Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-11-12
2001-12-11
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
C347S043000
Reexamination Certificate
active
06328401
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a printer and printing control method and, more particularly, to a printer and printing control method for performing printing using a printhead, utilizing an ink-jet printing method by discharging ink on a printing medium.
A printer for performing printing in accordance with the ink-jet printing method has a printhead, which discharges ink droplets, and an ink tank which supplies ink to the printhead.
The basic operation of the printhead is explained below with reference to FIG.
5
.
FIG. 5
is a schematic view showing a configuration of a part of an ink discharge portion of a printhead
9
.
Referring to
FIG. 5
, the printhead
9
which faces to a printing medium
1
, such as a recording paper sheet, includes a plurality of ink discharge orifices
10
formed at predetermined intervals in the vertical direction. When printing, each of the electrothermal transducers
11
(e.g., heating resistor) arranged in correspondence with the respective ink discharge orifices
10
is driven (heated by sending electric current) in accordance with inputted printing information, thereby causing ink film boiling, and consequently a bubble
12
is formed in the ink. The pressure of the formed bubble
12
causes ink to be discharged from the ink discharge orifice
10
. An ink droplet
13
A formed in the ink discharge operation adheres to the printing medium
1
, and a predetermined pattern is formed, thereby printing is performed in a dot pattern. Note that the electrothermal transducers
11
(e.g., heating resistor) are applied with a heat voltage (VH) controlled external to the printhead.
Thereafter, when the driving of the electrothermal transducers
11
is stopped, the inside of nozzles
11
A of the printhead
9
gradually cools down, and the bubble
12
disappears.
The printhead
9
is equipped with a heat driver
14
for switching on/off electric current to the electrothermal transducers
11
, a serial/parallel converter
16
for temporarily storing serially inputted printing information and converting it into parallel data, and a heat signal generator
17
for providing a heat signal to the heat driver
14
. Further, a circuit substrate of a printhead controller
29
for providing print data to the serial/parallel converter
16
in synchronization with a clock signal and providing a heat signal to the heat signal generator
17
is installed in a carriage on which the printhead
9
is mounted.
Further, in
FIG. 5
, reference numeral
10
A denotes a common liquid chamber for ink connected to the respective nozzles
11
A, and reference numeral
13
denotes a liquid channel from an ink tank to the common liquid chamber
10
A.
Next, a conventional row-column conversion will be explained with reference to FIG.
6
.
Conventionally, data transmitted from a host computer (referred to as “host” hereinafter) to a printer is divided by n bits (generally, n=8) in the direction perpendicular to the conveyance direction of the printing medium
1
as shown in FIG.
6
A. Such data is stored in a receiving buffer
25
a
provided in RAM
25
of the printer in the received order as shown in FIG.
6
B.
The nozzles of the printhead
9
are arranged in the direction parallel to the conveyance direction of the printing medium
1
. Therefore, as shown in
FIG. 6B
, when transmitting the data temporarily stored in the receiving buffer
25
a
to a print buffer
25
b,
the data is transmitted by an amount corresponding to n×N-bit addresses at predetermined intervals, thereby divided into blocks of n×n bits. Then, each block of the divided data is rotated 90 degrees in a data processor
102
. The above processing is called row-column conversion or H(honrizontal)−V(vertical) conversion (hereinafter referred to as “R-C conversion”).
Then, the R-C converted data is transmitted to the printhead
9
in corresponding to the number of nozzles of the printhead via the printhead controller
29
.
Next, a conventional smoothing processing will be explained with reference to FIG.
7
.
Recently, the resolution of a printer has been increased to improve the quality of a printed image. However, the resolution of data transmitted from a host to the printer is sometimes lower than that of the printer. In such cases, the resolution of print data may be converted to the resolution of the printer in the printer.
For instance, print data which represents a character pattern
701
as shown in
FIG. 7
with a resolution of m×m dots per unit area (8×8 dots in
702
of
FIG. 7
) is converted into a resolution of 2m×2m dots per unit area (16×16 dots in
703
of FIG.
7
). However, if the resolution conversion of the print data is simply performed as in the manner shown in
703
of
FIG. 7
, the quality of a printed image remains the same as that of the print data of the original resolution.
One purpose of representing an image in high resolution is to print smooth curves and smooth slanting lines; therefore, after a resolution of the print data is converted, the print data is further corrected in the printer as shown in
704
of
FIG. 7
so as to obtain smooth curves and smooth slanting lines. The above operation is called smoothing.
The simplest smoothing processing is to divide data in the print buffer
25
b
into blocks of i×j bits, compare them to patterns of i×j bits prestored in ROM, and apply predetermined corrections to the divided data if the divided data matches one of the patterns. Thus, in the smoothing processing, processes of comparison and correction are repeatedly performed for each of the plurality of patterns.
In the above conventional embodiment, however, when resolution conversion is performed, the print data is unconditionally subjected to smoothing processing; therefore, it takes a considerable time to perform smoothing processing, thus resulting in decreasing of throughput of the printer.
Taking into consideration that an increase in throughput of a printer is highly required as performance and processing speed of a host improve, low throughput of a printer is a considerable problem.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a printer and printing control method for improving throughput by performing efficient smoothing processing.
According to one aspect of the present invention, the foregoing object is attained by providing a printing apparatus performing printing on a printing medium using a printhead having a plurality of print elements, the apparatus comprising: scanning means for reciprocally scanning with the printhead; conveyance means for conveying the printing medium in a direction perpendicular to a scanning direction of the scanning means; input means for inputting print data of pixels arranged in the scanning direction of the scanning means; resolution conversion means for converting a resolution of the print data inputted by the input means; smoothing means for applying smoothing processing to the print data whose resolution was converted by the resolution conversion means; row-column conversion means for converting an order of the print data inputted by the input means into the direction of an arrangement of the print elements of the printhead; and control means for controlling execution of the row-column conversion means and/or the smoothing means in accordance with a content of the print data inputted by the input means.
The apparatus may further includes analysis means for analyzing in groups of a predetermined amount of the print data inputted by the input means to determine whether or not the print data causes print operation of the printhead, wherein the control means performs the control on the basis of an analyzed result by the analysis means.
The apparatus may further includes a receiving buffer for temporarily storing the print data inputted by the input means; and a print buffer for temporarily storing the print data for printing performed by the printhead, and in which case, it is preferred to have transmission means for transmitti
Kuronuma Akira
Murata Takayuki
Omo Shinichi
Umezawa Masahiko
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Le N.
Nguyen Lamson D.
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