Metal working – Piezoelectric device making
Patent
1996-09-25
1998-06-09
Vo, Peter
Metal working
Piezoelectric device making
298901, 347 70, 347 71, H01L 4122, B41J 2045, B41J 216
Patent
active
057617830
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ink-jet head which jets ink particles onto selected positions on an image recording medium, and a method of manufacturing the same.
BACKGROUND ART
Ink-jet printers among nonimpact printers progressively extending their market in recent years are based on the simplest principle and suitable for color printing. The so-called drop-on-demand (DOD) ink-jet printers which jets ink particles only when dots are formed are major ones among ink-jet printers.
Representative head systems for DOD ink-jet printers are, for example, a Kayser head system disclosed in JP-B No. 53-12138 and a thermal-jet head system disclosed in JP-B No. 61-59914.
A Kayser ink-jet head disclosed in JP-B No. 53-12138 is difficult to down-size, and a thermal-jet ink-jet head disclosed in JP-B No. 61-59914 has a problem that the ink burns and sticks to the ink-jet head because intense heat is applied to the ink.
An ink-jet head proposed to overcome both the foregoing disadvantages employs piezoelectric elements having a piezoelectric strain constant d.sub.33 (hereinafter referred to as "d.sub.33 mode ink-jet head").
The d.sub.33 mode ink-jet head employs thin pieces of a piezoelectric material (piezoelectric elements). Electrodes are formed on the opposite surfaces of the piezoeletric element, and the piezoelectric element is polarized in the direction of an electric field created between the electrodes so that the piezoelectric element has the piezoelectric strain constant d.sub.33. When an electric field is created across the electrodes, the piezoelectric element expands and contracts in the direction of the thickness (the d.sub.33 direction) to pressurize an ink chamber.
Known d.sub.33 mode ink-jet heads are disclosed in JP-A Nos. 3-10845 and 3-10846.
FIGS. 11 and 12 show a structure of the ink-jet head disclosed in JP-A No. 3-10846.
The ink-jet head disclosed in JP-A No. 3-10846 comprises a cover block 211 provided with two recesses, and a piezoelectric element block 213 which expands and contracts in the direction of the thickness (the d.sub.33 direction) when a voltage is applied thereto.
The piezoelectric block 213 has a layered structure. The piezoelectric block 213 is made of lead titanate zirconate. The piezoelectric block 213 is provided with grooves 216a, 216b, 216c and 216d extending perpendicularly to the paper. A portion of the piezoelectric block 213 between the grooves 216a and 216b is a first driving piezoelectric element 217a. The first driving piezoelectric element 217a is provided with a first electrode 215a. A portion of the piezoelectric block 213 between the grooves 216c and 216d is a second driving piezoelectric element 217b. The second driving piezoelectric element 217b is provided with a second electrode 215b.
The two recesses in the cover block 211 are covered with an oscillation plate 212. One of the recesses in the cover block 211 and the oscillation plate 212 define a first ink chamber 218a. The other recess in the cover block 211 and the oscillation plate 212 define a second ink chamber 218b. The first ink chamber 218a is connected to a first nozzle 219a. The second ink chamber 218b is connected to a second nozzle 219b.
In this ink-jet head, when a voltage is applied to, for example, the first electrode 215a, the first driving piezoelectric element 217a expands in the direction of the thickness (the direction d.sub.33). Consequently, the oscillation plate 212 is bent in the same direction to pressurize the first ink chamber 218a, whereby an ink particle is jetted through the first nozzle 219a.
The prior art ink-jet head disclosed in JP-A No. 3-10845 is substantially the same in principal constitution as the ink-jet head disclosed in JP-A No. 3-10845.
The foregoing prior art ink-jet head has the following problems.
As is obvious from FIGS. 11 and 12, the respective front and back surfaces of the piezoelectric block 213, and the electrodes 215a and 215b are exposed, and the open ends of the nozzles 219a and 219b are flush with the front end surface. Therefore
REFERENCES:
patent: 5128694 (1992-07-01), Kanayama
patent: 5144342 (1992-09-01), Kubota
patent: 5365645 (1994-11-01), Walker et al.
patent: 5479684 (1996-01-01), Murphy
patent: 5548894 (1996-08-01), Muto
patent: 5649346 (1997-07-01), Katsuumi et al.
Komiyama Takeo
Osawa Seiichi
Citizen Watch Co. Ltd.
Vo Peter
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