Patent Grant
9715199
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine or a multi-function machine having a plurality of functions of these machines.
Conventionally, in an electrophotographic image forming apparatus, a toner image is formed on a recording material (sheet) using an electrophotographic process and is fixed on the recording material by heating the recording material by a pair of rotatable members of a fixing device while nipping and feeding the recording material.
In such an image forming apparatus, a constitution in which electric power supply to a driving source for driving the fixing device is interrupted when an openable door is opened for permitting access to the fixing device has been proposed (see, Japanese Laid-Open Patent Application 2000-134787).
However, in the case of a constitution in which the electric power supply to the driving source for driving the fixing device is forcedly interrupted with opening of the openable door, for example, the electric power supply is interrupted also in the case where the openable door is opened for jam clearance (for removing a stagnated recording material by an operator). On the other hand, in order to facilitate a jam clearance operation by the operator, it is preferable that a state in which the pair of rotatable members is pressed against each other is eliminated or that the pair of rotatable members is placed in a light-pressure state. In such the background, when the openable door is erroneously opened, the electric power supply to the driving source is interrupted, so that transfer of the pair of rotatable members to the pressure-released state or the light-pressure state cannot be performed. Incidentally, such a problem can arise not only in the fixing device but also similarly in a feeding device for feeding the recording material.
According to the present invention, there is provided an image forming apparatus comprising: an apparatus main assembly including a door; a feeding unit including first and second rotatable members configured to form a nip for feeding a sheet and a moving mechanism configured to move the first rotatable member in a spacing direction from the second rotatable member, wherein the feeding unit is detachably mountable to the apparatus main assembly with opening of the door; a power source provided in the apparatus main assembly; a driving source, provided in the apparatus main assembly, configured to drive the moving mechanism; and an electric power supplying path capable of supplying electric power from the power source to the driving source via the feeding unit despite the door being in an open state.
An embodiment of the present invention will be described using
[Image Forming Apparatus]
An image forming apparatus 10 in this embodiment is a full-color printer employing an electrophotographic type. Such an image forming apparatus 10 includes an image forming portion 11 for forming a toner image and a recording material feeding portion 12 for feeding a recording material (sheet) for transferring thereon the toner image formed by the image forming portion 11. Incidentally, as the recording material, it is possible to cite, for example, a transfer sheet, an electrofax sheet, electrostatic recording paper, an OHP sheet, printing paper, format paper, and so on. The image forming portion 11 has a constitution of a so-called tandem type in which a plurality of image forming stations 1a, 1b, 1c, 1d are arranged in a traveling direction of an intermediary transfer belt 13. At the image forming stations 1a, 1b, 1c, 1d, toner images of yellow, magenta, cyan, and black are formed, respectively. In the case of this embodiment, each of the respective image forming stations 1a, 1b, 1c, 1d is constituted by a process cartridge.
At each of the image forming stations, the toner image is formed in the following manner. First, a surface of a photosensitive drum 14 is electrically charged by a charging device such as a charging roller, and the charged surface of the photosensitive drum 14 is exposed by an exposure device 15 to light depending on image information by a laser or the like, so that an electrostatic latent image is formed. Then, the electrostatic latent image is developed with a toner by a developing device, so that the toner image is formed on the surface of the photosensitive drum 14.
The toner images formed on the surfaces of the photosensitive drums 14 of the respective image forming stations are successively transferred superposedly on the intermediary transfer belt 13 at primary transfer portions T1, so that a full-color toner image is formed on the intermediary transfer belt 13. At the primary transfer portion T1, a primary transfer roller 16 as a primary transfer portion is disposed opposed to the photosensitive drum 14 while sandwiching the intermediary transfer belt 13 therebetween. Then, by applying a primary transfer bias between the primary transfer roller 16 and the photosensitive drum 14, the toner image on the photosensitive drum 14 is transferred onto the intermediary transfer belt 13.
The toner images on the intermediary transfer belt 13 are transferred onto a recording material P fed by a recording material feeding portion 12 at a secondary transfer portion T2. At the secondary transfer portion T2, an inner secondary transfer roller 17a and an outer secondary transfer roller 17b which are provided opposed to each other while sandwiching the intermediary transfer belt 13 therebetween are disposed. Then, by applying a secondary transfer bias between the inner secondary transfer roller 17a and the outer secondary transfer roller 17b, the toner images on the intermediary transfer belt 13 are transferred onto the recording material P. The recording material P on which the toner images are transferred is heated and pressed by a fixing device 100 as a heating device, so that the toner images are fixed. Details of the fixing device 100 will be described later. The recording material P on which the toner images are fixed is discharged onto a discharge tray 19 by a discharging roller 19.
The recording material feeding portion 12 is constituted by a plurality of feeding rollers, and the recording material P accommodated in a cassette 20 is picked up by a pick-up roller 21 and is fed to a feeding path 22. The recording material P fed to the feeding path 22 is fed to the secondary transfer portion T2 by a registration roller pair 23 by being timed to the toner images formed on the image forming portion 11. Further, the recording material P discharged from the fixing device 100 is reversed for effecting double-side printing and is fed to a reverse feeding path 30 in addition to the discharge onto the discharge tray 19 as described above. The recording material P fed through the reverse feeding path 30 merges with the feeding path 22 and is fed to the secondary transfer portion T2 similarly as described above.
Further, in the case of this embodiment, on an apparatus main assembly 24 in which the above-described various devices are disposed, an openable door 25 for permitting access to internal parts (components) is provided so as to open and close freely. The openable door 25 is provided rotatably about a rotation shaft 26 on a side where the feeding path 22 and the fixing device 100 are disposed. Then, by opening the openable door 25, the fixing device 100 and the feeding path 22 are exposed, so that mounting and demounting of the fixing device 100 and removal of a jammed recording material become possible. For this reason, the fixing device 100 is provided so as to be detachably mountable to the apparatus main assembly 24. A one-side roller of a feeding roller pair such as the registration roller pair 23 is disposed in the feeding path 22, and the outer secondary transfer roller 17b constituting the secondary transfer portion T2 is provided on the openable door 25 side. Further, when the openable door 25 is opened, these rollers are spaced from the opposing rollers and the intermediary transfer belt 13.
[Fixing Device]
Next, details of the fixing device (image heating apparatus) 100 functioning as a feeding unit for nipping and feeding the recording material (sheet) will be described using
The fixing film 101 is a cylindrical heat-resistant member obtained by forming an elastic layer on a base layer of a cylindrical thin metal, and is loosely fitted in locus-regulating members 105 disposed at both end portions of the fixing film 101. With respect to such a fixing film 101, in order to improve a quick start property by making a thermal capacity small, a film thickness is made 100 μm or less, preferably 20 μm or more and 50 μm or less. The fixing film 101 may also be a film including a base layer formed of metal such as SUS or may also be a single-layer film such as PTFE, PFA or FEP which have a heat-resistant property. Or, the fixing film 101 may also be a composite-layer film including a base layer of polyimide, polyamideimide, PEEK, PES, PPS or the like and a coating or coated layer of PTFE, PFA, FEP or the like on an outer peripheral surface of the base layer.
The opposite roller 102 is constituted by a core metal consisting of metal such as iron and a heat-resistant elastic material layer, molded and coated concentrically integrally about the core metal, formed of a silicone rubber, a fluorine-containing rubber or a fluorine-containing resin, and a parting layer is provided as a surface layer. For example, as a material for the parting layer, it is possible to select a material, having a good parting property and a good heat-resistant property, such as a fluorine-containing resin, a silicone resin, a fluorine silicon rubber, a fluorine-containing rubber or a silicone rubber. At both end portions of the core metal, unshown pressing member supporting members consisting of a heat-resistant resin such as PEEK, PPS or a liquid crystal polymer are mounted and rotatably supported. Further, the opposite roller 102 is driven by a motor 131, as a driving source, provided in the apparatus main assembly 24. The fixing film 101 is rotated by rotationally driving the opposite roller 102, and feeds the recording material nipped in the nip N.
As described above, the locus-regulating members 105 fitted in the fixing film 101 at the both end portions of the fixing film 101 are members consisting of PET, PPS, LCP or the like which is the heat-resistant resin. Such a locus-regulating member 105 is movably supported by a side plate of the fixing device 100, and not only rotatably supports the fixing film 101 but also is disposed in a casing of the fixing device 100. Then, the locus-regulating member 105 not only guides rotation of the fixing film 101 but also functions as an abutting portion of the fixing film 101 in a longitudinal direction (direction crossing a recording material feeding direction at the nip N).
Inside the fixing film 101, a stay 106 is disposed along the longitudinal direction, and both end portions of the stay 106 are supported by the locus-regulating members 105. Such a stay 106 is a member principally consisting of a metal such as iron or SUS. Further, on an opposite roller 102 side of the stay 106, a press-contact member 107 is disposed. Further, by pressing the stay 106 against the press-contact member 107 made by a relatively soft resin, the press-contact member 107 is caused to have a strength with respect to the longitudinal direction (direction crossing the recording material feeding direction at the nip N) and the press-contact member 107 is rectified.
The press-contact member 107 is a heat-resistant and heat-insulating member having a substantially semi-circular shape in cross-section. For example, the press-contact member 107 is formed of a material, having a good insulating property and a good heat-resistant property, such as a phenolic resin, a polyimide resin, a polyamide resin, a polyamideimide resin, PEEK resin, PES resin, PPS resin, PFA resin, PTFE resin or LCP resin. Further, the press-contact member 107 performs functions of backing-up the fixing film 101, being press-contacted against the fixing film 101 toward the opposite roller 102 and realizing feeding stability of the fixing film 101 during rotation.
A ceramic heater (herein after referred to as a heater) 104 as a heating source is supported by the press-contact member 107. The heater 104 is engaged in a groove formed on a surface of the press-contact member 107 on the nip N side along the longitudinal direction and is supported. The heater 104 includes, as a basic structure, an elongated thin plate-like ceramic substrate and an electric power supplying heat generating resistor layer, and is a low thermal capacitance heater increasing in temperature with an abrupt rising characteristic as a whole by electric power supply to the heat generating resistor layer.
Further, in the case of this embodiment, the fixing film 101 is pressed toward the opposite roller 101 by a pressing member 108, so that the above-described nip N is formed. Such a pressing member 108 stretches a spring 109 as a pressing elastic member as shown in
The pressure eliminating mechanism 103 functioning as a moving mechanism moves the above-described pressing member 108 to switch a state of the fixing film 101 and the opposite roller 102 between a state in which the fixing film 101 and the opposite roller 102 are pressed at the nip N and a state in which this (pressed) state is eliminated (a state in which the pressure is substantially eliminated or a state in which the pressure is lighter than that during the fixing). Such a pressure eliminating mechanism 103 includes a cam 103a and a cam contact surface 103b contacting a cam surface of the cam 103a formed on the pressing member 108. The cam 103a is driven by a motor 131, as a driving source, provided in the apparatus main assembly 24 and described later, and performs pressure application and pressure (application) elimination of the nip N (the pressure at the nip N during the fixing is eliminated or reduced) by causing the cam surface to contact or be spaced from the cam contact surface 103b of the pressing member 108.
During the pressure application of the nip N, as shown in
On the other hand, during the pressure elimination, the cam 103a rotates substantially 180 deg. from the state of
[Mounting and Demounting of Fixing Device]
As described above, the fixing device 100 is detachably mountable to the apparatus main assembly 24 as shown in
Further, during the mounting and the demounting of such a fixing device 100, a first connector 121 (main assembly-side connector) shown in
[Effect Power Supplying Path]
The electric power supplying path 123 supplies, as shown in
Incidentally, as the first connector 121 and the second connector 122, drawer connectors are used in an illustrated example, but if connectors can satisfy an equivalent function, the first and second connectors are not limited thereto. For example, such a type that a leaf spring member having elasticity is contacted to a metal plate member constituting a contact (point) or the like type may also be employed.
Here, the apparatus main assembly 24 is provided with a plurality of doors including the openable door 25 and includes interlock switches 27 which interrupt the electric power supply from the power source to the image forming portion 11 and the recording material feeding portion 12 by opening the doors. Accordingly, for example, when the openable door for permitting access to the image forming portion 11 is opened, the electric power supply to the image forming portion 11 is forcedly interrupted. Or, when the openable door for permitting the access to the image forming portion 11 is opened, a state in which the electric power supply to the image forming portion 11 cannot be made is formed. Such a constitution is similar also for the recording material feeding portion 12. Incidentally, the interlock switch extends via the electric power supplying path toward the heater 104 of the fixing device 100 and interrupts the electric power supply to the heater 104 by the opening of any of the doors including the openable door 25.
However, in this embodiment, the electric power supplying path 123 toward the motor 131 of the fixing driving portion 130 does not extend via all of the interlock switches. Accordingly, the electric power supplying path 123 is capable of supplying the electric power from the power source 120 to the motor 131 irrespective of the opening and the closing of the openable door 25. That is, even when the openable door 25 is opened, if the fixing device 100 is mounted in the apparatus main assembly 24, a state in which the electric power is supplied to the motor 131 is formed. Particularly, in the case of this embodiment, the electric power supplying path 123 does not extend via all of the interlock switches, and therefore the motor 131 can be operated irrespective of the open or closed state of all of the doors.
Further, in the case of this embodiment, with the opening of the openable door 25, the motor 131 is driven to eliminate the pressure application at the nip N. Particularly, in this embodiment, in the case where any of the doors of the plurality of the doors including the openable door 25 is opened, the pressure application at the nip N is eliminated. For this reason, all of the doors are provided with sensors 140 (
On the other hand, as shown in
[Driving Path of Fixing Device]
Here, as shown in
Accordingly, in the case where the recording material is fed to the nip N and the toner image on the recording material is heated, the controller 141 switches the path to a path for transmitting the power of the motor 131 to the opposite roller 102. On the other hand, in the case where the pressure elimination of the nip N is made, the controller 141 switches the path to a path for transmitting the power of the motor 131 to the cam 103a.
In this way, the driving gears 132, of the fixing driving portion 130, provided in the apparatus main assembly 24 are, as shown in
As described above, in the state in which the fixing device 100 is mounted in the apparatus main assembly 24, even when the openable door 25 is opened, the electric power is supplied to the motor 131, and therefore a state in which the motor 131 is driven and the driving gears 132 are rotatable is formed. Accordingly, by providing the protective wall portion 110 as described above, even when the operator opens the openable door 25 during jam clearance or during exchange (replacement) of the fixing device 100, the operator is prevented from touching the driving gears 132.
On the other hand, in the case where the fixing device 100 is demounted from the apparatus main assembly 24, as shown in
In the case of this thus constituted embodiment, irrespective of the opening and the closing of the openable door 25, the electric power is supplied from the power source 120 to the motor 131. For this reason, although the openable door 25 is in the open state, the pressure eliminating mechanism 103 can be driven by the motor 131. By doing so, for example, even in the case where the openable door 25 is opened during a printing operation and an operation of the image forming apparatus 100 stops partway and the (printing) operation stops in a state in which the recording material is nipped in the nip N, the pressure elimination of the nip N can be performed (the pressure at the nip N during the fixing is eliminated or reduced) by driving the motor 131. As a result of this, an operating force for removing the recording material remaining in the nip N can be made small, so that it is possible to prevent impartment of damage to the fixing device 100 in a state in which the recording material is torn and left in the main assembly or the fixing device 100 is pulled by the recording material to be removed.
Further, in the case of this embodiment, the electric power supplying path 123 extends via the inside of the fixing device 100, and therefore in the case where the fixing device 100 is demounted from the apparatus main assembly 24, the electric power supply to the motor 131 is interrupted. For this reason, even when the driving portion such as the driving gears 132 is exposed by demounting the fixing device 100 from the apparatus main assembly 24, the driving portion is not driven.
In the above-described embodiment, as the fixing device, the case where a constitution of the film heating type is used was described, but the present invention is not limited to such a film fixing type fixing device, and for example, is applicable to also a fixing device using another constitution such as a roller or a belt.
Further, the motor 131 as the driving source has a constitution, in the above-described embodiment, in which both of the pressure eliminating mechanism 103 and the opposite roller 102 are driven, but may only be required to drive at least the pressure eliminating mechanism 103. In the case where only the pressure eliminating mechanism 103 is driven by the motor 131, the opposite roller 102 is to be driven by another driving source, but the electric power supply to this driving source may also be effected without going through the inside of the fixing device as in the electric power supplying path 123. That is, the driving source for feeding the recording material at the nip may also be constituted so that the electric power supply is interrupted when the openable door is opened. Further, in the above, an example in which the fixing device (feeding unit) is provided with a by-pass like electric power supplying path was described, but the present invention is not limited thereto, and a similar constitution (in which the by-pass like electric power supplying path is provided) may also be applied to the recording material feeding portion 12. Specifically, with respect to a rotatable member pair, for nipping and feeding the recording material, provided in the recording material feeding portion 12 as the feeding unit, when the openable door for permitting access to the recording material feeding portion 12 is opened, as long as the recording material feeding portion 12 is mounted in the image forming apparatus, the recording material feeding portion 12 can be driven by the driving source.
According to the present invention, an image forming apparatus, in which even when an access door is opened during image formation, electric power supply to a necessary portion is maintained, is provided.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-199176 | Sep 2013 | JP | national |
| 2014-181876 | Sep 2014 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 9201367 | Miyake | Dec 2015 | B2 |
| 20060115291 | Chung | Jun 2006 | A1 |
| 20070140710 | Okano | Jun 2007 | A1 |
| 20090232550 | Obata | Sep 2009 | A1 |
| 20100329729 | Koshida | Dec 2010 | A1 |
| 20140369709 | Nakano | Dec 2014 | A1 |
| 20150093124 | Miyake | Apr 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 0493874 | Mar 1992 | JP |
| 04156560 | May 1992 | JP |
| 0916030 | Jan 1997 | JP |
| 2000134787 | May 2000 | JP |
| 2013164610 | Aug 2013 | JP |
| 2013257413 | Dec 2013 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20160202650 A1 | Jul 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2014/076340 | Sep 2014 | US |
| Child | 15078227 | US |
