Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-09-29
2001-03-06
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06196654
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transport means for transporting a recording material and a recording apparatus having the transport means.
2. Description of the Related Art
In recording apparatus, such as a copying machine or a printer, a recording material is generally transported from a sheet feeding station, such as a cassette, through an image forming station and to a sheet eject station. In such cases, conveyance of the recording material is controlled at a predetermined timing as the recording material is led from the sheet feeding station to the image forming station, recorded with an image, and ejected. It is necessary for the transport of the recording sheet material to be precise, especially since the timing of transport from the feed of the recording material to the image recording location influences the image recording position on the recording material. Furthermore, if the conveyance speed of the recording material during image recording is not kept constant, the magnification of the image varies and the image recorded on the recording material is partially expanded and contracted. Slippages among images recorded by the different recording heads therefore occur, especially in the case of an image recording apparatus in which a plurality of image recording heads are disposed side by side. In the case of a color image recording apparatus, such phenomenon results in color slippage and color irregularity, which are critical defects for high-quality image forming. Therefore, it is necessary to precisely drive a transport means and exactly transmit the conveying force of the transport means to the recording material in order to avoid the above problems.
With the above problems in view, various kinds of transport systems have been suggested. For example, a conventional conveyor system conveys a recording material by a pair of rollers and regulates the conveying direction by a guide. Since such a conveyor system feeds the recording material out by pressure between the rollers, the conveying force thereof is strong and the conveyance is reliable and simple. However, the pair of rollers must be placed with the minimum length of a recording material to be used in mind, and such a conveyor system is unsuitable for the conveyance of, for example, postcard-sized and visiting-card-sized recording materials. Furthermore, the system cannot be used in an apparatus, such as an electrophotographic apparatus, where the system cannot be allowed to contact the recording surface of the recording material at any point between the transfer of an image on the recording material by a drum and the fixing thereof.
Another method transports a recording material by nipping and pulling the leading edge of the recording material by a gripper. In this case, once the gripper nips the recording material, the conveying force is surely strong and reliable. However, the mechanism is complicated. Furthermore, the transport system is undesirable in that it is difficult to time the nip of the leading edge of the recording material by the gripper and a mark from the gripper is made on the recording material.
A still further method uses a fan or the like to suck a recording material from the rear of an endless belt with many holes, adhere the recording material to the belt by negative pressure generated by the suction, and convey the recording material. Although this method has been used to convey the recording material prior to fixing of a toner image in electrophotography, since the conveyance is executed by only the suction from the rear, the conveying force is small. Furthermore, it is likely that the surface of the belt will be soiled since dust and toner in the apparatus are also sucked.
In order to solve the above problems, a transport device using an electrostatic suction method shown in
FIG. 1
has been suggested by the applicant of the present invention for a color ink jet recording apparatus.
The color ink jet recording apparatus will now be schematically described with reference to
FIG. 1. A
scanner station
101
reads an image from a document
103
laid on a document table
102
and converts the image into electrical signals and a printer station
201
records on a recording material
203
in accordance with the converted electrical signals. In the scanner station
101
, a document scanning unit
104
scans in the direction indicated by the arrow A and reads the image from the document
103
. Reference numerals
105
,
106
and
107
denote an exposure means, a rod array lens and an equivalent magnification color separation line sensor (color image sensor), respectively. When the lamp of the exposure means
105
is lit during the scanning by the document scanning unit
104
and document
103
is irradiated, the light reflected by document
103
is focused onto the color image sensor
107
through the rod array lens
106
, and image information on the document
103
is read for respective colors and converted into digital signals.
In the printer station
201
, a cassette
202
feeds recording sheets
203
. The feeding operation of the recording sheets
203
stored in the cassette
202
is performed by a feeding roller
202
A. The feeding roller
202
A feeds recording sheets
203
one by one from the cassette
202
and through conveying rollers
202
B. A resist roller
204
temporarily stops the recording sheets
203
at an outlet thereof and then feeds out the recording sheet
203
onto an endless belt
211
in a belt conveyer station
210
according to the document read timing. A recording head unit
220
is composed of a plurality of recording heads
221
for jetting different inks, that is, a head BK for a black ink, a head Y for a yellow ink, a head M for a magenta ink and a head C for a cyan ink. The full-line heads
221
each have an unillustrated ink jet opening disposed corresponding to the recordable width of the sheet and placed at a predetermined space from the endless belt
211
.
A recovery cap means
230
is sealed on the jetting openings of the recording heads
221
at non-recording time and recovery time from defective jetting. While a recording operation is performed by the recording head unit
220
, the recording head unit
220
and the recovery cap means
230
are maintained in the state shown in
FIG. 1
, respectively. Reference numerals
240
and
250
denote an eject station for ejecting the recorded sheet
203
after fixing, and an eject tray.
Furthermore, reference numerals
202
B,
202
C,
202
D and
202
E denote a conveying roller, a manual supply table, a supply roller and an eject roller, respectively, and reference numerals
202
F and
202
G denote platens.
The belt conveyor station
210
will now be described in detail. The endless belt
211
(referred to as a conveyor belt hereinafter) is looped between a driving roller
212
and a driven roller
213
. A charging roller
214
charges the belt
211
so as to adhere the recording sheet
203
onto the belt
211
, a cleaner member
215
is disposed on the exit side of the belt conveyor station
210
and cleans the belt
211
soiled by ink as described below, and a platen
216
is disposed at the rear of the conveyor belt
211
and opposite to the recording head unit
220
. A conductive presser member
217
for pressing the recording sheet
203
onto the belt
211
and electrically grounding the recording sheet
203
is mounted on the belt
211
on the entrance side of the belt conveyor station
210
.
FIG. 2
shows the construction of the conveyor belt
211
. Reference numeral
211
A denotes an insulating layer made of an insulating material and which forms the surface of the conveyor belt
211
. A conductive layer
211
B made of an elastic and conductive material, for example, a conductive rubber or the like, is below the insulating layer
211
A. An indented layer
211
C is attached to the inside of the conductive layer
211
B and has a repeating dent structure.
In the color ink jet recording apparatus having such a construction, the printer station
201
per
Aoki Tomohiro
Ikkatai Masatoshi
Kobayashi Tohru
Mitomi Tatsuo
Murayama Yasushi
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Gordon Raquel Yvette
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