JP2007212865A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart excellent functions in high speed printing and durability by ensuring both the long-term stable application of a lubricant to the internal face of a belt and cleaning of the external face of the belt within the limited space of a belt fixing unit. <P>SOLUTION: The image forming apparatus includes: a rotatable fixing member; the rotatable endless belt disposed in contact with the fixing member; a fixing pressure member of a fixed type, disposed in contact with the internal face of the belt and pressed against the fixing member via an endless belt; and a lubricant application member, disposed in contact with the internal face of the belt. In the fixing device, a cleaning member is disposed on the external face of the belt so as to be pressed against the lubricant application member via the endless belt. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has an image forming means for forming an unfixed toner image on a recording material using an electrophotographic process or the like, and a fixing device for thermally fixing the unfixed toner image on the recording material. In addition, the present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer that obtains a hard copy.

  2. Description of the Related Art Conventionally, as a fixing device in an electrophotographic image forming apparatus, a heat roller pair type fixing device using a heating roller and a pressure roller is generally used. In recent years, as a method of increasing the heating time in the fixing device in order to increase the speed and energy saving of the device, a type of fixing device (belt type fixing device) using an endless belt as a heating member or a pressure member is also known. It has been.

Such a belt type fixing device includes a fixing device of a type in which a wide nip is formed by a fixed pressure member and pressure is applied from the inner surface of the endless belt by a sliding pressure member. In this type of fixing device, it is known to apply oil to the inner surface of the belt in order to reduce sliding friction between the sliding pressure member and the inner surface of the belt. For example, in JP-A-11-45018, a lubricant is applied to the inner surface of the endless belt. By providing a lubricant application member upstream of the pressurizing member, an appropriate amount and uniform application are performed so as not to hinder belt meandering control.
JP-A-11-45018 JP 2004-198700 A

  In the conventional oil application felt, there is a problem that the contact pressure on the inner surface of the belt is uneven, the oil application amount is unstable in time, and stable application over a long period of time is difficult. In JP-A-11-45018 and JP-A-2004-198700, an appropriate amount and a uniform amount of lubricant are applied so as not to hinder belt meandering control. However, in order to stably apply the lubricant over a long period of time, lubrication is performed. If the amount of the agent is increased, the meandering control of the belt becomes unstable, so that a method for managing an appropriate amount of lubricant is difficult, and it is not versatile for a high-speed printer that requires fixing speed and durability. Further, since pressure is applied unilaterally from the inner surface of the belt by the application felt, there is a possibility of adverse effects such as fluctuations in the wave of the belt. Further, it is not preferable that the oil wraps around the outer surface of the belt from the inner surface and that toner or paper dust from the recording paper adhere to the outer surface of the belt.

  In order to solve this problem, it is necessary to perform both long-term stable application of lubricant on the inner surface of the belt and cleaning of the outer surface of the belt. The object of the present invention is to solve this problem in a limited space of the belt fixing unit. This is achieved by providing functions with excellent high-speed printing and durability.

  The above problems are solved by the present invention as follows.

(1) A rotatable fixing member, a rotatable endless belt in contact with the fixing member, a fixed fixing pressure member in contact with the inner surface of the belt and pressurizing the fixing member through the endless belt, and an inner surface of the belt An electrophotographic belt fixing device comprising a fixing member provided with a lubricant application member in contact with a cleaning member, which is pressed against the lubricant application member via the endless belt. (2) The fixing device according to (1), wherein a lubricant intrusion prevention member is provided at an end of the cleaning member. (3) In (1), the lubricant application member is larger than the width of the endless belt. (4) In the above (1), the fiber density at the center of the lubricant application member is the highest and reaches the end. (5) In the above (1), the lubricant applying member is a rotary type and is driven to rotate with respect to the endless belt. (6) The fixing device according to (1), wherein the cleaning member is a rotary type and is driven to rotate with respect to the endless belt.

  According to the present invention described above, the stable application of the lubricant on the belt inner surface over a long period of time and ensuring the cleanliness of the outer surface of the belt can be achieved by pressing the members against each other at the opposing positions, thereby reducing the number of members. Realized while reducing. Furthermore, since the lubricant application member has a very simple configuration, unnecessary enlargement in the endless belt of the fixing device is not caused.

  Even if the position of the endless belt is fluctuated by steering, the end of the lubricant application member has a flexible structure and is pressed by the opposing member, so it can follow the endless belt. It is.

  Lubricant that wraps around the outer surface of the belt is collected at the end of the cleaning roller, and there is a lubricant intrusion prevention member at the end of the cleaning roller, so avoid the lubricant from going to the cleaning area of the recording material passage. Yes.

  With the above effects, in a limited area, it realizes management of lubricating materials and cleaning of endless belts that are essential for stable running of endless belts, and has images with high-speed printing and excellent durability. A forming apparatus can be provided.

  Hereinafter, the present invention will be described more specifically with reference to examples. Although these examples are examples of the best mode of the present invention, the present invention is not limited to these examples.

  Embodiment 1 of an image forming apparatus according to the present invention will be described with reference to FIG.

(1) `` Image forming part ''
The apparatus shown in FIG. 1 includes first, second, third, and fourth image forming portions Pa, Pb, Pc, and Pd, and toner images of different colors are latent images, development processes, and transfer processes. It is formed through.

  Each of the image forming portions Pa, Pb, Pc, and Pd includes a dedicated image carrier, in this example, the electrophotographic photosensitive drums 3a, 3b, 3c, and 3d, and the respective colors on the photosensitive drums 3a, 3b, 3c, and 3d. The toner image is formed. An intermediate transfer member 130 is installed adjacent to each photosensitive drum 3a, 3b, 3c, 3d, and the toner images of the respective colors formed on the photosensitive drums 3a, 3b, 3c, 3d are primarily transferred onto the intermediate transfer member 130. The image is transferred and transferred onto the recording material P at the secondary transfer portion. Further, the recording material P onto which the toner image has been transferred is fixed to the toner image by heating and pressurizing at the fixing unit 9 and then discharged out of the apparatus as a recorded image.

  Drum chargers 2a, 2b, 2c, 2d, developing devices 1a, 1b, 1c, 1d, primary transfer chargers 24a, 24b, 24c, 24d and cleaners are provided on the outer periphery of the photosensitive drums 3a, 3b, 3c, 3d, respectively. 4a, 4b, 4c, and 4d are provided, and a light source device and a polygon mirror (not shown) are installed above the device.

  The laser light emitted from the light source device is scanned by rotating the polygon mirror, the light beam of the scanning light is deflected by the reflection mirror, and condensed on the buses of the photosensitive drums 3a, 3b, 3c, 3d by the fθ lens. By exposing, latent images corresponding to the image signals are formed on the photosensitive drums 3a, 3b, 3c, and 3d.

  Developers 1a, 1b, 1c, and 1d are filled with a predetermined amount of cyan, magenta, yellow, and black toners as developers, respectively, by a supply device (not shown). The developing devices 1a, 1b, 1c, and 1d develop the latent images on the photosensitive drums 3a, 3b, 3c, and 3d, respectively, and visualize them as cyan toner images, magenta toner images, yellow toner images, and black toner images.

  The intermediate transfer member 130 is driven to rotate at the same peripheral speed as the photosensitive drum 3 in the direction of the arrow.

  The yellow toner image of the first color formed and supported on the photosensitive drum 3a passes through the nip portion between the photosensitive drum 3 and the intermediate transfer body 130 by the primary transfer bias applied to the intermediate transfer body 130. Intermediate transfer is performed on the outer peripheral surface of the intermediate transfer member 130 by the formed electric field and pressure.

  Reference numeral 11 denotes a secondary transfer roller, which corresponds to the intermediate transfer member 130 and is provided in parallel to be in contact with the lower surface portion. A desired secondary transfer bias is applied to the secondary transfer roller 11 by a secondary transfer bias source. Transfer of the composite color toner image superimposed and transferred onto the intermediate transfer body 130 to the recording material P passes through the registration roller 12 and the pre-transfer guide from the paper feed cassette 10 and the intermediate transfer body 130 and the secondary transfer roller 11. The recording material P is fed to the contact nip at a predetermined timing, and at the same time, a secondary transfer bias is applied from a bias power source. The composite color toner image is transferred from the intermediate transfer member 130 to the recording material P by the secondary transfer bias.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black toner image are sequentially superimposed and transferred onto the intermediate transfer body 130, and a composite color toner image corresponding to the target color image is obtained. Is formed.

  The photosensitive drums 3a, 3b, 3c, and 3d that have undergone the primary transfer are cleaned and removed of the transfer residual toner by the respective cleaners 4a, 4b, 4c, and 4d, and are subsequently prepared for forming the next latent image or less. The toner and other foreign matters remaining on the transfer belt 130 are wiped by contacting a cleaning web (nonwoven fabric) 19 with the surface of the transfer belt 130.

  The recording material P that has received the transfer of the toner image is sequentially introduced into a fixing device 9 described later, and is fixed by applying heat and pressure to the transfer material.

(2) `` Fixing part ''
FIG. 2 is an enlarged view of the fixing device according to the embodiment of the present invention. In this embodiment, a belt-type fixing device using an endless belt is used as the pressure unit. However, the endless belt is not limited to the specification of the pressure member, and the system uses an endless belt as the heating member. It is also used in a belt fixing device.

  The fixing roller 91 is formed by molding 1.5 mm of silicone rubber having a rubber hardness of 20 ° (JIS-A 1 kg load) as an elastic layer on a hollow cored bar made of Al having an outer diameter of 77.0 mm, and having a thickness of 30 to 100 μm on the surface thereof. A fixing roller having an outer diameter of φ80 mm covered with a PFA tube was used.

  The fixing roller 91 has a halogen heater 95 as a heating source inside, and is adjusted to 180 ° C. by a temperature sensor (not shown) and a temperature control circuit (not shown).

  The endless belt 92 is an endless belt stretched around a plurality of rollers 93, 96, and 97, and is pressed against the fixing roller 91 by a pressure member from within the belt.

  The endless belt 92 covers a surface of a base material made of a resin such as polyimide or a metal such as nickel, and an elastic body layer such as silicone rubber or fluorine rubber, and further, a fluorine release layer such as FRP, PFA or PTFE is formed thereon as a release layer. You may have resin, the rubber which mixed them, etc.

  The separation roller 93 is a roller made of a metal such as Fe or SUS and presses the fixing roller 91 through the endless belt 92 to deform the elastic body of the fixing roller 91 so that the surface of the fixing roller 91 is on the recording material P. Is separated from The pressure applied to the separation roller 93 was 300 to 500 N, and the contact portion (separation nip portion) between the fixing roller 91 and the separation roller 93 at that time was about 4 mm.

  The pressure pad 94 is a pressure member made of silicone rubber having a rubber hardness of 20 ° (JIS-A 1 kg load), is fixed to a belt unit side plate (not shown), and is slidably pressed through the inner surface of the endless belt 92. . Therefore, in order to increase the slidability of the pressure pad 94 with the endless belt 92, it is common to apply a fluorine resin coat on the surface or press the endless belt via a low friction sheet, for example. In this embodiment, a low-friction sheet (not shown) made of a glass fiber sheet (manufactured by Chuko Kasei Co., Ltd .: FGF-40) is fixed to the pressure pad 94, and the inner surface of the endless belt 92 is attached via the low-friction sheet. A configuration for sliding pressurization was used. The pressure applied by the pressure pad was 400 to 600 N, and the contact portion (pressure nip portion) formed by the fixing roller 91 and the pressure pad 94 at that time was about 20 mm.

  As described above, when the nip is formed by the fixing roller 91, the endless belt 92, and the pressure pad 94, a wide nip can be formed so as to wrap around the outer periphery of the fixing roller 91, and high-speed fixing is possible. Further, by pressing the separation roller 93 so as to bite into the surface of the fixing roller 91, a good separation property is exhibited even during high-speed fixing.

  Also, in the case of a conventional fixing device using a roller pair, when the nip width is widened, the elastic layer has to be thick, which is disadvantageous for energy saving. In the fixing device, since it is possible to form a wide nip without increasing the thickness of the elastic layer of the fixing roller 91, it is possible to prevent heat transfer loss due to the elastic layer, which is effective for energy saving and downsizing of the device. It is.

  The main part of the lubricant application member 98 is composed of a holding member and an impregnation member formed of metal, synthetic resin, or the like. The impregnated member includes a non-volatile oil (Shin-Etsu Chemical Co., Ltd.) such as dimethyl silicone oil having a viscosity of 10 cs to 10,000 cs applied to the inner surface of the belt for the purpose of improving the sliding property between the endless belt 92 and the pressure pad. ): Made of felt (Nomex) roller impregnated with KF96), but not limited to this, such as heat-resistant flexible unemployed cloth Used. The lubricant retaining member will be described in more detail later with reference to the drawings.

  The steering roller 96 has a core shaft made of Fe, Al, and SUS coated with an elastic layer made of silicon rubber, for example, by about 0.5 to 2.0 mm. The steering roller 96 performs meandering control of the belt by a drive unit (not shown) based on an output of a belt position detection sensor (not shown).

  The suspension roller 97 is a roller that suspends the endless belt.

  The lubricant application member 98 is located upstream of the pressure applying member 91 in the belt rotation direction, and a cleaning member 99 is disposed at an opposite position across the belt. In the case of a mechanism in which the lubricant applying member 98 or the cleaning member 98 is independently pressurized, there are problems that the endless belt 92 is unilaterally tensioned and a mechanism for driving is required. However, since the cleaning member 99 and the lubricant applying member 98 pressurize each other at a position where the belt is sandwiched, it is possible to bring the cleaning member 99 and the lubricant application member 98 in accordance with the movement of the belt, and the mechanism for driving itself is unnecessary. Furthermore, this can reduce the number of members required for the lubricant application member 98 and the cleaning member 99, and can also save the installation space for the members.

  Next, the operation of this fixing device will be described.

  First, when the surface of the fixing roller 91 reaches a predetermined set temperature by the heating of the halogen lamp 95 and a start signal for an image forming operation (such as a copying operation or a printing operation) in the image forming apparatus is received, recording is performed in the image forming apparatus. A toner image is transferred and formed on the material P, and the recording material P is conveyed to the fixing device. In synchronism with the start of the image forming operation, the fixing roller 91 starts to rotate in the direction of the arrow in the drawing, and at the same time, the endless belt 92 is stretched over the three rollers 93, 96, and 97 to the fixing roller 91. It follows to start rotating in the direction of the arrow in the figure.

  Due to the rotation of the fixing roller 91, the endless belt 92 rotates in a state where a nip is formed between the endless belt 92 and the fixing roller 91 due to the support by the separation roller 93 and the pressing by the pressure applying member 94. Further, a lubricant is applied to the inner peripheral surface of the endless belt 92 by a lubricant application member 98 on the upstream side of the pressure applying member 94 in the belt rotation direction. Thereby, since the lubricant is supplied between the endless belt 92 and the pressure applying member 94, the frictional resistance between the belt 92 and the pressure applying member 94 is reduced, and the low friction layer of the pressure applying member 94 is reduced. Abrasion is prevented.

  In this fixing device, the lubricant application member 98 (impregnation member) is disposed so as to contact the inner peripheral surface portion of the endless belt 92 between the suspension roller 97 and the steering roller 96. Any part of the belt can be provided. Since the lubricant applying member 98 and the cleaning member 99 are pressurized from the inside and outside, they are not easily affected by belt position fluctuations, and the member and the belt surface are easily brought into uniform contact with each other. In addition, since the impregnating member 98 and the cleaning member 99 are flexible portions with low fiber density, even if there are some fluctuations in the belt, they come into contact with each other so as to reliably follow the belt fluctuations. As a result, the lubricant impregnated in the lubricant-impregnated member 98 is always supplied to the belt inner peripheral surface side by a certain amount. Since the fiber density at the center of the lubricant application member 98 is high, the lubricant is more concentrated than the end due to capillary action, so that the lubricant is more easily applied to the center of the endless belt 92. Yes. As long as the lubricant in the impregnating member 98 remains, smooth rotation of the end belt 92 can be ensured, and wear of the low friction layer of the pressure applying member 94 can be suppressed.

  In the case of this fixing device, the lubricant applying member 98 is provided on the upstream side of the pressure applying member 94 in the belt rotation direction, and therefore the lubricant applied from the applying member 98 to the inner peripheral surface of the endless belt 92. Is reliably supplied without loss between the pressure applying member 94 and the endless belt 92 (in the nip). The problem that the lubricant wraps around the outer surface of the endless belt 92 and adversely affects the recording material P can be solved because the cleaning member 99 exists on the outer surface of the endless belt 92. Further, because of the relationship between the application member and the cleaning member shown in FIG. 3, a lubricant intrusion prevention member composed of a rubber-like member is provided at the end of the cleaning member 99 rather than the portion through which the recording material P passes. The lubricant can be prevented from going to the cleaning area through which the recording material P passes.

  Even when the position of the endless belt 92 is changed by the steering roller 96, the end portion of the lubricant applying member has a flexible configuration and is pressed by the opposing member. It will come to rotate stably without fluctuating due to the pressing by. As a result, in addition to the endless belt 92 rotating stably, the endless belt 92 is reliably kept in close contact with the fixing roller 91 at the nip to the separation roller 93 by the pressure applying member 94. Since the recording material P passing through the nip always passes in a constant state, there is no possibility that the fixed image is disturbed.

  Further, the lubricant application member 98 is replaced in time for the time when the impregnated lubricant is reduced. Further, when the amount of the lubricant is reduced, the amount of lubricant applied to the inner peripheral surface of the endless belt 92 is reduced, and substantially coincides with the time when the low friction layer of the pressure applying member 94 starts to be worn. This also almost corresponds to the replacement time of the member 94. In the case of this fixing device, the lubricant application member 98 and the cleaning member 99 are structured so as to pressurize at the opposite positions. Therefore, by removing the lubricant application member 98, the cleaning member 99 is also simultaneously provided. Since it can be removed, it is possible to perform the removal work of both of them, the replacement work, and the mounting work at the same time, thereby ensuring efficient workability.

(Industrial applicability)
It can be developed not only for oil but also for the purpose of applying other lubricants, and a wide range of applications can be expected with a fixing device using a belt. The inner oil application roller is not necessarily a rotating body as long as the oil application is stable, and the outer cleaning member may not be a rotating body as long as the material does not damage the belt surface layer. In addition, the lubricant application member and the cleaning member are members that need to be replaced over time. However, when the replacement is necessary, they can be replaced at the same time, and work efficiency is increased.

1 is a cross-sectional view of an image forming apparatus according to the present invention. 1 is a cross-sectional view of a fixing device according to a first embodiment of the present invention. 1 is a diagram of a fixing device according to a first embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Fixing part 91 Fixing roller 92 Endless belt 93 Separation roller 94 Pressure pad 95 Fixing roller 96 Steering roller 97 Suspension roller 98 Lubricant holding member 99 Cleaning roller 9A Lubricant intrusion prevention member

Claims (6)

  A rotatable fixing member, a rotatable endless belt that contacts the fixing member, a fixed fixing pressure member that contacts the inner surface of the belt and presses the fixing member via the endless belt, and a lubricant that contacts the inner surface of the belt An electrophotographic belt fixing device comprising a fixing member having an application member, the belt having a cleaning member pressed against the lubricant application member via the endless belt.   2. The fixing device according to claim 1, wherein a lubricant intrusion preventing member is provided at an end of the cleaning member.   2. The fixing device according to claim 1, wherein the entire length of the lubricant application member is shorter than the width of the endless belt.   2. The fixing device according to claim 1, wherein the density of the fiber in the center portion of the lubricant application member is highest and the density decreases toward the end portion.   2. The fixing device according to claim 1, wherein the lubricant applying member is a rotary type and is driven to rotate with respect to the endless belt.   2. The fixing device according to claim 1, wherein the cleaning member is a rotary member and is driven to rotate with respect to the endless belt.

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