Fixing apparatus and image forming apparatus

Abstract

To provide a fixing device and an image forming apparatus that can provide sufficient fixing characteristics even if a recording medium is metallic paper.SOLUTION: A fixing device comprises: non-contact heating means that heats a recording medium in a non-contact manner; and contact heating means that is in contact with toner on the recording medium on a downstream side of the non-contact heating means in a conveyance direction of the recording medium. When the recording medium is metallic paper, the non-contact heating means performs control to increase a quantity of heat applied to the recording medium compared to a quantity of heat applied to white paper instead of the metallic paper.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a fixing apparatus and an image forming apparatus. [Background technology]

[0002] A fixing device is known that includes a fixing mechanism having a nip section for fixing toner on a recording medium by heat and pressure, and a preheating mechanism positioned upstream of the fixing mechanism in the recording medium transport direction for heating the recording medium without contact, wherein the preheating mechanism has a plurality of heating elements arranged sequentially in the recording medium transport direction in close proximity to the transported recording medium and which become heated during the fixing process, and a shutter positioned between the plurality of heating elements and the recording medium transport path, which controls the opening and closing of a shield that blocks radiant heat from the heating elements to the recording medium, thereby adjusting the number of heating elements exposed to the transported recording medium, wherein the opening degree of the shutter in the preheating mechanism is adjusted based on at least one of the surface glossiness, thickness, and whiteness of the recording medium (Patent Document 1).

[0003] An image forming apparatus is also known in which the recording medium is heated by far-infrared radiation to heat the recording medium. The apparatus comprises a fixing device that transports a recording medium to a nip portion formed between a fixing member controlled to a predetermined temperature by a heating means and a pressing member that presses against the fixing member, and fixes a toner image on the surface of the recording medium; a recording medium heating device located upstream of the fixing device to heat the recording medium; a glossiness measuring means for measuring the glossiness of the surface of the recording medium after the toner image has been fixed by the fixing device; and a changing means for changing and controlling the heating conditions of the recording medium heating device based on the glossiness measured by the glossiness measuring means. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2011-137963 [Patent Document 2] Japanese Patent Publication No. 2011-43683 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention provides a fixing apparatus and an image forming apparatus that can obtain sufficient fixing characteristics even when the recording medium is metallic paper. [Means for solving the problem]

[0006] In order to solve the aforementioned problem, The 1 manner The fixing device is A non-contact heating means for heating a recording medium without contact, The recording medium is further provided with a contact heating means that contacts the toner on the recording medium downstream of the non-contact heating means in the transport direction of the recording medium, The non-contact heating means controls the amount of heat supplied to the recording medium to be greater than the amount of heat supplied to white paper (not metallic paper) when the recording medium is metallic paper. It is characterized by the following ru.

[0007] In order to solve the aforementioned problem, The 2 manner The image forming apparatus is An image forming unit that forms an image on a recording medium, The 1 manner Equipped with a fixing device, It is characterized by the following: [Effects of the Invention]

[0008] The 1 manner According to this research, sufficient fixing characteristics can be obtained when the recording medium is metallic paper.

[0009] The 2 manner According to this research, sufficient fixing characteristics can be obtained even when the recording medium is metallic paper.

Brief Description of the Drawings

[0010] [Figure 1] It is a cross-sectional schematic view showing an example of the schematic configuration of an image forming apparatus including a fixing device according to the first embodiment. [Figure 2] It is a perspective view showing the schematic configuration of a paper conveyance device. [Figure 3] It is a cross-sectional schematic view showing the schematic configuration of a fixing device including a paper conveyance device. [Figure 4] It is a diagram showing an example of the relationship between the heating time and the number of times the heating element is lit at a process speed of 300 mm / sec. [Figure 5] It is a cross-sectional schematic view showing the schematic configuration of another fixing device including a paper conveyance device. [Figure 6] It is a flowchart showing the flow of the fixing operation of colored paper. [Figure 7] It is a diagram showing an example of the paper setting of the paper tray of a paper feeding device. [Figure 8] It is a diagram schematically showing a state where a color image with a white toner image is secondarily transferred onto colored paper. [Figure 9] It is a flowchart showing the flow of the fixing operation of metallic paper. [Figure 10] It is a flowchart showing the flow of the fixing operation of a modified example of metallic paper. [Figure 11] It is a diagram showing an example of a table in which the pressing conditions of the contact fixing unit included in the image forming apparatus 1 according to the second embodiment are set. [Figure 12] It is a flowchart showing the flow of setting the pressing force in the contact fixing unit. [Figure 13] It is a diagram showing an example of the paper setting of the paper tray of a paper feeding device. [Figure 14] It is a flowchart showing the flow of the fixing operation of black paper of the image forming apparatus according to the second embodiment. [Figure 15] It is a flowchart showing the flow of the fixing operation of metallic paper of the image forming apparatus according to the second embodiment. [Modes for carrying out the invention]

[0011] The present invention will now be described in more detail with reference to the drawings, with examples of embodiments and specific examples provided below, but the present invention is not limited to these embodiments and specific examples. Furthermore, it should be noted that the following diagrams used in the explanation are schematic, and the proportions of the dimensions may differ from those of reality. For ease of understanding, diagrams of components other than those necessary for the explanation have been omitted as appropriate. For the sake of easier understanding of the following explanation, in the drawings, the front-to-back direction will be the X-axis direction, the left-to-right direction will be the Y-axis direction, and the up-and-down direction will be the Z-axis direction.

[0012] "First Embodiment" (1) Overall configuration and operation of the image forming apparatus (1.1) Overall configuration of the image forming apparatus Figure 1 is a schematic cross-sectional view showing an example of the general configuration of an image forming apparatus 1 equipped with a fixing device 17 according to this embodiment. The image forming apparatus 1 comprises an image forming unit 10, a paper feed device 20 attached to one end of the image forming unit 10, a paper discharge unit 30 provided at the other end of the image forming unit 10 for ejecting printed paper, an operation display unit 40, and an image processing unit 50 that generates image information from print information transmitted from a host device.

[0013] The image forming unit 10 comprises a system control device 11 (not shown), an exposure device 12, a photoreceptor unit 13, a developing device 14, a transfer device 15, a paper transport device 16, and a fixing device 17, and forms a toner image on the paper fed by the paper feed device 20 based on the image information received from the image processing unit 50.

[0014] The paper feeder 20 supplies various types of paper to the image forming unit 10 as recording media used for image formation. Specifically, it is equipped with multiple paper stacking sections that accommodate different types of paper (for example, material, thickness, paper size, and grain), and is configured to supply paper to the image forming unit 10 by feeding it from one of these paper stacking sections.

[0015] The paper output unit 30 ejects the paper from which images have been printed by the image forming unit 10. For this purpose, the paper output unit 30 is equipped with a paper output storage unit into which the paper after image printing is ejected. The paper output unit 30 may also have a function to perform post-processing such as cutting or stapling on the stack of paper output from the image forming unit 10.

[0016] The operation display unit 40 is used for inputting various settings and instructions, and for displaying information. In other words, it corresponds to the so-called user interface, and is specifically composed of a combination of a liquid crystal display panel, various operation buttons, a touch panel, etc.

[0017] (1.2) Configuration and operation of the image forming unit In an image forming apparatus 1 with this configuration, the paper is fed to the image forming unit 10 from a tray specified in the print job for each sheet of paper in the paper feeding device 20, in accordance with the timing of image formation.

[0018] The photoreceptor unit 13 is located below the exposure device 12, with each unit arranged in parallel and comprising a photoreceptor drum 31 that acts as a rotating image holder. The charging device 32, exposure device 12, developing device 14, primary transfer roller 52, and cleaning device 34 are arranged along the rotation direction of the photoreceptor drum 31.

[0019] The developing device 14 has a developing housing 41 in which a developer is contained. A developing roller 42 is arranged inside the developing housing 41, facing the photoreceptor drum 31, and forms a toner image on the photoreceptor drum. Each developing unit 14 is configured in substantially the same way, except for the developer housed in the developing housing 41, and each forms toner images of yellow (Y), magenta (M), cyan (C), black (K), white (W), and silver (S) as a special color.

[0020] Above the developing unit 14, replaceable toner cartridges T containing developer (toner including carrier) are provided, and the developer is supplied to the developing unit 14 from each toner cartridge T.

[0021] The surface of the rotating photoreceptor drum 31 is charged by the charging device 32, and an electrostatic latent image is formed by latent image forming light emitted from the exposure device 12. The electrostatic latent image formed on the photoreceptor drum 31 is developed as a toner image by the developing roller 42.

[0022] The transfer device 15 consists of an intermediate transfer belt 51 on which the toner images of each color formed on the photoreceptor drum 31 of each photoreceptor unit 13 are transferred in multiple layers, a primary transfer roller 52 that sequentially transfers the toner images of each color formed on each photoreceptor unit 13 onto the intermediate transfer belt 51 (primary transfer), and a secondary transfer roller 53 that transfers the toner images of each color superimposed and transferred onto the intermediate transfer belt 51 onto the paper all at once (secondary transfer). The backup roller 65 contacts the secondary transfer roller 53 via the intermediate transfer belt 51, forming a secondary transfer section (TR) between the backup roller 65 and the secondary transfer roller 53.

[0023] The toner images of each color formed on the photoreceptor drum 31 of each photoreceptor unit 13 are sequentially electrostatically transferred (primary transfer) onto the intermediate transfer belt 51 by a primary transfer roller 52 to which a predetermined transfer voltage is applied from a power supply unit (not shown) controlled by the system control device 11, thereby forming a superimposed toner image in which each color toner is superimposed.

[0024] The superimposed toner image on the intermediate transfer belt 51 is transported to the secondary transfer section TR where the secondary transfer roller 53 is located as the intermediate transfer belt 51 moves. When the superimposed toner image is transported to the secondary transfer section TR, paper is supplied to the secondary transfer section TR from the paper feed device 20 at the same time. Then, a predetermined transfer voltage is applied to the backup roller 65 facing the secondary transfer roller 53 via the intermediate transfer belt 51 from a power supply device controlled by the system control device 11, and the multiple toner images on the intermediate transfer belt 51 are transferred to the paper all at once.

[0025] The fixing device 17 includes a non-contact heating unit 17A that heats the paper transported by the paper transport device 16 without contact, and a contact fixing unit 17B located downstream of the non-contact heating unit 17A that fixes the toner image on the paper through heating and pressing. The paper P onto which the toner image has been transferred in the transfer device 15 is transported to the fuser device 17 via the paper transport device 16 while the toner image is still unfixed. The paper transported to the fuser device 17 is preheated in the non-contact heating unit 17A, and the toner image is fixed in the contact fuser unit 17B by a pair of fuser rolls 171B and pressure rolls 172B through heating and pressing.

[0026] Once the fixing process is complete, the paper P is fed into the paper discharge unit 30. If image output is to be performed on both sides of the paper P, the paper transport device 18a reverses the front and back of the paper P, and it is then fed back into the secondary transfer unit TR in the image forming unit 10 via the paper transport device 18b. After the toner image is transferred and the transferred image is fixed, the paper P is fed into the paper discharge unit 30. Once fed into the paper discharge unit 30, the paper P undergoes post-processing such as cutting or stapling as needed.

[0027] (2) Configuration of the paper transport device and the fixing device Figure 2 is a perspective view showing the schematic configuration of the paper transport device 16, and Figure 3 is a schematic cross-sectional view showing the schematic configuration of the fixing device 17, including the paper transport device 16, of the image forming apparatus 1 according to this embodiment. The fixing device 17 is mainly composed of a non-contact heating section 17A, which is an example of a non-contact heating means that heats the paper transported by the paper transport device 16 without contact, and a contact fixing section 17B, which is located downstream of the non-contact heating section 17A and is an example of a contact heating means that fixes the toner image on the paper by the action of heating and pressing.

[0028] (2.1) Paper transport device As an example, the paper transport device 16 includes an endless chain member 162 that is wrapped around a plurality of sprockets 161 and moves in a circular motion, a plurality of grippers 163 provided at intervals in the circumferential direction of the chain member 162, an air blower 164 (see Figures 1 and 3) that blows air from the back side of the paper P to lift the paper P being transported, and a paper guide plate 165 having a number of air holes 165a through which the blown air passes.

[0029] The chain member 162 is moved in a circular motion by a motor (not shown) that rotates the sprocket 161 with the Y direction as its axis. The gripper 163 is driven by a motor (not shown) and is configured to grasp the downstream end (tip LE) of the paper P in the transport direction at a set timing, or to release the grasped paper P at a set timing.

[0030] When the paper transport device 16 receives the paper P in the secondary transfer section TR with the gripper 163, the chain member 162 moves, and the paper P is lifted by the air blown from the air blower 164 on the paper guide plate 165 and transported toward the contact fixing section 17B. The paper P is transported on the paper guide board 165 while being heated to a predetermined amount of heat by the non-contact heating unit 17A, which will be described later.

[0031] (2.2) Non-contact heating section The non-contact heating section 17A consists of multiple heating elements 171a, such as halogen lamps, which are arranged sequentially in the paper transport direction in close proximity to the transported paper P and become heated when energized, emitting far-infrared rays (radiant heat), and a reflector 171b that reflects the far-infrared rays (radiant heat) from the heating elements 171a towards the paper guide plate 165, thereby increasing the heating efficiency of the heating elements 171a on the paper P. Before transporting the paper P on which unfixed toner has been transferred to the contact fixing section 17B, the non-contact heating is performed from the toner transfer side (the upper side of the paper P in the figure) as a preliminary step.

[0032] In this embodiment, the heating elements 171a are installed at 30 mm intervals, and a wire mesh (not shown) is provided to prevent the paper P from entering the heating elements 171a. The non-contact heating unit 17A can change the amount of heat supplied to the paper P by changing the number of lit heating elements 171a at a predetermined paper transport speed (process speed).

[0033] Figure 4 shows an example of the relationship between heating time and the number of lit heating elements 171a at a process speed of 300 mm / sec. As shown in Figure 4, increasing the number of lit heating elements 171a increases the heating time and thus increases the amount of heat supplied to the paper P. Furthermore, the amount of heat supplied to the paper P may be increased or decreased by changing the amount of electricity supplied to the heating element 171a to change the surface temperature of the heating element 171a, or by changing the process speed.

[0034] (2.3) Contact fixing part The contact fixing section 17B is located downstream of the non-contact heating section 17A in the paper transport direction and consists of a pair of heating rolls 171B and a pressure roll 172B. The heating roll 171B is equipped with a heater QL, for example, a halogen heater, inside, which brings the surface of the heating roll to a predetermined temperature.

[0035] The heating roll 171B is composed of a support 171Ba made of a rigid metal, such as aluminum, an elastic layer 171Bb made of silicone rubber laminated on the surface side (outer surface side) of the support 171Ba, and a release layer 171Bc made of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether polymer) or the like, which is coated on the elastic layer 171Bb.

[0036] The pressure roll 172B is constructed by laminating, for example, a cylindrical metal core 172Ba, a heat-resistant elastic layer 172Bb (for example, a silicone rubber layer or a fluororubber layer) covering the outer surface of the core 172Ba, and, if necessary, a release layer 172Bc made of a heat-resistant resin coating such as PFA or a heat-resistant rubber coating. The heating roll 171B is pressed against the pressure roll 172B by a moving mechanism (not shown) to form a nip portion N. The heating roll 171B is also supported by the moving mechanism so as to be able to move toward and away from the outer surface of the pressure roll 172B, and is pressed against the paper P to a predetermined pressing force according to the paper thickness. While the moving mechanism may move the pressure roll 172B, moving the pressure roll 172B would also move the sprocket 161, potentially changing the tension of the chain member 162. Therefore, a configuration in which the moving mechanism moves the heating roll 171B is preferable.

[0037] During the fixing operation, the paper P, which holds the unfixed toner image, is passed through the nip section N, and heat and pressure are applied to fix the unfixed toner image to the paper P.

[0038] Figure 5 is a schematic cross-sectional view showing the general configuration of the other fixing device 17, including the paper transport device 16. The contact fixing section 17B may be a fixing belt module consisting of a fixing belt 720, a first tension roller 721, a second tension roller 722, and a pressing member 723, as shown in Figure 5, instead of the heating roll 171B. The pressing member 723 is provided opposite the pressure roll 172B, sandwiching the fixing belt 720, and receives the load from the pressure roll 172B. The paper P is sandwiched from both sides by the pressure roll 172B and the pressing member 723, and pressure is applied to the paper P. Furthermore, a heater QL is provided inside the first tension roller 721, the second tension roller 722, and the pressing member 723 to heat them, and the heater QL is composed of, for example, a halogen heater.

[0039] (3) Fixing operation Figure 6 is a flowchart showing the flow of the fixing operation for colored paper, Figure 7 is a diagram showing an example of the paper settings for the paper tray of the paper feeder 20, and Figure 8 is a schematic diagram showing the state in which a color image with a white toner image is secondarily transferred onto colored paper. The fixing operation in the fuser 17 will be described below with reference to the drawings. In the fixing device 17, for example, the fixing temperature of the nip portion N in the contact fixing portion 17B is kept constant, and the heating conditions (amount of heat) of the non-contact heating portion 17A are changed according to the mass, color, and type of paper being transported P.

[0040] For example, black paper, which is one example of colored paper, has a higher infrared light absorption rate than white paper, even if the basis weight is the same. Conversely, metallic paper has a lower infrared light absorption rate. Therefore, there was a risk that the fixing quality, such as fixation and gloss, would change depending on the color and type of paper P. For example, if the amount of heat supplied to the paper P did not increase as the mass of the paper P increased, there was a risk that the fixing quality would deteriorate. Furthermore, with thin paper, there was a risk of paper wrinkling occurring if the pressure conditions in the contact fixing section 17B were high.

[0041] (3.1) Fixing operation of colored paper In the fixing device 17 of this embodiment, the non-contact heating unit 17A has a condition that the amount of heat applied to the paper P when the paper P is colored is less than the amount of heat applied to the paper P when the paper P is white. For example, the system control device 11 stores a table in which the amount of heat applied to the non-contact heating unit 17A is set based on the color of the paper P, and the table has a condition set that when the paper P is colored, the amount of heat applied to the paper P is less than the amount of heat applied to the paper P when the paper P is white.

[0042] Furthermore, if the mass of the paper P is higher than a predetermined mass, the amount of heat transferred to the paper P is increased compared to when the mass of the paper P is lower than a predetermined mass.

[0043] In this way, the amount of heat generated by the non-contact heating unit 17A is controlled based on a table that sets the amount of heat generated by the non-contact heating unit 17A based on the mass and color of the paper P, and the fixing operation is performed based on the "mass" and "color" information of the paper P. The image forming apparatus 1 first acquires paper information for the paper P used in the job (S101). Paper information includes paper type, paper color, and paper mass (basis weight). This information may be detected by a paper sensor (not shown) located inside or outside the image forming apparatus 1, or it may be acquired from paper information specified via the operation display unit 40, as shown in Figure 7. For example, for the setting item "Paper Type," selecting "Uncoated Paper / Coated Paper / Recycled Paper" sets it to "White Paper," selecting "Black Paper" sets it to "Black Paper," and selecting "Metallic Paper" sets it to "Metallic Paper." Note that paper mass can be considered as information representing the thickness of the paper P. That is, the higher the paper mass, the thicker the paper P tends to be.

[0044] Next, it is determined whether the paper P is colored or not (S102). Note that the color of the paper P is determined to be colored if it is a dark color other than white, such as black, blue, or red, and the type of paper can be any of plain paper, coated paper, recycled paper, etc. If it is determined that the paper P is colored (S102: Yes), the amount of heat for the non-contact heating unit 17A is set from the table for colored paper (for example, black) (S103). On the other hand, if it is determined that the paper P is white (S102: No), the amount of heat for the non-contact heating unit 17A is set from the table for white paper (S104). In other words, if the paper P is black paper, the amount of heat for the non-contact heating unit 17A is set to be relatively small. Also, if the mass of the paper P is higher than a predetermined mass, the amount of heat supplied to the paper P is set to be greater than when the mass of the paper P is lower than a predetermined mass.

[0045] This allows the amount of heat transferred to the paper P when it is black to be less than when the paper P is white, thereby suppressing excessive heat absorption and achieving sufficient fixing characteristics even when the paper P is black.

[0046] Figure 8 schematically shows the process of first transferring a white toner image WT onto colored paper so that it overlaps the toner image (YMCK), and then secondarily transferring the color image with the white toner image WT onto colored paper P. Thus, when a colored image is formed by concealing the color of colored paper P with white toner, the absorption rate of infrared light from the non-contact heating unit 17A is lower compared to when white toner is not used. Therefore, the heat output of the non-contact heating unit 17A may not be set to be lower than the heat output of paper P when the paper color is "white". For example, the heat output of the non-contact heating unit 17A is set from a table where the paper color is white. However, if the heat output of the non-contact heating unit 17A is set higher than the conditions for colored paper, the conditions for white paper do not need to be used.

[0047] (3.2) Fixing process for metallic paper Figure 9 is a flowchart showing the process of fixing metallic paper. In the fixing device 17 of this embodiment, the non-contact heating unit 17A has a condition that the amount of heat supplied to the paper P when the paper P is metallic paper is greater than the amount of heat supplied to the paper P when the paper P is plain paper. For example, the table is set so that when the paper P is metallic paper, the amount of heat supplied to the paper P is greater than when the paper P is plain paper. Also, when the mass of the paper P is higher than a predetermined mass, the amount of heat supplied to the paper P is set to be greater than when the mass of the paper is lower than a predetermined mass.

[0048] The image forming apparatus 1 acquires paper information for the paper P used in the job (S201). Next, it is determined whether or not the paper P is "metallic paper" (S202). If the paper type is "metallic paper," the color of the paper can be anything, but it is preferable that it be "silver." If it is determined that the paper P is "metallic paper" (S202:Yes), the amount of heat for the non-contact heating unit 17A is set from the table for metallic paper (S203). On the other hand, if it is determined that the paper P is "plain paper" (S202:No), the amount of heat for the non-contact heating unit 17A is set from the table for plain paper (S204). For example, if the paper P is "metallic paper", the amount of heat for the non-contact heating unit 17A is set to be relatively higher compared to when the paper P is "plain paper" and white. If the mass of the paper P is higher than a predetermined mass, the amount of heat supplied to the paper P is set to be greater compared to when the mass of the paper is lower than a predetermined mass.

[0049] This allows the amount of heat applied to the paper P to be greater when the paper P is "metallic paper" than when the paper P is "plain paper," thereby increasing the absorption rate of infrared light and obtaining sufficient fixing characteristics even when the paper P is "metallic paper."

[0050] "Variations" Figure 10 is a flowchart showing the flow of the fixing process for metallic paper in a modified example. The image forming apparatus 1 acquires paper information for the paper P used in the job (S301). Next, it is determined whether the paper P is "metallic paper" (S302). If it is determined that the paper P is "metallic paper" (S302: Yes), the amount of heat for the non-contact heating unit 17A is set from the table for metallic paper (S304). On the other hand, if it is determined that the paper P is "plain paper" (S302: No), it is further determined whether the paper P is colored (S303). If it is determined that the paper P is colored (S303: Yes), the amount of heat for the non-contact heating unit 17A is set from the table for plain paper and colored paper (for example, black) (S305). On the other hand, if it is determined that the paper P is white (S303: No), the amount of heat for the non-contact heating unit 17A is set from the table for plain paper and colored paper (S306). In addition, if the mass of the paper P is higher than a predetermined mass, the amount of heat supplied to the paper P is set to be greater than when the mass of the paper is lower than a predetermined mass.

[0051] For example, if the paper P is "plain paper" and "black paper," the amount of heat from the non-contact heating unit 17A is set to be relatively lower compared to when the paper P is "plain paper" and "white paper." In other words, when the paper P is black paper, the amount of heat from the non-contact heating unit 17A is set to be relatively smaller than when the paper P is white paper. For example, if the paper P is "metallic paper," the heat output of the non-contact heating unit 17A is set to be relatively higher compared to when the paper P is "plain paper" and black. In other words, if the paper P is metallic paper, the heat output of the non-contact heating unit 17A is set to be relatively greater than that of black paper.

[0052] This allows the amount of heat applied to paper P to be greater when paper P is "metallic paper" than when paper P is "plain paper" and "black," thereby increasing the infrared light absorption rate and obtaining sufficient fixing characteristics even when paper P is "metallic paper."

[0053] (3.3) Operation of the contact fixing part Figure 11 shows an example of a table in which the pressurization conditions of the contact fixing section of the image forming apparatus 1 according to this embodiment are set, and Figure 12 is a flowchart showing the flow of setting the pressurization pressure in the contact fixing section 17B. The pressure (nip pressure) of the contact fixing unit 17B in the image forming apparatus 1 is set such that, regardless of the color of the paper P, the pressure is lower when the mass of the paper P is lower than a predetermined mass than when the mass is higher than a predetermined mass.

[0054] Figure 11 shows the paper type (plain paper, metallic paper), paper color (white, black), and paper weight (60-79, 80-105, 106-169, 170-256, 257-300 g / m²) for paper P. 2 An example of a table showing the nip pressure conditions of the contact fixing part 17B for ) is shown. According to the table shown in Figure 12, regardless of the paper type and paper color, the paper mass is less than or equal to a predetermined paper mass (105 g / m²). 2 In this case, the pressure applied to the contact fixing section 17B is "low" (a condition where the nip pressure is low).

[0055] The image forming apparatus 1 acquires paper information for the paper P used in the job (S401). Then, it is determined whether the mass of the paper P is lower than a predetermined mass (S402). Here, the predetermined mass is set to a paper mass of "106 g / m²". 2 It is determined whether the paper mass of paper P is greater than "106 (g / m²)". As a result, it is determined whether the paper mass of paper P is greater than "106 (g / m²)". 2 If the pressure applied by the contact fixing part 17B is less than the predetermined mass of the paper P (106-300 g / m²), the pressure applied by the contact fixing part 17B is set to less than the predetermined mass of the paper P (106-300 g / m²). 2 Set the pressure to "low" so that it is lower than the pressure applied in the case of )」) (S403). This makes it possible to suppress paper wrinkles in thin paper.

[0056] "Second Embodiment" Figure 13 shows an example of paper settings in the paper tray of the paper feeder 20, Figure 14 is a flowchart showing the flow of the black paper fixing operation in the image forming apparatus 1 according to this embodiment, and Figure 15 is a flowchart showing the flow of the metallic paper fixing operation in the image forming apparatus 1 according to this embodiment. The fixing operation in the fixing device 17 will be described below with reference to the drawings. In the fixing device 17, the fixing conditions in the contact fixing section 17B (fixing temperature in the nip section N) are kept constant, and the heating conditions (heat quantity) of the non-contact heating section 17A and the nip pressure of the contact fixing section 17B are changed according to the mass, color, and type of paper being transported P.

[0057] (1.1) Fixing operation when the paper color is black The image forming apparatus 1 acquires paper information for the paper P used in the job (S501). Paper information includes paper type, paper color, and paper mass (basis weight), and can be obtained from the paper information specified via the operation display unit 40, as shown in Figure 14. For example, for the setting item "Paper type," selecting "Other than metallized paper" sets it to "Other than metallic paper," and selecting "Metallized paper" sets it to "Metallic paper." Similarly, for the paper color, selecting "White" sets it to "White paper," and selecting "Black" sets it to "Black paper."

[0058] Next, it is determined whether the paper P is "black" (S502). If it is determined that the paper P is black (S502: Yes), the amount of heat from the non-contact heating unit 17A is set to be less than the amount of heat supplied to the paper P when the paper P is "white" (S503).

[0059] Then, it is determined whether the mass of the paper P is lower than the first mass (S504). If the mass of the paper P is lower than the first mass (S504: Yes), the amount of heat from the non-contact heating unit 17A is set to be less than when the mass of the paper P is higher than the first mass (S505). In this embodiment, the first mass used to change the amount of heat in the non-contact heating section 17A based on the mass of the paper P is, as an example, "169 g / m²". 2) and if the mass is higher than the first mass, the heat output of the non-contact heating section 17A is set higher, and if the mass is lower than the first mass, the heat output of the non-contact heating section 17A is set lower. Furthermore, the pressure applied at the nip section N of the contact fixing section 17B is set so as not to decrease compared to when the paper color is "white" (S506). In this embodiment, for example, when the paper color is "white", the mass is the first mass "169 (g / m 2 If the condition is "", the pressure applied at the nip portion N of the contact fixing portion 17B is set to "high".

[0060] Next, it is determined whether the mass of the paper P is lower than the second mass (S507). If the result is that the mass of the paper P is lower than the second mass (S507: Yes), the pressure applied at the nip portion N of the contact fixing portion 17B is set to be lower than when the mass of the paper is higher than the second mass (S508). In this embodiment, the second mass used to change the pressure applied to the contact fixing unit 17B according to the mass of the paper P is, as an example, "106 g / m²". 2 If the first mass is higher than the second mass, the pressure applied at the nip portion N of the contact fixing unit 17B is set to "high," and if the mass of the paper P is lower than the second mass (S507: Yes), the pressure applied at the nip portion N of the contact fixing unit 17B is set to "low." In this embodiment, the first and second masses that serve as the boundary for changing the setting of the pressure applied at the nip portion N of the contact fixing unit 17B are different, but depending on the table used to set the fixing conditions, they may be the same mass.

[0061] This allows for sufficient fixing characteristics when the paper P is black, while suppressing paper wrinkles regardless of whether the paper is black or not.

[0062] (1.2) Fixing operation when metallic paper is used The image forming apparatus 1 acquires paper information of the paper P used in a job (S601), and determines whether the paper P is "metallic paper" (S502). When it is determined that the paper P is metallic paper (S602: Yes), the amount of heat of the non-contact heating unit 17A is set to be larger than the amount of heat applied to the paper P when the paper P is "plain paper" (S603).

[0063] Then, it is determined whether the mass of the paper P is lower than the first mass (S604). When the mass of the paper P is lower than the first mass (S604: Yes), the amount of heat of the non-contact heating unit 17A is set to be smaller than when the mass of the paper P is higher than the first mass (S605). Here, in the present embodiment, as an example, the first mass for changing the amount of heat of the non-contact heating unit 17A according to the mass of the paper P is "256 (g / m 2 )", and when it is higher than the first mass, the amount of heat of the non-contact heating unit 17A is set high, and when it is lower than the first mass, the amount of heat of the non-contact heating unit 17A is set low. And the pressing force in the nip portion N of the contact fixing unit 17B is set not to increase compared to the case where the paper is "plain paper" (S606). In the present embodiment, for example, when the paper is "plain paper" and the mass is the first mass "256 (g / m 2 )", the pressing force in the nip portion N of the contact fixing unit 17B is set to "high".

[0064] Next, it is determined whether the mass of the paper P is lower than the second mass (S607). As a result, when the mass of the paper P is lower than the second mass (S607: Yes), the pressing force in the nip portion N of the contact fixing unit 17B is set to be decreased compared to the case where the mass of the paper is higher than the second mass (S608). Here, in the present embodiment, as an example, the second mass for changing the pressing force of the contact fixing unit 17B according to the mass of the paper P is "106 (g / m 2 )", and when it is higher than the second mass, the pressing force in the nip portion N of the contact fixing unit

[0065] This allows for sufficient fixing characteristics when paper P is metallic paper, while suppressing paper wrinkles regardless of whether the paper is metallic or not.

[0066] As shown in the table in Figure 11, the nip pressure of the contact fixing unit 17B is controlled according to the paper mass information, regardless of the paper type and paper color information. However, it is also possible to determine the nip pressure according to the other information and the paper mass information, regardless of either the paper type or paper color information. For example, regardless of the paper color information, the nip pressure could be increased for metallic paper compared to plain paper. In this case, while suppressing paper wrinkles regardless of the paper color, the glossiness of the toner surface can be brought closer to that of metallic paper by fixing the toner image at a higher pressure when using metallic paper. [Explanation of Symbols]

[0067] 1. Image forming apparatus 10. Image Forming Unit 12. Exposure equipment 13. Photoconductor Unit 14. Developing equipment 15. Transfer device 16. Paper transport device 161... Sprocket 162... Chain components 163... Grippa 164...Air blower 165... Paper information board 17. Fixing device 17A...Non-contact heating section 17B... Contact fixing section 20. Paper feeder 30... Paper output section 40...Operation display section 50...Image Processing Unit

Claims

1. A non-contact heating means for heating a recording medium without contact, The recording medium is further provided with a contact heating means that contacts the toner on the recording medium downstream of the non-contact heating means in the transport direction of the recording medium, When the non-contact heating means determines that the recording medium is metallic paper, it controls the amount of heat supplied to the recording medium to be greater than the amount of heat supplied to white paper that is not metallic paper. The contact heating means controls the pressure applied to the recording medium to be less than the pressure applied at a predetermined basis weight if the basis weight of the recording medium is less than a predetermined basis weight, and controls the pressure applied to the recording medium to be greater than the pressure applied when the recording medium is metallic paper compared to when it is white paper that is not metallic. A fixing device characterized by the following features.

2. An image forming unit that forms an image on a recording medium, A fixing device according to claim 1, comprising: An image forming apparatus characterized by the following:

Images