Patent Grant
7437085
1. Field of the Invention
The present invention relates to a fixing apparatus and an image forming apparatus.
2. Description of the Related Art
Requirements for picture quality have been raised to higher and higher level as an image forming apparatus for forming an image on a recording material has been used in a variety of fields. As one of factors which determine the picture quality, particularly, the degree of gloss of full-color image, smoothness of output image can be mentioned.
To meet such a demand, for example, Japanese Patent Application Laid-Open NO. 64-35452 and Japanese Patent Application Laid-Open No. 5-216322 have disclosed an image forming method of forming color images by heating and melting color toner images after the color toner images of thermoplastic resin are transferred to a recording material in which transparent resin layer of thermoplastic resin is formed. As a preferred fixing method of these image forming methods, a belt fixing apparatus has been proposed.
As this belt fixing apparatus, for example, the belt fixing apparatuses described in Japanese Patent Application Laid-Open No. 5-216580 and Japanese Patent Application Laid-Open No. 4-362679 have been known. In the belt fixing apparatuses described in the Japanese Patent Application Laid-Open No. 5-216580 and Japanese Patent Application Laid-Open No. 4-362679, a recording material bearing a non-fixed toner image is pressed and heated with the fixing belt composed of heat resistant film and this recording material is cooled while kept in firm contact with the fixing belt so as to harden the toner image and then, the recording material to which the toner image is fixed is separated from the fixing belt.
As a result, with the toner image buried in transparent resin layer of the recording material, the transparent resin layer and toner image fixed on a surface of the recording material are coagulated along the belt surface configuration and the entire surface of the recording material turns to a smooth one, so as to obtain a color image excellent in the gloss property.
As the recording material having resin layer used in such an image forming apparatus, various recording materials as described in Japanese Patent Application Laid-Open No. 2003-84477 have been proposed. Japanese Patent Application Laid-Open No. 2003-84477 has proposed an electronic photographic transfer sheet in coated with resin layer mainly composed of thermoplastic resin having a glass transition temperature of 85% or less in the thickness of about 10 μm.
However, under the above-described structure, the apparatus is stopped at the same time as detection timing of an error in the apparatus if the error occurs in the downstream of a cooling means. Thus, the recording material before cooling can stop on an endless belt. In the meantime, the fixing apparatus includes art for stopping transportation of recording materials located in the upstream relative to an error position at the same time when the error is detected in that fixing apparatus, such as jamming of the recording material, and discharging recording materials located in the downstream relative to the error position. Even if this art is applied to a conventional structure including the fixing belt, the recording material can stop on the endless belt when any error occurs in the downstream of the fixing apparatus.
The recording material after heating and pressurization adheres to the endless belt strongly until it is cooled so that it is fixed thereto. Thus, if the recording material is left on the endless belt before cooling, it is difficult to remove the recording material left in the fixing apparatus. Further, there is a problem that if the endless belt is damaged or there is left fragments of the recording material not separated within the apparatus, fixing property after an error occurs may drop.
Accordingly, an object of the present invention is to provide a fixing apparatus capable of improving the performance of removal of residual recording material within the apparatus.
To achieve above-mentioned object, the present invention provides a fixing apparatus comprising:
a fixing rotary body;
a rotary body provided with an interval from the fixing rotary body;
an endless belt rotating in a condition in which it is wound around the fixing rotary body and the rotary body;
a pressure rotary body which makes a pressure contact with the fixing roller across the endless belt;
a heater for heating a recording material conveyed by the endless belt;
a cooling unit for cooling a recording material conveyed by the endless belt and heated by the heater; and
an error detecting means for detecting an error in conveyance of the recording material, wherein
when an error is detected in the downstream of the cooling unit by the error detecting means, the recording material is stopped after the recording material on the endless belt is conveyed to a position in which the cooling unit cools the recording material.
According to the present invention, there is left no recording material on the endless belt before cooling from which the recording material is hard to separate when the fixing apparatus is stopped even if any error occurs in the fixing apparatus. Therefore, the performance of removal is improved so as to facilitate removal of the recording material.
The invention, together with further advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:
Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. In the meantime, like reference numerals are attached to the same components or corresponding ones in all drawings of following embodiments. The dimension, material, shape and relative arrangement of the components described in this embodiment should be changed appropriately depending on the structure of the apparatus to which the invention is applied and various conditions and do not restrict the scope of the present invention to following embodiments.
Hereinafter, one embodiment of the invention will be described with reference to the drawings. In the meantime, like reference numerals are attached to the same components or corresponding ones in all drawings of following embodiment.
This image forming apparatus transfers toner images onto the recording material P successively in each color station so as to obtain a toner image. That is, as an image forming means, transfer units for forming four colors of black BK, cyan C, magenta M and yellow Y on the recording material P are provided. These transfer units include photosensitive drums 11a to 11d, exposure units 12a to 12d, chargers 21a to 21d, development units 31a to 31d and transfer rollers 22a to 22d. The recording materials P on which an image is to be formed are stacked and stored in cassettes 3a, 3b and picked up by pickup rollers 13a, 13b and conveyed onto an endless transfer belt 32 by conveyance rollers 23a, 23b.
The toner image formed on the recording material P is fixed by a fixing portion 40 as a fixing means within the image forming apparatus. This image recording apparatus can be set to mode A (plain paper recording mode) and mode B (photography mode).
Under mode A, the recording material P stored in a paper feed unit (for example, 81 g plain papers) is fed from the paper feed unit and a toner image is transferred and the toner image is fixed on the recording material P by the fixing portion 40. After that, the recording material P passes a conveyance passage 46 and is conveyed to the fixing apparatus 50. The recording material P is conveyed successively through a conveyance passage 104 as a common passage by conveyance rollers 70, 71, 72, 73. The recording material P is changed over by a flapper 107 as a changing means after it passes and conveyed through a conveyance passage 108 as a second passage and discharged to an discharge tray 31a by a discharge roller 74.
On the other hand, under mode B, the recording material P stored in the paper feed unit is supplied and a toner image is transferred while the paper passes the fixing portion 40. After that, the recording material P passes through the conveyance passage 46 and is conveyed to the fixing apparatus 50. The recording material P is conveyed through the conveyance passage 104 successively by the conveyance rollers 70, 71, 72, 73 and the passage is changed over by the flapper 107 so that the recording material P is conveyed to a conveyance passage 105 side which is part of the first passage. After that, fixing processing is carried out by the fixing belt 56 which is an endless belt. Subsequently, the recording material P is conveyed through a conveyance passage 106 which is part of the first passage and a predetermined processing is carried out by cutters 83, 84 successively and cut papers are discharged to the discharge tray 31b.
Roller heaters 59, 58, which are heaters for heating the recording material, are disposed within the fixing roller 51 and the pressure roller 52 respectively. These roller heaters 58, 59 are controlled in temperature by temperature sensors 85, 86, which are composed of a thermistor.
The fixing roller 51 is constituted of concentric three layers. The three layer structure includes a core portion, an elastic layer and a separation layer. The core portion of these is constituted of an aluminum made hollow pipe of 44 mm in diameter and 5 mm in thickness. In the meantime, a halogen lamp is disposed as a heat source within the hollow pipe of the core portion. The elastic layer is composed of silicone rubber having JIS-A hardness of 50 degrees and a thickness of 3 mm. The separation layer is composed of PFA of 50 μm in thickness. The pressure roller 52 adopts the same structure.
The fixing belt 56 is constituted of two layer structure in which a mirror-like separation layer is provided on a face (first surface) which makes contact with the recording material P or the pressure roller 52 and a base material is provided on a face (second surface) which makes contact with the fixing roller 51. The separation layer of these is constituted of PFA of 10 μm in thickness. The base material is constituted of an endless belt of stainless sheet of 100 μm in thickness.
The cooling fan 55 in a cooling area is provided inside the fixing belt 56. Air flow is blown in the direction perpendicular to the paper surface of the recording material P by the cooling fan 55.
The fixing belt 56 is supplied with a predetermined tension by the tension roller 54. When the fixing roller 51 is driven in rotation in the right direction in
The roller heaters 58, 59 constituted of halogen lamps disposed within each of the fixing roller 51 and the pressure roller 52 are supplied with electric power. Consequently, the surface temperatures of the fixing roller 51 and the pressure roller 52 are raised.
Next, the recording material P will be described. That is, the recording material for use in this embodiment is comprised of base material having pigment coating layer on at least one surface and resin layer provided on the pigment coating layer. The pigment coating layer is composed of mainly adhesive agent and pigment and the resin layer is composed of mainly thermoplastic resin.
Although this resin layer includes thermoplastic resin and thermosetting resin as its main component, it may be mixed resin layer which is mixed with thermoplastic resin and thermosetting resin. Further, the resin layer may be constituted of a plurality of layers including thermoplastic resin layer composed of mainly thermoplastic resin and thermosetting resin layer composed of mainly thermosetting resin.
When the resin layer is constituted of a plurality of layers, it is preferable to provide the thermosetting resin layer composed of mainly thermosetting resin on the topmost layer. Further, the resin layer may be constructed by combining the mixed resin layer, the thermoplastic resin layer and the thermosetting resin layer. In this case, the topmost layer is preferred to be composed of a layer including thermosetting resin, such as the mixed resin layer and the thermosetting resin layer. The thermoplastic resin includes polyester resin, styrene-acrylic acid ester and styrene-methacrylate ester and particularly, it is preferable to use polyester resin.
Next, control of the fixing apparatus of this embodiment will be described. FIG 3 shows a controller for controlling the fixing apparatus 50 of this embodiment. In
The I/O port 404 is connected to a driver 405. An output of the I/O port 404 is converted to a necessary drive voltage and supplied to various loads 407. Each load 407 includes a heater, a paper feeding motor for driving the conveyance roller, a motor, clutch and solenoid for cutting the recording material P. Further, the load 407 includes the fixing roller 51 and a motor for rotating the fixing belt 56 by driving the rotary roller 53. Serial communication interface 409 (SCI) is an interface which executes transmission/receiving of information between the CPU 401 and a controller (not shown) in the image forming apparatus A.
The temperature sensors 85, 86 (see
Next, the image forming operation at normal time of the fixing apparatus according to an embodiment will be described.
First, the recording material P output from the image forming apparatus A is conveyed to the fixing apparatus 50. The recording material P is conveyed through the conveyance passage 104 successively by the conveyance rollers 70, 71, 72, 73. The recording material P after passing the conveyance passage 104 is conveyed to the conveyance passage 105 following a selection by the flapper 107. After that, the recording material P passes the sensor 62 and is stopped when its front end is nipped by the resist roller pair 63. In the meantime, the rotation of the fixing belt 56 is continued.
A desired position of the fixing belt is detected by the sensor 61 and the resist roller pair 63 starts rotation again by synchronizing a timing when a recording material bonding position HT on the fixing belt 56 reaches a nipping position between the fixing roller 51, the fixing belt 56 and the pressure roller 52 with a timing when the topmost end of the recording material P reaches a fixing nip portion and then, the recording material P is conveyed into the fixing nip portion.
After that, the recording material P passes a pressure contact portion between the fixing belt 56 and the pressure belt 52. At this time, heat from the fixing roller 51 and the pressure roller 52 is added to the recording material P and toner T on the recording material P. Thus, the temperature of the transparent resin layer L2 within the recording material P is raised so that it is softened and further, pressures by the fixing roller 51 and the pressure roller 52 are added. As a result, toner image in a condition as shown in
After that, the recording material P is conveyed into the cooling area with a rotation of the fixing belt 56 in a condition in which it adheres to the fixing belt 56. The recording material P is cooled compulsorily and effectively in the cooling area by an action of the cooling fan and air flow within an air duct surrounding the cooling fan 55.
The recording material P adhering to the surface of the fixing belt 56 is thus cooled in the cooling area of the cooling fan 55. Then, as shown in
As shown in
Next, a series of continuous operation at normal time of the image forming system according to the embodiment will be described. Here, an image output under photography mode having continuous five pieces will be described.
As shown in
At this time, a third sheet P3 passes the fixing portion 40 of the image forming apparatus A. Further, the image forming operation is executed on a fourth sheet P4 on the transfer belt and a fifth sheet P5 is located at a position in which it is supplied from the paper feeding portion. Then, the desired position of the fixing belt is detected by the sensor 61 for the first sheet P1 and the resist roller pair 63 are started to rotation by synchronizing a timing when the recording material bonding position HT on the fixing belt 56 reaches the nipping portion (fixing nipping portion) between the fixing roller 51, the fixing belt 56 and the pressure roller 52 with a timing when the topmost end portion of the first sheet P1 reaches the fixing nipping portion. As a consequence, the first sheet is conveyed into the fixing nipping portion.
After that, the first sheet P1 passes the pressure contact portion between the fixing belt 56 and the pressure roller 52. At this time, the first sheet P1 and toner T on the first sheet P1 are heated by the fixing roller 51 and the pressure roller 52. Thus, the temperature of the transparent resin layer L2 of the first sheet P1 rises so that it is softened and pressures of the fixing roller 51 and the pressure roller 52 are added thereto. As a result, a toner image in the condition shown in
The first sheet P1 is conveyed through the cooling area with a rotation of the fixing belt 56 in a condition in which it adheres to the fixing belt 56. The first sheet P1 is cooled compulsorily and effectively by an action of air flow within the cooling fan 55 and the air duct (not shown) surrounding the cooling fan 55. In the meantime, the cooling fan 55 is so constructed to be capable of changing the flow rate of the air flow. Consequently, a flow rate of the air flow which allows the recording material P on the fixing belt 56 to be separated easily can be set up.
The first sheet P1 adhering to the surface of the fixing belt 56 is cooled sufficiently in the cooling area. The first sheet P1 is separated by its own stiffness (rigidity) from the surface of the fixing belt 56 in an area in which the curvature of the fixing belt 56 is changed by the rotary roller 53.
As shown in
As shown in
After that, as shown in
Subsequently, the first sheet P1 is conveyed to the cutter registration sensor 99 and cut out by the cutters 83, 84 based on a predetermined sequence. The vertical and horizontal ends of the first sheet P1 are cut at the cutting widths WT, WY shorter than the margin width of the first sheet P1 and the cut sheets are discharged to the discharge tray 31b by a conveyance roller 82. The same cutting treatment as the first sheet P1 is carried out on following second sheet P2 to fifth sheet P5 and they are discharged to the discharge tray 31b.
The conveyance speed of the recording material by the fixing belt 56 is slower than the conveyance speed by the conveyance rollers 77, 78, 79, 82 provided in the downstream of the cooling means.
Next, a series of continuous operations when an error occurs of the image forming apparatus according to this embodiment will be described. This embodiment will be described by exemplifying a case where images are output under photography mode of continuous five pieces of photos.
As shown in
More specifically, unless after a photo sensor detects a passage of the recording material, a photo sensor located one step down in the downstream with respect to that photo sensor detects the front end of the recording material within a predetermined time period, it is regarded that a delay jam (delay JAM) occurs so as to carry out an error treatment. Similarly, even if the recording material P is left within the fixing apparatus when the fixing apparatus is powered on, the same processing as described below is carried out.
If a recording material detection time by the photo sensors 62 to 100 for detecting the recording material P is longer than a predetermined time, error treatment is carried out as a holding jam (holding JAM). As shown in
Contrary to this, the cooling operation of the cooling fan 55 and conveyance of the second sheet P2 on the fixing belt 56 are continued. Conveyance of the second sheet P2 is stopped a predetermined time after the second sheet P2 is conveyed from the resist roller pair 63 so that the resist turns on or at a timing based on detection of a recording material by the separation sensor 96 and the cooling fan 55 is stopped. The predetermined time after the second sheet P2 is conveyed from the resist roller pair 63 so that the resist turns on or the timing based on detection of the recording material by the separation sensor 96 refers to a period after the second sheet P2 is conveyed to the cooling position by the cooling fan 55.
Paper jam and an instruction for removing it are indicated on the display portion (not shown) of the image forming apparatus so as to urge user for the execution. Even if the recording material P is left within the fixing apparatus when the fixing apparatus is powered on, the recording material P is conveyed up to the position of the cooling fan 55. Consequently, not only processing of keeping out a recording material from the endless belt before cooling is enabled reliably but also processing of keeping out any recording material from the endless belt before cooling is enabled even if the apparatus is stopped.
Next, a series of the continuous operations when an error occurs of the image forming apparatus according to this embodiment will be described.
First, in step S701, whether or not the interior of the apparatus is full of paper scraps cut by the cutters 83, 84 or the aforementioned errors such as delay jam or holding jam is generated is monitored by the CPU 401 at a predetermined interval. If the CPU 401 determines that the interior of the apparatus is not full of the paper scraps or no error such as delay jam or holding jam exists in step S701 (S701: NO), the procedure proceeds to step S702, in which the CPU 401 controls to continue the above-described normal conveyance processing.
On the other hand, if the CPU 401 determines that an error occurs in step S701 (S701: YES), the procedure proceeds to step S703. In step S703, whether or not a detected error position is in the downstream of the separation sensor 96 (see
If the CPU 401 determines that no recording material P exists on the fixing belt 56 in step S704 (S704: NO), the procedure proceeds to step S707, in which the CPU 401 controls to stop the image forming apparatus. On the other hand, if the CPU 401 determines that a recording material exists on the fixing belt 56 in step S704 (S704: YES), the procedure proceeds to step S705.
In step S705, the CPU 401 controls to stop conveyance operation other than for the recording material P existing on the fixing belt 56. The recording material P on the fixing belt 56 is conveyed up to a position which enables the recording material P to secure a sufficient cooling effect by the cooling fan 55. According to this embodiment, after the recording material P on the fixing belt 56 is detected by the sensor 96, the CPU 401 controls to stop the conveyance of the recording material and subsequently, the procedure proceeds to step S707, in which the CPU 401 stops the fixing apparatus.
The above-described embodiment indicates an example in which the apparatus is stopped when the error detection position is in the upstream of the sensor 96. However, when the recording material exists on the fixing belt 56 even if the error detection position is in the upstream of the sensor 96, the recording material on the fixing belt 56 may be controlled to be conveyed at least up to the sensor 96. If the error detection position is in the upstream of the sensor 96, it is permissible to continue the conveyance or processing of a recording material in the downstream of the error detection position and stop conveyance of the recording material existing in the upstream of the error position.
According to this embodiment, as described above, even if an error occurs in the fixing apparatus or the image forming apparatus, the recording material P before cooling is not left on the fixing belt 56. Thus, removal of the recording material P is facilitated and damage of the fixing belt 56 or contamination of the fixing belt 56 by resin of recording material can be prevented.
Although the embodiment of the present invention has been described specifically, the present invention is not restricted to the above-described embodiments but may be modified in various ways based on the technical spirit of the invention. For example, the materials mentioned in the above embodiment are only an example and other material may be used as required.
In the above-described embodiment, the sensor 96 is used to detect the position of the recording material P in step S706. However, the present invention is not restricted to this example. If any recording material exists on the fixing belt 56, the CPU 401 may control driving of the fixing belt 56 or the conveyance roller 77 to stop the conveyance of the recording material after the recording material on the fixing belt 56 is conveyed to the position in which the recording material is cooled by the cooling fan 55. For example, the position of the recording material may be deterred from a timing in which registration of the resist roller pair 63 turns on instead of detection of the recording material by the sensor 96 in step S706. That is, the CPU 401 may control to stop the recording material when a predetermined time elapses since the rotation of the resist roller pair 63 starts, so that the recording material is conveyed to a position in which it is cooled by the cooling fan. Further, the recording material P may be detected based on a timing when a predetermined time elapses since when it is detected by photo sensors for detecting the other positions of the recording material P.
If an error occurs in conveyance of the recording material and the CPU 401 determines that the recording material exists on the fixing belt 56, the CPU 401 may control to increase the cooling intensity of the cooling fan 55. For example, the rotation number of the cooling fan 55 is controlled by the CPU 401 to change the cooling intensity of the cooling fan 55. Then, the cooling intensity of the cooling fan 55 is increased when the CPU 401 controls the rotation number of the cooling fan 55, so as to accelerate the rotation speed of the cooling fan 55.
Although this embodiment has been described about a case where the jammed first sheet P1 is in the lowest downstream, any method of stopping the conveyance at the same time when an error is detected or discharging to the discharge tray 51b may be adopted for sheets located in the downstream of the first sheet P1.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-221919 | Jul 2005 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4497569 | Booth, Sr. | Feb 1985 | A |
| 4730204 | Satoh et al. | Mar 1988 | A |
| 5678123 | Kim | Oct 1997 | A |
| 5761567 | Yoshizuka | Jun 1998 | A |
| 5933677 | Lee | Aug 1999 | A |
| 6007918 | Tan et al. | Dec 1999 | A |
| 6271870 | Jacob et al. | Aug 2001 | B1 |
| 6374063 | Todome | Apr 2002 | B1 |
| 6539185 | Hanyu et al. | Mar 2003 | B2 |
| 6567640 | Ishikawa et al. | May 2003 | B2 |
| 6580884 | Kuwabara | Jun 2003 | B2 |
| 6934507 | Ohki et al. | Aug 2005 | B2 |
| 6985677 | Yamagata et al. | Jan 2006 | B2 |
| 7389078 | Daishi et al. | Jun 2008 | B2 |
| 20020098022 | Kabashima | Jul 2002 | A1 |
| 20040091296 | Ishizuka et al. | May 2004 | A1 |
| 20060131301 | Ohta et al. | Jun 2006 | A1 |
| 20060157475 | Nishihara et al. | Jul 2006 | A1 |
| 20070053708 | Mori et al. | Mar 2007 | A1 |
| 20070059057 | Kinoshita et al. | Mar 2007 | A1 |
| 20070166086 | Toyohara et al. | Jul 2007 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 301 585 | Feb 1989 | EP |
| 64-35452 | Feb 1989 | JP |
| 4-362679 | Dec 1992 | JP |
| 5-216322 | Aug 1993 | JP |
| 5-216580 | Aug 1993 | JP |
| 2003-84477 | Mar 2003 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20070025751 A1 | Feb 2007 | US |
