Patent Application
20050286946
1. Field of the Invention
This invention relates to an electrophotographic image forming apparatus, particularly, relates to a moisturizing technology which moisturizes paper fixed by a thermal fixing device.
2. Related Art
An image forming apparatus which forms images by an electrophotographic process forms an image with fine toner particles on paper and fixes the toner image by heating and pressing thereof.
When paper is heated to fix a toner image thereon, the paper loses its moisture by evaporation. When the fixed paper is exposed to a surrounding atmosphere, the paper gradually recovers moisture. However, this moisture recovery is not uniform on the paper. For example, when some sheets of paper are stacked up, the moisture absorbing rate is great near the edges of the stacked sheets but small or little in the center of the stacked sheets.
Therefore, each paper sheet has different moisture contents thereon and this difference in moisture contents causes the paper sheet to wave.
This paper waving phenomenon often takes place on the image-recorded paper sheets which are stacked on the paper-ejection tray or on the stapling stacker. Particularly, it is remarkable on paper sheets on a paper-ejection tray which consists of large-quantity stackers.
In some cases, paper sheets are curved or curled.
Patent Document 1 proposes a paper moisturizing apparatus for preventing paper curls by using a porous moisturizing roller to deliver paper, supplying water from the center of the shaft of the moisturizing roller, and moisturizing the paper.
[Patent Document 1]
With a view to the above, an object of this invention is to provide a useful recording medium moisturizing apparatus and an image forming apparatus.
A first aspect is a paper moisturizing apparatus comprising
A second aspect is a recording medium moisturizing apparatus comprising a first and second moisturizing member each of which has a porous layer, wherein a recording medium is delivered by the first and second moisturizing members and the moisturizing apparatus further comprises
A third aspect is an image forming apparatus comprising
The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, and wherein;
For a view to the above, moisturizing apparatus having the configuration below have proven useful.
A first aspect is a paper moisturizing apparatus comprising
It is preferable that the water-supplying device in the configuration is equipped with a water-supplying roller with a porous layer and supplies water to the moisturizing roller while the water-supplying roller rotates in contact with the moisturizing roller.
It is preferable that the regulating device is equipped with a regulating member which is in press-contact with the water-supplying roller and regulates the quantity of water in the water-supplying device. This configuration does not let the regulating member press the moisturizing roller and consequently can prevent deformation of the moisturizing roller.
The regulating member should preferably be able to move to touch and detach from the water-supplying roller. This configuration can prevent deformation of the water-supplying roller due to the continuous pressure to the roller by the regulating member.
Further, the regulating device can be a member which regulates the quantity of water in the moisturizing roller in press-contact with the moisturizing roller. The regulating member should be able to move to touch and detach from the moisturizing roller to prevent deformation of the moisturizing roller due to the continuous pressure to the moisturizing roller by the regulating member.
The water-supplying device may have a container to store water in which the water-supplying roller is dipped. The water-supplying device can comprise a water-supplying roller and an intermediate roller which is in contact with the water-supplying roller and at least one of the moisturizing rollers. In other words, for example, the moisturizing apparatus comprises a pair of moisturizing rollers each of which has a porous layer and forms a nip area to deliver paper, an intermediate roller which supplies water to at least one of the moisturizing rollers in contact therewith from the surface of the moisturizing roller, and a water-supplying device which supplies water to the intermediate roller. The intermediate roller can move to a position to be in contact with the moisturizing roller and the water-supplying roller and move away from at least one of the moisturizing roller and the water-supplying roller. In other words, the intermediate roller can be configured so that it can move to a position to be in contact with the moisturizing roller and the water-supplying roller and move away from at least one of the moisturizing roller and the water-supplying roller.
This configuration of the water-supplying device can exactly control supply and shut-off of water to the pair of moisturizing rollers. Therefore, this configuration can prevent excessive water supply to the moisturizing roller pair and suppress the occurrence of a problem due to excessive water supply.
For example, if water is supplied to the moisturizing roller which stopped, the excessive water will be given to the paper from the moisturizing roller when the moisturizing roller starts to rotate again. This will make the paper too wet.
In at least one of the above configurations, the moisturizing roller pair detachable to each other is one of the preferable configurations because it can prevent the deformation of the moisturizing roller.
The above configuration of the moisturizing apparatus has excellent effects in fully preventing the deformation of paper, applying uniform moisture to the whole paper, and facilitating moisture supply control. Further, this configuration can reduce the number of water-storage sections and downsize the apparatus. Naturally, the downsized configuration can be housed in the image forming apparatus easily. In summary, the first aspect of this invention is preferably applied to the image forming apparatus.
A second aspect is a recording medium moisturizing apparatus comprising a first and a second moisturizing members each of which has a porous layer, wherein a recording medium is delivered by the first and the second moisturizing members and the moisturizing apparatus further comprises
The preferable configuration of the second aspect has the same as the first aspect, and has the same advantages.
The third aspect is an image forming apparatus comprising
It is preferable that the third aspect further comprises a post-processing device which post-processes the moist paper moisturized by the moisturizing apparatus.
A phenomenon which causes paper sheets to be attached together (so-called “tacking”) takes place when paper sheets are stacked with their toner resin hardened insufficiently. The above image forming apparatus can preferably prevent such a phenomenon since the image forming apparatus can give adequate moisture to the fixed paper sheets.
In a double-sided image formation, a paper sheet loses its moisture by heat of thermal-fixing of an image on one side of the paper sheet and becomes dried and highly resistant. This dried and resistant paper sheet is fed again into the image forming section to receive another image transfer on the opposite side of the sheet. Consequently, the image on the opposite side of the paper may be deteriorated. The third aspect can preferably prevent such an unwanted phenomenon by adequately moisturizing the fixed paper to control the percentage of moisture content of the paper.
By using one or more configurations of the above, it is possible to give uniform moisture to the whole paper since water is supplied from the surface of the moisturizing roller and the quantity of supplied water is regulated exactly. Further, these configurations can improve the ability to control start and stop of operations and consequently optimize paper moisture control. This can preferably suppress paper deformations such as waves and curls and further prevent paper deformations on small-sized image forming apparatus.
This invention will be described in detail with reference to the accompanying drawings in which:
The main body of the image forming apparatus A consists of automatic document feeder 1, image scanner 2 in the upper part, and a printer section in the lower part. Paper storage sections 3 and 4 in the printer section store paper sheets P. Image forming section 5 houses photoconductive member 6 which is charged, exposed, and developed by an electrophotographic process. A toner image is formed on the photoconductive member 6, transferred onto a piece of paper P, and fixed by a fixing device 7. The fixing device 7 contains heating roller 7a which houses heat source 7c and pressing roller 7b. These rollers form a nip area to deliver paper P. The fixing device 7 melts a toner image and fixes it the paper by heating and pressing the paper while delivering it.
A sheet of paper P is supplied from the paper storage section 3 or 4, temporarily held by paper feed section 5a in the image forming section 5, and delivered therefrom to receive a toner image. The printed paper P is carried out from ejection port 13 by ejection rollers 10.
A paper delivery path consists of
There provided are three image forming modes: Single-Sided Face-Down Ejection mode, Single-Sided Face-Up Ejection mode, and Double-Sided Print mode. In the Single-Sided Face-Down Ejection mode, a paper sheet P is printed an image on one side of the paper, fixed by the fixing device 7, turned over upside down by the reversing means, and carried out to the outside by the ejection rollers 10.
In the Single-Sided Face-Up Ejection mode, a printed paper sheet P having an image on one side of the paper is carried along the delivery path 9 and carried out directly to the outside by the ejection rollers 10.
In the Double-Sided Print mode, a paper sheet P is printed an image on one side of the paper, fixed by the fixing device 7, carried downward into the reversing path 12, turned over upside down there, and fed back to the paper supply path 8.
The printed paper sheet P having an image on one side of the paper is printed another image on the opposite side of the paper, fixed by the fixing device 7, and carried out to the outside by the ejection rollers 10. Operation section 14 is provided to set print modes of the main body of the image forming apparatus A and output modes of the post-processing device C.
The paper P ejected from the main body of the image forming apparatus A is delivered to the post-processing device C via the moisturizing apparatus B. The moisturizing apparatus B will be explained later.
The post-processing device C comprises stapling section 202, shifting section 203, and intermediate stacker 204. The post-processing device C staples or shifts paper sheets and ejects them to elevating paper tray 206.
The post-processing device C further comprises stationary paper tray 205 for a small-quantity printing job. The tray 205 stacks a little amount of paper.
For stapling, a preset number of paper sheets are stacked on intermediate stacker 204 and stapled by the stapling section 202. A set of stapled paper sheets moves up above the stacker 204 and is ejected to the elevating ejection tray 206.
For a small-quantity printing job, paper sheets P fed from inlet port 201 are ejected to the stationary ejection tray 205.
When a large-quantity printing job is implemented, paper sheets P are ejected to the elevating ejection tray 206 even in a mode which does not require post-processing (stapling or shifting).
In
The moisturizing rollers 100 and 101 and the water-supplying roller 102 are driven by a motor (which is not shown in the drawing) to rotate in the arrow direction and deliver the paper P. During the delivery, the paper P is nipped by the moisturizing rollers 100 and 101 and delivered. The paper is moistened with water which exudes from the porous layers of the moisturizing rollers 100 and 101 in the nip area. The quantity of water to be applied to the paper P is adequately regulated by squeezing of the regulating member 103.
Although the regulating member 103 regulates the quantity of water to be supplied to the moisturizing roller 101 in press-contact therewith, it is possible to make the regulating member 103 to be driven to rotate by the moisturizing roller 101 or to make the regulating member 103 just press against the moisturizing roller 101 without rotating itself. The pressing force of the regulating member 103 can be determined adequately. Further, although water of the water-supplying roller 102 is supplied to the lower moisturizing roller 101, it is possible to supply water to the upper moisturizing roller 100 or to both upper and lower moisturizing rollers 100 and 101.
As the delivered paper P is adequately moistened by this regulation of water supply to the moisturizing rollers 100 and 101, it is possible to prevent various paper problems such as paper waves due to improper moistening, adhesion of stacked paper sheets due to excessive moisture, and unwanted transfer of toner to members which is in contact with the printed paper or to the succeeding paper.
The moisturizing roller 100 can be moved up to a position indicated by a dotted line. In other words, when the image forming apparatus stops, the moisturizing roller 100 retracts to the position indicated by a dotted line apart from the moisturizing roller 101. This can prevent the deformation of the moisturizing rollers 100 and 101. Similarly, when the image forming apparatus stops, the regulating member 103 is moved to the position indicated by a dotted line apart from the moisturizing roller 101. This can prevent the deformation of the moisturizing rollers 100 and 101.
It is possible to control the quantity of water to be applied to the paper P by changing the size of the nipping area between the moisturizing rollers 100 and 101, that is, the length of the nipping area along the movement of the paper P. Similarly, the quantity of water to be applied to the paper P can be controlled by changing the pressure onto the regulating member 103.
In the second embodiment, a regulating member 106 is in press-contact with the water-supplying roller 102. As the regulating member is in press-contact with the water-supplying roller 102 instead of the moisturizing roller 101 to regulate the quantity of water to be supplied to the water-supplying roller 102, the deformation of the moisturizing roller 101 can be prevented.
In the third embodiment, a regulating device comprises regulating members 103 and 106. The first regulating member 103 is made in press-contact with the moisturizing roller 101 to regulate the quantity of water in the moisturizing roller 101. Similarly, the second regulating member 106 is made in press-contact with the water-supplying roller 102 to regulate the quantity of water in the water-supplying roller 102. Using two regulating members 103 and 106 enables exact control of the quantity of water to be supplied to the paper P. With this, paper P can keep the best condition.
In the fourth embodiment, the water-supplying device comprises water-supplying roller 102 and intermediate roller 107. The intermediate roller 107 is placed between the lower moisturizing roller 101 and the water-supplying roller 102. The intermediate roller 107 works to receive water from the water-supplying roller 102 and supplies water to the moisturizing roller 101. It is preferable that the intermediate roller 107 has a porous layer thereon, but the porous layer can be substituted by a hydrophilic non-porous roller which can retain water in its surface. The intermediate roller 107 can move to a retracted position (indicated by a dotted line) which is away from the moisturizing roller 101. The intermediate roller 107 is in the service position (indicated by a solid line) when the image forming apparatus is running but retracts to the dotted position when the image forming apparatus stops. In the example of
This can prevent an uneven water supply to paper P when the stopped image forming apparatus starts again. When the image forming apparatus stops, the moisturizing roller 101 stops, too. If water is supplied to this stopped moisturizing roller 101, the quantity of water is not even on the moisturizing roller 101. This will unevenly moisten the paper P when the moisturizing roller 101 starts to rotate again. Further, when the moisturizing rollers 100 and 101 are driven to rotate without paper P, this can prevent excessive water supply to the moisturizing rollers 100 and 101 and keep the adequate water content on the rollers 100 and 101.
As explained in the first embodiment of
In this embodiment, the intermediate roller 107 is provided between the moisturizing roller 101 and water-supplying roller 102, and the regulating member 103 is in press-contact with the moisturizing roller 101 to regulate water supply to paper P. This embodiment can optimize water supply to paper P and prevent excessive water supply to the moisturizing rollers 100 and 101.
In this embodiment, the intermediate roller 107 is provided between the moisturizing roller 101 and water-supplying roller 102, and the regulating member 106 is in press-contact with the water-supplying roller 102 to regulate water supply to paper P. This embodiment can optimize water supply to paper P and prevent excessive water supply to the moisturizing rollers 100 and 101.
In this embodiment, the intermediate roller 107 is provided between the moisturizing roller 101 and water-supplying roller 102, and the regulating member 106 is in press-contact with the intermediate roller 107 to regulate water supply to paper P. This embodiment can optimize water supply to paper P and prevent excessive water supply to the moisturizing rollers 100 and 101.
It is also possible to provide the moisturizing apparatus in the downstream side of the fixing device in the image forming apparatus.
In this embodiment, the moisturizing apparatus B is provided between fixing device 7 and switching gate 16.
The switching gate 16 receives paper P from the fixing device 7 and works to guide the paper straight to ejection rollers 10 when the switching gate 16 is in the position indicated by a solid line or to guide downward when the switching gate 16 is in the position indicated by a dotted line. As already explained, in the Single-Sided Face-Down Ejection mode, the fixed paper is sent downward from the fixing device 7, turned over and moved up by the reversing rollers 17, guided to the ejection rollers 10 by the switching gate 16, and ejected to the outside. In the Single-Sided Face-Up Ejection mode, the fixed paper from the fixing device 7 is guided straight to the ejection rollers 10 by the switching gate 16 and ejected to the outside. In the Double-Sided Print mode, a paper sheet P is printed an image on one side of the paper, fixed by the fixing device 7, guided downward into the reversing path 12 by the switching gate, fed back to the image forming section 5, printed another image on the opposite side of the paper, guided straight to the ejection rollers 10 by the switching gate 16 and ejected to the outside. The switching gate 16 is driven to rotate and select a guide position (indicated by a solid or dotted line) by a solenoid (not shown in the drawing). Three guide positions are provided: a guide position to guide paper P straight to the ejection rollers 10, a guide position to guide paper P downward, and a guide position to guide the paper P from downward to the ejection rollers 10. The position indicated by a solid line is to guide paper P straight to the ejection rollers 10. The position indicated by a dotted line is to guide paper P from downward to the ejection rollers 10. The switching gate 16 in the dotted position is energized counterclockwise by a spring (not shown in the drawing) to switch between the guide position to guide paper P downward and the guide position to guide the paper P from downward to the ejection rollers 10. When running downward, the paper P pushes the switching gate 16 to open.
In the double-sided printing, this configuration passes the paper having an image on one side of the paper through the moisturizing apparatus B to moisten the paper before forming another image on the opposite side of the paper. This enables formation of images of the uniform quality on both side of the paper.
Although the above descriptions use water to moisten paper, it is possible to add other ingredients such as a surface-active agent to the water. Further, it is apparent that the rollers in the moisturizing and water-supplying device can be substituted by the other means such as endless belts and pads.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2004-184848 | Jun 2004 | JP | national |
