Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
2000-06-01
2004-01-20
Coles, Edward (Department: 2622)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S001100, C358S001500, C358S001800, C347S009000, C347S015000, C347S117000
Reexamination Certificate
active
06680785
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital printer, which prints an image obtained as a digital image data on a recording paper, and relates to a printing method of the digital printer.
2. Description of the Related Art
A digital printer receives a still picture data, which is described a gradation value of each pixel with a digital data, from a host computer or like, hereinafter called a host, and prints the still picture data line by line sequentially. Finally, a sheet of still picture is obtained on a recording paper.
In order to suppress total power capacity of a printer while printing, such a digital printer does not simultaneously conduct all printing elements per line of a printer head and prints with dividing the printing elements into several times. In other words, a number of elements to be simultaneously conducted is limited, so that necessary supply current is limited to not more than a predetermined value. Accordingly, power capacity required for a power supply section of the printer can be suppressed and is advantageous to dimensions and cost of the printer.
FIG. 9
is a block diagram of signal processing circuit in a digital printer performing divisional printing according to the prior art.
FIG. 10
is a timing chart showing behavior of each signal at a gradation number “L” according to the prior art.
Various kinds of methods of dividing printing data can be considered. A method of masking picture data transmitted to a printing head by using a data mask signal is depicted hereinafter. Further, a number of divisions is assumed to be 4 as an example.
As shown in
FIG. 9
, a host not shown retaining a picture data transmits the picture data to a signal processing circuit line by line in order. The picture data of one line is stored in a line memory
1
in accordance with a control signal of a memory controller
2
. The memory controller
2
starts on controlling to read out the picture data from the line memory
1
when the picture data of one line is stored completely, and transmits the data to a level comparator
3
pixel by pixel from a head pixel of the line to an end pixel in order. When the last pixel of the line is read out completely, the reading out operation starts once again from a head pixel of the next line data. A line data is read out repeatedly as many times as a number of printing gradations.
A gradation data from a level counter
21
is inputted to the level comparator
3
in conjunction with a pixel data read out from the line memory
1
. The level counter
21
starts on counting from a count number “0” and counts up one by one at each time when a count finish signal is inputted from a division number counter
24
in conjunction with starting on reading out a line data from the line memory
1
. The level counter
21
keeps counting up until a counting value reaches a value of printing gradation number.
The level comparator
3
compares a picture data from the line memory
1
with a level count value. In a case that a picture data value is larger than a level count value, the level comparator
3
outputs “1” (High level signal) and the pixel becomes a printing pixel at a gradation number indicated by a current level count value. In a case that a picture data value is equal to or smaller than a level count value, the level comparator outputs “0” (Low level signal) and the pixel is not a printing pixel. The output from the level comparator
3
is transmitted to a thermal head not shown through an AND gate
13
and becomes a printing data.
A count number in the division number counter
24
is reset to' “0” at each time when each gradation printing starts. The count number is counted up one by one at each period of reading out line data. Printing of the current gradation finishes when the count number is counted up from “0” to “3”, and the count number is reset to “0” when a next gradation printing starts. The count number is inputted to a data mask selecting section
23
. The division number counter
24
transmits a signal of count finish to the level counter
21
at each time when counting is completed and printing is shifted to a next gradation, and make the level counter
21
count up.
A data mask producing section
22
produces 4 data mask signals (data masks “0” through “3”), which divide the period of reading out line data into 4 equally such as data masks “0” through “3” shown in FIG.
10
. Each data mask is inputted into the data mask selecting section
23
and one data mask is selected in accordance with a count value outputted from the division number counter
24
. The selected data mask signal is inputted into the AND gate
13
in conjunction with a pixel data from the level comparator
3
.
FIG. 10
shows a case that the data mask “0” is selected in a first line data readout period.
Accordingly, a line printing is performed 4 times per each gradation. Since a different data mask is selected at each time and a picture data from the level comparator
3
is masked in the AND gate
13
, printing pixels constituting a line are divided into a plurality of pairs by a time sharing method at each gradation and transmitted to the thermal head not shown in FIG.
9
.
When a data of a first line is completely read out throughout all printing gradations, a data of one line is transferred to the thermal head completely. The memory controller
2
writes data of a second line from the host into the line memory
1
and controls on reading out the data of the second line from the line memory
1
. The signal processing circuit shown in
FIG. 9
keeps transferring a picture data from the host to the thermal head through the above mentioned signal processing. Processing picture data of one field comes to end when data of all lines are completely processed such that data of a third line, fourth line and up to a final line are repeatedly read out and wrote in according to an order of line. In a case of color printing, a color picture is obtained by printing the three primary colors of yellow, magenta and cyan repeatedly 3 times for 3 fields.
FIG. 11
shows an electrical configuration of a thermal head “SH” according to the prior art. The thermal head “SH” comprises two groups of registers, which equal to a number of line dots multiplied by 1 bit. Each register RE of a first register group
31
is corresponding to each heat generating element
35
and decides to turn on or off electricity to the heat generating element
35
by hold parameters of the register RE. The thermal head “SH” receives a serial picture data of 1 bit wide from the AND gate
13
shown in FIG.
9
and the serial picture data is sequentially accumulated in the first register group
31
constituting a shift register. When accumulation of data of one line is completed, data of the first register group
31
are transferred to a second register group
32
by a register set signal emitted from a thermal head controlling section not shown. The heat generating element
35
is turned on in response to a data value of the second register group
32
and prints a first time divisional printing. A data of next one line is written in the first register group
31
at a same time as printing the first time divisional printing. A turn-on period is controlled by a pulse width of a control signal of turn-on pulse width emitted from the thermal head controlling section not shown. A signal performed by the AND operation between a truth or falsehood value of each register in the second register group
32
and a control signal of turn-on pulse width at each AND gate
33
is inputted to a turn-on switch element
34
. In a case that an input value of the signal is truth, the heat generating element
35
is turned on.
According to the controlling method mentioned above, a division number is fixed. However, the Japanese Patent Laid-open Publication No. 62-58584 discloses the controlling method of varying a number of sections to be simultaneously turned on in response to a total number of printing pixels after dividing a line into plural sections. According to
Endo Yutaka
Nibe Toru
Shinya Tadao
Anderson Kill & Olick
Coles Edward
Lieberstein Eugene
Meller Michael N.
Park Chan
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