Incremental printing of symbolic information – Ink jet – Medium and processing means
Utility Patent
1996-10-18
2001-01-02
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C271S119000, C271S264000
Utility Patent
active
06168270
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording apparatus for letters, characters, images, and so on on a recording medium.
2. Related Background Art
FIG. 16
shows an example of a conventional recording apparatus, which comprises a sheet supply unit
210
for picking up recording sheets P, a conveyer unit
220
for conveying the recording sheets P from the sheet supply unit
210
, a recording unit
230
for processing, for example printing, the recording sheets P conveyed by the conveyer unit
220
, a sheet discharging unit
240
for discharging the processed recording sheets P, and a control device
250
for controlling sheet feed, conveyance and discharging.
More specifically, the control device
250
energizes a motor
251
to rotate a convey roller
221
and a pinch roller
222
of the conveyer unit
220
. Then, torque is transmitted through a gear train
260
consisting of gears
261
,
262
,
263
and
264
to a sheet supply roller
211
of the sheet supply unit
210
. On the surface of the sheet supply roller
211
, a semi-circular rubber roller
212
is provided, which stands still with a clearance A between itself and the recording sheet P after the sheet supply roller
211
makes one rotation. Every time the sheet supply roller
211
makes one rotation, one recording medium on top of the stack of the recording sheets set in a base
213
is frictionally picked up by the rubber roller
212
, led through the clearance A to be inserted between upper and lower guides
214
and
215
, and positioned between a recording head
231
and a platen
232
of the recording unit
230
by the convey roller
221
.
The recording head
231
processes, for example, prints line by line, the recording sheet P which is being conveyed by the convey roller
221
. After processing is finished, discharging rollers
241
and spurs
243
of the sheet discharging unit
240
discharge the recording sheet P onto a tray
244
.
Now, the above-mentioned conveyance operation which is controlled by the control device
250
using a sheet sensor
252
will be described with reference to the flowchart of FIG.
17
.
First, when a conveyance command is applied to the control device
250
(step S
1
), the control device judges whether the sheet sensor
252
is turned on or off (step S
2
). If the sheet sensor is judged to be turned on, the control device
250
energizes the motor
251
and rotate the convey roller
221
at normal speed in order to feed the recording sheet P toward the recording unit
230
(step S
3
).
On the other hand, if the sheet sensor
252
is judged to be turned off in step S
2
, it means that the apparatus is in the initial state, where the recording sheet P does not exist between the upper guide
214
and the lower guide
215
.
In this way, the conventional recording apparatus detects the recording sheet P by the sheet sensor
252
and drives the convey roller
221
at a predetermined normal speed when the recording sheet P is detected. After processing, for example, printing, the recording sheet P conveyed as described above is discharged onto the tray
244
by the discharging rollers
241
whose entire surfaces are covered with highly frictional material
242
.
In this conventional apparatus, however, if the recording sheet P is present in the conveyer unit
220
, the convey roller
221
is always driven at the predetermined normal speed regardless of the stand still postures of the sheet supply roller
211
. Therefore in case the sheet supply roller
211
is in an abnormal stand still posture as shown in
FIG. 18
, where the round part of the rubber roller
212
is in contact with the rear portion of the recording sheet P, the recording sheet P to be conveyed receives the load from the rubber roller
212
. Accordingly, conveyance failure may occur because the torque to rotate the convey roller
221
at normal speed is not sufficient to convey the recording sheet P.
To make provision for said case, the torque to drive the convey roller
221
may be increased. To do this, however, the rotating speed, that is, the conveyance speed of the recording sheet P has to be reduced, which deteriorates the performance of the recording apparatus.
In addition, in the conventional apparatus, since the entire surface of the discharging rollers
241
are covered with highly frictional material
242
such as rubber, the manufacturing cost of the apparatus is increased and assembly is not easy.
Further, in case where so many recording sheets P are discharged that the difference in level between an exit
242
and the discharged recording sheets P stacked on the tray
244
disappears, the fall for the recording sheet P to be newly discharged can not be obtained. In this case, the newly discharged recording sheet P is hampered by the frictional force and the electrostatic force of the recording sheets P previously ejected on the tray
244
, and it is hard to completely eject only by the highly frictional material
242
such as rubber.
SUMMARY OF THE INVENTION
The present invention is made in order to solve the above-mentioned problems in the prior art. The object of the present invention is to provide a recording apparatus which can reliably convey the recording medium even the rotary sheet feed body gives a load to the recording medium, and which can reliably discharge the recording medium.
REFERENCES:
patent: 3737158 (1973-06-01), Beery et al.
patent: 3764050 (1973-10-01), Clark
patent: 4437656 (1984-03-01), Onoda et al.
patent: 4723129 (1988-02-01), Endo et al.
patent: 4753433 (1988-06-01), Rod et al.
patent: 4888602 (1989-12-01), Watanabe
patent: 5046947 (1991-09-01), Endoh et al.
patent: 5191382 (1993-03-01), Okamura et al.
patent: 5335043 (1994-08-01), Kluger et al.
patent: 5372359 (1994-12-01), Miura et al.
patent: 58-157654 (1983-09-01), None
Hiramatsu Soichi
Kawakami Hideaki
Kinoshita Hiroyuki
Nojima Takashi
Saikawa Satoshi
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hallacher Craig
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