Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-02-19
2002-02-26
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S068000, C347S072000
Reexamination Certificate
active
06350020
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet recording head and a process for making same. In particular, the invention relates to an ink-jet recording head having a body which is a laminate of green sheets made of piezoelectric material. Each of the sheets has films formed in it. At the same time that the sheets are laminated, the films are laminated to form leading electrodes integrally in the head body. The electrodes will be connected to piezoelectric actuators.
2. Description of Related Art
A conventional ink jet printer has ink jet nozzles communicating with ink passages, which can be supplied with ink from an ink supply source. Droplets of ink can be ejected from the nozzles. Printers of such a type have been popular which can be small, which can make high speed recording, and which use on-demand systems, and particularly pressure control systems or bubble control systems by means of heat.
Ink jet printers which use pressure control systems have been made practicable and proposed which use piezoelectric systems with piezoelectric ceramics or other elements.
FIGS. 14-16
of the accompanying drawings show the ink jet head
100
of a conventional ink jet printer using such piezoelectric system. The head
100
includes a body
101
, which has ink passages
111
each defined between partition walls
114
made of piezoelectric material. The passages
111
can be supplied with ink from an ink supply source through a manifold. As shown in
FIG. 16
, an electrode
112
is formed on each side surface of each partition
114
. As shown in
FIG. 14
, a drive IC
107
is formed on a printed board
119
. While a drive signal is supplied for a predetermined slight time from the drive IC
107
to the electrodes
112
on the adjoining partitions
114
associated with the passage
111
through which ink should be ejected, these partitions
114
are deformed by shearing strain in such a manner that the passage
111
enlarges in volume to be replenished with ink. When the deformed partitions
114
return to their original shape, ink is ejected from the passage
111
out through the nozzle
110
at the front end of the passage.
The head body
101
also has leading electrodes
105
formed on its top to feed the electrodes
112
of the actuators each formed for one of the passages
111
. The leading electrodes
105
are connected electrically through a flexible print circuit (FPC)
115
to terminals of the wiring pattern
116
of the drive IC
107
.
The leading electrodes
105
are exposed, and each has a width of tens of microns and a thickness of several or some microns. Therefore, when the recording head
100
is assembled, or when it is mounted on a carriage for moving it, the electrodes
105
are liable to come off the head body
101
and break.
The FPC
115
includes a number of signal conductors, which corresponds to the number of leading electrodes
105
. Therefore, the electrical connections between the FPC
115
and the electrodes
105
and between it and the terminals of the wiring pattern
116
are complicated. In order to prevent the ink ejected from the nozzles
110
from sticking to the pattern
116
and the drive IC
107
, it is preferable that the printed board
119
be protected with resin or the like. If the board
119
is thus protected, however, the heat generated in the IC
107
cannot radiate well.
Japanese Patent application Laid-Open No. 8-112895 discloses an ink jet head, which includes an actuator plate. The plate has first channels formed in it in parallel for ejecting ink. The plate also has second channels, which extend perpendicularly to the first channels and in parallel to their side walls. Each of the second channels communicates with one of the first channels. Formed on the side walls of each first channel are first electrodes, to which actuator drive voltage can be applied. Formed on the side walls of each second channel are second electrodes (ejection channel lead wires), which are connected electrically to the first electrodes.
U.S. patent application Ser. No. 08/635,655 filed Apr. 22, 1996 discloses an ink jet print head, which includes an actuator plate. A leading pattern for a driver circuit is formed on a board, which is bonded to the actuator plate. The body consisting of the board and the plate has a number of channels formed in it, some of which serve as ink chambers. The partitions between the channels function as actuators. For use as a drive electrode, a conductive film is formed on part of each side surface of each partition by oblique vapor deposition and electroplating in such a manner that it is connected electrically to the leading pattern. The film extends on both the board and the plate. Therefore, voltage can be applied directly from the driver circuit to the drive electrodes.
SUMMARY OF THE INVENTION
It is an object of the invention to form integrally in the body of an ink jet print head a plurality of leading electrodes each for connection to the electrode of a piezoelectric actuator, and thereby protect the leading electrodes.
It is another object to simplify electrical connections in an ink jet print head and the mounting of a drive IC on the head body.
It is a further object to make efficient the heat radiation from the drive IC of an ink jet print head.
In accordance with a first aspect of the invention, an ink jet print head is provided, which includes a body having nozzles. The body also has ink passages formed in it to be filled with ink. The passages each communicate with one of the nozzles. The head also includes piezoelectric actuators each for changing the volume of one of the passages to eject ink from the associated nozzle. The actuators have leading electrodes extending through the thickness of the body.
As stated above, the leading electrodes of the actuators extend through the thickness of the head body perpendicularly to the ink passages. This prevents the electrodes from being damaged or broken when the print (recording) head is assembled or mounted on a carriage. One end of each leading electrode is exposed to the outside of the head body. Therefore, a drive circuit for the actuators can be connected directly to the exposed ends of the electrodes. Consequently, the IC chip including the circuit can be mounted directly on the body. This simplifies the structure of the head, and particularly its electrical connections, and accelerates the radiation of heat from the chip through the body.
The print head may further include second leading electrodes embedded in the head body for connecting the drive circuit to an electric system outside the head. The ends of the second electrodes may be exposed to the outside of the body. In this case, one end of each second leading electrode can be connected to the actuator drive circuit, and the other can be connected to wiring for supplying the circuit with data signals, a drive voltage, etc. It is therefore possible to simplify the electrical connections between the head and an external circuit, and between the drive circuit and the external circuit.
In accordance with a second aspect of the invention, an ink jet printer is provided, which comprises a print head and a device for supplying the head with ink. The head includes a body having nozzles. The body also has ink passages formed in it to be filled with ink. The passages each communicate with one of the nozzles. The head also includes piezoelectric actuators each for changing the volume of one of the passages to eject ink from the associated nozzle. The actuators have leading electrodes extending through the thickness of the body.
As stated above, the leading electrodes of the actuators extend through the thickness of the head body. This prevents the electrodes from being damaged or broken when the print (recording) head is assembled or mounted on a carriage. It is possible to make the head compact, thereby making the printer small. It is also possible to reduce the printer trouble or failure due to wiring breakage or the like.
In accordance with a third aspect of the inventio
Barlow John
Brother Kogyo Kabushiki Kaisha
Do An H.
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