Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-31
2003-06-24
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S061000
Reexamination Certificate
active
06582061
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head and ink jet recording apparatus for use in an ink jet printer, particularly in a bubble jet printer for utilizing a bubbling phenomenon to discharge an ink, and the like.
2. Description of the Related Art
A bubble jet recording system comprises: using a heating element to locally heat a liquid in a channel and generating a bubble; utilizing a high pressure generated during bubbling; pushing and discharging a liquid droplet from a microfine discharge port; and attaching the liquid droplet to a recording paper or another recording material to record an image. An ink jet recording head for use in recording the image by the bubble jet recording system generally includes a microfine discharge port, channel, and heating element disposed in the channel.
In order to use such ink jet recording head and record the image with a higher colorfulness, a technique of discharging the microfine liquid droplet with a high density is required. Therefore, it is basically important to form a microfine channel and heating source. Therefore, for the ink jet recording head of the bubble jet recording system, a method of utilizing simplicity of a head structure and fully using a photolithography technique to prepare a high-density head has been proposed (e.g., Japanese Patent Application Laid-Open No. 8-15629, and the like). Moreover, in order to adjust a discharge amount of liquid droplets so that microfine liquid droplets can be discharged, a heating element having a larger calorific value in a middle portion than in an end has been proposed (see Japanese Patent Application Laid-Open No. 62-201254).
As the heating element for use in the ink jet recording head, a tantalum nitride thin-film resistor with a thickness of about 0.05 &mgr;m is usually used, and liquid is bubbled by Joule heat generated during energizing of the resistor. In this resistance heating element, in order to usually prevent the surface of the resistance heating element from being damaged by cavitation, an anti-cavitation layer formed of Ta or another metal having a thickness of about 0.2 &mgr;m is disposed via SiN or another insulator having a thickness of about 0.8 &mgr;m.
Moreover, in Japanese Patent Application Laid-Open No. 64-20151, a so-called multi-nozzle ink jet recording head is disclosed in which a plurality of longitudinal and transverse wires are disposed on a substrate, a rectifier element for passing a forward current and thereby generating the heat is disposed in a plurality of intersections of the wires, and discharge ports are disposed in a matrix form. Furthermore, in Japanese Patent Application Laid-Open No. 57-36679, an ink jet recording head is disclosed in which a plurality of diodes are disposed as heating elements in the matrix form on the substrate. In the diode, heat can be generated by passing electricity in a forward direction, and electricity cannot be passed in a reverse direction.
Additionally, in Japanese Patent Application Laid-Open No. 5-185594, another ink jet recording head is disclosed. The head is constituted by disposing a diode, and an electrothermal conversion element connected to the diode and disposed as the heating element in the matrix form on a head substrate so that the electrothermal conversion element can selectively be driven, or is constituted by disposing a logic circuit constituted of a shift register portion, latch portion, and logic circuit, and the electrothermal conversion element connected to the logic circuit on the same substrate so that the electrothermal conversion element can selectively be driven.
SUMMARY OF THE INVENTION
In most of conventional ink jet recording heads, a heating element, diode, logic circuit portion, and the like are simultaneously constituted and manufactured on a silicon substrate by a semiconductor process (e.g., an ion injecting method). In the manufacturing method using such semiconductor process, when the ink jet recording head having a relatively small number of discharge ports is manufactured, a compact constitution can advantageously be manufactured in a single step. However, a so-called full multi-head has a length, for example, of 12 inches (about 30 cm), which extends over a full width of a recording paper. When a necessary element is integrally formed in such a broad range by the semiconductor process, it is difficult to use a usual silicon wafer. Therefore, when the full multi-head is manufactured using the semiconductor process, a manufacturing cost possibly increases.
Then, when a non-linear element able to be manufactured without using a conventional semiconductor process can be used to constitute the circuit for selectively driving heating elements disposed in a matrix form, a longitudinal ink jet recording head like a full multi-head can possibly be provided at a low cost.
As the nonlinear element, a metal insulator metal (MIM) element for conventional use in a liquid crystal is known. This is a nonlinear element having MIM type electrical characteristics in which a resistance value during application of a low voltage indicates a high value regardless of polarity as compared with the resistance value during application of a high voltage. When the MIM element is used in the liquid crystal, a power for generating a power density of about 1 W/m
2
is usually supplied. On the other hand, in the ink jet recording head of the bubble jet recording system, the power for generating a power density of about 0.1 GW/m
2
or more needs to be supplied to the heating element. Therefore, for use of the MIM element in selectively driving the heating element, a large amount of power which has not heretofore been supplied needs to be supplied to or via the MIM element.
When a voltage applied to the MIM element is increased, it is possible to increase the power supplied to or via the MIM element to some degree. However, the voltage applied to the MIM element having a constitution similar to the conventional constitution is increased, and then there is a fear that the MIM element is adversely affected by a strong electric field. Moreover, there is a fear that the MIM element itself is adversely affected by a temperature rise by the heat generated by the MIM element. There is a fear that the electric field or an electrical current is concentrated particularly in an edge portion or a step portion of an electrode pair of the MIM element and a remarkably high heat is locally generated. There is further fear that the MIM element is adversely affected by the locally generated heat.
An object of the present invention is to reduce an adverse effect onto the nonlinear element by the heat or the electric field generated during supply of a power for producing a large power density with respect to the nonlinear element for selectively driving heating elements disposed in a matrix form in an ink jet recording head of a bubble jet recording system.
Another object of the present invention is to use a nonlinear element in a circuit for selectively driving heating elements disposing in a matrix form so that a longitudinal ink jet head can be provided at a low cost.
To achieve the aforementioned objects, according to the present invention, there is provided an ink jet recording head comprising: heating means for generating a heat energy to be utilized for discharging an ink; and a nonlinear element for driving the heating means, having MIM type current/voltage characteristics in which a resistance value during application of a low voltage indicates a high value regardless of polarity as compared with the resistance value during application of a high voltage, wherein the nonlinear element has an electric field relaxing structure for relaxing generation of a locally strong electric field in the nonlinear element.
The nonlinear element having the MIM type electrical characteristics is used, and thereby the heating means disposed in the matrix form can selectively be driven with a relatively simple constitution in which the nonlinear element is disposed in an i
Barlow John
Brooke Michael S.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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