JP5747795B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  In the wet electrophotographic system, toner particles (hereinafter simply referred to as “toner”) are handled in a carrier liquid. As a result, the mobility of the toner is improved, and it is possible to use a toner having a small particle diameter of 3 μm or less, which is difficult to handle in the electrophotographic system. As a result, a high-quality image can be obtained on the recording material.

  In the wet electrophotographic method, the toner and carrier liquid are contained in the liquid developer. Therefore, in order to fix the image formed by the toner formed on the recording material, the amount of heat necessary for melting the toner is liquid developed. It is necessary to reduce the amount of the carrier liquid that has penetrated into the recording material as well as being supplied to the agent. This is to prevent image defects (backing) caused by the carrier liquid penetrating the recording material.

There are various “basis weights” of recording materials. It is difficult to obtain good toner fixing quality unless appropriate heating or pressurization is performed according to the characteristics of the recording material. Here, “basis weight” is a unit indicating the thickness and quality of a recording material, and means the weight of paper per square meter, and is expressed as “g / m ² ”.

  When the recording material has a high basis weight, the heat capacity of the recording material is large, and if the recording material is not heated and pressed sufficiently, a fixing failure due to toner melting failure occurs.

  When the recording material has a low basis weight, the heat capacity of the recording material is small and the heating characteristics are good, but the rigidity of the recording material is small, so paper wrinkles are likely to occur especially at the nip portion of the high pressure contact force. . Furthermore, the light scattering property of the recording material (transparency improvement) due to the penetration of the carrier liquid into the recording material is large, and the back surface where the image on the front surface can be seen through from the back surface is likely to occur.

  Japanese Patent Application Laid-Open No. 2011-75780 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2011-75781 (Patent Document 2) have a first heating and pressing device and a second heating and pressing device, and have a low basis weight. A technique for suppressing the occurrence of wrinkles is disclosed.

JP 2011-75780 A JP 2011-75781 A

  In each of the above patent documents, it is possible to suppress the generation of wrinkles when a recording material having a low basis weight is used. However, in order to suppress the generation of wrinkles, the second heating and pressing apparatus is not used, and only the first heating and pressing apparatus is used. Therefore, the ability to volatilize the carrier liquid from the recording material becomes insufficient, and there is a possibility that a problem of see-through (backing) generated due to the carrier liquid that has penetrated into the recording material having a low basis weight may occur.

  The present invention has been made in order to solve the above-described problem. Even when a recording material having a low basis weight is used, the fluoroscopic (backing) generated due to the carrier liquid that has penetrated into the recording material. An object of the present invention is to provide a fixing device and an image forming apparatus having a configuration capable of solving the problems.

  The fixing device according to the present invention is a fixing device that heats a liquid developer image including a toner and a carrier liquid formed on a recording material, and fixes the image of the toner on the recording material. A first heating and pressing apparatus including a first nip region for conveying the recording material while heating and pressurizing the liquid developer image formed on the recording material; and more than the first heating and pressing apparatus. The second heating and pressurization including a second nip region that is disposed downstream of the recording material in the transport direction and transports the recording material while heating and pressurizing the liquid developer image formed on the recording material. The recording material is transported while heating the liquid developer image of the recording material in a non-contact manner, disposed between the apparatus and at least the first heating and pressing device and the second heating and pressing device. A non-contact heating device.

  The fixing device includes a first fixing mode for sequentially passing the recording material through the first nip region, the non-contact heating device, and the second nip region, and the recording material through the first nip region and the first nip region. The operation is performed in the second fixing mode in which the non-contact heating device is passed and the fixing pressure in the second nip region is lower than the fixing pressure in the first nip region or the second nip region is not passed. In the second fixing mode, the recording material by the non-contact heating device in the second fixing mode is longer than the heating time of the recording material by the non-contact heating device in the first fixing mode. The heating time is set longer.

  In another form, in the second fixing mode, the recording material transport speed by the non-contact heating device is slower than the recording material transport speed by the non-contact heating device in the first fixing mode. Then, the recording material is conveyed with the fixing pressure in the second nip region lower than the fixing pressure in the first nip region.

  In another embodiment, the non-contact heating device is disposed between the first heating and pressing device and the second heating and pressing device, and heats the liquid developer image of the recording material in a non-contact manner. However, the first non-contact heating device that conveys the recording material and the liquid developer image of the recording material that is disposed downstream of the first non-contact heating device in the conveyance direction of the recording material. A second non-contact heating device that conveys the recording material while heating in a non-contact manner. In the second fixing mode, the recording material passes through the first non-contact heating device. The second non-contact heating device is passed without passing through the second nip region.

  In another embodiment, the second heating and pressing apparatus has a roller, and the second non-contact heating apparatus uses the roller for transporting the recording material.

  In another form, the second heating / pressurizing device is provided so as to be movable up and down. In the second fixing mode, the second heating / pressurizing device is lowered so that the top of the roller is placed on the recording material. By using it for conveyance, the recording material is conveyed without bending from the first non-contact heating device.

  An image forming apparatus according to the present invention includes any one of the fixing devices described above.

  According to the present invention, even when a recording material having a low basis weight is used, the fixing device has a configuration capable of solving the problem of backlining caused by the carrier liquid penetrating the recording material. It is possible to provide an image forming apparatus.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to Embodiment 1. FIG. 2A and 2B are diagrams illustrating a fixing device in Embodiment 1, FIG. 3A is a diagram illustrating a schematic configuration of the fixing device in a first fixing mode, and FIG. 3B is a rear end of a recording material in the first fixing mode. It is a figure which shows the conveyance speed on the basis of a position. 2A and 2B are diagrams illustrating a fixing device in Embodiment 1, FIG. 3A is a diagram illustrating a schematic configuration of the fixing device in a second fixing mode, and FIG. 3B is a rear end of a recording material in the second fixing mode. It is a figure which shows the conveyance speed on the basis of a position. FIG. 10 is a diagram illustrating a device configuration and a first fixing mode of a fixing device according to a second embodiment. 10 is a diagram illustrating a second fixing mode of the fixing device according to Embodiment 2. FIG. FIG. 10 is a diagram illustrating another device configuration of the fixing device according to the second embodiment. FIG. 10 is a diagram illustrating a device configuration and a first fixing mode of a fixing device according to Embodiment 3. 10 is a diagram illustrating a second fixing mode of the fixing device according to Embodiment 3. FIG. FIG. 10 is a diagram illustrating another device configuration of a fixing device according to Embodiment 3. FIG. 10 is a diagram illustrating a device configuration and a first fixing mode of a fixing device according to a fourth embodiment. 10 is a diagram illustrating a second fixing mode of the fixing device according to Embodiment 4. FIG. It is a figure which shows the evaluation result in Example 1 to Example 4 and Comparative Example 1 to Comparative Example 5.

  Hereinafter, a fixing device and an image forming apparatus including the fixing device according to an embodiment of the present invention will be described with reference to the drawings. Note that in the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated. In addition, it is planned from the beginning to use the structures in the embodiments in appropriate combinations.

(Embodiment 1)
(Image forming apparatus 1000)
The main configuration of the image forming apparatus 1000 according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a schematic configuration of the image forming apparatus 1000.

  In this image forming apparatus 1000, a liquid developer image (hereinafter simply referred to as “toner image”) formed on an image carrier (photoconductor) 1 by electrophotography is transferred to a recording material P and fixed by toner. The image is fixed and the image is formed on the recording material P. The recording material P may be any member as long as it can form a toner image on the surface, such as paper or film, and can be conveyed in the image forming apparatus 1000.

  The image forming apparatus 1000 includes an image carrier 1 for carrying an image. Around the image carrier 1, a charging device 2, an exposure device 3, a liquid developing device 4, a transfer roller 5, and Cleaners 6 are sequentially arranged along the rotation direction of the image carrier 1 (arrow A in FIG. 1).

  After the image carrier 1 is charged by the charging device 2, the image carrier 1 is exposed to the position of point E in FIG. 1 by an exposure device 3 equipped with a laser emitter or the like, and the surface of the image carrier 1 is electrostatic latent. An image is formed. The liquid developing device 4 uses an electrostatic latent image as a toner image using a liquid developer in which charged toner particles are dispersed in a carrier liquid.

  The transfer roller 5 transfers the toner image on the image carrier 1 to the recording material P, and then transports the recording material P in the direction of arrow C in the figure. After the toner image 11 on the recording material P is fixed by the fixing device 2000, the recording material P is conveyed to the outside of the fixing device 2000.

  The cleaner 6 removes the residual toner on the image carrier 1 after the transfer by, for example, a mechanical force.

  As the image carrier 1, the charging device 2, the exposure device 3, the liquid developing device 4, the transfer roller 5, and the cleaner 6 used in the image forming apparatus 1000, a well-known electrophotographic technique may be arbitrarily used. Further, the toner image formed on the image carrier 1 may be transferred to the recording material P via an intermediate transfer member.

  In the image forming apparatus 1000 using the liquid developer, the toner image 11 on the image carrier 1 developed by the liquid developing apparatus 4 includes toner and carrier liquid, and is transferred to the recording material P by the transfer roller 5. When the toner image 11 is transferred to the recording material P, the carrier liquid is transferred together with the toner, and the recording material P is conveyed to the fixing device 2000.

  The fixing device 2000 removes the excess carrier liquid in the toner image 11 and obtains sufficient fixing strength of the toner on the recording material P, the first heating and pressing device 8, the non-contact heating device 10, and A second heating and pressurizing device 9 is provided. The image forming apparatus 1000 includes a control device 200 that controls operations of the first heating and pressing device 8, the non-contact heating device 10, and the second heating and pressing device 9.

(Fixing device 2000)
Next, the fixing device 2000 in the present embodiment will be described with reference to FIGS. 2A and 2B are diagrams showing a fixing device 2000 according to the present embodiment, FIG. 2A is a diagram showing a schematic configuration of the fixing device 2000 in the first fixing mode, and FIG. 2B is a recording target in the first fixing mode. It is a figure which shows the conveyance speed on the basis of the rear end position of material. FIG. 3A is a diagram illustrating a schematic configuration of the fixing device 2000 in the second fixing mode, and FIG. 3B is a diagram illustrating a conveyance speed based on the rear end position of the recording material in the second fixing mode. It is.

  Referring to FIG. 2A, the fixing device 2000 includes a first heating and pressing device 8, a non-contact heating device 10, and a second heating device from the upstream side in the conveyance direction (arrow C in the drawing) of the recording material P. A heating / pressurizing device 9 is provided.

  The first heating and pressing device 8 includes a fixing roller 81 and a pressing roller 82. A heating device using a halogen heater or the like is built in the fixing roller 81 and the pressure roller 82 (not shown). The fixing roller 81 and the pressure roller 82 form a first nip region n1 that conveys the recording material P while heating and pressing the toner image 11 formed on the recording material P.

  The second heating and pressing device 9 includes a fixing roller 91 and a pressing roller 92. A heating device using a halogen heater or the like is built in the fixing roller 91 and the pressure roller 92 (not shown). The fixing roller 91 and the pressure roller 92 form a second nip region n2 that conveys the recording material P while heating and pressing the toner image 11 formed on the recording material P.

  The nip distance (L1) between the first heating and pressing device 8 and the second heating and pressing device 9 is set to be longer than the length along the conveyance direction (C direction) of the recording material P. . FIG. 2A shows a case where the fixing rollers 81 and 91 and the pressure rollers 82 and 92 are employed for the first heating and pressing device 8 and the second heating and pressing device 9, but the present invention is limited to this configuration. Not. One or both may be constituted by a belt member stretched by a plurality of rollers.

  A non-contact heating device that conveys the recording material P while heating the toner image 11 of the recording material P in a non-contact manner between the first heating and pressure device 8 and the second heating and pressure device 9. 10 is arranged. The non-contact heating device 10 includes a transport belt 103 as a transport device for transporting the recording material P. In the conveyance path (non-contact heating unit) of the recording material P, the recording material P is heated in a non-contact state, so that the conveyance belt 103 is sandwiched (in the vertical direction in FIG. 2), non- Far infrared heaters 101 and 102 are disposed as contact heating devices.

  Although the case where a far-infrared heater is employed as the non-contact heating apparatus is shown, the present invention is not limited to the far-infrared heater, and hot air or the like may be appropriately selected. Although FIG. 2 shows the case where the conveyance belt 103 is employed as the conveyance device, a conveyance device including a recording material conveyance guide and a conveyance roller may be used.

  In the conveyance path of the recording material P, the case where the far infrared heaters 101 and 102 are arranged so as to sandwich the conveyance belt 103 is shown, but the far infrared heater (non-contact heating device) has a surface on which a toner image is formed. It may be arranged only on the (surface). The back side of the recording material P on which the toner image is not formed is not limited to non-contact heating and may be contact heating.

  When a non-contact heating device is used on the back side of the recording material P, a metal plate having a large opening, a mesh member, a wire member, or other high opening ratio is used so that the heating efficiency of the conveying belt 103 is not impaired. A constituent member may be used.

<Fixing mode>
The fixing device 2000 of the present embodiment has two fixing modes according to the basis weight of the recording material P, and each fixing mode will be described below.

  In the embodiment, the switching between the first fixing mode and the second fixing mode is performed mainly based on the basis weight of the recording material P, and may be switched by detecting the basis weight (thickness) of the recording material. Switching may be performed based on selection of a recording material by a user.

The basis weight for switching the fixing mode includes the type of the recording material P (coated paper, high-quality paper), the setting conditions (temperature and pressure) of the first heating and pressing device 8 and the second heating and pressing device 9, and the system speed. Further, since it varies depending on the liquid developer used, it cannot be generally described. For example, a basis weight of 150 g / m ² or more can be set as the first fixing mode, and less than that can be set as the second fixing mode.

Further, the basis weight for switching the fixing mode may be changed according to the single-sided printing mode and the double-sided printing mode. For example, in the single-sided printing mode, switching is performed at 150 g / m ² , and in the double-sided printing mode, the fixing mode is switched at 200 g / m ² for the first side (front side), and 150 g / m ^{2 for} the second side (back side). The fixing mode may be switched with.

The basis weight for switching the fixing mode may be set as appropriate based on fixing strength, perspective (backing), paper wrinkles, and the like. The same applies to each of the following embodiments as well as the present embodiment. In the following description, the recording material P having a large basis weight means a recording material having a basis weight of 150 g / m ² or more, and the recording material P having a small basis weight has a basis weight of 150 g / m ^2. Means less than the recording material.

  The switching of each mode is controlled based on a signal from the control device 200, and each operation of the first heating and pressing device 8, the non-contact heating device 10, and the second heating and pressing device 9 is controlled.

[First fixing mode (FIGS. 2A, 2B)]
2A and 2B, in the first fixing mode used for the recording material P having a large basis weight, the recording material P includes the first heating and pressing device 8, the non-contact heating device 10, and the like. Then, the toner image 11 formed on the recording material P is fixed by being sequentially conveyed to the second heating and pressing apparatus.

  Since the recording material P having a large basis weight has a large heat capacity, the temperature of the recording material P and the toner image 11 is not sufficient with only the first heating and pressurizing device 8, so that the toner is insufficiently melted and sufficient fixing strength is obtained. Absent. Therefore, by using the second heating and pressurizing device 9, it becomes possible to compensate for the shortage of the temperature rise.

  Here, if the interval L1 between the first heating and pressing apparatus 8 and the second heating and pressing apparatus 9 is large, the recording material P between the first heating and pressing apparatus 8 and the second heating and pressing apparatus 9 is used. The temperature drop (including the toner image 11) becomes large, and the heating temperature and pressure conditions in the first nip region n1 of the first heating and pressing device 8 and the second nip region n2 of the second heating and pressing device 9 are set. Must be set high.

  On the other hand, the interval L1 between the first heating / pressurizing device 8 and the second heating / pressurizing device 9 can be made as small as possible to suppress the temperature drop of the recording material P (including the toner image 11). However, when the distance L1 is set to be equal to or shorter than the length along the conveyance direction of the recording material P, both end portions of the recording material P are simultaneously sandwiched between the first heating and pressing device 8 and the second heating and pressing device 9, An unnecessary load may be applied to the recording material P.

  Therefore, by disposing the non-contact heating device 10 between the first heating / pressurizing device 8 and the second heating / pressurizing device 9, the first heating / pressurizing device 8 and the second heating / pressurizing device 9 are arranged. It is possible to suppress the temperature drop of the recording material P (including the toner image 11) in the meantime and obtain a sufficient fixing strength of the toner image 11 to the recording material P.

  FIG. 2B is a diagram illustrating the conveyance speed based on the rear end position of the recording material P. The recording material P passes through the first heating and pressing device 8, the non-contact heating device 10, and the second heating and pressing device 9 at a constant transport speed S1. In addition, in the first nip region n1 of the first heating / pressurizing device 8 and the second nip region n2 of the second heating / pressurizing device 9, predetermined pressurizing force and heating temperature are applied to the recording material P.

  As an example in the present embodiment, the conveyance speed S1 of the recording material P in the first fixing mode is about 300 mm / s to 1000 mm / s, and the pressure is applied in the first nip region n1 and the second nip region n2. Is about 1000 N to 5000 N, the heating temperature (roller surface temperature) is about 100 ° C. to 200 ° C., and the heating temperature (heater temperature) in the non-contact heating apparatus 10 is about 150 ° C. to 300 ° C.

[Second Fixing Mode (FIGS. 3A, 3B)]
Next, referring to FIGS. 3A and 3B, the first fixing mode (FIGS. 2A and 2B) is also used in the second fixing mode used for the recording material P having a large basis weight. The fixing device 2000 having the same apparatus configuration as that of FIG.

  In the second fixing mode used for the recording material P having a small basis weight, the recording material P is conveyed to the first heating and pressing device 8 and the non-contact heating device 10. Here, as shown in FIG. 3B, after the rear end of the recording material P passes through the first heating and pressing device 8 (second nip region n2), the conveyance belt 103 in the non-contact heating device 10 is moved. By slowing the conveyance speed (S2: S2 <S1) or temporarily stopping, the passage time of the recording material P through the non-contact heating device 10 is made longer than that in the first fixing mode.

  The recording material P after passing through the non-contact heating device 10 is transported to the second heating / pressurizing device 9 whose pressure is weaker than that of the first heating / pressurizing device 8 and formed on the recording material P. The toner image 11 thus fixed is fixed on the recording material P. The pressing force of the second heating and pressing device 9 is weakened by separating the fixing roller 91 and the pressing roller 92 (arrow U1 in FIG. 3A).

  A mechanism is provided between the fixing roller 91 and the pressure roller 92 to adjust the pressure between the fixing roller 91 and the pressure roller 92 by adjusting the distance between the two rollers. The pressing force between the fixing roller 91 and the pressure roller 92 may be a pressing force required to transport the recording material P.

  The recording material P having a small basis weight has a small heat capacity, and the temperature of the recording material P and the toner image 11 can be sufficiently heated only by the first heating and pressing device 8. A sufficient fixing strength can be obtained by melting and pressing.

  Since the recording material P with a small basis weight has a significant light scattering reduction (improvement of transparency) due to the penetration of the carrier liquid, if there is a large amount of the carrier liquid that permeates and remains in the recording material P, There is a problem of “backing” in which the toner image 11 formed on the front surface of the recording material P can be seen through.

  Therefore, for the recording material P having a small basis weight, not only the fixing strength of the toner image 11 but also the carrier liquid that has permeated the recording material P needs to be volatilized to reduce the permeation amount. It is possible to volatilize the penetrating carrier liquid of the recording material P by heating with the second heating and pressurizing device 9.

  However, since the recording material P is substantially in a sealed environment in the second nip region n2, the volatilization efficiency is low, and in addition, the rigidity of the recording material P is reduced due to heating. As a result, when the recording material P has a small basis weight, wrinkles may occur in the recording material P in the second nip region n2.

  On the other hand, the non-contact heating device 10 provided between the first heating and pressurizing device 8 and the second heating and pressurizing device 9 has an apparatus configuration that is open to the atmosphere, and can promote the volatilization of the carrier liquid. is there. Here, in order to sufficiently reduce the amount of the carrier liquid from the recording material P, a certain time is required. It is possible to lengthen the non-contact heating time by widening the interval between the first heating and pressing device 8 and the second heating and pressing device 9. However, this directly leads to an increase in the size of the fixing device.

  Therefore, in the fixing mode 2 of the fixing device 2000 in the present embodiment, the non-contact heating time is made shorter than that in the first fixing mode by lowering or temporarily stopping the conveying speed of the conveying belt 103 in the non-contact heating device 10. It is long.

  The recording material P that has passed through the non-contact heating device 10 is transported and unloaded by the second heating and pressurizing device 9. At this time, as described above, the pressure contact force of the second heating and pressurizing device 9 is reduced or separated in order to suppress the generation of wrinkles in the second heating and pressurizing device 9. Thus, in the fixing mode 2, it is possible to suppress the occurrence of backlining and paper wrinkles while ensuring a sufficient fixing strength for the recording material P having a small basis weight.

  Further, by reducing the conveyance speed of the recording material in the non-contact heating apparatus 10 in the second fixing mode, the residence time of the non-contact heating apparatus 10 for the recording material can be extended. As a result, it is possible to reduce the amount of carrier liquid that has penetrated into the recording material with the minimum size and the number of parts of the non-contact heating apparatus 10.

  As an example in the present embodiment, the conveyance speed S1 of the recording material P in the second fixing mode is about 300 mm / s to 1000 mm / s, the conveyance speed S2 is about 0 mm / s to 200 mm / s, The applied pressure in the 1 nip region n1 is about 1000N to 5000N, the heating temperature (roller surface temperature) is about 100 ° C. to 200 ° C., the applied pressure in the second nip region n2 is about 0N to 50N, and the heating temperature (roller The surface temperature is about 100 ° C. to 200 ° C., and the heating temperature (heater temperature) in the non-contact heating apparatus 10 is about 150 ° C. to 300 ° C.

(Embodiment 2)
Hereinafter, the fixing device 2000A according to the present embodiment will be described with reference to FIG. 4 to FIG. The configuration of the image forming apparatus 1000 is the same as that shown in FIG. 1, and the configuration of the fixing device is different from that in the first embodiment. Parts that are the same as or equivalent to those of fixing apparatus 2000 in the first embodiment are given the same reference numerals, and redundant description may not be repeated.

  FIG. 4 is a diagram showing a device configuration and a first fixing mode of the fixing device 2000A, FIG. 5 is a diagram showing a second fixing mode of the fixing device 2000A, and FIG. 6 is a diagram showing another device configuration of the fixing device 2000A. It is.

(Fixing device 2000A)
The fixing device 2000A in the present embodiment is provided with a second non-contact heating device 10A around the fixing roller 91 of the second heating and pressing device 9 in addition to the fixing device 2000 shown in FIGS. Yes. In the present embodiment, the non-contact heating device 10 provided between the first heating / pressurizing device 8 and the second heating / pressurizing device 9 is the first non-contact heating device 10.

The second non-contact heating device 10 </ b> A is provided with a curved first guide member 108 and second guide member 109 that are disposed along the outer peripheral surface of the fixing roller 91. A transport roller pair 106 and a path switching device 105 are provided between the first guide member 108 and the second guide member 109 and the first non-contact heating device 10. On the opposite side of the first guide member 108 and the second guide member 109 from the conveying roller pair 106, a discharge roller pair 107 is provided.
Is provided. A far-infrared heater 104 is provided outside the second guide member 109 along the second guide member 109.

  The switching of each mode is based on the signal from the control device 200. Each operation of the first heating / pressurizing device 8, the first non-contact heating device 10, the second non-contact heating device 10A, and the second heating / pressurizing device 9 is performed. Is controlled.

[First fixing mode (FIG. 4)]
The first fixing mode shown in FIG. 4 is used for the recording material P having a large basis weight as in the first fixing mode of the first embodiment, and the recording material P includes the first heating and pressing device 8 and the first fixing mode. The toner image 11 formed on the recording material P is fixed by being sequentially conveyed to the non-contact heating device 10 and the second heating and pressing device.

[Second fixing mode (FIG. 5)]
In the second fixing mode shown in FIG. 5, similar to the second fixing mode of the first embodiment, the second fixing mode is used for the recording material P having a small basis weight, and the path switching device 105 bypasses the second heating and pressing device 9. Thus, the transport route is switched. In the second fixing mode, the recording material P does not pass through the second nip region n2, and the conveyance roller pair 106, the first guide member 108, the second guide member 109, and the discharge of the second heating and pressurizing device 9 are discharged. It is conveyed to the detour path by the roller pair 107.

  The first guide member 108 is preferably provided with an opening so as not to block the radiant heat radiated from the second far-infrared heater 104 of the second non-contact heating device 10A from reaching the recording material P. Similarly, the second guide member 109 is preferably provided with an opening so as not to block the radiant heat radiated from the fixing roller 91 from reaching the recording material P.

  Even when the detour path is adopted, the conveyance speed of the recording material P is constant, but the second non-contact heating device 10A is provided in addition to the first non-contact heating device 10 to increase the non-contact heating time. doing. Moreover, since 10 A of 2nd non-contact heating apparatuses have a conveyance mechanism, it can suppress generation | occurrence | production of a wrinkle in the 2nd heating-pressing apparatus 9. FIG. Thus, in the fixing mode 2, it is possible to suppress the occurrence of backlining and paper wrinkles while ensuring a sufficient fixing strength for the recording material P having a small basis weight.

  In the second fixing mode, the second heating and pressing device 9 is used as a heating device. Thus, by using the second heating and pressurizing device 9 as a heating device that does not apply a high pressure contact force to the recording material P, the increase in the number of components is suppressed and the amount of carrier liquid that has penetrated into the recording material P is reduced. Is possible.

  In the second non-contact heating apparatus 10A, when the amount of heating heat can be covered only by the halogen lamp provided inside the fixing roller 91, the far infrared heater 104 is not provided as shown in FIG. Adoption is also possible.

(Embodiment 3)
Hereinafter, the fixing device 2000B according to the present embodiment will be described with reference to FIGS. The configuration of the image forming apparatus 1000 is the same as that shown in FIG. 1, and the configuration of the fixing device is different from that in the first embodiment. Parts that are the same as or equivalent to those of fixing apparatus 2000 in the first embodiment are given the same reference numerals, and redundant description may not be repeated.

  FIG. 7 is a diagram showing a device configuration and a first fixing mode of the fixing device 2000B, FIG. 8 is a diagram showing a second fixing mode of the fixing device 2000B, and FIG. 9 is a diagram showing another device configuration of the fixing device 2000B. It is.

(Fixing device 2000B)
The fixing device 2000B in the present embodiment is provided with a second non-contact heating device 10B around the fixing roller 91 of the second heating and pressing device 9 in addition to the fixing device 2000 shown in FIGS. Yes. In the present embodiment, the non-contact heating device 10 provided between the first heating / pressurizing device 8 and the second heating / pressurizing device 9 is the first non-contact heating device 10.

  The second non-contact heating device 10 </ b> B is provided with a curved first guide member 108 disposed along the outer peripheral surface of the fixing roller 91. A transport roller pair 106 and a path switching device 105 are provided between the first guide member 108 and the first non-contact heating device 10. A transport roller 117 is provided on the opposite side of the first guide member 108 from the transport roller pair 106. A guide member 109 is provided on the side opposite to the first guide member 108 with the conveyance roller 117 interposed therebetween.

  The switching of each mode is based on the signal from the control device 200. Each operation of the first heating / pressurizing device 8, the first non-contact heating device 10, the second non-contact heating device 10B, and the second heating / pressurizing device 9 is performed. Is controlled.

[First fixing mode (FIG. 7)]
The first fixing mode shown in FIG. 7 is used for the recording material P having a large basis weight, similar to the first fixing mode of the first embodiment, and the recording material P includes the first heating and pressing device 8 and the first fixing mode. The toner image 11 formed on the recording material P is fixed by being sequentially conveyed to the non-contact heating device 10 and the second heating and pressing device.

[Second fixing mode (FIG. 8)]
In the second fixing mode shown in FIG. 8, similarly to the second fixing mode of the first embodiment, the second fixing mode is used for the recording material P with a small basis weight, and the path switching device 105 bypasses the second heating and pressing device 9. Thus, the transport route is switched. In the second fixing mode, the recording material P does not pass through the second nip region n2, and the conveying roller pair 106 of the second heating and pressing device 9, the outer peripheral surface of the fixing roller 91, the first guide member 108, The paper is conveyed to the detour path by the discharge roller pair 107 and the guide member 109.

  At this time, the rotation direction of the fixing roller 91 is reversed from the rotation direction of the first mode, and functions as a conveying device. At this time, the pressure roller 92 reverses the rotation direction like the fixing roller 91 or is separated from the fixing roller 91.

  Even when the detour route is adopted, the conveyance speed of the recording material P is constant, but the second non-contact heating device 10B is provided in addition to the first non-contact heating device 10, so that the non-contact heating time is long. Become. Moreover, since the 2nd non-contact heating apparatus 10B has a conveyance mechanism, it can suppress generation | occurrence | production of the wrinkle in the 2nd heating and pressurizing apparatus 9. FIG. Thus, in the fixing mode 2, it is possible to suppress the occurrence of backlining and paper wrinkles while ensuring a sufficient fixing strength for the recording material P having a small basis weight.

  Further, in the second fixing mode, the second heating and pressing device 9 is used as a paper transport device. Thus, by using the second heating and pressing device 9 as a paper transport device, it is possible to suppress the increase in the number of components and achieve both the transport of the recording material P and the efficient heating.

  In the second non-contact heating apparatus 10B, when the amount of heating heat can be covered only by the far infrared heater provided inside the fixing roller 91, as shown in FIG. 9, the far infrared heater 104 is not provided. Can also be adopted.

(Embodiment 4)
Hereinafter, with reference to FIGS. 10 and 11, a fixing device 2000C according to the present embodiment will be described. The configuration of the image forming apparatus 1000 is the same as that shown in FIG. 1, and the configuration of the fixing device is different from that in the first embodiment. Parts that are the same as or equivalent to those of fixing apparatus 2000 in the first embodiment are given the same reference numerals, and redundant description may not be repeated.

  FIG. 10 is a diagram showing a device configuration and a first fixing mode of the fixing device 2000C, and FIG. 11 is a diagram showing a second fixing mode of the fixing device 2000C.

(Fixing device 2000C)
The fixing device 2000C in the present embodiment is lower than the fixing device 2000 shown in FIGS. 2 and 3 when the second heating / pressurizing device 9 is viewed downward from the conveyance path of the first non-contact heating device 10. It has a movable lifting mechanism and a second non-contact heating device 10C. In the present embodiment, the non-contact heating device 10 provided between the first heating / pressurizing device 8 and the second heating / pressurizing device 9 is the first non-contact heating device 10.

  The second non-contact heating device 10 </ b> C has a transport roller 117 that is disposed to face the top of the fixing roller 91. Further, far-infrared heaters 110 and 111 and guide members 118 and 119 are provided along the conveyance path.

  The switching of each mode is performed based on a signal from the control device 200. Each operation of the first heating and pressing device 8, the first non-contact heating device 10, the second non-contact heating device 10C, and the second heating and pressing device 9 is performed. Is controlled.

[First fixing mode (FIG. 10)]
The first fixing mode shown in FIG. 10 is used for the recording material P having a large basis weight as in the first fixing mode of the first embodiment, and the recording material P includes the first heating and pressing device 8 and the first fixing mode. The toner image 11 formed on the recording material P is fixed by being sequentially conveyed to the non-contact heating device 10 and the second heating and pressing device.

[Second fixing mode (FIG. 11)]
In the second fixing mode shown in FIG. 11, similarly to the second fixing mode of the first embodiment, it is used for the recording material P having a small basis weight, and the second heating and pressurizing device 9 is lowered and the fixing roller 91 is moved. A conveyance path passing through the top is formed. In the second fixing mode, the conveyance belt 103, the guide member 118, the top of the fixing roller 91, and the guide member 119 are located on substantially the same plane.

  The recording material P having a small basis weight is transported along the guide member 118, the top of the fixing roller 91, the transport roller 117, and the guide member 109 without passing through the second nip region n2.

  At this time, the rotation direction of the fixing roller 91 is reversed from the rotation direction of the first mode, and functions as a conveying device. At this time, the pressure roller 92 reverses the rotation direction like the fixing roller 91 or is separated from the fixing roller 91.

  Even when the second heating and pressurizing device 9 is lowered, the conveyance speed of the recording material P is constant, but in addition to the first noncontact heating device 10, the second noncontact heating device 10C is provided. The non-contact heating time is lengthened. Moreover, since the second non-contact heating device 10 </ b> C has the transport mechanism, the generation of wrinkles in the second heating and pressurizing device 9 can be suppressed. In the conveyance of the recording material P, the recording material P can be conveyed from the first non-contact heating device 10 to the second non-contact heating device 10C without being bent.

  Thus, in the fixing mode 2, it is possible to suppress the occurrence of backlining and paper wrinkles while ensuring a sufficient fixing strength for the recording material P having a small basis weight.

  In the second fixing mode, a non-contact heating device for heating the recording material P in a non-contact manner is provided on the paper path. Thus, by providing the non-contact heating device also in the transport path, the non-contact heating time can be lengthened, and the amount of carrier liquid that has penetrated into the recording material can be reliably reduced.

(Example)
Examples and comparative examples for confirming the effects of the present embodiment will be described below. Using the image forming apparatus 1000 by liquid development using the fixing device 2000 shown in the first embodiment, a coated paper having a small basis weight (OK top coat + (registered trademark), basis weight 79.1 g) is used as a recording material. / M ² , manufactured by Oji Paper Co., Ltd., hereinafter referred to as “thin paper”), and coated paper having a large basis weight (Bon Ivory (registered trademark), basis weight 360 g / m ² , manufactured by Oji Paper Co., Ltd., hereinafter referred to as “cardboard”) An image was formed on each of these. For each of the following examples and comparative examples, the fixing strength of the recording material, the perspective of the toner (backing), and the paper wrinkle were evaluated.

(Evaluation method)
Fixing strength: The printed matter after fixing was folded with the image surface facing inward, and the toner peelability of the bent portion was visually evaluated. The case where there was no practical problem with toner peeling on the image was evaluated as “A”, and the case where many toners were peeled off on the image and there were practical problems was evaluated as “B”.

  Perspective of toner (back): A black plate was placed on the image surface (front surface) of the printed material after fixing, and the image on the surface was visually evaluated from the back surface (non-image area). The case where the surface image was hardly visible was evaluated as “A”, and the case where the image was visible was evaluated as “B”.

  Paper wrinkle: The paper wrinkle of the printed material after fixing was visually evaluated. The case where there was no paper wrinkle was evaluated as “A”, and the case where paper wrinkle was generated was evaluated as “B”.

Example 1
Using the fixing device 2000 having the configuration shown in the first embodiment, thick paper was fixed in the first fixing mode and thin paper was fixed in the second fixing mode.

(Example 2)
Using the fixing device 2000A having the configuration shown in the second embodiment, the thick paper was fixed in the first fixing mode and the thin paper was fixed in the second fixing mode.

(Example 3)
Using the fixing device 2000B having the configuration shown in the third embodiment, thick paper was fixed in the first fixing mode and thin paper was fixed in the second fixing mode.

Example 4
Using the fixing device 2000C having the configuration shown in the fourth embodiment, thick paper was fixed in the first fixing mode and thin paper was fixed in the second fixing mode.

(Comparative Example 1)
Using the fixing device 2000 having the configuration shown in Embodiment 1, both thick paper and thin paper were fixed in the first fixing mode.

(Comparative Example 2)
Using the fixing device 2000 having the configuration shown in the first embodiment, both thick paper and thin paper were fixed in the second fixing mode.

(Comparative Example 3)
The fixing device 2000 having the configuration shown in the first embodiment was used, the far infrared heater was turned off, and the thick paper was fixed in the first fixing mode and the thin paper was fixed in the second fixing mode.

(Comparative Example 4)
The fixing device 2000 having the configuration shown in the first embodiment was used to fix the thick paper in the first fixing mode and the thin paper in the first fixing mode with the far-infrared heater turned off.

(Comparative Example 5)
Using the fixing device 2000 having the configuration shown in the first embodiment, the thick paper is transported and fixed in the first fixing mode and the thin paper is transported in the second fixing mode without changing the transport speed.

  In FIG. 12, the evaluation result in Example 1 to Example 4 and Comparative Example 1 to Comparative Example 5 is shown. As is apparent from the evaluation results, according to the present embodiment, the fixing device (fixing strength, see-through (back lining), paper wrinkle) is compatible with both thick paper and thin paper while suppressing the enlargement of the fixing device. You can see that it is possible.

  As described above, according to the fixing device and the image forming apparatus in the present embodiment, the first nip region n1 that conveys the recording material P while heating and pressurizing the liquid developer image 11 formed on the recording material P is provided. The first heating and pressurizing device 8 and the liquid developer image 11 formed on the recording material P and disposed on the downstream side in the transport direction of the recording material P with respect to the first heating and pressing device 8 are heated and applied. The second heating and pressurizing device 9 including the second nip region n2 that conveys the recording material P while being pressed, and at least between the first heating and pressurizing device 8 and the second heating and pressurizing device 9, A non-contact heating device 10 that conveys the recording material P while heating the liquid developer image 11 of the material P in a non-contact manner, a first heating and pressing device 8, a non-contact heating device 10, and a second heating and pressing device. And a control device 200 that controls the operation of the device 9.

  The control device 200 includes a first fixing mode for sequentially passing the recording material P through the first nip region n1, the non-contact heating device 10 and the second nip region n2 according to the basis weight of the recording material P, The recording material P is allowed to pass through the first nip region n1 and the non-contact heating device 10, and the fixing pressure in the second nip region n2 is lower than the fixing pressure in the first nip region n1, or the second nip region n2. It is possible to select the second fixing mode that does not pass through.

  In the second fixing mode, the heating time of the recording material P by the non-contact heating device 10 in the second fixing mode is longer than the heating time of the recording material P by the non-contact heating device 10 in the first fixing mode. Provided.

  In this way, by switching the fixing mode according to the basis weight of the recording material P, it is possible to satisfy an appropriate fixing quality on recording materials having greatly different basis weights without increasing the size of the fixing device. It becomes.

  Specifically, for the recording material P having a large basis weight and a large heat capacity, sufficient fixability can be obtained by toner melting by a plurality of heating and pressing devices in the first fixing mode. In the second fixing mode when the recording material P having a small basis weight and low rigidity is used, the generation of paper wrinkles due to the use of a plurality of heating and pressing devices is suppressed, and furthermore, the non-contact heating time is long. Volatilization of the carrier liquid that has penetrated into the recording material P is promoted, and an image formed on the surface by the carrier liquid that has penetrated into the recording material P that is noticeable in a recording material having a small basis weight can be seen through the back surface. Defects can be eliminated.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Image carrier (photosensitive body) 2 Charging device 3 Exposure device 4 Liquid developing device 5 Transfer roller 6 Cleaner 8 First heating and pressing device 9 Second heating and pressing device 10 Non-contact heating device (First non-contact heating device), 10A, 10B, 10C second non-contact heating device, 11 toner image, 81, 91 fixing roller, 82, 92 pressure roller, 101, 102 far infrared heater, 103 transport belt, 104 Far infrared heater, 105 path switching device, 106 transport roller pair, 107 discharge roller pair, 108 first guide member, 109 second guide member (guide member), 110, 111 far infrared heater, 117 transport roller, 118, 119 guide Member, 1000 image forming apparatus, 2000, 2000A, 2000B, 2000C fixing apparatus, n1 First nip region, n2 Second nip region, P Recording material.

Claims (6)

A fixing device that heats a liquid developer image including a toner and a carrier liquid formed on a recording material and fixes an image of the toner on the recording material,
A first heating and pressurizing device including a first nip region for conveying the recording material while heating and pressurizing the liquid developer image formed on the recording material;
The second heating / pressurizing device is disposed on the downstream side in the transport direction of the recording material and transports the recording material while heating and pressurizing the liquid developer image formed on the recording material. A second heating and pressing device including a nip region;
Non-contact which is disposed between at least the first heating and pressing apparatus and the second heating and pressing apparatus and transports the recording material while heating the liquid developer image of the recording material in a non-contact manner. A heating device,
The fixing device is
A first fixing mode in which the recording material is sequentially passed through the first nip region, the non-contact heating device, and the second nip region;
The recording material is passed through the first nip region and the non-contact heating device, and the fixing pressure in the second nip region is lower than the fixing pressure in the first nip region, or the second nip. The operation by the second fixing mode that does not pass through the area is possible,
In the second fixing mode, the heating time of the recording material by the non-contact heating device in the second fixing mode is longer than the heating time of the recording material by the non-contact heating device in the first fixing mode. The fixing device is set longer. In the second fixing mode,
The conveyance speed of the recording material by the non-contact heating device is made slower than the conveyance speed of the recording material by the non-contact heating device in the first fixing mode,
The fixing device according to claim 1, wherein the recording material is conveyed with a fixing pressure in the second nip region lower than a fixing pressure in the first nip region. The non-contact heating device is:
The first non-pressurizing device is disposed between the first heating / pressurizing device and the second heating / pressurizing device, and conveys the recording material while heating the liquid developer image of the recording material in a non-contact manner. A contact heating device;
The second non-contact heating device is disposed downstream of the first non-contact heating device in the conveyance direction of the recording material, and conveys the recording material while heating the liquid developer image of the recording material in a non-contact manner. A contact heating device,
In the second fixing mode,
The fixing device according to claim 1, wherein the recording material passes through the second non-contact heating device without passing through the second nip region after passing through the first non-contact heating device. The second heating and pressing device has a roller,
The fixing device according to claim 3, wherein the second non-contact heating device uses the roller for transporting the recording material. The second heating and pressurizing device is provided to be movable up and down,
In the second fixing mode, the recording medium is bent from the first non-contact heating device by lowering the second heating and pressing device and using the top of the roller for transporting the recording material. The fixing device according to claim 4, wherein the fixing device is conveyed without any trouble.   An image forming apparatus comprising the fixing device according to claim 1.

Images