Fixing device and image forming system using same

Abstract

A fixing device and an image forming system using the same, the fixing device including: a heating fixing member having a heating source; a belt-shaped conveying and fixing member which is provided so as to be tensioned on the heating and fixing member, can circulate, and conveys the medium by coming into contact with an image surface of the medium; a pressure fixing member disposed to face the heating fixing member with the conveying fixing member interposed therebetween, the pressure fixing member being pressurized so as to form a fixing region between the pressure fixing member and the heating fixing member; a cooling member provided in contact with a back surface of a medium transport region of the transport fixing member on a downstream side of the transport fixing member in a transport direction of the medium from the fixing region, and cooling the transport fixing member; and a switching member that switches the conveying fixing member and the cooling member to a contact state or a non-contact state according to a passing state of the medium in a cooling region of the cooling member.

Description

Technical Field

[0001] The present invention relates to a fixing device and an image forming system using the fixing device. Background Art

[0002] Conventionally, as this type of fixing device, for example, devices described in Patent Documents 1 to 3 are known.

[0003] Patent Document 1 discloses a gloss imparting device having a cooling mode in which an endless belt is cooled by a radiator and a non-cooling mode in which the endless belt is not cooled by the radiator, and the non-cooling mode is implemented during a startup operation.

[0004] Patent document 2 discloses a method that includes a conveyor belt driving device, which, in a fixing device having a heat sink, temporarily stops or slows down a conveyor belt component after the rear end of a recording material passes through a fixing nip area, and returns the conveyor belt component to its original state before the front end of a subsequent recording material reaches the fixing nip area.

[0005] Patent document 3 discloses a fixing device having a gloss processing mode for performing gloss treatment on the image forming surface after cooling a recording medium having an unfixed colorant image fixed thereon to a predetermined temperature range by means of a cooling member while maintaining contact with a fixing belt, and having a temperature adjustment mode for adjusting the temperature of the cooling member in a startup state and / or a standby state.

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-181337 (Modes for Implementing the Invention, Figure 2 )

[0007] Patent Document 2: Japanese Patent Application Publication No. 2007-163787 (Preferred Mode for Carrying Out the Invention, Figure 4 )

[0008] Patent Document 3: Japanese Patent Application Publication No. 2006-243444 (Preferred Mode for Carrying Out the Invention, Figure 4 ) Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a fixing device and an image forming system using the fixing device, which can suppress unnecessary cooling that does not contribute to cooling of the medium and ensure fixing performance, compared with the case where a belt-shaped conveying fixing member is continuously cooled when an unfixed image on a medium is fixed by heating and cooling the conveying fixing member.

[0010] The first technical feature of the present invention is a fixing device that heats and pressurizes a medium holding an unfixed image, cools it, and fixes the unfixed image, the fixing device being characterized in that it comprises: a heating fixing member having a heating source; a belt-shaped conveying fixing member that is arranged to be stretched on the heating fixing member and capable of circulation, and that contacts the image surface of the medium to convey the medium; a pressurizing fixing member that is arranged opposite to the heating fixing member with the conveying fixing member sandwiched therebetween, and that applies pressure in a manner that forms a fixing area between the conveying fixing member and the heating fixing member; a cooling member that is arranged on the downstream side of the conveying direction of the medium in the conveying fixing member than the fixing area, and that contacts the back side of the medium conveying area of ​​the conveying fixing member, and cools the conveying fixing member; and a switching member that switches the conveying fixing member and the cooling member to a contact or non-contact state according to the passing state of the medium in the cooling area of ​​the cooling member.

[0011] The second technical feature of the present invention is a fixing device having the first technical feature, characterized in that the switching member switches the conveying fixing member and the cooling member to a non-contact state while the medium does not pass through the cooling area based on the cooling member in the conveying fixing member.

[0012] The third technical feature of the present invention is a fixing device having the first or second technical feature, characterized in that before the front end of the medium in the conveying direction reaches the entrance of the cooling area, the switching member switches the cooling member to a contact state, and when the rear end of the medium in the conveying direction has reached the exit of the cooling area, the cooling member is switched to a non-contact state.

[0013] The fourth technical feature of the present invention is a fixing device having the first or second technical feature, characterized in that the switching member switches the cooling member to a non-contact state under the condition that the medium is cooled to a predetermined temperature before the rear end of the medium in the conveying direction reaches the exit of the cooling area.

[0014] A fifth technical feature of the present invention is the fixing device having any one of the first to fourth technical features, wherein the switching member includes a moving mechanism that moves the cooling member relative to the transport fixing member.

[0015] The sixth technical feature of the present invention is a fixing device having the fifth technical feature, characterized in that the moving mechanism supports the cooling member so that it can swing with the end on the outlet side or the inlet side of the cooling area of ​​the cooling member as a swing point, and enables the cooling member to swing between a contact position with the conveying fixing member and a retreat position retreating from the conveying fixing member.

[0016] The seventh technical feature of the present invention is a fixing device having the fifth technical feature, characterized in that it comprises: a positioning member, which is arranged on the back side of the media conveying area of ​​the conveying fixing member, and when all or part of the cooling member retreats from the contact position with the back side of the conveying fixing member, the surface posture of the media conveying area of ​​the conveying fixing member is maintained.

[0017] An eighth technical feature of the present invention is the fixing device having any one of the first to fourth technical features, wherein the switching member includes a moving mechanism that moves the conveying fixing member relative to the cooling member.

[0018] The 9th technical feature of the present invention is a fixing device having the 8th technical feature, characterized in that the moving mechanism has an upward pushing member, which is arranged on the back side of the media conveying area of ​​the conveying fixing member except the cooling area, and pushes the media conveying area part of the conveying fixing member in a direction separating from the cooling member.

[0019] The tenth technical feature of the present invention is a fixing device having any one of the first to ninth technical features, characterized in that it comprises: an opposing rotating member, which is arranged opposite to the entrance of the cooling area of ​​the cooling member with the conveying fixing member sandwiched therebetween, and rotates following the conveying fixing member.

[0020] The 11th technical feature of the present invention is a fixing device having the 10th technical feature, characterized in that it comprises: a plurality of opposing rotating members, which are arranged opposite to each other with the conveying fixing member and the entrance of the cooling area of ​​the cooling member and a portion different from the entrance, and rotate following the conveying fixing member.

[0021] The twelfth technical feature of the present invention is a fixing device having the ninth technical feature, characterized in that it comprises: one or more opposing rotating members, which are arranged opposite to the entrance of the cooling area of ​​the cooling member across the conveying fixing member, or are arranged opposite to the entrance of the cooling area and a portion different from the entrance, and rotate following the conveying fixing member, and a part or all of the opposing rotating members move in conjunction with the pushing-up member.

[0022] The 13th technical feature of the present invention is a fixing device having any one of the 1st to 12th technical features, characterized in that the switching component has a position detection component for detecting the position of the front end or rear end in the conveying direction of the medium on the upstream side of the fixing area in the conveying direction of the medium, and the position of the front end or rear end in the conveying direction of the medium conveyed by the conveying fixing component is calculated based on the detection result of the position detection component, and the contact or non-contact state of the cooling component is switched.

[0023] The 14th technical feature of the present invention is a fixing device having the 13th technical feature, characterized in that when the position detection component detects the rear end position of the medium in the conveying direction, the switching component switches the cooling component to a non-contact state at the time when the rear end of the medium reaches the exit of the cooling area based on the detection result.

[0024] The 15th technical feature of the present invention is a fixing device having the 13th technical feature, characterized in that when the position detection component detects the front end position of the medium in the conveying direction, the switching component switches the cooling component to a contact state at a point before the front end of the medium reaches the entrance of the cooling area based on the detection result.

[0025] The 16th technical feature of the present invention is a fixing device having any one of the 1st to 15th technical features, characterized in that the switching component has a judging component for judging the distance between the rear end of the conveying direction of the preceding medium and the front end of the conveying direction of the subsequent medium, and under the condition that the distance judged by the judging component is less than the length of the cooling area, the contact / non-contact switching action of the cooling component is not performed.

[0026] The 17th technical feature of the present invention is an image forming system, characterized in that it comprises: an image generating component for producing an unfixed image on a medium; and a fixing device of any one of the 1st to 16th technical features for fixing the unfixed image retained on the medium.

[0027] Effects of the Invention

[0028] According to the first technical feature of the present invention, compared with the case where the belt-shaped conveying and fixing member is continuously cooled when the unfixed image on the medium is fixed by heating and cooling the conveying and fixing member, unnecessary cooling that does not contribute to cooling of the medium can be suppressed and fixing performance can be ensured.

[0029] According to the second technical feature of the present invention, when cooling of the medium is not required, the cooling operation of the transport fixing member by the cooling member can be omitted.

[0030] According to the third technical feature of the present invention, the cooling member can cool the transport fixing member while the medium passes through the cooling area of ​​the cooling member.

[0031] According to the fourth feature of the present invention, even when the medium has not completely passed through the cooling area of ​​the cooling member, if the temperature of the medium has been sufficiently cooled, the cooling operation of the transport fixing member by the cooling member can be omitted.

[0032] According to the fifth feature of the present invention, by moving the cooling member relative to the transport and fixing member, the contact and non-contact states of the cooling member can be easily switched.

[0033] According to the sixth aspect of the present invention, compared with the case where the entire cooling member is switched between contact and non-contact with respect to the transport fixing member, the cooling member can be switched between contact and non-contact with a simple configuration as the switching member.

[0034] According to the seventh aspect of the present invention, even when the cooling member is moved relative to the transport and fixing member, the surface posture of the medium conveying region of the transport and fixing member can be maintained.

[0035] According to the eighth aspect of the present invention, by moving the transport fixing member relative to the cooling member, the contact and non-contact states of the cooling member can be easily switched.

[0036] According to the ninth aspect of the present invention, the transport fixing member can be moved relative to the cooling member with a simple structure as the switching member.

[0037] According to the tenth feature of the present invention, compared with a case where no opposing rotating member is used, the medium conveyed on the conveying and fixing member can be brought into close contact with the cooling area of ​​the cooling member appropriately.

[0038] According to the eleventh feature of the present invention, compared with a case where one opposing rotating member is provided at the entrance of the cooling area of ​​the cooling member, the medium conveyed on the conveying and fixing member can be brought into close contact with the cooling area of ​​the cooling member appropriately.

[0039] According to the twelfth aspect of the present invention, even if the opposing rotating member is provided in the cooling region of the cooling member, the opposing rotating member does not become an obstacle and the fixing member can be pushed up and conveyed by the pushing-up member.

[0040] According to the thirteenth technical feature of the present invention, by utilizing the position detection means for detecting the conveying position of the medium, it is possible to easily grasp the switching timing of the state between the contact and non-contact state of the cooling means by the switching means.

[0041] According to the fourteenth aspect of the present invention, by utilizing the position detection member that detects the conveyance position of the medium, it is possible to easily realize the switching to the non-contact state of the cooling member.

[0042] According to the fifteenth feature of the present invention, by utilizing the position detection member for detecting the conveying position of the medium, it is possible to easily realize the switching to the contact state of the cooling member.

[0043] According to the sixteenth technical feature of the present invention, when the distance between the preceding medium and the succeeding medium is equal to or less than the length of the cooling region of the cooling member, the switching operation by the switching member can be omitted.

[0044] According to the 17th technical feature of the present invention, it is possible to construct an image forming system including a fixing device as follows, that is, compared with the case where the conveying fixing member is continuously cooled when the unfixed image on the medium is fixed by heating and cooling the belt-shaped conveying fixing member, it is possible to suppress unnecessary cooling that does not contribute to cooling of the medium and ensure fixing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0046] Figure 1 (a) is an explanatory diagram showing an overview of an embodiment of an image forming system incorporating a fixing device to which the present invention is applied, Figure 1 (b) means Figure 1 (a) is an explanatory diagram of a representative embodiment of a switching member, Figure 1 (c) means Figure 1 (a) is an explanatory diagram of another representative embodiment of a switching member;

[0047] Figure 2 is an explanatory diagram showing the overall configuration of an image forming system according to Embodiment 1;

[0048] Figure 3 is an explanatory diagram showing a main part of the second fixing device involved in the first embodiment;

[0049] Figure 4 (a) is an explanatory diagram showing a dedicated paper for photographic images as an example of a medium, Figure 4 (b) is an explanatory diagram showing a state where a toner image is fixed on a dedicated medium. Figure 4 (c) is an explanatory diagram showing a state where a toner image is fixed on ordinary paper as an example of a medium;

[0050] Figure 5 It is the main part of the contact or separation mechanism used in embodiment 1, Figure 5 (a) is an explanatory diagram showing a state in which the cooler is arranged at a contact position with respect to the conveying fixing belt, Figure 5 (b) is an explanatory diagram showing a state in which the cooler is arranged in a non-contact position relative to the conveying fixing belt;

[0051] Figure 6 is an explanatory diagram showing a control system for the second fixing device and its peripheral parts according to the first embodiment;

[0052] Figure 7 is a flow chart showing a contact or separation process of a cooler used in Embodiment 1;

[0053] Figure 8 (a) is an explanatory diagram showing the configuration state of the cooler just before the medium enters the cooling area of ​​the second fixing device, Figure 8 (b) is an explanatory diagram showing the configuration state of the cooler just after the medium passes through the cooling area of ​​the second fixing device;

[0054] Fig. 9 (a) schematically shows that a plurality of media maintain a predetermined page interval L. PG An illustration of the state of being transferred to the second fixing device, Fig. 9 (b) indicates L PG >L CA (length of the cooling area of ​​the second fixing device along the medium conveying direction) is an explanatory diagram of an example of contact or separation operation of the cooler, Fig. 9 (c) indicates L PG ≤L CA An explanatory diagram of an example of contact or separation action of a cooler when

[0055] Fig.10 is an explanatory diagram showing a main part of the second fixing device involved in the modification mode 1;

[0056] Fig.11 (a) is an explanatory diagram showing the action of the positioning roller in deformation mode 1, Fig.11 (b) is an explanatory diagram showing the secondary problem when the positioning roller is not used;

[0057] Fig.12 is an explanatory diagram showing a main part of a second fixing device according to a second embodiment;

[0058] Fig.13 It is the main part of the contact or separation mechanism used in embodiment 2, Fig.13 (a) is an explanatory diagram showing a state in which the conveying fixing belt is arranged at a contact position relative to the cooler, Fig.13 (b) is an explanatory diagram showing a state in which the conveying fixing belt is arranged in a non-contact position relative to the cooler;

[0059] Fig.14 (a) is an explanatory diagram showing the configuration state of the conveying fixing belt just before the medium enters the cooling area of ​​the second fixing device, Fig.14 (b) is an explanatory diagram showing the configuration state of the conveying fixing belt just after the medium passes through the cooling area of ​​the second fixing device;

[0060] Fig.15is an explanatory diagram showing a main part of a second fixing device according to a third embodiment;

[0061] Fig.16 is a flow chart showing the contact or separation process of the cooler used in Embodiment 3;

[0062] Fig.17 (a) is an explanatory diagram showing a state where the temperature of the back side of the medium is measured by the temperature sensor when the leading end of the medium passes through the cooling area of ​​the second fixing device (D). Fig.17 (b) is an explanatory diagram showing an example of the cooler retreat operation performed under the condition that the temperature Td measured by the temperature sensor is equal to or lower than the predetermined allowable temperature Tth. Fig.17 (c) is an explanatory diagram showing an example of the cooler retreat operation performed under the condition of Td>Tth. DETAILED DESCRIPTION

[0063] ◎Overview of implementation method

[0064] Figure 1 (a) shows an outline of an embodiment of an image forming system including a fixing device to which the present invention is applied.

[0065] Here, the unfixed image refers to an image that is not completely fixed on the medium S, including an image that has not passed through the fixing device 10 before passing through the fixing device and an image that is not completely fixed on the medium S due to passing through the fixing device with a low fixing temperature (temporarily fixed). For example, temporarily fixed refers to a state in which the toner image is not embedded in the image receiving layer of the medium S, including a case in which the toner image is embedded in the image receiving layer of the medium S by reheating.

[0066] In this figure, the image forming system includes an image generating unit 11 for forming an unfixed image G on a medium S, and a fixing device 10 for fixing the unfixed image G held on the medium S.

[0067] Furthermore, the fixing device 10 is a fixing device that heats and pressurizes a medium S holding an unfixed image G and then cools the medium S to fix the unfixed image G, and comprises: a heating fixing member 1 having a heating source 1a; a belt-shaped conveying fixing member 2 that is arranged to be stretched on the heat fixing member 1 and capable of circulation, and that contacts the image surface of the medium S to convey the medium S; a pressurizing fixing member 3 that is arranged opposite to the heating fixing member 1 with the conveying fixing member 2 interposed therebetween, and that pressurizes in a manner that forms a fixing area FA between the conveying fixing member 2 and the heating fixing member 1; a cooling member 4 that is arranged on the downstream side of the conveying direction of the medium S in the conveying fixing member 2 in contact with the back side of the medium conveying area of ​​the conveying fixing member 2, and cools the conveying fixing member 2; and a switching member 5 that switches the conveying fixing member 2 and the cooling member 4 to a contact or non-contact state according to the passing state of the medium S in the cooling area CA of the cooling member 4.

[0068] In this technical means, the fixing device 10 of this embodiment can be assembled in an image forming device including an image generating component 11 for producing an unfixed image G, or can be constructed as an image forming system assembled in a post-processing device different from the image forming device and composed of a plurality of units.

[0069] Furthermore, the heating fixing member 1 includes, for example, a heating fixing roller. The heating source 1a may be internal or external. Furthermore, the transport fixing member 2 includes a fixing belt. In this example, in order to obtain a high-gloss image such as a photographic image, the fixing belt is preferably formed with a highly smooth coating layer such as fluororubber or silicone rubber on the surface of an endless film made of a thermosetting polyimide resin. Furthermore, the pressurizing fixing member 3 may be in a roller or belt shape as long as it is pressurized in a manner to form a fixing area FA between the fixing member 1 and the heating fixing member 1.

[0070] The cooling member 4 includes a wide range of members as long as it contacts with the back side of the medium conveying area of ​​the conveying and fixing member 2 to cool the medium. A heat dissipation member such as a radiator is mainly used to dissipate the absorbed heat. In addition, the switching member 5 only needs to use the passing state of the medium S in the cooling area CA of the cooling member 4 as a judgment reference when switching the cooling member 4 to the contact state or the non-contact state with respect to the conveying and fixing member 2.

[0071] Next, a typical embodiment or a preferred embodiment of the fixing device according to the present embodiment will be described.

[0072] First, as a representative mode of the switching member 5, there can be cited a mode in which the transporting and fixing member 2 and the cooling member 4 are switched to a non-contact state during a period when the medium S does not pass through the cooling area CA by the cooling member 4 in the transporting and fixing member 2. This takes into account that the cooling of the medium S is not performed in the entire area of ​​the medium transporting area of ​​the transporting and fixing member 2 but in the cooling area CA by the cooling member 4. That is, during a period when the medium S does not pass through the cooling area CA, there is no need to cool the medium S, so even if the cooling operation of the transporting and fixing member 2 by the cooling member 4 is omitted during this period, the cooling process of the medium S will not be affected at all.

[0073] Therefore, as a method of switching the member 5, there can be cited a method of switching the cooling member 4 to a contact state before the front end of the medium S in the conveying direction reaches the entrance (upstream starting point) of the cooling area CA, and switching the cooling member 4 to a non-contact state when the rear end of the medium S in the conveying direction reaches the exit (downstream end point) of the cooling area CA. In this example, it is assumed that the cooling member 4 performs a cooling operation on the conveying fixing member 2 while the medium S passes through the cooling area CA of the cooling member 4.

[0074] Furthermore, the cooling effect on the medium S depends on the characteristic information (thickness, thermal conductivity, etc.) of the medium S. Therefore, the medium S may be cooled to a predetermined temperature (allowable cooling temperature) before completely passing through the cooling area CA by the cooling member 4 .

[0075] As a method of the switching member 5 suitable for this case, there can be cited a method of switching the cooling member 4 to a non-contact state under the condition that the medium S is cooled to a predetermined temperature before the rear end of the medium S in the conveying direction reaches the exit of the cooling area CA. In this example, it is necessary to determine whether the medium S passing through the cooling area CA is sufficiently cooled midway. In this case, a temperature detection member (not shown) that measures the temperature of the medium S (for example, the temperature of the back of the medium S that is non-contact with the conveying fixing member 2) midway in the conveying direction of the medium S in the cooling area CA can be used. Moreover, it is determined based on the detection signal of the temperature detection member whether the temperature of the medium S has reached the allowable cooling temperature, and the state switching of the cooling member 4 based on the switching member 5 can be performed.

[0076] In addition, as a representative structural example of the switching member 5, there is a mode in which a moving mechanism is provided to move the cooling member 4 relative to the transport fixing member 2. The moving mechanism also includes a mode in which the cooling member 4 is moved to a non-contact position with respect to the transport fixing member 2 while maintaining a partial contact state, or the cooling member 4 is moved entirely to a non-contact position.

[0077] Here, as a means of moving the mechanism, e.g. Figure 1As shown in (b), the cooling member 4 is supported so as to be able to swing with the end of the outlet side or the inlet side of the cooling area CA of the cooling member 4 as a swing point, and the cooling member 4 is swung between a contact position in contact with the conveying fixing member 2 and a retreat position retreated from the conveying fixing member 2. Compared with the method of switching between contact and non-contact by linearly moving the entire cooling member 4 relative to the conveying fixing member 2, this example is preferred from the viewpoint of being able to stabilize the switching operation with a simple structure.

[0078] Furthermore, when the cooling member 4 is retracted from the transport fixing member 2 to the retracted position, a gap is generated between the transport fixing member 2 and the cooling member 4, so that a part of the medium transport area of ​​the transport fixing member 2 may sink in the retracting direction. From the viewpoint of effectively solving this type of secondary problem, for example, Figure 1 As shown in (b), it is preferred to provide a positioning member 8 on the back side of the medium conveying region of the conveying fixing member 2. The positioning member 8 only needs to be arranged so as to maintain the surface posture of the medium conveying region of the conveying fixing member 2 when all or part of the cooling member 4 is withdrawn from the contact position with the back side of the conveying fixing member 2.

[0079] Furthermore, as another representative structural example of the switching member 5, Figure 1 As shown in (c), there is a method of having a moving mechanism that moves the conveying fixing member 2 relative to the cooling member 4. The moving mechanism can move the entire conveying fixing member 2 to a non-contact state relative to the cooling member 4, but from the viewpoint of maintaining the trajectory of the exit or entrance of the medium conveying area of ​​the conveying fixing member 2, for example, it is preferable to maintain a part of the conveying fixing member 2 in a contact state and move the remaining part to a non-contact state.

[0080] As a method of this type of moving mechanism, a push-up member 9 is set on the back side of the media conveying area of ​​the conveying fixing member 2 except for the cooling area CA, and the media conveying area part of the conveying fixing member 2 is pushed in the direction of separating from the cooling member 4 by the push-up member 9.

[0081] In this example, the push-up member 9 may or may not be in contact with the transport fixing member 2 before being pushed up. In addition, in the mode where the push-up member 9 is in contact with the transport fixing member 2 before being pushed up, the push-up member 9 and the positioning member 8 described above can also be used together.

[0082] Furthermore, from the viewpoint of ensuring the cooling effect by the cooling member 4 , for example, the medium S conveyed by the conveying and fixing member 2 is preferably arranged in close contact with the cooling area CA of the cooling member 4 .

[0083] From this point of view, for example, Figure 1 As shown in (a) to (c) of FIG. 1 , it is preferable to include an opposing rotating member 6 (specifically 6a) disposed opposite to the entrance of the cooling area CA of the cooling member 4 with the transport fixing member 2 interposed therebetween and rotating in accordance with the transport fixing member 2.

[0084] As a more preferred embodiment, for example, Figure 1 As shown in (a) to (c), there can be cited a method in which an entrance of a cooling area CA having an entrance separated from a conveying fixing member 2 and a cooling member 4 and a portion different from the entrance (an exit in this example) are arranged opposite to each other, and a plurality of opposing rotating members 6 (specifically 6a, 6b) that rotate following the conveying fixing member 2 can be cited.

[0085] Furthermore, in the case where the moving mechanism of the switching member 5 includes the push-up member 9, for example, Figure 1 As shown by the imaginary lines in (c), it is preferred that a part or all of the opposed rotating members 6 (6a, 6b) moves in conjunction with the push-up member 9. This example is effective in that the conveying fixing member 2 relative to the cooling member 4 is set to a non-contact state with the push-up member 9.

[0086] Furthermore, from the viewpoint of appropriately grasping the switching timing by the switching means 5, as the switching means 5, for example, Figure 1 As shown in (a), it is preferably the following method, that is, there is a position detection component 7 for detecting the position of the front end or rear end in the conveying direction of the medium S on the upstream side of the conveying direction of the medium S closer to the fixing area FA, the position of the front end or rear end in the conveying direction of the medium S conveyed by the conveying fixing component 2 is calculated based on the detection result of the position detection component 7, and the contact or non-contact state of the cooling component 4 is switched.

[0087] In this example, when the position detection member 7 detects the rear end position of the medium S in the conveying direction, the switching member 5 switches the cooling member 4 to a non-contact state when the rear end of the medium S reaches the exit of the cooling area CA based on the detection result.

[0088] When the position detection member 7 detects the front end position of the medium S in the conveying direction, the switching member 5 switches the cooling member 4 to the contact state at a time point before the front end of the medium S reaches the entrance of the cooling area CA based on the detection result.

[0089] Furthermore, the switching operation of the switching member 5 is performed according to the conveying position of the medium S, but when the distance between the plurality of media S (the distance between the rear end of the preceding medium S and the front end of the succeeding medium S) is short, there is a possibility that the cooling of the media S becomes insufficient. From this point of view, as a mode of the switching member 5, there is a mode in which a determination member (not shown) is provided for determining the distance between the rear end of the preceding medium in the conveying direction and the front end of the succeeding medium in the conveying direction, and the contact / non-contact switching operation of the cooling member 4 is not performed under the condition that the distance determined by the determination member is less than the length of the cooling area CA.

[0090] Hereinafter, the present invention will be described in more detail based on the embodiments shown in the drawings.

[0091] ◎Implementation method 1

[0092] Figure 2 The overall configuration of the image forming system according to the first embodiment is shown.

[0093] -Overall structure of image forming system-

[0094] In the figure, the image forming system 15 has an apparatus body 16 having an image forming unit capable of forming a color image, and a post-processing device 50 is additionally installed on the upper part of the apparatus body 16 as an optional device. On the other hand, a multi-stage media supply container 81 (81a, 81b) for supplying media such as paper can be pulled out and accommodated below the apparatus body 16.

[0095] -Image forming unit-

[0096] The image forming unit used in the present embodiment adopts, for example, an electrophotographic method, and has a so-called tandem type structure in which the image forming units 20 (20a to 20d) of four colors, namely, yellow (Y color), magenta (M color), cyan (C color), and black (K color), are arranged in a row with respect to the belt-shaped intermediate transfer body 30. Therefore, the toner images of the respective colors formed by the image forming units 20 (20a to 20d) are sequentially transferred once on the intermediate transfer body 30, for example, to be multiplexed, and the multiplexed toner images are collectively transferred to the medium conveyed from the medium supply container 81 and fixed. In addition, the color arrangement of the image forming units 20 of the four colors is not limited to this order, and may be in another order.

[0097] The image forming unit 20 (20a to 20d) in this embodiment is composed of a photoreceptor 21 as an image holding body for holding the toner images of the respective color components after forming them, a charging device 22 such as a charging roller for charging the photoreceptor 21, an exposure device 23 such as a laser scanner for forming a latent image on the charged photoreceptor 21, a developing device 24 for visualizing the electrostatic latent image on the photoreceptor 21, a primary transfer device 25 such as a primary transfer roller for primary transfer of the toner image on the photoreceptor 21 to the intermediate transfer body 30, a photoreceptor cleaner 26 for cleaning the residual toner remaining on the photoreceptor 21, and a static eliminator 27 for eliminating the residual charge on the photoreceptor 21. In addition, the exposure device 23 in this embodiment performs exposure of the entire image forming unit 20 (20a to 20d) of four colors by each exposure device of the image forming unit 20.

[0098] The intermediate transfer body 30 is stretched by a plurality of tension rollers. For example, the tension roller 31 is used as a driving roller to circulate the intermediate transfer body 30, and the tension roller 32 is used as a supporting roller of a secondary transfer device 33 composed of a secondary transfer roller. An intermediate transfer body cleaner 34 is provided at a position facing the tension roller 31 of the intermediate transfer body 30 to remove residual toner on the intermediate transfer body 30.

[0099] Furthermore, in the apparatus body 16 , four color toner cartridges 35 for supplying toner corresponding to the developers 24 of the image forming units 20 are provided above the intermediate transfer body 30 , and toner is supplied to the developers 24 corresponding to the respective colors via a transport path (not shown).

[0100] In addition, the media conveying system 80 in this embodiment is as follows. The media fed from each media supply container 81 by the pickup roller 82 is separated by the action of the feed roller 83 and the retard roller 84, so that only one piece of media is conveyed to the conveying path on the downstream side. In addition, the conveying path is provided with an integration roller 85 for positioning and integrating the media fed from the media supply container 81 before entering the secondary transfer device 33, and a first fixing device 40 for fixing the unfixed toner image transferred to the media by the secondary transfer device 33. In addition, a switching member 86 is provided on the downstream side of the first fixing device 40, and by switching the switching member 86, the media discharged from the first fixing device 40 is switched to the path of two directions, the post-processing device 50 side and the first discharge receiving portion 87 side that accommodates the media directly discharged from the device body 16.

[0101] In addition, as the media supply container 81, two media supply containers 81a and 81b for accommodating media of different sizes are shown, but the present invention is not limited thereto, and three or more media supply containers may be provided, or one media supply container may be provided. In addition, a manual feeder (not shown) may be provided, and the media may be guided to the conveying path from the manual feeder.

[0102] The first fixing device 40 of the present embodiment is as follows, for example. The first fixing device 40 includes a heating fixing roller 41 having a heat source (not shown) such as a halogen lamp inside, and a pressure fixing roller 42 arranged opposite to the heating fixing roller 41 and sandwiching and conveying the medium in a fixing area formed between the heating fixing roller 41.

[0103] Therefore, if the medium holding the unfixed toner image passes through the fixing area of ​​the first fixing device 40, the unfixed toner image on the medium is fixed to the medium due to heat and pressure. In addition, in the present embodiment, the medium holding the unfixed toner image that has passed through the first fixing device 40 is not completely fixed to the medium due to heat and pressure, but the fixing operation is completed by the heated fixing rollers 61 and 63 of the second fixing device 60 described later.

[0104] In addition, in this example, the first fixing device 40 adopts a roller pair structure of a heating and pressurizing method, but it is not limited to this. It is also possible to appropriately select a pressure pad to be arranged opposite to the heating fixing roller, insert a pressure belt linked to the heating fixing roller between the heating fixing roller and the pressure pad, and clamp the medium in the fixing area formed between the heating fixing roller and the pressure belt and heat and pressurize it for fixing.

[0105] - Example of the structure of the post-processing device -

[0106] Moreover, if Figure 2 As shown in FIG. 1 , the post-processing device 50 of the present embodiment includes a second fixing device 60 which is provided in the middle of the medium conveying path 51 and makes the toner image surface of the medium bright, and a cutting device 70 which cuts the medium which has passed through the second fixing device 60. In addition, in the present embodiment, a second discharge receiving portion 88 is provided on the downstream side of the post-processing device 50 and receives the medium which has passed through the cutting device 70.

[0107] -Basic structure of the second fixing unit-

[0108] The second fixing device 60 includes Figure 1 The fixing device 10 shown in (a) has the same basic structure.

[0109] That is, Figure 2 and Figure 3As shown, the second fixing device 60 includes: a heating fixing roller 61 as a heating fixing member; a conveying fixing belt 62 as a conveying fixing member, which is arranged to be stretched on the heating fixing roller 61 and can circulate, and is in contact with the image surface of the medium S to convey the medium S; a pressurizing fixing roller 63 as a pressurizing fixing member, which is arranged opposite to the heating fixing roller 61 with the conveying fixing belt 62 in between, and pressurizes in a manner of forming a fixing area FA between the heating fixing roller and the heating fixing roller; and a cooler 64 as a cooling member, which is arranged on the downstream side of the conveying direction of the medium S in the conveying fixing belt 62 in contact with the back side of the medium conveying area SA of the conveying fixing belt 62, and cools the conveying fixing belt 62.

[0110] <Heated fixing roller>

[0111] The heating fixing roller 61 has a structure in which a non-sticking layer (not shown) made of a PFA tube or the like is formed around a core portion 61a made of metal with high thermal conductivity. A heating source 65 such as a halogen lamp is provided inside the core portion 61a, and heating control is performed in such a manner that the surface of the fixing roller 61 is heated to a predetermined temperature by the heating source 65. In this embodiment, the heating fixing roller 61 is driven by a drive motor 69 (see Figure 6 ) is driven to rotate, and the conveying fixing belt 62 is circulated and rotated through the heating fixing roller 61.

[0112] <Transfer fixing belt>

[0113] The conveyor fixing belt 62 is an endless film made of thermosetting polyimide resin, for example, and a coating layer of fluororubber or silicone rubber with high smoothness is formed on the surface. The conveyor fixing belt 62 is stretched between the heating fixing roller 61, the peeling roller 67 and the steering roller 68, and can be circulated by the rotation of the heating fixing roller 61.

[0114] Here, the peeling roller 67 rotates following the movement of the conveyor fixing belt 62, and the peeling roller 67 wraps around the conveyor fixing belt 62 while tensioning it, thereby causing the moving direction of the conveyor fixing belt 62 to change suddenly. Therefore, the medium S on the conveyor fixing belt 62 is naturally peeled off from the conveyor fixing belt 62 at the position of the peeling roller 67 due to the rigidity of the medium S itself. In addition, the steering roller 68 always keeps the tension of the conveyor fixing belt 62 itself. The steering roller 68 maintains the tension of the conveyor fixing belt 62 by pushing the conveyor fixing belt 62 outward, and corrects the deviation (the phenomenon that the conveyor fixing belt 62 moves toward one end of the steering roller 68) generated when the conveyor fixing belt 62 circulates.

[0115] In order to maintain mechanical strength and effectively utilize thermal energy, appropriate thicknesses are selected for the base and cover layer of the conveying fixing belt 62. For example, a base material having a thickness of about 75 μm and a cover layer having a thickness of about 35 μm may be used.

[0116] <Pressure fixing roller>

[0117] On the other hand, the pressure fixing roller 63 is coated with an elastic layer 63b such as silicone rubber around a core 63a made of metal with high thermal conductivity, and a release layer (not shown) similar to the release layer of the heating fixing roller 61 is formed on the surface of the elastic layer 63b. In addition, in the present embodiment, a heating source 66 such as a halogen lamp is also provided inside the core 63a of the pressure fixing roller 63, and heating control is performed so that the surface of the pressure fixing roller 63 reaches a predetermined temperature. Therefore, the medium S conveyed to the second fixing device 60 is heated and pressurized in a state where the toner image surface is in contact with the conveying fixing belt 62 in the fixing area FA of the heating fixing roller 61 and the pressure fixing roller 63.

[0118] <Cooler>

[0119] In the present embodiment, the cooler 64 is provided between the heating fixing roller 61 and the peeling roller 67 (corresponding to the medium conveying area SA) so as to be in contact with the back surface of the conveying fixing belt 62. The cooler 64 is in contact with a part of the medium conveying area SA of the conveying fixing belt 62, and the contact area is set as the cooling area CA. That is, the cooler 64 absorbs the heat of the conveying fixing belt 62 through the cooling area CA, thereby cooling the conveying fixing belt 62. Therefore, the medium S conveyed in close contact with the conveying fixing belt 62 is cooled.

[0120] The cooler 64 in this embodiment is equivalent to a so-called radiator. The cooler 64 is composed of a sheet member 64a provided with a plurality of radiating fins extending in a direction substantially orthogonal to the surface along which the fixing belt 62 is conveyed, and a cover 64b having a rectangular cross-section cylindrical shape provided to cover the fins. The cooler 64 is configured such that air is circulated inside by an air blower (not shown) to forcibly dissipate the heat of the sheet member 64a.

[0121] In the cooler 64, for example, a temperature sensor 641 (see Figure 6 ), and according to the detection result of the temperature sensor 641, adjust the switch or air volume of the air supply blower not shown.

[0122] <Structure around the second fixing unit>

[0123] In this example, an entrance guide member 52 for guiding the medium S to the entrance of the second fixer 60 is provided near the entrance of the second fixer 60 , and a position sensor 53 for detecting the position of the front end or rear end of the medium S passing through the conveying path 51 is provided.

[0124] Furthermore, an exit guide member 54 for guiding the medium S discharged from the exit of the second fixing device 60 is provided near the exit of the second fixing device 60 , and a conveying roller 55 is provided on the downstream side of the exit guide member.

[0125] <Selection of Media>

[0126] Generally, in order to obtain a high gloss image such as a photographic image, for example, it is preferable to use a medium S such as Figure 4 As shown in FIG. 1 , the dedicated paper has a moisture-proof layer L2 on both sides of a base layer L1 and an image receiving layer L3 on the recording surface (toner image forming surface).

[0127] The moisture-proof layer L2 is made of a resin with no air permeability, such as polyethylene, and can obtain the moisture-proof effect of the base layer L1 as long as the thickness is about several μm. In addition, the image receiving layer L3 is mainly composed of a thermoplastic resin such as polyester with a melting temperature of about 130°C, and has a layer thickness of 5 to 20 μm, preferably a layer thickness of about 10 μm. On the other hand, the base layer L1 is composed mainly of cellulose, which is the same composition as ordinary paper, but for example, a dedicated base layer L1 with a different composition can also be used.

[0128] Therefore, as in the printing paper used in silver halide photography, a moisture-proof layer L2 is provided on both sides of the base layer L1, and an image receiving layer L3 made of the same material as the toner is further provided, thereby eliminating air permeability, thereby preventing the base layer L1 from absorbing moisture and stretching to cause curling or the toner image from being stretched and broken in a high humidity environment. In addition, the toner image is melted together with the image receiving layer L3 through the image receiving layer L3, and the toner image is well embedded in the image receiving layer L3 by applying pressure, thereby obtaining a smooth printing surface.

[0129] If this special paper is used for fixing by the second fixing device 60 in the photo printing mode, Figure 4 As shown in (b), the toner image is embedded in the image receiving layer L3. At this time, the surface properties of the conveying fixing belt 62 of the second fixing device 60 are transferred, and the surface of the image receiving layer L3 and the surface of the toner image become roughly uniform, so that a glossy image can be obtained. On the other hand, Figure 4 (c) shows the state in which the toner image is fixed on the ordinary paper as the medium S only by the first fixer 40 in the ordinary paper printing mode. At this time, the toner image is carried on the base layer L1, and the image surface can only obtain an image with poor glossiness due to the protrusion of the toner image.

[0130] -Characteristic structure of the second fixing device-

[0131] <Necessity of contact or separation mechanism>

[0132] In the present embodiment, the second fixing device 60 includes a contact or separation mechanism 100 as a switching member for switching the cooler 64 to a contact state or a non-contact state with respect to the conveying fixing belt 62 .

[0133] Here, assuming that the contact or separation mechanism 100 is not provided, the cooler 64 is always in contact with the back side of the conveying fixing belt 62. At this time, the medium S that has passed through the fixing area FA between the heating fixing roller 61 and the pressure fixing roller 63 moves in close contact with the conveying fixing belt 62, and is cooled only during the period when the medium S passes through the cooling area CA in contact with the cooler 64 in the medium conveying area SA of the conveying fixing belt 62. Therefore, if the cooler 64 performs a cooling operation when the medium S does not pass through the cooling area CA, the medium S is not cooled but the conveying fixing belt 62 is cooled exclusively. As a result, the temperature of the conveying fixing belt 62 is unnecessarily lowered, and when the conveying fixing belt 62 is heated again by the heating fixing roller 61, more power is required for heating. That is, the power required for the cooling operation of the conveying fixing belt 62 alone, which does not contribute to the cooling of the medium S, is wasted.

[0134] In this example, while the medium S is not passing through the cooling area CA of the transport fixing belt 62 by the cooler 64 , the transport fixing belt 62 and the cooler 64 are switched to a non-contact state to reduce waste of electric power.

[0135] <Contact or separation mechanism configuration example>

[0136] In this example, if Figure 5 As shown in (a) and (b), the contact or separation mechanism 100 calculates the period during which the medium S does not pass through the cooling area CA according to the passing state of the medium S in the cooling area CA of the cooler 64, and moves the cooler 64 from the contact position to the retracted position.

[0137] First, the contact or separation mechanism 100 has a swing shaft 101 at the end portion on the outlet (downstream end point B) side of the cooling area CA of the cooler 64, and supports the cooler 64 so as to be swingable with the swing shaft 101 as a swing point. The contact or separation mechanism 100 swings the cooler 64 between a contact position in contact with the conveying fixing belt 62 and a retreat position in a direction away from the conveying fixing belt 62.

[0138] like Figure 5As shown in (a) and (b) of FIG. 1 , the contact or separation mechanism 100 is provided with a variable mechanism 102 that changes the end position of the inlet (upstream starting point A) side of the cooling area CA of the cooler 64 in the swing rotation direction. In this example, the variable mechanism 102 includes an eccentric cam 104 rotated by a drive motor 103, cam followers 105 rotatably provided on both sides in the width direction of the inlet side of the cooling area CA of the cooler 64 and abutting against the cam surface of the eccentric cam 104, and a push spring 106 as a biasing member provided at a corner portion on the rotation free end side located on a diagonal line relative to the swing shaft 101 in the cooler 64 and biasing the cooler 64 toward the conveying fixing belt 62 side.

[0139] According to the contact or separation mechanism 100 of this embodiment, when the cooler 64 is provided at the contact position with the conveying fixing belt 62, as shown in FIG. Figure 5 As shown in (a), for example, the eccentric cam 104 is rotated counterclockwise by driving the motor 103, and the small diameter portion r1 of the eccentric cam 104 is brought into contact with the cam follower 105 by the force of the push spring 106. Then, the cooler 64 is swung toward the conveying fixing belt 62 side with the swing shaft 101 as the swing point, and is arranged at a predetermined contact position.

[0140] On the other hand, when the cooler 64 is retracted to the retracted position, as shown in FIG. Figure 5 As shown in (b), the eccentric cam 104 is rotated in the clockwise direction by driving the motor 103, and the large diameter portion r2 of the eccentric cam 104 is brought into contact with the cam follower 105 by overcoming the force of the push spring 106. Then, the cooler 64 is swung in the direction of separating from the conveying fixing belt 62 with the swing shaft 101 as the swing point, and is arranged in a predetermined retreat position.

[0141] <Close contact transmission of media>

[0142] In this embodiment, from the viewpoint of ensuring the cooling effect by the cooler 64, Figure 3 As shown, the medium S conveyed by the conveying and fixing belt 62 is designed to be arranged in close contact with the cooling area CA of the cooler 64 .

[0143] In this example, an inlet side opposing roller 131 as an opposing rotating member is provided on the surface side of the conveying fixing belt 62 at a position corresponding to the inlet (upstream starting point A) of the cooling area CA of the cooler 64. The inlet side opposing roller 131 is arranged in contact with the conveying fixing belt 62 and rotates following the conveying fixing belt 62.

[0144] Furthermore, an outlet side opposing roller 132 as an opposing rotating member is provided on the surface side of the conveying fixing belt 62 at a position corresponding to the outlet (downstream end point B) of the cooling area CA of the cooler 64. The outlet side opposing roller 132 is arranged in contact with the conveying fixing belt 62 and rotates following the conveying fixing belt 62.

[0145] In this example, the entrance side opposing roller 131 needs to be provided at a position corresponding to the entrance of the cooling area CA. Thus, the medium S conveyed on the conveyor fixing belt 62 is pulled in close contact with the conveyor fixing belt 62 by the entrance side opposing roller 131 at the entrance of the cooling area CA.

[0146] On the other hand, the outlet-side opposing roller 132 is effective in bringing the medium S into close contact with the conveying fixing belt 62 at two locations before and after the conveying direction of the medium S together with the inlet-side opposing roller 131. However, the outlet-side opposing roller 132 is provided at a location corresponding to the outlet of the cooling area CA, but is not limited thereto, and may be provided at a location further upstream than the outlet of the cooling area CA.

[0147] -Control system of the second fixing unit-

[0148] In this example, if Figure 6 As shown, the control system of the second fixing device 60 has a control device 150 composed of a microcomputer including various processors. The "processor" mentioned here refers to a processor in a broad sense, including a general-purpose processor (such as CPU: Central Processing Unit, Central Processing Unit, etc.) or a dedicated processor (such as GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, Field Programmable Gate Array, Programmable Logic Device, etc.).

[0149] In addition, an operation panel 151 of the image forming system 15 is connected to the control device 150. The operation panel 151 is provided with a start switch for starting the image generation process for the medium S; a mode switch for specifying an image generation mode such as single-sided printing, double-sided printing, high-definition printing, etc.; a media type indication portion for indicating the type of media to be used, etc.

[0150] In addition, a program related to the contact or separation process of the cooler 64 is preinstalled in the ROM as a storage device of the control device 150 (for example, refer to Figure 7). In addition, various detectors such as the position sensor 53 and the temperature sensor 641 are connected to the control device 150. In addition, various control objects (such as the drive motor 69, the heat sources 65, 66, the drive motor 103 of the contact or separation mechanism 100, etc.) are connected to the control device 150.

[0151] Then, the processor of the control device 150 receives instruction signals from the operation panel 151 and detection signals from various detectors, executes the aforementioned program, and sends appropriate control signals to each controlled object.

[0152] -Cutting device-

[0153] In this embodiment, the cutting device 70 can cut the edges of the media, for example to produce borderless printing. Figure 2 As shown, the cutting device 70 includes a paper cutter 71 for cutting the width direction of the medium, a plurality of circular cutters 72 (72a, 72b) for cutting the length of the medium in the conveying direction, and a plurality of conveying rollers 73, 74 for conveying the medium. The paper cutter 71 has a number of blades in the axial direction that matches the required number of cuts, and cuts in the conveying direction while conveying the medium. In addition, the circular cutter 72 performs cutting by temporarily stopping the conveying of the medium and moving the roller of the upper blade along the lower blade. In addition, as the circular cutter 72, for example, a roller blade may be provided in the axial direction, and cutting may be performed while conveying the medium.

[0154] Furthermore, the cutting device 70 not only has the function of cutting the medium into a plurality of sheets (e.g., four sheets), but can also print an L-sized image on a postcard-sized medium (100×150 mm) and complete the borderless printing by the cutting device 70. Furthermore, it is possible to obtain an arbitrary number of L-sized digital camera photos by combining printing four images on an A4-sized medium and printing one image each on an arbitrary number of postcard-sized media. In addition, by making the width direction position of the blade of the paper cutter 71 variable, it is also possible to cut into various sizes such as 4-fold, 6-fold, and 8-fold.

[0155] -Basic operation of image forming system-

[0156] Next, the basic operation of this image forming system will be described.

[0157] like Figure 2As shown in FIG. 1 , the multiple toner images formed on the intermediate transfer body 30 based on the multiplexing of the color toner images of the image forming units 20 (20a to 20d) are collectively transferred to the medium fed from the medium supply container 81 by the secondary transfer device 33. The transferred unfixed toner images are fixed by the first fixing device 40 and then guided to the first discharge receiving portion 87 by the switching member 86 or guided to the second discharge receiving portion 88 via the post-processing device 50.

[0158] In the present embodiment, the switching of the medium conveying direction by the switching member 86 is performed as follows. That is, in the plain paper printing mode (low gloss printing) for forming a normal image, after being fixed by the first fixing device 40, the medium is discharged to the first discharge receiving portion 87 by the switching member 86. On the other hand, in the photo printing mode (high gloss printing) for forming a high gloss image such as a photo image, after being fixed by the first fixing device 40, the medium is conveyed to the second fixing device 60 side by the switching member 86, and after being further fixed by the second fixing device 60, the medium is discharged to the second discharge receiving portion 88 via the cutting device 70. In particular, the cutting device 70 can be used when borderless printing such as a photo image is preferred, and in particular, when cutting is not required, the medium can be discharged to the second discharge receiving portion 88 without cutting.

[0159] Generally, in order to obtain a high-gloss image such as a photographic image, it is preferable to use, as the medium S, for example Figure 4 Special paper as shown in (a).

[0160] If this special paper is used for fixing by the second fixing device 60 in the photo printing mode, Figure 4 As shown in (b), the toner image is embedded in the image receiving layer L3. At this time, the surface properties of the conveying fixing belt 62 of the second fixing device 60 are transferred, and the surface of the image receiving layer L3 and the toner image surface become substantially uniform, thereby obtaining a glossy image.

[0161] -Fixing action by the second fixing device-

[0162] The fixing action by the second fixing device 60 is performed as follows.

[0163] like Figure 3 As shown, the medium S guided to the post-processing device 50 via the first fixing device 40 is about to enter the second fixing device 60. In this state, in the second fixing device 60, the heating fixing roller 61 and the pressure fixing roller 63 are heated to a temperature capable of fixing by the heating sources 65 and 66, respectively, and the conveying fixing belt 62 is in a state of circulating rotation accompanying the driving rotation of the heating fixing roller 61.

[0164] The cooler 64 is provided at a contact position on the back side of the conveying fixing belt 62 under the condition that the leading end of the medium S passes through a predetermined reference position C. The cooler 64 is in a standby state in which a cooling operation is performed by driving the air blower.

[0165] In this state, the medium S is subjected to heating and pressure fixing processing in the fixing area FA of the second fixing device 60 , is transported by the transport fixing belt 62 , is cooled by the cooler 64 , and is discharged from the second fixing device 60 .

[0166] Therefore, as the media S uses Figure 4 The special paper shown is subjected to a series of fixing processes such as a cooling process after being subjected to a heating and pressurizing process, thereby being able to obtain a high-gloss image like a photographic image.

[0167] -Contact or separation treatment of cooler-

[0168] While the fixing process of the second fixing device 60 is being performed, the contact or separation operation of the cooler 64 is performed in parallel in the second fixing device 60 .

[0169] The contact or separation process of the cooler is carried out according to Figure 7 The process is carried out according to the flowchart shown.

[0170] First, if Figure 6 As shown, the control device 150 detects whether the front end of the medium S passes through the position P of the position sensor 53. If the front end of the medium S passes through the position P of the position sensor 53, the control device 150 uses the detection result as a trigger to start the counting action of the timing counter. Then, the control device 150 determines whether the front end of the medium S passes through a predetermined reference position C in front of the cooling area CA of the cooler 64. The reference position C becomes a reference for moving the cooler 64 at the retreat position to the contact position, and is therefore appropriately selected in consideration of the time when the cooler 64 completes the movement to the contact position before the medium S reaches the entrance of the cooling area CA based on the cooler 64.

[0171] In this example, the time when the front end of the medium S passes the reference position C is determined by the count value of the timing counter triggered by the detection output of the position sensor 53. However, this is not limited to this, and as long as the position P of the position sensor 53 is selected so as to become the reference position C, the setting operation of the cooler 64 to the contact position can also be directly performed using the detection output of the position sensor 53.

[0172] In this example, when the front end of the medium S reaches the reference position C, Figure 8 As shown in (a), the control device 150 follows Figure 5The step shown in (a) is to perform the setting operation of the cooler 64 to the contact position.

[0173] The cooler 64 is set to the contact position before the medium S reaches the entrance of the cooling area CA of the cooler 64. Therefore, the entire area of ​​the medium S is cooled while passing through the cooling area CA of the cooler 64. Then, the cooled medium S leaves the cooling area CA of the conveying fixing belt 62 and is discharged from the second fixing device 60.

[0174] At this time, if the rear end of the medium S leaves the outlet of the cooling area (downstream end point B), the control device 150 identifies the time when the medium S leaves the cooling area CA according to the count value of the timing counter, such as Figure 8 As shown in (b), according to Figure 5 The step shown in (b) performs the retraction operation of the cooler 64 to the retracted position.

[0175] Thus, while the medium S passes through the cooling area CA of the cooler 64 of the conveying fixing belt 62, the cooler 64 is set at the contact position, and while the medium S does not pass through the cooling area CA, the cooler 64 is retracted to the retracted position not in contact with the conveying fixing belt 62. Therefore, unnecessary cooling of the conveying fixing belt 62 by the cooler 64 is avoided, and for example, additional energy required for cooling the cooler 64 or heating the heating fixing roller 61 and the pressure fixing roller 63 can be omitted, which is preferable in this regard.

[0176] -Fixing process when conveying multiple sheets of media by the second fixing device-

[0177] like Fig. 9 As shown in (a), it is assumed that a plurality of media S (S1, S2, ...) of the same type or different types are transmitted at a predetermined interval. Fig. 9 In (a), L CA L represents the length of the cooling area CA of the cooler 64 along the conveying direction of the medium S, and PG Indicates the distance between the rear end of the preceding medium S1 and the front end of the succeeding medium S2 (so-called page interval).

[0178] At this time, in the page interval L PG Length L beyond cooling area CA CA The condition is L PG >L CA (ensuring a certain degree of page spacing), such as Fig. 9As shown in (b), at the time tC(1), tC(2) ... when the front end of each medium S (S1, S2 ...) passes the reference position C, the cooler 64 can be moved from the retreat position to the contact position. On the other hand, at the time tB(1), tB(2) ... when the rear end of each medium S (S1, S2 ...) passes the downstream end point B of the cooling area CA, the cooler 64 can be retreated from the contact position to the retreat position.

[0179] In contrast, at page interval L PG is the length L of the cooling area CA CA The following conditions are L PG ≤L CA (page interval is shorter than cooling area), if you want to apply Fig. 9 (b) of FIG. 5 , there is a high possibility that the actual cooling effect of the cooler 64 on the medium is insufficient. Therefore, in the case of this example, for example, Fig. 9 As shown in (c), the contact or separation action of the cooler 64 is not performed. Exceptionally, the cooler 64 is preferably kept in a state of being always arranged in the contact position.

[0180] ◎Deformation method 1

[0181] Fig.10 It is an explanatory diagram showing a main part of the second fixing device according to the first modification.

[0182] In this figure, the basic structure of the second fixing device is substantially the same as that of the first embodiment, and a positioning roller 140 is provided on the back side between the inlet (upstream starting point A) of the cooling area CA and the fixing area FA in the conveying fixing belt 62. The positioning roller 140 is arranged at a position that matches the surface posture (reference posture) of the medium conveying area SA of the conveying fixing belt 62 when the cooler 64 is set at the contact position.

[0183] In addition, the same symbols as those in Embodiment 1 are given to the same structures as those in Embodiment 1, and their detailed description is omitted here.

[0184] Here, in the first embodiment, since there is no positioning roller 140, Fig.11 As shown by the dotted line in (a), if the cooler 64 is retracted to the retracted position with respect to the conveying fixing belt 62 with the swing shaft 101 as the swing point, a gap is generated between the back side of the conveying fixing belt 62 and the cooler 64. Fig.11 As shown by the dotted line in (a), the conveyor fixing belt 62 no longer supported by the cooler 64 may sink vertically downward. Fig.11As shown in (b), the posture of the conveying fixing belt 62 between the fixing area FA and the entrance (upstream starting point A) of the cooling area CA (equivalent to the conveying belt moving direction) forms an elevation angle θ1 with respect to the aforementioned reference posture (equivalent to the medium discharge direction m passing through the fixing area FA), and when the subsequent medium passes through the fixing area FA, the medium S is easily peeled off from the medium conveying surface of the conveying fixing belt 62. In this case, uneven front end gloss may occur due to the peeling of the front end of the medium S.

[0185] However, as shown in the first modification, if the registration roller 140 is provided, the posture of the surface on which the fixing belt 62 is conveyed is maintained at the reference posture, and thus, for example, the above-mentioned inconvenience can be eliminated, which is preferable in this respect.

[0186] ◎Deformation method 2

[0187] In the present embodiment, the contact or separation mechanism 100 of the cooler 64 is provided with a swing shaft 101 at the end portion on the outlet (downstream end point B) side of the cooling area CA, but the present invention is not limited thereto, and a swing shaft may be provided at the end portion on the inlet (upstream start point A) side of the cooling area CA to enable the contact or separation mechanism 100 of the cooler 64 to swing. In this case, the surface posture of the conveying fixing belt 62 between the inlet of the cooling area CA and the fixing area FA is maintained at the reference posture, so there is no need to provide a positioning roller as described above.

[0188] However, there is a possibility that the surface posture of the conveying fixing belt 62 may change between the exit of the cooling area CA (downstream end point B) and the medium peeling point (equivalent to the exit of the medium conveying area SA) by the peeling roller 67. In this case, from the viewpoint of maintaining the contact state between the medium S and the conveying fixing belt 62 between the downstream end point B and the peeling roller 67, for example, it is preferable to provide the aforementioned positioning roller in the area where there is a possibility that the surface posture of the conveying fixing belt 62 may change.

[0189] ◎Implementation method 2

[0190] Fig.12 This is an explanatory diagram showing a main part of a second fixing device according to the second embodiment.

[0191] In this figure, the basic structure of the second fixing device 60 is substantially the same as that of the first embodiment, but it includes a contact or separation mechanism 100 different from that of the first embodiment. The same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and detailed description thereof is omitted.

[0192] In implementation mode 2, if Fig.13As shown in (a) and (b), the contact or separation mechanism 100 calculates the period during which the medium S does not pass through the cooling area CA according to the passing state of the medium S in the cooling area CA of the cooler 64, and moves the conveying fixing belt 62 from the contact position to the retracted position relative to the fixedly configured cooler 64.

[0193] In this example, the contact or separation mechanism 100 includes a push-up roller 160 as a push-up member, a connecting bracket 165 for holding the two end shaft portions of the push-up roller 160, and a variable mechanism 170 for changing the position of the connecting bracket 165 along the thickness direction of the conveying fixing belt 62, at a position other than the cooling area CA on the back side of the media conveying area SA for conveying the fixing belt 62.

[0194] The contact or separation operation timing of the conveying fixing belt 62 by the contact or separation mechanism 100 is substantially the same as the contact or separation operation timing of the cooler 64 described in the first embodiment.

[0195] In this example, the push-up roller 160 is provided in contact with the back surface of the conveying fixing belt 62 located between the fixing area FA and the entrance (upstream starting point A) of the cooling area CA of the cooler 64 .

[0196] Furthermore, the connecting bracket 165 has a holding frame 166 extending above the conveyor fixing belt 62 in the width direction of the conveyor fixing belt 62 , and has a pair of holding arms 167 at both ends thereof hanging downwardly on the outer sides of the conveyor fixing belt 62 in the width direction.

[0197] In this example, the connecting bracket 165 rotatably holds both ends of the push-up roller 160 between a pair of holding arms 167. Furthermore, the connecting bracket 165 rotatably holds both ends of the entrance side opposing roller between a pair of holding arms 167. Here, the push-up roller 160 and the entrance side opposing roller 131 are arranged in a predetermined positional relationship with the conveying fixing belt 62 interposed therebetween.

[0198] Moreover, the variable mechanism 170 includes an eccentric cam 172 which is rotated by a driving motor 171, a cam follower 173 which is rotatably arranged on both sides of a pair of retaining arms 167 of the connecting bracket 165 and abuts against the cam surface of the eccentric cam 172, and a push spring 174 which serves as a biasing member for biasing the lower end portion of the retaining arm 167 of the connecting bracket 165 toward the side of the conveying fixing belt 62.

[0199] According to the contact or separation mechanism 100 of this embodiment, when the conveying fixing belt 62 is set at the contact position with the cooler 64, as shown in FIG. Fig.13As shown in (a), for example, the eccentric cam 172 is rotated in the clockwise direction by driving the motor 171, and the large diameter portion r2 of the eccentric cam 172 is brought into contact with the cam follower 173 by overcoming the force of the push spring 174. Then, the variable mechanism 170 presses the connecting bracket 165 downward, and accordingly, the upper push roller 160 and the entrance side opposing roller 131 are pressed downward. As a result, the conveying fixing belt 62 pushed upward by the upper push roller 160 returns to the contact position with the cooler 64. At this time, the conveying fixing belt 62 is also pressed downward with the downward pressing action of the entrance side opposing roller 131, so that the conveying fixing belt 62 is in contact with the cooler 64 and the entrance side opposing roller 131 abuts against the entrance (upstream starting point A) of the cooling area CA of the cooler 64 with the conveying fixing belt 62 interposed therebetween.

[0200] On the other hand, when the conveyor fixing belt 62 is retracted from the contact position with the cooler 64 to the retracted position, as shown in FIG. Fig.13 As shown in (b), the eccentric cam 172 is rotated in the counterclockwise direction by driving the motor 171, and the small diameter portion r1 of the eccentric cam 172 is brought into contact with the cam follower 173 by overcoming the force of the push spring 174. Then, the connecting bracket 165 is pushed upward by the force of the push spring 174. Along with this, the push-up roller 160 pushes up the conveying fixing belt 62. At this time, the entrance side opposing roller 131 is also pushed upward along with the upward push of the connecting bracket 165, maintaining the relative position relationship with the push-up roller 160.

[0201] Therefore, the conveyor fixing belt 62 retreats to a retreat position oblique to the contact position with the cooler 64 with the exit (downstream end point B) of the cooling area CA of the cooler 64 as the contact point. During the retreating operation of the conveyor fixing belt 62, the entrance side opposing roller 131 does not become an obstacle.

[0202] ◎Implementation method 3

[0203] Fig.15 This is an explanatory diagram showing a main part of the second fixing device according to the third embodiment.

[0204] In this figure, the basic structure of the second fixing device 60 is substantially the same as that of the first embodiment, but even when the medium S passes through the cooling area CA of the cooler 64, the cooling effect of the medium S is further improved. In addition, the same reference numerals are attached to the same components as those of the first embodiment, and their detailed description is omitted here.

[0205] -Structural example of contact or separation mechanism-

[0206] In this embodiment, similarly to the first embodiment, the contact or separation mechanism 100 is configured to be able to swing the cooler 64 , and swings the cooler 64 between the contact position and the retracted position with respect to the conveying fixing belt 62 .

[0207] In this embodiment, the timing at which the cooler 64 moves from the contact position to the retracted position is the same as that of the first embodiment.

[0208] However, the timing at which the cooler 64 moves from the retreat position to the contact position is different from that in Embodiment 1. That is, in this embodiment, the temperature of the medium S passing through the cooling area CA of the cooler 64 is measured, and based on the temperature information, the timing at which the cooler 64 moves is made different when the degree of cooling of the medium S is sufficient or not sufficient.

[0209] In this example, the medium S is conveyed in close contact with the conveying fixing belt 62, and a back surface (at the side opposite to the image holding surface of the medium S) is measured under the condition that the medium S passes through the cooling area CA of the cooler 64. Fig.15 The temperature sensor 180 is configured to measure the temperature Td of the front end of the medium S (corresponding to the upper surface of the medium S). The temperature sensor 180 is arranged above the conveying fixing belt 62 at a position that does not contact the medium S conveyed along the conveying fixing belt 62. As the non-contact type temperature sensor 180, for example, a radiation thermometer or the like can be used. The temperature sensor 180 measures the temperature Td of the front end of the medium S passing through the midpoint D, with the center position of the cooling area CA of the cooler 64 of the conveying fixing belt 62 in the medium conveying direction as the midpoint D.

[0210] In this example, the temperature sensor 180 measures the temperature of the back side of the medium S, but does not measure the temperature of the surface (image holding surface) of the medium S. Therefore, it is conceivable that the temperature distribution in the thickness direction of the medium S differs depending on the thickness or physical properties of the medium S, and the temperature of the back side of the medium S may be high depending on the type of the medium S. However, when the temperature of the back side of the medium S drops below the target temperature (allowable cooling temperature) Tth set as a target, it is easily estimated that the temperature of the surface of the medium S directly contacting the cooling area CA of the cooler 64 is below the allowable cooling temperature.

[0211] Furthermore, when Td≤Tth (for example, 60°C), it can be understood that the cooling process is completed when the medium S passes the midway point D. In this case, it can be inferred that the cooling process of the medium S is completed at the stage when the rear end of the medium S passes the midway point D. In this state, it is not necessary to continue the cooling process until the medium S leaves the cooling area CA.

[0212] Therefore, in this example, when the condition of Td≤Tth (for example, 60° C.) is satisfied, the cooler 64 starts to retract from the contact position to the retracted position when the rear end of the medium S passes through the midway point D of the cooling area CA.

[0213] However, under the condition of Td>Tth (for example, 60°C), as in embodiment 1, the following method is adopted, that is, when the rear end of the medium S passes through the exit (downstream end point B) of the cooling area CA, the retraction action of the cooler 64 from the contact position to the retraction position is started.

[0214] -Contact or separation treatment of cooler-

[0215] The contact or separation process of the cooler is carried out according to Fig.16 Proceed as shown in the flowchart.

[0216] First, the control device 150 detects whether the front end of the medium S passes through the position P of the position sensor 53. If the front end of the medium S passes through the position P of the position sensor 53, the control device 150 uses the detection result as a trigger to start the counting operation of the timing counter. Then, the control device 150 determines whether the front end of the medium S passes through a predetermined reference position C in front of the cooling area CA of the cooler 64. The reference position C becomes a reference for moving the cooler 64 at the retreat position to the contact position, and is selected in the same manner as in the first embodiment.

[0217] In this example, the time when the leading end of the medium S passes the reference position C is determined by the count value of the timing counter triggered by the detection output of the position sensor 53 .

[0218] In this example, when the front end of the medium S reaches the reference position C, similarly to the first embodiment, Figure 8 As shown in (a), the control device 150 follows Figure 5 The step shown in (a) is to perform the setting operation of the cooler 64 to the contact position.

[0219] The setting operation of the cooler 64 to the contact position is completed before the medium S reaches the entrance of the cooling area CA by the cooler 64 , so the entire area of ​​the medium S is cooled by the cooling action while passing through the cooling area CA of the cooler 64 .

[0220] Then, if Fig.17 As shown in (a), if the front end of the medium S reaches the midpoint D of the cooling area CA, the control device 150 determines the moment when the front end of the medium S passes the midpoint D based on the count value of the timing counter, and measures the temperature Td of the back side of the front end of the medium S through the temperature sensor 180.

[0221] At this time, the control device 150 compares the temperature Td measured by the temperature sensor 180 with a predetermined target temperature, that is, a cooling allowable temperature Tth (for example, 60° C.).

[0222] Then, if the control device 150 determines that the condition of Td≤Tth is satisfied, Fig.17 As shown in (b) of FIG. 1 , when the rear end of the medium S passes through the midway point D of the cooling area CA, the retraction operation of retracting the cooler 64 from the contact position to the retracted position is started.

[0223] On the other hand, when the control device 150 determines that the condition of Td>Tth (for example, 60°C) is satisfied, Fig.17 As shown in (c), at the time when the rear end of the medium S passes through the exit (downstream end point B) of the cooling area CA, the retraction operation of retracting the cooler 64 from the contact position to the retracted position is started.

[0224] As described above, in the present embodiment, the second fixing device 60 performs substantially the same functions as those in the first embodiment, and also performs the following unique functions.

[0225] Specifically, the following retraction action is adopted, that is, when the medium S receives sufficient cooling action while passing through the cooling area CA of the cooler 64, that is, when the medium S is sufficiently cooled, the cooler 64 is retracted to the retraction position before the medium S leaves the cooling area CA. Therefore, it is possible to eliminate the waste of cooling energy that is not necessary for cooling the medium S and is only provided for cooling the conveying fixing belt 62.

[0226] In addition, in the present embodiment, the temperature measurement location based on the temperature sensor 180 is the midpoint D of the cooling area CA, but the midpoint D is not limited to the central position of the cooling area CA in the media transmission direction, and the midpoint D can also be appropriately selected from the front and rear areas of the central position in the media transmission direction across the cooling area CA.

[0227] Furthermore, in this embodiment, the contact or separation mechanism 100 uses a mechanism substantially similar to that of the first embodiment, but a mechanism substantially similar to that of the second embodiment may also be used.

[0228] (Note)

[0229] (((1))) A fixing device that heats and pressurizes a medium holding an unfixed image and then cools the medium to fix the unfixed image, the fixing device comprising:

[0230] A heated fixing member having a heating source;

[0231] a belt-shaped conveying and fixing member, which is arranged to be stretched on the heating and fixing member and can circulate, and is in contact with the image surface of the medium to convey the medium;

[0232] a pressurizing fixing member disposed opposite to the heating fixing member with the conveying fixing member interposed therebetween and applying pressure so as to form a fixing area between the pressurizing fixing member and the heating fixing member;

[0233] a cooling member disposed on the downstream side of the fixing area in the conveying and fixing member in the conveying and fixing direction of the medium so as to contact with the back surface of the medium conveying area of ​​the conveying and fixing member and cool the conveying and fixing member; and

[0234] The switching member switches the conveying and fixing member and the cooling member to a contact state or a non-contact state according to a passing state of the medium in a cooling area of ​​the cooling member.

[0235] (((2)))The fixing device according to (((1))), characterized in that:

[0236] The switching member switches the conveying and fixing member and the cooling member to a non-contact state while the medium is not passing through a cooling area of ​​the conveying and fixing member by the cooling member.

[0237] (((3)))The fixing device according to (((1))) or (((2))), characterized in that:

[0238] Before the front end of the medium in the conveying direction reaches the entrance of the cooling area, the switching component switches the cooling component to a contact state, and when the rear end of the medium in the conveying direction has reached the exit of the cooling area, the cooling component is switched to a non-contact state.

[0239] (((4)))The fixing device according to (((1))) or (((2))), characterized in that:

[0240] The switching member switches the cooling member to a non-contact state under the condition that the medium is cooled to a predetermined temperature before the rear end of the medium in the conveying direction reaches the exit of the cooling area.

[0241] (((5))) The fixing device according to any one of (((1))) to (((4))), characterized in that:

[0242] The switching member includes a moving mechanism that moves the cooling member relative to the transporting and fixing member.

[0243] (((6)))The fixing device according to (((5))), characterized in that:

[0244] The moving mechanism supports the cooling member so that it can swing with the end of the outlet side or the inlet side of the cooling area of ​​the cooling member as a swing point, and swings the cooling member between a contact position with the conveying and fixing member and a retreat position retreated from the conveying and fixing member.

[0245] (((7)))The fixing device according to (((5))) is characterized by comprising:

[0246] A positioning member is provided on the back side of the medium conveying region of the conveying and fixing member, and maintains the surface posture of the medium conveying region of the conveying and fixing member when all or part of the cooling member is retracted from the contact position with the back side of the conveying and fixing member.

[0247] (((8))) The fixing device according to any one of (((1))) to (((4))), characterized in that:

[0248] The switching member includes a moving mechanism that moves the transport fixing member relative to the cooling member.

[0249] (((9)))The fixing device according to (((8))), characterized in that:

[0250] The moving mechanism includes a push-up member provided at a portion other than the cooling region in the back side of the medium conveying region of the conveying and fixing member, and pushing the medium conveying region portion of the conveying and fixing member in a direction away from the cooling member.

[0251] (((10)))The fixing device according to any one of (((1))) to (((9))), characterized by comprising:

[0252] The opposing rotating member is disposed to oppose the entrance of the cooling region of the cooling member with the transporting and fixing member interposed therebetween, and rotates following the transporting and fixing member.

[0253] (((11)))The fixing device according to (((10))) is characterized by comprising:

[0254] A plurality of opposed rotating members are disposed to oppose the transporting and fixing member and an entrance to a cooling region of the cooling member and a portion different from the entrance, and rotate following the transporting and fixing member.

[0255] (((12)))The fixing device according to (((9))) is characterized by comprising:

[0256] One or more opposed rotating members are arranged to face the entrance of the cooling area of ​​the cooling member across the conveying and fixing member, or to face the entrance of the cooling area and a portion different from the entrance, and rotate following the conveying and fixing member.

[0257] A part or all of the opposed rotating member moves in conjunction with the push-up member.

[0258] (((13)))The fixing device according to any one of (((1))) to (((12))), characterized in that:

[0259] The switching component has a position detection component that detects the position of the front end or rear end in the conveying direction of the medium at a position closer to the upstream side of the medium in the conveying direction than the fixing area, calculates the position of the front end or rear end in the conveying direction of the medium conveyed by the conveying fixing component based on the detection result of the position detection component, and switches the contact or non-contact state of the cooling component.

[0260] (((14)))The fixing device according to (((13))) is characterized in that:

[0261] When the position detection member detects the rear end position of the medium in the conveying direction, the switching member switches the cooling member to a non-contact state at a time when the rear end of the medium reaches the exit of the cooling area according to the detection result.

[0262] (((15)))The fixing device according to (((13))) is characterized in that:

[0263] When the position detection member detects the front end position of the medium in the conveying direction, the switching member switches the cooling member to the contact state at a point before the front end of the medium reaches the entrance of the cooling area based on the detection result.

[0264] (((16)))The fixing device according to any one of (((1))) to (((15))), characterized in that:

[0265] The switching component has a judging component for judging the distance between the rear end of the preceding medium in the conveying direction and the front end of the succeeding medium in the conveying direction. Under the condition that the distance judged by the judging component is less than the length of the cooling area, the contact / non-contact switching action of the cooling component is not performed.

[0266] (((17)))An image forming system, comprising:

[0267] An image generating component for producing an unfixed image on a medium; and

[0268] The fixing device described in any one of (((1))) to (((16))) fixes an unfixed image held on a medium.

[0269] According to the fixing device involved in (((1))), unnecessary cooling that does not contribute to cooling of the medium can be suppressed and fixing performance can be ensured, compared with the case where the conveying fixing member is continuously cooled when the unfixed image on the medium is fixed by heating and cooling the belt-shaped conveying fixing member.

[0270] According to the fixing device according to (((2))), when cooling of the medium is not required, the operation of cooling the transport fixing member by the cooling member can be omitted.

[0271] According to the fixing device according to (((3))), the cooling member can cool the transport fixing member while the medium passes through the cooling area of ​​the cooling member.

[0272] According to the fixing device of (((4))), even when the medium has not completely passed through the cooling area of ​​the cooling member, if the temperature of the medium has been sufficiently cooled, the cooling operation of the conveying fixing member by the cooling member can be omitted.

[0273] According to the fixing device according to (((5))), by moving the cooling member relative to the transport fixing member, the contact and non-contact states of the cooling member can be easily switched.

[0274] According to the fixing device of (((6))), compared with the case where the entire cooling member is switched between contact and non-contact with respect to the fixing conveying member, the cooling member can be switched between contact and non-contact with respect to the fixing conveying member with a simple configuration as the switching member.

[0275] According to the fixing device of (((7))), even if the cooling member is moved relative to the transport fixing member, the surface posture of the medium conveying region of the transport fixing member can be maintained.

[0276] According to the fixing device according to (((8))), by moving the fixing transport member relative to the cooling member, the contact and non-contact states of the cooling member can be easily switched.

[0277] According to the fixing device according to (((9))), the transport fixing member can be moved relative to the cooling member with a simple structure as the switching member.

[0278] According to the fixing device of (((10))), compared with a case where no opposing rotating member is used, the medium conveyed on the conveying fixing member can be brought into close contact with the cooling area of ​​the cooling member appropriately.

[0279] According to the fixing device of (((11))), compared with a case where a single opposing rotating member is provided at the entrance of the cooling area of ​​the cooling member, the medium conveyed on the conveying fixing member can be brought into close contact with the cooling area of ​​the cooling member appropriately.

[0280] According to the fixing device of (((12))), even if the opposing rotating member is provided in the cooling region of the cooling member, the opposing rotating member does not become an obstacle and the pushing-up member can push up and convey the fixing member.

[0281] According to the fixing device of (((13))), by using the position detection member that detects the conveyance position of the medium, the switching timing of the state between the contact and non-contact state of the cooling member by the switching member can be easily grasped.

[0282] According to the fixing device of (((14))), by using the position detection member for detecting the conveyance position of the medium, switching to the non-contact state of the cooling member can be easily achieved.

[0283] According to the fixing device of (((15))), by using the position detection member for detecting the conveyance position of the medium, switching to the contact state of the cooling member can be easily achieved.

[0284] According to the fixing device of (((16))), when the distance between the preceding medium and the succeeding medium is equal to or smaller than the length of the cooling region of the cooling member, the switching operation by the switching member can be omitted.

[0285] According to the image forming system involved in (((17))), it is possible to construct an image forming system including a fixing device that can suppress unnecessary cooling that does not contribute to cooling of the medium and ensure fixing performance, compared to a case in which a belt-shaped conveying fixing member is continuously cooled when an unfixed image on a medium is fixed by heating and cooling the belt-shaped conveying fixing member.

[0286] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

[0287] Explanation of symbols

[0288] 1-heating fixing member, 2-conveying fixing member, 3-pressurizing fixing member, 4-cooling member, 5-switching member, 6 (6a, 6b)-opposing rotating member, 7-position detecting member, 8-positioning member, 9-pushing member, 10-fixing device, 11-image generating member, CA-cooling area, FA-fixing area, G-unfixed image, S-medium.

Claims

1. A fixing device that heats and pressurizes a medium holding an unfixed image and then cools the medium to fix the unfixed image, the fixing device comprising: A heated fixing member having a heating source; a belt-shaped conveying and fixing member, which is arranged to be stretched on the heating and fixing member and can circulate, and is in contact with the image surface of the medium to convey the medium; a pressurizing fixing member disposed opposite to the heating fixing member with the conveying fixing member interposed therebetween and applying pressure so as to form a fixing area between the pressurizing fixing member and the heating fixing member; a cooling member disposed on the downstream side of the fixing area in the conveying and fixing member in the conveying and fixing direction of the medium so as to contact with the back surface of the medium conveying area of ​​the conveying and fixing member and cool the conveying and fixing member; and The switching member switches the conveying and fixing member and the cooling member to a contact state or a non-contact state according to a passing state of the medium in a cooling area of ​​the cooling member.

2. The fixing device according to claim 1, characterized in that: The switching member switches the conveying and fixing member and the cooling member to a non-contact state while the medium is not passing through a cooling area of ​​the conveying and fixing member by the cooling member.

3. The fixing device according to claim 1 or 2, characterized in that: Before the front end of the medium in the conveying direction reaches the entrance of the cooling area, the switching component switches the cooling component to a contact state, and when the rear end of the medium in the conveying direction has reached the exit of the cooling area, the cooling component is switched to a non-contact state.

4. The fixing device according to claim 1 or 2, characterized in that: The switching member switches the cooling member to a non-contact state under the condition that the medium is cooled to a predetermined temperature before the rear end of the medium in the conveying direction reaches the exit of the cooling area.

5. The fixing device according to any one of claims 1 to 4, characterized in that: The switching member includes a moving mechanism that moves the cooling member relative to the transporting and fixing member.

6. The fixing device according to claim 5, characterized in that: The moving mechanism supports the cooling member so that it can swing with the end of the outlet side or the inlet side of the cooling area of ​​the cooling member as a swing point, and swings the cooling member between a contact position with the conveying and fixing member and a retreat position retreated from the conveying and fixing member.

7. The fixing device according to claim 5, characterized in that: have: A positioning member is provided on the back side of the medium conveying region of the conveying and fixing member, and maintains the surface posture of the medium conveying region of the conveying and fixing member when all or part of the cooling member is retracted from the contact position with the back side of the conveying and fixing member.

8. The fixing device according to any one of claims 1 to 4, characterized in that: The switching member includes a moving mechanism that moves the transport fixing member relative to the cooling member.

9. The fixing device according to claim 8, characterized in that: The moving mechanism includes a push-up member provided at a portion other than the cooling region on the back side of the medium conveying region of the conveying and fixing member and pushing the medium conveying region portion of the conveying and fixing member in a direction away from the cooling member.

10. The fixing device according to any one of claims 1 to 9, characterized in that: have: The opposing rotating member is disposed to oppose the entrance of the cooling region of the cooling member with the transporting and fixing member interposed therebetween, and rotates following the transporting and fixing member.

11. The fixing device according to claim 10, characterized in that: have: A plurality of opposed rotating members are disposed to oppose the transporting and fixing member and an entrance to a cooling region of the cooling member and a portion different from the entrance, and rotate following the transporting and fixing member.

12. The fixing device according to claim 9, characterized in that: have: One or more opposed rotating members are arranged to face the entrance of the cooling area of ​​the cooling member across the conveying and fixing member, or to face the entrance of the cooling area and a portion different from the entrance, and rotate following the conveying and fixing member. A part or all of the opposed rotating member moves in conjunction with the push-up member.

13. The fixing device according to any one of claims 1 to 12, characterized in that: The switching component has a position detection component that detects the position of the front end or rear end in the conveying direction of the medium at a position closer to the upstream side of the medium in the conveying direction than the fixing area, calculates the position of the front end or rear end in the conveying direction of the medium conveyed by the conveying fixing component based on the detection result of the position detection component, and switches the contact or non-contact state of the cooling component.

14. The fixing device according to claim 13, characterized in that: When the position detection member detects the rear end position of the medium in the conveying direction, the switching member switches the cooling member to a non-contact state at a time when the rear end of the medium reaches the exit of the cooling area according to the detection result.

15. The fixing device according to claim 13, characterized in that: When the position detection member detects the front end position of the medium in the conveying direction, the switching member switches the cooling member to the contact state at a point before the front end of the medium reaches the entrance of the cooling area based on the detection result.

16. The fixing device according to any one of claims 1 to 15, characterized in that: The switching component has a judging component for judging the distance between the rear end of the preceding medium in the conveying direction and the front end of the succeeding medium in the conveying direction. Under the condition that the distance judged by the judging component is less than the length of the cooling area, the contact / non-contact switching action of the cooling component is not performed.

17. An image forming system, characterized in that: have: An image generating component for producing an unfixed image on a medium; and The fixing device according to any one of claims 1 to 16 fixes an unfixed image held on a medium.

Images