Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-06-01
2004-02-10
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S019000, C347S058000, C347S065000
Reexamination Certificate
active
06688729
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head adapted to discharge desired liquid based on the generation of bubbles, which occurs by applying thermal energy to the liquid, a liquid discharge head substrate used therefor, a manufacturing method of the liquid discharge head, a driving method of the same, and a liquid discharge apparatus equipped with the liquid discharge head. More specifically, the invention relates to a liquid discharge head having a function element made of a ferroelectric material, a liquid discharge head substrate used therefor, a manufacturing method of the liquid discharge head, a driving method of the same, and a liquid discharge apparatus equipped with the liquid discharge head.
The invention can be applied to an apparatus such as a printer, a copying machine, a facsimile having a communication system, a word processor having a printer section or the like, which is provided to perform recording on a recording medium made of paper, a string, a fiber, cloth, metal, plastic, glass, wood, ceramic or the like, and also to an industrial liquid discharge apparatus compositely combined with various processors.
In the invention, “recording” means not only the impartation of a significant image such as a character, a graph or the like to the recording medium but also the impartation of an insignificant image such as a pattern or the like thereto.
2. Related Background Art
An ink-jet recording method has conventionally been known, which performs image formation by applying energy of heat or the like to ink to cause a state change accompanied by a steep volume change of ink (generation of bubbles), discharging the ink from a discharge port by an operation force generated because of the state change, and then depositing the ink on the recording medium. As disclosed in publications such as U.S. Pat. No. 4,723,129, a recording apparatus using such a recording method typically comprises a discharge port for discharging ink, an ink flow passage communicated with the discharge port, and an electric thermal converter arranged in the ink flow passage as energy generating means to discharge ink. The recording apparatus of this kind is advantageous in that it is possible to record a high-quality image at a high speed and with low noise, in that it is possible to provide a compact and high-resolution recording apparatus, and in many other respects. Therefore, the use of such recording apparatus has become widespread in recent years, e.g., in office equipment such as a printer, a copying machine, a facsimile or the like, and even in an industrial system such as a textile printing machine or the like.
FIG. 1
shows a constitutional example of a recording head. As illustrated in
FIG. 1
, the liquid discharge head includes an element substrate
1
having a plurality of heaters
2
(only one is shown in
FIG. 1
) provided in parallel to apply thermal energy to liquid for generating bubbles, a top board
3
joined above the element substrate
1
, and an orifice plate
4
joined to the front end surfaces of the element substrate
1
and the top board
3
. The top board
3
has grooves, each of which is formed in a position corresponding to each heater
2
. By joining the element substrate
1
and the top board
3
, a liquid flow passage
7
is formed corresponding to each heater
2
.
The element substrate
1
is prepared by forming a silicon oxide film or a silicon nitride film on a substrate of silicon or the like for the purpose of insulation or heat accumulation, and patterning an electric resistance layer and a wiring constituting the heater
2
thereon. The heater
2
is caused to generate heat by applying a voltage from the wiring to the electric resistance layer, and supplying a current to the electric resistance layer. On the wiring and the electric resistance layer, a protective film is formed to protect these portions from ink. Further on the protective film, a cavitation resistance film is formed to provide protection from cavitation caused by the disappearance of ink bubbles.
The top board
3
constitutes a plurality of liquid flow passages
7
and a common liquid chamber
8
provided to supply liquid to each liquid flow passage
7
, and a flow passage side wall
9
is integrally provided to extend from the top portion between the heaters
2
. The top board
3
is made of a silicon-based material, and can be formed by forming the patterns of the liquid flow passage
7
and the common liquid chamber
8
by means of etching, depositing a material selected from silicon nitride, silicon oxide, and so on, for the flow passage side wall
9
on the silicon substrate by a widely known film-forming method such as a CVD method or the like, and then subjecting the portion of the liquid flow passage
7
to etching.
The orifice plate
4
has a plurality of discharge ports
5
formed corresponding to the respective liquid flow passages
7
and respectively communicated with the common liquid chamber
8
via the liquid flow passages
7
. The orifice plate
4
is also made of a silicon-based material, and formed by, for example shaving the silicon substrate having the discharge ports
5
to have a thickness set in the range of 10 to 150 &mgr;m. The orifice plate
4
is not always a necessary element for the invention. Thus, in place of the orifice plate
4
, it is possible to provide a top board equipped with discharge ports by leaving a wall equivalent to the thickness of the orifice plate
4
in the tip surface of the top board
3
when the liquid flow passage
7
is formed in the top board
3
, and forming the discharge ports in this portion.
When the heater
2
is caused to generate heat based on the foregoing arrangement, heat is applied to the liquid of a bubble generation region
10
, which faces the heater
2
located in the liquid flow passage
7
, and thereby bubbles are generated and grown on the heater
2
based on a film boiling phenomenon. The propagation of a pressure and the growth of the bubbles themselves based on the generation of bubbles are guided to the discharge port
5
side, and discharge from the discharge ports
5
.
On the other hand, when the bubbles enter the process of disappearance, in order to compensate for the reduced volume of the bubbles in the bubble generation region
10
and for the volume of the discharged liquid, liquid is caused to flow in from an upstream side, i.e., the common liquid chamber
8
side, filling the liquid flow passage
7
again (refilling).
In addition, the described liquid discharge head includes a circuit and an element provided to drive the heater
2
and control such driving. The circuit and the element are arranged on the element substrate
1
and the top board
3
in a divided manner. The circuit and the element can be easily and finely formed by using a semiconductor wafer processing technology, as the element substrate
1
and the top board
3
are made of silicon materials.
In the recording apparatus using the foregoing head, as shown in
FIG. 2
, a head carriage
1001
loading the liquid discharge head and a printer body
1002
are connected to each other via a cable
1003
, and recording is performed by moving the head carriage
1001
in a subscanning direction on the recording surface of the recording medium. In the case of such a structure, a wiring for supplying a current to the electric thermal converter (heater) of the liquid discharge head inevitably becomes longer. Consequently, as described above, in the case of the liquid discharge head employing ink-jet recording of the type for driving the heater by supplying a steep current thereto, a problem of easy generation of current noises occurs because of interaction of wiring inductance. In addition, when all the nozzles of the liquid discharge head are driven, a current of several amperes flows instantaneously between the head and the body, i.e., to the cable
1003
, resulting in the parallel passage of a logic signal in the cable
1003
. Thus, a problem of current noises being carried on a signa
Imanaka Yoshiyuki
Ishinaga Hiroyuki
Kubota Masahiko
Saito Ichiro
Sugama Sadayuki
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