Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2003-01-24
2004-07-20
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S009000
Reexamination Certificate
active
06764153
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a liquid ejecting apparatus for ejecting a drop of liquid from a nozzle. In particular, this invention is related to a liquid ejecting apparatus for ejecting a plurality of drops of liquid from a nozzle wherein respective volumes of the plurality of drops of liquid may be different.
BACKGROUND OF THE INVENTION
In a ink-jetting recording apparatus such as an ink-jetting printer or an ink-jetting plotter (a kind of liquid ejecting apparatus), a recording head (head member) is caused to move in a main scanning direction, and a recording paper (a kind of printing-recording medium) is caused to move in a sub-scanning direction. In cooperation with those movements, a drop of ink can be ejected from a nozzle of the recording head onto the recording paper. Thus, an image (character) can be recorded on the recording paper. For example, the drop of ink can be ejected by causing a pressure chamber communicating with the nozzle to expand and/or contract.
The pressure chamber may be caused to expand and/or contract, for example by utilizing deformation of a piezoelectric vibrating member. In such a recording head, the piezoelectric vibrating member can be deformed based on a supplied driving-pulse in order to change a volume of the pressure chamber. When the volume of the pressure chamber is changed, a pressure of the ink in the pressure chamber may be changed. Then, the drop of ink is ejected from the nozzle.
In such a recording apparatus, a driving signal consisting of a series of a plurality of driving-pulses is generated. On the other hand, printing data (ejecting data) including level (gradation) information can be transmitted to the recording head. Then, based on the transmitted printing data, only necessary one or more driving-pulses are selected from the driving signal and supplied to the piezoelectric vibrating member. Thus, a volume of the ink ejected from the nozzle may be changed based on the level information.
In detail, for example, in an ink-jetting printer used with four level data consisting of: printing data for no recording (level information 00), printing data for a small dot (level information 01), printing data for a middle dot (level information 10) and printing data for a large dot (level information 11), respective volumes of the ink corresponding to the respective level information may be ejected.
In order to achieve the above four-level recording, for example, a driving signal shown in
FIG. 18
may be used. As shown in
FIG. 18
, the driving signal has a first pulse signal PAPS
1
arranged in a term PAT
1
, a second pulse signal PAPS
2
arranged in a term PAT
2
and a third pulse signal PAPS
3
arranged in a term PAT
3
, which are connected in a series manner. The driving signal is a pulse-row signal having a recording period PATA.
In the case, the first pulse signal PAPS
1
is adapted to function as a first driving pulse PADP
1
. The second pulse signal PAPS
2
is adapted to function as a second driving pulse PADP
2
. The third pulse signal PAPS
3
is adapted to function as a third driving pulse PADP
3
.
The first driving pulse PADP
1
, the second driving pulse PADP
2
and the third driving pulse PADP
3
have a common wave-pattern (wave form). Each of them can eject a drop of the ink alone. That is, when each of the driving pulses is supplied to the piezoelectric vibrating member, a drop of the ink, whose volume corresponds to a small dot, is ejected from the nozzle.
In the case, as shown in
FIG. 19
, a level control can be achieved by increasing or decreasing the number of the driving pulses supplied to the piezo electric vibrating member. For example, when only one driving pulse is supplied to the piezoelectric vibrating member, a small dot recording is achieved. When only two driving pulses are supplied to the piezoelectric vibrating member, a middle dot recording is achieved. When the three driving pulses are supplied to the piezoelectric vibrating member, a large dot recording is achieved.
Prior to this invention, a Japanese Patent Application No. 2001-194025 has been filed. The invention disclosed in the specification thereof relates to a technique to eject ink in order to print an image on a printing medium.
When a line drawing such as a character or an illustration is printed by means of an ink-jetting printer, bleeding of the ink may be generated at a contour portion of the line drawing. Such bleeding of the ink may be caused because the ink ejected at the line-drawing area is not fully absorbed by the printing medium and hence forms an ink pool, and then the ink of the ink pool starts to flow toward another area wherein no ink dot is to be formed.
The object of the above invention is to restrain bleeding of ink at a contour portion, in a printing apparatus that ejects drops of the ink in order to print an image.
In a printing apparatus according to the above invention, a contour is extracted, and volumes of ink for dots formed in pixels adjacent to the contour are regularly reduced. Thus, bleeding of the ink can be restrained, particularly when a text is printed on a printing paper such as a normal paper whose capacity to absorb the ink is small.
The reduction of the volumes of ink may be conducted by culling dots or by forming smaller dots.
In addition, in the invention disclosed in the Japanese Patent Application No. 2001-194025, the manner of reducing the volumes of the ink is fixed for the pixels adjacent to the contour. For example, when the driving signal shown in
FIG. 18
is used, a small dot is formed in each pixel adjacent to the contour. As shown in
FIG. 19
, the small dot is formed by selecting the central driving pulse.
Thus, for example, if a large alphabet “H” is printed, drops of the ink are ejected at edge portions as shown in FIG.
20
.
However, the inventor has found that gap lines Gin
FIG. 20
can be easily perceived by human eyes, unexpectedly. Especially, in a case wherein BK (black) ink is used, existence of the gap lines G may be desight (eyesore) extremely. In order to achieve printing with much higher quality, it may be effective to restrain the gap lines G from being generated.
SUMMARY OF THE INVENTION
The object of this invention is to solve the above problems, that is, to provide a liquid ejecting apparatus such as an ink-jet recording apparatus that can achieve an edge process to prevent bleeding of ink and that can restrain generation of a gap line perceived at an edge portion.
This invention is a liquid ejecting apparatus comprising: a head having a nozzle; a main scanning unit that causes the head member to move in a main scanning direction relatively to a recording medium; a pressure-changing unit that causes pressure of liquid in the nozzle to change; a level-data setting unit that sets a selected level data from a plurality of level data, based on each of ejecting data forming a row corresponding to a main scanning movement; a driving-signal generator that generates an ejecting-driving signal; a driving-pulse generator that generates a driving pulse based on the selected level data and the ejecting-driving signal; and a main controller that causes the pressure-changing unit to operate, based on the driving pulse; wherein the row of the ejecting data includes: ejecting-sequential data corresponding to a continuous area of level data of relatively high density, an anterior edge data preceding the continuous area, and a posterior edge data following the continuous area; the level-data setting unit is adapted to set a selected level data of relatively high density based on each of the ejecting-sequential data, to set a selected level data of relatively low density based on the anterior edge data, and to set a selected level data of relatively low density based on the posterior edge data.
According to the invention, setting of level data based on the anterior edge data and setting of level data based on the posterior edge data can be independently conducted. Thus, for example, the manner of ejecting the liquid based on the anterior edge data may be made different from
Dudding Alfred
Meier Stephen D.
Seiko Epson Corporation
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