Fixing device and image forming system using the same

Abstract

During standby mode, when the power supply to the heating and fixing means is cut off or reduced, the heating and fixing means is allowed to rotate idle while suppressing a temperature drop in the heated transport and fixing means. [Solution] The system comprises a rotatable heating and fixing means 1 having a heating source 1a, a belt-shaped conveying and fixing means 2 stretched across the heating and fixing means 1 and circulatingly provided for conveying a medium S, a rotatable pressurizing and fixing means 3 that pressurizes to form a fixing area FA between itself and the heating and fixing means 1, a cooling means 4 that cools the conveying and fixing means 2 downstream of the fixing area FA in the direction of conveying the medium S, and a drive control means 6 that controls the conveying and fixing means 2 to perform idle rotation, repeating forward and reverse rotation movements, so that the portion of the conveying and fixing means 2 including the contact area CN that contacts the heating and fixing means 1 and the area up to the cooling area CA cooled by the cooling means 4 contacts the heating and fixing means 1.

Description

Technical Field

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

Background Art

[0002] Conventionally, as this type of fixing device, for example, the one described in Patent Document 1 is already known. In Patent Document 1, in order to solve the technical problem that wrinkles are likely to occur when an endless belt for fixing immediately after heating is sandwiched and pressed, the endless belt is rotated reversely before heat fixing and rotated forward after heating, and the time until the heated portion of the endless belt is pressed is lengthened, and an image forming apparatus provided with a fixing device for suppressing the generation of wrinkles in the endless belt is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technical problem to be solved by the present invention is to provide a fixing device that rotates the belt-shaped conveyance and fixing means idly while suppressing a temperature drop of the heated conveyance and fixing means and the heating and fixing means when the power supply to the heating and fixing means is cut off or reduced in a standby mode when cooling the belt-shaped conveyance and fixing means after heating and pressurizing to fix an unfixed image on a medium, and an image forming system using the same.

Means for Solving the Problems

[0005] A first technical feature of the present invention is a fixing device comprising: a rotatable heating and fixing means having a heating source; a belt-shaped transport and fixing means stretched over the heating and fixing means and circulatingly provided, which transports a medium in contact with the image surface of a medium holding an unfixed image; a rotatable pressurizing and fixing means positioned opposite the heating and fixing means with the transport and fixing means in between, which pressurizes to form a fixing area for fixing the unfixed image between itself and the heating and fixing means; a cooling means provided in contact with the back surface of the transport and fixing means at a point downstream of the fixing area in the transport region of the transport and fixing means, and for cooling the transport and fixing means; and a drive control means that controls the transport and fixing means to perform idle rotation, repeating forward and reverse rotation, so that a portion of the transport and fixing means, including the contact area that contacts the heating and fixing means and the area up to the cooling area cooled by the cooling means, contacts the heating and fixing means when the power supplied to the heating source of the heating and fixing means is cut off or reduced.

[0006] A second technical feature of the present invention is a fixing device having the first technical feature, wherein the drive control means stops the forward rotation drive of the transport fixing means and starts the reverse idle rotation drive of the transport fixing means when in standby mode which the power supplied to the heating fixing means is cut off or reduced. A third technical feature of the present invention is a fixing device having the second technical feature, wherein the drive control means starts the idle rotation drive in the reverse direction, then stops at a first position before the portion of the transport fixing means that has been cooled by the cooling means reaches the contact area of ​​the heating fixing means, and then starts the idle rotation drive of the transport fixing means in the forward direction. A fourth technical feature of the present invention is a fixing device having the third technical feature, wherein the drive control means starts the forward idle rotation drive of the transport fixing means, stops at a second position before the heated portion of the transport fixing means reaches the cooling area by the cooling means, then drives the transport fixing means to idle rotation in the reverse direction, and thereafter performs the forward and reverse idle rotation drive of the transport fixing means between the first position and the second position. A fifth technical feature of the present invention is a fixing device having the third technical feature, wherein the drive control means starts the forward idle rotation drive of the transport fixing means, stops at a third position before the portion of the transport fixing means cooled by the cooling means reaches the contact area of ​​the heating fixing means, then drives the transport fixing means to idle rotation in the reverse direction, and thereafter performs the forward and reverse idle rotation drive of the transport fixing means between the first position and the third position.

[0007] A sixth technical feature of the present invention is a fixing device having the first technical feature, wherein the drive control means performs forward and reverse idle rotation driving of the transport fixing means so that the portion of the transport fixing means that is passing through or has passed through the cooling area by the cooling means does not reach the contact area by the heating fixing means. The seventh technical feature of the present invention is a fixing device having the sixth technical feature, wherein the drive control means performs forward and reverse idle rotation drive of the conveying fixing means so that the portion of the conveying fixing means heated by the heating fixing means does not reach the cooling area of ​​the cooling means. The eighth technical feature of the present invention is a fixing device having the first technical feature, wherein the pressurized fixing means is provided with a contact / separation means that moves to and from a non-contact position away from a contact position that is in contact with the transport fixing means when in standby mode. The ninth technical feature of the present invention is a fixing device having the eighth technical feature, wherein the pressurized fixing means does not have a heating source. A tenth technical feature of the present invention is a fixing device having the first technical feature, wherein the fixing device has a position detection means for detecting the position of the leading or trailing end of the medium in the transport direction, located upstream of the fixing area in the transport direction of the medium, and the standby mode is released and power supply to the heating fixing means is started based on the detection result of the position detection means.

[0008] The eleventh technical feature of the present invention is an image forming system characterized by comprising: an imaging means for creating an unfixed image on a medium; and a fixing device having any of the first to tenth technical features for fixing the unfixed image held on the medium. [Effects of the Invention]

[0009] According to the first technical feature of the present invention, when fixing an unfixed image on a medium by heating and pressurizing a belt-shaped transport and fixing means and then cooling it, the transport and fixing means can be idled while suppressing the temperature drop of the heated transport and fixing means during standby mode in which the power supply to the heating and fixing means is cut off or reduced. According to a second technical feature of the present invention, the idle rotation drive of the transport and fixing means can be started immediately in standby mode. According to a third technical feature of the present invention, when the conveying and fixing means is driven to rotate freely in the reverse direction, it is possible to appropriately avoid a situation in which the temperature of the heating and fixing means decreases due to the portion cooled by the cooling means. According to the fourth technical feature of the present invention, when the conveying and fixing means is driven idle in the forward and reverse directions, it is possible to appropriately avoid the conveying and fixing means, which has been heated by the heating and fixing means, reaching the cooling zone of the cooling means. According to the fifth technical feature of the present invention, when the conveying and fixing means is driven idle in the forward and reverse directions, it is possible to appropriately avoid the conveying and fixing means, which has been cooled by the cooling means, reaching the contact area with the heating and fixing means. According to the sixth technical feature of the present invention, when the conveying and fixing means is driven idle in the forward and reverse directions, it is possible to avoid a situation in which the temperature of the heating and fixing means is unnecessarily cooled by the conveying and fixing means that has been cooled by the cooling means. According to the seventh technical feature of the present invention, when the conveying and fixing means is driven idle in the forward and reverse directions, it is possible to avoid a situation in which the temperature of the conveying and fixing means, which has been heated by the heating and fixing means, is unnecessarily cooled by the cooling means. According to the eighth technical feature of the present invention, compared to an embodiment without a contact / separation means, it is possible to avoid a situation in which the temperature of the transport and fixing means is unnecessarily lowered by the pressurizing fixing means during standby mode. According to the ninth technical feature of the present invention, compared to an embodiment without a contact / separation means, it is possible to avoid a situation in which the temperature of the transport fixing means unnecessarily decreases due to the pressurizing fixing means, which does not have a heating source, during standby mode. According to the tenth technical feature of the present invention, when performing a normal fixing mode, the standby mode can be released at an appropriate timing and power supply to the heating fixing means can be resumed. According to the eleventh technical feature of the present invention, when fixing an unfixed image on a medium by heating and pressurizing a belt-shaped transport and fixing means and then cooling it, an image forming system can be constructed that includes a fixing device capable of rotating the transport and fixing means while suppressing a decrease in the temperature of the heated transport and fixing means during a standby mode in which the power supply to the heating and fixing means is cut off or reduced. [Brief explanation of the drawing]

[0010] [Figure 1] (a) is an explanatory diagram showing an overview of an embodiment of an image forming system including a fixing device to which the present invention is applied, and (b) and (c) are explanatory diagrams showing examples of the behavior of the transport fixing means by the drive control means shown in (a). [Figure 2] This is an explanatory diagram showing the overall configuration of the image forming system according to Embodiment 1. [Figure 3] (a) is an explanatory diagram showing the main parts of the second fixing device according to Embodiment 1, and (b) is an explanatory cross-sectional view of the conveyor fixing belt. [Figure 4] (a) is an explanatory diagram showing special paper for photographic images as an example of a medium, (b) is an explanatory diagram showing the state in which a toner image has been fixed onto the special paper, and (c) is an explanatory diagram showing the state in which a toner image has been fixed onto plain paper as an example of a medium. [Figure 5] It is an explanatory diagram showing a control system of a second fixing device according to Embodiment 1. [Figure 6] It is a flowchart showing a drive control process of a second fixing device according to Embodiment 1. [Figure 7] (a) to (d) are explanatory diagrams schematically showing the behavior of the second fixing device in the standby mode executed according to the flowchart shown in FIG. 6. [Figure 8] It is a flowchart showing a drive control process of a second fixing device according to Modification 1. [Figure 9] (a) to (d) are explanatory diagrams schematically showing the behavior of the second fixing device in the standby mode executed according to the flowchart shown in FIG. 8. [Figure 10] It is an explanatory diagram showing a main part of a second fixing device according to Embodiment 2. [Figure 11] It is a flowchart showing a drive control process of a second fixing device according to Embodiment 2. [Figure 12] (a) to (d) are explanatory diagrams schematically showing the behavior of the second fixing device in the standby mode executed according to the flowchart shown in FIG. 11. [Figure 13] (a) is a graph showing the temperature change of the conveyance fixing belt in the standby mode of the second fixing device according to Example 1 and Comparative Example 1, and (b) is an explanatory diagram showing the temperature drop amounts of the conveyance fixing belt at standby times of 10 seconds and 30 seconds in the second fixing device according to Example 1 and Comparative Example 1, calculated based on the graph shown in (a).

MODE FOR CARRYING OUT THE INVENTION

[0011] ◎Overview of Embodiment FIG. 1(a) shows an overview of an embodiment of an image forming system including a fixing device to which the present invention is applied. In the figure, the image forming system includes an image forming means 11 for creating an unfixed image G on a medium S, and a fixing device 10 for fixing the unfixed image G held on the medium S. In this example, the fixing device 10 is a fixing device that heats and pressurizes a medium S holding an unfixed image G, then cools it to fix the unfixed image G, and comprises a rotatable heating and fixing means 1 having a heating source 1a, a belt-shaped transport and fixing means 2 stretched over the heating and fixing means 1 and circulatingly provided, which transports the medium S in contact with the image surface of the medium S, a rotatable pressurizing and fixing means 3 positioned opposite the heating and fixing means 1 with the transport and fixing means 2 in between, which pressurizes to form a fixing area FA between itself and the heating and fixing means 1, and the transport area of ​​the medium S of the transport and fixing means 2 The system includes a cooling means 4 provided downstream of the fixing area FA in the transport direction of the medium S, in contact with the back surface of the transport fixing means 2, for cooling the transport fixing means 2, and a drive control means 6 that controls the transport fixing means 2 to perform idle rotation, repeating forward and reverse rotation movements, so that the portion of the transport fixing means 2 including the contact area CN that contacts the heating fixing means 1 and the area up to the cooling area CA cooled by the cooling means 4 contacts the heating fixing means 1, when in standby mode when the power supplied to the heating source 1a of the heating fixing means 1 is cut off or reduced.

[0012] In this example, reference numeral 7 denotes a power supply means that supplies power to the heating source 1a of the heating and fixing means 1. This power supply means 7 cuts off or reduces the power supplied to the heating source 1a of the heating and fixing means 1 when in standby mode. Furthermore, the tensioning method of the transport and fixing means 2 includes a peeling means 5 that tensions the transport and fixing means 2 together with the heating and fixing means 1, as shown in Figure 1(a). This peeling means 5 is located downstream of the cooling means 4 in the transport direction of the medium S and is positioned to peel the medium S from the transport and fixing means 2. Note that the tensioning method of the transport and fixing means 2 is not limited to the configuration shown in Figure 1(a), and additional tensioning means not shown may be added.

[0013] In such technical means, the fixing device 10 of this embodiment may be incorporated into an image forming apparatus that includes an imaging means 11 for producing an unfixed image G, or it may be incorporated into a post-processing device separate from the image forming apparatus and configured as an image forming system consisting of multiple units. Furthermore, the heating and fixing means 1 includes, for example, a heating and fixing roll. The heating source 1a can be built-in or external. In addition, the transport and fixing means 2 includes a belt-shaped member. Here, in order to obtain a highly glossy image such as a photographic image, it is preferable that the belt-shaped member be, for example, an endless film made of thermosetting polyimide resin with a highly smooth coating layer formed on its surface. Furthermore, the pressure fixing means 3 can be roll-shaped or belt-shaped as long as it is pressurized to form a fixing area FA between itself and the heating and fixing means 1. The pressure fixing means 3 may have a heating source not shown as needed. The pressure fixing means 3 may also be equipped with a contact / separation means 8 that moves to and from a non-contact position away from a contact position that contacts the transport and fixing means 2 in standby mode. Furthermore, the cooling means 4 broadly includes any means that cools by contacting the back surface of the medium transport area of ​​the transport and fixing means 2. Primarily, a heat dissipation means that dissipates absorbed heat, such as a heat sink, is used.

[0014] Furthermore, the "standby mode" of the drive control means 6 includes not only cutting off the power supply to the heating source 1a of the heating fixing means 1, but also reducing the power supply. For example, there are cases where the power supply between the fixing device 10 in this example and another device is mutually controlled during warm-up. In this case, when warming up the other device, the fixing device 10 in this example is put into standby mode, and the power supply to the heating source 1a of the heating fixing means 1 is cut off. However, the fixing device 10 in this example can also be applied to configurations that do not presuppose mutual control. Therefore, in this example, in addition to cutting off the power supply to the heating source 1a of the heating fixing means 1 during standby mode, configurations that reduce the power supply are also included.

[0015] In this example, the drive control means 6 drives the transport fixing means 2 to idle when in standby mode, and ingenuity has been put into controlling the operation of the idle rotation drive. In particular, the "idle rotation drive" in this example requires that a predetermined portion of the transport and fixing means 2 be driven to repeatedly rotate in forward and reverse directions in contact with the heating and fixing means 1. The predetermined portion here refers to the portion 2h of the transport and fixing means 2 that is heated by the heating and fixing means 1 (see Figure 1(b)). More specifically, it is the portion that includes the contact area CN by the heating and fixing means 1 and the area from the heating and fixing means 1 to the cooling area CA by the cooling means 4. Such idle rotation is intended to minimize the temperature drop of the heating and fixing means 1 by the portion 2c of the transport and fixing means 2 that is cooled by the cooling means 4.

[0016] Next, a typical or preferred embodiment of the fixing device according to this embodiment will be described. First, a typical configuration of the drive control means 6 is as shown in Figure 1(b) when in standby mode, which involves cutting off or reducing the power supplied to the heating and fixing means 1. In this figure, the forward rotation drive of the transport and fixing means 2 is stopped, and the reverse idle rotation drive of the transport and fixing means 2 is started. A typical configuration of the drive control means 6 is to start the reverse-direction idle rotation drive of the transport and fixing means 2, as shown in Figure 1(b). In this figure, the portion 2c of the transport and fixing means 2 that has been cooled by the cooling means 4 stops at the first position P1, and then the forward-direction idle rotation drive of the transport and fixing means 2 is started. The "first position P1" here can be appropriately selected as long as it is a position before reaching the contact area CN by the heating and fixing means 1.

[0017] Furthermore, a typical configuration of the drive control means 6 is as shown in Figure 1(c), after starting the forward idle rotation drive of the transport and fixing means 2. In this figure, the heated portion 2h of the transport and fixing means 2 stops at the second position P2, and then the transport and fixing means 2 is driven to idle rotation in the reverse direction. The "second position P2" here can be appropriately selected as long as it is a position before reaching the cooling area CA by the cooling means 4. Thereafter, the transport and fixing means 2 can be driven to idle rotation in both forward and reverse directions between the first position P1 and the second position P2.

[0018] Another typical embodiment of the drive control means 6 is to start the forward idle rotation drive of the transport fixing means 2 and then perform the following actions. Now, as shown in Figure 1(a), the position before the portion 2c of the transport fixing means 2 cooled by the cooling means 4 reaches the contact area CN by the heating fixing means 1 is defined as the "third position P3". In this example, the cooled portion 2c of the transport fixing means 2 stops at the third position P3, and then the transport fixing means 2 is driven to idle rotation in the reverse direction. Thereafter, the transport fixing means 2 can be driven to idle rotation in both forward and reverse directions between the first position P1 and the third position P3.

[0019] Furthermore, a typical manner for disabling the standby mode by the power supply means 7 is shown in Figure 1(a). In this figure, reference numeral 9 denotes a position detection means that detects the position of the leading or trailing end of the medium S in the transport direction, upstream of the fixing area FA in the transport direction of the medium S. The power supply means 7 should disabling the standby mode based on the detection result of the position detection means 9 and start supplying power to the heating and fixing means 1.

[0020] Hereinafter, representative and preferred embodiments of a fixing device embodying the present invention will be described based on the embodiments shown in the attached drawings. ◎Embodiment 1 Figure 2 shows the overall configuration of the image forming system according to Embodiment 1. -Overall configuration of the image forming system- In the figure, the image forming system 15 has a main body 16 equipped with an image forming unit capable of forming color images. An optional post-processing device 50 is added to the top of the main body 16. On the other hand, a multi-stage media supply container 81 (81a, 81b) for supplying media such as paper is provided below the main body 16 and is retractable.

[0021] -Image Forming Unit- The image forming unit used in this embodiment employs, for example, an electrophotographic method and has a plurality of image forming units 20. The plurality of image forming units 20 form images of four colors, for example, yellow (Y), magenta (M), cyan (C), and black (K). In this example, each image forming unit 20 (20a to 20d) is arranged in parallel with a belt-shaped intermediate transfer body 30 in a so-called tandem configuration. Therefore, the toner images of each color formed in each image forming unit 20 (20a to 20d) are sequentially transferred onto, for example, the intermediate transfer body 30 and multiplexed. The multiplexed toner images are then transferred collectively onto a medium transported from a medium supply container 81 and fixed onto the medium S. Note that the color arrangement of the four image forming units 20 is not limited to this order and may be in other orders.

[0022] <Image Forming Section> In this embodiment, the image forming unit 20 (20a to 20d) has a photoreceptor 21 as an image holder that forms and holds toner images of each color component. Around the photoreceptor 21 are a charger 22, an exposure unit 23, a developer unit 24, a primary transfer unit 25, a photoreceptor cleaner 26, and a static eliminator 27, etc. The charger 22 is composed of a charging roll or the like that charges the photoreceptor 21. The exposure unit 23 is composed of a laser scanner or LED array or the like that forms a latent image on the photoreceptor 21 that has been charged by the charger 22. Furthermore, the developer unit 24 includes a developing roll or the like that that develops the electrostatic latent image formed on the photoreceptor 21 with toners of each color component. The primary transfer unit 25 is positioned opposite the photoreceptor 21, with an intermediate transfer unit 30 in between. The primary transfer unit 25 is composed of, for example, a primary transfer roll or a corona discharge unit that primary transfers the toner image on the photoreceptor 21 onto the intermediate transfer unit 30. Furthermore, the photoreceptor cleaner 26 includes a cleaning member for cleaning residual toner remaining on the photoreceptor 21. In addition, the static eliminator 27 consists of a static elimination roll and a corona discharger that remove residual charge on the photoreceptor 21. In this embodiment, the exposure unit 23 is configured to expose the entire four-color image forming unit 20 (20a to 20d) with a single exposure unit.

[0023] <Intermediate Transfer Material / Secondary Transfer Device> The intermediate transfer body 30 is stretched over multiple tension rolls 31 and 32. For example, tension roll 31 acts as a drive roll to circulate and transport the intermediate transfer body 30. Tension roll 32 is positioned opposite to the secondary transfer unit 33, for example, as a backup roll. Furthermore, an intermediate transfer body cleaner 34 is installed at a position opposite the tension roll 31 of the intermediate transfer body 30 to remove residual toner from the intermediate transfer body 30. In this example, the secondary transfer unit 33 has, for example, a secondary transfer roll 33a that contacts the surface side of the intermediate transfer body 30 facing the tension roll 32. In this example, the secondary transfer unit 33 applies a secondary transfer electric field between the secondary transfer roll 33a and the tension roll 32 to transfer the image on the intermediate transfer body 30 to the medium S in one go (secondary) transfer. Furthermore, within the main body 16 of the device, toner boxes 35 corresponding to each developer 24 of each image forming unit 20 are provided above the intermediate transfer body 30. Each toner box 35 supplies toner to the developer 24 corresponding to the respective color via a transport path (not shown).

[0024] <Media transport system> Furthermore, the media transport system 80 in this embodiment is configured as follows: Media is fed from each media supply container 81 by a pickup roll 82. The media is then handled by a feed roll 83 and a retard roll 84, and only one sheet of media is transported into the downstream transport path. Alignment rolls 85 and a first fuser 40 are provided in the transport path. The alignment rolls 85 position and align the media transported from the media supply container 81 before it enters the secondary transfer unit 33. The first fuser 40 fixes the unfixed toner image transferred onto the media by the secondary transfer unit 33. A switching member 86 for switching the transport path is provided downstream of the first fuser 40. In this example, the switching member 86 switches between two transport paths: one for the post-processing device 50 and the other for the first discharge receiver 87 which receives media directly discharged from the device body 16. In addition, two media supply containers 81a and 81b for accommodating media of different sizes are shown as media supply containers 81. However, the media supply containers 81 are not limited to these, and there may be three or more, or just one. Furthermore, a manual feeder (not shown) may be provided, and the media may be guided from the manual feeder to the transport path.

[0025] <First Fuser> The first fuser 40 of this embodiment includes, for example, a heating fuser roll 41 and a pressure fuser roll 42. Here, the heating fuser roll 41 is equipped with a heating source (not shown), such as a halogen lamp. The pressure fuser roll 42 is positioned opposite the heating fuser roll 41 and transports the medium by clamping it in the fixing area formed between the heating fuser roll 41 and the pressure fuser roll 42. Therefore, when the medium holding the unfixed toner image passes through the fixing area of ​​the first fuser 40, the unfixed toner image on the medium is fixed onto the medium by heat and pressure. In this example, the first fuser 40 is a roll-pair configuration with a heating and pressing method, but it is not limited to this and can be selected as appropriate. For example, one configuration is to hold the medium in a fixing area formed between a heating and fixing roll and a pressure fixing belt and heat and press fixing it. In this case, a pressure pad can be placed opposite the heating and fixing roll, and a pressure fixing belt can be interposed between the heating and fixing roll and the pressure pad. In this example, it is sufficient that the pressure fixing belt is rolled by the heating and fixing roll.

[0026] -Example configuration of a post-processing device- In this embodiment, the post-processing device 50, as shown in Figure 2, is provided in the middle of the media transport path 51 and includes a second fuser 60 that makes the toner image surface of the media highly glossy, and a cutting device 70 that cuts the media that has passed through the second fuser 60. In this embodiment, a second discharge receiver 88 is provided downstream of the post-processing device 50 to receive the media that has passed through the cutting device 70. Before describing the second fuser 60 in detail, we will first explain the cutting device 70.

[0027] -Cutting machine- In this embodiment, the cutting device 70 is capable of cutting the edges of the medium, for example, to produce borderless prints. Therefore, as shown in Figure 2, the cutting device 70 includes a slitter 71 and circular cutters 72 (72a, 72b). Here, the slitter 71 is a component that cuts the medium in the width direction, and the circular cutters 72 are components that cut the medium in the feed direction length. Furthermore, the cutting device 70 is equipped with a plurality of transport rolls 73, 74 for transporting the medium. In this example, the slitter 71 has a number of blades corresponding to the required number of cuts in the axial direction and cuts the material in the feeding direction while conveying it. The circular cutter 72 cuts the material by temporarily stopping the conveyance of the material and moving the upper rolling cutter along the lower blade. Alternatively, the circular cutter 72 may be provided with, for example, a roller cutter in the axial direction and cut the material while conveying it.

[0028] Furthermore, the cutting device 70 not only has the function of cutting a medium into multiple sheets (for example, four sheets), but also other functions. Other functions include, for example, printing one L-size image on a postcard-sized medium (100 x 150 mm) to create a borderless print. Another function is to obtain any number of L-size images (for example, photographic images taken with a digital camera). In this case, one can combine printing four images on an A4-sized medium with printing one image each on any number of postcard-sized mediums. Moreover, by making the widthwise position of the blade of the slitter 71 variable, it becomes possible to cut to various sizes such as 4-cut, 6-cut, and 8-cut.

[0029] -Basic configuration of the second fuser- The second fuser 60 has a basic configuration similar to that of the fuser device 10 shown in Figure 1(a). In other words, as shown in Figures 2 and 3, the second fuser 60 comprises a heated fuser roll 61, a conveyor fuser belt 62, a pressurized fuser roll 63, and a cooler 64. Here, the heated fixing roll 61 corresponds to the heated fixing means (see Figure 1(a)), and in this example, it has a heating source 65 inside. The conveying fixing belt 62 also corresponds to the conveying fixing means (see Figure 1(a)), and is stretched over the heated fixing roll 61 so as to be circulating. The conveying fixing belt 62 conveys the medium S in contact with the image surface of the medium S. Furthermore, the pressurized fixing roll 63 corresponds to the pressurized fixing means (see Figure 1(a)). The pressurized fixing roll 63 is positioned opposite the heated fixing roll 61, with the conveying fixing belt 62 in between. The pressurized fixing roll 63 is pressed against the heated fixing roll 61 so as to form a fixing area FA between it and the heated fixing roll 61. Furthermore, the cooler 64 corresponds to a cooling means (see Figure 1(a)) and is installed within the conveyor fixing belt 62 to cool the conveyor fixing belt 62. In this example, the cooler 64 is installed on the conveyor fixing belt 62 downstream of the fixing area FA in the conveyor direction of the medium S, and is in contact with the back surface of the medium conveying area SA of the conveyor fixing belt 62.

[0030] <Heat fixing roll> The heated fixing roll 61 has a structure in which a release layer (not shown) made of PFA tubing or the like is formed around a metal core 61a with high thermal conductivity. A heating source 65, such as a halogen lamp, is provided inside the core 61a, and the heating source 65 is controlled to heat the surface of the heated fixing roll 61 to a predetermined temperature. The heated fixing roll 61 is also rotated by a drive motor 69 (see Figure 5) and rotates in a circulating manner on the conveyor fixing belt 62.

[0031] <Conveyor fixing belt> The conveyor fixing belt 62 consists of an endless film substrate 62a made of, for example, thermosetting polyimide resin, with a highly smooth coating layer 62b made of fluororubber or silicone rubber formed on its surface. The film substrate 62a and coating layer 62b of the conveyor fixing belt 62 are selected to have appropriate thicknesses in order to maintain mechanical strength and effectively utilize thermal energy. For example, a substrate of about 75 μm with a coating layer of about 35 μm is used. Furthermore, the conveying and fixing belt 62 is stretched over the heating and fixing roll 61 and the peeling roll 67, and is designed to circulate as the heating and fixing roll 61 rotates. Here, the peeling roll 67 corresponds to a peeling means (see Figure 1(a)) that peels the medium S from the conveyor fixing belt 62. This peeling roll 67 rotates in accordance with the movement of the conveyor fixing belt 62, and as the peeling roll 67 wraps around the conveyor fixing belt 62 and stretches it, the direction of movement of the conveyor fixing belt 62 is abruptly changed. As a result, 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 roll 67 due to the rigidity of the medium S itself.

[0032] Furthermore, in this example, the conveyor fixing belt 62 is stretched over the heating fixing roll 61 and the peeling roll 67, but it is not limited to this configuration. For example, a steering roll (not shown) may be provided on the side of the conveyor fixing belt 62 that returns from the peeling roll 67 to the heating fixing roll 61. In this case, the steering roll maintains the tension of the conveyor fixing belt 62 by pressing it outward. The steering roll then corrects any misalignment that occurs when the conveyor fixing belt 62 moves in a circular motion by tilting its axial position. Here, "misalignment" refers to the phenomenon in which the conveyor fixing belt 62 moves toward one of the ends of the steering roll.

[0033] <Pressure fixing roll> On the other hand, the pressurized fixing roll 63 has a metal core 63a with high thermal conductivity, surrounded by an elastic layer 63b made of silicone rubber or the like. A release layer (not shown) similar to the release layer of the heated fixing roll 61 is formed on the surface of the elastic layer 63b. In this embodiment, a heating source 66, such as a halogen lamp, is also provided inside the core 63a of the pressurized fixing roll 63. This heating source 66 is controlled to heat the surface of the pressurized fixing roll 63 to a predetermined temperature. As a result, the medium S conveyed to the second fixing unit 60 passes through the fixing area FA between the heated fixing roll 61 and the pressurized fixing roll 63. At this time, the toner image on the medium S is heated and pressurized with the toner image surface in contact with the conveying fixing belt 62. In this example, the pressure fixing roll 63 is equipped with a heating source 66, but it goes without saying that it may also be equipped with no heating source 66.

[0034] <Cooler> In this embodiment, the cooler 64 is provided in contact with the back surface of the conveying and fixing belt 62 between the heating and fixing roll 61 and the peeling roll 67 (corresponding to the media conveying region SA). The cooler 64 contacts a portion of the media conveying region SA of the conveying and fixing belt 62, and this contact region is designated as the cooling region CA. In other words, the cooler 64 cools the conveying and fixing belt 62 by absorbing heat from the conveying and fixing belt 62 in the cooling region CA. As a result, the media S that is conveyed in close contact with the conveying and fixing belt 62 is cooled. In this embodiment, the cooler 64 corresponds to a so-called heat sink and is composed of a fin member 64a and a cover member 64b. Here, the fin member 64a has a number of heat dissipation fins that extend in a direction substantially perpendicular to the surface along the conveyor fixing belt 62. The cover member 64b is formed in a rectangular cross-section cylindrical shape so as to cover the fin member 64a. This cooler 64 forcibly releases heat from the fin member 64a by circulating air inside with a blower (not shown). Furthermore, the cooler 64 is equipped with a temperature sensor 641 (see Figure 5) on a part of the fin member 64a, for example. Based on the detection result of the temperature sensor 641, the cooler 64 is configured to turn on or off an air blower (not shown) or to adjust the strength of the airflow.

[0035] <Close transportability of the medium> In this embodiment, the measures shown in Figure 3 have been taken to ensure the cooling effect of the cooler 64. Specifically, in this example, the medium S conveyed by the conveyor fixing belt 62 is positioned in close proximity to the cooling area CA of the cooler 64. In this example, an inlet-side opposing roll 111 is provided on the surface side of the conveyor fixing belt 62 at a location corresponding to the inlet (upstream starting point A) of the cooling area CA of the cooler 64. This inlet-side opposing roll 111 is positioned in contact with the conveyor fixing belt 62 and rotates in accordance with the conveyor fixing belt 62. Furthermore, an outlet-side opposing roll 112 is provided on the surface side of the conveyor fixing belt 62 at a location corresponding to the outlet (downstream endpoint B) of the cooling area CA of the cooler 64. This outlet-side opposing roll 112 is positioned in contact with the conveyor fixing belt 62 and rotates in accordance with the conveyor fixing belt 62.

[0036] Thus, both the inlet-side opposing roll 111 and the outlet-side opposing roll 112 function as opposing rotation means. In this example, the inlet-side opposing roll 111 must be positioned at a location corresponding to the entrance of the cooling area CA. As a result, the medium S conveyed by the conveyor fixing belt 62 is drawn in by the inlet-side opposing roll 111 at the entrance of the cooling area CA so as to be in close contact with the conveyor fixing belt 62. On the other hand, the outlet-side opposing roll 112, together with the inlet-side opposing roll 111, is effective in bringing the medium S into close contact with the conveying and fixing belt 62 at two locations, front and rear, in the conveying direction of the medium S. However, although the outlet-side opposing roll 112 is provided at a location corresponding to the outlet of the cooling area CA, it is not limited to this, and may be provided upstream of the outlet of the cooling area CA.

[0037] <Selection of media> Typically, to obtain high-gloss images such as photographic images, it is preferable to use a special paper as the medium S, as shown in Figure 4(a). The special paper has a base layer L1 with moisture-proof layers L2 on both sides, and an image-receiving layer L3 on the recording surface (toner image-forming surface). This is similar in structure to photographic paper used in silver halide photography, for example. The moisture-proof layer L2 is made of an airtight resin such as polyethylene, and a thickness of a few μm is sufficient to provide the moisture-proof effect of the base layer L1. The image-receiving layer L3 is mainly composed of a thermoplastic resin such as polyester with a melting point of approximately 130°C, and is made with a layer thickness of 5 to 20 μm, preferably about 10 μm. On the other hand, the base layer L1 is made of a composition similar to ordinary paper, mainly composed of cellulose, but it is also possible to use a dedicated base layer L1 with a different composition.

[0038] Therefore, when selecting a medium S, one possible configuration is one in which a moisture-proof layer L2 is provided on both sides of the base layer L1, and an image-receiving layer L3 similar to that of toner material is provided. By using such a medium S, the following advantages can be obtained. (1) By eliminating air permeability, it is possible to prevent problems that occur when the substrate layer L1 absorbs moisture in a high-humidity environment. Examples of such problems include the substrate layer L1 stretching and curling, or the toner image being stretched and cracking. (2) The toner image can be well embedded in the image receiving layer L3, and a smooth print surface can be obtained. This is because the presence of the image receiving layer L3 melts the toner image together with the image receiving layer L3, and by applying pressure, it becomes possible to embed the toner image into the image receiving layer L3.

[0039] When using this special paper in photo print mode, fixing is performed by the second fuser 60, and as shown in Figure 4(b), the toner image is embedded in the image receiving layer L3. At this time, the surface properties of the transport fixing belt 62 of the second fuser 60 are transferred, and the surface of the image receiving layer L3 and the toner image surface become nearly uniform, resulting in a glossy image. On the other hand, Figure 4(c) shows the state in plain paper print mode where the toner image is fixed on plain paper as the medium S by the first fuser 40 only. In this case, the toner image is placed on the substrate layer L1, and the image surface is poorly glossy because the toner image protrudes.

[0040] <Peripheral structure of the second fuser> In this example, as shown in Figure 5, an inlet guide member 52 is provided near the inlet of the second fuser 60 to guide the medium S to the inlet of the second fuser 60. Furthermore, a position sensor 53 is provided to detect the position of the leading or trailing end of the medium S as it passes through the transport path 51. Furthermore, an outlet guide member 54 is provided near the outlet of the second fuser 60 to guide the medium S discharged from the outlet of the second fuser 60. A conveyor roll 55 is provided downstream of this outlet guide member 54. Furthermore, in this example, in order to obtain a high-gloss image, the peeling temperature Ts of the medium S at the peeling position of the second fuser 60 is adjusted to be below a predetermined threshold temperature. For this reason, a temperature sensor 56 is provided near the peeling position of the second fuser 60 to measure the peeling temperature Ts of the medium S at the peeling position in a non-contact manner. A radiation thermometer is used as the temperature sensor 56.

[0041] -Control system for the second fuser- In this example, the control system of the second fuser 60 has a control device 150 composed of a microcomputer including various processors, as shown in Figure 5. Here, "processor" refers to a processor in a broad sense, and includes general-purpose processors (e.g., CPU: Central Processing Unit, etc.) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.). Furthermore, the control device 150 is connected to the operation panel 151 of the image forming system 15. The operation panel 151 is equipped with a start switch to initiate the image formation process on the medium S, a mode switch to specify the image formation mode such as single-sided printing, double-sided printing, or high-resolution printing, and a medium type indicator to indicate the type of medium to be used.

[0042] Furthermore, the ROM, which serves as the memory device of the control device 150, has programs installed that control the second fuser 60. These programs include power supply processing that controls the power supply to the second fuser 60, and programs that execute processing for each operating mode of the second fuser 60. The processing for each operating mode referred to here includes the fixing process in the normal operation mode and the standby process in the standby mode. In this example, the power supply process controls the amount of heating power supplied according to each operating mode of the second fuser 60. In this example, normal heating power is supplied during normal operation mode, and the supply of heating power is cut off or reduced during standby mode. Furthermore, the fixing process in normal operation mode includes heating and pressurizing in the fixing area FA and cooling by the cooler 64, which are performed on the medium S conveyed by the conveyor fixing belt 62. Furthermore, the standby process in standby mode is the process of putting the transport fixing belt 62 into standby mode when the supply of heating power to the second fixing unit 60 is cut off or reduced. In this example, the standby process employs a method of driving the transport fixing belt 62 idle in order to suppress the temperature drop of the heated portion of the transport fixing belt 62 when in standby mode. Furthermore, various detectors such as a position sensor 53 and temperature sensors 56 and 641 are connected to the control device 150. In addition, various controlled objects (drive motor 69, heating sources 65 and 66, etc.) are connected to the control device 150. 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.

[0043] -Basic operation of the image forming system- Next, the basic operation of this image forming system 15 will be described. As shown in Figure 2, each toner image produced by each image forming unit 20 (20a to 20d) is first transferred onto the intermediate transfer body 30 and transported to the secondary transfer area. Meanwhile, the multiple toner images held on the intermediate transfer body 30 are secondarily (all at once) transferred to the medium S delivered from the medium supply container 81 by the secondary transfer unit 33. The unfixed toner image transferred to the medium S is then fixed by the first fuser 40. After that, the medium S holding the fixed toner image is guided by the switching member 86 to the second discharge receiver 88 via the first discharge receiver 87 or the post-processing device 50.

[0044] In this embodiment, the switching direction of media transport by the switching member 86 is performed as follows: it differs between the plain paper print mode (low gloss print) which forms a normal image and the photo print mode (high gloss print) which forms a high gloss image such as a photograph. In plain paper printing mode, the media S, after being fixed in the first fuser 40, is discharged to the first discharge tray 87 by the switching member 86. On the other hand, in photo printing mode, the media S, after being fixed in the first fuser 40, is transported to the second fuser 60 by the switching member 86. After that, the media S is further fixed by the second fuser 60 and then discharged to the second discharge tray 88 via the cutting device 70. In particular, the cutting device 70 should be used when borderless prints such as photographic images are preferred. If cutting is not necessary, the media should be discharged to the second discharge tray 88 without cutting.

[0045] Generally, to obtain high-gloss images such as photographs, it is preferable to use a special paper as the medium S, as shown in Figure 4(a). When using this special paper in photo print mode, fixing is performed by the second fuser 60, and as shown in Figure 4(b), the toner image is embedded in the image receiving layer L3. At this time, the surface properties of the transport fixing belt 62 of the second fuser 60 are transferred, and the surface of the image receiving layer L3 and the toner image surface become nearly uniform, resulting in a glossy image.

[0046] -Normal operation mode of the second fuser- In normal operation mode, the fixing action by the second fuser 60 is performed as follows. As shown in Figure 3, the medium S, which has been guided to the post-processing device 50 via the first fuser 40, is about to enter the second fuser 60. In this state, in the second fuser 60, the heating fuser roll 61 and the pressure fuser roll 63 are heated to a temperature suitable for fixing by the heating sources 65 and 66, respectively. The conveyor fuser belt 62 is also in a state of circulating rotation in accordance with the driving rotation of the heating fuser roll 61. Furthermore, the cooler 64 is in a standby state where it performs cooling operations by driving the air blower. In this state, the medium S is heated and pressurized in the fixing area FA of the second fuser 60 and then transported by the conveyor fixing belt 62. After the heated medium S is cooled by the cooler 64, it is peeled off at the peeling position of the second fuser 60. Therefore, the second fuser 60 performs a series of fixing processes, including heating and pressurizing followed by cooling. As a result, by using the special paper shown in Figure 4 as the medium S, it is possible to obtain high-gloss images similar to photographic images.

[0047] -Standby mode for the second fuser- <Necessity of standby mode> In this embodiment, the image forming system 15 is equipped with two fusers (a first fuser 40 and a second fuser 60). Since the first fuser 40 and the second fuser 60 each have a heating source, they require a certain amount of heating power during startup (warm-up). In such situations, the image forming system 15 often has a defined maximum allowable power limit that can be used simultaneously. In this case, for example, when the first fuser 40 and the second fuser 60 are started up simultaneously, the heating power for each will be supplied simultaneously. In this case, since the amount of heating power supplied for each will be relatively large, it is possible that the allowable power will be exceeded. To resolve this situation, an exclusive control method may be adopted when supplying heating power to the first fuser 40 and the second fuser 60. This exclusive control method cuts off the supply of heating power to the other fuser when heating power is supplied to one of the two fusers. For example, the second fuser 60, which has a slower startup time, is started up first, and the first fuser 40, which has a faster startup time, is started up after the second fuser 60 has started up. In this case, while the first fuser 40 is starting up, the supply of heating power to the second fuser 60 is cut off, and the second fuser 60 enters a standby mode to prepare for normal operation.

[0048] In this example, the first fuser 40 or the second fuser 60 will also enter standby mode if the power supply for heating to the first fuser 40 or the second fuser 60 is reduced. Here, for example, the case in which the power supply for heating to the second fuser 60 is reduced is described as follows. For example, in the image forming system 15, when the plain paper print mode is selected, only the first fuser 40 is used. During this time, if the second fuser 60 is driven in normal operation mode, the transport fuser belt 62 alone will rotate idle, repeatedly heating and cooling, resulting in wasted power. Therefore, in this example, a method is adopted in which the power supply for heating to the second fuser 60 is reduced and the system enters standby mode as one of the standby modes. As a result, when the power supply for heating to the second fuser 60 is reduced in standby mode, it is possible to reduce power consumption compared to the normal operation mode. However, in standby mode, a method is generally employed in which the conveyor fixing belt 62 is driven to rotate idle in a predetermined direction. However, with this method, if the supply of heating power is cut off or reduced, the temperature of the conveyor fixing belt 62 will drop. Specifically, the conveyor fixing belt 62 itself is cooled by the cooler 64, and the cooled conveyor fixing belt 62 comes into contact with the heating fixing roll 61, lowering its temperature. As a result, when transitioning from standby mode to normal operation mode, a large amount of heating power is required to supply the second fixing unit 60.

[0049] <Example of operation in standby mode of the second fuser> The operation of the second fuser in standby mode will be explained below based on the flowchart shown in Figure 6. In Figure 6, if the power supply for heating to the second fuser 60 is not interrupted or reduced, the second fuser 60 maintains its normal operating mode. On the other hand, if the power supply for heating to the second fuser 60 is interrupted or reduced, the second fuser 60 will switch to standby mode. In this example, the control device 150 then shuts off or reduces the power supply to the heating sources 65 and 66 of the heating and fixing roll 61 and the pressure fixing roll 63, respectively. In parallel with this, the control device 150 stops the drive of the conveyor fixing belt 62 and drives the conveyor fixing belt 62 to rotate freely in the reverse direction, as shown in Figure 7(a).

[0050] In this state, the heating and fixing roll 61 is driven to rotate in the reverse direction, and the conveying and fixing belt 62 rotates and moves in the reverse direction. At this time, the conveying and fixing belt 62 includes not only the heated portion 62h but also the portion 62c cooled by the cooler 64. Here, "heated portion 62h" includes the contact area CN by the heated fixing roll 61 and the area heated by the heated fixing roll 61 before reaching the cooler 64. "Cooled portion 62c" refers to the portion of the conveyor fixing belt 62 other than the heated portion 62h. Specifically, it refers to the portion of the conveyor fixing belt 62 that is passing through or has passed through the cooling area CA by the cooler 64. In Figures 7(a) to (d), the heated portion 62h is indicated by hatching with an "x" mark, and the cooled portion 62c is indicated by white outline.

[0051] Subsequently, as shown in Figure 7(b), the control device 150 stops the cooled portion 62c of the conveyor fixing belt 62 at a first position P1. Here, the "first position P1" is selected as the position just before reaching the contact area CN (see Figure 7(a)) by the heated fixing roll 61. At this time, the control device 150 has distance information J1 in advance from the entrance of the cooling area CA by the cooler 64 to the first position P1. Therefore, based on the distance information J1, the control device 150 rotates and stops the heated fixing roll 61 in the reverse direction, and moves the stopped conveyor fixing belt 62 by a predetermined amount. In this state, the cooled portion 62c of the conveyor fixing belt 62 does not exceed the first position P1 and therefore does not reach the contact area CN of the heated fixing roll 61. For this reason, there is no concern that the cooled portion 62c of the conveyor fixing belt 62 will lower the temperature of the heated fixing roll 61 and the pressure fixing roll 63. On the other hand, when the conveyor fixing belt 62 rotates and moves in the opposite direction, the heated portion 62h of the lower belt portion of the conveyor fixing belt 62 rotates and moves in the opposite direction. As a result, the heated portion 62h of the conveyor fixing belt 62 stops in a state where it extends beyond the contact area CN of the heating fixing roll 61.

[0052] Subsequently, as shown in Figure 7(b), the control device 150 drives the conveyor fixing belt 62 to rotate freely in the forward direction. At this time, the heating and fixing roll 61 is driven to rotate in the forward direction, and the conveyor fixing belt 62 rotates and moves in the forward direction. After this, the control device 150 stops the heated portion 62h of the conveyor fixing belt 62 at the second position P2. The "second position P2" is selected as the position just before reaching the cooling area CA provided by the cooler 64. At this time, the control device 150 has distance information J2 stored in advance from the first position P1 to the second position P2. Therefore, based on the distance information J2, the control device 150 rotates and stops the heated fixing roll 61 in the forward direction, and moves the conveyor fixing belt 62 by a predetermined amount. In this state, the heated portion 62h of the conveyor fixing belt 62 does not exceed the second position P2, and therefore does not reach the cooling region CA of the cooler 64. For this reason, there is no concern that the heated portion 62h of the conveyor fixing belt 62 will be cooled by the cooler 64.

[0053] On the other hand, when the conveyor fixing belt 62 rotates and moves in the forward direction, the protruding heated portion 62h in the lower belt portion of the conveyor fixing belt 62 rotates and moves in the forward direction. At this time, the lower belt portion of the conveyor fixing belt 62 has a cooled portion 62c adjacent to the protruding heated portion 62h. However, in this example, the cooled portion 62c does not reach the contact area CN of the heating fixing roll 61. To elaborate on this point, it is as follows: The amount of forward movement of the conveyor fixing belt 62 mentioned above is based on distance information J2 between the first position P1 and the second position P2. In contrast, the length dimension of the protruding heated portion 62h is based on distance information J1 between the entrance of the cooling area CA and the first position P1. Here, distance information J1 is longer than distance information J2 by ​​the length between the entrance of the cooling area CA and the second position P2. Therefore, even if the protruding heated portion 62h rotates and moves in the forward direction, the cooled portion 62c does not reach the contact area CN of the heating fixing roll 61. Therefore, there is no concern that the temperature of the heated fixing roll 61 will decrease due to the cooled portion 62c of the conveyor fixing belt 62.

[0054] Subsequently, as shown in Figure 7(c), the control device 150 drives the conveyor fixing belt 62, which has stopped at the second position P2, to rotate in the reverse direction. At this time, the control device 150 drives the heating fixing roll 61 to rotate in the reverse direction and stops it based on the distance information J2. As a result, the cooled portion 62c of the conveyor fixing belt 62 rotates and moves in the reverse direction and stops at the first position P1. From this point onward, as shown in Figure 7(d), the control device 150 drives the conveyor fixing belt 62 to rotate freely in both forward and reverse directions, using the first position P1 and the second position P2 as stopping references.

[0055] In this manner, the forward and reverse idle rotation drive of the conveyor fixing belt 62 is performed so that the heated portion 62h is in contact with the heated fixing roll 61. Therefore, the heated portion 62h of the conveyor fixing belt 62 does not pass through the cooling region CA provided by the cooler 64, and does not experience an unnecessary temperature drop. Consequently, the heated fixing roll 61 and the pressure fixing roll 63 do not experience a temperature drop associated with the idle rotation drive of the conveyor fixing belt 62. Alternatively, the forward and reverse idle rotation drive of the conveyor fixing belt 62 is performed in such a way that the cooled portion 62c does not reach the contact area CN of the heated fixing roll 61. Therefore, the heated fixing roll 61 is not cooled by the cooled portion 62c of the conveyor fixing belt 62. As a result, the heated fixing roll 61 does not experience an unnecessary temperature drop.

[0056] This forward and reverse idle rotation drive of the conveyor fixing belt 62 continues until the standby mode is released. In this example, the following are some cases in which the standby mode of the second fuser 60 may be canceled. (1) When the first fuser 40 enters standby mode (2) When the medium S to be fixed to the second fuser 60 is transported and passes through a predetermined position Furthermore, when the standby mode is deactivated, the control device 150 switches to normal operation mode for the second fuser 60.

[0057] ◎Transformation form 1 In Embodiment 1, the conveyor fixing belt 62 is configured to perform forward and reverse idle rotation drive using the first position P1 and the second position P2 as stopping references when in standby mode. However, the behavior of the conveyor fixing belt 62 in stop mode is not limited to this, and may be changed, for example, as in the modified form 1. Figure 8 is a flowchart showing the drive control process of the second fuser according to deformation form 1. In the same figure, if the power supply for heating to the second fuser 60 is not interrupted or reduced, the second fuser 60 maintains its normal operating mode. On the other hand, if the power supply for heating to the second fuser 60 is interrupted or reduced, the second fuser 60 will switch to standby mode. When the system switches to standby mode, the control device 150 first executes the following processes (1) to (4), in substantially the same manner as in Embodiment 1. (1) Cut off or reduce the power supply to the respective heating sources 65 and 66 of the heated fixing roll 61 and the pressurized fixing roll 63. (2) Stop the drive of the conveyor fixing belt 62 and drive the conveyor fixing belt 62 in the reverse direction to idle (see Figure 9(a)). (3) The cooled portion 62c of the conveyor fixing belt 62 is stopped at the first position P1 (see Figure 9(b)). At this time, in the upper belt portion of the conveyor fixing belt 62, the cooled portion 62c does not exceed the first position P1 and therefore does not reach the contact area CN by the heated fixing roll 61. In the lower belt portion of the conveyor fixing belt 62, the heated portion 62h is stopped in a state where it extends beyond the contact area CN by the heated fixing roll 61. (4) Drive the conveyor fixing belt 62 to rotate freely in the forward direction (see Figure 9(b)). In Figures 9(a) to (d), the heated portion 62h is indicated by hatching with an "X", and the cooled portion 62c is indicated by white outline.

[0058] Subsequently, unlike in Embodiment 1, the control device 150 stops the cooled portion 62c at a third position P3 in the lower part of the conveyor fixing belt 62. Here, the "third position P3" is selected as the position before the portion 62c cooled by the cooler 64 reaches the contact area CN by the heating fixing roll 61. At this time, the control device 150 holds distance information J3 between the tip position of the heated portion 62h that extends beyond the contact area CN by the heating fixing roll 61 and the third position P3. Here, the dimension between the tip position of the heated portion 62h that extends beyond the contact area CN and the contact area CN corresponds to distance information J1. The distance information J3 is calculated from the distance information J1 and the position information of the third position P3. In this example, the distance information J3 is shorter than the distance information J1 by the length between the third position P3 and the contact area CN. Therefore, the control device 150 rotates the heating and fixing roll 61 in the forward direction based on the distance information J3 and stops it, and moves the conveying and fixing belt 62 by a predetermined amount.

[0059] In this state, the cooled portion 62c of the lower belt portion of the conveyor fixing belt 62 does not exceed the third position P3, and therefore does not reach the contact area CN of the heated fixing roll 61. For this reason, there is no concern that the heated fixing roll 61 will experience a temperature drop due to the cooled portion 62c of the conveyor fixing belt 62. On the other hand, when the conveyor fixing belt 62 rotates and moves in the forward direction, the heated portion 62h of the upper belt portion of the conveyor fixing belt 62 rotates and moves in the forward direction. However, in this example, since the distance information J3 is shorter than the distance information J1, the heated portion 62h does not reach the cooling region CA of the cooler 64. Therefore, there is no concern that the heated portion 62h of the conveyor fixing belt 62 will experience a temperature drop due to the cooling region CA of the conveyor fixing belt 62.

[0060] Subsequently, as shown in Figure 9(c), the control device 150 drives the conveyor fixing belt 62, which has stopped at the third position P3, to rotate in the reverse direction. At this time, the control device 150 drives the heating fixing roll 61 to rotate in the reverse direction and stops it based on the distance information J3. As a result, the cooled portion 62c of the conveyor fixing belt 62 rotates and moves in the reverse direction and stops at the first position P1. From this point onward, as shown in Figure 9(d), the control device 150 drives the conveyor fixing belt 62 to rotate freely in both forward and reverse directions, using the first position P1 and the third position P3 as stopping references.

[0061] Thus, in this example, the forward and reverse idle rotation drive of the conveyor fixing belt 62 is performed in such a way that the heated portion 62h does not come into contact with the cooling region CA provided by the cooler 64. Therefore, the heated portion 62h does not pass through the cooling region CA provided by the cooler 64, and does not experience an unnecessary temperature drop. Furthermore, the forward and reverse idle rotation drive of the conveyor fixing belt 62 is performed in such a way that the cooled portion 62c does not come into contact with the contact area CN of the heated fixing roll 61. As a result, the heated fixing roll 61 is not cooled by the cooled portion 62c, and its temperature does not drop unnecessarily. This forward and reverse idle rotation drive of the conveyor fixing belt 62 continues, as in Embodiment 1, until the standby mode is released. Furthermore, similar to the first embodiment, when the standby mode is released, the control device 150 switches to normal operation mode for the second fuser 60.

[0062] ◎Embodiment 2 Figure 10 shows the main parts of the second fuser according to Embodiment 2. In the figure, the basic configuration of the second fuser 60 according to Embodiment 2 is substantially the same as that of Embodiment 1. However, in this example, the processing process in standby mode of the second fuser 60 differs in part due to the difference in the configuration of the pressure fixing roll 63. Components similar to those in Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and their detailed descriptions are omitted here. In this example, the second fuser 60 includes a heated fuser roll 61, a conveyor fuser belt 62, a pressurized fuser roll 63, and a cooler 64. In particular, in this example, unlike in Embodiment 1, the pressure fixing roll 63 does not have a heating source 66 inside the core 63a. The pressure fixing roll 63 is equipped with a contact / separation mechanism 130 as a means for moving the pressure fixing roll 63 toward and away from the pressure fixing roll 63. This contact / separation mechanism 130 moves the pressure fixing roll 63 toward and away from a contact position in the fixing area FA where it contacts the conveyor fixing belt 62, and a non-contact position away from this contact position. In this example, the contact / separation mechanism 130 can be appropriately selected as long as it moves the pressure fixing roll 63 toward and away from the contact position. For example, a method can be adopted in which the bearing member of the pressure fixing roll 63 is supported by a movable support member, and the position of the movable support member is changed by an eccentric cam member rotated by a drive motor.

[0063] In this example, the control device 150 (see Figure 5) drives and controls the second fuser 60 according to the flowchart shown in Figure 11. If the power supply for heating to the second fuser 60 is not interrupted or reduced, the second fuser 60 will be maintained in normal operation mode. On the other hand, if the power supply for heating to the second fuser 60 is interrupted or reduced, the second fuser 60 will switch to standby mode. When the system switches to standby mode, the control device 150 executes the following processes (1) to (7). Here, Figures 12(a) to (d) schematically show the behavior of the second fuser 60 in standby mode. In Figures 12(a) to (d), the heated portion 62h is shown with hatching using an "x" mark, and the cooled portion 62c is shown in white.

[0064] (1) The power supply to the heating source 65 of the heating fixing roll 61 is cut off or reduced. (2) The drive of the transport fixing belt 62 is stopped, and the pressure fixing roll 63 that was in contact with the transport fixing belt 62 is moved to a non-contact position (see Figure 12(a)). (3) Thereafter, the conveyance and fixing belt 62 is driven to rotate idly in the reverse direction, and the cooled portion 62c of the conveyance and fixing belt 62 is stopped at the first position P1 (see Fig. 12(b)). At this time, in the upper belt portion of the conveyance and fixing belt 62, since the cooled portion 62c does not exceed the first position P1, it does not reach the contact area CN by the heating and fixing roll 61. Further, the heated portion 62h that has passed through the contact area CN moves while contacting the heating and fixing roll 61, but does not contact the pressure and fixing roll 63. In this state, usually, the pressure and fixing roll 63 without a heating source is likely to be at a lower temperature than the heated portion 62h. However, since the heated portion 62h is not in contact with the pressure and fixing roll 63, it is not cooled by the pressure and fixing roll 63. Also, in the lower belt portion of the conveyance and fixing belt 62, the heated portion 62h stops in a state where it protrudes from the contact area CN by the heating and fixing roll 61 by the distance information J1.

[0065] (4) Thereafter, the conveyance and fixing belt 62 is driven to rotate idly in the forward direction, and the heated portion 62h of the conveyance and fixing belt 62 is stopped at the second position P2 (see Fig. 12(c)). At this time, in the upper belt portion of the conveyance and fixing belt 62, the heated portion 62h moves forward by the distance information J2 (<J1) and stops. However, since the heated portion 62h does not exceed the second position P2, it does not reach the cooling area CA by the cooler 64. Further, the heated portion 62h moves while contacting the heating and fixing roll 61, but does not contact the pressure and fixing roll 63. Therefore, the heated portion 62h is not cooled by the cooler 64 or the pressure and fixing roll 63. On the other hand, in the lower belt portion of the conveyance and fixing belt 62, the protruding heated portion 62h rotates and moves forward by the distance information J2. At this time, the cooled portion 62c does not reach the contact area CN of the heating and fixing roll 61, and the heating and fixing roll 61 is not cooled.

[0066] (5) After this, the conveyor fixing belt 62 is driven to rotate freely in the reverse direction, and the heated portion 62h of the conveyor fixing belt 62 is stopped at the first position P1 (see Figure 12(d)). At this time, the heated portion 62h of the conveyor fixing belt 62 moves in contact with the heated fixing roll 61, but moves without contact with the pressurized fixing roll 63. Also, the cooled portion 62c of the conveyor fixing belt 62 does not come into contact with the heated fixing roll 61. (6) From this point onward, the conveyor fixing belt 62 is driven to rotate freely in both forward and reverse directions, using the first position P1 and the second position P2 as stopping references (Figure 12(d)). During this time, neither the cooler 64 nor the pressure fixing roll 63 cools the heated portion 62h of the conveyor fixing belt 62. Furthermore, the cooled portion 62c of the conveyor fixing belt 62 does not come into contact with the heating fixing roll 61. Therefore, the heated portion 62h of the conveyor fixing belt 62 is not unnecessarily cooled by the heating fixing roll 61. This forward and reverse idle rotation drive of the conveyor fixing belt 62 continues, as in Embodiment 1, until the standby mode is released.

[0067] (7) When the standby mode is deactivated, the pressure fixing roll 63 is moved to the contact position, and then the second fixing unit 60 is switched to normal operation mode. In Embodiment 2, the forward and reverse idle rotation drive of the conveyor fixing belt 62 in standby mode is based on the first position P1 and the second position P2 as the stopping reference. However, it is not limited to this, and as shown in Modified Embodiment 1, the first position P1 and the third position P3 may also be used as the stopping reference. [Examples]

[0068] ◎Example 1 Example 1 embodies the second fuser according to Embodiment 1 and performs a series of drive control processes during standby mode. In this example, the second fuser according to Example 1 drives the conveyor fuser belt to rotate freely in both forward and reverse directions within a predetermined range when the heating power to the heating fuser roll is cut off. In this example, the conveyor fixing belt is driven to rotate freely in both forward and reverse directions at a cycle of 2 to 5 seconds so that the heated portion of the conveyor fixing belt comes into contact with the heated fixing roll. ◎Comparative Example 1 The second fuser according to Comparative Example 1 has substantially the same configuration as that of Example 1, and when the heating power to the heating fuser roll is cut off, it is driven to idle only in the normal forward direction.

[0069] For the second fuser according to Example 1 and Comparative Example 1, a series of drive control processes in standby mode are performed under the following conditions. In Example 1 and Comparative Example 1, the second fuser is started up first (warmed up), and then the first fuser is started up. While the first fuser is starting up, the heating power to the second fuser is cut off (power supply 0), and the second fuser is put into standby mode. Here, we assume that the initial temperature of the heat fixing roll during fixing is 140°C, the heating power is cut off, and the system enters standby mode. We then investigated the relationship between the standby time after cutting off the heating power (selected to be within 60 seconds) and the temperature change of the heat fixing roll, and obtained the results shown in Figure 13(a). In the figure, in Example 1, the temperature drop of the heated fixing roll was 2.5°C after a waiting time of 10 s (see Figure 13(b)) and 9.0°C after a waiting time of 30 s. In contrast, in Comparative Example 1, the temperature drop of the heated fixing roll was 9.5°C after a waiting time of 10 s and 22.5°C after a waiting time of 30 s. Thus, it was confirmed that the second fuser according to Example 1 can suppress the temperature drop of the heated fuser roll compared to the second fuser according to Comparative Example 1.

[0070] (Note) (((1))) A rotatable heating and fixing means having a heating source, A belt-shaped transport and fixing means is stretched over the heating and fixing means and provided to be circulating, and transports the medium in contact with the image surface of the medium on which the unfixed image is held, A rotatable pressurizing fixing means is positioned opposite the heating fixing means with the transport fixing means in between, and pressurizes to form a fixing area for fixing the unfixed image between itself and the heating fixing means, A cooling means is provided in contact with the back surface of the conveying and fixing means, located downstream of the fixing area in the conveying direction of the medium within the conveying area of ​​the conveying and fixing means, for cooling the conveying and fixing means. A drive control means controls the transport fixing means to perform idle rotation, repeatedly rotating in forward and reverse directions, so that when the heating fixing means is in standby mode, the power supplied to the heating source is cut off or reduced, the portion of the transport fixing means that includes the contact area that contacts the heating fixing means and the area that extends to the cooling area cooled by the cooling means comes into contact with the heating fixing means. A fixing device characterized by being equipped with the following features. (((2))) In the fixing device described in (((1))), The fixing device is characterized in that, when the drive control means is in standby mode, which cuts off or reduces the power supplied to the heating fixing means, it stops the forward rotation drive of the transport fixing means and starts the reverse idle rotation drive of the transport fixing means. (((3))) In the fixing device described in (((2))), The fixing device is characterized in that the drive control means starts the idle rotation drive in the reverse direction, then stops the portion of the transport fixing means that has been cooled by the cooling means at a first position before it reaches the contact area of ​​the heating fixing means, and then starts the idle rotation drive of the transport fixing means in the forward direction. (((4))) In the fixing device described in (((3))), The fixing device is characterized in that the drive control means starts the forward idle rotation drive of the transport fixing means, stops at a second position before the heated portion of the transport fixing means reaches the cooling area by the cooling means, then drives the transport fixing means to idle rotation in the reverse direction, and thereafter performs the forward and reverse idle rotation drive of the transport fixing means between the first position and the second position. (((5))) In the fixing device described in (((3))), The fixing device is characterized in that the drive control means starts the forward idle rotation drive of the transport fixing means, stops at a third position before the portion of the transport fixing means cooled by the cooling means reaches the contact area of ​​the heating fixing means, then drives the transport fixing means to idle rotation in the reverse direction, and thereafter performs the forward and reverse idle rotation drive of the transport fixing means between the first position and the third position. (((6))) In a fixing device described in any of (((1))) to (((5))), The fixing device is characterized in that the drive control means performs forward and reverse idle rotation driving of the conveying and fixing means so that the portion of the conveying and fixing means that is passing through or has passed through the cooling area by the cooling means does not reach the contact area by the heating and fixing means. (((7))) In the fixing device described in (((6))), The fixing device is characterized in that the drive control means performs forward and reverse idle rotation drive of the conveying and fixing means so that the portion of the conveying and fixing means heated by the heating and fixing means does not reach the cooling area of ​​the cooling means. (((8))) In a fixing device described in any of (((1))) to (((7))), The fixing device is characterized in that the pressurizing fixing means includes a contact / separation means that moves to and from a non-contact position away from a contact position that is in contact with the transport fixing means during the standby mode. (((9))) In the fixing device described in (((8))), The fixing device is characterized in that the pressurized fixing means does not have a heat source. (((10))) In a fixing device described in any of (((1))) to (((9))), A fixing device having a position detection means for detecting the position of the leading or trailing end of the medium in the transport direction, located upstream of the fixing area in the transport direction of the medium, and characterized in that the standby mode is canceled and power supply to the heating fixing means is started based on the detection result of the position detection means. (((11))) An image-making means for creating an unfixed image on a medium, A fixing device according to any one of (((1))) to (((10))) for fixing an unfixed image held on the medium, An image forming system characterized by comprising the following features.

[0071] According to the fixing device described in (((1))), when fixing an unfixed image on a medium by heating and pressurizing a belt-shaped transport fixing means and then cooling it, in standby mode in which the power supply to the heating fixing means is cut off or reduced, the transport fixing means can be rotated idle while suppressing the temperature drop of the heated transport fixing means and the heating fixing means. According to the fixing device described in (((2))), the idle rotation drive of the transport fixing means can be started immediately when in standby mode. According to the fixing device described in (((3))), when the transport fixing means is driven to rotate freely in the reverse direction, it is possible to appropriately avoid a situation in which the temperature of the heating fixing means decreases due to the part cooled by the cooling means. According to the fixing device described in (((4))), when the conveying fixing means is driven in the forward and reverse directions without moving, it is possible to appropriately avoid the conveying fixing means, which has been heated by the heating fixing means, reaching the cooling area of ​​the cooling means. According to the fixing device described in (((5))), when the conveying fixing means is driven idle in the forward and reverse directions, it is possible to appropriately avoid the conveying fixing means, which has been cooled by the cooling means, reaching the contact area with the heating fixing means. According to the fixing device described in (((6))), when the transport fixing means is driven in the forward or reverse idle direction, it is possible to avoid a situation in which the temperature of the heating fixing means is unnecessarily cooled by the transport fixing means which has been cooled by the cooling means. According to the fixing device described in (((7))), when the conveying fixing means is driven to rotate freely in the forward and reverse directions, it is possible to avoid a situation in which the temperature of the conveying fixing means, which has been heated by the heating fixing means, is unnecessarily cooled by the cooling means. According to the fixing device described in (((8))), compared to the configuration without a contact / separation means, it is possible to avoid a situation in which the temperature of the transport fixing means is unnecessarily lowered by the pressurized fixing means during standby mode. According to the fixing device described in (((9))), compared to the configuration without a contact / separation means, it is possible to avoid a situation in which the temperature of the transport fixing means unnecessarily decreases due to the pressurized fixing means, which does not have a heating source, during standby mode. According to the fixing device (((10))), when performing the normal fixing mode, the standby mode can be released at an appropriate timing and power supply to the heating fixing means can be resumed. According to the image forming system described in (((11))), when fixing an unfixed image on a medium by heating and pressurizing a belt-shaped transport and fixing means and then cooling it, an image forming system can be constructed that includes a fixing device capable of rotating the transport and fixing means while suppressing the temperature drop of the heated transport and fixing means during a standby mode in which the power supply to the heating and fixing means is cut off or reduced. [Explanation of symbols]

[0072] 1…Heating fixing means, 1a…Heating source, 2…Transport fixing means, 2h…Heated portion, 2c…Cooled portion, 3…Pressure fixing means, 4…Cooling means, 5…Peeling means, 6…Drive control means, 7…Power supply means, 8…Contact / separation means, 9…Position detection means, 10…Fixing device, 11…Image formation means, CA…Cooling area, CN…Contact area, FA…Fixing area, G…Unfixed image, S…Medium, P1…First position, P2…Second position, P3…Third position

Claims

1. A rotatable heating and fixing means having a heating source, A belt-shaped transport and fixing means is stretched over the heating and fixing means and provided to be circulating, and transports the medium in contact with the image surface of the medium on which the unfixed image is held, A rotatable pressurizing fixing means is positioned opposite the heating fixing means with the transport fixing means in between, and pressurizes to form a fixing area for fixing the unfixed image between itself and the heating fixing means, A cooling means is provided in contact with the back surface of the conveying and fixing means, located downstream of the fixing area in the conveying direction of the medium within the conveying area of ​​the conveying and fixing means, for cooling the conveying and fixing means. A drive control means controls the transport fixing means to perform idle rotation, repeatedly rotating in forward and reverse directions, so that when the heating fixing means is in standby mode, the power supplied to the heating source is cut off or reduced, the portion of the transport fixing means that includes the contact area that contacts the heating fixing means and the area that extends to the cooling area cooled by the cooling means comes into contact with the heating fixing means. A fixing device characterized by being equipped with the following features.

2. In the fixing device according to claim 1, The fixing device is characterized in that, when the drive control means is in standby mode, which cuts off or reduces the power supplied to the heating fixing means, it stops the forward rotation drive of the transport fixing means and starts the reverse idle rotation drive of the transport fixing means.

3. In the fixing device according to claim 2, The fixing device is characterized in that the drive control means starts the idle rotation drive in the reverse direction, then stops the portion of the transport fixing means that has been cooled by the cooling means at a first position before it reaches the contact area of ​​the heating fixing means, and then starts the idle rotation drive of the transport fixing means in the forward direction.

4. In the fixing device according to claim 3, The fixing device is characterized in that the drive control means starts the forward idle rotation drive of the transport fixing means, stops at a second position before the heated portion of the transport fixing means reaches the cooling area by the cooling means, then drives the transport fixing means to idle rotation in the reverse direction, and thereafter performs the forward and reverse idle rotation drive of the transport fixing means between the first position and the second position.

5. In the fixing device according to claim 3, The fixing device is characterized in that the drive control means starts the forward idle rotation drive of the transport fixing means, stops at a third position before the portion of the transport fixing means cooled by the cooling means reaches the contact area of ​​the heating fixing means, then drives the transport fixing means to idle rotation in the reverse direction, and thereafter performs the forward and reverse idle rotation drive of the transport fixing means between the first position and the third position.

6. In the fixing device according to claim 1, The fixing device is characterized in that the drive control means performs forward and reverse idle rotation driving of the conveying and fixing means so that the portion of the conveying and fixing means that is passing through or has passed through the cooling area by the cooling means does not reach the contact area by the heating and fixing means.

7. In the fixing device according to claim 6, The fixing device is characterized in that the drive control means performs forward and reverse idle rotation drive of the conveying and fixing means so that the portion of the conveying and fixing means heated by the heating and fixing means does not reach the cooling area of ​​the cooling means.

8. In the fixing device according to claim 1, The fixing device is characterized in that the pressurizing fixing means includes a contact / separation means that moves to and from a non-contact position away from a contact position that is in contact with the transport fixing means during the standby mode.

9. In the fixing device according to claim 8, The fixing device is characterized in that the pressurized fixing means does not have a heat source.

10. In the fixing device according to claim 1, A fixing device having a position detection means for detecting the position of the leading or trailing end of the medium in the transport direction, located upstream of the fixing area in the transport direction of the medium, and characterized in that the standby mode is canceled and power supply to the heating fixing means is started based on the detection result of the position detection means.

11. An image-making means for creating an unfixed image on a medium, A fixing apparatus according to any one of claims 1 to 10 for fixing an unfixed image held on the medium, An image forming system characterized by comprising the following features.

Images