Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-08-01
2003-05-06
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S061000
Reexamination Certificate
active
06557975
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head applicable to a bubble jet printer that utilizes bubbling phenomenon. The invention also relates to an ink jet recording apparatus and an ink jet recording method.
2. Related Background Art
Conventionally, the recording head applicable to the bubble jet recording method is generally provided with fine discharge ports, flow paths, and heat generating elements each installed on a part of each of the flow paths. respectively. The bubble jet recording method is a recording method in which each heat generating element is used to heat liquid locally in each flow path to a high temperature so as to generate each bubble, and then, by utilization of the high pressure exerted at the time of bubbling, liquid is discharged from each of the fine discharge ports to enable liquid to adhere to a recording medium, such as recording paper sheet, for recording.
In order to record the image to be recorded more precisely and colorfully by means of the recording technology of the kind, it is necessary to adopt the related technology and technique so that extremely fine liquid droplets should be discharged in higher density. Here, then, the fundamental importance is that extremely fine flow paths should be formed together with extremely fine heat generating sources. With this in view, making the best use of the simple structure of a bubble jet recording method, the method for manufacturing a head in high density has been disclosed in the specification of Japanese Patent Laid-Open Application No. 8-15629, for example. This disclosed method effectively adopts the technologies of photolithographic process for utilization. Also, there is disclosed in the specification of Japanese Patent Laid-Open Application 62-201254, the heat generating element which provides a larger heating amount on the central portion than the heat amount on each of the end portions thereof in order to adjust the discharge amount of liquid droplets effectively. Usually, the heat generating element uses a resistive member formed by tantalum nitride thin film in a thickness of approximately 0.05 &mgr;m. Then, when this film is energized, liquid is bubbled by the application of Joule heat. A resistive heat generating element of the kind is usually provided with a cavitation proof layer formed by metal, such as Ta, in a thickness of approximately 0.2 &mgr;m, which is arranged through an insulating member, such as SiN in a thickness of approximately 0.8 &mgr;m, in order to prevent the surface of the resistive heating member from being damaged due to cavitation.
Also, in the specification of Japanese Patent Laid-Open Application No. 64-20150, a multiple nozzle ink jet recording head is disclosed, which is characterized in that there are arranged on a plurality of vertical wires and a plurality of intersecting points on a base plate, the rectifying members each allowing the forward current to flow, and each of the heat generating elements connected therewith, respectively. Also, in the specification of Japanese Patent Laid-Open Application 57-36679, there is disclosed a thermal head on which a plurality of diodes are arranged in a array to be able to generate heat by electricity charged in the forward direction.
SUMMARY OF THE INVENTION
In general, the ink jet recording head of bubble jet type uses a larger electric current than that of other type in order to generate bubbles for discharging ink. As a result, it is easier for this type of head to generate relatively large noise voltage. However, in the case of the ink jet recording head disclosed in the specification of Japanese Patent Laid-Open Application 64-20150 referred to above, current flows in the forward direction of rectifying element even for the rectifying element and heat generating element which are not driven at that time, there should occur the noise voltage or the like having unstable polarity, such as the voltage lower than the driving voltage of the heat generating element. Consequently, unwanted heating is generated by the heat generating element which is connected with such rectifying element or such heat generating element, hence making it impossible to record high quality images stably in some cases.
Also, many of the conventional ink jet recording heads are produced on condition that heat generating elements, diodes, and logic circuits are produced on a silicon substrate by means of semiconductor process (such as ion injection method). Therefore, an ink jet recording head having a relatively small number of nozzles can be made compact, and there is an advantage that the head can be produced in a simple one process. However, in the case of a multiple head, for example, a length of 12 inches is needed if the multiple head should be produced integrally in order to cover the sheet fully in the widthwise direction, for example. It is made difficult to use any usual silicon wafer, and there is a fear that the manufacturing costs become extremely high.
Under the circumstances, therefore, if the heat generating elements for BJ (bubble jet) recording use are driven in matrix by use of each of the non-linear type elements which is independent of polarity, but capable of providing the MIM type current voltage characteristics that present a higher resistive value at the application of low voltage than the resistive value at the application of high voltage, and which can be manufactured without depending on the conventional semiconductor process, such as ion injection method. There is then a possibility that an elongated ink jet recording head is manufactured with the capability of recording images in high quality stably without generating unwanted heat.
Therefore, the inventors hereof have proposed with the U.S. application Ser. No. 09/586,890 an ink jet recording head provided with the heat generating elements for BJ recording use, which can be driven in matrix using the MIM (Metal Insulator Metal) elements. For this head, the MIM elements, which are non-linear type elements, are provided corresponding to a plurality of heat generating elements for BJ recording use. However, there is a need for dealing with the concentration of electric power of approximately 0.1 GW/m
2
or more for the resistive heat generating elements of the heater portion of the recording head for BJ use. Then, the resistive heat generating elements connected in series with the MIM elements should be provided with such electric power, the supply of which has never been experienced for the products having the conventional MIM elements adopted as the non-linear type elements for use of matrix driving. There is then a fear that the efficiency of energy utilization is reduced due to the loss of electric power of the MIM elements themselves when a large electric power should be supplied to the resistive elements arranged in the form of array in high density.
Such loss of electric power of the MIM elements themselves is extremely small for the conventional products that use MIM elements like the liquid crystal or some others, and any serious problem has never been encountered in the art so far. Here, it is considered that this power loss of MIM elements themselves is a problem characteristic of the MIM elements to be used for the BJ recording that should deal with the supply of a large electric power.
Now, therefore, the present invention aims at the provision of an elongated but inexpensive ink jet recording head which is capable of preventing the energy utilization efficiency from being reduced due to the loss of electric power of non-linear type elements themselves. It also aims at the provision of an ink jet recording apparatus, as well as an ink jet recording method.
In order to achieve these objectives, an ink jet recording head of the present invention comprises a resistive heat generating element; and a non-linear type element connected to said resistive heat generating element and having MIM type current voltage characteristics presenting the resistive value thereof being higher at the tim
Barlow John
Brooke Michael S
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