as shown in Figure 4 by sending print data specifying a solid image of a spot color (silver) across the entire A4 paper P from the host device 20 to the image forming apparatus 1, and by performing a silver developer printing process without using the special silver data conversion table 88 in the image forming apparatus 1. In the case of Comparative Example 1, a silver printed material is obtained, which is a printed material created by covering the entire A4 paper P with the print pattern PT101, shown in an enlarged view in Figure 6, as shown in Figure 4.

[0076] The printed pattern PT101 consists solely of silver developer images IS formed by the silver developer. Furthermore, when viewed within a 16x16 dot area, for example, the silver developer images IS are formed for 256 dots, representing the entire 16x16 dot area.

[0077] [4-3. Regarding Comparative Example 2] In Comparative Example 2, the print pattern PT201 is created when print data specifying a solid image of a spot color (silver) and an image pattern with a print image density of 30% in black is sent from the host device 20 to the image forming apparatus 1, and the image forming apparatus 1 creates it on the paper P as shown in Figure 4 without using the special data conversion table 88 for spot silver. In the case of Comparative Example 2, a silver-black superimposed print is obtained, which is a printed material created by laying out the print pattern PT201, shown in an enlarged view in Figure 7, across the entire A4 paper P as shown in Figure 4.

[0078] Furthermore, in the printing pattern PT201, the amount of silver developer on the paper surface (amount formed on the medium) in the image forming apparatus 1 is 0.19 [mg / cm³]. 2 The image was created by adjusting the development bias voltage so that ]. The image forming apparatus 1 creates an image pattern with a black developer print image density of 30[%] below the silver developer image IS, which is a solid image of the silver developer. 2 Print pattern PT201 is created by performing a bright superposition printing process to print the black developer image IB30, which is ]).

[0079] [4-4. Regarding Comparative Example 3] In Comparative Example 3, the print pattern PT301 is created when print data specifying a solid image of a spot color (silver) across the entire A4 sheet of paper P is sent from the host device 20 to the image forming apparatus 1. The image forming apparatus 1 then uses a special data conversion table 88 for spot silver to perform a glossy non-overlay printing process, creating the print on the paper P as shown in Figure 4. In the case of Comparative Example 3, the print pattern PT301, shown in an enlarged view in Figure 8, is laid out across the entire A4 sheet of paper P, resulting in a silver-black non-overlay print.

[0080] In print pattern PT301, the black developer image square IBS is shifted by one dot vertically (downward) and horizontally (leftward) compared to print pattern PT1 (Figure 5). As a result, two of the four sides of the black developer image square IBS are adjacent to the silver developer image square ISS without leaving a white area WH between them.

[0081] [4-5. Regarding Comparative Example 4] In Comparative Example 4, the print pattern PT401 is created when print data specifying a solid image of a spot color (silver) across the entire A4 paper P is sent from the host device 20 to the image forming apparatus 1, and the image forming apparatus 1 uses a special data conversion table 88 for spot silver to create the print pattern on the paper P as shown in Figure 4. In the case of Comparative Example 4, the print pattern PT401, shown in an enlarged view in Figure 9, is laid out across the entire A4 paper P as shown in Figure 4 to produce a printed product.

[0082] In print pattern PT401, the black developer image square IBS is shifted horizontally (to the left) by one dot compared to print pattern PT301 (Figure 8). As a result, the left half of the black developer image square IBS overlaps with the silver developer image square ISS. The image forming apparatus 1 performs a bright superposition printing process, printing the black developer image IB (solid black developer image) below the silver developer image IS (solid silver developer image), thereby forming an overlapping region between the black developer image square IBS and the silver developer image square ISS.

[0083] [4-6. Regarding Comparative Example 5] In Comparative Example 5, the print pattern PT501 is created when print data specifying a solid image of a spot color (silver) covering the entire area of ​​an A4 sheet of paper P is sent from the host device 20 to the image forming apparatus 1, and the image forming apparatus 1 uses a special data conversion table 88 for spot silver to create the print pattern on the paper P as shown in Figure 4. In the case of Comparative Example 5, the print pattern PT501, shown in an enlarged view in Figure 10, is laid out across the entire area of ​​the A4 sheet of paper P as shown in Figure 4 to produce a printed product.

[0084] In print pattern PT501, compared to print pattern PT1 (Figure 5), the black developer image square IBS is moved to the center of the silver developer image square ISS. As a result, the entire area of ​​the black developer image square IBS overlaps with the silver developer image square ISS. The image forming apparatus 1 performs a bright superposition printing process, printing the black developer image IB (solid black developer image) below the silver developer image IS (solid silver developer image), thereby forming an overlapping area between the black developer image square IBS and the silver developer image square ISS.

[0085] Thus, in the case of Comparative Examples 3, 4, and 5, the image forming apparatus 1, compared to Example 1, uses the special silver data conversion table 88 to form a silver developer image IS, a black developer image IB, and a white area WH in the same way as Example 1, but creates print patterns PT301, PT401, and PT501 which are different arrangement patterns of the silver developer image IS, black developer image IB, and white area WH from Example 1, for print data where a solid silver image is specified.

[0086] [4-7. Regarding print image density] Here, print image density is a value that represents the ratio of the number of pixels to which the developer is transferred to the paper P when the image is broken down into pixels. For example, when printing solid color over a predetermined area (such as one rotation of the photosensitive drum 36 or one page of the printing medium), printing with an area ratio of 100[%] is called a print image density of 100[%], and printing with an area equivalent to 1[%] of this print image density of 100[%] is called a print image density of 1[%]. The print image density DPD can be expressed mathematically using the number of dots used Cm, the rotation speed Cd, and the total number of dots CO as shown in (1) below.

[0087]

number

[0088] However, the number of dots used Cm is the number of dots actually used to form an image while the photoreceptor drum 36 rotates Cd, and is the total number of dots exposed by the LED head 14 (Figure 2) while the image is being formed. The total number of dots CO is the total number of dots per rotation of the photoreceptor drum 36 (Figure 2), that is, the total number of dots that can potentially be used to form an image while the photoreceptor drum 36 rotates once, regardless of whether or not they are exposed. In other words, the total number of dots CO is the sum of the number of dots used when forming a solid image in which developer is transferred to all pixels. Therefore, the value (Cd × CO) represents the total number of dots that can potentially be used to form an image while the photoreceptor drum 36 rotates Cd.

[0089] [5. Measurement and Evaluation of Developers] Next, the measurement and evaluation of the developer will be described. For this measurement and evaluation of the developer, a predetermined image was printed on paper P using the developer with the image forming apparatus 1 (Figure 1), and the color unevenness, glossiness, streaks, vertical streaks, and horizontal bands were measured and evaluated respectively.

[0090] In this evaluation, silver developer was placed in the developer container 12 (Figure 2) of the image forming unit 10S corresponding to the spot color (Figure 1), and black developer was placed in the developer container 12 (Figure 2) of the image forming unit 10K corresponding to black. Then, printing processes for Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5 were performed, and the color unevenness, glossiness, streaking, vertical streaks, and horizontal bands were evaluated for each.

[0091] Specifically, in this evaluation, the paper P is coated paper (OS coated paper W, 127 g / m²). 2 [Manufactured by Fuji Xerox Co., Ltd.] was used. In Example 1, Comparative Example 1, Comparative Example 3, Comparative Example 4 and Comparative Example 5, the amount of silver developer formed on the medium (amount attached to the paper surface) was 0.65 [mg / cm²]. 2The development bias voltage was adjusted for evaluation so as to achieve the following. Also, in Comparative Example 2, the amount of silver developer formed on the medium (amount adhered to the paper surface) was 0.19 [mg / cm 2 The development bias voltage was adjusted for evaluation so as to achieve the following.

[0092] [5-1. Measurement of the amount formed on the medium] Here, the measurement of the amount formed on the medium will be described. In this measurement, the amount of silver developer formed on the medium before fixing was measured. Here, the amount of developer adhered to a medium such as the paper P is represented by the weight [mg] per unit area of 1 [cm 2 , and its unit is [mg / cm 2 . Hereinafter, this will be referred to as the amount formed on the medium. That is, the amount formed on the medium is an index indicating how much developer is adhered to the paper P. This amount formed on the medium is measured and calculated by the following method.

[0093] First, a jig having a flat part made of metal is prepared, and double-sided tape is attached to a part of the flat part of this jig having an area of 1 [cm 2 . In this state, the weight of this jig is measured with an electronic balance (Sartorius, CAP225D), and then a DC voltage of +300 [V] is applied to this jig using an external power supply.

[0094] Next, as shown in FIG. 11, a medium (i.e., paper P (coated paper (OS coated paper W, basis weight 127 [g / m 2Prepare a sheet of paper P manufactured by Fuji Xerox Co., Ltd. On this sheet of paper P, press the jig once against a 10 mm square area (hereinafter referred to as the measurement area AR) that is approximately in the center in the main scanning direction and near the front in the media transport direction Dp (i.e., the sub-scanning direction) to collect developer from the medium. Incidentally, the length of the sheet of paper P in the main scanning direction (left-right direction in the diagram) is 297 mm, which is equivalent to the long side of an A4 size sheet or the short side of an A3 size sheet. Next, weigh the jig with the developer attached again using an electronic balance. Then, calculate the increase in the weight of the jig before and after developer collection to determine the amount formed on the medium [mg / cm³]. 2 The result is calculated.

[0095] To measure the amount of silver developer formed on the medium, the image forming apparatus 1 (C941dn: manufactured by OKI DATA Corporation) (Figure 1) prints an image pattern BT (a so-called solid image) with a printed image density of 100% for the silver developer, and then a jig is pressed once against this image pattern BT to collect the silver developer from the medium. The image forming apparatus 1 also adjusts the amount of silver developer formed on the medium by changing the bias voltage applied to the developing roller 34 from 110 to 335 V.

[0096] [5-2. Measurement and Evaluation of Color Unevenness] In this evaluation, a spectrophotometer (CM-2600d, measuring meter φ=8[mm]: manufactured by Konica Minolta, Inc.) was used to measure the luminous reflectance difference ΔY as a measurement indicating the silver hue (grayness) on the paper surface. The luminous reflectance difference ΔY is the difference between the luminous reflectance of a blank sheet of paper and the luminous reflectance of a printed image. Specifically, the luminous reflectance difference ΔY was measured by subtracting the luminous reflectance of the unprinted medium from the luminous reflectance of the printed medium. In addition, coated paper (OS coated paper W, 127[g / m²)) was used as the underlay for the printed material during measurement. 2 A 3D printer (manufactured by Fuji Xerox Co., Ltd.) was used. Here, the light source conditions were C, the angle was 2°, and the specular reflection processing method was SCE.

[0097] Here, a characteristic of silver developers is that they not only exhibit their own brilliance in printed materials, but also represent their inherent grayness as a color. However, if the luminous reflectance difference ΔY is less than 30, which is too small, that is, if the color is similar to the original medium, the grayness disappears and the grayness cannot be represented. On the other hand, if the luminous reflectance difference ΔY exceeds 34, which is too large, the color becomes too dark and blackish, and similarly, the grayness cannot be represented. Therefore, in this evaluation, we consider that the grayness of the silver developer after printing was represented when the luminous reflectance difference ΔY is between 30 and 34.

[0098] Furthermore, in order to avoid color unevenness across the paper, the luminous reflectance difference ΔY across the entire paper surface must be between 30 and 34. Therefore, as shown in Figure 12, the luminous reflectance difference ΔY was measured at 15 measurement points MP1, MP2, MP3, MP4, MP5, MP6, MP7, MP8, MP9, MP10, MP11, MP12, MP13, MP14, and MP15 (hereinafter collectively referred to as measurement points MP) that were set up across the entire A4 paper P. If all measured luminous reflectance differences ΔY fell within the above-mentioned range, it was determined that the color unevenness was good.

[0099] [5-3. Measurement and Evaluation of Glossiness] Next, in this evaluation, the luster was measured using a variable-angle photometer (GC-5000L: manufactured by Nippon Denshoku Industries Co., Ltd.). Specifically, as shown in Figure 13, the variable-angle photometer was used to irradiate the surface of the paper P with a light ray C from a direction of 45[°], and the reflected light was received at directions of 0[°], 30[°], and -65[°] perpendicular to the paper P. Based on the obtained reception results, the lightness index L*0, lightness index L*30, and lightness index L*-65 were calculated, respectively. Next, in this evaluation, the flop index FI was calculated by substituting each calculated lightness index into the following equation (2), and the luster of the image was measured.

[0100]

number

[0101] The flop index FI (FI value) is an indicator of glossiness; a higher value means high glossiness, and a lower value means low glossiness. When the FI value is 12.0 or higher, the printed material appears to have a metallic luster to the naked eye. Therefore, in this evaluation, we consider that sufficient glossiness has been achieved when the FI value is 12.0 or higher. Accordingly, we measured the FI values ​​within the measurement points MP shown in Figure 12, calculated the average value of the FI values ​​of these 15 measurement points MP, and determined that the glossiness was good when the average value of the FI values ​​was 12.0 or higher.

[0102] [5-4. Evaluation of Cassé] Next, in this evaluation, we assessed the degree of smudging within the paper. In this evaluation, we visually observed the 5cm square area A shown in Figure 14, centered on each measurement point MP shown in Figure 12. If no shading patterns like those shown in Figure 14 were observed in area A of all measurement points MP, the degree of smudging was judged to be good.

[0103] [5-5. Evaluation of vertical and horizontal stripes] Next, this evaluation assessed vertical streaks and horizontal bands within the paper. In this evaluation, we observed vertical streaks and horizontal bands, which are defects that occur from one end to the other on the surface of an A4 sheet of paper P. A streak refers to the phenomenon of thin white areas with a width of less than 1 mm appearing. A band refers to the phenomenon of areas with a difference in density of 1 mm or more appearing. In this evaluation, the absence of the vertical streaks 94 shown in Figure 15 was judged to be good. Also, in this evaluation, the absence of the horizontal bands 96 shown in Figure 16 was judged to be good.

[0104] [6. Measurement Results and Evaluation Results] The following describes the results of evaluation tests conducted to confirm the effectiveness of the examples, and the effects that can be inferred from them.

[0105] [6-1. Measurement and evaluation results of color unevenness] As shown in Figure 17, in Example 1, Comparative Example 2, and Comparative Example 3, the luminous reflectance difference ΔY was between 30 and 34 at all measurement points MP, resulting in good color uniformity. On the other hand, in Comparative Example 1, Comparative Example 4, and Comparative Example 5, there were measurement points MP where the luminous reflectance difference ΔY was outside the range of 30 to 34, resulting in poor color uniformity.

[0106] In this regard, the print pattern PT101 of Comparative Example 1 (Figure 6) forms silver developer in all 256 dots when viewed in a 16x16 dot area. In contrast, the print pattern PT1 of Example 1 (Figure 5) forms silver developer in 128 dots, which is half the number of dots as in Comparative Example 1, when viewed in a 16x16 dot area. Furthermore, when printing a print with a large amount of developer developed on the paper surface over a wide area such as the entire surface of an A4 sheet of paper, unevenness in color is likely to occur on the paper surface.

[0107] Therefore, in Example 1 (Figure 5), the amount of developer used for both the black and silver developers was such that color unevenness was unlikely to occur, resulting in good color uniformity. On the other hand, in Comparative Example 1 (Figure 6), the amount of developer developed on the paper was too large, resulting in poor color uniformity. Furthermore, in Comparative Examples 4 (Figure 9) and 5 (Figure 10), the amount of developer increased because at least a portion of the black and silver developers were overlapped, making it impossible to stably transfer the developer from the intermediate transfer belt 44 to the paper P, thus resulting in poor color uniformity.

[0108] [6-2. Measurement and evaluation results of glossiness] As shown in Figure 18, Examples 1, Comparative Example 2, and Comparative Example 3 had good gloss because the average value of the FI values ​​at all measurement points MP was 12 or higher. On the other hand, Comparative Examples 1, 4, and 5 had poor gloss because the average value of the FI values ​​at all measurement points MP was less than 12.

[0109] This is thought to be due to the property of silver developer that if too much developer is developed on the paper, the glossiness decreases. Therefore, it is thought that Example 1 (Figure 5) has better glossiness because it uses less silver developer than Comparative Example 1 (Figure 6). On the other hand, it is thought that in Comparative Examples 4 (Figure 9) and 5 (Figure 10), the black developer and silver developer overlapped in large quantities in some areas during printing, preventing the silver developer from dissolving smoothly, resulting in poor glossiness.

[0110] [6-3. Evaluation results of fading] As shown in Figure 19, in Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5, the streaking was good at all measurement points MP. On the other hand, in Comparative Example 1, the streaking was poor because there were measurement points MP with poor streaking.

[0111] This is thought to be due to the property of silver developers that if too much developer is developed on the paper, the glossiness decreases. Therefore, Example 1 (Figure 5) has a better glossiness because it uses less silver developer than Comparative Example 1 (Figure 6), and since good glossiness leads to good streaking, it is thought that the streaking was improved in Example 1.

[0112] [6-4. Evaluation results of vertical lines and horizontal bands] As shown in Figure 20, Example 1 showed good vertical and horizontal streaks, while Comparative Examples 1, 2, 3, 4, and 5 showed poor vertical and horizontal streaks.

[0113] In Example 1, when vertical or horizontal streaks occur in a location including the interior of the black developer image area ARIB (Figure 5), the vertical or horizontal streaks are easily visible, but when vertical or horizontal streaks occur in the interior of the white area, they are difficult to see. Furthermore, even if vertical or horizontal streaks occur in a location including the interior of the silver developer image area ARIS (Figure 5), because the silver developer image area ARIS is grid-like, the vertical or horizontal streaks do not occur continuously from one end of the paper P to the other. Thus, since Example 1 is composed of a combination of a silver developer image IS pattern that is less prone to the occurrence of vertical and horizontal streaks and a black developer image IB pattern, it is considered that the vertical and horizontal streaks are well-defined.

[0114] [6-5. Summary] Based on the above results, when the image forming apparatus 1 receives print data for the color silver 100%, it prints using the print pattern PT1 of Example 1 shown in Figure 5, which uses black (K) and silver (S), according to the conversion formula contained in the special silver data conversion table 88, thereby obtaining a printed material with good gloss, color unevenness, smudging, and vertical and horizontal streaks.

[0115] [7. Functional configuration of the image forming apparatus] Here, the basic functions related to the printing process in the image forming apparatus 1 are represented by a functional block diagram as shown in Figure 21.

[0116] The first image forming unit 90 corresponds to the image forming unit 10S (Figure 1) and is capable of forming a silver developer image IS as a lustrous developer image using a silver developer as a lustrous developer. The second image forming unit 91 corresponds to the image forming unit 10K (Figure 1) and is capable of forming a black developer image IB as a developer image using a black developer as a non-lustrous developer.

[0117] The control unit 92 corresponds to the print control unit 3 (Figure 3) and controls the operation of the first image forming unit 90 and the second image forming unit 91 according to the received print data. When the first image forming unit 90 forms a silver developer image IS on the paper P, which is the medium, based on the print data, the second image forming unit 91 forms a black developer image IB, which is a black developer image, outside the formation area of ​​the silver developer image IS.

[0118] [8. Effects, etc.] Here, when the amount of silver formed on the silver developer medium on the paper P is small, the FI value increases, but the luminous reflectance difference ΔY decreases. On the other hand, when the amount of silver formed on the silver developer medium on the paper P increases, the luminous reflectance difference ΔY increases, but the FI value decreases. Thus, to improve the luminous reflectance difference ΔY, it is necessary to increase the amount of silver formed on the silver developer medium on the paper P, but as the amount of silver formed on the silver developer medium increases, the FI value decreases. In other words, there is a trade-off relationship between the FI value and the luminous reflectance difference ΔY, making it difficult to achieve both high brilliance (FI value) and a high luminous reflectance difference ΔY.

[0119] In contrast, when the image forming apparatus 1 receives print data for a single color of silver developer, it does not form only a silver developer image IS consisting of silver developer on the paper P, but rather, as shown in Figure 5, it arranges the silver developer images IS in a grid pattern and forms a black developer image IB consisting of black developer in the areas other than the silver developer images IS.

[0120] Therefore, the image forming apparatus 1 can suppress the amount formed on the silver developer medium to prevent a decrease in the FI value, while compensating for the luminous reflectance difference ΔY with the black developer image IB. As a result, the image forming apparatus 1 can obtain a silver print that achieves both high luster (FI value) and a high luminous reflectance difference ΔY, even when the amount formed on the silver developer medium is small. Thus, the image forming apparatus 1 can achieve both metallic luster (FI value) and image color (luminous reflectance difference ΔY).

[0121] Here, when the image forming apparatus 1 receives print data for a single color of silver developer, it is conceivable that instead of forming only the silver developer image IS on the paper P, it controls the amount of silver developer formed on the medium and the amount of black developer formed on the medium, and then forms a black developer image IB in the layer below the silver developer image IS (i.e., between the silver developer image IS and the paper P) (Figure 7). This suppresses the amount of silver developer formed on the medium, thereby reducing the decrease in the FI value, while the black developer image IB compensates for the difference in luminous reflectance ΔY.

[0122] In that case, if the amount of silver developer formed on the medium is reduced by lowering the bias voltage applied to the developing roller 34 of the image forming unit 10S while keeping the print image density of the silver developer at 100%, it becomes difficult to control the formation of a thin layer of silver developer image IS with high precision and uniformity, and there is a high possibility that color unevenness, streaks, and printing defects such as vertical streaks and horizontal bands will occur in the silver developer image IS.

[0123] In response to this, the image forming apparatus 1 maintains the amount of silver developer formed on the silver developer medium while making the silver developer image IS a grid, thereby achieving a print image density of 50% when viewed across the entire paper surface. As a result, the image forming apparatus 1 can suppress the occurrence of printing defects in the silver developer image IS. This allows the image forming apparatus 1 to suppress printing defects in the silver developer while simultaneously achieving a high FI value and a high luminous reflectance difference ΔY.

[0124] Furthermore, the image forming apparatus 1 is configured to form a white region WH between the silver developer image IS and the black developer image IB. As a result, the image forming apparatus 1 can produce good vertical streaks and horizontal bands.

[0125] Furthermore, the image forming apparatus 1 is configured to form the silver developer image region ARIS larger (wider) than the black developer image region ARIB. As a result, the image forming apparatus 1 can improve glossiness (FI value) compared to, for example, the case where the silver developer image region ARIS and the black developer image region ARIB occupy the same size area.

[0126] According to the above configuration, the image forming apparatus 1 includes a first image forming unit 90 capable of forming a silver developer image IS with a silver developer, a second image forming unit 91 including at least one image forming unit 10 capable of forming a black developer image IB with a color developer, and a print control unit 3 that controls the operation of the first image forming unit 90 and the second image forming unit 91 according to the received print data. The print control unit 3 causes the first image forming unit 90 to form a silver developer image IS on the paper P based on the print data, and causes the second image forming unit 91 to form a black developer image IB outside the formation area of ​​the silver developer image IS.

[0127] This allows the image forming apparatus 1 to suppress the amount of silver developer formed on the paper P, thereby preventing a decrease in the FI value, while compensating for the luminous reflectance difference ΔY with the black developer image IB.

[0128] [9. Other Embodiments] In the embodiment described above, the image forming apparatus 1 is described as having a 4x4 dot square shape for the silver developer image square ISS in the print pattern PT1 (Figure 5), arranged in a grid pattern with a spacing of 4 dots between them vertically and horizontally. The present invention is not limited to this, and the image forming apparatus 1 may also have silver developer image square ISS of various shapes with various numbers of dots, and arrange them with various spacings of various numbers of dots between them. In that case, it is preferable to arrange the silver developer image square ISS in a grid pattern.

[0129] Furthermore, in the embodiment described above, the image forming apparatus 1 was described in the case where the black developer image square IBS in the print pattern PT1 (Figure 5) is a 2x2 dot square. The present invention is not limited to this, and the image forming apparatus 1 may also use various other shapes with various other dot counts for the black developer image square IBS.

[0130] Furthermore, in the above-described embodiment, the image forming apparatus 1 was described in a case where the white area WH in the print pattern PT1 (Figure 5) is formed by surrounding the black developer image square IBS with one dot at a time for one full circle. The present invention is not limited to this, however, the image forming apparatus 1 may also form the white area WH by surrounding the black developer image square IBS with two or more different dots at a time for one full circle.

[0131] Furthermore, in the embodiment described above, the case in which the image forming apparatus 1 defines the white region WH in the printed pattern PT1 (Figure 5) as a region in which no developer image is formed was described. The present invention is not limited to this, and the image forming apparatus 1 may also define the white region WH as a region in which a white developer image is formed.

[0132] Furthermore, when the image forming apparatus 1 receives print data from the host device 20 specifying a solid silver image across the entire A4 paper P, it may use the special silver data conversion table 88 to create print patterns PT601 (shown in an enlarged view in Figure 22), print pattern PT701 (shown in an enlarged view in Figure 23), or print pattern PT801 (shown in an enlarged view in Figure 24), on the paper P, with the same reference numerals assigned to the areas corresponding to print pattern PT1 (Figure 5).

[0133] In the print pattern PT601, the silver developer image IS, the black developer image IB, and the white area WH are arranged in a stepped manner. Outside the silver developer image area ARIS, the black developer image area ARIB is formed with the white area WH in between it and the silver developer image area ARIS.

[0134] In print pattern PT701, the silver developer image IS extends continuously vertically with a width of 4 bits horizontally, and each silver developer image IS is spaced horizontally with a gap of 4 bits between them. In addition, between the silver developer images IS in print pattern PT701, black developer images IB are discretely arranged vertically with a width of 2 bits horizontally, separated by a white area WH. In print pattern PT701, although vertical streaks or horizontal bands may occur because the silver developer images IS extend continuously along one direction, it can achieve good color uniformity and glossiness.

[0135] In print pattern PT801, the silver developer image IS extends continuously vertically with a width of 4 bits in the left-right direction, and each silver developer image IS is spaced horizontally with a gap of 4 bits between them. In print pattern PT801, black developer images IB extend continuously vertically with a width of 2 bits in the horizontal direction, with a white area WH between each silver developer image IS. In print pattern PT701, the silver developer image IS and black developer image IB extend continuously along one direction, which may result in vertical streaks or horizontal bands, but it can achieve good color uniformity and glossiness.

[0136] Furthermore, in the above-described embodiment, the image forming apparatus 1 was described in the case where a black developer image IB is formed using a black developer alone. The present invention is not limited to this, and the image forming apparatus 1 may also form a black developer image (black developer image) consisting of process black by combining a yellow developer, a magenta developer, and a cyan developer as non-glossy developers with a plurality of colored developers. In that case, the second image forming unit 91 (Figure 21) corresponds to the image forming units 10C, 10M, and 10Y (Figure 1). Alternatively, a black developer image consisting of process black may be formed by combining a yellow developer, a magenta developer, a cyan developer, and a black developer as non-glossy developers. In that case, the second image forming unit 91 (Figure 21) corresponds to the image forming units 10C, 10M, 10Y, and 10K (Figure 1).

[0137] For example, when forming an image equivalent to one with a black developer at a print image density of 30%, the image forming apparatus 1 will create process black using yellow, magenta, and cyan developers at a print image density of 20% each. Therefore, when expressing the same black color, process black will result in a larger amount of developer being formed on the paper P than black developer alone. Consequently, for paper P with significant surface irregularities, it is considered preferable to use process black rather than black developer alone to fill in the irregularities. In addition, for example, if the amount of black developer remaining in the developer container 12 of the image forming unit 10K is low, the black developer image may be formed using process black. In other words, black developer or process black may be selected according to the remaining amount of each color's developer.

[0138] Furthermore, in the embodiment described above, the image forming apparatus 1 described a case in which the aluminum (Al) contained in the lustrous pigment used to produce the developer is in the form of minute flakes having a planar portion. The present invention is not limited to this, and the image forming apparatus 1 may also use small pieces of various shapes, such as spherical or rod-shaped, for the aluminum (Al) contained in the lustrous pigment.

[0139] Furthermore, in the embodiment described above, the case where the metal contained in the luminous pigment used to generate the developer in the image forming apparatus 1 is aluminum (Al) was described. The present invention is not limited to this, and the image forming apparatus 1 may be made of various metals, such as brass or iron oxide. In this case, the color that the developer exhibits when fixed to the paper P will be a color corresponding to the metal.

[0140] Furthermore, in the above-described embodiment, the image forming apparatus 1 was described in a case where metallic color expressionability was evaluated using a silver developer as an example of a lustrous developer. The present invention is not limited to this, and the image forming apparatus 1 may also use a gold developer as an example of a lustrous developer. In that case, the gold developer can be prepared by the following manufacturing method. In the above-described embodiment, aluminum was added as a lustrous pigment during manufacturing to prepare the silver developer, but at this time, a yellow pigment (here, CIPigment Yellow 180 as an organic pigment), a magenta pigment (here, CIPigment Red 122 as an organic pigment), a red-orange fluorescent dye (FM-34N_Orange: manufactured by Shinloihi Co., Ltd.), and a yellow fluorescent dye (FM-35N_Yellow: manufactured by Shinloihi Co., Ltd.) are also added to prepare the gold developer.

[0141] Furthermore, in the above-described embodiment, the image forming apparatus 1 measures the amount of developer formed on the medium (paper P) onto which the image pattern BT (Figure 11) has been transferred. The present invention is not limited to this, and the image forming apparatus 1 may also measure the amount of developer formed on the photosensitive drum 36 before it is transferred to the paper P, or on the intermediate transfer belt 44, etc.

[0142] Furthermore, in the above-described embodiment, when the image forming apparatus 1 evaluates the printed pattern PT201 (Figure 7), the amount formed on the silver developer medium is 0.19 [mg / cm³]. 2 ], the amount of black developer (amount formed on the medium) is 0.025 [mg / cm³ 2 The present invention is not limited to this, but the image forming apparatus 1 has a silver developer medium with a formation amount of 0.13 to 0.24 [mg / cm³]. 2 When within the range of ], the ratio of (amount of black developer formed on the medium / amount of silver developer formed on the medium) is 0.068 [mg / cm³]. 2 ] or more 0.23[mg / cm 2 The amount of black developer (amount formed on the medium) should be adjusted to be within the following range: 0.01632 to 0.0299 [mg / cm³]. 2By adjusting it to fall within the range of [ ], you can achieve a similar effect.

[0143] Furthermore, the embodiments described above describe the case in which the present invention is applied to a developer used in a one-component development method. The present invention is not limited to this, and may also be applied to a developer in a two-component development method, which is a method in which an appropriate amount of charge is imparted to the toner by utilizing the friction between the carrier and the toner after mixing the carrier and the toner.

[0144] Furthermore, the above-described embodiment describes the application of the present invention to an image forming apparatus 1 that uses a so-called intermediate transfer method (or secondary transfer method), in which the developer images of each color are sequentially transferred from the photosensitive drum 36 of the image forming unit 10 to the intermediate transfer belt 44, and the developer images are then transferred from the intermediate transfer belt 44 to the paper P. The present invention is not limited to this, and may also be applied to an image forming apparatus that uses a so-called direct transfer method, in which the developer images of each color are sequentially transferred from the photosensitive drum 36 of the image forming unit 10 to the paper P used as a medium.

[0145] Furthermore, the above-described embodiment described a case in which five image forming units 10 are provided in the image forming apparatus 1 (Figure 1). 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.

[0146] Furthermore, the above-described embodiment described the case in which the present invention is applied to an image forming apparatus 1 which is a single-function printer. The present invention is not limited to this, and may also be applied to image forming apparatuses with various other functions, such as an MFP (Multi-Function Peripheral) that has the functions of a copier or a facsimile machine.

[0147] Furthermore, the above-described embodiment described the case in which the present invention is applied to an image forming apparatus 1. The present invention is not limited to this, and may be applied to various electronic devices such as photocopiers that form images on a medium such as paper P using an electrophotographic method with a developer.

[0148] Furthermore, the present invention is not limited to the embodiments described above and other embodiments. That is, the scope of the present invention extends to embodiments obtained by arbitrarily combining some or all of the embodiments described above and other embodiments. In addition, the scope of the present invention extends to embodiments obtained by extracting a part of the configuration described in any embodiment from the embodiments described above and other embodiments and substituting or adapting it with a part of the configuration of any embodiment from the embodiments described above and other embodiments, or by adding a part of the extracted configuration to any embodiment.

[0149] Furthermore, in the above-described embodiment, we have described a case in which the image forming apparatus 1 is configured with a first image forming unit 90 as a first image forming unit, a second image forming unit 91 as a second image forming unit, and a control unit 92 as a control unit. The present invention is not limited to this, and the image forming apparatus may be configured with a first image forming unit, a second image forming unit, and a control unit having various other configurations. [Industrial applicability]

[0150] This invention can be used when forming an image on a medium using an electrophotographic method with a developer containing a metal pigment.

[0151] The various aspects of this disclosure are summarized below as an appendix. (Note 1) A first image forming unit capable of forming a lustrous developer image using a lustrous developer, A second image forming unit including at least one image forming unit capable of forming a developer image with a non-glossy developer, A control unit controls the operation of the first image forming unit and the second image forming unit according to the received print data. Equipped with, The control unit, When the first image forming unit forms the luminous developer image on the medium based on the print data, the second image forming unit forms a black developer image outside the area where the luminous developer image is formed. An image forming apparatus characterized by the following features. (Note 2) The control unit, The region of the luminous developer image is made larger than the region of the black developer image. The image forming apparatus according to Appendix 1, characterized in that it is a picture forming apparatus. (Note 3) The control unit, When the first image forming unit forms the luminous developer image on the medium based on the print data, a white region is placed between the region of the luminous developer image and the region of the black developer image. The image forming apparatus according to Appendix 1 or Appendix 2, characterized by the above. (Note 4) The control unit, When the first image forming unit forms the luminous developer image on the medium based on the print data, a white region, in which no developer image is formed, is formed between the region of the luminous developer image and the region of the black developer image. The image forming apparatus according to Appendix 3, characterized in that it is a picture forming apparatus. (Note 5) The control unit, When the first image forming unit forms the luminous developer image on the medium based on the print data, a white region, which is the developer image region made of white developer, is formed between the region of the luminous developer image and the region of the black developer image. The image forming apparatus according to Appendix 3, characterized in that it is a picture forming apparatus. (Note 6) The aforementioned luminous developer image is lattice-like. An image forming apparatus as described in any one of Appendix 1 to Appendix 5, characterized by the above. (Note 7) The bright developer image and the black developer image are each composed of multiple pixel units, The control unit, When the first image forming unit forms the glossy developer image on the medium based on the print data, the multiple pixel units of the black developer image are formed outside the formation area of ​​the multiple pixel units of the glossy developer image. An image forming apparatus as described in any one of Appendix 1 to Appendix 6, characterized by the above. (Note 8) The aforementioned black developer image is formed by the black developer. An image forming apparatus as described in any one of Appendix 1 to Appendix 7, characterized by the above. (Note 9) The second image forming unit includes an image forming unit that forms the black developer image using the black developer, which is the non-glossy developer. An image forming apparatus as described in any one of Appendix 1 to Appendix 8, characterized by the above. (Note 10) The aforementioned black developer image is formed by multiple colored developers. An image forming apparatus as described in any one of Appendix 1 to Appendix 7, characterized by the above. (Note 11) The second image forming unit includes an image forming unit that forms the black developer image using a plurality of colored non-glossy developers. The image forming apparatus according to Appendix 10, characterized in that it is a picture forming apparatus. (Note 12) The second image forming unit includes an image forming unit that forms the black developer image using a plurality of non-glossy developers other than the black developer. The image forming apparatus according to Appendix 11, characterized in that it is a picture forming apparatus. [Explanation of symbols]

[0152] 1...Image forming apparatus, 2...Housing, 2T...Paper output tray, 3...Print control unit, 10...Image forming unit, 11...Image forming main body, 12...Developer container, 13...Developer supply unit, 14...LED head, 17...Interface unit, 18...Display control unit, 19...Memory, 20...Host device, 21...Display unit, 22...Sensor, 23...CPU, 30...Image forming housing, 31...Developer storage space, 32...First supply roller, 33...Second supply roller, 34...Developing roller, 35...Developing blade, 36...Photoreceptor drum 37...Charging roller, 38...Cleaning blade, 40...Intermediate transfer section, 41...Drive roller, 42...Driven roller, 43...Backup roller, 44...Intermediate transfer belt, 45...Primary transfer roller, 46...Secondary transfer roller, 47...Reverse bending roller, 48...Reverse bending backup roller, 49...Secondary transfer section, 50...First paper feed section, 51...Paper cassette, 52...Pickup roller, 53...Feed roller, 54...Retard roller, 55...Conveyor guide, 56, 57, 58...Conveyor roller pair, 60...Second paper feed 61...Paper tray, 62...Pickup roller, 63...Feed roller, 64...Retard roller, 65...Fixing unit, 66...Heating unit, 67...Pressurizing unit, 68...Transport roller pair, 69...Switching unit, 70...Paper discharge unit, 71...Transport guide, 72, 73, 74, 75...Transport roller pair, 76...Discharge port, 77...Retransport unit, 80...Process control unit, 81...Developing voltage control unit, 82...Supply voltage control unit, 83...Exposure control unit, 84...Transfer voltage control unit, 85...Motor control unit, 86...Data presence / absence determination unit, 87...Data Conversion table, 88... Special silver dedicated data conversion table, 90... First image forming unit, 91... Second image forming unit, 92... Control unit, 94... Vertical streaks, 96... Horizontal bands, PT1, PT101, PT201, PT301, PT401, PT501, PT601, PT701... Print pattern, IS... Silver developer image, ARIS... Silver developer image area, ISS... Silver developer image square, IB... Black developer image, ARIB... Black developer image area, IBS... Black developer image square, WH... White area, P... Paper.

Claims

1. A first image forming unit capable of forming a lustrous developer image using a lustrous developer, A second image forming unit including at least one image forming unit capable of forming a developer image with a non-glossy developer, A control unit that controls the operation of the first image forming unit and the second image forming unit according to the received print data, A table that converts print data specified in the print data, which has a print image density of 100% and is printed using the glossy developer, into first print data of the glossy developer image that can be formed by the first image forming unit and second print data of the black developer image that can be formed by the second image forming unit. Equipped with, The control unit, When the first image forming unit forms the glossy developer image on the medium based on the first print data, the second image forming unit forms the black developer image outside the area where the glossy developer image is formed, based on the second print data, and the area of ​​the glossy developer image is made larger than the area of ​​the black developer image in a predetermined area on the medium. An image forming apparatus characterized by the following:

2. The control unit, When the first image forming unit forms the luminous developer image on the medium based on the first print data, a white region is placed between the region of the luminous developer image and the region of the black developer image. The image forming apparatus according to feature 1.

3. The control unit, When the first image forming unit forms the luminous developer image on the medium based on the first print data, a white region, in which no developer image is formed, is formed between the region of the luminous developer image and the region of the black developer image. The image forming apparatus according to feature 2.

4. The control unit, When the first image forming unit forms the luminous developer image on the medium based on the first print data, a white region, which is the developer image region made of white developer, is formed between the region of the luminous developer image and the region of the black developer image. The image forming apparatus according to feature 2.

5. The aforementioned luminous developer image is lattice-like. The image forming apparatus according to feature 1.

6. The bright developer image and the black developer image are each composed of multiple pixel units, The control unit, When the first image forming unit forms the glossy developer image on the medium based on the first print data, the plurality of pixel units of the black developer image are formed outside the formation area of ​​the plurality of pixel units of the glossy developer image. The image forming apparatus according to feature 1.

7. The aforementioned black developer image is formed by the black developer. The image forming apparatus according to any one of claims 1 to 6.

8. The second image forming unit includes an image forming unit that forms the black developer image using the black developer, which is the non-glossy developer. The image forming apparatus according to feature 7.

9. The aforementioned black developer image is formed by multiple colored developers. The image forming apparatus according to any one of claims 1 to 6.

10. The second image forming unit includes an image forming unit that forms the black developer image using a plurality of colored non-glossy developers. The image forming apparatus according to feature 9.

11. The second image forming unit includes an image forming unit that forms the black developer image using a plurality of non-glossy developers other than the black developer. The image forming apparatus according to feature 10.

Images