JP2010164961A - Fixing apparatus, gloss processing apparatus, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus capable of improving image quality of the second side of a recording medium after passing through a fixing nip. <P>SOLUTION: The apparatus includes at least: fixing means (a fixing apparatus 5A) for fixing an image on a second side (Pb) of a recording medium (a print sheet P) after fixing an image on a first side (Pa) of the recording medium and reversing it; detection means (a temperature sensor 400) for detecting, at the fixing means, a maximum temperature of the first side of the recording medium after passing through the fixing nip; and temperature controlling means (a temperature controlling device 500) for controlling temperature of the first side of the recording medium after passing through the fixing nip so that the maximum temperature may not reach a predetermined temperature range in accordance with a predicted maximum temperature of the first side of the recording medium detected by the detection means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing device, a gloss processing device, and an image forming apparatus.

  Conventionally, an image forming apparatus for forming an image by forming an unfixed image on a printing paper as a recording medium using a colorant (developer) such as toner, and fixing the unfixed image by heating and pressing. , Pressurizing and rotating printing paper holding an unfixed image onto an endless belt that is heated and rotated so that the image to be formed has a smooth surface and excellent gloss There is a type using a fixing device and a gloss processing device of a type in which after fixing by pressure contact with a body, cooling is performed in a state in which the belt is in close contact with the belt, and separation is performed by fixing from the belt.

  Various techniques relating to such an image forming apparatus that can improve glossiness have been proposed.

  For example, in Japanese Patent Laid-Open No. 2002-287466, in order to prevent the temperature of the photosensitive drum from rising during double-sided printing, the first fixing temperature is set during single-sided printing, while a predetermined number of sheets are printed during double-sided printing. A technique for gradually changing from a first fixing temperature to a second fixing temperature is disclosed.

  Japanese Patent Laid-Open No. 2003-015464 discloses a technique for lowering the fixing temperature when a predetermined number of sheets are exceeded during backside fixing during double-sided copying in order to increase energy consumption efficiency.

  Japanese Patent Laid-Open No. 2003-255755 discloses a setting temperature of a heating member at the time of image heating on the front and back surfaces in order to prevent a difference in glossiness between the front and back surfaces during double-sided printing and image disturbance due to toner remelting. Further, a technique is disclosed in which the temperature is set lower than the set temperature when image heating is performed on only one side, and the set temperature during image heating on the front surface is set lower than the set temperature during image heating on the back surface.

JP 2002-287666 A JP 2003-015464 A JP 2003-255755 A

  An object of the present invention is to improve the image quality of the second surface of a recording medium after a fixing nip.

  In order to solve the above problem, the fixing device according to the first aspect of the present invention fixes the image on the first surface of the recording medium, and then fixes the image on the second surface by inverting the front and back of the recording medium. Based on the maximum temperature predicted value of the first surface of the recording medium obtained by the acquiring means, the acquisition means for acquiring the maximum temperature predicted value of the first surface of the recording medium after the fixing nip by the fixing means, And a temperature control means for performing temperature control so that the maximum temperature of the first surface of the recording medium after the fixing nip by the fixing means does not fall within a predetermined temperature range.

  According to a second aspect of the present invention, there is provided a fixing device according to the first aspect, wherein the determination unit determines whether or not the maximum temperature can be lower than the temperature range based on the predicted maximum temperature value acquired by the acquisition unit. And the temperature control means determines the temperature of the first surface of the recording medium after the fixing nip by the fixing means when the determination means determines that the maximum temperature can be lower than the temperature range. When the determination unit determines that the maximum temperature cannot be lower than the temperature range, the fixing unit sets the temperature of the first surface of the recording medium after the fixing nip to the temperature. Control is performed so as to be over the range.

  According to a third aspect of the present invention, there is provided a fixing device according to the first aspect, comprising: a table storage unit storing a table relating to a first surface temperature corresponding to a basis weight of the recording medium and a fixing condition; The means is a maximum temperature of the first surface of the recording medium after the fixing nip by the fixing device based on the temperature of the first surface of the recording medium stored in the table storage device and the basis weight and the fixing condition. The temperature is controlled so that the temperature does not fall within the temperature range.

  According to a fourth aspect of the present invention, there is provided the fixing device according to any one of the first to third aspects, wherein the maximum temperature of the first surface acquired by the acquisition unit is preset in the temperature control unit. The first side of the recording medium after the fixing nip is cooled when it is determined that it is below the first threshold value, and after the fixing nip is determined when it is determined that it is above the preset second threshold value. The image forming apparatus includes a cooling unit that is controlled so as not to cool the first surface of the recording medium.

  A fixing device according to a fifth aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the temperature control means sets in advance a maximum temperature of the first surface acquired by the acquisition means. When the recording medium is determined to be below the third threshold, the first surface of the recording medium is heated after the fixing nip. When it is determined that the recording medium is equal to or higher than the preset fourth threshold, The image forming apparatus includes a heating unit that is controlled so as not to heat the first surface of the recording medium.

  According to a sixth aspect of the present invention, there is provided a fixing device according to the fourth or fifth aspect, wherein at least one of the first threshold value, the second threshold value, the third threshold value, and the fourth threshold value. One is characterized by the melting point temperature of the wax contained in the color material used for image formation on the recording medium.

  The fixing device according to a seventh aspect of the present invention is the fixing device according to the sixth aspect, wherein the temperature range is a temperature range in which the wax contained in the color material melts.

  According to an eighth aspect of the present invention, there is provided a gloss processing apparatus, the fixing device according to any one of the first to seventh aspects, an endless belt that is wound around a plurality of members and rotates, and heats the belt. The apparatus includes at least a belt heating unit and a fixing nip member that press-contacts the recording medium as an object to be glossed against the belt heated by the belt heating unit.

  According to a ninth aspect of the present invention, an image forming apparatus includes the fixing device according to any one of the first to seventh aspects or the gloss processing device according to the eighth aspect.

  According to the present invention, the following effects can be obtained.

  That is, according to the first aspect of the present invention, the image quality of the second surface of the recording medium after the fixing nip can be improved as compared with the case where this configuration is not provided.

  According to the second aspect of the present invention, the glossiness can be improved by controlling the temperature of the back surface of the recording medium after the fixing nip as compared with the case where the present configuration is not provided.

  According to the third aspect of the present invention, as compared with the case where this configuration is not provided, the gloss of the back surface of the recording medium after the fixing nip is controlled by controlling the temperature according to the basis weight of the recording medium and the fixing conditions. Can be improved.

  According to the fourth aspect of the present invention, the cooling control based on the first threshold value and the second threshold value is performed and the rear surface of the recording medium after the fixing nip is compared with the case where the present configuration is not provided. Glossiness can be improved.

  According to the fifth aspect of the present invention, the heating control based on the third threshold value and the fourth threshold value is performed and the rear surface of the recording medium after the fixing nip is compared with the case where this configuration is not provided. Glossiness can be improved.

  According to the sixth aspect of the present invention, the back surface of the recording medium after the fixing nip is performed by performing temperature control using the melting point temperature of the wax contained in the color material as a threshold value, as compared with the case where this configuration is not provided. Can improve the glossiness.

  According to the seventh aspect of the present invention, the glossiness of the back surface of the recording medium after the fixing nip can be improved as compared with the case where this configuration is not provided.

  According to the eighth aspect of the present invention, the glossiness can be improved by controlling the temperature of the back surface of the recording medium after the fixing nip as compared with the case where the present configuration is not provided.

  According to the ninth aspect of the present invention, the glossiness can be improved by controlling the temperature of the back surface of the recording medium after the fixing nip as compared with the case where this configuration is not provided.

1 is a schematic configuration diagram illustrating a configuration of an image forming apparatus PR1 according to a first embodiment. FIG. 2 is a schematic configuration diagram illustrating a configuration of a fixing device 5A of the image forming apparatus PR1 according to the first embodiment. It is explanatory drawing which shows the structural example of the table of a back surface (1st surface) temperature. 6 is a graph showing a temperature change of the printing paper P. 3 is a functional block showing a configuration of an image forming apparatus PR1 according to the first embodiment. It is a flowchart which shows the process sequence of a cooling process. It is a flowchart which shows the other process sequence of a cooling process. FIG. 6 is a schematic configuration diagram illustrating a configuration of a secondary fixing device 5B of an image forming apparatus PR2 according to a second embodiment. 4 is a functional block showing a configuration of an image forming apparatus PR2 according to a second embodiment. It is explanatory drawing which shows the structural example of the table of a back surface (1st surface) temperature. It is a flowchart which shows the process sequence of heat processing. It is a flowchart which shows the other process sequence of heat processing. 12 is a functional block showing a configuration of an image forming apparatus PR3 according to a third embodiment. It is explanatory drawing which shows the structural example of the table of temperature. It is a flowchart which shows the process sequence of a cooling process. It is a flowchart which shows the process sequence of heat processing. It is a functional block which shows the structure of image forming apparatus PR4 which concerns on 4th Embodiment. It is a flowchart which shows the process sequence of a cooling process. It is a flowchart which shows the process sequence of heat processing.

  Hereinafter, an embodiment as an example of the present invention will be described in detail with reference to the drawings. Here, in the accompanying drawings, the same reference numerals are given to the same members, and duplicate descriptions are omitted. In addition, since description here is the best form by which this invention is implemented, this invention is not limited to the said form.

  (First embodiment)

  An image forming apparatus PR1 according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a configuration diagram showing the configuration of a color printer PR1 (an example of an image forming apparatus) according to the first embodiment.

  First, the basic configuration of the color printer PR1 will be described.

  The color printer PR1 is roughly divided into an image forming unit, an intermediate transfer unit, a paper transport unit, a primary fixing device 4, a secondary fixing device (fixing device) 5A, a cutting device 6, a document reading device 7, and a first paper discharge. A tray 101, a second paper discharge tray 102, and the like are included.

  The image forming unit includes image forming units 1Y to 1K corresponding to yellow (Y), magenta (M), cyan (C), and black (K), an exposure unit 12, and toner tanks 17Y to 17K. Yes.

  Each image forming unit 1 includes a photosensitive drum 10 as an image carrier that is rotationally driven in the direction of arrow A in the figure, a charging roll 11 that is disposed around the photosensitive drum 10, a developing device 13, and a primary unit. A transfer roll 14, a photoreceptor cleaning device 15, and a static elimination roll 16 are provided.

  The intermediate transfer unit supports an intermediate transfer belt 20 as an image carrier that is rotationally driven in the direction of arrow B in the drawing at the same moving speed as the peripheral speed of the photosensitive drum 10, and the intermediate transfer belt 20 is rotatable. A steering roller 23 that sandwiches the intermediate transfer belt 20, a belt cleaning device 24 that faces the steering roll 23, a backup roll 22, and a secondary transfer roll 21 that sandwiches the intermediate transfer belt 20 and faces the backup roll 22.

  The paper transport unit includes a first paper tray 30A and a second paper tray 30B in which different types of printing paper P (an example of a recording medium) are stored, pickups 31A and 31B, a pair of separating rolls 32B and 32B, and a pair of transport rolls. 33, 34, a resist roll pair 35, a path switching chute 36, a first discharge roll pair 37, and a second discharge roll pair 38.

  In this embodiment, the paper tray 30A contains postcard size printing paper P1, and the paper tray 30B contains A3 size printing paper P2.

  Note that the printing paper P used in the present embodiment has an image receiving layer made of the same type of resin as the resin (wax) constituting the toner base material on the first side Pa and the second side Pb. .

  Next, the basic operation of the color printer PR1 will be described.

  The color printer PR1 receives color image information sent from a host computer such as a personal computer (not shown), color image information of a color document read by the document reading device 7, and the like.

  In the color printer PR1, the input color image information is subjected to shading correction, position shift correction, lightness / color space conversion, gamma correction, frame erasing, color / color reduction by an image processing device (not shown) as necessary. Predetermined image processing such as moving editing is performed.

  Next, the image data that has been subjected to the predetermined image processing by the image processing apparatus as described above has four colors of yellow (Y), magenta (M), cyan (C), and black (K) (8 bits each). It is sent to the exposure unit 12 as material gradation data, and the exposure unit 12 performs image exposure with laser light in accordance with the original color material gradation data.

  The exposure unit 12 modulates a semiconductor laser (not shown) according to the original reproduction color material gradation data, emits a laser beam LB from the semiconductor laser according to the gradation data, and scans and exposes the laser beam LB. As a result, an electrostatic latent image is formed.

  The electrostatic latent images formed on the photosensitive drums 10Y to 10K are, for example, developed by four color developing devices 13Y to 13K of yellow (Y), magenta (M), cyan (C), and black (K). The toner image T is reversely developed with toner (charged color material) charged to a negative polarity that is the same polarity as the charged polarity of the photosensitive drum 10, and a toner image T of a predetermined color is obtained.

  Further, toner is supplied from the toner tanks 17Y to 17K as necessary.

  The toner images T (Y) to (K) of the respective colors formed on the photosensitive drum 10 are primary-transferred by primary transfer rolls 14Y to 14K on an intermediate transfer belt 20 disposed on the upper side of the photosensitive drum 10. Transcribed.

  On the intermediate transfer belt 20, all four colors of yellow (Y), magenta (M), cyan (C), and black (K) formed on the photosensitive drum 10 are formed according to the color of the image to be formed. Alternatively, a part of the toner images T (Y) to (K) is transferred in a state where the toner images T (Y) to (K) are sequentially superimposed by the primary transfer rolls 14Y to 14K.

  The toner image T (F) transferred onto the intermediate transfer belt 20 is conveyed to a secondary transfer position where the secondary transfer roll 21 and the backup roll 22 face each other at a predetermined timing.

  On the other hand, the printing paper P selected by the user is transported from the paper tray 30 and transported on the transport path by the pickups 31A and 31B, the pair of scooping rolls 32B and 32B, and the pair of transporting rolls 33 and 34. Once stopped.

  Then, in synchronization with the timing at which the toner image T (F) on the intermediate transfer belt 20 reaches the secondary transfer position, the registration roll pair conveys the printing paper P to the secondary transfer position.

  The toner image T (F) is transferred onto the printing paper P from the intermediate transfer belt 20 by the pressing force and electrostatic attraction force of the secondary transfer roll 21.

  The printing paper P on which the toner image T (F) is secondarily transferred is then primarily fixed by the primary fixing device.

  When the high gloss processing is not performed according to an instruction from the user, the first transport path is selected by the path switching chute 36 and discharged to the first discharge tray 101 by the first discharge roll pair 37. .

  Further, in the case where high gloss processing is performed in accordance with an instruction from the user, the second transport path is selected by the path switching chute 36 and transported to the secondary fixing device 5 by the first discharge roll pair 37, which will be described later. Glossy treatment is applied.

  Thereafter, the printing paper P is cut off at the four corners by the cutting device 6 and discharged to the second paper discharge tray 102 in a state in which no margin exists.

  In the color printer PR1 according to the present embodiment, after fixing an image on the first surface Pa of the printing paper P, the front and back of the printing paper P are reversed and the image is fixed on the second surface Pb. Is provided with a reversing mechanism (double-sided printing function) 600.

  When the color printer PR1 fixes images on both sides (first side Pa and second side Pb) of the printing paper P, the printing paper P with the image fixed on the first side Pa is transferred to the first paper discharge tray 101. Alternatively, the conveyance direction of the printing paper P is reversed by the reversing mechanism 600 without being discharged to the second paper discharge tray 102.

  Next, the printing paper P, whose conveyance direction is reversed by the reversing mechanism 600, is conveyed again to the secondary fixing device (fixing device) 5A and the like, and a predetermined image is fixed on the second surface Pb by the above-described procedure. After that, the paper is discharged to the second paper discharge tray 102. As a result, the occurrence of gloss unevenness is suppressed and the image is fixed on both surfaces (first surface Pa and second surface Pb) of the printing paper P in a state where the image quality is improved.

  Next, the configuration of the fixing device 5A will be described with reference to FIG.

  FIG. 2 is a schematic cross-sectional view illustrating the configuration of the fixing device 5A.

  First, the configuration of the fixing device 5A will be described.

  The fixing device 5A includes an endless fixing belt 50 (an example of a fixing unit), a heating roll 51 that rotatably supports the fixing belt 50, a peeling roll 52, and three rotary rolls including a walk control roll 53. A pressure roll 54 (an example of a fixing unit) that forms a nip portion N by pressing the fixing belt 50 and a heating roll 51 (an example of a fixing unit), and a nip portion N disposed in a hollow portion of the heating roll 51. A temperature sensor 400 (an example of an acquisition unit) that measures (acquires) the maximum temperature of the second surface Pb of the printing paper P after the fixing nip at the nip portion N, and a microcomputer or the like. By the temperature controller 500 (an example of the temperature controller) that is configured and the temperature controller 500 based on the maximum temperature of the first surface Pa measured by the temperature sensor 400. A cooling device 200 (an example of a cooling unit) that cools the first surface Pa of the printing paper P after the fixing nip at the nip N, and a heat sink 56 that cools the second surface Pb side of the printing paper P that is in close contact with the fixing belt 50. , Guide guides 57a and 57b for guiding the printing paper P to the nip N, peeling guides 58a and 58b for assisting the peeling of the printing paper P from the fixing belt 50, and a transport roll for transporting the peeled printing paper P And a pair 59.

  Note that the microcomputer or the like constituting the temperature control device 500 also serves as a determination unit described later.

  In addition, the temperature sensor 400 is not particularly limited, but is constituted by, for example, a radiation thermometer. Note that the temperature sensor 400 may be omitted when control using a table as shown in FIG. 3 is performed.

  The cooling device 200 is not particularly limited, but in the present embodiment, the cooling device 200 includes an electric motor 201 capable of controlling the number of rotations under the control of the temperature control device 500 and a blower fan 202 provided on the rotation shaft thereof. The Accordingly, a desired cooling effect is expected by appropriately increasing or decreasing the amount of air sent to the first surface Pa side of the printing paper P.

  In addition to the air cooling method as described above, the cooling device 200 is, for example, a method in which a cooling roll of a heat transfer material cooled by a refrigerant flow or a Peltier element is brought into contact with the first surface Pa of the printing paper P and the like. It is also possible to use.

  Further, when the maximum temperature acquired by the temperature sensor 400 can be lower than a predetermined range of temperatures, the temperature control device 500 sets the temperature of the first surface Pa of the printing paper P after the fixing nip to a predetermined temperature range or less. If the maximum temperature cannot be lower than a predetermined range, the temperature of the first surface Pa of the printing paper P after the fixing nip is controlled to be equal to or higher than the predetermined temperature range. .

  For example, the maximum temperature of the first surface Pa corresponding to the basis weight (thickness) of the printing paper P and the fixing conditions (temperature, nip time, etc.) A table relating to threshold values (first threshold value, second threshold value) is stored, and cooling control is performed based on the data.

  The temperature in the predetermined range may be a temperature range in which a resin (wax) constituting the toner base material melts.

  As a cooling control method, for example, when it is determined that the acquired maximum temperature of the first surface Pa is equal to or lower than a preset first threshold value, the cooling of the first surface Pa of the printing paper P after the fixing nip is performed. When it is determined that the second threshold value is set to be equal to or greater than a preset second threshold value, control is performed so that the first surface Pa of the printing paper P after the fixing nip is not cooled.

  Here, FIG. 3 shows a configuration example of the table.

  In the example of FIG. 3, modes 1 to 4 that can be selected by the user according to the paper basis weight (g / square meter) and the like are prepared.

  Specifically, in “mode 1”, the paper basis weight is 100 to 150 (g / square meter), the paper back surface (first side Pa) temperature is 105 to 115 ° C., the threshold value is 90 ° C., and the corresponding control operation is “cooling”. None ”.

  In “Mode 2”, the paper basis weight is 150 to 200 (g / square meter), the paper back surface (first side Pa) temperature is 95 to 105 ° C., the threshold value is 90 ° C., and the corresponding control operation is “no cooling”. It has become.

  In “Mode 3”, the paper basis weight is 200 to 250 (g / square meter), the paper back surface (first side Pa) temperature is 85 to 95 ° C., the threshold value is 90 ° C., and the corresponding control operation is “cooling”. ing.

  In “mode 4”, the paper basis weight is 250 to 300 (g / square meter), the paper back surface (first side Pa) temperature is 80 to 90 ° C., the threshold value is 90 ° C., and the corresponding control operation is “cooling”. ing.

  In the example shown in FIG. 3, the case where the threshold value is one (that is, the first threshold value and the second threshold value are the same) is shown, but the present invention is not limited to this, and the first threshold value and the second threshold value You can set a different value for.

  Although not particularly limited, in the present embodiment, the threshold value is the melting point temperature (90 ° C.) of the resin (wax) constituting the toner base material.

  A specific cooling processing procedure will be described later.

  Returning to FIG. 1, on the inner surface side of the fixing belt 50, between the heating roll 51 and the peeling roll 44, a cooling heat sink 56 that contacts the fixing belt 50 and forcibly cools is disposed. Yes.

  In order to assist the close contact between the conveyed printing paper P and the fixing belt 50, a biasing roll (not shown) that biases the printing paper P to the fixing belt 50 at a position facing the heat sink 56 with the fixing belt 50 interposed therebetween. Is provided.

  A small-diameter tension roll (not shown) that applies a constant tension to the fixing belt 50 is disposed between the cooling heat sink 56 and the heating roll 51.

  Here, the operation of the fixing device 5A will be described.

  The fixing of the image on the first surface Pa of the printing paper P is finished, and the front and back of the printing paper P are reversed by a reversing mechanism (not shown) to fix the image on the second surface Pb of the printing paper P. Shall.

  First, the toner image T (F) is transferred to the second surface Pb, and the primary fixed printing paper P is guided by the guide guide 57 and enters the nip portion N with the image surface side facing the fixing belt 50.

  In the nip portion N, the toner constituting the toner image T (F) is melted by the action of the heat from the halogen heater 55 and the pressure from the pressure roll 54 (the toner is substantially about 120 to 150 ° C.). The toner image T (F) is buried in the image receiving layer of the printing paper P softened by heat.

  Even after the nip portion N is removed, the second surface Pb of the printing paper P is conveyed while being in close contact with the fixing belt 50.

  Next, the first surface Pa of the printing paper P after the fixing nip at the nip portion N is air-cooled by the cooling device 200 that operates under the control of the temperature control device 500.

  More specifically, for example, as shown in the graph showing the temperature change of the printing paper P in FIG. 4 (the graph showing the relationship between the temperature and the time), it takes about 0.7 seconds (control interval) after the nip. Then, cooling by the cooling device 200 is executed.

  Thereby, the temperature of the first surface Pa of the printing paper P is cooled to a temperature within a predetermined range (in this embodiment, a temperature range in which the wax contained in the color material melts).

  The cooling device 200 is expected to have a more efficient cooling effect as it is closer to the nip portion N.

  Here, in the image forming apparatus as a comparison target that does not include the fixing device 5A according to the present embodiment, output is performed under a fixing condition in which the maximum temperature of the back surface (first surface) at the time of fixing the second surface is within a predetermined temperature range. In this case, gloss (gloss) unevenness occurs in the first image.

  This unevenness of gloss (gloss) is caused when the back surface (first surface) maximum temperature is within a certain temperature range when fixing the second surface, and the wax inside the toner layer becomes a semi-molten state and is flattened from a spherical shape to cause internal scattering. This is considered to occur because of the cause, and as a result, gloss unevenness in the image plane is caused.

  On the other hand, in the image forming apparatus PR1 according to the present embodiment, by controlling the cooling so that the maximum back surface (first surface) temperature does not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed and the image quality is improved. Is done.

  FIG. 5 is a functional block diagram showing the configuration of the main part of the color printer PR1 according to this embodiment.

  As shown in FIG. 5, the temperature controller 500 includes a table storage unit 501 for storing a table as shown in FIG. 3 and a mode selection unit 502 configured by buttons and the like for the user to select the above-described modes. It is connected.

  Here, with reference to the flowchart of FIG. 6, the processing procedure of the cooling process executed by the color printer PR1 according to the present embodiment will be described.

  When this process is started, first, in step S100, the user operates the mode selection unit 502 to select a desired mode (modes 1 to 4: see FIG. 3), and the process proceeds to step S101.

  In step S101, referring to a table as shown in FIG. 3, whether or not the back surface (first surface) temperature on the table is higher than a threshold value (90 ° C. in the present embodiment) serves as a determination means. It is determined by an apparatus (microcomputer or the like) 500.

  According to the table shown in FIG. 3, when mode 1 and mode 2 are selected, it is determined as “Yes”, and when mode 3 and mode 4 are selected, it is determined as “No”.

  In the case of “Yes”, the process proceeds to step S103, the printing process is executed as it is, and the process is terminated.

  On the other hand, in the case of “No”, the process proceeds to step S102, the back surface (first surface) is cooled by the cooling device 200, then the process proceeds to step S103, the printing process is performed, and the process is terminated.

  Thus, the cooling is controlled so that the maximum back surface (first surface) temperature does not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed, and the image quality is improved.

  Next, another processing procedure of the cooling process will be described with reference to the flowchart of FIG.

  When this process is started, first, in step S200, the user operates the mode selection unit 502 to select a desired mode (modes 1 to 4: see FIG. 3), and the process proceeds to step S201.

  In step S201, the printing process for the first page is executed, and the process proceeds to step S202.

  In step S202, a temperature control device (microcomputer) that also serves as a determination means whether or not the back surface (first surface) temperature measured by the temperature sensor 400 during printing of the first surface is higher than a threshold value (90 ° C. in the present embodiment). Etc.) It is determined by 500.

  In the case of “Yes”, the process proceeds to step S204, the printing process is executed as it is, and the process ends.

  On the other hand, if “No”, the process proceeds to step S203, the cooling of the back surface (first surface) by the cooling device 200 is turned on, then the process proceeds to step S103, the printing process is executed, and the process ends.

  Thus, the cooling is controlled so that the maximum back surface (first surface) temperature does not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed, and the image quality is improved.

  (Second Embodiment)

  With reference to FIGS. 8 to 12, an image forming apparatus (color printer) PR2 according to a second embodiment of the present invention will be described.

  The main configuration of the image forming apparatus PR2 according to the second embodiment is the same as that of the image forming apparatus PR1 according to the first embodiment shown in FIG.

  The image forming apparatus PR2 according to the second embodiment is different from the image forming apparatus PR1 according to the first embodiment in that a heating device 300 is used instead of the cooling device 200 in the fixing device 5B shown in FIG. It is a point provided.

  The main part of the image forming apparatus PR2 is shown in the functional block diagram of FIG.

  The temperature control device 500 is configured by a microcomputer or the like, and also serves as a determination unit described later.

  As shown in FIG. 9, the temperature control device 500 includes a table storage unit 501 for storing a table as shown in FIG. 10 and a mode selection unit 502 composed of buttons and the like for the user to select the above-described modes. It is connected.

  In addition, the temperature sensor 400 is not particularly limited, but is constituted by, for example, a radiation thermometer.

  Note that the temperature sensor 400 can be omitted when control using a table as shown in FIG. 10 is performed.

  In addition, although the heating device 300 is not particularly limited, in the present embodiment, the heating device 300 is configured by an electric heater 300 that can control supply power by the control of the temperature control device 500. Accordingly, a desired heating effect is expected by appropriately increasing or decreasing the amount of heat applied to the first surface Pa side of the printing paper P.

  In addition to the irradiation method as described above, the heating device 300 includes, for example, a heating method using a warm air fan, a heating roll of a heat transfer material heated by circulation of a heat medium, a Peltier element, or the like on the first surface of the printing paper P. It is also conceivable to use a method of heating by contacting with Pa.

  Further, when the maximum temperature acquired by the temperature sensor 400 can be lower than a predetermined range of temperatures, the temperature control device 500 sets the temperature of the first surface Pa of the printing paper P after the fixing nip to a predetermined range of temperatures. If the maximum temperature cannot be lowered below a predetermined temperature range, the temperature of the first surface Pa of the printing paper P after the fixing nip is controlled to be equal to or higher than the temperature in the predetermined range. To do.

  For example, the maximum temperature of the first surface Pa corresponding to the basis weight (thickness) of the printing paper P and the fixing conditions (temperature, nip time, etc.) in a table storage means composed of a non-volatile memory such as ROM or flash memory, A table relating to threshold values (third threshold value, fourth threshold value) is stored, and cooling control is performed based on the data.

  The temperature in the predetermined range may be a temperature range in which a resin (wax) constituting the toner base material melts.

  As a heating control method, for example, when it is determined that the acquired maximum temperature of the first surface Pa is equal to or lower than a preset third threshold value, the heating of the first surface Pa of the printing paper P after the fixing nip is performed. In the case where it is determined that the value is equal to or greater than a preset fourth threshold value, control is performed so as not to heat the first surface Pa of the printing paper P after the fixing nip.

  Here, FIG. 10 shows a configuration example of the table.

  In the example of FIG. 10, modes 1 to 4 that can be selected by the user according to the paper basis weight (g / square meter) and the like are prepared.

  Specifically, in “mode 1”, the paper basis weight is 100 to 150 (g / square meter), the paper back surface (first side Pa) temperature is 105 to 115 ° C., the threshold value is 90 ° C., and the corresponding control operation is “heating” None ”.

  In “Mode 2”, the paper basis weight is 150 to 200 (g / square meter), the paper back surface (first side Pa) temperature is 95 to 105 ° C., the threshold value is 90 ° C., and the corresponding control operation is “no heating”. It has become.

  In “Mode 3”, the paper basis weight is 200 to 250 (g / square meter), the paper back surface (first side Pa) temperature is 85 to 95 ° C., the threshold value is 90 ° C., and the corresponding control operation is “heating”. ing.

  In “mode 4”, the paper basis weight is 250 to 300 (g / square meter), the paper back surface (first side Pa) temperature is 80 to 90 ° C., the threshold value is 90 ° C., and the corresponding control operation is “heating”. ing.

  In the example illustrated in FIG. 10, the case where the threshold value is one (that is, the third threshold value and the fourth threshold value are the same) has been described. You can set a different value for.

  Although not particularly limited, in the present embodiment, the threshold value is the melting point temperature (90 ° C.) of the resin (wax) constituting the toner base material.

  Here, the operation of the fixing device 5B will be described.

  The fixing of the image on the first surface Pa of the printing paper P is completed, and the front and back of the printing paper P are reversed by a reversing mechanism (not shown in FIG. 1), and the fixing of the image to the second surface Pb of the printing paper P is performed. It is assumed that it is a stage to perform.

  First, the toner image T (F) is transferred to the second surface Pb, and the primary fixed printing paper P is guided by the guide guide 57 and enters the nip portion N with the image surface side facing the fixing belt 50.

  In the nip portion N, the toner constituting the toner image T (F) is melted by the action of the heat from the halogen heater 55 and the pressure from the pressure roll 54 (the toner is substantially about 120 to 150 ° C.). The toner image T (F) is buried in the image receiving layer of the printing paper P softened by heat.

  Even after the nip portion N is removed, the second surface Pb of the printing paper P is conveyed while being in close contact with the fixing belt 50.

  Next, the first surface Pa of the printing paper P after the fixing nip at the nip portion N is heated by the heating device 300 that operates under the control of the temperature control device 500.

  The heating device 300 is expected to have a more efficient heating effect as it is closer to the nip portion N.

  Here, in the image forming apparatus as a comparison target that does not include the fixing device 5B according to the present embodiment, output is performed under a fixing condition in which the maximum temperature of the back surface (first surface) at the time of fixing the second surface is within a predetermined temperature range. In this case, gloss (gloss) unevenness occurs in the first image.

  On the other hand, in the image forming apparatus PR2 according to the present embodiment, by controlling the heating so that the maximum back surface (first surface) temperature does not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed and the image quality is improved. Is done.

  Here, with reference to the flowchart of FIG. 11, the processing procedure of the heating process executed by the color printer PR2 according to the present embodiment will be described.

  When this process is started, first, in step S300, the user operates the mode selection unit 502 to select a desired mode (modes 1 to 4: see FIG. 10), and the process proceeds to step S301.

  In step S301, referring to a table as shown in FIG. 10, whether or not the back surface (first surface) temperature on the table is higher than a threshold value (90 ° C. in the present embodiment) also serves as a determination unit. It is determined by an apparatus (microcomputer or the like) 500.

  According to the table shown in FIG. 10, when mode 1 and mode 2 are selected, it is determined as “Yes”, and when mode 3 and mode 4 are selected, it is determined as “No”.

  In the case of “Yes”, the process proceeds to step S303, the printing process is executed as it is, and the process is terminated.

  On the other hand, in the case of “No”, the process proceeds to step S302, the heating of the back surface (first surface) by the heating device 300 is performed, then the process proceeds to step S303, the printing process is performed, and the process is terminated.

  As a result, the heating is controlled so that the maximum rear surface (first surface) temperature does not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed, and the image quality is improved.

  Next, another processing procedure of the heating process will be described with reference to the flowchart of FIG.

  When this process is started, first, in step S400, the user operates the mode selection unit 502 to select a desired mode (modes 1 to 4: see FIG. 10), and the process proceeds to step S401.

  In step S401, the printing process for the first page is executed, and the process proceeds to step S402.

  In step S402, a temperature control device (microcomputer) that also serves as a determination unit whether or not the back surface (first surface) temperature measured by the temperature sensor 400 during printing of the first surface is higher than a threshold value (90 ° C. in the present embodiment). Etc.) It is determined by 500.

  In the case of “Yes”, the process proceeds to step S404, the printing process is executed as it is, and the process ends.

  On the other hand, if “No”, the process proceeds to step S403, the heating of the back surface (first surface) by the heating device 300 is turned on, then the process proceeds to step S403, the printing process is executed, and the process ends.

  As a result, the heating is controlled so that the maximum rear surface (first surface) temperature does not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed, and the image quality is improved.

  (Third embodiment)

  With reference to FIGS. 13 to 16, an image forming apparatus (color printer) PR3 according to a third embodiment of the present invention will be described.

  The main configuration of the image forming apparatus PR3 according to the third embodiment is the same as that of the image forming apparatus PR1 according to the first embodiment or the image forming apparatus PR2 according to the second embodiment. Because of this, redundant explanation is omitted.

  The main part of the image forming apparatus PR3 is shown in the functional block diagram of FIG.

  The temperature control device 500 is configured by a microcomputer or the like, and also serves as a determination unit described later.

  As shown in FIG. 13, the temperature control device 500 includes a table storage unit 501 for storing a table as shown in FIG. 14, a mode selection unit 502 configured by buttons and the like for the user to select each mode described above, and the like. It is connected.

  The temperature adjustment unit 700 controlled by the temperature control device 500 includes a cooling unit 200 and a heating unit 300.

  Although the cooling device 200 is not particularly limited, in the present embodiment, the cooling device 200 includes an electric motor 201 capable of controlling the number of rotations under the control of the temperature control device 500 and a blower fan 202 provided on the rotation shaft thereof. Accordingly, a desired cooling effect is expected by appropriately increasing or decreasing the amount of air sent to the first surface Pa side of the printing paper P.

  In addition to the air cooling method as described above, the cooling device 200 is, for example, a method in which a cooling roll of a heat transfer material cooled by a refrigerant flow or a Peltier element is brought into contact with the first surface Pa of the printing paper P and the like. It is also possible to use.

  Further, when the maximum temperature acquired by the temperature sensor 400 can be lower than a predetermined range of temperatures, the temperature control device 500 sets the temperature of the first surface Pa of the printing paper P after the fixing nip to a predetermined range of temperatures. When the maximum temperature cannot be lowered below a predetermined temperature range, the temperature of the first surface Pa of the printing paper P after the fixing nip is controlled to be equal to or higher than the predetermined temperature range. .

  For example, the maximum temperature of the first surface Pa corresponding to the basis weight (thickness) of the printing paper P and the fixing conditions (temperature, nip time, etc.) A table relating to threshold values (first threshold value, second threshold value) is stored, and cooling control is performed based on the data.

  The temperature in the predetermined range may be a temperature range in which a resin (wax) constituting the toner base material melts.

  As a cooling control method, for example, when it is determined that the acquired maximum temperature of the first surface Pa is equal to or lower than a preset first threshold value, the cooling of the first surface Pa of the printing paper P after the fixing nip is performed. When it is determined that the second threshold value is set to be equal to or greater than a preset second threshold value, control is performed so that the first surface Pa of the printing paper P after the fixing nip is not cooled.

  Here, FIG. 14A shows a configuration example of the table.

  In the example shown in FIG. 14A, modes 1 to 4 that can be selected by the user according to the paper basis weight (g / square meter) and the like are prepared.

  Specifically, in “mode 1”, the paper basis weight is 100 to 150 (g / square meter), the paper back surface (first side Pa) temperature is 105 to 115 ° C., the threshold value is 90 ° C., and the corresponding control operation is “cooling”. None ”.

  In “Mode 2”, the paper basis weight is 150 to 200 (g / square meter), the paper back surface (first side Pa) temperature is 95 to 105 ° C., the threshold value is 90 ° C., and the corresponding control operation is “no cooling”. It has become.

  In “Mode 3”, the paper basis weight is 200 to 250 (g / square meter), the paper back surface (first side Pa) temperature is 85 to 95 ° C., the threshold value is 90 ° C., and the corresponding control operation is “cooling”. ing.

  In “mode 4”, the paper basis weight is 250 to 300 (g / square meter), the paper back surface (first side Pa) temperature is 80 to 90 ° C., the threshold value is 90 ° C., and the corresponding control operation is “cooling”. ing.

  In the example illustrated in FIG. 14, the case where the threshold value is one (that is, the first threshold value and the second threshold value are the same) has been described. You can set a different value for.

  Although not particularly limited, in the present embodiment, the threshold value is the melting point temperature (90 ° C.) of the resin (wax) constituting the toner base material.

  In addition, although the heating device 300 is not particularly limited, in the present embodiment, the heating device 300 is configured by an electric heater 300 that can control supply power by the control of the temperature control device 500. Accordingly, a desired heating effect is expected by appropriately increasing or decreasing the amount of heat applied to the first surface Pa side of the printing paper P.

  In addition to the irradiation method as described above, the heating device 300 includes, for example, a heating method using a warm air fan, a heating roll of a heat transfer material heated by circulation of a heat medium, a Peltier element, or the like on the first surface of the printing paper P. It is also conceivable to use a method of heating by contacting with Pa.

  Further, when the maximum temperature acquired by the temperature sensor 400 can be lower than a predetermined range of temperatures, the temperature control device 500 sets the temperature of the first surface Pa of the printing paper P after the fixing nip to a predetermined temperature range or less. If the maximum temperature cannot be lower than a predetermined range, the temperature of the first surface Pa of the printing paper P after the fixing nip is controlled to be equal to or higher than the predetermined temperature range. .

  For example, the maximum temperature of the first surface Pa corresponding to the basis weight (thickness) of the printing paper P and the fixing conditions (temperature, nip time, etc.) in a table storage means composed of a non-volatile memory such as ROM or flash memory, A table relating to threshold values (third threshold value, fourth threshold value) is stored, and cooling control is performed based on the data.

  The temperature in the predetermined range may be a temperature range in which a resin (wax) constituting the toner base material melts.

  As a heating control method, for example, when it is determined that the acquired maximum temperature of the first surface Pa is equal to or lower than a preset third threshold value, the heating of the first surface Pa of the printing paper P after the fixing nip is performed. In the case where it is determined that the value is equal to or greater than a preset fourth threshold value, control is performed so as not to heat the first surface Pa of the printing paper P after the fixing nip.

  Here, FIG. 14B shows a configuration example of the table.

  In the example shown in FIG. 14B, modes 1 to 4 that can be selected by the user according to the paper basis weight (g / square meter) and the like are prepared.

  Specifically, in “mode 1”, the paper basis weight is 100 to 150 (g / square meter), the paper back surface (first side Pa) temperature is 105 to 115 ° C., the threshold value is 90 ° C., and the corresponding control operation is “heating” None ”.

  In “Mode 2”, the paper basis weight is 150 to 200 (g / square meter), the paper back surface (first side Pa) temperature is 95 to 105 ° C., the threshold value is 90 ° C., and the corresponding control operation is “no heating”. It has become.

  In “Mode 3”, the paper basis weight is 200 to 250 (g / square meter), the paper back surface (first side Pa) temperature is 85 to 95 ° C., the threshold value is 90 ° C., and the corresponding control operation is “heating”. ing.

  In “mode 4”, the paper basis weight is 250 to 300 (g / square meter), the paper back surface (first side Pa) temperature is 80 to 90 ° C., the threshold value is 90 ° C., and the corresponding control operation is “heating”. ing.

  In the example shown in FIG. 14, the case where the threshold value is one (that is, the third threshold value and the fourth threshold value are the same) is shown. However, the present invention is not limited to this. You can set a different value for.

  Although not particularly limited, in the present embodiment, the threshold value is the melting point temperature (90 ° C.) of the resin (wax) constituting the toner base material.

  Here, with reference to the flowcharts of FIGS. 15 and 16, an example of a processing procedure of the cooling process and the heating process executed in the image forming apparatus PR3 will be described.

  15 and 16 show the case of cooling or heating in single-sided printing.

  In the cooling process of FIG. 15, the mode is selected in step S500, and the process proceeds to step S501.

  In step S501, it is determined whether the back surface temperature on the table is higher than the threshold value. If the determination result is “Yes”, the process proceeds to step S502, printing is started, and the process is terminated.

  If the determination result is “No”, the process proceeds to step S503, the cooling of the back surface (first surface) is turned on, then the process proceeds to step S504, printing is started, and the process is terminated.

  In the heat treatment of FIG. 16, the mode is selected in step S550, and the process proceeds to step S551.

  In step S551, it is determined whether the back surface temperature on the table is lower than the threshold value. If the determination result is “Yes”, the process proceeds to step S552, printing is started, and the process ends.

  When the determination result is “No”, the process proceeds to step S553, the heating of the back surface (first surface) is turned on, then the process proceeds to step S554, printing is started, and the process is terminated.

  Thus, cooling control or heating control is performed so that the maximum back surface (first surface) temperature does not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed, and image quality is improved.

  (Fourth embodiment)

  An image forming apparatus (color printer) PR4 according to a fourth embodiment of the present invention will be described with reference to the functional block diagram of FIG.

  Note that the main configuration of the image forming apparatus PR4 according to the fourth embodiment is the same as that of the image forming apparatus PR3 according to the third embodiment, and a redundant description thereof will be omitted.

  The image forming apparatus PR4 is different from the image forming apparatus PR3 in that the table storage unit 501 is not provided.

  In this case, temperature adjustment is performed based on the measured value and threshold value of the temperature sensor 400.

  Here, with reference to the flowcharts of FIGS. 18 and 19, an example of a processing procedure of the cooling process and the heating process executed in the image forming apparatus PR4 will be described.

  18 and 19 show the case of cooling or heating in double-sided printing.

  In the cooling process of FIG. 18, printing of the back surface (first surface) is started in step S600, and the process proceeds to step S601.

  In step S601, it is determined whether or not the back surface temperature measured at the time of printing the first side is higher than the threshold value. If “Yes”, the process proceeds to step S602, and printing of the front side (second side) is started and processed. Exit.

  On the other hand, if “No” is determined in step S601, the process proceeds to step S603, the back surface cooling is turned on, the process proceeds to step S604, printing is started, and the process is terminated.

  In the heat treatment of FIG. 19, printing of the back surface (first surface) is started in step S650, and the process proceeds to step S651.

  In step S651, it is determined whether or not the back surface temperature measured at the time of printing the first side is lower than the threshold value. If “Yes”, the process proceeds to step S652, printing of the front side (second side) is started and processed. Exit.

  On the other hand, if “No” is determined in step S651, the process proceeds to step S653, the back surface heating is turned on, the process proceeds to step S654, printing is started, and the process is terminated.

  Thereby, cooling control or heating control is performed so that the maximum temperatures of the back surface (first surface) and the front surface (second surface) do not fall within the wax melting point range, the occurrence of gloss unevenness is suppressed, and the image quality is improved.

  Although the invention made by the present inventor has been specifically described based on the embodiments, the embodiments disclosed herein are illustrative in all respects and are not limited to the disclosed technology. Should not be considered. That is, the technical scope of the present invention should not be construed restrictively based on the description in the above embodiment, but should be construed according to the description of the scope of claims. All modifications that fall within the scope of the claims and the equivalent technology are included.

  When using a program, it can be provided via a network or stored in a recording medium such as a CD-ROM.

  That is, the predetermined program including the image processing program is not limited to being recorded in a storage device such as a hard disk as a recording medium, and the predetermined program can be provided as follows.

  For example, a predetermined program may be stored in the ROM, and the CPU may load the predetermined program from the ROM to the main storage device and execute it.

  Further, the predetermined program may be stored and distributed in a computer-readable recording medium such as a DVD-ROM, CD-ROM, MO (magneto-optical disk), or flexible disk.

  Further, the image processing apparatus or the like is connected to a server apparatus or a host computer via a communication line (for example, the Internet), and after the predetermined program is downloaded from the server apparatus or the host computer, the predetermined program is executed. You may do it. In this case, examples of the download destination of the predetermined program include a memory such as a RAM and a storage device (recording medium) such as a hard disk.

  The fixing device, gloss processing device, and image forming device according to the present invention can be applied to a copying machine, a laser printer, a full-color printer, a printer, a facsimile machine, and the like.

PR1, PR2 Image forming apparatus P (P1, P2) Printing paper Pa First side Pb Second side 1Y-1K Image forming units 5A, 5B Secondary fixing device (fixing device)
6 Cutting Device 7 Document Reading Device 10 Photosensitive Drum 11 Charging Roll 12 Exposure Unit 13 Developing Device 14 Primary Transfer Roll 15 Photoconductor Cleaning Device 16 Static Removal Roll 17Y-K Toner Tank 20 Intermediate Transfer Belt 21 Secondary Transfer Roll 22 Backup Roll 23 Steering roll 24 Belt cleaning device 30 Paper tray 31A Pickup 32B Roll pair 33 Transport roll pair 35 Registration roll pair 37 Discharge roll pair 38 Discharge roll pair 44 Peeling roll 50 Fixing belt 51 Heating roll 52 Peeling roll 53 Walk control roll 54 Pressure roll 55 Halogen heater 56 Heat sink 56 Cooling heat sink 57 Guide guide 58a Peeling guide guide 59 Conveying roll pair 101, 102 Paper discharge tray 200 Cooling device 201 Electric motor 202 Wind fan 300 heating device 300 the electric heater 400 temperature sensor 500 temperature controller 501 table storage unit 502 mode selector N nip 600 reversing mechanism 700 temperature adjusting unit

Claims (9)

Fixing means for fixing the image on the second surface by inverting the front and back of the recording medium after fixing the image on the first surface of the recording medium;
An acquisition means for acquiring a maximum temperature predicted value of the first surface of the recording medium after the fixing nip by the fixing means;
Based on the predicted maximum temperature value of the first surface of the recording medium acquired by the acquiring means, the temperature so that the maximum temperature of the first surface of the recording medium after the fixing nip by the fixing means does not fall within a predetermined temperature range. Temperature control means for controlling,
A fixing device comprising: Determination means for determining whether or not the maximum temperature can be lower than the temperature range from the predicted maximum temperature value acquired by the acquisition means;
The temperature control means includes
When the determination unit determines that the maximum temperature can be lower than the temperature range, the fixing unit controls the temperature of the first surface of the recording medium after the fixing nip to be equal to or lower than the temperature range;
When the determination unit determines that the maximum temperature cannot be lower than the temperature range, the fixing unit controls the temperature of the first surface of the recording medium after the fixing nip to be equal to or higher than the temperature range. The fixing device according to claim 1. A table storing means for storing a table relating to the temperature of the first surface according to the basis weight and fixing conditions of the recording medium;
The temperature control means includes
Based on the temperature of the first surface of the recording medium stored in the table storage unit, the basis weight, and the fixing condition, the maximum temperature of the first surface of the recording medium after the fixing nip by the fixing unit is the temperature. The fixing device according to claim 1, wherein the temperature is controlled so as not to fall within a range. The temperature control means includes
When it is determined that the maximum temperature of the first surface acquired by the acquisition unit is equal to or lower than a first threshold value set in advance, the first surface of the recording medium after the fixing nip is cooled and set in advance. 4. The cooling device according to claim 1, further comprising a cooling unit that is controlled not to cool the first surface of the recording medium after the fixing nip when it is determined that the second threshold value is exceeded. The fixing device according to any one of the above. The temperature control means includes
When it is determined that the maximum temperature of the first side acquired by the acquisition unit is equal to or lower than a preset third threshold value, the first side of the recording medium after the fixing nip is heated and set in advance. 5. The heating device according to claim 1, further comprising a heating unit that is controlled not to heat the first surface of the recording medium after the fixing nip when it is determined that the fourth threshold value is exceeded. The fixing device according to any one of the above.   At least one of the first threshold value, the second threshold value, the third threshold value, and the fourth threshold value is a melting point temperature of a wax included in a color material used for image formation on the recording medium. The fixing device according to any one of claims 4 and 5.   The fixing device according to claim 6, wherein the temperature range is a temperature range in which wax contained in the color material melts. A fixing device according to any one of claims 1 to 7,
An endless belt that is wound around a plurality of members and rotates;
Belt heating means for heating the belt;
A fixing nip member that press-contacts the recording medium as an object to be glossed against the belt heated by the belt heating unit, and
A gloss processing apparatus comprising at least   An image forming apparatus comprising: the fixing device according to claim 1; or the gloss processing device according to claim 8.

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