Method and apparatus for electro-coagulation printing and...

Chemistry: electrical and wave energy – Apparatus – Electrophoretic or electro-osmotic apparatus

Reexamination Certificate

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C101SDIG029, C101SDIG029

Reexamination Certificate

active

06428671

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to methods and apparatuses for electro-coagulation printing in which electrodes are electrified to partially coagulate conductive ink films to form ink dots on surfaces of rotation drums, from which the ink dots are transferred onto papers. This invention also relates to electrode control units used for controlling the electrodes.
This application is based on Patent Application No. Hei 11-199583 filed in Japan, the content of which is incorporated herein by reference.
2. Description of the Related Art
Recently, engineers develop electro-coagulation-type printers (hereinafter, referred to as electro-coagulation printers) using conductive ink, which operate as follows:
Conductive ink films are formed on surfaces of rotation drums, which are made of metal materials. Applying electricity between the electrodes and rotation drums, conductive ink films are partially coagulated to form ink dots on the surfaces of the rotation drums, from which the ink dots are transferred onto papers to form desired print patterns (e.g., images and characters).
For example, Japanese Unexamined Patent Publication No. Hei 11-91158 discloses a fine pitch electrode unit used for the electro-coagulation printer, which will be described with reference to
FIGS. 37A
to
37
C.
FIG. 37A
shows essential parts of the electro-coagulation printer.
FIG. 37B
shows an example of ink dots being coagulated by applying electricity to electrodes.
FIG. 37C
shows an configuration of the fine pitch electrode unit containing LSI chips (or LSI circuits).
In general, the electro-coagulation printers correspond to a direct print system which does not require a printing plate. So, the electro-coagulation printers have an advantage in that a number of prints can be made uniformly and clearly at a high speed. As shown in
FIG. 37B
, electrified coagulation is effected on each of ink dots being arranged on a surface of a rotation drum
201
by applying electricity to electrodes of a fine pitch electrode unit
101
. Due to electricity being applied to prescribed electrodes which are aligned in proximity to the rotation drum
201
, ink dots are adequately condensed and solidified, while ink corresponding to other electrodes which are not electrified remain without being condensed and solidified. Then, image revealing is effected to remove the ink which is not condensed and solidified, so that an image is formed by solidified ink dots, which are transferred onto a paper (or papers). Thus, it is possible to perform high-speed printing. Because the electro-coagulation printer performs printing using ink without using the printing plate and without using photosensitive members and toner, it is possible to reduce printing cost per one sheet of print.
The fine pitch electrode unit
101
has a number of electrodes
101
a
to effect electrified coagulation with respect to ink dots. As shown in
FIG. 37B
, each of the electrodes
101
a
has a cylindrical shape whose diameter is “d”, while the electrodes
101
a
are arranged to adjoin each other with a prescribed pitch “S”. Herein, both the diameter d and the pitch S are designed to have fine dimensions which are units of micro-meters (&mgr;m).
FIG. 37C
shows an outline of the fine pitch electrode unit
101
. The fine pitch electrode unit
101
is equipped with a fine pitch electrode section
140
A including a prescribed number of fine electrodes
101
a,
which are aligned in a single line on a same plane and which are bared or exposed. A printed-circuit board
141
has the fine pitch electrode section
140
a
as one terminal end thereof. Electrode drive circuits
142
which are LSI chips or else are mounted on the printed-circuit board
141
. The printed-circuit board
141
is also equipped with connectors
143
for inputting drive commands given from the external (e.g., external system or device) with respect to the electrode drive circuits
142
. Printed wiring lines are laid on the printed-circuit board
141
and interconnect the aforementioned parts and components to enable operations independently. The fine pitch electrode unit shown in
FIG. 37C
is designed to collectively drive the prescribed number of electrodes.
Next, an example of an electrode driving method will be described with reference to
FIGS. 38A
to
38
C.
FIG. 38A
shows that thirty-two electrodes are switched over and driven respectively. Herein, every thirty-two electrodes are grouped in connection with a full print width of a dot-matrix format, for example. The thirty-two electrodes are supplied with a pulse signal (see
FIG. 38B
) consisting of pulses whose pulse widths represent gradation values. Herein, every single electrode within the thirty-two electrodes is designated by a switch
145
and is driven according to needs. The fine pitch electrode unit as a whole includes input lines, a number of which is calculated by N÷32 (where “N” denotes a total number of electrodes). Hence, those input lines are respectively connected to switches (
145
), each of which is provided for a group of thirty-two electrodes.
In the above, print information (i.e., pulse signal) is supplied to each group of thirty-two electrodes in a serial manner by which the electrodes are being driven at sequentially different timings. This causes unwanted deviations in print positions of dots as shown in FIG.
38
C.
In addition, the aforementioned fine pitch electrode unit is designed to drive the electrodes in response to analog signals. For this reason, it is difficult to adjust relationships between actual printing densities and gradation values corresponding to print data. In the case of color printing, it is difficult to adjust print positions among different colors of ink. That is the aforementioned electro-coagulation printer needs a mechanical installation accuracy to be strictly maintained among mechanical parts such that the electrodes are strictly aligned in a prescribed direction while maintaining a constant gap being formed between the electrodes and rotation drum. In other words, there is a drawback in that the conventional electro-coagulation printer cannot perform high-quality printing without strictly maintaining the mechanical installation accuracy among the mechanical parts.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method and an apparatus for electro-coagulation printing in which printing is performed with a high quality and at a high speed.
It is another object of the invention to provide an electrode control unit which is suited to the electro-coagulation printing method and apparatus.
A printing method of this invention for an electro-coagulation printer is realized by a print data reception step, a gradation data creation step, a parallel conversion step, a gradation value hold step, a parallel drive control step and an electrode drive step. Herein, the gradation data creation step creates gradation data representing gradation values for one line of pixels on the basis of the print data received by the print data reception step. The parallel conversion step receives the gradation data which are serially transferred thereto to parallel data corresponding to the gradation values with respect to one line of electrodes, which are aligned in proximity to a rotation drum having a conductive ink film on its surface. After the gradation value hold step completely holds one line of the gradation values, the parallel drive control step simultaneously outputs the gradation values in parallel to the electrode drive step to drive the electrodes respectively. Driving the electrodes, the conductive ink film is partially coagulated to form ink dots on the surface of the rotation drum, so that the ink dots are transferred onto a paper.
In the above, the gradation value can be configured using an arbitrary number of bits. If the gradation value is represented by eight bits, there are provided 256 steps of gradation. Incidentally, the gradation value can be configured by a single bit, in which digit 0 designates a blank (

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