Patent Application
20090238615
This application is based on Japanese Patent Application No. 2004-366252 filed on Dec. 17, 2004, the contents of which are incorporated herein by reference.
The present invention relates to a separating plate used to separate a transfer paper from a fixing member in an electro-photographic type-image forming apparatus such as copying machines, printers, facsimiles or the like, a fixing device having the separating plate, a method for producing the separating plate and an image forming apparatus including the separating plate or the fixing device.
An apparatus using an electro-photographic type, for example, a laser printer has a rotatable photoconductive drum and forms an electrostatic latent image by exposing a photoconductive layer on the photoconductive drum by a laser beam from a laser scanning unit after the photoconductive layer on the photoconductive drum is charged uniformly.
In addition, the laser printer is configured to form a toner image by developing the electrostatic latent image by a toner, transfer the toner image on a transfer paper, and then fix the toner image thermally by passing the transfer paper through a thermal fixing device.
Such a conventional thermal fixing device uses a fixing roller including an anti-sticky layer such as fluorine resin to prevent an adhesive of a toner on an outer peripheral surface of a cored bar of a hollow cylinder made of, for example, aluminum, or the like.
The fixing roller is configured to dispose a heater such as a halogen lamp in the hollow cored bar along a rotational central axis of the roller and heat the fixing roller from an inside thereof by radiant heat of the heater.
Furthermore, by providing a fixing roller and a pressure roller contacting with the fixing roller and passing a transfer paper between the fixing and pressure rollers, while melting a toner adhered on the transfer paper by heat of the fixing roller, the toner is transferred on the transfer paper by pressuring. At this time, because the transfer paper is ejected in such a manner that the toner melts and fits closely to the fixing roller, a separating pawl made of a heat-resistant resin such as polyimide, polyamide-imide, PPS (polyphenylene sulfide), or the like is provided to abut with the fixing roller in order to separate the transfer paper from the fixing roller or fixing belt.
In recent, with colorization of images, as a method of fixing a transfer paper in which several colored toners are laminated, a fixing belt including a belt made of a metal or polyimide, an elastic layer of silicon rubber formed on the belt, and an adhesion-preventing layer of a fluorine resin formed on the elastic layer to prevent the adhesion of the toner has been used.
In a fixing belt or fixing roller using a color toner, when the separating pawl is abutted with the elastic layer, the separating pawl bites in the elastic layer there is a problem that the elastic layer, separating pawl or the like is damaged. Therefore, a peeling sheet pr separating plate which does not contact with the elastic layer has bee used.
Conventionally known are various technologies for separating a transfer paper from a fixing member such as a fixing roller or fixing belt.
Japanese Patent Laid-Open No. 2001-83832 discloses a peeling sheet for peeling a recording paper ejected from a nipping part between a fixing roller and a pressure roller from the fixing roller. The peeling sheet is formed from a thin metallic plate and includes an edge having a continuous curvature, and the edge is covered with a coating layer of a fluorine resin having mold-releasing property.
Japanese Patent Laid-Open No. 2002-91222 discloses a peeling member including a supporting member, a peeling sheet connected with the supporting member by a sheet laser spot welding, and a fluorine resin sheet attached to a portion of the peeling sheet close to the fixing roller.
Japanese Patent Laid-Open No. 2004-109636 discloses a separating pawl configured to abut with a fixing roller for contacting with a pressure roller. The separating pawl is disposed so that an angle at which a line connecting centers of the fixing and pressure rollers and a line connecting the center of the fixing roller and a contacting point of the separating pawl with the fixing roller are disposed is set at 40° or less.
In addition, Japanese Patent Laid-Open No. 2003-122175 discloses that when a leading end of a transfer paper passes a separating member contacting with a fixing member, the separating member is moved.
However, in the peeling sheet disclosed in Japanese Patent Laid-Open No. 2001-83832, because the thin metallic plate is bent in a predetermined shape, thereafter the fluorine resin is coated on the bent plate, there is a problem that deformation, bow, damage at a bent portion or the like occurs in the bent plate due to a relatively high baking temperature for the fluorine resin, and therefore a stable gap between the peeling sheet and the fixing roller is not obtained.
Also, in Japanese Patent Laid-Open No. 2002-91222, because the fluorine resin sheet is attached to the peeling sheet by an adhesive, there is a problem requiring some processes such as carrying out a surface treatment such as etching on the peeling sheet, thereafter applying the adhesive to the peeling sheet, after heating and drying it, attaching the fluorine resin sheet to the peeling sheet.
Moreover, in Japanese Patent Laid-Open No. 2004-109636, because the separating pawl contacts with the fixing roller, there is a problem that the separating pawl causes damage to fixing roller.
Furthermore, in Japanese Patent Laid-Open No. 2003-122175, because a moving mechanism to move the separating plate is required, there is a problem that a structure is complicated.
An object of the present invention is to provide a separating plate capable of separating efficiently a transfer paper from a fixing member such as a fixing belt or fixing roller without requiring a complicated process and assembling accuracy, and generating a damage in the fixing member, a fixing device having the separating plate, a method for producing the separating plate and an image forming apparatus including the separating plate or the fixing device.
To accomplish the above-mentioned object, a separating plate according to one embodiment of the present invention is configured to separate a transfer paper ejected from a nipping part formed by a fixing member and a pressure member contacting with the fixing member, from the fixing member.
The separating plate includes an edge part disposed close to the fixing member.
The separating plate is disposed relative to the fixing member so that a sum of a thickness of the edge part of the separating plate and a gap formed between the edge part and the fixing member is lesser than a minimum floating amount of the transfer paper ejected from the nipping part.
Hereinafter, a best mode for carrying out the present invention will be explained based on some embodiments with reference to the accompanying drawings.
The fixing roller 61 and the pressure roller 7 hold the transfer paper 9 at a nipping part 8 formed between the fixing roller 61 and the pressure roller 7.
The fixing roller 61 includes a cored bar 61a and an elastic layer 61b. The pressure roller 11 has a heat source 11a such as a halogen heater or the like disposed therein. The fixing belt 6 includes a base member 6b and a mold releasing layer 6a (see
The fixing device 55 includes a separating plate 1 for peeling the transfer paper 9 closely fitted on the fixing belt 6 by the fixed toner on the transfer paper the from the fixing belt when the fixed transfer paper 9 is ejected from the nipping part 8 formed by the fixing belt 6 and the pressure roller 7.
The separating plate 1 has a structure shown in
Mounting holes 22a passing through a mounting shaft 5 are provided in the supporting portions 22.
The separating plate includes abutting parts 3 which are provided on areas where the transfer paper 9 does not pass, for example, opposite sides of the edge part 2 to contact with a surface of the fixing belt 6 (see
The supporting parts 22 of the separating plate 1 are rotatably attached to a suitable mounting part (not shown) through the mounting shaft 5 so that the edge part 2 approaches to the fixing belt 6 and separates from the fixing belt 6.
The separating plate 1 is rotated about the mounting shaft 5 so that the abutting parts 3 are contacted elastically with the surface of the fixing belt 6 by a biasing force of a spring 4 (see
When the abutting parts 3 of the separating plate 1 contact with the fixing belt, a gap having a predetermined dimension is established between the leading end, in other words, a tip p of the edge part 2 and the surface of the fixing belt (see
As shown in
In this example, as the three kinds of transfer papers, a tracing paper shown by a broken line, a Ricoh 6200 type-paper shown by a solid line, and a postcard shown by a chain line are used.
As is clear from
In this way, because the leading end of the transfer paper 9 ejected from the nipping part 8 lifts, if the edge part 2 of the separating plate 1 gets enters a gap between a lifted part and the fixing belt 6, it is possible to separate the transfer paper 9 from the surface of the fixing belt 6.
Here, as one example, the lift height or amount is determined based on empirical rule from a kind of the transfer paper.
In order to achieve smoothly the movement of the edge part 2 into the gap, a distance between the surface of the fixing belt 6 and the tip p of the edge part 2 of the separating plate 1 facing the fixing belt 6 is set to be lesser than a lift amount or lift height 12 of the transfer paper 9, which is obtained based on the kind and the blank space of the transfer paper 9 to be sent.
In other words, the separating plate is disposed relative to the fixing member so that a sum of a thickness of the edge part 2 of the separating plate 1 and a gap formed between the edge part and the fixing member is lesser than a minimum lift height of the transfer paper 9 ejected from the nipping part 8.
The gap 10 is set by suitably adjusting a thickness of the abutting pats 3 in accordance with the thickness of the edge part 2.
The adjustment of thickness of the abutting parts can be achieved when a process for producing the separating plate is executed as described below.
The process for the producing method includes a slitting step as shown in
More specifically, the process for producing the separating plate first includes a step for forming a rectangular slit 21 close to a location of a blank 20 corresponding to the edge part 2 of the separating plate 1 (slitting step), as shown in
Next, a rolling area 24 or location corresponding to the edge part 2 as shown in
In the rolling step, the rolling area 24 is first rolled by a first press die 31 of a hydraulic pressing machine depending on a length and a thickness of the edge part 2, as shown in
Meanwhile, the hydraulic pressing machine includes the first pressing die 31, a second pressing die 32, a third pressing die 33, and a pressing die 34 for punching. The third pressing die 33 has a surface 33a for forming a semi-circular shape.
In general, the ability of the pressing machine is determined by a load for pressing. When the blank 20 of a metallic plate having the thickness of 16 mm is rolled into the edge part 2 having the thickness of 0.2 mm, a plurality of times of rolling steps are applied to the blank by use of a die in a pressing machine having the ability of 150 to 500 tons to form the edge part 2 having a predetermined thickness.
If a pressure loading of the pressing machine is greater, the predetermined thickness of the edge part can be obtained with lesser times of rolling steps.
Next, as shown in
At this time, the abutting parts 3 are set to have a thickness adding the gap 10 to the thickness of the edge part 2 by the rolling.
In addition, abutting portions of the abutting parts with the surface of fixing belt 6 are configured to have curved surfaces, as shown in
Subsequently, as shown in
Next, as shown in the outer peripheral processing step in
The material and thickness of the blank 20 may be decided optionally based on a necessary stiffness depending on a moving speed and a passing width of the transfer paper 9. In particular, if the thickness of the edge part 2 is less than 0.1 mm, a corrugation or crack may be generated at the tip of the edge part.
If the thickness of the edge part 2 exceeds 0.5 mm, there is a limitation that a blank space must be provided on the tracing paper as shown in
As mentioned above, after the separating plate 1 is formed from the blank 20 by the pressing machine, a fluorine resin is covered on a surface of the separating plate 1 to prevent the attachment of a toner thereto right after fixation thereof.
The separating plate 1 has no function for melting the toner and attaching the melted toner to the transfer paper 9 at the nipping part 8.
A sufficient mold releasing force is not required for the separating plate 1 to achieve the function for preventing the adhesion of the toner, but it is preferable for the separating plate to form a more smoothly flat contacting surface to move smoothly the transfer paper 9 without generating orange peel or protrusions on a surface of the fluorine resin, which prevent the passing of the transfer paper.
As a result of reviewing the fluorine resin with a focus on the above, the mold releasing layer of the fixing belt or fixing roller, which is made of a material including a fluorine resin of 50 to 70 weight percents is better than as in a material including a fluorine resin of 100 weight percents in mold-release property and heat-flowability.
In addition, a primer layer is not required for the separating plate 1 by adding polyimide or polyamide-imide having an increased adhesiveness to the blank 20 to the material and a smoothly flat surface can be obtained for the separating plate 1.
For the fluorine resin, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perjluoroalkylvinylether-copolymer), FEP(tetrafluoroethylene-hexafluoroethylene-copolymer) or the like are listed as typical materials, while the fluorine resin has a high cohesive force and an insufficient dispersibility, therefore it requires a binder and occurs a spherical crystal when it is sintered, and hence has no a smooth surface.
Generally, if a fluorine resin layer is covered on the fixing roller, a finishing process such as a polishing or the like is required. In view of the fact and the function of the separating plate 1, it is possible to omit a primer or finishing process by suitably setting the mold releasing layer.
The coating of the fluorine resin is also formed on a surface where the transfer paper 9 passes. The surface where the transfer paper 9 passes means an outer corner portion or the tip p of the edge part 2, with which the transfer paper 9 ejected from the nipping part 8 contacts. Moreover, a coating is formed on each of the curved surfaces of the abutting parts 3. That is to say, in the separating plate 1, the portions contacting with the fixing belt 6 and the transfer paper 9 are coated.
In the rolling steps as shown in
In the rolling steps as shown in
In addition, instead of the rolling process of the abutting parts 3 after the edge part 2 is processed by rolling, after the abutting parts 3 are processed by rolling, the edge part 2 may be processed by rolling.
Subsequently, a further detailed process for producing the separating plate 1 is explained as follows.
A hot dip galvanized steel plate (SGCD 1) having the thickness of 1.6 mm and the size of 400 mm by 200 mm as the material of the separating plate 1 is first prepared. In the embodiment, a rectangular slit 21 having the width of 5 mm is provided close to one side of the rolling area or location 24 corresponding to the edge part 2 in the steel plate by use of the high-flex press-NS2300 tons made by Ida Engineering Co, Ltd, as shown in
One portion of the location 24 throughout the width of about 3 mm from one edge of the slit 21 is then rolled to form the abutting parts 3 having the thickness of about 0.35 mm (see
Next, an area of the location 24 other than the abutting parts 3 is further rolled to form the edge part 2 having the thickness of 0.2 mm (see
Subsequently, the outer periphery of the supporting portions 22 and the engaging part 26 is punched out along the punching out line 25 (see
Next, a fluorine-resinous paint including in solid content proportion, 60 weight percents of PTFE resin, 35 weight percents of polyimide resin, and 5 weight percents of a carbon black as an additive is sprayed on all surfaces of the separating plate where the transfer paper 9 passes, and the rolled part including the edge part 2 and the abutting parts 3 by a spray painting, after it is dried at 150° C., the separating plate is kept in an ambience of 360° C. for 20 minutes, thereby a coating of fluorine resin is completed by such a baking.
The separating plate 1 produced as the mentioned above was installed on a fixing unit in a color printer “IPSIO8000” made by Ricoh Co, Ltd, instead of a separating pawl (comparative example 1) which is mounted on the fixing unit and made of polyimide resin, and a test passing transfer papers was executed.
In the installation of the separating plate 1, the abutting parts 3 of the separating plate 1 were abutted with the both side areas of the fixing belt 6 where the transfer papers do not pass by pivoting the mounting shaft 5 having a diameter of 6 mm on both side plates of the fixing unit and by providing the spring 4 while setting a force similar to the presently set contacting load 0.25 N of the conventional separating pawl.
The thickness of the edge part 2 of the separating plate 1 was set to be 0.2 to 0.23 mm, and the gap was set to be 0.13 to 0.16 mm.
Moreover, as a comparative example 2, similarly to the method for producing the supporting member disclosed in Japanese Patent Laid-Open 2002-91222, a hot dip galvanized steel plate having the thickness of 1.6 mm is first connected to a similar hot dip galvanized steel plate having the thickness of 0.2 mm by a laser spot welding, thereafter, a silicon system-primer agent is then sprayed to the connected member, after it is dried at 150° C., a fluorine resin tape is attached to a leading end of the edge part 2 to surround the leading end from a surface facing the transfer paper to the opposite back surface.
The separating plate produced in this way is mounted on the fixing unit similarly as in the above, and a test for passing transfer papers was executed.
The results of the test are shown in a table 1 which is incorporated herein. As is clear from the table 1, various kinds of transfer papers 9 can be separated without generating abnormal images and life duration of the fixing belt 6 can be increased by the structure of the separating plate 1 as shown in the above-mentioned embodiments according to the present invention, compared with the conventional contact-type separating pawl.
In the above-mentioned embodiments, the abutting parts 3 and the edge part 2 are formed by the rolling process to have a step between the abutting parts and the edge part. However, the leading ends of the abutting parts 3 may be provided by bending them to contact with the fixing belt 6 tangentially, as shown in
The shape of the abutting parts may be selected optionally depending on a curvature of the fixing belt 6, a setting position of the separating plate 1, and a speed at which the transfer paper 9 is ejected.
The above-mentioned color laser printer has a structure in which upwardly and downwardly disposed paper feeders 42 are disposed downwardly of a main body 41 and an image forming part 43 is disposed above the feeders 42. In the printer, it is possible to use as a sheet-shaped medium any of a standard paper used for a usual copy or the like, and a special paper having a heat capacity greater than that of the standard paper and including an OHP sheet, a 90 K paper such as a card and a post card, a thick paper of basis weight, about 100 g/m2 or more, and an envelope or the like.
In addition, provided in the image forming part 43 is a transfer belt device which is disposed obliquely so that a feeding portion thereof is downwardly disposed and an ejecting portion thereof is upwardly disposed. The transfer belt device has an endless transfer belt 52 which is wound around a plurality of rollers 51, in the illustrated embodiment, four rollers 51 and rotated by driving one roller 51 by means of a drive source (not shown).
Four image forming units 44M, 44C, 44Y and 44BK for magenta (M), cyan (C), yellow (Y) and black (BK) are arranged on an upper traveling section of the transfer belt 52 in sequence from below.
A photoconductor 45 as an image carrier is provided on each of the image forming units 44M, 44C, 44Y and 44BK.
The photoconductor 45 is configured to be rotated clockwise as viewed in
Each of the developing devices 50 comprises a two ingredient developing device to which a toner is supplied by a toner supplying device which will be described below in accordance with a consumed amount of toner.
Next, an operation foe carrying out a full color print by the color printer having the structure as mentioned above is explained based on the image forming unit 44 M for magenta.
A light image developed by a magenta toner is written on the photoconductor 45 charged by the charging roller 46 by means of the light writing device 48 which illuminates a laser beam to a polygon-miller 48a driving an LD (laser diode) (not shown) and guides light reflected on the polygon-miller through a cylindrical lens or the like to the photoconductor 45. By the light writing, an electrostatic latent image based on image data sent by a host machine such as a personal computer or the like is formed on the photoconductor 45 and the latent image becomes a visible image by the toner in the developing device 50.
On the other hand, each of sheet-shaped media designated as transfer papers is supplied from each of the paper feeders 42, the supplied sheet-shaped medium is abutted once with a resist roller 53 provided at an upper stream in a direction of movement of the transfer belt 52, thereafter, it is supplied on the transfer belt 52 so as to synchronize with the visible image, and reaches a transfer position facing the photoconductor 45 by the movement of the transfer belt 52.
In this transfer position, the visible image of the magenta toner is transferred on the sheet-shaped medium by operation of the transfer roller 54 disposed to face a back side of the transfer belt 52.
Similarly to the above, the visible image of each toner even in each of the other image forming units 44C, 44Y, and 44BK is formed on a surface of the respective photoconductor 45, these visible images are overlapped and transferred every the time that the sheet-shaped medium transported by the transfer belt 52 reaches each transfer position.
Therefore, in the color printer, the full color image is overlapped and transferred on the sheet-shaped medium in a short time, similarly to a mono-color image. The sheet-shaped medium after the transfer is separated from the transfer belt 52 and fixed by a fixing device 55. After the fixing is completed, the sheet-shaped medium is ejected out of the image forming apparatus usually directly, while, the sheet-shaped medium is then turned over and ejected on an ejected tray 56 provided on an upper surface of the main body 41.
Meanwhile, although the fixing device 55 shown in
In each of the above-mentioned developing devices 50, a mixing ratio of the toner and a carrier in the apparatus is monitored, if the toner is insufficient, an insufficient amount of the toner is supplemented.
The supplementation of toner is accomplished by supplying the toner contained in a toner container 47 or toner containing device disposed at a position remote from the developing devices 50, in this embodiment, in a right and above position as shown in
In addition, although the some embodiments have been described, the present invention is not limited to the above-mentioned embodiments. For example, the fluorine resin coating is used as the mold-releasing material, but a fluorine resin sheet may be attached to the separating plate.
According to the present invention, the transfer paper can be separated from the fixing member efficiently without requiring a complicated process or assembly and damaging the fixing member such as the fixing roller or fixing belt, and hence jam or the like of the fixing member and so on can be prevented, and life duration of the fixing member can be increased.
In the above-mentioned embodiments, although the separating plate according to the present invention is applied to the image forming apparatus such as the printer or the like, without being limited to this, for example, the separating plate may be used as a scraper aligning powder.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-366252 | Dec 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/23543 | 12/16/2005 | WO | 00 | 6/8/2007 |
