Typewriting machines – Sheet or web – Including friction-feed means
Reexamination Certificate
1999-08-23
2002-05-07
Eickholt, Eugene (Department: 2854)
Typewriting machines
Sheet or web
Including friction-feed means
C347S104000, C271S209000, C400S625000
Reexamination Certificate
active
06382857
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bearing mechanism for holding a shaft, a conveying apparatus in which such a bearing mechanism is applied to a conveying portion, and a recording apparatus in which such a conveying apparatus is used to convey a recording medium and an image is formed on the recording medium by a recording head.
2. Related Background Art
Recording apparatuses having a function as a printer, a copying machine or a facsimile, or recording apparatuses used as output devices for composite electronic equipments including a computer or a word processor or as output devices for work stations are designed that an image is on a sheet to be recorded (recording medium) such as a paper sheet or a plastic thin sheet based on image information.
Such recording apparatuses can be divided into an ink jet system, a wire dot system, a thermal system, a laser beam system and the like, in dependence upon a recording style.
In a serial type recording apparatus having a serial scanning system in which main scanning is effected along a direction transverse to a conveying direction (sub-scanning direction) of the sheet to be recorded, the entire image is recorded by recording means mounted on a carriage movable along the sheet to be recorded, by repeating one-line recording effected by the main scanning and a predetermined amount sheet feeding (pitch conveyance) alternately.
Among the above-mentioned recording apparatuses, the recording apparatus of ink jet type (ink jet recording apparatus) is designed to effecting the recording by discharging ink from recording means (a recording head) onto the sheet to be recorded. This recording apparatus has advantages that the recording means can easily be made compact, a fine image can be recorded at a high speed, the recording can be effected on a plain paper without special treatment, a running cost is inexpensive, noise can be suppressed due to non-impact recording and a color image can easily be recorded by using multi color inks.
Now, conveying means of a recording apparatus according to an earlier technology will be described with reference to
FIGS. 13
to
18
.
FIG. 13
is a front view of such a recording apparatus and
FIG. 14
is a sectional view of the recording apparatus.
A sheet feeding portion
503
is attached to a chassis
508
formed by bending a metal sheet. The sheet feeding portion
503
includes a conveying roller
536
for conveying a sheet P′ and a PE sensor (sheet end detecting device)
532
.
The conveying roller
536
is constituted by wounding an elastic material such as rubber around a surface of a metal shaft and is attached to the chassis
508
by mounting both ends of the metal shaft within conductive bearings
538
,
539
. A conveying roller tension spring
681
is disposed between the bearing
538
and the conveying roller
536
to apply load to the conveying roller
536
on rotating thereby to provide stable conveyance. Namely, by biasing the conveying roller
536
through the spring
681
, predetermined load is applied.
The conveying roller
536
is attached as follows. First of all, one end of the metal shaft of the conveying roller
536
is inserted into the bearing
539
and then is attached to the chassis
508
. Then, the other end of the metal shaft of the conveying roller
536
is passed through a cut out portion of the chassis
508
. Then, the conveying roller tension spring
681
is attached and the bearing
538
is fitted into the chassis
508
while inserting the bearing
538
onto the shaft of the conveying roller
536
from outside. In this case, a pawl portion
686
of the bearing
538
enters into a groove portion
661
formed in the conveying roller
536
, so that the conveying roller
536
is secured to the chassis
508
. An assembled condition is shown in FIG.
15
B.
A plurality of driven pinch rollers
537
abut against the conveying roller
536
. The pinch rollers
537
are held by a pinch roller guide
530
pivotally mounted on a shaft
530
a
and are biased by a pinch roller spring
531
to urge the pinch rollers
537
against the conveying roller
536
, thereby providing a conveying force for the sheet P′.
The pinch rollers
537
are arranged so that they do not cover the entire area of the sheet P′ but divided to hold only predetermined ranges of the sheet. In this case, the rotation shaft
530
a
of the pinch roller guide
530
is attached to bearings of an upper guide
533
for rotation.
Further, an inlet of the sheet feeding portion
503
to which the sheet P′ is conveyed is provided with the upper guide
533
and a platen
534
which guide the sheet P′. The upper guide
533
is provided with a PE sensor lever
535
for transmitting detection of leading and trailing ends of the sheet P′ to the PE sensor
532
.
The platen
534
is positioned by a bearing portion
642
fitted and slidable on the conveying roller
536
to be attached to the chassis
508
, and an attachment shaft
643
directly attached to the chassis
508
. Further, a sheet holding-down portion
544
for conveying a side edge of the sheet P′ is provided at a sheet reference side of the platen
534
.
With this arrangement, even if the side edge of the sheet P′ is deformed or curled, the side edge of the sheet is prevented from floating to interfere with a carriage
550
or the recording head
507
.
The recording head
507
for forming an image based on image information is disposed at a downstream side of the conveying roller
536
in a conveying direction of the sheet P′.
In the above-mentioned arrangement, the sheet P′ fed to the sheet feeding portion
503
is guided by the platen
534
, pinch roller guide
530
and upper guide
533
to be sent to a pair of rollers (conveying roller
536
and pinch rollers
537
).
In this case, the PE sensor lever
535
detects the leading end of the sheet P′ being conveyed, thereby determining a printing position of the sheet P′. Further, the sheet P′ is conveyed on the platen
534
by rotating the pair of rollers
536
,
537
by an LF motor (not shown).
Incidentally, the recording head
507
is an easy exchangeable ink jet recording head integrally formed with an ink tank. In this recording head
507
, heat can be applied to ink by a heater or the like.
The ink is film-boiled by the heat to cause growth and contraction of a bubble to generate a change in pressure by which the ink is discharged from a nozzle
570
of the recording head
507
, thereby forming the image on the sheet P′.
In a sheet discharging portion
504
, a transmitting roller
540
abuts against the conveying roller
536
and further abuts against a sheet discharging roller
541
. Accordingly, a driving force of the conveying roller
536
is transmitted to the sheet discharging roller
541
through the transmitting roller
540
. Further, a spur roller
542
abuts against the sheet discharging roller
541
to be driven by rotation of the sheet discharging roller
541
.
The spur roller
542
is attached to a spur stay
641
of integral type provided on the platen
534
.
By providing the spur stay
641
integral with the platen
534
in this way, since dimensions of the spur roller
542
and the sheet discharging roller
541
can be controlled within the same part, a dimensional relationship can be kept stably.
Further, the spur stay
641
has a partially cut-away portion
641
a.
When the head
507
is exchanged, the carriage
550
is moved up to the cut-away portion
641
a
to create a space through which a hook lever
553
for mounting and dismounting the head
507
can be manipulated.
With the above-mentioned arrangement, the sheet P′ on which the image was formed in a carriage portion
505
is pinched by a nip between the sheet discharging roller
541
and the spur roller
542
to be conveyed and discharged onto a sheet discharging tray (not shown).
However, the above-mentioned technique has the following problems.
In the attachment of the conveying roller
536
to the cha
Sonoda Shinya
Tanaka Hiroyuki
Yanagi Haruyuki
Canon Kabushiki Kaisha
Eickholt Eugene
Fitzpatrick ,Cella, Harper & Scinto
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