Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1999-10-21
2002-05-21
Pham, Hai (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
C347S056000, C347S061000
Reexamination Certificate
active
06390589
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a head substrate having various layer films laminated on one base substrate, and an ink jet head that utilizes this head substrate. The invention also relates to an ink jet printer that utilizes this ink jet head.
2. Related Background Art
Conventionally, there have been in practice various types of image forming apparatuses, such as a laser printer, an ink jet printer. The ink jet printer is the one that forms images by discharging ink droplets. For the method of ink droplet discharges, there is an electrothermal transducing system which is called a bubble jet type.
The ink jet printer of electrothermal transducing type is arranged to keep ink liquid in the ink retaining portion comprising the nozzles, the supply paths, and the ink reservoir, and to create bubbles by heating ink liquid with the heat generating members in each of the nozzles, and then, to discharge ink droplets from the nozzles by the application of pressure exerted by bubbling of ink liquid.
Generally, for an ink jet printer, an ink jet head, which is structured to enable the ink jet printer to operate as described above, is movably supported by a carrier mechanism to travel in the main scanning direction. Then, in a position to face the ink jet head, a print sheet is sequentially carried by a sheet carrier mechanism in the sub-scanning direction.
In this way, the position where the ink jet head discharges the ink droplets and the surface of the print sheet are made relatively movable in the main scanning direction and the sub-scanning direction, respectively, hence making it possible for the ink jet head to discharge ink droplets onto the surface of the print sheet in accordance with printing data. Therefore, the ink jet head can form on the surface of the print sheet the dot matrix images by the adhesion of ink to it.
The ink jet head is structured by the combination of a head substrate and a covering member, for example. The covering member comprises the layer films that form separation walls, and a cover substrate. The head substrate is provided with one base substrate, and on the surface of this base substrate, various layer films are formed to constitute the ink discharge mechanism and others.
This ink discharge mechanism is formed by heater members for the electrothermal transducing type or formed by piezo members (elements) for the electromechanical transducing type. For a head substrate of the kind, it is generally practiced at present to provide the driver circuit that drives the ink discharge mechanism, and the data input unit through which the printing data are supplied to the driver circuit, by the formation of various layer films on the surface of the base substrate.
Further, for the ink jet head, it is proposed to install the ROM (Read Only Memory) at present on the head substrate in order to hold the data in such a manner as to read out freely the ID (identity) codes of the head itself, and the operational properties of the ink discharge mechanism. For example, in the specification of Japanese Patent Application Laid-Open No. 3-126560, it is disclosed that an EEPROM (Electrically Erasable Programmable ROM) is installed on an ink jet head.
However, the ink jet head disclosed in the above-mentioned Patent Laid-Open Application has the EEPROM which is installed separately from the head substrate. As a result, the device structure is complicated, and the productivity of the heads is not favorable. This complicated structure impedes making the apparatus lighter and smaller. Particularly, when the size of the recording data is large, the conventional ROM chip should be useful, but if the size of the recording data is small enough, it is not necessarily advantageous to provide the ROM chip from the viewpoint of manufacture costs in some cases.
Therefore, in the specifications of Japanese Patent Application Laid-Open No. 8-177732, U.S. Pat. No. 5,504,507, U.S. Pat. No. 5,536,314, or the like, it is disclosed that the ROM having the fuse array on it is formed on the base substrate of the head substrate together with the layer films of the ink discharge mechanism and others.
In this case, when the layer films of the ink discharge mechanism and others are formed on the base substrate, the fuse array that becomes ROM is formed simultaneously at the time of the head substrate manufacture.
If this fuse array is selectively fused by the control of the logic circuit which is formed together with the fuse array at a time, it becomes possible to hold the binary data by the presence and absence of fusing, for example.
Therefore, it is unnecessary to prepare the ROM chip separately from the head substrate for the ink jet heat that utilizes the aforesaid heat substrate. Then, the structure needed for holding the various readable data freely is simplified for the enhancement of the productivity. It also becomes possible to implement making the head smaller.
For the aforesaid head substrate, it is possible to hold the various readable data of the ink jet printer freely by means of the fuse array. Then, the fuse array can be formed on the base substrate together with various layer films. For the general ink jet head, the surface of the head substrate is mostly occupied by the ink retaining unit. Therefore, as shown in
FIG. 9A
, for example, the fuse array is formed in a position that overlaps with the ink reservoir.
In
FIG. 9A
, the head substrate
101
of the ink jet head
100
has the fuse member
103
, the interlayer insulation film
104
, the fuse electrode
105
, the protection film
106
, and others are appropriately laminated in a specific configuration on the base substrate
102
. Then, on the surface of the protection film
106
, the ink reservoir
107
is formed by the separation walls (not shown) of the covering member.
In other words, ink liquid
108
faces the fuse member
103
through the protection film
106
. However, since the fuse array holds various data by means of the selective fusing of a number of fuse members
103
, a considerable amount of heat is generated inevitably when the data recording is executed.
Therefore, when the fuse member
103
is fused in order to hold various date on the fuse array of the ink jet head
100
described above, the crack
190
may occur on the interlayer insulation film
104
and the protection film
106
arranged on the upper layer due to the locally generated heat as shown in FIG.
9
B.
In this case, ink liquid
108
in the ink reservoir
107
is allowed to be permeated up to the position of the fuse member
103
. As a result, the fuse member
103
thus fused is short circuited by the presence of the ink liquid
108
or the fuse member
103
and the fuse electrodes
105
may be eroded also by the presence of the ink liquid
108
, for example.
Particularly when the fused portions of the fuse member
103
or the logic circuit for controlling the data reading drive is formed on the circumference of the fuse array, the logic circuit is also contaminated with the ink liquid
108
which has been permeated from the crack. Then, the malfunction of the fuse array or the logic circuit may take place eventually.
In order to solve a problem of the kind, it may be conceivable to laminate the protection film
106
after the data storage has been completed on the fuse array. However, if, for example, the operational properties of the ink discharge mechanism should be recorded as data on the fuse array, there is a need for fusing the fuse array after the ink jet head
100
is completed and driven.
SUMMARY OF THE INVENTION
With a view to solving the problems discussed above, the present invention is designed. It is an object of the invention to provide a head substrate which does not cause any hindrance brought about by ink liquid even when the fuse array is selectively fused. The invention is also aimed at the provision of an ink jet head that utilizes such head substrate, and an ink jet printer that utilizes such ink jet head as well.
In order to achiever these objectives, a first head su
Imanaka Yoshiyuki
Ogawa Masahiko
Saito Ichiro
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