Fixation device and image formation system

Abstract

To provide a fixation device that can suppressing deterioration of image quality caused by vibration when a heating member contacts a compression member in accordance with the kind of recording media and required image quality, compared with when a load on a point of contact where a heating member and a compression member come to contact with each other is always constant, or that can secure fixability of a toner image onto a recording medium and high glossiness.SOLUTION: A fixation device 100 comprises: a heating roll 130 for heating a toner image on a surface of a sheet P; a compression roll 140 which has a recess part 148 which is entered by a gripper 76 holding the front end side of the sheet P on the outer peripheral surface thereof and which compresses the sheet P between itself and the heating roll 130; a movement unit 220 for moving the heating roll 130 relatively between a position where the heating roll 130 makes contact with the outer peripheral surface of the compression roll 140 and a position where the heating roll 130 separates from the outer peripheral surface of the compression roll 140 when the recess part 148 passes; and a second cam 234 for, depending on the kind of the sheet P or selection of a user, switching a magnitude of a load on a contact part where the heating roll 130 makes contact with the outer peripheral surface of the compression roll 140.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a fixing device and an image forming system. [Background technology]

[0002] The following Patent Document 1 discloses an image forming apparatus having a heating rotor and a pressure rotor that sandwich and transport a recording material in a nip portion between them to heat a toner image on the recording material, a pressure mechanism for pressing at least one of the heating rotor and the pressure rotor toward the other, a pressure force switching mechanism that switches the pressure applied to the nip portion by the pressure mechanism, a temperature control temperature switching unit that switches the controlled temperature of the heating rotor, a transport speed switching unit that switches the transport speed of the recording material through the nip portion, a display unit that displays information, a setting unit that is displayed on the display unit and allows an operator to set a correction level for envelope wrinkles, and an execution unit that switches the setting of at least one of the pressure force, the controlled temperature, and the transport speed depending on the correction level set by the setting unit and the width of the envelope to heat the toner image on the envelope. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-114000 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present disclosure is to obtain a fixing device and image forming system that can suppress deterioration of image quality due to vibration when the heating member comes into contact with the pressure member, or ensure fixability and high gloss of a toner image on a recording medium, depending on the type of recording medium and image quality requirements, compared to when the load at the contact point between the heating member and the pressure member is always constant. [Means for solving the problem]

[0005] The fixing device according to the first embodiment includes a heating member that heats a toner image on the surface of a recording medium, a pressure member having a recessed portion formed on its outer surface into which a gripping portion that grips the front end side of the recording medium fits, and which rotates and pressurizes the recording medium between the heating member, a moving unit that moves the heating member and the pressure member relatively to a position where the heating member contacts the outer peripheral surface of the pressure member directly or via the recording medium, and a position where the heating member moves away from the outer peripheral surface of the pressure member when the recessed portion passes, and a switching unit that switches the load at the contact portion between the heating member and the outer peripheral surface of the pressure member between high and low depending on the type of recording medium or a user's selection.

[0006] The fixing device according to the second aspect is the fixing device according to the first aspect, further comprising a heat quantity changing section that changes the amount of heat applied to the toner image on the surface of the recording medium depending on the type of the recording medium or a user's selection.

[0007] The fixing device of the third aspect is the fixing device of the first aspect, further comprising a non-contact heating section that is provided upstream of the heating member in the transport direction of the recording medium and heats a toner image on the surface of the recording medium in a non-contact state, and a transport section that transports the recording medium between the heating member and the pressure member while facing the surface of the recording medium to the non-contact heating section.

[0008] The fixing device according to a fourth aspect is the fixing device according to the third aspect, further comprising a heat quantity changing section that changes the amount of heat applied from the non-contact heating section to the toner image on the surface of the recording medium in accordance with the type of the recording medium or a user's selection.

[0009] A fixing device according to a fifth aspect is the fixing device according to the first aspect, wherein when the thickness of the recording medium is equal to or greater than the thickness of plain paper, or when the recording medium is a film member, the switching unit increases the load at the contact portion between the heating member and the outer peripheral surface of the pressure member.

[0010] A fixing device according to a sixth aspect is the fixing device according to the first aspect, wherein when a user selects a high gloss mode, the switching unit increases the load at the contact portion between the heating member and the outer peripheral surface of the pressure member.

[0011] A fixing device according to a seventh aspect is the fixing device according to the first aspect, wherein when a user selects a high image quality mode or when the recording medium is thinner than plain paper, the switching unit reduces the load at the contact portion between the heating member and the outer peripheral surface of the pressure member.

[0012] The fixing device of the eighth aspect is the fixing device of the second aspect, wherein when a user selects a high image quality mode or when the recording medium is a film member, the heat change section increases the amount of heat applied to the toner image on the surface of the recording medium.

[0013] A fixing device according to a ninth aspect is the fixing device according to the fourth aspect, wherein when a user selects a high image quality mode or when the recording medium is a film member, the heat change section increases the amount of heat applied to the toner image on the surface of the recording medium.

[0014] A fixing device according to a tenth aspect is the fixing device according to the fourth aspect, wherein when a user selects a high gloss mode, the heat quantity change section reduces the amount of heat applied to the toner image on the surface of the recording medium.

[0015] An image forming system according to an eleventh aspect has an image forming unit that forms a toner image on a recording medium, an input unit that allows a user to select an image quality mode by input, and a fixing device according to any one of the first to tenth aspects that fixes the toner image formed by the image forming unit to the recording medium. Effect of the Invention

[0016] According to the fixing device of the first aspect, compared to a case where the load at the contact point between the heating member and the pressure member is always constant, it is possible to suppress deterioration of image quality due to vibration when the heating member contacts the pressure member, or to ensure fixability and high gloss of the toner image on the recording medium, depending on the type of recording medium and the image quality requirements.

[0017] The fixing device according to the second aspect can ensure high fixability and gloss of the toner image on the recording medium, compared to a case in which the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0018] According to the fixing device of the third aspect, it is possible to ensure high fixability and gloss of an image on a recording medium, compared to a case in which the surface of the recording medium is not heated on the upstream side of the heating member.

[0019] According to the fixing device of the fourth aspect, it is possible to ensure high fixability and gloss of the toner image on the recording medium, compared to when the amount of heat applied from the non-contact heating section to the toner image on the surface of the recording medium is constant.

[0020] According to the fixing device of the fifth aspect, when the thickness of the recording medium is equal to or greater than the thickness of plain paper or when the recording medium is a film material, it is possible to ensure fixability and high gloss of the toner image on the recording medium, compared to a case where the load at the contact portion between the heating member and the outer peripheral surface of the pressure member is constant.

[0021] According to the fixing device of the sixth embodiment, when a high gloss image is required, it is possible to ensure fixability and high gloss of the toner image on the recording medium, compared to a case where the load at the contact portion between the heating member and the outer peripheral surface of the pressure member is constant.

[0022] According to the fixing device of the seventh aspect, degradation of image quality caused by vibration when the heating member comes into contact with the pressure member can be suppressed compared to when the load at the contact portion between the heating member and the outer peripheral surface of the pressure member is constant when the user selects a high image quality mode or when the recording medium is thinner than plain paper.

[0023] According to the fixing device of the eighth aspect, when high image quality is required or when the recording medium is a film material, it is possible to ensure high fixability and high gloss of the toner image on the recording medium, compared to when the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0024] According to the fixing device of the ninth aspect, when high image quality is required or when the recording medium is a film material, it is possible to ensure high fixability and high gloss of the toner image on the recording medium, compared to when the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0025] According to the fixing device of the tenth aspect, when high gloss is required, it is possible to ensure high gloss of the toner image on the recording medium, compared to a case where the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0026] According to the image forming system of the eleventh aspect, compared to a case where the load at the contact point between the heating member and the pressure member is always constant, it is possible to suppress deterioration of image quality due to vibration when the heating member contacts the pressure member, or to ensure fixability and high gloss of the toner image on the recording medium, depending on the type of recording medium and the image quality requirements. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic configuration diagram illustrating an example of an image forming system including a fixing device according to a first embodiment. [Diagram 2] 1 is a schematic diagram illustrating a toner image forming unit of an image forming system including a fixing device according to a first embodiment. [Diagram 3] FIG. 2 is a configuration diagram showing a fixing device according to the first embodiment. [Figure 4] FIG. 2 is a configuration diagram illustrating a part of a fixing unit of the fixing device according to the first embodiment. [Diagram 5] 2 is a block diagram showing an example of a hardware configuration of a fixing device according to the first embodiment; FIG. [Figure 6] 2 is a front view showing a moving portion of a fixing unit used in the fixing device of the first embodiment. FIG. [Figure 7] 4 is a perspective view showing a configuration in the vicinity of a cam shaft of a moving portion of the fixing unit; FIG. [Figure 8] 1A is a front view showing the arrangement of the fixing unit when it is fully separated, and FIG. 1B is an enlarged view showing the vicinity of the cam shaft when the fixing unit is fully separated. [Figure 9] FIG. 2A is a front view showing the arrangement of the home position of the fixing unit, and FIG. 2B is an enlarged view showing the vicinity of the cam shaft in the home position of the fixing unit. [Figure 10] FIG. 1A is a front view showing the arrangement of the fixing unit when a low load is applied, and FIG. 1B is an enlarged view showing the vicinity of the cam shaft when a low load is applied to the fixing unit. [Figure 11] FIG. 2A is a front view showing the arrangement of the fixing unit when a high load is applied, and FIG. 2B is an enlarged view showing the vicinity of a cam shaft when a high load is applied to the fixing unit. [Figure 12] 11 is a diagram showing the relationship between the load of the fixing unit, the heat quantity of the preheating unit, and the required quality. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] An example of an embodiment of the present invention will be described below with reference to the drawings. Note that the arrow H shown in each drawing indicates the vertical direction, i.e., the up-down direction of the device, the arrow W indicates the horizontal direction, i.e., the width direction of the device, and the arrow D indicates the front-rear direction of the device (depth direction of the device).

[0029] First Embodiment First, a description will be given of the configuration of an image forming system 10 including a fixing device 100 according to the first embodiment. Fig. 1 is a schematic diagram showing the configuration of the image forming system 10 according to the first embodiment.

[0030] (Image forming system) 1 is an electrophotographic image forming system that forms a toner image on paper P as an example of a recording medium. Specifically, as shown in FIG 1, the image forming system 10 has a storage section 50, a discharge section 52, an image forming section 12, a conveying mechanism 60, a reversing mechanism 80, a fixing device 100, and a cooling section 90. Furthermore, the image forming system 10 has a control device 200 that controls each section of the image forming system 10.

[0031] (Storage section) 1 has a function of storing paper P. In the image forming system 10, a plurality of (e.g., two) storage sections 50 are provided. The configuration is such that paper P is selectively sent out from the plurality of storage sections 50. As the paper P, a sheet of paper (cut paper) having a predetermined size is used.

[0032] (Discharge section) 1 is a portion where the paper P on which an image has been formed is discharged. Specifically, after the image has been fixed by the fixing device 100, the paper P cooled by the cooling section 90 is discharged to the discharge section 52.

[0033] (Image forming section) The image forming unit 12 shown in Fig. 1 is an example of an image forming unit that forms an image on a recording medium. Specifically, the image forming unit 12 has a function of forming a toner image on a sheet of paper P by an electrophotographic method. More specifically, as shown in Fig. 1, the image forming unit 12 has a toner image forming unit 20 that forms a toner image, and a transfer device 30 that transfers the toner image formed by the toner image forming unit 20 onto the sheet of paper P.

[0034] [Toner image forming section] A plurality of toner image forming units 20 are provided so as to form a toner image for each color. The image forming system 10 is provided with toner image forming units 20 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). (Y), (M), (C), and (K) shown in FIG. 1 indicate components corresponding to the above colors.

[0035] The toner image forming units 20 for each color are basically configured in the same way except for the toner used. Specifically, as shown in Fig. 2, the toner image forming units 20 for each color have a photoconductor drum 21 (photoconductor) that rotates in the direction of the arrow A in Fig. 2, and a charger 22 that charges the photoconductor drum 21. Furthermore, the toner image forming units 20 for each color have an exposure device 23 that exposes the photoconductor drum 21 charged by the charger 22 to form an electrostatic latent image on the photoconductor drum 21, and a developing device 24 that develops the electrostatic latent image formed on the photoconductor drum 21 by the exposure device 23 to form a toner image.

[0036] [Transfer device] 1 has a function of primarily transferring the toner images of the photoconductor drums 21 of each color in a superimposed manner onto an intermediate transfer body, and then secondarily transferring the superimposed toner images onto paper P. Specifically, as shown in FIG. 1, the transfer device 30 includes a transfer belt 31 as an intermediate transfer body, a primary transfer roll 33, and a transfer section 35.

[0037] The primary transfer roll 33 has the function of transferring the toner image formed on the photosensitive drum 21 onto the transfer belt 31 at a primary transfer position T (see Figure 2) between the photosensitive drum 21 and the primary transfer roll 33.

[0038] 1, the transfer belt 31 is endless and has a determined position by being wound around a plurality of rolls 32. When at least one of the rolls 32 is driven to rotate, the transfer belt 31 rotates in the direction of arrow B, and transports the primarily transferred image to the secondary transfer position NT.

[0039] The transfer unit 35 has a function of transferring the toner image transferred onto the transfer belt 31 onto the paper P. The transfer unit 35 specifically includes a secondary transfer unit 34 and an opposing roll 36.

[0040] The opposing roll 36 is disposed below the transfer belt 31 so as to face the transfer belt 31. The secondary transfer unit 34 is disposed inside the transfer belt 31 so that the transfer belt 31 is disposed between the opposing roll 36 and the secondary transfer unit 34, as shown in FIG. 1. As an example, the secondary transfer unit 34 is formed of a corotron. In the transfer unit 35, the toner image transferred onto the transfer belt 31 is transferred onto the paper P passing through the secondary transfer position NT by electrostatic force generated by discharge of the secondary transfer unit 34.

[0041] (Transport mechanism) 1 is a mechanism for transporting paper P. Specifically, the transport mechanism 60 has a function of transporting paper P stored in the storage section 50 to a secondary transfer position NT. Furthermore, the transport mechanism 60 has a function of transporting paper P from the secondary transfer position NT to a fixing unit 120 (a heating roll 130 and a pressure roll 140, which will be described later) which will be described later. In other words, the transport mechanism 60 has a function of transporting paper P, to which a toner image has been transferred, through the fixing device 100.

[0042] 1, the transport mechanism 60 has a feed roll 62, multiple transport rolls 64, and a chain gripper 66. The feed roll 62 is a roll that feeds out the paper P stored in the storage section 50. The multiple transport rolls 64 are rolls that transport the paper P sent out by the feed roll 62 to the chain gripper 66.

[0043] 3, the chain gripper 66 is an example of a conveying section that holds the front end side (leading end side) of the paper sheet P and conveys the paper sheet P. Specifically, the chain gripper 66 includes a pair of chains 72 and a gripper 76 as an example of a gripping section (holding section).

[0044] The pair of chains 72 are formed in a loop as shown in Fig. 1. The pair of chains 72 are arranged at an interval in the front-rear direction of the device (direction D in Fig. 1). The pair of chains 72 are wound around a pair of sprockets (not shown) arranged at one end side and the other end side in the axial direction of the counter roll 36 and the pressure roll 140 described below, respectively, and a pair of sprockets 74 arranged at an interval in the front-rear direction of the device. When one of the pair of sprockets rotates, the chain 72 goes around in the direction of arrow C (see Fig. 1).

[0045] An attachment member 75 (see FIG. 4) to which a gripper 76 is attached is hung between the pair of chains 72 in the front-rear direction of the device. A plurality of attachment members 75 are fixed to the pair of chains 72 at predetermined intervals along the circumferential direction (circumferential direction) of the chains 72. In each drawing, the components of the chain 72 are shown in blocks in order to simplify the illustration of the chain 72.

[0046] A plurality of grippers 76 are attached to the attachment member 75 at predetermined intervals along the front-rear direction of the device (see FIG. 3). The gripper 76 has a function of holding (grasping) the front end of the paper P. By holding the front end of the paper P, the position of the paper P in the paper transport direction is easily determined, and alignment (registration) between the paper P and the image in the transfer unit 35 is easy. Specifically, as shown in FIG. 3 and FIG. 4, the gripper 76 has a claw 76A and a claw base 76B. The gripper 76 is configured to hold the paper P by pinching the front end of the paper P between the claw 76A and the claw base 76B. For example, the gripper 76 has a claw 76A pressed against the claw base 76B by a spring or the like, and the claw 76A opens and closes with respect to the claw base 76B by the action of a cam or the like.

[0047] In the chain gripper 66, the chain 72 rotates in the direction of the arrow C while the gripper 76 holds the front end of the paper P, thereby transporting the paper P. The chain gripper 66 transports the paper P to the secondary transfer position NT while the first surface, which is an example of the front surface of the paper P, faces upward, and then transports the paper P to the fixing unit 120, which will be described later, after passing through a pre-heating section 102 described later. In this manner, the chain gripper 66 is a part that has the function of holding the paper P and passing it through the pre-heating section 102, and also transporting it from the pre-heating section 102 to the fixing unit 120, and also serves as the fixing device 100. Note that a part of the transport path along which the paper P is transported in the transport mechanism 60 is indicated by a dashed line in FIG. 1.

[0048] (Reversal mechanism) 1 is a mechanism for reversing the front and back of the paper P on which the toner image has been fixed by the fixing device 100. More specifically, as shown in FIG 1, the reversing mechanism 80 has a plurality of (e.g., two) transport rolls 82, a reversing device 84, and a plurality of (e.g., seven) transport rolls 86.

[0049] The multiple transport rolls 82 are rolls that transport the paper P sent from the fixing device 100 to the inverting device 84. The inverting device 84 is, for example, a device that transports the paper P while curving it multiple times so that the transport direction of the paper P changes by 90 degrees at a time, twisting the paper P like a Moebius strip and inverting the front and back of the paper P. The multiple transport rolls 86 are rolls that transport the paper P, the front and back of which have been inverted by the inverting device 84, to the chain gripper 66.

[0050] In this way, the reversing mechanism 80 turns over the paper P and delivers it to the chain gripper 66, whereby the chain gripper 66 transports the delivered paper P as a paper P having a fixed toner image on its first surface. In Fig. 1, a part of the transport path along which the paper P is transported in the reversing mechanism 80 is indicated by a dashed line. Note that the image forming system 10 does not necessarily need to include the reversing mechanism 80, and the reversing mechanism 80 may be omitted.

[0051] (Fixing device) 3 is an example of a fixing device that fixes an image formed by an image forming unit onto a recording medium. Specifically, the fixing device 100 is a device that fixes a toner image transferred by the transfer device 30 onto a sheet of paper P.

[0052] 1, the fixing device 100 is disposed downstream of the secondary transfer position NT in the transport direction of the paper P. As shown in FIG. 3, the fixing device 100 includes a pre-heating section 102, the chain gripper 66, a blower 160, a ventilation plate 180, and a fixing unit 120 (fixing section).

[0053] [Pre-heating section] The pre-heating section 102 shown in Fig. 3 is an example of a non-contact heating section that heats the toner image on the surface of the recording medium in a non-contact manner. Specifically, the pre-heating section 102 has a function of non-contact heating the toner image on the surface (i.e., the surface on the pre-heating section 102 side) of the paper P transported by the chain gripper 66. The pre-heating section 102 is provided upstream of the fixing unit 120 in the transport direction (arrow C direction) of the paper P. Although not shown in the figure, the surface of the paper P on the pre-heating section 102 side is the first surface, or the second surface when the paper P is reversed by the reversing mechanism 80.

[0054] The pre-heating section 102 is disposed downstream of the secondary transfer position NT (see FIG. 1) in the transport direction of the paper P, facing the upper surface of the paper P transported by the chain gripper 66. Specifically, the pre-heating section 102 includes a first heating unit 102A, a second heating unit 102B, and a third heating unit 102C, each of which is made up of a plurality of (e.g., three) heating units that can be operated independently. In the first embodiment, the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C are disposed in this order from the upstream side in the transport direction of the paper P. The first heating unit 102A, the second heating unit 102B, and the third heating unit 102C are each provided with a reflecting plate 104, a plurality of heaters 106 (heat sources), and a wire mesh 112.

[0055] In the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C, the heater 106 is controlled to be turned on and off separately, so that heating and non-heating are controlled independently. That is, the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C are an example of a heat quantity change unit that changes the amount of heat applied from the pre-heating unit 102 to the toner image on the paper P. For example, all of the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C can be operated, or two of the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C (for example, the second heating unit 102B and the third heating unit 102C that are closer to the fixing unit 120) can be operated.

[0056] The reflecting plate 104 has a function of reflecting infrared rays from the heater 106 to the lower side of the device (the side of the paper P transported by the chain gripper 66). The reflecting plate 104 is formed using a metal plate such as an aluminum plate. The reflecting plate 104 is formed in a box shape with the lower side of the device open.

[0057] The heater 106 is a cylindrical infrared heater having a length in the front-rear direction of the apparatus. In the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C, a plurality of heaters 106 (for example, six) are arranged inside the reflector 104 along the width direction of the apparatus. Although not shown, the heater 106 includes, for example, a carbon filament and a cylindrical quartz tube that houses the carbon filament therein. The surface temperature of the heater 106 in the pre-heating section 102 is set to a predetermined temperature of, for example, 300° C. or more and 1175° C. or less.

[0058] The wire mesh 112 is fixed to the edge of the opening on the lower side of the reflector 104. As a result, the wire mesh 112 separates the inside of the reflector 104 from the outside of the reflector 104. The wire mesh 112 also prevents the heater 106 from contacting the paper P being transported by the chain gripper 66.

[0059] As described above, the chain gripper 66 transports the paper P while the upper surface of the paper P faces the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C in the pre-heating section 102, by rotating the chain 72 in the direction of the arrow C with the gripper 76 holding the front end of the paper P. In other words, the chain gripper 66 is an example of a transport section that transports the paper P while the upper surface of the paper P faces the pre-heating section 102. Note that when transported by the chain gripper 66, the rear end side of the paper P is not held and is in a free state.

[0060] Furthermore, the chain gripper 66 has a function of transporting the paper P from the pre-heating section 102 to the fixing unit 120. In this manner, the chain gripper 66 functions as an example of a transport section of the fixing device 100 in a portion having a function of passing the paper P through the heating region of the pre-heating section 102 and transporting the paper P from the pre-heating section 102 to the fixing unit 120.

[0061] [Blower] 3 has a function of blowing air to the side of the recording medium transported by the transport unit opposite the pre-heating unit 102. The blowers 160 are arranged inside (inner circumference side) of the chains 72 when viewed in the front-rear direction of the device, below the pre-heating unit 102. The multiple blowers 160 are arranged two-dimensionally (in a matrix) along the transport direction of the paper P and the front-rear direction of the device.

[0062] 3, the blower 160 faces upward and is configured to blow air upward. That is, the blower 160 is configured to blow air in the thickness direction of the paper P only to the lower surface of the paper P transported by the chain gripper 66 while facing the pre-heating unit 102.

[0063] An axial flow fan that blows air in an axial direction is used as the fan 160, for example. Note that a centrifugal fan that blows air in a centrifugal direction, such as a multi-blade fan (for example, a sirocco fan), may also be used as the fan 160.

[0064] The blower 160 blows air to the lower surface of the paper P being transported by the chain gripper 66, thereby lifting the paper P. As a result, the lower surface of the paper P is in a non-contact state. Therefore, the blower 160 has a function of maintaining the non-contact state so that the paper P is transported by the chain gripper 66 with the lower surface of the paper P in a non-contact state. In addition, the blower 160 supplies air only to the lower surface of the paper P, thereby suppressing cooling of the toner transferred to the upper surface of the paper P.

[0065] [Ventilation board] 3 allows air sent from the blower toward the back surface of the recording medium to pass through. Specifically, the ventilation plate 180 is configured with a plate having a plurality of ventilation holes 182 formed therein, which allow air sent from the blower 160 toward the lower surface of the paper P to pass through.

[0066] This ventilation plate 180 is disposed on the inside (inner circumference side) of the chain 72 when viewed in the front-rear direction of the device, below the pre-heating section 102 and above the blower 160, with the thickness direction being the up-down direction of the device. That is, it is disposed on the blowing direction side of the blower 160 so as to cover the blower 160.

[0067] Each ventilation hole 182 penetrates the ventilation plate 180 in the thickness direction. The ventilation holes 182 are arranged, for example, two-dimensionally (in a matrix) along the transport direction of the paper P and the front-rear direction of the device.

[0068] This ventilation plate 180 is configured so that air blown from the blower 160 passes through a plurality of ventilation holes 182 and hits the lower surface of the paper P transported by the chain gripper 66.

[0069] [Fuser unit] 3 is an example of a fixing section that fixes a toner image on paper P to paper P. Specifically, the fixing unit 120 has a function of fixing the toner image on paper P by contacting with paper P and applying heat and pressure to paper P.

[0070] 3, the fixing unit 120 is disposed downstream of the pre-heating section 102 in the transport direction (direction of arrow C) of the paper P. Specifically, the fixing unit 120 has a heating roll 130, a pressure roll 140, and a driven roll 150.

[0071] [Heating roll] 3 is an example of a heating member that heats a toner image held on the surface of paper P. Specifically, the heating roll 130 is disposed downstream of the pre-heating unit 102 in the transport direction, and has a function of contacting and heating paper P. The heating roll 130 is disposed with its axial direction aligned in the front-rear direction of the apparatus so as to contact the upper surface of paper P (i.e., the surface of paper P on which the toner image is formed).

[0072] As an example, the heating roll 130 has a cylindrical base material 132, a rubber layer 134 formed on the outer periphery of the base material 132, a release layer 136 formed on the outer periphery of the rubber layer 134, and a heater 138 (heat source) housed inside the base material 132. The heater 138 is composed of, for example, a plurality of halogen lamps. The heater 138 is composed of a plurality of halogen lamps, so that the temperature of the heating roll 130 can be changed. The heating roll 130 is an example of a heat quantity changing section that changes the amount of heat applied to the toner image on the surface of the paper P.

[0073] [Driven roll] 3 is disposed with its axis extending in the front-rear direction of the device so as to contact an area of ​​the outer circumferential surface of the heating roll 130 other than the contact area with the paper P. As an example, two driven rolls 150 are provided, but the number of driven rolls 150 can be changed.

[0074] As an example, each driven roll 150 has a cylindrical base material 152 and a heater 154 (heat source) housed inside the base material 152. The driven roll 150 rotates following the heating roll 130 and heats the heating roll 130. The heating roll 130 is heated by the driven roll 150 and the heating roll 130 itself has a heater 138, so that the surface temperature of the heating roll 130 becomes a predetermined temperature of 180°C or more and 200°C or less. By providing two driven rolls 150, for example, one of them can be heated and the other can be unheated. The driven roll 150 is an example of a heat quantity changing unit that changes the amount of heat given to the toner image on the surface of the paper P.

[0075] [Pressure roll] 3 is an example of a pressure member that pressurizes a recording medium between itself and the heating roll 130. Specifically, the pressure roll 140 has a function of pressing paper P by nipping the paper P between itself and the heating roll 130. The pressure roll 140 is disposed below the heating roll 130 with the front-rear direction of the apparatus as its axial direction.

[0076] The circumferential length of the pressure roll 140 is the same as the interval at which grippers 76, which are an example of a gripping portion, are arranged on the chain 72. As shown in Fig. 4, a recessed portion 148 extending in the front-rear direction of the device is formed on the outer circumferential surface of the pressure roll 140. The gripper 76, which holds the front end side of the paper P, is configured to enter the recessed portion 148 when passing between the pressure roll 140 and the heating roll 130. The pressure roll 140 is an example of a pressure cylinder with a recessed portion 148 formed on its outer circumferential surface.

[0077] The pressure roll 140 includes a cylindrical substrate 142, a rubber layer 144 formed on the outer periphery of the substrate 142, and a release layer 146 formed on the outer periphery of the rubber layer 144. As an example, the substrate 142 is made of metal.

[0078] As shown in FIG. 6, the fixing unit 120 has a moving section 220 that relatively moves the heating roll 130 between a position where the heating roll 130 contacts the pressure roll 140 (see FIGS. 10(A) and 11(A)) and a position separated from the pressure roll 140 (see FIG. 9(A)). The moving section 220 includes a first cam 232, a second cam 234, and a cam shaft 236 that supports these. The second cam 234 is an example of a switching section that switches the load at the contact portion between the heating roll 130 and the pressure roll 140 between high and low by rotation (see FIGS. 10(A) and 11(A)). The configuration of the moving section 220 will be described later.

[0079] In the fixing unit 120, the pressure roll 140 is rotated by a drive unit (not shown), the heating roll 130 rotates following the pressure roll 140, and the driven roll 150 rotates following the heating roll 130.

[0080] (cooling section) 1, the cooling section 90 is disposed downstream of the fixing unit 120 in the transport direction (direction of arrow C) of the paper P. The cooling section 90 also includes a plurality of (for example, two) cooling rolls 92 arranged in the device width direction.

[0081] The cooling roll 92 includes a cylindrical roll made of metal or the like, and cools the paper P by sandwiching the paper P between a pair of upper and lower rolls. As an example, the cooling roll 92 cools the paper P by air cooling (heat exchange with the air) by circulating air inside the roll.

[0082] (Operation of image forming system) Next, the operation of the image forming system 10 will be described.

[0083] 1, the paper P is conveyed by a plurality of conveying rolls 64 and handed over to a chain gripper 66. The paper P handed over to the chain gripper 66 is conveyed by the chain gripper 66 to a secondary transfer position NT with the front end held by a gripper 76, and the toner image is transferred from the transfer belt 31 to the surface of the paper P. As shown in FIG. 3, the paper P with the transferred toner image is conveyed by the chain gripper 66 with the surface of the paper P facing a heater 106 of a pre-heating unit 102, and the toner image is heated.

[0084] The paper sheet P on which the toner image has been heated in the pre-heating section 102 is further transported by the chain gripper 66 to the fixing unit 120, where it is pressed and heated while being sandwiched between the heating roll 130 and the pressure roll 140. This fixes the toner image onto the surface of the paper sheet P. When an image is formed only on the surface (i.e., the first surface) of the paper sheet P, the paper sheet P on which the toner image has been fixed is cooled by the cooling roll 92 of the cooling section 90, and then discharged to the discharge section 52.

[0085] When forming images on both sides of the paper P (i.e., double-sided printing), the paper P is turned over by a reversing mechanism 80 shown in Fig. 1 and then handed over to the chain gripper 66 again. The paper P handed over to the chain gripper 66 is transported to the secondary transfer position NT as the paper P having the fixed toner image on its first side, and the toner image is transferred from the transfer belt 31 to the back side (i.e., the second side).

[0086] The paper P with the toner image transferred to the back surface (i.e., second surface) is heated in the pre-heating section 102, and then sandwiched between the heating roll 130 and the pressure roll 140 and pressurized and heated, so that the toner image is fixed to the paper P. At this time, in the pre-heating section 102, the blower 160 blows air to the first surface of the paper P transported by the chain gripper 66, so that the blower 160 maintains the non-contact state so that the paper P is transported without contacting the first surface of the paper P. The paper P with the fixed toner image is cooled by the cooling roll 92 of the cooling section 90, and then discharged to the discharge section 52.

[0087] (Hardware configuration of the fixing device) 5 is a block diagram showing a hardware configuration of the fixing device 100. As shown in FIG. 5, the fixing device 100 includes the control device 200, the pre-heating section 102, the fixing unit 120, the display section 211, and the input section 212 as described above. The pre-heating section 102 includes a first heating unit 102A, a second heating unit 102B, and a third heating unit 102C, which are three heating units. The fixing unit 120 includes a heating roll 130, a driven roll 150, a pressure roll 140, and a moving section 220. The moving section 220 includes a camshaft motor 270 for rotating the camshaft 236.

[0088] The control device 200 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a storage 204, and an input / output interface 205. Each component is connected to each other via a bus 209 so as to be able to communicate with each other.

[0089] The CPU 201 is a central processing unit that executes various programs and controls each part. The CPU 201 is an example of a processor. That is, the CPU 201 reads a program from the ROM 202 or the storage 204, and executes the program using the RAM 203 as a working area. The CPU 201 controls each of the above components and performs various arithmetic processing according to the program recorded in the ROM 202 or the storage 204. In this embodiment, an information processing program is stored in the ROM 202 or the storage 204.

[0090] The ROM 202 stores various programs and various data. The RAM 203 temporarily stores programs or data as a working area. The storage 204 is configured with an HDD (Hard Disk Drive) or an SSD (Solid State Drive) and stores various programs including an operating system and various data. The storage 204 stores a printer driver program. The CPU 201 reads the printer driver program from the storage 204 and executes the program to function as the printer driver.

[0091] The input / output interface 205 is an interface for communicating with each device mounted on the fixing device 100. The control device 200 is connected to a display unit 211, an input unit 212, the pre-heating unit 102, and the fixing unit 120 via the input / output interface 205. The display unit 211, the input unit 212, the pre-heating unit 102, and the fixing unit 120 may be directly connected via a bus 209.

[0092] The display unit 211 displays various information for forming an image. For example, the display unit 211 displays a screen showing the type of recording medium and the required image quality mode. The types of recording medium include, for example, plain paper, thick paper, textured paper, thin paper, and film material. Other types of recording medium include coated paper (for example, coated paper) and uncoated paper, which indicate whether or not the surface is coated with paint. The image quality modes include, for example, a high gloss mode for increasing gloss, a normal gloss mode for normal gloss, a high quality mode for increasing image quality, and a normal quality mode for normal image quality. Here, gloss refers to the luster of the image fixed on the paper P.

[0093] The input unit 212 inputs, for example, the type of recording medium, an instruction or selection of an image quality mode by the user, and the like. As an example, the display unit 211 is, for example, a liquid crystal display, and the input unit 212 inputs information by a touch panel method from a display screen that displays various information displayed on the display unit 211. Note that the input unit 212 may also be one that inputs information by operating a keyboard. The information input from the input unit 212 is sent to the CPU 51 via the input / output interface 205. The input information may also be stored in the storage 204 or the like.

[0094] The CPU 51 controls the operation of the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C in the pre-heating section 102. The CPU 51 changes the amount of heat applied from the pre-heating section 102 to the toner image on the paper P according to the type of paper P or a user selection. As an example, when the amount of heat applied from the pre-heating section 102 to the toner image on the surface of the paper P is to be increased, all of the three units, the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C, are operated. Also, as an example, when the amount of heat applied from the pre-heating section 102 to the toner image on the surface of the paper P is to be decreased, the two units, the second heating unit 102B and the third heating unit 102C, arranged closer to the fixing unit 120, are operated.

[0095] FIG. 12 shows the relationship between the load of the contact portion between the heating roll 130 and the pressure roll 140 of the fixing unit 120, the amount of heat of preheating by the preheating unit 102, and the type and required quality of the recording medium used. As shown in FIG. 12, in the case of thin paper printing using thin paper, thick paper printing using thick paper, or uneven paper printing using uneven paper as the type of recording medium, the amount of heat of preheating by the preheating unit 102 is reduced. In addition, in the case of high gloss printing as the required quality, the amount of heat of preheating by the preheating unit 102 is reduced. In addition, in the case of high quality printing using coated paper or the like as the type of recording medium, or film printing using a film member, the amount of heat of preheating by the preheating unit 102 is increased. As an example, the CPU 201 changes the amount of heat of preheating by controlling the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C by the preheating unit 102 according to the type of recording medium inputted by the input unit 212 and the mode selection by the user.

[0096] 12, when the user selects the high image quality mode via input unit 212, CPU 201 increases the amount of heat imparted from pre-heating unit 102 to the toner image on the surface of sheet P. Also, when the user selects the high gloss mode via input unit 212, CPU 201 decreases the amount of heat imparted from pre-heating unit 102 to the toner image on the surface of sheet P.

[0097] 5, the CPU 201 controls the moving section 220 in the fixing unit 120. Specifically, the moving section 220 controls the rotation of the motor 270 for the cam shaft 236 to move the position of the heating roll 130 relative to the pressure roll 140. For example, the motor 270 rotates the second cam 234 to switch the load of the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140 between high and low.

[0098] As an example, the CPU 201 switches the load of the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140 between high and low by rotating the second cam 234 by the motor 270 in accordance with the type of recording medium input by the input unit 212 or the selection by the user. As shown in Fig. 12, when printing on thin paper, the CPU 201 lowers the load of the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140. Furthermore, when using coated paper or when the user selects a high image quality mode by the input unit 212, the CPU 201 lowers the load of the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140.

[0099] Furthermore, in the case of printing on thick paper or printing on textured paper, the CPU 201 increases the load at the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140. In the case of printing on film or when the user selects the high gloss mode via the input unit 212, the CPU 201 increases the load at the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140.

[0100] As an example, the ROM 202 or the storage 204 stores a table showing the relationship between the load of the contact portion between the heating roll 130 and the pressure roll 140 in the fixing unit 120, the heat amount of the pre-heating unit 102, and the type and required quality of the recording medium as shown in Fig. 12. The CPU 51 controls the pre-heating unit 102 and the fixing unit 120 based on this table.

[0101] Although not shown, the CPU 201 may control the heater 138 of the heating roll 130 or the heaters 154 of the two driven rolls 150 to change the temperature of the heating roll 130 according to the type of recording medium or the user's selection. For example, in the case of thin paper printing, thick paper printing, textured paper printing, or high gloss printing, the temperature of the heating roll 130 may be lowered. For example, in the case of high quality printing such as coated paper, or film printing, the temperature of the heating roll 130 may be higher.

[0102] (Configuration of moving part of fixing unit) Fig. 6 is a front view showing the moving part 220 of the fixing unit 120. Fig. 7 is a perspective view showing the configuration in the vicinity of the cam shaft 236 in the moving part 220.

[0103] As shown in FIG. 6, the moving part 220 includes an upper lever 222, an intermediate lever 224, and a lower lever 226, which are arranged in this order from the top to the bottom in the vertical direction. The moving part 220 also includes a rotating shaft 228 that rotatably supports the upper lever 222, the intermediate lever 224, and the lower lever 226. The rotating shaft 228 is provided on the side closer to the heating roll 130, at a portion where the upper lever 222, the intermediate lever 224, and one end of the lower lever 226 overlap. The rotating shaft 228 and the shaft portion of the pressure roll 140 are supported by a frame (not shown) of the fixing unit 120, and the position of the rotation center of the rotating shaft 228 and the position of the rotation center of the pressure roll 140 do not change. For this reason, the position of the rotation center of the rotating shaft 228 does not change with respect to the rotation center of the pressure roll 140.

[0104] As shown in Fig. 6 and Fig. 7, the moving part 220 includes a first cam 232, a second cam 234, and a cam shaft 236 to which the first cam 232 and the second cam 234 are attached. The cam shaft 236 is disposed between the tip 222A of the upper lever 222 and the tip 224A of the intermediate lever 224 (see Fig. 6). The cam shaft 236 is rotatably supported by the frame 221 of the fixing unit 120, and the position of the rotation center of the cam shaft 236 does not change (see Fig. 7). That is, the position of the rotation center of the cam shaft 236 does not change with respect to the rotation center of the pressure roll 140. The cam shaft 236 is rotationally driven by a motor 270 (see Fig. 5).

[0105] The upper lever 222 is an L-shaped member when viewed from the front side shown in Fig. 6, and includes an upper arm 223A extending horizontally above the fixing unit 120, and a vertical arm 223B extending downward from one end of the upper arm 223A. The end of the upper arm 223A opposite the vertical arm 223B is the tip 222A. A rotation shaft 228 is provided at the end (i.e., the lower end) of the vertical arm 223B opposite the tip 222A. The tip 222A of the upper lever 222 is disposed obliquely above the rotation shaft 228.

[0106] Two driven rolls 150 are rotatably supported on the upper lever 222 via a mounting member 230. Specifically, the mounting member 230 includes a support piece 230A fixed to the upper lever 222, and two arms 230B and 230C extending from the support piece 230A. The two arms 230B and 230C each rotatably support a driven roll 150.

[0107] 6 and 7, a circular first cam follower 238 with which the first cam 232 can come into contact is provided on the tip portion 222A of the upper lever 222. A shaft portion 238A of the first cam follower 238 is rotatably supported by the tip portion 222A of the upper lever 222.

[0108] The intermediate lever 224 extends obliquely upward from near the rotating shaft 228, and a tip 224A of the intermediate lever 224 is disposed above the rotating shaft 228 (see FIG. 6). A circular second cam follower 240 with which the second cam 234 can come into contact is provided at the tip 224A of the intermediate lever 224. A shaft 240A of the second cam follower 240 is rotatably supported by the tip 224A of the intermediate lever 224.

[0109] The lower lever 226 extends horizontally from a portion where the rotation shaft 228 is provided. At a position on the lower lever 226 close to the rotation shaft 228, the heating roll 130 is rotatably supported.

[0110] A tension spring 244 is provided on the tip 226A of the lower lever 226 and the tip 222A of the upper lever 222. One end of the tension spring 244 is hung on a protrusion 227 provided on the tip 226A of the lower lever 226, and the other end of the tension spring 244 is hung on a protrusion 223C provided on the tip 222A of the upper lever 222. The lower lever 226 and the upper lever 222 are pulled by the tension spring 244, so that the heating roll 130 supported by the lower lever 226 and the two driven rolls 150 supported by the upper lever 222 come into contact with each other.

[0111] Further, a compression spring 246 is provided at the tip 226A of the lower lever 226 and the tip 224A of the intermediate lever 224. One end of the compression spring 246 is supported by an attachment portion of the tip 226A of the lower lever 226, and the other end of the compression spring 246 is supported by an attachment portion of the tip 224A of the intermediate lever 224. By the rotation of the second cam 234, the intermediate lever 224 changes the compression state of the compression spring 246 via the second cam follower 240 that contacts the second cam 234, so that the load at the contact portion between the heating roll 130 and the pressure roll 140 can be switched between high and low. That is, the second cam 234 functions as a switching portion that switches the load at the contact portion between the heating roll 130 and the pressure roll 140.

[0112] For example, by contacting the second cam follower 240 near the maximum radius of the second cam 232, the intermediate lever 224 equipped with the second cam follower 240 compresses the compression spring 246 and is pushed down. This increases the load at the contact point between the heating roll 130 and the pressure roll 140 (see FIG. 11(A)). Although not shown, the camshaft 236 is provided with two sensors that detect the positions of the first cam 232 and the second cam 234, and the positions of the first cam 232 and the second cam 234 are detected by signals from the two sensors.

[0113] (Movement of moving part of fixing unit) Next, the operation of the moving part 220 of the fixing unit 120 will be described.

[0114] Fig. 8(A) is a front view showing the arrangement of the fixing unit 120 when it is fully separated, that is, when the pressure roll 140, the heating roll 130, and the driven roll 150 are all separated. Fig. 8(B) is an enlarged view showing the vicinity of the cam shaft 236 when the fixing unit 120 is fully separated. As an example, when the fixing unit 120 is stopped, the pressure roll 140, the heating roll 130, and the driven roll 150 are all separated.

[0115] When the heating roll 130 is brought into contact with the pressure roll 140, the cam shaft 236 is rotated in the direction of arrow R1, and when the heating roll 130 is moved away from the pressure roll 140 (i.e., when retracting), the cam shaft 236 is rotated in the direction of arrow R2 (see Figure 8(B)).

[0116] 8(A) and (B), when the fixing unit 120 is fully separated, the rotation of the cam shaft 236 causes the vicinity of the portion of the first cam 232 with the maximum radius to come into contact with the first cam follower 238 of the upper lever 222. As a result, the first cam follower 238 of the upper lever 222 is pushed by the first cam 232, so that the upper lever 222 is pushed upward relative to the pressure roll 140, and the two driven rolls 150 are separated from the heating roll 130.

[0117] At that time, the lower lever 226 is pulled upward by the tension spring 244, and the second cam follower 240 of the intermediate lever 224 is in contact with the second cam 234 via the compression spring 246. As the lower lever 226 is pulled upward by the tension spring 244, the heating roll 130 is separated from the pressure roll 140.

[0118] FIG. 9(A) is a front view showing the arrangement of the home position of the fixing unit 120, and FIG. 9(B) is an enlarged view showing the vicinity of the cam shaft 236 in the home position of the fixing unit 120. As shown in FIGS. 9(A) and 9(B), the rotation of the cam shaft 236 causes the middle length portion of the radius of the first cam 232 to contact the first cam follower 238 of the upper lever 222. As a result, the lower lever 226 and the upper lever 222 are pulled by the tension spring 244, so that the heating roll 130 supported by the lower lever 226 and the two driven rolls 150 supported by the upper lever 222 come into contact with each other. At this time, the short radius portion of the second cam 234 faces the second cam follower 240, and the second cam 234 and the second cam follower 240 are not in contact with each other. Therefore, the intermediate lever 224 is not pushed downward, and the heating roll 130 and the pressure roll 140 supported by the lower lever 226 are not in contact with each other.

[0119] In the first embodiment, when the concave portion 148 of the pressure roll 140 passes a position facing the heating roll 130 due to the rotation of the pressure roll 140, the heating roll 130 is moved to a position separated from the outer peripheral surface of the pressure roll 140. The heating roll 130 shown in FIG. 9(A) is in a state where it has moved to a position separated from the outer peripheral surface of the pressure roll 140. When moving from the fully separated state shown in FIG. 8(A) to the home position (FIG. 9(A)) where the driven roll 150 contacts the heating roll 130, the camshaft 236 is rotated in the direction of the arrow R1. When separating the heating roll 130 and the pressure roll 140 from a state where the heating roll 130 and the pressure roll 140 are in contact with each other (see FIG. 10(A) and the like), the camshaft 236 is rotated in the direction of the arrow R2.

[0120] 10A is a front view showing the arrangement of the fixing unit 120 when a low load is applied, and FIG. 10B is an enlarged view showing the vicinity of the cam shaft 236 when a low load is applied to the fixing unit 120. As shown in FIGS. 10A and 10B, the rotation of the cam shaft 236 causes the middle length portion of the radius of the second cam 234 to contact the second cam follower 240 of the intermediate lever 224. As a result, the intermediate lever 224 is pushed down by the second cam 234 relative to the position of the intermediate lever 224 shown in FIGS. 9A and 9B, and the lower lever 226 is pushed down via the compression spring 246. As a result, the heating roll 130 rotatably supported by the lower lever 226 is pressed against the pressure roll 140 by the compression of the compression spring 246. At this time, since the portion of the second cam 234 at the middle length of the radius is in contact with the second cam follower 240 of the intermediate lever 224, the heating roll 130 comes into contact with the pressure roll 140 with a low load.

[0121] At this time, the first cam 232 is not in contact with the first cam follower 238 of the upper lever 222. In addition, the second cam 234 does not come into contact with the first cam follower 238 of the upper lever 222 because the first cam follower 238 and the axial position of the cam shaft 236 are different (see FIG. 7).

[0122] As described above, when moving from the position when a low load is applied as shown in Figures 10(A) and (B) to the home position where the heating roll 130 is separated from the pressure roll 140 as shown in Figures 9(A) and (B), the cam shaft 236 is rotated in the direction of arrow R2.

[0123] 11A is a front view showing the arrangement of the fixing unit 120 when a high load is applied, and FIG. 11B is an enlarged view showing the vicinity of the cam shaft 236 when a high load is applied to the fixing unit 120. As shown in FIGS. 11A and 11B, the rotation of the cam shaft 236 in the direction of the arrow R1 causes the vicinity of the maximum radius of the second cam 234 to contact the second cam follower 240 of the intermediate lever 224. As a result, the intermediate lever 224 is further pressed down by the second cam 234 with respect to the position of the intermediate lever 224 shown in FIGS. 10A and 10B, and the compression amount of the compression spring 246 increases, so that the heating roll 130 rotatably supported by the lower lever 226 is pressed against the pressure roll 140 with a high load.

[0124] At this time, the first cam 232 is not in contact with the first cam follower 238 of the upper lever 222 .

[0125] In addition, when moving from the position when a high load is applied as shown in Figures 11(A) and (B) to the home position where the heating roll 130 is separated from the pressure roll 140 as shown in Figures 9(A) and (B), the cam shaft 236 is rotated in the direction of arrow R2.

[0126] (Operation of the first embodiment) Next, the operation of the first embodiment will be described.

[0127] In the fixing device 100, the paper P is pressed between the heating roll 130 and the pressure roll 140, and the toner image on the surface of the paper P is heated by the heat from the heating roll 130. A recessed portion 148 is formed on the outer peripheral surface of the pressure roll 140, into which the gripper 76 that grips the front end of the paper P enters. The moving portion 220 moves the heating roll 130 relatively between a position where the heating roll 130 contacts the outer peripheral surface of the pressure roll 140 directly or via the paper P (see FIGS. 10(A) and 11(A)), and a position where the heating roll 130 is separated from the outer peripheral surface of the pressure roll 140 when the recessed portion 148 passes (see FIG. 9(A)).

[0128] The CPU 201 of the control device 200 rotates the cam shaft 236 by the motor 270 in response to the type of paper P or a user selection. As a result, the rotation of the second cam 234 switches the load at the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140 between high and low (see FIG. 10(A) and FIG. 11(A)).

[0129] Generally, in an image forming system, in a fixing device, when a heating roll comes into contact with or separates from a pressure roll, speed fluctuation of the pressure roll may be transmitted to the transfer belt 31 via the chain gripper 66 and the opposing roll 36, causing impulse banding. Impulse banding refers to image disturbance caused by an impact.

[0130] In the fixing device, impulse banding caused by speed fluctuations of the chain gripper 66 can be suppressed by lowering the load when the heating roll contacts the pressure roll, but ensuring the fixability of thick paper P and controlling the gloss become issues. For example, if the pressure when the heating roll contacts the pressure roll is low, it may be difficult to fix a toner image on thick paper or textured paper. Also, if the load at the contact point between the heating roll and the pressure roll is high, the gloss will be high, and if the load at the contact point between the heating roll and the pressure roll is low, the gloss will be low, making it difficult to control the gloss.

[0131] In the fixing device 100 of the first embodiment, the moving section 220 moves the heating roll 130 to a position where it is separated from the outer circumferential surface of the pressure roll 140 when the concave portion 148 of the pressure roll 140 passes (see FIGS. 10(A) and 11(A)). This prevents the speed fluctuation of the pressure roll 140, which occurs when the heating roll 130 comes into contact with and separates from the pressure roll 140, from being propagated to the chain gripper 66. Furthermore, in the fixing device 100, the load at the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140 is switched between high and low by the rotation of the second cam 234 according to the type of paper P or a user selection.

[0132] 12, in the case of high quality printing such as printing on thin paper or coated paper, the load at the contact portion between the heating roll 130 and the pressure roll 140 is reduced. In the case of high gloss printing, printing on thick paper, printing on textured paper, or printing on film, the load at the contact portion between the heating roll 130 and the pressure roll 140 is increased.

[0133] Therefore, in the fixing device 100, compared to when the load at the contact point between the heating roll and the pressure roll is always constant, it is possible to suppress deterioration of image quality due to vibration when the heating roll 130 contacts the pressure roll 140, or to ensure fixability and high gloss of the toner image on the paper P, depending on the type of paper P and the image quality requirements.

[0134] Furthermore, the fixing device 100 changes the amount of heat applied to the toner image on the surface of the paper P in accordance with the type of paper P or the user's selection. For example, the temperature of the heating roll 130 is changed in accordance with the type of paper P or the user's selection. Therefore, the fixing device 100 can ensure high fixability and high gloss of the toner image on the paper P compared to when the amount of heat applied to the toner image on the surface of the paper P is constant.

[0135] The fixing device 100 also includes a pre-heating section 102 that heats the toner image on the surface of the paper P in a non-contact state, upstream of the heating roll 130 in the transport direction of the paper P. The fixing device 100 also includes a chain gripper 66 that transports the paper P between the heating roll 130 and the pressure roll 140 while the surface of the paper P faces the pre-heating section 102. Therefore, the fixing device 100 can ensure fixability and high gloss of the image on the paper P, compared to a case in which the surface of the paper P is not heated upstream of the heating roll.

[0136] The fixing device 100 also includes a first heating unit 102A, a second heating unit 102B, and a third heating unit 102C that change the amount of heat applied from the pre-heating unit 102 to the toner image on the surface of the paper P according to the type of paper P or the user's selection. For example, as shown in FIG. 12, in the case of thin paper printing, high gloss printing, thick paper printing, or textured paper printing, the amount of heat pre-heated by the pre-heating unit 102 is reduced by operating the two second heating units 102B and the third heating unit 102C that are closer to the fixing unit 120. For example, in the case of high quality printing such as coated paper or film printing, the amount of heat pre-heated by the pre-heating unit 102 is increased by operating all three units: the first heating unit 102A, the second heating unit 102B, and the third heating unit 102C. Therefore, in the fixing device 100, the fixability of the toner image on the paper P and high gloss can be ensured compared to the case where the amount of heat applied from the pre-heating unit to the toner image on the surface of the paper P is constant.

[0137] Furthermore, when the thickness of the paper P is equal to or greater than that of plain paper, or when the recording medium is a film material, the fixing device 100 increases the load at the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140 by the rotation of the second cam 234 (see FIG. 12). Therefore, in the fixing device 100, it is possible to ensure high fixability and high gloss of the toner image on the paper P, compared to a case where the load at the contact portion between the heating roll and the outer circumferential surface of the pressure roll is constant when the thickness of the paper P is equal to or greater than that of plain paper, or when the recording medium is a film material.

[0138] Furthermore, when the user selects the high gloss mode, the fixing device 100 increases the load at the contact portion between the heating roll 130 and the outer circumferential surface of the pressure roll 140 by the rotation of the second cam 234 (see FIG. 12). Therefore, in the fixing device 100, when a high gloss image is required, it is possible to ensure fixability and high gloss of the toner image on the paper P, compared to a case where the load at the contact portion between the heating roll and the outer circumferential surface of the pressure roll is constant.

[0139] Furthermore, when the user selects the high-image-quality mode or when the paper P is thinner than the thickness of plain paper, the fixing device 100 reduces the load at the contact portion between the heating roll 130 and the outer peripheral surface of the pressure roll 140 by rotating the second cam 234 (see FIG. 12). Therefore, in the fixing device 100, deterioration of image quality due to vibration when the heating roll 130 contacts the pressure roll 140 can be suppressed compared to when the load at the contact portion between the heating roll and the outer peripheral surface of the pressure roll is constant when the user selects the high-image-quality mode or when the paper P is thinner than the thickness of plain paper.

[0140] Furthermore, when the user selects a high image quality mode or when the recording medium is a film material, the fixing device 100 increases the amount of heat applied from the pre-heating unit 102 to the toner image on the surface of the paper P (see FIG. 12). Therefore, the fixing device 100 can ensure high fixability and gloss of the toner image on the paper P compared to when a high image quality is required or when the recording medium is a film material and the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0141] Furthermore, when the user selects the high gloss mode, the fixing device 100 reduces the amount of heat applied from the pre-heating unit 102 to the toner image on the surface of the paper P. Therefore, the fixing device 100 can ensure high gloss of the toner image on the paper P, compared to a case where the amount of heat applied to the toner image on the surface of the paper P is constant when high gloss is required.

[0142] The image forming system 10 also includes an image forming unit 12 that forms a toner image on paper P, an input unit 212 that allows a user to select an image quality mode, and a fixing device 100 that fixes the toner image formed by the image forming unit 12 to paper P. Therefore, in the image forming system 10, compared to a case where the load at the contact portion between the heating roll and the pressure roll is always constant, it is possible to suppress deterioration of image quality caused by vibration when the heating roll 130 contacts the pressure roll 140, or to ensure fixability and high gloss of the toner image on paper P according to the type of paper P and image quality requirements.

[0143] <Other> In the above embodiment, the paper P or the film member is used as an example of the recording medium, but the present invention is not limited to this. For example, a sheet material formed in a sheet shape (paper shape, film shape) other than the paper P may be used as an example of the recording medium.

[0144] In the above embodiment, the chain gripper 66 as an example of a transport section transports the paper P to the secondary transfer position NT, and then transports the paper P to the fixing unit 120 after passing through the pre-heating section 102, but this is not limited to the above. Another example of the transport section may be a transport section such as a chain gripper to which the paper P that has passed through the secondary transfer position NT is handed over, and the paper P is transported to the fixing unit 120 after passing through the pre-heating section 102. In this case, the paper P is transported to the secondary transfer position NT by another transport section (for example, transport rolls).

[0145] In the above embodiment, the load at the contact portion between the heating roll 130 and the outer peripheral surface of the pressure roll 140 and the amount of pre-heating heat by the pre-heating unit 102 are changed according to the type of recording medium and the required quality shown in Fig. 12, but the present disclosure is not limited to this configuration. For example, it is possible to change the conditions of the recording medium and the required quality that change the load at the contact portion between the heating roll 130 and the outer peripheral surface of the pressure roll 140 and the amount of pre-heating heat by the pre-heating unit 102.

[0146] The above-described processing of the fixing device 100 can also be realized by a dedicated hardware circuit. In this case, the processing may be executed by a single piece of hardware, or may be executed by a plurality of pieces of hardware.

[0147] The program for operating the fixing device 100 may be provided by a computer-readable recording medium such as a Universal Serial Bus (USB) memory, a flexible disk, or a Compact Disc Read Only Memory (CD-ROM), or may be provided online via a network such as the Internet. In this case, the program recorded in the computer-readable recording medium is usually transferred to and stored in a memory or storage. The program may be provided as a standalone application software, or may be incorporated into the software of the fixing device 100 or the image forming system 10 as one function of the device.

[0148] Although the present disclosure has been described in detail with respect to a specific embodiment, the present disclosure is not limited to such embodiment, and it will be apparent to those skilled in the art that various other embodiments are possible within the scope of the present disclosure.

[0149] <Preferred aspects of the present disclosure> Preferred aspects of the present disclosure will be described below.

[0150] (((1))) a heating member for heating the toner image on the surface of the recording medium; a pressing member having an outer circumferential surface formed with a recess into which a gripping portion that grips a front end side of the recording medium fits, the pressing member rotating and pressing the recording medium between the pressing member and the heating member; a moving unit that moves the heating member and the pressure member relatively to a position where the heating member contacts the outer peripheral surface of the pressure member directly or via the recording medium, and a position where the heating member is separated from the outer peripheral surface of the pressure member when the concave portion passes; a switching unit that switches the load of the contact portion between the heating member and the outer peripheral surface of the pressing member to high or low depending on the type of the recording medium or a user's selection; A fixing device having the same.

[0151] (((2))) The fixing device according to (((1))), further comprising a heat quantity changing section that changes the amount of heat applied to the toner image on the surface of the recording medium in accordance with the type of the recording medium or a user selection.

[0152] (((3))) a non-contact heating unit that is provided upstream of the heating member in a conveying direction of the recording medium and that heats a toner image on a surface of the recording medium in a non-contact state; a conveying unit that conveys the recording medium between the heating member and the pressure member while the surface of the recording medium faces the non-contact heating unit; The fixing device according to (((1))) or (((2))), further comprising:

[0153] (((4))) The fixing device described in (((3))) has a heat quantity changing section that changes the amount of heat applied from the non-contact heating section to the toner image on the surface of the recording medium in accordance with the type of the recording medium or a user selection.

[0154] (((5))) A fixing device described in any one of (((1))) to (((4))), wherein when the thickness of the recording medium is equal to or greater than the thickness of plain paper, or when the recording medium is a film material, the switching unit increases the load at the contact portion between the heating member and the outer peripheral surface of the pressure member.

[0155] (((6))) A fixing device described in any one of (((1))) to (((5))), wherein when a user selects a high gloss mode, the switching unit increases the load at the contact portion between the heating member and the outer peripheral surface of the pressure member.

[0156] (((7))) A fixing device described in any one of (((1))) to (((6))), wherein when a user selects a high image quality mode or when the recording medium is thinner than plain paper, the switching unit reduces the load at the contact portion between the heating member and the outer peripheral surface of the pressure member.

[0157] (((8))) The fixing device described in (((2))) above, wherein when a user selects a high image quality mode or when the recording medium is a film material, the heat change section increases the amount of heat applied to the toner image on the surface of the recording medium.

[0158] (((9))) The fixing device described in (((4))) above, wherein when a user selects a high image quality mode or when the recording medium is a film material, the heat change section increases the amount of heat applied to the toner image on the surface of the recording medium.

[0159] (((10))) The fixing device according to ((4))), wherein when a user selects a high gloss mode, the heat quantity changing section reduces the amount of heat applied to the toner image on the surface of the recording medium.

[0160] (((11))) an image forming unit that forms a toner image on a recording medium; an input unit capable of selecting an image quality mode by a user's input; a fixing device according to any one of ((1)) to ((10)) that fixes a toner image formed by the image forming unit onto the recording medium; An image forming system comprising:

[0161] According to the fixing device described in (((1))), compared to a case where the load at the contact portion between the heating member and the pressure member is always constant, it is possible to suppress deterioration of image quality caused by vibration when the heating member comes into contact with the pressure member, or to ensure fixability and high gloss of the toner image on the recording medium, depending on the type of recording medium and the image quality requirements.

[0162] According to the fixing device described in (((2))), it is possible to ensure high fixability and gloss of the toner image on the recording medium, compared to when the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0163] According to the fixing device described in (((3))), it is possible to ensure high fixability and high gloss of an image on the recording medium, compared to a case in which the surface of the recording medium is not heated upstream of the heating member.

[0164] According to the fixing device described in (((4))), it is possible to ensure high fixability and high gloss of the toner image on the recording medium, compared to when the amount of heat applied from the non-contact heating section to the toner image on the surface of the recording medium is constant.

[0165] According to the fixing device described in (((5))), when the thickness of the recording medium is equal to or greater than the thickness of plain paper or when the recording medium is a film material, it is possible to ensure good fixation of the toner image onto the recording medium and high gloss, compared to a case in which the load at the contact portion between the heating member and the outer peripheral surface of the pressure member is constant.

[0166] According to the fixing device described in (((6))), when a high gloss image is required, it is possible to ensure good fixation of the toner image on the recording medium and high gloss, compared to a case where the load at the contact portion between the heating member and the outer peripheral surface of the pressure member is constant.

[0167] According to the fixing device described in (((7))), deterioration of image quality caused by vibration when the heating member comes into contact with the pressure member can be suppressed, compared to when the load at the contact portion between the heating member and the outer peripheral surface of the pressure member is constant when the user selects a high image quality mode or when the recording medium is thinner than plain paper.

[0168] According to the fixing device described in (((8))), when high image quality is required or when the recording medium is a film material, it is possible to ensure high fixability and high gloss of the toner image on the recording medium, compared to when the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0169] According to the fixing device described in (((9))), when high image quality is required or when the recording medium is a film material, it is possible to ensure high fixability and high gloss of the toner image on the recording medium, compared to when the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0170] According to the fixing device described in (((10))), when high gloss is required, it is possible to ensure high gloss of the toner image on the recording medium, compared to a case where the amount of heat applied to the toner image on the surface of the recording medium is constant.

[0171] According to the image forming system described in (((11))), compared to a case where the load at the contact portion between the heating member and the pressure member is always constant, it is possible to suppress deterioration of image quality caused by vibration when the heating member comes into contact with the pressure member, or to ensure good fixation of the toner image on the recording medium and high gloss, depending on the type of recording medium and the image quality requirements. [Explanation of symbols]

[0172] 10. Image forming system 12 Image forming unit (an example of an image forming unit) 66 Chain gripper (an example of a conveying unit) 76 Gripper (an example of a gripping part) 100 Fixing device 102 Pre-heating section (an example of a non-contact heating section) 102A First heating unit (an example of a heat quantity changing part) 102B Second heating unit (an example of a heat quantity changing part) 102C Third heating unit (an example of a heat quantity changing part) 130 Heating roll (an example of a heating member) 140 Pressure roll (an example of a pressure member) 148 Concave part 200 Control device (an example of a switching unit) 212 Input section 220 Mobile Division 234 Second cam (an example of a switching part) P Paper (an example of a recording medium)

Claims

1. a heating member for heating the toner image on the surface of the recording medium; a pressing member having an outer circumferential surface formed with a recess into which a gripping portion that grips a front end side of the recording medium fits, the pressing member rotating and pressing the recording medium between the pressing member and the heating member; a moving unit that moves the heating member and the pressure member relatively to a position where the heating member contacts the outer peripheral surface of the pressure member directly or via the recording medium, and a position where the heating member is separated from the outer peripheral surface of the pressure member when the concave portion passes; a switching unit that switches the load of the contact portion between the heating member and the outer peripheral surface of the pressing member to high or low depending on the type of the recording medium or a user's selection; A fixing device having the same.

2. 2. The fixing device according to claim 1, further comprising a heat quantity changing section that changes the amount of heat applied to the toner image on the surface of the recording medium in accordance with the type of the recording medium or a user's selection.

3. a non-contact heating unit that is provided upstream of the heating member in a conveying direction of the recording medium and that heats a toner image on a surface of the recording medium in a non-contact state; a conveying unit that conveys the recording medium between the heating member and the pressure member while the surface of the recording medium faces the non-contact heating unit; The fixing device according to claim 1 , further comprising:

4. 4. The fixing device according to claim 3, further comprising a heat quantity changing section that changes the amount of heat applied from the non-contact heating section to the toner image on the surface of the recording medium in accordance with the type of the recording medium or a user's selection.

5. 2. The fixing device according to claim 1, wherein the switching unit increases a load at a contact portion between the heating member and an outer peripheral surface of the pressure member when the thickness of the recording medium is equal to or greater than that of plain paper, or when the recording medium is a film member.

6. The fixing device according to claim 1 , wherein when a user selects a high gloss mode, the switching unit increases a load applied to a contact portion between the heating member and the outer circumferential surface of the pressure member.

7. 2. The fixing device according to claim 1, wherein the switching unit reduces a load at the contact portion between the heating member and the outer peripheral surface of the pressure member when a user selects a high-image-quality mode or when the recording medium is thinner than plain paper.

8. 3. The fixing device according to claim 2, wherein the heat quantity changing section increases the amount of heat applied to the toner image on the surface of the recording medium when a user selects a high image quality mode or when the recording medium is a film member.

9. 5. The fixing device according to claim 4, wherein the heat quantity changing section increases the quantity of heat applied to the toner image on the surface of the recording medium when a user selects a high image quality mode or when the recording medium is a film member.

10. 5. The fixing device according to claim 4, wherein when a user selects a high gloss mode, the heat quantity changing section reduces the amount of heat applied to the toner image on the surface of the recording medium.

11. an image forming unit that forms a toner image on a recording medium; an input unit capable of selecting an image quality mode by a user's input; a fixing device according to claim 1 , which fixes a toner image formed by the image forming unit onto the recording medium; An image forming system comprising:

Images