Patent Grant
10969716
This application claims the benefit of Japanese Patent Application No. 2018-221778 filed on Nov. 28, 2018, which is hereby incorporated by reference herein in its entirety.
The present invention relates to an image heating apparatus for heating a toner image in a non-contact manner in an electrophotographic image forming apparatus.
In general, fixing of an image in the electrophotographic image forming apparatus refers to that toner is melted by heat and is fixed on paper under application of pressure. Conventionally, in a fixing device in the electrophotographic image forming apparatus, a toner image formed on paper is generally fixed under application of heat and pressure by a heat roller or the like.
In Japanese Laid-Open Patent Application (JP-A) 2010-122341, a technique using ultraviolet radiation (energy) to cure a developer and, before ultraviolet irradiation, pre-heating the developer by irradiating the developer with infrared radiation has been proposed as a non-contact fixing device.
In the case when the developer is heated in the non-contact manner, as in JP-A 2010-122341, a non-contact heat source has heat even when electric power supply to the non-contact heat source is turned off, so that a heated state is continued. For that reason, a predetermined time from turning-off of the non-contact heat source after an end of a job or during detection of jam occurrence until the non-contact heat source is cooled to a predetermined temperature is needed. In that case, when rotation of a belt is stopped, a part of the belt is locally heated, so that there is a liability that a lifetime of the belt is shortened.
A principal object of the present invention is to provide an image heating apparatus for reducing a degree of heating of a feeding belt by a non-contact heat source from turning-off of the non-contact heat source to a predetermined temperature.
According to one aspect, the present invention provides an image heating apparatus for heating a toner image on a recording material with a liquid developer including toner and a liquid carrier. The image heating apparatus includes a rotatable belt, a driving source, a heating portion, a shielding member, a moving mechanism, and a controller. The rotatable belt is configured to feed the recording material on which the toner image is formed. The driving source is configured to rotate the belt. The heating portion opposes the belt in non-contact with the belt and is configured to heat a developer image on the recording material on the belt by radiant heat. The shielding member is configured to shield heat of the heating portion. The moving mechanism is configured to move the shielding member between a shielding position where the heat of the heating portion is shielded from moving toward the belt between the heating portion and the belt and a retracted position where the shielding member is retracted from the shielding position during an image heating operation. The controller is configured to control the moving mechanism so that the shielding member is in the shielding position, and rotation of the belt is at rest in a stand-by state in which the image heating apparatus waits for input of an image forming signal for forming the image.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Parts (a) and (b) of
In the following, embodiments of the present invention will be specifically described with reference to the drawings by taking an image heating apparatus for fixing an image of a liquid developer as an example.
(Image Forming Apparatus)
An image forming apparatus 100 includes an image forming portion 10 for forming an image (toner image) on a recording material 16 and an image heating apparatus (heating device) 11 for heating an image 15 formed on the recording material 16 and for heating the recording material 16. Here, the recording material 16 is a material on which the toner image is formed by the image forming apparatus 100, and for example, includes a sheet such as plain paper, coated paper, a postcard, or an envelope. Further, for example, the recording material 16 may also be an OHP sheet or a film.
A cassette 25 is an accommodating portion for accommodating the recording material 16 used for image formation. The recording material 16 accommodated in the cassette 25 is fed to the image forming portion 10 by a feeding mechanism 2. The feeding mechanism 2 is, for example, a sheet (paper) feeding roller and sends the recording material 16 in the cassette 25 toward a feeding passage 26. Incidentally, the accommodating portion may also have a constitution including a plurality of cassettes and may also have a tray shape (for example, a manual feeding tray).
The recording material 16 fed from the cassette 25 by the feeding mechanism 2 passes through the feeding passage 26 and is supplied to a contact portion between an image bearing member 1 and a transfer means 4. An image on an outer peripheral surface of the image bearing member 1 is transferred by the transfer means 4 onto the recording material 16 at the contact portion between the image bearing member 1 and the transfer means 4, and thereafter, the recording material 16 passes through a feeding passage 27 and is conveyed to the image heating apparatus 11.
The image forming portion 10 forms an image 15 on the recording material 16 with the liquid developer. The liquid developer is a developer containing toner (coloring agent) and a liquid carrier. The image forming portion 10 includes a cylindrical image bearing member 1 and the transfer means 4. An image forming means (not shown) of an electrophotographic type includes a charging portion for electrically charging the image bearing member 1 to a uniform surface potential, an exposure portion for forming a latent image by light exposure, and a developing portion for developing the latent image with the liquid developer, forming an image on the outer peripheral surface of the image bearing member 1. The image 15 formed on the image bearing member 1 is transferred by a transfer roller, as the transfer means 4, onto the recording material 16 supplied to a contact portion between the image bearing member 1 and the transfer means 4. That is, an unfixed toner image 15 is formed on the recording material 16 by the image forming portion 10.
The image bearing member 1 in this embodiment includes an organic photosensitive member surface layer on a surface of an aluminum cylinder (photosensitive drum) of 3 mm in thickness and 84 mm in outer diameter and is 370 mm in width (length in a direction substantially perpendicular to a recording material feeding direction) of a long signal. The image bearing member 1 is rotationally driven about a center supporting shaft as a center in an arrow R1 direction in
Incidentally, in this embodiment, the image forming apparatus 100 had a constitution of an electrophotographic type and a direct transfer type, but an image forming method to the recording material 16 is not limited thereto. For example, the image forming method may also be a color image forming apparatus including an image forming portion using yellow toner, an image forming portion using cyan toner, an image forming portion using magenta toner, an image forming portion using black toner, and an intermediary transfer belt.
The recording material 16 on which the image 15 is formed in the image forming portion 10 passes through the feeding passage 27 and is conveyed to the image heating apparatus 11. The image heating apparatus 11 includes a heating portion 13 as a non-contact heat source and a sheet feeding (conveying) device 30. The sheet feeding device 30 includes an endless feeding (conveying) belt 31 provided with many holes. The sheet feeding device 30 also includes driving roller 35 and a follower roller 36 that stretch the feeding belt 31. The sheet feeding device 30 includes a driving motor (not shown) for rotating the feeding belt 31 via the driving roller 35. The feeding belt 31 is rotated in a direction of an arrow R2 in the figure by drive of the driving motor. The sheet feeding device 30 carries, on the feeding belt 31, the recording material 16 on which the image 15 is formed by the image forming portion 10, and a conveys the recording material 16 so that the recording material 16 passes below the heating portion 13. The feeding belt 31 in this embodiment is 500 mm in width and 900 mm in peripheral length.
A suction plate 40 and a suction fan (not shown) are provided inside the feeding belt 31 and are used as a suction device for attracting the recording material 16 conveyed by the feeding belt 31 to a peripheral surface of the feeding belt 31 via the many holes formed in the feeding belt 31. The suction plate 40 is provided with a plurality of recessed portions, and the suction fan places an inside of the recessed portions under reduced pressure via holes bored in a bottom of the recessed portions. The suction plate 40 sucks air from an upper surface of the feeding belt 31 passing on the recessed portions thereof an attracts the conveyed recording material 16 to the upper surface of the feeding belt 31.
The heating portion 13 heats the liquid developer by irradiating the image 15 of the liquid developer on the recording material 16 with infrared radiation and fixes the image 15 on the recording material 16.
(Heating Device)
As described above, the heating device 11 includes the heating portion 13 and the sheet feeding device 30. The sheet feeding device 30 is disposed immediately below portions of the heating portion 13 that are adjacently arranged in a feeding direction of the recording material 16 and is constituted so that a single feeding belt passes through an irradiation region of the heating portion 13.
(Structure of Heating Portion)
A structure of the heating portion 13 in the heating device 11 will be specifically described.
The heating device 11 includes the sheet feeding device 30 and the heating portion 13 as shown in
The heat absorbing portion 13a is constituted by a single member and is 18 J/K or more in thermal capacity, and in this embodiment, as the heat absorbing portion 13a, an aluminum plate of 2.5 mm in thickness was used and was disposed in a state in which a surface thereof having emissivity of 0.94 with use of a black-body spray (for example, “OP-96929”, manufactured by KEYENCE Corp.) faces the quartz tube 13c.
The heat absorbing portion 13a is in a retracted position during sheet passing so that the radiant heat emitted by the quartz tube 13c is radiated toward a sheet feeding surface as shown in part (a) of
(Structure of Feeding Belt and Suction Plate)
The feeding belt 31 is 500 mm in width, and the suction plate 40 is 490 mm in width, so that the feeding belt 31 sufficiently covers the suction plate 40. Thus, light radiated by the heating portion 13 does not directly heat the suction plate 40.
In this embodiment, the feeding belt 31 is made of EPDM (ethylene-propylene-diene rubber) and is 1 mm in thickness. The suction plate 40 is made of SUS 304 and is 5 mm in thickness.
(Operation of Shielding Mechanism)
An operation during jam occurrence is shown in
First, when an instruction to start printing is provided from an operating portion 60, sheet passing is started in STEP 51 of
In the case of continuous sheet passing of a plurality of sheets, the CPU 65 receives a sheet passing continuation signal from the image forming portion 10 and sends the sheet passing OK signal to the image forming portion 10 so long as the CPU 65 receives the signal of no abnormality from the heating controller 61.
When a jam occurs in STEP S2, a sequence goes to STEP S3 of
Then, the sequence goes to STEP S5. After the operation of STEP S4, the CPU 65 causes a display portion 67 to display an error message of jam occurrence. After an end of jam clearance, when discrimination display of the end of j am clearance is inputted from the operating portion, the error message of the display portion is eliminated, and the image heating apparatus returns to a stand-by state preparing for subsequent sheet passing. Incidentally, in this embodiment, a constitution in which a stop of the energization to the heater and a stop of the rotation of the feeding belt were simultaneously carried out was employed, but a constitution in which the stop of the rotation of the feeding belt is carried out after the stop of the energization to the heater may also be employed.
As a result, local heating by heat of the feeding belt by the heat source during the stop of the feeding belt when the jam occurred can be reduced.
Next an operation of the shielding mechanism after an end of image formation will be described with reference to
First, when an instruction to start printing is provided from an operating portion 60, sheet passing is started in STEP S11 of
In the case of continuous sheet passing of a plurality of sheets, the CPU 65 receives a sheet passing continuation signal from the image forming portion 10 and sends the sheet passing OK signal to the image forming portion 10 so long as the CPU 65 receives the signal of no abnormality from the heating controller 61.
When the image formation ends in STEP S12, a sequence goes to STEP S13 of
Then, the sequence goes to STEP S15. After the operation of STEP S14, the state of the CPU 65 goes to a stand-by state in which the CPU 65 waits for input of a new image forming signal. Incidentally, in this embodiment, a constitution in which a stop of the energization to the heater and a stop of the rotation of the feeding belt were simultaneously carried out was employed, but a constitution in which the stop of the rotation of the feeding belt is carried out after the stop of the energization to the heater may also be employed.
The end of the image formation in this embodiment is an end of an operation of a series of an image forming jobs. However, the present invention is not limited to this constitution, but the time of the end of the image formation may also be the time of an end of heating, by the image heating apparatus 11, of the image on the final recording material in the series of image forming jobs.
In this embodiment, when the image forming job is started, in the case when the image forming operation is not interrupted, the heat absorbing portion is continuously kept in the retracted position. In the case of a sheet interval such that the heat absorbing portion is capable of performing a reciprocating operation between the retracted position and the shielding position, a constitution in which the heat absorbing portion is moved between the retracted position and the shielding position at each of sheet intervals may also be employed.
(Confirmation of Effect)
A comparison example is shown in
In order to confirm an effect of this embodiment, in the constitution of the comparison example and the constitution of this embodiment, the following experiments 1 and 2 were conducted.
The feeding belt 31 was idled for 30 minutes at a process speed of 175 mm/s in a condition that a heating amount of an infrared irradiation device (“IR10545H”, manufactured by SAKAGUCHI E.H VOC CORP.) was 1000 W, and thereafter energization to the infrared irradiation device was turned off. Then, a temperature of the feeding belt 31 was measured at a position immediately below the infrared irradiation device.
A 50 μm-thick polystyrene film was applied onto the feeding belt 31. The feeding belt 31 was idled for 30 minutes at a process speed of 175 mm/s in a condition that a heating amount of an infrared irradiation device (“IR10545H”, manufactured by SAKAGUCHI E.H VOC CORP.) was 1000 W, and thereafter energization to the infrared irradiation device was turned off. Then, a media temperature was measured at a position immediately below the infrared irradiation device.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2018-221778 | Nov 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5887238 | Matsuzoe | Mar 1999 | A |
| 20160070212 | Kamoda | Mar 2016 | A1 |
| 20160170339 | Takeda | Jun 2016 | A1 |
| 20170199489 | Shimomura | Jul 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| 2010-122341 | Jun 2010 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20200166877 A1 | May 2020 | US |
