Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent the occurrence of trouble in a wireless tag attached to a print medium.SOLUTION: An image forming apparatus has a conveying unit, an image forming unit, a fixing device, and a control unit. The conveying unit conveys a print medium attached with a wireless tag. The image forming unit forms an image on the print medium. The fixing device has a heating unit that heats the print medium, heats the print medium with the heating unit at a heating position of positions on a conveyance path through which the print medium is conveyed, and fixes, on the print medium, the image formed by the image forming unit to the print medium. In the heating of the print medium with the heating unit, the control unit decreases a temperature at which, of areas on the print medium, a second area including the wireless tag is heated compared with a temperature at which, of the areas on the print medium, a first area not including the wireless tag is heated.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] Embodiments of the present invention relate to an image forming apparatus. Place

Background Art

[0002] Conventionally, there is known an image forming apparatus capable of writing tag information to a wireless tag during conveyance of a printed medium with the wireless tag attached thereto.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when an image forming apparatus as described in Patent Document 1 fixes an image on a printed medium by heating the printed medium, the wireless tag attached to the printed medium is heated together with the printed medium. Due to this heating, there was a case where a problem occurred in the wireless tag attached to the printed medium in the image forming apparatus.

[0005] The problem to be solved by the present invention is to provide an image forming apparatus capable of suppressing a problem from occurring in a wireless tag attached to a printed medium. Place

Means for Solving the Problems

[0006] ​​The image forming apparatus of this embodiment comprises a transport unit, an image forming unit, a fixing device, and a control unit. The transport unit transports a printing medium to which a wireless tag is attached. The image forming unit forms an image on the printing medium. The fixing device has a heating unit for heating the printing medium, and heats the printing medium at a heating position on the transport path to which the printing medium is transported, thereby fixing the image formed on the printing medium by the image forming unit to the printing medium. In heating the printing medium by the heating unit, the control unit sets the temperature at which a second region of the printing medium, which includes the wireless tag, is heated to a lower temperature than the temperature at which a first region of the printing medium, which does not include the wireless tag, is heated. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of the configuration of the image forming apparatus 1 of the embodiment. [Figure 2] This figure shows an example of the configuration of a printed medium with a wireless tag attached. [Figure 3] This figure shows an example of the configuration of the fixing device AD. [Figure 4] This figure shows an example of the configuration of the heating element HE that is included in the heating unit HT shown in Figure 3. [Figure 5] This figure shows another example of the configuration of the heating element HE that is included in the heating unit HT shown in Figure 3. [Figure 6] Figure 5 shows another example of the configuration of the heating element HE that is included in the heating unit HT shown in Figure 5. [Figure 7] This figure shows another example of the configuration of the fixing unit AD. [Figure 8] This figure shows an example of the behavior of the two registration rollers 24 when the leading edge of the printing medium coincides with the detection position. [Figure 9] This figure shows another example of the behavior of the two registration rollers 24 when the leading edge of the printing medium coincides with the detection position. [Figure 10] This figure shows an example of the correlation between the location of a wireless tag and the received signal strength. [Figure 11] This diagram illustrates a method for determining the location of a wireless tag based on the distance between antennas. [Figure 12] This figure shows an example of the functional configuration of the control unit 110. [Figure 13] This figure shows an example of the process flow in which the image forming apparatus 1 changes the set temperature of the heating unit HT during the transport of printing media. [Figure 14] This graph shows an example of how the image forming apparatus 1 lowers the set temperature of the heating unit HT from the first temperature to the second temperature when the second region of the printing medium passes through the target section. [Figure 15] This figure compares the maximum temperature of the wireless tag on the printed media stacked on the output tray TB when a temperature reduction process is performed, with the maximum temperature of the wireless tag on the printed media stacked on the output tray TB when no temperature reduction process is performed. [Modes for carrying out the invention]

[0008] An image forming apparatus according to an embodiment will be described with reference to the drawings. In each figure, the same components are denoted by the same reference numerals. As an example of an image forming apparatus according to an embodiment, image forming apparatus 1 will be described as an example.

[0009] (Configuration of an image forming apparatus) Referring to Figure 1, the configuration of the image forming apparatus 1 will be described. Figure 1 is a diagram showing an example of the configuration of the image forming apparatus 1 in this embodiment.

[0010] Image forming apparatus 1 is a device that forms images on a printing medium, such as a multifunction printer, copier, or printer. Image forming apparatus 1 is placed, for example, in a workplace. The printing medium is the medium on which image forming and other processing are performed by image forming apparatus 1. The printing medium can be any sheet-like medium on which an image can be formed on at least one of its sides. For example, printing mediums can be printing paper, plastic film, etc.

[0011] The image forming apparatus 1 identifies the type of print medium that is the target of the process desired by the user according to the operation received from the user. The print medium is classified by the size of the print medium, the thickness of the print medium, the material of the print medium, and the presence or absence of a wireless tag. A print medium with a wireless tag is a print medium to which one or more wireless tags are attached. A print medium without a wireless tag is a print medium to which no wireless tag is attached.

[0012] The wireless tag is, for example, an RFID (Radio Frequency Identification) tag, but is not limited thereto. FIG. 2 is a diagram showing an example of the configuration of a print medium with a wireless tag. The arrow shown in FIG. 2 indicates the conveyance direction in which the print medium is conveyed in the image forming apparatus 1. The print medium PPA shown in FIG. 2 shows an example of a print medium with a wireless tag. The wireless tag TG shown in FIG. 2 shows an example of a wireless tag attached to the print medium PPA. The wireless tag TG has an IC (Integrated Circuit) chip CP and an antenna AT. The IC chip CP is an IC chip for writing / readout of tag information. The antenna AT is an antenna connected to the IC chip CP and performing reception of tag information written to the IC chip CP, transmission of tag information read from the IC chip CP, and the like.

[0013] The image forming apparatus 1 can detect the position of the wireless tag in the conveyance direction on the print medium. Therefore, the image forming apparatus 1 can distinguish the area on the print medium into two types of areas arranged in the conveyance direction, that is, a first area that does not include a wireless tag and a second area that includes a wireless tag. The first area is a rectangular area that does not include a wireless tag. The second area is a rectangular area that includes a wireless tag. For example, the image forming apparatus 1 detects the position of the wireless tag TG in the conveyance direction on the print medium PPA. In this case, based on the detected position, as shown in FIG. 2, the image forming apparatus 1 divides the area on the print medium PPA into a first area RAA that does not include the wireless tag TG, a second area RB that includes the wireless tag TG, and a first area RAB that does not include the wireless tag TG. In the example shown in FIG. 2, the three areas of the first area RAA, the second area RB, and the first area RAB are arranged in the order of the first area RAA, the second area RB, and the first area RAB in the conveyance direction.

[0014] The image forming apparatus 1 forms an image on a specifically specified type of print medium in response to an operation received from the user. For example, when the specifically specified type of print medium received from the user in response to the operation is a print medium having a wireless tag, the image forming apparatus 1 writes tag information to each of one or more wireless tags attached to the print medium. After writing the tag information to the one or more wireless tags, the image forming apparatus 1 forms an image on the print medium to which the one or more wireless tags to which the tag information has been written are attached. After forming the image on the print medium, the image forming apparatus 1 heats the print medium on which the image has been formed to fix the image to the print medium. After fixing the image to the print medium, the image forming apparatus 1 discharges the print medium on which the image has been fixed.

[0015] The wireless tag attached to the print medium is heated together with the print medium during such heating of the print medium. Due to this heating, the wireless tag attached to the print medium may cause problems. Problems that occur in the wireless tag are, for example, problems related to communication between the device that writes / read tag information and the wireless tag, deformation of the print medium due to heat generation of the wireless tag, and the like.

[0016] Therefore, when heating the printing medium, the image forming apparatus 1 sets the temperature at which it heats the second region of the printing medium, which includes the wireless tag, to be lower than the temperature at which it heats the first region of the printing medium, which does not include the wireless tag. For example, when heating the printing medium PPA shown in Figure 2, the image forming apparatus 1 sets the temperature at which it heats the second region RB to be lower than the temperature at which it heats the first region RAA and the first region RAB, respectively. This allows the image forming apparatus 1 to suppress malfunctions in the wireless tag attached to the printing medium.

[0017] The image forming apparatus 1 includes, for example, a printer unit 11, a control panel 12, a wireless tag communication device 13, a manual feed tray TA, and an output tray TB. The image forming apparatus 1 may also be configured to include other components, devices, etc., in addition to the printer unit 11, the control panel 12, the wireless tag communication device 13, the manual feed tray TA, and the output tray TB. The image forming apparatus 1 may also be configured without the wireless tag communication device 13. In this case, the image forming apparatus 1 is connected to the wireless tag communication device 13 from the outside so that it can communicate.

[0018] The printer unit 11 comprises a control unit 110, a paper feed cassette 111, a paper feed cassette 112, and an image forming unit 114.

[0019] The control unit 110 controls the entire image forming apparatus 1. In other words, the control unit 110 controls the printer unit 11, the control panel 12, the wireless tag communication device 13, and the image forming unit 114.

[0020] The paper feed cassette 111 stores the type of printing medium desired by the user. As an example, we will describe a case where the paper feed cassette 111 stores printing medium with a wireless tag attached.

[0021] The paper feed cassette 112 stores the type of printing medium desired by the user. As an example, the case in which the paper feed cassette 112 stores printing medium that does not have a wireless tag will be described.

[0022] The control panel 12 includes an operation reception unit and a display unit.

[0023] The operation reception unit receives operations from the user. The operation reception unit is an input device, such as a touchpad or input keys. The operation reception unit outputs information indicating the operation received from the user to the control unit 110.

[0024] The display unit displays images corresponding to operations received via the operation reception unit. The display unit is an image display device, such as a liquid crystal display or an organic EL (Electro-Luminescence) display. The display unit may also be integrated with the operation reception unit as a touch panel.

[0025] The image forming unit 114, in response to control from the control unit 110, transports the printing medium and forms the image indicated by the image data acquired from the control unit 110 onto the printing medium. For the sake of explanation, the process of forming an image on the printing medium will be referred to as printing. The configuration of the image forming unit 114 will be described later.

[0026] The wireless tag communication device 13 includes an antenna 131 that emits radio waves into a predetermined radiation area RA within the area on the transport path where the printing medium is transported in the image forming apparatus 1.

[0027] Antenna 131 is, for example, a single antenna that radiates radio waves into the radiation region RA. Antenna 131 may be composed of multiple antennas instead of a single antenna.

[0028] The wireless tag communication device 13 radiates radio waves from its antenna 131 toward the radiation area RA in response to control from the control unit 110. This allows the wireless tag communication device 13 to write tag information to one or more wireless tags attached to a printed medium having wireless tags. The method for writing tag information to the wireless tags may be a known method or a method to be developed in the future. Therefore, a description of the method for writing tag information to the wireless tags will be omitted.

[0029] (Configuration of the image forming unit) The configuration of the image forming unit 114 will be described below.

[0030] The image forming unit 114 includes an intermediate transfer belt 20. The image forming unit 114 includes a driven roller 21, a backup roller 22, a secondary transfer roller 23, two registration rollers 24, and a manual feed roller 25. The image forming unit 114 includes four sets of image forming stations: image forming station 31, image forming station 32, image forming station 33, and image forming station 34. The image forming unit 114 includes a fuser AD and a duplex printer DF.

[0031] The intermediate transfer belt 20 is the belt to which the toner image is primarily transferred by four sets of image forming stations. The intermediate transfer belt 20 is supported by driven rollers 21 and backup rollers 22, etc. The intermediate transfer belt 20 rotates in the direction indicated by arrow m in Figure 1. More specifically, the image forming unit 114 rotates the intermediate transfer belt 20 in this direction using a motor (not shown) in response to control from the control unit 110.

[0032] Image forming station 31 is an image forming station for yellow (Y) image formation. Image forming station 32 is an image forming station for magenta (M) image formation. Image forming station 33 is an image forming station for cyan (C) image formation. Image forming station 34 is an image forming station for black (K) image formation. In the image forming unit 114, these four sets of image forming stations are arranged below the intermediate transfer belt 20, along the rotational direction of the intermediate transfer belt 20.

[0033] The image forming station 31 comprises a photoreceptor drum 311, a charging charger 312, an exposure scanning head 313, a developing device 314, a photoreceptor cleaner 315, and a primary transfer roller 316. In the image forming station 31, the charging charger 312, the exposure scanning head 313, the developing device 314, the photoreceptor cleaner 315, and the primary transfer roller 316 are arranged around the photoreceptor drum 311, which rotates in the direction indicated by arrow n in Figure 1. The primary transfer roller 316 faces the photoreceptor drum 311 via an intermediate transfer belt 20.

[0034] The configurations of image forming stations 32, 33, and 34 are the same as those of image forming station 31. Therefore, the configurations of image forming stations 32, 33, and 34 will not be explained below.

[0035] The secondary transfer roller 23 faces the backup roller 22 via the intermediate transfer belt 20. The secondary transfer roller 23 secondarily transfers the toner image, which was first transferred to the intermediate transfer belt 20, to the printing medium that passes between the secondary transfer roller 23 and the intermediate transfer belt 20. The toner image secondarily transferred to the printing medium is an example of an image formed on the printing medium.

[0036] The two registration rollers 24 transport the printing media, which has been taken out from the paper feed cassette 111, paper feed cassette 112, and manual feed tray TA respectively by a transport mechanism (not shown), between the secondary transfer roller 23 and the intermediate transfer belt 20.

[0037] The manual feed roller 25 takes the printing medium from the manual feed tray TA and transports it to the two registration rollers 24.

[0038] The fixing device AD ​​is a device that fixes the toner image onto the printing medium after the toner image has been secondarily transferred by the secondary transfer roller 23. More specifically, the fixing device AD ​​heats the printing medium while transporting it with the roller, thereby fixing the toner image that has been secondarily transferred onto the printing medium to the printing medium.

[0039] The duplex printing device DF is a device that transports the printing medium, after the toner image has been fixed to the surface by the fuser device AD, to two registration rollers 24. The printing medium is transported to the duplex printing device DF after it has been flipped over to its front and back sides. As a result, the printing medium transported between the two registration rollers 24 via the duplex printing device DF has an image formed on its back side via the secondary transfer roller 23 and the fuser device AD.

[0040] (Operation of the image forming unit) The operation of the image forming unit 114 will be described below.

[0041] First, we will explain the operation of the four sets of image forming stations, using the operation of image forming station 31 as an example.

[0042] The image forming station 31 charges the photoreceptor drum 311 with the charger 312, and then exposes it with the exposure scanning head 313. This causes the image forming station 31 to form an electrostatic latent image on the photoreceptor drum 311. The image forming station 31 then causes the electrostatic latent image on the photoreceptor drum 311 to be developed by the developing device 314. The developing device 314 uses a two-component developer formed from toner and carrier to develop the electrostatic latent image on the photoreceptor drum 311 as a toner image. The primary transfer roller 316 then transfers the toner image formed on the photoreceptor drum 311 to the intermediate transfer belt 20. After this primary transfer, the photoreceptor cleaner 315 removes any remaining toner from the photoreceptor drum 311.

[0043] Each of the image forming stations 31, 32, 33, and 34 forms a color toner image on the intermediate transfer belt 20 using a primary transfer roller 316. The color toner image is formed by sequentially layering toner images of Y (yellow), M (magenta), C (cyan), and K (black).

[0044] Next, the operation of the secondary transfer roller 23 will be described. The secondary transfer roller 23 transfers the color toner image on the intermediate transfer belt 20 all at once to the printing medium passing between the secondary transfer roller 23 and the intermediate transfer belt 20. In the following description, the term "toner image" may refer to either a color toner image or a toner image of only one color. The toner image may also be a toner image using decolorized toner.

[0045] Next, we will describe the operation of the image forming unit 114, specifically the operation of transporting the printing medium.

[0046] The nip of the two registration rollers 24 is bent by a transport mechanism (not shown) that allows the printing medium taken from the paper feed cassette 111, paper feed cassette 112, and manual feed tray TA to bend. This aligns the leading edge of the printing medium. Subsequently, the two registration rollers 24 transport the printing medium between the secondary transfer roller 23 and the intermediate transfer belt 20 in accordance with the timing of the image forming unit 114 transferring the toner image to the printing medium. The transport paths from the paper feed cassette 111, paper feed cassette 112, and manual feed tray TA to the two registration rollers 24 converge at the junction PA shown in Figure 1.

[0047] Within the image forming unit 114, three transport paths—transport path LA, transport path LB, and transport path LC—are formed by two registration rollers 24, the fuser unit AD, and multiple rollers within the duplex printing unit DF. Transport path LA is the transport path from the merging section PA to the branching section PB shown in Figure 1. Transport path LB is the transport path that passes through the duplex printing unit DF, and is the transport path from the branching section PB to the merging section PA. Transport path LC is the transport path from the branching section PB to the output tray TB.

[0048] The two registration rollers 24 begin rotating in accordance with the position of the toner image on the rotating intermediate transfer belt 20, moving the printing medium to the position of the secondary transfer roller 23. As a result, the toner image formed on the intermediate transfer belt 20 is secondarily transferred to the printing medium by the secondary transfer roller 23. After the toner image has been secondarily transferred to the printing medium, the secondary transfer roller 23 transports the printing medium along the transport path LA to the fuser AD.

[0049] The fixing device AD ​​fixes the toner image, which has been secondarily transferred from the secondary transfer roller 23 to the printing medium, to the printing medium while it is being transported. Figure 3 shows an example of the configuration of the fixing device AD. The fixing device AD ​​includes, for example, a fixing member ADA, a pressurizing member ADB facing the fixing member ADA, and a heating unit HT. The three-dimensional coordinate system TC is a three-dimensional orthogonal coordinate system that indicates the direction in the figure in which the three-dimensional coordinate system TC is drawn.

[0050] The fixing member ADA is a member having an endless circumferential surface. For example, the fixing member ADA is a belt-shaped member. The fixing member ADA abuts against the outer circumferential surface of the pressurizing member ADB. The fixing member ADA rotates together with the pressurizing member ADB with which it abuts. A heating section HT is provided inside the fixing member ADA. A support member is provided inside the fixing member ADA to rotatably support the fixing member ADA. In Figures 1 and 3, this support member is omitted for simplification of the diagram. The fixing member ADA rotates around a rotation axis parallel to the X-axis of the three-dimensional coordinate system TC shown in Figure 3.

[0051] The pressurizing member ADB is a roller that contacts the outer surface of the fixing member ADA. The motor's driving force is transmitted to the pressurizing member ADB via gears or the like. In other words, the pressurizing member ADB rotates due to the motor's drive. The pressurizing member ADB rotates around an axis of rotation parallel to the X-axis of the three-dimensional coordinate system TC shown in Figure 3.

[0052] The pressurizing member ADB is pressed against the outer surface of the fixing member ADA by a biasing member such as a spring. By being pressed against the fixing member ADA, the pressurizing member ADB forms a nip with the fixing member ADA. In other words, the pressurizing member ADB forms a nip with the fixing member ADA by contacting it. In the fixing device AD, instead of the configuration in which the pressurizing member ADB is pressed against the outer surface of the fixing member ADA by a biasing member, the fixing member ADA may be pressed against the outer surface of the pressurizing member ADB by a biasing member.

[0053] The heating unit HT is a heating device that heats the fixing member ADA. For example, the heating unit HT is a lamp-type heating device and is equipped with a heating element HE. In this case, the heating element HE is in slidable contact with the fixing member ADA. The heating element HE may be configured to be in slidable contact with the fixing member ADA via a protective layer made of glass or the like, or it may be configured to be in direct slidable contact with the fixing member ADA without a protective layer. The heating unit HT generates heat from the heating element HE and heats the fixing member ADA that is in contact with the heating element HE. In the examples shown in Figures 1 and 3, the heating unit HT sets the heating position HP as the position on the transport path where the fixing member ADA and the pressurizing member ADB are in contact, and heats the area to be heated located at the heating position HP on the outer surface of the fixing member ADA. As a result, the heating unit HT can heat the surface of the printing medium passing between the fixing member ADA and the pressurizing member ADB. In Figure 3, for the sake of simplicity, the heating unit HT is shown as a rectangular object.

[0054] Figure 4 shows an example of the configuration of the heating element HE provided in the heating unit HT shown in Figure 3. As shown in Figure 4, the heating element HE is a heating element with a shape that extends in the axial direction of the rotation axis of the fixing member ADA. In the example shown in Figure 4, the heating element HE is composed of three heating elements: heating element HEA, heating element HEB, and heating element HEC. Heating element HEA is a heating element that heats the area near the center in the axial direction of the area to be heated. Heating element HEB is a heating element that heats one of the ends of the area to be heated in the axial direction of the area to be heated. Heating element HEC is a heating element that heats the other end of the area to be heated in the axial direction of the area to be heated. For this reason, in this example, these three heating elements are arranged in the order of heating element HEB, heating element HEA, and heating element HEC in the negative direction of the X axis of the three-dimensional coordinate system TC. As a result, the heating element HE can heat the entire area to be heated. These three heating elements are composed of a resistor such as a silver-palladium alloy and generate heat when energized by the control unit 110. In this example, these three heating elements are mounted on a circuit board on which the wiring is printed. The wiring connection configuration shown in Figure 4 is merely an example, and other connection configurations are also possible. Some or all of these three heating elements may be configured as a single unit. A more detailed configuration of the heating element HE shown in Figure 4 is described, for example, in Japanese Patent Application Publication No. 2021-039193. For this reason, in this embodiment, a further detailed explanation of the configuration of the heating element HE shown in Figure 4 is omitted.

[0055] The heating element HE of the heating section HT may be configured with multiple heating elements arranged in the direction of transport, as shown in Figure 5, instead of the configuration shown in Figure 4. Figure 5 is a diagram showing another example of the configuration of the heating element HE provided in the heating section HT shown in Figure 3. In the example shown in Figure 5, the heating element HE is composed of four heating elements: heating element HED, heating element HEE, heating element HEF, and heating element HEG. Heating element HED is a heating element that heats the entire area to be heated. Heating element HEE is a heating element that heats an area of ​​the area to be heated that is narrower than the area heated by heating element HED, and wider than the area heated by heating element HEF. Heating element HEF is a heating element that heats an area of ​​the area to be heated that is narrower than the area heated by heating element HEE, and is located near the center of the area in the axial direction of the area to be heated. Heating element HEG is a heating element that heats the entire area to be heated. In this example, the four heating elements are arranged in the order of heating element HEG, heating element HEF, heating element HEE, and heating element HED in the positive direction of the Z axis of the three-dimensional coordinate system TC, i.e., in the transport direction. This arrangement allows heating element HE to heat the entire area to be heated. These four heating elements are made of a resistor such as a silver-palladium alloy and generate heat when energized by the control unit 110. In this example, these four heating elements are provided on a circuit board on which wiring is printed. The wiring connection configuration shown in Figure 5 is merely an example, and other connection configurations are also possible. Some or all of these four heating elements may be configured as a single unit. A more detailed configuration of heating element HE shown in Figure 5 is described, for example, in Japanese Patent Application Publication No. 2021-162757. For this reason, in this embodiment, a further detailed explanation of the configuration of heating element HE shown in Figure 5 is omitted.

[0056] The heating element HE, which is composed of multiple heating elements arranged in the transport direction as shown in Figure 5, may also be composed of three heating elements as shown in Figure 6. Figure 6 is a diagram showing another example of the configuration of the heating element HE provided in the heating section HT shown in Figure 5. In the example shown in Figure 6, the heating element HE is composed of three heating elements: heating element HEH, heating element HEI, and heating element HEJ. These three heating elements are heating elements that have a shape in which their thickness changes in the direction in which they extend. In the example shown in Figure 6, when viewed in the negative direction of the Y axis of the three-dimensional coordinate system TC, the portion of heating element HEI near the center in the axial direction of the rotation axis of the fixing member ADA has a convex lens-like shape, which is wider than both ends of heating element HEI. In this case, heating element HEH has a concave lens-like shape in which the portion of heating element HEH near the center in the axial direction is recessed compared to both ends of heating element HEH, so as to fit with heating element HEI. In this case, the heating element HEJ has a concave lens-like shape, with the portion of the heating element HEJ near the center in the axial direction being recessed compared to both ends of the heating element HEJ, so as to fit with the heating element HEI. All three heating elements are heating elements that heat the entire area to be heated. In this example, the three heating elements are arranged in the order of heating element HEJ, heating element HEI, and heating element HEH in the positive direction of the Z axis of the three-dimensional coordinate system TC, i.e., in the transport direction. This also allows heating element HE to heat the entire area to be heated. These three heating elements are made of a resistor such as a silver-palladium alloy and generate heat when energized by the control unit 110. In this example, these three heating elements are provided on a circuit board on which wiring is printed. The wiring connection configuration shown in Figure 6 is merely an example, and other connection configurations are also possible. Some or all of these three heating elements may be configured as a single unit. A more detailed description of the heating element HE shown in Figure 6 is found in, for example, Japanese Patent Publication No. 2019-144451. Therefore, in this embodiment, further detailed explanation of the heating element HE shown in Figure 6 is omitted.

[0057] The lamp-type heating element HT, as shown in Figures 4 to 6, may be configured to be located inside the pressurizing element ADB instead of being located inside the fixing element ADA.

[0058] The heating section HT may be an induction heating (IH) type heating device as shown in Figure 7, instead of a lamp type heating device as shown in Figures 4 to 6. Figure 7 shows another example of the configuration of the fixing device AD. The heating section HT of the fixing device AD ​​shown in Figure 7 is an IH type heating device and comprises a ferrite core FC, an IH coil CL provided on the ferrite core FC, and a heating element MG that generates heat by the magnetic flux generated from the IH coil CL.

[0059] The ferrite core FC is positioned outside the fixing member ADA so that the magnetic flux generated from the IH coil CL is concentrated on the fixing member ADA. In the example shown in Figure 7, the ferrite core FC is curved along the outer surface of the fixing member ADA and is positioned opposite the position where the pressurizing member ADB is located.

[0060] The IH coil CL is provided on the inner circumferential surface of the ferrite core FC and is a coil that generates a magnetic flux corresponding to the alternating current supplied from the control unit 110. The inner circumferential surface of the ferrite core FC is the surface of the ferrite core FC that faces the outer circumferential surface of the fixing member ADA. In other words, the inner circumferential surface of the ferrite core FC is the surface of the ferrite core FC that faces the fixing member ADA. The IH coil CL heats the heating element MG provided inside the fixing member ADA with the magnetic flux it generates.

[0061] The heating element MG can be any object that generates heat due to the magnetic flux generated by the IH coil CL, for example, an object made of nickel-ferrite alloy, but is not limited to this. The heating element MG is curved along the inner circumferential surface of the fixing member ADA, extends in the axial direction of the rotation axis of the fixing member ADA, and is in slidable contact with the fixing member ADA inside the fixing member ADA. As a result, the heating element MG can heat the region on the outer circumferential surface of the rotating fixing member ADA that is located approximately opposite the heating position HP. Consequently, the heating element MG can heat the surface of the printing medium by the region that moves towards the heating position HP as the fixing member ADA rotates. The heating element MG may be in contact with the fixing member ADA via the aforementioned protective layer, or it may be in contact with the fixing member ADA without the protective layer. The heating element MG is supported inside the fixing member ADA by a support member (not shown).

[0062] A more detailed description of the fixing device AD ​​shown in Figure 7 is found in, for example, Japanese Patent Publication No. 2019-124716. Therefore, in this embodiment, no further detailed explanation of the heating element HE shown in Figure 7 is provided.

[0063] Furthermore, the configurations of the heating unit HT and the fixing device AD ​​may be any other configurations, as long as they do not impair the function of the fixing device AD ​​as described in this embodiment.

[0064] With the above configuration, the fuser unit AD has a heating unit HT that heats the printing medium. At the heating position HP on the transport path where the printing medium is transported, the heating unit HT heats the printing medium and fixes the toner image to the printing medium. As a result, the toner image that was secondarily transferred by the secondary transfer roller 23 is formed as an image on the printing medium. After the image is formed on the printing medium, the fuser unit AD transports the printing medium to the transport path LC. The printing medium transported to the transport path LC is then discharged by a roller (not shown).

[0065] In the case of double-sided printing, after the image is formed on the front surface and the entire printing medium passes through the branching section PB, a roller (not shown) transports the printing medium to the transport path LB via a switchback. This reverses the front and back surfaces of the printing medium. Subsequently, multiple rollers within the double-sided printing device DF transport the printing medium along the transport path LB to the nips of two registration rollers 24. The printing medium, with its front and back surfaces reversed, is then transported along the transport path LA via the two registration rollers 24, where the toner image is fixed by the fuser unit AD. As a result, an image is formed on the back surface of the printing medium. The fuser unit AD then transports the printing medium with the image formed on the back surface to the transport path LC and discharges it.

[0066] Thus, the secondary transfer roller 23, the two resist rollers 24, the fixing device AD, and the various rollers in the duplex printing device DF constitute a transport section for transporting the printing medium in the image forming apparatus 1.

[0067] (Detection of the position of wireless tags on the printed material in the transport direction) As described above, the image forming apparatus 1, when heating the printing medium with the heating unit HT, sets the temperature at which the second region of the printing medium, which includes the wireless tag, is heated to a lower temperature than the temperature at which the first region of the printing medium, which does not include the wireless tag, is heated. For this reason, the image forming apparatus 1 detects the position of the wireless tag on the printing medium in the transport direction and identifies at least the second region of the first and second regions, as will be explained below. The method for detecting the position of the wireless tag on the printing medium in the transport direction will be described below. For convenience of explanation, the position of the wireless tag on the printing medium in the transport direction will be simply referred to as the position of the wireless tag.

[0068] The image forming apparatus 1 detects wireless tag position information indicating the position of the wireless tag at a detection position on the transport path where the printing medium is transported, which is before the heating position HP.

[0069] The detection position is a position on the transport path where the printing medium is transported, where the leading edges of the printing medium can coincide while being held between the two registration rollers 24. The detection position is a predetermined distance from the nip of the two registration rollers 24 in the transport direction. This predetermined distance is, for example, a few centimeters, but is not limited to this. However, this predetermined distance is determined so that the wireless tag attached to the printing medium is not held between the two registration rollers 24. For this reason, this predetermined distance may have different configurations depending on the type of printing medium. As an example, the case where the detection position is a position included in the aforementioned radiation region RA will be described. The detection position may be a position where it is impossible for the leading edges of the printing medium to coincide while being held between the two registration rollers 24. The detection position may also be a position not included in the radiation region RA.

[0070] When the image forming apparatus 1 moves the printing medium from the nip of the two registration rollers 24 to the position of the secondary transfer roller 23 using the two registration rollers 24, it aligns the leading edge of the printing medium with the detection position before moving it to that position. After aligning the leading edge of the printing medium with the detection position, the image forming apparatus 1 stops the movement of the printing medium by the two registration rollers 24 until a predetermined detection time has elapsed. The detection time may be any time as long as it is longer than or equal to the time required for the image forming apparatus 1 to detect the wireless tag position information. After stopping the movement of the printing medium by the two registration rollers 24, the image forming apparatus 1 detects the wireless tag position information until the detection time has elapsed. If it then determines that the detection time has elapsed, the image forming apparatus 1 resumes the movement of the printing medium by the two registration rollers 24 and moves the printing medium to the position of the secondary transfer roller 23 using the two registration rollers 24.

[0071] When the leading edge of the printing medium coincides with the detection position, the wireless tag attached to the printing medium is positioned either closer to the secondary transfer roller 23 than the two registration rollers 24, or further away from the secondary transfer roller 23 than the two registration rollers 24, on the transport path. Figure 8 shows an example of the arrangement of the two registration rollers 24 when the leading edge of the printing medium PPB coincides with the detection position. The printing medium PPB is an example of a printing medium to which a wireless tag has been attached. Figure 8 shows the printing medium PPB sandwiched between the two registration rollers 24, and the antenna 131 of the wireless tag communication device 13 along with the two registration rollers 24. The printing medium PPB has a wireless tag TGB, which is an example of a wireless tag, attached to it. In the example shown in Figure 8, the wireless tag TGB is positioned closer to the secondary transfer roller 23 than the two registration rollers 24. On the other hand, Figure 9 shows another example of the arrangement of the two registration rollers 24 when the leading edge of the printing medium PPC coincides with the detection position. The printing medium PPC is an example of a printing medium to which a wireless tag has been attached. Figure 9 shows a printing medium PPC sandwiched between two registration rollers 24, and the antenna 131 of the wireless tag communication device 13 along with the two registration rollers 24. In the example shown in Figure 9, the distance from the nip of the two registration rollers 24 to the detection position shown in Figure 8 is the same distance from the nip of the two registration rollers 24 to the detection position shown in Figure 9. The printing medium PPC is fitted with a wireless tag TGC, which is an example of a wireless tag. In the example shown in Figure 9, the wireless tag TGC is located further from the secondary transfer roller 23 than from the two registration rollers 24.

[0072] The wireless tag location information can be any information that indicates the location of the wireless tag. For example, if the image forming apparatus 1 is equipped with a sensor that detects the location of the wireless tag, the image forming apparatus 1 detects the wireless tag location information by acquiring the information indicating the result detected by the sensor as the wireless tag location information. For example, if the image forming apparatus 1 is equipped with a sensor that detects other information indicating the location of the wireless tag, the image forming apparatus 1 detects the wireless tag location information by acquiring the other information detected by the sensor as the wireless tag location information. The image forming apparatus 1 can use the received signal strength indicator (RSSI) of the wireless tag as such other information. As an example, the case where the wireless tag location information is the received signal strength of the wireless tag will be described.

[0073] The received signal strength correlates with the distance from antenna 131 to the wireless tag. Specifically, as shown in Figure 10, the received signal strength decreases monotonically as the distance increases. Therefore, the received signal strength can be treated as an alternative indicator of the distance. For the sake of explanation, this distance will be referred to as the distance between antennas. Figure 10 shows an example of the correlation between the position of the wireless tag and the received signal strength.

[0074] When the image forming apparatus 1 detects a received signal strength, it can calculate the distance between antennas based on pre-stored correspondence information and the received signal strength. The correspondence information is information that associates the position of a wireless tag with the received signal strength. The correspondence information may be in the form of a table that associates the position of a wireless tag with the received signal strength, or it may be in the form of other information that associates the position of a wireless tag with the received signal strength.

[0075] The image forming apparatus 1 can determine the position of the wireless tag based on the calculated distance between antennas. Figure 11 is a diagram illustrating the method for determining the position of the wireless tag based on the distance between antennas. The printed medium PPD shown in Figure 11 is an example of a printed medium to which a wireless tag is attached. In the example shown in Figure 11, the leading edge of the printed medium PPD is located at the detection position. For example, if the wireless tag attached to the printed medium PPD is the wireless tag TGC shown in Figure 11, the distance between the wireless tag TGC and antenna 131 is the distance X shown in Figure 11. The wireless tag TGC is an example of a wireless tag attached to a printed medium PPD. On the other hand, for example, if the wireless tag attached to the printed medium PPD is the wireless tag TGD shown in Figure 11, the distance between the wireless tag TGD and antenna 131 is the distance Y shown in Figure 11. The wireless tag TGD is an example of a wireless tag attached to a printed medium PPD.

[0076] The distance β shown in Figure 11 represents the length of a hypothetical perpendicular line drawn from antenna 131 to the transport path. The distance α shown in Figure 11 represents the distance between the intersection of the perpendicular line and the transport path and the detection position. Distances α and β are predetermined values ​​and known values ​​from the design stage of the image forming apparatus 1. Therefore, the image forming apparatus 1 can, for example, determine the distance x from the detection position as the position of the wireless tag if the wireless tag attached to the print medium PPD is a wireless tag TGC, by using the Pythagorean theorem. Specifically, the image forming apparatus 1 can determine the distance x as the position of the wireless tag based on the following equation (1).

[0077] x = -α + √(X 2 -β 2 ) ···(1)

[0078] Similarly, if the wireless tag attached to the print medium PPD is a wireless tag TGD, the image forming apparatus 1 can use the Pythagorean theorem to determine the distance y from the detection position as the position of the wireless tag. Specifically, the image forming apparatus 1 can determine the distance y as the position of the wireless tag based on the following equation (2).

[0079] y = -α + √(Y 2 -β 2 ) ···(2)

[0080] As described above, the image forming apparatus 1 can determine the location of the wireless tag using the received signal strength as wireless tag location information. As a result, the image forming apparatus 1 can determine at least the second region out of the first region and the second region.

[0081] In the image forming apparatus 1, when the leading edge of the printing medium coincides with the detection position, part or all of the printing medium may be included inside the radiation region RA, or it may not be included inside the radiation region RA. In the example shown in Figure 1, in this case, the entire printing medium is included inside the radiation region RA.

[0082] (Functional configuration of the control unit) Next, the functional configuration of the control unit 110 will be described with reference to Figure 12. Figure 12 is a diagram showing an example of the functional configuration of the control unit 110.

[0083] As shown in Figure 12, the control unit 110 is connected to the printer unit 11, the control panel 12, and the wireless tag communication device 13 in a communicative manner. The control unit 110 includes an arithmetic unit 1101, a storage device 1102, a data receiving unit 1103, and an image data decompression unit 1104.

[0084] The arithmetic unit 1101 is, for example, a CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit). The arithmetic unit 1101 controls the printer unit 11, the control panel 12, and the wireless tag communication device 13 according to the image processing program stored in the storage device 1102. The control unit 110 outputs, for example, transport start information indicating that the transport of the printing medium has started.

[0085] The storage device 1102 may be a ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), etc. The storage device 1102 may be separate from the control unit 110. The storage device 1102 is an example of a storage unit.

[0086] The data receiving unit 1103 receives print data (for example, data written in a page description language) indicating the image to be printed from a host such as a PC (Personal Computer), and stores the received print data in the storage device 1102.

[0087] The image data expansion unit 1104 determines printing conditions from the print data stored in the storage device 1102 by the data receiving unit 1103, expands it into printable data (for example, raster data) for the printer unit 11, and stores it in the storage device 1102.

[0088] (A process in which the image forming apparatus changes the set temperature of the heating section during the transport of printing media.) Referring to Figure 13, the process by which the image forming apparatus 1 changes the set temperature of the heating unit HT during the transport of printing media will be described. Figure 13 is a diagram showing an example of the flow of the process by which the image forming apparatus 1 changes the set temperature of the heating unit HT during the transport of printing media. The image forming apparatus 1 performs the process shown in the flowchart in Figure 13 each time it prints on an individual printing medium. In the flowchart shown in Figure 13, the process of forming an image on the printing medium is omitted in order to clarify the flow of the process. As an example, the case in which the image forming apparatus 1 receives a print job instructing printing on a printing medium stored in the paper feed cassette 111 at a timing before the process of ACT 110 shown in Figure 13 is performed will be described. In this embodiment, the printing medium is a printing medium to which a wireless tag is attached, as described above. As an example, the case in which there is one wireless tag attached to the printing medium will be described. The number of wireless tags attached to the printing medium may be two or more.

[0089] After receiving a print job, the control unit 110 controls the rollers located upstream of the two registration rollers 24 among the rollers positioned on the transport path, and transports the printing medium to the nip of the two registration rollers 24 until the printing medium flexes at that nip (ACT110). In the example shown in Figure 13, the process of ACT110 is indicated by "transport to the nip".

[0090] Next, the control unit 110 controls the two registration rollers 24 to move the printing medium until the leading edge of the printing medium, which was bent in ACT110, coincides with the detection position (ACT120). In the example shown in Figure 13, the process of ACT120 is indicated by "move to detection position".

[0091] Next, the control unit 110 stops the rotation of the two registration rollers 24 and stops the movement of the printing medium by the two registration rollers 24 until the aforementioned detection time has elapsed (ACT130). In the example shown in Figure 13, the process of ACT130 is indicated by "conveyor stop".

[0092] Next, the control unit 110 controls the wireless tag communication device 13 and detects the received signal strength as wireless tag location information. The method by which the wireless tag communication device 13 detects the received signal strength may be a known method or a method to be developed in the future. After detecting the wireless tag location information, the control unit 110 detects the position of the wireless tag based on the received signal strength detected as wireless tag location information using the method described above (ACT 140). After detecting the position of the wireless tag, the control unit 110 identifies at least the second region of the first region and the second region based on the detected position of the wireless tag. If two or more wireless tags are attached to the printing medium, the control unit 110 identifies each of the two or more second regions based on the positions of the two or more detected wireless tags. After detecting the position of the wireless tag, the control unit 110 waits until the elapsed time since the movement of the printing medium was stopped in ACT 130 exceeds the detection time.

[0093] Next, the control unit 110 calculates the first and second timings described below (ACT150) based on the received signal strength detected as wireless tag position information in ACT140. In the example shown in Figure 13, the processing of ACT150 is shown as "timing calculation". The first timing is the timing when the wireless tag attached to the printing medium enters the target section when the transport of the printing medium is resumed. In the image forming apparatus 1, the first timing is indicated, for example, by the elapsed time from when the transport of the printing medium is resumed until the wireless tag enters the target section. In the image forming apparatus 1, the first timing may be indicated by other information indicating the timing instead of the elapsed time. The second timing is the timing when the wireless tag attached to the printing medium leaves the target section. In the image forming apparatus 1, the second timing is indicated, for example, by the elapsed time from when the transport of the printing medium is resumed until the wireless tag leaves the target section. In the image forming apparatus 1, the second timing may be indicated by other information indicating the timing instead of the elapsed time. The target section is the section on the transport path between the aforementioned heating position and a position one distance before the heating position. As described later, the image forming apparatus 1 sets the heating unit HT to a predetermined first temperature during the period when the first region of the printing medium passes through the target section. On the other hand, as described later, the image forming apparatus 1 sets the heating unit HT to a second temperature lower than the first temperature during the period when the second region of the printing medium passes through the target section. The first temperature is a temperature within a temperature range in which it is estimated that there will be no problems with the fixing of the toner image to the printing medium and no malfunctions will occur in the IC chip contained in the wireless tag. This temperature range is, for example, 120 to 135°C. This temperature range varies depending on the combination of the type of printing medium and the type of toner. Therefore, 120 to 135°C is merely one example of this temperature range. When the temperature range is 120 to 135°C, the first temperature is, for example, the maximum temperature in that temperature range, which is 135°C. In this case, the second temperature is, for example, 125°C, which is 10°C lower than the first temperature.The first temperature may be lower than the maximum temperature within the given temperature range, as long as it is higher than the second temperature within that range. However, a higher first temperature is preferable within that temperature range. The second temperature may be any temperature lower than the first temperature within that temperature range. However, a lower second temperature is preferable within that temperature range.

[0094] The first distance is a predetermined distance depending on the structure of the fixing device AD. Specifically, the first distance is the length of the portion of the outer circumference of the fixing member ADA that is not in contact with the heating element HE of the heating section HT, when the fixing member ADA is not rotating and is viewed in the axial direction of the rotation axis of the fixing member ADA. For convenience of explanation, this portion will be referred to as the unheated portion, and the portion of the outer circumference of the fixing member ADA that is in contact with the heating element HE of the heating section HT will be referred to as the heated portion. For example, if the fixing device AD ​​has a ramp type configuration as shown in Figures 4 to 6, the heated portion is only the portion of the outer circumference of the fixing member ADA located at the heating position HP. In this case, the length of the unheated portion approximately matches the circumference of a circle with the same radius as the rotation radius of the fixing member ADA when viewed in the axial direction. Therefore, the first distance in this case is the circumference of that circle. For example, if the radius of the fixing member ADA is 15 mm in this case, the first distance is approximately 94.25 mm. On the other hand, if the fixing device AD ​​has an IH (induction heating) configuration as shown in Figure 7, the heated portion is approximately half the circumference of the fixing member ADA when viewed in the axial direction. Therefore, in this case, the length of the unheated portion is approximately equal to half the circumference of a circle having the same radius as the rotation radius of the fixing member ADA when viewed in the axial direction. Consequently, the first distance in this case is half the circumference of that circle. For example, if the radius of the fixing member ADA is 15 mm in this case, the first distance is approximately 47.13 mm.

[0095] The control unit 110 calculates the first timing and the second timing, respectively, based on the transport speed of the printing medium set in advance according to the accepted print job and the position of the wireless tag detected by the ACT 140. Specifically, the control unit 110 calculates the distance between the position of the upstream end of the transport path among the ends of the target section and the position of the wireless tag, and calculates the first timing based on the calculated distance and the transport speed. On the other hand, the control unit 110 calculates the distance between the position of the downstream end of the transport path among the ends of the target section, i.e., the heating position and the position of the wireless tag, and calculates the second timing based on the calculated distance and the transport speed. If multiple wireless tags are attached to the printing medium, the control unit 110 calculates the first timing and the second timing, respectively, for each of the two or more second regions.

[0096] After the processing of ACT150 is completed, the control unit 110 sets the set temperature of the heating unit HT to the first temperature (ACT160).

[0097] Next, the control unit 110 controls the transport unit and restarts the transport of the printing medium (ACT170).

[0098] Next, the control unit 110 waits until the elapsed time from the restart timing in ACT170 matches the first timing calculated in ACT150 (ACT180). In the example shown in Figure 13, the process of ACT180 is indicated by "First Timing?".

[0099] If the control unit 110 determines that the elapsed time matches the first timing (ACT180-YES), it resets the set temperature of the heating unit HT from the first temperature to the second temperature (ACT190). In the example shown in Figure 13, the process of ACT190 is indicated by "set to second temperature".

[0100] Next, the control unit 110 waits until the elapsed time from the restart timing in ACT170 matches the second timing calculated in ACT150 (ACT200). In the example shown in Figure 13, the processing in ACT200 is indicated by "Second Timing?".

[0101] If the control unit 110 determines that the elapsed time matches the second timing (ACT200-YES), it resets the set temperature of the heating unit HT from the second temperature to the first temperature (ACT210). In the example shown in Figure 13, the process of ACT210 is indicated by "set to the first temperature".

[0102] Next, the control unit 110 waits until printing to the printing medium is finished (ACT220). The method by which the control unit 110 determines whether or not printing to the printing medium is finished may be a known method or a method to be developed in the future.

[0103] When the control unit 110 determines that printing to the printing medium is complete (ACT220-YES), it terminates the process shown in the flowchart in Figure 13.

[0104] As described above, when the image forming apparatus 1 heats the printing medium with the heating unit HT, the temperature at which the second region of the printing medium, which includes the wireless tag, is heated is lower than the temperature at which the first region of the printing medium, which does not include the wireless tag, is heated. Figure 14 is a graph showing an example of how the image forming apparatus 1 lowers the set temperature of the heating unit HT from the first temperature to the second temperature when the second region of the printing medium passes through the target section. The vertical axis of the graph in Figure 14 represents the set temperature of the heating unit HT. The horizontal axis of the graph represents the position of the wireless tag on the transport path with the heating position as the origin. As shown in Figure 14, the image forming apparatus 1 lowers the set temperature of the heating unit HT from the first temperature to the second temperature when the position of the wireless tag is included within the target section. This allows the image forming apparatus 1 to suppress malfunctions in the wireless tag attached to the printing medium.

[0105] If two or more wireless tags are attached to the printing medium, the image forming apparatus 1, for example, lowers the set temperature of the heating unit HT from the first temperature to the second temperature for each of the two or more second regions. This allows the image forming apparatus 1 to suppress malfunctions of the wireless tags attached to the printing medium, even in such cases.

[0106] Figure 15 compares the maximum temperature of the wireless tag on the printed media loaded on the output tray TB when a temperature reduction process is performed, with the maximum temperature of the wireless tag on the printed media loaded on the output tray TB when no temperature reduction process is performed. The temperature reduction process is the process shown in the flowchart in Figure 13. When no temperature reduction process is performed, the image forming apparatus 1 transports the printed media while maintaining the set temperature of the heating unit HT at the first temperature.

[0107] The vertical axis of the graph shown in Figure 15 represents the maximum temperature of the IC chip of the wireless tag attached to the printing medium immediately after 300 sheets of printing medium are stacked on the output tray TB. In the example shown in Figure 15, the maximum temperature was 60.2°C when no temperature reduction treatment was performed. On the other hand, in the same example, the maximum temperature was 54.1°C when temperature reduction treatment was performed. In other words, the image forming apparatus 1 can reduce the maximum temperature of the IC chip of the wireless tag attached to the printing medium by performing temperature reduction treatment. As a result, the image forming apparatus 1 can suppress the occurrence of malfunctions in the wireless tags attached to the printing medium.

[0108] In the image forming apparatus 1 described above, the control unit 110 may receive wireless tag position information through user operation. In this case, the wireless tag position information includes information indicating whether the surface of the printing medium to which the wireless tag is attached is the front or back surface. In the image forming apparatus 1 described above, the control unit 110 may be configured to identify wireless tag location information according to the type of printing medium received. In this case, the image forming apparatus 1 has information stored in advance that associates the type of printing medium with the wireless tag location information. In the example described above, the location of the wireless tag may be interpreted as the location of the IC chip contained within the wireless tag.

[0109] As described above, the image forming apparatus comprises a transport unit, an image forming unit, a fixing unit, and a control unit. The transport unit transports a printing medium to which a wireless tag is attached. The image forming unit forms an image on the printing medium. The fixing unit has a heating unit for heating the printing medium, and heats the printing medium at a heating position on the transport path where the printing medium is transported, fixing the image formed on the printing medium by the image forming unit to the printing medium. In heating the printing medium with the heating unit, the control unit sets the temperature at which the second region of the printing medium, which includes the wireless tag, is heated to a lower temperature than the temperature at which the first region of the printing medium, which does not include the wireless tag, is heated.

[0110] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0111] A program for realizing the function of any component in the apparatus described above (for example, the image forming apparatus 1) may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Here, "computer system" includes hardware such as the OS (Operating System) and peripheral devices. "Computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, CD (Compact Disk)-ROMs, and storage devices such as hard disks built into a computer system. "Computer-readable recording medium" also includes volatile memory (RAM) inside a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which holds the program for a certain period of time.

[0112] The above program may be transmitted from a computer system that stores this program in a memory device or the like to another computer system via a transmission medium, or by transmission waves within the transmission medium. The "transmission medium" for transmitting the program refers to a medium that has the function of transmitting information, such as a network (communication network) like the Internet or a communication line (communication line) like a telephone line. The above program may be intended to implement some of the functions described above. The above program may also be a so-called differential file (differential program) that can implement the functions described above in combination with a program already recorded in the computer system. [Explanation of Symbols]

[0113] 1…Image forming apparatus, 11…Printer unit, 12…Control panel, 13…Wireless tag communication device, 20…Intermediate transfer belt, 21…Driven roller, 22…Backup roller, 23…Secondary transfer roller, 24…Registration roller, 25…Paper feed roller, 31, 32, 33, 34…Image forming station, 110…Control unit, 111…Paper feed cassette, 112…Paper feed cassette, 114…Image forming unit, 131, AT…Antenna, 311…Photoreceptor drum, 312…Charging charger, 313…Exposure scanning head, 314…Developing device, 315…Photosensitive Body cleaner, 316... Primary transfer roller, 1101... Processing unit, 1102... Memory device, 1103... Data receiving unit, 1104... Image data development unit, AD... Fixing device, ADA... Fixing member, ADB... Pressurizing member, CL... IH coil, CP... IC chip, DF... Duplex printing device, FC... Ferrite core, HE, HEA, HEB, HEC, HED, HEE, HEF, HEG, HEH, HEI, HEJ... Heating element, HT... Heating unit, MG... Heating element, TA... Tray, TB... Output tray, TC... Three-dimensional coordinate system, TG, TGB, TGC, TGD... Wireless tag

Claims

1. A transport unit that transports printed materials with wireless tags attached, An image forming unit that forms an image on the printing medium, A fixing device having a heating unit for heating the printing medium, which heats the printing medium at a heating position on the transport path where the printing medium is transported, and which fixes the image formed on the printing medium by the image forming unit to the printing medium, In heating the printing medium by the heating unit, the control unit lowers the temperature at which the second region of the printing medium, which includes the wireless tag, is heated to a lower temperature than the temperature at which the first region of the printing medium, which does not include the wireless tag, is heated. Equipped with, The control unit lowers the heating temperature of the second region to the heating temperature of the first region based on the wireless tag position information detected by the detection unit, which detects the position of the wireless tag on the printing medium in the transport direction of the printing medium at a detection position on the transport path of the printing medium that is before the heating position. Image forming apparatus, wherein the control unit, in heating the printing medium with the heating unit, sets the temperature of the heating unit to a first temperature during the period when the first region passes through a target section on the transport path between the heating position and a position a first distance before the heating position, and sets the temperature of the heating unit to a second temperature lower than the first temperature during the period when the second region passes through the target section.

2. The control unit calculates a first timing for the wireless tag to enter the target section and a second timing for the wireless tag to leave the target section based on the wireless tag position information detected by the detection unit, and sets the temperature of the heating unit to a second temperature lower than the first temperature during the period in which the second region passes through the target section, according to the calculated first and second timings. The image forming apparatus according to claim 1.

3. The wireless tag location information is the received signal strength of the wireless tag. The control unit lowers the heating temperature of the second region to the heating temperature of the first region based on correspondence information which associates the position of the wireless tag on the printing medium in the transport direction of the printing medium with the received signal strength, and the wireless tag position information detected by the detection unit. The image forming apparatus according to claim 1 or 2.

Images