JP2011022465A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device employing a belt member on at least one side of a heating side and a pressing side, and an image forming apparatus, which prevent an image failure by torque increase of a belt after long term use or a rotation failure of the belt. <P>SOLUTION: This fixing device F includes a first rotating body 130 to be heated and a second rotating body 201 facing it, and heats and presses a recording material and fixes a toner image to the recording material by conveying the recording material 105 holding the toner image in a fixing nip section 101 formed of the first and second rotating bodies. At least one rotating body 130 is a belt-shaped rotating body that rotates while its inner surface is slid on the other member during the fixing operation, and the inside of the belt-shaped rotating body has an application member 301 for applying a lubricant. The application member 301 comes into contact with the inner surface of the belt-shaped rotating body 130 with a timing other than gripping conveyance of the recording material 105 to the fixing nip section 101, and supplies the lubricant. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device that heats a material to be heated, and an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile machine that includes the fixing device as an image fixing unit.

  The image forming apparatus is directly or indirectly applied to the surface of a recording material (paper, printing paper, transfer material sheet, OHT sheet, glossy paper, glossy film, etc.) by an image forming process such as electrophotography, electrostatic recording, and magnetic recording. An unfixed toner image corresponding to the image information is formed by the (transfer) method. Then, the image is fixed as a permanently fixed image on the recording material surface by the fixing device.

  As a fixing device, a heat fixing method is generally used in which an unfixed toner image formed on a recording material that is a heated material is heated and melted and fixed on the recording material.

  As a fixing device of such a heat fixing system, a recording material on which an unfixed toner image is placed is passed through a contact nip portion of two heating rollers (fixing roller, pressure roller), and the toner image is melted there. A so-called heat roller fixing device for fixing on a recording material has long been used.

  On the other hand, in recent years, due to increasing demands for smaller devices, energy savings, and shorter wait times, fixing devices that use belts or films instead of fixing rollers are widely used.

  For example, in what is called an on-demand fixing device, a heating device is constituted by a thin and long substrate-like ceramic heater and a belt member that rotates in contact with the heater. In this configuration, the heater can be disposed very close to the recording material through the belt, and the recording material can be efficiently heated. Moreover, since the heat capacity of the heating device can be reduced, the wait time, which is the time required for the temperature rise, can be shortened (see, for example, Patent Documents 1 and 2).

  In addition, a belt nip fixing device using a belt instead of a pressure roller is known. In this configuration, the pressure member is in contact with the belt rear surface of the fixing nip portion, and the belt and the recording material are pressed toward the fixing roller. Even in this configuration, the wait time can be shortened by reducing the heat capacity. Further, by devising the shape of the pressure member, a wide nip width can be ensured without increasing the diameter of the fixing roller, and the fixing performance can be improved with a small apparatus (for example, Reference 3). 4).

JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-9-34291 JP 2006-251622 A

  In a fixing device using a belt, the belt often rotates while its inner surface is in contact with a planar heater or a backup member for pressurization. At that time, if the sliding friction of the contact portion is large, the belt does not rotate smoothly, the recording material cannot be normally conveyed, and the image may be distorted or a jam may occur. Further, there arises a problem that the force (torque) necessary for driving the belt to rotate exceeds the allowable torque of the motor that is the driving force source. In order to prevent them, a lubricant is generally applied to the inner surface of the belt.

  However, although no problem occurred in the initial state where the amount of the lubricant was sufficient, image distortion and an increase in torque were also confirmed as the usage time passed and the durability progressed.

  The cause of these problems is considered to be as follows.

  In other words, as the use progresses, the lubricant is lost by moving to a place other than the sliding part or the inner surface of the belt, or the amount of lubricant is gradually reduced and volatilized. Is considered to be caused by deterioration and deterioration.

  On the other hand, it is also conceivable to increase the amount of lubricant applied in the initial stage so that the necessary amount of lubricant can be secured even in advanced use. However, in such a case, in an initial stage of use, an excessive lubricant protrudes from the back surface of the belt and wraps around the surface, which may contaminate the recording material.

  In particular, in the case of an on-demand fixing device that uses a belt on the heating device side, excessive lubricant can impede heat transfer from the heater to the belt, resulting in poor fixing performance or excessive lubricant. There was also a problem that the deviation of the amount from the non-exposed portion became apparent as glossy spots in the image.

  From the above, in order to supply fresh lubricant to the belt inner surface little by little, it is conceivable to bring the lubricant application member storing the lubricant into contact with the belt inner surface.

  However, in this case, there is a problem that the heat application capacity increases due to the contact of the lubricant application member, which is a new additional member, with the inner surface of the belt, and the wait time required for temperature rise increases. In addition, since heat is taken away by the lubricant application member even during the fixing operation, there is a problem that power consumption increases and energy saving performance is lowered.

  Further, after further progress in durability, image disturbance and torque increase were confirmed, and further improvement in durability performance was demanded.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent belt-up torque after long-term use or image failure due to belt rotation failure in a fixing device that employs a belt member on at least one of the heating side and the pressure side. A fixing device and an image forming apparatus are provided.

  Another object of the present invention is to provide a fixing device and an image forming apparatus that have less influence on wait time and power consumption.

The above object is achieved by a fixing device and an image forming apparatus according to the present invention. In summary, according to the first aspect of the present invention, the first rotating body to be heated and the second rotating body opposed to the first rotating body are formed, and formed by the first and second rotating bodies. A fixing device that heats and pressurizes the recording material by conveying the recording material holding the toner image to the fixing nip portion, and fixes the toner image on the recording material.
At least one of the rotating bodies is a belt-shaped rotating body that rotates while rubbing the inner surface with other members during a fixing operation, and an application member that applies a lubricant is provided inside the belt-shaped rotating body. Provided,
There is provided a fixing device in which the coating member is in contact with the inner surface of the belt-shaped rotating body at a timing other than when the recording material is nipped and conveyed to the fixing nip portion and supplies a lubricant.

According to the second aspect of the present invention, the fixing nip portion includes the first rotating body to be heated and the second rotating body facing the first rotating body, and is formed by the first and second rotating bodies. A fixing device that heats and pressurizes the recording material to fix the toner image to the recording material by conveying the recording material holding the toner image to the recording material;
At least one of the rotating bodies is a belt-shaped rotating body that rotates while rubbing the inner surface with other members during a fixing operation, and an application member that applies a lubricant is provided inside the belt-shaped rotating body. Provided,
There is provided a fixing device in which the coating member contacts the inner surface of the belt-shaped rotating body at a timing other than during the temperature rise of the fixing device and supplies a lubricant.

  According to a third aspect of the present invention, there is provided an image forming method including means for forming a toner image on a recording material, and fixing the toner image of the recording material with the fixing device having any one of the above configurations. An apparatus is provided.

  According to the present invention, the lubricant application member comes into contact with the inner surface of the belt-shaped rotating body and supplies the lubricant at a timing other than when the recording material is nipped and conveyed to the fixing nip portion or at a timing other than the temperature rise. This configuration prevents the lubricant from being deteriorated by being exposed to high temperatures for a long period of time and the exhaustion of the lubricant, and prevents an increase in the driving torque of the fixing belt and the occurrence of image disturbance over a long period of durability. it can.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention. 1 is a schematic configuration diagram of a fixing device showing a contact state of a lubricant application member with an inner surface of a fixing belt in an embodiment of the present invention. FIG. 3 is a schematic configuration diagram of a fixing device in a comparative example in a state where a lubricant application member is always in contact with an inner surface of a fixing belt. It is a schematic block diagram which shows the pressurization state of the fixing apparatus in the other Example of this invention. FIG. 6 is a schematic configuration diagram illustrating a pressure release state of a fixing device according to another embodiment of the present invention. It is a schematic block diagram which shows the pressurization state of the fixing apparatus in the other Example of this invention. FIG. 6 is a schematic configuration diagram illustrating a pressure release state of a fixing device according to another embodiment of the present invention.

  Hereinafter, a fixing device and an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
The greatest feature of this embodiment is that the lubricant application member comes into contact with the inner surface of the belt-shaped rotating body and supplies the lubricant at a timing other than when the recording material is nipped and conveyed to the fixing nip portion.

  Hereinafter, the image forming apparatus in this embodiment will be described first, then the fixing device will be described, and then the lubricant application mechanism will be further described. Thereafter, the most characteristic part of the present embodiment will be described.

(Image forming device)
FIG. 1 is a schematic configuration diagram of an embodiment of an image forming apparatus of the present invention. In this embodiment, the image forming apparatus is an electrophotographic color image forming apparatus employing a tandem method that is particularly excellent in terms of high speed.

  In FIG. 1, Y, M, C, and K are toner image forming units for yellow, magenta, cyan, and black, respectively. Each unit includes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 1 as an image carrier, a charging device 2, a laser exposure optical system 3, a developing device 4, a cleaning device 5, and the like. It has an electrophotographic process mechanism. The photosensitive drum 1 is rotationally driven at a predetermined peripheral speed in the direction of the arrow, and a toner image corresponding to each color is formed on the surface of the photosensitive drum by a known electrophotographic image forming process.

  A transfer belt 6 that is an intermediate transfer member is suspended between a driving roller 7 and a turn roller 8, and is arranged below all the units Y to K so as to cover all units. . The transfer belt 6 is rotationally driven in a counterclockwise direction indicated by an arrow at a peripheral speed corresponding to the peripheral speed of the photosensitive drum 1.

  In each unit Y, M, C, and K, the transfer roller 9 is pressed against the lower surface of the photosensitive drum 1 with the transfer belt 6 interposed therebetween to form a transfer nip portion.

  A registration roller 10 feeds a sheet-like recording material (transfer material, paper) 105 separated and fed from a paper feeding mechanism (not shown) to a predetermined end of the transfer belt 6 on the first unit Y side. Feed at the control timing. The fed recording material 105 is electrostatically attached to the surface of the transfer belt 6 by the electrode roller 11. The transfer belt 6 holds the recording material 105 and sequentially conveys it to the transfer nips of the first to fourth units Y, M, C, and K. A bias application power source V11 for the electrode roller 11 and a transfer bias application power source V9 for each transfer roller 9 are provided, and a predetermined voltage can be applied.

  As a result, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are sequentially superimposed and transferred in the aligned state on the surface of the same recording material 105, and an unfixed full-color toner image is synthesized and formed. The

  The recording material 105 transported and passed through the transfer nip portion of the fourth unit K is separated from the transfer belt 6, introduced into the fixing device F, and subjected to a heat fixing process for an unfixed toner image to form a full-color image formed product. It is discharged and conveyed.

(Fixing device)
Next, a schematic configuration of the fixing device F in this embodiment is shown in FIG. 2 and will be described in detail. The fixing device F of the present embodiment is an on-demand fixing device.

  The fixing device F includes a heating unit 200, and the heating unit 200 includes a fixing belt 130 that is a first rotating body to be heated, and a ceramic heater 131 that is a heat source inside thereof. Heat is transmitted by bringing the ceramic heater 131 into contact with the inner surface of the fixing belt, and the fixing belt 130 is heated. Further, the fixing device F includes a pressure roller 201 that is a second rotating body facing the fixing belt 130.

  The fixing belt 130 is provided with a 250 μm silicone rubber layer 130b as an elastic layer on a base layer 130a made of stainless steel (SUS) formed into a cylindrical shape having a thickness of 50 μm and a diameter of 24 mm. Further, a PFA resin tube having a thickness of 30 μm is coated on the outside to form a release layer (surface layer) 130c. As the base layer 130a of the fixing belt 130, another metal material such as nickel or a heat resistant resin material such as polyimide can be used. The surface layer 130c can also be formed by coating a fluororesin or the like.

  The elastic layer 130b can be omitted. However, in the case of an on-demand fixing device used in a color image forming apparatus as in the present embodiment, it is not omitted in order to prevent uneven gloss of the output image. Is desirable. The reason why the thickness of the elastic layer 130b is 250 μm is as follows.

That is, by increasing the thickness of the elastic layer 130b, the effect of preventing gloss unevenness is enhanced, while heat transfer from the heater 131 to the belt surface is reduced, and the heat capacity of the fixing belt itself is further increased. Will be late. According to the study by the present inventors, the balance between the gloss unevenness and the temperature rise is good when the thickness of the elastic layer 130b is 50 to 1000 μm, preferably around 100 to 500 μm. Further, the heat capacity of this time fixing belt 130 (1 cm ² per) was approximately ^{4.19 × 10 -2 J / cm 2} · K 4.19J / cm 2 · K.

Increasing the thermal conductivity of the elastic layer 130b is also effective for shortening the temperature rise time of the fixing belt 130 and improving the fixing ability. Therefore, in this embodiment, the thermal conductivity of the elastic rubber layer 130b is about 1.0 × 10 ⁻³ cal / sec · cm · K (4.19 × 10 ⁻³ J / sec · cm · K) or more. As the silicone rubber, one having high thermal conductivity was used.

  The ceramic heater 131 serving as a heating member is formed by forming a resistance heating element pattern on a substrate made of alumina, aluminum nitride or the like molded to a length of 270 mm, a width of 10 mm, and a thickness of 0.8 mm.

  On the other hand, in order to control the fixing belt temperature and the heater temperature as control amounts to target values, a main thermistor 160 as a temperature detection element is provided inside the fixing belt in contact with the inner surface of the belt. Further, a sub-thermistor (not shown) can be provided in contact with the non-contact surface of the ceramic heater 131 with the fixing belt 130. And the calorific value (input electric power) of the ceramic heater 131 is controlled according to those detection results.

  The holder member 132 made of heat-resistant resin (liquid crystal polymer or the like) holds the ceramic heater 131 and also plays a role of guiding the running of the fixing belt 130. A metal skeleton 151 that supports the holder member 132 in the longitudinal direction is provided. The applied pressure of the total pressure of 20 kg received by the metal skeleton from the pressurizing mechanism 152 is transmitted to the heater 131 through the holder member 132 so as to be uniform in the longitudinal direction. Press contact with 201.

  The members (from the heater 131 to the metal skeleton 151) provided inside the fixing belt 130 of the heating unit 200 are collectively referred to as “contents” of the fixing belt 130.

  The pressure roller 201 is provided with a silicone rubber elastic layer 141 having a thickness of 3.5 mm on an iron cored bar 140 having an outer diameter of 18 mm, and a coating layer made of PFA and FEP having a thickness of 50 μm as a release layer thereon. The one provided with 142 was used. Therefore, the outer diameter of the pressure roller 201 was about 25 mm. The product hardness of the pressure roller 201 was 60 degrees (ASKER-C load 1 Kgf). The width of the fixing nip portion 101 formed by the deformation of the elastic layer 141 under the pressure from the ceramic heater 131 is approximately 7.5 mm. In this embodiment, the pressure roller 201 is driven by a drive motor (not shown). The operation of the drive motor is controlled by a control unit (not shown) in terms of drive, stop, and rotation speed.

  During the fixing operation, the fixing belt 130 is driven by the pressure roller 201 by a frictional force acting on a contact portion (fixing nip portion 101) with the pressure roller 201, and slidably rubs against a part of the ceramic heater 131 and the holder member 132. That is, it is slid and rotated in the direction of the arrow.

During normal image formation in which an image is formed on plain paper having a basis weight of 60 to 100 g / m ² , the pressure roller 201 is driven at a peripheral speed of 210 mm / s, and the temperature of the fixing belt 130 is 180. The energization of the heater 131 is adjusted so that the temperature becomes 0 ° C.

  After the transfer process is completed, the recording material 105 on which the unfixed toner image 104 is placed is guided to the fixing nip portion 101, by the pressure applied at the nip portion 101 and the heat transmitted from the fixing belt 130 and the heater 131. The toner is melted and fixed on the recording material 105.

  As a result of adopting the above-described configuration, the fixing device F of the present embodiment has a low heat capacity and high heat transfer, the rise of the fixing nip temperature is fast, the warm-up time is short, and the elasticity provided on the fixing belt 130. Occurrence of gloss unevenness can be prevented by the effect of the layer 130b.

(Lubricant application mechanism)
During rotation of the fixing belt 130, the heater surface and the inner surface of the fixing belt slide against each other. In order to reduce the frictional force generated at this time, fluorine oil is interposed between the two as a lubricant. As the lubricant, silicone oil or heat resistant grease made of a mixture of fluorine oil and fluorine resin fine powder can be used.

  Further, in this embodiment, a lubricant application member 301 is provided in the longitudinal direction of the inner surface of the fixing belt in order to supply fluorine oil that decreases with use. The lubricant application member is held on an application member holder 311 serving as a backup member. The application member holder 311 is longer in the longitudinal direction than the fixing belt 130 and is exposed to the outside from both ends of the fixing belt 130. Yes. Further, the exposed portion of the application member holder 311 from the fixing belt 130 is assembled and fixed to the movable lever 302. That is, the lubricant application member 301, the application member holder 311 and the movable lever 302 are configured to be integrated. Yes.

  The movable lever 302 is rotatably fixed to the frame 300 of the fixing device F by a fulcrum 303. The movable lever 302 is connected to the rotating cam 305 via a tension spring 304 at a position 310 opposite to the lubricant applying member 301 with the fulcrum 303 of the movable lever 302 as the center.

  With the configuration described above, the lubricant application member 301 can be brought into contact with or separated from the inner surface of the belt by the rotational position around the rotation shaft 306 of the rotary cam 305. The operation of the cam 305 is controlled by a cam motor and a control unit (not shown) connected thereto.

  FIG. 2 shows a state where the lubricant application member 301 is separated from the inner surface of the belt. In this state, the spring 304 is contracted and the attractive force is weak. Therefore, due to the weight of the lubricant application member 301 and the application member holder 311, the lubricant application member 301 is retracted on the metal skeleton 151 and separated from the inner surface of the belt.

  On the other hand, FIG. 3 shows a state in which the lubricant application member 301 is in contact with the inner surface of the belt. In this state, the spring 304 is stretched by the rotation of the cam 305, and the attraction force acts more strongly. Then, the force by the spring 304 becomes stronger than the weight of the lubricant application member 301 and the application member holder 311, and the movable lever 302 rotates counterclockwise around the fulcrum 303. As a result, the lubricant application member 301 comes into contact with the inner surface of the belt at a constant pressure, and fresh lubricant is supplied to the inner surface of the belt.

  The lubricant application member 301 is mainly composed of a lower holding layer 301a and an upper supply layer 301b. The retaining layer 301a is a layer that impregnates and retains most of the lubricant retained by the lubricant application member 301, and the lubricant stored in this layer exudes through the supply layer 301b and is fixed to the fixing belt. 130 is supplied to the inner surface.

  Examples of the material for forming the holding layer 301a include porous materials such as sponges and porous ceramic bodies, and woven and non-woven fabrics made of organic and inorganic fibers. Among these, a nonwoven fabric composed of polyester fibers is preferably used.

  As the supply layer 301b, a porous film of fluororesin PTFE or the like can be used. For example, the porous membrane has a thickness of 15 to 130 μm, a large number of pores having an average diameter of 0.1 to 2 μm, a surface roughness Ra of 0.5 to 2.0 μm, and a porosity of 60 to 90%. is there. Further, those having an air permeability of 3 to 1500 (seconds / 100 cc) as a Gurley number measured by a B-type Gurley type densometer are preferably used.

  The application member holder 311 was made of a liquid crystal polymer.

  Next, the contact timing of the lubricant application member 301 to the inner surface of the belt, which is a characteristic part of the present embodiment, will be described.

  In this embodiment, in order to periodically supply fresh lubricant to the inner surface of the belt, the lubricant application member 301 is brought into contact with the inner surface of the belt at every fixed rotation speed of the fixing belt 130. Specifically, the control unit stores the number of rotations of the pressure roller 201 based on the number of rotations of the drive motor, and the lubricant application member 301 is moved once every 1500 rotations of the pressure roller 201. It was made to contact the inner surface of the belt. The contact time was 5 seconds per time. The 1500 rotations of the pressure roller 201 correspond to the number of rotations when 250 sheets of A4 size paper are printed.

  Since the fixing belt 130 is driven and rotated by the rotation of the pressure roller 201, the above configuration makes it possible to supply the lubricant at every fixed number of rotations of the fixing belt 130.

  Further, in this embodiment, the contact of the lubricant applying member 301 with the inner surface of the fixing belt is performed at a timing other than during the time when the recording material is nipped and conveyed to the fixing nip portion 101. That is, even when the timing for applying the lubricant is reached, if the recording material 105 passes through the fixing nip 101, the contact of the lubricant applying member 301 with the inner surface of the belt is canceled. The recording material 105 is contacted after passing.

  Next, in the case of the present example and the case where the constant lubricant application member 301 as the comparative example shown in FIG. 4 is in contact with the inner surface of the belt, the result of comparing the occurrence of image disturbance and the state of torque increase. Is shown in Table 1.

The torque shown here is the axial torque of the pressure roller 201, and the unit is kgfcm. Also, the occurrence of image distortion is
○: Not generated Δ: Not understood by observation for a short time (2 to 3 seconds), but generated when observed well X: Assumed to be easily generated even by observation for a short time , ○ △ × indicates the level.

  As shown in Table 1, in the comparative example, the torque is low in the initial stage and image disturbance does not occur. However, the torque increases and the image disturbance occurs at 150 K sheets or more at the end of the durability period. On the other hand, in this example, although the initial torque was higher than that of the comparative example, it was stable throughout the durability, and image disturbance did not occur even after the endurance of 200K sheets. The above results can be interpreted as follows.

  That is, in the comparative example in which the lubricant applying member 301 is always in contact with the inner surface of the belt, the lubricant is abundant in the initial stage, so that the torque is lighter than that of the embodiment and image problems do not occur. On the other hand, in the second half of the endurance, the lubricant is exhausted, or the lubricant itself stored in the coating member is deteriorated by being exposed to a high temperature for a normal time, and the lubricity of the inner surface of the belt is gradually lost. On the other hand, in the present embodiment, the supply of the lubricant is performed only for a short time periodically, and at other timings, the lubricant is withdrawn from the high-temperature fixing belt 130. Further, the lubricant in the application member is not easily deteriorated.

  Next, the power consumed by the fixing device during printing in the example and the comparative example was compared under the condition of continuous paper feeding at a speed of 20 sheets / minute of A4 80 g paper.

  As a result, the example was 320 W, and the comparative example was 350 W. According to this example, it was confirmed that the power during paper feeding decreased. This result can be interpreted as follows.

  In other words, in the comparative example, the lubricant application member 301 contacts the inner surface of the belt even during paper passing, and takes heat from the belt 130. Therefore, extra power is required to compensate for the loss. On the other hand, in the present embodiment, since the application member 301 is retracted from the belt 130 during paper feeding, it is considered that the power is reduced without taking heat of the belt 130.

  As described above, according to this embodiment, the lubricant application member 301 contacts the inner surface of the belt-shaped rotating body (fixing belt) 130 at a timing other than when the recording material 105 is nipped and conveyed to the fixing nip portion 101. Supply lubricant. As a result, it is possible to prevent an increase in the driving torque of the fixing belt 130 and the occurrence of image disturbance over a long period of durability, and to reduce power consumed during the fixing operation of the recording material.

Example 2
The configuration of the fixing device of this embodiment and the configuration and operation of the lubricant application member 301 are the same as those of the first embodiment. In this embodiment, the lubricant application member 301 contacts the inner surface of the belt-shaped rotating body (fixing belt) 130 at a timing other than during the temperature rise of the fixing device, and supplies the lubricant. Yes.

  That is, in this embodiment as well as in the first embodiment, the lubricant application member 301 is brought into contact with the inner surface of the fixing belt once every 1500 rotations of the pressure roller 201, thereby preventing an increase in torque and image distortion. Is obtained. Further, in this embodiment, when the temperature of the fixing device is rising prior to the fixing operation of the recording material 105 or when the temperature of the fixing device is rising immediately after the power of the main body is turned on, the lubricant application member The contact of 301 with the inner surface of the belt is canceled. Then, the recording material 105 is brought into contact at another timing, such as after passing the recording material 105 or after the temperature raising operation is completed.

  In the case of the present embodiment and the case where the constant lubricant application member 301 shown in FIG. 4 is in contact with the inner surface of the belt as a comparative example, it is necessary to start up from a room temperature state to 180 ° C. which is a fixing temperature. The time (warm-up time) was compared. A unified comparison was performed under the condition that 600 W was input to the heater as the power at startup.

  As a result of the comparative study, the warm-up time in the comparative example was 12 seconds, whereas in this example, it was 10 seconds, which was shortened by 2 seconds, and it was confirmed that the warm-up time was shortened. This result can be interpreted as follows.

  That is, in the comparative example, since the lubricant application member 301 contacts the inner surface of the fixing belt and takes heat away even during the temperature rise, it takes extra time to increase the temperature of the fixing belt 130. On the other hand, in this embodiment, since the coating member is always retracted from the fixing belt 130 during the temperature rise, it is considered that the temperature rise of the belt was accelerated without taking heat away.

  As described above, according to this embodiment, the lubricant application member 301 contacts the inner surface of the fixing belt 130 that is a belt-shaped rotating body and supplies the lubricant at a timing other than during the temperature rise of the fixing device. . As a result, as in the first embodiment, it is possible to prevent an increase in driving torque of the fixing belt 130 and occurrence of image disturbance over a long period of durability, and to further shorten the warm-up time, which is a time required for the fixing device to rise in temperature. be able to.

Example 3
The configuration of the fixing device of this embodiment and the configuration of the lubricant application member 301 are the same as those of the first embodiment. In this embodiment, the lubricant application member 301 comes into contact with the inner surface of the fixing belt 130 and supplies the lubricant when the temperature of the belt-shaped rotating body (fixing belt 130) is reduced to a predetermined temperature or lower. It is characterized by doing.

  More specifically, in the present embodiment, as in the first embodiment, the lubricant application member 301 is brought into contact with the inner surface of the belt once every 1500 rotations of the pressure roller 201, thereby increasing torque and image distortion. The prevention effect is obtained. Further, in this embodiment, when the temperature of the fixing belt 130 is equal to or higher than a certain temperature (100 ° C. in this embodiment), the contact of the lubricant application member 301 with the inner surface of the belt is canceled. Then, the fixing belt 130 is stopped after completion of the printing operation or in a standby state, and is brought into contact with the timing when the temperature of the fixing belt 130 becomes lower than a certain temperature.

  The temperature of the belt is determined based on the temperature detected by the main thermistor 160, which is a detecting means for detecting the temperature of the belt that is in contact with the inner surface of the belt.

  Table 2 below shows the results of the image disturbance occurrence and the state of torque increase in the case of the present embodiment in the same manner as Table 1 of the first embodiment.

  Compared with the results in Example 1 in Table 1, it can be seen that the torque increase in the latter half of the endurance such as 150K and 200K is further improved in this example. The above results can be interpreted as follows.

  In other words, in this embodiment, the lubricant application member 301 is in contact with the inner surface of the belt while the temperature of the belt is always lower than a certain temperature, so that the lubricant application member 301 is not exposed to a high temperature, and as a result, the lubricant Volatilization and deterioration of the lubricant in the application member are less likely to occur. As a result, it was considered that fresh lubricant without deterioration could be sufficiently supplied even at the end of durability, and the torque increase was suppressed.

  As described above, according to the present embodiment, the lubricant application member 301 comes into contact with the inner surface of the belt-shaped rotating body at the timing when the temperature of the fixing belt 130 cools and falls below a certain temperature, and the lubricant is supplied. To do. Accordingly, it is possible to prevent the driving torque of the fixing belt 130 from increasing and the occurrence of image distortion for a longer period than in the first embodiment.

Example 4
The fixing device in this embodiment has a pressure release mechanism (separation mechanism) of the heating unit 200. When the pressure is released, the lubricant application member 301 contacts the inner surface of the belt-shaped rotating body, and the lubricant is supplied. It is characterized by supply.

  In releasing the pressure, the heating unit 200 is retracted from the pressure roller 201 to release the pressure applied to the nip portion 101 when the power of the apparatus is turned off or the image forming is not performed for a long time and the sleep state is entered. . Such an operation is generally performed well to prevent deformation of the fixing belt 130 and the pressure roller 201.

  That is, when the heating unit 200 and the pressure roller 201 are stopped in a state where they are in contact with each other with a strong pressure for a long time, the pressure roller 201 and the fixing belt 130 are deformed (set) particularly in the fixing nip portion 101. .

  Therefore, the pressure applied to the metal skeleton 151 of the heating unit 201 is released to reduce the pressure of the nip 101 or to separate the nip 101 to prevent deformation.

  In this embodiment, the lubricant application member 301 is installed on the contents of the fixing belt 130, and the lubricant application member 301 contacts the inner surface of the belt as the contents of the fixing belt 130 are moved by the pressure release operation (separation operation). Configured to do.

  Next, the lubricant application mechanism in this embodiment will be described in detail with reference to FIGS. FIG. 5 shows a pressurizing state in which a pressing force is applied to the nip portion 101, and FIG. 6 shows a state in which the heating unit 200 is retracted and the pressing force is released.

  Incidentally, since the method of releasing the mechanical pressure is widely known, it is omitted here.

  In this embodiment, the lubricant application member 301 is installed and fixed on the metal skeleton 151 that is the content of the fixing belt 130. Further, in this embodiment, the lubricant application member 301 is disposed at a position where it does not contact the inner surface of the belt in the pressurized state shown in FIG. The configuration of the lubricant application member itself was the same as in Example 1.

  Next, in the state where the fixing pressure shown in FIG. 6 is released, the pressure applied to the metal skeleton 151 is released, and the metal skeleton 151 moves upward in the figure and retracts. Accordingly, the lubricant application member 301 also moves, contacts the inner surface of the fixing belt, and supplies the lubricant to the inner surface of the belt.

  In this embodiment, the lubricant application member 301 always remains in contact with the inner surface of the belt during release of the applied pressure, but the rotation of the fixing belt 130 is stopped. It is supplied only to the location, and there is no worry that the lubricant is supplied excessively at once.

  Next, Table 3 shows the result of showing the occurrence of image disturbance in durability and the state of torque increase in the same manner as Table 1 of Example 1. Here, assuming the actual use state, assuming that the power was turned off and the sleep state occurred three times during passing 1000 sheets, the applied pressure was released and the lubricant was applied to the inner surface of the belt, and durability evaluation was performed. ing.

  As in the previous examples, good results were obtained through endurance both in terms of torque increase and image distortion.

  In this embodiment, the lubricant application member 301 is brought into contact with the inner surface of the belt by utilizing the movement of the fixing belt contents (metal skeleton) accompanying the pressure release operation. Therefore, unlike the first embodiment, there is no need to provide a contact / separation mechanism dedicated to the lubricant application member, which is advantageous in that the configuration of the apparatus can be simplified. Specifically, the movable lever 302, the tension spring 304, and the rotating cam 305 of the lubricant application mechanism in the first embodiment (FIG. 2) can be omitted.

  As described above, according to the present embodiment, the lubricant application member 301 is installed on the contents of the fixing belt 130, and accompanying the movement of the contents of the fixing belt 130 by the pressure release operation (separation operation). The lubricant application member 301 contacts the inner surface of the belt and supplies the lubricant. As a result, as in the first embodiment, the driving torque of the fixing belt 130 and the occurrence of image disturbance can be prevented over a long period of time, and the apparatus configuration can be greatly simplified.

Example 5
The fixing device in the present embodiment also has a pressure release mechanism (separation mechanism) of the heating unit 200 as in the fourth embodiment, and the lubricant application member 301 is a belt-shaped rotating body (fixing belt) 130 when the pressure is released. It is characterized in that the lubricant is supplied in contact with the inner surface.

  Further, the point that the lubricant application member 301 is installed in the contents of the fixing belt 130 is the same as in the fourth embodiment.

  On the other hand, this embodiment is characterized in that the lubricant application member 301 contacts the inner surface of the belt due to a change in the shape of the fixing belt 130 accompanying the pressure release operation (separation operation).

  The configuration of the fixing device and the lubricant application mechanism in this embodiment will be described in detail.

  FIG. 7 shows a pressing state in which a pressing force is applied to the fixing nip portion 101 in this embodiment, and FIG. 8 shows a state in which the pressing force is released.

  In this embodiment, in order to secure the fixing nip portion 101 with a smaller belt diameter, as shown in FIG. 7, a larger proportion of the belt circumferential length is deformed into a flat shape as the nip portion 101 in a pressurized state. . As a result, the entire belt has a shape that is crushed vertically. By doing in this way, while the belt diameter is 18 mm smaller than the previous examples, the nip width of 8 mm is secured.

  On the other hand, the lubricant application member 301 is installed on the side surface of the holder member 132 on the nip entrance side so as not to contact the inner surface of the belt as shown in FIG.

  Next, in the state where the fixing pressure shown in FIG. 8 is released, the force that crushes the belt into a flat surface at the fixing nip portion 101 is weakened, so that the belt deforms so as to return to its original circular shape. As a result, the lateral dimension of the belt in the drawing is compressed, the lubricant application member 301 comes into contact with the inner surface of the belt, and the lubricant is supplied.

  The state of occurrence of image disturbance and the state of torque increase in endurance in this example were the same as those in Table 3 of Example 4, and good results were obtained through endurance for both increase in torque and occurrence of image disturbance.

  As described above, in this embodiment, the lubricant application member 301 is brought into contact with the inner surface of the belt by utilizing the change in posture and shape of the fixing belt 130 accompanying the pressure release operation. Thus, as in the fourth embodiment, there is no need to provide a contact / separation mechanism dedicated to the lubricant application member as in the first embodiment, and the configuration of the apparatus can be simplified while obtaining the same effects as in the first embodiment. There is. Specifically, the movable lever 302, the tension spring 304, and the rotating cam 305 of the lubricant application mechanism in the first embodiment can be omitted.

Other Embodiments In the embodiments so far, as an example of a fixing device using a belt, an example of an on-demand fixing device in which a belt is used on the heating side and the belt is heated by a heater that rubs on the inner surface during fixing operation. Have shown. However, even in the case of a belt nip fixing device that uses a belt on the pressure side and rotates while contacting the inner surface of the belt with a back-up member for pressure, or a fixing device that uses a belt on both the upper and lower sides, A lubricant application mechanism similar to that of the embodiment can be used.

  The belt nip fixing device and the fixing device using a belt on both the upper and lower sides are well known to those skilled in the art and will not be described in detail.

  As a result, it is possible to obtain similar effects such as reduction in belt driving torque over a long period of durability, stabilization of rotation, reduction of electric power, and shortening of warm-up time. Further, by adopting the same configuration as in the fourth and fifth embodiments, the same effect can be obtained without complicating the apparatus.

  As described above, according to the configuration of the present invention, the lubricant application member 301 is a belt-shaped rotating body at a timing other than when the recording material is nipped and conveyed to the fixing nip portion 101 or at a timing other than during temperature rise. Supply the lubricant in contact with the inner surface. As a result, the lubricant is prevented from being deteriorated by being exposed to a high temperature for a long time and the lubricant is not depleted, and an increase in the driving torque of the fixing belt 130 and the occurrence of image disturbance can be prevented over a long period of durability. it can.

F fixing device 101 fixing nip 105 recording material 130 fixing belt (first rotating body)
201 Pressure roller (second rotating body)
301 Lubricant application member

Claims (9)

A recording material having a first rotating body to be heated and a second rotating body facing the first rotating body and holding a toner image is conveyed to a fixing nip portion formed by the first and second rotating bodies. In the fixing device that heats and pressurizes the recording material and fixes the toner image on the recording material,
At least one of the rotating bodies is a belt-shaped rotating body that rotates while rubbing the inner surface with other members during a fixing operation, and an application member that applies a lubricant is provided inside the belt-shaped rotating body. Provided,
The fixing device is configured to supply a lubricant by contacting the inner surface of the belt-shaped rotating body at a timing other than when the recording material is nipped and conveyed to the fixing nip portion. A recording material having a first rotating body to be heated and a second rotating body facing the first rotating body and holding a toner image is conveyed to a fixing nip portion formed by the first and second rotating bodies. In the fixing device that heats and pressurizes the recording material and fixes the toner image on the recording material,
At least one of the rotating bodies is a belt-shaped rotating body that rotates while rubbing the inner surface with other members during a fixing operation, and an application member that applies a lubricant is provided inside the belt-shaped rotating body. Provided,
The fixing device is characterized in that the coating member contacts the inner surface of the belt-shaped rotating body at a timing other than during the temperature rise of the fixing device and supplies a lubricant.   3. The fixing according to claim 1, wherein the application member contacts an inner surface of the belt-shaped rotating body and supplies a lubricant when a temperature of the belt-shaped rotating body is equal to or lower than a predetermined temperature. apparatus.   A pressure release mechanism that weakens the applied pressure between the first rotating body and the second rotating body, and the application member contacts the inner surface of the belt-shaped rotating body when the applied pressure is released; The fixing device according to claim 1, wherein a lubricant is supplied.   The application member is installed in the contents of the belt-shaped rotating body, and the application member comes into contact with the inner surface of the belt-shaped rotating body due to the movement of the contents when the applied pressure is released, and lubricant is applied. The fixing device according to claim 4, wherein the fixing device is supplied.   The application member is installed in the contents of the belt-shaped rotating body, and the application member comes into contact with the inner surface of the belt-shaped rotating body due to the deformation of the belt-shaped rotating body accompanying release of pressure. The fixing device according to claim 4, wherein a lubricant is supplied.   At least the first rotating body is the belt-shaped rotating body, and the inner surface of the belt-shaped rotating body is in pressure contact sliding with a heating member for heating the belt-shaped rotating body. The fixing device according to any one of claims 1 to 6.   At least the second rotating body is the belt-shaped rotating body, and the belt-shaped rotating body is in pressure contact with a backup member for pressurizing the belt-shaped rotating body to the first rotating body. The fixing device according to claim 1, wherein the fixing device slides.   An image forming apparatus comprising: a toner image forming unit on a recording material, wherein the toner image on the recording material is fixed by the fixing device according to claim 1.

Images