Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-11-02
2002-11-12
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06478413
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a charging plate for liquid jet charging devices wherein a liquid filament injected through an orifice provided on an orifice member is electrostatically charged so that charged liquid droplets are formed by mechanically subdividing the liquid filament, and a method for making the same.
BACKGROUND OF THE INVENTION
This type of charging plate having a construction where a plurality of electrodes are arranged in parallel and printed on a side surface of a substrate of the charging plate is well known. Current-carrying parts for electrically connecting each of the electrodes are printed on the upper surface of the substrate.
FIG. 8
is a cross-sectional side view of assistance in explaining the construction of a liquid jet charging device having a charging plate of the conventional type (hereinafter referred to the prior art.). In the figure,
1
C denotes a charging plate for the device. The charging plate
1
C has such a construction that a plurality of electrodes
4
made of electrically conductive substance are arranged on one side surface
3
of a substrate
2
made of non-conductive substance, such as ceramics, at almost equal intervals in the depth direction (into the page in the figure) of the side surface
3
, and current-carrying parts
5
made of conductive substance are provided on an upper surface
7
of the substrate
2
as extending from the electrodes
4
individually.
Next, numeral
21
denotes an orifice member on the lower part of which an orifice
22
is provided.
The liquid jet charging device having the charging plate
1
C of the conventional type is operated in the following manner.
The pressurized liquid is continuously injected as a liquid filament
23
through an orifice on a high-frequency oscillated orifice member
21
. Liquid droplets
24
and
24
′ are generated and flown one after another as the liquid filament
23
is forcibly subdivided from the tip of the liquid filament
23
in accordance with the frequency of the high-frequency oscillation.
When a liquid inside the orifice member
21
is appropriately pressurized and vibrated at an appropriate frequency to obtain the droplets
24
and
24
′ in a stable state, the liquid filament
23
, whose length a is not more than 1 millimeter, is divided into droplets
24
and
24
′ beyond the tip thereof and flies in the air.
To cause the droplets
24
and
24
′ to be produced in an adequately charged state as the liquid filament
23
is subdivided, it is known that the electrode
4
be disposed as near as a few micrometers to ten-odd micrometers by the side of the liquid filament
23
, and in front and rear of a location where the liquid filament
23
is subdivided into the droplets
24
and
24
′ beyond the tip thereof.
Furthermore, it is also known that as a DC voltage is applied to the electrode
4
for a very short time in synchronism with the timing at which the liquid filament
23
is subdivided into droplets
24
and
24
′ from the tip thereof, an electric charge is induced for that very short time in the liquid filament corresponding to the electrode
4
, and as a result, the droplets
24
and
24
′ divided from the liquid filament
23
travel in the air in a charged state.
The conventional type of charging plate
1
C shown in
FIG. 8
, on the other hand, is given in advance appropriate roundness on the upper and lower edges
101
and
102
of one side surface
3
of the substrate
2
made of non-conductive material, as shown in the figure. An electrically conductive film is formed over an area ranging from the side surface
3
to the upper surface
7
of the substrate
2
, and then a plurality of electrodes
4
are formed on the side surface
3
of the substrate
2
and the current-carrying portions
5
extending from the electrodes
4
are formed on the upper surface
7
of the substrate by removing the conductive film from parts other than the desired electrodes
4
and current-carrying portions
5
.
The charging plate
1
C is given in advance appropriate roundness on the upper and lower edges
101
and
102
consisting of the upper surface
7
, the lower surface
6
and the side surface
3
of the substrate
2
for a machining convenience, with the radii of the roundness at the upper and lower edges being 0.5 millimeters to 1 millimeter.
Forming roundness on one edge of both the edges
101
and
102
has been particularly effective in preventing an end
111
of the current-carrying part
6
, which is formed as extending continuously from the electrode
4
formed on the side surface
3
to the upper surface
7
via the edge
101
, from being tapered off or broken off.
As an example of the prior art pertaining to the manufacturing method, a method for manufacturing a charging plate disclosed in Japanese Published Unexamined Patent Application No. Hei-9(1997)-314847 (hereinafter referred to as the prior art) is known. The prior art discloses a method for manufacturing a charging plate comprising the following five steps to form electrodes and current-carrying parts on a substrate.
That is, a charging plate is manufactured through a substrate preparation step, a step for forming electrodes made of electrically conductive material on a side surface of the substrate, a step for forming first current-carrying parts connecting ends of the electrodes on an upper surface of the substrate, a step for forming second current-carrying parts made of electrically conductive material on the upper surface of the substrate by bonding the second current-carrying parts to the first current-carrying parts, and a step for coating the upper surface of the substrate with a dielectric material.
In these steps, the electrodes and the first and second current-carrying parts are formed by screen- or stencil-printing and curing an electrically conductive paste. A method for forming the electrodes and the current-carrying parts by exposing the substrate using an electrically conductive photoresist is also disclosed.
The aforementioned charging plates for liquid jet charging device and the methods for making the same have the following problems to be solved.
In the prior art, a charging plate
1
C is manufactured by forming a film of electrically conductive material over an area ranging from the side surface
3
to the upper surface
7
of a substrate made of non-conductive material, and then forming a plurality of electrodes
4
and current-carrying parts
5
by etching and other means. This tends to cause the shape of the electrodes
4
formed on the side surface
3
to be collapsed at the distal ends thereof, resulting in irregular distal ends of the electrodes.
As a result, even when each electrode
4
is disposed facing the liquid filament
23
injected through the orifice, the distance between each electrode and the liquid filament
23
, which is critical to charge the liquid filament
23
, tends to be irregular. Furthermore, because the radius of roundness on the edge
101
of the side surface
3
of the charging plate
1
C is closely approximate to the length a of the liquid filament
23
, which is approximately 1 millimeter, each electrode
4
cannot be brought adequately close to the liquid filament
23
, making the liquid filament
23
injected through the orifice
22
unstable. This leads to some droplets
24
and
24
′ produced from the tip of the liquid filament
23
failing to be charged.
In other words, even if attempts are made to bring the charging plate
1
C close to the liquid filament
23
injected through the orifice
22
, and close to the lower surface of the orifice member
21
so as to bring the electrode
4
provided on the side surface
3
of the charging plate
1
C, the edge
101
consisting of the side surface
3
and the upper surface
7
of the charging plate
1
C having a roundness with a radius of almost the same size as the length a of the liquid filament
23
prevents the edge
111
of each electrode
4
from being placed adequately close to the liquid filament
23
even if the upper surfa
Kaneko Ryoji
Motegi Akira
McGlew and Tuttle , P.C.
Tokyo Kikai Seisakusho Ltd.
Vo Anh T. N.
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