Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1993-02-03
2001-12-11
Pendegrass, Joan (Department: 2852)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S043000
Reexamination Certificate
active
06328416
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ink jet recording method for a recording device equipped with a head having a plurality of nozzles corresponding to the respective ink colors of detractive color mixing of color recording to be used, for example, in color ink jet recording device.
2. Related Background Art
FIG. 1
is a schematic upper view of an example of an ink jet recording device in general,
FIG. 2
is a block diagram showing its control system.
In
FIG. 1
, numeral
1
is a platen which rotates at predetermined steps for sub-scanning during recording with a recording medium (not shown) wound therearound. Numeral
2
is a line feed motor which transmits rotation to the rotational shaft of the platen
1
through a gear
3
.
4
is an ink Jet recording head (hereinafter called “head”) mounted freely slidable on a guide bar (not shown) arranged in parallel to the platen
1
, and is provided with a plurality of discharge openings
5
for discharging ink as droplets. Numeral
6
is a belt for moving the head
5
reciprocally in the longitudinal direction of the platen
1
. Numerals
7
and
8
are pulleys arranged at the both ends of the belt
6
, and numeral
9
a carriage motor for rotating the pulley
8
.
Numeral
10
is a paper sensor for detecting the presence of a recording medium arranged in the vicinity of the surface of the platen
1
, numeral
11
an encoder sensor mounted on the head
4
, and numeral
12
a linear encoder fixedly arranged in parallel to the platen
1
and also opposed to the encoder sensor
11
. Numeral
13
is a home position sensor for detecting that the head
4
is in the home position, numeral
14
is a cap which is used when restoring poor discharge including non-discharge, numeral
15
a motor which is the driving source for progressing forward and backward the cap
14
with respect to the head, and numeral
16
a cap sensor for detecting that the cap
14
is mounted on the head
4
.
In the above constitution, when the recording medium is mounted on the platen
1
, it is detected by the paper sensor
10
to be made in a recordable state. When the recording start button is pushed the carriage is moved, and the head
4
after being set at the home position, moves following the printing format of the recording device, and permits ink droplets to fly following the recording data from the discharge openings. The head
4
is subjected to main scanning, driven by the belt
6
with the motor
9
as the driving source. Every time when one line of main scanning is completed, the motor
2
is driven to rotate the platen
1
.
For preventing clogging of the discharge openings of the head
4
, the cap
14
is covered over the head
4
periodically or if necessary. This state is detected by the cap sensor
16
, and recording actuation is intermitted by this detection. The restoration actuation comprises absorbing the ink within the nozzles from outside of the nozzles by an absorbing mechanism (not shown) communicated to the cap
14
, thereby removing foreign matters, etc. within the nozzles. By doing so, subsequent defective recording will be cancelled.
Next, the constitution of the control system shown in
FIG. 2
is to be described.
CPU
20
constitutes the main body of control, to which a group of switches
21
(arranged on the operational panel) are connected through an input and output interface (not shown), a DC servo reversing circuit
22
for driving the carriage motor
9
, a stepping motor driving circuit
23
for driving the line feed motor
2
, a head driver
24
for driving the recording head
4
based on the recording data, a group of various sensors
25
, the encoder sensor
11
and the home position sensor
13
.
In the constitution shown in
FIG. 2
, CPU
20
performs the following operational actuation corresponding to the operational input performed by the switch group
21
provided on the operational panel (not shown). More specifically, by referring to the input from the encoder sensor
11
and the home position sensor
13
, the driving control of the carriage motor
9
is conducted through the DC servo reversing circuit
22
, and also the driving control of the line feed motor
2
through the stepping motor driving circuit
23
, whereby the recording data D is output to the head driver
24
and the recording head
4
is driven with the head driver
24
. Also, control of other mechanisms is conducted corresponding to the inputs from another group of sensors
25
.
Under such constitution, recording actuation is commenced by pushing down of the print switch among the switch group
21
, and the line feed motor is driven several steps on confirmation of the presence of recording paper by the paper sensor
10
, whereby the platen
1
is rotated and the recording paper set at the recording start position. Subsequently, the carriage motor
9
is driven to move the recording head
4
in a reciprocating manner, and the line feed motor
2
is driven as synchronized therewith to deliver the recording paper line by line. During such actuation, driving signals corresponding to the recording data are applied from the head driver
24
on the recording head
4
to drive the recording head
4
, whereby ink is discharged as droplets through the discharge openings of the nozzles
5
to effect recording of letters, images, etc.
FIG. 3
is a schematic front view of the head
4
in FIG.
1
.
As shown in
FIG. 3
, four discharge openings
41
,
42
,
43
and
44
are arranged at predetermined intervals on the same line. To the openings
41
to
44
the ink of cyan (C), magenta (M), yellow (Y) and black (BK) are sequentially supplied. At the respective ink path communicated with the discharge opening energy generating members generating energy for discharging ink are mounted, which may comprise piezoelectric elements, etc. (not shown), and by applying predetermined voltages to the piezoelectric element, ink is discharged through the openings as droplets. To each of the openings
41
to
44
a pressure chamber the shape of a pipe (not shown) is individually communicated, and each pressure chamber is communicated, through a vinyl pipe, etc., to an ink tank containing the color ink corresponding to that opening.
In this case, as shown in
FIG. 4
, for the input signal, first a voltage Vrev of negative polarity is generated for a time period T1, which voltage is applied on the piezoelectric element to expand the pressure chamber. Next, a positive voltage Vop is generated for a time period T2, which is applied on the piezoelectric element to reduce the pressure chamber, thereby discharging the ink as the droplets. Further, the application voltage is gradually reduced over a time period T3, thereby effecting restoration actuation of the nozzle diameter. By setting suitably the levels of the voltages Vrev, Vop, the ink discharging amount (namely the recording dot diameter) can be varied. The minimum time interval for ink discharging is made, for example, the maximum 3 kHz of 333 &mgr;s. Full color recording can be effected by the presence of respective driving of the energy generating member provided corresponding to ink path communicated discharge openings
41
to
44
, control of the ink discharging amount, etc. Also, if the recording data D is letter data, recording of letter is also possible.
However, in such ink jet recording method of the prior art, which may be suitable for full color image by driving the energy generating member of the ink path corresponding respectively to the four colors, although printing only by black is necessary for recording of letter recording, the energy generating members in the ink path of other color are to be controlled, whereby no high speed printing could be performed. For example, in the case of performing recording one letter by 12 (dot)×7 (dot), if superfluous time other than recording is disregarded, when driven at 3 kHz, about 36 letters (3000/(12×7)=36) can be recorded per second, which however cannot be said to be high speed printing, thus not satisfying t
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Pendegrass Joan
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