Electrophotography – Document handling – Copy
Reexamination Certificate
1999-07-19
2001-07-10
Chen, Sophia S. (Department: 2852)
Electrophotography
Document handling
Copy
C399S406000
Reexamination Certificate
active
06259887
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus for forming images on cut sheets, a sheet humidifier for supplying moisture to cut sheets and a binding system including them.
2. Description of the Related Art
Electrophotographic image formation is generally carried out by transporting cut sheets having toner electrostatically absorbed thereon through a fuser to fuse the toner on to the sheets.
As shown in
FIG. 1
, however, the fusing of toner with a fuser results in the loss of a considerable amount of moisture included in cut sheets of paper, which reduces the sheet dimensions from initial values. Although the sheet dimensions are recovered because the sheets absorb moisture again as time passes, the fluctuation of dimensions results in various problems. For example, when dry sheets are collected and bound, the glued portion on the back of the book is fixed in a shrunk state. Although each sheet returns to the initial dimensions as a result of subsequent absorption of moisture, “wavy” distortions remain on each sheet because it is constrained by glue in the region of the back. Specifically, as shown in FIG.
2
, a book can become wavy as time passes even if it has been beautifully produced.
Further, when a cut sheet is extremely dry before an image is formed, the quality of the image formed thereon can be adversely affected.
The present invention has been conceived taking the above-described situation into consideration, and it is an object of the invention to provide an image forming apparatus, a sheet humidifier and a binding system in which cut sheets can be humidified by force.
SUMMARY OF THE INVENTION
In order to solve the above-described problems, according to the invention, there is provided a sheet humidifier comprising:
transport means for transporting a cut sheet;
at least a pair of sheet guide portions facing each other for allowing the cut sheet transported by the transport means to pass therebetween in one direction and for exposing front and rear sides of the cut sheet; and
a sprinkler provided outside the sheet guide portions for sprinkling water droplets toward one of the sheet guide portions to supply moisture to the cut sheet passing between the sheet guide portions.
According to the invention, a cut sheet subjected to a heating process passes between a pair of sheet guide portions. Since the sheet guide portions expose the front and rear sides of the cut sheet, water droplets sprinkled by the sprinkler land on the cut sheet while it passes therethrough. That is, the sheet guide portions guide the cut sheet and simultaneously maintains an area on the sheet where water droplets are to be sprinkled. This makes it possible to forcibly supply moisture to the cut sheet.
Each of the sheet guide portions may include a plurality of linear bodies disposed substantially on the same plane to allow water droplets to pass between the linear bodies. This allows a cut sheet to be easily guided and simultaneously maintains an area on the sheet where water droplets are to be sprinkled.
At least some of the linear bodies may be at an angle to the traveling direction of the cut sheet so that the intervals between the linear bodies increase with the distance traveled by the cut sheet downward.
In this case, even if the sheet is skewed, the no corner of the sheet will be caught by the linear bodies because the intervals between the linear bodies increase with the distance traveled the cut sheet downward, and the possibility of jamming or bending is thus reduced. Since the linear bodies are at an angle to the traveling direction of the sheet, regions of the sheet which have been blocked by the linear bodies from water droplets are exposed to water droplets as the sheet proceeds. This makes it possible to increase the humidified area.
The linear bodies are preferably thinner than the diameter of normal water droplets sprinkled by the sprinkler. With such thin linear bodies, the area on the cut sheet wetted by water can be increased.
Each of the sheet guide portions may include a plate member formed with a plurality of holes through which water droplets can pass. This allows a cut sheet to be easily guided and simultaneously maintains an area on the sheet where water droplets are to be sprinkled.
The intervals between the holes are preferably smaller than the diameter of the normal water droplets sprinkled by the sprinkler. Thus, the area on the cut sheet welled by water can be increased.
In the sheet humidifier,
the cut sheet may travel substantially upward;
the sheet guide portion closer to the sprinkler may be formed with an opening across which the linear bodies are stretched and provided with an edge serving as an upper end of the opening;
the edge may be tapered such that it is spaced from the linear bodies at an interval that increases as it extends downward; and
the opening may not be located directly under the edge in the vertical direction.
Therefore, when water droplets hit regions of the sheet guide portions above the opening, the water droplets drop from the edge. Since the opening is not located directly under the edge in the vertical direction, the dropping water droplets will not directly land on the sheet passing there. Thus, partial non-uniformity of the water content in the sheet is reduced to reduce the occurrence of wrinkles and breakage.
The sheet humidifier may include a water container disposed opposite to the sprinkler across a position where the cut sheet transported by the transport means passes for receiving water droplets which have been sprinkled by the sprinkler but have not hit the cut sheet. This makes it possible to prevent a great number of water droplets which have been sprinkled by the sprinkler but have not hit the cut sheet from dropping upon underlying components, which can cause problems in the components.
A cushion member may be provided which is disposed in the water container for being hit by the water droplets to suppress reflection. Such a cushion member prevents water droplets once contained in the water container from exiting through both openings. This consequently reduces the possibility of problems caused by water dropping upon underlying components. The collection of water with the water container makes it possible to achieve an improved collection ratio.
The sprinkler may be enclosed by a housing formed with a slit through which water droplets sprinkled by the sprinkler pass, and the slit may limit the range of the water droplets sprinkled by the sprinkler in the traveling direction of the cut sheet.
By limiting the range of sprinkled water droplets with the slit as described above, the area wetted by the sprinkled water droplets can be minimized to prevent wetting in unwanted regions. This consequently reduces the possibility of problems caused by water dropping upon underlying components. The collection of water with the water container makes it possible to achieve an improved collection ratio. In addition, since it is possible to prevent water droplets from being aggregated into a large droplet while they flow in such unwanted regions, this prevents a large water droplets from landing on a sheet passing thereunder. Thus, partial non-uniformity of the water content in the sheet is reduced to reduce the occurrence of wrinkles and breakage.
The housing may be provided with a port through which water droplets sprinkled by the sprinkler exit and may include an upper limit edge and a lower limit edge respectively serving as upper and lower ends of the port, and the upper limit edge does not protrude from the vertical plane on which the lower limit edge is located.
As a result, even when water droplets drop from the upper limit edge of the housing serving as the upper end of the port as a result of the action of gravity, the water droplets are received by the lower part of the housing. This reduces the possibility of problems caused by water dropping upon underlying components. The collection of water with the water container makes it possible to achieve an improved
Chen Sophia S.
Fuji 'Xerox Co., Ltd.
Oliff & Berridg,e PLC
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