JP2010151914A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device having an oil filter unit which removes impurity from collected oil over a long term and can provide a high-quality image without deteriorating coating performance of oil even when it is used circularly, or without shortening lives of a fixing member and a coating member, and to provide an image forming apparatus using the fixing device. <P>SOLUTION: The oil filter unit 10 has: a box type filter case 11 which has an inclination for making the oil received from a collection path 42a flow from an upper part to a lower part; and a filter member 12 which is used both as a partition that partitions the inside of the filter case 11 so as to form a plurality of cells 13 in a direction where the oil flows and a filter that is provided in the cell 13. The collected oil received by the upper cell 13 of the filter case 11 from the collection path 42a gets over a protrusion of the filter member 12 and shifts to the adjacent lower cell 13 repeatedly, or filters through the filter member 12 in the cell 13, whereby the impurity in the oil is removed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention has a fixing device for fixing a toner image formed on an image carrier to a recording medium, and an electrophotographic device using the same, which has an oil applying means for applying to the fixing member while circulating oil for preventing offset The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.

  In a fixing device used in an electrophotographic copying machine or a laser printer, a recording medium on which a toner image is transferred is sandwiched between a fixing member and a pressure member, and the toner image transferred from the photosensitive drum to the recording medium is heated. The recording medium is fixed by applying pressure. In particular, in a fixing device of a high-speed color image forming apparatus, a release agent such as silicone oil is applied to the surface of the fixing member in order to prevent a so-called offset phenomenon in which a toner image to be fixed on a recording medium adheres to the fixing member. (Hereinafter referred to as oil) is often applied, and the amount used is also large.

  Therefore, a tank for holding oil is held in the apparatus, and after being sucked up by the supply tube from the supply tank, it is applied to the surface of the fixing member via an application body such as felt and an application roller. In addition, if the toner image is fixed in a state where the oil is excessively applied to the surface of the fixing member, the recording medium is soiled with the oil, so that it is necessary to regulate the amount of applied oil. For this reason, a blade that scrapes off excess oil is in contact with the surface of the fixing member or the surface of the coating roller, and the oil scraped off by the blade is collected in a tank through a collection tube and reused. There are many things.

  However, since foreign matters such as paper dust and toner adhere to the surface of the fixing member, these foreign matters are mixed in the oil collected from the surface of the fixing member, and the oil collected in the tank is left as it is. If supplied, there is a concern that the supply tube, the coating felt and the like are clogged with foreign substances, resulting in insufficient supply or inability to supply. In addition, problems such as a decrease in oil release capability, damage to the fixing member and application roller, and quick deterioration occur, resulting in a significant reduction in image quality (gloss).

  For this reason, in the conventional oil supply apparatus, a filter is provided on the supply side or the recovery side of the tank, and paper dust, toner, and the like in the oil are filtered by the filter. However, the filter becomes clogged over time, so it must be periodically replaced and cleaned.For example, when a filter is provided in the middle of the oil circulation path such as a supply tube or a collection tube. Since the area cannot be set large, there has been a problem that the filter replacement cycle is shortened, oil overflow or the like occurs, and maintenance of the fixing device takes time. In addition, since oil has a high viscosity, it takes a long time to recover, and in order to put it to practical use, there are many problems such as the need for a dedicated pump for suctioning the filter.

  Patent Document 1 proposes that an impurity removal cartridge including a stepped oil flow path forming member and a filter disposed in the oil flow path is provided in the oil tank. However, this technology can make maintenance easier and extend the service life to some extent compared to the conventional technology. However, since a filter is provided in a staircase shape, a large space is required to secure the filter area. In the case of providing in this apparatus, filtration was not sufficient due to space limitations.

JP 2001-175110 A

  The present invention has been made in view of the above-described problems in the prior art, without deteriorating the oil application performance, without disturbing the circulation of the oil, and moreover of the fixing member and the application member. An object of the present invention is to provide a fixing device having an oil filter unit and an image forming apparatus using the fixing device capable of improving the economy by extending the period until filter replacement without shortening the service life. And

The present invention provided to solve the above problems is as follows.
[1] A fixing member (fixing belt 38) for fixing unfixed toner transferred to the recording medium by pressurizing and heating the recording medium (recording medium P), and oil as a release agent on the fixing member. Application means (oil application roller 47) for application, recovery means (recovery oil pan 42, recovery path 42a) for recovering excess of the oil applied to the fixing member, and oil in the oil recovered by the recovery means An oil filter unit (oil filter unit 10) for removing impurities, an oil tank (oil tank 50) for holding oil from the oil / oil filter unit, and a supply means for supplying oil in the oil tank to the application means And the oil filter unit is a box-type filter case having an inclination for flowing the oil received from the collecting means downward from above ( A filter case 11), a partition (filter member 12) that partitions the filter case so as to form a plurality of compartments (compartments 13) in the direction in which oil flows, and a filter (filter member 12) provided in the compartments The oil received in the upper compartment of the filter case from the collecting means repeatedly passes over the partition and moves to the adjacent lower compartment, or passes through the filter in the compartment. Thus, the fixing device (fixing device 100, FIG. 2) from which impurities in the oil are removed.
[2] The fixing device according to [1], wherein the filter case has holes (holes 11b and 11b ′) through which oil that has passed through the filter in the compartment is released (FIGS. 5, 7, 8, and 10). .
[3] The fixing device according to [1] or [2], wherein the partition is made of a filter material.
[4] The above-mentioned [1] to [3], wherein a member obtained by bending a sheet-like filter material so that the upper side is convex is used as a partition (filter member 12) in the filter case. The fixing device according to claim 1 (FIG. 5).
[5] The oil filter unit includes a box-shaped case member (sheet 16) having a sheet-like filter (filter 16) that receives the oil from which impurities are removed by the filter case and further removes impurities. The fixing device according to any one of [1] to [4], comprising a case member 15) (FIG. 4).
[6] The fixing device according to [5], wherein a space is provided between the filter case and the sheet-like filter and / or between the sheet-like filter and the case member (FIG. 8).
[7] The fixing device according to [5] or [6], wherein the porosity of the filter material used in the case member is smaller than that of the filter material used in the filter case.
[8] The fixing device according to any one of [5] to [7], wherein the case member has a flow path (flow path portion 15d) for flowing oil overflowing from the filter case to the oil tank (FIG. 8). ).
[9] The fixing device according to any one of [1] to [8], wherein the oil filter unit or the filter case has a cartridge structure that is detachable from the fixing device.
[10] An image forming apparatus comprising the fixing device according to any one of [1] to [9] (image forming apparatus 200, FIG. 1).

  According to the fixing device of the present invention, in the oil filter unit, by removing impurities in the oil by precipitation action by repeatedly moving over the partition and moving to the adjacent lower compartment, and by passing through the filter in the compartment. By combining the removal of impurities by filtration, it is possible to extend the life of the oil filter and increase the efficiency of recovery of oil from which impurities have been removed.

The configurations of the fixing device and the image forming apparatus according to the present invention will be described below with reference to the drawings.
First, an image forming apparatus according to the present invention will be described.
FIG. 1 shows a configuration of a tandem type color copying machine which is an image forming apparatus according to the present invention.
The color copying machine 200 includes an image forming unit 200A positioned at the center of the apparatus main body, a paper feeding unit 200B positioned below the image forming unit 200A, and an image reading unit (not shown) positioned above the image forming unit 200A. The fixing device 100 is incorporated in the image forming unit 200A.

  The image forming unit 200A is provided with a transfer belt 210 having a transfer surface extending in the horizontal direction, and a configuration for forming an image of a color complementary to the color separation color on the upper surface of the transfer belt 210. Is provided. That is, photoconductors 205Y, 205M, 205C, and 205K as image carriers that can carry images of toners of complementary colors (yellow, magenta, cyan, and black) are juxtaposed along the transfer surface of the transfer belt 210. ing.

  Each of the photoconductors 205Y, 205M, 205C, and 205K is configured by a drum that can rotate in the same direction (counterclockwise direction), and around the optical writing device 201 that performs image forming processing in the rotation process, Charging devices 202Y, 202M, 202C, 202K, developing devices 203Y, 203M, 203C, 203K, primary transfer devices 204Y, 204M, 204C, 204K and a cleaning device are arranged. Each developing device 203Y, 203M, 203C, 203K contains a respective color toner.

  The transfer belt 210 is configured to be able to move in the same direction at a position facing the photoconductors 205Y, 205M, 205C, and 205K by being wound around a driving roller and a driven roller. Further, a transfer roller 212 is provided at a position facing a roller 211 that is one of the driven rollers. Further, the conveyance path of the recording medium (also referred to as a sheet) P from the transfer roller 212 to the fixing device 100 is a horizontal path.

  The sheet feeding unit 200B separates the sheet P in the sheet feeding tray 220 one by one from the top in order from the top to the position of the transfer roller 212. It has a transport mechanism for transporting.

  In image formation in the image forming apparatus 200 of the present invention, the surface of the photoreceptor 205Y is uniformly charged by the charging device 202Y, and an electrostatic latent image is formed on the photoreceptor 205Y based on image information from the image reading unit. Is done. The electrostatic latent image is visualized as a toner image by a developing device 203Y containing yellow toner, and the toner image is primarily transferred onto the transfer belt 210 by a primary transfer device 204Y to which a predetermined bias is applied. Is done. The other photoconductors 205M, 205C, and 205K also form similar images only with different toner colors, and the toner images of the respective colors are sequentially transferred onto the transfer belt 210 by the electrostatic force and superimposed.

  Next, the toner image T primarily transferred from the photoconductors 205Y, 205M, 205C, and 205K onto the transfer belt 210 is transferred to the sheet P conveyed by the rollers 211 and 212. The sheet P on which the toner image T is transferred is further conveyed to the fixing device 100.

  The fixing device 100 includes a fixing nip portion that fixes a toner image T onto a sheet P that passes through heat and pressure by bringing a fixing member and a pressure member into contact with each other. In FIG. 1, a fixing member (fixing belt) spanned between a fixing roller and a heating roller with a constant tension, and a pressure member (pressure roller) can rotate freely below the fixing member (fixing belt). The structure in which the fixing nip is formed by pressing is shown. Here, the sheet P is fixed by passing through a fixing nip portion between the fixing belt and the pressure roller.

An appropriate amount of oil is applied to the fixing belt (and also to the pressure roller as required) by an oil application device, and a separation claw disposed on the exit side of the fixing nip functions as necessary. Then, the sheet P is discharged to the exit side of the fixing nip portion without being wound around the fixing belt and the pressure roller.
Next, the sheet P discharged from the fixing nip portion is sent out to the stacker 215 along the discharge path.

  As described above, the image forming apparatus 200 of the present invention can provide a more advanced fixing separation function, and can be applied to various types of paper (from thin paper to thick paper) and images (the image leading edge margin can be reduced). Correspondence becomes possible.

  In the image forming apparatus 200, the oil tank 50 is attached to the fixing device 100 to collect oil for improving the releasability of the sheet P used in the fixing device 100, and the oil in the oil tank 50 is fixed again. An oil circulation mechanism such as an oil pump 51 that supplies the apparatus 100 is provided. Details will be described below.

FIG. 2 is a schematic diagram showing a schematic configuration including an oil circulation mechanism in the fixing device according to the present invention.
In FIG. 2, reference numeral 36 denotes an entrance guide, and the recording medium P carrying a toner image enters the fixing device 100 through the entrance guide 36. The recording medium P is sandwiched between a fixing belt 38 heated by a heating roller 35 including a heater 44, a fixing roller 34, and a pressure roller 37 so that the toner image is fixed on the recording medium P. 40 is discharged to the outside along with the rotation of the discharge roller 41.

  At this time, toner or the like adheres to the surface of the fixing belt 38, but this dirt is cleaned by the cleaning roller 39. The cleaning roller 39 is cleaned by a web 45 which is fed little by little by a motor and always makes a clean surface contact. Further, the pressure roller 37 is cleaned by a cleaning member such as felt (not shown), applies oil in the recovered oil pan 42, and the amount of oil is regulated by the blade 43 and uniformly applied to the surface.

  On the surface of the fixing belt 38 cleaned by the web 45, oil as a release agent is uniformly applied by an oil application roller 47. In supplying oil to the oil application roller 47, first, oil dropped from the supply sub oil pan 33 is accumulated in the supply oil pan 32. One end of the application felt 46 is immersed in the oil in the supply oil pan 32. Accordingly, the coating felt 46 sucks up oil by capillary action and always maintains the state of containing oil. Oil is supplied from the impregnated application felt 46 to the oil supply roller 48, and the amount of oil on the oil supply roller 48 is uniformly regulated by the application blade 49 in contact with the oil supply roller 48. By supplying oil uniformly regulated on the oil supply roller 48 to the oil application roller 47, the oil can be uniformly applied from the oil application roller 47 to the fixing belt 38. Further, excess oil during application of the fixing belt is recovered to the recovery oil pan 42 through a path (not shown).

  This oil prevents the fixing roller 38 from being contaminated with impurities such as toner and the recording medium P from being wound around the fixing belt 38. As for the material of the oil, silicone oil is generally used at present. Among them, dimethyl type is particularly used, for example, KF-96 manufactured by Shin-Etsu Chemical Co., Ltd. Etc. are well known. The viscosity can be used from tens of thousands of cs or less, but is preferably several thousand cs or less. Those of several tens cs or less have high volatility, easily pollute the inside of the machine, have a low flash point, and have safety problems.

  Below the fixing device 100, an oil tank 50 that is an oil holding unit and an oil pump (not shown) that is a supply unit that supplies oil from the oil tank 50 to the supply sub oil pan 33 are provided. The oil pump may be provided with a backflow prevention valve. The oil tank 50 is provided with an oil end sensor (not shown), detects the amount in the oil tank 50, and notifies the oil replenishment timing. The detection method may be a method using a floater (floating) or a method of optically detecting by light refraction. Further, the oil recovered by the recovery oil pan 42 is purified by removing impurities by the oil filter unit 10 and then returned to the oil tank 50 for circulation.

  Here, in the oil circulation mechanism, solid impurities such as dust and calcium carbonate derived from the sheet P and toner are inevitably mixed in the oil. If oil is circulated with such solid impurities mixed in, the impurities adhere to other functional parts in the oil circulation path, resulting in malfunctions and image defects. For example, the oil application roller 47 and the fixing belt 38 are damaged, and as a result, the oil application unevenness is generated on the fixing belt 38, and a defect appears in the image as gloss unevenness. Therefore, even in the conventional oil circulation mechanism, such an impurity is provided in the oil supply path by providing an oil filter unit in the recovery path and filtering the recovered oil in the fixing device through the oil filter unit to remove solid impurities. Was not mixed.

However, if the oil circulation is continued, the conventional oil filter is clogged due to adhesion of solid impurities, the amount of oil circulation is reduced, and the oil circulation is disturbed in a relatively short time. There was a problem of image quality degradation due to insufficient oil supply. Therefore, it is necessary to periodically replace and clean the oil filter. For example, when a filter is provided in the middle of the circulation path of the release agent such as a supply tube or a collection tube, the area can be set large. As a result, the replacement life of the oil filter was short.
The inventors have intensively studied to improve that the oil filter in the oil filter unit is likely to be clogged while studying this problem, and have achieved the present invention. Hereinafter, an oil filter unit which is a fundamental part of the present invention will be described.

FIG. 3 is a perspective view showing a configuration example of an oil filter unit used in the present invention.
The oil filter unit 10 according to the present invention includes a box-shaped filter case 11 having an inclination for flowing oil received from the collecting means (the collecting path 42a of the collecting oil pan 42) downward from above, and the inside of the filter case 11 is oiled. A partition (filter member 12) for partitioning so as to form a plurality of compartments 13 in the direction in which the gas flows, and a filter (filter member 12) provided in the compartments 13, from the recovery means to the filter case 11 The oil received in the upper compartment 13 is moved over the partition and moved to the adjacent lower compartment 13 to remove impurities in the oil, and separately, the filter in the compartment 13 is filtered. By the permeation, impurities in the oil are removed.

FIG. 4 shows an exploded view of the oil filter unit 10.
The oil filter unit 10 includes a box-shaped case member 15 having a sheet-like filter 16 that receives the oil from which impurities are removed by the filter case 11 and further removes impurities.

  At this time, the filter case 11 is stored in a state of being supported by the protruding portion in the case of the case member 15, but the filter case 11 has a certain amount of space between the bottom surface of the filter case 11 and the filter 16. Should be supported. If the bottom surface of the filter case 11 and the filter 16 are in close contact with each other, the flow of oil that has come out of the filter case 11 is obstructed, and it takes time for oil filtration, leading to overflow from the oil filter unit 10. Therefore, by providing a space between them, the flow of oil from which impurities returning to the oil tank 50 are removed is improved, the filtration performance is improved, the filtration time is shortened, and the filtration efficiency is increased.

Next, the detailed structure of the filter case 11 is shown in FIG.
The filter case 11 is a box-shaped case having an open upper portion having a certain width in a direction orthogonal to the direction in which the oil flows. For example, the filter case 11 is an injection molded product of a resin material that does not react with oil. Further, positioning members 11a slightly projecting on both side walls and the bottom of the case in the direction orthogonal to the oil flowing direction are arranged at regular intervals in the oil flowing direction. In FIG. 5, twelve positioning members 11a are arranged. Is provided. In addition, a plurality of holes 11b penetrating to the bottom are provided in a direction perpendicular to the oil flow direction at the bottom of the case between the adjacent positioning members 11a. In FIG. 5, eight rows of φ4 mm holes 11b arranged in a direction orthogonal to the oil flowing direction are provided in 12 rows in the oil flowing direction. Furthermore, the rectangular opening part 11c is provided also in the side wall of the downward side of the direction through which oil flows.

  In such a filter case 11, a filter material in the form of a strip sheet having a certain thickness (for example, a thickness of about 2 mm) having the same length as the inner dimension width of the filter case 11 is bent and the folding line extends in the length direction. In this state, a member (filter member 12) bent so that the upper side is convex (mountain-folded) is fitted between the positioning members 11a, and the plurality of filter members 12 are spread in the oil flowing direction. It becomes the structure arranged. At this time, the hole 11b exists under the convex part of the filter member 12. The number (the number of stages) in which the plurality of fill members 12 are arranged is effective when it is 2 or more, but is preferably 6 or more. For example, in FIG. 5, the number of stages of filter members 12 to be spread is 12, and each filter member 12 has the same height. Alternatively, the height of the filter member 12 may be gradually lowered in the oil flowing direction. The filter member 12 may be fixed to the filter case 11 with an adhesive or the like.

  Further, the material of the filter member 12 is a compressed sheet made of a fiber (for example, meta-aramid fiber, etc.) that is heat resistant and does not react with oil. Oil is permeated while capturing inside.

  In addition, the inclination of the bottom surface of the filter case 11 is an inclination with respect to the horizontal reference of the fixing device 100 and thus the image forming apparatus 200 main body, and the inclination angle is an angle at which oil flows through the filter case 11, that is, several degrees. About 5 degrees.

FIG. 6 is a cross-sectional view showing the configuration of the case member 15.
The case member 15 is a box-shaped case that is opened at the top for housing and supporting the filter case 11, and is, for example, an injection-molded product of the same resin material as the filter case 11. Further, the bottom of the case member 15 has a discharge hole 15 a for discharging oil to the oil tank 50.

  It is desirable to provide a space between the filter 16 and the case member 15. When the filter 16 and the case member 15 are in close contact with each other, the flow of oil is hindered, and it takes time for oil filtration, leading to an oil overflow from the oil filter unit 10. For example, in FIG. 6, a rib 15b having a height of 2 mm is erected on the bottom surface of the case member 15 along the oil flowing direction. As a result, the sheet-like filter 16 is supported in a state of floating to some extent from the bottom of the case member 15, and a space is secured between the filter 16 and the bottom surface of the case member 15. It is possible to flow through the space on the bottom surface of the case member 15 and allow the case member 15 to be discharged from the discharge hole 15a without being retained.

  Furthermore, the case member 15 has a handle portion 15c extending further downward from the storage area of the filter case 11 in the direction in which the oil flows so that the user can handle the oil filter unit 10 by hand. Yes. In addition, a flow path portion 15 d that guides the overflowed oil directly to the oil tank 50 when the oil overflows from the filter case 11 is provided above the storage area of the filter case 11.

By the way, when the filter member 12 is arranged as shown in FIG. 5, the filter case 11 serves as both “partition” and “filter”. FIG. 7 shows the principle diagram.
First, the “partition” in the present invention plays a role of forming the compartment 13 in the filter case 11. In other words, the oil recovered from the recovery path 42 a is supplied and the oil is stored in the first compartment 13, and impurities in the oil are precipitated at the bottom of the compartment 13. Since the oil supply is continued, the first compartment 13 is filled with oil, and the oil overflows. At this time, since the filter case 11 is inclined, the oil in the supernatant that has been cleaned to some extent above the first compartment 13 passes over the convex portion of the filter member 12 and flows into the adjacent compartment 13. Become. Thus, the oil recovered by repeating the removal of impurities in the oil by the precipitation action (the action and effect of (1) in FIG. 7) by the number of compartments 13 (the number of stages of the filter member 12 −1). Can be cleaned. In addition, since the partition is the filter member 12 made of the filter material, when the oil gets over the filter member 12, impurities in the oil are trapped on the surface layer of the filter member 12, and the cleaning of the oil is further promoted. Yes.

  Further, the “filter” in the present invention plays a role of removing impurities in the recovered oil. That is, when the recovered oil enters the compartment 13, a part of the oil passes through the filter member 12. At this time, the filter member 12 removes impurities in the oil by the filtering action. The recovered oil is cleaned (the effect of (2) in FIG. 7). In addition, since the hole 11b is provided in the position corresponding to the convex part of the filter member 12 in the bottom part of the filter case 11, the clean oil filtered with the filter member 12 passes the hole 11b to the case member 15 side. Will be discharged.

FIG. 8 is a cross-sectional view showing the principle of oil cleaning in the oil filter unit 10. Here, the flow of oil is indicated by arrows.
In FIG. 8, the oil recovered by the recovery oil pan 42 is first supplied from the recovery path 42 a to the first compartment 13 on the uppermost side of the inclination of the filter case 11.
Oil is accumulated in the first compartment 13 and impurities in the oil settle on the bottom of the compartment 13. Then, since the oil supply is continued, the first compartment 13 is filled with oil, the oil overflows, and the superficial oil at the top of the first compartment 13 is cleaned to some extent. It flows over the convex part and flows into the adjacent compartment 13 ((a) in the figure). Also in this adjacent compartment 13, oil is similarly stored, and the oil supply is continued while the impurities in the oil are precipitated at the bottom of the compartment 13, so that the oil is full and the supernatant oil is filtered out. 12 gets over the upper part and flows into the adjacent compartment 13 further. The process of removing impurities by the precipitation action is sequentially performed in each compartment 13, and oil overflows from the last compartment 13 (the 11th compartment 13 in FIG. 8) over the upper part of the filter member 12 (in the drawing). (B)) is discharged to the case member 15 side through the opening 11c of the filter case 11 ((c) in the figure).

  In the filter case 11, the impurity removal by the filtering action by the filter member 12 is performed in parallel with the impurity removal by the precipitation action or in part after the impurity removal by the precipitation action. That is, when the recovered oil is supplied to the first compartment 13 from the recovery path 42a, a part of the oil passes through the filter member 12 and is filtered to remove impurities in the oil ( (D) in the figure). Filtration by the filter member 12 is performed in each compartment 13, and the filtered oil is discharged to the case member 15 side through the holes 11 b provided in the bottom of the filter case 11.

In the case member 15, both the oil that has entered through the opening 11 c of the filter case 11 and the oil that has entered through the hole 11 b are received by the sheet-like filter 16, and the oil is further filtered by the filter 16. Thus, impurities (such as fine paper dust and small particle size toner) that could not be removed by the filter case 11 are removed. Thereby, the recovered oil becomes a reusable oil from which impurities are sufficiently removed.
The oil finally filtered by the filter 16 is discharged to the oil tank 50 from the discharge hole 15a.

  As a means for increasing the filter filtration efficiency, it is preferable to make the filter porosity of the filter 16 smaller than the filter porosity of the filter member 12. Thereby, relatively large particles are removed by the upper filter member 12, and small particles are taken by the lower filter 16, so that the filtration time can be shortened and impurities can be efficiently removed.

  Further, when the amount of oil applied in the fixing device 100 increases for some reason and a large amount of recovered oil flows into the oil filter unit 10 and exceeds the oil holding capacity, or the filter member 12 is contaminated with impurities and the efficiency of filtering the oil In the case where the oil filter unit 10 is lowered, the oil may overflow from the oil filter unit 10 and may contaminate the fixing device 100 or the image forming apparatus 200 main body. Therefore, in the case member 15, a notch is provided at the upper edge of the case where the upper end of the filter case 11 in the direction in which the oil flows flows, and an overflow channel portion 15 d is provided in the notch. As a result, even when the oil overflows from the first compartment 13 of the filter case 11, the overflowed oil preferentially flows from the notch portion of the case member 15 into the flow path portion 15d. (An arrow indicated by a dotted line in FIG. 8), oil leakage to the fixing device 100 and the image forming apparatus 200 main body can be prevented.

  Thus, in the filter case 11, it is possible to set a large filter area as a whole by arranging a plurality of convex filter members 12, and the ability to remove impurities from the oil is increased accordingly. Replacement and cleaning cycles (filter life) can be extended. Oil takes a long time to recover due to its high viscosity, but it removes impurities by flowing oil through multiple routes by removing impurities by precipitation and removing impurities by filtration. Impurities can be efficiently removed only by the method of flowing oil using gravity (natural filtration) without using a dedicated pump. That is, since the filtration time can be shortened by increasing the number of flow paths for returning the oil to the oil tank 50, it is possible to prevent the oil from overflowing from the oil filter unit 10. In addition, by opening the hole 11b in the bottom of the filter case 11, the time required for removing the impurities of the recovered oil and returning it to the oil tank 50 is reduced by about 1 / 1.5 as compared with the case where the hole 11b is not provided. It was confirmed by experiments that

  The configuration of the filter case 11 in the present invention is not limited to that shown in FIG. 7, and a partition that partitions the inside of the filter case 11 so as to form a plurality of compartments 13 in the direction in which the oil flows. And a filter provided in the chamber 13, and any configuration that realizes the above-described removal of impurities in oil by the precipitation action and removal of impurities in oil by the filtration action. Also good.

  For example, the cross-sectional shape of the filter member 12 when the strip-like filter material is bent is not limited to the dogleg shape (triangular wave shape), and the dome shape as shown in FIG. A similar impurity removal effect can be obtained. Alternatively, instead of preparing each filter member 12 one by one, a configuration in which a plurality of filter members 12 are integrated by bending a sheet-like filter material into an accordion shape (accordion shape) may be used.

FIG. 10 shows another configuration example of the filter case 11.
FIG. 10A is formed integrally with the filter case 11, and a plurality of partitions 11 d are formed by partitioning the filter case 11 in the direction in which oil flows to form a plurality of compartments 13. This can be said that the positioning member 11a in FIG. 5 is a partition 11d. In addition, a strip-like filter member 12a is spread on the bottom of each compartment 13 as it is. Also by this structure, the sedimentation action (1) by the partition 11d is obtained, and the filtration action (2) by the filter member 12a is obtained.

  FIG. 10B shows a configuration in which the same partition 11 d as that in FIG. 10A is provided for the “partition”, and a sheet-like filter member 12 b is attached to the outside of the bottom surface of the filter case 11. Also by this structure, the sedimentation action (1) by the partition 11d is obtained, and the filtration action (2) by the filter member 12b is obtained.

  In FIG. 10C, the “partition” is provided with the same partition 11d as in FIG. 10A, and the strip-like filter member 12c is fixed in a state of being lifted to some extent from the bottom surface of each compartment 13. In this configuration, a certain amount of space is provided on the bottom side of the compartment 13. Also by this structure, the sedimentation action (1) by the partition 11d is obtained, and the filtration action (2) by the filter member 12c is obtained. Further, since there is a space on the bottom side of the compartment 13 as compared with the case of FIG. 10A, the oil that has entered the compartment 13 can easily pass through the filter member 12c, and the filtration efficiency is improved.

  FIG. 10D shows a “partition” in which a partition 11d having the same pattern as that in FIG. 10A is provided, and the strip-like filter member 12d is fixed in a state of being lifted to some extent from the bottom surface of each compartment 13. The bottom of the filter member 12d and the bottom surface of the filter case 11 form a flow path 11e that collects oil that has passed through the filter member 12d and flows downward, and further collects the oil below the flow path 11e. In this configuration, a hole 11b ′ for discharging is provided. Also with this configuration, the sedimentation action (1) by the partition 11d is obtained, and the filtration action (2) by the filter member 12d is obtained.

  FIG. 10E shows a configuration in which one strip sheet filter material is bent into an L shape and the filter member 12e is used as the partition 11d and the filter member 12a in FIG. 10A. Also with this configuration, a sedimentation action (1) is obtained by the standing part of the filter member 12e, and a filtration action (2) is obtained by the bottom part of the filter member 12e.

The oil filter unit 10 preferably has a cartridge structure that can be attached to and detached from the fixing device 100. FIG. 11 shows a configuration of the oil filter unit 10 having a cartridge structure.
As shown in FIG. 11, the oil filter unit 10 disposed at the upper part of the oil tank 50 is pulled out or pushed in the direction of the arrow with the handle portion 15c of the case member 15 from the apparatus main body (fixing apparatus 100). It can be easily detached from the front. Also, the filter case 11 alone can be easily attached and detached from the front, and only the filter case 11 can be replaced. In this way, the oil filter unit 10 as a whole or individual parts can be replaced, so that maintenance work such as filter replacement work can be reduced, and the maintenance for the user or operator is simplified.

Examples of the present invention will be described below.
Example 1
In the image forming apparatus 200 incorporating the oil filter unit 10 shown in FIGS. 3 to 5, image formation was performed, and the degree of impurity removal of oil returned to the oil tank 50 was investigated.
Note that a filter material having a thickness of 2 mm is used for the filter member 12, the filter member 12 is arranged in 12 stages in the filter case 11, and a filter material having a smaller porosity than the filter member 12 is used for the sheet-like filter 16. Using.

  In order to investigate the degree of impurity removal in the recovered oil, the change in oil turbidity for each number of plain paper passed was examined by haze. The haze degree was determined from the ratio of the scattered light intensity and the transmitted light intensity due to the particles in the oil using an integrating sphere photoelectric photometer. That is, the impurities in the oil scatter light, and the higher the scattered light ratio (the higher the haze degree), the more dirty the oil is. As measurement conditions, each oil sample was put in a glass cell (optical path length: 1 mm), and the haze degree was measured with an integrating sphere photoelectric photometer.

  FIG. 12 shows the survey results. As is apparent from FIG. 12, the oil filter unit 10 of the present invention (with the oil filter of FIG. 12) has a haze of less than 5% even when the number of sheets passed is 200000, and the recovered oil is an impurity. Was removed and purified as if it were new. In addition, there was no coating unevenness (gloss unevenness) caused by oil stains on the formed image. On the other hand, when image formation is performed without using the oil filter unit 10 (in the case of no oil filter in FIG. 12), the haze degree increases in proportion to the number of sheets to be passed. The haze degree was 15% or more, which is a standard for generating unevenness.

The relationship between the haze degree and impurities in the oil was confirmed as follows. That is, since the main additive in the plain paper used as the recording medium P is calcium carbonate, the calcium contained in the oil was quantitatively analyzed by inductively coupled plasma emission spectrometry using the following apparatus. As a result, the result of quantifying calcium carbonate in oil using plain paper showed a high correlation with the haze degree.
-Equipment used: Inductively coupled plasma emission spectrometer (SII Nano Technology, SPS-1700HVR type), sulfur analyzer (Horiba, EMIA-520SP type)

In addition, since coated paper may be used as the recording medium P, the relationship between the degree of haze and the impurities in the oil was also investigated. Here, since the surface of the coated paper contains a wax component, the mixture of the wax component into the oil was analyzed by Fourier transform infrared spectroscopy (FT-IR) analysis using the following apparatus. As a result, the qualitative analysis showed a high correlation between the amount of test paper passing through the coated paper and the degree of haze. Also in this case, it was confirmed that when the oil filter unit 10 was used, an increase in the haze degree was suppressed.
-Equipment: Fourier transform infrared spectroscopy (FT-IR) analyzer (Varian, FTS7000e / FastImageIR)

  As described above, in the fixing device 100 of the present invention, the oil filter unit 10 removes impurities (paper dust, toner, etc.) from the recovered oil over a long period of time. In addition, a high-quality image can be provided without shortening the life of the fixing member and the coating member.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited. For example, in the oil filter unit 10 of FIG. 3, the structure is such that a plurality of filter cases 11 are stacked in the height direction so that the oil descends from the upper filter case 11 to the lower filter case 11 in order while removing impurities. Then, it may be finally filtered by the filter 16 of the case member 15 and discharged to the oil tank 50.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. FIG. 2 is a cross-sectional view illustrating a configuration of a fixing device according to the present invention. It is a perspective view which shows the structural example of the oil filter unit used by this invention. It is an exploded view of the oil filter unit of FIG. It is a perspective view which shows the structural example of a filter case. It is sectional drawing which shows the structural example of a case member. It is a figure (1) explaining the principle of the impurity removal in oil in a filter case. It is a figure (2) explaining the principle of the impurity removal in oil in a filter case. It is sectional drawing which shows the structural example (1) of a filter case. It is sectional drawing which shows the structural example (2) of a filter case. It is a perspective view which shows the structure of the oil filter unit made into the cartridge structure. It is a figure which shows the relationship between the number of paper passing of Example 1, and the haze degree of oil.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Oil filter unit 11 Filter case 11a Positioning member 11b, 11b 'Hole 11c Opening part 11d Partition 11e Flow path 12, 12a, 12b, 12c, 12d, 12e Filter member 13 Compartment 15 Case member 15a Exhaust hole 15b Rib 15c Handle part 15d Channel portion 16 Filter 32 Supply oil pan 33 Supply sub oil pan 34 Fixing roller 35 Heating roller 36 Inlet guide 37 Pressure roller 38 Fixing belt 39 Cleaning roller 40 Guide 41 Paper discharge roller 42 Recovery oil pan 42a Recovery path 43 Blade 44 Heater 45 Web 46 Application felt 47 Oil application roller 48 Oil supply roller 49 Application blade 50 Oil tank 51 Oil pump 100 Fixing device 200 Image forming device 200A Forming unit 200B Paper feeding unit 201 Optical writing device 202Y, 202C, 202M, 202K Charging device 203Y, 203M, 203C, 203K Developing device 204Y, 204M, 204C, 204K Primary transfer device 205Y, 205C, 205M, 205K Photoconductor 210 Transfer Belt 211 driven roller (roller)
212 Transfer roller 215 Stacker 220 Paper feed tray O Oil P Recording medium (sheet)

Claims (10)

A fixing member for fixing the unfixed toner transferred to the recording medium by pressurizing and heating the recording medium, an application means for applying oil as a release agent to the fixing member, and an oil applied to the fixing member A recovery means for recovering excess, an oil filter unit for removing impurities in the oil recovered by the recovery means, an oil tank for holding oil from the oil oil filter unit, and an oil tank in the oil tank Supply means for supplying oil to the application means,
The oil filter unit includes a box-shaped filter case having an inclination for flowing the oil received from the collecting means from above to below, and a partition that forms a plurality of compartments in the direction in which the oil flows in the filter case. And a filter provided in the compartment,
The oil received in the upper compartment of the filter case from the recovery means repeatedly passes over the partition and moves to the adjacent lower compartment, or passes through the filter in the compartment, so that impurities in the oil are removed. Fixing device to be removed.   The fixing device according to claim 1, wherein the filter case has a hole through which oil that has passed through the filter in the compartment is released.   The fixing device according to claim 1, wherein the partition is made of a filter material.   The fixing device according to any one of claims 1 to 3, wherein a member obtained by bending a sheet-like filter material so as to project upward is used as a partition and a filter in the filter case.   5. The oil filter unit includes a box-shaped case member having a sheet-like filter that receives the oil from which impurities are removed by the filter case and further removes impurities. The fixing device according to any one of the above.   The fixing device according to claim 5, wherein a space is provided between the filter case and the sheet-like filter and / or between the sheet-like filter and the case member.   The fixing device according to claim 5, wherein a porosity of the filter material used in the case member is smaller than that of the filter material used in the filter case.   The fixing device according to claim 5, wherein the case member has a flow path for flowing oil overflowing from the filter case to an oil tank.   The fixing device according to claim 1, wherein the oil filter unit or the filter case has a cartridge structure that is detachable from the fixing device. An image forming apparatus comprising the fixing device according to claim 1.