Electrophotography – Document handling – Copy
Reexamination Certificate
2000-12-26
2002-01-15
Pendegrass, Joan (Department: 2852)
Electrophotography
Document handling
Copy
C399S067000, C399S390000
Reexamination Certificate
active
06339692
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a printing apparatus and printing method for positioning the next printing area to the image formation unit after the last printing area of the previous printing instruction has been fixed, and more particularly to a printing apparatus and printing method for reducing wrinkling of the recording medium.
2. Description of the Related Art
Printing apparatus are widely used as output devices for computers. Electronic photographic devices, which are capable of printing on the normal paper, are used as such a printing device. In recent years, with the increase in speed and capacity of host systems, electronic photographic printing devices that are capable of printing large quantities of data at high speed are desired. Therefore, electronic photographic printing devices that print on continuous paper, which can be continuously fed, are being provided.
FIG. 33
is a drawing explaining the prior art. Is shows an electronic photographic type, continuous-paper printing device. In the electronic photographic printing device, a toner image, that is developed on the photoconductive drum, is transferred to the paper, then the transferred toner image is fixed and the printing process is finished.
This electronic photographic type continuous-paper printing device is explained for a printing device that prints both surfaces of the paper. As shown in
FIG. 33
, the double-side printing device comprises: a printing unit
101
that prints the top surface of continuous paper
100
, and a printing unit
102
that prints the back surface of the continuous paper
100
. The continuous paper
100
has machine perforations on every page. The printing unit
102
for the back surface has a photoconductive drum
90
. The photoconductive drum
90
is electrically charged by a pre-charger that is not shown in the drawing, then it is exposed with the light image by an exposure device that is not shown in the drawing. By doing this, an electric latent image that corresponds to the light image is formed on the photoconductive drum
90
. And the electric latent image on this photoconductive drum
90
is developed by toners with a developing device that is not shown in this figure. And then the toner image on this photoconductive drum
90
is transferred to the continuous paper
100
by a transfer device
91
. Printing the back surface of the continuous paper
100
is performed in this way.
The top surface of the continuous paper
100
is printed in a similar manner. In other words, the printing unit
101
for the top surface also has a photoconductive drum
92
. The photoconductive drum
92
is electrically charged by a pre-charger (not shown in the drawing), and then is exposed with light image by an exposure device that is not shown in the drawing. By doing this, an electric latent image that corresponds to the light image is formed on the photoconductive drum
92
. And the electric latent image on this photoconductive drum
92
are developed by toners with a developing device not shown in this figure. And then the toner image on this photosensitive drum
92
is transferred to the continuous paper
100
by a transfer unit
93
. Printing the top surface of the continuous paper
100
is performed in this way.
Next, the toner images on both surface of the paper
100
are fixed by a fixing unit
94
. This fixing unit
94
uses various methods for fixing the toner. For example, there is a heat-roller method that moves the paper with a high-temperature heat roller and fixes the toner with heat, or there is a flash fixing method that uses a flash lamp to irradiate the paper with a high-energy light that melts and fixes the toner. This kind of electric photographic type double-side printing device for printing on continuous paper has been discloses in Japanese Unexamined published patent No. 7-77581, or Japanese Unexamined published patent No. 8-211664.
With this kind of continuous-paper printing device, the transfer position of the toner image and the fixing position are separated. Therefore, if the last printed page
110
of one printing job stops in an un-fixed state when one printing job is finished printing, the un-fixed image could be blurred due to various causes. Therefore, when a ‘Stop Printing’ command is received, it is not advisable to stop feeding paper when there are still unfixed pages.
Therefore, before printing operation is stopped, the transferred pages are fed and fixed by the fixing unit
94
. In other words, the last printed page
110
of the job is positioned in fixing unit
94
. At this time, the next page
111
after the last printed page
110
is positioned very near the fixing unit
94
. When printing starts from this state when the next printing job arrives, not the next page
111
, but a page area
2
to
3
pages later is positioned in the image forming unit
102
, so the space between the next page
111
and this page area is not printed and becomes a blank page. This is a waste of paper.
As shown by the arrows in the figure, in order to do away with this blank page, after the last printed page
110
has been fixed by the fixing unit
94
, it is proposed to feed the paper backward at the start of the next job to a position where the image forming unit
102
can transfer an image to the next page
111
.
FIG. 34
is a drawing explaining the problems with the prior art. In the fixation step such as flash-light, the flash light is flashed on the un-fixed toner, and the toner is melted by the heat and fixed. When doing this, the moisture in the paper (continuous paper)
100
is evaporated, and this dries the paper and causes it to shrink. As shown in
FIG. 34
, in the aforementioned printing operation sequence, the last page
110
of the previous printing has shrunk considerably by fixation, and the first page
111
of the next printing has not shrunk at all.
When a paper shrinkage difference occurs between these adjacent pages, since originally the paper was continuous paper with the same width, the paper with the width is pulled by the paper with the narrow width, and wrinkling in the shape of a sine curve occurs in the vertical direction. In other words, wrinkling occurs at the top of the first page
111
of the next printing.
Printing is then performed on this wrinkled starting page
111
, and when the toner image is transferred to the page by the image formation unit, not all of the page in the width direction of the paper comes in uniform contact with the photo-sensitive drum, so there is a problem in that there are areas where no toner is transferred.
Particularly, in the case of a high-speed printer (for example when printing at 8000 lines/min.), the speed at which the continuous paper is moving is fast and the transfer time is short. Therefore, there is a good chance that toner will not be transferred to the areas of no contact due to the wrinkling.
Moreover, in a double-side printing device, fixation energy is applied from both side of the paper by the fixation unit, so there is a large amount of moisture that evaporates from the paper. Therefore, there is a large amount of paper shrinkage, and it becomes easy for wrinkling to occur in the first page.
SUMMARY OF THE INVENTION
The objective of this invention is to provide a printing device and printing method for reducing the amount of wrinkling that occurs in the leading region of the record medium, and preventing poor toner transfer to this leading region.
Another objective of the invention is to provide a printing device and printing method, for reducing the amount of wrinkling that occurs in the leading region of the record medium and preventing poor toner transfer to this leading region, which is simply constructed.
A further objective of the invention is to provide a printing device and printing method for reducing the amount of wrinkling that occurs in the leading region of the record medium and preventing poor toner transfer to this leading region, in which it is possible to adjust the amount of moisture evaporation in the end region.
Still a furth
Adachi Katsumi
Fujii Daisuke
Inui Takashi
Matsuzuki Masato
Takano Yukitoshi
Armstrong Westerman Hattori McLeland & Naughton LLP
Fujitsu Limited
Pendegrass Joan
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