Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-08-06
2001-11-06
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06312108
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet head, and, more specifically, to a structure of an ink-jet head in an ink-jet recording apparatus and a method of making such an ink-jet head.
2. Description of the Related Art
On-demand-type ink-jet heads are widely known. As a result of the demand for performing printing in color, and, for high-quality printing and high-speed printing, there has been a requirement that the number of nozzles and the nozzle density of ink-jet heads be increased.
One conventional ink-jet head has a structure and operation which are simple and which achieves high ink-jet-head density. This ink-jet head has a system in which an electrostatic force is produced between a diaphragm and an electrode, the diaphragm is deformed, and a liquid is pressurized due to the restoration force of the diaphragm so that the liquid is fired. A diffused layer in a Si substrate is used as the electrode.
Japanese Laid-Open Patent Application No. 6-55732 discloses an ink-jet head in which a metal layer is formed so that the resistance of a diaphragm is reduced without reducing the resistance of a Si substrate in order to provide a driving device in the Si substrate which is integral with the diaphragm.
In such an electrostatic-type ink-jet head, ink is fired using the restoration force produced due to elasticity of the diaphragm. In this ink-jet head, the short-side-direction width of the diaphragm must be narrowed due to the increase in the nozzle density. The displacement of the diaphragm is proportional to the fourth power of the short-side length thereof. Therefore, the driving voltage must be very high in order to obtain sufficient displacement of the diaphragm. For example, in a case where the short-side length is 55 &mgr;m, the driving voltage reaches a voltage of about 150 V. When the nozzle density increases, the total number of nozzles increases. Therefore, when the cost of the driving circuit for each nozzle increases due to the increase in the driving voltage, the total cost increases greatly.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of the present invention provide an ink-jet head which includes a high-voltage-driving active device such as a MOS transistor disposed in a substrate such that little change is required to the manufacturing process of the ink-jet head, it is possible to use an inexpensive, low-voltage driving circuit, and there is no increase in the total cost of the ink-jet head.
In a structure of an ink-jet head according to preferred embodiments of the present invention, a driving circuit is not provided in a Si substrate on the side of a diaphragm, but, instead, an active driving device is manufactured so as to be integral with an electrode substrate via a semiconductor-device manufacturing technique. Accordingly, it is possible to easily manufacture the ink-jet head, and to prevent increase in the cost of the ink-jet head.
In an ink-jet head, according to prefererred embodiments of the present invention, an electrostatic force is produced between a diaphragm and an electrode, the diaphragm is thus deformed, and liquid is pressurized and fired by restoration force of the diaphragm, wherein a diffused layer on a Si substrate is used as the electrode, and an active device which acts as a driving circuit is formed in the Si substrate.
Thus, as a result of providing the active device in the electrode substrate for each nozzle, it is possible to prevent any increase in the driving voltage, which increase results from reduction in the short-side length of each diaphragm in order to achieve a high nozzle density. That is, it is possible to control the driving device, such as a MOS transistor, so as to control the diaphragm by inputting a signal to the gate using an inexpensive, low-voltage driving circuit.
In an ink-jet head, according to another preferred embodiment of the present invention, the ink-jet head is constructed such that an electrostatic force is produced between a diaphragm and an electrode, the diaphragm is thus deformed, and liquid is pressurized and fired by restoration force of the diaphragm, wherein a diffused layer in a Si substrate is used as the electrode, and the diffused layer is a part of a MOS transistor.
Thus, as a result of providing the MOS transistor for each nozzle, it is possible to prevent any increase in the driving voltage, which results from reduction in the short-side length of each diaphragm, in order to achieve a high nozzle density. That is, it is possible to control the MOS transistor so as to control the diaphragm by inputting a signal to the gate using an inexpensive, low-voltage driving circuit.
The MOS transistor for controlling a voltage applied to the electrode for driving the diaphragm and a MOS transistor for causing an electric charge to escape from the electrode may be provided for each nozzle.
As a result of providing the MOS transistor for discharging electric charge for each nozzle, it is possible to prevent reduction in the driving frequency of diaphragm.
Other elements, features, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 5055859 (1991-10-01), Wakabayashi et al.
patent: 5075250 (1991-12-01), Hawkins et al.
patent: 5157419 (1992-10-01), Matsumoto et al.
patent: 5216447 (1993-06-01), Fujita et al.
patent: 5666142 (1997-09-01), Fujita et al.
patent: 5734395 (1998-03-01), Kamisuki et al.
patent: 5850242 (1998-12-01), Asaba
patent: 6076914 (2000-06-01), Imai
patent: 3-224741 (1991-10-01), None
patent: 3-227639 (1991-10-01), None
patent: 6-55732 (1994-03-01), None
Barlow John
Greenberg & Traurig, LLP
Loper, Jr. Robert D
Ricoh & Company, Ltd.
LandOfFree
Ink-jet head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink-jet head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink-jet head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2581183